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2007

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Articles 6511 - 6540 of 6763

Full-Text Articles in Physical Sciences and Mathematics

The Spectral And Photophysical Characterization Of Water Solubilizing Metal Phthalocyanines For Highly Sensitive Detection In Biological Studies, Vera Tamisha Verdree Jan 2007

The Spectral And Photophysical Characterization Of Water Solubilizing Metal Phthalocyanines For Highly Sensitive Detection In Biological Studies, Vera Tamisha Verdree

LSU Doctoral Dissertations

Efforts to improve the technology for DNA analyses stimulated the work presented here to develop a series of fluorescent probes that would aid in the increased multiplexing capabilities allowing the ability to detect multiple targets in a single measurement. Typically, spectral discrimination has been used to identify each DNA fragment in sequencing or diagnostic applications by means of unique emission properties from several labeling dyes. This has been accomplished with labels that fluoresce in the visible region. The limitations with these dyes is the broad emission profile making discrimination difficult, high intrinsic biological fluorescence and structural differences of the dyes …

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Shear Responses Of Poly(Ethylene Oxide)-Laponite Nanocomposite Hydrogels, Elena Loizou Jan 2007

Shear Responses Of Poly(Ethylene Oxide)-Laponite Nanocomposite Hydrogels, Elena Loizou

LSU Doctoral Dissertations

This research seeks to understand the structure and shear responses of poly(ethylene oxide)-Laponite nanocomposite hydrogels and to relate the macroscopic physical properties to the nanoscopic structural changes. Understanding that relationship is necessary, in order to tailor material properties to specific applications. Information on the structure at rest on multiple length scales was obtained by combining microscopic and neutron scattering techniques. The structural changes that occur in response to a shear field were explored using rheology and neutron scattering. These structures were examined as a function of polymer molecular weight, polymer and clay concentrations, and sample preparation method. While the sample …

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Subrepresentation Semirings And An Analogue Of 6j-Symbols, Nam Hee Kwon Jan 2007

Subrepresentation Semirings And An Analogue Of 6j-Symbols, Nam Hee Kwon

LSU Doctoral Dissertations

Let G be a quasi simply reducible group, and let V be a representation of G over the complex numbers $mathbb{C}$. In this thesis, we introduce the twisted 6j-symbols over G which have their origin to Wigner's 6j-symbols over the group SU(2) to study the structure constants of the subrepresentation semiring S_{G}(End(V)), and we study the representation theory of a quasi simply reducible group G laying emphasis on our new G-module objects. We also investigate properties of our twisted 6j-symbols by establishing the link between the twisted 6j-symbols and Wigner's 3j-symbols over the group G.

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Wet And Dry Aging Of Polymer-Asphalt Blends: Chemistry And Performance, Ionela Chiparus Glover Jan 2007

Wet And Dry Aging Of Polymer-Asphalt Blends: Chemistry And Performance, Ionela Chiparus Glover

LSU Doctoral Dissertations

A PG 76-22 Polymer Modified Asphalt Cement composition was subjected in the laboratory to accelerated aging using both a standard Thin Film Oven Test and a Pressure Aging Vessel. Conditions simulating wet atmospheres (PAV in saturated water vapors) as well as very long service terms (multiple dry and wet PAV operations) were studied. A Rotating Cylinder Aging Test has been employed as an alternate asphalt aging technique using the same PMAC composition in order to observe the initial phases of the oxidative aging process. The data provided by this technique was correlated with the actual aging in the field of …

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An Evaluation Of An Inshore Aquaculture Park For Sustainable Coastal Community Development, Vanesssa Maxwell Jan 2007

An Evaluation Of An Inshore Aquaculture Park For Sustainable Coastal Community Development, Vanesssa Maxwell

