Formation of rectifier with gold nanoclusters

Gold nanoclusters encapsulated with organic molecules are of great interest for its possible applications in the fields of molecular electronics, catalysis and medical science. Here we demonstrate that monolayer and bilayer films of thiol-capped gold nanoclusters can exhibit diode-like properties provided controlled spatial asymmetry exist between two tunnel junctions used to connect a thiol capped gold nanoclusters. Current-voltage characteristics of this rectifier were obtained from conducting probe atomic force microscopy measurements and also from conventional two probe resistance measurements. Systematic x-ray reflectivity and atomic force microscopy measurements were carried out to characterize the spatial asymmetry introduced by a monolayer of fatty acid salt gadolinium stearate used to deposit thiol-capped gold nanocluster molecules on hydrophilic SiO2-Si(001) substrate by Langmuir Blodgett technique. This information was used to explain prominent rectification observed in these nano-structured films.Comment: 13 pages, 3 figure

Hysteretic Optimization

We propose a new optimization method based on a demagnetization procedure well known in magnetism. We show how this procedure can be applied as a general tool to search for optimal solutions in any system where the configuration space is endowed with a suitable `distance'. We test the new algorithm on frustrated magnetic models and the traveling salesman problem. We find that the new method successfully competes with similar basic algorithms such as simulated annealing.Comment: 5 pages, 5 figure

Stability analysis of an eco-epidemiological model incorporating a prey refuge

The present paper deals with the problem of a predator-prey model incorporating a prey refuge with disease in the prey-population. We assume the predator population will prefer only infected population for their diet as those are more vulnerable. Dynamical behaviours such as boundedness, permanence, local and global stabilities are addressed. We have also studied the effect of discrete time delay on the model. The length of delay preserving the stability is also estimated. Computer simulations are carried out to illustrate our analytical findings

Symmetric and anti-symmetric Landau parameters and magnetic properties of dense quark matter

We calculate the dimensionless Fermi liquid parameters (FLPs), $F_{0,1}^{sym}$ and $F_{0,1}^{asym}$, for spin asymmetric dense quark matter. In general, the FLPs are infrared divergent due to the exchange of massless gluons. To remove such divergences, the Hard Density Loop (HDL) corrected gluon propagator is used. The FLPs so determined are then invoked to calculate magnetic properties such as magnetization $\langle M\rangle$ and magnetic susceptibility $\chi_M$ of spin polarized quark matter. Finally, we investigate the possibility of magnetic instability by studying the density dependence of $\langle M\rangle$ and $\chi_M$.Comment: 14 pages, 5 figures, abstract and introduction modifified. Published in Phys. Rev. C. 81, 054906 (2010

Sympathovagal Imbalance in Prehypertensive Offspring of Two Parents versus One Parent Hypertensive

Objective. Though prehypertension has strong familial predisposition, difference in pathophysiological mechanisms in its genesis in offspring of both parents and single parent hypertensive have not been elucidated. Methods. Body mass index (BMI), waist-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), HR and BP response to standing, deep breathing difference, BP response to handgrip and spectral indices of heart rate variability (HRV) were analyzed in normotensive offspring of two parents hypertensive (Group I), normotensive offspring of one parent hypertensive (Group II), prehypertensive offspring of two parents hypertensive (Group III) and prehypertensive offspring of one parent hypertensive (Group IV). Results. Sympathovagal imbalance (SVI) in prehypertensive offspring was observed due to increased sympathetic and decreased vagal activity. In group III, SVI was more prominent with greater contribution by vagal withdrawal. LF-HF ratio, the marker of SVI was correlated more with diastolic pressure, 30 : 15 ratio and E : I ratio in prehypertensives and the degree of correlation was more in group III prehypertensives. Conclusion. Vagal withdrawal plays a critical role in development of SVI in prehypertensive offspring of hypertensive parents. The intensity of SVI was more in offspring of two parents hypertensive compared to single parent hypertensive