Planar Two-particle Coulomb Interaction: Classical and Quantum Aspects

The classical and quantum aspects of planar Coulomb interactions have been studied in detail. In the classical scenario, Action Angle Variables are introduced to handle relativistic corrections, in the scheme of time-independent perturbation theory. Complications arising due to the logarithmic nature of the potential are pointed out. In the quantum case, harmonic oscillator approximations are considered and effects of the perturbations on the excited (oscillator) states have been analysed. In both the above cases, the known 3+1-dimensional analysis is carried through side by side, for a comparison with the 2+1-dimensional (planar) results.Comment: LaTex, Figures on request, e-mail:<[email protected]

Internal magnetic fields in thin ZnSe epilayers

Strain induced spin-splitting is observed and characterized using pump-probe Kerr rotation spectroscopy in n-ZnSe epilayers grown on GaAs substrates. The spin-splitting energies are mapped out as a function of pump-probe separation, applied voltage, and temperature in a series of samples of varying epilayer thicknesses and compressive strain arising from epilayer-substrate lattice mismatch. The strain is independently quantified using photoluminescence and x-ray diffraction measurements. We observe that the magnitude of the spin splitting increases with applied voltage and temperature, and is highly crystal direction dependent, vanishing along [1 1-bar 0].Comment: 9 pages, 3 figure

Effect of Basin Versus Drip Irrigation on Quality Production in Mosambi Sweet Orange

An investigation was undertaken to find out the effect of basin and drip irrigation on growth, production, fruit quality, foliar N, P, K values and soil moisture status in Mosambi sweet orange grown in laterite soil. Treatments included drip irrigation at 0.6, 0.8 and 1.0 Epan with and without black polythene mulching, basin irrigation @ 30 liter/plant at 18 days interval + black polythene mulching and control (No watering + black polythene mulching). The plants receiving irrigation at 0.8 Epan + polythene mulching resulted 136 fruits per plant with superior in fruit quality in terms of highest TSS (11.2°B), sugar (8.5%) and vitamin C (47.8 mg/100ml) content. Maximum fruit weight of 166 g and diameter of 7.0 cm were recorded in the fruits of the plants which received irrigation at 1.0 Epan + polythene mulching. Foliar nitrogen content was highest (2.65%) in plants with drip irrigation at 0.8 Epan + polythene mulching while phosphorus and potassium content were non-significant among the treatments. Irrigation (drip or basin) of the plants during dry months resulted lower shoot drying as compared to no irrigation

Diamond degradation in hadron fields

The energy dependence of the concentration of primary displacements induced by protons and pions in diamond has been calculated in the energy range 50 MeV - 50 GeV, in the frame of the Lindhard theory. The concentrations of primary displacements induced by protons and pions have completely different energy dependencies: the proton degradation is very important at low energies, and is higher than the pion one in the whole energy range investigated, with the exception of the delta33 resonance region. Diamond has been found, theoretically, to be one order of magnitude more resistant to proton and pion irradiation in respect to silicon.Comment: 7 pages, 3 figure

Magnetized Accretion Inside the Marginally Stable Orbit around a Black Hole

Qualitative arguments are presented to demonstrate that the energy density of magnetic fields in matter accreting onto a black hole inside the marginally stable orbit is automatically comparable to the rest-mass energy density of the accretion flow. Several consequences follow: magnetic effects must be dynamically significant, but cannot be so strong as to dominate; outward energy transport in Alfven waves may alter the effective efficiency of energy liberation; and vertical magnetic stresses in this region may contribute to "coronal" activity.Comment: to appear in Ap. J. Letter

Current-Induced Polarization and the Spin Hall Effect at Room Temperature

Electrically-induced electron spin polarization is imaged in n-type ZnSe epilayers using Kerr rotation spectroscopy. Despite no evidence for an electrically-induced internal magnetic field, current-induced in-plane spin polarization is observed with characteristic spin lifetimes that decrease with doping density. The spin Hall effect is also observed, indicated by an electrically-induced out-of-plane spin polarization with opposite sign for spins accumulating on opposite edges of the sample. The spin Hall conductivity is estimated as 3 +/- 1.5 Ohms**-1 m**-1/|e| at 20 K, which is consistent with the extrinsic mechanism. Both the current-induced spin polarization and the spin Hall effect are observed at temperatures from 10 K to 295 K.Comment: 5 pages, 4 figure

Comparative Soil Organic Carbon Dynamics in Tropical and Subtropical Grassland Ecosystems

