Digital Commons Network^™

The Importance Of Functional Form In Optimal Control Solutions Of Problems In Population Dynamics, Michael C. Runge, Fred A. Johnson

United States Fish and Wildlife Service: Publications

Optimal control theory is finding increased application in both theoretical and applied ecology, and it is a central element of adaptive resource management. One of the steps in an adaptive management process is to develop alternative models of system dynamics, models that are all reasonable in light of available data, but that differ substantially in their implications for optimal control of the resource. We explored how the form of the recruitment and survival functions in a general population model for ducks affected the patterns in the optimal harvest strategy, using a combination of analytical, numerical, and simulation techniques. We compared …

Organochlorine Chemical Residues In Fish From The Mississippi River Basin, 1995, C.J. Schmitt

United States Geological Survey: Staff Publications

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Fish were collected in late 1995 from 34 National Contaminant Biomonitoring Program (NCBP) stations and 13 National Water Quality Assessment Program (NAWQA) stations in the Mississippi River basin (MRB) and in late 1996 from a reference site in West Virginia. Four composite samples, each comprising (nominally) 10 adult common carp (Cyprinus carpio) or black bass (Micropterus spp.) of the same sex, were collected from each site and analyzed for organochlorine chemical residues by gas chromatography with electron capture detection. At the NCBP stations, which are located on relatively large rivers, concentrations of organochlorine chemical residues were generally lower than …

Evidence For The Timing And Duration Of The Last Interglacial Period From High-Precision Uranium-Series Ages Of Corals On Tectonically Stable Coastlines, Daniel R. Muhs

United States Geological Survey: Staff Publications

The last interglacial period has a timing and duration that can be estimated from U-series dating of emergent, coral-bearing deposits on tectonically stable coastlines. High-precision dating from Bermuda, the Bahamas, Hawaii, and Australia suggests that the last interglacial period had a sea level at least as high as present from ∼128,000 to 116,000 yr B.P. Sea level reached a near-present level more quickly after the close of the penultimate glacial period than at the close of the last glacial period and the duration of high sea level is longer than that implied by the deep-sea record.

Age Of Ground Water At City Of Lincoln's Municipal Well Field Near Ashland, Nebraska, Gregory V. Steele

United States Geological Survey: Water Reports and Publications

The Platte River alluvial aquifer, which underlies the Plaue River Valley, is an important source of water for public supply in central and eastern Nebraska. Knowing the age of ground water can help scientists and water managers better understand the dynamics of the groundwater system. In turn, this knowledge will help in calibrating groundwater-flow models and aid in developing a conceptual understanding of how long it takes for recharge water to reach certain areas of the aquifer. Although previous studies (Davis, 1992; Steele and Verstraeten, 1999; Verstraeten et al., 1999) reported the interaction of surface water and ground water at …

A Biologic Basis For Integrated Malaria Control, F. Ellis Mckenzie, J. Kevin Baird, John C. Beier, Altaf A. Lal, William H. Bossert

United States Navy: Publications

In a series ofmodels of Plasmodium falciparum dynamics, spontaneous local extinctions ofthe parasite sometimes occurred under steady, perennial-transmission conditions. These extinctions occurred only with extremely low mosquito densities or when the parameter describing the duration ofhu man infection-blocking immunity was at its maximum value, and, simultaneously, those describing vector survivorship and the duration ofhuman infectivity were at their minimum values. The range and frequency of extinctions increased with seasonal transmission, and decreased with the emergence ofrecombinant genotypes. Here we extend the immunity parameter up to levels that would describe a successful vaccine, and examine the combined influences of seasonality, genotype …

West Nile Virus: A Threat To North American Avian Species, Robert G. Mclean

United States Geological Survey: Staff Publications

West Nile virus (WNV) was introduced into the United States (US), specifically in New York City (NYC), in 1999; this translocation represented a major shift out of its normal geographical distribution of Africa, the Middle East, Europe and the western parts of Asia (Center for Disease Control 1999a). The route or method of entry into the US is still unknown. WNV is in the genus Flavivirus, the family Flaviviridae and is closely related to some other viruses in this family, such as Japanese encephalitis virus in Southeast Asia, Murray Valley encephalitis virus in Australia and St. Louis encephalitis (SLE) …

Last Interglacial Climates, George J. Kukla, Michael L. Bender, Jacques-Louis De Beaulieu, Gerard Bond, Wallace S. Broecker, Piet Cleveringa, Joyce E. Gavin, Timothy D. Herbert, John Imbrie, Jean Jouzel, Lloyd D. Keigwin, Karen-Luise Knudsen, Jerry F. Mcmanus, Josef Merkt, Daniel R. Muhs, Helmut Muller, Richard Z. Poore, Stephen C. Porter, Guy Seret, Nicholas J. Shackleton, Charles Turner, Polychronis C. Tzedakis, Isaac J. Winograd

