1,768 research outputs found

    On the use of non-canonical quantum statistics

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    We develop a method using a coarse graining of the energy fluctuations of an equilibrium quantum system which produces simple parameterizations for the behaviour of the system. As an application, we use these methods to gain more understanding on the standard Boltzmann-Gibbs statistics and on the recently developed Tsallis statistics. We conclude on a discussion of the role of entropy and the maximum entropy principle in thermodynamics.Comment: 29 pages, uses iopart.cls, major revisions of text for better readability, added a discussion about essentially microcanonical ensemble

    Dynamical quantum phase transition of a two-component Bose-Einstein condensate in an optical lattice

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    We study dynamics of a two-component Bose-Einstein condensate where the two components are coupled via an optical lattice. In particular, we focus on the dynamics as one drives the system through a critical point of a first order phase transition characterized by a jump in the internal populations. Solving the time-dependent Gross-Pitaevskii equation, we analyze; breakdown of adiabaticity, impact of non-linear atom-atom scattering, and the role of a harmonic trapping potential. Our findings demonstrate that the phase transition is resilient to both contact interaction between atoms and external trapping confinement.Comment: 8 pages, 8 figure

    Electron-Beam Manipulation of Silicon Dopants in Graphene

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    The direct manipulation of individual atoms in materials using scanning probe microscopy has been a seminal achievement of nanotechnology. Recent advances in imaging resolution and sample stability have made scanning transmission electron microscopy a promising alternative for single-atom manipulation of covalently bound materials. Pioneering experiments using an atomically focused electron beam have demonstrated the directed movement of silicon atoms over a handful of sites within the graphene lattice. Here, we achieve a much greater degree of control, allowing us to precisely move silicon impurities along an extended path, circulating a single hexagon, or back and forth between the two graphene sublattices. Even with manual operation, our manipulation rate is already comparable to the state-of-the-art in any atomically precise technique. We further explore the influence of electron energy on the manipulation rate, supported by improved theoretical modeling taking into account the vibrations of atoms near the impurities, and implement feedback to detect manipulation events in real time. In addition to atomic-level engineering of its structure and properties, graphene also provides an excellent platform for refining the accuracy of quantitative models and for the development of automated manipulation.Comment: 5 figures, 4 supporting figure

    Spin-orbit coupled Bose-Einstein condensate in a tilted optical lattice

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    Bloch oscillations appear for a particle in a weakly tilted periodic potential. The intrinsic spin Hall effect is an outcome of a spin-orbit coupling. We demonstrate that both these phenomena can be realized simultaneously in a gas of weakly interacting ultracold atoms exposed to a tilted optical lattice and to a set of spatially dependent light fields inducing an effective spin-orbit coupling. It is found that both the spin Hall as well as the Bloch oscillation effects may coexist, showing, however, a strong correlation between the two. These correlations are manifested as a transverse spin current oscillating in-phase with the Bloch oscillations.Comment: 12 pages, 7 figure

    Trends of kidney cancer burden from 1990 to 2019 in European Union 15+ countries and World Health Organization regions

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    In recent decades, variability in the incidence and mortality of kidney cancer (KC) has been reported. This study aimed to compare trends in incidence, mortality, and disability-adjusted life years (DALY) of KC between the European Union (EU) 15 + countries and 6 World Health Organization (WHO) regions. The data of KC Age-standardized incidence rates (ASIRs), age-standardized mortality rates (ASMRs), and age-standardized DALYs were extracted from the Global Burden of Disease database. Joinpoint regression was employed to examine trends. From 1990 to 2019, the ASIR increased in most countries except for Luxembourg (males), the USA (females) and Austria and Sweden (both sexes). ASIR increased across all 6 WHO regions for both sexes except for females in Americas. The ASMR increased in 10/19 countries for males and 9/19 for females as well across most WHO regions. The mortality-to-incidence ratio (MIR) decreased in all countries and WHO regions. Trends in DALYs were variable across countries and WHO regions. While the incidence and mortality from KC rose in most EU15 + countries and WHO regions from 1990 to 2019, the universal drop in MIR suggests an overall improvement in KC outcomes. This is likely multifactorial, including earlier detection of KC and improved treatments

