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– Today's shutdown-related media darling looks to be a new website called DrunkDialCongress.org. Its creators want you to vent some rage at a member of Congress over the shutdown, and if you're three sheets to the wind while doing so, all the better. It works like so: You call up the site, plug in your phone number, and get a call-back with a slurred automated message. "Is this government shutdown making you want to drink?" it asks. "When I drink I like to tell people what’s on my mind." After that, your call gets forwarded to the office of a random House member. The left-leaning Revolution Messaging is behind the site, but the calls go to Democrats and Republicans alike, notes MarketWatch. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Whether you are a furloughed worker, being forced to work for free, or just fed up at Capitol Hill. Call & Yell at a random Member of Congress Your phone number will be used only once to connect you to a Member of Congress. (By providing my phone number I certify that this is my phone number and I expressly authorize Creative Majority PAC to contact me using automated means of communication). ||||| Reuters Give Boehner a call… maybe. Want more alcohol in your politics? DrunkDialCongress.org is a new site that forwards calls from users to a random U.S. representative’s office, at which point they can complain about the government shutdown, or whatever else is on their mind. The site, which was put up Wednesday night, is produced by Revolution Messaging, a Washington-based mobile strategy company that works for left-left leaning politicians and causes. DrunkDialCongress, however, will forward calls to Democrats and Republicans in the House. More than 1,000 calls have already been made through the site. Ideally, members of Congress will be “saturated” with calls and reminded about the impasse’s real impact on constituents, said Keegan Goudiss, a partner at Revolution Messaging. “A lot of people are fed up with what’s going on,” Goudiss said. You don’t have to be drunk to use the site. Rather, after entering their phone number, users receive a phone call from an inebriated-sounding voice slurring: “Is this government shutdown making you want to drink?…When I drink I like to tell people what’s on my mind…” Once the automated message is complete, users are forwarded to a lawmaker’s office. Goudiss said the site was inspired by reports of lawmakers drinking even as Congress had yet to reach any agreement on spending. –Ruth Mantell Follow Ruth on Twitter @RuthMantell Follow the Capitol Report blog on Twitter @CapitolReport |
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– Kim Kardashian is now Kim Kardashian West, at least on her Twitter and Instagram accounts. The move could be a sign this marriage will last longer than 72 days, considering, as the New York Daily News points out, Kim never took the name of her last ex-hubby, Kris Humphries. The Kardashian-Wests are currently honeymooning in Ireland, E! reports, where sources say they're staying in a mansion called Castle Olivier that costs $34,000 per week. Click for more, much more, from their wedding extravaganza last weekend. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Castle Olivier has "seven four-poster bedroom suites, all unique and different from each other," says an insider, noting that the furniture was "custom made for the castle in 2007." The privately owned mansion also hosts the the largest wine cellar in Ireland, which contains some 55,000 bottles of vino! But North West's mom and dad weren't just lying around the castle and taking in the idyllic scenes around them—they were off exploring! A source tells E! News that on Tuesday at 8 a.m., Kim, Kanye and "four other people in their entourage" took off on a biking adventure with Ballyhoura Tourism. "It was a beautiful, clear morning and they saw a huge amount of wildlife," says a source. "They totally immersed themselves into what was on offer. They couldn't believe the views. It was just a totally different part of the world that they had never experienced. They were engrossed in the environment and they enjoyed being able to escape." ||||| khloekardashian via Instagram Kim Kardashian adopted the surname of new husband Kanye West on Twitter and Instagram. Kim Kardashian has gone West. The reality star updated her Twitter and Instagram accounts Wednesday to show that her full name is “Kim Kardashian West.” The name change comes just a few days after she wed Kanye West in a lavish wedding ceremony in Florence, Italy. KimKardashian via Twitter The reality star now goes by ‘Kim Kardashian West’ on her social media accounts. It seems like a good sign that Kardashian adopted her husband’s surname, considering she didn’t do so during her brief marriage to Kris Humphries. But it makes sense that she’d want to go by Mrs. West, considering her infant daughter North also has Kanye West’s last name. The name change comes just one day after Kardashian shared images from her wedding day on Instagram, and shared details about her wedding week on her blog. |
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– In a heartbreaking ending to an already tragic story, the 2-month-old giraffe whose mother trampled a US scientist and her 3-year-old son in South Africa earlier this month has died. Katy Williams and son Finn were near their home in Blyde Wildlife Estate when they surprised the mother and calf, and the mother attacked. Both giraffes were to be relocated from the wildlife reserve to another location; the mother survived the move, but the calf did not, the Times reports. "It is with the utmost sadness that we have to break the news that the 2-month-old calf unfortunately did not survive," the board of the estate said in a statement. The estate manager adds that "all necessary precautions were taken and all legal requirements were adhered to," and says everyone involved is "devastated," the New York Daily News reports. As for the Williams family, their lawyer says Katy "understands that it will take time to recover fully‚ but she has a positive attitude and she is surprising doctors with her rapid progress. She is communicating by writing words and sentences on paper‚ and she has written to ask [husband] Sam to thank everyone for their overwhelming support so far on her behalf." A GoFundMe campaign set up to raise money for medical expenses says she is also using sign language. Finn, according to the crowdfunding page, is "stable but still in critical condition, and Sam has stated that he hopes he wakes up so that they can be reunited as a family." The family's lawyer says Finn has been sedated but is beginning to wake up; the severity of his injuries will be better understood when he has regained consciousness. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | “She is communicating by writing words and sentences on paper, and she has written to ask Sam to thank everyone for their overwhelming support so far on her behalf.” ||||| The giraffe cow that seriously injured a mother and son at the Blyde Wildlife Estate in Limpopo was relocated on Tuesday but her two-month-old calf did not survive. Dr Katy Williams‚ 35‚ and three-year-old Finn‚ were injured when they were attacked by the female giraffe at the estate – where they live - outside Hoedspruit on September 3. The mother and son survived but were taken to hospital in a critical condition and underwent surgery. The family’s lawyer‚ Marina Botha from Botha & Lovegrove Incorporated‚ said on Friday that Williams' recovery was going well and her condition was improving daily. “She understands that it will take time to recover fully‚ but she has a positive attitude and she is surprising doctors with her rapid progress. She is communicating by writing words and sentences on paper‚ and she has written to … thank everyone for their overwhelming support so far on her behalf.” ||||| Katy Willams, a wildlife biologist, and her three year old son Finn were attacked by a giraffe whilst walking close to their home near Hoedspruit, South Africa, and sustained life changing injuries. They are currently both in hospital in critical condition. It will be a long and difficult recovery for both of them so this is to raise funds to help support the family throughout the process. You can find an article covering the accident here If you are based outside the UK you can still donate as normal - here are the details about payments from abroad made to the platform: "We do not charge any conversion fees, but your donors may want to check with their bank to see if they charge a currency conversion fee." |
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we describe the optical emission and the carrier dynamics of an ensemble of self - assembled gaas quantum dots embedded in gap(001 ) .
the qd formation is driven by the 3.6 @xmath0 lattice mismatch between gaas and gap in stranski - krastanow mode after deposition of more than 1.2 monolayers of gaas .
the quantum dots have an areal density between 6 and 7.6 @xmath1 per @xmath2 and multimodal size distribution .
the luminescence spectra show two peaks in the range of 1.7 and 2.1 ev .
the samples with larger quantum dots have red emission and show less thermal quenching compared to the samples with smaller qds . the large qds luminescence up to room temperature .
we attribute the high energy emission to indirect carrier recombination in the thin quantum wells or small strained quantum dots , whereas the low energy red emission is due to the direct electron - hole recombination in the relaxed quantum dots .
optical emitters are one of the key components of optoelectronics and photonics . in spite of the rapid progress in light emitting technology for the visible spectral range during the last decades ,
the realization of efficient light emitters embedded in the silicon environment remains a challenge .
several efforts have been focused on monolithic integration of iii - v light emitters with silicon . among the iii - v compounds , gap has the smallest lattice mismatch to si ( less than 0.4% ) .
conventionally , gap is used in manufacturing low - cost green to orange light - emitting diodes ( leds ) .
gap is , however , similar to si , an indirect band gap semiconductor ( @xmath3 ev ) and useful light emission from it is only possible by doping which results in low luminescence efficiency .
the challenge of high - efficiency light emitters based on gap has recently been approached by exploring the use of epitaxial quantum structures embedded in this material .
the optical emission from several gap - based qds systems has been investigated .
the inp / gap qd system with a lattice mismatch of 7.7% emits light at about 2 ev @xcite and light - emitting diodes based on inp / gap quantum structures emitting in the red to green spectrum have been demonstrated @xcite .
however , it has been found that the inp / gap quantum structures do not always possess a direct heterointerface and depending on the size and geometry of quantum structures the heterointerface can be indirect in both * k * and real space @xcite , or the lowest electron states can be localized at the interface with a mixed @xmath4 character @xcite .
the system inas / gap may provide a stable direct heterointerface due to its higher conduction band offset compared to the inp / gap .
however , the high lattice mismatch of about 11.4% between inas and gap results not only in the formation of volmer - weber islands but also in dislocations @xcite . adding ga into inas reduces the large lattice mismatch and allows the growth of defect - free stranski - krastanow qds .
the ( in , ga)as / gap qds show photoluminescence ( pl ) in the red range @xcite and , depending on the in concentration and the shape the dots , can have direct heterointerface @xcite .
light emitting diodes and electrical injection qd laser have been demonstrated based on this materials system @xcite . in the materials system ( in , ga)as / gap , the gaas / gap has the lowest lattice mismatch of 3.6% but sufficient for formation of self - organized defect - free qds in the stranski@xmath5krastanow mode @xcite .
low - temperature pl of gaas / gap qds at about 1.96 ev has been reported @xcite .
it has been shown that the relaxed gaas / gap qds have a type - i heterointerface with the lowest electronic state at l minima of the gaas conduction band @xcite .
the pseudomorphic gaas / gap quantum wells ( qws ) and qds , however , have type - ii heterointerface @xcite . in this letter , we demonstrate that by controlling the growth of gaas / gap qds , the gaas / gap qds can be changed from an indirect type - ii or type - i system to a direct type - i system with light emission up to room temperature . depending on the growth conditions , the optical emission of the structures peaks between 1.7 and 2.1 ev .
structures were grown in a riber-32p gas - source molecular beam epitaxy ( gsmbe ) system on gap(001 ) substrates .
after oxide desorption , a 0.5 @xmath6 m gap buffer layer at a growth rate of 0.83 @xmath7m / h was grown at 520@xmath8c .
the growth then was interrupted while the substrate temperature was reduced to 450@xmath8c .
then , the desired thickness of gaas was grown at a rate of 0.3 monolayers / s ( ml / s ) .
the resulting structures were capped by 50 nm of gap . during growth
, the process was monitored using reflection high - energy electron diffraction ( rheed ) .
the surface of gap showed a sharp ( 2@xmath94 ) reconstruction .
the rheed pattern remained streaky for the first ml of gaas , indicating 2-dimensional growth and changed to the broken lines for thicker gaas coverage , indicating the formation of qds .
each sample contains one gaas layer with a nominal coverage between 1.2 and 3.6 ml .
( one ml of unstrained gaas is 0.28 nm thick .
) samples for atomic force microscopy ( afm ) were grown without the gap cap layer .
the density and size of qds were characterized using a bruker icon dimension afm with peak force mode @xcite .
fig .
1 depicts the afm images of the samples with nominal coverage of 1.2 ( fig .
1a ) and 1.8 mls ( fig .
1b ) of gaas . according to the afm results , the formation of qds occurs for gaas nominal thickness greater than 1.2 ml and confirms our rheed observation . the lateral size and the average height of qds increase with increasing nominal thickness from 18 nm and 0.9 nm ( 1.8-ml gaas ) to 36 nm and 2 nm ( 3.6-ml gaas ) .
the data are summarized in fig .
1c .
the areal density of qds varies in the range of @xmath10 @xmath2 .
the estimated thickness of the wetting layer using the afm data is between 0.3 - 0.5 nm .
the cross - section image of a capped 1.8-ml sample measured using high - angle annular dark - field scanning transmission electron microscopy ( tem ) provides similar information about the wetting - layer thickness and the size of the qds .
fig .
1d shows the distribution of the height of qds for three different nominal coverage of gaas between 1.8 to 3.6 ml .
the distribution of both height and lateral size seems to be multimodal @xcite .
the similar size distribution has been reported for the gaas / gap qds investigated by tem @xcite .
spectrally resolved cathodoluminescence ( cl ) measurements were carried out using a xiclone ( gatan uk ) cl system attached to an leo 1530 ( carl - zeiss ) field - emission scanning electron microscope .
the cl signal was detected with a peltier - cooled ccd camera .
fig .
2 depicts the cl spectra ( 80 k ) and their corresponding fits from four gaas / gap samples , each consisting of a single layer gaas with nominal thickness between 1.2 and 3.6 mls and a 50-nm gap cap layer . in order to reduce the effect of the luminescence due to the gap buffer
, we applied an acceleration voltage of 5 kv that leads to an effective excitation depth of about 100 nm . the beam current was controlled by varying the microscope aperture size .
the cl spectrum of a gap epitaxial layer is also shown for comparison in fig .
2 .
the cl spectrum of the 1.2-ml sample , which , according to the afm results , consists of a single qw , demonstrates only one emission peak at 2.07 ev .
samples with gaas nominal thickness above 1.2 ml and containing qds show , however , spectra that can be fitted using two gaussian - shaped lines . for thicker gaas
nominal coverage , the total light output increases and the spectra have an overall redshift .
the first emission peak at higher energies ( position a ) shifts from 2.06 ( 1.8-ml sample ) to 1.88 ev ( 3.6-ml sample ) and the second emission peak ( position b ) shifts from 1.93 ( 1.8-ml sample ) to 1.78 ev ( 3.6-ml sample ) .
temperature dependent cl and pl measurements show that the 2.7-ml and 3.6-ml samples emit light up to room temperature , whereas the light output of the 1.2-ml and 1.8-ml samples become negligible for temperatures above 160 k. apparently , the thermal quenching of the luminescence is less for the thicker gaas coverage ; e.g. in the temperature range between 10 and 300 k the light output of 2.7-ml sample decreases more than 30 times and for 3.6 ml sample only 6 times . in order to investigate the carrier recombination dynamics and the origin of the luminescence
, we carried out time - resolved pl between 5 and 300 k. the samples were excited by 80-fs pulses at 388 nm from a mode - locked laser producing an optical pulse train at 82 mhz .
fig .
3a depicts the pl intensity decay of the 3.6-ml sample at 75 k for two emission peaks , a and b. the transients were fitted by a simple exponential decay with a single time constant .
fig .
3b summarizes the energy dependence of the emission decay times for the three different samples represented in fig .
2 .
the decay times for the peak a and b are highlighted .
for all samples , higher emission energy is correlated with slower luminescence decay . as the nominal coverage of gaas
is increased from 1.8 ml to 3.6 ml , the decay time for the peak a decreases from 8.5 ns to 6 ns .
the decay time at peak b changes from 3 ns to 2.4 ns .
increasing temperature results in the shorter decay time as a consequence of the thermally activated non - radiative decay processes ; e.g. the 3.6-ml sample exhibits decay times at 300 k of about 3.1 and 0.9 ns for peaks a and b. our experimental results can be understood as follows : according to the structural investigations , the qw sample ( 1.2 ml ) and the small qds ( less than 1 nm high ) are fully strained . due to the strain , the conduction band minimum of gaas has a shift of 356 mev to higher energy and hence , the @xmath11-like electrons in the gaas are located significantly higher than the x - valley in the gap . in such a case , the favorable optical transition is indirect and occurs between the electrons ( e ) localized at the x state of gap and the heavy - holes ( hh ) in gaas . with increased the gaas coverage , the qds become larger and partially relaxed . depending on the degree of relaxation , the bottom of the @xmath11-conduction band in gaas shifts to lower energy . finally for the fully relaxed qds , the electrons at the @xmath11 state in gaas are localized lower than the x - valley in the gap matrix and the electron - hole transition becomes direct in both @xmath12 and real space .
fig .
4a shows schematically the band alignment of the two extreme situations of a fully strained ( type ii and indirect ) and a fully relaxed ( type i and direct ) gaas / gap heterostructure .
the two arrows indicate the e - hh transition for both cases . from the afm analysis , we know that for nominal thickness above 1.8 ml , a multimodal size distribution fits better to the investigated qds than a single gaussian distribution .
we divide the qds , therefore , depending on their height , into small , intermediate , and large qds .
such arrangement fits to the lateral size distribution , too .
the small qds are strained with an indirect e - hh transition , whereas the large qds are relaxed with a direct e - hh transition .
the electrons localized in the qds with intermediate size are expected to have a mixed @xmath4 nature .
we consider that all of qds contribute to the optical emission and they are the origin of peaks a and b in fig . 2 for nominal thickness above 1.8 ml .
peak a is due to the smaller qds and peak b to the larger qds .
our model is also experimentally supported by the behavior of the luminescence intensity for the samples with different gaas coverage , in particular the ratio between peaks a and b. as can be seen in fig .
2 , an increased nominal coverage of gaas is correlated with a larger total light output and more dominant peak b. we suggest that the increasing of the total light intensity is connected to a transition from a fully strained indirect type - ii qds system ( 1.8 ml sample ) to a relaxed system with direct type - i qds ( 3.6-ml sample ) . for 2.7 and 3.6 ml samples , the large qds are already relaxed and have higher intensity due to the stronger overlap between electrons and holes wave functions in the type - i band alignment . the facts that both samples emit light up to room temperature and the faster decay time for peak b indicate a direct gap and type - i character of large qds in the samples .
the larger qds have light emission at lower energy mainly due to the confinement effect .
the small qds , on the other hand , emit predomintly at position a with a slower decay time and faster thermal quenching , behaving like a type - ii system .
the connection between the increasing of size and the red shift in emission energy with the corresponding band alignment explain the decay time behavior presented in fig .
3b . the probability to have a mixed direct and indirect transition , and finally a direct and type - i qd increases with increasing the size of the qds .
larger dots with type - i band alignment have large overlap between the electron - hole wave functions and hence , faster decay time .
the fastest measured decay time of about 2 ns is still higher than the reported values for the pure type - i systems , but it can be explained by the mixed direct - indirect nature of the optical transitions . generally , at the interface of two semiconductors , with their conduction band minima at two different valleys , the formation of localized interface states is expected .
such states may have also mixed @xmath4 character and lead to optical transition , particularly for a common anion heterointerface . however , in the case of gaas / gap with a common cation heterointerface the interface states are not localized in the gap and are not optically active , as predicted by atomic empirical pseudopotential calculations @xcite .
the appearance of peak a and b in luminescence spectra shows that both kinds of transition occur simultaneously in a mixed ensemble of type - i and type - ii qds .
the excitation intensity dependence of the pl measurements in the range of 0.001 to 10 w/@xmath13 verifies this picture and shows a remarkable 50 mev blueshift for peak a and a slight blueshift of about 6 mev for peak b for the 3.6-ml sample .
the strong blueshift has already been reported for several type - ii qds @xcite . in order to corroborate our model , we calculated the energy states of gaas / gap qws and qds using the effective mass approximation for different relaxation degree @xcite .
since the height of the qds is at least one order of magnitude smaller than their lateral size , the qds were modeled as qws with a thickness equivalent to the height of the qds . according to the calculation
, a direct e - hh transition in gaas qds is expected only if the qds are higher than 2 nm and fully relaxed .
fig .
