1,190 research outputs found

    Supersolid in a one-dimensional model of hard-core bosons

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    We study a system of hardcore boson on a one-dimensional lattice with frustrated next-nearest neighbor hopping and nearest neighbor interaction. At half filling, for equal magnitude of nearest and next-nearest neighbor hopping, the ground state of this system exhibits a first order phase transition from a Bond-Ordered (BO) solid to a Charge-Density-Wave(CDW) solid as a function of the nearest neighbor interaction. Moving away from half filling we investigate the system at incommensurate densities, where we find a SuperSolid (SS) phase which has concurrent off-diagonal long range order and density wave order which is unusual in a system of hardcore bosons in one dimension. Using the finite-size Density-Matrix Renormalization Group (DMRG) method, we obtain the complete phase diagram for this model

    Vasodilator and antihypertensive effects of l-serine

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    L-serine, a non-essential amino acid, plays a role in the biosynthesis of the amino acids, proteins, purine and pyrimidine nucleotides. It is important for the proper functioning of the nervous system. It has been considered in the treatment of patients with schizophrenia, depression, chronic fatigue syndrome and psychomotor retardation, and of the seizures encountered in patients with rare inborn errors of L-serine biosynthesis. However, there are no reports in the literature of the direct cardiovascular effects of L-serine. Using normotensive Sprague-Dawley rats, Sprague-Dawley rats rendered hypertensive by chronic treatment with the nitric oxide (NO) synthase inhibitior NG nitro L-arginine methyl ester (L-NAME) and spontaneously hypertensive rats (SHR), the present study examined the in vitro and in vivo effects of L-serine. In vitro studies focused on L-serine induced changes in phenylephrine constricted third order branches of rat mesenteric arterioles while the in vivo studies examined the effects of intravenous infusion of L-serine on mean arterial pressure (MAP) and heart rate (HR) in intact anaesthetized rats. L-serine (10 to 200 µmol/L) evoked concentration-dependent vasodilatation in phenylephrine constricted endothelium-intact, but not in endothelium-denuded, rat mesenteric arterioles. The vasodilator responses to L-serine were absent in the combined presence of apamin, a calcium activated small conductance potassium (SKCa) channel inhibitor, and TRAM-34, a calcium activated intermediate conductance potassium (IKCa) channel inhibitor, or ouabain, a sodium pump inhibitor and barium (Ba2+), an inward rectifying potassium (Kir) channel inhibitor, or when the vessels were depolarized by potassium chloride. The maximal vasodilatation response (Emax) to L-serine was higher in vessels from L-NAME treated rats (40%) than from control rats (20%). In anesthetized rats, L-serine evoked a rapid, reversible, dose-dependent fall in MAP (without a significant change in HR), which was more pronounced in L-NAME treated rats (> 60 mmHg) than in normotensive control rats (25 mmHg). The fall in MAP was inhibited (

    Phases and phase transitions of frustrated hard-core bosons on a triangular ladder

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    We study hardcore bosons on a triangular ladder at half filling in the presence of a frustrating hopping term and a competing nearest neighbor repulsion VV which promotes crystallization. Using the finite-size density-matrix renormalization group method, we obtain the phase diagram which contains three phases: a uniform superfluid (SF), an insulating charge density wave (CDW) crystal and a bond ordered insulator (BO). We find that the transitions from SF to CDW and SF to BO are continuous in nature, with critical exponents varying continously along the phase boundaries, while the transition from CDW to BO is found to be first order. The phase diagram is also shown to contain an exactly solvable Majumdar Ghosh point, and re-entrant SF to CDW phase transitions.Comment: 10 pages, 16 figure

    Quantum Phases of Ultracold Bosonic Atoms in a One Dimensional Optical Superlattice

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    We analyze various quantum phases of ultracold bosonic atoms in a periodic one dimensional optical superlattice. Our studies have been performed using the finite size density matrix renormalization group (FS-DMRG) method in the framework of the Bose-Hubbard model. Calculations have been carried out for a wide range of densities and the energy shifts due to the superlattice potential. At commensurate fillings, we find the Mott insulator and the superfluid phases as well as Mott insulators induced by the superlattice. At a particular incommensurate density, the system is found to be in the superfluid phase coexisting with density oscillations for a certain range of parameters of the system.Comment: 7 pages, 11 figure

    COVID-19 and India: What Next?

