882 research outputs found
High Order Riesz Transforms and Mean Value Formula for Generalized Translate Operator
In this paper, the mean value formula depends on the Bessel generalized shift
operator corresponding to the solutions of the boundary value problem related
to the Bessel operator are studied. In addition to, Riesz Bessel transforms
related to the Bessel operators are studied. Since Bessel generalized shift
operator is translation operator corresponding to the Bessel operator, we
construct a family of RBxj by using Bessel generalized shift operator. Finally,
we analysis weighted inequalities involving Riesz Bessel transforms
Drukčiji matematički model za sklop tranzistorskog pretvarača (chopper-a)
In this study, dc-dc boost converter circuit is described as transformer circuit for direct form of energy in the electrical machine driver system of electrical and electronic engineering.First, mathematical equations of the converter circuit are created when circuit switch opened and closed controlling two states. Then, the equations are resolved for common equation so that the state space equation is formed in matrix form. A mathematical model of the converter circuit is performed at the Matlab Simulink.U ovom istraživanju opisan je sklop istosmjernog uzlaznog pretvarača kao transformatorski sklop za izravne oblike energije u vozačkom sustavu električnog motora u elektrotehnici i elektronici. Prvo su kreirane matematičke jednadžbe sklopa pretvarača, a sklopka sklopa otvaranjem i zatvaranjem kontrolira dva stanja. Zatim su riješene jednadžbe za opću jednadžbu tako što je jednadžba prostora stanja formirana u matričnom obliku. Matematički model stvorenog pretvarača sklopa izveden je u Matlab Simulink
MicroRNA Control of Invasion and Metastasis Pathways
Despite recent advances, cancer remains a leading cause of death worldwide. In developed countries, the incidence of colorectal and breast cancer has been stable, but no improvement in prognosis has been observed if the patient presents with metastases at diagnosis. This fact highlights the importance of therapeutic approaches targeting cellular invasion and metastasis programs as the next step in cancer treatment. During carcinoma progression a process called epithelial–mesenchymal transition (EMT) results in enhanced invasion and motility which is directly linked with loss of epithelial polarity and epithelial junctions, migration permissive cytoskeleton alterations, and the acquisition of mesenchymal properties. The recent discovery of microRNAs (miRNAs) controlling key cellular pathways has opened a new era in understanding how EMT pathways are modulated. In this review, we classify EMT regulating proteins according to their cellular localization (membrane, cytoplasmic, and nuclear), and summarize the current knowledge on how they are controlled by miRNAs and propose potential miRNAs for the transcripts that may control their expression
Growth and physical property study of single nanowire (diameter ~ 45nm) of half doped Manganite
We report here the growth and characterization of functional oxide nanowire
of hole doped manganite of La0.5Sr0.5MnO3 (LSMO). We also report four probe
electrical resistance measurement of single nanowire of LSMO (diameter ~ 45nm)
using FIB fabricated electrodes. The wires were fabricated by hydrothermal
method using autoclave at a temperature of 270 oC. The elemental analysis and
physical property like electrical resistivity were studied at individual
nanowire level. The quantitative determination of Mn valency and elemental
mapping of constituent elements was done by using Electron Energy Loss
Spectroscopy (EELS) in the Scanning Transmission Electron Microscopy (STEM)
mode. We addressed the important issue of whether as a result of size reduction
the nanowires can retain the desired composition, structure and physical
properties. The nanowires used were found to have a ferromagnetic transition
(TC) at around 325 K which is very close to the bulk value of around 330 K
found in single crystal of the same composition confirming that the functional
behavior is likely to be retained even after size reduction of the nanowires to
a diameter of 45 nm. The electrical resistivity shows insulating behavior
within the temperature range measured, which is very much similar to the bulk
system.Comment: 11 pages, 7 figures, accepted in Journal of Nanomaterial
A new Tolman test of a cosmic distance duality relation at 21 cm
Under certain general conditions in an expanding universe, the luminosity
distance (d_L) and angular diameter distance (d_A) are connected by the
Etherington relation as d_L = d_A (1 + z)^2. The Tolman test suggests the use
of objects of known surface brightness, to test this relation. In this letter,
we propose the use of redshifted 21 cm signal from disk galaxies, where neutral
hydrogen (HI) masses are seen to be almost linearly correlated with surface
area, to conduct a new Tolman test. We construct simulated catalogs of
galaxies, with the observed size-luminosity relation and realistic redshift
evolution of HI mass functions, likely to be detected with the planned Square
Kilometer Array (SKA). We demonstrate that these observations may soon provide
the best implementation of the Tolman test to detect any violation of the
Etherington relation.Comment: 4 pages, 2 figures, 1 table, v2: published versio
Exchange Bias Effect in Au-Fe3O4 Nanocomposites
We report exchange bias (EB) effect in the Au-Fe3O4 composite nanoparticle
system, where one or more Fe3O4 nanoparticles are attached to an Au seed
particle forming dimer and cluster morphologies, with the clusters showing much
stronger EB in comparison with the dimers. The EB effect develops due to the
presence of stress in the Au-Fe3O4 interface which leads to the generation of
highly disordered, anisotropic surface spins in the Fe3O4 particle. The EB
effect is lost with the removal of the interfacial stress. Our atomistic
Monte-Carlo studies are in excellent agreement with the experimental results.
