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1998

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Articles 1321 - 1350 of 2574

Full-Text Articles in Physical Sciences and Mathematics

Classics In Human Geography Revisited: Ley, D. 1974: The Black Inner City As Frontier Outpost: Images And Behavior Of A Philadelphia Neighborhood, Risa Palm Jan 1998

Classics In Human Geography Revisited: Ley, D. 1974: The Black Inner City As Frontier Outpost: Images And Behavior Of A Philadelphia Neighborhood, Risa Palm

Geosciences Faculty Publications

No abstract provided.

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Urban Earthquake Hazards: The Impact Of Culture On Perceived Risk And Response In The Usa And Japan, Risa Palm Jan 1998

Urban Earthquake Hazards: The Impact Of Culture On Perceived Risk And Response In The Usa And Japan, Risa Palm

Geosciences Faculty Publications

This paper reports on a major survey of earthquake hazard response in neighbourhoods in Tokyo-Yokohama and Los Angeles, two metropolitan areas of highly industrialized nations which routinely exchange ideas in order to try to learn from the policies, practices and experiences of the other. Survey findings showed many similarities in hazard response and preferred public policy, but also important contrasts in behaviour, and significant differences in the factors associated with these behaviours. The findings suggest caution in bi-national policy-sharing unless such sharing is preceded by a careful study of local cultural contexts.

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1998 Platte River Basin Ecosystem Symposium Proceedings Jan 1998

1998 Platte River Basin Ecosystem Symposium Proceedings

Water Current Newsletter

No abstract provided.

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Stand Density Effects On Biomass Allocation Patterns And Subsequent Soil Nitrogen Demand, Christopher Dicus, Thomas J. Dean Jan 1998

Stand Density Effects On Biomass Allocation Patterns And Subsequent Soil Nitrogen Demand, Christopher Dicus, Thomas J. Dean

Natural Resources Management and Environmental Sciences

Growth and yield data from a loblolly pine plantation in southeastern Louisiana were obtained yearly from 1993 to 1996 on numbered trees within two stands initially planted on a 1.22- by 1.22-meter spacing, and two stands planted on a 2.44- by 2.44-meter spacing. Using allometric equations derived from a 1994 on-site destructive harvest, cited nitrogen concentrations of various tree tissues, and accounting for foliar nitrogen retranslocation, stand growth and soil nitrogen demands were determined. Results showed that production of all aboveground tissues increased as stand density index (SDI) increased. Annual soil nitrogen demand increased with SDI primarily as a result …

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Postfire Succession And Disturbance Interactions On An Intermountain Subalpine Spruce-Fir Forest, Michael J. Jenkins, Christopher Dicus, Elizabeth G. Hebertson Jan 1998

Postfire Succession And Disturbance Interactions On An Intermountain Subalpine Spruce-Fir Forest, Michael J. Jenkins, Christopher Dicus, Elizabeth G. Hebertson

Natural Resources Management and Environmental Sciences

Four general postfire successional pathways leading to a climax Engelmann spruce (Picea engelmmlilii Parry)-subalpine fir (Abies /asiocarpa [Hook] Nutt.) forest operate on the T.W. Daniel Experimental Forest in northern Utah. Depending on the successional pathway followed. reestablishment of the prefire climax forest will take 200 to 400 years or more due to a rarity of extreme burning conditions. During the long period between catastrophic stand-replacing fires, a variety of other natural disturbances contribute to the varying structure and composition of vegetation and the fuel mosaic in internountain subalpine spruce-fir forests. Disturbances may range from chronic and small scale …

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Restoration Of Mixed Conifer Communities Using Prescribed Fire In Bryce Canyon National Park, Michael J. Jenkins, Christopher Dicus, Joel E. Godfrey Jan 1998

Restoration Of Mixed Conifer Communities Using Prescribed Fire In Bryce Canyon National Park, Michael J. Jenkins, Christopher Dicus, Joel E. Godfrey

Natural Resources Management and Environmental Sciences

A fire history conducted in the mixed conifer community types of Bryce Canyon National Park found the mean fire-return interval has lengthened from 7.5 to 45 years since 1900. Dendroecology, species, diameter, and age-class analysis showed a change in stand composition in favor of white fir (Abies concolor) and Douglas-fir (Psuedotsuga menziesii) and a 200% increase in fuel accumulation. Recommendations for prescribed burning and mechanical reduction of fuels were incorporated into the Bryce Canyon management plan.