4b depicts the calculated energetically lowest and favorable e - hh transition for fully strained , 75% strained , and fully relaxed qds as a function of the height .
the symbols show the peak positions of samples with nominal coverage between 1.2 ml to 3.6 ml .
the corresponding height for every peak position was taken from afm analysis and gives the average height of small and large qds in every sample .
the luminescence peak positions fit well to the calculated results .
these results support our model for a transition from optically low - efficient indirect type - ii strained qw and qds to optically efficient direct type - i relaxed qds while the size of dots increases .
the strain relaxation in the gaas / gap qds occurs via the formation of edge dislocations , which do not act as nonradiative recombination centers and hence , allows the realization of high - efficient e - hh transition @xcite .
similar characteristics have been also reported for the qds based on the direct gap ingaas embedded in the indirect gap matrix @xcite .
several stranski - krastanow qds systems such as ( in , ga)as / gaas and inas / inp show luminescence spectra with two peaks , which are attributed to the qds and to the wetting layer .
however , the emission energy of gaas / gap qds is very low for the strained wetting layer with an estimated thickness of @xmath14 nm .
therefore , we believe that the origin of the light emission is the carrier recombination in the qds . only for 1.8-ml sample the origin of peak a might be the fully strained wetting layer . in summary
, we have demonstrated the optical emission of the gaas / gap qds up to room temperature in the visible range .
the luminescence spectra can be fitted using two gaussians .
the afm analysis shows a multimodal size distribution for the qds .
the thin quantum wells and small dots are fully strained and have type - ii band alignment with indirect e - hh transition , whereas the large qds are fully relaxed with type - i band alignment and direct e - hh transition .
this research has been supported by the european commission fp7-ict-2013 - 613024-grasp .
s. dadgostar thanks yousef jameel foundation for the financial support .
xx f. hatami , w.t .
masselink , and l. schrottke appl .
. lett . * 78 * , 2163 ( 2001 ) .
f. hatami , w.t .
masselink , l. schrottke , j.w .
tomm , v. talalaev , c. kristukat , and a.r .
gni , phys .
rev .
b * 67 * , 85306 ( 2003 ) . f. hatami , w.t .
masselink , v. lordi , and j.s .
harris , phot .
tec .
lett , ieee . * 18 * , 895 ( 2006 ) .
f. hatami , w.t .
masselink , and j.s .
harris , nanotechnology * 17 * , 3703 ( 2006 ) .
a.r .
gni , c. kristukat , f. hatami , s. dressler , w.t .
masselink , and c. thomsen , phys .
rev .
b * 67 * , 75306 ( 2003 ) .
f. hatami , g. mussler , m. schmidbauer , and w. t. masselink , appl .
. lett . * 79 * , 2886 ( 2001 ) .
v. popescu and a. zunger , phys .
rew .
b. * 84 * , 125315 ( 2011 ) .
r. leon , c. lobo , t.p .
chin , j.m .
woodall , s. fafard , s. ruvimov , z. liliental - weber , and m.a .
stevens kalceff , appl .
. lett . * 72 * , 1356 ( 1998 ) . y. song , p.j .
simmonds , and m.l .
lee , appl .
phys . lett.*97 * , 223110 ( 2010 ) .
t. nguyen thanh , c. robert , c. cornet , m. perrin , j. m. jancu , n. bertru , j. even , n. chevalier , h. folliot , o. durand , and a. le corre , appl . phys .
lett . * 99 * , 143123 , ( 2011 ) .
g. stracke , e.m .
sala , s. selve , t. niermann , a. schliwa , a. strittmatter , and d. bimberg appl .
. lett . * 104 * , 123107 ( 2014 ) . c. robert , c. cornet , p. turban , t. nguyen thanh , m.o .
nestoklon , j. even , j.m .
jancu , m. perrin , h. folliot , t. rohel , s. tricot , a. balocchi , d. lagarde , x. marie , n. bertru , o. durand , and a. le corre , phys .
rev .
b * 86 * , 205316 ( 2012 ) . y. song , and m.l .
lee , appl .
phys . lett.*100 * , 251904 ( 2012 ) .
m. heidemann , s. hfling , and m. kamp , appl .
. lett . * 104 * , 011113 ( 2014 ) .
t. nomura , k. ishikawa , k. murakami , and m. hagino , j. cryst .
growth * 127 * , 584 ( 1993 ) .
t.s .
shamirzaev , d.s .
abramkin , a.k .
gutakovskii , and m. a. putyato , appl .
. lett . * 97 * , 023108 ( 2010 ) .
d.s .
abramkin , m.a .
putyato , s.a .
budennyy , a.k .
gutakovskii , b.r .
semyagin , v.v .
preobrazhenskii , o.f .
kolomys , v.v .
strelchuk , and t.s .
shamirzaev , j. appl . phys . * 112 * , 083713 ( 2012 ) .
i. horcas , r. fernndez , j.m .
gmez - rodrguez , j. colchero , j. gmez - herrero , and a. m. baro , rev .
sci .
instrum.*78 * , 013705 ( 2007 ) .
h. kissel , u. mller , c. walther , w. t. masselink , yu . i. mazur , g. g. tarasov , and m. p. lisitsa , _ phys .
rev .
b _ , vol . 62 , pp . 72137218 , 2000 .
s. birner , t zibold , t andlauer , t kubis , m sabathil , a. trellakis , p. vogl electron devices , ieee transactions on * 54 ( 9 ) * , 2137(2007 ) m.k.k .
nakaema , f. iikawa , m.j.s.p .
brasil , e. ribeiro , g. medeiros - ribeiro , w. carvalho , m.z .
maialle , and m.h .
degani , appl .
phys .
lett .
81 , 2743 ( 2002 ) .
f. hatami , m. grundmann , n. n. ledentsov , f. heinrichsdorff , r. heitz , j. bohrer , and d. bimberg , et.al , phys .
rev .
b , * 57 * , ( 1988 ) . | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | figure.1- afm images of ( a ) 1.2 ml and ( b ) 1.8 ml gaas / gap .the scale bar is 100 nm .( c ) the summary of the afm analysis for the lateral size ( circles and left axis ) and height ( squares and right axis ) for different gaas coverage .the dashed lines are a guide to the eye .( d ) histograms of height distribution for three different gaas coverage .+ figure.2- cl spectra of gaas / gap quantum structures capped by 50 nm gap at 80 k with corresponding fits .cl spectrum of gap buffer is also shown for comparison .the measurements were performed using 5 kev excitation energy .+ figure.3- ( a ) time - resolved pl spectra of the 3.6-ml sample for two emission peak maxima a ( blue circles ) and b ( red squares ) at 75 k with their corresponding fits ( black lines ) .the two arrows in the inset show the energy position of peak a and b. the decay time of peak a is 5.5 ns and for peak b 2.4 ns .( b ) pl decay times of 1.8 , 2,7 , and 3.6 ml samples for different emission energy at 75 k. + figure.4- ( a ) scheme of band alignment for a fully strained ( type ii and indirect ) and a fully relaxed ( type i and relaxed ) gaas / gap heterostructure .the two arrows present the favorable e - hh transition .( b ) the calculated energetically lowest e - hh transition for fully strained , 75% strained , and fully relaxed qds as a function of the height .the symbols show the luminescence peak positions of four samples .the height for every peak position was taken from afm analysis and gives the average height of small and large dots for the qds samples , and the thickness of the qw in 1.2-ml sample . |
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– The world may have a surprise new "oldest person," and by a good margin, reports AFP. A daily newspaper in Guatemala reports that a woman named Juana Chox Yac has a government birth certificate that puts her age at 120. That would make her four years older than the current No. 1, Japan's Misao Okawa. But the Washington Post notes that the two leading authorities on such matters—the Guinness Book of World Records and the Gerontology Research Group—apparently have yet to confirm. Yac is an indigenous Mayan who was born in a farming village called Santa Lucia Utatlan. She married at 15 and had two kids, but her husband died nine years later. She remarried at age 29 and had seven more children before becoming a widow for the second time in 1964. Government officials describe her as "lucid" and looking forward to her 121st birthday in November. (Click to read about what it's like to be 100.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | GUATEMALA CITY: A Guatemalan woman who used to pick coffee and tend sheep - and who will turn 121 in November - could be the world's oldest by far, a national newspaper reported Tuesday. Juana Chox Yac, who is an indigenous Kaqchikel Maya, was born November 29, 1893 in the farming village of Santa Lucia Utatlan, Solola department, the report in the daily Siglo 21 said. As a young woman, she worked picking coffee beans, and tending sheep and goats, before marrying at 15, the newspaper said. Her first husband died nine years after they were married and their two children have died as well. Chox Yac however remarried at 29 and had seven more children before being widowed again in 1964. She has a family of 75 relatives including children, grandchildren, great-grandchildren and great-great-grandchildren, said the report, which published a government document with her birth date. It was not immediately known if her details have been submitted to the Guinness Book of World Records for verification. But the report puts her age at four years older than Japan's Misao Okawa, who turned 116 on March 5 and is the book's official record holder for longest-lived woman. ||||| Please enable cookies on your web browser in order to continue. The new European data protection law requires us to inform you of the following before you use our website: We use cookies and other technologies to customize your experience, perform analytics and deliver personalized advertising on our sites, apps and newsletters and across the Internet based on your interests. By clicking “I agree” below, you consent to the use by us and our third-party partners of cookies and data gathered from your use of our platforms. See our Privacy Policy and Third Party Partners to learn more about the use of data and your rights. You also agree to our Terms of Service. |
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– Hiring picked up in August as US employers added a stronger-than-expected 201,000 jobs, a sign of confidence that consumers and businesses will keep spending despite the Trump administration's conflicts with trading partners, per the AP. The Labor Department says the unemployment rate remained 3.9%, near an 18-year low. Americans' paychecks grew at a faster pace. Average hourly wages rose in August and are now 2.9% higher than they were a year earlier, the fastest annual gain in eight years. Still, after adjusting for inflation, pay has been flat for the past year. The economy is expanding steadily, fueled by tax cuts, confident consumers, greater business investment in equipment, and more government spending. Growth reached 4.2% at an annual rate in the April-June quarter, the fastest pace in four years. The good news might not necessarily be a boon for investors. The Wall Street Journal notes that stock futures dropped and the dollar surged in the immediate aftermath of the report's release—on fears the Fed will step up rate increases with wages and inflation on the rise. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | WASHINGTON (AP) — Hiring picked up in August as U.S. employers added a strong 201,000 jobs, a sign of confidence that consumers and businesses will keep spending despite the Trump administration's conflicts with U.S. trading partners. The Labor Department says the unemployment rate remained 3.9 percent, near an 18-year low. Americans' paychecks grew at a faster pace. Average hourly wages rose in August and are now 2.9 percent higher than they were a year earlier, the fastest annual gain in eight years. Still, after adjusting for inflation, pay has been flat for the past year. The economy is expanding steadily, fueled by tax cuts, confident consumers, greater business investment in equipment and more government spending. Growth reached 4.2 percent at an annual rate in the April-June quarter, the fastest pace in four years. ||||| One sector to keep an eye on in future jobs reports: manufacturing. The sector was little changed last month on the employment front, losing 3,000 jobs, a slowdown for one of the economy's bright spots in recent months. Although the dip ended a streak of 12 consecutive months of job additions, the group is still up 254,000 jobs in the past year. Some lukewarm manufacturing data points have started to worry some analysts, and investor sentiment toward large U.S. manufacturs has also taken a hit due to continuing trade fights. Dean Baker, a senior economist at the Center for Economic and Policy Research, notes that wage gains also grew 1.8% from a year earlier in the sector, lagging behind other groups. "While it is far too early to determine if the Trump administration's trade policy is responsible for this weakness, it seems clear that it is not showing obvious benefits at this point," he says in a note. But even with the drop off for the manufacturing sector, strength in professional and business services, health care and construction lifted the headline jobs number. |
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– The rail dispatcher in charge of two trains that collided in Germany in February, killing 11, was playing a game on his phone just before the crash, authorities say. The man, whose name is not being released but who is a 39-year-old with years of experience, has been arrested on suspicion of negligent homicide, the Wall Street Journal reports. The collision near Munich Feb. 9 was one of the worst rail accidents in Germany's recent history, and no technical problems have been found to have contributed, the AP reports. "Due to the close timing it must be assumed that the accused was distracted from controlling the cross-traffic of the trains," prosecutors say in a statement, adding that the dispatcher had been actively playing the cellphone game for "an extended period of time" until shortly before the collision. He likely gave the trains the incorrect signals, then pressed the wrong combination of buttons while trying to issue an emergency call, meaning the train drivers probably never heard it. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | BERLIN (AP) — A German rail dispatcher was playing an online game on his cellphone shortly before two trains he was in charge of collided on a single-track line, killing 11 people, prosecutors said Tuesday. The unnamed dispatcher was arrested on suspicion of negligent homicide, prosecutors in the Bavarian town of Traunstein said in a statement. The two trains were filled with commuters when they collided head-on Feb. 9 near the town of Bad Aibling, about 60 kilometers (40 miles) southeast of Munich. It was one of Germany's worst rail accidents in recent history. Prosecutors said the man had been actively playing the game on his cellphone for "an extended period of time" until shortly before the crash. Rail dispatcher rules forbid the use of personal cellphones at work. "Due to the close timing it must be assumed that the accused was distracted from controlling the cross-traffic of the trains," the statement said. This likely led the dispatcher to give the trains the wrong signals and then, once he noticed his error, to fumble the emergency call by pressing the wrong combination of buttons, meaning the train drivers were unable to hear it, prosecutors said. The man acknowledged during questioning that he had played a game, but denied having been distracted by this, they said. So far, investigators haven't been able to find any indication of a technical problem that might have caused or contributed to the crash, prosecutors said. ||||| BERLIN—A train dispatcher who was overseeing the stretch of track where two trains collided head-on in February, leaving 11 dead, was playing with his smartphone until just before the crash, investigators said Tuesday as they announced his arrest. The high-speed crash between two commuter trains traveling along a one-way section of track in the Bavarian town of Bad Aibling left the wagons of one train wedged inside the other and more than 80 passengers injured. ... |
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– This might just be a weird coincidence, or Tim Tebow's dramatic defeat of the Steelers last night may have been a miracle in more ways than one. The polarizing Denver quarterback wound up throwing for 316 yards, which, if you toss in a colon in the right spot, mirrors the call number of a famous bible verse, John 3:16. That's a verse Tebow occasionally wrote on his face while playing at the University of Florida, Fox News reports. Not weird enough for you? Well, Tebow threw those 316 yards over the course of 10 completions, meaning he averaged 31.6 yards per completion. Wait, there's more: John Ourand of the Sports Business Journal tweeted that the TV rating for the last 15 minutes of the game was—you guessed it—a 31.6. Was this some kind of divine product placement? Probably not, but if it was it worked: As of this writing, John 3:16 is No. 1 on Google Trends. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Tim Tebowed and Denver rose as one. The Broncos quarterback's 80-yard touchdown pass to receiver Demaryius Thomas on the first play of overtime against Pittsburgh both clinched Sunday's game and wrote another improbable chapter in Tebow's book of clutch plays to win high-pressure games. His performance also borrowed a little magic from another famous book. The devout Christian's stat line in Sunday's game mirrors the numbering of the Biblical passage that Tebow at times had painted on to his black eye paint during his career at the University of Florida -- John 3:16. The passage reads, according to the New American Standard Bible, "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life." Officially, Tebow passed for 316 yards against the Steelers, completing 10 of 21 pass attempts -- meaning he passed for 31.6 yards per completion. After his final pass was caught and brilliantly taken downfield by Thomas, Tebow shrugged off three bad weeks -- when he threw for just one touchdown and four interceptions -- and took a knee and prayed in his classic style. "First and foremost, I just want to thank my savior, the Lord, Jesus Christ," Tebow said at the postgame press conference. "I am so thankful for the platform God has given me." Next up for those on the Tebow bandwagon, a trip to New England to tackle Tom Brady and the Patriots in the AFC divisional playoff game on Saturday. ||||| Focused crawls are collections of frequently-updated webcrawl data from narrow (as opposed to broad or wide) web crawls, often focused on a single domain or subdomain. You are using unsupported browser. Some features may not work correctly. Upgrade to a modern browser , such as Google Chrome Trends has upgraded to a newer version, which is not supported by this device. |
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– A "badass" guitar designed for women is coming to market in March, Esquire notes, and female shredders have Annie Clark to thank for it. Clark, better known as alternative rocker St. Vincent, has designed a signature guitar for manufacturer Ernie Ball Music Man, and as Clark notes on Instagram, the instrument is "ergonomic, lightweight, and sleek"—and by "sleek" she means there's "room for a breast … or two." The guitar, which comes in black or "Vincent Blue" (which the artist hand-mixed herself), is made of African mahogany with a rosewood neck, has a slim and tapered waist, and weighs just over 7 pounds, per Guitar World. "For me a guitar that is not too heavy is really important because I'm not a very big person," she tells the magazine. "I can't even play a ['60s] Strat or ['70s] Les Paul. I would need to travel with a chiropractor on tour in order to play those guitars." Clark, who notes she "really had total free reign" over the design, says she was approached by Ernie Ball in the early spring of 2015 and had worked up a first prototype within a week of visiting the factory (there have been many other versions since her collaboration with Ernie Ball engineers). While creating it, she took into account how its weight would be distributed, as well as the fact that she didn’t want it to cover up what she considers to be one of a female performer's best features: her waist. In the end, though, it’s all about the music. "If you have a great instrument you're going to play better," she says. "You're going to play up to the level of the instrument because it makes it easier for you to succeed." Her first public performance with the guitar? On stage at a Taylor Swift concert with Swift and Beck. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Indiana UniversityArchive-It Partner Since: Sep, 2005Organization Type: Colleges & UniversitiesOrganization URL: http://www.libraries.iub.edu The IU Bloomington Libraries are one of the leading academic research library systems in North America, providing strong collections, quality service and instructional programs, and leadership in the application of information technologies.The Bloomington campus library holdings include more than 6 million bound volumes and more than 17 million other materials, including manuscripts, maps, music, microforms, and films. The IU Bloomington Libraries comprise the Main Library (which houses collections in the humanities and social sciences), subject-specific campus libraries, and other units such as the Wylie House Museum and University Archives. ||||| Did you know most guitars are not female-friendly? Neither did we until Annie Clark introduced the St. Vincent signature guitar she designed for Ernie Ball Music Man. And it looks badass. Advertisement - Continue Reading Below In an interview with Guitar World, Clark (aka St. Vincent), talked about why traditional guitars are not a viable option for her: "I'm not a very big person. I can't even play a Sixties Strat or Seventies Les Paul. I would need to travel with a chiropractor on tour in order to play those guitars." That's why Clark designed the St. Vincent with a thin waist. As she wrote on Instagram, "There is room for a breast. Or two." Aside from functionality, the design combines a retro aesthetic with a '67 Corvette color scheme. The model will be released in March. "If you have a great instrument you're going to play better," Clark says. "You're going to play up to the level of the instrument because it makes it easier for you to succeed." Advertisement - Continue Reading Below Need proof? Watch her rock out with her new guitar on stage with Beck and Taylor Swift. And here's more shredding: And here she is on stage with the surviving members of Nirvana: |
