1,423 research outputs found
First report of annual ryegrass toxicity in the Republic of South Africa
The occurrence of annual ryegrass toxicity (ARGT) in sheep and cattle is reported for the first
time in South Africa. To date it has been diagnosed conclusively in South African Mutton Merino
sheep on a farm in the Caledon district and in cattle on 3 farms, 2 of which are situated in the Bredasdorp
district and 1 in the Ceres district. It is a neurological disease characterized by symptoms of
tremor, ataxia, intermittent epileptiform seizures, nystagmus, opisthotonus, abortions and high
mortality.
The history, clinical signs and experimental reproduction of the disease as well as the pathology
of 4 experimental and 10 natural cases in sheep and 2 in cattle are described.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
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Collision-induced dissociation of bradykinin ions in the interface region of an ESI-MS
AbstractBy applying different electric field strengths to the orifice–skimmer region of an electrospray ionization mass spectrometer, the rate of dissociation can be varied based on the amount of internal energy acquired by an ion through collisions with the curtain gas molecules. Both the Arrhenius equation and Rice-Ramsperger-Kassel (RRK) theory can be used to predict the rate of dissociation of internally excited molecules. A previously determined model for collision-induced dissociation is tested by comparison of predicted and experimentally observed orifice–skimmer potential differences for dissociation of ions. The rate of collision-induced dissociation of bradykinin ions is determined by monitoring the fragments produced in a mass spectrometer. The semi-quantitative model is found to yield effective predictions when accurate Arrhenius and RRK parameters are utilized
Thermodynamic gauge-theory cascade
It is proposed that the cooling of a thermalized SU() gauge theory can be
formulated in terms of a cascade involving three effective theories with
successively reduced (and spontaneously broken) gauge symmetries, SU()
U(1) Z. The approach is based on the assumption that away
from a phase transition the bulk of the quantum interaction inherent to the
system is implicitly encoded in the (incomplete) classical dynamics of a
collective part made of low-energy condensed degrees of freedom. The properties
of (some of the) statistically fluctuating fields are determined by these
condensate(s). This leads to a quasi-particle description at tree-level. It
appears that radiative corrections, which are sizable at large gauge coupling,
do not change the tree-level picture qualitatively. The thermodynamic
self-consistency of the quasi-particle approach implies nonperturbative
evolution equations for the associated masses. The temperature dependence of
these masses, in turn, determine the evolution of the gauge coupling(s). The
hot gauge system approaches the behavior of an ideal gas of massless gluons at
asymptotically large temperature. A negative equation of state is possible at a
stage where the system is about to settle into the phase of the (spontaneously
broken) Z symmetry.Comment: 25 pages, 6 figures, 1 reference added, minor corrections in text,
errors in Sec. 3.2 corrected, PRD versio
A suspected lipofuscin storage disease of sheep associated with ingestion of the plant, Trachyandra divaricata (Jacq.) Kunth
Paresis afflicted 85 out of a flock of 770 young Merino ewes kept on old wheat lands in the western Cape during a period of drought. Many of the paretic ewes died. The vegetation was sparse and was dominated by Trachyandra divaricata. At necropsy, yellowish-brown discoloration of the grey matter throughout the brain and spinal cord and mild brown discoloration of the liver, renal cortex and lymph nodes were consistently seen.
Light microscopical examination revealed abundant, yellowish-brown pigment granules in the cytoplasm of most of the larger neurons. Similar pigment also occurred in some non-nervous tissues. Shrinkage and loss of a few randomly scattered axons were observed in the white matter of the spinal cord in 2 sheep. Histochemical and ultrastructural features of the pigment were consistent with those of lipofuscin.
