7,785 research outputs found
Quick-disconnect coupling safe transfer of hazardous fluids
Quick-disconnect coupling is used for uncoupling of plumbing during ground-to-vehicle transfer of cryogenic and hazardous fluids. The coupling allows remote positive control of liquid pressure and flow during the transfer operation, remote connection and separation capabilities, and negligible liquid spillage upon disconnection
Lensing Properties of Cored Galaxy Models
A method is developed to evaluate the magnifications of the images of
galaxies with lensing potentials stratified on similar concentric ellipses. A
simple contour integral is provided which enables the sums of the
magnifications of even parity or odd parity or the central image to be easily
calculated. The sums for pairs of images vary considerably with source
position, while the signed sums can be remarkably uniform inside the tangential
caustic in the absence of naked cusps. For a family of models in which the
potential is a power-law of the elliptic radius, the number of visible images
is found as a function of flattening, external shear and core radius. The
magnification of the central image depends on the core radius and the slope of
the potential. For typical source and lens redshifts, the missing central image
leads to strong constraints; the mass distribution in the lensing galaxy must
be nearly cusped, and the cusp must be isothermal or stronger. This is in
accord with the cuspy cores seen in high resolution photometry of nearby,
massive, early-type galaxies, which typically have the surface density falling
like distance^{-1.3} outside a break radius of a few hundred parsecs. Cuspy
cores by themselves can provide an explanation of the missing central images.
Dark matter at large radii may alter the slope of the projected density;
provided the slope remains isothermal or steeper and the break radius remains
small, then the central image remains unobservable. The sensitivity of the
radio maps must be increased fifty-fold to find the central images in
abundance.Comment: 42 pages, 11 figures, ApJ in pres
Double layers on auroral field lines
Time-stationary solutions to the Vlasov-Poisson equation for ion holes and double layers were examined along with particle simulations which pertain to recent observations of small amplitude (e phi)/t sub e approx. 1 electric field structures on auroral field lines. Both the time-stationary analysis and the simulations suggest that double layers evolve from holes in ion phase space when their amplitude reaches (e phi)/t sub e approx. 1. Multiple small amplitude double layers which are seen in long simulation systems and are seen to propagate past spacecraft may account for the acceleration of plasma sheet electrons to produce the discrete aurora
Photon Orbital Angular Momentum in Astrophysics
Astronomical observations of the orbital angular momentum of photons, a
property of electromagnetic radiation that has come to the fore in recent
years, have apparently never been attempted. Here, I show that measurements of
this property of photons have a number of astrophysical applications.Comment: 17 pages plus two figure
Weed Management in Alfalfa
Weeds compete with alfalfa for water, nutrients, light, and space. This competition can decrease yields, lower forage quality, increase disease and insect problems, create harvesting problems, and initiate or poison the animals which will consume the forage. Premature loss of alfalfa stands is usually the result of the interaction of the pest complex - diseases, insects, and weeds
Herbicides for Alfalfa Weed Control
Numerous herbicides are available for controlling weeds in pure or mixed stands of alfalfa. In addition, these herbicides can be applied at different times and stages of alfalfa growth -from prior to planting to actively growing alfalfa to dormant applications during the winter. To be confident of achieving the desired weed control, it is important to apply alfalfa herbicides at the proper growth stage and rate.
The following tables contain information pertinent to proper utilization of the herbicides to obtain maximum weed control
New Developments in Pasture Weed Control
Weeds in pastures continue to offer challenges to the producer for controlling these unwanted plants. The combination of forage grasses grown in pastures and the climate of Kentucky provides an environment that is conducive for having numerous weedy species. Most pastures have a combination of cool season (those that begin growth in fall and mature in spring or early summer) and warm season (those that begin growth in spring and mature in late summer or fall) weeds. Additionally, some weeds such as thistles severely restrict grazing while other weeds do not. The decision to apply a weed management strategy is often difficult because of the wide array of weedy species and because some weeds cause little forage reduction
Using Anthropogenic Risks to Inform Salmonid Conservation at the Landscape Scale
The expansion and industrialization of humanity has caused many unforeseen consequences to the natural world. Due to the importance of freshwater for people, rivers have been particularly altered to meet human needs, often at the expense of the natural world. Supplying water for farms, industries, and cities has reshaped the natural state of rivers by altering river paths, chemistry, and species compositions. These changes have harmed many species that prospered before widespread human alterations, including the native trout and salmon of western North America. As human populations continue to grow, new threats will surface for rivers, and the trout and salmon that call rivers home. As a result, many scientists have considered how to assess and counter-act threats to trout and salmon. Often, efforts focus around rehabilitating stretches of river, but do not consider large-scale watershed conditions,which may be responsible for chronic stream degradation. Tools have been developed to guide decision making for coordinating conservation efforts that consider the multitude of risks facing trout and salmon. In this thesis I implemented these tools to help managers and decision makers understand how risks affect their conservation efforts. Two examples are provided, with the first considering development and resource extraction risks to Pacific salmon spawning habitat in Alaska. The second example considers climate, development, and competition risks for cutthroat trout, throughout Utah. Results from both examples clarify that managers who consider risks while conducting conservation yield greater results than managers who attempt to avoid risks. The findings here intend to inform future conservation effort for trout and salmon, and also clarify the importance of risk management in conservation
Economic problems of low income farmers in Iowa
The basic economic and social maladjustments confronting American agriculture during the preceding two decades have stimulated a variety of studies and a variety of programs intended to correct the discrepancies in income. At first they were centered around methods of raising prices to farmers, often by placing a barrier between domestic and foreign prices, under the assumption that such price changes would correct the major portion of the unfavorable income position of the farm economy. As the programs and researches expanded and proliferated there was a growing realization that such broad, industry-wide approaches did very little to change the distribution of income within agriculture and was at least as likely to increase the range as to narrow it.
In consequence an increasing number of special problem groups became the focus for a small coterie of workers; farmers on poor land, in drouth areas, migratory laborers and part-time farmers are a few examples of focal problems. Gradually these separate studies are being integrated into a study of disadvantaged classes of farmers-farmers at the lower end of the income scale. This reorientation promises to have much greater analytical significance since it focuses directly on the problem- low income-and attempts to discover the reasons or series of reasons for their income position, rather than orienting the whole study around one hypothesis
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