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Articles 1891 - 1920 of 2433

Full-Text Articles in Physical Sciences and Mathematics

Effects Of Agricultural Practices On Nutrient Concentrations And Loads In Two Small Watersheds, Northwestern Arkansas, Robin G. Roggio, Kenneth F. Steele, P. F. Vendrell, M. A. Nelson Jan 1998

Effects Of Agricultural Practices On Nutrient Concentrations And Loads In Two Small Watersheds, Northwestern Arkansas, Robin G. Roggio, Kenneth F. Steele, P. F. Vendrell, M. A. Nelson

Journal of the Arkansas Academy of Science

The water quality of two small, adjacent watersheds was monitored to determine the effect of land use on nutrient loads and flow-weighted mean concentrations. Poultry litter and liquid swine waste are surface applied as fertilizer to pastures that are used for hay production and beef cattle grazing. The study area is located in northwestern Arkansas, east central Washington County. Cannon Creek, the less influenced watershed (628 hectares), contains 11% pasture; whereas, Shumate Creek, the more influenced watershed (589 hectares), contains 22% pasture and receives approximately four times more land applied animal waste as fertilizer. The remaining land cover in both …

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Using Labview To Synchronize An Infrared Diode Laser Spectrometer With A Pulsed Supersonic Jet Expansion, Philip Williams, Anthony Bednar, Eric Barnett, Scott W. Reeve Jan 1998

Using Labview To Synchronize An Infrared Diode Laser Spectrometer With A Pulsed Supersonic Jet Expansion, Philip Williams, Anthony Bednar, Eric Barnett, Scott W. Reeve

Journal of the Arkansas Academy of Science

We describe software developed with LabVIEW to provide operational control for an in-house infrared diode laser spectrometer that has been combined with a pulsed supersonic jet expansion sample source. Data were collected with this instrument using a modified version of the rapid-scanning method. A prerequisite in employing the rapid-scan detection scheme is that the modulation used to scan the laser be synchronized in time with the electrical signal used to trigger the pulsed gas valve. Software performance was evaluated by examining a series of rotation vibration (ro-vibrational) spectra for the carbon monoxide molecule in the five micron region of the …

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Continuation Of Illinois River Water Quality Monitoring Of Moores Creek, Paul F. Vendrell Dec 1997

Continuation Of Illinois River Water Quality Monitoring Of Moores Creek, Paul F. Vendrell

Technical Reports

In Northwest Arkansas, nutrients transported by surface water are a major concern. These nutrients are implicated in causing water quality impairment of lakes in Northwest Arkansas and eastern Oklahoma. The nutrients of concern are nitrogen and phosphorus. Nitrogen and phosphorus stimulate algae production in water bodies and can cause objectionable water quality. Problems associated with algae growth are aesthetic impairment, objectionable taste and odor of potable water, interference with recreation activities, and fish kills in some hyper-eutrophic cases. The sources of these nutrients are primarily from land application of confined animal wastes as soil amendments to pastures. In 1990, the …

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Arkansas Soil Fertility Studies 1996, Wayne E. Sabbe Apr 1997

Arkansas Soil Fertility Studies 1996, Wayne E. Sabbe

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

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Beaver Lake Water Quality Enhancement Project Data Analysis, Thomas Soerens, Brian E. Haggard, David G. Parker Mar 1997

Beaver Lake Water Quality Enhancement Project Data Analysis, Thomas Soerens, Brian E. Haggard, David G. Parker

Technical Reports

No abstract provided.

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Coplanarity Test For Selecting A Pair Of Charged-Particle Tracks Resulting From A Single Neutral-Particle Decay, Edwin S. Braithwaite, Wilfred J. Braithwaite Jan 1997

Coplanarity Test For Selecting A Pair Of Charged-Particle Tracks Resulting From A Single Neutral-Particle Decay, Edwin S. Braithwaite, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

It is hard to determine directly the position of a neutral subatomic particle, but when such a particle decays into a pair of charged particles, it is easy to determine the positions of the charged decay particles and thereby infer the position of the parent particle at the time of its decay. A minimum of two coordinate points for each of the two decay particles is needed to reconstruct the position of the parent vertex. The mathematics of the reconstruction process is inherently interesting, and it can be used to demonstrate to students the utility of some of the most …

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Artificial Neural Networks Used To Predict Electrical Properties Of Polymers, Sanjay K. Mitra, Qing Luo, Jerry A. Darsey Jan 1997

