Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 70411 - 70440 of 78838

Full-Text Articles in Entire DC Network

Agricultural Water Quality Index, Jeffrey Cooper, Richard Rediske, Melvin Northup, Mark Thogerson, Jonathan Van Denend Jan 1998

Agricultural Water Quality Index, Jeffrey Cooper, Richard Rediske, Melvin Northup, Mark Thogerson, Jonathan Van Denend

Scientific Technical Reports

The primary purpose of the Agricultural Water Quality Index (AWQI) is to provide the agricultural community with a practical technical method for conducting cost-effective water quality assessments of rivers and streams in agroecosystems. The protocols presented have been derived from extensive literature review and the results of field research in agroecosystems performed during the summer of 1997 by the authors of this index. This assessment tool is not intended to replace those already in use by state agencies or to be used without regional modifications.


Western Australian Fisheries - Key Achievements 1997-1998, Fisheries Western Australia Jan 1998

Western Australian Fisheries - Key Achievements 1997-1998, Fisheries Western Australia

Fisheries Published Reports

The WA fishing community can look back at the past year with considerable satisfaction.

Close partnership arrangements between Government, industry, the community and Fisheries Western Australia have both consolidated and advanced the State's position at the forefront of sustainable management of marine environments and fish resources.

Together, commercial fishing and recreational fishing make 􀁚 annual $1.5 billion contribution to the Western Australian economy. Through a carefully balanced portfolio of policies and initiatives the Coalition is making sure that both sectors continue to prosper, while at the same time ensuring that future generations inherit a marine environment which we are all …


Non-Volatile Dissolved Organic Iodine In Marine Water, Xianhao Cheng Jan 1998

Non-Volatile Dissolved Organic Iodine In Marine Water, Xianhao Cheng

OES Theses and Dissertations

An analytical scheme for the determination of marine DOI has been established. The concentration of DOI is estimated as total iodine (TI) minus total inorganic iodine (TII). The concentration of total iodine is determined as [special characters omitted] after DOI has been oxidized to inorganic iodine quantitatively by intensive UV-irradiation and all the inorganic iodine in the samples had been converted to [special characters omitted] by the addition of NaClO.

Production of DOI in seawater can be via both non-phytoplankton and phytoplankton related processes. In the former, iodide is converted to DOI. In the latter, most likely, iodate is converted …


Preservice Teacher Education: Alive And Well At Two-Year Colleges, R. Collins, V. Bergeron Jan 1998

Preservice Teacher Education: Alive And Well At Two-Year Colleges, R. Collins, V. Bergeron

Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.


College Of San Mateo Mathematics And Science Teacher Education Program: A Bay Area Collaborative For Excellence In Teacher Preparation With San Jose State University And San Francisco State University, C. Tonini Jan 1998

College Of San Mateo Mathematics And Science Teacher Education Program: A Bay Area Collaborative For Excellence In Teacher Preparation With San Jose State University And San Francisco State University, C. Tonini

Journal of Mathematics and Science: Collaborative Explorations

The College of San Mateo (CSM), a community college serving the San Mateo County area of California, is part of a collaborative effort in the San Francisco Bay Area to improve mathematics and science teacher preparation. With funding mainly through the National Science Foundation, the project is locally referred to as the MASTEP Project (Math and Science Teacher Education Program). MASTEP partners include two California State Universities (San Jose State University and San Francisco State University), four community colleges (College of San Mateo, City College of San Francisco, Evergreen Valley Community College, and San Jose City College), selected K-12 schools, …


The Community College Of Philadelphia: Educating Teachers For A Changing World, K. Armstrong Jan 1998

The Community College Of Philadelphia: Educating Teachers For A Changing World, K. Armstrong

Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.


Collaborative Efforts To Enhance And Strengthen Teacher Training In Mathematics And Science, G. Turbeville, D. Jovanovich Jan 1998

Collaborative Efforts To Enhance And Strengthen Teacher Training In Mathematics And Science, G. Turbeville, D. Jovanovich

Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.


