2,668 research outputs found
A theoretical approach to the determination of magnetic torques by near field measurement
Theoretical approach to determination of magnetic torques on orbiting spacecraft by near-field measuremen
Applications of the AVE-Sesame data sets to mesoscale studies
Data collected by the lightning data concentrator are available for research. The Mark 3 McIDAS capability provides greater flexibility for the Marshall user community and serves as a model of future UW McIDAS to remote computer links. Techniques were investigated for the display of dynamic 3-D data sets. To date the most promising display technology is a polarized two CRT perspective display which allows both dynamic 3-D images and graphics presentations with full color capability. Algorithms were for the preparation and display of conventional and satellite based weather data in 3-D. These include gridding, contouring, and streamlining processors which operate on both real time and case study data bases. An upper air trajectory model was implemented which creates a display of air parcel trajectories in perspective 3-D. A subsystem for the generation of 3-D solid surface display with shading and hidden surface display with shading and hidden surface removal was tested and its products are currently being evaluated. Motion parallax introduced by moving the point of observation during display is an important depth cue, which, when added to the perspective parallax creates a very realistic appearing display
Barriers to mental health service use among distressed family caregivers of lung cancer patients
Although family caregivers of patients with lung and other cancers show high rates of psychological distress, they underuse mental health services. This qualitative study aimed to identify barriers to mental health service use among 21 distressed family caregivers of lung cancer patients. Caregivers had not received mental health services during the patient's initial months of care at a comprehensive cancer centre in New York City. Thematic analysis of interview data was framed by Andersen's model of health service use and Corrigan's stigma theory. Results of our analysis expand Andersen's model by providing a description of need variables (e.g. psychiatric symptoms), enabling factors (e.g. finances), and psychosocial factors associated with caregivers' non-use of mental health services. Regarding psychosocial factors, caregivers expressed negative perceptions of mental health professionals and a desire for independent management of emotional concerns. Additionally, caregivers perceived a conflict between mental health service use and the caregiving role (e.g. prioritising the patient's needs). Although caregivers denied stigma associated with service use, their anticipated negative self-perceptions if they were to use services suggest that stigma may have influenced their decision to not seek services. Findings suggest that interventions to improve caregivers' uptake of mental health services should address perceived barriers
The Lockheed OSO-8 program. Analysis of data from the mapping X-ray heliometer experiment
The final report describes the extent of the analysis effort, and other activities associated with the preservation and documentation of the data set are described. The main scientific results, which are related to the behavior of individual solar activity regions in the energy band 1.5 - 15 keV, are summarized, and a complete bibliography of publications and presentations is given. Copies of key articles are also provided
A Combination Theorem for Metric Bundles
We define metric bundles/metric graph bundles which provide a purely
topological/coarse-geometric generalization of the notion of trees of metric
spaces a la Bestvina-Feighn in the special case that the inclusions of the edge
spaces into the vertex spaces are uniform coarsely surjective quasi-isometries.
We prove the existence of quasi-isometric sections in this generality. Then we
prove a combination theorem for metric (graph) bundles (including exact
sequences of groups) that establishes sufficient conditions, particularly
flaring, under which the metric bundles are hyperbolic. We use this to give
examples of surface bundles over hyperbolic disks, whose universal cover is
Gromov-hyperbolic. We also show that in typical situations, flaring is also a
necessary condition.Comment: v3: Major revision: 56 pages 5 figures. Many details added.
Characterization of convex cocompact subgroups of mapping class groups of
surfaces with punctures in terms of relative hyperbolicity given v4: Final
version incorporating referee comments: 63 pages 5 figures. To appear in
Geom. Funct. Ana
PolIVb influences RNA-directed DNA methylation independently of its role in siRNA biogenesis.
Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tThis article contains supporting information online at www.pnas.org/cgi/content/full/0709632105/DC1.