Artificial Neural Networks Used To Predict Electrical Properties Of Polymers, Sanjay K. Mitra, Qing Luo, Jerry A. Darsey

Journal of the Arkansas Academy of Science

The ability to predict properties of molecules prior to their synthesis can be of great importance in optimizing their design. Substantial savings in time as well as cost can be achieved if some desired properties can be predicted prior to the synthesis of the molecule. The outer orbitals of a molecule are primarily responsible for many different properties of the molecules. These outer orbital parameters can be utilized by an intelligent computing system like an Artificial Neural Network to extract necessary knowledge about the properties of the molecule. An Artificial Neural Network was trained to extract electrical parameters of several …

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New Studies Of Polyfuran And Polymers Of 3-Substituted Furan Rings, Rose M. Mcconnell, Walter E. Godwin, Bradley Phillips Jan 1997

New Studies Of Polyfuran And Polymers Of 3-Substituted Furan Rings, Rose M. Mcconnell, Walter E. Godwin, Bradley Phillips

Journal of the Arkansas Academy of Science

No abstract provided.

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Reductive Dechlorinatin Of A 2-Chloronicotinic Acid Under Finkelstein Conditions, Frank L. Setliff, Leslie B. Coop Jan 1997

Reductive Dechlorinatin Of A 2-Chloronicotinic Acid Under Finkelstein Conditions, Frank L. Setliff, Leslie B. Coop

Journal of the Arkansas Academy of Science

No abstract provided.

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Separating K+/- From Pi+/- Using In-Flight Decays To Mu+/- + Nu, Wilfred J. Braithwaite, Edwin S. Braithwaite Jan 1997

Separating K+/- From Pi+/- Using In-Flight Decays To Mu+/- + Nu, Wilfred J. Braithwaite, Edwin S. Braithwaite

Journal of the Arkansas Academy of Science

A method is presented for completely distinguishing between charged kaons and charged pions by using their charged muon (plus neutrino) decays (with neutrinos undetected) for meson laboratory momenta up to 1000 MeV/c. When either a charged kaon or a charged pion decays into a muon and a neutrino, momentum-energy (four-momentum) conservation will be used to provide unique "kinematic trajectories" for distinguishing kaon decays from pion decays when the change in three-momentum of the muon from that of either parent kaon or pion is measured (or simulated). Ina magnetic field, observation of a tracked particle showing a "kink" and/or a change …

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Electron Shock Waves: Effect Of Current On Electron Temperature And Density, Mostafa Hemmati, Mathues Shane Doss Jan 1997

Electron Shock Waves: Effect Of Current On Electron Temperature And Density, Mostafa Hemmati, Mathues Shane Doss

Journal of the Arkansas Academy of Science

In our attempt to find analytical solutions for breakdown waves, we employ a set of three-component fluid equations. In addition to reporting the method of integration of electron fluid dynamical equations through the dynamical transition region (sheath region), the wave profile for ionization rate, electron number density and electron temperature inside the sheath will be discussed. Also, the effect of the current on electron temperature, electron number density and ionization rate will be reported.

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Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs Jan 1997

Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs

Journal of the Arkansas Academy of Science

We have demonstrated significant photoconductance in indium sulfide thin films prepared by thermal vacuum evaporation ofIn2$3 powders synthesized in-house by chemical precipitation ofInCl3 or In(CH3COO)3, and (NH4)2S or Na2S. The Delta G lambda/Gdark values have been as high as 0.1 in the initial unoptimized films. Excess sulfur (via a mixture of polysulfide and sulfide ions in the synthesis bath) appears to be important in achieving reproducible and large photoconductivities. In2S3 is particularly attractive as a lower toxicity alternative to CdS in optoelectronic applications such as photovoltaic and photoconductive cells.

