774 research outputs found
A nonstationary form of the range refraction parabolic equation and its application as an artificial boundary condition for the wave equation in a waveguide
The time-dependent form of Tappert's range refraction parabolic equation is
derived using Daletskiy-Krein formula form noncommutative analysis and proposed
as an artificial boundary condition for the wave equation in a waveguide. The
numerical comparison with Higdon's absorbing boundary conditions shows
sufficiently good quality of the new boundary condition at low computational
cost.Comment: 12 pages, 9 figure
Structural phase control of (LaNdSr)CuO thin films by epitaxial growth technique
Epitaxial growth of (LaNdSr)CuO thin films was
studied by pulsed-laser deposition technique on three different substrates,
SrTiO (100), LaSrAlO (001), and YAlO (001). The
(Nd,Sr,Ce)CuO-type structure appears at the initial growth stage on
SrTiO (100) when the film is deposited under the growth conditions
optimized for (La,Sr)CuO. This (Nd,Sr,Ce)CuO-type structure can
be eliminated by increasing the substrate temperature and the laser repetition
frequency. Films on LaSrAlO (001) maintain a LaCuO-type structure
as bulk samples, but those on YAlO (001) show phase separation into
LaCuO- and NdCuO-type structures. Such complicated results are
explained in terms of the competition between lattice misfit and thermodynamic
conditions. Interestingly the films with LaCuO-type structure prepared
on SrTiO and LaSrAlO show different surface structures and transport
properties. The results indicate the possibility of controlling charge stripes
of (LaNdSr)CuO as was demonstrated in
(La,Ba)CuO thin films by Sato et al. (Phys. Rev. B {\bf 62}, R799
(2000)).Comment: 5 pages, 6 EPS figure, accepted for publication in Phys. Rev.
Low-background applications of MICROMEGAS detector technology
The MICROMEGAS detector concept, generally optimized for use in accelerator
experiments, displays a peculiar combination of features that can be
advantageous in several astroparticle and neutrino physics applications. Their
sub-keV ionization energy threshold, excellent energy and space resolution, and
a simplicity of design that allows the use of radioclean materials in their
construction are some of these characteristics. We envision tackling
experimental challenges such as the measurement of neutral-current
neutrino-nucleus coherent scattering or Weakly Interacting Massive Particle
(WIMP) detectors with directional sensitivity. The large physics potential of a
compact (total volume O(1)m), multi-purpose array of low-background
MICROMEGAS is made evident.Comment: 5 pg, presented at IMAGING-2000, Stockholm, June 2000. To appear in
Nucl. Instr. & Meth. Final version after referees' inpu
Extension of the Space Experiment GRIS Onboard the ISS Capabilities: Registration of Short Gamma-ray Bursts and TGF
The unique capabilities of the detector, based on the CeBr3 crystal (very short flashing time) allow us to expand the range of problems solved in the GRIS experiment. In addition to registering solar flares that have characteristic times per second÷minute, this detector allows solving problems in identifying and recording characteristics of geophysical and astrophysical events (short gamma-ray bursts - SGRB and terrestial gamma-ray flares - TGF) in the time range of 10μs÷1 ms. The modification of the hardware of the GRIS device for solving these problems is described and discussed in this paper
Neutrino Properties Studied with a Triton Source Using Large TPC Detectors
The purpose of the present paper is to study the neutrino properties as they
may appear in the low energy neutrinos emitted in triton decay, with maximum
neutrino energy of 18.6 KeV. The technical challenges to this end can be
summarized as building a very large TPC capable of detecting low energy
recoils, down to a few 100 eV, within the required low background constraints.
More specifically We propose the development of a spherical gaseous TPC of
about 10-m in radius and a 200 Mcurie triton source in the center of curvature.