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– A Florida man's cunning plan to smuggle drugs in his ample stomach fat was foiled because he was too big to fasten his seat belt. Police say that after 450-pound suspect Christopher Mitchell—whose aliases include "Fat Boy" and "Biggie"—appeared nervous during a traffic stop, a drug-sniffing dog was called in and a search turned up 23 grams of marijuana stashed under rolls of fat, the Smoking Gun reports. Cocaine, a handgun, and $7,000 in cash stuffed into a sock were also found during a search of the vehicle, which was pulled over when a deputy spotted that Mitchell didn't have a seat belt on, the New York Daily News reports. The 42-year-old suspect, who weighed around 200 pounds less when he was convicted of conspiracy to traffic cocaine in 2002, was charged with marijuana possession as well as failure to wear a seat belt. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Police: 450-Pound Florida Man Had Marijuana Stashed In His "Stomach Fat" Share Tweet A 450-pound Florida man was arrested yesterday after cops conducting a traffic stop discovered that he had stashed marijuana under his stomach fat. Christopher Mitchell, 42, was traveling in a vehicle driven by Keithian Roberts, 38, when the car passed a sharp-eyed Volusia County Sheriff’s Office deputy who noticed that the 5' 6" Mitchell was not wearing a seatbelt. During a subsequent traffic stop, both men reportedly appeared nervous, prompting the cop to summon a drug-detection dog. Mitchell, investigators noted, claimed to be so big that he was unable to buckle himself in. After the drug dog alerted to the presence of narcotics in the vehicle, officers searched Mitchell, Roberts, and the car. Investigators found "23 grams of marijuana hidden under Mitchell’s stomach fat,” a handgun, $7000 in cash, and some cocaine (for which Roberts was hit with a possession charge). Mitchell, seen in the above mug shot, was also cited for failure to wear a seat belt. Additonally, deputies noticed that the car’s trunk and its interior were “sprinkled with carpet freshener and scented dryer sheets, a common tactic used to conceal the odor of drugs when they’re being transported,” according to a news release which does not reveal which unfortunate deputy had to excavate the pot from Mitchell's stomach cave. According to Florida Department of Corrections records, Mitchell was previously convicted of cocaine trafficking (for which he served three years in prison). Mitchell, who was freed in December 2004, had several aliases, including “Biggie” and “Fat Boy.” His weight a decade ago was 265 pounds, jailers reported. The svelter, smock-wearing Mitchell is seen above in a old prison photo. ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. |
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– In a Twitter storm on Tuesday, Donald Trump implied he'd been chained to the Republican Party for too long. But in the wake of recent denouncements from dozens of Republicans, including Paul Ryan, "the shackles have been taken off me and I can now fight for America the way I want to," he said, per Politico. In what is widely viewed as evidence of a widening rift in the Republican Party, Trump went on to bash Ryan as a "very weak and ineffective leader" and label Democrats—"with the exception of cheating Bernie"—as "far more loyal to each other" than Republicans. "Despite winning the second debate in a landslide (every poll), it is hard to do well when Paul Ryan and others give zero support!" he continued, adding, Republicans "are far more difficult than Crooked Hillary." Bustle's take: Trump's "going rogue and it could get scary." In response, a rep says Ryan "is focusing the next month on defeating Democrats, and all Republicans running for office should probably do the same," per USA Today. Despite several GOP members calling on Trump to remove himself from the presidential race, the nominee vowed Tuesday to teach Republicans "how to win." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Donald Trump’s tweet was a tacit attack on House Speaker Paul Ryan. | Getty Trump: 'It is so nice that the shackles have been taken off me' Donald Trump celebrated his freedom from the Republican establishment Tuesday, boasting that it’s “so nice” to be unchained. Trump’s tweet was a tacit attack on House Speaker Paul Ryan, whom the Republican nominee has continued to lash out at since the top elected Republican on Monday told his conference he would no longer defend Trump. Story Continued Below “It is so nice that the shackles have been taken off me and I can now fight for America the way I want to,” Trump tweeted. The real estate mogul also highlighted the chasm in the Republican Party, conceding that Democrats are “far more loyal” than the GOP. More than two dozen Republicans have either said they will no longer support their nominee or called on him to step aside from the top of the ticket since a tape emerged Friday showing Trump speaking in incredibly lewd terms about sexually assaulting women. “With the exception of cheating Bernie out of the nom the Dems have always proven to be far more loyal to each other than the Republicans!” Trump wrote. Trump began blasting Ryan on Twitter at about 8 a.m., when he posted a tweet criticizing the GOP leader for not supporting him and followed up by calling him “weak and ineffective.” ||||| Tweet with a location You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more ||||| Tweet with a location You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more |
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– President Obama secretly penned a letter to Ayatollah Khamenei last month, sources tell the Wall Street Journal, in an attempt to prod the Iranian leader toward a nuclear deal while simultaneously underscoring the two nations' joint interest in fighting ISIS—with any cooperation on the latter being what the Journal calls "largely contingent" on the former. Senior American officials wouldn't talk about the letter, and NPR notes that White House Press Secretary Josh Earnest said today that he's "not in a position to talk about private correspondence between the president and another world leader." Khamenei has reportedly never directly responded to any of Obama's previous three letters. The US and Tehran have shared warmer relations since the election of Hasan Rouhani, but it's not clear how far Obama's going to get with Khamenei. Obama himself said yesterday that "there’s a sizable portion of the political elite that cut their teeth on anti-Americanism," and that "whether they can manage to say 'yes' ... is an open question." Khamenei as recently as last month blamed "America, Zionism, and ... the wicked government of Britain" for creating "al-Qaeda and (ISIS) in order to create divisions and to fight against the Islamic Republic, but today, they have turned on them." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | WASHINGTON—President Barack Obama secretly wrote to Iran’s Supreme Leader Ayatollah Ali Khamenei in the middle of last month and described a shared interest in fighting Islamic State militants in Iraq and Syria, according to people briefed on the correspondence. The letter appeared aimed both at buttressing the campaign against Islamic State and nudging Iran’s religious leader closer to a nuclear deal. Mr. Obama stressed to... ||||| America Report: Obama Wrote Letter To Iran's Ayatollah Khamenei About Islamic State Citing "people briefed on the correspondence," The Wall Street Journal is reporting that President Obama wrote a letter to Iran's supreme religious leader Ayatollah Ali Khamenei this past October. The letter, according to the newspaper, was about the U.S.-led fight against the so-called Islamic State. The Journal reports: "The letter appeared aimed both at buttressing the Islamic State campaign and nudging Iran's religious leader closer to a nuclear deal. "Mr. Obama stressed to Mr. Khamenei that any cooperation on Islamic State was largely contingent on Iran reaching a comprehensive agreement with global powers on the future of Tehran's nuclear program by a Nov. 24 diplomatic deadline, the same people say. "The October letter marked at least the fourth time Mr. Obama has written Iran's most powerful political and religious leader since taking office in 2009 and pledging to engage with Tehran's Islamist government." During his regularly scheduled press briefing, White House Press Secretary Josh Earnest was asked about the report and responded that he was "not in a position to talk about private correspondence between the president and another world leader." Earnest said U.S. policy on Iran "remains unchanged" and that the United States has engaged in talks with Iran about its nuclear program and on the sidelines of those talks, it has also addressed the U.S.-led offensive against the Islamic State. Earnest said the U.S. "will not cooperate militarily" and will not share intelligence with Iran. |
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we study the effect of a many - body interaction on inter - band oscillations in a two - band bose - hubbard model with external stark force .
weak and strong inter - band oscillations are observed , where the latter arise from a resonant coupling of the bands .
these oscillations collapse and revive due to a weak two - body interaction between the atoms .
effective models for oscillations in and out of resonance are introduced that provide predictions for the system s behaviour , particularly for the time - scales for the collapse and revival of the resonant inter - band oscillations .
_ introduction .
_ recent experiments proved the possibility to study the coherent dynamics of interacting many - particle systems @xcite .
such realisations of many - body systems with ultra - cold gases in optical lattices have a short but impressive history and open immense possibilities for various fields of physics @xcite .
the demonstration of the well - known phenomenon of collapse and revival , the latter being a pure quantum effect , with ultra - cold atoms bears witness of this coherent evolution of a many - body wave function @xcite .
additionally , the high degree of control in such experiments allows a manipulation of many system parameters and makes them particularly interesting for various fields of physics as well as future applications @xcite .
different ways of addressing additional degrees of freedom in such ultra - cold bosonic gases have been suggested @xcite . in the present fast track communication
, we discuss a two - band model with an additional external force to control the coupling between the two bands . applying a force to atoms in optical lattices leads to bloch oscillations and
is a realization of a many - body wannier stark system @xcite .
the coupling of the low - lying energy bands in such systems has been demonstrated in different experiments , e.g. on landau - zener tunnelling @xcite and the influence of the many - body interaction on a weak coupling of the bands has also been studied theoretically @xcite .
we go beyond a weak coupling of energy bands and consider an isolated two - band system with a strong external force .
a closed two - band system is an idealisation but can be realised approximatively with ultra - cold atoms @xcite using different techniques as , e.g. , super lattices @xcite .
besides the possibility of experimental realisation , a closed two - band model is also interesting as a simple model system . for the latter , we focus on the two lowest energy bands of interacting bosons in a optical lattice @xmath0 , with the wave vector of the optical lattice @xmath1 .
then , all parameters of the model hamiltonian just depend on this external potential .
the parameters can be computed numerically ( see , e.g. , appendix a in @xcite ) and analytical approximations exist for them for not too small amplitudes @xmath2 @xcite . using this setup , we are able to identify regions of strong and weak inter - band coupling .
a weak two - body interaction introduces new energy scales in the coherent evolution of the many - body wave function , leading to a collapse of such oscillations , but the form of the interaction gives rise to subsequent revivals .
we give analytical expressions for all time - scales in this many - body realisation of a two - band collapse and revival phenomenon , and experimental ramifications for a realisation with ultra - cold bosonic gases are discussed . _ the many - particle model .
_ we study a two - band bose - hubbard model with an additional external stark force for a strong coupling of the two bands , introduced in @xcite @xmath3 . } \ ] ] here , @xmath4 ( @xmath5 ) annihilates ( creates ) a particle at site @xmath6 of totally @xmath7 sites in the lower band and @xmath8 ( @xmath9 ) in the upper band .
the corresponding number operators are @xmath10 , @xmath11 .
the bands are separated by a bandgap @xmath12 and have onsite - energies @xmath13 , respectively .
we include hopping between neighbouring sites in band @xmath14 with a hopping strength @xmath15 , and a repulsive interaction between particles occupying the same site in band @xmath16 with a strength @xmath17 .
the two bands are coupled via @xmath18 , with the external stark force @xmath19 and a coupling constant @xmath20 depending on the depth of the lattice @xmath2
@xcite , and also via the inter - particle interaction with a strength @xmath21 .
all parameters are measured in recoil energies @xmath22 and we set @xmath23 troughout .
focussing on a realisation with a single optical lattice rather than a superlattice , the relation between the parameters is generally : @xmath24 , as well as @xmath25 and @xmath26 .
we take the external force @xmath19 as a free parameter .
we assume that the interaction strength can be tuned ( experimentally , e.g , by the use of feshbach resonances @xcite ) and include a corresponding scaling factor @xmath27 to all interaction terms . to study the occupation of the upper band , we prepare the system in an initial state @xmath28 , with a uniform distribution of particles in the lower band only and evolve it in time by the many - body schrdinger equation .
the quantity we study is the ( normalised ) number of particles in the upper band @xmath29 where @xmath30 is the total number of particles .
we will refer to @xmath31 as _ occupation of the upper band_. let us discuss the non - interacting single - particle case @xmath32 first .
we apply the following transformation involving bessel functions of the first kind @xmath33 to our operators , which is known to remove the hopping terms in the single - band case @xcite @xmath34 with @xmath35 , @xmath36 . using relations for bessel functions , we arrive at @xmath37,\ ] ]
where @xmath38 and @xmath13 as above .
we obtain coupling between any two sites of the two different bands , weighted by bessel functions . in the coupling between different and possibly remote sites
originates from an on - site coupling and subsequent hoppings .
it can thus be considered a higher order process in the original basis .
but in the transformed hamiltonian , this coupling is now direct with a strength modified by the factor @xmath39 .
the hilbert space in the many - particle problem is spanned by fock states with fixed particle number @xmath40 with single - particle basis @xmath41 .
the total dimension of the fock space for a given number of atoms @xmath42 and lattice sites @xmath7 per band is given by @xmath43 $ ] . for numerical simulations ,
we change to the interaction - picture with respect to the external force @xcite which removes the tilt @xmath44 and replaces @xmath45 ( and likewise for @xmath46 ) .
the hamiltonian is then time - dependent with a periodicity of @xmath47 and decomposes into a direct sum of operators for specific quasi - momenta @xmath48 @xcite . as a consequence
, the size of the hilbert space is reduced by a factor of the order of @xmath7 @xcite .
since the different subspaces are physically equivalent , we restrain our discussion to the @xmath49-subspace of the hilbert space @xcite . + for the time - evolution of a given initial state , we use either a direct numerical integration ( with an adaptive step - size runge - kutta algorithm @xcite ) or an eigenbasis expansion after diagonalising the problem : @xmath50 here we use the eigenstates @xmath51 of the floquet - bloch operator ( @xmath52 denotes time - ordering ) @xmath53,\ ] ] since the hamiltonian is explicitly time - dependent , with a periodicity @xmath54 . in addition , this gives us the full spectrum and enables access to relevant energy scales of the problem , as well as an identification of the most important states participating in the time - evolution .
_ results .
_ for the specific system under consideration , i.e. , bosons in optical lattices , both hopping coefficients @xmath55 are smaller than unity and ( since we are interested in strong inter - band coupling ) we take the external stark force @xmath19 to be much larger than the hopping coefficients : @xmath56 .
the non - interacting hamiltonian now allows for simple solutions for two regimes : values of the external force @xmath19 not leading to a degeneracy between energy levels of different bands ( _ off - resonant _ regime ) and values of the force @xmath19 leading to such a degeneracy ( _ resonant _ regime ) .
for the off - resonant regime we make use of @xmath57 and neglect all bessel functions in except for @xmath58 .
the hamiltonian then decomposes @xcite into a sum of independent two - level systems and the occupation of the upper band when initially zero follows a simple rabi formula @xmath59^{-1}\sin^2 ( \tilde\delta t/2)$ ] , where @xmath60 .
this corresponds to rabi oscillations between the bands with an amplitude much smaller than unity and a period @xmath61 of the order of the _ bloch period _ @xmath62 .
an example is shown in the lower panel of where the off - resonant contribution to the oscillations is shown .
although the coupling from a site @xmath6 to sites in the other band with different index @xmath63 is usually small ( cf . discussion after ) , it is important when the two levels become degenerate in energy , i.e. , for resonant values of the force @xmath19 .
this happens when the energy gap between both bands is close to an integer multiple of the external force @xmath64 and we refer to this regime as _ resonant of order @xmath65_. in resonance , the coupling of the degenerate levels is most important and the hamiltonian of can similarly be reduced to a sum of independent two - level systems @xmath66,\ ] ] and diagonalised by @xmath67 and @xmath68 .
the resonant oscillations ( of order @xmath65 ) between the two bands have an amplitude of almost unity and a period given by @xmath69 an example of these resonant oscillations for @xmath70 is shown as the thin dashed line in . the period predicted by the reduction to independent two - level systems
is @xmath71 for the parameters given there , in excellent agreement with where the actual period is @xmath72 .
we found equally good agreement in numerical simulations for different lattice depths and other orders @xmath65 of resonance not explicitly reported here .
let us now study the effect of the many - body interaction in the original hamiltonian
. also shows the occupation of the upper band as a function of time for the initial state @xmath73 in a weakly interacting system with @xmath74 .
we observe a decay of the resonant oscillations followed by a major revival . at later times
several minor revivals occur ( not shown in ) .
this effect is stable against variations of the system parameters ( as number of particles and lattice sites , even for fillings @xmath75 of order but not always close to one ) , with the time scales of decay and revival depending on the interaction strength @xmath27 ( see the following section and ) .
we found the same phenomenon with different initial states in numerical simulations as long as the particles are mainly delocalised along the lattice and occupy only the lower band , i.e. , excluding fock states with all particles on one lattice site for instance .
the oscillatory behaviour depicted in strongly reminds of the collapse and revival effect known from quantum optics @xcite .
a specific feature in these systems is a linear dependence of the collapse and revival time on the inverse coupling strength , i.e. @xmath76 and @xmath77 where @xmath27 usually denotes the coupling strength between the light field and the two - level atom in the quantum optical systems @xcite .
we verified numerically for our system that the observed decay and revival times obey a similar dependence with the interaction parameter @xmath27 as coupling strength in our model .
we define @xmath78 as the time when the difference between the maximal and average amplitude of the inter - band oscillations has fallen to @xmath79 , i.e. , @xmath80 . the revival time is taken as the maximum of the revived oscillations .
clearly demonstrates the linear dependence of these times on the inverse interaction strength . to find an effective description , we try to understand the most relevant interaction processes
clearly , the repulsive two - body interaction disfavours double occupancy of sites since this will always cost an interaction energy @xmath81 for two particles occupying the same site in the lower ( upper ) band .
starting from an initial state with population of the ground band only , the strong stark force leads to an occupation of the upper band .
doubly occupied sites are also suppressed there , but two particles may sit at the same site in either band , i.e. on top of each other " . indeed , the most important interaction term in the time - evolution is @xmath82 , since it already gives a non - zero contribution when there is only one particle per site in each of the two bands .
in fact , comparing the time evolution of the initial state with all interaction terms and only the one mentioned shows almost no difference ( cf . ) .
we focus on fillings close to unity @xmath83 and study the time - evolution of states of the form @xmath84 , which is not an eigenstate of the system in resonance . note
that this is the most important contribution to the superfluid ground state in an expansion in our configuration state fock basis . for large enough systems the superfluid ground state of the untilted system ( and the single - occupancy state @xmath85 likewise ) becomes indistinguishable from a coherent state ( eq . ( 66 ) in @xcite ) that factorises into a product of local coherent states at each site @xmath6 : @xmath86 |{\rm vac}\rangle = \prod_l \big ( \rme^{\sqrt{\bar n } a_l^{{\dagger } } } |{\rm vac}\rangle_l\big ) = \prod_l |\varphi ; 0\rangle_l \equiv |\boldsymbol \varphi ; 0\rangle.\ ] ] we denote this coherent state with phase @xmath87 by @xmath88 .
we are now going to re - write this state in the resonant basis and determine the effect of the interaction term @xmath89 when acting on this state .
we start by inserting the transformation @xmath90 into to obtain @xmath91 |{\rm vac}\rangle \nonumber\\ % & = { \rm exp}\bigg[\sqrt{\frac{n}{2l}}\sum_{l , n}j_{l - n}(x_a)(\mu_n^{\dagger}- \nu_n\dag ) \bigg ] |{\rm vac}\rangle \nonumber\\ & = \prod_n \rme^{\sqrt{\bar n/2}\;\mu_n^{\dagger } } \rme^{-\sqrt{\bar n/2}\;\nu_n^{\dagger } } |{\rm vac}\rangle .
