Physical Sciences and Mathematics Commons^™

Crystal-Size Distributions And Possible Biogenic Origin Of Fe Sulfides, Mihály Pósfai, Krisztina Cziner, Emö Márton, Péter Márton, Peter R. Buseck, Richard B. Frankel, Dennis A. Bazylinski

Physics

Sedimentary greigite (Fe₃S₄) can form either by ''biologically controlled'' or by ''biologically induced mineralization'' (BCM and BIM, respectively). In order to identify the origin of magnetic Fe sulfides, we studied and compared the sizes and morphologies of greigite crystals produced by a magnetotactic microorganism (previously described and referred to as the ''many-celled magnetotactic prokaryote'', MMP) and Fe sulfides from two specimens of Miocene sedimentary rocks (from Łaka, in the foredeep of the Western Carpathians and from Michalovce, in the Transcarpathian Depression). Greigite grains from the MMP and the Łaka rock show nearly Gaussian crystal-size distributions (CSDs), …

Historical Water-Quality Data For The High Plains Regional Ground-Water Study Area In Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, And Wyoming, 1930–98, David W. Litke

United States Geological Survey: Publications

The High Plains aquifer underlies 174,000 square miles in parts of eight States and includes eight primary hydrogeologic units, including the well-known Ogallala Formation. The High Plains aquifer is an important resource, providing water for 27 percent of the Nation’s irrigated agricul¬tural lands in an otherwise dry landscape. Since the 1980’s there has been concern over the sustainability of the aquifer due to water-level declines caused by substantial pumping. Water quality of the aquifer is a more recent concern. As part of the U.S. Geological Survey’s National Water-Quality Assessment Program, historical water-quality data have been gathered for the High Plains …

Off-Axis Electron Holography Of Magnetotactic Bacteria: Magnetic Microstructure Of Strains Mv-1 And Ms-1, R. E. Dunin-Borkowski, Martha R. Mccartney, Mihály Pósfai, Richard B. Frankel, Dennis A. Bazylinski, Peter R. Buseck

Physics

Off-axis electron holography in the transmission electron microscope is used to characterize the magnetic microstructure of magnetotactic bacteria. The practical details of the technique are illustrated through the examination of single cells of strains MV-1 and MS-1, which contain crystals of magnetite (Fe₃O₄) that are ~50nm in size and are arranged in chains. Electron holography allows the magnetic domain structures within the nanocrystals to be visualized directly at close to the nanometer scale. The crystals are shown to be single magnetic domains. The magnetization directions of small crystals that would be superparamagnetic if they were isolated …

Snags In Beaver Ponds And Indications Of Use By Primary Cavity-Nesting Birds In The Western Oregon Cascades, Jacqueline I. Fern

Dissertations and Theses

Dead trees, or snag , are used by primary cavity-nesting birds for nesting, foraging, and roosting and are essential habitat for the e species. Snags formed in beaver ponds due to flooded conditions are utilized by a variety of woodpecker species. In this study I quantified and compared snag density, size, decay characteristics, and excavations in beaver ponds and in forested riparian sites without beaver influence (reference sites) in the western Oregon Cascades. Beaver ponds were treated as a pooled group (n=8) and also categorized into old (n=5) and new (n=3) classes based on decay indicators. Reference sites (n=8) were …

Emacs Speaks Statistics: A Universal Interface For Statistical Analysis, Anthony Rossini, Martin Maechler, Kurt Hornik, Richard M. Heiberger, Rodney Sparapani

UW Biostatistics Working Paper Series

Emacs Speaks Statistics (ESS) is a user interface for developing statistical applications and performing data analysis using any of several common statistical programming languages. ESS falls in the programming tools category of Integrated Development Environments (IDEs), which are approaches for developing and visualizing computer programs. We discuss how it works, the advantages of using it, and extensions for increasing statistical programming efficiency.

