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2009

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Articles 211 - 240 of 6337

Full-Text Articles in Physical Sciences and Mathematics

Metal Oxide And Mercuric Sulfide Nanoparticles Synthesis And Characterization, Xin Xu Dec 2009

Metal Oxide And Mercuric Sulfide Nanoparticles Synthesis And Characterization, Xin Xu

All Dissertations

Increasing applications of nanoparticles (NPs), such as metal oxide and mercuric sulfide NPs, lead to heightened environmental concern. Challenges to the study of natural and engineered NPs include the physical and chemical characterizations.
Commercially available and laboratory-synthesized metal based NPs, iron oxide (Fe2O3), copper oxide (CuO), titanium dioxide (TiO2), zinc oxide (ZnO) and mercuric sulfide (HgS) were studied by comprehensive characterizations methods. The general synthesis process was modified sol-gel method. The size and morphology of NPs could be influenced by temperature, sonication, calcination, precursor concentration, pH and types of reaction media. In the synthesis of nZnO in ethanol, the essential …

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Statistical Tools For Linking Engine-Generated Malware To Its Engine, Edna Chelangat Milgo Dec 2009

Statistical Tools For Linking Engine-Generated Malware To Its Engine, Edna Chelangat Milgo

Theses and Dissertations

Malware-generating engines challenge typical malware analysts by requiring them to quickly extract and upload to their customers' machines, a signature for each of a possibly vast number of never-before-seen malware instances that an engine can generate in a short amount of time In this thesis we propose and evaluate two methods for linking variants of engine-generated malware to its engine. The proposed methods use the w-gram frequency vector (NFV) of the opcode mnemonics of an engine-generated malware in- stance as a feature vector for the instance. An NFV is a tuple that maps «-grams with their frequencies. The in-formation contained …

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Computational Fluid Dynamics Of Aggregating Red Blood Cells In Postcapillary Venules, Bong Jae Chung, Sangho Kim, Paul C. Johnson, Aleksander S. Popel Dec 2009

Computational Fluid Dynamics Of Aggregating Red Blood Cells In Postcapillary Venules, Bong Jae Chung, Sangho Kim, Paul C. Johnson, Aleksander S. Popel

Department of Applied Mathematics and Statistics Faculty Scholarship and Creative Works

Aggregate formation of red blood cells (RBCs) in a postcapillary venular bifurcation is investigated with three-dimensional computer simulations using the Chimera grid method. Interaction energy between the RBCs is modelled by a depletion interaction theory; RBCs are modelled as rigid oblate ellipsoids. The cell-cell interactions of RBCs are strongly dependent on vessel geometry and shear rates. The experimental data on vessel geometry, pseudoshear rates, and Dextran concentration obtained in our previous in vivo RBC aggregation study in postcapillary venules of the rat spinotrapezius muscle were used to simulate RBC aggregation. The computational results were compared to the experimental results from …

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A Characterization Of Caffeine Imprinted Polypyrrole Electrode, Deepika Mandadi Dec 2009

A Characterization Of Caffeine Imprinted Polypyrrole Electrode, Deepika Mandadi

Masters Theses & Specialist Projects

Nanotechnology holds great potential for improving our lives by creating many new materials and devices in medical sciences, electronics and also in energy production. Molecularly imprinted polymers (MIPs) are highly stable synthetic polymers that possess molecular recognition properties due to cavities created in the polymer matrix that are complementary to an analyte both in shape and in positioning of functional groups. These MIPs have been widely employed for diverse applications (e.g., in chromatographic separation, drug screening, chemosensors, catalysis, immunoassays etc) due to their specificity towards the target molecules and high stability against physicochemical perturbations. Conductive polymers, (CPs) such as polypyrrole, …

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Transition From N-Type To P-Type Destroys Ferromagnetism In Semiconducting Sn1-XCoXO2 And Sn1-XCrXO2 Nanoparticles, C. Van Komen, A. Punnoose, M. S. Seehra Dec 2009

Transition From N-Type To P-Type Destroys Ferromagnetism In Semiconducting Sn1-XCoXO2 And Sn1-XCrXO2 Nanoparticles, C. Van Komen, A. Punnoose, M. S. Seehra