% \equiv \prod_n\big|\frac{\varphi}{\sqrt{2 } } ; -\frac{\varphi}{\sqrt{2}}\big)_n.\end{aligned}\ ] ] where we used @xmath92 $ ] for @xmath93 @xcite and @xmath94=0 $ ] which follows from the properties of the operators @xmath95 .
let us denote fock states with single - particle basis @xmath96 by round parentheses @xmath97 .
from we see , that the coherent state of the lower band in resonance is a product of local coherent states for both bands in the resonance basis @xmath98 with @xmath99 .
the time - evolution of this state ( for the non - interacting system in resonance ) is simple since it is diagonal in the eigenbasis of the hamiltonian in resonance .
we continue to study the phase evolution created by the most important term @xmath89 perturbatively by expressing the operators @xmath100 in the @xmath101-basis : @xmath102 |\boldsymbol{\tilde\varphi } ; -\boldsymbol{\tilde\varphi } ) = \exp\bigg[\frac{\rmi gw_x t } { 2}\sum_{l}\sum_{l_1,\ldots , l_4 } j_{l - l_1}(x_a)j_{l - l_2}(x_a)j_{l - l_3}(x_b ) \times \nonumber\\ j_{l - l_4}(x_b ) ( \mu_{l_1}^{\dagger } - \nu_{l_1}^{\dagger})(\mu_{l_2 } - \nu_{l_2})(\mu_{l_3}^{\dagger}+ \nu_{l_3}^{\dagger})(\mu_{l_4 } + \nu_{l_4})\bigg ] |\boldsymbol{\tilde\varphi } ; -\boldsymbol{\tilde\varphi}).\end{aligned}\ ] ] since @xmath103 is a product of local coherent states we can ignore the sum over @xmath6 and discuss the expected behaviour .
firstly , both @xmath104 are much smaller than unity and the main contribution in the sums over @xmath105 will come from the zeroth - order bessel functions @xmath106 . secondly , the product of operators gives @xmath107 different combinations of the field operators .
but due to the prefactors , the combinations with equal indices are the most important .
they simply give an integer number when applied to the product of local coherent states they are acting on . taking these two points together , the time evolution of this state should show an approximate revival at @xmath108 this result is valid for large systems and can not account for the effect of non - universal properties like a limited number of particles and lattice sites , but we expect it to yield the right order of magnitude for finite systems , and in particular the correct scaling with the parameters of external potentials ( c.f .
, inset , below ) .
additional finite size corrections to can be understood by using the decomposition into the eigenbasis .
the evolution of the occupation of the upper band certainly depends on the initial state , which we can take into account by studying the weights @xmath109 of the initial state expanded in the eigenbasis .
the result of a numerical diagonalisation for a system in resonance is depicted in , where the absolute values of the expansion coefficients with their corresponding quasi - energies are shown .
for vanishing two - body interaction strength @xmath110 , the quasi - energies from the states with different occupation numbers are degenerate as expected .
the energy difference between neighbouring lines of constant quasi - energies corresponds to the time - scale of the resonant inter - band oscillations and follows from the diagonalisation of the resonant non - interacting system as @xmath111 . in the non - interacting system ( @xmath110 )
, two coefficients are dominating and the difference of the quasi - energies yields a single time - scale @xmath112 .
when the interaction is turned on , the weight of states with many contributions from double- or higher occupancies of sites decrease significantly ( since they are energetically disfavoured ) and their quasi - energies are slightly shifted .
but , surprisingly , only a limited number of additional coefficients @xmath109 contributes significantly in the eigenbasis expansion even for @xmath113 .
the observed collapse and revival signal is now determined by a few expansion coefficients that are much larger than the others .
if we focus on the three largest coefficients , denoted as @xmath114 and sorted by their quasi - energies @xmath115 , we find that the latter are shifted by the interaction by different amounts . the differences between neighbouring quasi - energies , @xmath116 and @xmath117 ( shown for the example @xmath118 in ) , lead to a beating between two oscillations with periods @xmath119 and the revival time will thus be given by @xmath120 this estimate requires a numerical diagonalisation but gives a clear physical interpretation to the revival time observed in a specific realisation with @xmath42 atoms on @xmath7 lattice sites .
thus , taking and together , we have an understanding of the general physical mechanism triggering the collapse and revival of the resonant two - band oscillations .
we compare our prediction for the revival time , and , to actual numerical simulations in .
we find that gives the right order of magnitude for the revival in a specific realisation , and , in particular , it shows the correct scaling behaviour with the depth of the optical lattice ( shown in the inset of ) .
additionally , shows that the corrections for specific sizes of the system are well accounted for by , which only slightly underestimate the revival times by a few percent .
this deviation could be corrected by including more than three participating states , extending in this manner the arguments which lead to .
+ in an experimental realisation , the shorter the collapse time @xmath78 the easier it could be observed , and for an estimate we make use of the fact @xcite that the collapse time is proportional to the revival time @xmath121 where @xmath122 denotes the width of the distribution of coefficients @xmath109 necessary to expand the initial state in the eigenbasis . for the specific example of @xmath123 and @xmath124
we find @xmath125 for the width of the distribution ( i.e. the @xmath126 couplings include just one or very few additional states as in the derivation of above ) , such that we estimate @xmath127 compared to @xmath128 found numerically . in this work ,
we focused on realisations with ultra - cold atoms in a tilted periodic potential , and the observed effect can be manipulated by engineering the potential @xcite or the two - body interaction @xcite .
specifically , the revival time depends sensitively on parameters as the hopping strength and the external force close to the zeros of the bessel function in .
this is analogous to already realised manipulations by time - dependent forces as predicted by @xcite and realized in @xcite .
the observation of bloch oscillations over thousands of periods and a fine control on the two - body interaction have already been demonstrated experimentally @xcite .
therefore , the collapse and revival of resonant inter - band oscillations predicted here should be accessible in such state - of - the - art experiments .
we finally remark that the collapse and revival phenomena discussed in this section have their origin ( cf . ) in the degradation ( due to interactions ) of single particle _
inter - band _ oscillations .
so , even if there are analogies to the collapses and revivals observed in other experiments @xcite , the collapse - revival oscillations reported there arise from the interaction within a single - band .
therefore , in contrast to our results , those oscillations would not at all occur when the lower band interaction is suppressed , equivalent to @xmath129 in the model here discussed .
_ summary .
_ we studied the coupling between two energy bands in a two - band bose hubbard model with an additional tilting force .
the force can lead to a strong coupling of the bands and we found strong resonances in the inter - band oscillations in this lattice model .
furthermore , the two - particle interaction leads to a collapse and revival of the resonant inter - band oscillations . here , we made predictions for the relevant time scales which were verified numerically .
+ a closed two - band system is an idealisation , but it can approximately be realised in various parameter regimes with ultra - cold atoms @xcite using different techniques as e.g. super lattices @xcite .
in addition , the use of feshbach resonances allows a complete control and fine tuning of the interaction strength @xcite needed to test our predictions .
our work is a first important step in going beyond ground - band physics and accessing more degrees of freedom in bosonic ultra - cold gases .
this work was supported within the framework of the excellence initiative by the german research foundation ( dfg ) through the heidelberg graduate school of fundamental physics ( grant number gsc 129/1 ) , the frontier innovation fonds , and the global networks mobility fund .
p.p . is grateful to andrea tomadin and acknowledges support from the klaus tschira foundation . | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | 80 gustavsson m _ et al ._ 2008 interference of interacting matter waves _ preprint _arxiv:0812.4836 will s _ et al . _ 2009 multi - orbital quantum phase diffusion _gustavsson m __ 2008 , 080404 bloch i , dalibard j and zwerger w 2008 885 bloch i 2008 nature * 453 * 1016 greiner m , mandel o , hnsch t w and bloch i 2002 nature * 6902 * 51 giovannetti v _ et al ._ 2004 science * 306 * 1330 ; esteve j _ et al ._ 2008 nature * 455 * 1216 - 1219 .morsch o and oberthaler m 2006 179 ; zenesini a _ et al ._ 2008 053038 morsch o __ 2001 140402 tomadin a , mannella r and wimberger s 2007 130402 salger t __ 2007 190405 ; salger t __ 2009 science * 326 * 1241 breid b m , witthaut d and korsch h j 2006 110 tomadin a , mannella r and wimberger s 2008 a * 77 * 013606 tomadin a 2006 _ quantum chaos with ultracold atoms in optical lattices _ , ( master thesis , universit di pisa ) fukuyama h , bari r a and fogedby h c 1973 b * 8 * 55795586 kolovsky a r and buchleitner a 2003 e * 68 * 056213 press w __ 1992 _ numerical recipes in c _( cambridge university press ) nakamura y , pashkin y a and tsai j s 2001 246601 meystre p and sargent m 1991 _ elements of quantum optics _ ( springer ) abramowitz m and stegun i a 1968 _ handbook of mathematical functions _ ( dover publications ) buchleitner a , delande d and zakrzewski j 2002 _ physics reports _ * 368 * 409 547 eckardt a , weiss c and holthaus m 2005 260404 zenesini a _ et al ._ 2009 100403 anderlini m _ et al ._ 2006 s199 ; sebby - strabley j _ et al ._ 2007 200405 |
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– In a sign that the "billion dollar divorce" saga might actually be over before the only billionaires involved are lawyers, the Oklahoma Supreme Court has ruled against Sue Ann Hamm, the ex-wife of oil tycoon Harold Hamm. In a 7-2 decision, the court decided that since Sue Ann Hamm cashed a $974 million check from her ex-husband earlier this year, she no longer had the right to appeal the settlement, NBC News reports. Sue Ann Hamm, who was married to Harold for more than 20 years, was seeking a bigger slice of an estimated $18 billion fortune, reports the AP. The court ruled that Harold can still appeal the settlement, which also awarded Sue Ann three of their homes, if he chooses. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | One chapter in the "billion dollar divorce" has ended, and Oklahoma oil tycoon Harold Hamm has won, if you can call paying one of the largest divorce settlements ever a victory. The Oklahoma Supreme Court on Tuesday dismissed the appeal of his ex-wife Sue Ann Arnall over the $974.8 million a judge ordered Hamm to pay her in November, according to reports. Both Arnall and Hamm appealed that earlier decision. Arnall's appeal argued that she deserved more of the nearly $18 billion in wealth Hamm had amassed (at the time) as founder of Continental Resources Inc. Hamm and Arnall were married for more than two decades. She filed for divorce in 2012. The Oklahoma Supreme Court, in a 7-2 decision, ruled on Tuesday that since she cashed the check in January, she forfeited her right to appeal, The Associated Press said. The two dissenting judges said the law was old-fashioned. The court did not dismiss Hamm's appeal. Play Facebook Twitter Embed Harold Hamm: No tie to fracking and Oklahoma earthquakes 2:14 autoplay autoplay Copy this code to your website or blog -- The Associated Press contributed to this report. ||||| OKLAHOMA CITY (AP) — The Oklahoma Supreme Court has dismissed an appeal by the ex-wife of billionaire energy tycoon Harold Hamm in their near-$1 billion divorce settlement. In a 7-2 decision Tuesday, the state's highest court ruled in favor of Hamm, the chairman and CEO of energy giant Continental Resources Inc. and granted his motion to dismiss the appeal by Sue Ann Hamm. The couple was married for more than 20 years before Sue Ann Hamm filed for divorce in 2012. An Oklahoma County judge in November approved the couple's divorce settlement, which included an award of nearly $1 billion to Sue Ann Hamm. But Sue Ann Hamm appealed, arguing that the amount was only a fraction of the couple's estimated $18 billion wealth. |
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– Minecraft gamers kicked into real-life survival mode on Sunday when a fellow player who IDed himself as a teen "crippled" by depression and social anxiety posted desperate messages on Reddit. NotARomanGuy, who plays Minecraft using the CaesarOctavius handle, posted two notes to Reddit Sunday. One posted on r/UltraHardcore began "tonight, I am taking my life." In that post and the second, he relayed his eight-year struggle with depression and called himself "an unliked outcast at school," "unloved in my family and not appreciated in any other groups," "inadequate and meaningless, hated and worthless." He added, "Even my mother told me she doesn't want me in her life" and said, "I just want to know what it's like to be appreciated. To be liked. To be loved." The Reddit community gave him the chance to experience those feelings by rallying to his support on both the SuicideWatch and UltraHardcore subreddits, offering words of encouragement and imploring him to seek help. One user created a Minecraft homage to NotARomanGuy's avatar, while more than 50 others joined a voice conference to talk him out of it, according to Mashable. The next day, he expressed his gratitude in a couple of follow-up Reddit posts: In one he mentions his "extremely tough" night, adding, "Thanks for all the support; it was overwhelming and it saved my life. I love you all." Meanwhile, in his second online "thank you," he assures other posters he'll be consulting with a school counselor about selecting a psychiatrist and tells others to "ask people how they're doing before it's too late, because it was almost too late for me. Everyone fights their own battles." Read his heartfelt messages in their entirety here and here. (Meanwhile, a 29-year-old is planning to take her own life for a very different reason.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. |
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dipole , triangular , and higher harmonic flow that have an origin in the initial density fluctuations has gained a lot of attention as they can provide additional important information about the dynamical properties ( e.g. viscosity ) of the system .
the fluctuations in the initial geometry should be also reflected in the detail shape and velocity field of the system at freeze - out . in this
talk i discuss the possibility to measure such fluctuations by means of identical and non - identical particle interferometry .
the initial spatial conditions in heavy ion collisions are not azimuthally symmetric .
due to particle rescatterings it leads to the anisotropic flow
anisotropies in particle momentum distributions with elliptic flow being the well known example .
recently , a significant progress has been reached in understanding the role of the initial density fluctuations .
in particular it was realized that such fluctuations lead to odd harmonic anisotropic flow , studying of which brings new insights into dynamics of the system evolution .
below , i briefly summarize recent developments .
i apologize for not providing the full list of references many of which can be found in other proceedings of this conference . an importance of the initial state fluctuations for flow development has been noticed in @xcite , though the exact relation between fluctuation and the final event anisotropies were not clear . in
@xcite an observation was made that non - zero two - particle rapidity correlations ( as observed in @xmath0 collisions ) in conjunction with radial flow ( accepted part of the system evolution in @xmath1 collisions ) lead to a narrow in azimuth and long ranged in rapidity correlations .
such correlations were observed experimentally and called _
ridge_. this mechanism ( non - zero `` primordial '' rapidity correlations + radial flow @xmath2 ridge ) have been exploited later in several other models that try to address in more detail a ( more subtle ) question of the origin of the `` primordial '' rapidity correlations .
although the appearance of the ridge and anisotropic flow fluctuations look as totally unrelated phenomena , they appeared to be different views on the same thing
reaction of the system to the fluctuation in the initial density . in
@xcite it was shown explicitly that the fluctuations in the initial density distribution that extends over large rapidity range lead to the ridge structure in two particle correlations .
it was also noticed that after subtraction of the expected contribution from elliptic flow , two - bump structure appears on the away - side .
further studies @xcite with a single hot spot
embedded into otherwise smooth background appeared quite revealing .
contrary to an expectation @xcite that such a hot spot moved out by the radial flow would create a `` bump '' in azimuthal distribution it appeared that that the hot spot actually `` blocks '' the development of the radial flow and leads to a `` dip '' in particle distribution at the corresponding azimuth , accompanied by side - splashes from both sides .
remarkably , in terms of the correlation function the `` bump '' and the `` dip '' leads to the same structure - the ridge , as both means _ positive _ correlations . at the same time , the exact shape of the correlation function ( e.g. the strength of the third harmonic , which is important below ) is different .
it was noticed in @xcite that the fluctuating initial conditions generate anisotropic flow of different harmonics . that followed by understanding @xcite that the perturbations due to each of the hot spots can be treated independently , which allows to reformulate the problem from a different perspective
decompose the initial density into multipoles and study the system responce to each of the multipoles - the approach widely discussed at this conference as flow ( dipole , triangular , quadrangular , etc . )
fluctuations .
one can envision such an approach as rotating each of the event to a given harmonic symmetry plane , such that at the end one could have a smooth initial conditions but with a shape corresponding to a given harmonic .
the question addressed in this talk is if with the help of femtoscopy ( identical and non - identical two - particle correlations ) one can directly observe such triangular etc .
shapes of the system . in this study
i follow an approach of the first papers where the azimuthally sensitive femtoscopic analyses have been proposed @xcite , and blast wave and ampt models calculations . for typical values of parameters used in this work . ,
title="fig:",width=207 ] for typical values of parameters used in this work .
, title="fig:",width=192 ] for typical values of parameters used in this work .
, title="fig:",width=226 ] intensity interferometry ( identical particle femtoscopy ) , measures particle space - time distribution at freeze - out . due to the probe on - mass constraint
, the full space - time information can not be obtained , and one can access only the distribution in @xmath3 , where @xmath4 is the particle position at time @xmath5 ( after freeze - out ) , and @xmath6 is the particle velocity . for a gaussian source , the correlation function appears to be a gaussian c ( , ) 1 + _ i , j r_ij^2 q_i q_j , where @xmath7 is the pair relative momentum , @xmath8 is the particle average momentum , and @xmath9 are the hbt radii .
the deviation from a gaussian form can be studied by evaluating the higher moments of the distribution ( for the effect of non - gaussiness on hbt radii , see @xcite ) .
detailes of femtoscopic analyses can be found in a review @xcite .
we use a standard side - out - long system @xcite ( see figure [ fig : coordinates ] ) and concentrate on azimuthal dependence of the side , out , and side - out radii . for a _ stationary _ ( not expanding ) source
the radii azimuthal dependence can be expressed as r_side^2= = ^2+^2 - 2 , which has only @xmath10 harmonic .
higher harmonics azimuthal dependence appears only as deviation from the gaussian , e.g. in @xmath11 and @xmath12 for triangular and quadrangular shapes respectively .
the picture changes if one considers azimuthal variation in the expansion velocity . to study this effect
we employ a blast wave model .
we assume longitudinally boost invariant source and freeze - out at a constant temperature @xmath13 mev .
expansion velocity profile is parametrized in a form _ t(r,)=_t , max[1+a_boost ( n ) ] , + r_max = r[1+a_space ( n ) ] , with direction of the collective velocity being perpendicular to the line @xmath14 $ ] going through the emission point .
the parameter @xmath15 which corresponds to an average expansion velocity @xmath16 and @xmath17 gev . @xmath18 and @xmath19 parameters define the spatial eccentricity at freeze - out and modulation in the expansion velocity . for the first we assume that the system spatial eccentricity is reduced about two times during the system evolution , which leads to @xmath20
; @xmath19 can be estimated from @xmath21 dependence and is taken to be in the range 0.03 - 0.07 .
the azimuthal dependence of the obtained hbt radii , see figure [ fig : bwradii ] , indicates that the higher harmonics shape effects become clearly visible ( and measurable ) .
note the difference in the amplitudes of @xmath22 terms .
the radii modulation strongly depends on the parameters of the model , and the correspondng measurements will be very important in evaluating the velocity profiles at freeze - out and testing models . the ampt model @xcite has been extensively used in studying the effect of the initial state fluctuations .
we use this model to study au+au collisions at = 200 gev .
figure [ fig : amptradii ] shows the hbt radii variation as function of the azimuth relative to a given harmonic _
event plane _ which includes the effects of finite reaction plane resolution .
once again , the radii dependence on the azimuth is clearly seen . a detailed investigation of the side - out relative phases , dependece on the particle transverse momentum , etc .
requires additional investigations . , at @xmath23 .
