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Measurement Of The High-Field Q Drop In The Tm010 And Te011 Modes In A Niobium Cavity, Gianluigi Ciovati, Peter Kneisel

Physics Faculty Publications

In the last few years superconducting radio-frequency (rf) cavities made of high-purity ( residual resistivity ratio > 200) niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards achieving reproducibly higher fields is represented by "anomalous'' losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field (B_p) is above about 90 mT, in the absence of field emission. This effect, called "Q drop'' has been measured in many laboratories with single- and multicell cavities mainly in the gigahertz range. In addition, a low-temperature (100 - 140 °C) "in situ'' baking of …

Measurement Of The X- And Q2 -Dependence Of The Asymmetry A1 On The Nucleon, K. V. Dharmawardane, S. E. Kuhn, P. Bosted, Y. Prok, G. Adams, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Zhang

Physics Faculty Publications

We report results for the virtual photon asymmetry A₁ on the nucleon from new Jefferson Lab measurements. The experiment, which used the CEBAF Large Acceptance Spectrometer and longitudinally polarized proton (¹⁵NH₃) and deuteron (¹⁵ND₃) targets, collected data with a longitudinally polarized electron beam at energies between 1.6 GeV and 5.7 GeV. In the present Letter, we concentrate on our results for A₁ ( x , Q² ) and the related ratio g1 / F₁ ( x , Q² ) in the resonance and the deep inelastic …

Measurement Of Deeply Virtual Compton Scattering With A Polarized-Proton Target, S. Chen, M. Amarian, H. Bagdasaryan, M. Bektasoglu, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Clas Collaboration

Physics Faculty Publications

The longitudinal target-spin asymmetry A_UL for the exclusive electroproduction of high-energy photons was measured for the first time in e→p→e′pγ. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH₃ target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinϕ moment is 0.252±0.042^stat±0.020^sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions …

Electron Scattering From High-Momentum Neutrons In Deuterium, A.V. Klimenko, S. E. Kuhn, H. Bagdasaryan, S. Bültmann, S. L. Careccia, K. V. Dharmawardane, Gail Dodge, G. Gavalian, N. Guler, C.E. Hyde-Wright, A. Klein, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, Et Al., Clas Collaboration

Physics Faculty Publications

We report results from an experiment measuring the semiinclusive reaction ²H(e,e′p_s) in which the proton p_s is moving at a large angle relative to the momentum transfer. If we assume that the proton was a spectator to the reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred. This method, known as spectator tagging, can be used to study electron scattering from high-momentum (off-shell) neutrons in deuterium. The data were taken with a 5.765 GeV electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CEBAF …

Η’ Photoproduction On The Proton For Photon Energies From 1.527 To 2.227 Gev, M. Bektasoglu, S.L. Careccia, K. V. Dharmawardane, G. E. Dodge, C. E. Hyde-Wright, H. G. Juengst, A. Klein, S. E. Kuhn, A. V. Klimenko, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Yun, J. Zhang, Et Al., Clas Collaboration

Physics Faculty Publications

Differential cross sections for the reaction γp→η′p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the η′N channel to both the S₁₁(1535) and P₁₁(1710) resonances, known to couple strongly to the ηN channel in photoproduction on the proton, and the importance of J=3/2 resonances in the process.

Measurement Of The Deuteron Structure Function F₂ In The Resonance Region And Evaluation Of Its Moments, H. Bagdasaryan, S. Bültmann, K. V. Dharmawardane, G. E. Dodge, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, S. E. Kuhn, L. B. Weinstein, J. Yun, Et Al., Clas Collaboration

Physics Faculty Publications

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F₂ with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasielastic peak up to the invariant mass of the final-state hadronic system W similar or equal to 2.7 GeV with four-momentum transfers Q² from 0.4 to 6 (GeV/c)². These data are complementary to previous measurements of the proton structure function F₂ and cover a similar two-dimensional region of Q² and Bjorken variable x. Determination of …

High-Energy Effective Action From Scattering Of Qcd Shock Waves, Ian Balitsky

Physics Faculty Publications

At high energies, the relevant degrees of freedom are Wilson lines--infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops

The Ground Axiom, Jonas Reitz

Dissertations, Theses, and Capstone Projects

Semi-Automated Grading Of Novice Java Programs For An Online Grading System, Micheal Alexis Ponniah

Theses, Dissertations and Culminating Projects

In recent years, World Wide Web usage for teaching and learning has increased rapidly. At the same time, even with some computerized works involved, the traditional grading of home works have not changed too much. Clearly an online grading system would be a highly desirable addition to the educational tool-kit, particularly if it can provide less costly and more effective outcome. The task of grading student programs is neither simple nor entirely mechanical; rather, it is often a tedious and laborious process that is prone to human error. Recently there are a lot of researches in automating this job. Of …

