197 research outputs found
Nonlinear double Compton scattering in the full quantum regime
A detailed analysis of the process of two photon emission by an electron
scattered from a high-intensity laser pulse is presented. The calculations are
performed in the framework of strong-field QED and include exactly the presence
of the laser field, described as a plane wave. We investigate the full quantum
regime of interaction, where photon recoil plays an essential role in the
emission process, and substantially alters the emitted photon spectra as
compared to those in previously-studied regimes. We provide a semiclassical
explanation for such differences, based on the possibility of assigning a
trajectory to the electron in the laser field before and after each quantum
photon emission. Our numerical results indicate the feasibility of
investigating experimentally the full quantum regime of nonlinear double
Compton scattering with already available plasma-based electron accelerator and
laser technology.Comment: 5 pages, 3 figure
Концепція, інформаційно-аналітичне та системне програмно-технічне забезпечення ЄІАС " Вибори"
Базаров Д. А. Концепція, інформаційно-аналітичне та системне програмно-технічне забезпечення ЄІАС " Вибори" / Д. А. Базаров // Теоретичні та практичні проблеми забезпечення сталого розвитку державності та права : матер. міжнар. наук. конф. (Одеса, 30 листопада 2012 р.) Т.1 / відп. за випуск д.ю.н., проф. В. М. Дрьомін ; Націон. ун-т «Одеська юридична академія». – Одеса : Фенікс, 2012. – С. 747-749
New phase structure of the Nambu -- Jona - Lasinio model at nonzero chemical potential
It is shown that in the Nambu -- Jona - Lasinio model at nonzero chemical
potential there are two different massive phases with spontaneously broken
chiral symmetry. In one of them particle density is identically zero, in
another phase it is not equal to zero. The transition between phases is a phase
transition of the second order.Comment: 8 pages, LaTeX, no figures
Обеспечение информационной безопасности ЕИАС "Выборы" на выборах народных депутатов 2012
Базаров Д. А. Обеспечение информационной безопасности ЕИАС "Выборы" на выборах народных депутатов 2012 / Д. А. Базаров // Правове життя сучасної України : матеріали Міжнар. наук. конф. проф.-викл. та аспірант. складу (м. Одеса, 16-17 травня 2013 р.) / відп. за вип. В. М. Дрьомін ; НУ "ОЮА". Півд. регіон. центр НАПрН України. - Одеса : Фенікс, 2013. - Т. 1. - С. 746-747
Formation of the internal structure of solids under severe action
On the example of a particular problem, the theory of vacancies, a new form
of kinetic equations symmetrically incorporation the internal and free energies
has been derived. The dynamical nature of irreversible phenomena at formation
and motion of defects (dislocations) has been analyzed by a computer
experiment. The obtained particular results are extended into a thermodynamic
identity involving the law of conservation of energy at interaction with an
environment (the 1st law of thermodynamics) and the law of energy
transformation into internal degree of freedom (relaxation). The identity is
compared with the analogous Jarzynski identity. The approach is illustrated by
simulation of processes during severe plastic deformation, the Rybin kinetic
equation for this case has been derived.Comment: 9 pages, 5 figure
Synchrotron radiation representation in phase space
The notion of brightness is efficiently conveyed in geometric optics as
density of rays in phase space. Wigner has introduced his famous distribution
in quantum mechanics as a quasi-probability density of a quantum system in
phase space. Naturally, the same formalism can be used to represent light
including all the wave phenomena. It provides a natural framework for radiation
propagation and optics matching by transferring the familiar `baggage' of
accelerator physics (beta-function, emittance, phase space transforms, etc.) to
synchrotron radiation. This paper details many of the properties of the Wigner
distribution and provides examples of how its use enables physically insightful
description of partially coherent synchrotron radiation in phase space
Beam-Breakup Instability Theory for Energy Recovery Linacs
Here we will derive the general theory of the beam-breakup instability in
recirculating linear accelerators, in which the bunches do not have to be at
the same RF phase during each recirculation turn. This is important for the
description of energy recovery linacs (ERLs) where bunches are recirculated at
a decelerating phase of the RF wave and for other recirculator arrangements
where different RF phases are of an advantage. Furthermore it can be used for
the analysis of phase errors of recirculated bunches. It is shown how the
threshold current for a given linac can be computed and a remarkable agreement
with tracking data is demonstrated. The general formulas are then analyzed for
several analytically solvable cases, which show: (a) Why different higher order
modes (HOM) in one cavity do not couple so that the most dangerous modes can be
considered individually. (b) How different HOM frequencies have to be in order
