132 research outputs found
Length-weight relationships for some important forage crustaceans from South Africa
The diet of marine animals is usually determined by stomach content analysis. Although partially digested prey fragments can often be identified to species level, it is difficult to estimate the original mass of the prey organism. This information, however, is essential for calculating both the total food intake as well as the relative contribution of each prey item. In this study we present regression equations that can be used to estimate the original mass of 18 common South African crustaceans from various indigestible fragments such as the carapace (length and width), chelae (length and width of left and right dactylus) and eye (length and width)
Slaughterhouse zoonoses: Are workers reservoirs of zoonotic disease?
Slaughterhouse workers are considered a high risk group for zoonotic disease due to increased contact
with animals, animal products and excreta. Globally, slaughterhouse workers have been shown to have an
increased seroprevalence to zoonotic pathogens, though no such studies exist in Kenya. Slaughterhouse
workers may also act as reservoirs of these zoonotic organisms and asymptomatic carriage of pathogenic
bacteria has been demonstrated. This study aimed to determine the carriage of enteropathogens in
slaughterhouse workers in rural western Kenya and to determine if there was asymptomatic carriage of
Staphylococcus aureus specifically Methicillin Resistant S. aureus (MRSA). This study was conducted
in the Lake Victoria Crescent region of western Kenya. Five hundred slaughterhouse workers from this
region were asked a comprehensive questionnaire regarding risk factors for zoonotic disease, faecal samples
were collected for examination and culture and a nasal swab was cultured for S. aureus. This study reports
on the seroprevalence of Salmonella spp, Shigella spp, pathogenic Escherichia coli and Campylobacter
spp. in these individuals as well as reporting the nasal carriage of S. aureus and MRSA. This is the first
community based study regarding S. aureus and MRSA in Kenya. The asymptomatic carriage of these
organisms in slaughterhouse workers highlights a reservoir that may be important in the dissemination of
these pathogens. The study further comments on the risk factors for infection with these pathogens and
suggestions are made for simple hygiene interventions that can reduce disease in slaughterhouse workers
and dissemination to the wider communit
Moduli Instability in Warped Compactifications of the Type IIB Supergravity
We show that the conifold and deformed-conifold warped compactifications of
the ten-dimensional type IIB supergravity, including the Klebanov-Strassler
solution, are dynamically unstable in the moduli sector representing the scale
of a Calabi-Yau space, although it can be practically stable for a quite long
time in a region with a large warp factor. This instability is associated with
complete supersymmetry breaking except for a special case and produces
significant time-dependence in the structure of the four-dimensional base
spacetime as well as of the internal space.Comment: 24 pages, no figure. Typos corrected, and some arguments in section 5
are adde
Potential and mass-matrix in gauged N=4 supergravity
We discuss the potential and mass-matrix of gauged N=4 matter coupled
supergravity for the case of six matter multiplets, extending previous work by
considering the dependence on all scalars. We consider all semi-simple gauge
groups and analyse the potential and its first and second derivatives in the
origin of the scalar manifold. Although we find in a number of cases an
extremum with a positive cosmological constant, these are not stable under
fluctuations of all scalar fields.Comment: 28 pages, LaTe
Holographic Dark Energy Model and Scalar-Tensor Theories
We study the holographic dark energy model in a generalized scalar tensor
theory. In a universe filled with cold dark matter and dark energy, the effect
of potential of the scalar field is investigated in the equation of state
parameter. We show that for a various types of potentials, the equation of
state parameter is negative and transition from deceleration to acceleration
expansion of the universe is possible.Comment: 11 pages, no figure. To appear in General Relativity and Gravitatio
Can induced gravity isotropize Bianchi I, V, or IX Universes?
We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory
can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the
non--minimal coupling of gravity and the scalar field. The analytical results
that we found for the Brans-Dicke (BD) theory are now applied to the IG theory
which has ( being the square ratio of the Higgs to
Planck mass) in a cosmological era in which the IG--potential is not
significant. We find that the isotropization mechanism crucially depends on the
value of . Its smallness also permits inflationary solutions. For the
Bianch V model inflation due to the Higgs potential takes place afterwads, and
subsequently the spontaneous symmetry breaking (SSB) ends with an effective FRW
evolution. The ordinary tests of successful cosmology are well satisfied.Comment: 24 pages, 5 figures, to be published in Phys. Rev. D1
Tachyonic Inflation in a Warped String Background
We analyze observational constraints on the parameter space of tachyonic
inflation with a Gaussian potential and discuss some predictions of this
scenario. As was shown by Kofman and Linde, it is extremely problematic to
achieve the required range of parameters in conventional string
compactifications. We investigate if the situation can be improved in more
general compactifications with a warped metric and varying dilaton. The
simplest examples are the warped throat geometries that arise in the vicinity
of of a large number of space-filling D-branes. We find that the parameter
range for inflation can be accommodated in the background of D6-branes wrapping
a three-cycle in type IIA. We comment on the requirements that have to be met
in order to realize this scenario in an explicit string compactification.Comment: Latex, JHEP class, 20 pages, 4 figures. v2: references added, small
error in section 7 corrected, published versio
Non-minimally Coupled Tachyonic Inflation in Warped String Background
We show that the non-minimal coupling of tachyon field to the scalar
curvature, as proposed by Piao et al, with the chosen coupling parameter does
not produce the effective potential where the tachyon field can roll down from
T=0 to large along the slope of the potential. We find a correct choice of
the parameters which ensures this requirement and support slow-roll inflation.
However, we find that the cosmological parameter found from the analysis of the
theory are not in the range obtained from observations. We then invoke warped
compactification and varying dilaton field over the compact manifold, as
proposed by Raeymaekers, to show that in such a setup the observed parameter
space can be ensured.Comment: minor typos corrected and references adde
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