Physical Sciences and Mathematics Commons^™

Three X-Ray Transients In M31 Oberserved With Swift, R. Voss, W. Pietsch, F. Haberl, H. Stiele, J. Greiner, G. Sala, Dieter H. Hartmann, D. Hatzidimitriou

Publications

Aims.The purpose of this study is to find transient X-ray sources in M 31, and to investigate and classify their nature.Methods.Three X-ray transients were observed with Swift. For each of the three X-ray transients we use the Swift X-ray and opticaldata together with observations from XMM-Newton and Chandra to investigate the lightcurves and the spectra of the outburst, andthereby to identify the source types. Results.The outburst of XMMU J004215.8+ 411924 lasted for about one month. The source had a hard power-law spectrum with aphoton index of 1.6. It was previously identified as a Be/X-ray binary based on the optical identification …

Supernova Neutrino Nucleosynthesis Of Light Elements With Neutrino Oscillations, Takashi Yoshida, Toshitaka Kajino, Hidekazu Yokomakura, Keiichi Kimura, Akira Takamura, Dieter H. Hartmann

Publications

Light element synthesis in supernovae through neutrino-nucleus interactions, i.e., the ν-process, is affected by neutrino oscillations in the supernova environment. There is a resonance of 13-mixing in the O/C layer, which increases the rates of charged-current ν-process reactions in the outer He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and 1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing resonance, compared to those without neutrino oscillations. In the case of an inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the increase in the 7Li and 11B yields is much smaller. Observations …

Towards A System For Controlling Client-Server Traffic In Virtual Worlds Using Sdn, Jason Anderson, Jim Martin

Publications

Scaling virtual worlds in the age of cloud computing is complicated by the problem of efficiently directing client-server traffic in the face of agile and dynamic compute resources. In this proposed model, Software Defined Networking and compact encoding of avatar data in packet headers are combined to make a fast, scalable, high capacity proxy server that can hide the server infrastructure while fitting well with the IaaS paradigm of modern cloud providers.

Neutron Study Of Structured Polymers At Interfaces, Thusitha Etampawala

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This work focuses on interfacial structure and dynamics of structured polymers in thin films and in solutions using neutron techniques accompanied by atomic force microscopy. We probed polymers with a common theme that were highly segregated either because of presence of ionic groups or topological constraints. In these polymers the interfacial regions often define their function in different applications such as clean energy, printing adhesions and drug delivery systems. Thin film studies include systems of polystyrene/sulfonated polystyrene, a rigid sulfonated polyphenylene and polystyrene three-arm stars/linear polystyrene. The first two systems include ionic components and the last exhibits topological constraints. Polystyrene …

Molecular Dynamics Simulations Using Advanced Sampling And Polarizable Force Fields, Tugba Kucukkal

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Molecular dynamics (MD) simulations were carried out for aqueous dipeptides, water over self-assembled monolayer (SAM) surfaces, and the nicotinic acetylcholine receptor (nAChR) ion channel. The main goal is to use advanced methods to increase the accuracy of molecular dynamics simulations while seeking solutions to problems relevant to chemistry, biophysics and materials science. In addition, activation energies of several cyclodimerization reactions were studied quantum mechanically. The simulations of the aqueous dipeptides and SAM surfaces involve modeling and detailed analysis of interfacial water, which is of interest to a range of fields from biology to materials science. For example, water has a …

Surface Shape Perception In Volumetric Stereo Displays, Meng Zhu

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In complex volume visualization applications, understanding the displayed objects and their spatial relationships is challenging for several reasons. One of the most important obstacles is that these objects can be translucent and can overlap spatially, making it difficult to understand their spatial structures. However, in many applications, for example medical visualization, it is crucial to have an accurate understanding of the spatial relationships among objects. The addition of visual cues has the potential to help human perception in these visualization tasks. Descriptive line elements, in particular, have been found to be effective in conveying shape information in surface-based graphics as …

Arachidonic Acid Reverses The Pyriproxyfen And Ibuprofen Induced Toxicity In Daphnia Magna, Gautam Kumar Ginjupalli

