3,398 research outputs found
Life History Attributes of Asian Carps in the Upper Mississippi River System
INTRODUCTION: The Upper Mississippi River (UMR) system starts at the confluence of the Ohio River at Cairo, Illinois, and serves as a conduit for many aquatic invasive species to enter the waterways of the central and northern interior of the United States, including the Great Lakes. One well-established group found in this waterway is the Asian carps including the common carp Cyprinus carpio, grass carp Ctenopharyngodon idella, and two recent invaders, the bighead car
Partonic Energy Loss and the Drell-Yan Process
We examine the current status of the extraction of the rate of partonic
energy loss in nuclei from A dependent data. The advantages and difficulties of
using the Drell-Yan process to measure the energy loss of a parton traversing a
cold nuclear medium are discussed. The prospects of using relatively low energy
proton beams for a definitive measurement of partonic energy loss are
presented.Comment: 12 pages, 2 figure
Probing Nucleon Strangeness with Neutrinos: Nuclear Model Dependences
The extraction of the nucleon's strangeness axial charge, Delta_s, from
inclusive, quasielastic neutral current neutrino cross sections is studied
within the framework of the plane-wave impulse approximation. We find that the
value of Delta_s can depend significantly on the choice of nuclear model used
in analyzing the quasielastic cross section. This model-dependence may be
reduced by one order of magnitude when Delta_s is extracted from the ratio of
total proton to neutron yields. We apply this analysis to the interpretation of
low-energy neutrino cross sections and arrive at a nuclear theory uncertainty
of plus/minus 0.03 on the value of Delta_s expected to be determined from the
ratio of proton and neutron yields measured by the LSND collaboration. This
error compares favorably with estimates of the SU(3)-breaking uncertainty in
the value of Delta_s extracted from inclusive, polarized deep-inelastic
structure function measurements. We also point out several general features of
the quasielastic neutral current neutrino cross section and compare them with
the analogous features in inclusive, quasielastic electron scattering.Comment: 40 pages (including 11 postscript figures), uses REVTeX and
epsfig.st
The Angular Correlations in the Decay of Excited States in 8Be
Motivated by the recent observation of anomalous electron-positron angular
correlations in the decay of the 18.15 MeV 1+ excited states in 8Be, we
reexamine in detail the Standard Model expectations for these angular
correlations. The 18.15 MeV state is above particle threshold, and several
multipoles can contribute to its decay. We present the general
theoretical expressions for angular distributions for nuclear decay by
C0, C1, C2 M1, E1, and E2 multipoles, and we examine their relative
contribution to the decay of 8Be at 18.15 MeV. We find that this
resonance is dominated by M1 and E1 decay, and that the ratio of M1 to E1
strength is a strong function of energy. This is in contract to the original
analysis of the angular distributions, where the M1/E1 ratio was
assumed to be a constant over the energy region Ep = 0:8-1:2 MeV. We find that
the existence of a `bump' in the measured angular distribution is strongly
dependent on the assumed M1/E1 ratio, with the present analysis finding the
measured large-angle contributions to the angular distribution to be
lower than expectation. Thus, in the current analysis we find no evidence for
axion decay in the 18.15 MeV resonance region of 8Be
Energy Loss Effect in High Energy Nuclear Drell-Yan Process
The energy loss effect in nuclear matter, which is another nuclear effect
apart from the nuclear effect on the parton distribution as in deep inelastic
scattering process, can be measured best by the nuclear dependence of the high
energy nuclear Drell-Yan process. By means of the nuclear parton distribution
studied only with lepton deep inelastic scattering experimental data, measured
Drell-Yan production cross sections for 800GeV proton incident on a variety of
nuclear targets are analyzed within Glauber framework which takes into account
energy loss of the beam proton. It is shown that the theoretical results with
considering the energy loss effect are in good agreement with the FNAL E866
Spleen stiffness measurements using point shear wave elastography detects noncirrhotic portal hypertension in human immunodeficiency virus
