Effect of dimensions on the efficiency of radiant energy cells

Effect of dimensions on quantum and photovoltaic energy conversion efficiency of germanium p-n semiconducting cell

Nonuniversal exponents in sandpiles with stochastic particle number transfer

We study fixed density sandpiles in which the number of particles transferred to a neighbor on relaxing an active site is determined stochastically by a parameter $p$. Using an argument, the critical density at which an active-absorbing transition occurs is found exactly. We study the critical behavior numerically and find that the exponents associated with both static and time-dependent quantities vary continuously with $p$.Comment: Some parts rewritten, results unchanged. To appear in Europhys. Let

Relevance of inter-composite fermion interaction to the edge Tomonaga-Luttinger liquid

It is shown that Wen's effective theory correctly describes the Tomonaga-Luttinger liquid at the edge of a system of non-interacting composite fermions. However, the weak residual interaction between composite fermions appears to be a relevant perturbation. The filling factor dependence of the Tomonaga-Luttinger parameter is estimated for interacting composite fermions in a microscopic approach and satisfactory agreement with experiment is achieved. It is suggested that the electron field operator may not have a simple representation in the effective one dimensional theory.Comment: 5 pages; accepted in Phys. Rev. Let

Evolutionary dynamics of the most populated genotype on rugged fitness landscapes

We consider an asexual population evolving on rugged fitness landscapes which are defined on the multi-dimensional genotypic space and have many local optima. We track the most populated genotype as it changes when the population jumps from a fitness peak to a better one during the process of adaptation. This is done using the dynamics of the shell model which is a simplified version of the quasispecies model for infinite populations and standard Wright-Fisher dynamics for large finite populations. We show that the population fraction of a genotype obtained within the quasispecies model and the shell model match for fit genotypes and at short times, but the dynamics of the two models are identical for questions related to the most populated genotype. We calculate exactly several properties of the jumps in infinite populations some of which were obtained numerically in previous works. We also present our preliminary simulation results for finite populations. In particular, we measure the jump distribution in time and find that it decays as $t^{-2}$ as in the quasispecies problem.Comment: Minor changes. To appear in Phys Rev

Two-Proton Radioactivity with 2p halo in light mass nuclei A==18−-34

Two-proton radioactivity with 2p halo is reported theoretically in light mass nuclei A $=$ 18-34. We predict $^{19}$Mg, $^{22}$Si, $^{26}$S, $^{30}$Ar and $^{34}$Ca as promising candidates of ground state 2p-radioactivity with S$_{2p}$ $$ 0. Observation of extended tail of spatial charge density distribution, larger charge radius and study of proton single particle states, Fermi energy and the wave functions indicate 2p halo like structure which supports direct 2p emission. The Coulomb and centrifugal barriers in experimentally identified 2p unbound $^{22}$Si show a quasi-bound state that ensures enough life time for such experimental probes. Our predictions are in good accord with experimental and other theoretical data available so far.Comment: 5 Pages, 5 figure

Prevalence of Mental Distress and Addiction Habits among Medical Undergraduates

Introduction: Medical education across the globe is perceived as being inherently stressful leading to mental distress in medical undergraduates. Among all psychological problems, stress is one of the common problems faced by medical students. Stress is a situation that leads to tension, pressure or negative emotions such as anxiety, depression and anger. Exposure to chronic stress can lead to both physical and mental illnesses. The stressors among medical students are academic, social, personal and financial. Psychological distress among students reduces their self-esteem, quality of life and academic performance. They may engage in potentially harmful methods of coping with stress such as tobacco, alcohol and substance abuse. Objective: The present study was conducted to determine the prevalence of stressrelated problems among medical undergraduates using DASS 21 scale and also to find prevalence of addiction habits in relation to stress. Methods: It was a cross-sectional study done among medical undergraduate students. Prevalence of psychological mood disorders was assessed by using DASS-21. A pretested and predesigned questionnaire was also prepared assessing correlation of mental distress with sociodemographic characteristics and addiction habits among medical undergraduates. Results: Prevalence of depression, anxiety and stress was found to be very high among medical undergraduates with prevalence being more in females as compared to males. Hostellers were found to have more mental distress as compared to day scholars. As compared to females, males were more engaged in addiction habits mostly consumption of alcohol. Conclusion: Family support, counselling lessons and various other methods of stress management should be given to the medical students to decrease the stress level and make them aware of healthy ways of living