2,001 research outputs found
Motivation for everyday social participation in cognitively able individuals with autism spectrum disorder
Objective - The purpose of the present study was to examine motivation for the contextual nature of motivations for social participation in cognitively able adolescents and adults with autism spectrum disorder, using self-determination theory as a theoretical framework. Methods - Fourteen Australians and 16 Taiwanese (aged 16–45 years) with Asperger’s syndrome and high functioning autism were asked to carry a device which prompted them seven times/day for 7 days, to record what they were doing, with whom, perceived difficulty and social reciprocity, and the reasons for engaging in a situation, which were then coded into degree of self-determination. Results - Multilevel analyses showed that participants were more likely to be self-determined while engaging in “solitary/parallel leisure” and “social activities” than in other types of activities. Interactions with “family members” and “casual/intimate friends” were also positively associated with self-determined motivation. Further, participants were more likely to perceive higher levels of being listened to during interaction with casual/intimate friends than in interaction with other people. Global social anxiety served as a moderator for their perceptions of difficulty and social reciprocity during social engagement. Conclusion - The findings highlight the context-dependent motivations for social engagement of cognitively able individuals with autism spectrum disorder
Anisotropic Dirac fermions in a Bi square net of SrMnBi2
We report the highly anisotropic Dirac fermions in a Bi square net of
SrMnBi2, based on a first principle calculation, angle resolved photoemission
spectroscopy, and quantum oscillations for high-quality single crystals. We
found that the Dirac dispersion is generally induced in the (SrBi)+ layer
containing a double-sized Bi square net. In contrast to the commonly observed
isotropic Dirac cone, the Dirac cone in SrMnBi2 is highly anisotropic with a
large momentum-dependent disparity of Fermi velocities of ~ 8. These findings
demonstrate that a Bi square net, a common building block of various layered
pnictides, provide a new platform that hosts highly anisotropic Dirac fermions.Comment: 5 pages, 4 figure
Stars in the age of micro-arc-second astrometry
The understanding and modeling of the structure and evolution of stars is
based on statistical physics as well as on hydrodynamics. Today, a precise
identification and proper description of the physical processes at work in
stellar interiors are still lacking (one key point being that of transport
processes) while the comparison of real stars to model predictions, which
implies conversions from the theoretical space to the observational one,
suffers from uncertainties in model atmospheres. That results in uncertainties
on the prediction of stellar properties needed for galactic studies or
cosmology (as stellar ages and masses). In the next decade, progress is
expected from the theoretical, experimental and observational sides. I
illustrate some of the problems we are faced with when modeling stars and the
possible tracks towards their solutions. I discuss how future observational
ground-based or spatial programs (in particular those dedicated to
micro-arc-second astrometry, asteroseismology and interferometry) will provide
precise determinations of the stellar parameters and contribute to a better
knowledge of stellar interiors and atmospheres in a wide range of stellar
masses, chemical compositions and evolution stages.Comment: 7 pages; to appear in the proceedings of "IAU Symposium 248 - A Giant
Step: from Milli- to Micro-arcsecond Astrometry", held in Shanghai, China,
15-19 Oct. 200
Influence of the Earth on the background and the sensitivity of the GRM and ECLAIRs instruments aboard the Chinese-French mission SVOM
SVOM (Space-based multi-band astronomical Variable Object Monitor) is a
future Chinese-French satellite mission which is dedicated to Gamma-Ray Burst
(GRB) studies. Its anti-solar pointing strategy makes the Earth cross the field
of view of its payload every orbit. In this paper, we present the variations of
the gamma-ray background of the two high energy instruments aboard SVOM, the
Gamma-Ray Monitor (GRM) and ECLAIRs, as a function of the Earth position. We
conclude with an estimate of the Earth influence on their sensitivity and their
GRB detection capability.Comment: 24 pages, 15 figures, accepted for publication in Experimental
Astronom
Voltage controlled terahertz transmission through GaN quantum wells
We report measurements of radiation transmission in the 0.220--0.325 THz
frequency domain through GaN quantum wells grown on sapphire substrates at room
and low temperatures. A significant enhancement of the transmitted beam
intensity with the applied voltage on the devices under test is found. For a
deeper understanding of the physical phenomena involved, these results are
compared with a phenomenological theory of light transmission under electric
bias relating the transmission enhancement to changes in the differential
mobility of the two-dimensional electron gas
AlGaN/GaN High Electron Mobility Transistors with Ultra -Wide Bandgap AlN buffer
International audienc
Further studies of 1E 1740.7-2942 with ASCA
We report the ASCA results of the Great Annihilator 1E 1740.7-2942 obtained
with five pointing observations in a time span of 3.5 years. The X-ray spectrum
for each period is well fitted with a single power-law absorbed by a high
column of gas. The X-ray flux changes by a factor of 2 from period to period,
but the other spectral parameters show no significant change. The photon index
is flat with \Gamma = 0.9--1.3. The column densities of hydrogen N_H is
1.0 x 10^{23} H cm^{-2} and that of iron N_{Fe} is 10^{19} Fe cm^{-2}.
These large column densities indicate that 1E 1740.7-2942 is near at the
Galactic Center. The column density ratio leads the iron abundance to be 2
times larger than the other elements in a unit of the solar ratio. The
equivalent width of the K\alpha-line from a neutral iron is less than 15 eV in
90% confidence. This indicates that the iron column density within several
parsecs from 1E 1740.7-2942 is less than 5 x 10^{17} Fe cm^{-2}. In addition,
the derived hydrogen column density is about 1/6 of that of giant molecular
clouds in the line of sight. All these facts support that 1E 1740.7-2942 is not
in a molecular cloud, but possibly in front of it; the X-rays are not powered
by accretion from a molecular cloud, but from a companion star like ordinary
X-ray binaries.Comment: To appear in ApJ July 20, 1999 issue, Vol. 520 #1, 23 pages LaTeX
files, uses aasms4.sty and psfig.sty, also available at
http://www-cr.scphys.kyoto-u.ac.jp/member/sakano/work/paper/index-e.htm
The Faint Cepheids of the Small Magellanic Cloud: an evolutionary selection effect?
Two problems about the faintest Small Magellanic Cloud (SMC) Cepheids are
addressed. On one hand evolutionary tracks fail to cross the Cepheid
Instability Strip for the highest magnitudes (i.e. I-mag~17) where Cepheids are
observed; Mass-Luminosity relations (ML) obtained from evolutionary tracks
disagree with Mass-Luminosity relations derived from observations. We find that
the above failures concern models built with standard input physics as well as
with non-standard ones. The present work suggests that towards highest
magnitudes, Cepheids stars undergo a selection effect caused by evolution: only
the most metal poor stars cross the Instability Strip during the ``blue loop''
phase and are therefore the only ones which can be observed at low luminosity.
This solution enables us to reproduce the shape of the lower part of the
Instability Strip and improves the agreement between observed and theoretical
ML-relations. Some issues are discussed, among them Beat Cepheids results argue
strongly in favor of our hypothesis.Comment: 13 pages, 8 figure
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