These results show a new path towards tuning EB in nanostructures, namely
controllably creating interfacial stress, and open up the possibility of tuning
the anisotropic properties of biocompatible nanoparticles via a controllable
exchange coupling mechanism.Comment: 28 pages, 6 figures, submitted to Nanotechnolog
Planetoid strings : solutions and perturbations
A novel ansatz for solving the string equations of motion and constraints in
generic curved backgrounds, namely the planetoid ansatz, was proposed recently
by some authors. We construct several specific examples of planetoid strings in
curved backgrounds which include Lorentzian wormholes, spherical Rindler
spacetime and the 2+1 dimensional black hole. A semiclassical quantisation is
performed and the Regge relations for the planetoids are obtained. The general
equations for the study of small perturbations about these solutions are
written down using the standard, manifestly covariant formalism. Applications
to special cases such as those of planetoid strings in Minkowski and spherical
Rindler spacetimes are also presented.Comment: 24 pages (including two figures), RevTex, expanded and figures adde
Cosmology with decaying tachyon matter
We investigate the case of a homogeneous tachyon field coupled to gravity in
a spatially flat Friedman-Robertson-Walker spacetime. Assuming the field
evolution to be exponentially decaying with time we solve the field equations
and show that, under certain conditions, the scale factor represents an
accelerating universe, following a phase of decelerated expansion. We make use
of a model of dark energy (with p=-\rho) and dark matter (p=0) where a single
scalar field (tachyon) governs the dynamics of both the dark components. We
show that this model fits the current supernova data as well as the canonical
\LambdaCDM model. We give the bounds on the parameters allowed by the current
data.Comment: 14 pages, 6 figures, v2, Discussions and references addede
FORMULATION OF FAST-DISSOLVING TABLETS OF DOXAZOSIN MESYLATE DRUG BY DIRECT COMPRESSION METHOD
Objective: The rationale of the current research work was to formulate and evaluate fast-dissolving tablets of doxazosin mesylate with minimum disintegration time and improved dissolution efficiency using solid dispersion method.Methods: Solid dispersions of doxazosin mesylate and polyethylene glycol 8000 in different ratios were prepared using the kneading method. The prepared solid dispersions were subjected to drug interaction and dissolution studies to select the effective solid dispersion for the formulation of fast-dissolving tablets. Fast dissolving tablets containing drug-polyethylene glycol 8000 solid dispersion (1:3) were prepared using various super-disintegrants such as crospovidone, croscarmellose sodium, mixture and coprocessed crospovidone and croscarmellose sodium in concentration range of 2% and 5% by direct compression technique. The prepared formulations (F1–F16) were evaluated for post compression parameters; hardness, thickness, friability, wetting time, disintegration time, and in–vitro drug release.Results: Drug doxazosin mesylate showed enhanced aqueous solubility of 13.3µg/ml in the presence of polyethylene glycol 8000. Differential scanning calorimetery and Fourier transform infrared spectroscopy studies confirmed no interaction between drug and polyethylene glycol 8000and, drug-polyethylene glycol 8000 solid dispersion showed cumulative drug release of 44.48% in 60 min. Formulated FDT of drug-polyethylene glycol 8000 solid dispersion, containing coprocessed mixture of crospovidone and croscarmellose sodium (5%) exhibited disintegration time of 14.5s with percentage cumulative release of 92.46% in 60 min.Conclusion: The work reasonably concludes that for the formulated doxazosin mesylate-fast dissolving tablets, disintegration time was effectively reduced by the presence of coprocessed mixture of crospovidone and croscarmellose sodium and dissolution efficiency was improved by preparation of solid dispersion with polyethylene glycol 8000
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