12,403 research outputs found
Consideration of space applications transfer centers for the NASA office of applications
The concept of Space Applications Transfer Centers is examined to consider the design of the first of these facilities. The questions to be considered are listed
Computerized Response Inhibition Training For Children With Trichotillomania
Evidence suggests that trichotillomania is characterized by impairment in response inhibition, which is the ability to suppress pre-potent/dominant but inappropriate responses. This study sought to test the feasibility of computerized response inhibition training for children with trichotillomania. Twenty-two children were randomized to the 8-session response inhibition training (RIT; n = 12) or a waitlisted control (WLT; n = 10). Primary outcomes were assessed by an independent evaluator, using the Clinical Global Impression-Improvement (CGI-I), and the NIMH Trichotillomania Severity (NIMH-TSS) and Impairment scales (NIMH-TIS) at pre, post-training/waiting, and 1-month follow-up. Relative to the WLT group, the RIT group showed a higher response rate (55% vs. 11%) on the CGI-I and a lower level of impairment on the NIMH-TIS, at post-training. Overall symptom reductions rates on the NIMH-TSS were 34% (RIT) vs. 21% (WLT) at post-training. The RIT\u27s therapeutic gains were maintained at 1-month follow-up, as indicated by the CGI-I responder status (= 66%), and a continuing reduction in symptom on the NIMH-TSS. This pattern of findings was also replicated by the 6 waitlisted children who received the same RIT intervention after post-waiting assessment. Results suggest that computerized RIT may be a potentially useful intervention for trichotillomania
Scaling Analysis and Application: Phase Diagram of Magnetic Nanorings and Elliptical Nanoparticles
The magnetic properties of single-domain nanoparticles with different
geometric shapes, crystalline anisotropies and lattice structures are
investigated. A recently proposed scaling approach is shown to be universal and
in agreement with dimensional analysis coupled with an assumption of {\em
incomplete} self-similarity. It is used to obtain phase diagrams of magnetic
nanoparticles featuring three competing configurations: in-plane and
out-of-plane ferromagnetism and vortex formation. The influence of the vortex
core on the scaling behavior and phase diagram is analyzed. Three-dimensional
phase diagrams are obtained for cylindrical nanorings, depending on their
height, outer and inner radius. The triple points in these phase diagrams are
shown to be in linear relationship with the inner radius of the ring.
Elliptically shaped magnetic nanoparticles are also studied. A new
parametrization for double vortex configurations is proposed, and regions in
the phase diagram are identified where the double vortex is a stable ground
state.Comment: 9 pages, 7 figures; added references, and discussion, as suggested by
referee
Drude weight and total optical weight in a t-t'-J model
We study the Drude weight D and the total optical weight K for a t-t'-J model
on a square lattice that exhibits a metallic phase-modulated antiferromagnetic
ground state close to half-filling. Within a suitable 1/N expansion that
includes leading quantum-fluctuation effects, D and K are found to increase
linearly with small hole doping away from the Mott metal-insulator transition
point at half-filling. The slow zero-sound velocity near the latter transition
identifies with the velocity of the lower-energy branch of the twofold
excitation spectrum. At higher doping values, D and K eventually saturate and
then start to decrease. These features are in qualitative agreement with
optical conductivity measurements in doped antiferromagnets.Comment: 7 pages, REVTEX file (3 Postscript figures). To appear in J. Phys.:
Condens. Mattte
The relevance of ERTS-1 data to the state of Ohio
There are no author-identified significant results in this report
Ascaroside Signaling Is Widely Conserved among Nematodes
Background: Nematodes are among the most successful animals on earth and include important human pathogens, yet little is known about nematode pheromone systems. A group of small molecules called ascarosides has been found to mediate mate finding, aggregation, and developmental diapause in Caenorhabditis elegans, but it is unknown whether ascaroside signaling exists outside of the genus Caenorhabditis.