LSU Doctoral Dissertations

This dissertation addresses applying industrial park concepts to the development of aquaculture parks in public waters specifically for off-bottom triploid Easter oyster, Crassostrea virginica, culture. The objectives are to identify the permitting process, relevant agencies, and legislation needed to facilitate development of aquaculture parks in the Gulf of Mexico states, and test and analyze off-bottom oyster culture for commercial production of triploid oysters. Off-bottom culture can increase oyster production, but fouling organisms can reduce growth and survival rates. The Adjustable Longline System (ALS), commercially used in Australia, allows oyster bags to be suspended in the water column and positioned for …

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Mass Transfer And Evolution Of Compact Binary Stars, Vayujeet Gokhale Jan 2007

Mass Transfer And Evolution Of Compact Binary Stars, Vayujeet Gokhale

LSU Doctoral Dissertations

We present a study of key aspects of the evolution of binary stars with emphasis on binaries consisting of two white dwarf stars. The evolution of such systems is driven by the loss of angular momentum by gravitational wave radiation. Effects like mass transfer and other modes of angular momentum loss and redistribution influence the evolutionary fate of the binary, and can lead to a merger, the tidal disruption of one of the components or its survival as a long-lived AM Canum Venaticorum (AM CVn) type system. Our study takes into account some of these effects; like mass loss, tides, …

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Properties Of Silica-Polypeptide Composite Particles, Jianhong Qiu Jan 2007

Properties Of Silica-Polypeptide Composite Particles, Jianhong Qiu

LSU Doctoral Dissertations

Studies of grafting polymer on surfaces with chemical bonds started in the 1970’s, but few projects have focused on grafting polypeptide on spherical particles. In this research, polypeptides poly(å-carbobenzyloxy-L-lysine) (PCBL) or poly(ã-benzyl-L-glutamate) (PBLG) were grafted on silica sphere surfaces by using the “grafting from” method. The polypeptide-grafted silica spheres are called SiPCPs. The growth of polypeptide chains as a function of monomer amount and reaction time was explored. The properties of a mixture of PBLG rod-like polymer and PBLG SiPCPs were investigated. At high concentrations of these two components, the phase behavior was studied. At low concentrations of PBLG, the …

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The Application Of Controlled Radical Polymerization Processes On The Graft Copolymerization Of Hydrophobic Substituents Onto Guar Gum And Guar Gum Derivatives, Veronica Holmes Jan 2007

The Application Of Controlled Radical Polymerization Processes On The Graft Copolymerization Of Hydrophobic Substituents Onto Guar Gum And Guar Gum Derivatives, Veronica Holmes

LSU Doctoral Dissertations

Guar gum is a naturally occurring polysaccharide; guar gum and its derivatives, such as carboxymethyl guar gum (CMG) are widely used in the oil and gas industry. A hydraulic fracturing fluid for rock formations to enhance oil recovery (EOR) is comprised of viscosifier, gelled CMG, and sand particles (proppants). The gel is mixed with proppant (sand) and pumped at high rate and high pressure into an oil/gas well to the hydrocarbon-producing zone. The applied pressure will force the rock formation to fracture allowing entry of the guar gel/sand mixture. The mixture then fills the resultant fracture. The viscosity of the …

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Comparison Of Kp And Bbm-Kp Models, Gideon Pyelshak Daspan Jan 2007

Comparison Of Kp And Bbm-Kp Models, Gideon Pyelshak Daspan

LSU Doctoral Dissertations

In this dissertation we show that the solution of the pure initial-value problems for the KP and regularize KP equations are the same, to within the order of accuracy attributable to either, on the time scale from zero to epsilon to negative three halves power, during which nonlinear and dispersive effects may accumulate to make an order-one relative difference to the wave profiles.

