1,107 research outputs found
Si(Li) position sensitive detector
A position sensitive detector was made using the lithium diffused layer of a lithium-drifted-silicon detector as the uniform resistive layer. An expression is derived for estimating the resistance from the thickness of the lithium layer. Expressions for the noise and ballistic deficit for single differentiation-double integration pulse shaping are presented. Room temperature data for a 1 Mev proton beam on a 45 mm long detector shows that the linearity is better than .05% and that the position resolution is 1.06 + or - .05 mm
Three-body bound states with zero-range interaction in the Bethe-Salpeter approach
The Bethe-Salpeter equation for three bosons with zero-range interaction is
solved for the first time. For comparison the light-front equation is also
solved. The input is the two-body scattering length and the outputs are the
three-body binding energies, Bethe-Salpeter amplitudes and light-front wave
functions. Three different regimes are analyzed: ({\it i}) For weak enough
two-body interaction the three-body system is unbound. ({\it ii}) For stronger
two-body interaction a three-body bound state appears. It provides an
interesting example of a deeply bound Borromean system. ({\it iii}) For even
stronger two-body interaction this state becomes unphysical with a negative
mass squared. However, another physical (excited) state appears, found
previously in light-front calculations. The Bethe-Salpeter approach implicitly
incorporates three-body forces of relativistic origin, which are attractive and
increase the binding energy.Comment: 13 pages, 7 figure
Veterinary use of bacteriophage therapy in intensively-reared livestock
Zoonoses are infectious diseases transmitted directly or indirectly between animals and humans. Several important zoonotic pathogens colonize farm animals asymptomatically, which may lead to contamination of the food chain and public health hazards. Moreover, routine sampling of carcasses at retail by government authorities over the past 20 years suggests the prevalence of antibiotic resistance in foodborne pathogens has increased. If this continues, antibiotics may be ineffective against such pathogens in the future and alternative approaches, such as phage therapy, may be necessary. Intensive livestock farming is the only realistic way of meeting the demand for meat from an increasing global population and growth in middle class consumers in developing countries, particularly in Asia. This review elaborates on the use of phages to control zoonotic pathogens in intensively-reared livestock (poultry and pigs)
Bound state structure and electromagnetic form factor beyond the ladder approximation
We investigate the response of the bound state structure of a two-boson
system, within a Yukawa model with a scalar boson exchange, to the inclusion of
the cross-ladder contribution to the ladder kernel of the Bethe-Salpeter
equation. The equation is solved by means of the Nakanishi integral
representation and light-front projection. The valence light-front wave
function and the elastic electromagnetic form factor beyond the impulse
approximation, with the inclusion of the two-body current, generated by the
cross-ladder kernel, are computed. The valence wave function and
electromagnetic form factor, considering both ladder and ladder plus
cross-ladder kernels, are studied in detail. Their asymptotic forms are found
to be quite independent of the inclusion of the cross-ladder kernel, for a
given binding energy. The asymptotic decrease of form factor agrees with the
counting rules. This analysis can be generalized to fermionic systems, with a
wide application in the study of the meson structure.Comment: 19 pages, 6 figures, submitted to Phys. Lett.
Fermion dynamics in torsion theories
In this work we have studied the non-geodesical behaviour of particles with
spin 1/2 in Poincar\'e gauge theories of gravity, via the WKB method and the
Mathisson-Papapetrou equation. We have analysed the relation between the two
approaches and we have argued the different advantages associated with the WKB
approximation. Within this approach, we have calculated the trajectories in a
particular Poincar\'e gauge theory, discussing the viability of measuring such
a motion.Comment: 17 pages, 2 figures, minor changes, conclusions unchanged. It matches
the version published in JCA
Chromosome 1p13 genetic variants antagonize the risk of myocardial infarction associated with high ApoB serum levels
PMCID: PMC3480949This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
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