1,312 research outputs found

    Global evolution in spherical symmetry for self-gravitating massive fields

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    We are interested in the global dynamics of a massive scalar field evolving under its own gravitational field and, in this paper, we study spherically symmetric solutions to Einstein's field equations coupled with a Klein-Gordon equation with quadratic potential. For the initial value problem we establish a global existence theory when initial data are prescribed on a future light cone with vertex at the center of symmetry. A suitably generalized solution in Bondi coordinates is sought which has low regularity and possibly large but finite Bondi mass. A similar result was established first by Christodoulou for massless fields. In order to deal with massive fields, we must overcome several challenges and significantly modify Christodoulou's original method. First of all, we formulate the Einstein-Klein-Gordon system in spherical symmetry as a non-local and nonlinear hyperbolic equation and, by carefully investigating the global dynamical behavior of the massive field, we establish various estimates concerning the Einstein operator, the Hawking mass, and the Bondi mass, including positivity and monotonicity properties. Importantly, in addition to a regularization at the center of symmetry we find it necessary to also introduce a regularization at null infinity. We also establish new energy and decay estimates for, both, regularized and generalized solutions.Comment: 43 page

    Anxious/depressed symptoms are related to microstructural maturation of white matter in typically developing youths

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    AbstractThere are multiple recent reports of an association between anxious/depressed (A/D) symptomatology and the rate of cerebral cortical thickness maturation in typically developing youths. We investigated the degree to which anxious/depressed symptoms are tied to age-related microstructural changes in cerebral fiber pathways. The participants were part of the NIH MRI Study of Normal Brain Development. Child Behavior Checklist A/D scores and diffusion imaging were available for 175 youths (84 males, 91 females; 241 magnetic resonance imagings) at up to three visits. The participants ranged from 5.7 to 18.4 years of age at the time of the scan. Alignment of fractional anisotropy data was implemented using FSL/Tract-Based Spatial Statistics, and linear mixed model regression was carried out using SPSS. Child Behavior Checklist A/D was associated with the rate of microstructural development in several white matter pathways, including the bilateral anterior thalamic radiation, bilateral inferior longitudinal fasciculus, left superior longitudinal fasciculus, and right cingulum. Across these pathways, greater age-related fractional anisotropy increases were observed at lower levels of A/D. The results suggest that subclinical A/D symptoms are associated with the rate of microstructural development within several white matter pathways that have been implicated in affect regulation, as well as mood and anxiety psychopathology.</jats:p

    Web-based multimodal graphs for visually impaired people

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    This paper describes the development and evaluation of Web-based multimodal graphs designed for visually impaired and blind people. The information in the graphs is conveyed to visually impaired people through haptic and audio channels. The motivation of this work is to address problems faced by visually impaired people in accessing graphical information on the Internet, particularly the common types of graphs for data visualization. In our work, line graphs, bar charts and pie charts are accessible through a force feedback device, the Logitech WingMan Force Feedback Mouse. Pre-recorded sound files are used to represent graph contents to users. In order to test the usability of the developed Web graphs, an evaluation was conducted with bar charts as the experimental platform. The results showed that the participants could successfully use the haptic and audio features to extract information from the Web graphs

    Some chemical constituents isolated from Acorus tatarinowii Shott.

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    Anew 8,1′-neolignan, tatarinone, 4-[2-(1,2,3-trimethoxybenz-5-yl)-1-methylethyl]-2,5-dimethoxy-4-(2-propenyl)-2,5-cyclohexadien-1-one, has been isolated from Acorus tatarinowii rhizome and  its structure determined by spectroscopic methods, including 2D-NMR spectra. Asarylaldehyde and a mixture of α-asarone and β-asarone were also isolated and  indentified.Keywords: Acorus tatarinowii;Araceae; 8,1′-neolignans; asarylaldehyde; α-asarone; β-asarone; NMR

    Functional MRI comparison of passive and active movement: possible inhibitory role of supplementary motor area:

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    Recent studies have hypothesized that the supplementary motor area plays a role in motor inhibition. To study this possible role, we used functional MRI study to compare conditions, which require various level of inhibition of motor patterns. Seventeen healthy participants were scanned while executing – actively or passively – rhythmic opening/closing movements of their right hand, with and without congruent visual information. The contrast passive&gt;active movement in the visual guidance condition which requires inhibition in order ‘not’ to perform the movement, yields to significant activation of areas commonly involved in the inhibitory brain circuitry among which, notably, controlateral supplementary motor area

    Usefulness of Parent-Completed ASQ for Neurodevelopmental Screening of Preterm Children at Five Years of Age.

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    International audienceINTRODUCTION: Preterm children are at greater risk of developmental impairment and require close follow-up for early and optimal medical care. Our goal was to examine use of the parent-completed Ages and Stages Questionnaire (ASQ) as a screening tool for neurodevelopmental disabilities in preterm infants at five years of age.PATIENTS AND METHODS: A total of 648 preterm children (285 were not distinctive for mild delay or normal development. In children with developmental delay, no difference was found when ASQ scores according to maternal education levels were analyzed.CONCLUSIONS: ASQ at five years is a simple and cost-effective tool that can detect severe developmental delay in preterm children regardless of maternal education level, while its capacity to identify children with mild delay appears to be more limited

    Towards Noncommutative Fuzzy QED

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    We study in one-loop perturbation theory noncommutative fuzzy quenched QED_4. We write down the effective action on fuzzy S**2 x S**2 and show the existence of a gauge-invariant UV-IR mixing in the model in the large N planar limit. We also give a derivation of the beta function and comment on the limit of large mass of the normal scalar fields. We also discuss topology change in this 4 fuzzy dimensions arising from the interaction of fields (matrices) with spacetime through its noncommutativity.Comment: 33 page

    GIVE: portable genome browsers for personal websites.

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    Growing popularity and diversity of genomic data demand portable and versatile genome browsers. Here, we present an open source programming library called GIVE that facilitates the creation of personalized genome browsers without requiring a system administrator. By inserting HTML tags, one can add to a personal webpage interactive visualization of multiple types of genomics data, including genome annotation, "linear" quantitative data, and genome interaction data. GIVE includes a graphical interface called HUG (HTML Universal Generator) that automatically generates HTML code for displaying user chosen data, which can be copy-pasted into user's personal website or saved and shared with collaborators. GIVE is available at: https://www.givengine.org/
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