Physical Sciences and Mathematics Commons^™

Ionizing Radiation Detection Using Microstructured Optical Fiber, Stanton Dehaven

Electrical & Computer Engineering Theses & Dissertations

Ionizing radiation detecting microstructured optical fibers are fabricated, modeled and experimentally measured for X-ray detection in the 10-40 keV energy range. These fibers operate by containing a scintillator material which emits visible light when exposed to ionizing radiation. An X-ray source characterized with a CdTe spectrometer is used to quantify the X-ray detection efficiency of the fibers. The solid state CdTe detector is considered 100% efficient in this energy range. A liquid filled microstructured optical fiber (MOF) is presented where numerical analysis and experimental observation leads to a geometric theory of photon transmission using total internal reflection. The model relates …

Photoproduction Of Π0 On Hydrogen With Clas From 1.1 Gev - 5.45 Gev Using E+E –Γ Decay, Michael C. Kunkel

Physics Theses & Dissertations

Photoproduction of the π⁰ meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range E_γ = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction γp → pe ⁺e^–(γ). The final state of the reaction is the sum of two subprocesses for π⁰ decay, the Dalitz decay mode of π⁰ → e ⁺e^–γ and conversion mode where one photon from π⁰ → γγ decay is converted into a …

A Fault Prediction Scheme For Takagi-Sugeno Fuzzy Systems With Immeasurable Premise Variables And Disturbance, Balaje T. Thumati, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

As explained in the literature, it is very hard to measure premise variables of a Takagi-Sugeno (TS) fuzzy system. Therefore, in this paper, a fault detection and prediction (FDP) scheme is designed for a class of TS fuzzy systems with immeasurable (unknown) premise variables and external disturbances. A fault detection (FD) observer is designed to approximate the system output and the premise variables. Subsequently, a FD residual is generated by comparing the observer output with respect to the system output. The FD residual is evaluated to detect any faults in the system. Further, time-to-failure (TTF) of the TS fuzzy system …

Developing Important Marine Mammal Area Criteria: Learning From Ecologically Or Biologically Significant Areas And Key Biodiversity Areas, Collenn M. Corrigan, Jeff A. Ardron, Mia T. Comeros-Raynal, Erich Hoyt, Giuseppe Notarbartolo Di Sciara, Kent E. Carpenter

Biological Sciences Faculty Publications

1. This paper explores how criteria to identify important marine mammal areas (IMMAs) could be developed, and nested in existing global criteria. This process would consider 134 species of marine mammals. 2. Particular attention is given to two suites of global criteria to identify areas important for the persistence of marine biodiversity: Ecologically or Biologically Significant Areas (EBSAs) developed through the Convention on Biological Diversity (CBD), and Key Biodiversity Areas (KBAs) in revision through the International Union for the Conservation of Nature (IUCN). They are seen as mutually complementary in the development of IMMAs. 3. The specificities necessary for identifying …

Advancements In The Diastereoselective Synthesis Of Acyl Pyrrolidines Via The Tandem Aza-Cope—Mannich Cyclization Pathway, Danielle St. Germaine

Master's Theses and Doctoral Dissertations

We have developed a Lewis-acid catalyzed, diastereoselective aza-Cope rearrangement— Mannich cyclization to form acyl pyrrolidines from conformationally mobile substrates. In earlier studies from our lab, Brønsted acid-catalyzed reactions to form the same acyl pyrrolidines resulted in diastereoselectivities of 8:1 trans to cis at elevated temperatures (60 °C) over the course of 150 minutes. We have demonstrated an improvement in our method yielding exclusively the trans isomers at ambient temperature with substoichiometric amounts of BF₃•OEt₂ within 3 minutes. Catalyst loadings as low as 0.05 equivalents of BF₃•OEt₂ initiate this transformation. Our synthetic method employs the …

Emergence Of Algal Blooms: The Effects Of Short-Term Variability In Water Quality On Phytoplankton Abundance, Diversity, And Community Composition In A Tidal Estuary, Todd A. Egerton, Ryan E. Morse, Harold G. Marshall, Margaret R. Mulholland

