Phase delay time and superluminal propagation in barrier tunneling

In this work we study the behaviour of Wigner phase delay time for tunneling in the reflection mode. Our system consists of a circular loop connected to a single wire of semi-infinite length in the presence of Aharonov-Bohm flux. We calculate the analytical expression for the saturated delay time. This saturated delay time is independent of Aharonov- Bohm flux and the width of the opaque barrier thereby generalizing the Hartman effect. This effect implies superluminal group velocities as a consequence. We also briefly discuss the concept called "space collapse or space destroyer".Comment: 5 pages, 5 figure

Application of semi-implicit scheme of integration to barotropic prediction

Application of a semi-implicit version of primitive equation barotropic model to predict monsoon depressions is proposed. Forecasts upto 48 hr have been quite satisfactory. The results are compared with those obtained from an explicit version of primitive equation barotropic model developed earlier. The flow patterns from these two versions are similar with few exceptions in isolated pockets, however, the forecast movement obtained from the semi-implicit version is comparable or slightly superior to those obtained from the explicit version. The computational time in semi-implicit and explicit schemes is approximately in the ratio of 1:2

Stochastic thermodynamics of macrospins with fluctuating amplitude and direction

We consider stochastic energy balance and entropy production (EP) in a generalized Langevin dynamics of macrospins, allowing for both amplitude and direction fluctuations, under external magnetic field. EP is calculated using Fokker-Planck equation, distinguishing between reversible and irreversible parts of probability currents. The system entropy increases due to irreversible non-equilibrium processes, and reduces as heat dissipates to surrounding environment. Using path probability distributions of time-forward trajectories and conjugate trajectories under time reversal, we obtain fluctuation theorems (FT) for total stochastic EP. We show that the choice of conjugate trajectories is crucial in obtaining entropy like quantities that obey FTs.Comment: 7 pages, no figure; version accepted for publication in Phys. Rev.

Electrical and microphysical responses to salt seeding in warm maritime cumulus clouds

Electrical, microphysical and dynamical responses to salt seeding have been investigated during cloud seeding experiments in several parts of India. Following massive salt seeding, increases in cloud temperature by I to 2 Celsius and cloud liquid water content up to 200 percent were observed in warm cumulus clouds (Ramahandra Murty eta., 1975, 1976). Cloud drop size distributions in seeded warm cumulus clouds increased in mean volume diameter up to 478 percent and computed liquid water content increased upward of 60 percent (Kapoor et al., 1976). In maritime warm cumulus clouds, which developed rain following seeding, the electric field reversed from initial negative to positive, occasionally preceded by intensification (Ramachandra Murty et al., 1976). This field reversal was attributed to the transport of large positive charges, from upper cloud levels to the base, by raindrops which form initially at higher levels in vigorous updraft regions. The prior intensification was attributed to updraft invigoration produced by massive salt seeding, since electrical activity is closely associated with convective activity (Latham and Stow, 1969)

Integration of biocontrol agents with fungicide, weedicide and plant growth regulator for management of stem and root rot of jute

Combination of chemical fungicides (viz., Carbendazim 50 WP and Tebuconazole 250 EC) and biocontrol agents (viz., Pseudomonas fluorescens Psfl1, P. striata Pst1, Azotobacter chrococcum Azbc3, Bradyrhizobium japonicum Brj4, Trichoderma aureoviridae S12, T. harzianum JTV2, T. virens JPG1, Aspergillus niger AN15 strains respectively either singly or in consortium) were used to counteract Macrophomina phaseolina, the causal organism of stem and root rot of jute. In addition, suitable plant growth regulator viz., Indole-3-acetic acid (100-1.0 µg/ppm) and herbicide Quizalofop ethyl 5 % EC were used to augment the activity of Trichoderma. T. aureoviridae strain S12 was found to be the best among the eight isolates screened for tolerance against the two fungicides and herbicide at a concentration of 10000 - 500 µg respectively as well as against M. phaseolina (Inhibition=72.33 %) in-vitro. This strain showed best compatibility with other strains and highest tolerance to fungicide i.e., Carbendazim 50 % (up to 500 ?g). Highest number (13.7×106) of active spores was recorded at a concentration of 25 ppm of IAA under in-vitro condition. S12 recorded a biocontrol efficiency of 61.8 % against stem rot of jute along with significant plant growth promotion and fibre production. Plant biomass also increased up to 7.5-12.1 % and fibre production 37.0-39.9 % with fungal and bacterial consortium + carbendazim seed dressing and soil drenching. These biocontrol fungi and PGPR consortium with high tolerance to fungicide, weedicide and plant growth regulator up to certain extent may be potentially exploited in IDM which may be a low cost technology in jute and allied fibre crops

Energy absorption by "sparse" systems: beyond linear response theory

The analysis of the response to driving in the case of weakly chaotic or weakly interacting systems should go beyond linear response theory. Due to the "sparsity" of the perturbation matrix, a resistor network picture of transitions between energy levels is essential. The Kubo formula is modified, replacing the "algebraic" average over the squared matrix elements by a "resistor network" average. Consequently the response becomes semi-linear rather than linear. Some novel results have been obtained in the context of two prototype problems: the heating rate of particles in Billiards with vibrating walls; and the Ohmic Joule conductance of mesoscopic rings driven by electromotive force. Respectively, the obtained results are contrasted with the "Wall formula" and the "Drude formula".Comment: 8 pages, 7 figures, short pedagogical review. Proceedings of FQMT conference (Prague, 2011). Ref correcte

Quantum current magnification in a multi-channel mesoscopic ring

We have studied the current magnification effect in a multi-channel open mesoscopic ring. We show that the current magnification effect is robust even in the presence of several propagating modes inspite of mode mixing and cancellation effects. The magnitude of circulating currents in the multi-channel regime can be much larger than that in a single channel case. Impurities can enhance or degrade the current magnification effect depending sensitively on the system parameters. Circulating currents are mostly associated with Fano resonances in the total transport current. We further show that system-lead coupling qualitatively changes the current magnification effect.Comment: 12 pages, 11 figure