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Investigation Of The Statistical And Spatial Distributions Of Mercury Contaminated Fish, Surface Waters And Soils In Arkansas, H. D. Scott, J. M. Mckimmey Jan 1997

Investigation Of The Statistical And Spatial Distributions Of Mercury Contaminated Fish, Surface Waters And Soils In Arkansas, H. D. Scott, J. M. Mckimmey

Technical Reports

Mercury (Hg) contamination of fish is a widespread problem throughout much of the United States and the world (Louisiana WWW page, 1997). Levels ofHg in fish suffic1ent to exceed the FDA action level of 1 mg kg-1 have been found in many water bodies, including some in Arkansas and Louisiana. As a result of the serious public health ramifications for developing fetuses and for people that subsist on native fish, fish consumption advisories due to Hg contamination have been issued in 29 states. Contamination of surface water bodies by Hg results from deforestation, forest fires, fossil fuels, mining, natural emissions …

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Spatial Analysis Of The Cause Of Mercury Contamination Of Fish In Arkansas - A Report Submitted To The Arkansas Mercury Task Force, H. S. Lin, H. D. Scott Jan 1997

Spatial Analysis Of The Cause Of Mercury Contamination Of Fish In Arkansas - A Report Submitted To The Arkansas Mercury Task Force, H. S. Lin, H. D. Scott

Technical Reports

There have been concerns about mercury (Hg) contamination in fish in Arkansas since the discovery of the problem in the Ouachita River in 1992 (Armstrong et aI., 1995). Of the more than 170 lakes and streams sampled by the Mercury Task Force from 1992 through 1994, 23% had fish with Hg concentrations exceeding the FDA Action Level of 1 ppm (Armstrong et aI., 1995). Cause of the fish Hg contamination, however, is unknown. Given the economic, human-health and environmental costs associated with fish Hg contamination, it is critical that the cause of this widely-spread problem be identified. Determination of the …

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Acidity Studies Of Deuterated Acids And Bases Commonly Used As Buffers In Nmr Studies, Rose M. Mcconnell, Walter E. Godwin, Brant Stanley, M. Shane Green Jan 1997

Acidity Studies Of Deuterated Acids And Bases Commonly Used As Buffers In Nmr Studies, Rose M. Mcconnell, Walter E. Godwin, Brant Stanley, M. Shane Green

Journal of the Arkansas Academy of Science

Structure based drug development is currently considered to be an important strategy for drug discovery. This strategy requires that critical knowledge of the three dimensional binding site on receptor molecules be known. NMR studies are frequently employed to ascertain important structural data on individual proteins as well as complexes of proteins with ligands. Deuterium labeled acids and bases are frequently used as buffers in deuterium oxide solutions for NMR studies on the structural conformations of bioactive molecules. Since pH is an important factor in any study of the conformational and stereochemical aspects of biologically active molecules, deuterated buffers are an …

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Discovery Of Fossil Cretaceous Bird In Southwest Arkansas, Leo Carson Davis, Kathie Harris Jan 1997

Discovery Of Fossil Cretaceous Bird In Southwest Arkansas, Leo Carson Davis, Kathie Harris

Journal of the Arkansas Academy of Science

No abstract provided.

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Hydrogeological And Hydrochemical Connection Between The Decatur City Spring And Crystal Lake, Benton County, Arkansas, Demetra O. Salisbury, Ralph K. Davis Jan 1997

Hydrogeological And Hydrochemical Connection Between The Decatur City Spring And Crystal Lake, Benton County, Arkansas, Demetra O. Salisbury, Ralph K. Davis

Journal of the Arkansas Academy of Science

Arkansas is ranked nationally in the production of broilers, laying hens, turkey, swine and beef cattle. These animals produce large volumes of waste, which are spread on pasture land as a method of disposal, as well as a source of fertilizer, resulting in nonpoint source contamination of surface water and ground water. One area of concern includes the Decatur City Spring, which provides municipal water for the city of Decatur. A total of eight sites in the surrounding area were monitored routinely for water quality parameters, including pH, specific conductance, and nitrate-nitrogen. Water temperature and spring and lake stage were …

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Watershed Prioritization, David G. Parker, Rod Williams, Hubert D. Scott Dec 1996

Watershed Prioritization, David G. Parker, Rod Williams, Hubert D. Scott

Technical Reports

The overall objective of this two-year study was to evaluate the water quality in the thirty-seven sub-basin watersheds in the Illinois River in Arkansas and to arrive at a watershed prioritization list to use in targeting non-point source activities. A water quality monitoring program was conducted with sampling in all thirty-seven sub-basins during both storm and base flow events and more intensive sampling in eight representative sub-basins during stOffil events. Each sub-basin was sampled seasonally during low flow (base-flow) conditions and during high flow storm (storm flow) conditions. In addition to the regular sampling, the intensive sub-basins were sampled approximately …

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Directory Of Water Related Courses Offered At Colleges And Universites In Arkansas, Kenneth F. Steele Nov 1996