to consider them separately. (c) That no optics can cause the HOMs of two
cavities to cancel. (d) How an optics can avoid the addition of the
instabilities of two cavities. (e) How a HOM in a multiple-turn recirculator
interferes with itself. Furthermore, a simple method to compute the orbit
deviations produced by cavity misalignments has also been introduced. It is
shown that the BBU instability always occurs before the orbit excursion becomes
very large.Comment: 12 pages, 6 figure
Electronic structure of β-RbSm(MoO4)(2) and chemical bonding in molybdates
Microcrystals of orthorhombic rubidium samarium molybdate, β-RbSm(MoO4)2, have been fabricated by solid state synthesis at T = 450 °C, 70 h, and at T = 600 °C, 150 h. The crystal structure has been refined by the Rietveld method in space group Pbcn with cell parameters a = 5.0984(2), b = 18.9742(6) and c = 8.0449(3) Å (RB = 1.72%). Thermal properties of β-RbSm(MoO4)2 were traced by DSC over the temperature range of T = 20–965 °C, and the earlier reported β ↔ α phase transition at T ∼ 860–910 °C was not verified. The electronic structure of β-RbSm(MoO4)2 was studied by employing theoretical calculations and X-ray photoelectron spectroscopy. It has been established that the O 2p-like states contribute mainly to the upper part of the valence band and occupy the valence band maximum, whereas the Mo 4d-like states contribute mainly to the lower part of the valence band. Chemical bonding effects have been analysed from the element core level binding energy data. In addition, it was found that the luminescence spectrum of β-RbSm(MoO4)2 is rather peculiar among the Sm3+ containing materials. The optical refractive index dispersion in β-RbSm(MoO4)2 was also predicted by the first-principles calculations
The crystal growth and properties of novel magnetic double molybdate RbFe(MoO) with mixed Fe/Festates and 1D negative thermal expansion
Single crystals of new compound RbFe(MoO) were successfully grown by the flux method, and their crystal structure was determined using the X-ray single-crystal diffraction technique. The XRD analysis showed that the compound crystallizes in the monoclinic space group P21/m, with unit cell parameters a = 6.8987(4), b = 21.2912(12) and c = 8.6833(5) Å, β = 102.1896(18)°, V = 1246.66(12) Å, Z (molecule number in the unit cell) = 2, R-factor (reliability factor) = 0.0166, and T = 293(2) K. Raman spectra were collected on the single crystal to show the local symmetry of MoO tetrahedra, after the confirmation of crystal composition using energy dispersive X-ray spectroscopy (EDS). The polycrystalline samples were synthesized by a solid-state reaction in the Ar atmosphere; the particle size and thermal stability were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses. The compound decomposes above 1073 K in an Ar atmosphere with the formation of Fe(III) molybdate. The thermal expansion coefficient along the c direction has the value α = −1.3 ppm K over the temperature range of 298–473 K. Magnetic measurements revealed two maxima in the magnetization below 20 K, and paramagnetic behavior above 50 K with the calculated paramagnetic moment of 12.7 μB per formula unit is in good agreement with the presence of Fe and Fe in the high-spin (HS) state. The electronic structure of RbFe5(MoO4)7 is comparatively evaluated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations
Phylogenetic analysis of the microbial mat in the hot spring Garga (Baikal rift zone) and the diversity of natural peptidases
Hydrolytic bacteria (in particular, proteolytics) are the primary destructors in hot springs. The proteolytic bacteria are able to secrete enzymes that are active in wide ranges of pH and temperature. The aim of this work was to study the taxonomic composition, the structure of the bacterial microbial mat, and to study the distribution of peptidases in the thermophilic microbial Garga community. For the study, we sampled the microbial mat at a water temperature of 54.2 °C and a pH of 8.3. Hydrochemical analysis of water showed a high content of sulfates, 390 mg/dm3. The microelement composition of water showed that the Garga water had increased concentrations of B, Rb, Li, Ba, Sr. We analyzed the taxonomic diversity of the microbial community in the hot spring Garga at a temperature zone of 54 °C. The structure of the microbial mat is represented by various phylogenetic groups of mesophilic and thermophilic bacteria, with various metabolic and ecological functions. The dominant group in this community was the phylum Firmicutes (64 %). The analysis of the collected metagenomic sequences of the microbial community allowed the detected peptidases in the microbial community in the hot spring Garga to be for the first time systematized and characterized. Comparisons of metagenomic sequences of representative data showed a dominance of serine peptidase class enzymes. Natural peptidases in the investigated microbial community ensure the hydrolysis of biopolymers at the first stages of the destruction of organic matter and may have biotechnological relevance
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