1,960 research outputs found
Uniqueness of the electrostatic solution in Schwarzschild space
In this Brief Report we give the proof that the solution of any static test
charge distribution in Schwarzschild space is unique. In order to give the
proof we derive the first Green's identity written with p-forms on (pseudo)
Riemannian manifolds. Moreover, the proof of uniqueness can be shown for either
any purely electric or purely magnetic field configuration. The spacetime
geometry is not crucial for the proof.Comment: 3 pages, no figures, uses revtex4 style file
Finite hadronization time and unitarity in quark recombination model
The effect of finite hadronization time is considered in the recombination
model, and it is shown that the hadron multiplicity turns out to be
proportional to the initial quark density and unitarity is conserved in the
model. The baryon to meson ratio increases rapidly with the initial quark
density due to competition among different channels.Comment: 4 pages in RevTeX, 3 eps figures, to appear in J. Phys.G as a lette
Spin-dependent transmission through a chain of rings: influence of a periodically modulated spin-orbit interaction strength or ring radius
We study ballistic electron transport through a finite chain of quantum
circular rings in the presence of spin-orbit interaction of strength \alpha.
For a single ring the transmission and reflection coefficients are obtained
analytically and from them the conductance for a chain of rings as a function
of \alpha and of the wave vector k of the incident electron. We show that due
to destructive spin interferences the chain can be totaly opaque for certain
ranges of k the width of which depends on the value of \alpha. A periodic
modulation of the strength \alpha or of the ring radius widens up the gaps
considerably and produces a nearly binary conductance output.Comment: 4 pages, 4 figures. Appl. Phys. Lett., in pres
Retention Behaviour of MNOS Memory Devices with Embedded Si or Ge Nanocrystals – Computer Simulation
The charge retention behaviour of MNOS structures with embedded Si or Ge nanocrystals are studied by computer simulation. It is obtained that the oxide thickness and the location of nanocrystlas affect the retention behaviour very strongly. The retention time changes from a few ms to several years.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3538
Chemical and kinetic equilibrations via radiative parton transport
A hot and dense partonic system can be produced in the early stage of a
relativistic heavy ion collision. How it equilibrates is important for the
extraction of Quark-Gluon Plasma properties. We study the chemical and kinetic
equilibrations of the Quark-Gluon Plasma using a radiative transport model.
Thermal and Color-Glass-Condensate motivated initial conditions are used. We
observe that screened parton interactions always lead to partial pressure
isotropization. Different initial pressure anisotropies result in the same
asymptotic evolution. Comparison of evolutions with and without radiative
processes shows that chemical equilibration interacts with kinetic
equilibration and radiative processes can contribute significantly to pressure
isotropization.Comment: Presented at 24th International Nuclear Physics Conference
(INPC2010), Vancouver, Canada, 4-9 July 201
Time evolution in the Morse potential using supersymmetry: dissociation of the NO molecule
We present an algebraic method for treating molecular vibrations in the Morse
potential perturbed by an external laser field. By the help of a complete and
normalizable basis we transform the Schr\"{o}dinger equation into a system of
coupled ordinary differential equations. We apply our method to calculate the
dissociation probability of the NO molecule excited by chirped laser pulses.
The dependence of the molecular dipole-moment on the interatomic separation is
determined by a quantum-chemical method, and the corresponding transition
dipole moments are given by approximate analytic expressions. These turn out to
be very small between neighboring stationary states around the vibrational
quantum number , therefore we propose to use additional pulses in order
to skip this trapping state, and to obtain a reasonable dissociation
probability.Comment: 4 pages, 3 figure
Electrical Noise From Phase Separation In Pr2/3Ca1/3MnO3 Single Crystal
Low frequency electrical noise measurements have been used to probe the
electronic state of the perovskite-type manganese oxide Pr2/3Ca1/3MnO3 versus
temperature and in the vicinity of the field-induced transition from the
insulating, charge-ordered state (I-CO) to the metallic, ferromagnetic state
(M-F). At high temperature we have observed a high level of the excess noise
with mainly a gaussian distribution of the resistance fluctuations, and the
associated power spectral density has a standard 1/f dependence. However, in
the hysteretic region, where the electrical resistance depends dramatically on
the sample history, we have observed a huge non-gaussian noise characterized by
two level fluctuator-like switching (TLS) in the time domain. We discuss the
origin of the noise in terms of percolative behavior of the conductivity. We
speculate that the dominant fluctuators are manganese clusters switching
between the M-F and the I-CO phases.Comment: RevTeX, 6 pages with 3 figure
Changes in the hardwood groves of the Martonvásár Manor Park (Hungary) in the last 30 years
The subject of the present study is the monitoring of the hardwood groves at the Martonvásár Manor Park with the involvement of 20 earlier (recorded in 1980–1981) and 20 current (recorded in 2011–2012) phytocoenological relevés. The manor park was created in the first half of the 19th century. Since then the woods along the St László stream have developed into species-rich and semi-natural forests, which can be identified as related to the oak-ash-elm groves (Scillo vindobonensis-Ulmetum) of the Zámoly Basin and the Csepel Island. The results of the current monitoring repeated 30 years after the first survey show momentous changes in forest dynamics such as the ageing-related opening of the upper canopy and an intense closure of the lower canopy and shrub layer. The ratio of the invasive species doubled. Present findings may provide additional information for long-term forest ecology research, however, results could be considered as changes of a semi-natural hardwood forest with minimal human impact
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