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Articles 282631 - 282660 of 304417

Full-Text Articles in Physical Sciences and Mathematics

Problems With Deducing Ionospheric Plasma Convection Patterns, Jan Josef Sojka, Robert W. Schunk Jan 1986

Problems With Deducing Ionospheric Plasma Convection Patterns, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

It is well-known that convection electric fields have an important effect on the ionosphere-thermosphere system at high latitudes and that a quantitative understanding of their effect requires a knowledge of the plasma convection pattern. Consequently, convection electric fields have been measured by a variety of techniques, including satellite, rocket, and balloon-borne probes, optical tracking of ionized barium clouds, incoherent scatter observations of drifting F region plasma, and coherent scatter observations of drifting E region irregularities. Since all of these measurement techniques provide information on only a limited spatial region at any time, the construction of the overall convection pattern requires …

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Comparison Of Simultaneous Chatanika And Millstone Hill Observations With Ionospheric Model Predictions, C. E. Rasmussen, Robert W. Schunk, Jan Josef Sojka, Vincent B. Wickwar, O. De La Beaujardiere, J. Foster, J. Holt, D. S. Evans, E. Nielsen Jan 1986

Comparison Of Simultaneous Chatanika And Millstone Hill Observations With Ionospheric Model Predictions, C. E. Rasmussen, Robert W. Schunk, Jan Josef Sojka, Vincent B. Wickwar, O. De La Beaujardiere, J. Foster, J. Holt, D. S. Evans, E. Nielsen

All Physics Faculty Publications

As part of the MITHRAS program, the Chatanika and Millstone Hill incoherent-scatter radars made coordinated observations of the polar ionosphere on June 27 and 28, 1981. We compare these data with predictions made by a high-latitude ionospheric model. Qualitatively, the same features are evident in both the model and the radar data: fairly constant densities on the dayside with a mid-latitude trough forming poleward of 65 degrees around 1900 MLT (magnetic local time). This trough is seen to extend equatorward with increasing MLT, such that the minimum densities occurring in the trough appear just after midnight around 60 degrees dipole …

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Formation Kinetics Of Thermal Donors In Silicon, J T. Borenstein, J W. Corbett, David Peak Jan 1986

Formation Kinetics Of Thermal Donors In Silicon, J T. Borenstein, J W. Corbett, David Peak

All Physics Faculty Publications

The kinetics of thermal donor formation in Czochralski-silicon at ca. 450° C are explained by a simple model based on the work of Suezawa and Sumino which derives forward and reverse reaction rates for each electrically active species from the general features of the infrared electronic absorption spectra. The model, which is independent of the chemical nature of the thermal donor core, assumes that all thermal donors beyond the first donor species are chemically stable at the donor formation temperature, and approximates the reactions for species smaller than the first thermal donor as being in chemical equilibrium. The model is …

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Crossover From Contact Propagation To Chemical Propagation In First-Passage Percolation, A. R. Kerstein, Boyd F. Edwards Jan 1986

Crossover From Contact Propagation To Chemical Propagation In First-Passage Percolation, A. R. Kerstein, Boyd F. Edwards

All Physics Faculty Publications

On lattices whose bonds are assigned time delays from a bimodal distribution with modes at b and a≫b whose relative weights are p and 1-p, the dependence of the first-passage velocity v on p is investigated by means of scaling arguments and computations. As p increases, v exhibits a sharp rise near the percolation threshold due to a crossover from the contact-propagation regime, in which slow-bond crossings are rate limiting, to the chemical-propagation regime, in which the tortuosity of the shortest path through the fast-bond network is rate limiting. Previous analyses of criticality in the limit a/b→∞ are extended by …

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A Theoretical Study Of The Production And Decay Of Localized Electron Density Enhancements In The Polar Ionosphere, Jan Josef Sojka, Robert W. Schunk Jan 1986

A Theoretical Study Of The Production And Decay Of Localized Electron Density Enhancements In The Polar Ionosphere, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