Directory Of Water Related Courses Offered At Colleges And Universites In Arkansas, Kenneth F. Steele

Technical Reports

This publication lists the water and water-related courses at several universities and colleges in Arkansas as reported during the Fall of 1996. It Is anticipated that users of this directory will extend beyond college students, and will include professionals seeking continuing education, and professors desiring to exchange information on courses. This directory is not an "absolute" source of water and water-related courses because all of the higher learning institutions in Arkansas are not listed, and, secondly, because the definition of "water and water-related" varies from institution to institution. None-the-less this directory provides a very valuable and impressive reference on water …

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Diversity Of Arkansas Water Resources Research, Kenneth F. Steele Oct 1996

Diversity Of Arkansas Water Resources Research, Kenneth F. Steele

Technical Reports

In order to understand, protect, and manage our water resources effectively knowledge is required from many diverse areas of science, engineering, economics, and sociology. These proceedings of the conference on the Diversity of Arkansas Water Resources Research reflect this need and demonstrate how researchers in the state are responding to water issues and problems in Arkansas. The papers in these proceedings are representative of the research in Arkansas, but are only a sample of the work being conducted by universities and government agencies in Arkansas. We are grateful that Arkansas has the expertise available to provide the information necessary to …

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Effects Of Zebra, Mussel, Dreissena Polymorpha Infestation On Lake Dardanelle Water Quality, Charles J. Gagen, Joseph N. Stoeckel Jun 1996

Effects Of Zebra, Mussel, Dreissena Polymorpha Infestation On Lake Dardanelle Water Quality, Charles J. Gagen, Joseph N. Stoeckel

Technical Reports

Zebra mussels recently invaded southern waterways including the Arkansas River. Large-scale filtration of suspended particulate matter by dense populations could alter reservoir ecosystem function. Furthermore, they attach to hard surfaces, thereby threatening normal operations of artificial structures. We designed this study to provide baseline data prior to establishment of high population levels of zebra mussels in Lake Dardanelle. The characterization of spatial and temporal variability in water quality, zooplankton, phytoplankton, and macrophytes will allow testing of several hypotheses. We sampled zebra mussel veliger and settling juvenile densities and zooplankton densities at four fixed sites and the key water quality variables …

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Bioaccumulation Of Methyl Mercury Through A Food Chain, J. T. Knight Jun 1996

Bioaccumulation Of Methyl Mercury Through A Food Chain, J. T. Knight

Technical Reports

The bioaccumulation of mercury through the food chain has received much attention in Arkansas during the last three years. The discovery of mercury contamination and subsequent fish consumption advisories in southwest Arkansas have increased public awareness of the potential for bioaccumulation of different toxic compounds. It is postulated that the mercury problem in Arkansas is a result of methylation and resulting bioaccumulation of mercury as methyl mercury. This study was designed to derive a Bioaccumulation Factor (BAF) for mercury in a simple food chain under controlled conditions. A BAF is calculated by dividing the concentration found in the organism by …

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Influence Of Rice Production On The Quality Of Water In Tailwater Collection Reservoirs, R. A. Dewell, T. L. Lavy Jun 1996

Influence Of Rice Production On The Quality Of Water In Tailwater Collection Reservoirs, R. A. Dewell, T. L. Lavy

Technical Reports

Since maintaining high water quality standards in the state remains a high priority, monitoring for pesticides in water sources must continue. Determining the type, concentration, and characteristics of any pesticides present in water supplies are essential to the overall assessment of water quality. Five independent locations, implementing contained water management systems and recyclable water, were monitored in 1995 and 1996. Irrigation, runoff, and pond water samples were collected every 10 to 14 days between permanent flood establishment and draining. Water samples were transported to the laboratory and extracted for 16 pesticides using solid phase extraction (SPE) techniques. Quantification and confirmation …

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Identification Of Optimal Locations For Sampling Ground Water For Pesticides In The Mississippi Delta Region Of Eastern Arkansas, H. S. Lin, H. D. Scott, J. M. Mckimmey May 1996

Identification Of Optimal Locations For Sampling Ground Water For Pesticides In The Mississippi Delta Region Of Eastern Arkansas, H. S. Lin, H. D. Scott, J. M. Mckimmey

