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2003

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Articles 2191 - 2220 of 3876

Full-Text Articles in Physical Sciences and Mathematics

Effects Of Holocene Climate Change On Mercury Deposition In Elk Lake, Minnesota: The Importance Of Eolian Transport In The Mercury Cycle, W.F. Cannon, Walter E. Dean, John H. Bullock Jr. Feb 2003

Effects Of Holocene Climate Change On Mercury Deposition In Elk Lake, Minnesota: The Importance Of Eolian Transport In The Mercury Cycle, W.F. Cannon, Walter E. Dean, John H. Bullock Jr.

United States Geological Survey: Staff Publications

Sediments in Elk Lake, Minnesota, consist of 10,400 varve layers that provide a precise chronology for Holocene fluctuations in climate and biota recorded in the strata. Progressively greater concentrations and accumulation rates of mercury since ca. A.D. 1875 reflect deposition of anthropogenic mercury additions to the atmosphere. Within the Holocene record are numerous short intervals in which mercury concentrations and accumulation rates exceed the modern values. The highest mercury concentrations formed ca. 8 ka, coincident with a rapid change from cool, moist conditions to warm, dry conditions. A related change in flora from pine forest to prairie caused destruction of …


Parasitism, The Diversity Of Life, And Paleoparasitology, Adauto Araújo, Ana M. Jansen, Françoise Bouchet, Karl J. Reinhard, Luiz F. Ferreira Feb 2003

Parasitism, The Diversity Of Life, And Paleoparasitology, Adauto Araújo, Ana M. Jansen, Françoise Bouchet, Karl J. Reinhard, Luiz F. Ferreira

School of Natural Resources: Faculty Publications

The parasite-host-environment system is dynamic, with several points of equilibrium. This makes it difficult to trace the thresholds between benefit and damage, and therefore, the definitions of commensalism, mutualism, and symbiosis become worthless. Therefore, the same concept of parasitism may encompass commensalism, mutualism, and symbiosis. Parasitism is essential for life. Life emerged as a consequence of parasitism at the molecular level, and intracellular parasitism created evolutive events that allowed species to diversify. An ecological and evolutive approach to the study of parasitism is presented here. Studies of the origin and evolution of parasitism have new perspectives with the development of …


A Sign-Changing Solution For A Superlinear Dirichlet Problem, Ii, Alfonso Castro, Pavel Drabek, John M. Neuberger Feb 2003

A Sign-Changing Solution For A Superlinear Dirichlet Problem, Ii, Alfonso Castro, Pavel Drabek, John M. Neuberger

All HMC Faculty Publications and Research

In previous work by Castro, Cossio, and Neuberger [2], it was shown that a superlinear Dirichlet problem has at least three nontrivial solutions when the derivative of the nonlinearity at zero is less than the first eigenvalue of -Δ with zero Dirichlet boundry condition. One of these solutions changes sign exactly-once and the other two are of one sign. In this paper we show that when this derivative is between the k-th and k+1-st eigenvalues there still exists a solution which changes sign at most k times. In particular, when k=1 the sign-changing exactly-once solution persists although one-sign solutions no …


Consensus-Halving Via Theorems Of Borsuk-Ulam And Tucker, Forrest W. Simmons, Francis E. Su Feb 2003

Consensus-Halving Via Theorems Of Borsuk-Ulam And Tucker, Forrest W. Simmons, Francis E. Su

All HMC Faculty Publications and Research

In this paper we show how theorems of Borsuk-Ulam and Tucker can be used to construct a consensus-halving: a division of an object into two portions so that each of n people believes the portions are equal. Moreover, the division takes at most n cuts, which is best possible. This extends prior work using methods from combinatorial topology to solve fair division problems. Several applications of consensus-halving are discussed.


Impact Of Blackbird Damage To Sunflower: Bioenergetic And Economic Models, Brian D. Peer, H. Jeffrey Homan, George M. Linz, William J. Bleier Feb 2003

Impact Of Blackbird Damage To Sunflower: Bioenergetic And Economic Models, Brian D. Peer, H. Jeffrey Homan, George M. Linz, William J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

We constructed bioenergetic and economic models to estimate the potential impact of Red-winged Blackbirds (Agelaius phoeniceus), Common Grackles (Quiscalus quiscula), and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) on production yields of sunflower in the northern Great Plains of North America. The amount of sunflower consumed annually by males and females, after considering field metabolic rates, energy value and moisture content of achenes, and percentage of sunflower in diets was, respectively: Red-winged Blackbirds 277 g and 168 g; Common Grackles 267 g and 230 g; and Yellow-headed Blackbirds 248 g and 139 g. The per capita annual …


