305 research outputs found
The High E_T Drop of J/psi to Drell-Yan Ratio from the Statistical c anti-c Coalescence Model
The dependence of the J/psi yield on the transverse energy E_T in heavy ion
collisions is considered within the statistical c anti-c coalescence model. The
model fits the NA50 data for Pb+Pb collisions at the CERN SPS even in the
high-E_T region (E_T > 100 GeV). Here E_T-fluctuations and E_T-losses in the
dimuon event sample naturally create the celebrated drop in the J/psi to
Drell-Yan ratio.Comment: 14 pages, REVTeX, 1 PS-figure. v2: References are corrected and
update
Van der Waals Excluded Volume Model of Multicomponent Hadron Gas
A generalization of the Van der Waals excluded volume procedure for the
multicomponent hadron gas is proposed. The derivation is based on the grand
canonical partition function for the system of particles of several species
interacting by hard core potentials. The obtained formulae for thermodynamical
quantities are consistent with underlying principles of statistical mechanics
as well as with thermodynamical identities. The model can be applied to the
analysis of experimental data for particle number ratios in relativistic
nucleus-nucleus collisions.Comment: 8 page
Stability and Representation Dependence of the Quantum Skyrmion
A constructive realization of Skyrme's conjecture that an effective pion mass
``may arise as a self consistent quantal effect'' based on an ab initio quantum
treatment of the Skyrme model is presented. In this quantum mechanical Skyrme
model the spectrum of states with , which appears in the collective
quantization, terminates without any infinite tower of unphysical states. The
termination point depends on the model parameters and the dimension of the
SU(2) representation. Representations, in which the nucleon and
resonance are the only stable states, exist. The model is developed for both
irreducible and reducible representations of general dimension. States with
spin larger than 1/2 are shown to be deformed. The representation dependence of
the baryon observables is illustrated numerically.Comment: 19 pages, Late
Heavy flavor kinetics at the hadronization transition
We investigate the in-medium modification of the charmonium breakup processes
due to the Mott effect for light (pi, rho) and open-charm (D, D*)
quark-antiquark bound states at the chiral/deconfinement phase transition. The
Mott effect for the D-mesons effectively reduces the threshold for charmonium
breakup cross sections, which is suggested as an explanation of the anomalous
J/psi suppression phenomenon in the NA50 experiment. Further implications of
finite-temperature mesonic correlations for the hadronization of heavy flavors
in heavy-ion collisions are discussed.Comment: 4 pages, 2 figures, Contribution to SQM2001 Conference, submitted to
J. Phys.
Intellectual decline in patients with schizophrenia with comorbid type ii diabetes mellitus and alcoholism
Comorbid conditions in general psychopathological practice need equally research in the field of psychiatry and narcology, as well as the development of issues of social practice in relation to mental patients. There is an opinion that comorbid mental pathologies are even more common than “pure” forms of diseases. In most cases of comorbid conditions, the medical community increasingly encounters clinical situations where “classic” symptoms and syndromes are deformed, mutually intertwined and, superimposed on the actual social situation of the patient, acquire an “unreal fancy character”.Schizophrenia remains one of the most urgent problems at the stage of modern psychiatry formation. Up to date there are 1.1% of men and 1.9% of women in the general population of patients. Schizophrenic spectrum disorders are often combined with a number of chronic pathologies that increase the negative impact on the neuro-cognitive sphere of a person. One of the main problems of modern urbanized society is type II diabetes and alcoholism. By increasing the negative impact on a person’s cognitive abilities, they accelerate the process of disintegration of personality and its social functioning. The intellectual level of patients with those chronic diseases that require patients to actively and consciously participate in the treatment process and social functioning can significantly affect the patient’s ability to learn, independently manage the disease, establish a high level of compliance and, as a result, the effectiveness of therapy. An attentive study of the issue of the state of intelligence of patients with comorbid pathology will lead to an improvement in the patient’s social adaptation, a more careful attitude to their somatic health and reduce the risk of disability of the able-bodied population
Second Cluster Integral and Excluded Volume Effects for the Pion Gas
The quantum mechanical formula for Mayer's second cluster integral for the
gas of relativistic particles with hard-core interaction is derived. The proper
pion volume calculated with quantum mechanical formula is found to be an order
of magnitude larger than its classical evaluation.
