13,226 research outputs found
Sustainable production of organic wheat
The aim of the project is to use an ecological approach to analyse the interactions of a range of key agronomic variables in organic wheat production (wheat genotype, spatial arrangement of seed, seed density and wheat/white clover bi-cropping) to determine an optimal approach to improved and stabilised production. The fi rst set of data revealed that seedling competition was infl uenced by seed rate and drilling arrangement. Furthermore, the variety Hereward had increased emergence and establishment to Aristos. An interaction exists between wheat variety, seed rate and drilling arrangement on the level of canopy cover at different developmental stages – these factors are important for the suppression of weeds. The input of farmers in the selection of trial variables ensures results have a direct application to the industry. The results of yield and quality at harvest will provide further insights into the interaction of agronomic variables
Plasmas in Saturn's magnetosphere
The solar wind plasma analyzer on board Pioneer 2 provides first observations of low-energy positive ions in the magnetosphere of Saturn. Measurable intensities of ions within the energy-per-unit charge (E/Q) range 100 eV to 8 keV are present over the planetocentric radial distance range about 4 to 16 R sub S in the dayside magnetosphere. The plasmas are found to be rigidly corotating with the planet out to distances of at least 10 R sub S. At radial distances beyond 10 R sub S, the bulk flows appear to be in the corotation direction but with lesser speeds than those expected from rigid corotation. At radial distances beyond the orbit of Rhea at 8.8 R sub S, the dominant ions are most likely protons and the corresponding typical densities and temperatures are 0.5/cu cm and 1,000,000 K, respectively, with substantial fluctuations. It is concluded that the most likely source of these plasmas in the photodissociation of water frost on the surface of the ring material with subsequent ionization of the products and radially outward diffusion. The presence of this plasma torus is expected to have a large influence on the dynamics of Saturn's magnetosphere since the pressure ratio beta of these plasmas approaches unity at radial distances as close to the planet as 6.5 R sub S. On the basis of these observational evidences it is anticipated that quasi-periodic outward flows of plasma, accompanied with a reconfiguration of the magnetosphere beyond about 6.5 R sub S, will occur in the local night sector in order to relieve the plasma pressure from accretion of plasma from the rings
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If You Don’t Find It Often, You Often Don’t Find It: Why Some Cancers Are Missed in Breast Cancer Screening
Mammography is an important tool in the early detection of breast cancer. However, the perceptual task is difficult and a significant proportion of cancers are missed. Visual search experiments show that miss (false negative) errors are elevated when targets are rare (low prevalence) but it is unknown if low prevalence is a significant factor under real world, clinical conditions. Here we show that expert mammographers in a real, low-prevalence, clinical setting, miss a much higher percentage of cancers than are missed when the mammographers search for the same cancers under high prevalence conditions. We inserted 50 positive and 50 negative cases into the normal workflow of the breast cancer screening service of an urban hospital over the course of nine months. This rate was slow enough not to markedly raise disease prevalence in the radiologists’ daily practice. Six radiologists subsequently reviewed all 100 cases in a session where the prevalence of disease was 50%. In the clinical setting, participants missed 30% of the cancers. In the high prevalence setting, participants missed just 12% of the same cancers. Under most circumstances, this low prevalence effect is probably adaptive. It is usually wise to be conservative about reporting events with very low base rates (Was that a flying saucer? Probably not.). However, while this response to low prevalence appears to be strongly engrained in human visual search mechanisms, it may not be as adaptive in socially important, low prevalence tasks like medical screening. While the results of any one study must be interpreted cautiously, these data are consistent with the conclusion that this behavioral response to low prevalence could be a substantial contributor to miss errors in breast cancer screening
Developing collaborative partnerships with culturally and linguistically diverse families during the IEP process
Family participation in the special education process has been federally mandated for 40 years, and educators recognize that effective collaboration with their students’ families leads to improved academic and social outcomes for students. However, while some family-school relationships are positive and collaborative, many are not, particularly for culturally and linguistically diverse (CLD) families. This article provides practice guidelines based in research for teachers who seek to improve their practices when working with CLD families who have children served by special education
Inflation-Produced Magnetic Fields in R^n F^2 and I F^2 models
We re-analyze the production of seed magnetic fields during Inflation in
(R/m^2)^n F_{\mu \nu}F^{\mu \nu} and I F_{\mu \nu}F^{\mu \nu} models, where n
is a positive integer, R the Ricci scalar, m a mass parameter, and I \propto
\eta^\alpha a power-law function of the conformal time \eta, with \alpha a
positive real number. If m is the electron mass, the produced fields are
uninterestingly small for all n. Taking m as a free parameter we find that, for
n \geq 2, the produced magnetic fields can be sufficiently strong in order to
seed dynamo mechanism and then to explain galactic magnetism. For \alpha
\gtrsim 2, there is always a window in the parameters defining Inflation such
that the generated magnetic fields are astrophysically interesting. Moreover,
if Inflation is (almost) de Sitter and the produced fields almost
scale-invariant (\alpha \simeq 4), their intensity can be strong enough to
directly explain the presence of microgauss galactic magnetic fields.Comment: 5 pages, 2 figures. Minor revisions. References added. Accepted for
publication in Phys. Rev.
