Physical Sciences and Mathematics Commons^™

Co2 Sensitivity Of Southern Ocean Phytoplankton, Philippe D. Tortell, Christopher D. Payne, Yingyu Li, Scarlett Trimborn, Bjorn Rost, Walker O. Smith, Christina Riesselman, Robert B. Dunbar, Peter Sedwick, Giacomo R. Ditullio

OES Faculty Publications

The Southern Ocean exerts a strong impact on marine biogeochemical cycles and global air-sea CO₂ fluxes. Over the coming century, large increases in surface ocean CO₂ levels, combined with increased upper water column temps. and stratification, are expected to diminish Southern Ocean CO₂ uptake. These effects could be significantly modulated by concomitant CO₂-dependent changes in the region's biol. carbon pump. Here we show that CO₂ concentrations affect the physiology, growth and species composition. of phytoplankton assemblages in the Ross Sea, Antarctica. Field results from in situ sampling and ship-board incubation experiments demonstrate that inorganic …

Shallow Marine Carbonate Dissolution And Early Diagenesis-Implications From An Incubation Study, Xinping Hu, David J. Burdige

OES Faculty Publications

Surface carbonate sediments fro, sites on the Bahamas Bank with different seagrass densities were incubated across a range of O₂ delivery rates, to study the controls on metabolic carbonate dissolution in these sediments. The results continued the 1:1 ratio between the rates of O₂ consumption and carbonate dissolution, demonstrating that microbial respiration was the rate-limiting step in metabolic carbonate dissolution. Furthermore, the dissolution we observed was actually net dissolution resulting front Coupled dissolution and reprecipitation. This carbonate reprecipitation occurs on the time scale of days, and significantly alters the pore water dissolved inorganic carbon (DIC) stable isotopic composition. …

Pentadienyl Complexes Of Alkali Metals: Structure And Bonding, Erick Cerpa, Francisco J. Tenorio, Maryel Contreras, Manuel Villanueva, Hiram I. Beltran, Thomas Heine, Kelling J. Donald, Gabriel Merino

Chemistry Faculty Publications

A systematic density functional study of the structure and bonding in the alkali-metal pentadienyl complexes C₅H₇E (E = Li-Cs) and their analogues derived from the 2,4-dimethylpentadienyl ligand is performed. The bonding in these structures has been analyzed in some detail with reference to molecular orbital analysis, and energy partition analysis, obtained by density functional calculations. An energy decomposition analysis indicates that the electrostatic interaction is the main factor to be considered in the stabilization of the gas-phase complexes we have studied. The stability of the U-shaped minimum energy structure decreases (the potential energy surface becomes more …

Structural And Elastic Properties Of Mgx (X=Se, Te) Semi Conducting Compounds Under High Pressure, Purvee Bhardwaj, Sadhna Singh, Neeraj Kumar Gaur

Turkish Journal of Physics

In the present paper, we have investigated the high-pressure structural phase transition of magnesium chalcogenides using the three-body potential (TBP) model. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBP are in reasonably good agreement with experimental data. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP has promise to predict phase transition pressure, elastic constants, and their pressure derivatives for other chalcogenides as well.

Size-Controlled Synthesis Of Monodisperse Core/Shell Nanogels, William H. Blackburn, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Small, monodisperse nanogels (similar to 50-nm radius) were synthesized by free-radical precipitation polymerization and were characterized using a suite of light scattering and chromatography methods. Nanogels were synthesized with either N-isopropylacrylamide or N-isopropylmethacrylamide as the main monomer, with acrylic acid or 4-acrylamidofluorescein as a comonomer and N,N'-methylenebis(acrylamide) as a cross-linker. By varying the surfactant and initiator concentrations, particle size was controlled while maintaining excellent monodispersity. An amine-containing shell was added to these core particles to facilitate subsequent bioconjugation. Successful conjugation of folic acid to the particles was demonstrated as an example of how such materials might be employed in a …

Masses Of Charged Leptons And Gauge Mixing Parameters, Cvavb Chandra Raju

Turkish Journal of Physics

It is shown that the electroweak physics of the electron and the muon is based on the left-right gauge model with the mixing parameters 0.2254 and 0.2746. These mixing parameters are determined by the masses of the electron and the muon. The electroweak physics of the Tau-lepton and its left-handed neutrino is based on the gauge group SU(2)_L XU(1).The mixing parameter for this gauge model is 0.5 and is determined by the mass of the charged Tau-lepton. The W and Z bosons that mediate the electroweak physics of Tau-lepton and its neutrino have masses 173.5 GeV and 245.4 GeV, respectively.

