1,505 research outputs found
Small-scale movement and migration cues of Australian bass (Percalates novemaculeata) in an urbanised river
Urban river catchments are often severely affected by human activities but may still retain significant biodiversity. Surprisingly little is known about the behaviour of urban fishes, even those popular with anglers. Key environmental variables that trigger fish behaviour, such as river flow, are highly affected by instream structures including weirs and changes in the natural flow regime. Here, we used acoustic telemetry to examine the movements of Australian bass in a river located in suburban Sydney, Australia. We found that fish tended to be nocturnally active, however, small-scale movements were highly idiosyncratic and less associated with river flow than other factors. Larger-scale movements associated with spawning migrations were strongly correlated with winter floods. Half of the tagged fish migrated to the confluence of the river with Sydney Harbour to breed. Their return migration was hampered by a weir, but the provision of a new fish way facilitated successful return to freshwater at high tide. Despite occupying a highly affected, urban catchment fish behaviour showed similarity to those occupying more natural drainages. Our results highlight the importance of maintaining natural river flows in urban catchments and sustaining fish movement and migration capabilities through the installation of appropriate fish passage devices
Successful vaccination of BALB/c mice against human hookworm (Necator americanus): the immunological phenotype of the protective response
In this murine (BALB/c) model of necatoriasis, high levels of protection against challenge infection by Necator americanus larvae (n = 300) were afforded by successive vaccinations at 14-day intervals, either subcutaneously or percutaneously, with γ-irradiated N. americanus larvae (n = 300). Percutaneous vaccination was significantly more effective than the subcutaneous route, with pulmonary larval burdens at 3 days post-infection being reduced by 97.8% vs. 89.3%, respectively, after three immunisations (p < 0.05). No worms were recovered from the intestines of thrice vaccinated mice. Two percutaneous vaccinations also reduced worm burdens, by 57% in the lungs and 98% in the intestines; p < 0.05. In vaccinated animals, lung pathology (mainly haemorrhage) following infection was greatly reduced compared with non-vaccinated animals. In vaccinated mice (but not in non-vaccinated mice) mast cells accumulated in the skin and were degranulated. RT-PCR analyses of mRNAs in the skin of vaccinated animals indicated increased expression of IL-4 relative to γ-IFN. Lymphocytes from the axillary (skin-draining) lymph nodes of vaccinated mice, stimulated in vitro with concanavalin A, exhibited enhanced secretion of IL-4 protein and a higher Il-4/γ-IFN protein ratio than lymphocytes from non-vaccinated animals. In vaccinated mice, levels of IgG1 and IgG3 (directed against larval excretory/secretory products) were elevated for the most part compared with those in non-vaccinated animals. These data demonstrate the successful vaccination of BALB/c mice against human hookworm infection and suggest that a localised Th2 response may be important for conferring protection against necatoriasis
Solution of the microscopic gap equation for a slab of nuclear matter with the Paris NN-potential
The gap equation in the -channel is solved for a nuclear slab with the
separable form of the Paris potential. The gap equation is considered in the
model space in terms of the effective pairing interaction which is found in the
complementary subspace. The absolute value of the gap turned out to be
very sensitive to the cutoff in the momentum space in the equation
for the effective interaction. It is necessary to take to guarantee 1% accuracy for . The gap equation itself is
solved directly, without any additional approximations. The solution reveals
the surface enhancement of the gap which was earlier found with an
approximate consideration. A strong surface-volume interplay was found also
implying a kind of the proximity effect. The diagonal matrix elements of
turned out to be rather close to the empirical values for heavy atomic
nuclei.Comment: 17 pages, 12 figure
Selenium Content of Forage and Hay Crops in the Pacific Northwest
A map illustrating the Se content of forage and hay
crops in different sections of the Pacific Northwest was
prepared, based on analyses of crop samples. The primary
criterion used in mapping was to delineate areas
where forage and hay crops generally contain insufficient
Se to meet requirements of lambs and calves, and thus
prevent white muscle disease (WMD) and other Se-responsive
diseases. The minimal requirement may vary
from 0.03 to 0.10 ppm Se in the diet, depending upon the
diet level of vitamin E and possibly other substances.
Under normal livestock management practices, WMD
is common when forages and hay contain less than 0.10
ppm Se and the incidence is greater at lower Se levels.
The western half of Washington and Oregon and part
of northern California comprise an extremely low Se
area. The eastern half of Washington, northern Idaho,
extreme western Montana, and the northeast corner of
Oregon comprise a low Se area. Most of the remaining
portion of the Northwest may be considered as variable
in Se, with farm-to-farm variations common, but some
small areas of adequate Se were found and mapped
Quantum inequalities in two dimensional curved spacetimes
We generalize a result of Vollick constraining the possible behaviors of the
renormalized expected stress-energy tensor of a free massless scalar field in
two dimensional spacetimes that are globally conformal to Minkowski spacetime.