One can list a number of exciting studies, concerning fundamental physics
issues, that could be made using a large volume TPC and low energy
antineutrinos:1) The oscillation length involving the small mixing angle in the
electronic neutrino disappearancei experiment is comparable to the length of
the detector. Measuring the counting rate of neutrino-electron elastic
scattering will give a precise measurement of the oscillation parameters free
of systematic errors. First estimations show that a sensitivity of a few
percent for the measurement of the above angle. 2) The low energy detection
threshold offers a unique sensitivity for the neutrino magnetic moment which is
about two orders of magnitude beyond the current experimental limit. 3)
Scattering at such low neutrino energies has never been studied and any
departure from the expected behavior may be an indication of new physics beyond
the standard model. We present results of theoretical calculation and studies
of possible measurements.Comment: 30 LaTex pages and 9 figure
Notion of territorial system's structure and some approaches to their modeling
Development, forming and functioning of the territorial systems of each level of hierarchy and form are complicated and durable processes. The notion of stability occupies the central place and connects with the presence in territorial system some unchangeable invariant, which serves as a starting point of stability. As an example of such invariant (the base carrier of invariant on time characteristics) the usage of structural sistem is proposed. Assignment of territorial system's structure as a function carrier and simultaneous as an invariant in time permits to state the question of the system management by influence on the structure. Ability of the structure for improvement mainly determines peculiarities of the territorial system's behavior and possibilities of their management. Proposed approach permits to use for modeling structure (general and special) multitude theory, which in one tern gives the possibility to determine the corresponding models and modeling structures, pick up special structures in accordance to their inner condition, use their different combinations as multitude of relations and multitude of operations as a base for the modeling structures, etc
Complex ecological-economical systems: Problems of study (economical aspect)
Economical mechanism of the regional land use has been studied as a basis of sustainable development. System of payment for the natural resources considered as a base of it. These payments reflect the diversity of economical forms of property rights by the subjects of the Russian Federation to the natural resources. Rent can serve as a basis for forming the rates of payments, as in the market economy the price for the natural resources is the capitalised rent. It is stated that the payment for the natural resources is the economical form of treatment, which has been pooling together during the process of their owing, using and ordering between their owners and users. The region appropriate the rent, as it is the owner of the bowels of the earth, and in some cases the land rent or the tax on it (under the presence of the private property to the land). The interconnection of such notions as economical growth, land use and protection of the environment has been proofed. The common goals and specific tasks of coming to a cooperative decision has been put, which are necessary for the land use
Neutrinos in a spherical box
In the present paper we study some neutrino properties as they may appear in
the low energy neutrinos emitted in triton decay with maximum neutrino energy
of 18.6 keV. The technical challenges to this end can be achieved by building a
very large TPC capable of detecting low energy recoils, down to a a few tenths
of a keV, within the required low background constraints. More specifically We
propose the development of a spherical gaseous TPC of about 10-m in radius and
a 200 Mcurie triton source in the center of curvature. One can list a number of
exciting studies, concerning fundamental physics issues, that could be made
using a large volume TPC and low energy antineutrinos: 1) The oscillation
length involving the small angle of the neutrino mixing matrix, directly
measured in this disappearance experiment, is fully contained inside the
detector. Measuring the counting rate of neutrino-electron elastic scattering
as a function of the distance of the source will give a precise and unambiguous
measurement of the oscillation parameters free of systematic errors. In fact
first estimates show that even with a year's data taking a sensitivity of a few
percent for the measurement of the above angle will be achieved. 2) The low
energy detection threshold offers a unique sensitivity for the neutrino
magnetic moment which is about two orders of magnitude beyond the current
experimental limit. 3) Scattering at such low neutrino energies has never been
studied and any departure from the expected behavior may be an indication of
new physics beyond the standard model. In this work we mainly focus on the
various theoretical issues involved including a precise determination of the
Weinberg angle at very low momentum transfer.Comment: 16 Pages, LaTex, 7 figures, talk given at NANP 2003, Dubna, Russia,
June 23, 200
Torque Teno Virus (TTV) distribution in healthy Russian population
<p>Abstract</p> <p>Background</p> <p>Torque teno virus (TTV) is a circular, single-stranded DNA virus that chronically infects healthy individuals of all ages worldwide. There is a lot of data on the prevalence and genetic heterogeneity of TTV in healthy populations and in patients with various diseases now available. However, little is known about TTV load among healthy human population. In this study we analyzed TTV load in the group of 512 Russian elite athletes, who are supposed to be, by some standards, the healthiest part of the human population.</p> <p>Results</p> <p>The prevalence rate of TTV among the Russian Olympic Reserve members was 94% (for test sensitivity about 1000 genome equivalents per 1 ml of blood). Quantities varied from 10<sup>3 </sup>(which corresponded to detection limit) to 10<sup>10 </sup>copies per 1 ml of blood, with median at 2.7 × 10<sup>6 </sup>copies.</p> <p>Conclusion</p> <p>About 94% of healthy individuals in Russian population have more than 1000 TTV genome copies per 1 ml of blood. This result exceeds the previously published data, and can be explained by either more sensitive PCR test system or by higher TTV distribution in Russian population or both. TTV viral load neither depends on gender, nor age.</p
Singularities, Lax degeneracies and Maslov indices of the periodic Toda chain
The n-particle periodic Toda chain is a well known example of an integrable
but nonseparable Hamiltonian system in R^{2n}. We show that Sigma_k, the k-fold
singularities of the Toda chain, ie points where there exist k independent
linear relations amongst the gradients of the integrals of motion, coincide
with points where there are k (doubly) degenerate eigenvalues of
representatives L and Lbar of the two inequivalent classes of Lax matrices
(corresponding to degenerate periodic or antiperiodic solutions of the
associated second-order difference equation). The singularities are shown to be
nondegenerate, so that Sigma_k is a codimension-2k symplectic submanifold.
Sigma_k is shown to be of elliptic type, and the frequencies of transverse
oscillations under Hamiltonians which fix Sigma_k are computed in terms of
spectral data of the Lax matrices. If mu(C) is the (even) Maslov index of a
closed curve C in the regular component of R^{2n}, then (-1)^{\mu(C)/2} is
given by the product of the holonomies (equal to +/- 1) of the even- (or odd-)
indexed eigenvector bundles of L and Lmat.Comment: 25 pages; published versio
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