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Articles 210781 - 210810 of 295129

Full-Text Articles in Physical Sciences and Mathematics

Corrigendum To ‘‘Distribution And Environmental Limitations Of An Amphibian Pathogen In The Rocky Mountains, Usa’’ [Biological Conservation 141 (2008) 1484–1492], Erin Muths, David S. Pilliod, Lauren J. Livo Jan 2008

Corrigendum To ‘‘Distribution And Environmental Limitations Of An Amphibian Pathogen In The Rocky Mountains, Usa’’ [Biological Conservation 141 (2008) 1484–1492], Erin Muths, David S. Pilliod, Lauren J. Livo

United States Geological Survey: Staff Publications

The author regrets that in the above published paper the following error occurred:
In our recently published paper, ‘‘Distribution and environmental limitations of an amphibian pathogen in the Rocky Mountains, USA’’, we erroneously included the paper by J. Bosch et al. (2006), ‘‘Climate change and outbreaks of amphibian chytridiomycosis in a montane area of Central Spain: is there a link?’’ in a list of studies from the tropics. Clearly Dr. Bosch and colleagues worked in the temperate zone at a latitude very similar to that in our study suggesting that further investigation of additional similarities between the two sites might …

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Paleoclimatic Significance Of Chemical Weathering In Loess-Derived Paleosols Of Subarctic Central Alaska, Daniel R. Muhs, Thomas A. Ager, Gary Skipp, Jossh Beann, James Budahn, John P. Mcgeehin Jan 2008

Paleoclimatic Significance Of Chemical Weathering In Loess-Derived Paleosols Of Subarctic Central Alaska, Daniel R. Muhs, Thomas A. Ager, Gary Skipp, Jossh Beann, James Budahn, John P. Mcgeehin

United States Geological Survey: Staff Publications

Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid- Wisconsin interstadials. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most …

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Apparent Tolerance Of Turkey Vultures (Cathartes Aura) To The Non-Steroidal Anti-Inflammatory Drug Diclofenac, Barnett A. Rattner, Maria A. Whitehead, Grace Gasper, Carol U. Meteyer, William A. Link, Mark A. Taggart, Andrew A. Meharg, Oliver H. Pattee, Deborah J. Pain Jan 2008

Apparent Tolerance Of Turkey Vultures (Cathartes Aura) To The Non-Steroidal Anti-Inflammatory Drug Diclofenac, Barnett A. Rattner, Maria A. Whitehead, Grace Gasper, Carol U. Meteyer, William A. Link, Mark A. Taggart, Andrew A. Meharg, Oliver H. Pattee, Deborah J. Pain

United States Geological Survey: Staff Publications

The nonsteroidal anti-inflammatory drug diclofenac is extremely toxic to Old World Gyps vultures (median lethal dose ~0.1–0.2 mg/kg), evoking visceral gout, renal necrosis, and mortality within a few days of exposure. Unintentional secondary poisoning of vultures that fed upon carcasses of diclofenac-treated livestock decimated populations in the Indian subcontinent. Because of the widespread use of diclofenac and other cyclooxygenase-2 inhibiting drugs, a toxicological study was undertaken in turkey vultures (Cathartes aura) as an initial step in examining sensitivity of New World scavenging birds. Two trials were conducted entailing oral gavage of diclofenac at doses ranging from 0.08 to …

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Grenetic Evidence Of Intercontinental Movement Of Avian Influenza In A Migratory Bird: The Northern Pintail (Anas Acuta), Anson V. Koehler, John M. Pearce, Paul L. Flint, J. Christian Franson, Hon S. Ip Jan 2008

Grenetic Evidence Of Intercontinental Movement Of Avian Influenza In A Migratory Bird: The Northern Pintail (Anas Acuta), Anson V. Koehler, John M. Pearce, Paul L. Flint, J. Christian Franson, Hon S. Ip

United States Geological Survey: Staff Publications

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses …

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Tools And Technology Article: Evaluation Of An Aerial Survey To Estimate Abundance Of Wintering Ducks In Mississippi, Aaron T. Pearse, Stephen J. Dinsmore, Richard M. Kaminski, Kenneth J. Reinecke Jan 2008