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Healthy reproduction and neonatal sex ratios of Daphnia are crucial to the health of the aquatic ecosystems in which Daphnia play principal roles in trophic transfer of nutrients. Combinations of environmental factors such as availability and quality of diet, overcrowding, hypoxia, reduced photoperiods and fall in ambient temperatures perturb normal parthenogeneic reproduction and induce sexual reproduction through male production. Male production provides a mechanism for overcoming specific stressors such as overcrowding and overwinter pond desiccation. However, it also induces a decrease in the Daphnia population that could have adverse implications on the pond ecosystem that depend on Daphnia . Interestingly, …

Ecology And Impacts Of Coyotes (Canis Latrans) In The Southeastern United States, Cady Etheredge

All Dissertations

Recent coyote (Canis latrans ) colonization of the southeastern United States has prompted speculation on the top-down effects of a new top predator on systems which have gone without a strong predator presence since the extirpation of the red wolf (Canis rufus ). This dissertation reports on the results of a series of investigations of the potential impact of coyotes on raccoons (Procyon lotor ) and other management issues related to coyotes in the Southeast. Chapters 1-3 present indirect field tests of the Mesopredator Release Hypothesis. Chapter 4 presents an overview of the current knowledge of the …

Factors Affecting The Surface-Mediated Reduction Of Plutonium In The Presence Of Pure Mineral Phases, Amy Hixon

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The overall objective of the research is to investigate the mechanistic and kinetic aspects of the surface-mediated reduction of plutonium. The first chapter is a critical review of plutonium sorption to pure mineral phases. The objective is to study if and how the mechanisms by which plutonium interacts with mineral surfaces are connected to mechanisms for the surface-mediated reduction of plutonium. The main conclusion of the review is that advanced spectroscopy, microscopy, and molecular modeling are needed to fully understand not only the surface structure of pure mineral phases, but also the coordination and bonding environment of plutonium surface complexes. …

Genetic Algorithm Techniques In Climate Changepoint Problems, Shanghong Li

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The first part of this dissertation studies genetic algorithms as a means of estimating the number of changepoints and their locations in a climatic time series. Such methods bypass classical subsegmentation algorithms, which sometimes yield suboptimal conclusions. Minimum description length techniques are introduced. These techniques require optimizing an objective function over all possible changepoint numbers and location times. Our general objective functions allow for correlated data, reference station aspects, and/or non-normal marginal distributions, all common features of climate time series. As an exhaustive evaluation of all changepoint configurations is not possible, the optimization is accomplished via a genetic algorithm that …

An Investigation Into The Interactions Of Gold Nanoparticles With Aquatic Vascular Macrophytes, James Glenn

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Nanomaterials (NMs) have promised lighter, stronger, smaller and more efficient products in areas such as electronics, medicines and even environmental sectors. This investigation started at the base of the food chain and characterized NMs interactions with aquatic plants. Citrate capped gold nanoparticles were used as a model nanoparticle to track fate and gain insight on factors that influence gold nanoparticle (AuNP) bioavailability and absorption. Four species of aquatic macrophytes were investigated. Azolla caroliniana, Myriophyllum simulans, Egeria densa and Myriophyllum aquaticum were selected due to growth habitat, leaf morphology and root structure. Because aquatic plants absorb the majority of their nutrients …

Chemical Evolution Of The Neutron-Rich Iron-Group Isotopes And Implications For The Formation Of Fun Cais, Tianhong Yu

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Calcium-aluminum-rich inclusions (CAIs) are millimeter-sized refractory objects found in primitive meteorites. CAIs are considered as some of the first solids to form in the solar system, because they are refractory. FUN CAIs, those with Fractionated and Unknown Nuclear effects, are a small subset of CAIs. These FUN CAIs show correlated excesses and deficits in the neutron-rich iron-group isotopes such as ⁴⁸ Ca and ⁵⁰ Ti which regular CAIs do not. Interestingly, these isotopes are most likely produced infrequently but in huge quantities in a rare class of thermonuclear (Type Ia) supernovae. I propose that the isotopic effects in the neutron-rich …