Evidence For Temperature Dependent Moments Ordering In Ferromagnetic Nimnsb(100), C.N. Borca, Takashi Komesu, Hae-Kyung Jeong, Peter A. Dowben, Delia Ristoiu, Ch. Hordequin, J. P. Nozie`Res, J. Pierre, Shane Stadler, Y. U. Idzerda

Peter Dowben Publications

From magnetic circular dichroism measurements of the Heusler alloy NiMnSb, in combination with other techniques, we show that a dramatic increase in the Mn and Ni moments occurs below a ‘‘crossover’’ transition temperature of about 80–100 K. This phase transition is well below the Curie temperature of NiMnSb (~730 K). While the spin polarization near the Fermi level, from spin-polarized inverse photoemission, remains very high for k_II50, it is unlikely that NiMnSb is a half-metallic ferromagnet near room temperature.

A Construction Of Compactly-Supported Biorthogonal Scaling Vectors And Multiwavelets On $R^2$, Bruce Kessler

Mathematics Faculty Publications

In \cite{K}, a construction was given for a class of orthogonal compactly-supported scaling vectors on $\R^{2}$, called short scaling vectors, and their associated multiwavelets. The span of the translates of the scaling functions along a triangular lattice includes continuous piecewise linear functions on the lattice, although the scaling functions are fractal interpolation functions and possibly nondifferentiable. In this paper, a similar construction will be used to create biorthogonal scaling vectors and their associated multiwavelets. The additional freedom will allow for one of the dual spaces to consist entirely of the continuous piecewise linear functions on a uniform subdivision of the …

Insufficiency Of Piecewise Evolution, Sanza Kazadi, Yan Qi, Isaac Park, Nancy Huang, Paul Hwu, Brian Kwan, Wayne Lue, Hubert Li

Sanza Kazadi

Microscopic Kinetics And Time-Dependent Structure Factors, T. Aspelmeier, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

The time evolution of structure factors (SF) in the disordering process of an initially phase-separated lattice depends crucially on the microscopic disordering mechanism, such as Kawasaki dynamics (KD) or vacancy-mediated disordering (VMD). Monte Carlo simulations show unexpected “dips” in the SFs. A phenomenological model is introduced to explain the dips in the odd SFs, and an analytical solution of KD is derived, in excellent agreement with simulations. The presence (absence) of dips in the even SFs for VMD (KD) marks a significant but not yet understood difference of the two dynamics.

X‐Ray–Emitting Groups In The Infall Region Of Abell 2199, K. Rines, A. Mahdavi, M. J. Geller, A. Diaferio, J. J. Mohr, G. Wegner

Dartmouth Scholarship

Using a large redshift survey covering 95 deg2, we demonstrate that the infall region of Abell 2199 contains Abell 2197, one or two X-ray-emitting groups, and up to five additional groups identified in redshift surveys. Our survey shows that the X-ray-emitting systems, located at projected radii of 14, 19, and 51 (2.2, 3.1, and 8.0 h-1 Mpc), are connected kinematically to A2199. A2197 is itself an optically rich cluster; its weak X-ray emission suggests that it is much less massive than A2199. The absence of a sharp peak in the infall pattern at the position of A2197 supports this …

Stellar Pollution In The Solar Neighborhood, N. Murray, B. Chaboyer, P. Arras, B. Hansen, R. W. Noyes

Dartmouth Scholarship

We study spectroscopically determined iron abundances of 640 solar-type stars to search for the signature of accreted iron-rich material. We find that the metallicity [Fe/H] of a subset of 466 main-sequence stars, when plotted as a function of stellar mass, mimics the pattern seen in lithium abundances in open clusters. Using Monte Carlo models, we find that, on average, these stars appear to have accreted ~0.5 M⊕ of iron while on the main-sequence. A consistency check is provided by a much smaller sample of 19 stars in the Hertzsprung gap, which are slightly evolved and the convection zones of …

Geochemical Variation Among Small Eruptive Centers In The Central Svz Of The Andes : An Evaluation Of Subduction, Mantle And Crustal Influences, Murong Sun

FIU Electronic Theses and Dissertations

Subduction zone magmatism is an important and extensively studied topic in igneous geochemistry. Recent studies focus on from where arc magmas are generated, how subduction components (fluids or melts) are fluxed into the source of the magmas, and whether or how the subduction components affect partial melting processes beneath volcanic arcs at convergent boundaries.