A Study Of Environmental Justice In Relation To Air Pollution And Income, Christian A. Malveaux

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is come to a conclusion on whether or not air pollution and income levels are connected. There is an ongoing pollution problem in Las Vegas. The question that will be attempted to answer in this is paper is: Is there a difference in the amount of air pollution in affluent parts of the Las Vegas Valley and the less affluent parts of the valley? Information and data regarding air pollution is gathered from the Clark County website and other literature. Information on income levels is gathered from journals and literature pertinent to the subject and …

Multiple View Geometry For Video Analysis And Post-Production, Xiaochun Cao

Electronic Theses and Dissertations

Multiple view geometry is the foundation of an important class of computer vision techniques for simultaneous recovery of camera motion and scene structure from a set of images. There are numerous important applications in this area. Examples include video post-production, scene reconstruction, registration, surveillance, tracking, and segmentation. In video post-production, which is the topic being addressed in this dissertation, computer analysis of the motion of the camera can replace the currently used manual methods for correctly aligning an artificially inserted object in a scene. However, existing single view methods typically require multiple vanishing points, and therefore would fail when only …

Sensor-Based Computing Techniques For Real-Time Traffic Evacuation Management, Georgiana Hamza-Lup

Electronic Theses and Dissertations

The threat of terrorist incidents is higher than ever before and devastating acts, such as the terrorist attacks on the World Trade Center and the Pentagon, have left many concerns about the possibility of future incidents and their potential impact. Unlike some natural disasters that can be anticipated, terrorist attacks are sudden and unexpected. Even if sometimes we do have partial information about a possible attack, it is generally not known exactly where, when, or how an attack will occur. This lack of information posses great challenges on those responsible for security, specifically, on their ability to respond fast, whenever …

Image-Based Material Editing, Erum Khan

Electronic Theses and Dissertations

Photo editing software allows digital images to be blurred, warped or re-colored at the touch of a button. However, it is not currently possible to change the material appearance of an object except by painstakingly painting over the appropriate pixels. Here we present a set of methods for automatically replacing one material with another, completely different material, starting with only a single high dynamic range image, and an alpha matte specifying the object. Our approach exploits the fact that human vision is surprisingly tolerant of certain (sometimes enormous) physical inaccuracies. Thus, it may be possible to produce a visually compelling …

Syntax-Based Concept Extraction For Question Answering, Demetrios Glinos

Electronic Theses and Dissertations

Question answering (QA) stands squarely along the path from document retrieval to text understanding. As an area of research interest, it serves as a proving ground where strategies for document processing, knowledge representation, question analysis, and answer extraction may be evaluated in real world information extraction contexts. The task is to go beyond the representation of text documents as "bags of words" or data blobs that can be scanned for keyword combinations and word collocations in the manner of internet search engines. Instead, the goal is to recognize and extract the semantic content of the text, and to organize it …

Sequential Binding Of Cobalt(Ii) To Metallo-Β-Lactamase Ccra, Gopal R. Periyannan, Alison L. Costello, David L. Tierney, Ke-Wu Yang, Brian Bennett, Michael W. Crowder

Physics Faculty Research and Publications

In an effort to probe Co(II) binding to metallo-β-lactamase CcrA, EPR, EXAFS, and ¹H NMR studies were conducted on CcrA containing 1 equiv (1-Co(II)-CcrA) and 2 equiv (Co(II)Co(II)-CcrA) of Co(II). The EPR spectra of 1-Co(II)-CcrA and Co(II)Co(II)-CcrA are distinct and indicate 5/6-coordinate Co(II) ions. The EPR spectra also reveal the absence of significant spin-exchange coupling between the Co(II) ions in Co(II)Co(II)-CcrA. EXAFS spectra of 1-Co(II)-CcrA suggest 5/6-coordinate Co(II) with two or more histidine ligands. EXAFS spectra of Co(II)Co(II)-CcrA also indicate 5/6 ligands at a similar average distance to 1-Co(II)-CcrA, including an average of about two histidines per Co(II). ^{1 …}

Inside Alternatively Powered Vehicles: The Problems And The Possibilities, Roxanne Greitz Miller

Education Faculty Articles and Research

This article explores alternatively powered vehicles.