The Energy Spectrum Of Two-Electron Semiconductor Quantum Dots, Mohammad K. Elsaid

Turkish Journal of Physics

The ground-state properties of a two-dimensional quantum-dot are studied. We have used the shifted 1/N expansion method to solve the relative part Hamiltonian of two electrons confined in a quantum in the presence of an applied uniform magnetic field. The spin singlet-triplet transition in the ground state of the QD is shown. We have also displayed the singlet-triplet energy gap, J = \Delta = E_T - E_S, against the strength of the magnetic field for two electron quantum dot. Based on comparisons, the eigenenergies obtained by the shifted method are in excellent agreement with exact, variational, Hartree-Fock (HF) and Full-Configuration …

Critical State Models For Intergrain Junctions Of Polycrystalline Superconductors By Third Harmonic Ac Susceptibility Measurements, Ioseb R. Metskhvarishvili

Turkish Journal of Physics

High harmonic response of high-T_c and Chevrel-phase polycrystalline superconductors are measured in the presence of small ac excitation field and dc magnetic field applied on it. The aim of this work is to study the Josephson weak link behavior and compare the two systems in order to understand the granular nature of polycrystalline superconductors. Critical state models are used to explain the nonlinear magnetic response in polycrystalline superconductors.

Photoelectrochemical Investigations On Hg_Xcd_{1-X}Se Thin Film Electrode/Electrolyte System, Vithal Bhivaba Pujari, L. P. Deshmukh

Turkish Journal of Physics

Thin film electrodes of Hg_xCd_{1-x}Se (0 \le x \le 0.2) were prepared in an aqueous alkaline medium (pH \cong 11) on highly conducting stainless steel substrates by chemical bath technique. Use of these films was made as an active photoelectrode in an electrochemical photovoltaic cell, comprising: electrode; sodium polysulphide electrolyte; and impregnated graphite as a counter electrode. The investigations on these cells were made by studying I-V and C-V characteristics in dark, power output, built-in-potential, spectral and photo responses. Cell performance parameters were evaluated: open-circuit photopotential V_{ph}; and short-circuit photocurrent I_{ph}; series and shunt resistances R_{s} and R_{sh}; quantum conversion …

Ac Conductivity And Ultrasonic Studies In Khco_3 Compound, Fathy Salman, Sayed Abouelhassan, Eslam Sheha, Mabrouk Elmansy

Turkish Journal of Physics

The total conductivity of KHCO_3 compound is studied in the frequency range 50 Hz-1 MHz and in the temperature range 300-370 K. The conductivity frequency dependence relation is divided into three regions: one at low frequency (dc conductivity), while the others appear at a moderate and relatively higher frequency range. In general, the conductivity frequency dependence conductivity obeys a double power law relation, \sigma_{tot} = \sigma_{dc} + A\omega^p + B\omega^q. The powers p and q have been found to be in the range 0 to 1 and 1 to 2, respectively. The attenuation coefficient \beta of KHCO_3 compound was studied …

Nonlinear Two-Mode Squeezed Vacuum States As Realization Of Su(1,1) Lie Algebra, Gamal Mohamed Abd Al-Kader, Abdel-Shafy Fahmy Obada

Turkish Journal of Physics

Nonlinear extensions of the two-mode squeezed vacuum states (NTMSVS's) are constructed and special cases of these states are discussed. We have constructed the NTMSVS's realization of SU(1,1) Lie algebra. Two cases of the definition are considered for unitary and non-unitary deformation operator functions. Some nonclassical properties of these states are discussed.