OES Faculty Publications

Algal blooms are dynamic phenomena, often attributed to environmental parameters that vary on short timescales (e.g., hours to days). Phytoplankton monitoring programs are largely designed to examine long-term trends and interannual variability. In order to better understand and evaluate the relationships between water quality variables and the genesis of algal blooms, daily samples were collected over a 34 day period in the eutrophic Lafayette River, a tidal tributary within Chesapeake Bay's estuarine complex, during spring 2006. During this period two distinct algal blooms occurred; the first was a cryptomonad bloom and this was followed by a bloom of the mixotrophic …

Phytoplankton And Nutrient Dynamics In A Tidally Dominated Eutrophic Estuary: Daily Variability And Controls On Bloom Formation, Ryan E. Morse, Margaret R. Mulholland, Todd A. Egerton, Harold G. Marshall

OES Faculty Publications

To better understand nutrient dynamics and factors that promote the initiation of algal blooms, the Lafayette River, a tidal subestuary of Chesapeake Bay that experiences seasonal algal blooms, was sampled daily for a period of 54 d in the fall of 2005. Three phytoplankton blooms (chl a concentrations exceeding twice the average of monthly measurements from 2000 to 2009) occurred during this period: a mixed bloom of Akashiwo sanguinea and Gymnodinium sp., a monospecific Skeletonema costatum bloom, and a monospecific Gymnodinium sp. bloom. Over the sampling period, nutrient concentrations increased following precipitation events and were elevated between bloom periods but …

The Great 2012 Arctic Ocean Summer Cyclone Enhanced Biological Productivity On The Shelves, Jinlun Zhang, Carin Ashjian, Robert Campbell, Victoria Hill, Yvette H. Spitz, Michael Steele

OES Faculty Publications

A coupled biophysical model is used to examine the impact of the great Arctic cyclone of early August 2012 on the marine planktonic ecosystem in the Pacific sector of the Arctic Ocean (PSA). Model results indicate that the cyclone influences the marine planktonic ecosystem by enhancing productivity on the shelves of the Chukchi, East Siberian, and Laptev seas during the storm. Although the cyclone's passage in the PSA lasted only a few days, the simulated biological effects on the shelves last 1 month or longer. At some locations on the shelves, primary productivity (PP) increases by up to 90% and …

Reproductive Phase Determination In Male Meagre (Argyrosomus Regius, Sciaenidae): Testis Development And Histologic Corroboration Of A Gross Anatomical Scale, Nuno Prista, Leonel Gordo, José Lino Costa, Maria José Costa, Cynthia Jones

OES Faculty Publications

Reproductive stage determination of male gonads has received sparse attention in fish biology literature with few studies detailing the building of gross anatomical- and histologic scales. The meagre (Argyrosomus regius) is one of the world's largest sciaenids and supports a significant regional fishery in European and North African waters whose reproductive patterns are yet to be fully investigated. In the present study, we derive a macroscopic grading system for meagre testis using semi-quantitative graphs that feature the testis variability along the species size range and time of the year. We then describe the histological stages and reproductive phases of male …

Reproductive Phase Determination In Male Meagre (Argyrosomus Regius, Sciaenidae): Testis Development And Histologic Corroboration Of A Gross Anatomical Scale, Nuno Prista, Leonel Gordo, Jose L. Costa, Maria J. Costa, Cynthia M. Jones

OES Faculty Publications

Reproductive stage determination of male gonads has received sparse attention in fish biology literature with few studies detailing the building of gross anatomical-and histologic scales. The meagre (Argyrosomus regius) is one of the world's largest sciaenids and supports a significant regional fishery in European and North African waters whose reproductive patterns are yet to be fully investigated. In the present study, we derive a macroscopic grading system for meagre testis using semi-quantitative graphs that feature the testis variability along the species size range and time of the year. We then describe the histological stages and reproductive phases of …

The Impact Of Changing Surface Ocean Conditions On The Dissolution Of Aerosol Iron, Matthew P. Fishwick, Peter N. Sedwick, Maeve C. Lohan, Paul J. Worsfold, Kristen N. Buck, Thomas M. Church, Simon J. Ussher

OES Faculty Publications

The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols …

A Loose Domain Swapping Organization Confers A Remarkable Stability To The Dimeric Structure Of The Arginine Binding Protein From Thermotoga Maritima, Alessia Ruggiero, Jonathan D. Dattelbaum, Maria Staiano, Rita Berisio, Sabato D'Auria, Luigi Vitagliano