Freely available online through the PNAS open access option. © 2008 by The National Academy of Sciences of the USADNA-dependent RNA polymerase (Pol)IV in Arabidopsis exists in two isoforms (PolIVa and PolIVb), with NRPD1a and NRPD1b as their respective largest subunits. Both isoforms are implicated in production and activity of siRNAs and in RNA-directed DNA methylation (RdDM). Deep sequence analysis of siRNAs in WT Arabidopsis flowers and in nrpd1a and nrpd1b mutants identified >4,200 loci producing siRNAs in a PolIV-dependent manner, with PolIVb reinforcing siRNA production by PolIVa. Transposable element identity and pericentromeric localization are both features that predispose a locus for siRNA production via PolIV proteins and determine the extent to which siRNA production relies on PolIVb. Detailed analysis of DNA methylation at PolIV-dependent loci revealed unexpected deviations from the previously noted association of PolIVb-dependent siRNA production and RdDM. Notably, PolIVb functions independently in DNA methylation and siRNA generation. Additionally, we have uncovered siRNA-directed loss of DNA methylation, a process requiring both PolIV isoforms. From these findings, we infer that the role of PolIVb in siRNA production is secondary to a role in chromatin modification and is influenced by chromatin context
Animal models of tic disorders: A translational perspective
Tics are repetitive, sudden movements and/or vocalizations, typically enacted as maladaptive responses to intrusive premonitory urges. The most severe tic disorder, Tourette syndrome (TS), is a childhood-onset condition featuring multiple motor and at least one phonic tic for a duration longer than 1 year. The pharmacological treatment of TS is mainly based on antipsychotic agents; while these drugs are often effective in reducing tic severity and frequency, their therapeutic compliance is limited by serious motor and cognitive side effects.
The identification of novel therapeutic targets and development of better treatments for tic disorders is conditional on the development of animal models with high translational validity. In addition, these experimental tools can prove extremely useful to test hypotheses on the etiology and neurobiological bases of TS and related conditions. In recent years, the translational value of these animal models has been enhanced, thanks to a significant re-organization of our conceptual framework of neuropsychiatric disorders, with a greater focus on endophenotypes and quantitative indices, rather than qualitative descriptors.
Given the complex and multifactorial nature of TS and other tic disorders, the selection of animal models that can appropriately capture specific symptomatic aspects of these conditions can pose significant theoretical and methodological challenges. In this article, we will review the state of the art on the available animal models of tic disorders, based on genetic mutations, environmental interventions as well as pharmacological manipulations. Furthermore, we will outline emerging lines of translational research showing how some of these experimental preparations have led to significant progress in the identification of novel therapeutic targets for tic disorders
A method for measuring the Neel relaxation time in a frozen ferrofluid
We report a novel method of determining the average Neel relaxation time and
its temperature dependence by calculating derivatives of the measured time
dependence of temperature for a frozen ferrofluid exposed to an alternating
magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles
(diameter 13.7 nm +/- 4.7 nm), was synthesized via wet chemical precipitation
and characterized by x-ray diffraction and transmission electron microscopy. An
alternating magnetic field of constant amplitude (H0 = 20 kA/m) driven at
frequencies of 171 kHz, 232 kHz and 343 kHz was used to determine the
temperature dependent magnetic energy absorption rate in the temperature range
from 160 K to 210 K. We found that the specific absorption rate of the
ferrofluid decreased monotonically with temperature over this range at the
given frequencies. From these measured data, we determined the temperature
dependence of the Neel relaxation time and estimate a room-temperature
magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with
previously published results
Measurement of the ER=338 keV resonance strength for 23Na(p,a)20Ne
The absolute strength of the [Formula Presented] resonance for [Formula Presented] has been determined. The experiment was carried out by measuring the number of resonant [Formula Presented] particles, integrated over the yield curve, simultaneously with the number of Rutherford scattered protons. The method applied in the present work is independent of target stoichiometry, uniformity, stopping power, beam straggling, and current integration. For the resonance strength, we obtained a value of [Formula Presented] Previous results are systematically higher, because the change of target stoichiometry under proton bombardment was not taken into account. With proper consideration, the present method can also be applied to other low-energy [Formula Presented] resonances
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