73 research outputs found
A systematic review of the effects of exercise interventions on body composition in HIV+ adults
Get PDFOver the years, physical activity and exercise have been used to positively impact the health and quality of life of persons infected with HIV and, more recently, has been associated with a spectrum of body composition changes. The aim of this review was to examine the effects of various exercise interventions on body composition in HIV positive adults, using a search strategy of randomized, controlled trials (RCTs). A systematic review was performed by five independent reviewers using a predetermined protocol adapted from previous research for assessing the articles for inclusion, the extracted data, and methodological quality. Eight RCTs involving 430 (26% female) HIV positive adults performing exercise a minimum of thrice weekly for at least six weeks were finally selected: Four were progressive resistance training (PRT) studies, three were aerobic training (AT) studies, and one involved yoga. In the PRT studies, there were significant increases in three anthropometric measures, namely, body mass, sum of skinfolds and sum of limb girths. In the AT studies, significant decreases were found in seven anthropometric measures, namely, body mass index, waist-hip ratio, body mass, triceps skinfold, waist circumference and sum of skinfolds. With yoga, the changes were nonsignificant. Exercise contributes to improved body composition and, when applied safely, appears to be beneficial for adults living with HIV/AIDS. However, these findings should be interpreted cautiously due to the relatively few RCTs published to date. Future studies would benefit from increased attention to sample size, female participants, participant follow-up, complete statistical analysis and intention-to-treat analysis.Scopu
Dust in Supernovae and Supernova Remnants I : Formation Scenarios
Get PDFSupernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe
Linear Line Polarimetry Modelling of Pre-main Sequence Stars
Get PDFOriginal paper can be found at: http://www.aspbooks.org/ Copyright ASPWe present emission line polarimetry data and modelling relevant to the circumstellar geometry and kinematics around pre-main sequence stars. For a sample of both Herbig Ae/Be stars and T Tauri stars, we find that most show polarization changes across H®, implying that flattened structures are common on the smallest scales { and over a range of stellar masses. We also present Monte Carlo calculations of spectral line profiles scattered in rotating accretion disks. We consider the case of a central star that emits line photons uniformly, as well as via hot spots. Intriguingly, the switch between a uniform point source and a finite-sized star results in a marked difference in the position angle variation across the line. Our models demonstrate the diagnostic potential of line polarimetry in determining the disk inclination and the size of the inner hole { a spatial scale no other technique currently accesses
- …
