29,097 research outputs found
An experimental 100 kilowatt wind turbine generator
Experimental generator consists of two blades mounted on 100 foot tower, driving transmission train and electric generator mounted on top of tower. Machine generates 100 kW of electricity at wind speeds from 18 to 60 miles per hour. Yaw control mechanism automatically orients machine into wind
Reversible tuning of the surface state in a psuedo-binary Bi2(Te-Se)3 topological insulator
We use angle-resolved photoemission spectroscopy to study non-trivial surface
state in psuedobinary Bi2Se0.6Te2.3 topological insulator. We show that unlike
previously studied binaries, this is an intrinsic topological insulator with
conduction bulk band residing well above the chemical potential. Our data
indicates that under good vacuum condition there are no significant aging
effects for more then two weeks after cleaving. We also demonstrate that shift
of the Kramers point at low temperature is caused by UV assisted absorption of
molecular hydrogen. Our findings pave the way for applications of these
materials in devices and present an easy scheme to tune their properties.Comment: 4 pages, 4 figure
IMPACTS OF LIBERALIZING THE JAPANESE PORK MARKET
The Japanese pork market is protected by a complex set of restrictions, including a variable levy and an import tariff. The combination of these policies distorts the quantity, price, and form of Japanese pork imports. An important issue relevant to the liberalization of the Japanese pork market is the accurate measurement of the price wedge between Japanese and world pork prices. The analysis indicates that the tariff equivalent of the price wedge over the 1986-88 period was 44%. If the tariff equivalent of the price wedge is reduced over a ten-year period, Japanese pork imports are projected to increase by over 39% initially and by over 215% compared to baseline projections by the year 2000. Producer welfare can be maintained by a deficiency payment scheme. A less costly alternative is an industry buffer scheme, which maintains the level of the pork industry for two years and then implements a declining deficiency payment scheme that limits the decrease in production levels to 5% per year.International Relations/Trade,
Rural Land-Use Trends in the Conterminous United States, 1950-2000.
In order to understand the magnitude, direction, and geographic distribution of land-use changes, we evaluated land-use trends in U.S. counties during the latter half of the 20th century. Our paper synthesizes the dominant spatial and temporal trends in population, agriculture, and urbanized land uses, using a variety of data sources and an ecoregion classification as a frame of reference. A combination of increasing attractiveness of nonmetropolitan areas in the period 1970–2000, decreasing household size, and decreasing density of settlement has resulted in important trends in the patterns of developed land. By 2000, the area of low-density, exurban development beyond the urban fringe occupied nearly 15 times the area of higher density urbanized development. Efficiency gains, mechanization, and agglomeration of agricultural concerns has resulted in data that show cropland area to be stable throughout the Corn Belt and parts of the West between 1950 and 2000, but decreasing by about 22% east of the Mississippi River. We use a regional case study of the Mid-Atlantic and Southeastern regions to focus in more detail on the land-cover changes resulting from these dynamics. Dominating were land-cover changes associated with the timber practices in the forested plains ecoregions and urbanization in the piedmont ecoregions. Appalachian ecoregions show the slowest rates of landcover change. The dominant trends of tremendous exurban growth, throughout the United States, and conversion and abandonment of agricultural lands, especially in the eastern United States, have important implications because they affect large areas of the country, the functioning of ecological systems, and the potential for restoratio
Companions to peculiar red giants: HR 363 and HR 1105
Recent IUE observations of two Tc-deficient S-type peculiar red giants that are also spectroscopic binaries, HR 363 and HR 1105 are reported. A 675 min SWP exposure of HR 363 shows emission lines of O I 1304 and Si II 1812 and a trace of continuum. Compared to the M giants, the far UV flux may be relatively larger, indicating a possible contribution from a white dwarf companion, but no high temperature emission lines are seen to indicate that this is an interacting system where mass-transfer recently occurred. However, HR 1105 appears to have a highly variable UV companion. In 1982, no UV flux was discerned for this system, but by 1986 C IV was strong, increasing by a factor of 3 in 1987 with prominent lines of Si III, C III, O III, Si IV, and N V. Using orbital parameters, these observations are consistent with high activity occuring when the side of the S-star primary illuminated by the companion faces the Earth, but since the IUE data were taken over 3 orbits, a secular change in the UV component cannot be excluded
Refiguring Prose Style: Possibilities for Writing Pedagogy
For about two decades, say Johnson and Pace, the discussion of how to address prose style in teaching college writing has been stuck, with style standing in as a proxy for other stakes in the theory wars. The traditional argument is evidently still quite persuasive to some—that teaching style is mostly a matter of teaching generic conventions through repetition and practice. Such a position usually presumes the traditional view of composition as essentially a service course, one without content of its own. On the other side, the shortcomings of this argument have been much discussed—that it neglects invention, revision, context, meaning, even truth; that it is not congruent with research; that it ignores 100 years of scholarship establishing composition\u27s intellectual territory beyond service. The discussion is stuck there, and all sides have been giving it a rest in recent scholarship. Yet style remains of vital practical interest to the field, because everyone has to teach it one way or another. A consequence of the impasse is that a theory of style itself has not been well articulated. Johnson and Pace suggest that moving the field toward a better consensus will require establishing style as a clearer subject of inquiry. Accordingly, this collection takes up a comprehensive study of the subject. Part I explores the recent history of composition studies, the ways it has figured and all but effaced the whole question of prose style. Part II takes to heart Elbow\u27s suggestion that composition and literature, particularly as conceptualized in the context of creative writing courses, have something to learn from each other. Part III sketches practical classroom procedures for heightening students\u27 abilities to engage style, and part IV explores new theoretical frameworks for defining this vital and much neglected territory. The hope of the essays here—focusing as they do on historical, aesthetic, practical, and theoretical issues—is to awaken composition studies to the possibilities of style, and, in turn, to rejuvenate a great many classrooms.https://digitalcommons.usu.edu/usupress_pubs/1156/thumbnail.jp
Modelling the Fluid Mechanics of Cilia and Flagella in Reproduction and Development
Cilia and flagella are actively bending slender organelles, performing
functions such as motility, feeding and embryonic symmetry breaking. We review
the mechanics of viscous-dominated microscale flow, including time-reversal
symmetry, drag anisotropy of slender bodies, and wall effects. We focus on the
fundamental force singularity, higher order multipoles, and the method of
images, providing physical insight and forming a basis for computational
approaches. Two biological problems are then considered in more detail: (1)
left-right symmetry breaking flow in the node, a microscopic structure in
developing vertebrate embryos, and (2) motility of microswimmers through
non-Newtonian fluids. Our model of the embryonic node reveals how particle
transport associated with morphogenesis is modulated by the gradual emergence
of cilium posterior tilt. Our model of swimming makes use of force
distributions within a body-conforming finite element framework, allowing the
solution of nonlinear inertialess Carreau flow. We find that a three-sphere
model swimmer and a model sperm are similarly affected by shear-thinning; in
both cases swimming due to a prescribed beat is enhanced by shear-thinning,
with optimal Deborah number around 0.8. The sperm exhibits an almost perfect
linear relationship between velocity and the logarithm of the ratio of zero to
infinite shear viscosity, with shear-thickening hindering cell progress.Comment: 20 pages, 24 figure
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