Temporal Genetic Variation In A Coyote (Canis Latrans) Population Experiencing High Turnover, Christen Lenney William, Karen Blejwas, John J. Johnston, Michael M. Jaeger Feb 2003

Temporal Genetic Variation In A Coyote (Canis Latrans) Population Experiencing High Turnover, Christen Lenney William, Karen Blejwas, John J. Johnston, Michael M. Jaeger

United States Department of Agriculture Wildlife Services: Staff Publications

Coyotes (Canis latrans) are mobile, adaptable canids found in a wide range of habitats across North America, with range extensions into previously unoccupied areas in the western and eastern United States. Although long-distance dispersal capabilities in both sexes (Harrison 1992) and relatively large proportions of transient coyotes that do not exhibit fidelity to a single territory (typically 13–34% of a population— Andelt 1985; Windberg and Knowlton 1988) suggest that coyotes exist as a panmictic population, other aspects of coyote behavior may increase the likelihood of local population structure.


Enterobius Vermicularis: Ancient Dna From North And South American Human Coprolites, Alena M. Iñiguez, Karl J. Reinhard, Adauto Araújo, Luiz F. Ferreira, Ana Carolina P. Vicente Feb 2003

Enterobius Vermicularis: Ancient Dna From North And South American Human Coprolites, Alena M. Iñiguez, Karl J. Reinhard, Adauto Araújo, Luiz F. Ferreira, Ana Carolina P. Vicente

School of Natural Resources: Faculty Publications

A molecular paleoparasitological diagnostic approach was developed for Enterobius vermicularis. Ancient DNA was extracted from 27 coprolites from archaeological sites in Chile and USA. Enzymatic amplification of human mtDNA sequences confirmed the human origin. We designed primers specific to the E. vermicularis 5S ribosomal RNA spacer region and they allowed reproducible polymerase chain reaction identification of ancient material. We suggested that the paleoparasitological microscopic identification could accompany molecular diagnosis, which also opens the possibility of sequence analysis to understand parasite-host evolution.


Noise-Induced Unstable Dimension Variability And Transition To Chaos In Random Dynamical Systems, Ying-Cheng Lai, Zonghua Liu, Lora Billings, Ira B. Schwartz Feb 2003

Noise-Induced Unstable Dimension Variability And Transition To Chaos In Random Dynamical Systems, Ying-Cheng Lai, Zonghua Liu, Lora Billings, Ira B. Schwartz

Department of Mathematics Facuty Scholarship and Creative Works

Results are reported concerning the transition to chaos in random dynamical systems. In particular, situations are considered where a periodic attractor coexists with a nonattracting chaotic saddle, which can be expected in any periodic window of a nonlinear dynamical system. Under noise, the asymptotic attractor of the system can become chaotic, as characterized by the appearance of a positive Lyapunov exponent. Generic features of the transition include the following: (1) the noisy chaotic attractor is necessarily nonhyperbolic as there are periodic orbits embedded in it with distinct numbers of unstable directions (unstable dimension variability), and this nonhyperbolicity develops as soon …


Efficient Incorporation Of Coa, Nad And Fad Into Rna By In Vitro Transcription, Faqing Huang Feb 2003

Efficient Incorporation Of Coa, Nad And Fad Into Rna By In Vitro Transcription, Faqing Huang

Faculty Publications

Protein enzymes frequently recruit small molecule coenzymes to perform a variety of biochemical reactions. While the catalytic activities of RNA have been expanding rapidly, a similar strategy for RNA to utilize coenzymes and to increase its functional capabilities has yet to be demonstrated. A general in vitro transcription procedure has been developed to efficiently prepare RNA with coenzymes CoA, NAD and FAD covalently attached to the 5' end. These adenosine-containing coenzymes initiate transcription under the T7 class II promoter by T7 RNA polymerase. In addition to the three coenzymes, other adenosine-containing molecules may be incorporated into the first nucleotide position …


Search For Tev Emissions From Pulsars In Binary Systems, P. T. Reynolds, Et. Al. Feb 2003

Search For Tev Emissions From Pulsars In Binary Systems, P. T. Reynolds, Et. Al.