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Biological And Management Implications Of Fire-Pathogen Interactions In The Giant Sequoia Ecosystem, Douglas D. Piirto, John R. Parmeter Jr., Fields W. Cobb Jr., Kevin L. Piper, Amy C. Workinger, William J. Otrosina Jan 1998

Biological And Management Implications Of Fire-Pathogen Interactions In The Giant Sequoia Ecosystem, Douglas D. Piirto, John R. Parmeter Jr., Fields W. Cobb Jr., Kevin L. Piper, Amy C. Workinger, William J. Otrosina

Natural Resources Management and Environmental Sciences

An overriding management goal for national parks is the maintenance or, where necessary, the restoration of natural ecological processes. In Sequoia-Kings Canyon and Yosemite National Parks, there is concern about the effects of fire suppression on the giant sequoia-mixed conifer forest ecosystem. The National Park Service is currently using prescribed fire management and prescribed burning as tools to reintroduce fire as a natural process. However, there are questions about the positive and negative effects of reintroducing fire in the giant sequoia-mixed conifer ecosystem. Reintroducing fire in the Sierra Nevada forests needs critical evaluation with respect to the pathogens that affect …

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An Embedding Of Schwartz Distributions In The Algebra Of Asymptotic Functions, Michael Oberguggenberger, Todor D. Todorov Jan 1998

An Embedding Of Schwartz Distributions In The Algebra Of Asymptotic Functions, Michael Oberguggenberger, Todor D. Todorov

Mathematics

We present a solution of the problem of multiplication of Schwartz distributions by embedding the space of distributions into a differential algebra of generalized functions, called in the paper "asymptotic function," similar to but different from J. F Colombeau's algebras of new generalized functions.

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Ai And The Changing Face Of Health Care, Erika Rogers Jan 1998

Ai And The Changing Face Of Health Care, Erika Rogers

Computer Science and Software Engineering

No abstract provided.

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Interactive Image Cases For Medical Problem Solving, Erika Rogers, Barb Ericson Jan 1998

Interactive Image Cases For Medical Problem Solving, Erika Rogers, Barb Ericson

Computer Science and Software Engineering

The development of an intelligent assistance agent for diagnostic radiology faces a number of challenges: e.g., how to gain access to the knowledge used an such visual problem solving tasks, how to operationalize it for further processing, and how to present it an the most useful manner for diagnosis. Our previous work an this domain placed an emphasis on the first two issues, and has shown that both perception and problem solving need to be supported an these types of tasks. However, the interface to the underlying intelligence in our first prototypes did not reflect how medical practitioners physically interact …

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Vibrational Sum Frequency Spectroscopy Of Surfactants And Phospholipids Monolayers At Liquid-Liquid Interfaces, B. L. Smiley, R. A. Walker, D. E. Gragson, T. E. Hannon, G. L. Richmond Jan 1998

Vibrational Sum Frequency Spectroscopy Of Surfactants And Phospholipids Monolayers At Liquid-Liquid Interfaces, B. L. Smiley, R. A. Walker, D. E. Gragson, T. E. Hannon, G. L. Richmond

