Physical Sciences and Mathematics Commons^™

Ichnology Of Holocene Carbonate Eolianites Of The Bahamas, H. Allen Curran, Brian White

Geosciences: Faculty Publications

No abstract provided.

Behavioral Plasticity Of Modern And Cenozoic Burrowing Thalassinidean Shrimp, M. F. Miller, H. Allen Curran

Geosciences: Faculty Publications

No abstract provided.

Resilience And Recovery Of Coral Reefs From Large-Scale Disturbances: Contrasting Patterns For San Salvador Island, Bahamas, And Belize, Paulette M. Peckol, H. Allen Curran, Martha Robbart, Benjamin J. Greenstein

Geosciences: Faculty Publications

Benjamin J. Greenstein and Cindy K. Carney (eds)

San Salvador, Gerace Research Center

Coastal Effects Of Hurricane Floyd On San Salvador Island, Bahamas, H. Allen Curran, Priscilla Delano, Brian White, Meredith Barrett

Geosciences: Faculty Publications

Hurricane Floyd, a Category 4 storm with winds up to I 55 mph, made a close encounter with San Salvador Island on September 13-14, 1999. In addition to inflicting severe damage to homes, tourist facilities, businesses, and infrastructure on the island, the storm also caused considerable beach erosion and coastal modification, mostly on the western and northern coasts. This paper reports and documents with photos the findings of a survey of coastal erosion effects on four areas of the San Salvador coastline: Coast Guard Beach, Rocky Point south to Cockburn Town and Fernandez Bay, South of Sugarloaf toward Grotto Bay, …

Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt

All Peer-Reviewed Publications

The effect of solar radiation, rainfall and cannibalism on the disappearance of eggs and larvae of the cereal stemborer Chilo partellus (Swinhoe) were studied. Disappearance and nonviability of egg batches was higher on plants exposed to solar radiation than on shaded plants. Significantly fewer small larvae were recovered from plants exposed to rainfall than from shielded plants. Cannibalism among larvae of the same size was not common except at high larval densities. Contrary to the common belief that disappearance is the result of prédation, these studies show that solar radiation and rainfall might also play an important role in the …

Habitat Management Strategies For The Control Of Cereal Stemborers And Striga In Maize In Kenya, Z. R. Khan, J. A. Pickett, L. Wadhams, F. Muyekho

All Peer-Reviewed Publications

Maize is the principal food and cash crop for millions of people in the predominantly mixed crop-livestock farming systems in Kenya. Stemborers and striga (Striga hermonthica) are major constraints to increased maize production in eastern Africa. An intercropping and trap crop system has been developed, using a ‘push-pull’ strategy, for the control of stemborers in small scale maize farming systems. The ‘push-pull’ strategy involves trapping stemborers on highly susceptible trap plants (pull) and driving them away from the crop using repellent intercrops (push). Napier grass (Pennisetum piirpiirenm Schumach) and Sudan grass (Sorghum vulgare sudanense Stapf J are used as trap …

Uber Potenzsummenpolynome (On Polynomials Of Sums Of Power), Jorg Feldvoss

University Faculty and Staff Publications

No abstract provided.

Electron Cyclotron Resonance Heating In Spherical Plasmas: O-X-Ebw Mode Conversion In Mast, Josef Preinhaelter, M. A. Irzak, Linda L. Vahala, George Vahala

Electrical & Computer Engineering Faculty Publications

Using a full wave solution, the O-X-EBW mode conversion is examined for density and magnetic profiles in MAST. The effects of magnetic shear and the sharp density pedestal for H-mode operation are considered with an eye to understanding both electron cyclotron emission (ECE) and electron cyclotron resonance heating (ECRH).

Boron-Doped Homoepitaxial Diamond (100) Film Investigated By Scanning Tunneling Microscopy, Bing Xiao, Weihai Fu, Sacharia Albin, Jason Moulton, John Cooper

Electrical & Computer Engineering Faculty Publications

Conducting epitaxial diamond films of high quality are essential for many diamond studies and diamond electronic device fabrication. We have grown boron-doped epitaxial diamond films on type Ila natural diamond (100) substrates by microwave plasma chemical vapor deposition. A gas mixture of H₂/CH₄ was used. Boron doping was done by placing solid sources of pure boron in the microwave plasma. Homoepitaxial films with atomic smoothness were achieved under the following growth conditions: substrate temperature 900 °C, gas pressure 40 Torr, and gas flow rates of H₂/CH₄ = 900/7.2 seem. The growth rate was 0.87 …

Water And Growth In Colorado: A Review Of Legal And Policy Issues, Peter D. Nichols, Megan K. Murphy, Douglas S. Kenney, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

xiv, 191 p. : ill., maps (some col.) ; 28 cm

Preliminary Evaluation Of A Guideline Classification System, Elmer Bernstam, Nachman Ash, Mor Peleg, Samson Tu, Edward H. Shortliffe, Robert A. Greenes

Faculty, Staff and Student Publications

In a previous paper, we presented a proposed expansion of the National Guideline Clearing-house (NGC) classification1. We performed a preliminary evaluation of the classification based on 100 guidelines randomly selected from the NGC collection. We found that 89 of the 100 guidelines could be assigned to a single guideline category. To test inter-observer agreement, twenty guidelines were also categorized by a second investigator. Agreement was found to be 40-90% depending on the axis, which compares favorably with agreement among MeSH indexers (30-60%)2. We conclude that categorization is feasible. Further research is needed to clarify axes with poor inter-observer agreement.

Order-Disorder Phase Transitions In Kno2 , Csno2, And Tlno2 Crystals: A Molecular Dynamics Study, Chun-Gang Duan, Wai-Ning Mei, R. W. Smith, Jianjun Liu, M. M. Ossowski, John R. Hardy

John R. Hardy Papers

The order-disorder phase transitions of KNO₂ , CsNO₂, and TlNO₂ have been studied using parameter-free molecular dynamics simulation. It is found that the phase transitions in nitrites investigated are driven by the rotations of the NO₂^- ions about different axes together with displacements of cations and anions. We successfully reproduce the high-temperature phases of these nitrites, i.e., the NaCl-like structure for KNO₂ and CsCl-like structure for Cs(Tl)NO₂. Based on the investigation of the radial distribution function of the cations and anions, we explain why KNO₂ and Cs(Tl)NO₂ form quite …

Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium: Ii. H2 And He, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd

M. Eugene Rudd Publications

We have studied the energy and angular distributions of low-energy electron emission in collisions of bare carbon ions of 1-MeV/u energy with He and H₂ targets. The double-differential cross sections (DDCS’s) are measured for electrons with energies between 0.5 and 300 eV emitted within an angular range of 15° to 160°. The large forward-backward asymmetry observed in the angular distributions is explained in terms of the two-center effect. Single differential cross sections (SDCS’s) and total cross sections are also derived by integrating the DDCS’s over emission angles and energies. The data are compared with different theoretical calculations based on …

Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium. I. Atomic Hydrogen, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd, R. Moshammer

M. Eugene Rudd Publications

We have investigated ionization mechanisms in fast ion-atom collisions by measuring the low-energy electron emission cross sections in a pure three-body collision involving bare carbon ions (v=6.35 a.u.) colliding with atomic hydrogen targets. The measurements have also been extended to molecular hydrogen and helium targets. In this paper we provide the energy and angular distributions of double differential cross sections of low-energy electron emission for atomic hydrogen targets. The Slevin rf source with a high degree of dissociation was used to produce the atomic H target. It is found that the two-center effect has a major influence on …

Search For Electroweak Production Of Single Top Quarks In Pp̅ Collisions, B. Abbott

Gregory Snow Publications

We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ≈90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the D Ø detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process pp̅→tb+X of 39 pb. The upper limit for the t-channel processpp̅→tqb+X …

Perspectives Of Giant Magnetoresistance, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

Giant magnetoresistance (GMR) is one of the most fascinating discoveries in thin-film magnetism, which combines both tremendous technological potential and deep fundamental physics. Within a decade of GMR being discovered in 1988 commercial devices based on this phenomenon, such as hard-disk read-heads, magnetic field sensors and magnetic memory chips, had become available in the market. These achievements would not have been possible without a detailed understanding of the physics of GMR, which requires a quantum-mechanical insight into the electronic spin-dependent transport in magnetic structures.

Major Herbicides In Ground Water: Results From The National Water-Quality Assessment, Jack . E. Barbash, Gail P. Thelin, Dana W. Kolpin, Robert J. Gilliom

United States Geological Survey: Staff Publications

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydro- logic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides—atrazine (2-chloro-4-ethylamino-6-iso-propylamino- s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis- [ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N- [methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]- N-[ 2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N- [2-ethyl-6-methylphenyl]-N-[2-methoxy-1-methylethyl]acetamide)— as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 μg L^-1 at 98% …

Impact Of Climate And Parent Material On Chemical Weathering In Loess-Derived Soils Of The Mississippi River Valley, Daniel R. Muhs, E. A. Bettis Iii, J. Been, J. P. Mcgeehin

United States Geological Survey: Staff Publications

Peoria Loess-derived soils on uplands east of the Mississippi River the midcontinent of North America (Ruhe, 1969; Hall valley were studied from Louisiana to Iowa, along a south-to-north and Anderson, 2000), Alaska (Muhs et al., 2001), and gradient of decreasing precipitation and temperature. Major element China (Maher et al., 1994). Critical to paleoclimatic interanalyses of deep loess in Mississippi and Illinois show that the composi- pretations, using paleosols, are reliable climofunctions tion of the parent material is similar in the northern and southern for modern soils, which give an understanding of soil parts of the valley. We hypothesized that in …

