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2009

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Articles 1951 - 1980 of 7616

Full-Text Articles in Physical Sciences and Mathematics

Magmatic Evolution Of The Eocene Volcanic Rocks Of The Bijgerd Kuh E Kharchin Area, Uromieh-Dokhtar Zone, Iran, Armita Davarpanah Jul 2009

Magmatic Evolution Of The Eocene Volcanic Rocks Of The Bijgerd Kuh E Kharchin Area, Uromieh-Dokhtar Zone, Iran, Armita Davarpanah

Geosciences Theses

Composition and texture of the Middle and Late Eocene volcanic, volcaniclastic, and volcanic-sedimentary rocks in the Bijgerd-Kuh e Kharchin area, in the Uromieh-Dokhtar zone northwest of Saveh, Iran, suggest the complexity of the magmatic system that involved multiple eruptions from one or more sources. Hydrated volcanic fragments in hyaloclastic rocks, and the presence of a sequence of shallow and intermediate-depth marine microfossils, suggest that the Middle Eocene units were erupted in a marine basin. The bimodal volcanism of the Late Eocene is distinguished by the presence of four alternating sequences of hyaloclastite lava and ignimbrite. The REE patterns show spatial …

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Advanced Statistical Methodologies In Determining The Observation Time To Discriminate Viruses Using Ftir, Shan Luo Jul 2009

Advanced Statistical Methodologies In Determining The Observation Time To Discriminate Viruses Using Ftir, Shan Luo

Mathematics Theses

Fourier transform infrared (FTIR) spectroscopy, one method of electromagnetic radiation for detecting specific cellular molecular structure, can be used to discriminate different types of cells. The objective is to find the minimum time (choice among 2 hour, 4 hour and 6 hour) to record FTIR readings such that different viruses can be discriminated. A new method is adopted for the datasets. Briefly, inner differences are created as the control group, and Wilcoxon Signed Rank Test is used as the first selecting variable procedure in order to prepare the next stage of discrimination. In the second stage we propose either partial …

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The Effect Of Negative Energy Shells On Schwarzschild Spacetime And Their Penrose Diagrams, Jeffrey Hazboun, Tevian Dray Jul 2009

The Effect Of Negative Energy Shells On Schwarzschild Spacetime And Their Penrose Diagrams, Jeffrey Hazboun, Tevian Dray

Presentations

No abstract provided.

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Spin Polarization Control By Electric Stirring: Proposal For A Spintronic Device, Yuriy V. Pershin Dr, N. A. Sinitsyn, A. Kogan, A. Saxena, D. L. Smith Jul 2009

Spin Polarization Control By Electric Stirring: Proposal For A Spintronic Device, Yuriy V. Pershin Dr, N. A. Sinitsyn, A. Kogan, A. Saxena, D. L. Smith

Faculty Publications

We propose a spintronic device to generate spin polarization in a mesoscopic region by purely electric means. We show that the spin Hall effect in combination with the stirring effect are sufficient to induce measurable spin polarization in a closed geometry. Our device structure does not require the application of magnetic fields, external radiation or ferromagnetic leads, and can be implemented in standard semiconducting materials.

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Geochemical Partitioning Of Copper, Lead And Zinc In Benthic, Estuarine Sediment Profiles, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Geochemical Partitioning Of Copper, Lead And Zinc In Benthic, Estuarine Sediment Profiles, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

Received for publication May 11, 2004. The geochemical partitioning of copper (Cu), lead (Pb), and zinc (Zn) was examined in benthic sediment profiles (0- to 20-cm depth interval) composed of relatively coarse (65–90% sand-sized particles), noncohesive, suboxic material (Eh +120 to +260 mV). Total Cu, Pb, and Zn concentrations ranged from 8.3 to 194, 16.3 to 74.8, and 30.1 to 220 mg/kg, respectively, and were related to vertical trends in sediment texture. The observed distribution coefficients describing solid–solution partitioning were in the range of 100 to 1000 L/kg. The geochemical partitioning of solid-phase Cu, Pb, and Zn between six operationally …

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Iron-Sulfide And Trace Element Behaviour In Sediments Of Coombabah Lake, Moreton Bay (Australia), Edward Burton, Leigh Sullivan, Richard Bush, Bernard Powell Jul 2009

Iron-Sulfide And Trace Element Behaviour In Sediments Of Coombabah Lake, Moreton Bay (Australia), Edward Burton, Leigh Sullivan, Richard Bush, Bernard Powell

Associate Professor Edward D Burton

No abstract provided.