Chemistry and Biochemistry

Work from our laboratory on vibrational sum frequency spectroscopic investigations of molecular ordering at the carbon tetrachloride-water interface is reviewed. Simple charged surfactants adsorbed at the liquid-liquid interface are seen to induce alignment of interfacial water molecules to a degree which is dependent on the induced surface potential. Saturation of water molecule alignment occurs at a surfactant surface concentration corresponding to a calculated surface potential of approximately 160 mV. In complementary studies, the relative degree of hydrocarbon chain ordering within monolayers of symmetric phosphatidylcholines of different chain lengths is inferred by the relative signal contributions of the methyl and methylene …

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Chapter 2 Climate, Donald A. Wilhite, Kenneth G. Hubbard Jan 1998

Chapter 2 Climate, Donald A. Wilhite, Kenneth G. Hubbard

Drought Mitigation Center: Faculty Publications

The broad climatic patterns of the Sand Hills region are also characteristic of the central Great Plains environment. The spatial and temporal patterns of these climatic variables have a significant effect on the natural resources of the region.

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D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury Jan 1998

D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury

Chemistry Department: Faculty Publications

The two diastereomers of 4-nitro-1,3-diphenylpentan-1-one behave differently in deuterium for hydrogen exchange in DMSO-d6/D2O solutions using various bases as catalyst. Reaction of the erythro diastereomer gives largely the same diastereomer upon D/H exchange (retention), i.e., exchange exceeds epimerization. Pyridine and acetonitrile as solvents lead to faster epimerization than exchange. In the threo diastereomer (DMSO-d6 solution), epimerization exceeds exchange, and the anion to some extent regains the same hydrogen originally removed by the base on the opposite face. 2-Bromo-4-nitro-1,3-diphenylbutan-1-one undergoes ring closure to the cyclopropane faster than exchange (within seconds). The cyclopropane shows faster exchange than equilibration, i.e., retention of configuration, …

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Spatial Estimates For Stochastic Flows In Euclidean Space, Salah-Eldin A. Mohammed, Michael K. R. Scheutzow Jan 1998

Spatial Estimates For Stochastic Flows In Euclidean Space, Salah-Eldin A. Mohammed, Michael K. R. Scheutzow

Articles and Preprints

We study the behavior for large |x| of Kunita-type stochastic flows φ(t, ω, x) on Rd, driven by continuous spatial semimartingales. For this class of flows we prove new spatial estimates for large |x|, under very mild regularity conditions on the driving semimartingale random field. It is expected that the results would be of interest for the theory of stochastic flows on noncompact manifolds as well as in the study of nonlinear filtering, stochastic functional and partial differential equations. Some examples and counterexamples are given.

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Robots In The Undergraduate Curriculum, D. Kumar, Lisa A. Meeden Jan 1998

Robots In The Undergraduate Curriculum, D. Kumar, Lisa A. Meeden

Computer Science Faculty Works

No abstract provided.

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Thermochronological Evidence For Late Proterozoic (Vendian) Cooling In Southwest Wedel Jarlsberg Land, Spitsbergen, M. Manecki, D. K. Holm, J. Czerny, Daniel R. Lux Jan 1998

Thermochronological Evidence For Late Proterozoic (Vendian) Cooling In Southwest Wedel Jarlsberg Land, Spitsbergen, M. Manecki, D. K. Holm, J. Czerny, Daniel R. Lux

Earth Science Faculty Scholarship

Two Proterozoic terranes with different metamorphic histories are distinguished from geological mapping in southwestern Wedel Jarlsberg Land: a northern greenschist facies terrane and a southern amphibolite facies terrane which has been overprinted by greenschist facies metamorphism. To better characterize the tectonothermal history of these terranes we have obtained new Ar-40/Ar-39 mineral dates from this area. A muscovite separate from the northern terrane yielded a Caledonian plateau age of 432 +/- 7 Ma. The southern terrane yielded significantly older Ar-40/Ar-39 ages with three muscovite plateau dates of 584 +/- 14 Ma, 575 +/- 15 Ma, and 459 +/- 9 Ma, a …

