1,051 research outputs found
Codon Distributions in DNA
The codons, sixtyfour in number, are distributed over the coding parts of DNA
sequences. The distribution function is the plot of frequency-versus-rank of
the codons. These distributions are characterised by parameters that are almost
universal, i.e., gene independent. There is but a small part that depends on
the gene. We present the theory to calculate the universal (gene-independent)
part. The part that is gene-specific, however, has undetermined overlaps and
fluctuations.Comment: 31 pages, 5 figure
Equation of state for the MCFL phase and its implications for compact star models
Using the solutions of the gap equations of the magnetic-color-flavor-locked
(MCFL) phase of paired quark matter in a magnetic field, and taking into
consideration the separation between the longitudinal and transverse pressures
due to the field-induced breaking of the spatial rotational symmetry, the
equation of state (EoS) of the MCFL phase is self-consistently determined. This
result is then used to investigate the possibility of absolute stability, which
turns out to require a field-dependent bag constant to hold. That is, only if
the bag constant varies with the magnetic field, there exists a window in the
magnetic field vs. bag constant plane for absolute stability of strange matter.
Implications for stellar models of magnetized (self-bound) strange stars and
hybrid (MCFL core) stars are calculated and discussed.Comment: 11 pp. 11 figure
Immuno-virological and toxicity outcomes of HIV-infected patients after 48 months of ART in Phnom Penh, Cambodia
Mexico AIDS Conference 200
Application of Tikhonov Regularized Methods to Image Deblurring Problem
We consider the monotone inclusion problems in real Hilbert spaces. Proximal
splitting algorithms are very popular technique to solve it and generally
achieve weak convergence under mild assumptions. Researchers assume strong
conditions like strong convexity or strong monotonicity on the considered
operators to prove strong convergence of the algorithms. Mann iteration method
and normal S-iteration method are popular methods to solve fixed point
problems. We propose a new common fixed point algorithm based on normal
S-iteration method {using Tikhonov regularization }to find common fixed point
of nonexpansive operators and prove strong convergence of the generated
sequence to the set of common fixed points without assuming strong convexity
and strong monotonicity. Based on the proposed fixed point algorithm, we
propose a forward-backward-type algorithm and a Douglas-Rachford algorithm in
connection with Tikhonov regularization to find the solution of monotone
inclusion problems. Further, we consider the complexly structured monotone
inclusion problems which are very popular these days. We also propose a
strongly convergent forward-backward-type primal-dual algorithm and a
Douglas-Rachford-type primal-dual algorithm to solve the monotone inclusion
problems. Finally, we conduct a numerical experiment to solve image deblurring
problems
Shear-free radiating collapse and conformal flatness
Here we study some general properties of spherical shear-free collapse. Its
general solution when imposing conformal flatness is reobtained [1,2] and
matched to the outgoing Vaidya spacetime. We propose a simple model satisfying
these conditions and study its physical consequences. Special attention
deserve, the role played by relaxational processes and the conspicuous link
betweeen dissipation and density inhomogeneity.Comment: 13 pages Latex. Some misprints in eqs.(17), (30) and (35) have been
correcte
Condensation of Excitons in Cu2O at Ultracold Temperatures: Experiment and Theory
We present experiments on the luminescence of excitons confined in a
potential trap at milli-Kelvin bath temperatures under cw-excitation. They
reveal several distinct features like a kink in the dependence of the total
integrated luminescence intensity on excitation laser power and a bimodal
distribution of the spatially resolved luminescence. Furthermore, we discuss
the present state of the theoretical description of Bose-Einstein condensation
of excitons with respect to signatures of a condensate in the luminescence. The
comparison of the experimental data with theoretical results with respect to
the spatially resolved as well as the integrated luminescence intensity shows
the necessity of taking into account a Bose-Einstein condensed excitonic phase
in order to understand the behaviour of the trapped excitons.Comment: 41 pages, 23 figure
Oxidation mechanism in metal nanoclusters: Zn nanoclusters to ZnO hollow nanoclusters
Zn nanoclusters (NCs) are deposited by Low-energy cluster beam deposition
technique. The mechanism of oxidation is studied by analysing their
compositional and morphological evolution over a long span of time (three
years) due to exposure to ambient atmosphere. It is concluded that the
mechanism proceeds in two steps. In the first step, the shell of ZnO forms over
Zn NCs rapidly up to certain limiting thickness: with in few days -- depending
upon the size -- Zn NCs are converted to Zn-ZnO (core-shell), Zn-void-ZnO, or
hollow ZnO type NCs. Bigger than ~15 nm become Zn-ZnO (core-shell) type: among
them, NCs above ~25 nm could able to retain their initial geometrical shapes
(namely triangular, hexagonal, rectangular and rhombohedral), but ~25 to 15 nm
size NCs become irregular or distorted geometrical shapes. NCs between ~15 to 5
nm become Zn-void-ZnO type, and smaller than ~5 nm become ZnO hollow sphere
type i.e. ZnO hollow NCs. In the second step, all Zn-void-ZnO and Zn-ZnO
(core-shell) structures are converted to hollow ZnO NCs in a slow and gradual
process, and the mechanism of conversion proceeds through expansion in size by
incorporating ZnO monomers inside the shell. The observed oxidation behaviour
of NCs is compared with theory of Cabrera - Mott on low-temperature oxidation
of metal.Comment: 9 pages, 8 figure
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