Inside Global Warming, Roxanne Greitz Miller

Education Faculty Articles and Research

Over the last 15 years, much attention has been given to global warming, and whether the increase in the Earth's temperature in recent decades threatens the survival of life on Earth. Release of the films The Day After Tomorrow (2004), where North America is rapidly plunged into a new ice age, and An Inconvenient Truth (2006), where Al Gore focuses on the future impacts of global warming, has raised much public and media attention on the subject. As such, it's important that science teachers understand the basics behind the scientific phenomenon, the controversy surrounding the topic, and how to discuss …

Polystyrene Nanocomposites Based On An Oligomerically-Modified Clay Containing Maleic Anhydride, Xiaoxia Zheng, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

An oligomerically-modified clay containing maleic anhydride was used to prepare polystyrene-clay nanocomposites by melt blending and the effect of this modified clay on the thermal stability and fire performance was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed immiscible/intercalated/delaminated morphology. The maleic anhydride modified clay improved the compatibility between the clay and the polystyrene.

Ligand-Promoted Solvent-Dependent Ionization And Conformational Equilibria Of Re(Co)3Br[Ch2(S-Tim)2] (Tim = 1-Methylthioimidazolyl). Crystal Structures Of Re(Co)3Br[Ch2(S-Tim)2] And {Re(Co)3(Ch3Cn)[Ch2(S-Tim)2]}(Pf6), Rosalice M. Silva, Brendan J. Liddle, Sergey V. Lindeman, Mark D. Smith, James R. Gardinier

Chemistry Faculty Research and Publications

The compounds Re(CO)₃Br[CH₂(S-tim)₂] (1) and {Re(CO)₃(CH₃CN)[CH₂(S-tim)₂]}(PF₆) (2), where tim is 1-methylthioimidazolyl, were prepared in high yields and characterized both in the solid state and in solution. The solid-state structures show that the ligand acts in a chelating binding mode where the eight-member chelate ring adopts twist-boat conformations in both compounds. A comparison of both solid-state IR data for CO stretching frequencies and the solution-phase voltammetric measurements for the Re^1+/2+ couples between 1, 2, …

Highly Cooperative Tetrametallic Ruthenium-Μ-Oxo-Μ-Hydroxo Catalyst For The Alcohol Oxidation Reaction, Chae S. Yi, Tonya N. Zeczycki, Ilia A. Guzei

Chemistry Faculty Research and Publications

The tetrametallic ruthenium-oxo-hydroxo-hydride complex {[(PCy₃)(CO)RuH]₄(μ₄-O)(μ₃-OH)(μ₂-OH)} (1) was synthesized in two steps from the monomeric complex (PCy₃)(CO)RuHCl (2). The tetrameric complex 1 was found to be a highly effective catalyst for the transfer dehydrogenation of alcohols. Complex 1 showed a different catalytic activity pattern toward primary and secondary benzyl alcohols, as indicated by the Hammett correlation for the oxidation reaction of p-X-C₆H₄CH₂OH (ρ = −0.45) and p-X-C₆H₄CH(OH)CH₃ (ρ = +0.22) (X = …

Cowboy: An Agile Programming Methodology For A Solo Programmer, Ashby Brooks Hollar

Theses and Dissertations

Very little research in software engineering has focused on the model of a programmer working alone. These so-called cowboys are disdained for not working in teams to build software. In reality many cowboys work by themselves due to the circumstances of their work environment, not because they are unable or unwilling to work with well with others. These solo programmers could benefit from a methodology to assist them in consistently developing reliable software on time and within budget while satisfying the customer's needs. Cowboy was designed to help fill this void. This agile-based system incorporates the benefits of agile methodologies …

Enhancing The Third-Order Nonlinear Optical Properties Of Porphyrins And Molecular Wires, Jonathan L. Humphrey

Theses and Dissertations

The third-order nonlinear optical (NLO) properties of indium tin oxide (ITO) thin films, Fe3+, Mn3+, Co2+ 5,10,15,20-tetrakis-4hydroxytetraphenyl)porphyrin (TPP) films, and a series of ethynyl-linked azobenzene oligomers were investigated using degenerate four wave mixing (DFWM) with 100 fs laser pulses. To measure the NLO of ITO thin films, A DFWM method for measuring thin films on thick substrates was refined for the characterization of films less than 100 nm thick and applied to ITO films ~25 nm thick. It was found that the third-order nonlinear susceptibility of ITO, χ(3)ITO, is purely electronic at 900 - 1300 nm (11000 - 7700 cm-1) …

Janus Scorpionates:  Supramolecular Tectons For The Directed Assembly Of Hard−Soft Alkali Metallopolymer Chains, Rosalice M. Silva, Chengeto Gwengo, Sergey V. Lindeman, Mark D. Smith, James R. Gardinier

