1,768 research outputs found
On the use of non-canonical quantum statistics
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
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
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
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
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
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
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Self-assembly, nematic phase formation and organocatalytic behaviour of a proline-functionalized lipopeptide
The self-assembly of the amphiphilic lipopeptide PAEPKI-C16 (P = proline, A = alanine, E = glutamic acid, K = lysine, I = isoleucine, C16 = hexadecyl) was investigated using a combination of spectroscopic, microscopic and scattering methods and compared to C16-IKPEAP with the same (reversed) peptide sequence and the alkyl chain positioned N-terminally and which lacks a free N-terminal proline residue. The catalytic activity of these peptides were then compared using a model aldol reaction system. For PAEPKI-C16, Cryo-TEM images showed the formation of micrometer length fibers, which by Small-angle X-ray scattering (SAXS) were found to have a radius of 2.5 - 2.6 nm. Spectroscopic analysis shows these fibers are built from -sheets. This behaviour is in complete contrast to that of C16-IKPEAP which forms spherical micelles with peptides in a disordered conformation [Hutchinson, J. A. et al. J. Phys. Chem. B 2019, 123, 613]. For PAEPKI-C16, the spontaneous alignment of fibers was observed upon increasing pH, which was accompanied by observed birefringence and anisotropy of SAXS patterns. This shows the formation of a nematic liquids and unprecedented nematic hydrogel formation was also observed these lipopeptides at sufficiently high concentrations. SAXS shows retention of an ultrafine (1.7 nm core radius) fibrillar network within the hydrogel. PAEPKI-C16 with free N-terminal proline shows enhanced anti:syn diastereoselectivity and better conversion compared to C16-IKPEAP. The cytotoxicity of PAEPKI-C16 was also lower than C16-IKPEAP for both fibroblast and cancer cell lines. These results highlight the sensitivity of lipopeptide properties to the presence of a free proline residue. The spontaneous nematic phase formation by PAEPKI-C16 points to the highly anisotropy of its ultrafine fibrillar structure and the formation of such a phase at low concentration in aqueous solution may be valuable for future applications
Maternal and perinatal outcome in severe pre-eclampsia and eclampsia: a study of 120 cases at a tertiary health care center in Western India
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
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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