Inhibition Of Erythrocyte Δ- Aminolevulinic Acid Dehydratase (Alad) Activity In Fish From Waters Affects By Lead Smelters, Christopher J. Schmitt, Colleen A. Caldwell, Bill Olsen, Dave Serdar

United States Geological Survey: Staff Publications

We assessed the effects on fish of lead (Pb) released to streams by smelters located in Trail, BC (Canada), E. Helena, MT, Herculaneum, MO, and Glover, MO. Fish were collected by electrofishing from sites located downstream of smelters and from reference sites. Blood from each fish was analyzed for δ-aminolevulinic acid dehydratase (ALAD) activity and hemoglobin (Hb), and samples of blood, liver, or carcass were analyzed for Pb, zinc (Zn), or both. Fish collected downstream of all four smelters sites had elevated Pb concentrations, decreased ALAD activity, or both relative to their respective reference sites. At E. Helena, fish from …

Remnant Colloform Pyrite At The Haile Gold Deposit, South Carolina: A Textural Key To Genesis, Nora Foley, Robert A. Ayuso, Robert R. Seal Ii

United States Geological Survey: Staff Publications

Auriferous iron sulfide-bearing deposits of the Carolina slate belt have distinctive mineralogical and textural features—traits that provide a basis to construct models of ore deposition. Our identification of paragenetically early types of pyrite, especially remnant colloform, crustiform, and layered growth textures of pyrite containing electrum and pyrrhotite, establishes unequivocally that gold mineralization was coeval with deposition of host rocks and not solely related to Paleozoic tectonic events. Ore horizons at the Haile deposit, South Carolina, contain many remnants of early pyrite: (1) fine-grained cubic pyrite disseminated along bedding; (2) finegrained spongy, rounded masses of pyrite that may envelop or drape …

2,3,7,8-Tetrachlorodibenzo-P-Dioxin Induces Apoptotic Cell Death And Cytochrome P4501a Expression In Developing Fundulus Heteroclitus Embryos, Barbara Holland Toomey, Susan Bello, Mark E. Hahn, Susannah Cantrell, Peggy Wright, Donald E. Tillitt, Richard T. Di Giulio

United States Geological Survey: Staff Publications

Fundulus heteroclitus embryos were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during early development using nanoinjection or water bath exposure. TCDD caused developmental abnormalities that included hemorrhaging, loss of vascular integrity, edema, stunted development and death. The LC₅₀ and LD₅₀ of TCDD for Fundulus embryos were ~19.7 ± 9.5 pg TCDD/µl (water bath) and 0.25 ± 0.09 ng TCDD/g embryo (nanoinjection). To identify a possible cause for these developmental abnormalities we analyzed the effects of TCDD on apoptotic cell death and cytochrome P4501A (CYP1A) expression in the embryos. TCDD exposure increased apoptotic cell death in several tissues including brain, …

Fluvial Processes And Passive Rehabilitation Of The Lisbon Bottom Side-Channel Chute, Lower Missouri River, Robert B. Jacobson, Mark S. Laustrup, Michael D. Chapman

United States Army Corps of Engineers, Omaha District

Multiple large floods in 1993-1997 on the Lower Missouri River carved a side-channel chute through the river bottom at Lisbon, Missouri. Although similar in some respects to engineered side-channel chutes designed for habitat rehabilitation projects, the Lisbon Bottom chute has been unique in that it was allowed to evolve for more than four years with minimal stabilization. During the wet years, 1996-1999, the chute was subjected to abnormally high discharges and passed as much as 20% of the total discharge of the Missouri River. Relatively unrestrained fluvial processes during this time created a wide channel with highly diverse habitats. The …

Origin Of Late Quaternary Dune Fields On The Southern High Plains Of Texas And New Mexico, Daniel R. Muhs, Vance T. Holliday

United States Geological Survey: Staff Publications

Mostly stabilized late Holocene eolian sands on the Southern High Plains of the United States were studied to determine their origins and to assess whether present dune stability depends more strongly on sediment supply, sediment availability, or transport limitations. Geomorphic, sedimentological, and geochemical trends indicate that late Holocene dunes formed under westerly paleowinds, broadly similar to those of today. Mineralogical and geochemical data indicate that the most likely source for the sands is not the Pecos River valley, but the Pleistocene Blackwater Draw Formation, an older, extensive eolian deposit in the region. These observations suggest that new sand is supplied …

Vegetation And Paleoclimate Of The Last Interglacial Period, Central Alaska, Daniel R. Muhs, Thomas A. Ager, James E. Begét

