810 research outputs found
Resource efficiency and economic implications of alternatives to surgical castration without anaesthesia
This paper presents an analysis of the economic implications of alternative methods to surgical castration without anaesthesia. Detailed research results on the economic implications of four different alternatives are reported. castration with local anaesthesia, castration with general anaesthesia, immunocastration and raising entire males. The first three alternatives have been assessed for their impact on pig production costs in the most important pig-producing Member States of the EU. The findings on castration with anaesthesia show that cost differences among farms increase if the anaesthesia cannot be administered by farmers and when the veterinarian has to be called to perform it. The cost of veterinarian service largely affects the total average costs, making this solution economically less feasible in small-scale pig farms. In all other farms, the impact on production costs of local anaesthesia is however limited and does not exceed 1 (sic)ct per kg. General anaesthesia administered by inhalation or injection of Ketamin in combination with a sedative (Azaperone, Midazolan) is more expensive. These costs depend heavily on farm size, as the inhalation equipment has to be depreciated on the largest number of pigs possible. The overall costs of immunocastration - including the cost of the work load for the farmer - has to be evaluated against the potential benefits derived from higher daily weight gain and feed efficiency in comparison with surgical castrates. The economic feasibility of this practice will finally depend on the price of the vaccine and on consumer acceptance of immunocastration, The improvement in feed efficiency may compensate almost entirely for the cost of vaccination. The main advantages linked to raising entire males are due to the higher efficiency of feed conversion, to the better growth rate and to the higher leanness of carcass. A higher risk of boar taint on the slaughter line has to be accounted for Raising entire males should not generate more than 2.5% of boar taint among slaughter pigs, in order to maintain the considerable economic benefits of better feed efficiency of entire males with respect to castrates
Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure
Using pulsed laser ablation with arsenic over pressure, the growth conditions
for GaAs nanowires have been systematically investigated and optimized. Arsenic
over pressure with As molecules was introduced to the system by thermal
decomposition of polycrystalline GaAs to control the stoichiometry and shape of
the nanowires during growth. GaAs nanowires exhibit a variety of geometries
under varying arsenic over pressure, which can be understood by different
growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs
nanowires with uniform diameter, lengths over 20 m, and thin surface oxide
layer were obtained and can potentially be used for further electronic
characterization
Brane plus Bulk Supersymmetry in Ten Dimensions
We discuss a generalized form of IIA/IIB supergravity depending on all R-R
potentials C^(p) (p=0,1,...,9) as the effective field theory of Type IIA/IIB
superstring theory. For the IIA case we explicitly break this R-R democracy to
either p=5 which allows us to write a new bulk action that can be
coupled to N=1 supersymmetric brane actions.
The case of 8-branes is studied in detail using the new bulk & brane action.
The supersymmetric negative tension branes without matter excitations can be
viewed as orientifolds in the effective action. These D8-branes and O8-planes
are fundamental in Type I' string theory. A BPS 8-brane solution is given which
satisfies the jump conditions on the wall. As an application of our results we
derive a quantization of the mass parameter and the cosmological constant in
string units.Comment: 15 pages, proceedings of 37th Karpacz Winter School, feb 200
Singular perturbation techniques in the gravitational self-force problem
Much of the progress in the gravitational self-force problem has involved the
use of singular perturbation techniques. Yet the formalism underlying these
techniques is not widely known. I remedy this situation by explicating the
foundations and geometrical structure of singular perturbation theory in
general relativity. Within that context, I sketch precise formulations of the
methods used in the self-force problem: dual expansions (including matched
asymptotic expansions), for which I identify precise matching conditions, one
of which is a weak condition arising only when multiple coordinate systems are
used; multiscale expansions, for which I provide a covariant formulation; and a
self-consistent expansion with a fixed worldline, for which I provide a precise
statement of the exact problem and its approximation. I then present a detailed
analysis of matched asymptotic expansions as they have been utilized in
calculating the self-force. Typically, the method has relied on a weak matching
condition, which I show cannot determine a unique equation of motion. I
formulate a refined condition that is sufficient to determine such an equation.
However, I conclude that the method yields significantly weaker results than do
alternative methods.Comment: 39 pages, 5 figures, final version to be published in Phys. Rev. D,
several typos corrected, added discussion of order-reductio
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