Chemistry Faculty Publications

The arginine binding protein from Thermatoga maritima (TmArgBP), a substrate binding protein (SBP) involved in the ABC system of solute transport, presents a number of remarkable properties. These include an extraordinary stability to temperature and chemical denaturants and the tendency to form multimeric structures, an uncommon feature among SBPs involved in solute transport. Here we report a biophysical and structural characterization of the TmArgBP dimer. Our data indicate that the dimer of the protein is endowed with a remarkable stability since its full dissociation requires high temperature as well as SDS and urea at high concentrations. In order to elucidate …

Stop Rotating! One Substitution Halts The B19- Motor, Francisco Cervantes-Navarro, Gerarso Martínez-Guajardo, Edison Osorio, Diego Moreno, William Tiznado, Rafael Islas, Kelling J. Donald, Gabriel Merino

Chemistry Faculty Publications

The B₁₉^- anion and other boron species have been dubbed ‘Wankel motors’ for the almost barrierless rotation of inner and outer concentric rings relative to each other in these compounds. A single substitution in B₁₉^- is shown to shut down the well-established fluxionality in the anion. A carbon atom substituted in the structure to give a neutral CB₁₈ species is shown computationally to enforce bond localization.

Upper Pleistocene And Holocene Palaeoenvironmental Records In Cueva Mayor Karst (Atapuerca, Spain) From Different Proxies: Speleothem Crystal Fabrics, Palynology And Archaeology., Virginia Martínez-Pillado, Arantza Aranburu, Juan Luis Arsuaga, Blanca Ruiz-Zapata, Maria José Gil-García, Heather Stoll, Iñaki Yusta, Eneko Iriarte, José Miguel Carretero, R. Lawrence Edwards, Hai Cheng

International Journal of Speleology

The Cueva Mayor karst system of Atapuerca, in Northern Spain, hosts a highly significant record of human occupation from the Pleistocene. The climatic context of the human activities during the Pleistocene-Holocene for this inland site has not been well constrained, since existing records of the palaeoclimatic evolution of the Northern Iberian Peninsula are from more distal coastal and high-elevation sites. In this study, we interpret the palaeoenvironmental information recorded on the petrography of a stalagmite and the pollen spectra of the Sierra de Atapuerca karst system during the last 20 kyr. The integration of both types of records has allowed …

Design And Implementation Of E-Commerce Site For Online Shopping, Sidhartha Reddy Vatrapu

All Capstone Projects

In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.

Online Shopping is a lifestyle e-commerce web application, which retails various fashion and lifestyle products (Currently Men’s Wear). This project allows viewing various products available enables registered users to purchase desired products instantly using PayPal payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to …

Risk Factors For Physical Violence Against Partners In The U.S., K. Daniel O'Leary, Nathan L. Tintle, Evelyn Bromet

Faculty Work Comprehensive List

Objective: To examine unique and relative predictive values of demographic, social learning, developmental, psychopathology, and dyadic variables as risk factors for perpetration of intimate partner physical aggression in a national sample of married or cohabiting individuals. Method: Men (n = 798) and women (n = 770) were selected from the public use data file of the 2003 National Comorbidity Survey Replication (NCS-R) which used a multistage cluster sampling design. Results: Eight percent of women and 5% of men reported perpetrating physical aggression in the past year. Based on multivariable regression analyses, among men, the unique risk factors for perpetrating physical …

The Results Of The First Photonuclear Reaction Performed In Turkey: The Zinc Example, İsmai̇l Boztosun, Haris Dapo, Süleyman Fati̇h Özmen, Yi̇ği̇t Çeçen, Mesut Karakoç, Abdullah Çoban, Alp Cesur, Tanfer Caner, Edi̇p Bayram, Gi̇zem Büşra Keller, Beyza Küçük, Abdullah Güvendi̇, Melek Derman, Deni̇z Kaya

Turkish Journal of Physics

We have investigated the decays of several zinc isotopes produced by photonuclear reactions, which were induced by bremsstrahlung photon beams from a clinical e-linac. A photon beam of 18 MeV endpoint energy was directed at a target consisting of primarily zinc isotopes in their natural abundances. Subsequently, the induced decays of unstable zinc isotopes were measured with an HPGe detector twice, once shortly after irradiation and once on the following day. Decays of Zn-63, Zn-65, Zn-69m, and Cu-67 were measured and fitted. In addition, the gamma energy levels of the daughters of these decays were measured with good accuracy. All …

Analytical Solution Of The Klein-Gordon Equation Under The Coulomb-Like Scalar Plus Vector Potential With The Laplace Transforms Approach, Ebrahim Momtazi, Ali Akbar Rajabi, Bentol Hoda Yazarloo, Hassan Hassanabadi

Turkish Journal of Physics

In this paper, analytical solution of the Klein-Gordon equation with Coulomb-like scalar plus vector potentials is obtained exactly. We considered the Laplace transform approach in our calculation. The exact bound state energy eigenvalues and the corresponding eigenfunctions are reported for various values of the quantum numbers n and l.