Tools And Technology Article: Evaluation Of An Aerial Survey To Estimate Abundance Of Wintering Ducks In Mississippi, Aaron T. Pearse, Stephen J. Dinsmore, Richard M. Kaminski, Kenneth J. Reinecke

United States Geological Survey: Staff Publications

Researchers have successfully designed aerial surveys that provided precise estimates of wintering populations of ducks over large physiographic regions, yet few conservation agencies have adopted these probability-based sampling designs for their surveys. We designed and evaluated an aerial survey to estimate abundance of wintering mallards (Anas platyrhynchos), dabbling ducks (tribe Anatini) other than mallards, diving ducks (tribes Aythini, Mergini, and Oxyurini), and total ducks in western Mississippi, USA. We used design-based sampling of fixed width transects to estimate population indices (/), and we used model-based methods to correct population indices for visibility bias and estimate population abundance (N) for 14 …

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Tools And Technology Article: Estimation And Correction Of Visibility Bias In Aerial Surveys Of Wintering Ducks, Aaron T. Pearse, Patrick D. Gerard, Stephen J. Dinsmore, Richard M. Kaminski, Kenneth J. Reinecke Jan 2008

Tools And Technology Article: Estimation And Correction Of Visibility Bias In Aerial Surveys Of Wintering Ducks, Aaron T. Pearse, Patrick D. Gerard, Stephen J. Dinsmore, Richard M. Kaminski, Kenneth J. Reinecke

United States Geological Survey: Staff Publications

Incomplete detection of all individuals leading to negative bias in abundance estimates is a pervasive source of error in aerial surveys of wildlife, and correcting that bias is a critical step in improving surveys. We conducted experiments using duck decoys as surrogates for live ducks to estimate bias associated with surveys of wintering ducks in Mississippi, USA. We found detection of decoy groups was related to wedand cover type (open vs. forested), group size (1-100 decoys), and interaction of these variables. Observers who detected decoy groups reported counts that averaged 78% of the decoys actually present, and this counting bias …

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Relations Between And Among Contaminant Concentrations And Biomarkers In Black Bass (Micropterus Spp.) And Common Carp (Cyprinus Carpio) From Large U.S. Rivers, 1995–2004, Jo Ellen Hinck, Christopher J. Schmitt, Mark R. Ellersieck, Donald E. Tillitt Jan 2008

Relations Between And Among Contaminant Concentrations And Biomarkers In Black Bass (Micropterus Spp.) And Common Carp (Cyprinus Carpio) From Large U.S. Rivers, 1995–2004, Jo Ellen Hinck, Christopher J. Schmitt, Mark R. Ellersieck, Donald E. Tillitt

United States Geological Survey: Staff Publications

Environmental contaminant and biomarker monitoring data from major U.S. river basins were summarized for black bass (Micropterus spp.) and common carp (Cyprinus carpio) sampled over a nine year period. Cumulative frequency distributions revealed taxon differences for many organochlorine residue concentrations, elemental contaminant concentrations, and biomarkers, but few gender differences were evident for chemical concentrations. Concentrations of dacthal, pentachloroanisole, p,p'-DDE, endosulfan sulfate, barium, cadmium, copper, manganese, lead, selenium, vanadium, and zinc were greater in carp than bass, but concentrations of mercury and magnesium were greater in bass. Gender differences were evident in bass for mercury and in carp …

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The Automation Of Software Development Metrics, Anthony J. Traino Jan 2008

The Automation Of Software Development Metrics, Anthony J. Traino

Regis University Student Publications (comprehensive collection)

With the push to streamline medical records and the use of electronic medical records system technology on the rise, successful implementation is important. The push is due in part for the need to reduce unnecessary paperwork, increase reimbursement, increase quality of medical records and increase overall quality of care. Factors to consider are the effects of implementation on quality of care, quality of medical records, physician and staff perceptions, working conditions, patient satisfaction, cost and barriers. Implementation may have a positive, negative or neutral effect on these factors making the need to review literature and report outcomes significant.