Estimates Of Annual Survival Probabilities For Adult Florida Manatees (Trichechus Manatus Latirostris), C. A. Langtimm, T. J. O'Shea, R. Pradel, C. A. Beck Jan 1998

Estimates Of Annual Survival Probabilities For Adult Florida Manatees (Trichechus Manatus Latirostris), C. A. Langtimm, T. J. O'Shea, R. Pradel, C. A. Beck

United States Geological Survey: Staff Publications

The population dynamics of large, long-lived mammals are particularly sensitive to changes in adult survival. Understanding factors affecting survival patterns is therefore critical for developing and testing theories of population dynamics and for developing management strategies aimed at preventing declines or extinction in such taxa. Few studies have used modern analytical approaches for analyzing variation and testing hypotheses about survival probabilities in large mammals. This paper reports a detailed analysis of annual adult survival in the Florida manatee (Trichechus manatus latirostris), an endangered marine mammal, based on a mark-recapture approach. Natural and boat- inflicted scars distinctively "marked" individual …


Book Review Of Paleolimnology Of Europeanmaar Lakes By J. F.W. Negendank & B. Zolitschka (Eds)., J. Platt Bradbury Jan 1998

Book Review Of Paleolimnology Of Europeanmaar Lakes By J. F.W. Negendank & B. Zolitschka (Eds)., J. Platt Bradbury

United States Geological Survey: Staff Publications

This book represents a collection of papers presented at a symposium in May, 1991 on the formation and paleolimnology of European maar lakes. Paleolimnological discussions embrace maar lake deposits of late Quaternary to early Tertiary age in Germany, France and Italy. The goal of the symposium and its outgrowth, this book, is to develop a funding initiative to study, core and analyze the deposits of these remarkable depositional systems.


Early Life History Stages Of Gulf Sturgeon In The Suwannee River, Florida, Kenneth J. Sulak, James P. Clugston Jan 1998

Early Life History Stages Of Gulf Sturgeon In The Suwannee River, Florida, Kenneth J. Sulak, James P. Clugston

United States Geological Survey: Staff Publications

Egg sampling confirmed that Suwannee River Gulf sturgeon Acipenser ozyrinchus desotoi, a subspecies of Atlantic sturgeon A. o. oxyrinchus use the same spawning site at river kilometer (rkm) 215 from the mouth of the river each year. Forty-nine eggs were recorded in 1995, and 368 were recorded in 1996. Spawning began 4-7 d after the March new moon in both years and lasted 10-11 d; in 1996, a second 10-d spawning round began on the April new moon. Developmental synchrony among eggs recovered suggested serval discrete spawning events in both years. Total eggs deposited for three 1996 sampling days …


Seasonal Patterns Of Nitrogen Fixation In Termites, A. D. Curtis, D. A. Waller Jan 1998

Seasonal Patterns Of Nitrogen Fixation In Termites, A. D. Curtis, D. A. Waller

Biological Sciences Faculty Publications

Summary

1. Termite nitrogenase activity was highest in autumn and spring (≈ 3 µg N2 fixed termite fresh mass (g)–1 day–1) and lowest in winter and summer (≈ 0·8 µg N2 fixed termite fresh mass (g)–1 day–1).

2. The nitrogenase activity of worker termites was significantly higher than all other castes (1·58 ± 0·27 µg N2 fixed termite fresh mass (g)–1 day–1).

3. Worker termites constituted the largest proportion of all the castes throughout the study period (≈ 90%).

4. The localized input of fixed nitrogen by termites …


Mesozooplankton Distribution And Abundance In The Pagan River: A Nutrient Enriched Subestuary Of The James River, Virginia, Lillian N. Davis, Harold G. Marshall Jan 1998

Mesozooplankton Distribution And Abundance In The Pagan River: A Nutrient Enriched Subestuary Of The James River, Virginia, Lillian N. Davis, Harold G. Marshall

Biological Sciences Faculty Publications

The mesozooplankton in the Pagan River was dominated by calanoid copepods, with abundance peaks occurring during late winter-early spring and from late summer into early fall. This included spring, summer, and fall abundance maxima. The total mean abundance of the mesozooplankton was 3,008/m3.