Grassland ecosystems play significant role in mitigating the climate change by sequestering atmospheric CO2. One fifth of the total terrestrial C is stored in the root zone of grasslands as soil organic carbon. However, because of lack of proper management, overgrazing, and conversion to crop lands, these grasslands are becoming a source of CO2 emissions. It has been observed that in Imperata grasslands of Northeast India, a third of total C captured annually is lost though CO2 emissions. In the absence of intensified grazing and burning, these grasslands exhibit significantly high capacity to store SOC stocks. On the other hand, Southern grasslands of China inherently have a weak C sink. Grazing and burning together significantly increased CO2 fluxes as observed in Andean grasslands. With the introduction of high yielding grass species and with liberal use of chemical fertilizers, grazing land intensification has been found to rather promote SOC sequestration. It has been observed that in C4 grass species dominated tropical and sub-tropical grasslands; there occurs a rapid transfer of plant C into mineral-dominated C pools. With change of C3 to C4 grass species, the grazer effects rather shift from negative to positive even under decreasing precipitation conditions. Similarly, rise in atmospheric temperatures due to climate change affects grasslands differently depending on the dominating grass species. Graminoids and shrubs appear to benefit from elevated temperatures while forbs are likely to decrease in abundance through competitive elimination. Extreme heat waves and frequent drought events is decreasing the extent and capacity of forests as C sink as compared to grasslands. Grasslands have been shown to be comparatively more resilient to changes in climate. The resilience of grasslands to rising temperatures, drought and fire events helps to preserve sequestered terrestrial C in the root-zone of grassland soil and prevent it from re-entering atmosphere

Drought Mitigation in Bundelkahand Grassland Ecosystem for Improving Livelihood of Farming Community-A Case Study

Bundelkhand grassland ecosystem (23º20´ and 26°20´N latitude and 78°20´ and 81°40´E longitude) is an undulating rain fed region (annual rain fall, 768-1087 mm) spread over an area of 7.08 m ha in central India in the states of Madhya Pradesh and Uttar Pradesh. This region has to support 16 million human and 8.5 million animal populations. Area is prone to surface run off losses, severe soil erosion and increasingly more drought events, leading to only mono-cropping. Lively-hood of the people, which is mainly the live-stock rearing and marginal agriculture, is at stake. In-situ conservation of rain water, forage management, and environmental services are the main issues to be addressed at priority to enhance productivity per unit area of this biome. Development funds amounting to about 1000 million US$, provided for constructing sustainable infrastructure like check-dams, dug-wells, embankments, rising of crest height etc. has significantly improved the surface and ground water resources. Impact evaluation as discussed in this paper includes water resource development, watershed management, crop and live-stock productivity, and rural drinking water. A robust and resilient management system has been developed through farmer’s participatory integrated watershed management program. Major aim is in-situ conservation of the rain water and recharging the dug wells, open wells, village ponds, and farm ponds. It has remarkably improved the financial condition of farming community. Initiation of restoration process of this grassland biome has increased its carrying capacity by 41%. An additional 25% land area has come under irrigation resulting in increase of net-sown area by 11%, cropping intensity by 6%, and farm income by 35%

Noncommutative Chern-Simons Soliton

We have studied the noncommutative extension of the relativistic Chern-Simons-Higgs model, in the first non-trivial order in $\theta$, with only spatial noncommutativity. Both Lagrangian and Hamiltonian formulations of the problem have been discussed, with the focus being on the canonical and symmetric forms of the energy-momentum tensor. In the Hamiltonian scheme, constraint analysis and the induced Dirac brackets have been provided. The spacetime translation generators and their actions on the fields are discussed in detail. The effects of noncommutativity on the soliton solutions have been analysed thoroughly and we have come up with some interesting observations. Considering the {\it{relative}} strength of the noncommutative effects, we have shown that there is a universal character in the noncommutative correction to the magnetic field - it depends {\it{only}} on $\theta$. On the other hand, in the cases of all other observables of physical interest, such as the potential profile, soliton mass or the electric field, $\theta$ as well as $\tau$, (comprising solely of commutative Chern-Simons-Higgs model parameters), appear on similar footings. This phenomenon is a new finding which has come up in the present analysis. Lastly, we have pointed out a generic problem in the NC extension of the models, in the form of a mismatch between the BPS dynamical equation and the full variational equations of motion, to $O(\theta)$. This mismatch indicates that the analysis is not complete as it brings in to fore the ambiguities in the definition of the energy-momentum tensor in a noncommutative theory.Comment: 21 page