7,291 research outputs found
An assessment of the recreational fishery in the St Lucia estuarine system, KwaZulu-Natal, South Africa
St Lucia is one of the largest estuarine systems in Africa, and attracts thousands of anglers each year. Catch card data from the National Marine Linefish System for the years 1986–1999 were analysed to determine catch composition, catch per unit effort (cpue) and seasonality of catches by recreational anglers. Because not all anglers completed catch cards, estimates of total catch were made using additional data on the number of private
boat outings, the number of boat trailers at boat slipways and the number of boats recorded entering the campsite gates during 1992 and 1993. In all, 27 fish families, constituting 55 species, were recorded by recreational anglers. Dusky kob Argyrosomus japonicus, spotted grunter Pomadasys commersonnii, perch Acanthopagrus berda, Natal stumpnose Rhabdosargus sarba, springer Elops machnata and mini-kob Johnius dorsalis were the most prominent species caught in terms of numbers and mass. Catch rates expressed numerically (fish angler-1 h-1) peaked during the summer and early winter. However, in terms of mass, catch rates peaked during late winter and spring, when there were increased landings of large dusky kob. Fluctuations in cpue were linked to salinity and estuary mouth conditions (i.e. mouth closure). Despite annual fluctuations in cpue, regression analysis revealed an overall downward trend for the dominant species (dusky kob and spotted grunter) and a gradual increase for stumpnose, perch and springer, but with the exception of stumpnose, these trends were not significant. Socio-economic aspects of the fishery were also investigated by conducting an independent boat-angler survey. The value of the recreational fishery, in terms of accommodation and direct angler expenditure, was estimated to be in the region of R9 million during 1992. Angler attitudes towards fishing regulations were positive and anglers generally had a good knowledge of the regulations for target species. Based on this assessment, a number of suggestions are made regarding the future management of the recreational fishery at St Lucia.Keywords: catch and effort, management, recreational angling, socio-economics, St Lucia estuarine systemAfrican Journal of Marine Science 2002, 24: 263–27
Exploring Exogenic Sources for the Olivine on Asteroid (4) Vesta
The detection of olivine on Vesta is interesting because it may provide
critical insights into planetary differentiation early in our Solar System's
history. Ground-based and Hubble Space Telescope (HST) observations of asteroid
(4) Vesta have suggested the presence of olivine on the surface. These
observations were reinforced by the discovery of olivine-rich HED meteorites
from Vesta in recent years. However, analysis of data from NASA's Dawn
spacecraft has shown that this olivine-bearing unit is actually impact melt in
the ejecta of Oppia crater. The lack of widespread mantle olivine, exposed
during the formation of the 19 km deep Rheasilvia basin on Vesta's South Pole,
further complicated this picture. Ammannito et al., (2013a) reported the
discovery of local scale olivine-rich units in the form of excavated material
from the mantle using the Visible and InfraRed spectrometer (VIR) on Dawn. Here
we explore alternative sources for the olivine in the northern hemisphere of
Vesta by reanalyzing the data from the VIR instrument using laboratory spectral
measurements of meteorites. We suggest that these olivine exposures could be
explained by the delivery of olivine-rich exogenic material. Based on our
spectral band parameters analysis, the lack of correlation between the location
of these olivine-rich terrains and possible mantle-excavating events, and
supported by observations of HED meteorites, we propose that a probable source
for olivine seen in the northern hemisphere are remnants of impactors made of
olivine-rich meteorites. Best match suggests these units are HED material mixed
with either ordinary chondrites, or with some olivine-dominated meteorites such
as R-chondrites.Comment: 62 pages, 12 figures, 4 tables; Icarus, Available online 30 January
2015, ISSN 0019-1035, http://dx.doi.org/10.1016/j.icarus.2015.01.01
The V-A sum rules and the Operator Product Expansion in complex q^2-plane from tau-decay data
The operator product expansion (OPE) for the difference of vector and axial
current correlators is analyzed for complex values of momentum q^2. The vector
and axial spectral functions, taken from hadronic tau-decay data, are treated
with the help of Borel, Gaussian and spectral moments sum rules. The range of
applicability, advantages and disadvantages of each type are discussed. The
general features of OPE are confirmed by the data. The vacuum expectation
values of dimension 6 and 8 operators are found to be O_6=-(6.8\pm 2.1)*10^{-3}
GeV^6, O_8=(7\pm 4)*10^{-3} GeV^8.Comment: 1 latex + 10 eps files, 14 page
Work stress and cancer researchers : an exploration of the challenges, experiences and training needs of UK cancer researchers.