T. divaricata failed to reproduce the condition when dosed to a sheep, but the paresis and pigmentation shown to be caused by the closely related plant, T. laxa, are strikingly similar. Trachyandra poisoning appears to be the first documented example in farm animals of an acquired lipofuscin storage disease involving nervous and non-nervous tissues for which a specific plant has been causally implicated.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
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Neutrino Halos in Clusters of Galaxies and their Weak Lensing Signature
We study whether non-linear gravitational effects of relic neutrinos on the
development of clustering and large-scale structure may be observable by weak
gravitational lensing. We compute the density profile of relic massive
neutrinos in a spherical model of a cluster of galaxies, for several neutrino
mass schemes and cluster masses. Relic neutrinos add a small perturbation to
the mass profile, making it more extended in the outer parts. In principle,
this non-linear neutrino perturbation is detectable in an all-sky weak lensing
survey such as EUCLID by averaging the shear profile of a large fraction of the
visible massive clusters in the universe, or from its signature in the general
weak lensing power spectrum or its cross-spectrum with galaxies. However,
correctly modeling the distribution of mass in baryons and cold dark matter and
suppressing any systematic errors to the accuracy required for detecting this
neutrino perturbation is severely challenging.Comment: 13 pages, 11 figures. Submitted to JCA
Palm pairs and the general mass-transport principle
We consider a lcsc group G acting properly on a Borel space S and measurably
on an underlying sigma-finite measure space. Our first main result is a
transport formula connecting the Palm pairs of jointly stationary random
measures on S. A key (and new) technical result is a measurable disintegration
of the Haar measure on G along the orbits. The second main result is an
intrinsic characterization of the Palm pairs of a G-invariant random measure.
We then proceed with deriving a general version of the mass-transport principle
for possibly non-transitive and non-unimodular group operations first in a
deterministic and then in its full probabilistic form.Comment: 26 page
Generation and characterization of function-blocking anti-ectodysplasin A (EDA) monoclonal antibodies that induce ectodermal dysplasia.
Development of ectodermal appendages, such as hair, teeth, sweat glands, sebaceous glands, and mammary glands, requires the action of the TNF family ligand ectodysplasin A (EDA). Mutations of the X-linked EDA gene cause reduction or absence of many ectodermal appendages and have been identified as a cause of ectodermal dysplasia in humans, mice, dogs, and cattle. We have generated blocking antibodies, raised in Eda-deficient mice, against the conserved, receptor-binding domain of EDA. These antibodies recognize epitopes overlapping the receptor-binding site and prevent EDA from binding and activating EDAR at close to stoichiometric ratios in in vitro binding and activity assays. The antibodies block EDA1 and EDA2 of both mammalian and avian origin and, in vivo, suppress the ability of recombinant Fc-EDA1 to rescue ectodermal dysplasia in Eda-deficient Tabby mice. Moreover, administration of EDA blocking antibodies to pregnant wild type mice induced in developing wild type fetuses a marked and permanent ectodermal dysplasia. These function-blocking anti-EDA antibodies with wide cross-species reactivity will enable study of the developmental and postdevelopmental roles of EDA in a variety of organisms and open the route to therapeutic intervention in conditions in which EDA may be implicated
Ovine hepatogenous photosensitivity caused by the plant Nidorella foetida (Thunb.) DC. (Asteraceae)
Following a field outbreak of hepatogenous photosensitivity in sheep, an identical condition was reproduced experimentally by dosing 2 sheep with green, homogenized, Nidorella foetida material, collected from the camp where the outbreak occurred. This is a rare, unpalatable, aromatic shrub found in swampy places in the south-western Cape Province. The main lesion was a hepatosis, characterized by peripheral coagulative necrosis and midzonal degeneration in the 2 acute cases and mild bile duct proliferation and hepatic regeneration in the more chronic field case. Botanical, toxicological, clinical and pathological data are given.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
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Efficient photoionization for barium ion trapping using a dipole-allowed resonant two-photon transition
Two efficient and isotope-selective resonant two-photon ionization techniques
for loading barium ions into radio-frequency (RF)-traps are demonstrated. The
scheme of using a strong dipole-allowed transition at \lambda=553 nm as a first
step towards ionization is compared to the established technique of using a
weak intercombination line (\lambda=413 nm). An increase of two orders of
magnitude in the ionization efficiency is found favoring the transition at 553
nm. This technique can be implemented using commercial all-solid-state laser
systems and is expected to be advantageous compared to other narrowband
photoionization schemes of barium in cases where highest efficiency and
isotope-selectivity are required.Comment: 8 pages, 5 figure
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