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Classification Of Non-Heat Generating Outdoor Objects In Thermal Scenes For Autonomous Robots, William L. Fehlman Jan 2008

Classification Of Non-Heat Generating Outdoor Objects In Thermal Scenes For Autonomous Robots, William L. Fehlman

Dissertations, Theses, and Masters Projects

We have designed and implemented a physics-based adaptive Bayesian pattern classification model that uses a passive thermal infrared imaging system to automatically characterize non-heat generating objects in unstructured outdoor environments for mobile robots. In the context of this research, non-heat generating objects are defined as objects that are not a source for their own emission of thermal energy, and so exclude people, animals, vehicles, etc. The resulting classification model complements an autonomous bot's situational awareness by providing the ability to classify smaller structures commonly found in the immediate operational environment. Since GPS depends on the availability of satellites and onboard …

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Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating Jan 2008

Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating

Dissertations, Theses, and Masters Projects

The Lattice Boltzmann Method (LBM) is a simple and highly efficient method for computing nearly incompressible fluid flow. However, it is well known to suffer from numerical instabilities for low values of the transport coefficients. This dissertation examines a number of methods for increasing the stability of the LBM over a wide range of parameters. First, we consider a simple transformation that renders the standard LB equation implicit. It is found that the stability is largely unchanged. Next, we consider a stabilization method based on introducing a Lyapunov function which is essentially a discrete-time H-function. The uniqueness of an H-function …

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Formal Analysis Of Firewall Policies, Robert Mathias Marmorstein Jan 2008

Formal Analysis Of Firewall Policies, Robert Mathias Marmorstein

Dissertations, Theses, and Masters Projects

This dissertation describes a technique for formally analyzing a firewall security policy using a quasi-reduced multiway decision diagram model. The analysis allows a system administrator to detect and repair errors in the configuration of the firewall without a tedious manual inspection of the firewall rules.;We present four major contributions. First, we describe a set of algorithms for representing a firewall rule set as a multi-way decision diagram and for solving logical queries against that model. We demonstrate the application of these techniques in a tool for analyzing iptables firewalls. Second, we present an extension of our work that enables analysis …

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As Particles Collide: Extra Dimensions And Heavy Leptons, Erin Kathleen De Pree Jan 2008

As Particles Collide: Extra Dimensions And Heavy Leptons, Erin Kathleen De Pree

Dissertations, Theses, and Masters Projects

Despite excellent agreement with experiment, the Standard Model leaves several issues unresolved. These issues will be explored and several extensions to the Standard Model introduced: models with extra dimensions and a fourth family of particles.;In extra dimensional models, there are Fourier modes of the Standard Model particles. We study the detection of bound states of one of the modes and its Standard Model particle.;We then explore a particular model of extra dimensions known as Randall-Sundrum or warped extra dimensions. We will see how this model affects top quark measurements at the proposed International Linear Collider.;Finally we will study the detection …

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The Semiclassical Description Of The Energy Spectrum Of Hydrogen In Near-Perpendicular Fields, Christopher Robert Schleif Jan 2008

The Semiclassical Description Of The Energy Spectrum Of Hydrogen In Near-Perpendicular Fields, Christopher Robert Schleif

Dissertations, Theses, and Masters Projects

We examine the energy spectrum of hydrogen in weak near-perpendicular electric and magnetic fields using quantum computations and semiclassical analysis. The structure of the quantum spectrum is displayed in a lattice constructed by plotting the difference between total energy and first order energy versus first order energy, for all states of a given principal quantum number n. For some field parameters, the lattice structure is not regular, but has a lattice defect structure which may be characterized by the transport of lattice vectors. We find that in near-perpendicular fields the structure of the spectrum is divided into six distinct parameter …

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Measurement Of Inclusive Proton Double -Spin Asymmetries And Polarized Structure Functions, Robert G. Fersch Jan 2008

Measurement Of Inclusive Proton Double -Spin Asymmetries And Polarized Structure Functions, Robert G. Fersch