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Sludge-Derived Cu And Zn In A Humic-Gley Soil: Effect Of Dissolved Metal-Organic Matter Complexes On Sorption And Partitioning, Edward Burton, Darryl Hawker, M Redding Jul 2009

Sludge-Derived Cu And Zn In A Humic-Gley Soil: Effect Of Dissolved Metal-Organic Matter Complexes On Sorption And Partitioning, Edward Burton, Darryl Hawker, M Redding

Associate Professor Edward D Burton

A sequential extraction scheme was combined with sorption isotherm analysis in order to investigate sorption of sewage sludge-derived Cu and Zn to the A-horizon of a humic-gley soil as a whole, and to the operationally defined exchangeable (1 M MgCl2), carbonate (1 M NaOAc), Fe/Mn oxide (0.04 M NH2OH.HCl), and organic (0.02 M HNO3+30% H2O2) soil fractions. Sorption parameters were compared for a sample of sludge leachate (with 97.4% of Cu and 63.2% of Zn present as dissolved metal-organic matter complexes, as calculated by geochemical modelling involving MINTEQA2 and verified …

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Reactive Sulphide Relationships With Trace Metal Extractability In Sediments From Southern Moreton Bay, Australia, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Reactive Sulphide Relationships With Trace Metal Extractability In Sediments From Southern Moreton Bay, Australia, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

No abstract provided.

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Factors Controlling The Geochemical Partitioning Of Trace Metals In Estuarine Sediments, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Factors Controlling The Geochemical Partitioning Of Trace Metals In Estuarine Sediments, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

The geochemical partitioning of trace metals in sediments is of great importance in risk assessment and remedial investigation. Selected factors that may control the partitioning behavior of Cu, Pb and Zn in non-sulfidic, estuarine sediments were examined with the use of combined sorption curve—sequential extraction analysis. This approach, which has not been previously used to examine estuarine sediments, allowed determination of sorption parameters for Cu, Pb and Zn partitioning to individual geochemical fractions. Partitioning behavior in sulfidic sediments was also determined by sequentially extracting Cu, Pb, and Zn from synthetic sulfide minerals and from natural sediment and pure quartz sand …

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Sorption And Desorption Behaviour Of Tributyltin With Natural Sediments, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Sorption And Desorption Behaviour Of Tributyltin With Natural Sediments, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

Tributyltin (TBT) sorption to four natural sediment samples in artificial seawater was examined under a range of modified pH and salinity conditions. Three of the sediment samples were relatively pristine with regard to TBT contamination, but the fourth was a TBT-contaminated sediment from a commercial marina. Sorption of TBT was described well by linear sorption isotherms, with distribution coefficients ranging from 6.1 to 5210 L/kg depending on the pH and salinity. The sediment organic C content and particle size distribution were important determinants of sorption behavior. The presence of resident TBT in the contaminated marina sediment caused a substantial reduction …

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Tributyltin Partitioning In Sediments: Effect Of Aging, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Tributyltin Partitioning In Sediments: Effect Of Aging, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

The effect of aging on the solid/pore-water partitioning and desorption behaviour of tributyltin (TBT) in sediments was examined. Three sediment samples with contrasting physical and chemical properties were spiked with 10 mg/kg TBT and aged under sterile conditions for periods of time ranging from 1 to 84 days. Aging had a negligible effect on partitioning and desorption behaviour in a sandy sample with very low organic carbon content (0.2% w/w). In contrast, for samples with larger amounts of organic carbon (2.6% and 4.8% w/w), aging caused substantial increases in TBT sorption. For these samples, apparent distribution coefficients (KD,app) obtained from …

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Fractionation And Extractability Of Sulfur, Iron And Trace Elements In Sulfidic Sediments, Edward Burton, Richard Bush, Leigh Sullivan Jul 2009

Fractionation And Extractability Of Sulfur, Iron And Trace Elements In Sulfidic Sediments, Edward Burton, Richard Bush, Leigh Sullivan

Associate Professor Edward D Burton

This study describes iron and sulfur fractionation, and the related extractability of selected trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in estuarine sediments. The sediments were sulfidic, with moderately high concentrations of pore-water sulfide (200–600 μmol l−1) and acid-volatile sulfide (AVS; 9.9–129 μmol g−1). Pyrite-S concentrations increased with depth, with 63–251 μmol g−1 at site W1 and 312–669 μmol g−1 at site W2. The degree of sulfidisation was generally high (>80%), indicating that Fe may be limiting pyrite accumulation. The ratios of AVS to pyrite-S increased with sediment depth, as expected for the pyritisation of solid-phase …

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Distribution And Enrichment Of Trace Metals In Benthic, Estuarine Sediments: Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Distribution And Enrichment Of Trace Metals In Benthic, Estuarine Sediments: Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

The distribution and enrichment of selected trace metals (Cd, Cr, Cu, Ni, Pb, Sn, Zn) in benthic sediments of the Southport Broadwater, a semi-enclosed coastal body of water adjacent to the Gold Coast city, south-eastern Queensland, Australia, was studied with the objective of assessing the extent and degree of sediment contamination. Sediment samples from the 0–10 cm and 10–20 cm depth intervals of 32 sites within the Southport Broadwater and surrounding residential canals were analysed for particle size distribution, pH, organic C and ‘near-total’ major (Al, Ca, Fe, Mn) and trace (Cd, Cr, Cu, Ni, Pb, Sn, Zn) metal contents. …

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Acid-Volatile Sulfide Oxidation In Coastal Floodplain Drains: Iron-Sulfur Cycling And Effects On Water Quality, Edward Burton, Richard Bush, Leigh Sullivan Jul 2009

Acid-Volatile Sulfide Oxidation In Coastal Floodplain Drains: Iron-Sulfur Cycling And Effects On Water Quality, Edward Burton, Richard Bush, Leigh Sullivan

Associate Professor Edward D Burton

The effect of acid-volatile sulfide (AVS) oxidation on Fe-S cycling and water quality in coastal flood plain drains from acid-sulfate soil landscapes was examined using natural sediments and synthetic iron monosulfide. Oxidation of AVS occurred rapidly (half-time ≤ 1 h) and produced elemental sulfur (S80(s)) and iron oxyhydroxide (FeOOH(s)). The initial rapid AVS oxidation process occurred without significant acidification or changes to the aqueous-phase composition. Severe acidification (pH < 4) occurred only once S80(s) began to oxidize to SO4 (within 2-3 days of the initial AVS oxidation). Our results demonstrate, for the first time with natural sediments, a significant pH-buffered (near-neutral) …

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Sedimentary Iron Geochemistry In Acidic Waterways Associated With Coastal Lowland Acid Sulfate Soils, Edward Burton, Richard Bush, Leigh Sullivan Jul 2009

Sedimentary Iron Geochemistry In Acidic Waterways Associated With Coastal Lowland Acid Sulfate Soils, Edward Burton, Richard Bush, Leigh Sullivan

Associate Professor Edward D Burton

We examined the solubility, mineralogy and geochemical transformations of sedimentary Fe in waterways associated with coastal lowland acid sulfate soils (CLASS). The waterways contained acidic (pH 3.26–3.54), FeIII-rich (27–138 μM) surface water with low molar Cl:SO4 ratios (0.086–5.73). The surficial benthic sediments had high concentrations of oxalate-extractable Fe(III) due to schwertmannite precipitation (kinetically favoured by 28–30% of aqueous surface water Fe being present as the FeIIISO4 species). Subsurface sediments contained abundant pore-water HCO3 (6–20 mM) and were reducing (Eh < −100 mV) with pH 6.0–6.5. The development of reducing conditions caused reductive dissolution of buried schwertmannite and goethite (formed via in situ transformation of schwertmannite). As a consequence, pore-water FeII concentrations were high (>2 mM) and were constrained by precipitation–dissolution of siderite. The near-neutral, reducing conditions also promoted SO4-reduction and the formation of acid-volatile …

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Nutrient Leaching In Undisturbed Cores Of An Acidic Sandy Podosol Following Simultaneous Potassium Chloride And Di-Ammonium Phosphate Application, Ian Phillips, Edward Burton Jul 2009

Nutrient Leaching In Undisturbed Cores Of An Acidic Sandy Podosol Following Simultaneous Potassium Chloride And Di-Ammonium Phosphate Application, Ian Phillips, Edward Burton

