670 research outputs found
Pelletized Forage-Based Rations as Alternative Feeds for Improving Goat Productivity
Goat farming is very popular in the Philippines as it is considered by many to be a viable rural enterprise. Despite this, the goat industry is faced with many challenges, including problems relating to high pre-weaning mortality, poor nutrition and lack of strategic approaches to accelerate genetic improvement. The long term rate of increase of goat numbers is only 0.97% per annum, due to high offtake rates and low productivity. Thus, the Philippine goat population is only expected to reach 4.27million by 2020 (compared with the target of 6.2 million), given the 3.88million population in 2010 (Alo 2012). Interventions are needed to accelerate growth of the goat population. Goats are typically fed on locally available resources which are characterised by low quality and highly variable availability. These characteristics can be overcome through processing techniques such as sun drying and pelleting to ensure year round feed supply. Pelleting offers particular advantages. Feeding animals with pellets provides better feed efficiency, greater starch digestibility, less feed waste, non-selective feeding, better handling and storage, and increased income due to more efficient feeding and higher productivity. While pellets are available for swine, poultry and buffalo in the Philippine market, pellets for goats are not currently available. The aim of this study was to develop pelletized forage-based rations for goats and evaluate them for their technical and financial viability
RPA quasi-elastic responses in infinite and finite nuclear systems
Quasi-elastic responses in nuclear matter and in C and Ca
nuclei are calculated in ring approximation to investigate the finite size
effects on the electromagnetic quasi-elastic responses. A method to simulate
these effects in infinite systems calculations is proposed. The sensitivity of
the results to the various terms of the residual interaction is studied. The
results of nuclear matter RPA calculations are compared with those obtained in
ring approximation to evidence the importance of the exchange terms.Comment: 14 pages, 8 figure
Neutrino-Oxygen CC0 scattering in the SuSAv2-MEC model
We present the predictions of the SuSAv2-MEC model for the double
differential charged-current muonic neutrino (antineutrino) cross section on
water for the T2K neutrino (antineutrino) beam. We validate our model by
comparing with the available inclusive electron scattering data on oxygen and
compare our predictions with the recent T2K -O data, finding
good agreement at all kinematics. We show that the results are very similar to
those obtained for C scattering, except at low energies, and we
comment on the origin of this difference. A factorized spectral function model
of O is also included for purposes of comparison.Comment: 28 pages, 10 figures, JLAB-THY-17-2586. Version 2 accepted for
publication in Journal of Physics G: Nucl. Part. Phy
Origin of Relativistic Effects in the Reaction D(e,e'p)n at GeV Energies
In a series of recent publications, a new approach to the non-relativistic
reduction of the electromagnetic current operator in calculations of
electro-nuclear reactions has been introduced. In one of these papers, the
conjecture that at energies of a few GeV, the bulk of the relativistic effects
comes from the current and not from the nuclear dynamics was made, based on the
large relativistic effects in the transverse-longitudinal response. Here, we
explicitly compare a fully relativistic, manifestly covariant calculation
performed with the Gross equation, with a calculation that uses a
non-relativistic wave function and a fully relativistic current operator. We
find very good agreement up to missing momenta of 400 MeV/c, thus confirming
the previous conjecture. We discuss slight deviations in cross sections for
higher missing momenta and their possible origin, namely p-wave contributions
and off-shell effects.Comment: 25 pages, 11 figure
Two-nucleon knockout contributions to the C reaction in the dip and {}(1232) regions
The contributions from C and C to the
semi-exclusive C cross section have been calculated in an
unfactorized model for two-nucleon emission. We assume direct two-nucleon
knockout after virtual photon coupling with the two-body pion-exchange currents
in the target nucleus. Results are presented at several kinematical conditions
in the dip and (1232) regions. The calculated two-nucleon knockout
strength is observed to account for a large fraction of the measured
strength above the two-nucleon emission threshold.Comment: 12 Revtex pages, 4 postscript figures (available upon request),
University of Gent preprint SSF94-02-0
Alkaloids Analysis of Habranthus cardenasianus (Amaryllidaceae), Anti-Cholinesterase Activity and Biomass Production by Propagation Strategies
Plants in the Amaryllidaceae family synthesize a diversity of bioactive alkaloids. Some of these plant species are not abundant and have a low natural multiplication rate. The aims of this work were the alkaloids analysis of a Habranthus cardenasianus bulbs extract, the evaluation of its inhibitory activity against cholinesterases, and to test several propagation strategies for biomass production. Eleven compounds were characterized by GC-MS in the alkaloid extract, which showed a relatively high proportion of tazettine. The known alkaloids tazettine, haemanthamine, and the epimer mixture haemanthidine/6-epi-haemanthidine were isolated and identified by spectroscopic methods. Inhibitory cholinesterases activity was not detected. Three forms of propagation were performed: bulb propagation from seed, cut-induced bulb division, and micropropagated bulbs. Finally, different imbibition and post-collection times were evaluated in seed germination assays. The best propagation method was cut-induced bulb division with longitudinal cuts into quarters (T1) while the best conditions for seed germination were 0-day of post-collection and two days of imbibition. The alkaloids analyses of the H. cardenasianus bulbs showed that they are a source of anti-tumoral alkaloids, especially pretazettine (tazettine) and T1 is a sustainable strategy for its propagation and domestication to produce bioactive alkaloids. Keywords: Amaryllidaceae; bioactive alkaloids; GC-MS; propagation methods; biomass productio
Relativistic Effects in the Electromagnetic Current at GeV Energies
We employ a recent approach to the non-relativistic reduction of the
electromagnetic current operator in calculations of electronuclear reactions.