Physics Faculty Publications and Presentations

This work reports strong correlations between the structural, magnetic and electronic properties of room temperature ferromagnets (RTFM) Sn1-xCoxO2 and Sn1-xCrxO2 for x = 0 to 0.1. The samples prepared by the sol-gel chemical method show RTFM for x < xL with the limiting concentration xL = 0.01 for Co doping and xL = 0.025 for Cr doping. As doping level x is increased from x = 0, the magnetic moment per ion, μ, increases and the lattice volume VL decreases up to x = xL. …

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A 236-Ghz Fe3+ Epr Study Of Nanoparticles Of The Ferromagnetic Room-Temperature Semiconductor Sn1-XFeXO2 (X = 0.005), Sushil K. Misra, S. I. Andronenko, Alex Punnoose, Dmitry Tipikin, J. H. Freed Dec 2009

A 236-Ghz Fe3+ Epr Study Of Nanoparticles Of The Ferromagnetic Room-Temperature Semiconductor Sn1-XFeXO2 (X = 0.005), Sushil K. Misra, S. I. Andronenko, Alex Punnoose, Dmitry Tipikin, J. H. Freed

Physics Faculty Publications and Presentations

High-frequency (236 GHz) electron paramagnetic resonance (EPR) studies of Fe3+ ions at 255 K are reported in a Sn1-xFexO2 powder with x = 0.005, which is a ferromagnetic semiconductor at room temperature. The observed EPR spectrum can be simulated reasonably well as the overlap of spectra due to four magnetically inequivalent high-spin (HS) Fe3+ ions (S = 5/2). The spectrum intensity is calculated, using the overlap I(BL) + (I(HS1) + I(HS2) + I(HS3) + I(HS4)) 9 x e-0.00001xB, where B is the magnetic field intensity …

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Relating Fires’ Effect On Forest Succession And Forest's Effect On Fire Severity In One Burned And Unburned Environment, Tyler Jay Seiboldt Dec 2009

Relating Fires’ Effect On Forest Succession And Forest's Effect On Fire Severity In One Burned And Unburned Environment, Tyler Jay Seiboldt

Department of Environmental Studies: Undergraduate Student Theses

Wildfires are a natural part of many forest ecosystems and play a vital role in maintaining their health.  Wildfires can have a critical influence on a landscapes plant community through their relative frequency, seasonality, and severity.  One of the most heavily influenced regions by wildfire disturbance is the Klamath Mountain region of California.  I looked at the affect a wildfires severity had on the Whiskey creek valley within the Whiskeytown National Recreation Area.  8 tree species and 4 flower species were examined on both the burned and unburned regions within this valley nearly a year after the wildfire (May 17-23 …

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A System For Detecting Xml Similarity In Content And Structure Using Relational Database, Waraporn Viyanon, Sanjay Kumar Madria Dec 2009

A System For Detecting Xml Similarity In Content And Structure Using Relational Database, Waraporn Viyanon, Sanjay Kumar Madria

Computer Science Faculty Research & Creative Works

In this paper, we describe a system incorporating an improved technique that detects the similarity of two XML documents based on content and structure similarity using keys. the technique consists of three major components: A subtree generator and validator, a key generator, and similarity components that compare content and structure of the XML documents. First, an XML document is stored in a relational database and extracted into small subtrees using leaf-node parents. the leaf-node parents are considered as a root of a subtree which is then recursively traversed bottom-up for matching. Second, a possible key(s) is identified in order to …

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Morphology Of The Dayside Ionosphere Of Mars: Implications For Ion Outflows, Jane L. Fox Dec 2009

Morphology Of The Dayside Ionosphere Of Mars: Implications For Ion Outflows, Jane L. Fox

Physics Faculty Publications

Significant fluxes of tailward streaming ions have been detected in the Martian wake by instruments on spacecraft. Imposing outward fluxes at the top of a model will produce dayside ion density profiles that are characterized by smaller scale heights than those of diffusive equilibrium. We determine the maximum outward fluxes of ions, and those implied by radio occultation data, by constructing ∼180 models, with upward velocity boundary conditions in the range from 0 to (7–8) × 105 cm s−1 in small increments. As the upward velocity is increased, the topside ion or electron densities decrease until eventually the …

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Uptake Of Gold Nanoparticles In An Algae - Daphnid Food Chain, Matthew Osborne-Koch Dec 2009

Uptake Of Gold Nanoparticles In An Algae - Daphnid Food Chain, Matthew Osborne-Koch

All Theses

Nanoparticle entry into the environment can result in deleterious effects to exposed organisms, disruption of ecological processes, and accumulation within the wood web. Gold nanoparticles (AuNPs), which are classified as zero-valent metals, are of significant interest due to their use in a variety of applications including electrical, biomedical, catalytic, magnetic, and optical technology. The wide range of uses for AuNPs can be attributed to a combination of the unique physical properties of the element gold (i.e. density, conductivity, stability, etc.) and the diversity of sizes, shapes, and surface compositions that can be achieved through manipulation of AuNP synthesis. While previous …

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Analysis Of Mercury And Lead In Birds Of Prey From Gold-Mining Areas Of The Peruvian Amazon, Peggy Shrum Dec 2009

Analysis Of Mercury And Lead In Birds Of Prey From Gold-Mining Areas Of The Peruvian Amazon, Peggy Shrum

All Theses

This study was conducted to determine levels of lead and mercury in the raptors of the South-eastern Peruvian Amazon. The study took place within the Los Amigos Conservation Concession in Madre de Dios, Peru. Eighty-six raptors from among sixteen species were captured with Bal-Chatri traps. From each individual, feather samples were obtained for mercury analysis and blood was taken for lead analysis. Each raptor was then released without incident or injury.
Mercury amalgamation for gold extraction is widely used by small-scale, transient mining operations, which are numerous along the rivers and creeks in the tropical forests and other locations in …

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A Cognitive Model For Problem Solving In Computer Science, Jennifer Parham Dec 2009

A Cognitive Model For Problem Solving In Computer Science, Jennifer Parham

All Dissertations

According to industry representatives, computer science education needs to emphasize the processes involved in solving computing problems rather than their solutions. Most of the current assessment tools used by universities and computer science departments analyze student answers to problems rather than investigating the processes involved in solving them. Approaching assessment from this perspective would reveal potential errors leading to incorrect solutions.
This dissertation proposes a model describing how people solve computational problems by storing, retrieving, and manipulating information and knowledge. It describes how metacognition interacts with schemata representing conceptual and procedural knowledge, as well as with the external sources of …

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Synthesis And Development Of Novel Fullerene-Based Structures For Photovoltaics, Electronic Applications And Mri Contrast Agents, Manuel Chaur Dec 2009

Synthesis And Development Of Novel Fullerene-Based Structures For Photovoltaics, Electronic Applications And Mri Contrast Agents, Manuel Chaur

All Dissertations

Metallic nitride endohedral metallofullerenes (EMFs) are one of the most interesting types of metallofullerenes due to their high yields and interesting electronic properties. The synthesis of these compounds allows the encapsulation of different metals inside fullerenes making it possible to combine the properties of the metal with those of the fullerene. Their interesting electrochemical and optical features make them potential candidates for several applications such as molecular electronics, biomedical imaging, non-linear optical devices, and magnetic resonance imaging (MRI) agents. This thesis reports the synthesis of novel metallic nitride EMFs based on Gd, Nd, Pr, Ce and La. These families of …

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Convergenceconcepts: An R Package To Investigate Various Modes Of Convergence, Pierre Lafaye De Micheaux, Benoit Liquet Dec 2009

Convergenceconcepts: An R Package To Investigate Various Modes Of Convergence, Pierre Lafaye De Micheaux, Benoit Liquet

The R Journal

ConvergenceConcepts is an R pack age, built upon the tkrplot, tcltk and lattice packages, designed to investigate the convergence of simulated sequences of random variables. Four classical modes of convergence may be studied, namely: almost sure convergence (a.s.), convergence in probability (P), convergence in law (L) and convergence in r-th mean (r). This investigation is performed through ac curate graphical representations. This package may be used as a pedagogical tool. It may give students a better understanding of these notions and help them to visualize these difficult theoretical concepts. Moreover, …

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Structured P2p Technologies For Distributed Command And Control, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins Dec 2009

