646 research outputs found
Effects of the tensor force on the ground and first states of the magic Ca nucleus
The magic nature of the Ca nucleus is investigated in the light of the
recent experimental results. We employ both HFB and HF+BCS methods using
Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the
single-particle spectra is studied for the N=34 isotones: Fe, Cr,
Ti and Ca. An increase is obtained in the neutron spin-orbit
splittings of and states due to the effect of the tensor force which
also makes Ca a magic nucleus candidate. QRPA calculations on top of
HF+BCS are performed to investigate the first = states of the
calcium isotopic chain. A good agreement for excitation energies is obtained
when we include the tensor force in the mean-field part of the calculations.
The first states indicate a subshell closure for both Ca and
Ca nuclei. We confirm that the tensor part of the interaction is quite
essential in explaining the neutron subshell closure in Ca and Ca
nuclei.Comment: 8 pages, 3 figure
An Empirical Study on the Efficiency of Performance Appraisal System in Oil and Natural Gas Commission (ONGC), India
The study provides a crisp and comprehensive picture of the objectives with which the Indian organizations apply systems to appraise their employees,the basis the companies use to appraise their employees and the reasons for which the companies have attempted to adopt new systems of performance appraisal. Further the study works upon empirical data pertaining to the above system with special reference to Oil and Natural Gas Commission (ONGC), India. Also, certain suggestive schemes which this state statutory body has come up to overcome the limitations of the existing system and survive in the dynamic environment, have been mentioned
TeV Gamma Rays from Geminga and the Origin of the GeV Positron Excess
The Geminga pulsar has long been one of the most intriguing MeV-GeV gamma-ray
point sources. We examine the implications of the recent Milagro detection of
extended, multi-TeV gamma-ray emission from Geminga, finding that this reveals
the existence of an ancient, powerful cosmic-ray accelerator that can plausibly
account for the multi-GeV positron excess that has evaded explanation. We
explore a number of testable predictions for gamma-ray and electron/positron
experiments (up to ~100 TeV) that can confirm the first "direct" detection of a
cosmic-ray source.Comment: 4 pages and 3 figures; Minor revisions, accepted for publication in
Physical Review Letter
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Molecular Aging of Triosephosphate Isomerase
This work was initiated to acquire a better understanding of the mechanisms, regulations, and significances of deamidation, as well as its role in the aging process
An Unexpectedly Swift Rise in the Gamma-ray Burst Rate
The association of long gamma-ray bursts with supernovae naturally suggests
that the cosmic GRB rate should trace the star formation history. Finding
otherwise would provide important clues concerning these rare, curious
phenomena. Using a new estimate of Swift GRB energetics to construct a sample
of 36 luminous GRBs with redshifts in the range z=0-4, we find evidence of
enhanced evolution in the GRB rate, with ~4 times as many GRBs observed at z~4
than expected from star formation measurements. This direct and empirical
demonstration of needed additional evolution is a new result. It is consistent
with theoretical expectations from metallicity effects, but other causes remain
possible, and we consider them systematically.Comment: 4 pages, 4 figures; minor changes to agree with published versio
Effects of intrathecal bupivacaine and bupivacaine plus sufentanil in elderly patients undergoing transurethral resection
Introduction: The present study compared the effect of bupivacaine and bupivacaine + sufentanil on hemodynamic parameters and characteristics of spinal anesthesia in elderly patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia.Technical Considerations: The study included 40 American Society of Anesthesiologists (ASA) I‑III patients scheduled to undergo TURP. Patients were blindly and randomly divided into two groups. Group B (n = 20) received 10 mg of intrathecal bupivacaine and group BS (n = 20) received 7.5 mg of bupivacaine + 5 μg of sufentanil. Sensory and motor block characteristics, hemodynamic changes, side effects, and time to first analgesic requirement were recorded. No differences in mean arterial pressure or heart rate, time for sensory blockade to reach the T10 level, and maximum