Associate Professor Edward D Burton

In south-east Queensland, Australia, extensive areas of sandy soils (Podosols) with shallow (<1>m) watertables are used for exotic pine tree production. Despite concerns that surface-applied fertilisers (di-ammonium phosphate (DAP) and potassium chloride (KCl)) may be contributing to a decline in local groundwater quality, published information on nutrient leaching in these Podosols is scarce. Large (0.3 m i.d. · 0.85 m long) undisturbed soil cores were intermittently leached with deionised water following a single surface application of KCl in combination with DAP. Potassium was applied at rates (equivalent on a surface area basis) of 0 (K0), 50 (K50), 100 (K100) …

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Effects Of Diffusion And Resuspension On Nutrient Release From Submerged Sediments, Ian Phillips, Edward Burton, Darryl Hawker Jul 2009

Effects Of Diffusion And Resuspension On Nutrient Release From Submerged Sediments, Ian Phillips, Edward Burton, Darryl Hawker

Associate Professor Edward D Burton

Nutrient release from a coarse-sand (CS) and a fine-sand (FS) estuarine sediment into the overlying water column was studied under static (diffusion-controlled) and dynamic (resuspension) conditions. Resuspension increased the amounts of NH4+, NO3- and P released from the sediment cores compared to those released by diffusion alone due to direct release of these nutrients from the readily available pore-water and ion exchange fractions. The average effective NH4+, NO3- and P diffusion coefficients (De) were found to be similar for both sediments, and did not vary significantly between static and dynamic conditions. Values of De were typically of the order of …

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Copper Behaviour In A Podosol. Ii: Sorption Reversibility, Geochemical Partitioning And Column Leaching, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb Jul 2009

Copper Behaviour In A Podosol. Ii: Sorption Reversibility, Geochemical Partitioning And Column Leaching, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb

Associate Professor Edward D Burton

The sorption–desorption and leaching behaviour of Cu in a Podosol from south-east Queensland, Australia, was examined. Copper sorption was described by a linear distribution coefficient at low sorption levels (KDCa→0) of 481 L/kg and a sorption capacity (CS,Max) of 382 mg/kg. Selective removal of soil organic matter reduced these values by approximately 95%, indicating that Cu was sorbed predominantly to soil organic matter. The KDCa→0 and CS,Max values from Cu desorption experiments were 934 L/kg and 516 mg/kg, respectively, which indicates that sorption was not fully reversible. This irreversibility was related to …

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Effects Of Ph And Salinity On Copper, Lead And Zinc Sorption Rates In Sediments From Moreton Bay, Australia, Ian Phillips, Dane Lamb, Darryl Hawker, Edward Burton Jul 2009

Effects Of Ph And Salinity On Copper, Lead And Zinc Sorption Rates In Sediments From Moreton Bay, Australia, Ian Phillips, Dane Lamb, Darryl Hawker, Edward Burton

Associate Professor Edward D Burton

No abstract provided.

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Schwertmannite Transformation To Goethite Via The Fe(Ii) Pathway: Reaction Rates And Implications For Iron-Sulfide Formation, Edward Burton, Richard Bush, Leigh Sullivan, David Mitchell Jul 2009

Schwertmannite Transformation To Goethite Via The Fe(Ii) Pathway: Reaction Rates And Implications For Iron-Sulfide Formation, Edward Burton, Richard Bush, Leigh Sullivan, David Mitchell

Associate Professor Edward D Burton

Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III)-oxyhydroxysulfate mineral in acid-sulfate systems, where its formation and fate strongly influence water quality. The present study examines transformation of schwertmannite to goethite (FeOOH), as catalyzed by interactions with Fe(II) in anoxic aquatic environments. This study also evaluates the role of the Fe(II) pathway in influencing the formation of iron–sulfide minerals in such environments. At pH > 5, the rates of Fe(II)-catalyzed schwertmannite transformation were several orders of magnitude faster than transformation in the absence of Fe(II). Complete transformation of schwertmannite occurred within only 3–5 h at pH > 6 and Fe(II)(aq) 5 mmol L−1. Model calculations …

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Copper Behaviour In A Podosol. I: Ph-Dependent Sorption-Desorption, Sorption Isotherm Analysis And Aqueous Speciation Modelling, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb Jul 2009