Π-Systems As Lithium/Hydrogen Bond Acceptors: Some Theoretical Observations, Salai Cheettu Ammal, P. Venuvanalingam Jan 1998

Π-Systems As Lithium/Hydrogen Bond Acceptors: Some Theoretical Observations, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio calculations at the Hartree–Fock and correlated levels and density functional theory calculations have been performed with 6-31++G(d,p) and 6-311++G(d,p)basis sets on LiF and HF complexes of benzene, ethylene, and acetylene. Complex binding energies have been corrected for basis set superposition error, and zero point energy corrections have been done on Hartree–Fock binding energies. Computed results indicate that the complexes exist in different conformations and among them those with π-lithium and π-hydrogen bonds are the most stable. π-lithium bonds are stronger than π-hydrogen bonds. The computed binding energies and geometry of HF complexes correlate well with the available experimental …


Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam Jan 1998

Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio and DFT computations have been carried out on LiF and HF complexes of a set of n-donors viz. trimethylamine, dimethyl ether and dimethyl sulfide with a 6-31++G(d,p) basis set. The effect of correlation has been included with MP2, MP4 and DFT calculations. NBO analyses of the wavefunctions have been performed to examine the intermolecular interaction at the orbital level. Calculations reveal that these donors form strong n→σ* complexes and computed binding energies of the (CH3)2O···HF complex agree very well with the experimental binding energies from IR spectroscopy. LiF forms stronger complexes than HF, …


Composition And Environmental Assessment Of Soils From United Arab Emirates, Torfa Alsheba Khames Alsheriani Jan 1998

Composition And Environmental Assessment Of Soils From United Arab Emirates, Torfa Alsheba Khames Alsheriani

Theses

The study focuses on the mineral and chemical composition, the textural characters and environmental assessment of some soils from the UAE. About forty soil samples were collected from AI Ain District and the Eastern Mountain District. Soils in AI Ain and its suburb are strongly influenced by the aeolian sedimentation, while those of the Eastern Mountain are formed in narrow valleys strikingly close to ophiolitic hinterland.

The studied soils· are remarkably impoverished in clay size fraction and clay minerals as well. This is due to the impeded chemical weathering under the prevailing arid climate. Corroborative techniques including X-ray diffraction, infrared …


Imaging Tissue Conductivity Via Contactless Measurements: A Feasibility Study, Nevzat G. Gençer, M. Nejat Tek Jan 1998

Imaging Tissue Conductivity Via Contactless Measurements: A Feasibility Study, Nevzat G. Gençer, M. Nejat Tek

Turkish Journal of Electrical Engineering and Computer Sciences

The feasibility of a new imaging system is investigated. This system will be used to image electrical conductivity distribution of biological tissues via contactless measurements. This will be achieved by introducing currents in the conductive medium using time-varying magnetic fields and measuring the magnetic fields of the induced currents. Consequently, the imaging system consists of transmitter and receiver coils placed nearby the conductive body. In this study, the basic features of the coplanar and coaxial coils are studied. The validity of the simplifying assumptions for the governing field equations is investigated. It is found that, for operating frequency of 100 …


Agricultural Water Quality Index Field Handout, Jeffrey Cooper, Richard Rediske, Melvin Northup, Mark Thogerson, Jonathan Van Denend Jan 1998

Agricultural Water Quality Index Field Handout, Jeffrey Cooper, Richard Rediske, Melvin Northup, Mark Thogerson, Jonathan Van Denend

Scientific Technical Reports

The Agricultural Water Quality Index (AWQI) is an assessment tool designed for use in agroecosystems. Most existing environmental indices and assessment tools focus on the stream channel and/or riparian zone (the area between the channel and active land use). In contrast, the AWQI places an emphasis on land use and soil types that play a significant role in hydrologic cycles and water quality characteristics within the watershed.