, title="fig:",width=219 ] , at @xmath23 . , title="fig:",width=219 ] , at @xmath23 . ,
title="fig:",width=219 ] using the blast wave and ampt models we have demostrated the possibility of femtoscopic higher harmonics system shape analysis that promices new insights into the physics of heavy ion collisions . | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | 10 c. e. aguiar , y. hama , t. kodama , t. osada , nucl .* a698 * , 639 - 642 ( 2002 ) . s. a. voloshin , phys .* b632 * , 490 - 494 ( 2006 ) .* a749 * , 287 - 290 ( 2005 ) . j. takahashi et al . phys .lett . * 103 * , 242301 ( 2009 ) .r. p. g. andrade , f. grassi , y. hama , w. -l .qian , nucl .* a854 * , 81 - 88 ( 2011 ) .a. p. mishra , r. k. mohapatra , p. s. saumia , a. m. srivastava , phys .rev . * c81 * , 034903 ( 2010 ) .p. sorensen , j. phys .g * g37 * , 094011 ( 2010 ) .d. teaney , l. yan , [ arxiv:1010.1876 [ nucl - th ] ] .s. a. voloshin , w. e. cleland , phys . rev . *c53 * , 896 - 900 ( 1996 ) .phys . rev .* c54 * , 3212 - 3217 ( 1996 ) .s. voloshin , r. lednicky , s. panitkin and n. xu , phys .* 79 * , 4766 ( 1997 ) .d. hardtke , s. a. voloshin , phys .rev . * c61 * , 024905 ( 2000 ) .m. a. lisa , s. pratt , r. soltz , u. wiedemann , ann .nucl . part .* 55 * , 357 - 402 ( 2005 ) .b. zhang , c. m. ko , b. -a .li , z. -w .lin , phys .rev . * c61 * , 067901 ( 2000 ) . |
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– A woman hospitalized after she was hit by a falling tree while protecting her three young sons is suing New York City and the Central Park Conservancy for $200 million, WABC reports. According to ABC News, 39-year-old Anne Monoky Goldman was pushing two of her children, ages 4 and 2, in a stroller while her 41-day-old infant was strapped to her chest Aug. 15 in Central Park when a 75-foot-tall elm tree fell on them. Monoky Goldman was pinned under the tree for 10 minutes or so before being rescued. "They had to go take her out with chainsaws," a witness told the New York Daily News at the time. Her lawyers say she suffered spine and neck injuries and a concussion. Her 2-year-old son was treated for a brain hemorrhage and concussion. In the lawsuit filed this week, lawyers claim the tree fell because it was decayed underground, posed a danger to all park visitors, and hadn't been properly maintained or inspected. Monoky Goldman was released from the hospital last week, but her lawyers say she has to lay flat in bed for the next two to three months while her neck fractures heal. They say she may not be able to walk again. "She can't pick up her baby, she can't breast-feed, she can't do her job" doing social media for Tory Burch, one attorney tells the Daily News. The city is reviewing the lawsuit. (A pregnant woman was killed by a falling tree in an NYC park in 2013.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| There's a big new development Tuesday night in the story of the mother who last month saved her three children from a falling tree in Central Park.She saved them by taking the brunt of crashing tree. August 15th is the last time this 2-month-old baby boy was held by his mother, seen being placed into an ambulance in Central Park.It's the day a 75-foot tree snapped, falling on 39-year-old Anne Monoky Goldman and her three sons at Central Park West and West 62nd Street."Ms. Monoky risked her life and body to save her children and she has paralysis threatening injuries," said Jordan Merson in a written statement, the attorney for the Midtown mother.He plans to file a $200-million notice of claim against the city and the Central Park Conservancy for the American elm that the conservancy found uprooted because of decay beneath the surrounding pavement.Monoky Goldman just got out the hospital a week ago, but cannot get out of bed. Her attorney says she has to lay flat for two to three months, with her neck and back immobilized, in order for her neck fractures to heal.Her 2-year-old son is recovering from a brain hemorrhage and a concussion.And not only is Monoky Goldman unable to her hold her infant, she also is unable to nurse him, losing out precious bonding between a mother and newborn son. |
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– It's a crime of some passion in Syracuse, just down the road from the birthplace of the Buffalo chicken wing: Father and son Paul Rojek and Joshua Rojek stand accused of pilfering a squawk-worthy $41,000 worth of wings from the restaurant where they worked, and as the Post-Standard reports, they apparently managed to do it in a 10-month spree that ended in late November with criminal charges. Police say the Rojeks billed the wings to the business account of the Twin Trees Two Restaurant, picked them up from the supplier, then sold them on the street and on the side to other restaurants at slashed prices, pocketing the proceeds. They're charged with third-degree grand larceny and first-degree falsifying business records. It's allegedly not the first time they pulled the caper, reports CNYCentral: They were charged last year with stealing chicken wings from another restaurant. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | SYRACUSE, NY -- Two employees of a Syracuse restaurant are accused of stealing more than $40,000 in chicken wings and selling them to other restaurants and "on the street" for a poultry sum, according to the Onondaga County Sheriff's Office. Sheriff's office spokesman Jon Seeber said Paul Rojek, 56, and Joshua Rojek, 33, of Syracuse, billed approximately $41,000 of chicken-wing orders to the Twin Trees Two restaurant's business account between February and late November. The father-son pair was employed there as cooks, Seeber said. The pair would pick up the orders and re-sell them on the street or to other local establishments for a reduced price. They would later destroy and withhold the sales transactions receipts for those orders, Seeber said. They're facing charges including grand larceny in the third degree and falsifying business records in the first degree. They appeared in court Nov. 24 where a judge set their bail at $2,500 cash or bond. ||||| SYRACUSE, N.Y. -- A father and son found themselves in hot water after police busted their chicken wing racket last month, according to the Onondaga County Sheriff's Office. Police say 56-year-old Paul Rojek and 33-year-old Joshua Rojek started the racket while they were employed as cooks at Twin Trees Too Restaurant on Milton Avenue. The duo allegedly developed a system where they would order chicken wings from the restaurant's supplier, pick up the orders and re-sell the chicken on the street or to other local businesses for a reduced price, according to police. From February to November, the father and son were able to hide $41,000 worth of product. Both men are charged with third-degree grand larceny and first-degree falsifying business records. This is not the first time the father has been arrested for this same crime -- According to the Onondaga County Sheriffs' Office, he was arrested for allegedly stealing chicken wings from Dominick's restaurant in 2014. |
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– If the public sector won't have him, Mitt Romney is fine returning to the private one: He is taking a new post with son Tagg's venture capital firm, reports NBC News. Romney will serve as chair of Solamere Capital's executive committee, which translates into about a week of work per month advising on private-equity decisions. Letters have gone out to top investors, reports AP, which notes that Romney already was a limited partner at the Boston company. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Mitt Romney has a new position with his son's Boston-area venture capital firm. Last year's Republican presidential nominee will serve as chairman of the executive committee for Solamere Capital. The firm was founded by Romney's oldest son, Tagg, and the national finance committee chairman for his presidential campaign, Spencer Zwick. Romney has been a limited partner in Solamere, and investors have been sent letters announcing his elevated role. The Associated Press obtained a copy of one of the letters on Wednesday. Romney has just begun to emerge from months of isolation at his home in southern California. In a Sunday television interview, he said "it kills me" to have lost the presidential race. He delivers his first public speech since the loss next week in Washington. ||||| Former Massachusetts governor and GOP presidential nominee Mitt Romney will be working at his son Tagg's investment firm, Solamere Capital, for one week a month. NBC's Brian Williams reports. Former Massachusetts governor and Republican presidential nominee Mitt Romney has a new job. NBC News has learned that Romney is returning to the private sector, joining his eldest son Tagg's investment firm, Solamere Capital, as chairman of the executive committee. A person with knowledge of the deal tells NBC that Romney is planning to work with Solamere for one week a month. He will be advising on matters of private equity, and is not planning to fundraise at all for the firm. An email is expected to go out tomorrow heralding the news to top investors. Romney has held office space at Solamere, which is based in Boston, since the election. However, he has mostly spent time with his family since the loss, and has not been officially involved in business matters. His campaigns for president in 2008 and 2012 largely focused on his background in the business world. Romney founded asset management company Bain Capital in 1984. This story was originally published on |
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marijuana is one of the most frequently abused illicit substances in the world especially australia .
cannabinoid hyperemesis syndrome ( chs ) is characterized by a triad of symptoms : cyclic vomiting , chronic marijuana use , and compulsive bathing .
it involves recurrent episodes of self - limited nausea and vomiting lasting several days and patients are asymptomatic between episodes .
we believe that cannabinoid hyper emesis syndrome is much more common than currently recognized .
we present a unique case with an apparent positive family history of the same clinical entity . | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | marijuana 's medicinal use as an anti - emetic and appetite stimulant , especially in patients receiving chemotherapy , is well established . the first published cases of chs were reported in 2004 although an earlier case was reported in 1996 ; however , the authors did not specify cannabis use as the cause . cannabis has an active compound -9-tetrahydrocannabinol ( thc ) which acts on presynaptic brain receptors cb1 and cb2 , whereas , inhibition of gastric motility by 9-thc is primarily due to activation of the cb1 receptor in the vagal circuitry of the brainstem . while the mechanism of this syndrome remains unknown , there are hypotheses which fall into two categories 1 ) dose dependent build - up of cannabinoid and related effects of cannabinoid toxicity and , 2 ) the functionality of cannabinoid receptors in the brain and , particularly , in the hypothalamus ( which regulates body temperature and the digestive system ) . the enteric effects of marijuana ( e.g. , decreased gastrointestinal motility ) are thought to override the brainstem - mediated antiemetic effects to promote emesis ; however , this does not fully explain antiemetic action of cannabis . it is also suggested that instead of 9-thc , other lipid - soluble components of marijuana such as non - intoxicating cannabinoid could induce vomiting , since high doses of this compound have been reported to cause emesis in the house musk shrew . the desire for hot showers is either to counteract the marijuana - induced decrease in core body temperature or is a direct response to cb1 receptor activation in the hypothalamus . considering the ambiguity of the role of marijuana in producing this syndrome , further research is warranted to enhance our understanding of the role of cannabinoids in gastric motility . considering the mass of case reports published so far and the possibility of familial effects , we wonder if it opens a portal for a new diagnosable entity . |
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– President Obama is back in DC after a two-week Hawaii vacation, and one detail of how he spent his 15th day in paradise is grabbing a few headlines: In addition to beach time and a visit to the National Memorial Cemetery of the Pacific (his mother's father is buried there), Obama and his girls visited with Pearl Jam lead singer Eddie Vedder on Saturday afternoon. The Washington Post reports that Vedder lives part-time in the state, also likes Chicago sports, and has rubbed shoulders with Obama before: The musician performed at a fundraiser for Obama in Florida in 2012 and managed to get in a birther joke, quipping that the ukulele he was playing had its own "little birth certificate." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| Eddie Vedder. No word on Obama's favorite Pearl Jam album. (AP Photo/Andre Penner) President Obama spent part of Saturday hanging out with Pearl Jam frontman Eddie Vedder. Obama and his daughters visited Vedder and his family, according to the White House. Vedder lives in Hawaii part-time and is an Obama supporter. He played a four-song set at a Florida fundraiser in 2012, trading in a mandolin for a Hawaiian ukulele. "It has a little birth certificate in there," Vedder joked. He recorded an album titled 'Ukulele Songs' in 2011. Vedder and Obama had another thing to talk about - they're both Chicago sports fans. But their politics have diverged at times. Vedder supported Green Party presidential candidate Ralph Nader in the 2000 presidential election. No word on what the two discussed or Obama's favorite Pearl Jam album. Our vote is for 'Ten.' Obama made a number of other stops during the final hours of his Hawaii vacation Saturday. Obama, Malia and Sasha spent about 20 minutes at the Honolulu home of his half sister, Maya Soetoro-Ng. . The president and his daughters also spent time at the Punchbowl Memorial Cemetery of the Pacific, where his maternal grandfather is buried. Obama and his family will return to Washington Sunday. |
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– As doctors bring Joan Rivers out of a medically induced coma, there's some concern the comedian could end up "either a vegetable or in a wheelchair," the New York Daily News reports. That news has her family considering a lawsuit. Whether or not Rivers, 81, has suffered brain damage won't be evident until she wakes up, which could happen today; she's been on life support since Sunday. Rivers' condition—following cardiac and respiratory arrest during an outpatient, routine throat surgery last week—has left her daughter, Melissa, "totally hysterical," a source tells the Daily News. "Shock and upset is turning to anger, and they are looking for someone to blame," says the source. The legal threats are directed at Yorkville Endoscopy on the Upper East Side, which Rivers' family claims botched the surgery on her vocal cords Thursday, the Washington Times adds. "The night before she was performing, and now she is on life support. An 81-year-old should not have that procedure as an outpatient. Very ill-advised," says one family member. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Joan Rivers‘ family is mulling whether or not to sue the medical facility that performed her throat surgery, alleging doctors botched the job and sent her into a coma and onto life support. Ms. Rivers also suffered a heart attack during the surgery, which family members say was supposed to be routine. “The night before she was performing and now she is on life support,” one family member told the New York Daily News. “An 81-year-old should not have that procedure as an outpatient. Very ill advised.” PHOTOS: Celebrity deaths in 2014 Ms. Rivers had been undergoing an endoscopy at a clinic when she was rushed to Mount Sinai Hospital in New York when her medical condition took a turn for the worse, The Telegraph reported. She was placed on life support over the weekend, and doctors warn that if she does recover, she cold face brain damage. Ms. Rivers‘ daughter, Melissa, 46, and grandson, Cooper, 13, are at the hospital, The Telegraph reported. “The waking-up process has begun and will take until Tuesday,” one source close t0 the family said to the New York Daily News. “There is real concern that the part of the brain that controls motor skills may have been compromised, leaving her as either a vegetable or in a wheelchair.” ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. |
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– The Air Force is cutting loose a staff sergeant who championed the debunked “birther” conspiracy theory online. Daryn Moran says he stopped reporting for duty at an Air Force base in Germany, arguing that his orders were invalid because Obama was an invalid president. “Now it’s plain and simple,” he tweeted Monday, according to the Omaha World Herald. “Arrest B. Obama, or arrest me.” But that was never going to happen, the Air Force Times reports, because he didn't actually go AWOL, as he claimed; Moran was already on approved leave. "He is currently outprocessing for discharge from the Air Force which was previously approved by his commander on August 4th," reads an Air Force statement. Moran’s birther antics weren’t the only thing that may have gotten him discharged; on Aug. 15 he wrote that mental health evaluators had recommended he be discharged “for a ‘personality disorder’” because he said homosexuality is a sin. A coworker had also complained after he asked a doctor in his unit about her Muslim faith—according to Politico, he’d made disparaging comments about Muslims, and Obama’s ties to the faith. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Web wide crawl with initial seedlist and crawler configuration from March 2011. This uses the new HQ software for distributed crawling by Kenji Nagahashi. What’s in the data set: Crawl start date: 09 March, 2011 Crawl end date: 23 December, 2011 Number of captures: 2,713,676,341 Number of unique URLs: 2,273,840,159 Number of hosts: 29,032,069 The seed list for this crawl was a list of Alexa’s top 1 million web sites, retrieved close to the crawl start date. We used Heritrix (3.1.1-SNAPSHOT) crawler software and respected robots.txt directives. The scope of the crawl was not limited except for a few manually excluded sites. However this was a somewhat experimental crawl for us, as we were using newly minted software to feed URLs to the crawlers, and we know there were some operational issues with it. For example, in many cases we may not have crawled all of the embedded and linked objects in a page since the URLs for these resources were added into queues that quickly grew bigger than the intended size of the crawl (and therefore we never got to them). We also included repeated crawls of some Argentinian government sites, so looking at results by country will be somewhat skewed. We have made many changes to how we do these wide crawls since this particular example, but we wanted to make the data available “warts and all” for people to experiment with. We have also done some further analysis of the content. If you would like access to this set of crawl data, please contact us at info at archive dot org and let us know who you are and what you’re hoping to do with it. We may not be able to say “yes” to all requests, since we’re just figuring out whether this is a good idea, but everyone will be considered. ||||| US troops, civilians killed in suicide attack in Syria Play Video |