United States Geological Survey: Staff Publications

The last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial unit MIS 5d. The age of the stage is determined by correlation to uranium–thorium dates of raised coral reefs. The most detailed proxy record of interglacial climate is found in the Vostok ice core where the temperature reached …

Timing And Warmth Of The Last Interglacial Period: New U-Series Evidence From Hawaii And Bermuda And A New Fossil Compilation For North America, Daniel R. Muhs, Kathleen R. Simmons, Bree Steinke

United States Geological Survey: Staff Publications

The timing and duration of the Last Interglacial period have been controversial, with some studies suggesting a relatively short duration that is orbitally forced and others suggesting a long duration that is at most only partly related to orbital forcing. New, high-precison thermal ionization mass spectrometric (TIMS) U-series ages of Last Interglacial corals from Hawaii and Bermuda test these competing hypotheses. Waimanalo Formation corals from slowly uplifting Oahu, Hawaii range in age from ~ 134 to ~ 113 ka, with most ages between ~ 125 and ~ 115 ka. Combined with published U-series ages from nearby Lanai, the data suggest …

Reconstruction Of Hydrological Changes And Response To Effective Moisture Variations From North-Central Usa Lake Sediments, Antje Schwalb, Walter E. Dean

United States Geological Survey: Staff Publications

Ratios of the stable isotopes of oxygen and carbon in benthic ostracodes and marl from cores taken from two lakes in north-central Minnesota reflect Holocene hydrological and vegetation changes. Oxygen isotopes show that Williams and Shingobee Lakes, located in the same watershed but with different positions along a hydrologic gradient, were connected before 9.8 ka as part of a larger lake, Lake Willobee. From 9.8–7.7 ka, the level of Lake Willobee fell as a result of glacial retreat and increasing evaporation, leaving small separated basins. Further decreases in lake level after 7.7 ka due to increasing aridity triggered the inflow …

Derivation Of Risk Based Wipe Surface Screening Levels For Industrial Scenarios, Lisa M. May, Bonnie Gaborek, Tony Pitrat, Laura Peters

Uniformed Services University of the Health Sciences

The environmental characterization of building interiors and other surfaces has generally been performed with wipe-sampling because it is a non-destructive technique. There is no consensus, however, as to the interpretation of the results of wipe-sampling. Specifically, there is not a standardized method to determine if chemicals found at sampled levels pose a threat to human health. A methodology was developed, based on acceptable health risk levels, to derive screening levels for evaluating wipe-sampling results pertaining to industrial scenarios. The methodology was based on the United States Environmental Protection Agency (USEPA) Region IX Preliminary Remediation Goal (PRG) approach; a multi-exposure methodology …

My Library At Virginia Commonwealth University: Third Year Evaluation, Jimmy Ghaphery

VCU Libraries Faculty and Staff Publications

My Library is a personalization tool that allows the library user to consolidate frequently used library resources and services. Since 1998, My Library has been available as a web page to users of the Virginia Commonwealth University Libraries. An evaluation of My Library use at Virginia Commonwealth University (VCU) was completed and published in 2000. This article reports on a follow up study that took place between March 2000 and December 2001. The article also discusses the value of My Library as a teaching tool at VCU.

The Administration's Approach To The Esa: Building A Stewardship Ethic For The 21st Century, Amy Klee

United States Bureau of Land Management: Staff Publications

When President Nixon signed the Endangered Species Act (ESA) into law in 1973, it is unlikely that anyone imagined the pivotal role it would play in a wide range of land and water management decisions. There are now over 1,200 species of plants and animals listed as threatened or endangered in the United States. Certain areas of the country that historically have had a great diversity of species are now home to large numbers oflisted plants and animals. California, for example, has 292 listed species, and Alabama has 125. In some areas, every major land and water management decision or …

Jecp/Ed Manual, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

JECP/ED is a Java program with graphic interface for simulating electron diffraction pattern. It is designed and written by Dr. Xingzhong in University of Nebraska- Lincoln. This is verision 12-2002. It can be used for simulating electron diffraction zone pattern(ZOLZ with/without FOLZ), it allows to select zone axis, high voltage, sample thickness in the simulation, optional to show index, intensity and Laue center, featureed with manuniplating the pattern with slightly tilting, 360 degree rotation, zoom. The diffraction intensity is calculated on the basis of the kinematical theory. The program is extended to simulate electron diffraction with a precession of incident …

Wyoming Toad (Bufo Baxteri), R. Andrew Odum, Paul Stephen Corn

United States Geological Survey: Staff Publications

Historically, Wyoming toads (Bufo baxteri) were abundant in the vicinity of Laramie, Albany County, Wyoming (Baxter, 1952; Corn, 1991), where they were found in the flood plains of the Big and Little Laramie rivers (Stebbins, 1985), an area of only 2,330 km² (Lewis et al., 1985). A rapid decline was observed in the mid-1970s (Lewis et al., 1985) when they disappeared from most of their range. Surveys in the early 1980s yielded few animals, and Lewis et al. f 1985) reported their possible extinction in 1983. Wyoming toads were listed as Endangered under the Endangered Species Act …