Exploratory Synthesis Of New Iron(Ii,Iii)-Containing Polyanion Framework Solids Of Electrochemical And Magnetic Interest, Liurukara Sanjeewa

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The studies demonstrated in this dissertation were primarily focused on the synthesis, structure and property characterizations of iron(II,III) containing framework solids. The scope of this research is threefold: 1) explore new iron(II, III)-containing open framework structures in hopes of creating new materials, useful in the areas of both Li- and Na-ion battery applications; 2) synthesis and characterization of low-dimensional magnetic nanostructures exhibiting novel magnetic properties due to confined magnetic lattices; and 3) conduct structure/property correlation studies to identify the origins of any unusual physical phenomena associated with these new compounds.

In the syntheses of new compounds, molten salt fluxes were …

Approximation In Multiobjective Optimization With Applications, Lakmali Weerasena

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Over the last couple of decades, the field of multiobjective optimization has received much attention in solving real-life optimization problems in science, engineering, economics and other fields where optimal decisions need to be made in the presence of trade-offs between two or more conflicting objective functions. The conflicting nature of objective functions implies a solution set for a multiobjective optimization problem. Obtaining this set is difficult for many reasons, and a variety of approaches for approximating it either partially or entirely have been proposed.

In response to the growing interest in approximation, this research investigates developing a theory and methodology …

Room Generation, Removal, And Recovery In Udk 3.5, Scott Johnson

All Theses

This paper explores algorithms and techniques for creating an extended game world that represents a radical departure from the widely used static content in current use with most games featuring procedurally generated game worlds. Using the Unreal Development Kit 3.5 game engine and focusing on a small set of rooms and doors the research sets to create a game world that is in constant flux and addresses issues of game development limitations on the size of game worlds.

Lithostratigraphic And Petrophysical Analysis Of The Middle Devonian Marcellus Shale At The Mamont Prospect, Westmoreland County, Pennsylvania, Ty Taylor

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The organic-rich Middle Devonian Marcellus Shale of the Appalachian basin is a rapidly developing natural gas play. Stratigraphic boundaries of the Marcellus Shale in Westmoreland County, Pennsylvania were identified using geophysical logs from 10 vertical gas-producing wells in a 23 sq. km area. Gamma-ray, bulk density, and resistivity well logs were examined to assess hydrocarbon potential. Values of porosity, total organic carbon (TOC), and water saturation (SW) were derived and mapped by incorporating well-log data into Marcellus-specific formulas. Gamma-ray, penetration (minutes per foot drilled), and mud-logging gas (total gas) from 12 horizontal wells from within the study area were also …

Macroscopic Investigation Of Ionic- And Nano-Silver Toxicity To Soil Nitrification Process, Abdurrahman Masrahi

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The worldwide production of engineered nanoparticles (ENPs) has grown rapidly in our era because of the popular applications in industrial and consumer markets. Especially silver (Ag) NP is one of mostly common ENPs in our consumer products due to its unique antimicrobial property. However, release of AgNPs into environment through wastewater treatment plants poses a question that what impact AgNPs have on microbially mediated processes in environment (e.g., nutrient and trace element cycles). In the last decades, numerous toxicological studies of AgNPs on bacteria have been conducted in pure culture systems, and several different antimicrobial mechanisms of AgNPs have been …

Aqueous Geochemistry Of Rhenium And Chromium In Saltstone: Implications For Understanding Technetium Mobility In Saltstone, Amanda Hatfield

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Incorporation of low level radioactive waste in cementitious materials is an important waste disposal technology in practice at a U.S. DOE facility, the Savannah River Site (SRS), Aiken, SC. One of the major risk drivers, technetium (99Tc)

The Detection Of A Light Echo From Sn 2007af, Dina Drozdov

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Type Ia supernovae are widely studied for their uniform properties, which make them ideal candidates for cosmological surveys. Although these exploding stars are popular targets, key funda-mental questions about their nature remain, and new techniques need to be developed to investigate the progenitor system and explosion mechanisms. Light echoes are created by light scattering off dust that reaches the observer after the direct path light from the explosion arrived and have been studied for the past 100 years. Light echoes from Type Ia supernovae are rare, with only a few cases being discovered in the past decades. Because light echoes …