Structured P2p Technologies For Distributed Command And Control, Daniel R. Karrels, Gilbert L. Peterson, Barry E. Mullins

Faculty Publications

The utility of Peer-to-Peer (P2P) systems extends far beyond traditional file sharing. This paper provides an overview of how P2P systems are capable of providing robust command and control for Distributed Multi-Agent Systems (DMASs). Specifically, this article presents the evolution of P2P architectures to date by discussing supporting technologies and applicability of each generation of P2P systems. It provides a detailed survey of fundamental design approaches found in modern large-scale P2P systems highlighting design considerations for building and deploying scalable P2P applications. The survey includes unstructured P2P systems, content retrieval systems, communications structured P2P systems, flat structured P2P systems and …

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Automation In Cs1 With The Factoring Problem Generator, Joshua B. Parker Dec 2009

Automation In Cs1 With The Factoring Problem Generator, Joshua B. Parker

Master's Theses

As the field of computer science continues to grow, the number of students enrolled in related programs will grow as well. Though one-on-one tutoring is one of the more effective means of teaching, computer science instructors will have less and less time to devote to individual students. To address this growing concern, many tools that automate parts of an instructor’s job have been proposed. These tools can assist instructors in presenting concepts and grading student work, and they can help students learn to program more effectively. A growing group of intelligent tutoring systems attempts to tie all of this functionality …

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A Neural Network Approach To Border Gateway Protocol Peer Failure Detection And Prediction, Cory B. White Dec 2009

A Neural Network Approach To Border Gateway Protocol Peer Failure Detection And Prediction, Cory B. White

Master's Theses

The size and speed of computer networks continue to expand at a rapid pace, as do the corresponding errors, failures, and faults inherent within such extensive networks. This thesis introduces a novel approach to interface Border Gateway Protocol (BGP) computer networks with neural networks to learn the precursor connectivity patterns that emerge prior to a node failure. Details of the design and construction of a framework that utilizes neural networks to learn and monitor BGP connection states as a means of detecting and predicting BGP peer node failure are presented. Moreover, this framework is used to monitor a BGP network …

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Mrm-Applicable Orthogonal Polynomials For Certain Hypergeometric Functions, Izumi Kubo, Hui-Hsiung Kuo Dec 2009

Mrm-Applicable Orthogonal Polynomials For Certain Hypergeometric Functions, Izumi Kubo, Hui-Hsiung Kuo

Communications on Stochastic Analysis

No abstract provided.

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Exact Scenario Simulation For Selected Multi-Dimensional Stochastic Processes, Eckhard Platen, Renata Rendek Dec 2009

Exact Scenario Simulation For Selected Multi-Dimensional Stochastic Processes, Eckhard Platen, Renata Rendek

Communications on Stochastic Analysis

No abstract provided.

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Nonlinear Filtering Of Itô-Lévy Stochastic Differential Equations With Continuous Observations, S Popa, S S Sritharan Dec 2009

Nonlinear Filtering Of Itô-Lévy Stochastic Differential Equations With Continuous Observations, S Popa, S S Sritharan

Communications on Stochastic Analysis

No abstract provided.

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Sample Properties Of Random Fields. Ii. Continuity, Jürgen Potthoff Dec 2009

Sample Properties Of Random Fields. Ii. Continuity, Jürgen Potthoff

Communications on Stochastic Analysis

No abstract provided.

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On The Extension Of A Basic Property Of Conditional Expectations To Second Quantization Operators, Alberto Lanconelli Dec 2009

On The Extension Of A Basic Property Of Conditional Expectations To Second Quantization Operators, Alberto Lanconelli

Communications on Stochastic Analysis

No abstract provided.

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Stochastic Integral Characterizations Of Semi-Selfdecomposable Distributions And Related Ornstein-Uhlenbeck Type Processes, Makoto Maejima, Yohei Ueda Dec 2009

Stochastic Integral Characterizations Of Semi-Selfdecomposable Distributions And Related Ornstein-Uhlenbeck Type Processes, Makoto Maejima, Yohei Ueda

Communications on Stochastic Analysis

No abstract provided.

