6,256 research outputs found
Fisheries Management: The Kuwaiti Experience
Siddeek et al. (1991) discussed very briefly some recent developments in Kuwait's shrimp fishery, including an important increase in landings of the main commercial species, Penaeus semisulcatus. This increase coincided with a marked fall in landings of the other important species, Metapenaeus affinis. They thought that these changes were caused by a reduction in effort combined with a more or less simultaneous favorable environmental change for P. semisulcatus and an unfavorable environmental change for M. affinis, but did not give any unequivocal evidence to support this conclusion. The results they reported are, nevertheless, very important and may be relevant to scientists and managers in other parts of the world
Stocking, Enhancement, and Mariculture of Penaeus orientalis and Other Species in Shanghai and Zhejiang Provinces, China
China's marine aquaculture landings provide only 18% of its combined freshwater and amrine capture and culture landings, at a per-capita consumption of only 3.2 kg/yr out of a total of 18.1 kg/yr. We described development and some of the results of long-term mariculture and stocking/enhancement projects that have been underway for up to 20 years in the Hangzhou Bay area. Penaeus orientalis (also referred to as P. chinensis) stocking provided up to 400 t/yr, at a total cost-benefit ratio of up to 8 Yuan of landed shrimp per Yuan invested in shrimp stocking. Over 40 t of Penaeus orientalis were produced commercially in 1993, with proceeds being used to fund mariculture and fisheries research. Large scale edible jellyfish restocking is also underway, while semicommercial culture of abalone, Haliotis diversicolor, has been successful. Technical problems limitig mariculture have been solved successfully for some species
Vector boson production in association with KK modes of the ADD model to NLO in QCD at LHC
Next-to-leading order QCD corrections to the associated production of vector
boson (Z/W) with the the Kaluza-Klein modes of the graviton in large extra
dimensional model at the LHC, are presented. We have obtained various kinematic
distributions using a Monte Carlo code which is based on the two cut off phase
space slicing method that handles soft and collinear singularities appearing at
NLO level. We estimate the impact of the QCD corrections on various observables
and find that they are significant. We also show the reduction in factorization
scale uncertainty when QCD corrections are included.Comment: 12 pages, 5 figure
Quantum oscillator and Kepler-Coulomb problems in curved spaces: deformed shape invariance, point canonical transformations, and rational extensions
The quantum oscillator and Kepler-Coulomb problems in -dimensional spaces
with constant curvature are analyzed from several viewpoints. In a deformed
supersymmetric framework, the corresponding nonlinear potentials are shown to
exhibit a deformed shape invariance property. By using the point canonical
transformation method, the two deformed Schr\"odinger equations are mapped onto
conventional ones corresponding to some shape-invariant potentials, whose
rational extensions are well known. The inverse point canonical transformations
then provide some rational extensions of the oscillator and Kepler-Coulomb
potentials in curved space. The oscillator on the sphere and the Kepler-Coulomb
potential in a hyperbolic space are studied in detail and their extensions are
proved to be consistent with already known ones in Euclidean space. The
partnership between nonextended and extended potentials is interpreted in a
deformed supersymmetric framework. Those extended potentials that are
isospectral to some nonextended ones are shown to display deformed shape
invariance, which in the Kepler-Coulomb case is enlarged by also translating
the degree of the polynomial arising in the rational part denominator.Comment: 32 pages, no figure; published versio
Spitzer Observations of Transient, Extended Dust in Two Elliptical Galaxies: New Evidence of Recent Feedback Energy Release in Galactic Cores
Spitzer observations of extended dust in two optically normal elliptical
galaxies provide a new confirmation of buoyant feedback outflow in the hot gas
atmospheres around these galaxies. AGN feedback energy is required to prevent
wholesale cooling and star formation in these group-centered galaxies. In NGC
5044 we observe interstellar (presumably PAH) emission at 8 microns out to
about 5 kpc. Both NGC 5044 and 4636 have extended 70 microns emission from cold
dust exceeding that expected from stellar mass loss. The sputtering lifetime of
this extended dust in the ~1keV interstellar gas, ~10^7 yrs, establishes the
time when the dust first entered the hot gas. Evidently the extended dust
originated in dusty disks or clouds, commonly observed in elliptical galaxy
cores, that were disrupted, heated and buoyantly transported outward. The
surviving central dust in NGC 5044 and 4636 has been disrupted into many small
filaments. It is remarkable that the asymmetrically extended 8 micron emission
in NGC 5044 is spatially coincident with Halpha+[NII] emission from warm gas. A
calculation shows that dust-assisted cooling in buoyant hot gas moving out from
the galactic core can cool within a few kpc in about ~10^7 yrs, explaining the
optical line emission observed. The X-ray images of both galaxies are
disturbed. All timescales for transient activity - restoration of equilibrium
and buoyant transport in the hot gas, dynamics of surviving dust fragments, and
dust sputtering - are consistent with a central release of feedback energy in
both galaxies about 10^7 yrs ago.Comment: 13 pages. Accepted by ApJ; minor typos correcte
NLO-QCD Corrections to Dilepton Production in the Randall-Sundrum Model
The dilepton production process at hadron colliders in the Randall-Sundrum
(RS) model is studied at next-to-leading order in QCD. The NLO-QCD corrections
have been computed for the virtual graviton exchange process in the RS model,
in addition to the usual gamma, Z-mediated processes of standard Drell-Yan.
