4,688 research outputs found
Protection of pigs against challenge with virulent <i>Streptococcus suis</i> serotype 2 strains by a muramidase-released protein and extracellular factor vaccine
The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF) vaccine in preventing infection and disease in pigs challenged either with a homologous or a heterologous Streptococcus suis serotype 2 strain (MRP EF ) was compared with the efficacy of a vaccine containing formalin-killed bacterin of S suis serotype 2 (MRP EF ). The enhancement of the immune response by different adjuvants (a water-in-oil emulsion [wo] and an aluminium hydroxide-based adjuvant [AH]) and their side effects were also studied. The MRP and EF were purified by affinity chromatography. Pigs were vaccinated twice at three weeks and six weeks of age and challenged intravenously with virulent S suis serotype 2 strains (MRP EF ) at eight weeks of age. At challenge, the pigs vaccinated with MRP EF/WO had high anti-MRP and anti-EF titres and were protected as effectively as pigs vaccinated with wo-formulated vaccines with bacterin. Eight of the nine pigs survived the challenge and almost no clinical signs of disease were observed. The titres obtained with the MRP EF/AH vaccine were low and only two of the five pigs were protected. Pigs vaccinated with either MRP or EF were less well protected; three of the four pigs died after challenge but the clinical signs of disease were significantly less severe than those observed in the placebo-vaccinated pigs. The protective capacity of the bacterin/AH vaccine was very low, and the mortality among these pigs was as high as in the placebo-vaccinated pigs (80 per cent). Postmortem histological examination revealed meningitis, polyserositis and arthritis in the clinically affected pigs. The results demonstrate that a subunit vaccine containing both MRP and EF, formulated with the wo adjuvant, protected pigs against challenge with virulent S suis type 2 strains
Ammonia volatilization from manure in cropping systems for ethanol production
Non-Peer ReviewedEffect of tillage on ammonia (NH3) volatilized from fresh and com posted farmyard manure (FYM) used for fertilizing barley (Hordeum vulgare L.), was determined at two sites near Melfort, Saskatchewan in 1993. Ammonia losses were markedly higher in plots under zero tillage than under conventional tillage, as well as in plots which received a high rate (90 t ha-1) of FYM versus a lower rate (22 t ha-1). In conservation tillage cropping systems in which FYM is not incorporated into soil, the amount ofNH3 volatilized is not very large when FYM-N rates are comparable to crop requirements
Electron Spin Injection at a Schottky Contact
We investigate theoretically electrical spin injection at a Schottky contact
between a spin-polarized electrode and a non-magnetic semiconductor. Current
and electron density spin-polarizations are discussed as functions of barrier
energy and semiconductor doping density. The effect of a spin-dependent
interface resistance that results from a tunneling region at the
contact/semiconductor interface is described. The model can serve as a guide
for designing spin-injection experiments with regard to the interface
properties and device structure.Comment: 4 pages, 4 figure
An investigation into wound infection and abscess formation in a mine
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High-resolution UV spectrum of the benzeneâN2 van der Waals complex
The rotationally resolved spectrum of the 610 band of the S1 â S0 electronic transition of the benzeneâN2 van der Waals complex has been recorded and 119 transitions assigned. The C6H6·N2 complex, produced in a pulsed molecular beam, was detected by mass-selected two-photon two-colour ionization employing a high-resolution (ÎÎœUV = 100 MHz, fwhm) pulsed-amplified cw laser for the resonant intermediate excitation. The observed rotational structure is that of a rigid symmetric top with weaker additional rotational transitions most likely arising from the free internal rotation of the N2 in the plane parallel to the benzene ring. The N2 is located parallel to the benzene ring at a distance of 3.50 Ă
; this decreases by 45 mĂ
in the excited electronic state
Characterization of an INVS Model IV Neutron Counter for High Precision () Cross-Section Measurements
A neutron counter designed for assay of radioactive materials has been
adapted for beam experiments at TUNL. The cylindrical geometry and 60% maximum
efficiency make it well suited for () cross-section measurements near
the neutron emission threshold. A high precision characterization of the
counter has been made using neutrons from several sources. Using a combination
of measurements and simulations, the absolute detection efficiency of the
neutron counter was determined to an accuracy of 3% in the neutron energy
range between 0.1 and 1 MeV. It is shown that this efficiency characterization
is generally valid for a wide range of targets.Comment: 22 pages, 13 figure
Primordial non-Gaussianity in the Bispectrum of the Halo Density Field
The bispectrum vanishes for linear Gaussian fields and is thus a sensitive
probe of non-linearities and non-Gaussianities in the cosmic density field.
Hence, a detection of the bispectrum in the halo density field would enable
tight constraints on non-Gaussian processes in the early Universe and allow
inference of the dynamics driving inflation. We present a tree level derivation
of the halo bispectrum arising from non-linear clustering, non-linear biasing
and primordial non-Gaussianity. A diagrammatic description is developed to
provide an intuitive understanding of the contributing terms and their
dependence on scale, shape and the non-Gaussianity parameter fNL. We compute
the terms based on a multivariate bias expansion and the peak-background split
method and show that non-Gaussian modifications to the bias parameters lead to
amplifications of the tree level bispectrum that were ignored in previous
studies. Our results are in a good agreement with published simulation
measurements of the halo bispectrum. Finally, we estimate the expected signal
to noise on fNL and show that the constraint obtainable from the bispectrum
analysis significantly exceeds the one obtainable from the power spectrum
analysis.Comment: 34 pages, 15 figures, (v3): matches JCAP published versio
Astrophysical thermonuclear functions
As theoretical knowledge and experimental verification of nuclear cross
sections increases it becomes possible to refine analytic representations for
nuclear reaction rates. In this paper mathematical/statistical techniques for
deriving closed-form representations of thermonuclear functions are summarized
and numerical results for them are given.The purpose of the paper is also to
compare numerical results for approximate and closed-form representations of
thermonuclear functions.Comment: 17 pages in LaTeX, 8 figures available on request from
[email protected]
Improving multivariate Horner schemes with Monte Carlo tree search
Optimizing the cost of evaluating a polynomial is a classic problem in
computer science. For polynomials in one variable, Horner's method provides a
scheme for producing a computationally efficient form. For multivariate
polynomials it is possible to generalize Horner's method, but this leaves
freedom in the order of the variables. Traditionally, greedy schemes like
most-occurring variable first are used. This simple textbook algorithm has
given remarkably efficient results. Finding better algorithms has proved
difficult. In trying to improve upon the greedy scheme we have implemented
Monte Carlo tree search, a recent search method from the field of artificial
intelligence. This results in better Horner schemes and reduces the cost of
evaluating polynomials, sometimes by factors up to two.Comment: 5 page
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