Half Cycle Pulse Train Induced State Redistribution of Rydberg Atoms

Population transfer between low lying Rydberg states independent of the initial state is realized using a train of half-cycle pulses with pulse durations much less than the classical orbit period. We demonstrate experimentally the transfer of population from initial states around n=50 down to n<40 as well as up to the continuum. The measured population transfer matches well to a model of the process for 1D atoms.Comment: V2: discussion extended, version accepted for publication in Physical Review

Collapse/Flattening of Nucleonic Bags in Ultra-Strong Magnetic Field

It is shown explicitly using MIT bag model that in presence of ultra-strong magnetic fields, a nucleon either flattens or collapses in the direction transverse to the external magnetic field in the classical or quantum mechanical picture respectively. Which gives rise to some kind of mechanical instability. Alternatively, it is argued that the bag model of confinement may not be applicable in this strange situation.Comment: 8 pages, REVTEX, 3 figures .eps files (included

Influence of Vehicular Emissions (NO, NO2, CO and NMHCs) on the Mixing Ratio of Atmospheric Ammonia (NH3) in Delhi, India

Mixing ratios of atmospheric ammonia (NH3), nitric oxide (NO), carbon monoxide (CO), nonmethane hydrocarbons (NMHCs), and methane (CH4) were measured to investigate the vehicular emissions, which are a dominant source of atmospheric NH3 in urban sites of Delhi, India from January 2013 to December 2014. The annual average mixing ratios of NH3, NO, CO, NMHCs, and CH4 were 21.2 +/- 2.1 ppb, 21.2 +/- 6.1 ppb, 1.89 +/- 0.18 ppm, 0.67 +/- 0.21 ppm and 3.11 +/- 0.53 ppm, respectively. Considering NO as a tracer of vehicular plume, ambient NH3 was correlated with NO during peak traffic hour in the morning (7:00-10:00 h) and evening (17:00-19:00 h) and observed significant positive correlation between them. Result reveals that the mixing ratio of atmospheric NH3 significantly positive correlated with traffic related pollutants (NO, CO, and NHHCs) during all the seasons (winter, summer, and monsoon). During winter, the average mixing ratio of atmospheric NH3 was increased by 1.2-3.5 ppb in the morning peak hour, whereas increased by 0.3-1.6 ppb in the evening peak hour. Similarly, an increase in NH3 mixing ratio was observed during summer (morning: 1.2-2.7 ppb and evening: 1.5-1.6 ppb) and monsoon (morning: 0.4-3.6 ppb and evening: 0.9-1.4 ppb) seasons. The results emphasized that the traffic could be one of the dominant source of ambient NH3 at the urban site of Delhi, as illustrated by positive relationships of NH3 with traffic related co-pollutants (NO, CO and NMHCs)

Statistical Mechanics of DNA Rupture: Theory and Simulations

We study the effects of the shear force on the rupture mechanism on a double stranded DNA. Motivated by recent experiments, we perform the atomistic simulations with explicit solvent to obtain the distributions of extension in hydrogen and covalent bonds below the rupture force. We obtain a significant difference between the atomistic simulations and the existing results in the iterature based on the coarse-grained models (theory and simulations). We discuss the possible reasons and improve the coarse-grained model by incorporating the consequences of semi-microscopic details of the nucleotides in its description. The distributions obtained by the modified model (simulations and theoretical) are qualitatively similar to the one obtained using atomistic simulations.Comment: 18 pages, 9 figures. Accepted in J. Chem. Phys. (2013). arXiv admin note: text overlap with arXiv:1104.305

N=2 Supersymmetric Sigma Models and D-branes

We study D-branes of N=2 supersymmetric sigma models. Supersymmetric nonlinear sigma models with 2-dimensional target space have D0,D1,D2-branes, which are realized as A-,B-type supersymmetric boundary conditions on the worldsheet. When we embed the models in the string theory, the Kahler potential is restricted and leads to a 2-dim black hole metric with a dilaton background. The D-branes in this model are susy cycles and consistent with the analysis of conjugacy classes. The generalized metrics with U(n) isometry is proposed and dynamics on them are realized by linear sigma models. We investigate D-branes of the linear sigma models and compare the results with those in the nonlinear sigma models.Comment: 23 pages, 5 figure

Neutrality of a magnetized two-flavor quark superconductor

We investigate the effect of electric and color charge neutrality on the two-flavor color superconducting (2SC) phase of cold and dense quark matter in presence of constant external magnetic fields and at moderate baryon densities. Within the framework of the Nambu-Jona-Lasinio (NJL) model, we study the inter-dependent evolution of the quark's BCS gap and constituent mass with increasing density and magnetic field. While confirming previous results derived for the highly magnetized 2SC phase with color neutrality alone, we obtain new results as a consequence of imposing charge neutrality. In the charge neutral gapless 2SC phase (g2SC), a large magnetic field drives the color superconducting phase transition to a crossover, while the chiral phase transition is first order. At larger diquark-to-scalar coupling ratio $G_D/G_S$, where the 2SC phase is preferred, we see hints of the Clogston-Chandrasekhar limit at a very large value of the magnetic field ($B\sim 10^{19}$G), but this limit is strongly affected by Shubnikov de Haas-van Alphen oscillations of the gap, indicating the transition to a domain-like state.Comment: 19 pages, 7 figures, Matches with the published versio

Determining Composition of Volatiles in Couroupita guianensis Aubl. Through Headspace-Solid Phase Micro-Extraction (HS-SPME)

Composition of volatile components in Couroupita guianensis Aubl. flowers was analyzed using headspace-solid phase micro-extraction (HS-SPME), followed by capillary gas chromatography and mass spectrometry (GC-MS) separation and identification. In all, 75 compounds were identified accounting for 96.32% of the total volatiles present. The major groups of compounds present were oxygenated terpenoids (35.66%), alcohols (26.92%), esters (17.36%), mono-and sesqui-terpenoids (8.64%), aldehydes and ketones (4.71%), hydrocarbons (1.68%), phenols (0.18%), acids (0.754%) and heterocyclic compounds (0.42%) constituted a small proportion of the volatile profile. The most abundant individual constituent was eugenol (18.95%) followed by nerol (13.49%), (E,E) farnesol (12.88%), (E,E)-farnesyl acetate (6.68%), trans ocimene (6.02%), nootkatone (4.64%), geraniol (2.94%), 2-isopropenyl-5- methyl-4-hexenyl acetate (2.69%), cedr-8-en-13-ol (2.58%), (E,Z)-farnesyl acetate (2.40%) and methyl (11E)-11- hexadecenoate (2.041%). Analytical comparison of composition of volatiles in the flowers, obtained by different methods of extraction, viz., solvent extraction, micro-simultaneous extraction and headspace-solid phase microextraction, revealed specific variations in relative concentrations of the constituent chemicals. Linalool was the major chemical (21.5% and 14.9%) in solvent extract and micro-simultaneous extract, respectively, but appeared in negligible quantity (0.16%) in head-space analysis

Relativistic calculations of angular dependent photoemission time delay

Angular dependence of photoemission time delay for the valence $np_{3/2}$ and $np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold