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1999

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Articles 1651 - 1680 of 2555

Full-Text Articles in Physical Sciences and Mathematics

Neutron Stars And Black Holes As Machos, Aparna Venkatesan, Angela V. Olinto, James W. Truran Jan 1999

Neutron Stars And Black Holes As Machos, Aparna Venkatesan, Angela V. Olinto, James W. Truran

Physics and Astronomy

We consider the contribution of neutron stars and black holes to the dynamical mass of galactic halos. In particular, we show that if these compact objects were produced by an early generation of stars with initial metallicity 10-4 Z☉, they can contribute at most 30%-40% of the Galactic halo mass without creating supersolar levels of enrichment. We show that the case for halo neutron stars and black holes cannot be rejected on metal overproduction arguments alone because of the critical factor of the choice of progenitor metallicity in determining the yields. We show that this scenario satisfies …

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The Planet, 1999, Winter, Anita White, Huxley College Of The Environment, Western Washington University Jan 1999

The Planet, 1999, Winter, Anita White, Huxley College Of The Environment, Western Washington University

The Planet

No abstract provided.

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Ground-Water Quality In Kentucky: Fluoride, Philip G. Conrad, Daniel I. Carey, James S. Webb, James S. Dinger, R. Stephen Fisher, Matthew J. Mccourt Jan 1999

Ground-Water Quality In Kentucky: Fluoride, Philip G. Conrad, Daniel I. Carey, James S. Webb, James S. Dinger, R. Stephen Fisher, Matthew J. Mccourt

Information Circular--KGS

Fluoride (F-) is an ion of the element fluorine, and is a natural component in most water resources. According to Hem (1989), fluoride concentrations in fresh water are generally less than 1 mg/L (milligrams per liter), and the concentration of fluoride in the world's oceans is about 1.3 mg/L. The source of most fluoride in natural fresh-water resources is various rocks and minerals in bedrock and sediments.

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Scwds Briefs: Volume 14, Number 4 (January 1999) Jan 1999

Scwds Briefs: Volume 14, Number 4 (January 1999)

Southeastern Cooperative Wildlife Disease Study: Publications

SCWDS BRIEFS
January 1999
Wildlife Health Alert on Neurologic Disease in Ducks and Eagles
National Wildlife Health Center of the U.S. Geological Survey (USGS)
Vacuolar myelinopathy
Michigan TB Update
Bovine tuberculosis (TB)
Liberalization of hunting regulations
TB Regs Finalized for Cervids
USDA's Animal and Plant Health Inspection Service
Captive cervid herds in regard to TB status
Eastern and Western Regional Emergency Animal Disease Eradication Organizations (READEO)
"Nimby" Test Exercise
Arkansas Elk Hunt
Model Health Protocol for Importation of Wild Elk for Restoration
Diseases of major concern, i.e., chronic wasting disease, bovine tuberculosis, brucellosis, Johne's disease, and Pasteurella pneumonia
Sarcocystis
Anaplasma …

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1999 File Geodatabase Containing Aerial Photos, Pete Reehling, Richard Mckenzie, City Of Tampa Department Of Sanitary Sewers Bay Study Group Jan 1999

1999 File Geodatabase Containing Aerial Photos, Pete Reehling, Richard Mckenzie, City Of Tampa Department Of Sanitary Sewers Bay Study Group

Images

The Bay Study Group was created by the City of Tampa in 1976 to monitor the effects of pollution abatement that occurred in Hillsborough Bay when the city’s wastewater treatment plant was upgraded from primary to advanced treatment in 1979. The Bay Study Group documented a remarkable restoration of water quality parameters and biological indicators in Hillsborough Bay from the mid 1980s until 2009, when it was disbanded. This zip Geodatabase file contains the aerial photos for the year 1999.

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Development Of Regional Climate Scenarios Using A Downscaling Approach, David Easterling Jan 1999

Development Of Regional Climate Scenarios Using A Downscaling Approach, David Easterling

United States Department of Commerce: Staff Publications

As the debate on potential climate change continues, it is becoming increasingly clear that the main concerns to the general public are the potential impacts of a change in the climate on societal and biophysical systems. In order to address these concerns researchers need realistic, plausible scenarios of climate change suitable for use in impacts analysis. It is the purpose of this paper to present a downscaling method useful for developing these types of scenarios that are grounded in both General Circulation Model simulations of climate change, and in situ station data. Free atmosphere variables for four gridpoints over the …

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Evidence Of A Feeding Aggregation Of Humpback Whales (Megaptera Novaeangliae) Around Kodiak Island, Alaska, Janice Waite, Marilyn Dahlheim, Roderick Hobbs, Sally Mizroch Jan 1999

Evidence Of A Feeding Aggregation Of Humpback Whales (Megaptera Novaeangliae) Around Kodiak Island, Alaska, Janice Waite, Marilyn Dahlheim, Roderick Hobbs, Sally Mizroch

United States Department of Commerce: Staff Publications

The known summer feeding range of the North Pacific humpback whale (Megaptera novaeangliae) extends from California, along the coasts of Oregon, Washington, and Alaska, into the Bering Sea, along the Aleutian Islands, the Sea of Okhotsk (Tomilin 1957), and to northern Japan (Rice 1977). In feeding areas of the northeastern Pacific Ocean, humpback whale photoidentification research has been concentrated off California (Calambokidis et al. 1993), southeastern Alaska (Darling and McSweeney 1985, Baker et al. 1986, 1992; Perry et al. 1990), Prince William Sound in Alaska (von Ziegesar 1992), the Oregon and Washington coasts (Calambokidis et al. 1993), and …

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Baleen Whales: Conservation Issues And The Status Of The Most Endangered Populations, Phillip Clapham, Sharon Young, Robert L. Brownell Jr. Jan 1999

Baleen Whales: Conservation Issues And The Status Of The Most Endangered Populations, Phillip Clapham, Sharon Young, Robert L. Brownell Jr.

United States Department of Commerce: Staff Publications

Most species of baleen whales were subject to intensive overexploitation by commercial whaling in this and previous centuries, and many populations were reduced to small fractions of their original sizes. Here, we review the status of baleen whale stocks, with an emphasis on those that are known or thought to be critically endangered. Current data suggest that, of the various threats potentially affecting baleen whales, only entanglement in fishing gear and ship strikes may be significant at the population level, and then only in those populations which are already at critically low abundance. The impact of some problems (vessel harassment, …

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The Carbon Cycle And Biogeochemical Dynamics In Lake Sediments, Walter E. Dean Jan 1999

The Carbon Cycle And Biogeochemical Dynamics In Lake Sediments, Walter E. Dean

United States Geological Survey: Staff Publications

The concentrations of organic carbon (OC) and CaCO3 in lake sediments are often inversely related. This relation occurs in surface sediments from different locations in the same lake, surface sediments from different lakes, and with depth in Holocene sediments. Where data on accumulation rates are available, the relation holds for organic carbon and CaCO3 accumulation rates as well. An increase of several percent OC is accompanied by a decrease of several tens of percent CaCO3 indicating that the inverse relation is not due to simple dilution of one component by another. It appears from core data that …

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Geochemistry, Toxicity, And Sorption Properties Of Contaminated Sediments And Pore Waters From Two Reservoirs Receiving Acid Mine Drainage, D. Kirk Nordstrom, Charles N. Alpers, Jennifer A. Coston, Howard E. Taylor, R. Blaine Mccleskey, James W. Ball, Scott Ogle, Jeffrey S. Cotsifas, James A. Davis Jan 1999

Geochemistry, Toxicity, And Sorption Properties Of Contaminated Sediments And Pore Waters From Two Reservoirs Receiving Acid Mine Drainage, D. Kirk Nordstrom, Charles N. Alpers, Jennifer A. Coston, Howard E. Taylor, R. Blaine Mccleskey, James W. Ball, Scott Ogle, Jeffrey S. Cotsifas, James A. Davis

United States Geological Survey: Staff Publications

Acid mine waters from the Iron Mountain Superfund Site, Shasta County, California, flow through Spring Creek Reservoir and into Keswick Reservoir on the Sacramento River. In Keswick Reservoir, the acid mine waters have neutralized on mixing with neutral-pH lake water, producing fine-grained, metalrich sediments. Sediment cores were collected during 1997 from both reservoirs for characterization and pore waters were extracted under anoxic conditions. Chemical composition, mineralogical identification, redox chemistry, sorption properties, and toxicity were determined on several samples. Metal concentrations in sediment ranged from 4 to 47 % for Fe, 200 to 4,800 mg/kg (milligrams per kilogram) for Cu, and …

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Evolution Of Quaternary Intraplate Mafic Lavas Detailed Using Helium-3 Surface Exposure And Argon-40/Argon-39 Dating, And Elemental And Helium, Strontium, Neodymium And Lead Isotopic Signatures: Potrillo Volcanic Field, New Mexico, United States Of America And San Quintin Volcanic Field, Baja California Norte, Mexico, Wendi Joan Whitehead Williams Jan 1999

Evolution Of Quaternary Intraplate Mafic Lavas Detailed Using Helium-3 Surface Exposure And Argon-40/Argon-39 Dating, And Elemental And Helium, Strontium, Neodymium And Lead Isotopic Signatures: Potrillo Volcanic Field, New Mexico, United States Of America And San Quintin Volcanic Field, Baja California Norte, Mexico, Wendi Joan Whitehead Williams

Open Access Theses & Dissertations

The Pleistocene Potrillo volcanic field (PVF) resides within the southern axis of the Rio Grande Rift, New Mexico, U.S.A., near the eastern extent of the Basin and Range Province. Its alkalic mafic volcanism has resulted in several hundred cones, flows and maars distributed over approximately 4,600 km2. Alignments are segregated into two halves relative to the East Robledo fault system that dissects this field. Three of the five maars have brought peridotitic and lower to upper crustal xenoliths to the surface; several older, non maar-related flows from the west half of the field host ultramafic clots. Stratigraphic relationships, 3He surface …

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Slip-Parallel Seismic Lineations On The Northern Hayward Fault, California, Felix Waldhauser, William L. Ellsworth, Alex Cole Jan 1999

Slip-Parallel Seismic Lineations On The Northern Hayward Fault, California, Felix Waldhauser, William L. Ellsworth, Alex Cole

United States Geological Survey: Staff Publications

A high-resolution relative earthquake location procedure is used to image the fine-scale seismicity structure of the northern Hayward fault, California. The seismicity defines a narrow, near-vertical fault zone containing horizontal alignments of hypocenters extending along the fault zone. The lineations persist over the 15-year observation interval, implying the localization of conditions on the fault where brittle failure conditions are met. The horizontal orientation of the lineations parallels the slip direction of the fault, suggesting that they are the result of the smearing of frictionally weak material along the fault plane over thousands of years.

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Are Shifts In Herbicide Use Reflected In Concentration Changes In Midwestern Rivers?, William Battaglin, Donald Goolsby Jan 1999

Are Shifts In Herbicide Use Reflected In Concentration Changes In Midwestern Rivers?, William Battaglin, Donald Goolsby

United States Geological Survey: Staff Publications

In many Midwestern rivers, elevated concentrations of herbicides occur during runoff events for 1-3 months following application. The highest or “peak” herbicide concentration often occurs during one of these runoff events. Herbicide concentrations in rivers are affected by a number of factors, including herbicide use patterns within the associated basin. Changing agricultural practices, reductions in recommended and permitted herbicide applications, shifts to new herbicides, and greater environmental awareness in the agricultural community have resulted in changes to herbicide use patterns. In the Midwestern United States, alachlor use was much larger in 1989 than in 1995, while acetochlor was not used …

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Late Quaternary Loess In Northeastern Colorado: Part I—Age And Paleoclimatic Significance, Daniel R. Muhs, John N. Aleinikoff, Thomas W. Stafford Jr., Rolf Kihl, Josh Been, Shannon A. Mahan, Scott Cowherd Jan 1999

Late Quaternary Loess In Northeastern Colorado: Part I—Age And Paleoclimatic Significance, Daniel R. Muhs, John N. Aleinikoff, Thomas W. Stafford Jr., Rolf Kihl, Josh Been, Shannon A. Mahan, Scott Cowherd

United States Geological Survey: Staff Publications

Loess in eastern Colorado covers an estimated 14,000 km2, and is the westernmost part of the North American midcontinent loess province. Stratigraphic studies indicate there were two periods of loess deposition in eastern Colorado during late Quaternary time. The first period spanned ca. 20,000 to 12,000 14C yr B.P. (ca. 20–14 ka) and correlates reasonably well with the culmination and retreat of Pinedale glaciers in the Colorado Front Range during the last glacial maximum. The second period of loess deposition occurred between ca. 11,000 and 9,000 14C yr B.P. This interval may be Holocene or may …

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Factorization And High-Energy Effective Action, Ian Balitsky Jan 1999

Factorization And High-Energy Effective Action, Ian Balitsky

Physics Faculty Publications

I demonstrate that the amplitude for high-energy scattering can be factorized as a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators—infinite gauge factors ordered along the straight line. The resulting factorization formula gives a starting point for a new approach to the effective action for high-energy scattering in QCD.

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Role Of Spontaneous Emission In Ultracold Two-Color Optical Collisions, C. I. Sukenik, T. Walker Jan 1999

Role Of Spontaneous Emission In Ultracold Two-Color Optical Collisions, C. I. Sukenik, T. Walker

Physics Faculty Publications

We have observed violet photon emission resulting from energy-pooling collisions between ultracold Rb atoms illuminated by two colors of near-resonant infrared laser light. We have used this emission as a probe of doubly excited state ultracold collision dynamics. By varying the detuning of the lasers, we have clearly identified the effect of spontaneous emission on the collision process.

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Pyrene Labeled Poly (Aryl Ether) Monodendrons: Synthesis And Photophysical Studies, Wajiha Adnan Khan Jan 1999

Pyrene Labeled Poly (Aryl Ether) Monodendrons: Synthesis And Photophysical Studies, Wajiha Adnan Khan

Seton Hall University Dissertations and Theses (ETDs)

.

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Application-Specific Extensible Operating System's Support For Mpeg Video-Encoding, Kamal Wagdy Botros Sami Jan 1999

Application-Specific Extensible Operating System's Support For Mpeg Video-Encoding, Kamal Wagdy Botros Sami

Archived Theses and Dissertations

No abstract provided.

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Backtracking In Wormhole-Switched Interconnection Networks, Soha Saad Zaghloul Abdallah Jan 1999

Backtracking In Wormhole-Switched Interconnection Networks, Soha Saad Zaghloul Abdallah

Archived Theses and Dissertations

No abstract provided.

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Parametric Polymorphism In The Simple Language, Soumaia Ahmed Al Ayyat Jan 1999

Parametric Polymorphism In The Simple Language, Soumaia Ahmed Al Ayyat

Archived Theses and Dissertations

No abstract provided.

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Semiclassical Calculation Of Cumulative Reaction Probabilities, David J. Tannor, Sophya V. Garashchuk Jan 1999

Semiclassical Calculation Of Cumulative Reaction Probabilities, David J. Tannor, Sophya V. Garashchuk

Faculty Publications

Calculation of chemical reaction rates lies at the very core of theoretical chemistry. The essential dynamical quantity which determines the reaction rate is the energy-dependent cumulative reaction probability, N(E), whose Boltzmann average gives the thermal rate constant, k(T). Converged quantum mechanical calculations of N(E) remain a challenge even for three- and four-atom systems, and a longstanding goal of theoreticians has been to calculate N(E) accurately and efficiently using semiclassical methods. In this article we present a variety of methods for achieving this goal, by combining semiclassical initial value …

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Semiclassical Calculation Of Cumulative Reaction Probabilities, Sophya V. Garashchuk, D. J. Tannor Jan 1999

Semiclassical Calculation Of Cumulative Reaction Probabilities, Sophya V. Garashchuk, D. J. Tannor

Faculty Publications

Calculation of chemical reaction rates lies at the very core of theoretical chemistry. The essential dynamical quantity which determines the reaction rate is the energy-dependent cumulative reaction probability, N(E), whose Boltzmann average gives the thermal rate constant, k(T). Converged quantum mechanical calculations of N(E) remain a challenge even for three- and four-atom systems, and a longstanding goal of theoreticians has been to calculate N(E) accurately and efficiently using semiclassical methods. In this article we present a variety of methods for achieving this goal, by combining semiclassical initial value …

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Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya V. Garashchuk, D. J. Tannor Jan 1999

Cumulative Reaction Probability In Terms Of Reactant-Product Wave Packet Correlation Functions, Sophya V. Garashchuk, D. J. Tannor

Faculty Publications

We present new expressions for the cumulative reaction probability (N(E)), cast in terms of time-correlation functions of reactant and product wave packets. The derivation begins with a standard trace expression for the cumulative reaction probability, expressed in terms of the reactive scattering matrix elements in an asymptotic internal basis. By combining the property of invariance of the trace with a wave packet correlation function formulation of reactive scattering, we obtain an expression for N(E) in terms of the correlation matrices of incoming and outgoing wave packets which are arbitrary in the internal coordinates. This formulation, like other recent formulations of …

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Ua56/1 Facts At A Glance, Wku Institutional Research Jan 1999

Ua56/1 Facts At A Glance, Wku Institutional Research

WKU Archives Records

Statistical and demographic profile of WKU.

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Ua56/1 Fact Book, Wku Institutional Research Jan 1999

Ua56/1 Fact Book, Wku Institutional Research

WKU Archives Records

Statistical and demographic profile of WKU.

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A Rapid Development Of Dependable Applications In Ad Hoc Mobility, Amy L. Murphy Jan 1999

A Rapid Development Of Dependable Applications In Ad Hoc Mobility, Amy L. Murphy

All Computer Science and Engineering Research

Advances in wireless communication and network computing technologies make possible new kinds of applications involving transient interactions among physical components that move across a wide range of spaces, from the confines of a room to the airspace across an ocean, and require no fixed networking infrastructure to communicate with one another. Such components may come together to form ad hoc networks for the purpose of exchanging information or in order to engage in cooperative task-oriented behaviors. Ad hoc networks are assembled, reshaped and taken apart as components move in and out of communication range; all interactions are transient; computations become …

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Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco Jan 1999

Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco

All Computer Science and Engineering Research

The provision of a reliable communication infrastructure for mobile agents is still an open research issue. The challenge to reliability we address in this work does not come from the possibility of faults, but rather from the mere presence of mobility, which slightly complicates the problem of ensuring the delivery of information even in a fault-free network. For instance, the asynchronous nature of message passing and agent migration may cause situations where messages forever chase a mobile agent that moves frequently from one host to another. Current solutions rely on conventional technologies that either do not provide a solution for …

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A Geomorphology Of Megaliths: Neolithic Landscapes In The Alto Alentejo, Portugal, Gregory A. Pope, Vera C. Miranda Jan 1999

A Geomorphology Of Megaliths: Neolithic Landscapes In The Alto Alentejo, Portugal, Gregory A. Pope, Vera C. Miranda

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic monuments: tombs (dolmens or antas) and ceremonial features such as standing stones (menhirs) and stone circles (cromleques). Concentrations of these monuments tend to be found on or near weathered granite terrains. Unloading slabs and remnant corestones appear to be the stones of preference for megalith makers in the Alentejo district of Portugal. Some of the stones may have been imported from distant sources, but most appear to be of local origin. In general, most stones do not appear to have been altered much from their original …

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A Biogeochemical Comparison Of Fossil (Carboniferous) And Modern Crustose Red Algae, Michael A. Kruge, John E. Utgaard, William Ferry Jan 1999

A Biogeochemical Comparison Of Fossil (Carboniferous) And Modern Crustose Red Algae, Michael A. Kruge, John E. Utgaard, William Ferry

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The nature of the contribution of the various types of algae to sedimentary organic matter continues to be a topic of research interest. Crustose red algae have however received less attention than other types. The fossil calcareous red algae (Rhodophyta) analyzed in this study are two relatively unrecrystallized specimens of Parachaetetes (Family Solenoporacea) from the lower part of the Ste. Genevieve Formation (Carboniferous, Visean) in Union County, Illinois, USA. They occurred in the patch reef phase of a small carbonate mudmound-patchreef. The three modern specimens (collected and identified by F. Collier) are the crustose algae Lithothamnion, Clathromorphum and Phymatolithon …

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Cubane Tetrameric Complexes Of Copper(I) Chloride And Bromide With Triphenyl Phosphite, Robert D. Pike, William H. Starnes Jr., Gene B. Carpenter Jan 1999

Cubane Tetrameric Complexes Of Copper(I) Chloride And Bromide With Triphenyl Phosphite, Robert D. Pike, William H. Starnes Jr., Gene B. Carpenter

Arts & Sciences Articles

The crystal structures of tetra-/z3-chloro-tetrakis[(triphenyl phosphite-P)copper(I)], [CunC14(CI8HI503P)4], and tetra-#3-bromo-tetrakis [ (triphenyl phosphite-P) - copper(I)], [Cu4Br4(CI8H1503P)4], are described. Both have distorted 'cubane' CuaX4 cores. Distortion of the cubane structure is reflected in X--Cu--X angles > 90 ° and Cu--X--Cu angles < 90 °, and is more pronounced in the bromide complex.

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