At 39.5°S in the Central Southern Volcanic Zone of the Andes, Volcano Villarrica is surrounded by a suite of Small Eruptive Centers (SEC). The SECs are located mostly to the east and northeast of the stratovolcano and aligned along the Liquine - Ofqui Fault …

Late Quaternary Climate And Hydrology Of Tropical South America Inferred From An Isotopic And Chemical Model Of Lake Titicaca, Bolivia And Peru, Scott L. Cross, Paul A. Baker, Geoffrey O. Seltzer, Sherilyn C. Fritz, Robert B. Dunbar

Department of Earth and Atmospheric Sciences: Faculty Publications

A simple mass balance model provides insight into the hydrologic, isotopic, and chemical responses of Lake Titicaca to past climatic changes. Latest Pleistocene climate of the Altiplano is assumed to have been 20% wetter and 5°C colder than today, based on previous modeling. Our simulation of lacustrine change since 15,000 cal yr B.P. is forced by these modeled climate changes. The latest Pleistocene Lake Titicaca was deep, fresh, and overflowing. The latest Pleistocene riverine discharge from the lake was about 8 times greater than the modern average, sufficient to allow the expansion of the great paleolake Tauca on the central …

A Theory Of Global Climate Change On Millennial Time Scales, Kirk A. Maasch

University of Maine Office of Research Administration: Grant Reports

A Theory of Global Climate Change on Millennial Time Scales In the northern hemisphere, large and rapid shifts in environmental conditions have occurred repeatedly over the last glacial- interglacial cycle. Indications are that climate change occurs on two characteristic time scales, roughly 1 - 3,000 years and 5 - 10,000 years. Evidence for millennial-scale climate variability has been found in ice cores drilled through the Greenland ice sheet, sediment cores from the North Atlantic Ocean, pollen records from both North America and Europe, and glacial deposits in North America. Paleoclimate records from the southern hemisphere also show climatic variability on …

Student Survey Of Information Technology, Wku Information Technology, Richard Kirchmeyer

Board of Regents Documents

Survey of 400 WKU students about information technology used in strategic operations planning for Information Technology. The survey attempted to determine the depth and breadth of student computer use and knowledge of a variety of hardware and software. The report was presented to the WKU Board of Regents at the August 17, 2001 meeting.

Cyp83b1 Is The Oxime-Metabolizing Enzyme In The Glucosinolate Pathway In Arabidopsis, Carsten Horslev Hansen, Liangcheng Du, Peter Naur, Carl Erik Olsen, Kristian B. Axelsen, Alastair J. Hick, John A. Pickett, Barbara Ann Halkier

Liangcheng Du Publications

CYP83B1 from Arabidopsis thaliana has been identified as the oxime-metabolizing enzyme in the biosynthetic pathway of glucosinolates. Biosynthetically active microsomes isolated from Sinapis alba converted p-hydroxyphenylacetaldoxime and cysteine into S-alkylated p-hydroxyphenylacetothiohydroximate, S-(p-hydroxyphenylacetohydroximoyl)-L-cysteine, the next proposed intermediate in the glucosinolate pathway. The production was shown to be dependent on a cytochrome P450 monooxygenase. We searched the genome of A. thaliana for homologues of CYP71E1 (P450ox), the only known oxime-metabolizing enzyme in the biosynthetic pathway of the evolutionarily related cyanogenic glucosides. By a combined use of bioinformatics, published expression data, and knock-out phenotypes, we identified the …