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Limited Migration Of Soluble Ionic Species In A Siple Dome, Antarctica, Ice Core, Karl J. Kreutz, Paul Andrew Mayewski, Sallie I. Whitlow, Mark S. Twickler Jan 1998

Limited Migration Of Soluble Ionic Species In A Siple Dome, Antarctica, Ice Core, Karl J. Kreutz, Paul Andrew Mayewski, Sallie I. Whitlow, Mark S. Twickler

Earth Science Faculty Scholarship

High-resolution (>10 samples a -1) glaciochemical analyses covering the last 110 years from a Siple Dome, Antarctica, ice core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO3 and Mg2+). Th e observed chemical migration m ay be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and m ore acidic summer (from high marine biogenic acid concentrations) layers, common at coastal sites such as Siple Dome. Exact mechanisms to explain the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are …

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Spatial Variability Of Snow Chemistry In Western Dronning Maud Land, Antarctica, Malin Stenberg, Elisabeth Isaksson, Margareta Hansson, Wibjörn Karlén, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, Niels Gundestrup Jan 1998

Spatial Variability Of Snow Chemistry In Western Dronning Maud Land, Antarctica, Malin Stenberg, Elisabeth Isaksson, Margareta Hansson, Wibjörn Karlén, Paul Andrew Mayewski, Mark S. Twickler, Sallie I. Whitlow, Niels Gundestrup

Earth Science Faculty Scholarship

During the austral summer of 1993-94 a number of 1-2 m deep snow pits were sampled in connection with firn-coring in western Dronning Maud Land, Antarctica. The traverse went from 800 to about 3000 m a.s.l. upon the high-altitude plateau. Profiles of cations (Na+, K+, Mg2+, Ca2+), anions (CI-, NO3-, SO42-, CH3SO3-) and stable oxygen isotopes (δ18O) from II snow pits are presented here. Close to the coast 2 m of snow accumulates in about 2-3 years, whilst …

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Measuring & Monitering Plant Populations, Caryl L. Elzinga, Daniel W. Salzer, John W. Willoughby Jan 1998

Measuring & Monitering Plant Populations, Caryl L. Elzinga, Daniel W. Salzer, John W. Willoughby

United States Bureau of Land Management: Staff Publications

This technical reference describes the role of effective monitoring and provides a step-by-step overview of the entire monitoring process for single plant species. The challenges of successful monitoring involve efficient and specific design and a commitment to implementation of the monitoring project, from data collection to reporting and using results. The material in this reference is presented in a logical progression from planning and objective setting, designing the methodology, and taking the measurements in the field to analyzing and presenting the data and making the necessary management responses. However, many of the steps occur simultaneously or provide feedback for the …

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Declines In Benthic Macroinvertebrate Populations In Southern Lake Michigan, 1980–1993, Thomas F. Nalepa, David J. Hartson, David L. Fanslow, Gregory A. Lang, Stephen J. Lozano Jan 1998

Declines In Benthic Macroinvertebrate Populations In Southern Lake Michigan, 1980–1993, Thomas F. Nalepa, David J. Hartson, David L. Fanslow, Gregory A. Lang, Stephen J. Lozano

United States Department of Commerce: Staff Publications

Densities of the major benthic macroinvertebrate groups declined dramatically at sites shallower than 50 m in southern Lake Michigan between 1980 and 1993. Declines in Diporeia, Oligochaeta, and Sphaeriidae ranged from 40 to 75% at these depths. Total densities declined from 16 800·m–2 in 1980–1981 to 4800·m–2 in 1992–1993 at sites in the 16–30 m depth interval and from 21 300 to 11 300·m–2 at sites in the 31–50 m depth interval. Changes at sites deeper than 50 m were minimal; only sphaeriids declined to any extent. Declines in oligochaetes and sphaeriids occurred uniformly throughout the …

