7,439 research outputs found
Low stress and safe handling of outdoor cattle - effective measures to improve work environment and avoid dangerous situations
Grazing cattle are needed to preserve 450 000 hectares of semi-natural grasslands of high biodiversity in Sweden. Keeping cattle outdoors promotes their health and possibili¬ties to conduct natural behaviors. Working with cattle on pasture however, can increase accident rates (Health and Safety Authority, 2011). During the last two years, five fatali¬ties and several accidents have occurred during handling of cattle in Sweden. A method, based on knowledge of the animals’ natural behavior, referred to as low stress stock han¬dling (LSS-method), has been introduced to Sweden for cattle handling (Atkinson, 2011). A handler who consistently uses this method prevents the use of hits, sticks, harsh voice or negative forceful handling techniques. A consistent predictable approach from the han¬dler creates consistent and predictable animal behavior in return. Cattle become more trusting with their handlers and consequently more cooperative. This positive interaction between human being and animal can lead to both a safer work situation and a better animal welfare. On two of five studied farms so far, the LSS-method was actually inter¬vened during the observations, resulted in a successful reversal of conflict behaviour. On farm1, a highly stressed heifer took over three hours in attempt to load into a transport. It was successfully loaded within an hour after the intervention. On another farm, five escaped cows that the farmer had attempted to capture unsuccessfully for three conse¬cutive weeks were successfully captured through using the LSS-method
Scattering properties of weakly bound dimers of fermionic atoms
We consider weakly bound diatomic molecules (dimers) formed in a
two-component atomic Fermi gas with a large positive scattering length for the
interspecies interaction. We develop a theoretical approach for calculating
atom-dimer and dimer-dimer elastic scattering and for analyzing the inelastic
collisional relaxation of the molecules into deep bound states. This approach
is based on the single-channel zero range approximation, and we find that it is
applicable in the vicinity of a wide two-body Feshbach resonance. Our results
draw prospects for various interesting manipulations of weakly bound dimers of
fermionic atoms.Comment: extended version of cond-mat/030901
Collective oscillations of a trapped Fermi gas near a Feshbach resonance
The frequencies of the collective oscillations of a harmonically trapped
Fermi gas interacting with large scattering lengths are calculated at zero
temperature using hydrodynamic theory. Different regimes are considered,
including the molecular Bose-Einstein condensate and the unitarity limit for
collisions. We show that the frequency of the radial compressional mode in an
elongated trap exhibits a pronounced non monotonous dependence on the
scattering length, reflecting the role of the interactions in the equation of
state.Comment: 3 pages, including 1 figur
A cesium gas strongly confined in one dimension : sideband cooling and collisional properties
We study one-dimensional sideband cooling of Cesium atoms strongly confined
in a far-detuned optical lattice. The Lamb-Dicke regime is achieved in the
lattice direction whereas the transverse confinement is much weaker. The
employed sideband cooling method, first studied by Vuletic et al.\cite{Vule98},
uses Raman transitions between Zeeman levels and produces a spin-polarized
sample. We present a detailed study of this cooling method and investigate the
role of elastic collisions in the system. We accumulate of the atoms
in the vibrational ground state of the strongly confined motion, and elastic
collisions cool the transverse motion to a temperature of K=, where is the oscillation
frequency in the strongly confined direction. The sample then approaches the
regime of a quasi-2D cold gas. We analyze the limits of this cooling method and
propose a dynamical change of the trapping potential as a mean of cooling the
atomic sample to still lower temperatures. Measurements of the rate of
thermalization between the weakly and strongly confined degrees of freedom are
compatible with the zero energy scattering resonance observed previously in
weak 3D traps. For the explored temperature range the measurements agree with
recent calculations of quasi-2D collisions\cite{Petr01}. Transparent analytical
models reproduce the expected behavior for and also for where the 2D
features are prominent.Comment: 18 pages, 12 figure
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