sensory level were observed between the two groups. The time to first analgesic request was longer in group BS (P < 0.05). Motor block was significantly higher in group B (P < 0.05). In terms of side effects, no statistically significant differences occurred between the groups.Conclusions: Similar hemodynamic stability and sufficient level of sensory blockade were provided by bupivacaine and bupivacaine + sufentanil used for spinal anesthesia in patients undergoing TUR. Due to the fact that less motor block was observed and the time to first analgesic request was longer, the combination of bupivacaine + sufentanil might be appropriate for patients undergoing TUR.Key words: Bupivacaine, intrathecal, opioid, spinal, sufentani
Dynamic phase transition properties and hysteretic behavior of a ferrimagnetic core-shell nanoparticle in the presence of a time dependent magnetic field
We have presented dynamic phase transition features and stationary-state
behavior of a ferrimagnetic small nanoparticle system with a core-shell
structure. By means of detailed Monte Carlo simulations, a complete picture of
the phase diagrams and magnetization profiles have been presented and the
conditions for the occurrence of a compensation point in the system
have been investigated. According to N\'{e}el nomenclature, the magnetization
curves of the particle have been found to obey P-type, N-type and Q-type
classification schemes under certain conditions. Much effort has been devoted
to investigation of hysteretic response of the particle and we observed the
existence of triple hysteresis loop behavior which originates from the
existence of a weak ferromagnetic core coupling , as well as a
strong antiferromagnetic interface exchange interaction . Most
of the calculations have been performed for a particle in the presence of
oscillating fields of very high frequencies and high amplitudes in comparison
with exchange interactions which resembles a magnetic system under the
influence of ultrafast switching fields. Particular attention has also been
paid on the influence of the particle size on the thermal and magnetic
properties, as well as magnetic features such as coercivity, remanence and
compensation temperature of the particle. We have found that in the presence of
ultrafast switching fields, the particle may exhibit a dynamic phase transition
from paramagnetic to a dynamically ordered phase with increasing ferromagnetic
shell thickness.Comment: 12 pages, 12 figure
Constraints on Neutrino Parameters from Neutral-Current Solar Neutrino Measurements
We generalize the pull approach to define the function to the
analysis of the data with correlated statistical errors. We apply this method
to the analysis of the Sudbury Neutrino Collaboration data obtained in the
salt-phase. In the global analysis of all the solar neutrino and KamLAND data
we find the best fit (minimum ) values of neutrino parameters to be
and
eV. We confirm that the maximal mixing is strongly disfavored while the
bounds on are significantly strengthened.Comment: 6 figures. Some typos are corrected, figures are visually improve
Revisiting the Cosmic Star Formation History: Caution on the Uncertainties in Dust Correction and Star Formation Rate Conversion
The cosmic star formation rate density (CSFRD) has been observationally
investigated out to redshift z~10. However, most of theoretical models for
galaxy formation underpredict the CSFRD at z>1. Since the theoretical models
reproduce the observed luminosity functions (LFs), luminosity densities (LDs),
and stellar mass density at each redshift, this inconsistency does not simply
imply that theoretical models should incorporate some missing unknown physical
processes in galaxy formation. Here, we examine the cause of this inconsistency
in UV wavelengths by using a mock catalog of galaxies generated by a
semi-analytic model of galaxy formation. We find that this inconsistency is due
to two observational uncertainties: dust obscuration correction and conversion
from UV luminosity to star formation rate (SFR). The methods for correction of
obscuration and SFR conversion used in observational studies result in the
overestimation of CSFRD by ~ 0.1-0.3 dex and ~ 0.1-0.2 dex, respectively,
compared to the results obtained directly from our mock catalog. We present new
empirical calibrations for dust attenuation and conversion from observed UV LFs
and LDs into CSFRD.Comment: 12 pages including 11 figures. matches the published version (ApJ
2013 Jan. 20 issue
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