Influence Of Composition On The Structure And Optoelectronic Properties Of Pb_Xin_{25-X}Se_{75} Thin Films, Hesham Azmi Elmeleegi, Zeinab El Sayed El Mandouh, Ahmed Abdel Moez

Turkish Journal of Physics

Pb_xIn_{25-x}Se_{75} thin films with 2 compositions were prepared by thermal evaporation. The surface topography of these films was studied by transmission electron microscope. The optical reflectance and transmittance were studied in order to determine the optical parameters such as optical energy gap, refractive index, extinction coefficient, dielectric loss, and dielectric tangent loss for these films. A single oscillator theory equation was applied for these films in order to determine both dispersion energy and oscillating energy, and the ratio of free carrier concentration/effective mass (N/m*) was determined optically. It was found that change in the composition of these films affects strongly …

Representation Of Electromagnetic And Gravitoelectromagnetic Poynting Theorems In Higher Dimensions, Mustafa Emre Kansu, Murat Tanişli, Süleyman Demi̇r

Turkish Journal of Physics

This study investigates whether the electromagnetic and gravitoelectromagnetic energy conservation equations are obtained together by using octonion algebra or not. Maxwell and Maxwell-like equations for linear gravity with magnetic monopole terms are used in the SI unit system. A new complex octonionic field term is suggested for the first time. The complex octonionic source equation is then obtained. Finally, Poynting theorems for both electromagnetism and gravitoelectromagnetism are defined for the first time by using higher dimensional algebra.

Fast Numerical Algorithm For A High-Precision 6d Electromagnetic Positioning Navigation System, Qian Xiang, Shiqing Wang, Haifeng Liu

Turkish Journal of Physics

A fast numerical algorithm is proposed for the 6 degrees of freedom electromagnetic navigation system, which can be used to improve surgical operations guided by medical images. Both the rotation transformation technique and optimization technique are adopted in the algorithm. The results from simulations show that the calculating time is improved greatly under the required precision in the surgery. A navigation system based on the algorithm can make the medical device's dimensions miniaturized and the structure simplified and portable. The performance and application scope of the electromagnetic positioning navigation system can be improved.

Octonion Symmetric Dirac-Maxwell Equations, Bhupesh Chandra Chanyal

Turkish Journal of Physics

We know that the octonion algebra is the largest division algebra. Therefore, we have discussed the octonion 8-dimensional space as the combination of 2 (external and internal) 4-dimensional spaces. The octonion wave equations in terms of 8 components has been written in terms of an 8 x 8 matrix. Octonion forms of potential as well as fields equations of dyons in terms of an 8 x 8 matrix are discussed in a consistent manner. At last, we have obtained the generalized Dirac-Maxwell equations of dyons in two 4-dimensional spaces, from the 8 x 8 matrix representation of octonion wave equations. …

Saga Of Efficiency Degradation At High Injection In Ingan Light Emitting Diodes, Vitaliy Avrutin, Shopan A. Hafiz, Fan Zhang, Ümi̇t Özgür, Enrico Bellotti, Francesco Bertazzi, Michele Goano, Arvydas Matulionis, Adam T. Roberts, Henry O. Everitt, Hadis Morkoç

Turkish Journal of Physics

No abstract provided.

Extended Defects In Gan Nanocolumns Characterized By Cathodoluminescence Directly Performed In A Transmission Electron Microscope, Frank Bertram, Marcus Müller, Gordon Schmidt, Peter Veit, Jürgen Christen, Arne Urban, Joerg Malindretos, Angela Rizzi

Turkish Journal of Physics

Using cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope at liquid helium temperature, the structural and optical properties of GaN nanocolumns, in particular extended defects like stacking faults and dislocations, have been characterized. The influence of the crystalline real structure on the emission properties using the capability of addressing individual stacking faults is comprehensively examined.

