173 research outputs found
Deciphering nonfemtoscopic two-pion correlations in collisions with simple analytical models
A simple model of nonfemtoscopic particle correlations in proton-proton
collisions is proposed. The model takes into account correlations induced by
the conservation laws as well as correlations induced by minijets. It
reproduces well the two-pion nonfemtoscopic correlations of like-sign and
unlike-sign pions in proton-proton collision events at GeV
analyzed by the ALICE Collaboration. We also argue that similar nonfemtoscopic
correlations can appear in the hydrodynamic picture with event-by-event
fluctuating nonsymmetric initial conditions that are typically associated with
nonzero higher-order flow harmonics.Comment: 21 pages, 10 figures, misprints correcte
The KHOLOD Experiment: A Search for a New Population of Radio Sources
Published data from long-term observations of a strip of sky at declination
+5 degrees carried out at 7.6 cm on the RATAN-600 radio telescope are used to
estimate some statistical properties of radio sources. Limits on the
sensitivity of the survey due to noise imposed by background sources, which
dominates the radiometer sensitivity, are refined. The vast majority of noise
due to background sources is associated with known radio sources (for example,
from the NVSS with a detection threshold of 2.3 mJy) with normal steep spectra
({\alpha} = 0.7-0.8, S \propto {\nu}^{- \alpha}), which have also been detected
in new deep surveys at decimeter wavelengths. When all such objects are removed
from the observational data, this leaves another noise component that is
observed to be roughly identical in independent groups of observations. We
suggest this represents a new population of radio sources that are not present
in known catalogs at the 0.6 mJy level at 7.6 cm. The studied redshift
dependence of the number of steep-spectrum objects shows that the sensitivity
of our survey is sufficient to detect powerful FRII radio sources at any
redshift, right to the epoch of formation of the first galaxies. The inferred
new population is most likely associated with low-luminosity objects at
redshifts z < 1. In spite of the appearance of new means of carrying out direct
studies of distant galaxies, searches for objects with very high redshifts
among steep and ultra-steep spectrum radio sources remains an effective method
for studying the early Universe.Comment: 13 pages, 10 figure
Correlation search for coherent pion emission in heavy ion collisions
The methods allowing to extract the coherent component of pion emission
conditioned by the formation of a quasi-classical pion source in heavy ion
collisions are suggested. They exploit a nontrivial modification of the quantum
statistical and final state interaction effects on the correlation functions of
like and unlike pions in the presence of the coherent radiation. The extraction
of the coherent pion spectrum from pi+pi-, pi+pi+ and pi-pi- correlation
functions and single--pion spectra is discussed in detail for large expanding
systems produced in ultra-relativistic heavy ion collisions.Comment: 21 pages, 3 eps figures, ReVTeX, corrected submission abstract.
Version published in PRC 65 (2002) 064904. Added is a detailed explanation of
the differences between pure coherent states and charge constrained coherent
states in the case of a simple example model. The expressions for
two-particle spectra taking into account both the final state interaction and
the coherent component of pion emission are derived in a more general and
transparent wa
Suppression of surface barrier in superconductors by columnar defects
We investigate the influence of columnar defects in layered superconductors
on the thermally activated penetration of pancake vortices through the surface
barrier. Columnar defects, located near the surface, facilitate penetration of
vortices through the surface barrier, by creating ``weak spots'', through which
pancakes can penetrate into the superconductor. Penetration of a pancake
mediated by an isolated column, located near the surface, is a two-stage
process involving hopping from the surface to the column and the detachment
from the column into the bulk; each stage is controlled by its own activation
barrier. The resulting effective energy is equal to the maximum of those two
barriers. For a given external field there exists an optimum location of the
column for which the barriers for the both processes are equal and the
reduction of the effective penetration barrier is maximal. At high fields the
effective penetration field is approximately two times smaller than in
unirradiated samples. We also estimate the suppression of the effective
penetration field by column clusters. This mechanism provides further reduction
of the penetration field at low temperatures.Comment: 8 pages, 9 figures, submitted to Phys. Rev.