Work stress is a significant issue for many UK healthcare professionals, in particular those working in the field of oncology. However, there have been very few attempts to explore the challenges, experiences or training needs of researchers working in cancer research. In doing so, we will be better positioned to support and develop these researchers.
18 UK oncology researchers from a variety of backgrounds took part in a semi-structured interview. Interviews were transcribed and analysed using thematic analysis.
The analysis identified two overarching themes: logistical research issues (workload, accessing/ recruiting participants, finances) and sensitive research issues (emotional demands, professional boundaries, sensitivity around recruitment). One cross-cutting theme, supportive strategies (support and training, coping mechanisms), was seen to influence both logistical and sensitive research issues. While further research is needed to fully understand the causes and impact of work stress on cancer researchers, three specific issues were highlighted: emotional demands are relevant to quantitative and mixed methods researchers as well as those engaged in qualitative research; the researchers’ background (experience; clinical/non-clinical) was influential and an exploration of effective coping strategies is required; and there is a clear need for adequate support systems and training to be available, particularly for early career researchers.</p
On the Renormalization of a Bosonized Version of the Chiral Fermion-Meson Model at Finite Temperature
Feynman's functional formulation of statistical mechanics is used to study
the renormalizability of the well known Linear Chiral Sigma Model in the
presence of fermionic fields at finite temperature in an alternative way. It is
shown that the renormalization conditions coincide with those of the zero
temperature model.Comment: 12 pages, no figures, LaTex, reference [17] is updated, to appear in
Phys. Lett.
alpha_s and the tau hadronic width
Different choices exist for the renormalisation group resummation in the
determination of from hadronic decays: namely fixed-order
(FOPT) and contour-improved perturbation theory (CIPT). The two approaches lead
to systematic differences in the resulting . On the basis of a model
for higher-order terms in the perturbative series, which incorporates
well-known structure from renormalons, it is found that while CIPT is unable to
account for the fully resummed series, FOPT smoothly approaches the Borel sum.
Employing the model to determine yields , which after evolution leads to .Comment: 6 pages, 2 figures. Talk given at the 10th International Workshop on
Tau Lepton Physics, Novosibirsk, Russia, Sep. 22-25, 200
Nanodust detection near 1 AU from spectral analysis of Cassini/RPWS radio data
Nanodust grains of a few nanometer in size are produced near the Sun by
collisional break-up of larger grains and picked-up by the magnetized solar
wind. They have so far been detected at 1 AU by only the two STEREO spacecraft.
Here we analyze the spectra measured by the radio and plasma wave instrument
onboard Cassini during the cruise phase close to Earth orbit; they exhibit
bursty signatures similar to those observed by the same instrument in
association to nanodust stream impacts on Cassini near Jupiter. The observed
wave level and spectral shape reveal impacts of nanoparticles at about 300
km/s, with an average flux compatible with that observed by the radio and
plasma wave instrument onboard STEREO and with the interplanetary flux models
Biomineral repair of Abalone shell apertures
The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair
Cosmological implications of a class of SO(10) models
The cosmological implications of a class of SO(10) models are discussed. In
particular we show how a good prediction for neutrino masses is obtained in
order to fit with the MSW mechanism to explain the solar neutrino flux deficit
and with the predicted amount of the dark matter hot component. A possible
scenario for baryogenesis is also considered.Comment: latex file, 3 pages, appeared in Proceedings of TAUP 95, Toledo, 17
-21 September 1995. Nucl. Phys. B (Proc. Suppl.) 48 (1996) 272, Eds. A.
Morales, J. Morales and J. A. Villa
Learning to embed sustainability skills and knowledge in the workplace- Final Project Report.
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