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Invariant States For The Asymmetric Exclusion Quantum Markov Semigroup, Julio C Garcia, Leopoldo Pantaleón-Martinez, Roberto Quezada Dec 2009

Invariant States For The Asymmetric Exclusion Quantum Markov Semigroup, Julio C Garcia, Leopoldo Pantaleón-Martinez, Roberto Quezada

Communications on Stochastic Analysis

No abstract provided.

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Irreducible And Periodic Positive Maps, Franco Fagnola, Rely Pellicer Dec 2009

Irreducible And Periodic Positive Maps, Franco Fagnola, Rely Pellicer

Communications on Stochastic Analysis

No abstract provided.

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Converse Comparison Theorems For Backward Doubly Stochastic Differential Equations, Mohamed El Otmani, Naoual Mrhardy Dec 2009

Converse Comparison Theorems For Backward Doubly Stochastic Differential Equations, Mohamed El Otmani, Naoual Mrhardy

Communications on Stochastic Analysis

No abstract provided.

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Spatial Instability Of Electrically Driven Jets With Finite Conductivity And Under Constant Or Variable Applied Field, Saulo Orizaga, Daniel N. Riahi Dec 2009

Spatial Instability Of Electrically Driven Jets With Finite Conductivity And Under Constant Or Variable Applied Field, Saulo Orizaga, Daniel N. Riahi

School of Mathematical & Statistical Sciences Faculty Publications

We investigate the problem of spatial instability of electrically driven viscous jets with finite electrical conductivity and in the presence of either a constant or a variable applied electric field. A mathematical model, which is developed and used for the spatially growing disturbances in electrically driven jet flows, leads to a lengthy equation for the unknown growth rate and frequency of the disturbances. This equation is solved numerically using Newton’s method. For neutral temporal stability boundary, we find, in particular, two new spatial modes of instability under certain conditions. One of these modes is enhanced by the strength Ω of …

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On The Testing And Estimation Of High-Dimensional Covariance Matrices, Thomas Fisher Dec 2009

On The Testing And Estimation Of High-Dimensional Covariance Matrices, Thomas Fisher

All Dissertations

Many applications of modern science involve a large number of parameters. In
many cases, the number of parameters, p, exceeds the number of observations,
N. Classical multivariate statistics are based on the assumption that the
number of parameters is fixed and the number of observations is large. Many of
the classical techniques perform poorly, or are degenerate, in high-dimensional
situations.
In this work, we discuss and develop statistical methods for inference of
data in which the number of parameters exceeds the number of observations.
Specifically we look at the problems of hypothesis testing regarding and the
estimation of the covariance …

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Exploring Formation And Distribution Of Halonitromethanes In Drinking Waters, Jia Hu Dec 2009

Exploring Formation And Distribution Of Halonitromethanes In Drinking Waters, Jia Hu

All Dissertations

ABSTRACT
Nine halonitromethanes (HNMs) were among the more than fifty unregulated high-priority disinfection by-products (DBPs) that were monitored for and detected in drinking waters in a 2000-2002 nationwide occurrence study funded by the US Environmental Protection Agency (USEPA). The toxicology studies conducted in recent years have shown that HNMs are one of the most cytotoxic and genotoxic classes among the emerging DBPs, with orders of magnitude higher cytotoxicity and genotoxicity than any of the regulated organic DBPs. Furthermore, brominated HNMs were found to be more toxic than their chlorinated analogs, with dibromonitromethane being the most cyto- and genotoxic. Today, our …

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Tactical Analysis Of Attack In Physical And Digital Security Incidents:Towards A Model Of Asymmetry, Atif Ahmad Dec 2009

Tactical Analysis Of Attack In Physical And Digital Security Incidents:Towards A Model Of Asymmetry, Atif Ahmad

Australian Information Warfare and Security Conference

Asymmetric warfare is frequently described as a conflict where ‘weaker’ parties aim to offset their relatively inadequate resources by using particular strategies and tactics to their advantage. This research-in-progress paper develops a concept model of asymmetric warfare that represents the leverage available to the ‘weaker’ party over the ‘stronger’ party simply because the former is attacking rather than defending. Points of leverage include choice of timing, location, method of attack, best use of limited resources and time to prepare. The resulting concept model is used to discuss generic defensive strategies that can be applied by ‘stronger’ parties in the physical …

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