Temporal Decomposition Studies of GRB Lightcurves

Gamma-ray bursts (GRB) are extremely energetic events and produce highly diverse light curves. Light curves are believed to be resulting from internal shocks reflecting the activities of the GRB central engine. Hence their temporal studies can potentially lead to the understanding of the GRB central engine and its evolution. The light curve variability time scale is an interesting parameter which most models attribute to a physical origin e.g., central engine activity, clumpy circumburst medium, or relativistic turbulence. We develop a statistical method to estimate the GRB minimum variability time scale (MVT) for long and short GRBs detected by GBM. We find that the MVT of short bursts is distinctly shorter than that for long GRBs supprting the possibility of a more compact central engine of the former. We find that MVT estimated by this method is consistent with the shortest rise time of the fitted pulses. Hence we use the fitted pulse rise times to study the evolution of burst variability time scale. Variability time is in turn related to the minimum bulk Lorentz factor. Using this we relate the GRB spectral evolution to the evolution of the variability time scale. %Gamma-ray burst (GRB) light curves are believed to result from internal shocks reflecting the activities of the GRB central engine. %Hence their temporal deconvolution studies can potentially lead to the understanding of the evolution of the minimum variability %time scales which in turn is related to the minimum bulk Lorentz factor. We relate the GRB spectral evolution to the evolution of the %minimum variability time scale.Comment: 5 pages 6 figures. Presented at GRB2012 at Marbella, Spai

A Study on Proteolytic Enzyme Activity in the Erythrocytes of Diabetic Patients

The present study demonstrates the possibility of increased proteolytic activities in diabetic individuals. Proteolytic activity was measured by the amount of amino group released by the erythrocyte lysate of the diabetic individual using phenylhydrazine treated hemoglobin as substrate. The proteolytic activity in erythrocyte lysates against oxidatively damaged hemoglobin was significantly increased in diabetic individuals compared to controls (p<0.001).The result of this study indicates that in diabetic individuals, proteolytic enzymes degrade many oxidatively altered proteins preventing the accumulation of altered and damaged proteins in the cell

Scaling of the risk landscape drives optimal life history strategies and the evolution of grazing

Consumers face numerous risks that can be minimized by incorporating different life-history strategies. How much and when a consumer adds to its energetic reserves or invests in reproduction are key behavioral and physiological adaptations that structure much of how organisms interact. Here we develop a theoretical framework that explicitly accounts for stochastic fluctuations of an individual consumer's energetic reserves while foraging and reproducing on a landscape with resources that range from uniformly distributed to highly clustered. First, we show that optimal life-history strategies vary in response to changes in the mean productivity of the resource landscape, where depleted environments promote reproduction at lower energetic states, greater investment in each reproduction event, and smaller litter sizes. We then show that if resource variance scales with body size due to landscape clustering, consumers that forage for clustered foods are susceptible to strong Allee effects, increasing extinction risk. Finally, we show that the proposed relationship between consumer body size, resource clustering, and Allee effect-induced population instability offers key ecological insights into the evolution of large-bodied grazing herbivores from small-bodied browsing ancestors.Comment: 9 pages, 5 figures, 3 Supplementary Appendices, 2 Supplementary Figure