Copper Behaviour In A Podosol. I: Ph-Dependent Sorption-Desorption, Sorption Isotherm Analysis And Aqueous Speciation Modelling, Edward Burton, Ian Phillips, Darryl Hawker, Dane Lamb

Associate Professor Edward D Burton

The effects of pH and Cu loading on the solid/solution partitioning of Cu in a Podosol from south-east Queensland, Australia was examined. Sorption–desorption of Cu exhibited maximum linear distribution coefficients (KD) at approximately pH 5. Observed decrease in KD values at pH >5 was attributed to increased solubility of native dissolved organic carbon (DOC) at higher pH and subsequent formation of non-sorbing Cu–DOC complexes. Speciation modelling with the MINTEQA2 code indicated that >90% of aqueous Cu was present as Cu–DOC complexes at pH >5.5. The effect of Cu loading was examined with sorption isotherm analysis at pH …

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Trace Metals And Nutrients In Bottom Sediments Of The Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker Jul 2009

Trace Metals And Nutrients In Bottom Sediments Of The Southport Broadwater, Australia, Edward Burton, Ian Phillips, Darryl Hawker

Associate Professor Edward D Burton

No abstract provided.

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Estimating Sludge Loadings To Land Based On Trace Metal Sorption In Soil: Effect Of Dissolved Organo-Metallic Complexes, Edward Burton, Darryl Hawker, M Redding Jul 2009

Estimating Sludge Loadings To Land Based On Trace Metal Sorption In Soil: Effect Of Dissolved Organo-Metallic Complexes, Edward Burton, Darryl Hawker, M Redding

Associate Professor Edward D Burton

This paper describes the results of research examining the effect of dissolved organo-metallic complexes of copper (Cu) and zinc (Zn) from sewage sludge leachate on sorption by a humic-gley soil A-horizon, and the influence of such complexes on resultant sludge loading estimates. Sorption was described with Linear, Freundlich or Langmuir equations, and compared between a sample of sludge leachate (containing 97.4% of Cu and 63.2% of Zn as dissolved organo-metallic complexes) and a reference solution (which mimicked the leachate, except for a lack of dissolved organic material). This comparison revealed that dissolved organo-metallic complexes significantly depressed Cu and Zn sorption …

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Almost Avoiding Permutations, Robert Brignall, Shalosh B. Ekhad, Rebecca Smith, Vincent Vatter Jul 2009

Almost Avoiding Permutations, Robert Brignall, Shalosh B. Ekhad, Rebecca Smith, Vincent Vatter

Dartmouth Scholarship

The permutation π of length n, written in one-line notation as π (1)π (2)· · · π (n), is said to contain the permutation σ if π has a subsequence that is order isomorphic to σ, and each such subsequence is said to be an occurrence of σ in π or simply a σ pattern. For example, π = 491867532 contains σ = 51342 because of the subsequence π (2)π (3)π (5)π (6)π (9) = 91672. Permutation containment is easily seen to be a partial order on the set of all (finite) permutations, which we simply denote by ≤. If …

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Comet C/2004 Q2 (Machholz): Parent Volatiles, A Search For Deuterated Methane, And Constraint On The Ch4 Spin Temperature, Boncho Bonev, Michael Mumma, Erika Gibb, Michael Disanti, Geronimo Villanueva, Karen Magee-Sauer, Richard Ellis Jul 2009

Comet C/2004 Q2 (Machholz): Parent Volatiles, A Search For Deuterated Methane, And Constraint On The Ch4 Spin Temperature, Boncho Bonev, Michael Mumma, Erika Gibb, Michael Disanti, Geronimo Villanueva, Karen Magee-Sauer, Richard Ellis

Physics Faculty Works

High-dispersion (λ/δλ ≈ 25,000) infrared spectra of Comet C/2004 Q2 (Machholz) were acquired on 2004 November 28-29, and 2005 January 19 (UT dates) with the Near InfraRed echelle SPECtrograph (NIRSPEC) at the Keck-2 telescope on Mauna Kea. We detected H2O, CH4, C2H2, C2H6, CO, H2CO, CH3OH, HCN, and NH3 and we conducted a sensitive search for CH3D. We report rotational temperatures, production rates, and mixing ratios (with respect to H2O) at heliocentric distances of 1.49 AU (2004 November) and 1.21 AU (2005 January). We highlight three principal results. (1) The mixing ratios of parent volatiles measured at 1.49 AU and …