The AWQI is designed to be used by agricultural technicians with limited experience in aquatic ecology; however, it does assume a reasonable background in soil characteristics. This index is intended for use during …


Coastal Marine Science For Law And Business Students: Preparing Law And Business Professionals To Make "Informed Decisions" About Coastal Issues, David H. Niebuhr, Lynda L. Butler, Don Rahtz, Britt E. Anderson, April N. Lawrence Jan 1998

Coastal Marine Science For Law And Business Students: Preparing Law And Business Professionals To Make "Informed Decisions" About Coastal Issues, David H. Niebuhr, Lynda L. Butler, Don Rahtz, Britt E. Anderson, April N. Lawrence

Faculty Publications

The rigors of employment-directed undergraduate education. and decreased emphasis on "Liberal Arts" studies occurring at some colleges and universities has left many graduates with a level of scientific understanding which is inadequate to make infonned choices about issues which effect the environment. To address this lack of scientific understanding. the Chesapeake Bay National Estuarine Research Reserve (Virginia) and the Virginia Institute of Marine Science, with the Marshall-Wythe School of Law and the School of Business Administration of the College of William and Mary are developing a Coastal Ecosystem Science Program to teach future law and business professionals the basics of …


Contaminated Communities: A Video Documentary Of The Alberton, Montana Mixed-Chemical Spill And An Analysis Of How Its Effects On Toxics Victims Fits Into A Larger Contamination Framework From A Political Ecology Perspective, Lisa A. Mosca Jan 1998

Contaminated Communities: A Video Documentary Of The Alberton, Montana Mixed-Chemical Spill And An Analysis Of How Its Effects On Toxics Victims Fits Into A Larger Contamination Framework From A Political Ecology Perspective, Lisa A. Mosca

Graduate Student Theses, Dissertations, & Professional Papers

The small rural mountain town of Alberton, MT located 32 miles west of Missoula, MT was the 1996 site of the largest contamination event in railroad history involving a mixture of chemicals. On April 11, 1996 a Montana Rail Link train derailed just west of the town of Alberton, leaking 130,000 pounds of chlorine gas, 17,000 of potassium cresylate (spent oil refinery waste), and 85 dry bulk pounds of sodium chlorate into the Alberton environment. Approximately 1000 people were evacuated from their homes, many for the seventeen day evacuation period that followed. The video documentary project that I embarked on …


Hazardous Waste Determination And Government Enforcement Actions In The Resource Conservation And Recovery Act And The Law No. 24051: Comparison Between The United States And Argentina, Eduardo Jose Conghos Jan 1998

Hazardous Waste Determination And Government Enforcement Actions In The Resource Conservation And Recovery Act And The Law No. 24051: Comparison Between The United States And Argentina, Eduardo Jose Conghos

LLM Theses and Essays

The incremental generation and disposal of hazardous waste, causing severe environmental pollution, has become one the world’s most important ecological problems starting with the Stockholm Conference in 1972. This paper examines two legislative reactions to pollution caused by hazardous wastes in the United States, under the Resource Conservation and Recovery Act 1976 (RCRA), and Argentina, in Law No. 24051. This paper makes a comparative analysis of the material provisions of both the RCRA and the Law with emphasis on the tools and actions provided for the enforcement of the RCRA and the Law. The paper concludes that the RCRA and …


Random Fractals And Multifractal Measures, Kenneth E. Sunderland Jan 1998

Random Fractals And Multifractal Measures, Kenneth E. Sunderland

Theses, Dissertations and Capstones

Much of what we call fractal geometry today can be traced to the critical years around the turn of the 19th/20th century. One of the cracks in what some had considered to be a virtually complete mathematical edifice may have been the publication in 1883 of Georg Cantor's famous "perfect and dense-in-itself' set. This set, a set of points on the real line everywhere dense in itself but nowhere dense on the line, was considered at best paradoxical and at worst monstrous. It challenged standard notions of continuity since Cantor was able to prove that there existed a one-to-one and …