Objectives:To assess the utility of spleen stiffness as a diagnostic tool inindividuals withHIV andnon-cirrhotic portal hypertension(NCPH).Design:The Philips EPIQ7TM, a newpoint shearwave elastography (pSWE) technique, was used to assess liver and spleen stiffnessin3 patient groups. Group1:HIV and NCPH(n=11); Group 2: HIV withpast didanosine(ddI) exposure without known liver disease or NCPH(n=5), Group 3: HIV without known liver disease or ddI exposure(n=9). Methods:Groups were matched for age, HIV chronicity and antiretroviral treatment (including cumulative ddI exposure in Groups 1 and 2). Differences in liver and spleen stiffness (in kPa) between groups were analysed using the Mann-Whiney U test.Results:Liver and spleen stiffness were both significantly higher in NCPH vs ddI-exposed (p=0.019 and p=0.006) and ddI-unexposed controls (p=0.038 and p<0.001). Spleen stiffness was more effective than liver stiffness at predicting NCPH, AUROC 0.812 vs 0.948. Combining the two variables improved the diagnostic performance, AUROC 0.961. The optimal cut-off for predicting NCPH using splenic stiffness was 25.4kPa, with sensitivity 91%, specificity 93%, PPV 91%, NPV 93%, positive likelihood ratio 12.73, negative likelihood ratio 0.10. Spleen and liver stiffness scores were strongly correlated (p=0.0004 95%CI 18,59). Conclusions:Elevated spleen stiffness is observed in HIV with NCPH and can be quantified easily using pSWE with high diagnostic accuracy. Novel strategies such as pSWE for longitudinal monitoring of patients with HIV and NCPH should be considered
Risky behaviors performed by the piglet 72 hours after parturition that can contribute to pre-weaning mortality when housed in farrowing huts
The objective was to compare the behavior of loose-housed outdoor litters that had one or more piglet mortalities (CR; n=4) compared to litters where no mortalities occurred (NC; n=4). The litter of piglets was observed using 10-min scan samples over 72 h from birth and individual piglets were continually observed 1 h prior to death. Postures, nursing, unknown, location within the hut, and vicinity to the sow were determined. There were no differences observed for any measures 1 h before a piglet\u27s death. There were no differences for treatment or day by treatment over the 72 h for behaviors or vicinity to sow. There was a day effect with piglets becoming more inactive and nursing less often from d1 to d3. There was a day effect for vicinity to sow with piglets spending less time by the sow over the 3 d. Few behavioral differences were observed between treatments
Why, what, and how? case study on law, risk, and decision making as necessary themes in built environment teaching
The paper considers (and defends) the necessity of including legal studies as a core part of built environment undergraduate and postgraduate curricula. The writer reflects upon his own experience as a lawyer working alongside and advising built environment professionals in complex land remediation and site safety management situations in the United Kingdom and explains how themes of liability, risk, and decision making can be integrated into a practical simulation in order to underpin more traditional lecture-based law teaching. Through reflection upon the writer's experiments with simulation-based teaching, the paper suggests some innovations that may better orientate law teaching to engage these themes and, thereby, enhance the relevance of law studies to the future needs of built environment professionals in practice.</p
Exchange Current Corrections to Neutrino--Nucleus Scattering
Relativistic exchange current corrections to neutrino--nucleus cross sections
are presented assuming non--vanishing strange quark form factors for the
constituent nucleons. For charged current processes the exchange current
corrections can lower the impulse approximation results by 10\% while these
corrections are found to be sensitive to both the nuclear density and the
strange quark axial form factor of the nucleon for neutral current processes.
Implications on the LSND experiment to determine this form factor are
discussed.Comment: 11 pages, 2 figures, revtex 3.0, full postscript version of the file
and figures available at
http://www.nikhefk.nikhef.nl/projects/Theory/preprints/preprints.html To
appear in Phys. Rev. Lett
A STRANGE MESONIC TRANSITION FORM FACTOR
The strange-quark vector current -to- meson transition form factor
is computed at one-loop order using strange meson intermediate states. A
comparison is made with a -meson dominance model estimate. We find that
one-loop contributions are comparable in magnitude to those predicted by
-meson dominance. It is possible that the one-loop contribution can make
the matrix element as large as those of the electromagnetic current mediating
vector meson radiative decays. However, due to the quadratic dependence of the
one-loop results on the hadronic form factor cut-off mass, a large uncertainty
in the estimate of the loops is unavoidable. These results indicate that
non-nucleonic strange quarks could contribute appreciably in moderate-
parity-violating electron-nucleus scattering measurements aimed at probing the
strange-quark content of the nucleon.Comment: Revtex, six figures available as hard copy upon request
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