Control of star formation by supersonic turbulence

Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support, modulated by ambipolar diffusion. Recently, however, both observational and numerical work has begun to suggest that support by supersonic turbulence rather than magnetic fields controls star formation. In this review we outline a new theory of star formation relying on the control by turbulence. We demonstrate that although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic scale star formation. (ABSTRACT ABBREVIATED)Comment: Invited review for "Reviews of Modern Physics", 87 pages including 28 figures, in pres

Metabolic Syndrome and Health-Related Quality of Life in Obese Individuals Seeking Weight Reduction

Background: No previous research has examined the association between metabolic syndrome (MetSyn) and health-related quality of life (HRQoL) using standard criteria for defining MetSyn. We hypothesized that MetSyn would be associated with lower HRQoL on measures of physical and mental health. Methods and Procedures: Participants were 361 individuals in two randomized weight loss trials. MetSyn was defined by the National Cholesterol Education Panel criteria. The Medical Outcomes Study, Short Form-36 (SF-36) was used to assess HRQoL. Differences in HRQoL and in clinical and psychosocial characteristics were compared among participants with and without MetSyn. Multiple regression was used to determine predictors of HRQoL. Results: MetSyn was associated with lower scores on the physical function and general health subscales of the SF-36 and on the physical component summary (PCS) score. This association remained after controlling for age or depression but was eliminated by controlling for BMI. MetSyn was not associated with lower mental quality of life, a higher depression score, tobacco or alcohol use, or a higher rate of psychosocial stressors. Discussion: Individuals with MetSyn reported lower HRQoL. This appeared to be an effect of increased weight, rather than a unique effect of MetSyn. Larger studies are needed to assess whether MetSyn may have an independent effect on HRQoL