Dissertations, Theses, and Masters Projects

The scattering of polarized electrons from a polarized proton target provides a means for studying the internal spin structure of the proton. The CLAS (CEBAF Large Acceptance Spectrometer) EG1b experiment in Hall-B at Jefferson Laboratory measured double-spin inclusive and exclusive electron-nucleon scattering asymmetries using longitudinally polarized frozen NH3 and ND3 targets and a longitudinally polarized electron beam at 4 different energies (1.6, 2.5, 4.2, 5.6 GeV). Extraction of the virtual photon asymmetry Ap1 (for 0.05 GeV2 < Q2 < 5.0 GeV2) provides precision measurements of the polarized proton spin-structure function gp1 in and above the resonance region. Linear regression of data between the varying energies yields new constraints on the virtual photon asymmetry Ap2 (and thus the structure function gp2 ) in the resonance region (for 0.3 GeV2 < Q2 < 1.0 GeV2). Measurements of these structure functions and their moments allows testing of perturbative Quantum Chromodynamics (pQCD) models and evaluation of moments of the structure functions in the Operator Product Expansion. Testing of Chiral Perturbation Theory (chiPT) at Q2 < 0.2 GeV 2 is enabled by the new data. Other applications of polarized structure functions include measurement of foward-spin polarizability, evaluation of high-order corrections in 1H hyperfine splitting, and testing of quark-hadron duality.

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Downflow Limestone Beds For Treatment Of Net-Acidic, Oxic, Iron-Laden Drainage From A Flooded Anthracite Mine, Pennsylvania, Usa: 2. Laboratory Evaluation, Charles A. Cravotta Iii, Suzanne J. Ward, Jane M. Hammarstrom Jan 2008

Downflow Limestone Beds For Treatment Of Net-Acidic, Oxic, Iron-Laden Drainage From A Flooded Anthracite Mine, Pennsylvania, Usa: 2. Laboratory Evaluation, Charles A. Cravotta Iii, Suzanne J. Ward, Jane M. Hammarstrom

United States Geological Survey: Staff Publications

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO3 and MgCO3 contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO3 and MgCO3 contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to …

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Developing Conceptual Hydrogeological Model For Potsdam Sandstones In Southwestern Quebec, Canada, M. Nastev, Roger H. Morin, R. Godin, A. Rouleau Jan 2008

Developing Conceptual Hydrogeological Model For Potsdam Sandstones In Southwestern Quebec, Canada, M. Nastev, Roger H. Morin, R. Godin, A. Rouleau

United States Geological Survey: Staff Publications

A hydrogeological study was conducted in Potsdam sandstones on the international border between Canada (Quebec) and the USA (New York). Two sandstone formations, arkose and conglomerate (base) and well-cemented quartz arenite (upper), underlie the study area and form the major regional aquifer unit. Glacial till, littoral sand and gravel, and marine silt and clay discontinuously overlie the aquifer. In both sandstone formations, sub-horizontal bedding planes are ubiquitous and display significant hydraulic conductivities that are orders of magnitude more permeable than the intact rock matrix. Aquifer tests demonstrate that the two formations have similar bulk hydrologic properties, with average hydraulic conductivities …

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Metals Fate And Transport Modelling In Streams And Watersheds: State Of The Science And Usepa Workshop Review, B. S. Caruso, T. J. Cox, R. L. Runkel, M. L. Velleux, K. E. Bencala, D. K. Nordstrom, P. Y. Julien, B. A. Butler, Charles N. Alpers, A. Marion, K. S. Smith Jan 2008

Metals Fate And Transport Modelling In Streams And Watersheds: State Of The Science And Usepa Workshop Review, B. S. Caruso, T. J. Cox, R. L. Runkel, M. L. Velleux, K. E. Bencala, D. K. Nordstrom, P. Y. Julien, B. A. Butler, Charles N. Alpers, A. Marion, K. S. Smith

United States Geological Survey: Staff Publications

Metals pollution in surface waters from point and non-point sources (NPS) is a widespread problem in the United States and worldwide (Lofts et al., 2007; USEPA, 2007). In the western United States, metals associated with acid mine drainage (AMD) from hardrock mines in mountainous areas impact aquatic ecosystems and human health (USEPA, 1997a; Caruso and Ward, 1998; Church et al., 2007). Metals fate and transport modelling in streams and watersheds is sometimes needed for assessment and restoration of surface waters, including mining-impacted streams (Runkel and Kimball, 2002; Caruso, 2003; Velleux et al., 2006). The Water Quality Analysis …

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Lead Concentration Of Soils In Sorby Hills Area Of Proposed M2 Irrigation Area, East Kimberley, Edward (Ted) Arnold Griffin, Noel R. Schoknecht, Ross Brennan, Jane Speijers, Dave Allen, Mike Freeman Jan 2008

Lead Concentration Of Soils In Sorby Hills Area Of Proposed M2 Irrigation Area, East Kimberley, Edward (Ted) Arnold Griffin, Noel R. Schoknecht, Ross Brennan, Jane Speijers, Dave Allen, Mike Freeman

Resource management technical reports

No abstract provided.

