183 research outputs found
Nuclear Parton Distribution Functions
We study nuclear effects of charged current deep inelastic neutrino-iron
scattering in the framework of a chi^2 analysis of parton distribution
functions (PDFs). We extract a set of iron PDFs which are used to compute
x_Bj-dependent and Q^2-dependent nuclear correction factors for iron structure
functions which are required in global analyses of free nucleon PDFs. We
compare our results with nuclear correction factors from neutrino-nucleus
scattering models and correction factors for charged-lepton--iron scattering.
We find that, except for very high x_Bj, our correction factors differ in both
shape and magnitude from the correction factors of the models and
charged-lepton scattering.Comment: 11 pages, 6 figures, to appear in the proceedings of the Ringberg
Workshop "New Trends in HERA Physics 2008
A large-scale experiment finds no evidence that a seismic survey impacts a demersal fish fauna
Seismic surveys are used to locate oil and gas reserves below the seabed and can be a major source of noise in marine environments. Their effects on commercial fisheries are a subject of debate, with experimental studies often producing results that are difficult to interpret. We overcame these issues in a large-scale experiment that quantified the impacts of exposure to a commercial seismic source on an assemblage of tropical demersal fishes targeted by commercial fisheries on the North West Shelf of Western Australia. We show that there were no short-term (days) or long-term (months) effects of exposure on the composition, abundance, size structure, behavior, or movement of this fauna. These multiple lines of evidence suggest that seismic surveys have little impact on demersal fishes in this environment
One health profile of a community at the wildlife-domestic animal interface, Mpumalanga, South Africa
We used a community engagement approach to develop a One Health profile of an agropastoralist
population at the interface of wildlife areas in eastern South Africa. Representatives
from 262 randomly-selected households participated in an in-person, cross-sectional survey.
Questions were designed to ascertain the participantsâ knowledge, attitudes, and practices with
regard to human health, domestic animal health, and natural resources including wildlife and
water. Surveys were conducted within four selected villages by a team of trained surveyors and
translators over four weeks in July-August 2013. Questions were a combination of multiple
choice (single answer), multiple selection, open-ended, and Likert scale.
The study found that nearly three-quarters of all households surveyed reported owning at
least one animal (55% owned chickens, 31% dogs, 25% cattle, 16% goats, 9% cats, and 5%
pigs). Among the animal-owning respondents, health concerns identified included dissatisfaction
with government-run cattle dip facilities (97%) and frequent morbidity and mortality of chickens
that had clinical signs consistent with Newcastle disease (49%). Sixty-one percent of participants
believed that diseases of animals could be transmitted to humans. Ninety-six percent of
respondents desired greater knowledge about animal diseases. With regard to human health
issues, the primary barrier to health care access was related to transportation to/from the
community health clinics. Environmental health issues revealed by the survey included disparities by village in drinking water reliability and frequent domiciliary rodent sightings
positively associated with increased household size and chicken ownership. Attitudes towards
conservation were generally favorable; however, the community demonstrated a strong
preference for a dichotomous approach to wildlife management, one that separated wildlife from
humans.
Due to the location of the community, which neighbors the Great Limpopo Transfrontier
Conservation Area, and the livestock-dependent lifestyle of the resource-poor inhabitants, a One
Health approach that takes into consideration the interconnectedness of human, animal, and
environmental health is necessary. The community profile described in this study provides a
foundation for health research and planning initiatives that are driven by community engagement
and consider the multitude of factors affecting health at the human-domestic animal-wildlife
interface. Furthermore, it allows for the determination and quantification of the linkages between
human, animal, and environmental health.The project was funded by the UC Davis Deanâs Innovation Fund
and the UC Davis Global Affairs Seed Grant for International Activities.http://www.elsevier.com/locate/prevetmed2017-08-31hb2016Centre for Veterinary Wildlife StudiesVeterinary Tropical Disease
A CsI(Tl) Scintillating Crystal Detector for the Studies of Low Energy Neutrino Interactions
Scintillating crystal detector may offer some potential advantages in the
low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed
near the core of Nuclear Power Station II in Taiwan is being constructed for
the studies of electron-neutrino scatterings and other keV-MeV range neutrino
interactions. The motivations of this detector approach, the physics to be
addressed, the basic experimental design, and the characteristic performance of
prototype modules are described. The expected background channels and their
experimental handles are discussed.Comment: 34 pages, 11 figures, submitted to Nucl. Instrum. Method
Adsorption of mono- and multivalent cat- and anions on DNA molecules
Adsorption of monovalent and multivalent cat- and anions on a deoxyribose
nucleic acid (DNA) molecule from a salt solution is investigated by computer
simulation. The ions are modelled as charged hard spheres, the DNA molecule as
a point charge pattern following the double-helical phosphate strands. The
geometrical shape of the DNA molecules is modelled on different levels ranging
from a simple cylindrical shape to structured models which include the major
and minor grooves between the phosphate strands. The densities of the ions
adsorbed on the phosphate strands, in the major and in the minor grooves are
calculated. First, we find that the adsorption pattern on the DNA surface
depends strongly on its geometrical shape: counterions adsorb preferentially
along the phosphate strands for a cylindrical model shape, but in the minor
groove for a geometrically structured model. Second, we find that an addition
of monovalent salt ions results in an increase of the charge density in the
minor groove while the total charge density of ions adsorbed in the major
groove stays unchanged. The adsorbed ion densities are highly structured along
the minor groove while they are almost smeared along the major groove.
