6,275 research outputs found
Incommensurate phonon anomaly and the nature of charge density waves in cuprates
While charge density wave (CDW) instabilities are ubiquitous to
superconducting cuprates, the different ordering wavevectors in various cuprate
families have hampered a unified description of the CDW formation mechanism.
Here we investigate the temperature dependence of the low energy phonons in the
canonical CDW ordered cuprate LaBaCuO. We discover
that the phonon softening wavevector associated with CDW correlations becomes
temperature dependent in the high-temperature precursor phase and changes from
a wavevector of 0.238 reciprocal space units (r.l.u.) below the ordering
transition temperature up to 0.3~r.l.u. at 300~K. This high-temperature
behavior shows that "214"-type cuprates can host CDW correlations at a similar
wavevector to previously reported CDW correlations in non-"214"-type cuprates
such as YBaCuO. This indicates that cuprate CDWs may
arise from the same underlying instability despite their apparently different
low temperature ordering wavevectors.Comment: Accepted in Phys. Rev. X; 9 pages; 5 figures; 3 pages of
supplementary materia
Creating Open Digital Library Using XML: Implementation of OAi-PMH Protocol at CERN
This article describes the implementation of the OAi-PMH protocol within the CERN Document Server (CDS). In terms of the protocol, CERN acts both as a data provider and service provider and the two core applications are described. The application of XML Schema and XSLT technology is emphasized
Effect of K Doping on Phonons in Ba1-xKxFe2As2
The lattice dynamics of Ba1-xKxFe2As2 (x = 0.00, 0.27) have been studied by
inelastic X-ray scattering measurement at room temperature. K doping induces
the softening and broadening of phonon modes in the energy range E = 10-15 meV.
Analysis with a Born-von Karman force-constant model indicates that the
softening results from reduced interatomic force constants around (Ba,K) sites
following the displacement of divalent Ba by monovalent K. The phonon
broadening may be explained by the local distortions induced by the K
substitution. Extra phonon modes are observed around the wave vector q =
(0.5,0,0) at E = 16.5 meV for the x = 0.27 sample. These modes may arise either
from the local disorder induced by K doping or from electron-phonon coupling.Comment: J. Phys. Soc. Jpn. (in press
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A behavioral comparison of male and female adults with high functioning autism spectrum conditions
Autism spectrum conditions (ASC) affect more males than females in the general population. However, within ASC it is unclear if there are phenotypic sex differences. Testing for similarities and differences between the sexes is important not only for clinical assessment but also has implications for theories of typical sex differences and of autism. Using cognitive and behavioral measures, we investigated similarities and differences between the sexes in age- and IQ-matched adults with ASC (high-functioning autism or Asperger syndrome). Of the 83 (45 males and 38 females) participants, 62 (33 males and 29 females) met Autism Diagnostic Interview-Revised (ADI-R) cut-off criteria for autism in childhood and were included in all subsequent analyses. The severity of childhood core autism symptoms did not differ between the sexes. Males and females also did not differ in self-reported empathy, systemizing, anxiety, depression, and obsessive-compulsive traits/symptoms or mentalizing performance. However, adult females with ASC showed more lifetime sensory symptoms (p = 0.036), fewer current socio-communication difficulties (p = 0.001), and more self-reported autistic traits (p = 0.012) than males. In addition, females with ASC who also had developmental language delay had lower current performance IQ than those without developmental language delay (p<0.001), a pattern not seen in males. The absence of typical sex differences in empathizing-systemizing profiles within the autism spectrum confirms a prediction from the extreme male brain theory. Behavioral sex differences within ASC may also reflect different developmental mechanisms between males and females with ASC. We discuss the importance of the superficially better socio-communication ability in adult females with ASC in terms of why females with ASC may more often go under-recognized, and receive their diagnosis later, than males
AFTER, the front end ASIC of the T2K Time Projection Chambers
The T2K (Tokai-to-Kamioka) experiment is a long baseline neutrino oscillation experiment in Japan. A near detector, located at 280m of the production target, is used to characterize the beam. One of its key elements is a tracker, made of three Time Projection Chambers (TPC) read by Micromegas endplates. A new readout system has been developed to collect, amplify, condition and acquire the data produced by the 124,000 detector channels of these detectors. The front-end element of this system is a a new 72-channel application specific integrated circuit. Each channel includes a low noise charge preamplifier, a pole zero compensation stage, a second order Sallen-Key low pass filter and a 511-cell Switched Capacitor Array. This electronics offers a large flexibility in sampling frequency, shaping time, gain, while taking advantage of the low physics events rate of 0.3 Hz. We detail the design and the performance of this ASIC and report on the deployment of the frond-end electronics on-site
Nuclear structure and reaction studies at SPIRAL
The SPIRAL facility at GANIL, operational since 2001, is described briefly.
The diverse physics program using the re-accelerated (1.2 to 25 MeV/u) beams
ranging from He to Kr and the instrumentation specially developed for their
exploitation are presented. Results of these studies, using both direct and
compound processes, addressing various questions related to the existence of
exotic states of nuclear matter, evolution of new "magic numbers", tunnelling
of exotic nuclei, neutron correlations, exotic pathways in astrophysical sites
and characterization of the continuum are discussed. The future prospects for
the facility and the path towards SPIRAL2, a next generation ISOL facility, are
also briefly presented.Comment: 48 pages, 27 figures. Accepted for publication in Journal of Physics
Family coordination in families who have a child with autism spectrum disorder
Little is known about the interactions of families where there is a child with autism spectrum disorder (ASD). The present study applies the Lausanne Trilogue Play (LTP) to explore both its applicability to this population as well as to assess resources and areas of deficit in these families. The sample consisted of 68 families with a child with ASD, and 43 families with a typically developing (TD) child. With respect to the global score for family coordination there were several negative correlations: the more severe the symptoms (based on the child’s ADOS score), the more family coordination was dysfunctional. This correlation was particularly high when parents had to play together with the child. In the parts in which only one of the parents played actively with the child, while the other was simply present, some families did achieve scores in the functional range, despite the child’s symptom severity. The outcomes are discussed in terms of their clinical implications both for assessment and for interventio
Scaling of the distribution of fluctuations of financial market indices
We study the distribution of fluctuations over a time scale (i.e.,
the returns) of the S&P 500 index by analyzing three distinct databases.
Database (i) contains approximately 1 million records sampled at 1 min
intervals for the 13-year period 1984-1996, database (ii) contains 8686 daily
records for the 35-year period 1962-1996, and database (iii) contains 852
monthly records for the 71-year period 1926-1996. We compute the probability
distributions of returns over a time scale , where varies
approximately over a factor of 10^4 - from 1 min up to more than 1 month. We
find that the distributions for 4 days (1560 mins) are
consistent with a power-law asymptotic behavior, characterized by an exponent
, well outside the stable L\'evy regime . To
test the robustness of the S&P result, we perform a parallel analysis on two
other financial market indices. Database (iv) contains 3560 daily records of
the NIKKEI index for the 14-year period 1984-97, and database (v) contains 4649
daily records of the Hang-Seng index for the 18-year period 1980-97. We find
estimates of consistent with those describing the distribution of S&P
500 daily-returns. One possible reason for the scaling of these distributions
is the long persistence of the autocorrelation function of the volatility. For
time scales longer than days, our results are
consistent with slow convergence to Gaussian behavior.Comment: 12 pages in multicol LaTeX format with 27 postscript figures
(Submitted to PRE May 20, 1999). See
http://polymer.bu.edu/~amaral/Professional.html for more of our work on this
are
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