179 research outputs found
Periodic force induced stabilization or destabilization of the denatured state of a protein
We have studied the effects of an external sinusoidal force in protein
folding kinetics. The externally applied force field acts on the each amino
acid residues of polypeptide chains. Our simulation results show that mean
protein folding time first increases with driving frequency and then decreases
passing through a maximum. With further increase of the driving frequency the
mean folding time starts increasing as the noise-induced hoping event (from the
denatured state to the native state) begins to experience many oscillations
over the mean barrier crossing time period. Thus unlike one-dimensional barrier
crossing problems, the external oscillating force field induces both
\emph{stabilization or destabilization of the denatured state} of a protein. We
have also studied the parametric dependence of the folding dynamics on
temperature, viscosity, non-Markovian character of bath in presence of the
external field
Staphylococcus aureus septicemia presenting as disseminated intravascular coagulation - thrombotic thrombocytopenic purpura overlap and thrombus in inferior vena cava, right atrium and right ventricle: a case report
Staphylococcal sepsis following furunculosis and complicated by suspected deep vein thrombosis and septic inferior vena caval, right atrium, right ventricle emboli accompanied by disseminated intravascular coagulation (DIC) - thrombotic thrombocytopenic overlap in a 65 years old lady is presented. She was managed successfully with antibiotics and anticoagulation. The case is reported for its rarity and brings to light the vivid manifestations of septicemia specially staphylococcal
Effect of Arsenic in germination, growth and biochemistry of Rice (Oryza sativa)
Arsenic is a highly toxic metalloid element and occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. Arsenic poisoning from naturally occurring arsenic compounds in drinking water remains a problem in many parts of the world. Arsenic contaminated water is also used in the agricultural field for irrigation purpose. The influence of 0, 1, 2 and 4mg/l sodium arsenite on germination, seedling growth and biochemistry of two varieties of Rice (Oryza sativa), Nayanmani and Satabdi was studied under controlled conditions. After 3 weeks the various parameters (percentage of seed germination, root and shoot length, dry biomass, chlorophyll, peroxidase, protein and ascorbic acid content) were estimated following standard procedures. It was observed that the root and shoot length, germination percentage, dry biomass, protein content, chlorophyll, ascorbic acid content and peroxidase activity decreased significantly with increasing exposure to arsenic in both the plant varieties. The study shows that arsenic is toxic to both rice varieties and affects adversely the normal rate of germination and growth through alteration in the plant biochemistry
Quantum oscillator on complex projective space (Lobachewski space) in constant magnetic field and the issue of generic boundary conditions
We perform a 1-parameter family of self-adjoint extensions characterized by
the parameter . This allows us to get generic boundary conditions for
the quantum oscillator on dimensional complex projective
space() and on its non-compact version i.e., Lobachewski
space() in presence of constant magnetic field. As a result, we
get a family of energy spectrums for the oscillator. In our formulation the
already known result of this oscillator is also belong to the family. We have
also obtained energy spectrum which preserve all the symmetry (full hidden
symmetry and rotational symmetry) of the oscillator. The method of self-adjoint
extensions have been discussed for conic oscillator in presence of constant
magnetic field also.Comment: Accepted in Journal of Physics
Self-Adjointness of Generalized MIC-Kepler System
We have studied the self-adjointness of generalized MIC-Kepler Hamiltonian,
obtained from the formally self-adjoint generalized MIC-Kepler Hamiltonian. We
have shown that for \tilde l=0, the system admits a 1-parameter family of
self-adjoint extensions and for \tilde l \neq 0 but \tilde l <{1/2}, it has
also a 1-parameter family of self-adjoint extensions.Comment: 11 pages, Latex, no figur
Kinetics of self-induced aggregation of Brownian particles: non-Markovian and non-Gaussian features
In this paper we have studied a model for self-induced aggregation in
Brownian particle incorporating the non-Markovian and non-Gaussian character of
the associated random noise process. In this model the time evolution of each
individual is guided by an over-damped Langevin equation of motion with a
non-local drift resulting from the local unbalance distributions of the other
individuals. Our simulation result shows that colored nose can induce the
cluster formation even at large noise strength. Another observation is that
critical noise strength grows very rapidly with increase of noise correlation
time for Gaussian noise than non Gaussian one. However, at long time limit the
cluster number in aggregation process decreases with time following a power
law. The exponent in the power law increases remarkable for switching from
Markovian to non Markovian noise process
Stochastic Energetics of Quantum Transport
We examine the stochastic energetics of directed quantum transport due to
rectification of non-equilibrium thermal fluctuations. We calculate the quantum
efficiency of a ratchet device both in presence and absence of an external load
to characterize two quantifiers of efficiency. It has been shown that the
quantum current as well as efficiency in absence of load (Stokes efficiency) is
higher as compared to classical current and efficiency, respectively, at low
temperature. The conventional efficiency of the device in presence of load on
the other hand is higher for a classical system in contrast to its classical
counterpart. The maximum conventional efficiency being independent of the
nature of the bath and the potential remains the same for classical and quantum
systems.Comment: To be published in Phys. Rev.
Lower bound of minimal time evolution in quantum mechanics
We show that the total time of evolution from the initial quantum state to
final quantum state and then back to the initial state, i.e., making a round
trip along the great circle over S^2, must have a lower bound in quantum
mechanics, if the difference between two eigenstates of the 2\times 2
Hamiltonian is kept fixed. Even the non-hermitian quantum mechanics can not
reduce it to arbitrarily small value. In fact, we show that whether one uses a
hermitian Hamiltonian or a non-hermitian, the required minimal total time of
evolution is same. It is argued that in hermitian quantum mechanics the
condition for minimal time evolution can be understood as a constraint coming
from the orthogonality of the polarization vector \bf P of the evolving quantum
state \rho={1/2}(\bf 1+ \bf{P}\cdot\boldsymbol{\sigma}) with the vector
\boldsymbol{\mathcal O}(\Theta) of the 2\times 2 hermitian Hamiltonians H
={1/2}({\mathcal O}_0\boldsymbol{1}+ \boldsymbol{\mathcal
O}(\Theta)\cdot\boldsymbol{\sigma}) and it is shown that the Hamiltonian H can
be parameterized by two independent parameters {\mathcal O}_0 and \Theta.Comment: 4 pages, no figure, revtex
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