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– Today's appearance by the NSA chief on Capitol Hill didn't produce many surprises—he said data mining is necessary and used in such a way that it doesn't invade privacy—but it did produce one strange moment featuring Sen. Barbara Mikulski. At one point, the Maryland Democrat paused the hearing to read a critical tweet from BuzzFeed reporter Rosie Gray—"@SenatorBarb is trying hard to keep the other senators from asking Gen. Alexander anymore about data mining programs.” Mikulski took exception, reports Politico. “Not everybody might be watching C-SPAN, so I want to say to Rosie and to others who might read it from Rosie: There is no attempt here to muzzle, stifle any senator from asking any line of questioning.” She also noted that the hearing was originally scheduled to talk about cybersecurity, not surveillance, "but any senator can ask any question at this hearing that they want to." Around that point, she smiled and picked up her smartphone. "So Rosie, it’s an open hearing. Hi. Look forward to keeping in touch.” (After which, Gray tweeted, "guess I should have subtweeted.") | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Who says senators aren’t tech-savvy? Sen. Barbara Mikulski (D-Md.) briefly halted her hearing for a moment Wednesday to respond to a tweet from BuzzFeed reporter Rosie Gray, which read: “@SenatorBarb is trying hard to keep the other senators from asking Gen. Alexander anymore about data mining programs.” Text Size - + reset Mikulski, the chairwoman of the Senate Appropriations Committee, had National Security Agency head Keith Alexander as well as FBI and Homeland Security Department officials before her on the issue of cyber security. But the news cycle had most senators looking for Alexander to address revelations of broad phone recordkeeping and Internet surveillance by the NSA — so most senators took the opportunity to ask Alexander about the surveillance anyway, with Mikulski interrupting several such inquiries. (PHOTOS: Pols, pundits weigh in on NSA report) After catching a glimpse of Gray’s Twitter critique, Mikulski said, “Not everybody might be watching C-SPAN, so I want to say to Rosie and to others who might read it from Rosie: There is no attempt here to muzzle, stifle any senator from asking any line of questioning.” “We’re here on cyber, but any senator can ask any question at this hearing that they want to. So Rosie, it’s an open hearing,” she said, smiling and holding up her smartphone. “Hi. Look forward to keeping in touch.” The chairwoman got some bipartisan back-up: Sen. Dan Coats (R-Ind.) said Mikulski had been “extremely tolerant of our diversion” from the subject of cybersecurity. Mikulski had warned as the hearing began that NSA questions are for “another day”: Thursday, when all 100 members of the Senate will have the opportunity to meet with Alexander — behind closed doors. ||||| Tweet with a location You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more |
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– Note to movie makers: Give the police a heads-up when filming a robbery scene in public. Newly released police bodycam video released by the city of Crawfordsville, Ind., shows how close one actor came to learning that lesson in the worst possible way. Officers responded to a robbery call at a local bar when someone spotted a masked gunman entering. Cops arrived just as actor Jim Duff was stepping back out, holding a fake gun, and an officer fired a shot when he didn't immediately drop his weapon as ordered, reports ABC 7. Luckily, the bullet didn't hit him. "We're doing a movie," Duff can be heard trying to explain as officers order him to get on the ground. Police ended up holding him in custody until they confirmed that he was, in fact, part of a movie being filmed. No charges will be filed related to the incident, reports the Journal & Courier. "We ask, for obvious safety purposes, that our department be notified of future instances where toy or prop weapons are going to be used," said a city statement. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. ||||| New video shows the moment an Indiana police officer confronted and shot at a man he thought was robbing a business.The incident happened last week in Crawfordsville, when police responded to a 911 call about a robbery at Backstep Brewery. The caller told dispatchers that a man in a ski mask entered the bar with a gun.Sgt. Matt Schroeter arrived at the location and saw a man in a ski mask backing out the door. He appeared to be holding a weapon. The "robber" was actually actor Jim Duff, who was filming a scene for a movie.But Schroeter didn't know that."Drop the gun! Drop the gun now!" Schroeter yells in body camera footage released after the incident. Duff then turns toward the officer and takes off his mask; Schroeter fires a shot and repeats his orders for Duff to drop his weapon."We're doing a movie," Duff says after taking off the ski mask and dropping the weapon.The officer then orders him to get on the ground. Duff complies and then yells to someone inside the bar, "You guys better get out here, man."Someone starts to come out the door, but the officer tells them to stay inside.Police said neither the production company nor the bar owners told them that a movie was being shot in the area. It didn't help that the other actors and filming equipment were inside the business, making it difficult to know that a movie was being shot.Duff was placed into custody until police could confirm that he was part of a movie scene."We could not see the police, so when the actor left the building we had no knowledge any police had even arrived at the scene," Montgomery County Movies owner Philip Demoret told CBS4.No charges were filed in connection with the case. Demoret said he planned to work with Crawfordsville police so that something like this doesn't happen again. |
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– A young American basketball player on a pro team in Romania has died after being attacked in a bar, reports AP. Chauncey Hardy, who played for CSS Giurgiu in southern Romania, was celebrating after a home win when he was apparently attacked by several men Saturday night. Hardy, 23, suffered severe injuries in the attack and was in a coma when he was brought to a local hospital. He suffered two heart attacks before dying last night in the hospital. A local man wanted in the attack has already turned himself in to police. He said he attacked Hardy because the basketball player wanted to dance with his girlfriend. "We are deeply saddened by the loss of a fine young man who had his life cut short at such a young age while he was overseas doing something he loved," said the athletic director at Sacred Heart college, where Hardy played before going pro. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Authorities say American basketball player Chauncey Hardy has died after being attacked in a bar in Romania. Carmen Tocala, chief of the Romanian Basketball Federation, told GSP radio that Hardy died Sunday evening after suffering two heart attacks _ a day after he was beaten up Saturday night. "We are deeply saddened by the loss of a fine young man who had his life cut short at such a young age while he was overseas doing something he loved," said C. Donald Cook, athletic director at Hardy's former college Sacred Heart. Police spokeswoman Mirela Gheta said the 23-year-old Hardy had sustained severe head injuries and was in a coma when he was admitted to the hospital. Hardy died shortly after undergoing surgery in a Bucharest hospital. Hardy, who played for CSS Giurgiu in southern Romania, was celebrating victory over rivals Dinamo Bucharest in Giurgiu when several men were reported to have attacked him. "This is a terrible tragedy and we are saddened as a University and a basketball program," Sacred Heart men's basketball coach Dave Bike said in a statement. "This is not just about a basketball player, but the person as well. It transcends what happens on a basketball court. We feel tremendous sadness and loss for Chauncey's family and those who were close to him." Hardy averaged 12.5 points for Sacred Heart in 2009-10. ||||| Romanian prosecutors say a man has been detained over the killing of American basketball player Chauncey Hardy. Ionut Adrian Tanasoaia surrendered to police early Monday. He is accused of beating up Hardy in a bar in the southern Romanian city of Giurgiu on Saturday night. Mediafax new agency reported Tanasoaia attacked Hardy because he wanted to dance with his girlfriend. Hardy died shortly after undergoing surgery in a Bucharest hospital on Sunday. The 23-year-old player had sustained severe head injuries and was in a coma when he was admitted to the hospital. Hardy played for CSS Giurgiu in southern Romania. |
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– It appears something good came of Derek Carr's broken leg, which arguably cost his Oakland Raiders a win in the first round of the NFL playoffs. Instead of spending Saturday taking on the New England Patriots, the quarterback retweeted a notice about a missing Oakland toddler to his 247,000 Twitter followers, the San Francisco Chronicle reports. Police say one Twitter user saw the Amber Alert message and called 911 after seeing a car matching the description, leading to police finding the child safe. "So it appears the secret to sharing local missing child info is a [retweet] by your local NFL QB," Lt. Chris Bolton tweeted. Carr responded to thank the police for "letting me know they are safe." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Oakland police thank Derek Carr for assist in locating missing Amber Alert toddler Oakland Raiders quarterback Derek Carr, #4, waves to the crowd at the end of a game against the Carolina Panthers which ended in a Raiders victory, of 35-32, at the Oakland Colliseum, in Oakland, California, on Sunday November 27, 2016. less Oakland Raiders quarterback Derek Carr, #4, waves to the crowd at the end of a game against the Carolina Panthers which ended in a Raiders victory, of 35-32, at the Oakland Colliseum, in Oakland, California, ... more Photo: Gabrielle Lurie, The Chronicle Photo: Gabrielle Lurie, The Chronicle Image 1 of / 14 Caption Close Oakland police thank Derek Carr for assist in locating missing Amber Alert toddler 1 / 14 Back to Gallery A retweet may not seem like much but, when you're as famous as Derek Carr, sometimes it's enough to have a huge impact. Such was the case on Saturday, when an Amber Alert was issued for a missing Oakland toddler. The Raiders quarterback, who's a dad of two himself, retweeted the alert to his 247,000 followers. And it paid off. Oakland police say they were contacted on Twitter by an alert citizen who had seen the Amber Alert there and noticed a vehicle matching the description in it. Police located the boy and returned him safely to his mother. @OPDChris great news! Thank you for letting me know they are safe! God bless y'all! — Derek Carr (@derekcarrqb) January 15, 2017 "So it appears the secret to sharing local missing child info is a RT [retweet] by your local NFL QB," Oakland police lieutenant Chris Bolton tweeted. "Thank you, @derekcarrqb!" MORE: Raiders aim higher in 2017 after breakthrough season Carr is spending his offseason recovering from a broken leg — and apparently helping broadcast important community messages. Quite the assist, Derek. ||||| I strive to embody the values of my department and profession. Currently on a Twitter hiatus. See & for official public information. |
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– Robin Wright is having a good run of late: The 47-year-old actress is up for a Golden Globe tonight for her role on House of Cards, and as E! reports, she's rocking a little extra bling in the way of an engagement ring courtesy of beau and fellow actor Ben Foster. It's the third time down the aisle for Wright and the first for Foster, 33, who is starring in a forthcoming Lance Armstrong biopic. The pair met on the set of Rampart. Wright's ex Sean Penn (who once said after their divorce, "She is a ghost to me now") is stepping out with his own new flame: Radar reports that he was looking cozy last night with Charlize Theron at a Haiti benefit. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Charlize Theron and Sean Penn couldn’t take their eyes off each other Saturday night at a lavish fundraiser for his charity, The pair, who have been dating just a few weeks, attended the Sean Penn & Friends Help Haiti Home Gala, in Beverly Hills. PHOTOS: Charlize Theron & Sean Penn Go Public As A Couple The twosome was first spotted together in Hawaii. Then, last Sunday, they were seen out on a movie date in Hollywood. Last night, they walked the red carpet separately but sat together, gazing at each other, often giggling, and occasionally sharing a kiss. Penn kissed her on the neck and she had her arms wrapped around his neck, a source told E! PHOTOS: Charlize Theron Takes Her Son For A Buzz Cut He even introduced Theron to his mom, Eileen Ryan Penn, who sat with them. It must be serious! ||||| The night before, the lovebirds made their first appearance since getting engaged at a party at the Chateau Marmont with Dylan. A source reveals to E! News that the couple was really "sweet" with each other. "They're both just really cool," the source said. "They were talking to people but weren't over doing it with PDA. They would have their arms around each other and were so chill." Wright and Foster costarred in the 2011 crime drama Rampart and reports began to surface that they were a couple after they were spotted getting cozy in February 2012. Wright can be seen as Kevin Spacey's conniving wife on the Netflix series House of Cards, while Foster is starring in the upcoming Lance Armstrong biopic. This will be the third marriage for Wright, she was previously married to Sean Penn for 13 years and Dane Witherspoon for 2 years. This will be the first marriage for Foster. Congrats to the happy couple! —Reporting by Marc Malkin and Katie Rhames |
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– Jennifer and Sam share the same blood type and birth date, down to the year, but that's not what makes them a perfect match. In a video posted to YouTube by Jennifer's employer, HSBC Bank—pointed out by Mashable—the Taiwanese couple explain they make each other better people. Over 11 years together, Sam says Jennifer has made her "more positive," while Jennifer says Sam "gets me to explore the beauty of this world." That's why the two weren't willing to let Taiwanese law stop them from declaring their love for each other in a wedding ceremony on Nov. 13, just as Jennifer wasn't going to let her parents' objections keep her from walking down the aisle. Luckily, she wasn't alone. Though her parents no longer speak to her, "my boss and colleagues have been very supportive," says Jennifer. In fact, when she told HSBC's Taiwan CEO John Li that her dad wouldn't be there to walk her down the aisle, he offered to step in. He "told us not to be nervous and to walk slowly," she recalls. "We cried because we never thought we would make it this far." While same-sex marriage is not yet legal in Taiwan, Jennifer says a ceremonial wedding was better than "faking a marriage for my father's sake," something she previously considered. Still, she hopes to one day make her father proud. For now, though, the couple have one goal: to "create respect among different communities." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Being gay can be especially tough in some conservative Asian cultures, but supportive workplaces can make all the difference. This video posted by HSBC Bank in Taiwan tells the story of one of its employees, Jennifer. In an interview segment in the video, she reveals that her parents don't acknowledge her relationship with her partner, and refused to attend their wedding. So the bank's country CEO, John Li, walked her down the aisle on her big day. The touching video also talks about Jennifer's 11-year relationship with her partner, Sam. Image: hsbc now/youtube "My parents are strongly against it," says Jennifer. "Whenever my father sees Sam, he will push her out and tell her to get lost." Jennifer adds that her biggest worry about coming out was that it would affect her work. "I was concerned that it would stop clients banking with [us]. So I considered it very carefully," she says. However, her colleagues have come out in full support of her. Image: HSBC NOW/YOUTUBE "CEO John was willing to walk me down the aisle, [he even] told us not to be nervous and to walk slowly," she says. Taiwan has not legalised same-sex marriages, so the couple's wedding is ceremonial. But Jennifer notes that she hopes her story will encourage others LGBTQ couples facing the same pressures. "This wedding is really for the LGBTQ community," says Jennifer. "We hope our actions will encourage people and create respect among different communities." This is not the first time HSBC has made a big show of support for LGBTQ couples. Earlier last year, it unveiled a pair of rainbow lions in front of its Hong Kong office as part of its "Celebrate Pride, Celebrate Unity" campaign. "This campaign demonstrates our commitment to achieving a truly open and diverse working environment," said HSBC Group general Kevin Martin in a statement. ||||| Go to the Legal Help page to request content changes for legal reasons. |
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– If you just hate the idea that someone can let a camera crew follow them around and end up a millionaire, do not read on. Celebuzz rounds up the 10 richest reality stars: Kim Kardashian: Not only is she one of the richest reality stars, she's also the second highest paid woman on TV—period. Snooki: Yes, the Jersey Shore star makes it on the list. She made a reported $150,000 per episode for the last season of the show, plus she has tons of endorsements and other projects. Simon Cowell: He made $90 million in 2012, but at least he's not slacking. He's behind both American Idol and X Factor, and he also has a record label. Donald Trump: The real estate mogul didn't exactly need any more money, yet he makes a reported $3 million for every Apprentice episode. Britney Spears: From pop star to reality star? The singer reportedly made $15 million for the one season of X Factor she did. Click for the complete list, which includes yet another Kardashian and multiple Real Housewives. Or if you'd rather, check out the highest-earning American Idol stars. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Hollywood Rich List How much do these celebs make - and how are they spending it? MORE >> A career in reality TV isn’t as bad as it used to be. Just ask anyone from The Real Housewives franchise, or the party animals of Jersey Shore. Nicole “Snooki” Polizzi and some of her MTV pals were treated to a big raise, making as much as $150,000 per episode during Jersey Shore’s final season. And that doesn’t include Snooki’s new spinoff with her BFF Jenni “JWoww” Farley, now in its second season. Being a judge on American Idol or The X Factor pays off too. While Simon Cowell’s $90 million in earnings (reported by Forbes in May 2012) comes from a variety of roles — and different continents — his heart and soul is in reality TV. Ryan Seacrest, whose production company is responsible for Keeping Up With the Kardashians, its spinoffs and the new series Shahs of Sunset, is still getting a fat paycheck from his American Idol family. As the second highest paid female on the small screen, behind Sofia Vergara, Kim Kardashian is one of the most powerful celebrities at $18 million in earnings, with a only a fraction coming in from her reality shows. (Kourtney & Kim Take Miami premiered in January). The 32-year-old is also a hard working businesswoman, with Kardashian Kollection and DASH, the clothing line and store, respectively, she manages with her sisters Kourtney and Khloe. Check out the gallery, above, for more on the hottest reality stars and the dough they’re rolling in. Are you surprised by how much some of these celebrities earn? Who do you think should make more? Less? Weigh in below. ||||| Who's No. 1? American Idol is in the business of making music stars, and in turn, has made lots of money for some of their contestants. Forbesreleased their list of the top-earning Idol alums of 2012 a few names on this list are sure to surprise you. |
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for
bulk liquid helium the bottom of the conduction band ( v0 ) is above the vacuum level . in this case
the
surface of the liquid represents an electronic surface barrier for
an electron to be injected into the liquid .
here we study the electronic
conduction band for doped helium droplets of different sizes . utilizing
an electron monochromator , the onset of the ( h2o)2 ion yield corresponding to v0 is determined for helium droplets doped with the water
dimer .
while for larger droplets the onset approaches the well - known
bulk value of about 1 ev , the barrier does not continuously decrease
with smaller droplet size .
a minimum value of v0 = 0.76 0.10 ev is observed , which corresponds to a
droplet size of nmin = 1600 900 .
for droplet sizes below nmin ,
a peak at
0 ev appears , which is well - known from neat h2o
clusters .