The second cluster integral for the pion gas is calculated in quantum
mechanical approach with account for both attractive and hard-core repulsive
interactions. It is shown that, in the second cluster approximation, the
repulsive pion-pion-interactions as well as the finite width of resonances give
important but almost canceling contributions. In contrast, an appreciable
deviation from the ideal gas of pions and pion resonances is observed beyond
the second cluster approximation in the framework of the Van der Waals
excluded-volume model.Comment: 29 pages, Latex, 9 PS-figure
The Updated Zwicky Catalog (UZC)
The Zwicky Catalog of galaxies (ZC), with m_Zw<=15.5mag, has been the basis
for the Center for Astrophysics (CfA) redshift surveys. To date, analyses of
the ZC and redshift surveys based on it have relied on heterogeneous sets of
galaxy coordinates and redshifts. Here we correct some of the inadequacies of
previous catalogs by providing: (1) coordinates with <~2 arcsec errors for all
of the Nuzc catalog galaxies, (2) homogeneously estimated redshifts for the
majority (98%) of the data taken at the CfA (14,632 spectra), and (3) an
estimate of the remaining "blunder" rate for both the CfA redshifts and for
those compiled from the literature. For the reanalyzed CfA data we include a
calibrated, uniformly determined error and an indication of the presence of
emission lines in each spectrum. We provide redshifts for 7,257 galaxies in the
CfA2 redshift survey not previously published; for another 5,625 CfA redshifts
we list the remeasured or uniformly re-reduced value. Among our new
measurements, Nmul are members of UZC "multiplets" associated with the original
Zwicky catalog position in the coordinate range where the catalog is 98%
complete. These multiplets provide new candidates for examination of tidal
interactions among galaxies. All of the new redshifts correspond to UZC
galaxies with properties recorded in the CfA redshift compilation known as
ZCAT. About 1,000 of our new measurements were motivated either by inadequate
signal-to-noise in the original spectrum or by an ambiguous identification of
the galaxy associated with a ZCAT redshift. The redshift catalog we include
here is ~96% complete to m_Zw<=15.5, and ~98% complete (12,925 galaxies out of
a total of 13,150) for the RA(1950) ranges [20h--4h] and [8h--17h] and
DEC(1950) range [-2.5d--50d]. (abridged)Comment: 34 pp, 7 figs, PASP 1999, 111, 43
Lenticular galaxies with UV-rings
By using the public UV imaging data obtained by the GALEX (Galaxy Ultraviolet
Explorer) for nearby galaxies, we have compiled a list of lenticular galaxies
possessing ultraviolet rings - starforming regions tightly confined to
particular radial distances from galactic centers. We have studied large-scale
structure of these galaxies in the optical bands by using the data of the SDSS
(Sloan Digital Sky Survey): we have decomposed the galactic images into
large-scale disks and bulges, have measured the ring optical colours from the
residual images after subtracting model disks and bulges, and have compared the
sizes of the rings in the optical light and in the UV-band. The probable origin
of the outer starforming ring appearances in unbarred galaxies demonstrating
otherwise the regular structure and homogeneously old stellar population beyond
the rings is discussed.Comment: 9 pages plus one big colour figure in the Appendix; the slightly
expanded version of the paper accepted to Astronomy Letter
One-dimensional Model of a Gamma Klystron
A new scheme for amplification of coherent gamma rays is proposed. The key
elements are crystalline undulators - single crystals with periodically bent
crystallographic planes exposed to a high energy beam of charged particles
undergoing channeling inside the crystals. The scheme consists of two such
crystals separated by a vacuum gap. The beam passes the crystals successively.
The particles perform undulator motion inside the crystals following the
periodic shape of the crystallographic planes. Gamma rays passing the crystals
parallel to the beam get amplified due to interaction with the particles inside
the crystals. The term `gamma klystron' is proposed for the scheme because its
operational principles are similar to those of the optical klystron. A more
simple one-crystal scheme is considered as well for the sake of comparison. It
is shown that the gamma ray amplification in the klystron scheme can be reached
at considerably lower particle densities than in the one-crystal scheme,
provided that the gap between the crystals is sufficiently large.Comment: RevTeX4, 22 pages, 4 figure
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