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Setting Targets For Resource Condition In Narrakine Gully And Highbury Catchments, Leon Van Wyk, Gregory Paul Raper Jan 2008

Setting Targets For Resource Condition In Narrakine Gully And Highbury Catchments, Leon Van Wyk, Gregory Paul Raper

Resource management technical reports

No abstract provided.

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Introgression And Dispersal Among Spotted Owl (Strix Occidentalis) Subspecies, W. Chris Funk, Eric D. Forsman, Thomas D. Mullins, Susan M. Haig Jan 2008

Introgression And Dispersal Among Spotted Owl (Strix Occidentalis) Subspecies, W. Chris Funk, Eric D. Forsman, Thomas D. Mullins, Susan M. Haig

United States Geological Survey: Staff Publications

Population genetics plays an increasingly important role in the conservation and management of declining species, particularly for defining taxonomic units. Subspecies are recognized by several conservation organizations and countries and receive legal protection under the US Endangered Species Act (ESA). Two subspecies of spotted owls, northern (Strix occidentalis caurina) and Mexican (S. o. lucida) spotted owls, are ESA-listed as threatened, but the California (S. o. occidentalis) spotted owl is not listed. Thus, determining the boundaries of these subspecies is critical for effective enforcement of the ESA. We tested the validity of previously recognized spotted …

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The Origin Of Molecular Hydrogen Emission In Cooling-Flow Filaments, Gary J. Ferland, A. C. Fabian, N. A. Hatch, R. M. Johnstone, R. L. Porter, P. A. M. Vanhoof, R. J. R. Williams Jan 2008

The Origin Of Molecular Hydrogen Emission In Cooling-Flow Filaments, Gary J. Ferland, A. C. Fabian, N. A. Hatch, R. M. Johnstone, R. L. Porter, P. A. M. Vanhoof, R. J. R. Williams

Physics and Astronomy Faculty Publications

The optical filaments found in many cooling flows in galaxy clusters consist of low-density (∼103 cm−3) cool (∼103 K) gas surrounded by significant amounts of cosmic-ray and magnetic field energy. Their spectra show anomalously strong low-ionization and molecular emission lines when compared with Galactic molecular clouds exposed to ionizing radiation such as the Orion complex. Previous studies have shown that the spectra cannot be produced by O-star photoionization. Here, we calculate the physical conditions in dusty gas that is well shielded from external sources of ionizing photons and is energized either by cosmic rays or dissipative …

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Assessment Of Water Quality Trends In The North Fork Of Kentucky River Basin: Focus On Pathogen Impairment, Kentucky Water Resources Research Institute Jan 2008

Assessment Of Water Quality Trends In The North Fork Of Kentucky River Basin: Focus On Pathogen Impairment, Kentucky Water Resources Research Institute

KWRRI Research Reports

This project consisted of analyzing existing water quality data for streams in the Upper Forks of Kentucky River Basin, with a particular focus on pathogen trends. According to the most recent 303(d) list of Kentucky waters, the majority of streams assessed in the Upper Forks of Kentucky River Basin are impaired for primary recreational contact as a result of pathogens. The state pathogen standard for primary contact recreation is expressed in a dual form which specifies that the 30-day geometric mean of fecal coliform counts not exceed 200 colonies per 100 mL (on a minimum of five samples) and not …

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Kentucky Water Resources Research Institute Annual Technical Report Fy 2007, Kentucky Water Resources Research Institute, University Of Kentucky Jan 2008

Kentucky Water Resources Research Institute Annual Technical Report Fy 2007, Kentucky Water Resources Research Institute, University Of Kentucky

KWRRI Annual Technical Reports (USGS’s 104b Grant Program)

The 2007 Annual Technical Report for Kentucky consolidates reporting requirements of the Section 104(b) base grant award into a single document that includes: 1) a synopsis of each student research enhancement project conducted during the period, 2) citations for related publications, reports, and presentations, 3) a description of information transfer activities, 4) a summary of student support during the reporting period, and 5) notable awards and achievements during the year.