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Synthesis And Evaluation Of Derivatives And Analogs Of Xanthene Dyes, Xiangyang Xu Jan 2007

Synthesis And Evaluation Of Derivatives And Analogs Of Xanthene Dyes, Xiangyang Xu

LSU Doctoral Dissertations

Xanthene dyes are one of the oldest synthetic dyes. Fluorescein was first synthesized by von Baeyer in 1871. Since its discovery, it has been extensively studied. Fluorescein can exist as four different ionic forms (cationic form, neutral form, monoanionic form and dianionic form). Under physiological conditions (pH 7.4), fluorescein mainly exists as the dianionic form which grants it large quantum yield and excellent solubility in water. This renders fluorescein and its derivatives useful for studies in biological media. Cysteine (Cys) and homocysteine (Hcy) are of the few amino acids which contain sulfur and both of them are believed to be …

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A Growth Theory Perspective On The International Diffusion Of Electronic Commerce., S.C Ho, Robert John Kauffman, T.P. Liang Jan 2007

A Growth Theory Perspective On The International Diffusion Of Electronic Commerce., S.C Ho, Robert John Kauffman, T.P. Liang

Research Collection School Of Computing and Information Systems

Information and communication technologies (ICTs) continue to have a profound effect on the economies and societies where they are used. In this article, we propose three related theories to describe the underlying mechanism for growth in e-commerce revenues at the national level. Endogenous growth theory posits that the primary drivers of e-commerce growth are internal to a country. Exogenous growth theory suggests that the primary drivers of e-commerce growth are external to an economic system, and reflect the forces of the regional economy. A blend of these, a mixed endogenous–exogenous growth theory, incorporates drivers from both the economy and …

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Searching And Tagging: Two Sides Of The Same Coin?, Qiaozhu Mei, Jing Jiang, Hang Su, Chengxiang Zhai Jan 2007

Searching And Tagging: Two Sides Of The Same Coin?, Qiaozhu Mei, Jing Jiang, Hang Su, Chengxiang Zhai

Research Collection School Of Computing and Information Systems

This paper presents the duality hypothesis of search and tagging, two important behaviors of web users. The hypothesis states that if a user views a document D in the search results for query Q, the user would tend to assign document $D$ a tag identical to or similar to Q; similarly, if a user tags a document D with a tag T, the user would tend to view document D if it is in the search results obtained using T as a query. We formalize this hypothesis with a unified probabilistic model for search and tagging, and show that empirical …

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Quantifying Position Accuracy Of Multimodal Data From Global Positioning System–Enabled Cell Phones, David P. Aguilar, Sean J. Barbeau, Miguel A. Labrador, Alfredo J. Perez, Rafael A. Perez Jan 2007

Quantifying Position Accuracy Of Multimodal Data From Global Positioning System–Enabled Cell Phones, David P. Aguilar, Sean J. Barbeau, Miguel A. Labrador, Alfredo J. Perez, Rafael A. Perez

Computer Science Faculty Publications

The emergence of cell phones with embedded Global Positioning System (GPS) chips provides opportunities to push personalized real-time travel information subject to an individual's current location. One such application, a travel assistant device, notifies cognitively disabled public transportation users when it is time to request a stop and exit the vehicle. GPS-enabled cell phones must provide highly accurate real-time location data for this type of service. The components used in the data-collection process are identified, and a quantitative analysis of real-time GPS data obtained with a cell phone while walking, driving a vehicle, and riding public transportation is provided. The …

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Quantum Dot Photolithography, Raghuveer Reddy Gadipalli Jan 2007

Quantum Dot Photolithography, Raghuveer Reddy Gadipalli

Doctoral Dissertations

"This dissertation presents a simple method for the photolithographic patterning of silica hydrogel monoliths and planar substrates with quantum dots and inorganic semiconductor nanoparticles. We developed a method for surface patterning and bulk (3D) patterning of silica hydrogel monoliths and surface patterning of planar substrates with CdS, CdSe, PbS and PbSe quantum dots using infrared light, ultraviolet light, X-rays, and multi-photon ionization radiation. Precursor combinations were prepared which can readily dissociate with IR, UV, X-rays, and multi-photon ionization radiation. Different capping agents were used for improving quantum dot size distribution. The luminescence quantum yield of the composites can be increased …

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Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony Jan 2007

Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony

Doctoral Dissertations

"Ethanol and ionizing radiation exposure are independently known to cause tissue damage through various mechanisms. Non-enzymatic and enzymatic metabolism of ethanol, the latter via the cytochrome P₄₅₀2E1-dependent pathway, produces free radicals which deplete cellular glutathione (GSH). Ionizing radiation exposure has been shown to induce lipid peroxidation, DNA damage, protein oxidation, and GSH depletion, as well. It was postulated that initial exposure to ethanol, followed by ionizing radiation, would result in heightened oxidative stress. The in vitro model used in this investigation was HepG2 cells (human hepatocellular liver carcinoma cell line), while the in vivo model was Cd-1 mice"--Abstract, page iii.