Vollick derived a lower bound for the energy density measured by a static
observer in a static spacetime, averaged with respect to the observers proper
time by integrating against a smearing function. Here we extend the result to
arbitrary curves in non-static spacetimes. The proof, like Vollick's proof, is
based on conformal transformations and the use of our earlier optimal bound in
flat Minkowski spacetime. The existence of such a quantum inequality was
previously established by Fewster.Comment: revtex 4, 5 pages, no figures, submitted to Phys. Rev. D. Minor
correction
Serum antioxidants as predictors of the adult respiratory distress syndrome in septic patients
Adult respiratory distress syndrome (ARDS) can develop as a complication of various disorders, including sepsis, but it has not been possible to identify which of the patients at risk will develop this serious disorder. We have investigated the ability of six markers, measured sequentially in blood, to predict development of ARDS in 26 patients with sepsis.
At the initial diagnosis of sepsis (6-24 h before the development of ARDS), serum manganese superoxide dismutase concentration and catalase activity were higher in the 6 patients who subsequently developed ARDS than in 20 patients who did not develop ARDS. These changes in antioxidant enzymes predicted the development of ARDS in septic patients with the same sensitivity, specificity, and efficiency as simultaneous assessments of serum lactate dehydrogenase activity and factor VIII concentration. By contrast, serum glutathione peroxidase activity and α1Pi-elastase complex concentration did not differ at the initial diagnosis of sepsis between patients who did and did not subsequently develop ARDS, and were not as effective in predicting the development of ARDS.
Measurement of manganese superoxide dismutase and catalase, in addition to the other markers, should facilitate identification of patients at highest risk of ARDS and allow prospective treatment
Negative Kaons in Dense Baryonic Matter
Kaon polarization operator in dense baryonic matter of arbitrary isotopic
composition is calculated including s- and p-wave kaon-baryon interactions. The
regular part of the polarization operator is extracted from the realistic
kaon-nucleon interaction based on the chiral and 1/N_c expansion. Contributions
of the Lambda(1116), Sigma(1195), Sigma*(1385) resonances are taken explicitly
into account in the pole and regular terms with inclusion of mean-field
potentials. The baryon-baryon correlations are incorporated and fluctuation
contributions are estimated. Results are applied for K- in neutron star matter.
Within our model a second-order phase transition to the s-wave K- condensate
state occurs at rho_c \gsim 4 \rho_0 once the baryon-baryon correlations are
included. We show that the second-order phase transition to the p-wave
condensate state may occur at densities in
dependence on the parameter choice. We demonstrate that a first-order phase
transition to a proton-enriched (approximately isospin-symmetric) nucleon
matter with a p-wave K- condensate can occur at smaller densities, \rho\lsim 2
\rho_0. The transition is accompanied by the suppression of hyperon
concentrations.Comment: 41 pages, 24 figures, revtex4 styl
Strangeness production time and the K+/pi+ horn
We construct a hadronic kinetic model which describes production of strange
particles in ultrarelativistic nuclear collisions in the energy domain of SPS.
We test this model on description of the sharp peak in the excitation function
of multiplicity ratio K+/pi+ and demonstrate that hadronic model reproduces
these data rather well. The model thus must be tested on other types of data in
order to verify the hypothesis that deconfinement sets in at lowest SPS
energies.Comment: proceedings of Hot Quarks 0
Enhancement of fusion rates due to quantum effects in the particles momentum distribution in nonideal media
This study concerns a situation when measurements of the nonresonant
cross-section of nuclear reactions appear highly dependent on the environment
in which the particles interact. An appealing example discussed in the paper is
the interaction of a deuteron beam with a target of deuterated metal Ta. In
these experiments, the reaction cross section for d(d,p)t was shown to be
orders of magnitude greater than what the conventional model predicts for the
low-energy particles. In this paper we take into account the influence of
quantum effects due to the Heisenberg uncertainty principle for particles in a
non-ideal medium elastically interacting with the medium particles. In order to
calculate the nuclear reaction rate in the non-ideal environment we apply both
the Monte Carlo technique and approximate analytical calculation of the Feynman
diagram using nonrelativistic kinetic Green's functions in the medium which
correspond to the generalized energy and momentum distribution functions of
interacting particles. We show a possibility to reduce the 12-fold integral
corresponding to this diagram to a fivefold integral. This can significantly
speed up the computation and control accuracy. Our calculations show that
quantum effects significantly influence reaction rates such as p +7Be, 3He
+4He, p +7Li, and 12C +12C. The new reaction rates may be much higher than the
classical ones for the interior of the Sun and supernova stars. The possibility
to observe the theoretical predictions under laboratory conditions is
discussed
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