Technical Reports

Concerns about the presence of pesticides in the Mississippi River Valley alluvial aquifer in the Arkansas Delta have generated the need to develop a map of ground water vulnerability for this region comprised of approximately 10 million acres. Based on the availability of digital data and the scale of this study. we used a modified Pesticide DRASTIC model in a GRASS GIS environment to identify areas that were physically more sensitive to pesticide contamination than other areas within the Delta. Spatial distribution of pesticide loading was estimated from pesticide application rates in different crops and crop distribution map interpreted from …

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An Introduction To Lake And Reservoir Water Quality Modeling, Kenneth H. Reckhow Mar 1996

An Introduction To Lake And Reservoir Water Quality Modeling, Kenneth H. Reckhow

Technical Reports

No abstract provided.

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Reference Sediment Selection In The Lower Mississippi Delta, M. T. Moore, C. D. Milam, Jerry L. Farris Jan 1996

Reference Sediment Selection In The Lower Mississippi Delta, M. T. Moore, C. D. Milam, Jerry L. Farris

Journal of the Arkansas Academy of Science

Floodplain deposition has been a critical part in the evolution of Arkansas' Delta ecoregion, and because ofits high potential for such events, this region is highly enriched and extremely fertile. Historically, water quality in the area has been the subject ofscientific study, and as a result littlehas been published on the effects of underlying sediment with associated benthic communities. Sediment analysis is critical to many of the ongoing aquatic studies because ofits significance as both a habitat for benthic organisms and a sink for contaminants. Seven rivers and one creek within the Delta ecoregion were examined for water chemistry, sediment …

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Illinois River Water Quality Automatic Sampler Installation, David G. Parker, Rodney Williams, Evan Teague Jan 1996

Illinois River Water Quality Automatic Sampler Installation, David G. Parker, Rodney Williams, Evan Teague

Technical Reports

No abstract provided.

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Measuring Strangeness Production From Relativisitic Collisions Between Pairs Of Nuclei Using A Vertex Time Projection Chamber, Christine A. Byrd, Wilfred J. Braithwaite Jan 1996

Measuring Strangeness Production From Relativisitic Collisions Between Pairs Of Nuclei Using A Vertex Time Projection Chamber, Christine A. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

At collider energies of 200A-GeV, tracking of charged particle pairs originating from neutrals is dominated by singlystrange KJ.' decays. Counting the number ofsecondary vertex pairs is a method of measuring the strangeness production. The VTX is a four-layer micro-strip gas time projection chamber being designed for use with the STAR instrument in an experiment using the Relativistic Heavy Ion Collider under construction at Brookhaven National Laboratory. Simulated pixel data generated from CERN's Monte Carlo detector-modeling program Geant were put into tables using the TAS sorting structures available from the STAR Collaboration. The response of VTX was mapped for charged pion …

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Wave Profile For Proforce Current Bearing Waves, Mostafa Hemmati, Steven Young Jan 1996

Wave Profile For Proforce Current Bearing Waves, Mostafa Hemmati, Steven Young

Journal of the Arkansas Academy of Science

A complete wave profile for proforce style of breakdown waves with a current behind the shock front is discussed. The solution of the electron fluid dynamical equations in the sheath region for proforce current bearing waves conforms with the expected conditins for the values of the dynamical variables at the trailing edge of the wave. The wave profile for electric field and electron velocity, temperature, and number density are presented.

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Completion Report: Arkansas State Pesticides In Ground Water Monitoring Project Phase V: Vulnerable Areas In Jackson, Monroe, Lawrence And Lonoke Counties, T. Nichols, P. Vendrell, K. Steele, H. D. Scott, C. Armstrong Jan 1996

Completion Report: Arkansas State Pesticides In Ground Water Monitoring Project Phase V: Vulnerable Areas In Jackson, Monroe, Lawrence And Lonoke Counties, T. Nichols, P. Vendrell, K. Steele, H. D. Scott, C. Armstrong

Technical Reports

In 1996, sixty-seven water samples were drawn from 65 wells, including 62 new wells and 3 wells sampled previously . One Woodruff County well and two Pulaski County wells were resampled. Thirty-two samples were drawn from 30 wells in Monroe County (well #1 was sampled 3 times during this phase) . Ten wells in Jackson County, 12 wells in Lawrence County and 10 wells in Lonoke were also tested (Figures 1-5) . With the completion of Phase V, the number of wells tested has risen to 231 with a total of 258 samples analyzed . Initially, the wells were tested …

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