High-PT Jets In Pp̅ Collisions At √S =630 And 1800 Gev, B. Abbott, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

Results are presented from analyses of jet data produced in pp̅ collisions at √s =630 and 1800 GeV collected with the DØ detector during the 1994–1995 Fermilab Tevatron Collider run. We discuss the details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at √s = 630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at√s =630 and 1800 GeV are compared to next-to-leading order QCD predictions. The order α_s³ calculations are in …

Contributions From Mafic Alkaline Magmas To The Bingham Porphyry Cu-Au-Mo Deposit, Utah, U.S.A., Daniel T. Maughan

Theses and Dissertations

The Bingham porphyry Cu-Au-Mo deposit, Utah, may only be world-class because of substantial contributions of sulfur and metals from mafic alkaline magma to an otherwise unremarkable calc-alkaline system. Volcanic mafic alkaline rocks in the district are enriched in Cr, Ni, and Ba as well as ore-related constituents of Cu, Au, platinum group elements (PGE) and S. The bulk of the volcanic section that is comagmatic with ore-related porphyries is dacitic to trachytic in composition, but has inherited the geochemical signature of high Cr, Ni, and Ba from magma mixing with the mafic alkaline rocks. The volcanic section that most closely …

Shortcuts In The Fifth Dimension, Robert Caldwell, David Langlois

Dartmouth Scholarship

If our Universe is a three-brane embedded in a five-dimensional anti-de Sitter spacetime, in which matter is confined to the brane and gravity inhabits an infinite bulk space, then the causal propagation of luminous and gravitational signals is in general different. A gravitational signal traveling between two points on the brane can take a “shortcut” through the bulk, and appear quicker than a photon traveling between the same two points along a geodesic on the brane. Similarly, in a given time interval, a gravitational signal can propagate farther than a luminous signal. We quantify this effect, and analyze the impact …

Magnetic States Of Granular Layered Cofe-Al2O3, J.B. Sousa, G.N. Kakazei, Y.G. Pogorelov, J.A.M. Santos, O. Petracic, Wolfgang Kleemann, Christian Binek, Susana Cardoso De Freitas, P.P. Freitas, M.M. Pereira De Azevedo, N.A. Lesnik, Stanislav Rokhlin, P.E. Wigen

Christian Binek Publications

The granular layered magnetic system Co₈₀Fe₂₀(t)/Al₂ O₃ (3 nm), where the Co₈₀Fe₂₀ layers of nominal thickness t form separate, almost spherical magnetic granules of typical diameter 2-3 nm between the Al₂O₃ spacers, was studied. We discuss measurements of the dc and ac magnetic susceptibility χ for 1 nm

Dynamics Of Symmetry Breaking And Tachyonic Preheating, Gary Felder, Juan García-Bellido, Patrick B. Greene, Lev Kofman, Andrei Linde, Igor Tkachev

Physics: Faculty Publications

We reconsider the old problem of the dynamics of spontaneous symmetry breaking (SSB) using 3D lattice simulations. We develop a theory of tachyonic preheating, which occurs due to the spinodal instability of the scalar field. Tachyonic preheating is so efficient that SSB typically completes within a single oscillation as the field rolls towards the minimum of its effective potential. We show that, contrary to previous expectations, preheating in hybrid inflation is typically tachyonic. Our results may also be relevant for the theory of the formation of topological defects and of disoriented chiral condensates in heavy ion collisions.