Alligator Feeding Habits: New Data and a Review
Nutria (Myocastor coypus) and muskrats (Ondatra zibethicus) are the predominant food items of alligators over 1.5 min length in southeastern Louisiana. Our data and a review of the literature on alligator diets indicate that the mammals are apparently major components of the diet of large alligators over much of their range, with fishes and crustaceans being more important to smaller alligators
Preliminary catalog of pictures taken on the lunar surface during the Apollo 15 mission
Catalog of all pictures taken from lunar module or lunar surface during Apollo 15 missio
The Broadband Spectrum of Galaxy Clusters
We examine whether nonthermal protons energized during a cluster merger are
simultaneously responsible for the Coma cluster's diffuse radio flux (via
secondary decay) and the departure of its intra-cluster medium (ICM) from a
thermal profile via Coulomb collisions between the quasithermal electrons and
the hadrons. Rather than approximating the influence of nonthermal
proton/thermal electron collisions as extremely rare events which cause an
injection of nonthermal, power-law electrons (the `knock-on' approximation), we
self-consistently solve (to our knowledge, for the first time) the covariant
kinetic equations for the two populations. The electron population resulting
from these collisions is out of equilibrium, yet not a power law, and
importantly displays a higher bremsstrahlung radiative efficiency than a pure
power law. Observations with GLAST will test this model directly.Comment: Accepted for publication in Ap
Elm Farm Organic Research Centre Bulletin 83 April 2006
Regular bulleting with technical updates from Organic Advisory Service
Issue contains:
Testing for Tolerance - a pragmatic view GM Debate
Vaccination nation - to jab or not to jab Future shape of OCIS
Evolutionary wheat makes the grade? NIAB tracks health of organic cereal seed
Stopping erosion of soil quality - the organic way
Care needed to halt butterfly collapse
Aspects of poultry behaviour: How free range is free range?
On choosing an organic wheat A local education challenge
New Wakelyns Science Building Organic vegetable market growt
Neutrinos and Gamma Rays from Galaxy Clusters
The next generation of neutrino and gamma-ray detectors should provide new
insights into the creation and propagation of high-energy protons within galaxy
clusters, probing both the particle physics of cosmic rays interacting with the
background medium and the mechanisms for high-energy particle production within
the cluster. In this paper we examine the possible detection of gamma-rays (via
the GLAST satellite) and neutrinos (via the ICECUBE and Auger experiments) from
the Coma cluster of galaxies, as well as for the gamma-ray bright clusters
Abell 85, 1758, and 1914. These three were selected from their possible
association with unidentified EGRET sources, so it is not yet entirely certain
that their gamma-rays are indeed produced diffusively within the intracluster
medium, as opposed to AGNs. It is not obvious why these inconspicuous
Abell-clusters should be the first to be seen in gamma-rays, but a possible
reason is that all of them show direct evidence of recent or ongoing mergers.
Their identification with the EGRET gamma-ray sources is also supported by the
close correlation between their radio and (purported) gamma-ray fluxes. Under
favorable conditions (including a proton spectral index of 2.5 in the case of
Abell 85, and sim 2.3 for Coma, and Abell 1758 and 1914), we expect ICECUBE to
make as many as 0.3 neutrino detections per year from the Coma cluster of
galaxies, and as many as a few per year from the Abell clusters 85, 1758, and
1914. Also, Auger may detect as many as 2 events per decade at ~ EeV energies
from these gamma-ray bright clusters.Comment: Accepted for publication in Ap
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