Exotic orbits due to spin-spin coupling around Kerr black holes

We report exotic orbital phenomena of spinning test particles orbiting around a Kerr black hole, i.e., some orbits of spinning particles are asymmetrical about the equatorial plane. When a nonspinning test particle orbits around a Kerr black hole in a strong field region, due to relativistic orbital precessions, the pattern of trajectories is symmetrical about the equatorial plane of the Kerr black hole. However, the patterns of the spinning particles' orbit are no longer symmetrical about the equatorial plane for some orbital configurations and large spins. We argue that these asymmetrical patterns come from the spin-spin interactions between spinning particles and Kerr black holes, because the directions of spin-spin forces can be arbitrary, and distribute asymmetrically about the equatorial plane.Comment: 15 pages, 20 figure

Body image distortions and muscle dysmorphia symptoms among Asian men : do exercise status and type matter?

Theoretical Framework: Body image distortions and muscle dysmorphia symptoms were assessed among 78 Asian men who engaged in regular resistance training, aerobic training or did not engage in either. Method: Body fat and muscularity were measured and participants also completed the Muscle Dysmorphia Disorder Inventory. Results: Resistance trained men selected a body shape ideal that was higher in muscularity and lower in body fat. Aerobically trained men also reported higher perceived current Body Fat even though their actual levels were close to their ideal. Conclusion: The results suggest that specificity in body image distortion (e.g., perceived current-ideal versus perceived current-actual) when examining body image distortions might reduce conflicting findings in extant research

Estimating Marginal Hazard Ratios by Simultaneously Using A Set of Propensity Score Models: A Multiply Robust Approach

The inverse probability weighted Cox model is frequently used to estimate marginal hazard ratios. Its validity requires a crucial condition that the propensity score model is correctly specified. To provide protection against misspecification of the propensity score model, we propose a weighted estimation method rooted in empirical likelihood theory. The proposed estimator is multiply robust in that it is guaranteed to be consistent when a set of postulated propensity score models contains a correctly specified model. Our simulation studies demonstrate satisfactory finite sample performance of the proposed method in terms of consistency and efficiency. We apply the proposed method to compare the risk of postoperative hospitalization between sleeve gastrectomy and Roux-en-Y gastric bypass using data from a large medical claims and billing database.We further extend the development to multi-site studies to enable each site to postulate multiple site-specific propensity score models