K-factors for the cross-sections at the LHC and Tevatron for differential in
the invariant mass, Q, and the rapidity, Y, of the lepton pair are presented.
We find the K-factors are large over substantial regions of the phase space.Comment: 24 pages, 12 figure
Ashotgun marriage community health workers and government health services
In 1988 the Western Cape Regional Services Council (RSC) initiated a community health worker (CHW) project in Khayelitsha in order to extend its preventive services to people in the community and promote 'community upliftment'. An evaluation of this project was undertaken in 1991 and 1992 in order to examine the potential of this local health authority-run CHW project to be an appropriate primary health care model. Qualitative research methods were used to explore the nature of the work done by the CHWs, whether they were accepted in their communities, and whether the project functioned as part of an integrated health service infrastructure in Khayelitsha. The CHWs were found to provide the basis for a potentially effective, community-responsive service. However, several structural problems mitigated against this service. Relations between the CHWs and nurses in all the formal public health services in the area were superficial and fraught with problems. There were significant differences and conflicting policies between the RSC's CHW project and other neighbouring nongovernment CHW projects, and these posed various threats to both the RSC and the non-government projects. One of the most serious of these differences was that the RSC project had no structures or plans for community involvement in the running of the project. Before a CHW project is initiated, several critical issues need to be carefully considered and discussed with all the relevant stakeholders. Furthermore, CHWs need to be flexible, and accountable to the communities in which they work. Before employing CHWs, formal public health authorities need to consider carefully whether they are able to meet these criteria
DCO, DCN and ND reveal three different deuteration regimes in the disk around the Herbig Ae star HD163296
The formation pathways of deuterated species trace different regions of
protoplanetary disks and may shed light into their physical structure. We aim
to constrain the radial extent of main deuterated species; we are particularly
interested in spatially characterizing the high and low temperature pathways
for enhancing deuteration of these species. We observed the disk surrounding
the Herbig Ae star HD 163296 using ALMA in Band 6 and obtained resolved
spectral imaging data of DCO (=3-2), DCN (=3-2) and ND
(=3-2). We model the radial emission profiles of DCO, DCN and
ND, assuming their emission is optically thin, using a parametric model
of their abundances and radial excitation temperature estimates. DCO can be
described by a three-region model, with constant-abundance rings centered at 70
AU, 150 AU and 260 AU. The DCN radial profile peaks at about ~60 AU and
ND is seen in a ring at ~160 AU. Simple models of both molecules using
constant abundances reproduce the data. Assuming reasonable average excitation
temperatures for the whole disk, their disk-averaged column densities (and
deuterium fractionation ratios) are 1.6-2.6 cm
(0.04-0.07), 2.9-5.2 cm (0.02) and 1.6-2.5 cm (0.34-0.45) for DCO, DCN and ND, respectively.
Our simple best-fit models show a correlation between the radial location of
the first two rings in DCO and the DCN and ND abundance
distributions that can be interpreted as the high and low temperature
deuteration pathways regimes. The origin of the third DCO ring at 260 AU is
unknown but may be due to a local decrease of ultraviolet opacity allowing the
photodesorption of CO or due to thermal desorption of CO as a consequence of
radial drift and settlement of dust grains
Utilizing NVIDIA GPUs for Waveform Analysis for the Nab Experiment
GPUs are composed of a large number of small computational cores compared to CPUs which are generally just a few larger cores. While the CPU excels at linear processes, the GPU excels at parallel tasks. For this project, the goal was to find a way to use the massive parallelism of a GPU to rapidly analyze waveform data from the Nab experiment
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