Chemistry Faculty Research and Publications

A new scorpionate ligand [HB(mtda)₃^-] containing mercaptothiadiazolyl (mtda) heterocyclic rings with both hard nitrogen donors and soft sulfur donors has been prepared. This new ligand, the Janus scorpionate, is a hybrid of a tris(pyrazolyl)borate and a tris(mercaptoimidazolyl)borate. The differential hard/soft character of the dissimilar donor groups in this bridging ligand was exploited for the controlled solid-state organization of homometallic and heterometallic alkali metal coordination polymers. Remarkably, in the case of sodium, coordination polymers with both acentric (with NaS₃N₃H kernels) and centric (with alternating NaN₆ and NaS₆H₂ kernels) chains are …

A Practical Synthesis Of Bridged Diarylacetylenes, Ruchi Shukla, Daniel M. Brody, Sergey V. Lindeman, Rajendra Rathore

Chemistry Faculty Research and Publications

An efficient and practical synthesis of bridged diarylacetylenes in multigram quantities has been successfully carried out using high-yielding (classical) synthetic methods and readily available starting materials. The structural analysis of the representative bridged diarylacetylenes by X-ray crystallography strongly suggests that conformations, bending of the linear triple bond, and the angle between the mean planes of aromatic rings in various bridged diarylacetylenes are governed by the p−π conjugation among the aromatic rings and the ethereal groups. Furthermore, the synthetic scheme also allows the preparation of (appropriately) bromo-substituted bridged diarylacetylenes which hold potential for their future usage for the preparation of polymeric …

Traveling Waves In A Suspension Bridge System, Robert A. Ain

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we study the traveling waves in a Lazer-McKenna suspension bridge system which is governed by two coupled nonlinear beam and wave equations. The Lazer-McKenna suspension bridge system describes the vertical deflections in the roadbed and supporting cable of a suspension bridge. Based on some basic analysis on the system, we are able to compute traveling waves numerically by using MAPLE. Multiple large-amplitude traveling waves are obtained. The graphs of various traveling waves are displayed and discussed.

Injective Modules And Prime Ideals Of Universal Enveloping Algebras, Jorg Feldvoss

University Faculty and Staff Publications

In this paper we study injective modules over universal enveloping algebras of finite-dimensional Lie algebras over fields of arbitrary characteristic. Most of our results are dealing with fields of prime characteristic but we also elaborate on some of their analogues for solvable Lie algebras over fields of characteristic zero. It turns out that analogous results in both cases are often quite similar and resemble those familiar from commutative ring theory.

Role Of Anomalous Warm Gulf Waters In The Intensification Of Hurricane Katrina, Menas Kafatos, D. Sun, Ritesh Gautam, Z. Boybeyi, Ruixin Yang, G. Cervone

Mathematics, Physics, and Computer Science Faculty Articles and Research

The year 2005 experienced several strong hurricanes intensifying in the Gulf of Mexico before making landfall that severely damaged the Gulf States, especially Hurricane Katrina. Remarkable similarities between sea surface temperature anomaly (SSTA) and major hurricane (categories 3 and higher) activity over the Gulf are identified. However, the intensification of individual hurricanes may not necessarily be temporally and spatially coincident with the distribution of warm waters or high sea surface temperature (SST). High SST values are found in advance of significant intensification of Hurricane Katrina. We emphasize that high SSTA which occurred at the right time and right place was …

Computational Sciences: At The Intersection Of Science And Engineering - Case Study For Academic And Research Programs, Menas Kafatos, P. A. Becker, Z. Boybeyi

Mathematics, Physics, and Computer Science Faculty Articles and Research

No abstract provided.

Comments On The Mechanism Of Aging Of Antimony Doped Tin Oxide Based Electrochromic Devices, Joo C. Chan, Nicole A. Hannah, Shankar B. Rananavare, Laura Yeager, Liviu Dinescu, Ashok Saraswat, Pradeep Iyer, James P. Coleman

Chemistry Faculty Publications and Presentations

Electrochromic effects of antimony doped tin oxide (ATO) nanoparticles are investigated to probe device yellowing (degradation). Voltage vs contrast ratio curves exhibit hysteresis, i.e., image-sticking phenomena due to irreversible charge insertion. X-ray, impedance and optical b* studies suggest that the yellowing/charge trapping is nanoparticle size-dependent with 4 nm size particles exhibiting the least yellowing. Yellowing results in increased impedances of electrode–electrolyte interface and electrode corrosion. Plausible sources of discoloration are formation of insulating complex alkali oxide film, carrier inversion (n-to-p type) through electrochemical Li doping, redeposition of the corroded electrode material and perhaps residual concentration of charge-transfer species.