Furthermore, for a fixed amount of added salt, the major groove cationic charge
is independent on the counterion valency. For increasing salt concentration the
major groove is neutralized while the total charge adsorbed in the minor groove
is constant. DNA overcharging is detected for multivalent salt. Simulations for
a larger ion radii, which mimic the effect of the ion hydration, indicate an
increased adsorbtion of cations in the major groove.Comment: 34 pages with 14 figure
The impacts of environmental warming on Odonata: a review
Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns
Risk factors for bacterial zoonotic pathogens in acutely febrile patients in Mpumalanga Province, South Africa
Endemic zoonoses, such as Q fever and spotted fever group (SFG) rickettsiosis, are prevalent in South Africa, yet often undiagnosed. In this study, we reviewed the demographics and animal exposure history of patients presenting with acute febrile illness to community health clinics in Mpumalanga Province to identify trends and risk factors associated with exposure to Coxiella burnetii , the causative agent of Q fever, and infection by SFG Rickettsia spp. Clinical and serological data and questionnaires elucidating exposure to animals and their products were obtained from 141 acutely febrile patients between 2012 and 2016. Exposure or infection status to C. burnetii and SFG Rickettsia spp. was determined by presence of IgG or IgM antibodies. Logistic regression models were built for risk factor analysis. Clinical presentation of patients infected by SFG rickettsiosis was described. There were 37/139 (27%) patients with a positive C. burnetii serology, indicative of Q fever exposure. Patients who had reported attending cattle inspection facilities (âdip tanksâ) were 9.39 times more likely to be exposed to Q fever (95% CI: 2.9â30.4). Exposure risk also increased with age (OR: 1.03, 95% CI: 1.002â1.06). Twentyâone per cent of febrile patients (24/118) had evidence of acute infection by SFG Rickettsia spp. Similarly, attending cattle inspection facilities was the most significant risk factor (OR: 8.48, 95% CI: 1.58â45.60). Seropositivity of females showed a significant OR of 8.0 when compared to males (95% CI: 1.49â43.0), and consumption of livestock was associated with a decreased risk (OR: 0.02, 95% CI: 0.001â0.54). A trend between domestic cat contact and SFG rickettsiosis was also noted, albeit borderline nonâsignificant. In this endemic region of South Africa, an understanding of risk factors for zoonotic pathogens, including exposure to domestic animals, can help clinic staff with diagnosis and appropriate therapeutic management of acutely febrile patients as well as identify target areas for education and prevention strategies.The National Institute for Communicable Disease, the University of Pretoria, and the University of California, Davis.http://wileyonlinelibrary.com/journal/zph2020-08-01hj2020Centre for Veterinary Wildlife StudiesVeterinary Tropical Disease
Observation of the decay \psip\rar\kstark
Using 14 million events collected with the BESII detector,
branching fractions of \psip\rar\kstarkpm and \kstarknn are determined to
be: \calB(\psip\rar\kstarkpm)=(2.9^{+1.3}_{-1.7}\pm0.4)\times 10^{-5} and
\calB(\psip\rar\kstarknn)=(13.3^{+2.4}_{-2.7}\pm1.9)\times 10^{-5}. The
results confirm the violation of the "12%" rule for these two decay channels
with higher precision. A large isospin violation between the charged and
neutral modes is observed.Comment: 5 pages, 3 figure
Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
Nearby clusters and groups of galaxies are potentially bright sources of
high-energy gamma-ray emission resulting from the pair-annihilation of dark
matter particles. However, no significant gamma-ray emission has been detected
so far from clusters in the first 11 months of observations with the Fermi
Large Area Telescope. We interpret this non-detection in terms of constraints
on dark matter particle properties. In particular for leptonic annihilation
final states and particle masses greater than ~200 GeV, gamma-ray emission from
inverse Compton scattering of CMB photons is expected to dominate the dark
matter annihilation signal from clusters, and our gamma-ray limits exclude
large regions of the parameter space that would give a good fit to the recent
anomalous Pamela and Fermi-LAT electron-positron measurements. We also present
constraints on the annihilation of more standard dark matter candidates, such
as the lightest neutralino of supersymmetric models. The constraints are
particularly strong when including the fact that clusters are known to contain
substructure at least on galaxy scales, increasing the expected gamma-ray flux
by a factor of ~5 over a smooth-halo assumption. We also explore the effect of
uncertainties in cluster dark matter density profiles, finding a systematic
uncertainty in the constraints of roughly a factor of two, but similar overall
conclusions. In this work, we focus on deriving limits on dark matter models; a
more general consideration of the Fermi-LAT data on clusters and clusters as
gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo,
minor revisions to be consistent with accepted versio
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