Effects Of Submergence On Embryonic Survival And Developmental Rate Of The Florida Applesnail, Pomacea Paludosa: Implications For Egg Predation And Marsh Management, Richard L. Turner Jan 1998

Effects Of Submergence On Embryonic Survival And Developmental Rate Of The Florida Applesnail, Pomacea Paludosa: Implications For Egg Predation And Marsh Management, Richard L. Turner

Ocean Engineering and Marine Sciences Faculty Publications

Aerial deposition of egg clutches by the aquatic Florida applesnail is believed to have evolved in response to aquatic egg predators. Adaptation to aerial conditions might, however, have rendered embryos intolerant of submergence, a potential occurrence in natural and managed marshes, rivers, and lakes. In this study, eggs were submerged in water for various durations in the laboratory to assess their ability to survive flooding; and clutches of known ages were submerged for several days in the field to determine if aquatic predators might decrease survival below levels expected to occur due to flooding alone. Submergence of clutches slowed embryonic …


Novel Synthetic Route To 5-Substituted Indoles, Helen Y. Chen Jan 1998

Novel Synthetic Route To 5-Substituted Indoles, Helen Y. Chen

Master's Theses

No abstract provided.


Biomineralization Of Magnetic Iron Minerals In Bacteria, Richard B. Frankel, Dennis A. Bazylinski, Dirk Schϋler Jan 1998

Biomineralization Of Magnetic Iron Minerals In Bacteria, Richard B. Frankel, Dennis A. Bazylinski, Dirk Schϋler

Physics

Magnetotactic bacteria orient and migrate along magnetic field lines. This ability is based on a submicron assembly of single-magnetic domain iron mineral particles that elegantly solves the problem of how to construct a magnetic dipole that is large enough to be oriented in the geomagnetic field at ambient temperature, yet fit inside a micron-sized cell. The solution is based on the ability of the bacteria to accumulate high concentrations of iron, and control the deposition, size and orientation of a specific iron mineral at specific locations in the cell.


Age, Growth, And Mortality Of Black Drum, Pogonias Cromis, In The Chesapeake Bay Region, Cynthia M. Jones, Brian Wells Jan 1998

Age, Growth, And Mortality Of Black Drum, Pogonias Cromis, In The Chesapeake Bay Region, Cynthia M. Jones, Brian Wells

OES Faculty Publications

We used otolith ageing to describe the population dynamics of black drum, Pogonias cromis, collected over a three-year period from the Chesapeake Bay region's commercial and recreational fisheries. Black drum average age, total length, and weight were 26 years, 109.5 cm, and 22.1 kg respectively. The oldest fish was 59 years and fish older than 50 years were present in the catch from 1990 to 1992. Growth in length slowed by age 20, whereas growth in weight did not slow until age 45. A von Bertalanffy growth function was fitted to our data (L(infinity) = 117.3 cm, …


The Biogeochemical Cycling Of Dissolved Organic Nitrogen In Estuarine Sediments, David J. Burdige, Shilong Zheng Jan 1998

The Biogeochemical Cycling Of Dissolved Organic Nitrogen In Estuarine Sediments, David J. Burdige, Shilong Zheng

OES Faculty Publications

Benthic fluxes and pore-water profiles of dissolved organic nitrogen and carbon (DON and DOC, respectively) were determined in seasonal studies at contrasting sites in Chesapeake Bay. Pore-water dissolved organic matter (DOM) concentrations were elevated over bottom-water values, generally increased with depth, and ranged from 15 to similar to 160 μM for DON and ~200-2000 μM for DOC. Pore-water DOM concentrations and the C:N ratio of this material showed spatial (depth) and temporal changes that varied among the sites studied. These trends appeared to be related to differences in the types of sediment organic matter (SOM) undergoing remineralization, as well as …


Iron In Ice Cores From Law Dome, East Antarctica: Implications For Past Deposition Of Aerosol Iron, R. Edwards, Peter N. Sedwick, Vin Morgan, C. F. Boutron, S. Hong Jan 1998