Nature Of Oxygen At Rocksalt And Spinel Oxide Surfaces, Marjorie Langell, J.G. Kim, D. L. Pugmire, W. Mccarroll

Marjorie A. Langell Publications

The chemical environment of oxygen in cobalt-containing metal oxides with compositions M _xM′_{( x – 1)} O and M _xM′_{(3x – 1)} O₄ (M,M′ = Mn,Ni,Co) has been studied by Auger, x-ray and ultraviolet photoelectron, and high resolution electron energy loss spectroscopies. While there is a single type of lattice oxygen in the bulk structure of simple rocksalt and spinel oxides, the nature of oxygen at the surface of the spinel oxides is considerably more complex. Photoemission from core oxygen states in these materials often shows multiple peaks and satellite structure which have been …

The Virginia Wetlands Report Vol. 16, No. 2, Virginia Institute Of Marine Science

Virginia Wetlands Reports

• Northern Water Snake. William L. Roberts
• Book Review Discovering the Unknown Landscape: A History of America’s Wetlands. Tom Barnard
• Shoreline Situation Report Update. Marcia Berman
• A Summary of the EPA Rapid Bioassessment of Wetland Health Workshop.Rebecca Jo Thomas
• Through The Years in Virginia’s Wetlands: The 1970’s. Gene M. Silberhorn
• Atlantic White Cedar. Pam Mason

Announcements: Summer/Fall 2001

Drought Network News (1994-2001)

Contents:

Allocating and Managing Water for a Sustainable Future: Lessons from Around the World

Defending the Integrity of Ground Water: Understanding the Impacts of Natural and Manmade Disasters

Conference on Energy Climate, Environment and Water—Issues and Opportunities for Irrigation and Drainage

Determination Of Surface Heterogeneity And Enthalpies Of Ca-K And Pb-K Systems In Tropical Soil Using Flow Adsorption Calorimetry, Chip Appel, Lena Ma, Dean Rhue, Bill Reve

Earth and Soil Sciences

No abstract provided.

Precise Environmental Searches: Integrating Hierarchical Information Search With Envirodaemon, George Chang, Gunjan Samtani, Marcus Healey, Franz J. Kurfess, Jason Wang

Computer Science and Software Engineering

Information retrieval has evolved from searches of references, to abstracts, to documents. Search on the Web involves search engines that promise to parse full-text and other files: audio, video, and multimedia. With the indexable Web at 320 million pages and growing, difficulties with locating relevant information have become apparent. The most prevalent means for information retrieval relies on syntax-based methods: keywords or strings of characters are presented to a search engine, and it returns all the matches in the available documents. This method is satisfactory and easy to implement, but it has some inherent limitations that make it unsuitable for …

Even Kakutani Equivalence And The Loose Block Independence Property For Positive Entropy Zᵈ Actions, Aimee S. A. Johnson, A. A. Şahin

Mathematics & Statistics Faculty Works

In this paper we define the loose block independence property for positive entropy Zᵈ actions and extend some of the classical results to higher dimensions. In particular, we prove that two loose block independent actions are even Kakutani equivalent if and only if they have the same entropy. We also prove that for d > 1 the ergodic, isometric extensions of the positive entropy loose block independent Zᵈ actions are also loose block independent.

Constructing Critical Indecomposable Codes, Judy L. Walker

Department of Mathematics: Faculty Publications

Critical indecomposable codes were introduced by Assmus, who also gave a recursive construction for these objects. One of the key ingredients in the construction is an auxiliary code, which is an indecomposable code of minimum distance at least 3. In terms of actually being able to construct all critical indecomposable codes, however, Assmus leaves many unanswered questions about these auxiliary codes. In this paper, we provide answers to these questions, including a description of when two equivalent auxiliary codes can yield inequivalent critical indecomposable codes, and results on both the minimum length and the maximum number of critical columns of …

Circulation, Vol. 8, No. 2, Center For Coastal Physical Oceanography, Old Dominion University, Larry P. Atkinson

CCPO Circulation

Summer 2001 issue of CCPO Circulation featuring article "Oceanographic Research in the Antarctic" by Larry Atkinson

The Power Of Two Random Choices: A Survey Of Techniques And Results, Michael Mitzenmacher, Andrea Richa, Ramesh Sitaraman

Ramesh Sitaraman

No abstract provided.