hence , we interpret nmin as
the smallest droplet size in which the electronic band structure is
formed in liquid helium droplets . | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | the present experiments are performed with a he droplet source combined with a pick - up cell containing h2o vapor , an ion source , and a mass spectrometer system to analyze the resulting anions as previously described in detail . the helium droplet beam is formed by expansion of he through a nozzle of 5 m diameter into vacuum at a temperature between 9 and 11 k and at a constant pressure of 20 bar . at a distance of 1 cm downstream , the he droplets pass a skimmer before they enter a differentially pumped chamber containing a pick - up cell , an ion source , and a mass analyzer . after passing the pick - up cell , the h2o - doped helium droplets enter the collision region of the ion source , where free electron attachment to the doped droplets takes place . the electron beam is generated by a home - built hemispherical electron monochromator , which provides an electron beam with a full width at half - maximum of about 100 mev . the electron energy scale is calibrated by measuring the well - known resonance in sf6 yielding sf6 close to threshold ( 0 ev ) . ion yields at negative electron energies are caused by the finite resolution of the electron beam . anions formed are mass selected by a quadrupole mass filter and detected by a channel electron multiplier . in general , the number of pick - up events can be changed by adjusting the water pressure in the pick - up cell . all h2o partial pressures mentioned were determined by an ion gauge mounted at the ion source chamber . hence , the exact pressure in the pick - up cell is unknown ; however , the chamber pressure can be considered a qualitative measure of the pressure in the pick - up cell . |
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– A French tourist is being praised for saving a busload of fellow passengers from "catastrophe" after the driver passed out. The bus was on a winding road in the Austrian Alps near Schwaz when the 76-year-old driver collapsed, the BBC reports. As the bus was careening toward a precipice, a 65-year-old man sitting near the front jumped from his seat and managed to hit the brakes at the last second, per Le Quotidien. The bus slammed into a wooden barrier, preventing it from hurtling down a slope and over a 328-foot cliff. LQ published a photo of the bus, its front end punctured by the barrier, tilting down a grassy hill. A local police rep praised the hero passenger's quick reflexes. "We were a hair's breadth from catastrophe," he tells AFP. He calls it "incredible luck" the man managed to stop the bus. In 2004, five tourists were killed when their bus plunged down a 98-foot embankment south of Salzburg, Austria, the BBC notes. (Two dozen seniors in Germany escaped a bus crash in July, but 18 were killed.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Image copyright EPA Image caption "A hair's breadth from catastrophe", local police say A quick-thinking French tourist has been praised for preventing a bus from plunging over a cliff in the Austrian Alps after the driver passed out. The vehicle was travelling through the mountains in the Tyrolean Alps with 21 passengers on board when the driver, 76, collapsed, police say. As the bus continued towards a steep cliff, the Frenchman was able to brake. The bus crashed into a barrier at the side of the road and came to a stop. Four people were taken to hospital. The passenger, a 65-year-old Frenchman, was sitting close to the driver when he became ill near the city of Schwaz in western Austria on Saturday, local media report. He then leapt from his seat as the vehicle crashed through the wooden roadside guardrail and applied the brake, leaving the bus full of passengers hanging over the cliff edge a short distance from a 100m (328ft) drop. "We were a hair's breadth from catastrophe," a local police spokesman said, adding it was "incredible luck" that the passenger's reflexes had managed to stop the bus, AFP news agency reports. In 2004, five tourists were killed when a coach left the road and tumbled down a 30m embankment near the village of Bad Dürrnberg, south of Salzburg, in Austria. ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. |
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– House Republicans won't take up immigration reform after all, because there's "widespread doubt" about whether President Obama can be trusted to enforce anything they pass, John Boehner said today. "The president seems to change the health-care law on a whim," Boehner said, according to the Wall Street Journal. "Now he's running around the country telling everyone he'll keep acting on his own." Boehner suggested that Obama push Senate Democrats to take up House-passed job legislation as a trust-building measure, Politico reports. The comments are widely being viewed as a stake through the heart of immigration reform hopes, because Boehner is seen as immigration's biggest fan amongst the GOP leadership. Yesterday Mitch McConnell said reform was likely impossible, because the Senate insists on a comprehensive bill, and the House insists on piece-meal efforts, CNN reports. "I think we have an irresolvable conflict here," the Senate minority leader said. Many Republicans also worry that passing anything would be seen as a Democratic victory going into the midterms. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | House Speaker John Boehner squashed growing expectations that Congress would rewrite immigration laws this year—dealing a setback to the White House, a swath of U.S. businesses and a bloc of fellow Republicans seeking to improve their party's chances with Hispanic voters. Rank-and-file Republicans have voiced few complaints about the GOP's latest ideas for an immigration overhaul, which include some legal status for most of the 11.5 million people in the U.S. illegally. But many balked at debating an issue that divides... ||||| 4 years ago (CNN) - Senate Minority Leader Mitch McConnell said Tuesday he can't see an agreement on immigration reform happening this year, citing an "irresolvable conflict" between the U.S. Senate and House. McConnell indicated the Democratic-controlled Senate's insistence on comprehensive legislation is at impossible odds with the House Republican majority's preferred piecemeal approach to immigration reform. Follow @politicalticker "I think we have an irresolvable conflict here. The Senate insists on comprehensive. The House says it won't go to conference with the Senate on comprehensive and wants to look at step-by-step," he told reporters after a meeting with the Senate Republican conference. "I don't see how you get to an outcome this year with the two bodies in such a place." House Republicans laid out last week a blueprint of immigration "standards," saying there "will be no special path to citizenship" for the country's estimated 11 million undocumented immigrants. The GOP principles call instead for a path to legalization, and only after those already in the country illegally get in the back of the line and the federal government continues to bolster border security. The Kentucky Republican did not take a position on the GOP outline. The Senate passed a comprehensive bill that included a path to citizenship last year, but the House has not taken up the measure. The White House has said it's open to the House approach but the President warned in an interview with CNN's Jake Tapper against reform that creates "two classes of people" in the country. |
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– A North Carolina woman who seemingly vanished in 2011 has been found safe and living under a false name in Columbus, Ohio, police say. Rachel Natacha Owens was just 15 when she was last spotted getting off a school bus and into a vehicle in the parking lot of South Brunswick High School in Boiling Spring Lakes, reports the Wilmington Star News. The teen had previously run away for brief periods, per the New York Daily News, and for five years, Owens' parents and five siblings didn't hear a word from her. In 2014, however, FBI agents say they received a tip that Owens might be in Columbus—which is exactly where she was found around noon Friday, according to the Brunswick County Sheriff's Office. The 21-year-old—previously believed to be with a much older man, per the Star News—had left North Carolina of her own accord and "went to great lengths to intentionally conceal her whereabouts, even assuming a false identity and date of birth," police say in a release. "There is no foul play in Rachel’s disappearance and no charges will be pursued at this time." In that respect, it's a happy ending because "some people assumed you are never going to find her because ... you're chasing a ghost," FBI Special Agent Rich Novelli says. "Thankfully none of us gave up." It isn't clear if a reunion is expected. (Police have a new lead in a 47-year-old disappearance.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | A North Carolina woman who went missing as a teenager five years ago is reportedly alive and well and living in Columbus, Ohio. Rachel Natacha Owens had not reached out to her parents or her five siblings since her May 5, 2011 disappearance. Reports say it was her intention to remain undetected. Owens was 15 years old the last time residents of Boiling Spring Lakes saw her. The small town girl was recognized getting off a South Brunswick High School bus and getting into an unidentified vehicle, according to footage recovered by police. The FBI released a missing persons report on the teen, offering a $5,000 reward for information leading to her return. The report admitted it wasn’t the first time the teenager had run away. Two Texas teens found a day after they went missing Rachel Natacha Owens disappeared when she was 15 years old. (FBI) Owens, now 21, is said to have gone to “great lengths” to hide her whereabouts. She had even assumed a false identity and date of birth when found by police. The Sheriff’s Office released a press statement on Friday announcing, “There is no foul play in Rachel’s disappearance.” “No charges will be pursued, at this time,” a spokeswoman from the department wrote. In a press conference the day before Father’s Day in 2014, Brunswick County Sheriff's Office Sgt. Candi West spoke on behalf of Rachel’s parents, Kenneth and Kathy Owens. “If Rachel sees this or someone that is associated with Rachel sees this — her family just wants to know that she’s okay, her family just wants her to know that they miss her and they love her,” West said. Owens’ parents did not respond Monday to repeated attempts for comment. Sign up for BREAKING NEWS Emails privacy policy Thanks for subscribing! ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. |
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– Note to police: Buses make bad holding cells. The San Diego County Sheriff’s Department has ordered an internal review, City Beat reports, after the paper revealed that police detained 51 Occupy San Diego protesters inside a bus and a van for four to eight hours—and that neither vehicle had a bathroom. Detainees say deputies told them to just relieve themselves in the bus, which they did, with one woman defecating. The Sheriff's Department confirmed the incident in its statement, calling “this unfortunate result ... very unusual." | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Search in Movies Theater Any AMC Fashion Valley 18 AMC La Jolla Village 12 AMC Mission Valley 20 Carmel Mountain Edwards Mira Mesa Stadium 18 & IMAX Edwards Rancho San Diego Stadium 15 Gaslamp Stadium Grossmont Center 10 Hillcrest Cinema Ken Cinema La Jolla Village Cinema La Paloma Regal Cinemas Oceanside Stadium 16 Regal Parkway Plaza Stadium 18 & IMAX Reuben H. Fleet Science Center Town Square Stadium UltraStar Mission Valley Cinemas United Artists Horton Plaza 14 Features Any Cafe on Premises Digital Light Processing Digital Theater Systems Discounted / Bargain shows Game Room on Premises Listening Devices Available Print At Home Ticketing Sony Digital Dynamic Sound Stadium Seating Wheelchair Accessible City, State or Zip ||||| Search in Movies Theater Any 99 West Drive-In Academy Theater Avalon Theatre & Wunderland Bagdad Theater Century 16 Cedar Hills Century 16 Eastport Plaza Century Clackamas Town Center and XD Cinema 21 CineMagic Theatre Cinetopia Mill Plain 8 Clinton Street Theater Cornelius 9 Cinemas Edgefield Powerstation Theater Empirical Theatre at OMSI Fifth Avenue Cinema Forest Theatre Hollywood Theatre Indoor Twin Cinemas Kennedy School Theater Kiggins Theatre Lake Theater & Cafe Laurelhurst Theatre & Pub Living Room Theaters Milwaukie Cinema & Wunderland Mission Theater and Pub Moreland Theatre Mt. Hood Theatre NW Film Center's Whitsell Auditorium Oak Grove 8 Cinemas Regal Cinema 99 Stadium 11 Regal Cinemas Bridgeport Village Stadium 18 & IMAX Regal City Center Stadium 12 Regal Division Street Stadium 13 Regal Evergreen Parkway Stadium 13 Regal Fox Tower Stadium 10 Regal Hilltop 9 Cinema Regal Lloyd Center 10 & IMAX Regal Lloyd Mall 8 Regal Movies On TV Stadium 16 Regal Pioneer Place Stadium 6 Regal Sherwood Stadium 10 Regal Tigard 11 Regal Vancouver Plaza 10 Regal Wilsonville Stadium 9 Roseway Theatre Sandy Cinemas St. Johns Cinemas St. Johns Theater The Joy Cinema and Pub Valley Theater Features Any Cafe on Premises Digital Light Processing Digital Theater Systems Discounted / Bargain shows Game Room on Premises Listening Devices Available Print At Home Ticketing Sony Digital Dynamic Sound Stadium Seating Wheelchair Accessible City, State or Zip |
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– A Vermont librarian who sued consumer credit bureau giant Equifax following a massive 2017 breach of private data has been awarded $600. The largely symbolic suit by Jessamyn West was her way of showing people they have the power to arm themselves in the fight for data security, even when companies like Equifax and others go largely unpunished. In an interview with KrebsOnSecurity, West said she hoped her decision to take direct action against the company as an individual would inspire others to do the same. "A lot of people don’t feel they have agency around privacy and technology in general," West told the site. "This case was about having your own agency when companies don’t behave how they’re supposed to." West originally filed the suit in small claims court for $5,000, where she argued that the widely publicized September breach was an undue burden on her as she struggled to deal with her personal data security and that of her recently deceased mother. A judge instead awarded her $690, with the $90 going to court costs and the rest recognizing the cost of two years of identity theft protection. As the Daily Dot notes, the judgment isn't much for a giant corporation like Equifax, but lots of little suits could add up. In fact, one claimant wrote back in January about receiving $8,000 in a similar suit against Equifax. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | BTW Equifax seems to have suffered very little in the wake of its massive 2017 data breach, which compromised the personal data of 143 million people. While many simply checked if there data was included in the breach and angrily went on there way, one Vermont librarian decided to take action—she sued Equifax, and won. Unfortunately, the victory was more symbolic than a deep-pocketed punishment that Equifax would feel to the core, but a victory is a victory nonetheless, and it could inspire others to follow suit. Jessamyn West, a 49-year-old librarian, sued Equifax in small claims court for the undue burden it put on herself and her family. West’s mother died in July, and she was in the process of settling her finances. The breach “added to the work of sorting out her mom’s finances while trying to respond to having the entire family’s credit files potentially exposed to hackers and identity thieves,” according to Krebs on Security. West sued for $5,000 in damages, but the judge ruled to only award her $690—$600, plus $90 to cover court fees. The $600 sum was awarded in order to cover the cost of identity theft protection services for two years. West’s goal wasn’t to make a large sum off of Equifax, which still reported $3.4 billion in revenue last year despite its enormous data breach, but rather to draw continued awareness about privacy and technology. “This case was about having your own agency when companies don’t behave how they’re supposed to with our private information,” West said. Following news of the data breach, one Stanford student developed a bot to help victims file suits in small claims court. Others who’ve filed suits have been awarded up to $8,000. While West—and others’—sum from her case is small, if millions of others who suffered in the aftermath of the data breach decided to file claims, Equifax could finally feel the impact of its negligence. H/T Krebs on Security ||||| Your email account may be worth far more than you imagine. |
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– Ever wonder why it doesn't take elephants an hour to pee? Well someone did. After studying mammals of all walks of life at Zoo Atlanta, scientists discovered that, aside from those that weigh 6.5 pounds or less, it takes the rest of us mammals on average 21 seconds to pee, give or take 13 seconds, reports Scientific American. Doesn't matter if it's a newborn human, a gorilla, or a giraffe; urination time is extremely consistent, something fairly remarkable when you consider an elephant's bladder is almost 3,600 times bigger than that of a cat. The reason, they surmise, is that even though bigger mammals tend to have bigger bladders, their urethra is wider and also longer, and thus—thanks to gravity—the flow is faster. David Hu, the mechanical engineer who filmed the mammals at the zoo, tells the LA Times he got the idea a few years ago when he was changing his young kids' diapers and thought, "How could anything be worse right now?" Which was immediately followed by: "Well, maybe if I was changing an elephant’s diaper." After hours spent at the zoo (during which they collected urine in cut-up soda bottles during the act in order to measure flow rate), the researchers also learned that smaller animals, like rats, don't pee in a jet stream but rather in little "gumballs" of water dispensed one at a time; they lack the amount of liquid needed to create a real flow. It seems that 6.5 pounds is the tipping point, which is why a grown bear takes as long to pee as sweet little Toto. Hu notes that the study could have health implications for humans: If one's urination duration falls outside the norm, it could signal a medical problem. (Speaking of Toto, dogs appear to use Earth's magnetic field to poop.) | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | In the time it takes you to listen to this story, an elephant could empty its bladder about three times. And, despite being much smaller, so could an adult cat. And a goat. Also a cow. Because researchers find that all mammals that weigh more than six-and-a-half pounds or so take about the same time to pee: 21 seconds, plus or minus 13 seconds. The researchers videoed various mammals urinating at Zoo Atlanta. And they found that, once you get above the squirrel-mouse-shrew level, tinkle-time does not scale with body size. Good news for elephants, who could otherwise spend all day going number one. Seems that larger animals have a longer urethra, the conduit that whisks the wee-wee away. That difference in size is big enough that gravity starts to really weigh in. As a result, when Jumbo answers nature’s call he has a much faster flow than does Mittens. Given the urethra’s structure, the researchers say that the mammalian urinary system can be “scaled up by a factor of 3,600 in volume without compromising its function.” The study is in the Proceedings of the National Academy of Sciences. [Patricia J. Yang et al, Duration of urination does not change with body size, preprint] This hydrodynamic finding could help engineers design systems that rapidly drain reservoirs, regardless of size. It also means if Mittens and Jumbo hit the head together, they can come out at the same time. —Karen Hopkin [The above text is a transcript of this podcast.] ||||| While timing each pee session was easy, measuring the flow rate was hard, because they had to collect the urine. That's no easy task. First off, it's hard to catch an animal in the act. Second, you have to catch all the urine in order to get an accurate measurement of how much liquid is coming out per second. And you have to do it by hand. It was unavoidable: The high-speed camera was occasionally splattered by urine, Hu said. |
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– When a 2-year-old wants to find her mom and dad, a little wet concrete isn't going to stand in her way. And that's why little Izzadora Millaway of Cleveland, Tenn., is enjoying some viral fame, reports UPI. It seems that workers had just poured concrete in the basement when Izzadora, thinking her parents were down there, headed down to find them. As it turns out, her parents were with workers from Porter Concrete Construction, looking at the finished work from the outside of the house. And that's where they were when Izzadora trudged through the basement, leading to a few memorable photos posted by the company under the caption, "Best concrete comedy!!!" Mom Sara Millaway tells WTVC that they considered leaving the footprints in place but will instead settle for saving just a pair of them. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | July 30 (UPI) -- A Tennessee 2-year-old who went searching for her parents walked through wet concrete in her home's basement and into the hearts of the Internet. Porter Concrete Construction shared photos on Facebook showing little Izzadora Millaway and the trail of footprints she left through the basement of her family's Cleveland home when she went searching for her parents. "Best concrete comedy!!!" the viral post said. "Normally we see cats and dogs run or walk in concrete, but not this time. This little girl was trying to go see her mom and dad, so she came from upstairs to the basement to find them." Sara Millaway, the girl's mother, said she and her husband were with Porter workers looking at their work from outside when the toddler walked down the steps into the basement and trudged across the wet concrete. Millaway said she briefly considered leaving the footprints as a memento of Izzadora's amusing misadventure, but she decided instead to do a pair of "official keepsake" footprints on the still-wet floor. ||||| See more of Porter Concrete Construction Co. on Facebook ||||| A 2-year-old girl in Cleveland looking for her parents wound up leaving her mark - in a lot of places - in a basement that was being resurfaced on Friday. Workers for Porter Concrete Construction were on the job, and were outside with Izzadora Millaway's folks, taking a look from that perspective. But Izzadora didn't realize that. Her mom, Sara Millaway, says she went downstairs and walked through the wet cement to find mom and dad. Millaway says everyone thought it was hilarious. She says Izzadora is not in trouble, considering she just made a memory they'll all laugh about for years. Asked if she considered preserving the unintended footprints for all time on the basement floor, Millaway says they considered doing that, but decided instead to do a pair of "official keepsake" footprints from Izzadora before the cement dries. |
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– Hulk Hogan, with funding from frequent Gawker target Peter Thiel, helped bring the media group to bankruptcy via his sex-tape lawsuit, so Thiel's choice of costume at a posh Long Island party might not be terribly surprising: He reportedly dressed as the Hulkster on Saturday night, when the PayPal founder attended a costume party thrown by Donald Trump donor Robert Mercer. The event was also attended by Trump himself and campaign manager Kellyanne Conway, who was "decked out as Dolly Parton meets Superwoman," per Vanity Fair. "Honoring the ultimate hero at the Mercer 'Heroes and Villians' party on Long Island. Crowd thrilled w/ surprise!" Conway tweeted, showing a photo of her and her boss, disguised as … himself, apparently, in a suit and tie. No pictures of Thiel's costume have popped up yet; the intel comes via two party guests who tell Bloomberg they saw him in his Hogan getup. A Thiel spokesman wouldn't comment. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Tweet with a location You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more ||||| This weekend, Donald Trump took a break from using his Twitter account to raise the specter of a trade war (or maybe a real war) with China to abscond to the North Shore of Long Island, where the president-elect and several dozen other members of the new conservative elite attended billionaire hedge-fund tycoon and Trump donor Robert Mercer’s annual costume party, the latest stop on Trump’s own self-congratulatory, post-election “Thank You Tour.” The theme of this year’s event: heroes and villains. Naturally, Trump came dressed as himself. Former Trump campaign manager Kellyanne Conway showed up, too, decked out as Dolly Parton meets Superwoman. Onetime leader of the U.K.’s pro-Brexit Independence Party Nigel Farage—who has gotten closer to Trump since the election—was nattily attired as the naval hero Admiral Lord Nelson. Some costumes were more on the nose than others. Not one to be outdone, libertarian tech billionaire and Trump surrogate Peter Thiel reportedly arrived dressed as Hulk Hogan, the former wrestler whose invasion-of-privacy lawsuit against Gawker Media, which Thiel clandestinely funded, ultimately bankrupted the company earlier this year, fulfilling Thiel’s nearly decade-long personal vendetta against Gawker. (Unfortunately, no pictures of Thiel in costume have yet publicly surfaced.) Ever a contrarian, Thiel raised eyebrows in Silicon Valley earlier this year when he became a California delegate for Trump, delivering a prime-time speech on the Republican nominee’s behalf at the G.O.P. convention. Thiel also donated $1.25 million to Trump’s presidential campaign, forcing both start-up accelerator Y Combinator and Facebook to defend their corporate relationships with him, and turning Thiel into something of a pariah in the otherwise-liberal Bay Area. In October, Thiel defended both his financial contribution to the Trump campaign and his decision to bankroll Hogan’s lawsuit. “If you’re a single-digit millionaire like Hulk Hogan you have no effective access to our legal system,” he said, without a hint of irony. |
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– At 6:28pm Eastern time tonight, an aircraft carrier-sized asteroid will swing by Earth at a distance of 201,000 miles, which is within the moon’s orbit. That’s the closest an asteroid has come to the planet since 1976, but don’t worry: NASA has determined the space rock poses no threat, the Wall Street Journal reports. You won’t be able to view it with the naked eye, but if you have a good sky chart and a 6-inch or larger telescope, you may have a shot, the Telegraph adds. The 1,300-foot-wide 2005 YU55 is traveling at 29,000 miles per hour. Researchers have been monitoring it, and will learn more about it through radar images. Asteroids are among the solar system’s oldest objects, and astronomers hope to glean clues about the origins of life on our planet. “This is an extraordinary opportunity to look at an extremely important type of asteroid,” says one NASA scientist. “A small army of astronomers are pretty excited about it.” Click for more on the asteroid. | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | Dow Jones Reprints: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues, clients or customers, use the Order Reprints tool at the bottom of any article or visit www.djreprints.com Astronomers are tracking an asteroid about the size of an aircraft carrier that on Tuesday will pass by Earth, within the moon's orbit, in the closest approach of such an object in a generation. The 1,300-foot-wide asteroid, known as 2005 YU55, poses no hazard, experts at NASA's Jet Propulsion Laboratory said. They are monitoring the spinning space rock by radar as it nears and eventually speeds past Earth at a distance of 201,000 miles. The asteroid is going 29,000 miles per hour, according to astronomers at the University of Arizona. It is the first time since 1976 that an asteroid ... ||||| Scientists at NASA's Near-Earth Object Programme, which tracks asteroids and comets, ruled out any chance of impact. They are using the close encounter to learn more about the space rock known as 2005 YU55. The last time a cosmic interloper this size came this close to Earth was in 1976 and it will not happen again until 2028. Since late last week, antennas at the space agency's Deep Space Network in California have been monitoring the quarter-mile-wide asteroid as it approaches from the direction of the sun. The Arecibo Observatory in Puerto Rico planned a viewing Tuesday when the asteroid is set to make its closest pass at a distance of 202,000 miles at 11.28pm GMT. Since its discovery six years ago by a University of Arizona astronomer, scientists have learned a great deal about 2005 YU55. Its surface is coal black, and it spins slowly through space. Amateur skygazers who want a glimpse need two things: a good sky chart and a 6-inch telescope or larger since the asteroid is too faint to detect with the naked eye. Even with a telescope, sighting is not guaranteed. The glare from the moon may make the asteroid difficult to spot. |
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* the ability to manipulate phonon waveforms in continuous media has attracted significant research interest and is crucial for practical applications ranging from biological imaging to material characterization . although several spatial focusing techniques have been developed , these systems require sophisticated artificial structures , which limit their practical applications . this is because the spatial control of acoustic phonon waves is not as straightforward as photonics so there is a strong demand for an alternative approach .
here we demonstrate a phononic time lens in a dispersive one - dimensional phononic crystal waveguide , which enables the temporal control of phonon wave propagation .
pulse focusing is realized at a desired time and position with chirped input pulses that agree perfectly with the theoretical prediction .
this technique can be applied to arbitrary systems and will offer both an improvement in time and spatial sensing resolution and allow the creation of a highly intense strain field , enabling the investigation of novel nonlinear phononic phenomena such as phononic solitons and rogue waves .