In contrast to the traditional scheme, where approximations are made for the
transferred momentum, transferred energy and initial momentum of the struck
nucleon in obtaining an on-shell inspired form for the current, we treat the
problem exactly for the transferred energy and transferred momentum. We
calculate response functions for the reaction at CEBAF (TJNAF)
energies and find large relativistic corrections. We also show that in Plane
Wave Impulse Approximation, it is always possible to use the full operator, and
we present a comparison of such a limiting case with the results incorporating
relativistic effects to the first order in the initial momentum of the struck
nucleon.Comment: 31 pages, 8 figures, Revte
Relativistic bound-state equations in three dimensions
Firstly, a systematic procedure is derived for obtaining three-dimensional
bound-state equations from four-dimensional ones. Unlike ``quasi-potential
approaches'' this procedure does not involve the use of delta-function
constraints on the relative four-momentum. In the absence of negative-energy
states, the kernels of the three-dimensional equations derived by this
technique may be represented as sums of time-ordered perturbation theory
diagrams. Consequently, such equations have two major advantages over
quasi-potential equations: they may easily be written down in any Lorentz
frame, and they include the meson-retardation effects present in the original
four-dimensional equation. Secondly, a simple four-dimensional equation with
the correct one-body limit is obtained by a reorganization of the generalized
ladder Bethe-Salpeter kernel. Thirdly, our approach to deriving
three-dimensional equations is applied to this four-dimensional equation, thus
yielding a retarded interaction for use in the three-dimensional bound-state
equation of Wallace and Mandelzweig. The resulting three-dimensional equation
has the correct one-body limit and may be systematically improved upon. The
quality of the three-dimensional equation, and our general technique for
deriving such equations, is then tested by calculating bound-state properties
in a scalar field theory using six different bound-state equations. It is found
that equations obtained using the method espoused here approximate the wave
functions obtained from their parent four-dimensional equations significantly
better than the corresponding quasi-potential equations do.Comment: 28 pages, RevTeX, 6 figures attached as postscript files. Accepted
for publication in Phys. Rev. C. Minor changes from original version do not
affect argument or conclusion
Spin-orbit final state interaction in the framework of Glauber theory for (e,e'p) reactions
We investigate the reactions D(e,e'p)n and D(\vec e,e'p)n at GeV energies and
discuss the opportunities to distinguish between different models for the
nuclear ground state by measuring the response functions. In calculating the
final-state interaction (FSI) we employ Glauber theory, and we also include
relativistic effects in the electromagnetic current. We include not only the
central FSI, but also the spin-orbit FSI which is usually neglected in (e,e'p)
calculations within the Glauber framework and we show that this contribution
plays a crucial role for the fifth response function. All of the methods
developed here can be applied to any target nucleus.Comment: 20 pages, 12 figures, minor change in figures 3 and 4 (changed beam
energy), correction of error in figure 4 in the previous replacemen
Deuteron Magnetic and Quadrupole Moments with a Poincar\'e Covariant Current Operator in the Front-Form Dynamics
The deuteron magnetic and quadrupole moments are unambiguosly determined
within the front-form Hamiltonian dynamics, by using a new current operator
which fulfills Poincar\'e, parity and time reversal covariance, together with
hermiticity and the continuity equation. For both quantities the usual
disagreement between theoretical and experimental results is largely removed.Comment: To appear in Phys. Rev. Let
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