Results: To determine whether ascarosides are used as signaling molecules by other nematode species, we performed a mass spectrometry-based screen for ascarosides in secretions from a variety of both free-living and parasitic (plant, insect, and animal) nematodes. We found that most of the species analyzed, including nematodes from several different clades, produce species-specific ascaroside mixtures. In some cases, ascaroside biosynthesis patterns appear to correlate with phylogeny, whereas in other cases, biosynthesis seems to correlate with lifestyle and ecological niche. We further show that ascarosides mediate distinct nematode behaviors, such as retention, avoidance, and long-range attraction, and that different nematode species respond to distinct, but overlapping, sets of ascarosides.
Conclusions: Our findings indicate that nematodes utilize a conserved family of signaling molecules despite having evolved to occupy diverse ecologies. Their structural features and level of conservation are evocative of bacterial quorum sensing, where acyl homoserine lactones (AHLs) are both produced and sensed by many species of gram-negative bacteria. The identification of species-specific ascaroside profiles may enable pheromone-based approaches to interfere with reproduction and survival of parasitic nematodes, which are responsible for significant agricultural losses and many human diseases worldwide
Web Service Discovery – Reality Check 2.0
In practice the ability to find the right Web service decides between a functionality being implemented anew and at least the possibility of executing it via a service. This report evaluates existing public portals for Web service discovery with respect to their characteristics and their acceptance by developers. For this, we distinguish different possible settings and use cases and evaluate how these are supported in practice. Only few of the publicly available Web service registries are growing in size and importance, with the use case best supported being the pre-programming phase of evaluation of the service landscape. <br
Using the J1-J2 Quantum Spin Chain as an Adiabatic Quantum Data Bus
This paper investigates numerically a phenomenon which can be used to
transport a single q-bit down a J1-J2 Heisenberg spin chain using a quantum
adiabatic process. The motivation for investigating such processes comes from
the idea that this method of transport could potentially be used as a means of
sending data to various parts of a quantum computer made of artificial spins,
and that this method could take advantage of the easily prepared ground state
at the so called Majumdar-Ghosh point. We examine several annealing protocols
for this process and find similar result for all of them. The annealing process
works well up to a critical frustration threshold.Comment: 14 pages, 13 figures (2 added), revisions made to add citations and
additional discussion at request of referee
Few-Qubit lasing in circuit QED
Motivated by recent experiments, which demonstrated lasing and cooling of the
electromagnetic modes in a resonator coupled to a superconducting qubit, we
describe the specific mechanisms creating the population inversion, and we
study the spectral properties of these systems in the lasing state. Different
levels of the theoretical description, i.e., the semi-classical and the
semi-quantum approximation, as well as an analysis based on the full Liouville
equation are compared. We extend the usual quantum optics description to
account for strong qubit-resonator coupling and include the effects of
low-frequency noise. Beyond the lasing transition we find for a single- or
few-qubit system the phase diffusion strength to grow with the coupling
strength, which in turn deteriorates the lasing state.Comment: Prepared for the proceedings of the Nobel Symposium 2009, Qubits for
future quantum computers, May 2009 in Goeteborg, Sweden. Published versio
Optimized supernova constraints on dark energy evolution
A model-independent method to study the possible evolution of dark energy is
presented. Optimal estimates of the dark energy equation of state w are
obtained from current supernovae data from Riess et al. (2004) following a
principal components approach. We assess the impact of varying the number of
piecewise constant estimates of w using a model selection method, the Bayesian
information criterion, and compare the most favored models with some
parametrizations commonly used in the literature. Although data seem to prefer
a cosmological constant, some models are only moderately disfavored by our
selection criterion: a constant w, w linear in the scale factor, w linear in
redshift and the two-parameter models introduced here. Among these, the models
we find by optimization are slightly preferred. However, current data do not
allow us to draw a conclusion on the possible evolution of dark energy.
Interestingly, the best fits for all varying-w models exhibit a w<-1 at low
redshifts.Comment: 6 pages, 4 figures; typos removed and reference added to match
published versio
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