The Asymptotic Iteration Method For The Eigenenergies Of The Complex Potential V(X) = \Gamma X^4 + I \Beta X^3 + I \Alpha X, Abdallah Jamiel Sous

Turkish Journal of Physics

Recently, three complex potentials V(x) = i x^3,V(x) = i x^3 + i \alpha x, and V(x) = x^4 + i \alpha x have been studied in the literature. Here, we combine these potentials in one. With the aid of the asymptotic iteration method we have numerically calculated the eigenenergies of the new complex potential. The obtained numerical results are compared with those obtained by using the WKB, EMM, and MRF methods and found to be in an excellent agreement. We discuss how an adjustable parameter \zeta can help to improve our results.

Stability Of Hickson Groups Of Galaxies, Ibrahim Selim, Naseer Iqbal

Turkish Journal of Physics

In this work we have used the Viril theorem to investigate the dynamical stability of Hickson compact groups of galaxies. The average luminous mass of the galaxies member is approximately 1.3 \times 0^{11} M_{\odot} and average total luminous mass of group is approximately 4.6 \times 0^{11} M_{\odot}. The virial theorem has used to estimate the virial mass. The average Virial mass of group of galaxies is approximately 6.3 \times 0^{13} M_{\odot} This is attributed to the presence of large amount of dark matter which is more than 90% in this group. Hickson compact groups of galaxies are unstable system due …

Two-To-Four Coherent Beams Interference Patterns Of Non-Orthogonal Planes, Ali̇ekber Aktağ

Turkish Journal of Physics

In this paper, we present an analysis of intensity distribution of interference pattern of two-to-four linearly polarized plane waves at their intersection in a plane surface. A configuration in which the four plane waves intersect at different angles along four non-orthogonal planes is considered. We show that the shape and the intensity distribution of the interference pattern is strong function of the angles of planes, kinds of polarizations, beam incidence angles. A variety of two-dimensional intensity distribution arrays have been formed by two-to-four beams with differing plane angles, angles of beam incidence and beam polarizations, which may potentially be useful …

Heat Capacity Anomalies Of Tlins_2 And Tlgas_2 Single Crystals Detected By Differential Scanning Calorimetry (Dsc), Muhammed Açikgöz

Turkish Journal of Physics

Specific heat capacity C_p anomalies of layered single crystals TlInS_2 and TlGaS_2 have been investigated using differential scanning calorimetry (DSC) as a new technique for such crystals. Special features of C_p have been revealed in the temperature range of the possible phase transitions of both crystals. A sequence of maximum values of C_p is obtained at 163, 174, 184, 193, 201, 212, 224, 254, and 259 K for TlInS_2. In the case of TlGaS_2, the temperatures of the obtained maximum C_p values at 177 and 241 K agree well with the intervals of the phase transition temperatures reported in the …

Characterization Of Thin Film Al/P-Cdte Schottky Diode, M. G. Mahesha, V. B. Kasturi, G. K. Shivakumar

Turkish Journal of Physics

A study has been made on the behavior of Al/p-CdTe thin film junction grown by thermal evaporation method. I-V characteristics show that the Al makes Schottky contact with p-CdTe. The variation of junction capacitance with frequency and voltage has been studied to evaluate the barrier height. The activation energy and band gap have been estimated by studying variation of resistivity with temperature. Using all these data, band diagram of Al/p-CdTe has been proposed.

High Pressure Phase Transition Of Copper Halides, Deoshree Baghmar, Neeraj Kumar Gaur, Sadhna Singh, Dinesh Chandra Gupta

Turkish Journal of Physics

The structural changes within copper halides induced by pressure from zinc-blend to rock-salt passing through an intermediate tetragonal structure have been investigated using an effective interionic interaction potential. The values of the phase transition pressures obtained by us for the copper halides are in good agreement with their available experimental data. We have also investigated the equation of state, which shows an appreciable volume collapses at the phase transition pressures.