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Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille Jan 2008

Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille

All Master's Theses

Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …

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Fourier-Transform Microwave Spectroscopy Of Cyclopropylmethylgermane And Van Der Waals Complexes Of Fluorinated Methanes, Michal M. Serafin Jan 2008

Fourier-Transform Microwave Spectroscopy Of Cyclopropylmethylgermane And Van Der Waals Complexes Of Fluorinated Methanes, Michal M. Serafin

Masters Theses

No abstract provided.

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Synthetic Studies Towards The Stellettins, Tung Yin Lin Jan 2008

Synthetic Studies Towards The Stellettins, Tung Yin Lin

Masters Theses

No abstract provided.

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Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu Jan 2008

Synthesis And Surface Characterization Of Silica-Polypeptide Composite Particles, Erick Isael Soto-Cantu

LSU Doctoral Dissertations

The synthesis and sequential surface characterization of silica-polypeptide composite particles is described. Nearly monodisperse colloidal silica cores were obtained by the alkaline hydrolysis of tetraethyl orthosilicate (TEOS). The hydrodynamic radius can be easily controlled in the range of ƒî 20-140 nm by the water/TEOS ratio in the starting reaction mixture. The surface of the synthesized silica cores was further passivated/functionalized (P/F) by a mixture of (3-aminopropyl) trimethoxysilane (APS) and methyl-trimethoxysilane (MTMS). The amino groups were quantified using UV-Vis spectrometry after reaction with ninhydrin. The use of zeta potential measurements of the P/F silica particles at low pH is presented as …

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Fast Marching Methods - Parallel Implementation And Analysis, Maria Cristina Tugurlan Jan 2008

Fast Marching Methods - Parallel Implementation And Analysis, Maria Cristina Tugurlan

LSU Doctoral Dissertations

Fast Marching represents a very efficient technique for solving front propagation problems, which can be formulated as partial differential equations with Dirichlet boundary conditions, called Eikonal equation: $F(x)|\nabla T(x)|=1$, for $x \in \Omega$ and $T(x)=0$ for $x \in \Gamma$, where $\Omega$ is a domain in $\mathbb{R}^n$, $\Gamma$ is the initial position of a curve evolving with normal velocity F>0. Fast Marching Methods are a necessary step in Level Set Methods, which are widely used today in scientific computing. The classical Fast Marching Methods, based on finite differences, are typically sequential. Parallelizing Fast Marching Methods is a step forward for …

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Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne Jan 2008

Incorporation Of Cα,Α-Disubstituted Amino Acids Into Model Peptide Systems: Conformational Analysis And Possible Applications As Therapeutic Agents, Marcus A. Etienne

LSU Doctoral Dissertations

A diverse set of human diseases is associated with the misfolding of proteins into insoluble fibrillar structures that have predominantly β-sheet secondary structure. Thus it is imperative to elucidate the structural elements that contribute to β-sheet formation and stability. Peptides that autonomously form β-sheets are ideal models to study principles of protein folding and design. Gellman and coworkers first introduced an automonously folded β-hairpin (H-Arg-Tyr-Val-Glu-Val-Yyy-Xxx-Orn-Lys-Ile-Leu-Gln-NH2) that remained monomeric up to ~1 mM. Circular dichroism (CD) and nuclear magnetic resonance (NMR) analyses revealed that incorporation of non-stereogenic Aib-Xxx dipeptidyl sequences into i+1 and i+2 positions of a model peptide nucleates a …

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Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer Jan 2008

Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer

LSU Doctoral Dissertations

Investigations of hurricane disturbances on coastal vegetated communities are common, but relatively few are comprehensive across broad geographic regions. The 2005 hurricanes, Katrina and Rita, exposed Louisiana coastal landscapes to physical modifications and extensive and prolonged flooding, resulting in measurable physicochemical changes. This research used remote sensing and field investigations to regionally assess (1) porewater salinity and sulfide impacts to and recovery of coastal Louisiana vegetation communities, and (2) the importance of mineral sediment deposition on accretionary processes. Hurricane effects were most direct and prominent in eastern Louisiana from Katrina and western Louisiana from Rita, compared to central Louisiana exposed …

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