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    The study carries out predictive modeling based on publicly available COVID-19 data for the duration 01 April to 20 June 2020 pertaining to India and five of its most infected states: Maharashtra, Tamil Nadu, Delhi, Gujarat, and Rajasthan using susceptible, infected, recovered, and dead (SIRD) model. The basic reproduction number R0 is derived by exponential growth method using RStudio package R0. The differential equations reflecting SIRD model have been solved using Python 3.7.4 on Jupyter Notebook platform. For visualization, Python Matplotlib 3.2.1 package is used. The study offers insights on peak-date, peak number of COVID-19 infections, and end-date pertaining to India and five of its states. The results could be leveraged by political leadership, health authorities, and industry doyens for policy planning and execution.Comment: 20 pages, 3 figures, 3 table

    PURIFICATION AND CHARACTERIZATION OF a-GLUCOSIDASE FROM MOSS HYOPHILLA NYMANIANA (FLEISH.) MENZEL

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    Objective: The present study was undertaken to extract and purify α-glucosidase N-linked glycosylation enzyme from moss Hyophilla nymaniana(Fleish.) Menzel.Methods: Frozen protonemal cells were taken for crude enzyme extraction, and the enzyme α-glucosidase was purified from the prepared crudeenzyme extract by ammonium sulfate (NH4) 2SO4 precipitation, gel filtration and finally on diethylaminoethyl sephadex column chromatography.Results: The final purification step of the enzyme resulted in 35 fold purification with a recovery of 4%. A single protein band of 72±5 kilodalton wasseen on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The physiochemical characterization of the enzyme reveled the enzyme hada wide pH stability range 4-7 with optimum pH 5 while the temperature stability study revealed the enzyme was stable up to 60°C while the optimumtemperature of the purified enzyme was 45°C. The enzyme was strongly inhibited by Hg2+ and Ag2+ at 1 mM concentration while Mg ionsenhanced the enzyme activity at the same concentration. The kinetic study of the enzyme showed Km and V of the enzyme 5.2 mM/ml and 8.6 U/ml,respectively.Conclusion: The wide pH and temperature stability range show its suitability toward industrial application.maxKeywords: α-glucosidase, Hyophilla nymaniana (Fleish.) Menzel. gel filtration, Diethylaminoethyl sephadex column chromatography

    Task irrelevant external cues can influence language selection in voluntary object naming: evidence from Hindi-English bilinguals

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    We examined if external cues such as other agents’ actions can influence the choice of language during voluntary and cued object naming in bilinguals in three experiments. Hindi– English bilinguals first saw a cartoon waving at a color patch. They were then asked to either name a picture in the language of their choice (voluntary block) or to name in the instructed language (cued block). The colors waved at by the cartoon were also the colors used as language cues (Hindi or English). We compared the influence of the cartoon’s choice of color on naming when speakers had to indicate their choice explicitly before naming (Experiment 1) as opposed to when they named directly on seeing the pictures (Experiment 2 and 3). Results showed that participants chose the language indicated by the cartoon greater number of times (Experiment 1 and 3). Speakers also switched significantly to the language primed by the cartoon greater number of times (Experiment 1 and 2). These results suggest that choices leading to voluntary action, as in the case of object naming can be influenced significantly by external non-linguistic cues. Importantly, these symbolic influences can work even when other agents are merely indicating their choices and are not interlocutors in bilingual communicatio

    Research Excellence of IITs in Business, Management and Accounting: A bibliometric study

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    The present study assesses business research in Indian Institute of Technologies (IITs). The publications of IITs in business, Management and Accounting recorded in Scopus database dates back to 1963. The study analyzed top performing nine IITs and found 5000 publications during 1963 to 2019. Bibliometric analysis is implemented on data retrieved from Scopus database. The study identifies annual growth, prolific authors, authorship trend, leading journals and Bradford’s Law is tested on the collected data of Scattering in different source

    Hardcore bosons in a zig-zag optical superlattice

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    We study a system of hard-core bosons at half-filling in a one-dimensional optical superlattice. The bosons are allowed to hop to nearest and next-nearest neighbor sites producing a zig-zag geometry and we obtain the ground state phase diagram as a function of microscopic parameters using the finite-size density matrix renormalization group (FS-DMRG) method. Depending on the sign of the next-nearest neighbor hopping and the strength of the superlattice potential the system exhibits three different phases, namely the bond-order (BO) solid, the superlattice induced Mott insulator (SLMI) and the superfluid (SF) phase. When the signs of both hopping amplitudes are the same (the "unfrustrated" case), the system undergoes a transition from the SF to the SLMI at a non-zero value of the superlattice potential. On the other hand, when the two amplitudes differ in sign (the "frustrated" case), the SF is unstable to switching on a superlattice potential and also exists only up to a finite value of the next nearest neighbor hopping. This part of the phase diagram is dominated by the BO phase which breaks translation symmetry spontaneously even in the absence of the superlattice potential and can thus be characterized by a bond order parameter. The transition from BO to SLMI appears to be first order.Comment: 6 pages, 11 figure
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