313 research outputs found
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
Strong Upper Limits on Sterile Neutrino Warm Dark Matter
Sterile neutrinos are attractive dark matter candidates. Their parameter
space of mass and mixing angle has not yet been fully tested despite intensive
efforts that exploit their gravitational clustering properties and radiative
decays. We use the limits on gamma-ray line emission from the Galactic Center
region obtained with the SPI spectrometer on the INTEGRAL satellite to set new
constraints, which improve on the earlier bounds on mixing by more than two
orders of magnitude, and thus strongly restrict a wide and interesting range of
models.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in
Physical Review Letter
Stringent Constraint on Galactic Positron Production
The intense 0.511 MeV gamma-ray line emission from the Galactic Center
observed by INTEGRAL requires a large annihilation rate of nonrelativistic
positrons. If these positrons are injected at even mildly relativistic
energies, higher-energy gamma rays will also be produced. We calculate the
gamma-ray spectrum due to inflight annihilation and compare to the observed
diffuse Galactic gamma-ray data. Even in a simplified but conservative
treatment, we find that the positron injection energies must be
MeV, which strongly constrains models for Galactic positron production.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in PR
Neutrino physics from new SNO and KamLAND data and future prospects
We analyze the cumulative data from the latest SNO, KamLAND and other solar
neutrino experiments in the standard scenario of three oscillating active
neutrinos. We determine the solar neutrino oscillation parameters and obtain
new bounds on . We also place constraints on the fraction of
oscillating solar neutrinos that transform to sterile neutrinos with the B
flux normalization left free. Concomitantly, we assess the sensitivity of
future data from the SNO and KamLAND experiments to and to the
sterile neutrino content of the solar flux.Comment: 4 pages, 4 figures. Latest SNO salt-phase data and KamLAND data
included in analyse
Gamma-Ray Constraints on Maximum Cosmogenic Neutrino Fluxes and UHECR Source Evolution Models
The dip model assumes that the ultra-high energy cosmic rays (UHECRs) above
10 eV consist exclusively of protons and is consistent with the spectrum
and composition measure by HiRes. Here we present the range of cosmogenic
neutrino fluxes in the dip-model which are compatible with a recent
determination of the extragalactic very high energy (VHE) gamma-ray diffuse
background derived from 2.5 years of Fermi/LAT data. We show that the largest
fluxes predicted in the dip model would be detectable by IceCube in about 10
years of observation and are within the reach of a few years of observation
with the ARA project. In the incomplete UHECR model in which protons are
assumed to dominate only above 10 eV, the cosmogenic neutrino fluxes
could be a factor of 2 or 3 larger. Any fraction of heavier nuclei in the UHECR
at these energies would reduce the maximum cosmogenic neutrino fluxes. We also
consider here special evolution models in which the UHECR sources are assumed
to have the same evolution of either the star formation rate (SFR), or the
gamma-ray burst (GRB) rate, or the active galactic nuclei (AGN) rate in the
Universe and found that the last two are disfavored (and in the dip model
rejected) by the new VHE gamma-ray background.Comment: 19 pages, 16 figures, JHEP3.cls needed to typese
What is the association of acute renal failure, angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker in a young patient?
Neutrino Spectrum from SN 1987A and from Cosmic Supernovae
The detection of neutrinos from SN 1987A by the Kamiokande-II and
Irvine-Michigan-Brookhaven detectors provided the first glimpse of core
collapse in a supernova, complementing the optical observations and confirming
our basic understanding of the mechanism behind the explosion. One
long-standing puzzle is that, when fitted with thermal spectra, the two
independent detections do not seem to agree with either each other or typical
theoretical expectations. We assess the compatibility of the two data sets in a
model-independent way and show that they can be reconciled if one avoids any
bias on the neutrino spectrum stemming from theoretical conjecture. We
reconstruct the neutrino spectrum from SN 1987A directly from the data through
non-parametric inferential statistical methods and present predictions for the
Diffuse Supernova Neutrino Background based on SN 1987A data. We show that this
prediction cannot be too small (especially in the 10-18 MeV range), since the
majority of the detected events from SN 1987 were above 18 MeV (including 6
events above 35 MeV), suggesting an imminent detection in operational and
planned detectors.Comment: 9 pages, 4 figures; Matches version published in Phys. Rev.
Evolution in the Volumetric Type Ia Supernova Rate from the Supernova Legacy Survey
We present a measurement of the volumetric Type Ia supernova (SN Ia) rate
(SNR_Ia) as a function of redshift for the first four years of data from the
Canada-France-Hawaii Telescope (CFHT) Supernova Legacy Survey (SNLS). This
analysis includes 286 spectroscopically confirmed and more than 400 additional
photometrically identified SNe Ia within the redshift range 0.1<z<1.1. The
volumetric SNR_Ia evolution is consistent with a rise to z~1.0 that follows a
power-law of the form (1+z)^alpha, with alpha=2.11+/-0.28. This evolutionary
trend in the SNLS rates is slightly shallower than that of the cosmic
star-formation history over the same redshift range. We combine the SNLS rate
measurements with those from other surveys that complement the SNLS redshift
range, and fit various simple SN Ia delay-time distribution (DTD) models to the
combined data. A simple power-law model for the DTD (i.e., proportional to
t^-beta) yields values from beta=0.98+/-0.05 to beta=1.15+/-0.08 depending on
the parameterization of the cosmic star formation history. A two-component
model, where SNR_Ia is dependent on stellar mass (Mstellar) and star formation
rate (SFR) as SNR_Ia(z)=AxMstellar(z) + BxSFR(z), yields the coefficients
A=1.9+/-0.1 SNe/yr/M_solar and B=3.3+/-0.2 SNe/yr/(M_solar/yr). More general
two-component models also fit the data well, but single Gaussian or exponential
DTDs provide significantly poorer matches. Finally, we split the SNLS sample
into two populations by the light curve width (stretch), and show that the
general behavior in the rates of faster-declining SNe Ia (0.8<s<1.0) is
similar, within our measurement errors, to that of the slower objects
(1.0<s<1.3) out to z~0.8.Comment: Accepted in A
Searching for prompt signatures of nearby core-collapse supernovae by a joint analysis of neutrino and gravitational-wave data
We discuss the science motivations and prospects for a joint analysis of
gravitational-wave (GW) and low-energy neutrino data to search for prompt
signals from nearby supernovae (SNe). Both gravitational-wave and low-energy
neutrinos are expected to be produced in the innermost region of a
core-collapse supernova, and a search for coincident signals would probe the
processes which power a supernova explosion. It is estimated that the current
generation of neutrino and gravitational-wave detectors would be sensitive to
Galactic core-collapse supernovae, and would also be able to detect
electromagnetically dark SNe. A joint GW-neutrino search would enable
improvements to searches by way of lower detection thresholds, larger distance
range, better live-time coverage by a network of GW and neutrino detectors, and
increased significance of candidate detections. A close collaboration between
the GW and neutrino communities for such a search will thus go far toward
realizing a much sought-after astrophysics goal of detecting the next nearby
supernova.Comment: 10 pages, 3 figures. To appear in Class. Quantum Gra
- …