4,876 research outputs found

    Physical fitness and activity levels among Chinese people with schizophrenia: A cross-sectional study with matched case-control comparison

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    People with schizophrenia have an increased risk of developing cardiometabolic diseases and a reduced life expectancy. Studies conducted mainly in Western settings report low amounts of activity and poor levels of fitness in this population. This study aims to compare physical fitness and activity levels between people with schizophrenia/healthy matched controls and investigate potential associations between these variables. A cross-sectional study was conducted with 57 community-dwelling people with schizophrenia and 57 age-, gender- and BMI-matched controls. Participants completed the International Physical Activity Questionnaire and the YMCA Fitness Assessment Protocol with accompanying cardiovascular/lung function tests. Cardiorespiratory fitness was significantly better in healthy matched controls than individuals with schizophrenia in all areas (all p<.05, d=0.38 to 1.06). Performance in best trunk flexion, half sit-ups and one-minute pulse recovery following the 3-minute step test were significantly worse in the schizophrenia group (all p<.001, d=0.76 to 1.04). Higher levels of weekly moderate activity (t=-2.66, p=.009) and total weekly activity levels (t=-2.013, p=.047) were reported by the healthy controls. Levels of vigorous activity were significantly correlated with some areas of lung functioning in the schizophrenia group (all p<.05). The findings show that Chinese people with schizophrenia have significantly poorer fitness than matched healthy controls, demonstrating the need to provide timely effective exercise-based interventions as a matter of routine to attenuate the risk of developing chronic physical illnesses

    The Ultraluminous X-ray Sources near the Center of M82

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    We report the identification of a recurrent ultraluminous X-ray source (ULX), a highly absorbed X-ray source (possibly a background AGN), and a young supernova remnant near the center of the starburst galaxy M82. From a series of Chandra observations taken from 1999 to 2005, we found that the transient ULX first appeared in 1999 October. The source turned off in 2000 January, but later reappeared and has been active since then. The X-ray luminosity of this source varies from below the detection level (~2.5e38 erg/s) to its active state in between ~7e39 erg/s and 1.3e40 erg/s (in the 0.5-10 keV energy band) and shows unusual spectral changes. The X-ray spectra of some Chandra observations are best fitted with an absorbed power-law model with photon index ranging from 1.3 to 1.7. These spectra are similar to those of Galactic black hole binary candidates seen in the low/hard state except that a very hard spectrum was seen in one of the observations. By comparing with near infrared images taken with the Hubble Space Telescope, the ULX is found to be located within a young star cluster. Radio imaging indicates that it is associated with a H II region. We suggest that the ULX is likely to be a > 100 solar mass intermediate-mass black hole in the low/hard state. In addition to the transient ULX, we also found a highly absorbed hard X-ray source which is likely to be an AGN and an ultraluminous X-ray emitting young supernova remnant which may be related to a 100-year old gamma-ray burst event, within 2 arcsec of the transient ULX.Comment: 9 pages, 8 figures. Accepted for publication in Ap

    Relativistic Compact Objects in Isotropic Coordinates

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    We present a matrix method for obtaining new classes of exact solutions for Einstein's equations representing static perfect fluid spheres. By means of a matrix transformation, we reduce Einstein's equations to two independent Riccati type differential equations for which three classes of solutions are obtained. One class of the solutions corresponding to the linear barotropic type fluid with an equation of state p=γρp=\gamma \rho is discussed in detail.Comment: 9 pages, no figures, accepted for publication in Pramana-Journal of Physic

    IL-33 ameliorates Alzheimer’s disease-like pathology and cognitive decline

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    Alzheimer’s disease (AD) is a devastating condition with no known effective treatment. AD is characterized by memory loss as well as impaired locomotor ability, reasoning, and judgment. Emerging evidence suggests that the innate immune response plays a major role in the pathogenesis of AD. In AD, the accumulation of β-amyloid (Aβ) in the brain perturbs physiological functions of the brain, including synaptic and neuronal dysfunction, microglial activation, and neuronal loss. Serum levels of soluble ST2 (sST2), a decoy receptor for interleukin (IL)-33, increase in patients with mild cognitive impairment, suggesting that impaired IL-33/ST2 signaling may contribute to the pathogenesis of AD. Therefore, we investigated the potential therapeutic role of IL-33 in AD, using transgenic mouse models. Here we report that IL-33 administration reverses synaptic plasticity impairment and memory deficits in APP/PS1 mice. IL-33 administration reduces soluble Aβ levels and amyloid plaque deposition by promoting the recruitment and Aβ phagocytic activity of microglia; this is mediated by ST2/p38 signaling activation. Furthermore, IL-33 injection modulates the innate immune response by polarizing microglia/macrophages toward an antiinflammatory phenotype and reducing the expression of proinflammatory genes, including IL-1β, IL-6, and NLRP3, in the cortices of APP/PS1 mice. Collectively, our results demonstrate a potential therapeutic role for IL-33 in AD

    Absolute Stability Limit for Relativistic Charged Spheres

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    We find an exact solution for the stability limit of relativistic charged spheres for the case of constant gravitational mass density and constant charge density. We argue that this provides an absolute stability limit for any relativistic charged sphere in which the gravitational mass density decreases with radius and the charge density increases with radius. We then provide a cruder absolute stability limit that applies to any charged sphere with a spherically symmetric mass and charge distribution. We give numerical results for all cases. In addition, we discuss the example of a neutral sphere surrounded by a thin, charged shell.Comment: 25 pages, 1 figure 1 June 07: Replaced with added citations to prior work along same line

    Solving Linear Coupled Fractional Differential Equations by Direct Operational Method and Some Applications

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    A new direct operational inversion method is introduced for solving coupled linear systems of ordinary fractional differential equations. The solutions so-obtained can be expressed explicitly in terms of multivariate Mittag-Leffler functions. In the case where the multiorders are multiples of a common real positive number, the solutions can be reduced to linear combinations of Mittag-Leffler functions of a single variable. The solutions can be shown to be asymptotically oscillatory under certain conditions. This technique is illustrated in detail by two concrete examples, namely, the coupled harmonic oscillator and the fractional Wien bridge circuit. Stability conditions and simulations of the corresponding solutions are given

    Constraints on Modified Gravity from Sunyaev-Zeldovich Cluster Surveys

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    We investigate the constraining power of current and future Sunyaev-Zeldovich cluster surveys on the f(R) gravity model. We use a Fisher matrix approach, adopt self-calibration for the mass- observable scaling relation, and evaluate constraints for the SPT, Planck, SPTPol and ACTPol surveys. The modified gravity effects on the mass function, halo bias, matter power spectrum, and mass-observable relation are taken into account. We show that, relying on number counts only, the Planck cluster catalog is expected to reduce current upper limits by about a factor of four, to {\sigma}fR0 = 3 {\times} 10-5 (68% confidence level). Adding the cluster power spectrum further improves the constraints to {\sigma}fR0 = 10-5 for SPT and Planck, and {\sigma}fR0 = 3 {\times} 10-6 for SPTPol, pushing cluster constraints significantly beyond the limit where number counts have no constraining power due to the chameleon screening mechanism. Further, the combination of both observables breaks degeneracies, especially with the expansion history (effective dark energy density and equation of state). The constraints are only mildly worsened by the use of self-calibration but depend strongly on the mass threshold of the cluster samples.Comment: 16 pages, 9 figure
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