99 research outputs found
Дія амітриптиліну на біоелектричну активність гіпокампу на фоні розвитку довготривалого стресу
Dynamics of changes of capacities of gypocampus bioelectric activity in control rats, in animals under immobilization stress and in the long-term stressed rats, which was administrated by amitriptilinum, was analyzed. The dynamics of changes of the gypocampus bioelectric activity reflects features of reorganization of the brain adaptive mechanisms with the constant change of its functioning mode under conditions of the long-term stress development. Проаналізовано динаміку змін потужностей біоелектричної активності гіпокампу у тварин контрольної групи та за умов імобілізаційного стресу паралельно зі щурами, які на фоні розвитку стрес-реакції приймали амітриптилін. Динаміка змін біоелектричної активності гіпокампу відображає особливості перебудови пристосувальних механізмів мозку при стійкій зміні режиму його функціонування за умов розвитку довготривалого стресу.Проаналізовано динаміку змін потужностей біоелектричної активності гіпокампу у тварин контрольної групи та за умов імобілізаційного стресу паралельно зі щурами, які на фоні розвитку стрес-реакції приймали амітриптилін. Динаміка змін біоелектричної активності гіпокампу відображає особливості перебудови пристосувальних механізмів мозку при стійкій зміні режиму його функціонування за умов розвитку довготривалого стресу
Вплив карбамазепіну на біоелектричну активність гіпоталамуса щурів за умов розвитку стрес-реакції
The influence of carbamazepine medication on bioelectric activity of the posterior and anterior hypothalamus in rats under stress conditions was studied. It is shown, that carbamazepine changes amplitude of the basic rhythms of electric activity of the hypothalamus posterior zone, which value were less compared with the capacities amplitude of the hypothalamic anterior zone.Досліджено вплив фармакологічного препарату карбамазепіну на біоелектричну активність заднього та переднього гіпоталамуса щурів за умов стресу. Показано, що карбамазепін змінює амплітуду основних ритмів електричної активності задньої зони гіпоталамуса, значення якої були меншими порівняно з амплітудою потужності передньої зони. Досліджено вплив фармакологічного препарату карбамазепіну на біоелектричну активність заднього та переднього гіпоталамуса щурів за умов стресу. Показано, що карбамазепін змінює амплітуду основних ритмів електричної активності задньої зони гіпоталамуса, значення якої були меншими порівняно з амплітудою потужності передньої зони
System size and energy dependence of near-side di-hadron correlations
Two-particle azimuthal () and pseudorapidity ()
correlations using a trigger particle with large transverse momentum () in
+Au, Cu+Cu and Au+Au collisions at =\xspace 62.4 GeV and
200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is
separated into a jet-like component, narrow in both and
, and the ridge, narrow in but broad in .
Both components are studied as a function of collision centrality, and the
jet-like correlation is studied as a function of the trigger and associated
. The behavior of the jet-like component is remarkably consistent for
different collision systems, suggesting it is produced by fragmentation. The
width of the jet-like correlation is found to increase with the system size.
The ridge, previously observed in Au+Au collisions at = 200
GeV, is also found in Cu+Cu collisions and in collisions at
=\xspace 62.4 GeV, but is found to be substantially smaller at
=\xspace 62.4 GeV than at = 200 GeV for the
same average number of participants ().
Measurements of the ridge are compared to models.Comment: 17 pages, 14 figures, submitted to Phys. Rev.
Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons
We report first results from an analysis based on a new multi-hadron
correlation technique, exploring jet-medium interactions and di-jet surface
emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons
are used for triggers to study associated hadron distributions. In contrast
with two- and three-particle correlations with a single trigger with similar
kinematic selections, the associated hadron distribution of both trigger sides
reveals no modification in either relative pseudo-rapidity or relative
azimuthal angle from d+Au to central Au+Au collisions. We determine associated
hadron yields and spectra as well as production rates for such correlated
back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure
Measurements of Dihadron Correlations Relative to the Event Plane in Au+Au Collisions at GeV
Dihadron azimuthal correlations containing a high transverse momentum (\pt)
trigger particle are sensitive to the properties of the nuclear medium created
at RHIC through the strong interactions occurring between the traversing parton
and the medium, i.e. jet-quenching. Previous measurements revealed a strong
modification to dihadron azimuthal correlations in Au+Au collisions with
respect to \pp\ and \dAu\ collisions. The modification increases with the
collision centrality, suggesting a path-length dependence to the jet-quenching
effect. This paper reports STAR measurements of dihadron azimuthal correlations
in mid-central (20-60\%) Au+Au collisions at \snn=200~GeV as a function of
the trigger particle's azimuthal angle relative to the event plane,
\phis=|\phit-\psiEP|. The azimuthal correlation is studied as a function of
both the trigger and associated particle \pt. The subtractions of the
combinatorial background and anisotropic flow, assuming Zero Yield At Minimum
(\zyam), are described. The away-side correlation is strongly modified, and the
modification varies with \phis, which is expected to be related to the
path-length that the away-side parton traverses. The pseudo-rapidity (\deta)
dependence of the near-side correlation, sensitive to long range \deta
correlations (the ridge), is also investigated. The ridge and jet-like
components of the near-side correlation are studied as a function of \phis.
The ridge appears to drop with increasing \phis while the jet-like component
remains approximately constant. ...Comment: 50 pages, 39 figures, 6 table
Observation of the antimatter helium-4 nucleus
High-energy nuclear collisions create an energy density similar to that of
the universe microseconds after the Big Bang, and in both cases, matter and
antimatter are formed with comparable abundance. However, the relatively
short-lived expansion in nuclear collisions allows antimatter to decouple
quickly from matter, and avoid annihilation. Thus, a high energy accelerator of
heavy nuclei is an efficient means of producing and studying antimatter. The
antimatter helium-4 nucleus (), also known as the anti-{\alpha}
(), consists of two antiprotons and two antineutrons (baryon
number B=-4). It has not been observed previously, although the {\alpha}
particle was identified a century ago by Rutherford and is present in cosmic
radiation at the 10% level. Antimatter nuclei with B < -1 have been observed
only as rare products of interactions at particle accelerators, where the rate
of antinucleus production in high-energy collisions decreases by about 1000
with each additional antinucleon. We present the observation of the antimatter
helium-4 nucleus, the heaviest observed antinucleus. In total 18
counts were detected at the STAR experiment at RHIC in 10 recorded Au+Au
collisions at center-of-mass energies of 200 GeV and 62 GeV per nucleon-nucleon
pair. The yield is consistent with expectations from thermodynamic and
coalescent nucleosynthesis models, which has implications beyond nuclear
physics.Comment: 19 pages, 4 figures. Submitted to Nature. Under media embarg
Strangeness Enhancement in Cu+Cu and Au+Au Collisions at \sqrt{s_{NN}} = 200 GeV
We report new STAR measurements of mid-rapidity yields for the ,
, , , , ,
particles in Cu+Cu collisions at \sNN{200}, and mid-rapidity
yields for the , , particles in Au+Au at
\sNN{200}. We show that at a given number of participating nucleons, the
production of strange hadrons is higher in Cu+Cu collisions than in Au+Au
collisions at the same center-of-mass energy. We find that aspects of the
enhancement factors for all particles can be described by a parameterization
based on the fraction of participants that undergo multiple collisions
Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at GeV
We report transverse momentum ( GeV/) spectra of , , , ,
, and at mid-rapidity in p+p and Au+Au collisions at
= 200 GeV. Perturbative QCD calculations are consistent with
spectra in p+p collisions but do not reproduce and
spectra. The observed decreasing antiparticle-to-particle ratios with
increasing provide experimental evidence for varying quark and gluon jet
contributions to high- hadron yields. The relative hadron abundances in
Au+Au at GeV/ are measured to be similar to the p+p
results, despite the expected Casimir effect for parton energy loss.Comment: 6 pages, 3 figures, published at PR
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