187 research outputs found
The effective temperature
This review presents the effective temperature notion as defined from the
deviations from the equilibrium fluctuation-dissipation theorem in out of
equilibrium systems with slow dynamics. The thermodynamic meaning of this
quantity is discussed in detail. Analytic, numeric and experimental
measurements are surveyed. Open issues are mentioned.Comment: 58 page
Isolation and characterization of an insertion element-like repetitive sequence specific for Mycobacterium tuberculosis complex
We report the characterization of an insertion-like
repetitive sequence containing the clone of Mycobacterium
tuberculosis. This repetitive sequence contains
seven inverted repeats. Restriction fragment length
polymorphism studies using this probe have shown
that it is not a highly polymorphic probe but rather
shows conservative fingerprint pattern. Out of the 150
strains tested, only three showed different fingerprint
patterns. It has several direct and inverted repeats.
Homology studies of the putative protein coding region
show that this repeat element might code for a
metalloproteinase of M. tuberculosis. Homology studies
also implicate this repeat element to be from a very
essential region of the M. tuberculosis genome participating
in recombination. This repeat has been found
to be an ideal target for polymerase chain reaction to
detect M. tuberculosis
Development of DNA probes for M. tuberculosis
Attempts were made to develop DNA
probes for M. tuberculosis. Random library of M.
tuberculosis was constructed in plasmid pGEM -4.
Selection of recombinant clones was made by hybridisation
with 32P labelled M. tuberculosis probe.
Ten recombinant clones were selected on the basis
of strong signals from the random library.
These 10 clones named pTRC1-10 were subjected to
tests for specificity and sensitivity. On this basis,
pTRC4 was chosen and this is also, useful in restriction
fragment length polymorphism (RFLP)
studies
Restriction fragment length polymorphism of Mycobacterium tuberculosis strains from various regions of India, using direct repeat probe
Intraspecies differentiation was studied on 68 M. tuberculosis strains obtained from 6 states of India by
restriction fragment length polymorphism (RFLP) using a direct repeat probe (DR probe) hybridised
with Alu I digest of DNA. Most strains showed polymorphism based patterns that comprised between 2
to 7 bands and were grouped into 26 RFLP types. Of the 11 strains tested from Amritsar, 8 were RFLP
type 5; the remaining 3 were of type 11 and were exclusively confined to this region. The strains from
other regions were more heterogeneous. We confirm that DR-associated RFLP can be an excellent tool
for the differentiation of M. tuberculosis strains. Depending on their geographical origin, these strains can
be differentiated to a large extent by DR fingerprinting
Using the Hadamard and related transforms for simplifying the spectrum of the quantum baker's map
We rationalize the somewhat surprising efficacy of the Hadamard transform in
simplifying the eigenstates of the quantum baker's map, a paradigmatic model of
quantum chaos. This allows us to construct closely related, but new, transforms
that do significantly better, thus nearly solving for many states of the
quantum baker's map. These new transforms, which combine the standard Fourier
and Hadamard transforms in an interesting manner, are constructed from
eigenvectors of the shift permutation operator that are also simultaneous
eigenvectors of bit-flip (parity) and possess bit-reversal (time-reversal)
symmetry.Comment: Version to appear in J. Phys. A. Added discussions; modified title;
corrected minor error
Symmetrically coupled higher-order nonlinear Schroedinger equations: singularity analysis and integrability
The integrability of a system of two symmetrically coupled higher-order
nonlinear Schr\"{o}dinger equations with parameter coefficients is tested by
means of the singularity analysis. It is proven that the system passes the
Painlev\'{e} test for integrability only in ten distinct cases, of which two
are new. For one of the new cases, a Lax pair and a multi-field generalization
are obtained; for the other one, the equations of the system are uncoupled by a
nonlinear transformation.Comment: 12 pages, LaTeX2e, IOP style, final version, to appear in
J.Phys.A:Math.Ge
Formulation and Evaluation of Cephalexin Extended-release Matrix Tablets Using Hydroxy Propyl Methyl Cellulose as Rate-controlling Polymer
The present investigation reports the design and evaluation of six-hour extended release film-coated matrix tablets of cephalexin using different grades of hydrophilic polymer hydroxypropylmethylcellulose (HPMC) employing direct compression method. The preformulation studies performed included the physical compatibility studies, Differential Scanning Calorimetry analysis, drug characterization using Fourier Transform Infra Red spectroscopic analysis and particle size analysis using sieve method. The tablets were evaluated for weight variation, hardness, thickness and friability. Results of the studies indicate that the polymers used have significant release-retarding effect on the formulation. The dissolution profile comparison of the prepared batches P1 to P8 and market preparation (Sporidex AF 375) was done by using Food and Drug Administration-recommended similarity factor (f2) determination. The formulation P8 (10% HPMC K4M, 15% HPMC 15cps) with a similarity factor (f2) of 77.75 was selected as the optimized formulae for scale-up batches. The dissolution data of the best formulation P8 was fitted into zero order, first order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. The results of the accelerated stability study of best formulation P8 for three months revealed that storage conditions were not found to have made any significant changes in final formulation F3. The release of cephalexin was prolonged for 6 h by using polymer combinations of HPMC and a twice daily matrix tablet was formulated
Nonholonomic deformation of KdV and mKdV equations and their symmetries, hierarchies and integrability
Recent concept of integrable nonholonomic deformation found for the KdV
equation is extended to the mKdV equation and generalized to the AKNS system.
For the deformed mKdV equation we find a matrix Lax pair, a novel two-fold
integrable hierarchy and exact N-soliton solutions exhibiting unusual
accelerating motion. We show that both the deformed KdV and mKdV systems
possess infinitely many generalized symmetries, conserved quantities and a
recursion operator.Comment: Latex, 2 figures, 16 pages. Revised with more explanations after
Referees' feedback.To be published in J. Phys.
Matter-Wave Solitons in an F=1 Spinor Bose-Einstein Condensate
Following our previous work [J. Ieda, T. Miyakawa, M. Wadati,
cond-mat/0404569] on a novel integrable model describing soliton dynamics of an
F=1 spinor Bose--Einstein condensate, we discuss in detail the properties of
the multi-component system with spin-exchange interactions. The exact multiple
bright soliton solutions are obtained for the system where the mean-field
interaction is attractive (c_0 < 0) and the spin-exchange interaction is
ferromagnetic (c_2 < 0). A complete classification of the one-soliton solution
with respect to the spin states and an explicit formula of the two-soliton
solution are presented. For solitons in polar state, there exists a variety of
different shaped solutions including twin peaks. We show that a "singlet pair"
density can be used to distinguish those energetically degenerate solitons. We
also analyze collisional effects between solitons in the same or different spin
state(s) by computing the asymptotic forms of their initial and final states.
The result reveals that it is possible to manipulate the spin dynamics by
controlling the parameters of colliding solitons.Comment: 12 pages, 9 figures, to appear in J. Phys. Soc. Jpn. Vol.73 No.11
(2004
Continuous Symmetries of Difference Equations
Lie group theory was originally created more than 100 years ago as a tool for
solving ordinary and partial differential equations. In this article we review
the results of a much more recent program: the use of Lie groups to study
difference equations. We show that the mismatch between continuous symmetries
and discrete equations can be resolved in at least two manners. One is to use
generalized symmetries acting on solutions of difference equations, but leaving
the lattice invariant. The other is to restrict to point symmetries, but to
allow them to also transform the lattice.Comment: Review articl
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