308 research outputs found
Several New Active Galactic Nuclei Among X-ray Sources Detected by INTEGRAL and SWIFT Observatories
We present the results of the optical identifications of a set of X-ray
sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical
data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray
sources were identified as active galactic nuclei (AGNs). Two of them are
hosted by nearby, nearly exactly edge-on, spiral galaxies MCG -01-05-047 and
NGC 973. One source, IGR J16562-3301, is most probably BL Lac object (blazar).
Other AGNs are observed as stellar-like nuclei of spiral galaxies, with broad
emission lines in their spectra.
For the majority of our hard X-ray selected AGNs, their hard X-ray
luminosities are well-correlated with the luminosities in [OIII],5007 optical
emission line. However, the luminosities of some AGNs deviate from this
correlation. The fraction of these objects can be as high as 20%. In
particular, the flux in [OIII] line turns to be lower in two nearby edge-on
spiral galaxies, which can be explained by the extinction in their galactic
disks.Comment: 9 pages, 3 figures, accepted for publication in Astronomy Letters,
the original text in Russian can be found at
http://hea.iki.rssi.ru/~rodion/poptid.pd
Directional approach to spatial structure of solutions to the Navier-Stokes equations in the plane
We investigate a steady flow of incompressible fluid in the plane. The motion
is governed by the Navier-Stokes equations with prescribed velocity
at infinity. The main result shows the existence of unique solutions for
arbitrary force, provided sufficient largeness of . Furthermore a
spacial structure of the solution is obtained in comparison with the Oseen
flow. A key element of our new approach is based on a setting which treats the
directino of the flow as \emph{time} direction. The analysis is done in
framework of the Fourier transform taken in one (perpendicular) direction and a
special choice of function spaces which take into account the inhomogeneous
character of the symbol of the Oseen system. From that point of view our
technique can be used as an effective tool in examining spatial asymptotics of
solutions to other systems modeled by elliptic equations
New Kinds of Acoustic Solitons
We find that the modified sine-Gordon equation belonging to the class of the
soliton equations describes the propagation of extremely short transverse
acoustic pulses through the low-temperature crystal containing paramagnetic
impurities with effective spin S=1/2 in the Voigt geometry case. The features
of nonlinear dynamics of strain field and effective spins, which correspond to
the different kinds of acoustic solitons, are studied.Comment: 9 pages, 1 figur
Magnetic structure in the spin liquid TbTiO induced by a [111] magnetic field: Search for a magnetization plateau
We have studied the field-induced magnetic structures of Tb2Ti2O7 pyrochlore by single-crystal neutron diffraction under a field applied along the [111] axis, up to H=12 T and down to T=40 mK. We refined the magnetic structures with k=0 propagation vector by performing a symmetry analysis in the space group R3¯m, reducing the number of free parameters to three only. The Tb moments gradually reorient towards the field direction, keeping close to a “3-in, 1-out / 1-in, 3-out” spin structure (magnetic space group R3¯m′) in the whole measured field range 0.05–12 T. Our results rule out the “all-in/all-out” structure previously proposed and do not support the existence of a magnetization plateau. We perform a quantitative comparison with mean-field calculations and we propose the presence of a low-temperature dynamic symmetry breaking of the local trigonal symmetry, akin to a dynamic Jahn-Teller effect, i.e., preserving the overall cubic symmetry. We discuss the possible origin of this off-diagonal mixing term in the crystal field Hamiltonian in terms of quadrupole-quadrupole interaction or magnetoelastic effects
LISTS OF VOCATIONAL EDUCATION PROGRAMMES: STATUS AND POSSIBLE WAYS OF MODERNISATION
Introduction. The liberalisation of state educational standards and the provision of greater autonomy for educational institutions in the formation of educational programmes indicate the need for development of a new classification system for Russian education, which should become common for all types of professional educational programmes, including additional training programmes. The aim of the publication was to discuss the status and possible ways to modernise the system of classification of educational programmes in Russian vocational education, taking into account the prospects of its development and the constant replenishment of the registers of professional standards and qualifications. Methodology and research methods. In the course of the study, a retrospective analysis of the development of the classification system of professional educational programmes was used, during which the best Russian and foreign practices were compared. Results. The features of the current lists of professions and specialties of secondary vocational education and areas of improvement in accordance with modern requirements of the system of classification of professional educational programmes used in these lists were considered. For updated lists, a new composition of enlarged groups of the classification system of vocational education programs has been proposed, coupled with a list of areas of professional activity of the register of professional standards of the Ministry of Labour of Russia. Scientific novelty. For the first time, it is proposed to refuse classifiers that are strictly tied to the lists of professions, specialties and training areas approved by the Ministry of Education and Science, which formally copy these lists. Combining the classification systems of vocational education programmes and areas of professional activity will allow an adequate comparison of statistical information on training in the education system with their actual use in the labour market.Practical significance. The introduction of the proposed classification system allows us more fully to take into account data on the training of specialists in the Russian system of vocational education, to reflect this data as accurately as possible in national and international educational statistics and to correlate them with employment indicators in various sectors of the economy and production.