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An Investigation Of Lead And Other Metal Contaminants In The Sediments Of Clearwater Lake, Missouri, Gary W. Krizanich Jan 2007

An Investigation Of Lead And Other Metal Contaminants In The Sediments Of Clearwater Lake, Missouri, Gary W. Krizanich

Doctoral Dissertations

"The purpose of this investigation is to characterize the spatial and temporal distribution and concentration of trace metals in sediments of Clearwater Lake. Understanding how trace metals are released to and transported in aquatic environments is important to the overall understanding of the impacts of mining on the natural environment. The main focus of this research will be on historic sedimentation within Clearwater Lake, which may act as a sink where mining related trace metals are stored. Because of their high preservation rates in basins, sediments can provide detailed chronostratigraphic histories of trace metal inputs in lakes. Sediment records can …

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Electron Beam Characterization Of Carbon Nanostructures, Eric Samuel Mandell Jan 2007

Electron Beam Characterization Of Carbon Nanostructures, Eric Samuel Mandell

Doctoral Dissertations

"Atom-thick carbon nanostructures represent a class of novel materials that are of interest to those studying carbon's role in fossil fuel, hydrogen storage, scaled-down electronics, and other nanotechnology. Electron microscope images of "edge-on" graphene sheets show linear image features due to the projected potential of the sheets. Here, intensity profiles along these linear features can measure the curvature of the sheet, as well as the shape of the sheet (i.e. hexagonal, triangular). Also, electron diffraction powder profiles calculated for triangular graphene sheet shapes show a broadening of the low frequency edge of diffraction rings, in comparison to those calculated for …

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Hyphenated Hplc-Ms Technique For Analysis Of Compositional Monosaccharides Of Transgenic Corn Glycoprotein And Characterization Of Degradation Products Of Diazinon, Fonofos And Aldicarb In Various Oxidation Systems, Tongwen Wang Jan 2007

Hyphenated Hplc-Ms Technique For Analysis Of Compositional Monosaccharides Of Transgenic Corn Glycoprotein And Characterization Of Degradation Products Of Diazinon, Fonofos And Aldicarb In Various Oxidation Systems, Tongwen Wang

Doctoral Dissertations

"The studies of this dissertation are composed of two sections. The first one deals with the analysis of compositional monosaccharides of transgenic corn glycoproteins. The method used in this study involved derivatization of monosaccharides with two fluorophores followed by HPLC/fluorescence detection for quantitative studies, and by HPLC/SSI/MS for identification confirmation of individual monosaccharide...The second section investigates the degradation processes of several pesticides including diazinon, fonofos and aldicarb in various oxidation systems"--Abstract, page iv.

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Cauchy Integrals And Möbius Geometry Of Curves, David E. Barrett, Michael Bolt Jan 2007

Cauchy Integrals And Möbius Geometry Of Curves, David E. Barrett, Michael Bolt

University Faculty Publications and Creative Works

No abstract provided.

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Using Principles Of Momentum Conservation To Develop A Coastal Storm Impulse Scale (Cosi), Chris Adam Klentzman Jan 2007

Using Principles Of Momentum Conservation To Develop A Coastal Storm Impulse Scale (Cosi), Chris Adam Klentzman

Civil & Environmental Engineering Theses & Dissertations

Coastal engineers have long recognized the need for a storm classification system that combines wave conditions, storm surge, and the length of time for the storm event. A new classification system has been developed that is based on the conservation of total horizontal momentum. This research concentrated on developing the theory and then applying that theory for a 10-year period of data from the Army Corps of Engineers Field Research Facility (FRF) in Duck, North Carolina. When fully developed, the Coastal Storm Impulse scale (COSI) may be applied to all previous Hurricane and Northeaster storm events along a coast and …