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Population Growth Of Antarctic Fur Seals: Limitation By A Top Predator, The Leopard Seal?, Peter L. Boveng, Lisa M. Hiruki, Michael K. Schwartz, John L. Bengtson Jan 1998

Population Growth Of Antarctic Fur Seals: Limitation By A Top Predator, The Leopard Seal?, Peter L. Boveng, Lisa M. Hiruki, Michael K. Schwartz, John L. Bengtson

United States Department of Commerce: Staff Publications

Antarctic fur seals (Arctocephalus gazella) in the South Shetland Islands are recovering from 19th-century exploitation more slowly than the main population at South Georgia. To document demographic changes associated with the recovery in the South Shetlands, we monitored fur seal abundance and reproduction in the vicinity of Elephant Island during austral summers from 1986/1987 through 1994/1995. Total births, mean and variance of birth dates, and average daily mortality rates were estimated from daily live pup counts at North Cove (NC) and North Annex (NA) colonies on Seal Island. Sightings of leopard seals (Hydrurga leptonyx) and incidents …

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Seasonal Patterns In The Abundance And Distribution Of California Cetaceans, 1991-1992, Karin A. Forney, Jay Barlow Jan 1998

Seasonal Patterns In The Abundance And Distribution Of California Cetaceans, 1991-1992, Karin A. Forney, Jay Barlow

United States Department of Commerce: Staff Publications

This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100-150 nmi (185-278 km) of the California coast during 1991 and 1992. The results of a shipboard line-transect survey conducted in July-November 1991 (“summer”) were compared to those from aerial line-transect surveys conducted in March-April 1991 and February-April 1992 (“winter”). Using a confidence-interval-based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (a = 0.05) differences between the winter and summer surveys. Pacific white-sided dolphins (Lagenorhynchus obliquidens), Risso’s dolphins (Grampus griseus), common dolphins ( …

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Success With Serradella In The Wheatbelt, Clinton Revell, Bradley Nutt, Michael Ewing Jan 1998

Success With Serradella In The Wheatbelt, Clinton Revell, Bradley Nutt, Michael Ewing

Journal of the Department of Agriculture, Western Australia, Series 4

Clinton Revell, Bradley Nutt, and Michael Ewing review the latest developments with new varieties of French serradella and yellow seradella that should provide the basis for productive legume pastures on acidic, sandy soils throughout the wheatbelt of Western Australia

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Lee Weights Of Z/4z-Codes From Elliptic Curves, José Felipe Voloch, Judy L. Walker Jan 1998

Lee Weights Of Z/4z-Codes From Elliptic Curves, José Felipe Voloch, Judy L. Walker

Department of Mathematics: Faculty Publications

In [15: J. L. Walker, Algebraic geometric codes over rings], the second author defined algebraic geometric codes over rings. This definition was motivated by two recent trends in coding theory: the study of algebraic geometric codes over finite fields, and the study of codes over rings. In that paper, many of the basic parameters of these new codes were computed. However, the Lee weight, which is very important for codes over the ring Z/4Z, was not considered. In [14: J.-F. Voloch and J. L. Walker, Euclidean weights of codes from elliptic curves over rings], this …

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Relationships Among The First Variation, The Convolution Product, And The Fourier-Feynman Transform, Chull Park, David Skough, David Storvick Jan 1998

Relationships Among The First Variation, The Convolution Product, And The Fourier-Feynman Transform, Chull Park, David Skough, David Storvick

Department of Mathematics: Faculty Publications

In this paper we examine the various relationships that exist among the first variation, the Fourier- Feynman transform, and the convolution product for functionals on Wiener space that belong to a Banach algebra S.