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A Gpu Stream Computing Approach To Terrain Database Integrity Monitoring, Sean Patrick Mckeon Jul 2009

A Gpu Stream Computing Approach To Terrain Database Integrity Monitoring, Sean Patrick Mckeon

Computer Science Theses

Synthetic Vision Systems (SVS) provide an aircraft pilot with a virtual 3-D image of surrounding terrain which is generated from a digital elevation model stored in an onboard database. SVS improves the pilot's situational awareness at night and in inclement weather, thus reducing the chance of accidents such as controlled flight into terrain. A terrain database integrity monitor is needed to verify the accuracy of the displayed image due to potential database and navigational system errors. Previous research has used existing aircraft sensors to compare the real terrain position with the predicted position. We propose an improvement to one of …

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The Expectation Of Transition Events On Finite-State Markov Chains, Jeremy Michael West Jul 2009

The Expectation Of Transition Events On Finite-State Markov Chains, Jeremy Michael West

Theses and Dissertations

Markov chains are a fundamental subject of study in mathematical probability and have found wide application in nearly every branch of science. Of particular interest are finite-state Markov chains; the representation of finite-state Markov chains by a transition matrix facilitates detailed analysis by linear algebraic methods. Previous methods of analyzing finite-state Markov chains have emphasized state events. In this thesis we develop the concept of a transition event and define two types of transition events: cumulative events and time-average events. Transition events generalize state events and provide a more flexible framework for analysis. We derive computable, closed-form expressions for the …

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Submodular Percolation, Graham R. Brightwell, Peter Winkler Jul 2009

Submodular Percolation, Graham R. Brightwell, Peter Winkler

Dartmouth Scholarship

Let $f:{\cal L}\to\mathbb{R}$ be a submodular function on a modular lattice ${\cal L}$; we show that there is a maximal chain ${\cal C}$ in ${\cal L}$ on which the sequence of values of f is minimal among all paths from 0 to 1 in the Hasse diagram of ${\cal L}$, in a certain well-behaved partial order on sequences of reals. One consequence is that the maximum value of f on ${\cal C}$ is minimized over all such paths—i.e., if one can percolate from 0 to 1 on lattice points X with $f(X)\le b$, then one can do so along a …

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The Orbifold Landau-Ginzburg Conjecture For Unimodal And Bimodal Singularities, Natalie Wilde Bergin Jul 2009

The Orbifold Landau-Ginzburg Conjecture For Unimodal And Bimodal Singularities, Natalie Wilde Bergin

Theses and Dissertations

The Orbifold Landau-Ginzburg Mirror Symmetry Conjecture states that for a quasihomogeneous singularity W and a group G of symmetries of W, there is a dual singularity WT and dual group GT such that the orbifold A-model of W/G is isomorphic to the orbifold B-model of WT/GT. The Landau-Ginzburg A-model is the Frobenius algebra HW,G constructed by Fan, Jarvis, and Ruan, and the B-model is the Orbifold Milnor ring of WT . The unorbifolded conjecture has been verified for Arnol'd's list of simple, unimodal and bimodal quasi-homogeneous singularities with G the maximal diagonal symmetry group by Priddis, Krawitz, Bergin, Acosta, et …

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A Microwave Digestion Technique For The Extraction Of Fossil Diatoms From Coastal Lake And Swamp Sediments, Jeffrey Parr, Kathryn Taffs, Christopher Lane Jul 2009

A Microwave Digestion Technique For The Extraction Of Fossil Diatoms From Coastal Lake And Swamp Sediments, Jeffrey Parr, Kathryn Taffs, Christopher Lane

Jeffrey Parr

This study provides an introduction to a microwave digestion technique for the extraction of fossil diatoms from sediments. The microwave technique is compared with the standard diatom extraction technique of Battarbee (Diatom analysis. In: Berglund B.E. (ed.), Handbook of Holocene Palaeoecology and Palaeohydrology. John Wiley and Sons) that uses a combination of dilute hydrochloric acid and hydrogen peroxide and the advantages and disadvantages of their use are discussed. The results suggest that the microwave technique is fast, inexpensive and most importantly produces replicable fossil diatom assemblage data. Small samples sizes are used (0.3 g) for the microwave method thus lower …

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