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Biogeochemistry And Phytoplankton Dynamics In The Ross Sea, Antarctica, Amy Rebecca Shields Jan 2007

Biogeochemistry And Phytoplankton Dynamics In The Ross Sea, Antarctica, Amy Rebecca Shields

Dissertations, Theses, and Masters Projects

The Ross Sea, Antarctica seasonal phytoplankton bloom is one of the largest in the Southern Ocean. This project focuses on the biological pump, which removes carbon from the surface ocean to the deep ocean through the settling of particulate organic matter, the advection of dissolved organic carbon, and active flux due to vertical migration of zooplankton. The objective of this study was to focus on three interrelated components of the biological pump including sedimentation, photosynthetic rates and grazing. The study was conducted in coordination with the Interannual Variability in the Antarctic-Ross Sea program, which covered the time period between 2001--2005. …

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Neighborhood Defined Feature Selection Strategy For Improved Face Recognition In Different Sensor Modalitie, Satyanadh Gundimada Jan 2007

Neighborhood Defined Feature Selection Strategy For Improved Face Recognition In Different Sensor Modalitie, Satyanadh Gundimada

Electrical & Computer Engineering Theses & Dissertations

A novel feature selection strategy for improved face recognition in images with variations due to illumination conditions, facial expressions, and partial occlusions is presented in this dissertation. A hybrid face recognition system that uses feature maps of phase congruency and modular kernel spaces is developed. Phase congruency provides a measure that is independent of the overall magnitude of a signal, making it invariant to variations in image illumination and contrast. A novel modular kernel spaces approach is developed and implemented on the phase congruency feature maps. Smaller sub-regions from a predefined neighborhood within the phase congruency images of the training …

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Freelib: A Self-Sustainable Peer-To-Peer Digital Library Framework For Evolving Communities, Ashraf A. Amrou Jan 2007

Freelib: A Self-Sustainable Peer-To-Peer Digital Library Framework For Evolving Communities, Ashraf A. Amrou

Computer Science Theses & Dissertations

The need for efficient solutions to the problem of disseminating and sharing of data is growing. Digital libraries provide an efficient solution for disseminating and sharing large volumes of data to diverse sets of users. They enable the use of structured and well defined metadata to provide quality search services. Most of the digital libraries built so far follow a centralized model. The centralized model is an efficient model; however, it has some inherent problems. It is not suitable when content contribution is highly distributed over a very large number of participants. It also requires an organizational support to provide …

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Plant Assemblage Structure On Barrier Island ‘Pimple’ Dunes At The Virginia Coast Reserve Long-Term Ecological Research Site, Brett A. Mcmillan Jan 2007

Plant Assemblage Structure On Barrier Island ‘Pimple’ Dunes At The Virginia Coast Reserve Long-Term Ecological Research Site, Brett A. Mcmillan

Biological Sciences Theses & Dissertations

The habitats at the VCR LTER that were the focus of the current study are the Hog Island and Parramore Island 'pimples', small, rounded dunes forming along main dune ridges of the barrier islands. There are distinct plant assemblage zones found on pimples, although most of these dunes are 10–20 m in diameter. Hypotheses of the study were that fresh water availability was a main determinant of differences between assemblages and that pimple size and location would influence diversity and assemblage structure. Research goals were (1) to describe the plant assemblages on pimples, (2) to relate edaphic and geomorphological factors …

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Investigation Of A Possible Lead-Lag Relationship Between The Innuitian And Laurentide Ice Sheets, Arctic Canada, Paula Zimmerman Jan 2007

Investigation Of A Possible Lead-Lag Relationship Between The Innuitian And Laurentide Ice Sheets, Arctic Canada, Paula Zimmerman