Iron In Ice Cores From Law Dome, East Antarctica: Implications For Past Deposition Of Aerosol Iron, R. Edwards, Peter N. Sedwick, Vin Morgan, C. F. Boutron, S. Hong

OES Faculty Publications

Total-dissolvable iron has been measured in sections of three ice cores from Law Dome, East Antarctica, and the results used to calculate atmospheric iron deposition over this region during the late Holocene and to provide a preliminary est. of aerosol iron deposition during the Last Glacial Maximum (LGM). Ice-core sections dating from 56-2730 BP (late Holocene) and ∼18 000 BP (LGM) were decontaminated using trace-metal clean techniques, and total-dissolvable iron was determined in the acidified meltwaters by flow-injection analysis. Our results suggest that the atmospheric iron flux onto the Law Dome region has varied significantly over time-scales ranging from seasonal …


Evaluation Of Toxicity, Bioavailability And Speciation Of Lead, Zinc And Cadmium In Mine/Mill Wastewaters, Mujde Erten-Unal, Bobby G. Wixson, Nord Gale, Jerry L. Pitt Jan 1998

Evaluation Of Toxicity, Bioavailability And Speciation Of Lead, Zinc And Cadmium In Mine/Mill Wastewaters, Mujde Erten-Unal, Bobby G. Wixson, Nord Gale, Jerry L. Pitt

Civil & Environmental Engineering Faculty Publications

The toxicity of common compounds of lead, cadmium and zinc was evaluated in waters similar to that found in the world's largest lead producing area in Missouri. Static, acute toxicity tests were performed using fathead minnows (Pimephales promelas) and water fleas (Daphnia magna) respectively. Test organisms were subjected to varying amounts of sulfide, carbonate, chloride and sulfate salts of lead, zinc and cadmium mixed in hard, alkaline waters typical to this region. Median lethal concentrations were calculated using nominal versus measured metal concentrations. Measured metal concentrations included four different metal fractionation (extraction/filtration) techniques at different pH …


Kinetic Studies Of The Thermal Decomposition Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Moazzam H. Bhatti, Sohail Mahmood, Muhammad Mazhar, M. Saleem Khalid, Nazar Hussain Jan 1998

Kinetic Studies Of The Thermal Decomposition Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Moazzam H. Bhatti, Sohail Mahmood, Muhammad Mazhar, M. Saleem Khalid, Nazar Hussain

Turkish Journal of Chemistry

The di- and tri-organotin complexes of general formula R$_2$SnL$_2$ and R$_3$SnL where R = C$_4$H$_9$, C$_6$H$_5$, C$_6$H$_5$CH$_2$, C$_6$H$_{11}$ and L=1-nitroso-2-naphthol, were subjected to thermal decomposition by means of thermogravimetry (TG). The decomposition occurred in steps and the kinetics of every set of reactions were determined using the method described by Coats and Redfern. These results were analysed to establish the decomposition kinetics and hence to calculate activation energies. The activation energies were also determined by applying the method described by Horowitz, which yielded comparable results.


Trace Element Signatures In Otoliths Record Natal River Of Juvenile American Shad (Alosa Sapidissima), Simon R. Thorrold, Cynthia M. Jones, Steven E. Campana, James W. Mclaren, Joseph W. H. Lam Jan 1998

Trace Element Signatures In Otoliths Record Natal River Of Juvenile American Shad (Alosa Sapidissima), Simon R. Thorrold, Cynthia M. Jones, Steven E. Campana, James W. Mclaren, Joseph W. H. Lam

OES Faculty Publications

The elemental composition of fish otoliths may represent a permanent record of the environmental conditions an individual has experienced as trace elements, incorporated into the growing surface of the otolith, reflect the physical and chemical characteristics of the ambient water. We tested the utility of trace element signatures in otoliths as natural tags of the river of origin of juvenile American shad (Alosa sapidissima) collected from the Connecticut, Hudson and Delaware Rivers in August and October 1994. Four elements (K, Mn, Sr, and Ba) showed significant variability among sites within rivers in August, although only Mg showed a …