Iii-Nitride Quantum Dots In Nanowires: Growth, Structural, And Optical Properties, Bruno Daudin

Turkish Journal of Physics

Nanowires (NWs) have emerged as a platform to build complex, self-assembled, defect-free nanostructures. In particular, the growth of single islands/disks of various III-nitride combinations (InGaN in GaN, GaN in AlN, AlGaN in AlN) are possible in NW heterostructures, extending the field of experimental quantum dot exploration. Specific to NWs, the possibility to disperse them paves the way to probe and investigate only a single wire/dot. In the present article, the growth of GaN disks/islands and InGaN islands as well as their optical properties at the nanometer scale will be reviewed. Besides the intentional growth of QD-in NW heterostructures, special attention …

A Study On Si And P Doped H-Bn Sheets: Dft Calculations, Hati̇ce Kökten, Şaki̇r Erkoç

Turkish Journal of Physics

Structural properties and energetics of silicon and phosphorus doped hexagonal boron nitride sheets were investigated by performing density functional theory calculations. The dopant atoms were substituted in a neutral charge state at either the B or the N site in the system as an impurity. All the systems under consideration were fully optimized. A systematic study was performed to see the effect of cell size on the calculated quantities, such as bond length, charge transfer, and defect formation energies. It was found that both silicon and phosphorus atom substitutions cause the bond lengths to increase with respect to the pristine …

Gan Nanostructuring For The Fabrication Of Thin Membranes And Emerging Applications, Ion Tiginyanu, Veaceslav Ursaki

Turkish Journal of Physics

We present a review of technological methods developed in recent years for the purpose of gallium nitride nanostructuring, with the main focus on fabrication of thin GaN membranes. In particular, we report on traditional methods of wet etching undercutting for membrane manufacturing, technologies applied for the fabrication of photonic crystal structures based on GaN nanomembranes, double side processing, and surface charge lithography. Prospects of membrane applications in photonic devices, sensors, and microoptoelectromechanical and nanoelectromechanical systems are discussed, taking into account the advantageous piezoelectric, optical, and mechanical properties of GaN and related III-V nitride materials.

Self-Assembled Nanocrystalline Zno Thin Film Transistor Performance Optimization For High Speed Applications, Burhan Bayraktaroglu, Kevin Leedy

Turkish Journal of Physics

ZnO nanocrystals grown at relatively low temperatures using various vacuum deposition techniques can yield semiconducting thin films of self-assembled nanocolumns 20-50 nm in diameter. Such films are suitable for the fabrication of high speed and transparent thin film transistors (TFTs). Unlike amorphous TFTs, the performance of ZnO transistors depends both on the crystal quality of nanocrystals and the electrical properties of boundary layers between them. We investigated the use of radio frequency sputtering, atomic layer deposition, and pulsed laser deposition techniques to fabricate self-assembled nanocrystalline thin films and determined the influence of deposition conditions on the performance of transistors. Device …

Optical Properties Of Zno/(Zn, Mg)O Quantum Wells, Thierry Bretagnon

Turkish Journal of Physics

This paper reviews the optical properties of ZnO/(Zn, Mg)O single quantum wells grown by molecular beam epitaxy. Both heteroepitaxial quantum well growth along the polar c-direction and homoepitaxial quantum well growth on the nonpolar M plane cases are considered. The optical properties of these quantum wells are investigated by using reflectance, continuous wave photoluminescence, and time-resolved photoluminescence spectroscopies. The quantum-confined Stark effect dominates the properties of the excitons for polar quantum wells. The magnitude of the internal electric field that is induced by both spontaneous and piezoelectric polarizations is determined by comparing the experimental results with a variational calculation of …

Synthesis And Gas Sensor Applications Of Nanostructured Zno Grown At Low Temperatures, Oleg Lupan, Thierry Pauporte, Lee Chow

Turkish Journal of Physics

ZnO nanoarchitecture-based nano- and microdevices came into the focus due to their multifunctional operation. In this work, we summarize cost-effective procedures to grow ZnO nano- and microstructures, namely hydrothermal growth and electrochemical deposition. These techniques allow the controllable growth of ZnO nano- and microarchitectures at relatively low temperatures, below 100 °C, and do not require sophisticated equipment. We report on technological details for synthesis of ZnO and its characterization and applications in different novel devices such as gas sensors. Nanosensors and microsensors were fabricated using a focused ion beam and by metal welding an individual nano- and microstructure to form …