13,266 research outputs found
Gastrointestinal nematodes of Ovis aries in Eastern Cape, South Africa and an evaluation of current anthelmintic procedures
Humans have known about helminth infections since ancient times. Today half of the human population is plagued by a nematode infection. Nematodes are responsible for billions of dollars in global crop damage annually and have had devastating effects on the global livestock industry. Due to the lack of a vaccine, and only a handful of approved classes of anthelmintics, nematode resistance has become a serious global phenomenon, and the South African commercial sheep industry has been one of the worst affected worldwide. The current study used fecal float parasitology to determine the nematode species found on a commercial sheep farm in Eastern Cape, South Africa, and the severity of their burden. There were five main species of nematodes found: Strongyles, Strongyloides spp., Trichuris ovis, Nematodirus spathiger, and Haemonchus contortus. The farm had two different populations of sheep – the flock population which were of acceptable wool quality and the stud population which were of superior wool quality. The two populations were compared to each other. There was no significant difference in nematode species present or severity of infection between the two populations. Although the nematode burden of this farm was not as severe as many other South African farms, a discussion of current anthelmintic treatments and possible practices that may improve animal health and wool quality are discussed
The Star Formation History of the Solar Neighbourhood from the White Dwarf Luminosity Function
The termination in the white dwarf luminosity function is a standard
diagnostic tool for measuring the total age of nearby stellar populations. In
this paper, an algorithm is presented for inverting the full white dwarf
luminosity function to obtain a maximum likelihood estimate of the time varying
star formation rate of the host stellar population. Tests with synthetic data
demonstrate that the algorithm converges over a wide class of underlying star
formation rate forms. The algorithm successfully estimates the moving average
star formation rate as a function of lookback time in the presence of realistic
measurement noise, though suffers from degeneracies around discontinuities in
the underlying star formation rate. The inversion results are most sensitive to
the choice of white dwarf cooling models, with the models produced by different
groups giving quite different results. The results are relatively insensitive
to the progenitor metallicity, initial mass function, initial-final mass
relation and ratio of H/He atmosphere white dwarfs. Application to two
independent determinations of the Solar neighbourhood white dwarf luminosity
function gives similar results. The star formation rate has a bimodal form,
with broad peaks at 2-3 Gyr and 7-9 Gyr in the past, separated by a significant
lull of magnitude 30-90% depending on choice of cooling models. The onset of
star formation occurs around 8-10 Gyr ago. The total integrated star formation
rate is ~0.014 stars/pc3 in the Solar neighbourhood, for stars more massive
than 0.6M_{solar}.Comment: 18 pages, 17 figures. Accepted to MNRA
Carney Hospital's Maternity Service Plan: A study of one hundred and eleven patients admitted to the Carney Hospital's prenatal clinic during the months of May, June, July, 1949
Thesis (M.S.)--Boston Universit
Overt Research Project- 'A Fieldguide to Dark Places - South Edition'
Directed by artist researcher Neal White, Office of Experiments collaborated with researcher and artist Steve Rowell a project manager at the Center for Land Use Interpretation for 18 months in an exchange of methods, standard and experimental, fieldwork and mapping processes. The development of a specifically named research method 'Overt Research' was used to label an inversion of the direction of technologies and techniques exploited in surveillance and security control, and was used in this research to document both the real and imaginary spaces of secrecy in the UK, initially near to Southampton. Using photographic and GIS data sites of experimentation, intelligence and knowledge not normally accessible to the public were brought together in a drupal database. With a taxonomy and vocabulary based on levels of transparency of sites the research output brought together discourse concerning the UK and its techno-scientific and military complex and the public imaginary in relation to these sites. 'A Fieldguide to Dark Places - South Edition' was a central part of the larger exhibition, Dark Places, that White co-curated at John Hansard Gallery in 2009-10. ORP was launched as an 'open project' that also engages members of the public and amateur enthusiasts, and now incorporates them into the research process through attendance of planned activities and events. Many works are also included in 'Critical Dictionary' (Blackdog 2012) and were also exhibited in an installation at Blackdog Gallery, London 2012. Featured extracts from the database appeared in a 6 page article as part of Blueprint magazine edition examining new topographies. March 2010. Critical excursions / mediated bus tours using the ORP have further been supported by ESCR (Experimental Ruins, UCL, London), Big Picture (Secrets of Portland, Portland, Dorset 2011) and The Heritage Lottery Fund (London Orbital Tour 2012)
Unitary Braid Representations with Finite Image
We characterize unitary representations of braid groups of degree
linear in and finite images of such representations of degree exponential
in .Comment: 17 page
Degeneracy Implies Non-abelian Statistics
A non-abelian anyon can only occur in the presence of ground state degeneracy
in the plane. It is conceivable that for some strange anyon with quantum
dimension that the resulting representations of all -strand braid
groups are overall phases, even though the ground state manifolds for
such anyons in the plane are in general Hilbert spaces of dimensions . We
observe that degeneracy is all that is needed: for an anyon with quantum
dimension the non-abelian statistics cannot all be overall phases on the
degeneracy ground state manifold. Therefore, degeneracy implies non-abelian
statistics, which justifies defining a non-abelian anyon as one with quantum
dimension . Since non-abelian statistics presumes degeneracy, degeneracy is
more fundamental than non-abelian statistics.Comment: State the main result as a theorem and add several clarification
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