8,921 research outputs found
Neutron-Deuteron System and Photon Polarization Parameter at Thermal Neutron Energies
Effective Field Theory(EFT) is, the unique, model independent and systematic
low-energy version of QCD for processes involving momenta below the pion mass.
A low-energy photo-nuclear observable in three-body systems, photon
polarization parameter at thermal neutron energies is calculated by using
pionless EFT up to next-to-next to leading order(NLO). In order to make a
comparative study of this model, we compared our results for photon
polarization parameter with the realistic Argonne two-nucleon and
Urbana IX or Tucson-Melbourne three-nucleon interactions. Three-body currents
give small but significant contributions to some of the observables in the
neutron-deuteron radiative capture cross section at thermal neutron energies.
In this formalism the three-nucleon forces are needed up to NLO for cut-off
independent results. Our result converges order by order in low energy
expansion and also cut-off independent at this order.Comment: 10 pages, 3 figures, 2 table
Time-Dependent Models for Dark Matter at the Galactic Center
The prospects of indirect detection of dark matter at the galactic center
depend sensitively on the mass profile within the inner parsec. We calculate
the distribution of dark matter on sub-parsec scales by integrating the
time-dependent Fokker-Planck equation, including the effects of
self-annihilations, scattering of dark matter particles by stars, and capture
in the supermassive black hole. We consider a variety of initial dark matter
distributions, including models with very high densities ("spikes") near the
black hole, and models with "adiabatic compression" of the baryons. The
annihilation signal after 10 Gyr is found to be substantially reduced from its
initial value, but in dark matter models with an initial spike,
order-of-magnitude enhancements can persist compared with the rate in
spike-free models, with important implications for indirect dark matter
searches with GLAST and Air Cherenkov Telescopes like HESS and CANGAROO.Comment: Four page
Larval Ecology of Some Lower Michigan Black Flies (Diptera: Simuliidae) With Keys to the Immature Stages
The species composition, succession, and seasonal abundance of -immature simuliids ocmrrhg in the Rose Lake Wildlife Research Area in lower Michigan are presented. Selected physical and chemical characteristics of streams in the above area were examined and compared in relation to faunal distributions. Comparisons of species differences between permanent and temporary streams were made utilizing the functional group concept based on feeding mechanisms.
Keys and illustrations are presented for the identiiication of larvae and pupae of four genera (Prosimulium, Simulium, Stegopterna, Cnephia) and 19 species of Simuliidae known to occur in lower Michigan. Two species, Cnephia ornithophilia and Simulium vemum, were recorded for the first time in Michigan
Minimizing Chaos
The thesis works presented in this paper are mixed media paintings that explore the tension between artistic control and abandon in what is essentially an intuitive driven process of image making. With these thesis works I have sought to use additive and subtractive processes to create compositions that are as much an exploration of materials as they are an exploration of the formal elements of art. My work is focused on recreating the patterns, textures, and surfaces found in man-made objects and environments that I find in my daily life and I believe are often overlooked in their aesthetic value. In doing so, I hope to recreate for the viewer the moments of aesthetic discovery that I have found within the patterns, textures, and surface qualities of these objects
Engineering in American Society: 1850–1875
Technology, which has significantly changed Western man’s way of life over the past century, exerted a powerful influence on American society during the third quarter of the nineteenth century. In this study Raymond H. Merritt focuses on the engineering profession, in order to describe not only the vital role that engineers played in producing a technological society but also to note the changes they helped to bring about in American education, industry, professional status, world perspectives, urban existence, and cultural values.
During the development period of 1850-1875, engineers erected bridges, blasted tunnels, designed machines, improved rivers and harbors, developed utilities necessary for urban life, and helped to bind the continent together through new systems of transportation and communication. As a concomitant to this technological development, states Merritt, they introduced a new set of cultural values that were at once urban and cosmopolitan. These cultural values tended to reflect the engineers’ experience of mobility—so much a part of their lives—and their commitment to efficiency, standardization, improved living conditions, and a less burdensome life.
