4,664 research outputs found
Linking anthropogenic resources to wildlife-pathogen dynamics: a review and meta-analysis
Urbanisation and agriculture cause declines for many wildlife, but some species benefit from novelresources, especially food, provided in human-dominated habitats. Resulting shifts in wildlife ecol-ogy can alter infectious disease dynamics and create opportunities for cross-species transmission,yet predicting host–pathogen responses to resource provisioning is challenging. Factors enhancingtransmission, such as increased aggregation, could be offset by better host immunity due toimproved nutrition. Here, we conduct a review and meta-analysis to show that food provisioningresults in highly heterogeneous infection outcomes that depend on pathogen type and anthropo-genic food source. We also find empirical support for behavioural and immune mechanismsthrough which human-provided resources alter host exposure and tolerance to pathogens. Areview of recent theoretical models of resource provisioning and infection dynamics shows thatchanges in host contact rates and immunity produce strong non-linear responses in pathogen inva-sion and prevalence. By integrating results of our meta-analysis back into a theoretical frame-work, we find provisioning amplifies pathogen invasion under increased host aggregation andtolerance, but reduces transmission if provisioned food decreases dietary exposure to parasites.These results carry implications for wildlife disease management and highlight areas for futurework, such as how resource shifts might affect virulence evolution
Improved Predictions of Neutron Detection Efficiency for Hydrocarbon Scintillators from 1 MeV to About 300 MeV
This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit
Applicability of the Fisher Equation to Bacterial Population Dynamics
The applicability of the Fisher equation, which combines diffusion with
logistic nonlinearity, to population dynamics of bacterial colonies is studied
with the help of explicit analytic solutions for the spatial distribution of a
stationary bacterial population under a static mask. The mask protects the
bacteria from ultraviolet light. The solution, which is in terms of Jacobian
elliptic functions, is used to provide a practical prescription to extract
Fisher equation parameters from observations and to decide on the validity of
the Fisher equation.Comment: 5 pages, 3 figs. include
Ripple and kink dynamics
We propose a relevant modification of the Nishimori-Ouchi model [{\em Phys.
Rev. Lett.} {\bf 71}, 197 (1993)] for granular landscape erosion. We explicitly
introduce a new parameter: the angle of repose , and a new process:
avalanches. We show that the parameter leads to an asymmetry of the
ripples, as observed in natural patterns. The temporal evolution of the maximum
ripple height is limited and not linear, according to recent
observations. The ripple symmetry and the kink dynamics are studied and
discussed.Comment: 7 pages, 10 figure, RevTe
The spectrum of the random environment and localization of noise
We consider random walk on a mildly random environment on finite transitive
d- regular graphs of increasing girth. After scaling and centering, the
analytic spectrum of the transition matrix converges in distribution to a
Gaussian noise. An interesting phenomenon occurs at d = 2: as the limit graph
changes from a regular tree to the integers, the noise becomes localized.Comment: 18 pages, 1 figur
The (p,t) Reaction at Higher Energy
This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit
Metal-insulator transition in one-dimensional lattices with chaotic energy sequences
We study electronic transport through a one-dimensional array of sites by
using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic
sequence. The correlation degree between these energies is controlled by a
parameter regulating the dynamic Lyapunov exponent measuring the degree of
chaos. We observe the effect of chaotic sequences on the localization length,
conductance, conductance distribution and wave function, finding evidence of a
Metal-Insulator Transition (MIT) at a critical degree of chaos. The
one-dimensional metallic phase is characterized by a Gaussian conductance
distribution and exhibits a peculiar non-selfaveraging.Comment: 5 pages, 5 figures (one figure replaced). Includes new results and a
few additional references. Improved style for publication. Accepted in
Physics Letters
Order of Two-Dimensional Isotropic Dipolar Antiferromagnets
The question of the existence of order in two-dimensional isotropic dipolar
Heisenberg antiferromagnets is studied. It is shown that the dipolar
interaction leads to a gap in the spin-wave energy and a nonvanishing order
parameter. The resulting finite N\'eel-temperature is calculated for a square
lattice by means of linear spin-wave theory.Comment: 10 pages, REVTEX, 1 figure available upon request, TUM-CP-93-0
Goserelin, as an ovarian protector during (neo)adjuvant breast cancer chemotherapy, prevents long term altered bone turnover
Background: The Ovarian Protection Trial In Premenopausal Breast Cancer Patients “OPTION” trial
(NCT00427245) was a prospective, multicenter, randomised, open label study evaluating the frequency of
primary ovarian insufficiency (POI) at 12 months in women randomised to 6–8 cycles of (neo)adjuvant
chemotherapy (CT) þ/ goserelin (G). Here we report the results of a secondary endpoint analysis of the
effects of CTþ/-G on markers of bone turnover.
Methods: Serum for bone alkaline phosphatase (BALP) and urine for N-terminal telopeptide (NTX) were
collected at baseline, 6, 12, 18, 24 and 36 months. Changes in median levels of bone turnover markers
were evaluated for the overall population, according to age stratification at randomisation (r40 vs 440
years) and with exploratory analysis according to POI rates at 12 months.
Results: In the overall population, there was a significant increase in NTX at 6 months compared to
baseline in patients treated with CTþG (40.81 vs 57.82 p¼0.0074) with normalisation of levels thereafter.
BALP was significantly increased compared to baseline at 6 months and 12 months in those receiving
CTþG, but normalised thereafter. BALP remained significantly higher compared to baseline at 12, 24 and
36 months in patients receiving CT, resulting in a significant difference between treatment groups at 36
months (CTþG 5.845 vs CT 8.5 p¼0.0006). These changes were predominantly seen in women 440
years. Women with POI at 12 months showed altered bone formation compared to baseline levels for a
longer duration than women who maintained menses.
Conclusion: Addition of G to CT increases bone turnover during treatment with normalisation after
cessation of treatment suggesting G may offer sufficient ovarian protection against CT induced POI to
negate longstanding altered bone turnover associated with POI
Formation of soliton trains in Bose-Einstein condensates as a nonlinear Fresnel diffraction of matter waves
The problem of generation of atomic soliton trains in elongated Bose-Einstein
condensates is considered in framework of Whitham theory of modulations of
nonlinear waves. Complete analytical solution is presented for the case when
the initial density distribution has sharp enough boundaries. In this case the
process of soliton train formation can be viewed as a nonlinear Fresnel
diffraction of matter waves. Theoretical predictions are compared with results
of numerical simulations of one- and three-dimensional Gross-Pitaevskii
equation and with experimental data on formation of Bose-Einstein bright
solitons in cigar-shaped traps.Comment: 8 pages, 3 figure
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