404 research outputs found
Mobility and stochastic resonance in spatially inhomogeneous system
The mobility of an overdamped particle, in a periodic potential tilted by a
constant external field and moving in a medium with periodic friction
coefficient is examined. When the potential and the friction coefficient have
the same periodicity but have a phase difference, the mobility shows many
interesting features as a function of the applied force, the temperature, etc.
The mobility shows stochastic resonance even for constant applied force, an
issue of much recent interest. The mobility also exhibits a resonance like
phenomenon as a function of the field strength and noise induced slowing down
of the particle in an appropriate parameter regime.Comment: 14 pages, 12 figures. Submitted to Phys. Rev.
Nanodot to Nanowire: A strain-driven shape transition in self-organized endotaxial CoSi2 on Si (100)
We report a phenomenon of strain-driven shape transition in the growth of
nanoscale self-organized endotaxial CoSi2 islands on Si (100) substrates. Small
square shaped islands as small as 15\times15 nm2 have been observed. Islands
grow in the square shape following the four fold symmetry of the Si (100)
substrate, up to a critical size of 67 \times 67 nm2. A shape transition takes
place at this critical size. Larger islands adopt a rectangular shape with ever
increasing length and the width decreasing to an asymptotic value of ~25 nm.
This produces long wires of nearly constant width.We have observed nanowire
islands with aspect ratios as large as ~ 20:1. The long nanowire
heterostructures grow partly above (~ 3 nm) the surface, but mostly into (~17
nm) the Si substrate. These self-organized nanostructures behave as nanoscale
Schottky diodes. They may be useful in Si-nanofabrication and find potential
application in constructing nano devices.Comment: 9 pages, 7 figure
Brownian rectifiers in the presence of temporally asymmetric unbiased forces
The efficiency of energy transduction in a temporally asymmetric rocked
ratchet is studied. Time asymmetry favours current in one direction and
suppresses it in the opposite direction due to which large efficiency ~ 50% is
readily obtained. The spatial asymmetry in the potential together with system
inhomogeneity may help in further enhancing the efficiency. Fine tuning of
system parameters considered leads to multiple current reversals even in the
adiabatic regime
A Mild and Efficient Method for the Syntheses and Regioselective Ring-Opening of Aziridines
We have developed a new synthetic method for the synthesis of aziridines using Chloramine-T as an effective reagent in the presence of NH2OH center dot HCl and NaIO4. We found that the same combination of NH2OH center dot HCl and NaIO4 is also very effective for nucleophilic ring opening of aziridines.This research was funded by the Russian Science Foundation, grant number 18-19-00090
de Sitter group and Einstein-Hilbert Lagrangian
Axial vector torsion in the Einstein-Cartan space is considered here.
By picking a particular term from the SO(4,1) Pontryagin density and then
modifying it in a SO(3,1) invariant way, we get a Lagrangian density with
Lagrange multipliers. Then considering torsion and torsion-less connection as
independent fields, it has been found that and of
Einstein-Hilbert Lagrangian, appear as integration constants in such a way that
has been found to be linked with the topological Nieh-Yan density of
space.Comment: 14 page
Phases of one dimensional large N gauge theory in a 1/D expansion
We consider large N Yang Mills theory with D adjoint scalar fields in d
dimensions for d=0 or 1. We show the existence of a non-trivial saddle point of
the functional integral at large D which is characterized by a mass gap for the
adjoint scalars. We integrate out the adjoint scalars in a 1/D expansion around
the saddle point. In case of one dimension which is regarded as a circle, this
procedure leads to an effective action for the Wilson line. We find an analogue
of the confinement/deconfinement transition which consists of a second order
phase transition from a uniform to a non-uniform eigenvalue distribution of the
Wilson line, closely followed by a Gross-Witten-Wadia transition where a gap
develops in the eigenvalue distribution. The phase transition can be regarded
as a continuation of a Gregory-Laflamme transition. Our methods involve large
values of the dimensionless 'tHooft coupling. The analysis in this paper is
quantitatively supported by earlier numerical work for D=9.Comment: 27 pages + 21 pages of Appendix; 8 figures, v2:some comments are
added in sec.4.3, minor corrections, one reference added, v3: minor
corrections, one reference added, version to be published in JHE
Derangement of liver function tests in dengue patients
Background: Changes in the liver function test may serve as an early marker for timely diagnosis and identification of patients who may develop severe dengue. The purpose of this study was to examine the link between dengue fever severity and liver function test.
Methods: This prospective observational study was conducted in the Department of General Medicine, Madhesh Institute of health sciences, provincial hospital, Janakpurdham in which we included dengue positive patients (aged 18 years or more) based on NS1 antigen or high titer on IgM/IgG testing from July 2023 till August 2023. We excluded patients with diseases like malaria, cirrhosis of liver, enteric fever, viral hepatitis or any other disease or taking any medication which can derange LFT.
Results: We included 96 patients fulfilling the study criteria. Of these, 71% had DF, 22% had DHF and 7% had DSS. Among liver enzymes, mean AST of the patients was significantly higher in DSS group of patients (775.19±39.65 U/l), as compared to those in the DF and DHF group of patients, p value <0.01. Similarly, mean ALT of the patients was significantly higher in DSS group of patients (387.8±18.6 U/l), as compared to those in the DF and DHF group of patients, p value<0.01. On the contrary, mean alkaline phosphatase levels were similar between the three patient groups.
Conclusions: Based on the results our study, we conclude that raised AST and ALT levels were significantly associated with severity of DSS and DHF. Patients with dengue infection should have a baseline liver function test and subsequent LFT monitoring to detect early hepatic impairment
Hydrodynamics of R-charged D1-branes
We study the hydrodynamic properties of strongly coupled Yang-Mills
theory of the D1-brane at finite temperature and at a non-zero density of
R-charge in the framework of gauge/gravity duality. The gravity dual
description involves a charged black hole solution of an
Einstein-Maxwell-dilaton system in 3 dimensions which is obtained by a
consistent truncation of the spinning D1-brane in 10 dimensions. We evaluate
thermal and electrical conductivity as well as the bulk viscosity as a function
of the chemical potential conjugate to the R-charges of the D1-brane. We show
that the ratio of bulk viscosity to entropy density is independent of the
chemical potential and is equal to . The thermal conductivity and bulk
viscosity obey a relationship similar to the Wiedemann-Franz law. We show that
at the boundary of thermodynamic stability, the charge diffusion mode becomes
unstable and the transport coefficients exhibit critical behaviour. Our method
for evaluating the transport coefficients relies on expressing the second order
differential equations in terms of a first order equation which dictates the
radial evolution of the transport coefficient. The radial evolution equations
can be solved exactly for the transport coefficients of our interest. We
observe that transport coefficients of the D1-brane theory are related to that
of the M2-brane by an overall proportionality constant which sets the
dimensions.Comment: 57 pages, 12 figure
A Mild and Efficient Method for the Syntheses and Regioselective Ring-Opening of Aziridines
We have developed a new synthetic method for the synthesis of aziridines using Chloramine-T as an effective reagent in the presence of NH 2OH·HCl and NaIO 4. We found that the same combination of NH 2OH·HCl and NaIO 4is also very effective for nucleophilic ring opening of aziridines. Copyright © 2017 Georg Thieme Verlag Stuttgart · New York
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