11,645 research outputs found
Responses of a bacterial pathogen to phosphorus limitation of its aquatic invertebrate host
Host nutrition is thought to affect the establishment, persistence, and severity of pathogenic infections. Nutrient-deficient foods possibly benefit pathogens by constraining host immune function or benefit hosts by limiting parasite growth and reproduction. However, the effects of poor elemental food quality on a host's susceptibility to infection and disease have received little study. Here we show that the bacterial microparasite Pasteuria ramosa is affected by the elemental nutrition of its aquatic invertebrate host, Daphnia magna. We found that high food carbon : phosphorus (C: P) ratios significantly reduced infection rates of Pasteuria in Daphnia and led to lower within-host pathogen multiplication. In addition, greater virulent effects of bacterial infection on host reproduction were found in Daphnia-consuming P-deficient food. Poor Daphnia elemental nutrition thus reduced the growth and reproduction of its bacterial parasite, Pasteuria. The effects of poor host nutrition on the pathogen were further evidenced by Pasteuria's greater inhibition of reproduction in P-limited Daphnia. Our results provide strong evidence that elemental food quality can significantly influence the incidence and intensity of infectious disease in invertebrate hosts
Periodicity of high-order functions in the CNS Final progress report, year ending 30 Jun. 1971
Analysis of cerebral slow potentials underlying human attentive processes in central nervous syste
Analysis of data from NASA B-57B gust gradient program
Statistical analysis of the turbulence measured in flight 6 of the NASA B-57B over Denver, Colorado, from July 7 to July 23, 1982 included the calculations of average turbulence parameters, integral length scales, probability density functions, single point autocorrelation coefficients, two point autocorrelation coefficients, normalized autospectra, normalized two point autospectra, and two point cross sectra for gust velocities. The single point autocorrelation coefficients were compared with the theoretical model developed by von Karman. Theoretical analyses were developed which address the effects spanwise gust distributions, using two point spatial turbulence correlations
Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering
We report measurements of the magnetic excitation spectrum of the layered
antiferromagnet La2CoO4 by time-of-flight neutron inelastic scattering. In the
energy range probed in our experiments (0-250 meV) the magnetic spectrum
consists of spin-wave modes with strong in-plane dispersion extending up to 60
meV, and a nearly dispersionless peak at 190 meV. The spin-wave modes exhibit a
small (~1 meV) dispersion along the magnetic zone boundary. We show that the
magnetic spectrum can be described very well by a model of a Heisenberg
antiferromagnet that includes the full spin and orbital degrees of freedom of
Co2+ in an axially-distorted crystal field. The collective magnetic dynamics
are found to be controlled by dominant nearest-neighbour exchange interactions,
strong XY-like single-ion anisotropy and a substantial unquenched orbital
angular momentum.Comment: 8 pages, 7 figure
The Effect of Silage Harvester Type on Harvesting Efficiency
Choice of harvesting system can significantly influence production costs. Whether a tractor-powered or self-propelled forage harvester or a self-loading forage wagon system is used will depend on particular circumstances. However, in order to make an informed choice relevant information has to be available. A trial was commissioned by Landmec Pottinger (Ivybridge, UK) and Traynors (Clonmel, Ireland) at this Institute to investigate the performance of a self-propelled forage harvester system and a self-loading forage wagon system
Dairy Cow Performance Associated with Two Contrasting Silage Feeding Systems
As a result of increasing labour costs, the lack of skilled labour, and the desire of many farmers to reduce their working hours, there is considerable interest in using simple feeding systems for dairy cows. A study was conducted to compare two silage feeding systems that differed in complexity
Transformations of Progesterone by Subcellular Fractions of Human Skin
Homogenates of human skin metabolize progesterone-4-14C to the same products as whole skin. Studies with subcellular fractions obtained by differential centrifugation indicate the presence in skin of a membrane-bound 5α-reductase and a soluble 20α-hydroxysteroid dehydrogenase (20α-HSD), both of which utilize TPNH as cofactor. The 20α-HSD has a pH optimum of 6.2 and a Km of approximately 7 ÎŒM. Unlike placental preparations, the 105,000 Ă g supernatant fraction prepared from human skin has more 20α-HSD than 17ÎČ-hydroxy-steroid dehydrogenase activity. This soluble skin enzyme acting on steroid hormones is distinct from previously reported particulate enzymes
Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source
The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10âMeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 107. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays
FliPpr: A Prettier Invertible Printing System
When implementing a programming language, we often write
a parser and a pretty-printer. However, manually writing both programs
is not only tedious but also error-prone; it may happen that a pretty-printed
result is not correctly parsed. In this paper, we propose FliPpr,
which is a program transformation system that uses program inversion
to produce a CFG parser from a pretty-printer. This novel approach
has the advantages of fine-grained control over pretty-printing, and easy
reuse of existing efficient pretty-printer and parser implementations
- âŠ