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No Tillage Use For Crop Production In Kentucky Counties In 1997, G. R. Haszler Jan 1998

No Tillage Use For Crop Production In Kentucky Counties In 1997, G. R. Haszler

Soil Science News and Views

Three years ago (1994) and again last year (1996), we reported the status of no-tillage adoption in Kentucky counties. Now, CTIC has published the results for 1997. As before, Kentucky leads the nation in percent of all crops produced under no tillage, but the percentage has slightly decreased from 1996. In 1994, 44% of all crops were produced under no tillage in Kentucky, whereas in 1996, that figure had reached 51% . It dropped to 48% in 1997. The results for 1994, 1996 and 1997 are shown in Table 1. The percentage of major grain crops (corn, soybeans and small …

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Precision Agriculture: A Field Study Of Soil Test Variability And Its Effect On Accuracy Of Fertilizer Recommendations, Kenneth L. Wells, James E. Dollarhide Jan 1998

Precision Agriculture: A Field Study Of Soil Test Variability And Its Effect On Accuracy Of Fertilizer Recommendations, Kenneth L. Wells, James E. Dollarhide

Soil Science News and Views

Use of precision agriculture techniques in Kentucky during the past several years has generated interest in how to soil sample a field for use in programming computer-driven, on-the-go, variable rate fertilizer spreaders (VRS). The advantage achieved by VRS is related directly to variability of soil test (ST) values within a specific field and the accuracy of how they represent the field. Since variability of ST values commonly exists on a small scale, a very intensive sampling procedure (grids of one acre or less in size) would be required to accurately describe the nature and extent of such variability within a …

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Precision Agriculture: The Effect Of Variable Rate Fertilizer Application On Soil Test Values, Kenneth L. Wells, James E. Dollarhide Jan 1998

Precision Agriculture: The Effect Of Variable Rate Fertilizer Application On Soil Test Values, Kenneth L. Wells, James E. Dollarhide

Soil Science News and Views

Use of variable rate fertilizer spreaders (VRS) is available to farmers in many areas of Kentucky. For use of VRS, a soil fertility map must be prepared for the field to be spread which requires subdividing the field into subunits. Each subunit is then soil sampled separately. A common procedure in commercial use is to grid a field into 2.5 acre blocks and to take a composite sample of 6-8 cores along the perimeter of a circular radius of 60-80 ft from the center of each block. Each block receives a separate fertilizer recommendation based on results from the soil …

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Late Season Supplemental Nitrogen On Double-Cropped Soybeans, Curt Judy, Lloyd W. Murdock Jan 1998

Late Season Supplemental Nitrogen On Double-Cropped Soybeans, Curt Judy, Lloyd W. Murdock

Soil Science News and Views

Soybeans produce their own nitrogen for crop growth with the aid of nitrogen fixing bacteria in the soil that infect the soybean root and form nodules which contain the bacteria. This is a symbiotic relationship that benefits both the plant and the bacteria. The bacteria are able to take atmospheric nitrogen and convert it into a form of nitrogen that the plant can use. Much of the nitrogen requirement for soybean production begins at seed development. Soybean physiology studies suggest that the amount of nitrogen supplied for the soybean plant from fixation in the nodules is less than the potential …

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A Two Year Evaluation Of Nitrate-N And Triazine Herbicides In Groundwater And Surface Water Of An Intensively Row Cropped Agricultural Watershed In Western Kentucky, Larry Reber, John Potts Jan 1998

A Two Year Evaluation Of Nitrate-N And Triazine Herbicides In Groundwater And Surface Water Of An Intensively Row Cropped Agricultural Watershed In Western Kentucky, Larry Reber, John Potts

Soil Science News and Views

The quality of water in Kentucky's agricultural watersheds has received considerable attention in recent years. The main concerns in corn production areas usually center on water content of nitrate-N from commercial fertilizer and triazines from herbicide applications. Although N can be found naturally in Kentucky soils, it cannot supply all the N that corn needs to produce optimum yields. Therefore, fertilizer N is added to ensure ample nutrition. Triazines, on the other hand, do not occur naturally in the soil but are applied to the soil to effectively control weeds. Most commonly, these herbicides are applied at the time of …

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