462 research outputs found
Two-dimensional magnetoexcitons in the presence of spin-orbit coupling
We study theoretically the effect of spin-orbit coupling on quantum well
excitons in a strong magnetic field. We show that, in the presence of an
in-plane field component, the excitonic absorption spectrum develops a
double-peak structure due to hybridization of bright and dark magnetoexcitons.
If the Rashba and Dresselhaus spin-orbit constants are comparable, the
magnitude of splitting can be tuned in a wide interval by varying the azimuthal
angle of the in-plane field. We also show that the interplay between spin-orbit
and Coulomb interactions leads to an anisotropy of exciton energy dispersion in
the momentum plane. The results suggest a way for direct optical measurements
of spin-orbit parameters.Comment: 9 pages, 6 figure
Non-Linear Algebra and Bogolubov's Recursion
Numerous examples are given of application of Bogolubov's forest formula to
iterative solutions of various non-linear equations: one and the same formula
describes everything, from ordinary quadratic equation to renormalization in
quantum field theory.Comment: LaTex, 21 page
Magnetic Resonance of the Intrinsic Defects of the Spin-Peierls Magnet CuGeO3
ESR of the pure monocrystals of CuGeO3 is studied in the frequency range 9-75
GHz and in the temperature interval 1.2-25 K. The splitting of the ESR line
into several spectral components is observed below 5 K, in the temperature
range where the magnetic susceptibility is suppressed by the spin-Peierls
dimerization. The analysis of the magnetic resonance signals allows one to
separate the signals of the S=1/2- and S=1 defects of the spin-Peierls phase.
The value of g-factor of these signals is close to that of the Cu-ion. The
additional line of the magnetic resonance is characterized by an anomalous
value of the g-factor and by the threshold-like increase of the microwave
susceptibility when the microwave power is increasing. The ESR signals are
supposingly attributed to two types of the planar magnetic defects, arising at
the boundaries of the domains of the spin-Peierls state with the different
values of the phase of the dimerization.Comment: LATEX-text, 12 PS-figures, typos corrected, LATEX-style change
Study of the , , Decays with an SND Detector on a VEPP-2M Collider
The process was studied in the energy range
MeV with an SND detector on a VEPP-2M collider. The
decay branching ratios , , and
were measured.Comment: 5 pages, 4 figure
Anomalous exponents in the rapid-change model of the passive scalar advection in the order
Field theoretic renormalization group is applied to the Kraichnan model of a
passive scalar advected by the Gaussian velocity field with the covariance
. Inertial-range
anomalous exponents, related to the scaling dimensions of tensor composite
operators built of the scalar gradients, are calculated to the order
of the expansion. The nature and the convergence of
the expansion in the models of turbulence is are briefly discussed.Comment: 4 pages; REVTeX source with 3 postscript figure
Антимикробная и антимикотическая фотодинамическая терапия (обзор литературы)
This review highlights the possibilities of photodynamic therapy (PDT) using drugs based on chlorin e6, aluminum phthalocyanine, methylene blue as photosensitizers for bacterial and fungal pathologies. This method was developed initially to treat tumor diseases, where it had shown its high efficiency and safety. Now photodynamic therapy is actively used in the treatment of cancers of the skin, bronchi, stomach, cervix, larynx, or other regions. However, numerous studies have been carried out for the entire existence of the method, demonstrating new possibilities of its application. This review highlights a number of studies in which the efficacy and safety of antimicrobial and antimycotic PDT were studied in vivo and in vitro. It has been proven to have a positive effect on the reparative processes in the wound. An experimental study was carried out to study the effectiveness of photodynamic therapy in the treatment of peritonitis in mice. Demonstrated anti-inflammatory potential in the treatment of autoimmune diseases.В обзоре литературы освещены возможности фотодинамической терапии (ФДТ) с использованием в качестве фотосенсибилизатора (ФС) ряда препаратов, в том числе на основе хлорина е6, фталоцианина алюминия, метиленового синего, при бактериальных и грибковых патологиях. Метод ФДТ изначально был разработан для лечения опухолевых заболеваний, в борьбе с которыми показал свою высокую эффективность и безопасность. В настоящее время ФДТ активно применяется при лечении пациентов с раком кожи, бронхов, желудка, шейки матки, гортани и других локализаций. Однако за все время существования метода были проведены многочисленные исследования, демонстрирующие новые возможности его применения. В настоящем обзоре освещен ряд научно-исследовательских работ, в которых была изучена эффективность и безопасность антимикробной и антимикотической ФДТ в экспериментах in vivo и in vitro. Выполнен обзор публикаций, посвященных изучению механизмов антимикробного действия ФДТ, а также изучающих влияние ФДТ на репаративные процессы в ране. В исследованиях, включенных в настоящий обзор, доказана высокая эффективность антимикробной и антимикотической ФДТ. Продемонстрирован противовоспалительный потенциал метода при лечении аутоиммунных заболеваний у людей
Finite temperature nonlocal effective action for quantum fields in curved space
Massless and massive scalar fields and massless spinor fields are considered
at arbitrary temperatures in four dimensional ultrastatic curved spacetime.