Physical Sciences Publications

A survey of binary systems containing pulsars was conducted, with the intention of detecting Galactic sources of very high energy γ-ray emission. Observations were carried out with the Whipple 10 m imaging atmospheric Cerenkov telescope. Standard analysis techniques were applied to these sources to search for steady, unpulsed emission. Periodic tests were also performed to search for emission correlated with both the orbital and spin phases, where appropriate. Analyses indicate that the binaries in this study do not emit detectable levels of very high energy photons within the sensitivity of our instrument. The flux upper limits presented here fail to …


Paired Site Sampling For Soil Carbon Estimation – Western Australia, Edward Arnold Griffin, W H. Verboom, D G. Allen Feb 2003

Paired Site Sampling For Soil Carbon Estimation – Western Australia, Edward Arnold Griffin, W H. Verboom, D G. Allen

Natural resources research reports

This report describes a detailed paired site study at nine locations in the drier parts of south–western Australia representative of areas most recently cleared for agriculture. The pairing was of uncleared, short-term cleared and long-term cleared sites. The study provided samples for modelling soil organic carbon fluxes by CSIRO Land and Water. Analysis and interpretation of results from the samples collected and detailed soil morphology descriptions provide comprehensive documentation of the soil carbon and other soil parameters. This provides a basis for better understanding factors influencing soil carbon dynamics in soils in Western Australia, particularly in areas with sandy topsoils. …


Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report November- December 2002 January 2003, John Farley Feb 2003

Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report November- December 2002 January 2003, John Farley

Transmutation Sciences Materials (TRP)

We continue to get valuable data from sputter depth profiling of steel samples. We meet weekly to discuss progress. We took depth-profiling data on D9 steel that had been exposed to LBE. This the first time we have examined this type of steel. This is important because it will enable us to separate out two effects and determine their effect on corrosion: composition of the steel vs surface preparation.

We started to plan a small experiments using a crucible of heated LBE, with the research program to be conducted at UNLV, on basic aspects of corrosion in this system. The …


Perspectives On Radioactive Waste Disposal: A Consideration Of Economic Efficiency And Intergenerational Equity, Helen R. Neill, Robert H. Neill Feb 2003

Perspectives On Radioactive Waste Disposal: A Consideration Of Economic Efficiency And Intergenerational Equity, Helen R. Neill, Robert H. Neill

Public Policy and Leadership Faculty Publications

There are both internal and external pressures on the U.S. Department of Energy to reduce the estimated costs of isolating radioactive waste, $19 billion for transuranic waste at Waste Isolation Pilot Plant (WIPP) and $57 billion for high level waste at Yucca Mountain. The question arises whether economic analyses would add to the decision-making process to reduce costs yet maintain the same level of radiological protection. This paper examines the advantages and disadvantages of using cost-benefit analysis (CBA), a tool used to measure economic efficiency as an input for these decisions. Using a comparative research approach, we find that CBA …


A Multi-Diagnostic Investigation Of Mesospheric Bore Phenomenon, S. M. Smith, Michael J. Taylor, G. R. Swenson, C. Y. She, W. Hocking, J. Baumgardner, M. Mendillo Feb 2003

A Multi-Diagnostic Investigation Of Mesospheric Bore Phenomenon, S. M. Smith, Michael J. Taylor, G. R. Swenson, C. Y. She, W. Hocking, J. Baumgardner, M. Mendillo

All Physics Faculty Publications

Imaging measurements of a bright wave event in the nighttime mesosphere were made on 14 November 1999 at two sites separated by over 500 km in the southwestern United States. The event was characterized by a sharp onset of a series of extensive wavefronts that propagated across the entire sky. The waves were easily visible to the naked eye, and the entire event was observed for at least 5 1 2 hours. The event was observed using three wide-angle imaging systems located at the Boston University field station at McDonald Observatory (MDO), Fort Davis, Texas, and the Starfire Optical Range …


Index-Matched Boundary Techniques For The Elimination Of Acoustical Resonances, Jack H. Parker, Bradley D. Duncan Feb 2003

Index-Matched Boundary Techniques For The Elimination Of Acoustical Resonances, Jack H. Parker, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

We extend the principle of optical index of refraction to apply the concept of acoustical index for transverse acoustical wave propagation in strings. The relationship between acoustical index and mass density of the acoustic material is developed. With this theoretical link established, classic index-matching techniques are explored at acoustical boundaries. Proper selection of boundary interface segments leads to the elimination of resonant vibrationalmodes that occur in rigidly supported strings, while maintaining the nonresonant vibration response.