United States Geological Survey: Staff Publications

The last interglacial period is thought to be the last time global climate was signi"cantly warmer than present. New stratigraphic studies at Eva Creek, near Fairbanks, Alaska indicate a complex last interglacial record wherein periods of loess deposition alternated with periods of soil formation. The Eva Forest Bed appears to have formed about the time of or after deposition of the Old Crow tephra (dated to ~ 160 to ~ 120 ka), and is therefore correlated with the last interglacial period. Pollen, macrofossils, and soils from the Eva Forest Bed indicate that boreal forest was the dominant vegetation and precipitation …

Evolution Of Soils On Quaternary Reef Terraces Of Barbados, West Lndies, Daniel R. Muhs

United States Geological Survey: Staff Publications

Soils on uplifted Quaternary reef terraces of Barbados, ~125,000 to ~700,000 yr old, form a climo-chronosequence and show changes in physical, chemical, and mineralogical properties with terrace age. Parent materials are dust derived from the Sahara, volcanic ash from the Lesser Antilles island arc, and detrital carbonate from the underlying reef limestone. Although some terrace soils are probably eroded, soils or their remnants are redder and more clay-rich with increasing terrace age. Profile-average Al₂O₃ and Fe₂O₃ content increases with terrace age, which partially reflects the increasing clay content, but dithionite-extractable Fe also increases with …

Comparison Of Instream Methods For Measuring Hydrolic Conductivity In Sandy Streambeds, Matthew K. Landon, David L. Rus, F. Edwin Harvey

United States Geological Survey: Staff Publications

Streambed hydraulic conductivity (K) values were determined at seven stream transects in the Platte River Basin in Nebraska using different instream measurement techniques.

The Pacific Island Mapping Program Of The Us Geological Survey, Frank C. Whitmore Jr.

United States Geological Survey: Staff Publications

A little-known aspect of the U.S. Geological Survey history is its involvement in preparing terrain intelligence reports during World War II. The Survey's Military Geology Unit was in charge of compiling these reports on areas of possible military operations. Maps were the main part of' these studies; they were compiled from existing maps, geologic and soils literature, aerial and ground photographs, and travelers' accounts. Compiled geologic anti soils maps served as basic data for interpretative maps on such subjects as construction materials. water supply, road and airfield siting and construction, and cross-country movement by tanks.

Evidence For Millennial-Scale Climate Change During Marine Isotope Stages 2 And 3 At Little Lake, Western Oregon, U.S.A., Laurie D. Grigg, Cathy Whitlock, Walter E. Dean

United States Geological Survey: Staff Publications

Pollen and geochemical data from Little Lake, western Oregon, suggest several patterns of millennial-scale environmental change during marine isotope stage (MIS) 2 (14,100–27,600 cal yr B.P.) and the latter part of MIS 3 (27,600–42,500 cal yr B.P.). During MIS 3, a series of transitions between warm- and cold-adapted taxa indicate that temperatures oscillated by ca. 2±–4±C every 1000–3000 yr. Highs and lows in summer insolation during MIS 3 are generally associated with the warmest and coldest intervals. Warm periods at Little Lake correlate with warm sea-surface temperatures in the Santa Barbara Basin. Changes in the strength of the subtropical high …

Occurrence Of Cyanazine Compounds In Groundwater: Degradates More Prevalent Than The Parent Compound, Dana Kolpin, E. Michael Thurman, S. Michael Linhart

United States Geological Survey: Staff Publications

A recently developed analytical method using liquid chromatography/mass spectrometry was used to investigate the occurrence of cyanazine and its degradates cyanazine acid (CAC), cyanazine amide (CAM), deethylcyanazine (DEC), and deethylcyanazine acid (DCAC) in groundwater. This research represents some of the earliest data on the occurrence of cyanazine degradates in groundwater. Although cyanazine was infrequently detected in the 64 wells across Iowa sampled in 1999, cyanazine degradates were commonly found during this study. The most frequently detected cyanazine compound was DCAC (32.8%) followed by CAC (29.7%), CAM (17.2%), DEC (3.1%), and cyanazine (3.1%). The frequency of detection for cyanazine or one …

Effect Of Scale On The Behavior Of Atrazine In Surface Waters, Paul Capel, Steven Larson

United States Geological Survey: Staff Publications

Field runoff is an important transport mechanism by which agricultural pesticides, including atrazine, move into the hydrologic environment. Atrazine is chosen because it is widely used, is transported in runoff relatively easily, is widely observed in surface waters, and has relatively little loss in the stream network. Data on runoff of atrazine from experimental plot and field studies is combined with annual estimates of load in numerous streams and rivers, resulting in a data set with 408 observations that span 14 orders of magnitude in area. The load as a percent of use (LAPU) on an annual basis is the …