RC J0311+0507: A Candidate for Superpowerful Radio Galaxies in the Early Universe at Redshift z=4.514
A strong emission line at 6703A has been detected in the optical spectrum for
the host galaxy (R=23.1) of the radio source RC J0311+0507 (4C+04.11). This
radio galaxy, with a spectral index of 1.31 in the frequency range 365-4850
MHz, is one of the ultrasteep spectrum objects from the deep survey of a sky
strip conducted with RATAN-600 in 1980-1981. We present arguments in favor of
the identification of this line with Ly\alpha at redshift z=4.514. In this
case, the object belongs to the group of extremely distant radio galaxies of
ultrahigh radio luminosity (P_{1400}=1.3 x 10^{29}W Hz^{-1}). Such power can be
provided only by a fairly massive black hole (~10^9M_\sun}) that formed in a
time less than the age of the Universe at the observed z(1.3 Gyr) or had a
primordial origin.Comment: 8 pages, 3 figure
Impact of anxiety and depression disorders on adherence to anticoagulant therapy among patients with atrial fibrillation
Aim. To determine the possible impact of anxiety and depression disorders on the adherence of patients with atrial fibrillation (AF) to anticoagulant the rapy.Material and methods. The study included outpatients with AF of any type. After signing the informed consent, patients filled out questionnaires and scales that determined the level of anxiety and personal predisposition (MMAS-8, MMAS-4, SF-36, SHAI, STAI, HADS, NEO-FFI).Results. A total of 117 outpatients treated for AF were included. The mean age of patients was 74±5 years (men, 38%). Based on MMAS-4 and MMAS-8 results, adherent and non-adherent cohorts of patients were formed. Low adherence group had significantly higher situational anxiety according to STAI (45,9±9,9 vs 41,1±10,7, p=0,045) and depression according to HADS (7,9±3,6 vs 5,9±3,5, p=0,018). SF 36 showed that non-adherent patients had a lower general health (41,6±12,9 vs 52,2±20,0, p=0,01). Five-factor model revealed an association between low compliance and low extraversion (21,3±6,6 vs 26,4±7,2, p=0,002). Pharmacokinetic data on blood concentrations of anticoagulants or its metabolites at the second visit were available in 76 (67%) patients. Assessment of pharmacokinetic and compliance data revealed a moderate direct correlation (Matthews correlation coefficient (MCC), 0,345) and a weak direct correlation with the MMAS-8 (MCC, 0,177). The difference in MMAS-4 and MMAS-8 scores between high and low pharmacokinetic adherence groups was significant on both scales (p=0,011 and 0,015, respectively).Conclusion. The rationale for widespread introduction of standardized questionnaires and scales (MMAS 4, MMAS 8, STAI, HADS, SF 36, Big 5) was shown in order to early identify patients with low adherence to treatment. The results highlight the need for further study of the contribution of psychiatric disorders to low compliance to anticoagulant therapy
Catalog of Radio Galaxies with z>0.3. I:Construction of the Sample
The procedure of the construction of a sample of distant () radio
galaxies using NED, SDSS, and CATS databases for further application in
statistical tests is described. The sample is assumed to be cleaned from
objects with quasar properties. Primary statistical analysis of the list is
performed and the regression dependence of the spectral index on redshift is
found.Comment: 9 pages, 6 figures, 2 table
On the Spectral Index of Distant Radio Galaxies
The problems of using the spectral index of radio galaxies in various tests,
in particular, in selecting distant radio sources are considered. The history
of the question of choosing a criterion of searching for distant radio galaxies
based on the spectral index is presented. For a new catalog of 2442 radio
galaxies constructed from NED, SDSS, and CATS data, an analytical form of the
sp ectral index.redshift relation has been determined for the first time. The
spectral index.angular size and spectral index.flux density diagrams have also
been constructed. Peculiarities of the distribution of sources on these
diagrams are discussed.Comment: 7 pages,5 figure
The estimation of black-hole masses in distant radio galaxies
We have estimated the masses of the central supermassive black holes of 2442
radio galaxies froma catalog compiled using data from the NED, SDSS, and CATS
databases. Mass estimates based on optical photometry and radio data are
compared. Relationships between the mass of the central black hole
and the redshift are constructed for both wavelength ranges. The
distribution of the galaxies in these diagrams and systematic effects
influencing estimation of the black-hole parameters are discussed.
Upperenvelope cubic regression fits are obtained using the maximum estimates of
the black-hole masses. The optical and radio upper envelopes show similar
behavior, and have very similar peaks in position, , and
amplitude, = 9.4. This is consistent with a model in which the
growth of the supermassive black holes is self-regulating, with this redshift
corresponding to the epoch when the accretion-flow phase begins to end and the
nuclear activity falls off.Comment: 8 pages, 6 figure
Analysis of the RC catalog sample in the region overlapping with the regions of the FIRST and SDSS surveys: I. Identification of sources with the VLSS, TXS, NVSS, FIRST, and GB6 catalogs
Radio sources of the RC catalog produced in 1980--1985 at RATAN-600 radio
telescope based on a deep survey of a sky strip centered on the declination of
the SS 433 source are optically identified in the region overlapping with FIRST
and SDSS surveys (about 132 square degrees). The NVSS catalog was used as the
reference catalog for refining the coordinates of the radio sources. The
morphology is found for about 75% of the objects of the sample and the ratio of
single, double and multicomponent radio sources is computed based on FIRST
radio maps. The 74, 365, 1400, and 4850 MHz data of the VLSS, TXS, NVSS, FIRST,
and GB6 catalogs are used to analyze the shape of the spectra.Comment: 16 pages, 3 figure
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