Observation of coherent Josephson response in the non-linear ab-plane microwave impedance of YBa2Cu3O6.95YBa_{2}Cu_{3}O_{6.95} single crystals

We report novel non-linear phenomena in the $ab$-plane microwave impedance of $YBaCu_{2}O_{7-\delta }$ single crystals. The $R_s$ vs. $H_{rf}$ data are well described by the non-linear RSJ model : $\dot{\phi}+\sin \phi =i_{rf}\cos \omega t$. The entire crystal behaves like a single Josephson junction. The extraordinary coherence of the data suggests an intrinsic mechanism.Comment: 2 pages,1 figure, Submitted to Proc. of M^2SHTSC-V (Beijing), also available at http://sagar.physics.neu.edu/preprint

Comments on "Vortex Glass and Lattice Melting Transitions in a YNi_2B_2C Single Crystal"

Recently, Mun et.al. (Phys. Rev. Lett., 76, 2790 (1996)) have published their results on single crystal YNi_2B_2C, claiming that their experimental observations can be explained in terms of formation of Vortex Glass and Lattice melting. Our experiments, carried out on samples obtained from the SAME source, reveal a much richer phase diagram and span wider regions of experimental parameter space than Mun et. al. that encompasses most of their observations. We speculate that this material has anomalous intrinsic properties and the results cannot be explained by simple models about the flux lattice.Comment: 1 page, LaTeX type, 1 PostScript figure, Uses PRABIB.STY file, 600 dpi PS file available at http://sagar.physics.neu.edu/preprints.html To appear in Physical Review Letter

The squeezed generalized amplitude damping channel

Squeezing of a thermal bath introduces new features absent in an open quantum system interacting with an uncorrelated (zero squeezing) thermal bath. The resulting dynamics, governed by a Lindblad-type evolution, extends the concept of a generalized amplitude damping channel, which corresponds to a dissipative interaction with a purely thermal bath. Here we present the Kraus representation of this map, which we call the squeezed generalized amplitude damping channel. As an application of this channel to quantum information, we study the classical capacity of this channel.Comment: Accepted for publication in Physical Review A; note on methods of generating bath squeezing added in Section II A; 12 pages, 7 figure

Catalytic epoxidation of cyclic vinylsilanes by ruthenium(II) complexes under aerobic conditions

A new methodology has been developed for the catalytic epoxidation of cyclic vinylsilanes using a ruthenium(II) bisoxazoline complex 2 with molecular oxygen. An attempt has been made to understand the role of -SiMe3 group on the rate of epoxidation process. © 2003 Elsevier Ltd. All rights reserved

Bilarge neutrino mixing from supersymmetry with high-scale nonrenormalizable interactions

We suggest a supersymmetric (SUSY) explanation of neutrino masses and mixing, where nonrenormalizable interactions in the hidden sector generate lepton number violating Majorana mass terms for both right-chiral sneutrinos and neutrinos. It is found necessary to start with a superpotential including an array of gauge singlet chiral superfields. This leads to nondiagonal $\Delta L = 2$ mass terms and almost diagonal SUSY breaking $A$-terms. As a result, the observed pattern of bilarge mixing can be naturally explained by the simultaneous existence of the seesaw mechanism and radiatively induced masses. Allowed ranges of parameters in the gauge singlet sector are delineated, corresponding to each of the cases of normal hierarchy, inverted hierarchy and degenerate neutrinos.Comment: 19 pages, 5 figures. Minor modifications are made in the title and the text, some new references are added. To appear in this form in Physical Review

RP-HPLC METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS QUANTITATIVE ESTIMATION OF MEBEVERINE HYDROCHLORIDE AND CHLORDIAZEPOXIDE IN CAPSULES

Objective: To develop an accurate, precise and linear Reverse Phase High Performance Liquid Chromatographic (RP-HPLC) method for simultaneous quantitative estimation of Mebeverine hydrochloride and Chlordiazepoxide in MEVA C capsules and validate as per ICH guidelines.Methods: The optimized method uses a reverse phase column, Enable Make C18G (250 X 4.6 mm; 5μ), a mobile phase of triethylammonium phosphate buffer (pH 2.5): acetonitrile in the proportion of 60:40 v/v, flow rate of 1.0 ml/min and a detection wavelength of 240 nm using a UV detector.Results: The developed method resulted in Mebeverine eluting at 5.8 min and Chlordiazepoxide at 3.9 min. Mebeverine exhibited linearity in the range 250-750μg/ml, while Chlordiazepoxide exhibited linearity in the range 9.25-27.75μg/ml. The precision is exemplified by relative standard deviations of 1.45% for Mebeverine and 1.58% for Chlordiazepoxide. Percentage Mean recoveries were found to be in the range of 98â€102, during accuracy studies. The limit of detection (LOD) for Mebeverine hydrochloride and Chlordiazepoxide were found to be 91.67µg/ml and 2.23µg/ml respectively, while limit of quantitation (LOQ) for Mebeverine hydrochloride and Chlordiazepoxide were found to be 277.81µg/ml and 6.77µg/ml respectively.Conclusion: A simple, accurate, precise, linear and rapid RP-HPLC method was developed for simultaneous quantitative estimation of Mebeverine hydrochloride and Chlordiazepoxide in MEVA C capsules and validated as per ICH guidelines. Hence it can be used for the routine analysis of Mebeverine and Chlordiazepoxide in capusles in various pharmaceutical industries.Â

Complementarity in generic open quantum systems

We develop a unified, information theoretic interpretation of the number-phase complementarity that is applicable both to finite-dimensional (atomic) and infinite-dimensional (oscillator) systems, with number treated as a discrete Hermitian observable and phase as a continuous positive operator valued measure (POVM). The relevant uncertainty principle is obtained as a lower bound on {\it entropy excess}, $X$, the difference between the entropy of one variable, typically the number, and the knowledge of its complementary variable, typically the phase, where knowledge of a variable is defined as its relative entropy with respect to the uniform distribution. In the case of finite dimensional systems, a weighting of phase knowledge by a factor $\mu$ ($> 1$) is necessary in order to make the bound tight, essentially on account of the POVM nature of phase as defined here. Numerical and analytical evidence suggests that $\mu$ tends to 1 as system dimension becomes infinite. We study the effect of non-dissipative and dissipative noise on these complementary variables for oscillator as well as atomic systems.Comment: 18 pages, 15 figures; accepted for publication in Modern Physics Letters

4-(3-Eth­oxy-4-hydroxy­styr­yl)-1-methyl­pyridinium tosyl­ate monohydrate

In the title compound, C16H18NO2 +·C7H7O3S−·H2O, the dihedral angle between the pyridyl and benzene rings of the pyridinium cation is 0.2 (1)°. The benzene ring of the tosyl­ate anion makes a dihedral angle of 4.8 (2)° with the best mean plane of the pyridinium cation. The pyridinium cation and the tosyl­ate anion are hydrogen bonded to the water mol­ecule, and the crystal packing is further stabilized by inter­molecular C—H⋯O and π–π inter­actions [centroid–centroid separations of 3.648 (3) and 3.594 (2) Å