The origins, transport, and decay of large-scale (≳ 10 km) F region density irregularities were theoretically studied using a high-latitude time dependent ionospheric model. Such density irregularities (blobs) have been found both in the polar cap and the auroral zone. The model study, which focuses on blobs being produced by auroral precipitation, shows that the observed energy fluxes can readily account for the blob densities if a plasma flux tube is exposed to the precipitation for 5-10 min. Once the flux tube is transported away from the source, the F region density profile recovers its shape on a time scale …

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Effects Of Different Convection Models Upon The High-Latitude Ionosphere, C. E. Rasmussen, Robert W. Schunk, Jan Josef Sojka Jan 1986

Effects Of Different Convection Models Upon The High-Latitude Ionosphere, C. E. Rasmussen, Robert W. Schunk, Jan Josef Sojka

All Physics Faculty Publications

It is well known that convection electric fields have an important effect on the ionosphere at high latitudes and that a quantitative understanding of their effect requires a knowledge of plasma convection over the entire high-latitude region. Two empirical models of plasma convection that have been proposed for use in studying the ionosphere are the Volland and Heelis models. Both of these models provide a similar description of two-celled ionospheric convection, but they differ in several ways, in particular, in the manner in which plasma flows over the central polar cap and near the polar cap boundary. In order to …

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Theoretical Study Of The Electron Temperature In The High-Latitude Ionosphere For Solar Maximum And Winter Conditions, Robert W. Schunk, Jan Josef Sojka, M. D. Bowline Jan 1986

Theoretical Study Of The Electron Temperature In The High-Latitude Ionosphere For Solar Maximum And Winter Conditions, Robert W. Schunk, Jan Josef Sojka, M. D. Bowline

All Physics Faculty Publications

The electron temperature (Te) variation in the high-latitude ionosphere at altitudes between 120 and 800 km has been modeled for solar maximum, winter solstice, and strong magnetic activity conditions. The calculated electron temperatures are consistent with the plasma densities and ion temperatures computed from a time-dependent ionospheric model. Heating rates for both solar EUV and auroral precipitation were included. In general, the predicted UT variation of the electron temperature that results from the displacement between the magnetic and geographic poles is only a few hundred degrees. However, in sunlit trough regions, Te hot spots develop, and …

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'Hobble Creek' - A Superior Selection Of Low-Elevation Mountain Big Sagebrush, United States Department Of Agriculture, Forest Service Jan 1986

'Hobble Creek' - A Superior Selection Of Low-Elevation Mountain Big Sagebrush, United States Department Of Agriculture, Forest Service

Forestry

This is the foundation document for the release of the 'Hobble Creek' selection of big sagebrush. It is a low-elevation mountain big sagebrush (Artemisia tridentata ssp. vaseyana). 'Hobble Creek' is needed to increase the nutrient content of winter diets of mule deer (Odocoileus hemionus hemionus) and domestic sheep (Ovis aries). This sagebrush exceeds the typical winter forage values in amount of energy-producing compounds, crude protein, phosphorus, and carotene. Of the 186 big sagebrush selections tested. 'Hobble Creek' is the most preferred by wintering mule deer and ranks high in preference by wintering domestic sheep. 'Hobble Creek' does not contain substances …

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The Influence Of Viewing Angle On Elk Hiding Cover In Young Timber Stands, United States Department Of Agriculture, Forest Service Jan 1986

The Influence Of Viewing Angle On Elk Hiding Cover In Young Timber Stands, United States Department Of Agriculture, Forest Service

Forestry

Young timber stands, even when providing 100 percent visual concealment for elk when viewed on a horizontal plane, may provide 50 percent or less cover when viewed from an opposing slope at an elevated viewing angle. The higher the viewing angle, the greater the relative cover loss. In a simple linear model, viewing angle explained 52 percent of the variation in hiding cover values. Slightly more variation was accounted for when the data were stratified by tree height. On the average, for a 10-degree elevation in viewing angle, hiding cover decreased by 10 percent. The cover loss relationship was most …

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Proceedings -- National Wilderness Research Conference: Current Research, United States Department Of Agriculture, Forest Service Jan 1986

Proceedings -- National Wilderness Research Conference: Current Research, United States Department Of Agriculture, Forest Service

Forestry

Includes more than 70 reports of current wilderness research. Papers are organized around nine topics: wilderness resource research, including natural fire, air quality, impacts to soil and vegetation, fish and wildlife, and water; and wilderness user research related to recreational use and user characteristics, attitudes and behavior, benefits, and management concepts and tools.

