2,738 research outputs found
Interfacial elastic relaxation during the ejection of bi-layered tablets
The predilection of a bi-layered tablet to fail in the interface region after its initial formation in the compaction process reduces its practicality as a choice for controlled release solid drug delivery system. Hence, a fundamental appreciation of the governing mechanism that causes the weakening of the interfacial bonds within the bi-layered tablet is crucial in order to improve the overall bi-layered tablet mechanical integrity. This work has shown that the occurrence of the elastic relaxation in the interface region during the ejection stage of the compaction process decreases with the increase in the bi-layered tablet interface strength. This is believed to be due to the increase in the plastic bonding in the interface region. The tablet diametrical elastic relaxation affects the tablet height elastic relaxation, where the impediment of the tablet height expansion is observed when the interface region experiences a diametrical expansion
Helicity-dependent photoabsorption cross sections on the nucleon
We examine the energy dependence of single-meson photoproduction as it
contributes to the Gerasimov-Drell-Hearn (GDH) sum rule. For photon energies
above approximately 1 GeV, through the full resonance region, this contribution
dominates the proton sum rule integral. Over the same energy region, our
single-pion contribution to the neutron sum rule also qualitatively follows a
recent set of GDH data. The predicted neutral-pion contribution to the neutron
sum rule is nearly zero above 1 GeV in this result. The SAID and Mainz (MAID)
results are very different for a number of observables over this energy region.Comment: 7 pages, 5 figur
On the Extraction of Cross Sections for pi0 and eta Photoproduction off Neutrons from Deuteron Data
We discuss the procedure of extracting the photoproduction cross section for
neutral pseudoscalar mesons off neutrons from deuteron data. The main statement
is that the final-state interaction (FSI) corrections for the proton and
neutron target are in general not equal, but for pi0 production there are
special cases were they have to be identical and there are large regions in the
parameter space of incident photon energy and pion polar angle, \theta^*, where
they happen to be quite similar. The corrections for both target nucleons are
practically identical for production in the energy range of the
Delta(1232)3/2+ resonance due to the specific isospin structure of this
excitation. Also above the -isobar range large differences between
proton and neutron correction factors are only predicted for extreme forward
angles ( < 20 deg), but the results are similar for larger angles.
Numerical results for the gp-->pi0p and gn-->pi0n correction factors are
discussed. Also the model description for the available data on the
differential gd-->pi0pn cross sections are given.Comment: 16 pages, 5 figures; v2 fixed several minor typo
The (Non) Influence of Monetary Incentives on Teacher Job Performance in Edo Central Senatorial District, Nigeria
In many developing countries Performance-Based Pay rewards (PBP) are a solution for improving teacher motivation. This study tested examines how teachers in Edo State, Nigeria felt about monetary incentives to increase job performance. Random sampling was used selecting a 20% sample of 164 of 820 teachers. Participants completed a questionnaire, and the data were analyzed using the Pearson Product Moment Correlation Coefficient. The study confirms no significant relationship between monetary incentives and teacher performance. Some possible explanations are provided and conclude that the use of monetary incentives in education in the state of Edo, Nigeria should be further reviewed
Extracting the photoproduction cross section off the neutron gn-->pi-p from deuteron data with FSI effects
The incoherent pion photoproduction reaction gd-->pi-pp is considered
theoretically in a wide energy region Eth =< Eg =< 2700 MeV. The model applied
contains the impulse approximation as well as the NN- and piN-FSI amplitudes.
