709 research outputs found
Influence of Corn Density on Pig Growth and Nutrient Digestibility
The pricing of corn is baded upon a number of factors including moisture content, test weight, level contaminants, and deterioration of quality. It is understood that high moisture content dilutes the concentration of energy and nutrients. Poor quality because of deterioration during storage and the presence of contaminants lowers the palatability of the ingredient and may have negative health ramifications With less logical reasoning it has been assumed that the feeding value of corn for pigs is related to cornâs bulk density. Low-test weight corn is sold at a discount even if moisture content and quality factors are desirable. Corn harvested in the fall of 1992 with a density of either 20.9 kg/bu (46 lb/bu; LO) or 25.5 kg/bu (56 lb/bu; HI) was used in a growth trial and a digestibility study to further evaluate the effect for growing pig
Predation risk influences food-web structure by constraining species diet choice
The foraging behaviour of species determines their diet and, therefore, also emergent food-web structure. Optimal foraging theory (OFT) has previously been applied to understand the emergence of food-web structure through a consumer-centric consideration of diet choice. However, the resource-centric viewpoint, where species adjust their behaviour to reduce the risk of predation, has not been considered. We develop a mechanistic model that merges metabolic theory with OFT to incorporate the effect of predation risk on diet choice to assemble food webs. This 'predation-risk-compromise' (PR) model better captures the nestedness and modularity of empirical food webs relative to the classical optimal foraging model. Specifically, compared with optimal foraging alone, risk-mitigated foraging leads to more-nested but less-modular webs by broadening the diet of consumers at intermediate trophic levels. Thus, predation risk significantly affects food-web structure by constraining species' ability to forage optimally, and needs to be considered in future work
Low-mass dileptons and dropping rho meson mass
Using the transport model, we have studied dilepton production from heavy-ion
collisions at Bevalac energies. It is found that the enhanced production of
low-mass dileptons observed in the experiment by the DLS collaboration cannot
be explained by the dropping of hadron masses, in particular the -meson
mass, in dense matter.Comment: 9 pages, LaTeX, including 1 postscript figure, to appear in Phys.
Lett.
Period- and mirror-maps for the quartic K3
We study in detail mirror symmetry for the quartic K3 surface in P3 and the
mirror family obtained by the orbifold construction. As explained by Aspinwall
and Morrison, mirror symmetry for K3 surfaces can be entirely described in
terms of Hodge structures. (1) We give an explicit computation of the Hodge
structures and period maps for these families of K3 surfaces. (2) We identify a
mirror map, i.e. an isomorphism between the complex and symplectic deformation
parameters, and explicit isomorphisms between the Hodge structures at these
points. (3) We show compatibility of our mirror map with the one defined by
Morrison near the point of maximal unipotent monodromy. Our results rely on
earlier work by Narumiyah-Shiga, Dolgachev and Nagura-Sugiyama.Comment: 29 pages, 3 figure
Analysis of Kaon Production at SIS Energies
We analyse the production and propagation of pions and kaons in heavy-ion
reactions from 0.8 -- 1.8~AGeV within a coupled channel transport
approach including the kaon production channels and . Assuming the hyperon selfenergy to be 2/3 of the nucleon selfenergy
we find that all inclusive experimental spectra at SIS energies can be
reproduced reasonably well without any selfenergies for the kaons although a
slightly repulsive kaon potential cannot be excluded by the present data on
kaon spectra and flow.Comment: 19 pages, LaTeX, including 8 postscript figures, to appear in Nucl.
Phys.
production in reactions at SIS energies
Detailed predictions for dilepton production from reactions at SIS
energies are presented within a semi-classical BUU transport model that
includes the off-shell propagation of vector mesons nonperturbatively and
calculates the width of the vector mesons dynamically. Different scenarios of
in-medium modifications of vector mesons, such as collisional broadening and
dropping vector meson masses, are investigated and the possibilities for an
experimental observation of in-medium effects in reactions at 1--4 GeV
are discussed for a variety of nuclear targets.Comment: 38 pages, LaTeX, including 20 postscript figures, to be published in
Nucl. Phys.
Perspectives of production in pp, pd and p Be reactions at SIS energies
We study dilepton production from pp, pd and p Be collisions from 1 - 5 GeV
including the , , and Dalitz decays, direct
decays of vector mesons (, ) as well as subthreshold
production via baryonic resonances (e.g. ). Our
calculations compare rather well with the pp and pd data from the DLS
Collaboration, however, overestimate slightly the 'old' p Be data from that
group. Futhermore, detailed predictions for differential dilepton spectra at
SIS energies are made with a high mass resolution that can be controlled
experimentally by the HADES Collaboration in near future.Comment: 27 pages, LaTeX, including 13 postscript figures, to be published in
Nucl. Phys.
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