Personality Types In Software Engineering, Luiz Fernando Capretz Feb 2003

Personality Types In Software Engineering, Luiz Fernando Capretz

Electrical and Computer Engineering Publications

No abstract provided.


Envirocare Of Utah: Expanding Waste Acceptance Criteria To Provide Low-Level And Mixed Waste Disposal Options., B. Rogers, K. Loveland Feb 2003

Envirocare Of Utah: Expanding Waste Acceptance Criteria To Provide Low-Level And Mixed Waste Disposal Options., B. Rogers, K. Loveland

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

Envirocare of Utah operates a low-level radioactive waste disposal facility 80 miles west of Salt Lake City in Clive, Utah. Accepted waste types includes NORM, 11e2 byproduct material, Class A low-level waste, and mixed waste. Since 1988, Envirocare has offered disposal options for environmental restoration waste for both government and commercial remediation projects. Annual waste receipts exceed 12 million cubic feet. The waste acceptance criteria (WAC) for the Envirocare facility have significantly expanded to accommodate the changing needs of restoration projects and waste generators since its inception, including acceptable physical waste forms, radiological acceptance criteria, RCRA requirements and treatment capabilities, …


Temperature Dependence Of Droplet Nucleation In A Yukawa Fluid, Jinsong Li, Gerald Wilemski Feb 2003

Temperature Dependence Of Droplet Nucleation In A Yukawa Fluid, Jinsong Li, Gerald Wilemski

Physics Faculty Research & Creative Works

We have studied the temperature dependence of gas-to-liquid nucleation in Yukawa fluids with gradient theory and density functional theory. Each of these nonclassical theories exhibits a weaker (i.e., better) temperature dependence than classical nucleation theory. At fixed temperature, the reversible work to form a critical nucleus found from gradient theory approaches the value given by density functional theory as the supersaturation increases. At high temperatures, the two theories remain quite close over a wide range of vapor densities. As the temperature is reduced, the difference between the two theories increases with decreasing vapor density. Compared to the classical theory we …


Terrain Influences On Severe Convective Storms Along The Pine Ridge From East Central Wyoming To Northwest Nebraska, Richard Bann, Michael Weiland, Ray Mcanelly Feb 2003

Terrain Influences On Severe Convective Storms Along The Pine Ridge From East Central Wyoming To Northwest Nebraska, Richard Bann, Michael Weiland, Ray Mcanelly

United States Department of Commerce: Staff Publications

Severe convective weather in the warm season is a common occurrence in the high plains. The storms in the high plains are produced primarily by synoptic and mesoscale features which have been described by Doswell (1980) and Maddox et al (1981). In addition to the weather parameters involved in producing severe convective weather, local terrain can also be a factor. The effects of the large scale Rocky Mountains on development of severe thunderstorms are well known. Since the early to mid 1980s, small scale terrain has been shown to have an effect on the development of severe convective weather, primarily …


Wetlands Of Virginia: Total, Isolated And Headwater, Carl Hershner, Kirk J. Havens, Marcia Berman, Tamia Rudnicky, Daniel Schatt Feb 2003

Wetlands Of Virginia: Total, Isolated And Headwater, Carl Hershner, Kirk J. Havens, Marcia Berman, Tamia Rudnicky, Daniel Schatt

Reports

No abstract provided.


Scattering Of Ultra Wide Band X-Wave Pulses By A Sphere, Maged Fayez Moawad Feb 2003

Scattering Of Ultra Wide Band X-Wave Pulses By A Sphere, Maged Fayez Moawad

Archived Theses and Dissertations

No abstract provided.


White River Watershed Preliminary Habitat Assessment, Richard Rediske, Matt Cooper, Don Uzarski, Rod Denning, Dr. Thomas M. Burton Feb 2003

White River Watershed Preliminary Habitat Assessment, Richard Rediske, Matt Cooper, Don Uzarski, Rod Denning, Dr. Thomas M. Burton

Scientific Technical Reports

In this project, a preliminary assessment of habitats in the White River watershed was conducted. Land cover and land use were evaluated using available remote sensing data to provide an assessment of current conditions and an analysis of significant change over a 20 year period (1978 to 1992/1997/1998). Investigations of water and habitat quality were also conducted in White Lake, the drowned rivermouth wetland, and selected streams and wetlands in the tributaries and branches of the White River. The report includes significant findings and recommendations.


