209 research outputs found
Observations of Sy2 galaxy NGC 3281 by XMM-Newton and INTEGRAL satellites
We present here the results of our analysis of X-ray properties of Seyfert 2
galaxy NGC 3281, based on the observational data obtained by XMM-Newton and
INTEGRAL within the energy ranges 0.2-12 keV and 20-150 keV, respectively. The
XMM-Newton spectrum of this object is presented for the first time. We show
that fitting the X-ray spectrum of this galaxy with models based on the
reflection from the disc with infinite column density yields non-physical
results. More appropriate fit takes into account both transmitted and reflected
emission, passed through a gas-dusty torus-like structure. Keeping this in
mind, to model the inhomogeneous clumpy torus, we used the MYTorus model.
Hence, we propose that the torus of NGC 3281 is not continuous structure, but
it consists of separate clouds, which is in a good agreement with the results
of near-IR observations. Using this assumption, we found that the torus
inclination angle and the hydrogen column density are 66.98^{+2.63}_{-1.34}
degrees and 2.08^{+0.35}_{-0.18}x10^{24} cm^{-2}, respectively. Also, the
emission of the hot diffuse gas with temperature ~590 eV and warm absorption
were detected.Comment: 8 pages, 5 figures, 2 tables, accepted for publication in Advances in
Astronomy and Space Physic
Nonequilibrium transport equations and ab initio study of adsorption processes on carbon nanotubes
In a theoretical study of gas adsorption on carbon nanotubes (CNT)
nonequilibrium processes of ionization, polarization, surface diffusion and
desorption of atoms are considered self-consistently. The approach is based on
Zubarev's method of nonequilibrium statistical operator and reaction-diffusion
theory. The set of nonlinear transport equations are obtained for the chosen
parameters of description: the average numbers of adsorbed atoms, ionized and
polarized atoms in the electromagnetic field of CNT, and the average number of
atoms desorbed from the CNT surface. Ab initio simulations are conducted for a
"gas-single wall carbon nanotube" system for gases of particular practical
interest: He and NO. The obtained values of adsorption energy reveal preferable
localization sites of absorbed He atoms as well as their dependency on
adsorption distances. A significant effect of NO adsorption on CNT electronic
properties is demonstrated. The effect of presence of vacancies on adsorption
nature is analyzed. It is shown that under the influence of vacancy formation
the CNT structure undergoes reconstruction that enables chemisorption of NO
molecules.Comment: 12 pages, 4 figure
Chronic Fatigue Syndrome in Medical Students
The term "burnout syndrome" was first used in 1974 by the American psychiatrist
H.J. Freundenberger, who drew attention to this phenomenon in psychiatric workers and
described it as "defeat, exhaustion or wear and tear that happens to a person as a result
of sharply overestimated requirements for their own resources and forces" [5].
If a medical student during his studies does not feel his personal connection with
professional activity, he does not see intrinsic value, can not really give himself to it,
then inevitably there is internal devastation, because there is no dialogic exchange in
which a person not only gives, but also receives. As a result, the disorder becomes
depressive
Statistical description of electrodiffusion processes in the electron subsystem of a semibounded metal within the generalized jellium model
Based on the calculation of the quasiequilibrium statistical sum by means of
the functional integration method, we obtained a nonequilibrium statistical
operator for the electron subsystem of a semibounded metal in the framework of
the generalized jellium model in the Gaussian and higher approximations with
respect to the dynamic electron correlations. This approach allows one to go
beyond the linear approximation with respect to the gradient of the
electrochemical potential corresponding to weakly nonequilibrium processes and
to obtain generalized transport equations that describe nonlinear processes.Comment: 13 page
Machine learning technique for morphological classification of galaxies at z<0.1 from the SDSS
Methods. We used different galaxy classification techniques: human labeling,
multi-photometry diagrams, Naive Bayes, Logistic Regression, Support Vector
Machine, Random Forest, k-Nearest Neighbors, and k-fold validation. Results. We
present results of a binary automated morphological classification of galaxies
conducted by human labeling, multiphotometry, and supervised Machine Learning
methods. We applied its to the sample of galaxies from the SDSS DR9 with
redshifts of 0.02 < z < 0.1 and absolute stellar magnitudes of 24m < Mr <
19.4m. To study the classifier, we used absolute magnitudes: Mu, Mg, Mr , Mi,
Mz, Mu-Mr , Mg-Mi, Mu-Mg, Mr-Mz, and inverse concentration index to the center
R50/R90. Using the Support vector machine classifier and the data on color
indices, absolute magnitudes, inverse concentration index of galaxies with
visual morphological types, we were able to classify 316 031 galaxies from the
SDSS DR9 with unknown morphological types. Conclusions. The methods of Support
Vector Machine and Random Forest with Scikit-learn machine learning in Python
provide the highest accuracy for the binary galaxy morphological
classification: 96.4% correctly classified (96.1% early E and 96.9% late L
types) and 95.5% correctly classified (96.7% early E and 92.8% late L types),
respectively. Applying the Support Vector Machine for the sample of 316 031
galaxies from the SDSS DR9 at z < 0.1, we found 141 211 E and 174 820 L types
among them.Comment: 10 pages, 5 figures. The presentation of these results was given
during the EWASS-2017, Symposium "Astroinformatics: From Big Data to
Understanding the Universe at Large". It is vailable through
\url{http://space.asu.cas.cz/~ewass17-soc/Presentations/S14/Dobrycheva_987.pdf
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