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Visitor Attitudes Toward Wilderness Fire Management Policy -- 1971-84, United States Department Of Agriculture, Forest Service Jan 1986

Visitor Attitudes Toward Wilderness Fire Management Policy -- 1971-84, United States Department Of Agriculture, Forest Service

Wildfires

The historical role of naturally occurring fire in shaping the character of many American landscapes has become an accepted ecological principle. Prior to the coming of the Europeans, natural fires had a major influence in producing a variety of vegetational mosaics. Fire suppression policies of the 20th century, however, significantly changed the evolution of many landscapes compared to what would have occurred had natural fires been allowed to continue. Although natural fires can no longer be allowed to burn in many places because of resource values or danger to the public, such fires may be permitted in many wildernesses and …

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Flood Insurance Study, City Of Salina, Utah, Sevier County, Federal Emergency Management Agency Jan 1986

Flood Insurance Study, City Of Salina, Utah, Sevier County, Federal Emergency Management Agency

All U.S. Government Documents (Utah Regional Depository)

This Flood Insurance Study investigates the existence and severity of flood hazards in the City of Salina, Sevier County, Utah, and aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This study has developed flood risk data for various areas of the community that will be used to establish actuarial flood insurance rates and assist the community in its efforts to promote sound flood plain management. Minimum flood plain management requirements for participation in the National Flood Insurance Program (NFIP) are set forth in the Code of Federal Regulations …

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The Seedskadee Project: Remote Sensing In Non-Site Archeology, Dwight L. Drager, Arthur K. Ireland, National Park Service, Bureau Of Reclamation, United Sates Department Of The Interior Jan 1986

The Seedskadee Project: Remote Sensing In Non-Site Archeology, Dwight L. Drager, Arthur K. Ireland, National Park Service, Bureau Of Reclamation, United Sates Department Of The Interior

All U.S. Government Documents (Utah Regional Depository)

The project area includes some 185,000 acres of land along the banks of the Green River below the Fontenelle Dam in southwestern Wyoming. The Statement of Work calls for 1) a Class I Cultural Resources Survey and Remote Sensing Survey to assess the general nature of the resources, 2) the preparation of a predictive study design based on available information, and 3) a ground truth survey on a small sample of the project area. This proposal discusses the methods that the Branch of Remote Sensing of the Division of Cultural Research of the Southwest Cultural Resources Center of the National …

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Correction Of The Basis Set Superposition Error In Scf And Mp2 Interaction Energies. The Water Dimer, M. M. Szczesniak, Steve Scheiner Jan 1986

Correction Of The Basis Set Superposition Error In Scf And Mp2 Interaction Energies. The Water Dimer, M. M. Szczesniak, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

There has been some discussion concerning whether basis set superposition error is more correctly evaluated using the full set of ghost orbitals of the partner molecule or some subset thereof. A formal treatment is presented, arguing that the full set is required at the Møller–Plesset level. Numerical support for this position is provided by calculation of the interaction energy between a pair of water molecules, using a series of moderate sized basis sets ranging from 6‐31G∗∗ to the [432/21] contraction suggested by Clementi and Habitz. These energies, at both the SCF and MP2 levels, behave erratically with respect to changes …

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Nebraska Mineral Operations Review, 1985, Ray R. Burchett, Duane A. Eversoll Jan 1986

Nebraska Mineral Operations Review, 1985, Ray R. Burchett, Duane A. Eversoll

Conservation and Survey Division

No abstract provided.

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Annual Outflow/Inflow Of Water From Nebraska, 1950-1985, Conservation And Survey Division Jan 1986

Annual Outflow/Inflow Of Water From Nebraska, 1950-1985, Conservation And Survey Division

Conservation and Survey Division

No abstract provided.

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Resource Notes-Summer 1986 Jan 1986

Resource Notes-Summer 1986

Conservation and Survey Division

No abstract provided.

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Resource Notes-Spring 1986 Jan 1986

Resource Notes-Spring 1986

Conservation and Survey Division

No abstract provided.