OES Theses and Dissertations

Peaks of iron-rich grains in Arctic Ocean sediment cores matched to the Laurentide and Innuitian Ice Sheets appear to show a lead-lag relationship during the Late Pleistocene when grain abundances are plotted against time and depth below sea floor. Cores from across the Arctic have been analyzed to determine if this is the case. Of the six IRD events identified, the Innuitian leads 68% of the time with 26% of events in all cores occurring simultaneously. The Innuitian seems to lead 33.3% of the time when peaks from the Innuitian and Laurentide occur within close proximity (less than 1 cm), …

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Measurement Of Neutral Current Cross Sections At High Bjorken-X With The Zeus Detector At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli Jan 2007

Measurement Of Neutral Current Cross Sections At High Bjorken-X With The Zeus Detector At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli

Faculty Publications

A new method is employed to measure the neutral current cross section up to Bjorken-x values of one with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb-1 for e+p collisions and 16.7 pb-1 for e-p collisions at √s = 318 GeV and 38.6 pb-1 for e+p collisions at √s = 300 GeV. Cross sections have been extracted for Q2 ≥648 GeV2 and are compared to predictions using different parton density functions. For the highest x bins, the data have a tendency to lie above the expectations using recent parton density function parametrizations. © Springer-Verlag Berlin Heidelberg …

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Measurement Of Prompt Photons With Associated Jets In Photoproduction At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli Jan 2007

Measurement Of Prompt Photons With Associated Jets In Photoproduction At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli

Faculty Publications

The photoproduction of prompt photons, together with an accompanying jet, has been studied in ep collisions at a centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 77 pb-1. Cross sections were measured for the transverse energy of the photon and the jet larger than 5 and 6 GeV, respectively. The differential γ+jet cross sections were reconstructed as functions of the transverse energy, pseudorapidity and xγobs, the fraction of the incoming photon momentum taken by the photon-jet system. Predictions based on leading-logarithm parton-shower Monte Carlo models and next-to-leading-order (NLO) QCD generally underestimate the …

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Search For Stop Production In R-Parity-Violating Supersymmetry At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli Jan 2007

Search For Stop Production In R-Parity-Violating Supersymmetry At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli

Faculty Publications

A search for stop production in R-parity-violating supersymmetry has been performed in e+p interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb-1. At HERA, the R-parity-violating coupling λ' allows resonant squark production, e+d→̃ q. Since the lowest-mass squark state in most supersymmetry models is the light stop, ̃t, this search concentrated on production of ̃t, followed either by a direct R-parity-violating decay, or by the gauge decay to b̃x1+. No evidence for stop production was found and limits were set on λ'131 as a function of the stop mass in the framework of the minimal …

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Multiple Mixed-Type Attractors In A Competition Model, J. M. Cushing, Shandelle M. Henson, Chantel C. Blackburn Jan 2007

Multiple Mixed-Type Attractors In A Competition Model, J. M. Cushing, Shandelle M. Henson, Chantel C. Blackburn

Faculty Publications

We show that a discrete-time, two-species competition model with Ricker (exponential) nonlinearities can exhibit multiple mixed-type attractors. By this is meant dynamic scenarios in which there are simultaneously present both coexistence attractors (in which both species are present) and exclusion attractors (in which one species is absent). Recent studies have investigated the inclusion of life-cycle stages in competition models as a casual mechanism for the existence of these kinds of multiple attractors. In this paper we investigate the role of nonlinearities in competition models without life-cycle stages. © 2007 Taylor & Francis Group, LLC.

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Raman Scattering In Gan And Zno, Shinobu Nagata Jan 2007

Raman Scattering In Gan And Zno, Shinobu Nagata

Theses and Dissertations

The Micro-Raman scattering technique has been used for the study of GaN and ZnO. Capabilities of the Raman technique and existing literature on Raman spectroscopy in GaN and ZnO are reviewed. About 50 GaN and ZnO samples with a wide range of properties are studied. From the analysis of positions of the E2H and A1(LO) phonon modes, biaxial stress and plasmon coupling of the Al(LO) mode are observed and compared to a bulk GaN sample. The stress-related shift rate for the AI(LO) mode in hexagonal GaN is established to be 2.7 ± 0.4 cm-1/GPa through series of GaN with low …

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