Biomedical subjects

R N Bhatt

Publications and source records attributed to R N Bhatt.

5 recordsLinked to original sources

PubMed2005

Understanding and improving the Wang-Landau algorithm.

We present a mathematical analysis of the Wang-Landau algorithm, prove its convergence, and identify sources of errors and strategies for optimization. In particular, we found the histogram increases uniformly with small fluctuations after a stage of initial accumulation, and the statistical error is found to scale as square root of (ln f) with the modification factor f . This has implications for strategies for obtaining fast convergence.

Journal Article↗

PubMed2004

Laterally modulated 2D electron system in the extreme quantum limit.

We report on magnetotransport of a two-dimensional electron system (2DES), located 32 nm below the surface, with a surface superlattice gate structure of periodicity 39 nm imposing a periodic modulation of its potential. For low Landau level fillings nu, the diagonal resistivity displays a rich pattern of fluctuations, even though the disorder dominates over the periodic modulation. Theoretical arguments based on the combined effects of the long-wavelength, strong disorder and the short-wavelength, weak periodic modulation present in the 2DES qualitatively explain the data.

Journal Article↗

PubMed2003

Disorder-driven collapse of the mobility gap and transition to an insulator in the fractional quantum Hall effect.

We study the nu=1/3 quantum Hall state in the presence of random disorder. We calculate the topologically invariant Chern number, which is the only quantity known at present to distinguish unambiguously between insulating and current carrying states in an interacting system. The mobility gap can be determined numerically this way and is found to agree with experimental value semiquantitatively. As the disorder strength increases towards a critical value, both the mobility gap and plateau width narrow continuously and ultimately collapse, leading to an insulating phase.

Journal Article↗

PubMed2001

Effects of disorder on ferromagnetism in diluted magnetic semiconductors.

We present results of a numerical mean-field treatment of interacting spins and carriers in doped diluted magnetic semiconductors, which takes into account the positional disorder present in these alloy systems. Within our mean-field approximation, disorder enhances the ferromagnetic transition temperature for metallic densities not too far from the metal-insulator transition. Concurrently, the ferromagnetic phase is found to have very unusual temperature dependence of the magnetization as well as specific heat as a result of disorder. Unusual spin and charge transport is implied.

Journal Article↗

PubMed1993

Interspecific associations among anophelines in different breeding habitats of Kheda district Gujarat: Part II--Non-canal area.

A total of 25,858 anophelines comprising 15 species emerged from 1104 samples of immatures from 9 breeding habitats surveyed for one year in six villages representing the non-canal area of Kheda district. Species diversity and homogeneity were maximum in seepage drains. An. annularis, An. barbirostris, An. culicifacies, An. stephensi and An. subpictus were ubiquitous. Interspecific associations occurred more commonly in habitats representing the stable ecosystem. Community groups of anophelines in different habitats were identified.

Animals↗