Merritt concludes from his study that the rapid growth of the engineering profession was aided greatly by the introduction of new teaching methods which emphasized and encouraged the solution of immediate problems. Schools devoted exclusively to the education and training of engineers flourished—schools such as Rensselaer Polytechnic Institute and Stevens Institute of Technology. Moreover, business corporations and governments sought the services of the engineers to meet the new technological demands of the day. In response, they devised methods and materials that went beyond traditional techniques. Their specialized experiences in planning, constructing, and supervising the early operation of these facilities brought them into positions of authority in the new business concerns, since they often were the only qualified men available for the executive positions of authority for the executive positions of America’s earliest large corporations. These positions of authority further extended their influence in American society. Engineers took a positive view of administration, developed systems of cost accounting, worked out job descriptions, defined levels of responsibility, and played a major role in industrial consolidation.
Despite their close association with secular materialism, Merritt notes that many engineers expressed the hope that human peace and happiness would result from technical innovation and that they themselves could devote their technological knowledge, executive experience, and newly acquired status to solve some of the critical problems of communal life. Having begun merely as had become the planners and, in many cases, municipal enterprises which they hoped would turn a land of farms and cities into a “social eden.”
Raymond H. Merritt is assistant professor of history at the University of Wisconsin, Milwaukee.https://uknowledge.uky.edu/upk_history_of_science_technology_and_medicine/1007/thumbnail.jp
Reduced herbicide antagonism through novel spray application techniques
Field studies were conducted to test three application methods for applying antagonistic herbicide combinations: 1) tank mix (TMX), 2) mix-in-line (MIL), and 3) separate boom (SPB). Sethoxydim applied with bentazon, glyphosate applied with dicamba or 2,4-D, and clethodim applied with dicamba or 2,4-D had higher efficacy when applied using the SPB method. Antagonism of all the herbicide combinations above was observed when applied using the TMX and MIL methods. In some cases, antagonism was avoided when using the SPB method. Three application methods tested in greenhouse studies were 1) TMX, 2) synthetic auxin applied first (AAF), and 3) synthetic auxin applied second (AAS). The AAS application method resulted in higher weed control than the TMX and AAF methods. Analysis done through liquid chromatography mass spectrometry supported the greenhouse results with higher rates of glyphosate detected with the AAS method
Using Wii technology to explore real spaces via virtual environments for people who are blind
Purpose - Virtual environments (VEs) that represent real spaces (RSs) give people who are blind the opportunity to build a cognitive map in advance that they will be able to use when arriving at the RS. Design - In this research study Nintendo Wii based technology was used for exploring VEs via the Wiici application. The Wiimote allows the user to interact with VEs by simulating walking and scanning the space. Finding - By getting haptic and auditory feedback the user learned to explore new spaces. We examined the participants' abilities to explore new simple and complex places, construct a cognitive map, and perform orientation tasks in the RS. Originality – To our knowledge, this finding presents the first virtual environment for people who are blind that allow the participants to scan the environment and by this to construct map model spatial representations
Cloud atlas for the FIRE Cirrus Intensive Field Observation (IFO)
An Intensive Field Observation (IFO) of cirrus clouds was conducted over the mid-western U.S. during the period October 13 to November 2, 1986. This activity, part of the First ISCCP Regional Experiment (FIRE), included measurements made from specially deployed instruments on the ground, balloons, and aircraft as well as observations from existing operational and experimental satellites. One of the sets of satellite observations was the radiance measurements made with the 5-channel AVHRR radiometer on the NOAA 9 polar orbiting meteorological satellite. The ground resolution of the measurements at nadir is approx. 1 km. It is these measurements, made once each day at approximately 2:30 p.m. local time, that were used in determining the present cloud atlas. The area covered by the atlas is slightly larger than the area specified for the IFO, in order to be in alignment with the grid that will be used in a forthcoming atlas for the larger, ETO region. The atlas contains four pages of information for each satellite pass. The 1st page of each group shows the distribution of measured radiances in channel 1 (normalized to the incoming solar flux multiplied by the cosine of the solar zenith angle) and in channel 4 for the area as a whole and for each analysis box. The 2nd page shows the images in: channels 1 and 2, channel 3R; and channel 4. The 3rd page shows the retrieved parameters in graphical form for the region as a whole and for each analysis box, where cloud fraction appears as a contour plot with respect to optical thickness and cloudtop temperature. The 4th page provides a statistical summary of the retrieved parameters in numerical form for each analysis box
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