137 research outputs found
Astrophysical and Astrobiological Implications of Gamma-Ray Burst Properties
Combining results for the local cosmic rate and mean peak luminosity of GRBs
with the cosmic history of the star formation rate, we provide estimates for
the local GRB rate per unit blue luminosity in galaxies. We find a typical GRB
rate per unit B luminosity of 2.4x10^-17 h_{70}^2/Lsun/yr. The corresponding
mean rate in the Milky Way is 5.5x10^-7 h_{70}^2/yr. We conclude: 1) the ratio
of supernova rate to isotropic equivalent GRB rate is large: more than 6000
SNIbc per GRB or 30,000 SNII per GRB. GRBs could arise in a large fraction of
black hole-forming events only with collimation in the range 0.01 - 0.001 and a
steep enough slope of the IMF; 2) GRBs cannot account for the majority of large
HI holes observed in galaxies; 3) the probability that the solar system was
exposed to a fluence large enough to melt the chondrules during the first 10^7
yr of solar system history is negligibly small; 4) Even for very opaque
atmospheres, a significant fraction of the GRB energy is transmitted as UV
lines due to excitation by secondary electrons. For eukaryotic-like organisms
in thin atmospheres (e.g. contemporary Mars), or for UV line exposure in thick
atmospheres (e.g. Earth), biologically significant events occur at a rate of
about 100--500 /Gyr. The direct contribution of these "jolts" to mutational
evolution may, however, be negligible because of the short duration of the
GRBs. Evolutionary effects due to partial sterilizations and to longer-lived
disruptions of atmospheric chemistry should be more important. (Abridged)Comment: 36 pages, no figures Accepted by Astrophysical Journal Oct. 2001.
First submitted December,1999. Substantially rewritten discussion of burst
source count distributions and of biological implication
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
Early echocardiographic alterations in cancer patients during chemotherapy
Aim. To evaluate the early manifestation of cardiotoxicity after the first course of multiagent chemotherapy (MAC) using echocardiography with an assessment of the left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS).Material and methods. The study included 49 cancer patients with elective MAC.Results. After the first administration of a therapeutic dose of chemotherapy, a decrease in LVEF ≥10 and GLS >15 was demonstrated in more than 6,1% of patients, as well as a subclinical decrease in LVEF ≥5% in 22,4% and a decrease in GLS ≥12% in 24,5%.Conclusion. In cancer patients, after the first course of chemotherapy, GLS dynamics should be assessed during echocardiography as a marker of myocardial dysfunction
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
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
The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines
The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of
kton liquid double phase TPC complemented by a magnetised iron
calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km
from CERN. The conventional neutrino beam is produced by 400 GeV protons
accelerated at the SPS accelerator delivering 700 kW of power. The long
baseline provides a unique opportunity to study neutrino flavour oscillations
over their 1st and 2nd oscillation maxima exploring the behaviour, and
distinguishing effects arising from and matter. In this paper we
show how this comprehensive physics case can be further enhanced and
complemented if a neutrino beam produced at the Protvino IHEP accelerator
complex, at a distance of 1160 km, and with modest power of 450 kW is aimed
towards the same far detectors. We show that the coupling of two independent
sub-MW conventional neutrino and antineutrino beams at different baselines from
CERN and Protvino will allow to measure CP violation in the leptonic sector at
a confidence level of at least for 50\% of the true values of
with a 20 kton detector. With a far detector of 70 kton, the
combination allows a sensitivity for 75\% of the true values of
after 10 years of running. Running two independent neutrino
beams, each at a power below 1 MW, is more within today's state of the art than
the long-term operation of a new single high-energy multi-MW facility, which
has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 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
Возможности портативного регистратора электрокардиограммы и пульсовой волны в выявлении систолической дисфункции левого желудочка