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Annual Outflow Of Water From Nebraska, 1950-1985, Conservation Survey Division Jan 1986

Annual Outflow Of Water From Nebraska, 1950-1985, Conservation Survey Division

Conservation and Survey Division

No abstract provided.

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On The Existence Of Periodic And Eventually Periodic Solutions Of A Fluid Dynamic Forced Harmonic Oscillator, Charlie H. Cooke Jan 1986

On The Existence Of Periodic And Eventually Periodic Solutions Of A Fluid Dynamic Forced Harmonic Oscillator, Charlie H. Cooke

Mathematics & Statistics Faculty Publications

For certain flow regimes, the nonlinear differential equation Y¨=F(Y)−G, Y≥0, G>0 and constant, models qualitatively the behaviour of a forced, fluid dynamic, harmonic oscillator which has been a popular department store attraction. The device consists of a ball oscillating suspended in the vertical jet from a household fan. From the postulated form of the model, we determine sets of attraction and exploit symmetry properties of the system to show that all solutions are either initially periodic, with the ball never striking the fan, or else eventually approach a periodic limit cycle, after a sufficient number of bounces away from …

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Fungicide Testing, M. J. Barbetti Jan 1986

Fungicide Testing, M. J. Barbetti

Experimental Summaries - Plant Research

Fungicidal control of Phoma blackstem disease in medic, 86 KA 11. Medic cultivar susceptibility to Phoma blackstem disease, 85 KA 56. Role of Phoma seed infection in medic, 85 KA 57. Effect of soil pasteurization on damage caused by six fungal root pathogens, 86 PE 53. Susceptibility of 18 sub-clover cultivars to isolates of the clover scorch fungus, Kabatiella caulivora, 86 PE 54. Effect of plant age or growth stage of subterranean clover on susceptibility to infection by the clover scorch fungus, Kabatiella caulivora, 86 PE 55. Susceptibility of rapeseed lines to blackleg crown canker, 86 MT 1, 86 MT …

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Root Diseases Of Cereals., G. C. Macnish Jan 1986

Root Diseases Of Cereals., G. C. Macnish

Experimental Summaries - Plant Research

Take-all Effects of nitrogen source on take-all 82N34, 77E4. Take-all and rates of PP450 and Bayleton 86MT40. Take-all and control by lupins 86MT6. Take-all and field inoculation rates, 86MT58. Take-all and fumigation, 86MT57. Rhizoctonia root rot Rhizoctonia patch and soil compaction, 86E39. Rhizoctonia patch and short chemical fallow, 86E40. Rhizoctonia root rot and Glean, 86E42. Rhizoctonia strains-and paddock history, 86E31. Rhizoctonia root rot - host effects on strains, 86BA38, 85E28, 86E30.

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Lupin Root Rot, Lupin Hypocotyl Rot, Rhizoctonia Coleoptile Rot Of Wheat, Rhizoctonia Root Rots In Long Term Wheat-Pasture Rotation Trials., M. Sweetingham Jan 1986

Lupin Root Rot, Lupin Hypocotyl Rot, Rhizoctonia Coleoptile Rot Of Wheat, Rhizoctonia Root Rots In Long Term Wheat-Pasture Rotation Trials., M. Sweetingham

Experimental Summaries - Plant Research

Lupin Root Rot: 86Cl4, 86WH15, 86ME85, 86LG63, 85C63, 86WH14. Lupin Hypocotyl rot, 86BA49, 86BA21. Rhizoctonia coleoptile rot of wheat, 86BA19, 86BA20 Rhizoctonia root rots in long term wheat-pasture rotation trials.

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Root And Foliar Diseases Of Wheat On Sandplain In The Geraldton Region., J. Wilson Jan 1986

Root And Foliar Diseases Of Wheat On Sandplain In The Geraldton Region., J. Wilson

Experimental Summaries - Plant Research

Leaf disease trial, 86C69. Drench trial, 86C70. Fumigation trial, 86C71. Three springs trial, 86TS31. Soil transfer trial, 86C98. Wheat leaf disease control trial, 86C99. Water use rotation trial, 86C63. Cultivation, naraling (jarvis), 82GE38. Wheat diseases, survey.