Введение. Либерализация государственных образовательных стандартов и предоставление большей самостоятельности учебным учреждениям в формировании образовательных программ указывают на необходимость разработки для российского образования новой системы классификации, которая должна стать общей для всех типов профессиональных образовательных программ, включая программы дополнительного обучения. Цель публикации – обсуждение состояния и возможных путей модернизации системы классификации образовательных программ в российском профессиональном образовании с учетом перспектив его развития и постоянного пополнения реестров профессиональных стандартов и квалификаций. Методология и методики. В ходе исследования применялся ретроспективный анализ развития системы классификации профессиональных образовательных программ, при проведении которого проводилось сравнение лучших отечественных и зарубежных практик. Результаты. Рассмотрены особенности действующих перечней профессий и специальностей СПО и направления совершенствования в соответствии с современными требованиями используемой в данных перечнях системы классификации профессиональных образовательных программ. Для обновляемых перечней предложен новый состав укрупненных групп системы классификации профессиональных образовательных программ, сопряженный с перечнем областей профессиональной деятельности реестра профессиональных стандартов Министерства труда России. Научная новизна. Впервые предлагается отказаться от классификаторов, жестко привязанных к утверждаемым Министерством образования и науки перечням профессий, специальностей и направлений подготовки, формально копирующих эти перечни. Сопряжение систем классификации профессиональных образовательных программ и областей профессиональной деятельности позволит осуществлять адекватное сопоставление статистической информации о подготовке кадров в системе образования с их реальным использованием на рынке труда. Практическая значимость. Внедрение предлагаемой системы классификации разрешает более полно учитывать данные об обучении специалистов в российской системе профессионального образования, максимально точно отражать эти данные в национальной и международной образовательной статистике и соотносить их с показателями занятости населения в разных сферах экономики и производства
Backward asymmetry of the Compton scattering by an isotropic distribution of relativistic electrons: astrophysical implications
The angular distribution of low-frequency radiation after single scattering
by an isotropic distribution of relativistic electrons considerably differs
from the Rayleigh angular function. In particular, the scattering by an
ensemble of ultra-relativistic electrons obeys the law p=1-cos(alpha), where
alpha is the scattering angle; hence photons are preferentially scattered
backwards. We discuss some consequences of this fact for astrophysical
problems. We show that a hot electron-scattering atmosphere is more reflective
than a cold one: the fraction of incident photons which become reflected having
suffered a single scattering event can be larger by up to 50 per cent in the
former case. This should affect the photon exchange between cold accretion
disks and hot coronae or ADAF flows in the vicinity of relativistic compact
objects; as well as the rate of cooling (through multiple inverse-Compton
scattering of seed photons supplied from outside) of optically thick clouds of
relativistic electrons in compact radiosources. The forward-backward scattering
asymmetry also causes spatial diffusion of photons to proceed slower in hot
plasma than in cold one, which is important for the shapes of Comptonization
spectra and the time delays between soft and hard radiations coming from
variable X-ray sources.Comment: 20 pages, 3 figures, to appear in Astronomy Letters, added reference
Optical identification of hard X-ray source IGRJ18257-0707
We present the results of the optical identification of hard X-ray source
IGRJ18257-0707 trough the spectroscopic observations of its optical counterpart
with RTT150 telescope. Accurate position of the X-ray source, determined using
Chandra observations, allowed us to associate this source with the faint
optical object (m_R=~20.4), which shows broad H_\alpha emission line in its
optical spectrum. Therefore we conclude that the source IGRJ18257-0707 is a
type 1 Seyfert galaxy at redshift z=0.037.Comment: 4 pages, 3 figures, accepted for publication in Astronomy Letters,
the original text in Russian can be found at
http://hea.iki.rssi.ru/~rodion/pigrj18257-0707.pd
Cosmic polarimetry in magnetoactive plasmas
Polarimetry of the Cosmic Microwave Background (CMB) represents one of the
possible diagnostics aimed at testing large-scale magnetism at the epoch of the
photon decoupling. The propagation of electromagnetic disturbances in a
magnetized plasma leads naturally to a B-mode polarization whose angular power
spectrum is hereby computed both analytically and numerically. Combined
analyses of all the publicly available data on the B-mode polarization are
presented, for the first time, in the light of the magnetized CDM
scenario. Novel constraints on pre-equality magnetism are also derived in view
of the current and expected sensitivities to the B-mode polarization.Comment: 34 pages, 13 figure
Heating of gas inside radio sources to mildly relativistic temperatures via induced Compton scattering
Measured values of the brightness temperature of low-frequency synchrotron
radiation emitted by powerful extragalactic sources reach 10^11--10^12 K. If
some amount of nonrelativistic ionized gas is present within such sources, it
should be heated as a result of induced Compton scattering of the radiation. If
this heating is counteracted by cooling due to inverse Compton scattering of
the same radio radiation, then the plasma can be heated up to mildly
relativistic temperatures kT~10--100 keV. The stationary electron velocity
distribution can be either relativistic Maxwellian or quasi-Maxwellian (with
the high-velocity tail suppressed), depending on the efficiency of Coulomb
collisions and other relaxation processes. We derive several easy-to-use
approximate expressions for the induced Compton heating rate of mildly
relativistic electrons in an isotropic radiation field, as well as for the
stationary distribution function and temperature of electrons. We also give
analytic expressions for the kernel of the integral kinetic equation (one as a
function of the scattering angle and another for the case of an isotropic
radiation field), which describes the redistribution of photons in frequency
caused by induced Compton scattering in thermal plasma. These expressions can
be used in the parameter range hnu<< kT<~ 0.1mc^2 (the formulae earlier
published in Sazonov, Sunyaev, 2000 are less accurate).Comment: 22 pages, 7 figures, submitted to Astronomy Letter
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