* acoustic phonons have been widely utilized in various applications and are especially important as a tool for nonintrusive sensing in such areas as biological imaging and defence systems@xcite .
the capabilities of these phonon systems , for example imaging resolution and accuracy , are determined by the spatial size and energy density of generated waves . to improve these capabilities ,
several spatial phonon focusing techniques have been proposed where engineered structures such as the phased arrays , negative - index materials and acoustic metamaterials enable acoustic phonons to be focused in tiny spatial regions@xcite .
however , these conventional focusing techniques , which use a spatial lens , rely on sophisticated spatially designed structures , and this limits their practical use .
a time lens , which is a temporal analogue to a spatial lens , has been introduced in the field of optics @xcite . according to space - time duality , which describes the mathematical equivalence between paraxial - beam diffraction and dispersive pulse broadening ,
the effect of dispersion in a medium is the key to realizing a time lens .
importantly , this temporal focusing method can be applied in an arbitrary dispersive material in which it imparts quadratic time - varying phase shift . on the basis of this concept ,
various useful ideas have been developed including temporal imaging , temporal magnification and real - time spectroscopy in optics @xcite . by introducing the approach in the field of phononics ,
we have realized a phononic time lens in a one - dimensional ( 1d ) phononic crystal waveguide ( pnc wg)@xcite which is constructed by nanoelectromechanical systems ( nems ) technology .
ultrasound phonon waves travelling through the wg experience pulse broadening due to the group velocity dispersion ( gvd ) effect .
this gvd effect can be used to compensate for the frequency modulation of the initial pulse that leads to temporal focusing . by further incorporating excellent mechanical properties of nems such as high - quality factors , integrability and nonlinearity into this device@xcite ,
the ability to temporally focus the travelling phonons will open up the possibility of developing an ultrashort and highly intense phonon pulse generator , which will be useful for practical applications as in the case of optical laser systems@xcite , and investigaing nonlinear phononic phenomena .
the pnc wg consists of a 1 mm long membrane made from a gaas / algaas heterostructure as shown in fig .
1(a ) , where periodically - arrayed air holes with a pitch of 8 @xmath0 m are formed along the wg that can be used to suspend the membrane with a width of 22 @xmath0 m by selectively etching the al@xmath1ga@xmath2as layer .
the application of an alternating voltage to an electrode located at both edges of the wg induces phonon vibrations due to the piezoelectric effect .
the resultant vibrations travel down the wg and are detected in an optical interferometer .
figure 1(b ) shows the experimental transmission spectrum of the device and the corresponding band structure calculated by using a finite element method ( fem ) simulation ( comsol multiphysics ) .
the phonon vibrations are observed in 3.5 - 7.5 mhz owing to the presence of 1st phonon band , where the phonon vibrations propagate in the wg and are reflected at both clamping edges thus resulting in the generation of equidistant fabry - perot peaks in the spectral response . on the other hand , phonon waves around 8 mhz experience bragg reflection from the periodic air holes , giving rise to a phonon bandgap , and
this prevents them from propagating in the wg@xcite . above the bandgap
, there is a new phonon branch that again allows the phonon vibrations to be guided . in the experiments described below , we focus on the 1st phonon branch to investigate the temporal dynamics of the phonon vibrations in the device .
a transverse deflection @xmath3 travelling in a 1d pnc wg can be described by euler - bernoulli equations as@xcite , @xmath4 where @xmath5 is the young s modulus , @xmath6 and @xmath7 are the area and moment of inertia of the cross section , @xmath8 is the density of the wg per unit length and @xmath9 and @xmath10 are the elastic coefficients of the wg . to solve equation ( [ eq : w ] )
, the slowly varying amplitude of travelling wave is assumed that the envelope of a travelling vibration pulse centred around wavenumber @xmath11 and angular frequency @xmath12 varies slowly in temporal and spatial domain on the moving - frame with group velocity , @xmath13 .
\label{eq : za}\ ] ] we introduce the linear loss term @xmath14 , then @xmath15 satisfies the following equation@xcite , @xmath16 where @xmath17 is the inverse of the group velocity , @xmath18 is the gvd coefficient and @xmath19 is a nonlinear parameter .
these terms are determined by the material and geometric parameters of the wg in equation ( [ eq : w ] ) .
thus , the dynamics of phonon propagation based on the euler - bernoulli equation corresponds to a nonlinear schr@xmath20dinger equation ( nlse ) , which is used to describe the dynamics of an optical wave propagating in a dispersive medium@xcite . by neglecting the nonlinear term in equation ( [ eq : aa ] ) and using the new time coordinate @xmath21 moving with the group velocity @xmath22 , @xmath23
at the same time we introduce a normalized amplitude @xmath24 , @xmath25 where @xmath26 is the peak amplitude of the input pulse , and the equation can be simplified as @xmath27 interestingly , equation ( [ eq : u ] ) is mathematically equal to the paraxial wave equation that governs the diffraction of cw light .
if we assume a gaussian pulse as an input , the normalized amplitude at distance @xmath28 is given by@xcite , @xmath29 where @xmath30 is the half - width at the 1/@xmath31-intensity point , and its output width @xmath32 is written as @xmath33 thus a phonon temporal waveform travelling down a dispersive medium depends on the absolute value of the gvd coefficient that enables the temporal pulse width to be broadened further due to the larger dispersion . to elucidate the temporal characteristics of this device experimentally ,
phonon vibrations are measured at the left edge by exciting them with a gaussian pulse with @xmath34s from the right edge as shown in fig .
2(a ) .
this time - of - flight measurement also enables the group velocity @xmath35 and the gvd coefficient @xmath36 to be estimated as function of excitation frequency as shown in figs .
2(b ) and 2(c ) respectively .
the experimental @xmath35 value increases with increasing frequency i.e. anomalous dispersion ( @xmath37 ) in the band except near the bandgap where there is a large reduction in @xmath35 , i.e. normal dispersion ( @xmath38 ) , because of the decreased slope of the band .
in addition , the temporal waveform of the pulse around the band edges is distorted and becomes asymmetric with an oscillation near the trailing edge caused by a contribution from the 3rd order dispersion effect ( see supplementary information for more detail ) .
these experimental results can be well reproduced by the calculation results obtained with fem - simulated band structures .
the temporal pulse widths can also be estimated from the time - of - flight measurement in fig .
2(a ) by fitting a gaussian envelope to the output waveforms .
figures 3(b ) and 3(c ) reveal the output pulse widths at various excitation frequencies when exciting gaussian pulses with @xmath39 and 0.7 @xmath0s respectively and measuring them at distances @xmath40 1 , 3 and 5 mm ( see fig .
3(a ) ) .
as theoretically predicted , the pulse widths are greatly increased as the frequency approaches the band edges where @xmath41 is large and the gvd - induced pulse broadening becomes distinct with increasing propagation distance as shown in figs .
3(b)and 3(c)@xcite .
in particular , shortening the input pulse from @xmath42 @xmath0s to 0.7 @xmath0s , namely spectrally broadening , leads to the significant influence of the propagation distance on the output width as shown in fig .
3(c ) . in the previous experiment we confirmed that the pulse is broadened during propagation thanks to the gvd effect . in an anomalous ( normal ) dispersion regime ,
the high - frequency components of the pulse travel faster ( slower ) than its low - frequency components , thus allowing the injected un - chirped pulse to be frequency chirped and broadened , where the product of the temporal and spectral widths is not transform limited . in general
, this effect is unfavorable for efficient phonon guiding .
however , we utilize the disadvantage to demonstrate temporal focusing , namely the compression and amplification , of the travelling phonon pulse . here
, a frequency - chirped pulse is excited as the input , and frequency modulation within the pulse is compensated for by the gvd via propagation , thus resulting in the pulse being compressed to the lower limit for the pulse width determined by a given spectrum , namely transform limited , and the peak amplitude being amplified .
thus this temporal analogue of a spatial lens , called a time lens , enables the temporal focusing of a phonon wave@xcite .
the dynamics of the chirped pulse evolution in the wg can also be described by nlse , and the output pulse width @xmath43 is given by @xmath44 @xmath45 is a chirp parameter that is positive ( negative ) when the frequency increases ( decreases ) linearly from the leading to the trailing edge , and is defined by @xmath46 where @xmath47 is the spectral half - width at the 1/@xmath31-intensity point .
equation ( [ eq : t ] ) indicates that pulse focusing occurs only when @xmath48 , where an up - chirped @xmath49 ( down - chirped @xmath50 ) pulse is used as an input in an anomalous ( normal ) dispersion regime @xmath51 ( @xmath52 ) . as an experimental demonstration in this device
, an up - chirped pulse is injected in the anomalous dispersion regime between 3.5 - 7 mhz as shown in fig .
4(a ) .
the output pulse width is measured at various distances by exciting different chirped pulses with a centre frequency of 5.8 mhz as shown in figs .
4(b)-(d ) .
the pulse widths with negative @xmath45 monotonically increase with increasing distance ( see fig .
4(b ) and the upper panel of fig .
4(c ) ) , whereas the widths with a positive @xmath45 first decrease to the transform limited value , and in turn , increase with distance ( see fig .
4(b ) and the lower panel of fig .
4(c ) ) .
it should be also noted that a smaller pulse width is observed when we employ a larger absolute value of positive @xmath45 and indeed , strong focusing is realized when @xmath53 where the pulse width is compressed from 2 @xmath0s to 0.5 @xmath0s and the strain energy is enhanced more than one order of magnitude . making use of the gvd effect enables a travelling pulse waveform to be engineered that leads to the temporal focusing of phonons . in a conventional spatial lens ,
the figures of merit such as the compression and amplification factors , and the ability to spatially adjust the focusing position , are mainly determined by the geometric parameters of the system .
therefore , these techniques require sophisticated artificial structures if they are to control waves .
in contrast this time lens enables them to be dynamically designed by simply changing the excitation frequency , input pulse width and chirp parameters .
although , in this study , these focusing properties are limited by the device structure causing the reflection at both wg edges , and the finite bandwidth of the lock - in amplifier , it is possible to further enhance this focusing effect by modifying the device structure and optimizing the measurement set - up . in conclusion
, we have demonstrated a phononic time lens in a 1d pnc wg .
the dispersion effect determined by the periodic geometry of the device induces frequency chirp in the gaussian input pulse during propagation .
this phenomenon also allows the travelling wave to be temporally focused , and this can be controlled by changing the input chirp parameters .
this novel temporal focusing can enhance the availability of mobile phonons , and this ability will open up potential applications to investigate nonlinear phononic phenomena .
+ + * methods * + nanomechanical vibrations in the pnc wg were excited by applying an amplitude modulated alternating voltage from a signal generator ( nf wavefactory 1974 and 1968 ) , and were measured with a he - ne laser doppler interferometer ( neoark mld-230v-200-nn ) . in the spectral measurements in fig .
1(b ) , the electrical output from the interferometer was measured with a vector signal analyzer ( hp89410a ) . in the temporal measurements in figs .
2(a ) , 3(b)-(c ) and 4(b)-(c ) , the electrical output was first filtered by a lock - in amplifier ( zurich instruments hf2li ) , and then measured with an oscilloscope ( agilent dso6014a ) .
the spectral bandwidth of the low - pass filter in the lock - in amplifier was set at 470 khz , which is equivalent a time constant of 102.6 ns .
+ + * acknowlegements * + we are grateful to y. ishikawa for growing the heterostructure .
this work is partly supported by a mext grant - in - aid for scientific research on innovative areas `` science of hybrid quantum systems '' ( grant no .
jp15h05869 ) .
+ + * author contributions * + m.k . and d.h . performed the measurements and data analysis .
d.h . fabricated the sample and k.o .
co - fabricated the gaas / algaas heterostructure .
m.k . and d.h .
wrote the paper and h.y .
planned the project .
10 buckingham , m. j. , berknout , b. v. , and glegg , s. a. imaging the ocean with ambient noise .
, 327329 ( 1992 ) .
fatemi , m. and greenleaf , j. f. ultrasound - stimulated vibro - acoustic spectrography .
, 8285 ( 1998 ) .
kushibiki , j. and chubachi , n. material characterization by line - focus - beam acoustic microscope .
, 189212 ( 1985 ) .
esenaliev , r. o. , karabutov , a. a. , and oraevsky , a. a. sensitivity of laser opto - acoustic imaging in detection of small deeply embedded tumors . , 981988 ( 1999 ) .
yang , s. , page , j. h. , liu , z. , _
et al .
_ focusing of sound in a 3d phononic crystal .
, 024301 ( 2004 ) .
spadoni , a. and daraio , c. generation and control of sound bullets with a nonlinear acoustic lens .
, 72307234 ( 2010 ) .
chen , y. , liu , h. , reilly , m. , _
et al . _ enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials . , 5247 ( 2014 ) .
hatanaka , d. , dodel , a. , mahboob , i. , _
et al . _ phonon propagation dynamics in band - engineered one - dimensional phononic crystal waveguides . , 113032 ( 2015 ) .
hatanaka , d. , mahboob , i. , onomitsu , k. , _
et al . _
phonon waveguides for electromechanical circuits . , 520524 ( 2014 ) .
akhmanov , s. , chirkin , a. , drabovich , k. , _
et al . _
nonstationary nonlinear optical effects and ultrashort light pulse formation . , 598605 ( 1968 ) .
treacy , e. optical pulse compression with diffraction gratings .
, 454458 ( 1969 ) .
foster , m. a. , salem , r. , geraghty , d. f. , _
et al . _ silicon - chip - based ultrafast optical oscilloscope . , 8184 ( 2008 ) .
salem , r. , foster , m. a. , and gaeta , a. l. application of space - time duality to ultrahigh - speed optical signal processing .
, 274317 ( 2013 ) .
salem , r. , foster , m. , turner , a. , _ et al . _ optical time lens based on four - wave mixing on a silicon chip .
, 1047 ( 2008 ) .
bennett , c. , scott , r. , and kolner , b. temporal magnification and reversal of 100 gb / s optical data with an up - conversion time microscope . , 2513 ( 1994 ) .
kolner , b. h. and nazarathy , m. temporal imaging with a time lens .
, 630632 ( 1989 ) .
solli , d. , chou , j. , and jalali , b. amplified wavelength - time transformation for real - time spectroscopy . , 4851 ( 2007 ) .
singh , v. , bosman , s. j. , schneider , b. h. , _
et al . _ optomechanical coupling between a multilayer graphene mechanical resonator and a superconducting microwave cavity . , 820824 ( 2014 ) .
weber , p. , gttinger , j. , tsioutsios , i. , _
et al .
_ coupling graphene mechanical resonators to superconducting microwave cavities .
, 28542860 ( 2014 ) .
okamoto , h. , gourgout , a. , chang , c. y. , _
et al . _ coherent phonon manipulation in coupled mechanical resonators . , 480484 ( 2013 ) .
faust , t. , rieger , j. , seitner , m. j. , _
et al . _
coherent control of a classical nanomechanical two - level system .
, 485488 ( 2013 ) .
mourou , g. a. , tajima , t. , and bulanov , s. v. optics in the relativistic regime .
, 309371 ( 2006 ) .
perry , m. d. and mourou , g. terawatt to petawatt subpicosecond lasers .
, 917924 ( 1994 ) .
gauthier , d. , allaria , e. , coreno , m. , _
et al . _ chirped pulse amplification in an extreme - ultraviolet free - electron laser .
, 13688 ( 2016 ) .
nayfeh , a. h. and mook , d. t. .
wiley classics library .
wiley , ( 2008 ) .
agrawal , g. .
boston , fifth edition , ( 2013 ) .
mollenauer , l. f. , tomlinson , w. j. , stolen , r. h. , _
et al . _
extreme picosecond pulse narrowing by means of soliton effect in single - mode optical fibers .
, 289291 ( 1983 ) .
blanco - redondo , a. , husko , c. , eades , d. , _ et al .
_ observation of soliton compression in silicon photonic crystals .
, 3160 ( 2014 ) .
marcuse , d. pulse distortion in single - mode fibers . , 1653 ( 1980 ) .
liu , j. , usami , k. , naesby , a. , _ et al .
_ high - q optomechanical gaas nanomembranes . , 243102 ( 2011 ) .
s and an amplitude of 1.0 v@xmath54 from the right edge .
( * b * ) , ( * c * ) the frequency dependence of the group velocity @xmath35 and the gvd coefficient @xmath36 respectively , where the experimental and fem simulated results are denoted as circles and solid lines . ] * supplementary information * + on - chip phononic time lens + + + + | Make an abstract according to the given text content, only output the abstract content and nothing else. | [] | the gvd effect , which is proportional to @xmath36 , determines the phonon pulse waveform .however , we also need to take account of the third - order dispersion ( tod ) effect @xmath55 when the centre frequency of the pulse approaches the band edges ( ref .s1 ) . to evaluate the contribution of these effects ,it is useful to introduce dispersion length scales for gvd and tod ( ref . s2 ) , @xmath56 using equation ( s1 ) , equation ( 6 ) in the main text can be modified to , @xmath57 where @xmath58 depending on the signs of @xmath36 and @xmath59 .equation ( s2 ) indicates that the gvd effect is dominant in pulse evolution when @xmath60 is smaller than @xmath61 , but the tod effect also becomes dominant when @xmath62 approaches @xmath60 .supplementary figure 1(a)-(c ) shows the frequency dependence of @xmath63 and the ratio @xmath64 of 1d pnc wg , respectively , which are calculated from an fem simulation .these results indicate that the pulse evolution is mainly dominated by the gvd effect around the centre of the band , where @xmath64 is sufficiently large , and thus , the temporal focusing of the phonon wave at 5.8 , 5.35 and 4.5 mhz can be described solely by the gvd effect as shown in fig .4(b ) , supplementary fig .2(a ) and 2(b ) , respectively . on the other hand, @xmath64 is small at the band edges , which allows the tod effect to distort the pulse waveform , where it becomes asymmetric and an oscillatory structure appears near the tailing edge as shown in supplementary fig .3(a ) , and thus the dynamics of the temporal focusing deviates from the gvd theory as shown in supplementary fig .+ + @xmath0s when @xmath68 .( * b * ) temporal pulse width as a function of propagation distances when exciting a 2.5 @xmath0s chirped pulse with a centre frequency of 5.8 mhz with chirp parameters of @xmath66 and 0 .solid lines indicate the theoretical results when @xmath69 . ] |
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