Scalar models under consideration can be either conformal or nonconformal and
include selfinteraction. The one-loop nonlocal effective action at finite
temperature and free energy for these quantum fields are found up to the second
order in background field strengths using the covariant perturbation theory.
The resulting expressions are free of infrared divergences. Spectral
representations for nonlocal terms of high temperature expansions are obtained.Comment: 32 pages, LaTe
Observational Manifestations of the First Protogalaxies in the 21 cm Line
The absorption properties of the first low-mass protogalaxies (mini-halos)
forming at high redshifts in the 21-cm line of atomic hydrogen are considered.
The absorption properties of these protogalaxies are shown to depend strongly
on both their mass and evolutionary status. The optical depths in the line
reach 0.1-0.2 for small impact parameters of the line of sight. When a
protogalaxy being compressed, the influence of gas accretion can be seen
manifested in a non-monotonic frequency dependence of the optical depth. The
absorption characteristics in the 21-cm line are determined by the thermal and
dynamical evolution of the gas in protogalaxies. Since the theoretical line
width in the observer's reference frame is 1-6 kHz and the expected separation
between lines 8.4 kHz, the lines from low mass protogalaxies can be resolved
using ongoing and future low frequency interferometers.Comment: 12 pages, 5 figure
О разработке новых криминалистических средств выявления следов кожного покрова человека
The article reviews the main physical and physicochemical factors influencing the three-component system “fingerprint powder – prints bearing surface – sweat and grease print substance”. The authors propose new model compositions of fingerprint powders considering the reviewed common patterns: non-magnetic and luminescent magnetic. The features of prints bearing surfaces and developed fingerprint powders have been evaluated by applying electronic microscopy methods (scanning and probe microscopy). The authors have proven that the use of nano- and ultra disperse materials in the developed compositions (carbon nanotubes and shungite) enables to vary the sorption and adhesive capacity of fingerprint powders, which allows detecting fingerprints on varying surfaces with high selectivity toward the sweat and grease print substance and contrasting effect.Несмотря на широкий спектр технико-криминалистических средств выявления и фиксации следов кожного покрова человека, проблема разработки дактилоскопических порошков, обладающих одновременно универсальностью по отношению к различным поверхностям и специфичностью при взаимодействии с потожировым веществом, остается актуальной. В статье рассмотрены основные физические и физико-химические факторы, оказывающие влияние на трехкомпонентную систему «дактилоскопический порошок – следонесущая поверхность – потожировое вещество следа». Разработаны новые модельные составы дактилоскопических порошков: немагнитного и люминесцентного магнитного с учетом рассмотренных закономерностей. Характеристики полученных порошков, а также следонесущие поверхности оценивали методами электронной микроскопии (растровой и зондовой). Показано, что применение нано- и ультрадисперсных материалов (углеродных нанотрубок и шунгита) в разработанных составах позволяет варьировать сорбционную и адгезионную способность порошков. Это делает возможным выявление следов рук на различных по контрастности и свойствам поверхностях с высокой селективностью по отношению к потожировому веществу следа.
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