Application Of Plasma Resonance Condition For Prediction Of Large Kerr Effects, A. De, A. Puri

Physics Faculty Publications

Resonance like enhancement of magneto-optic Kerr effects (MOKEs) have been attributed to numerous effects, one of them being plasma resonance of free charge carriers, which is analytically and numerically investigated here. Analytical expressions for frequency dependent enhancement of MOKE are obtained in the general framework of the Drude model, which are then applied to well known expressions describing MOKE. The derived expressions are numerically tested for various optical constants. It is known that for certain materials, the resonance like enhancements in the Kerr spectrum occur in the near vicinity of Re[ε_xx]=1, which is generally near the …

Cyclotron Frequency Coupled Enhancement Of Kerr Rotation In Low Refractive Index-Dielectric/Magneto-Optic Bilayer Thin-Film Structures, A. De, A. Puri

Physics Faculty Publications

We investigate the enhancement of magneto-optic polar Kerr rotation over a broad range of optical frequencies. The Drude model for the dielectric tensor is considered. Resonance-like peaks in the Kerr rotation and ellipticity caused in the vicinity of a plasma edge is extended throughout the visible spectrum by deriving an expression for the cyclotron frequency such that Re(ϵ_xx)∼1 at any given incident photon energy and plasma frequency of the material. The Kerr rotation obtained by use of this expression was studied for the case of InSb and further enhancement of Kerr rotation was achieved in the …

Semiparametric Maximum Likelihood Estimates Of Spatial Dependence, R. Kelley Pace, James P. Lesage

Faculty Publications

We semiparametrically model spatial dependence via a combination of simpler weight matrices (termed spatial basis matrices) and fit this model via maximum likelihood. Estimation of the model relies on the intuition that bounds to the log-determinant term in the log-likelihood can provide penalties to overfitting both the level and pattern of spatial dependence. By relying on symmetric and doubly stochastic spatial basis matrices that reflect different weight specifications assigned to neighboring observations, we are able to derive a mathematical expression for bounds on the log-determinant term that appears in the likelihood function. These bounds can be conveniently calculated allowing us …

An Undergraduate Biophysics Program: Curricular Examples And Lessons From A Liberal Arts Context, Suzanne Amador Kane

Physics Faculty Scholarship

I wrote this article to give a thorough and comprehensive overview of what such programs look like and what sort of institutional challenges arise on putting these programs together. The stimulus for doing so was the steady stream of requests, usually via email, from other college physics departments in terested in starting up their own biophysics prohgrams and from other professors wishing to teach biophysics. --author-supplied description

Electronic Cooling Of A Generic Transmitter, Anil L. Jeswani

Electronic Theses and Dissertations

No abstract provided.

Szemeredi's Regularity Lemma And Applications, Joshua Owen Hanes

Electronic Theses and Dissertations

No abstract provided.

Are Judges Really More Principled Than Voters?, Roderick M. Hills Jr.

Faculty Articles

Eisgruber and Dworkin have substituted the life tenure and unchanging salary of Article III judges for the real property of the landed gentry, but, mutatis mutandi, the logic of their argument is the same as the old Tory case for the House of Lords. Article III courts are "forums of principle," because the Constitution guarantees that they enjoy "social prestige and a comfortable salary" regardless of their decisions. Thus, judges, like the landed gentry, do not stand to gain or lose any material benefit from their exercise of power: They can deliberate freely about the meaning of moral principle "on …

Intentionality And Ontology / By Joseph W. Ulatowski, Joseph W. Ulatowski

Electronic Theses and Dissertations

No abstract provided.

Gas-Liquid Chromatography With A Volatile 'Stationary' Liquid Phase / By Shuxia Zhou, Shuxia Zhou

Electronic Theses and Dissertations

No abstract provided.

Application Of Fvm-Based Cche2d Model To River Restoration With Riparian Vegetation, Nobuyuki Chiba

Electronic Theses and Dissertations

No abstract provided.

Nurseries Of Morality : Collegiate Constructions Of Manhood, Mary K. Clingerman

Electronic Theses and Dissertations

No abstract provided.

Software Receiver Using Undersampling Technique, Madhu Babu Anugandula

Electronic Theses and Dissertations

No abstract provided.

Pressure Variation And Resin Flow In Injection Pultrusion, Sameer S. Rahatekar

Electronic Theses and Dissertations

No abstract provided.

Analysis And Limitations Of Microstrip Directional Couplers, Ashwini Anand Almad

Electronic Theses and Dissertations

No abstract provided.

Science Teacher Education: A Wonderful Journey Around The World, Nelofer Halai

Institute for Educational Development, Karachi

No abstract provided.

Quintessence And Variation Of The Fine Structure Constant In The Cosmic Microwave Background Radiation, Greg Huey, Stephon Alexander, Levon Pogosian

Astronomy Faculty Scholarship

No abstract provided.