    Micro evolution of bitter taste domain drugs

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    Ayurveda classified the drugs in various ways and one of which the classification is based on Rasa (taste) dominancy. Rasa is essential to identify drugs and to know its therapeutic application. In this study the drug has been selected according to Charaka classification of Tikta Rasa (bitter taste) drugs with an aim to find out the similar characters among all the drugs having bitter Rasa dominancy. Till date there is no data available regarding the pharmacognostical evaluation in concern bitter taste. For the first time selected five bitter drugs are subjected to various pharmacognostical evaluation, result reveals that Organoleptic characters of all five drugs give bitter taste, microscopic evaluation revealed that presence of starch grain, vessels, fiber , brown content are dominant in all five raw drug and all the five powder subjected to alkaloid test by using dragondroff reagent and give positive result for alkaloid

    Maternal and perinatal outcome in severe pre-eclampsia and eclampsia: a study of 120 cases at a tertiary health care center in Western India

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    Background: Hypertensive disorders of pregnancy are a leading cause of maternal and perinatal mortality and morbidity worldwide. Pre-eclampsia accounts for the majority of referrals in a tertiary care center as it stands one of the major causes of maternal and perinatal morbidity and mortality. It complicates 6-10% of all pregnancies. In India, they account for the third most important cause of maternal mortality. Patients with PIH are at a greater risk of abruptio placenta, cerebrovascular events, organ failure and DIC. Fetuses are at a greater risk of IUGR, preterm birth, small for gestational age and IUD. This study aimed to determine the maternal and perinatal outcomes of hospitalized pregnant cases with severe preeclampsia and eclampsia.Methods: This was a single year retrospective study conducted in a tertiary care center of Western India from May 2019 to May 2020. Maternal and perinatal outcomes were analyzed among the severe preeclampsia and eclampsia groups.Results: A total 52 (43.33%) of the cases were in the age group of 21-25 years, 64 (53.33%) were primigravidae and the majority were referred from peripheral hospitals. Liver function tests were deranged in 26.68% of the patients and 32.5% had abnormal renal function. Labetalol was the most commonly used antihypertensive and magnesium sulphate was the anticonvulsant used in all the cases. Lower segment caesarean section was the mode of delivery in 62 (51.67%) of the cases. Commonest maternal complication was atonic PPH (12.5%). There was one maternal mortality due to aspiration pneumonia. 85 (70.83%) of the babies needed NICU admission. There were 5 (4.16%) perinatal deaths.Conclusions: Accessible health care and health education and awareness regarding antenatal check-ups for all women will lead to early detection of severe preeclampsia. Prompt treatment and management of its complications will certainly improve the maternal and fetal outcome

    Derivation and Improvements of the Quantum Canonical Ensemble from a Regularized Microcanonical Ensemble

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    We develop a regularization of the quantum microcanonical ensemble, called a Gaussian ensemble, which can be used for derivation of the canonical ensemble from microcanonical principles. The derivation differs from the usual methods by giving an explanation for the, at the first sight unreasonable, effectiveness of the canonical ensemble when applied to certain small, isolated, systems. This method also allows a direct identification between the parameters of the microcanonical and the canonical ensemble and it yields simple indicators and rigorous bounds for the effectiveness of the approximation. Finally, we derive an asymptotic expansion of the microcanonical corrections to the canonical ensemble for those systems, which are near, but not quite, at the thermodynamical limit and show how and why the canonical ensemble can be applied also for systems with exponentially increasing density of states. The aim throughout the paper is to keep mathematical rigour intact while attempting to produce results both physically and practically interesting.Comment: 17 pages, latex2e with iopar
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