Highlights. The article presents a novel and unique method for assessment of left ventricular systolic disfunction using electrocardiography and photoplethysmography data. This method will improve and simplify the detection of cardiovascular diseases.Aim. To evaluate left ventricular (LV) systolic function using electrocardiogram (ECG) and photoplethysmogram (PPG) signals recorded by a single-channel ECG and PPG-based monitor.Methods. The prospective study included 489 patients over 18 years old with various cardiovascular diseases. All participants underwent echocardiography to determine the main indicators of LV systolic function: LV ejection fraction (EF), LV outflow tract velocity time integral (LVOT VTI), and global longitudinal strain (GLS). Moreover, all patients underwent 1-lead ECG and PPG recording using a single-channel ECG and PPG-based monitor (CardioQvark). The obtained data were analyzed, and ROC curve analysis was performed.Results. We have identified ECG and PPG parameters associated with a decrease in LV contractile function. During the analysis, the ECG, T-wave amplitude (TA) and RonsF parameters showed the highest diagnostic accuracy. With EF below 55%, the area under the ROC curve (AUC) was 0.822, sensitivity (Se) 80%, specificity (Sp) 69% in EF below 55% in TA; in RonsF AUC was 0.743, Se 81%, Sp 77%. With EF below 40%, AUC was 0.915, Se 85%, Sp 83% in TA, and in RonsF AUC was 0.844, Se 82%, Sp 82%. Diagnostic accuracy of ECG signals in case of LVOT VTI lower than 16 cm was measured: TA (AUC 0.755, Se 82%, Sp 70%), RonsF (AUC 0.620, Se 77%, Sp 72%). PPG signals were not significantly associated with reduced EF; however, the pulse wave parameters were associated with lower LVOT VTI: in DP-B0 AUC was 0.687, Se 71%, Sp 74%. The combination of ECG and PPG signals was significantly associated with EF below 40% (RonsF * DP-SEP (AUC 0.877, Se 86%, Sp 85%). ECG and PPG signals were not associated with LV GLS.Conclusion. Assessment of LV systolic function can be performed by analyzing ECG and PPG signals recorded using a portable single-channel CardioQvark monitor.Основные положения. Описана возможность диагностики снижения систолической функции левого желудочка по данным электро- и фотоплетизмограммы. Разработка метода оценки систолической функции левого желудочка на основе электро- и фотоплетизмограммы позволит улучшить и упростить выявление сердечно-сосудистых заболеваний. Метод оценки систолической функции сердца, изложенный в исследовании, представлен впервые и является уникальным.Цель. Оценка систолической функции левого желудочка (ЛЖ) на основе параметров электро- (ЭКГ) и фотоплетизмограммы (ФПГ), зарегистрированных одноканальным монитором ЭКГ с функцией фотоплетизмографии.Материалы и методы. В проспективное исследование включено 489 пациентов в возрасте старше 18 лет, имеющих заболевания сердечно-сосудистой системы. Всем участникам исследования выполнена эхокардиография с определением основных показателей систолической функции ЛЖ: фракции выброса (ФВ) ЛЖ, интеграла линейной скорости кровотока в выносящем тракте ЛЖ (VTI в ВТЛЖ), глобальной деформации ЛЖ (GLS). Также всем больным проведена регистрация ЭКГ в I отведении и ФПГ с использованием монитора ЭКГ с функцией фотоплетизмографии (CardioQVARK). Проведены расчет всех полученных параметров, затем ROC-анализ данных.Результаты. Выявлены параметры ЭКГ и ФПГ, ассоциированные со снижением сократительной функции ЛЖ. При анализе ЭКГ параметры TA (амплитуда T-волны) и RonsF (частота максимальной энергии переднего фронта R-волны) имели наибольшую диагностическую точность. При ФВ менее 55% для TA площадь под ROC-кривой (AUC) составила 0,822, чувствительность (Se) 80%, специфичность (Sp) 69%, а для параметра RonsF – AUC 0,743, Se 81%, Sp 77%. При ФВ менее 40%: AUC для TA составила 0,915, Se 85%, Sp 83%, для RonsF – AUC 0,844, Se 82%, Sp 82%. Диагностическая точность параметров ЭКГ при снижении VTI в ВТЛЖ менее 16 см: TA (AUC 0,755, Se 82%, Sp 70%), RonsF (AUC 0,620, Se 77%, Sp 72%). При оценке параметров ФПГ достоверной взаимосвязи со снижением ФВ не выявлено, однако параметры пульсовой волны ассоциированы с уменьшением VTI в ВТЛЖ: для DP-B0 AUC 0,687, Se 71%, Sp 74%. Комбинации параметров ЭКГ и ФПГ достоверно взаимосвязаны со значением ФВ менее 40% (RonsF*DP-SEP (AUC 0,877, Se 86%, Sp 85%)). Взаимосвязи параметров ЭКГ и ФПГ со значением GLS ЛЖ не обнаружено.Заключение. Определение систолической функции ЛЖ возможно при анализе параметров ЭКГ и ФПГ, зарегистрированных с помощью портативного одноканального монитора CardioQVARK
Pion interferometry in Au+Au collisions at = 200 GeV
We present a systematic analysis of two-pion interferometry in Au+Au
collisions at = 200 GeV using the STAR detector at RHIC. We
extract the HBT radii and study their multiplicity, transverse momentum, and
azimuthal angle dependence. The Gaussianess of the correlation function is
studied. Estimates of the geometrical and dynamical structure of the freeze-out
source are extracted by fits with blast wave parameterizations. The expansion
of the source and its relation with the initial energy density distribution is
studied.Comment: 21 pages, 30 figures. As published in Physics Review
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