Detection Sensitivity Optimization Of Optical Signals Generated By Fiber Optic Bragg Gratings Under Dynamic Excitation, John Lekki, James A. Lock Feb 2003

Detection Sensitivity Optimization Of Optical Signals Generated By Fiber Optic Bragg Gratings Under Dynamic Excitation, John Lekki, James A. Lock

Physics Faculty Publications

The dynamic response of a fiber optic Bragg grating to mechanical vibrations is examined both theoretically and experimentally. The theoretical expressions describing the consequences of changes in the grating's reflection spectrum are derived for partially coherent beams in an interferometer. The analysis is given in terms of the dominant wavelength, optical bandwidth, and optical path difference of the interfering signals. Changes in the reflection spectrum caused by a periodic stretching and compression of the grating are experimentally measured using an unbalanced Michelson interferometer, a Michelson interferometer with a nonzero optical path difference. The interferometer's sensitivity to changes in the dominant …


Adl Modeling Of Jini-Upnp Bridging Using Rapide, Rehab Ahmed El Kharboutly Feb 2003

Adl Modeling Of Jini-Upnp Bridging Using Rapide, Rehab Ahmed El Kharboutly

Archived Theses and Dissertations

No abstract provided.


A Hybrid Method For Solving The Non-Rigid Point Matching Problem In 3d, Nahla El Said Feb 2003

A Hybrid Method For Solving The Non-Rigid Point Matching Problem In 3d, Nahla El Said

Archived Theses and Dissertations

No abstract provided.


A Uml Extension For Modeling Aspect-Oriented Oo Systems, Aida Atef Zakaria Feb 2003

A Uml Extension For Modeling Aspect-Oriented Oo Systems, Aida Atef Zakaria

Archived Theses and Dissertations

No abstract provided.


Techniques Of Dna-Studies On Prehispanic Ectoparasites (Pulex Sp., Pulicidae, Siphonaptera) From Animal Mummies Of The Chiribaya Culture, Southern Peru, Katharina Dittmar, U. Mammat, M. Whiting, Sonia Guillén, Karl J. Reinhard, T Goldmann Feb 2003

Techniques Of Dna-Studies On Prehispanic Ectoparasites (Pulex Sp., Pulicidae, Siphonaptera) From Animal Mummies Of The Chiribaya Culture, Southern Peru, Katharina Dittmar, U. Mammat, M. Whiting, Sonia Guillén, Karl J. Reinhard, T Goldmann

School of Natural Resources: Faculty Publications

During a paleoparasitological survey of several animal mummies (Cavia aperea f. porcellus and Canis familiaris) from Chiribaya Baja, an archaeological site in Southern Peru, an unexpected find was made. In the well preserved fur, large numbers of mummified fleas (Pulex simulans/irritans) that parasitized the animals during life were encountered. Due to the relative recent event of the host mummification and the outstanding preservation of the fleas, an attempt for the retrieval of DNA was made. A DNA extraction and sequencing protocol for archaeological ectoparasitic remains has been established, taking additional studies for tissue and protein preservation into account. Tissue preservation …


High Water Use Plant Options For The Fitzgerald River Catchment : A Case Study, P L. Hill, Nadene Schiller Feb 2003

High Water Use Plant Options For The Fitzgerald River Catchment : A Case Study, P L. Hill, Nadene Schiller

Resource management technical reports

This report summarises the outcomes of a project initiated to examine the potential to integrate high water use plant options into existing farm systems to combat rising watertables and reduce salinity and waterlogging. Planting options investigated include commercial trees, perennials, fodder shrubs, annual crops and native grasses. The research uses a new GIS based methodology for undertaking catchment scale land capability analyses.


Beaumont-Condingup Area : Catchment Appraisal 2002, A Alderman, Natural Heritage Trust (Australia) Feb 2003

Beaumont-Condingup Area : Catchment Appraisal 2002, A Alderman, Natural Heritage Trust (Australia)

Resource management technical reports

Using the Rapid Catchment Appraisal process, this report summarises current information for the Beaumont - Condingup area, east of Esperance. The object of the Rapid Catchment Appraisal is to assess the condition of, and future risks to agricultural and natural resources, and provide information for reducing those risks within geographic catchments and attempts to identify the most suitable options to manage these risks.


Groundwater Study Of The Bullaring Townsite, S Ghauri Feb 2003

Groundwater Study Of The Bullaring Townsite, S Ghauri

Resource management technical reports

A groundwater study was carried out in the townsite of Bullaring, Western Australia. This report describes the town and its catchment, the hydrogeological investigation characterising groundwater flow systems within the townsite, and recommends actions for managing salinity risk.