496 research outputs found
The power distribution of the eeg rhythm in verbal and spatial solving problems
The work is devoted to the study of the electrical activity of the cerebral cortex in students during verbal, image and spatial cognitive tasks. 35 students (17 men and 18 women) aged 18 to 25 years participated in the experiment. Three types of tasks were presented during the experiment. EEG was recorded while solving tasks. EEG spectral power in the implementation of various types of cognitive activity was analyzed. Multiple zonal differences of theta and alpha1 power were found between different cognitive states, including background with open eyes.Работа посвящена исследованию электрической активности коры головного мозга у студентов при решении вербальных, образных и пространственных задач. В эксперименте приняли участие 35 студентов вузов в возрасте от 18 до 25 лет. Испытуемым предъявлялись три типа задач, во время решения которых регистрировалась ЭЭГ. Проведен анализ спектральной мощности ЭЭГ при осуществлении различных типов когнитивной деятельности. Выявлены множественные зональные различия мощностей тета-ритма и альфа1-ритма между разными когнитивными состояниями, включая фоновое с открытыми глазами
The K^- \alpha scattering length and the reaction dd \to \alpha K^+ K^-
We present predictions for the the K^- \alpha scattering length obtained
within the framework of the multiple scattering approach. Evaluating the pole
position of the K^- \alpha scattering amplitude within the zero range
approximation, we find a loosely bound K^- \alpha state with a binding energy
of E_R = -2 ... -7 MeV and a width \Gamma_R = 11 ... 18 MeV. We propose to
measure the K^- \alpha scattering length through the final state interaction
between the \alpha and K^- meson produced in the reaction dd \to \alpha K^+
K^-. It is found that the K^-\alpha invariant mass distribution from this
reaction at energies near the threshold provides a new tool to determine the
s-wave K^- \alpha scattering length.Comment: 6 pages, 3 PS figure
Behaviour of the Blazar CTA 102 during two giant outbursts
Blazar CTA 102 underwent exceptional optical and high-energy outbursts in 2012 and 2016-2017. We analyze its behaviour during these events, focusing on polarimetry as a tool that allows us to trace changes in the physical conditions and geometric configuration of the emission source close to the central black hole. We also use Fermi gamma-ray data in conjunction with optical photometry in an effort to localize the origin of the outbursts.AST-1615796 - Boston Universit
Near-threshold production of -mesons in and NN collisions and -mixing
We consider near-threshold -meson production in and
collisions. An effective Lagrangian approach with one-pion exchange is applied
to analyze different contributions to the cross section for different isospin
channels. The Reggeon exchange mechanism is also evaluated for comparison. The
results from reactions are used to calculate the contribution of the
meson to the cross sections and invariant mass distributions
of the reactions and . It is found that
the experimental observation of mesons in the reaction is much more promising than the observation of mesons in
the reaction . Effects of isospin violation in the reactions
, , and , which are induced by -- mixing, are also analyzed.Comment: 43 pages, including 16 eps figures, to be bublished in Phys. Atom.
Nucl. (Yad. Fiz.) vol. 65, No. 11 (2002
Aspects of a0-f0 mixing in the reaction pn->da0
Some aspects of a0-f0 mixing effects in the reaction
with perpendicular polarized proton beam are discussed. An angular--asymmetry
parameter is defined to study those effects. It is shown that, for energies
close to the production threshold, the angular--asymmetry parameter is proportional to the a0-f0 mixing amplitude for arbitrary polar and
azimuthal angles and of the outgoing meson. This
statement is also valid for arbitrary energies, but then only at polar angles
and . The mass dependence of the differential cross
section in the reaction in the
presence of \mix mixing is also discussed.Comment: 17 pages, 3 Figure
Indication of asymptotic scaling in the reactions H, He and
It is shown that the differential cross sections of the reactions and measured at c.m.s.scattering angle
in the interval of the deuteron beam energy 0.5 - 1.2 GeV demonstrate the
scaling behaviour,, which follows from constituent
quark counting rules. It is found also that the differential cross section of
the elastic scattering at follows
the scaling regime at beam energies 0.5 - 5 GeV. These data are
parameterized here using the Reggeon exchange.Comment: 6 pages, Latex, 2 eps figures; final version accepted by Pis'ma v
ZHETF, corrected and completed reference
Production of -mesons in pp and pn reactions
We investigate the cross section for the reaction near
threshold and at medium energies. An effective Lagrangian approach with
one-pion exchange is applied to analyze different contributions to the cross
section for different isospin channels. The Reggeon exchange mechanism is also
considered. The results are used to calculate the contribution of the
meson to the cross sections and invariant mass distributions of the
reactions and . It is found that the
experimental observation of mesons in the reaction is much more promising than the observation of mesons in the
reaction .Comment: 26 pages, including 11 eps figures, to be bublished in J. Phys.
A multi-wavelength polarimetric study of the blazar CTA 102 during a Gamma-ray flare in 2012
We perform a multi-wavelength polarimetric study of the quasar CTA 102 during
an extraordinarily bright -ray outburst detected by the {\it Fermi}
Large Area Telescope in September-October 2012 when the source reached a flux
of F photons cm s.
At the same time the source displayed an unprecedented optical and NIR
outburst. We study the evolution of the parsec scale jet with ultra-high
angular resolution through a sequence of 80 total and polarized intensity Very
Long Baseline Array images at 43 GHz, covering the observing period from June
2007 to June 2014. We find that the -ray outburst is coincident with
flares at all the other frequencies and is related to the passage of a new
superluminal knot through the radio core. The powerful -ray emission is
associated with a change in direction of the jet, which became oriented more
closely to our line of sight (1.2) during the ejection of
the knot and the -ray outburst. During the flare, the optical polarized
emission displays intra-day variability and a clear clockwise rotation of
EVPAs, which we associate with the path followed by the knot as it moves along
helical magnetic field lines, although a random walk of the EVPA caused by a
turbulent magnetic field cannot be ruled out. We locate the -ray
outburst a short distance downstream of the radio core, parsecs from the black
hole. This suggests that synchrotron self-Compton scattering of near-infrared
to ultraviolet photons is the probable mechanism for the -ray
production.Comment: Accepted for publication in The Astrophysical Journa
KKbar photoproduction from protons
We study the contribution of the Drell mechanism driven by K^+ and K^-
exchange to the reaction gamma N -> KKbar N. Our calculation implements the
full KN and KbarN reaction amplitudes in the form of partial wave amplitudes
taken from a meson-exchange model (KN) and a partial wave analysis (KbarN),
respectively. Comparing our results to data of the LAMP2 collaboration we
observe that the Drell mechanism alone cannot describe the large Lambda(1520)
photoproduction rate observed experimentally. We argue that the discrepancy
could be due to significant contributions from K*-meson exchange with
subsequent excitation of the Lambda(1520) resonance. After adding such
contributions to our model a good agreement of the LAMP2 experiment is
achieved. When applying the same model to the recent SAPHIR data we find an
excellent description of the K^+p spectrum and can determine the parameters of
the Lambda(1600) P01 resonance, M_R = 1617 +/- 2 MeV and Gamma_R = 117 +/- 4
MeV, from the K^-p mass distribution.Comment: updated version, analysis of new CLAS data included, 11 pages, 11
figure
Special approach to the analysis and evaluation of the composition of red blood in athletes (on the example of rowing and canoeing)
The results of the analysis of red blood parameters in professional rowers showed that they have different mechanisms for the development of pre- and anemic conditions. This makes it necessary in each specific case to determine the prevailing of them, which requires an expansion of the set of recorded parameters
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