The Fabrication And Study Of Silver Nanoparticle Structures, Aubrie Pfirman

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Nanotechnology and the synthesis of nanoparticle systems are attractive in part because of interesting, tunable optical and electrical properties that are not observed with bulk material. Silver nanoparticles (Ag NPs) interact with visible light more efficiently than any other system due to the excitation of plasmon resonances, which are the collective oscillations of the free electron density. These collective oscillations produce an enhanced local electromagnetic (EM) field: this field is responsible for highly-utilized phenomena such as surface enhanced Raman scattering (SERS), enhanced fluorescence, surface enhanced infrared absorption (SEIRA), and many others. Many experiments have been conducted to optimize and tailor …

Characterization Of The Hydrogeology And Stress State In The Vicinity Of The Homestake Mine, Lead, Sd, Johnathan Ebenhack

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Underground workings in fractured rock are common worldwide. They have applications in numerous areas and fields of study. These include mining operations, civil engineering projects like tunnels and underground facilities, and research projects that require underground laboratories such as the physics research being conducted by Sanford Laboratory at the former Homestake mine and Fermi Laboratory near Chicago (Bahcall et al. 2001, Elsworth 2009, Sadoulet et al. 2006, bge science@DUSEL, fnal.gov). These excavations can reach several kilometers in depth including the 3.9 km deep TauTona mine in South Africa, the 3 km deep LaRonde mine in Quebec and the 2.4 km …

Sequential Autotrophic-Heterotrophic Culture Of Scenedesmus Spp. For Lipid Production, Jazmine Taylor

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Algae are fascinating organisms that are receiving growing attention for their versatility on many fronts of research areas. Immense amounts of research is being conducted to find solutions to challenges in energy and climate change. A large portion of research is focused on algae as a potential solution to both of these issues. The focus of this research is to look at algae closer to home as a local, economical resource to aid in solving both of these problems. The algal genus Scenedesmus was tested for growth in a bi-phased scheme: photoautotrophically for carbon sequestration then heterotrophically on glycerol for …

Virtualizing Intelligent River®: A Comparative Study Of Alternative Virtualization Technologies, Aravindh Sampathkumar

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Emerging cloud computing infrastructure models facilitate a modern and efficient way of utilizing computing resources, enabling applications to scale with varying demands over time. The core enabler of the cloud computing paradigm is virtualization. The concept is not new; virtualization has garnered significant research attention, fostering a race to achieve the lowest possible virtualization overhead. The evolution has led to three primary virtualization approaches: full-virtualization, para-virtualization, and container-based virtualization, each with a unique set of strengths and weaknesses. Thus it becomes important to study and evaluate their quantitative and qualitative differences. The operational requirements of the Intelligent River® middleware system …

Stimulated Raman Scattering In Micro Sphere Resonators, Ruoyu Zhang

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Micro sphere resonators that hold optical whisper gallery modes (WGMs) provide an innovative option for implementing micro optical resonators. The unique properties of the micro sphere resonator make it capable to introduce resonance for various optical phenomenon, like stimulated Raman scattering (SRS), in micron scale.

This thesis illustrates the characteristics of micro sphere resonators and demonstrates the resonance-enhanced SRS in micro sphere resonators with reduce threshold power. Both theoretical and experimental results are presented. Coupling model for WGM is derived in transfer matrix method. Simulation analyses for mode pattern of WGMs are solved based on mathematic model and finite element …

L1 Methods For Shrinkage And Correlation, Jie Shen

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This dissertation explored the idea of L1 norm in solving two statistical problems including multiple linear regression and diagnostic checking in time series. In recent years L1 shrinkage methods have become popular in linear regression as they can achieve simultaneous variable selection and parameter estimation. Their objective functions containing a least squares term and an L1 penalty term which can produce sparse solutions (Fan and Li, 2001). Least absolute shrinkage and selection operator (Lasso) was the first L1 penalized method proposed and has been widely used in practice. But the Lasso estimator has noticeable bias and is inconsistent for variable …