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Summary Of Rhizobium Experiments., J. G. Howieson Jan 1986

Summary Of Rhizobium Experiments., J. G. Howieson

Experimental Summaries - Plant Research

Rotation trials, 84ME32, 84ME24, 84N18, 84M18, 85KA58. Cross row trials, 85M28. One year trials, 86M41, 86M42. On-going trials, 86M58, 85KA64, 86V3, 86AL. 84WH24.

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Multivariate Rational Approximation, Ronald A. Devore, Xiang Ming Yu Jan 1986

Multivariate Rational Approximation, Ronald A. Devore, Xiang Ming Yu

Faculty Publications

No abstract provided.

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Seal Development And Infiltration As Affected By Rainfall Kinetic Energy, Deah Abed Mahamad Jan 1986

Seal Development And Infiltration As Affected By Rainfall Kinetic Energy, Deah Abed Mahamad

Electronic Theses and Dissertations

The infiltration of water into soil has been studied for more than 50 years. Much of the effort has concentrated on obtaining infiltration rate measurements for different soils and on developing equations which describe the resulting data. A portion of the infiltration literature has dealt with the large affect that the development of a surface seal has had on the resulting infiltration measurement of a soil. This surface seal may be more significant in determining the infiltration characteristics of a soil than any other single or perhaps combination of factors. Surface seal development has been linked to both rainfall energy …

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Stocking Density, Strain Performance, And Feeding Method Evaluation Of Cage Reared Rainbow Trout (Salmo Gairdneri) In Eastern South Dakota, Dale B. Allen Jan 1986

Stocking Density, Strain Performance, And Feeding Method Evaluation Of Cage Reared Rainbow Trout (Salmo Gairdneri) In Eastern South Dakota, Dale B. Allen

Electronic Theses and Dissertations

Methods for cage rearing rainbow trout (Salmo gairdneri) were investigated to assist in the development of a landowner aquaculture program for eastern South Dakota. Rainbow trout when stocked as small fingerlings in the spring did not reach a marketable weight (200 g). The fish did attain a size acceptable to some landowners for personal consumption. Maximum stocking density (fish/m3) was not determined. Densities greater than those used would have been needed to determine the optimum stocking rate. The use of a deeper culture cage (3 m) was justified in this area due to the high water temperatures that were common. …

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Growth, Survival, And Reproductive Success Of Largemouth Bass Stocked With Selected Forage Fishes In South Dakota Ponds, R. Dean Beck Jan 1986

Growth, Survival, And Reproductive Success Of Largemouth Bass Stocked With Selected Forage Fishes In South Dakota Ponds, R. Dean Beck

Electronic Theses and Dissertations

Five fish stocking combinations were evaluated to determine effects of forage availability and geographic location on largemouth bass (Micropterus salmoides) growth, survival, and reproductive success two and three years following stocking. Four forage species stocked with largemouth bass included bluegills (Lepomis macrochirus), black bullheads (Ictalurus melas), golden shiners (Notemigonus crysoleucas), and fathead minnows (Pimephales promelas). A largemouth bass only stocking strategy was also evaluated. Largemouth bass survival two years after stocking in eastern South Dakota ponds averaged 26.5%. Largemouth bass only and largemouth bass-bluegill combinations exhibited the greatest survival rates (31.6% and 28.8%, respectively), while the largemouth bass-black bullhead combination …

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Dynamics And Distribution Of Fishes Occupying A South Dakota Power Plant Cooling Reservoir, Timothy R. Walters Jan 1986

Dynamics And Distribution Of Fishes Occupying A South Dakota Power Plant Cooling Reservoir, Timothy R. Walters

Electronic Theses and Dissertations

Distribution, population number, growth rate, and reproductive activities of walleyes (Stizostedion vitreum vitreum) were studied to evaluate the potential of the Big Stone Power Plant cooling reservoir as a source of walleye brood stock. In addition, dynamics and distribution of bluegill (Lepomis macrochirus) and orangespotted sunfish (L. humilis) were examined. Walleye grew well, reaching a weighted mean total length of 271 mm at formation of annulus I. Survival of walleye was poor, with population estimates of 41 and 43 fish in 1984 and 1985, respectively. Low sample size precluded analysis of distribution, but no consistent preference for an area of …

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