The aim of the paper is to study a reliable way for getting the information on
elementary gn-->pi-p reaction cross section beyond the impulse approximation
for gd-->pi-pp. For the elementary gN-->piN, NN-->NN, and piN-->piN amplitudes,
the results of the GW DAC are used. There are no additional theoretical
constraints. The calculated cross section dSigma/dOmega(gd->pi-pp) are compared
with existing data. The procedure used to extract information on the
differential cross section dSigma/dOmega(gn-->pi-p) on the neutron from the
deuteron data using the FSI correction factor R is discussed. The calculations
for R versus pi-p CM angle \theta_1 of the outgoing pion are performed at
different photon-beam energies with kinematical cuts for "quasi-free" process
gn-->pi-p. The results show a sizeable FSI effect R \neq 1 from S-wave part of
pp-FSI at small angles close to \theta_1 ~ 0: this region narrows as the photon
energy increases. At larger angles, the effect is small (|R-1|<<1) and agrees
with estimations of FSI in the Glauber approach.Comment: 28 pages, 5 figures, 1 tabl
Ratios of Elastic Scattering of Pions from 3H and 3He
We have measured the elastic-scattering ratios of normalized yields for
charged pions from 3H and 3He in the backward hemisphere. At 180 MeV, we
completed the angular distribution begun with our earlier measurements, adding
six data points in the angular range of 119 deg to 169 deg in the pi-nucleus
center of mass. We also measured an excitation function with data points at
142, 180, 220, and 256 MeV incident pion energy at the largest achievable angle
for each energy between 160 deg and 170 deg in the pi-nucleus center of mass.
This excitation function corresponds to the energies of our forward-hemisphere
studies. The data, taken as a whole, show an apparent role reversal of the two
charge-symmetric ratios r1 and r2 in the backward hemisphere. Also, for data >
100 deg we observe a strong dependence on the four-momentum transfer squared
(-t) for all of the ratios regardless of pion energy or scattering angle, and
we find that the superratio R data match very well with calculations based on
the forward-hemisphere data that predicts the value of the difference between
the even-nucleon radii of 3H and 3He. Comparisons are also made with recent
calculations incorporating different wave functions and double scattering
models.Comment: RevTex 8pages, 12 figure file
-meson in nuclear matter
The -nucleon (N) interactions are deduced from the heavy baryon
chiral perturbation theory up to the next-to-leading-order terms. Combining the
relativistic mean-field theory for nucleon system, we have studied the
in-medium properties of -meson. We find that all the elastic scattering
N interactions come from the next-to-leading-order terms. The N
sigma term is found to be about 280130 MeV. The off-shell terms are also
important to the in-medium properties of -meson. On application of the
latest determination of the N scattering length, the ratio of
-meson effective mass to its vacuum value is near , while
the optical potential is about MeV, at the normal nuclear density.Comment: 8 pages, 3 figures, to appear in PRC, many modification
Are We Missing Important Areas in Pelagic Marine Conservation? Redefining Conservation Hotspots in the Ocean
The protection of biodiversity is one of the most important goals in terrestrial and marine conservation. Marine conservation approaches have traditionally followed the example of terrestrial initiatives. However, patterns, processes, habitats, and threats differ greatly between the 2 systems - and even within the marine environment. As a result, there is still a lack of congruence as to how to best identify and prioritize conservation approaches moving from the static terrestrial and nearshore realm into a more fluid, 3-dimensional pelagic realm. To address this problem, we investigate how the conservation science literature has been used to inform and guide management strategies in the marine system from coastal to pelagic environments. As cumulative impacts on the health of the oceans continue to increase, conservation priorities have shifted to include highly dynamic areas of the pelagic marine system. By evaluating whether priorities match science with current place-based management approaches (i.e. marine protected areas, MPAs), we identify important gaps that must be considered in current conservation schemes. Effective pelagic MPA design requires monitoring and evaluation across multiple physical, biological, and human dimensions. Because many threatened and exploited marine species move through an ephemeral and ever-changing environment, our results highlight the need to move beyond traditional, 2-dimensional approaches to marine conservation, and into dynamic management approaches that incorporate metrics of biodiversity as well as oceanographic features known to promote multilevel, trophic productivity
Coherent photoproduction of pi(+) from He-3
We have measured the differential cross section for the gamma He-3 -\u3e pi(+)t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid He-3 target. The differential cross sections for the gamma He-3 -\u3e pi(+)t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model
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