2,087,702 research outputs found
Study of X-ray emission from the old open cluster, M67
We present an X-ray analysis of a 4 Gyr old open cluster, M67, using archival
XMM-Newton data. The aim of this study was to find new X-ray members of M67,
and to use the updated member list for studying X-ray variability, and derive
the X-ray luminosity functions (XLFs) of different stellar types and compare
them with other star clusters of similar age. We report the detection of X-ray
emission from 25 members of M67, with membership based primarily on their
proper motion, of which one X-ray source is a new member. Supplementing this
study with previous ROSAT and Chandra studies of M67, and using the most recent
proper motion study by Vereshchagin et al., we have compiled a revised list of
X-ray emitting members of M67 consisting of 43 stars. Sixteen of these are
known RS CVn type binaries having orbital periods 10 days, and
near-circular orbits, 5 are contact binaries with orbital periods 6 hours,
5 are yellow and blue stragglers, 2 are Algol-type binaries, and one source is
a cataclysmic variable. Fourteen members do not have any orbital information
and cannot be classified. Fourteen of the X-ray sources detected do not have
any optical counterpart down to a magnitude of , and their
membership is uncertain. Finally, we report the X-ray luminosity functions of
RS CVn type and other types of stars in M67 and compare them with other open
clusters of intermediate-to-old age.Comment: 13 pages, 8 figures, 5 tables. Accepted for publication in MNRA
Knowledge and Attitudes on Fetal Anomalies Among Pregnant Women in Teaching Hospital Mahamodara, Galle
Fetal anomalies significantly contribute towards neonatal mortality worldwide. In Sri Lanka major cause for neonatal deaths is fetal anomalies 41%. A Descriptive cross-sectional study was conducted in Antenatal clinic, Teaching Hospital, Mahamodara. An interviewer-administered, pretested questionnaire was used. Hundred and fifty pregnant women participated in this study. Majority; 105 (70%) were found in the age of below 30 years, and 80 (53.3%) educated up to G.C.E. Ordinary Level. 83 (53.3%) were multigravida and 93(62%) were planned pregnancies. Higher proportion of the participants; 92(61%) , 88(56.7%) and 123(82%) had good knowledge on the risk factors, pre conception care and on preventive actions related to birth defects respectively. Significant proportion (26.7%) had poor knowledge regarding birth defects. There are 143 (95.3%) of the participants interested to know more information on birth defects, 72% believed birth defects were due to evil spirits. Even though 52% of women did not want to terminate their pregnancy if they had a fetus with anomalies, 80.7% of them opined that the termination of pregnancy with birth defected should be legalized. The educational level, parity and planning of current pregnancy of the participants were significantly correlated (p < 0.05) with their knowledge on pre conception care, preventive actions, knowledge on risk factors on birth defects
Multiplicity fluctuations in heavy-ion collisions using canonical and grand-canonical ensemble
We report the higher order cumulants and their ratios for baryon, charge and
strangeness multiplicity in canonical and grand-canonical ensembles in ideal
thermal model including all the resonances. When the number of conserved quanta
is small, an explicit treatment of these conserved charges is required, which
leads to a canonical description of the system and the fluctuations are
significantly different from the grand canonical ensemble. Cumulant ratios of
total charge and net-charge multiplicity as a function of collision energies
are also compared in grand canonical ensemble.Comment: 7 pages, 5 Figs, Published versio
Linear and nonlinear properties of Rao-dust-Alfv\'en waves in magnetized plasmas
The linear and nonlinear properties of the Rao-dust-magnetohydrodynamic
(R-D-MHD) waves in a dusty magnetoplasma are studied. By employing the
inertialess electron equation of motion, inertial ion equation of motion,
Amp\`ere's law, Faraday's law, and the continuity equation in a plasma with
immobile charged dust grains, the linear and nonlinear propagation of
two-dimensional R-D-MHD waves are investigated. In the linear regime, the
existence of immobile dust grains produces the Rao cutoff frequency, which is
proportional to the dust charge density and the ion gyrofrequency. On the other
hand, the dynamics of an amplitude modulated R-D-MHD waves is governed by the
cubic nonlinear Schroedinger equation. The latter has been derived by using the
reductive perturbation technique and the two-timescale analysis which accounts
for the harmonic generation nonlinearity in plasmas. The stability of the
modulated wave envelope against non-resonant perturbations is studied. Finally,
the possibility of localized envelope excitations is discussed.Comment: 30 pages, 8 figures, to appear in Physics of Plasma
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