Grb 091024a And The Nature Of Ultra-Long Gamma-Ray Bursts, F. J. Virgili, C. G. Mundell, V. Pal'shin, C. Guidorzi, R. Margutti, A. Melandri, R. Harrison, S. Kobayashi, R. Chornock, A Henden, A C. Updike, S B. Cenko, N R. Tanvir, I A. Steele, A Cucchiara, A Gomboc, A Levan, Z Cano, C J. Mottram, N R. Clay, D Bersier, D Kopac, J Japelj, A V. Filippenko, W Li, D Svinkin, S Golenetskii, Dieter H. Hartmann, P A. Milne, G Williams, P T. O'Brien, D B. Fox, E Berger

Publications

We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus–Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ∼1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory. We also observed the burst with 8 and 10 m class telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the optical and γ-ray …

High-Resolution Near-Infrared Spectroscopy Of Hd 100546. I. Analysis Of Asymmetric Ro-Vibrational Oh Emission Lines, Joseph Liskowsky, Sean D. Brittain, Joan R. Najita, John S. Carr, Greg W. Doppman, Matthew R. Troutman

Publications

We present observations of ro-vibrational OH and CO emission from the Herbig Be star HD 100546. The emission from both molecules arises from the inner region of the disk extending from approximately 13 AU from the central star. The velocity profiles of the OH lines are narrower than the velocity profile of the [O i] λ6300 line, indicating that the OH in the disk is not cospatial with the Oi. This suggests that the inner optically thin region of the disk is largely devoid of molecular gas. Unlike the ro-vibrational CO emission lines, the OH lines are highly asymmetric. We …

High-Resolution Near-Infrared Spectroscopy Of Hd 100546. Ii. Analysis Of Variable Rovibrational Co Emission Lines, Sean D. Brittain, Joan Najita, John S. Carr, Joseph Liskowsky, Matthew R. Troutman, Greg W. Doppmann

Publications

We present observations of rovibrational CO in HD 100546 from four epochs spanning 2003 January through 2010 December. We show that the equivalent widths of the CO lines vary during this time period with the v = 1–0 CO lines brightening more than the UV fluoresced lines from the higher vibrational states.While the spectroastrometric signal of the hot band lines remains constant during this period, the spectroastrometric signal of the v = 1–0 lines varies substantially. At all epochs, the spectroastrometric signals of the UV fluoresced lines are consistent with the signal one would expect from gas in an axisymmetric …

Preferential Scattering By Interfacial Charged Defects For Enhanced Thermoelectric Performance In Few-Layered N-Type Bi2te3, Pooja Puneet, Ramakrishna Podila, Mehmet Karakaya, Song Zhu, Jian He, Terry M. Tritt, Mildred S. Dresselhaus, Apparao Rao

Publications

Over the past two decades several nano-structuring methods have helped improve the figure of merit (ZT) in the state-of-the art bulk thermoelectric materials. While these methods could enhance the thermoelectric performance of p-type Bi₂Te₃, it was frustrating to researchers that they proved ineffective for n-type Bi₂Te₃ due to the inevitable deterioration of its thermoelectric properties in the basal plane. Here, we describe a novel chemical-exfoliation spark-plasma-sintering (CE-SPS) nano-structuring process, which transforms the microstructure of n-type Bi₂Te₃ in an extraordinary manner without compromising its basal plane …

Molecular Mechanisms Of Disease-Causing Missense Mutations, Shannon Stefl, Hafumi Nishi, Marharyta Petukh, Anna R. Panchenko, Emil Alexov

Publications

Genetic variations resulting in a change of amino acid sequence can have a dramatic effect on stability, hydrogen bond network, conformational dynamics, activity and many other physiologically important properties of proteins. The substitutions of only one residue in a protein sequence, so-called missense mutations, can be related to many pathological conditions, and may influence susceptibility to disease and drug treatment. The plausible effects of missense mutations range from affecting the macromolecular stability to perturbing macromolecular interactions and cellular localization. Here we review the individual cases and genome-wide studies which illustrate the association between missense mutations and diseases. In addition we …