Groundwater Contamination In Caves: Four Case Studies In Spain, Monserrat Jiménez-Sánchez, Heather Stoll, Iñaki Vadillo, Manolo López-Chicano, María Domínguez-Cuesta, Wenceslao Martín-Rosales, Mónica Meléndez-Asensio

International Journal of Speleology

Groundwater quality was monitored in four Spanish caves using concentrations of nitrate, potassium, phosphorus and in some cases total organic carbon. Three of the caves are located in NW Spain and contain prehistoric cave paintings and hence have special conservation interest. Of these, two are open show caves (Tito Bustillo and Pindal Caves), while the other one (Herrerías Cave) is not managed for tours and is partially closed off to public access. The fourth cave (Las Maravillas Cave) is located in SW Spain and is opened to the public because of its geological features and natural beauty. In this paper, …

Patterns Of Aspect-Oriented Design, Black P. Andrew, James Noble, David J. Pearce, Arno Scmidmeir

Computer Science Faculty Publications and Presentations

Aspect-oriented programming languages are becoming commonplace, and programmers are accumulating experience in building and maintaining aspect-oriented systems. This paper addresses how the use of these languages affects program design: how aspect-oriented languages change the design space, which designs should be emulated and which avoided, and the strengths and weaknesses of particular kinds of design. We identify five patterns of aspect-oriented design: Spectator, Regulator, Patch, Extension, and Heterarchical Design. For each pattern, we describe the problem it solves, show how aspect-oriented language features are used in the pattern, give characteristic examples of the pattern’s use, and assess its benefits and liabilities. …

Private Query On Encrypted Data In Multi-User Setting, Feng Bao, Robert H. Deng, Xuhua Ding, Yanjiang Yang

Research Collection School Of Computing and Information Systems

Searchable encryption schemes allow users to perform keyword based searches on an encrypted database. Almost all existing such schemes only consider the scenario where a single user acts as both the data owner and the querier. However, most databases in practice do not just serve one user; instead, they support search and write operations by multiple users. In this paper, we systematically study searchable encryption in a practical multi-user setting. Our results include a set of security notions for multi-user searchable encryption as well as a construction which is provably secure under the newly introduced security notions.

Adhesion Enhancement Of Polymeric Films On Glass Surfaces By A Silane Derivative Of Azobisisobutyronitrile (Aibn)., Sudhir Mulik, Chariklia Sotiriou-Leventis, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Adhesion of polymeric films on surfaces can be due to a combination of van der Waals, electrostatic or covalent interactions between the two materials. The interfacial adhesion between a polymer film and glass or metal can be improved by using a broad class of silane coupling agents. Typically, silane coupling compounds used for adhesion improvement have structure similar to (R´O)3-Si-R, where R´O- is an alkoxy group and -R is an organofunctional group. Under appropriate reaction conditions alkoxy groups condense with hydroxyl groups available on the surface, resulting in surfaces decorated with organofunctional -R groups, which promote formation of covalent bonding …

Thermal Analysis Of Adsorbed Poly(Vinyl Acetate) On Silica, Boonta Hetayothin, Frank D. Blum

Chemistry Faculty Research & Creative Works

The physical properties of polymers at interfaces can be quite different from those in bulk due to the interaction between the absorbed polymer and the surface. This phenomenon can be probed through the dynamic behavior of the polymer chains at the interface which can be experimentally probed by techniques such as nuclear magnetic resonance spectroscopy (NMR),1 viscoelasticity, and calorimetry. At the polymer-air interface, polymer chains have more flexibility than those at the polymer-substrate interface. On the other hand, at the silica-polymer interface, where chains are more restricted on the surface, a higher glass transition temperature (Tg) results as compared with …

On Existence And Uniqueness Results For The Bbm Equation With Arbitrary Forcing Terms, Timothy A. Smith

Publications

The problem of classical solutions for the regularized long-wave equation is considered where various additional forcing terms are introduced which are often required for physical modifications in the wave theory. Sufficient conditions of solvability and existence are established and then these conditions are related to the structure of the forcing terms under consideration.

Stochastic Dynamic Equations, Suman Sanyal

Doctoral Dissertations

"We propose a new area of mathematics, namely stochastic dynamic equations, which unifies and extends the theories of stochastic differential equations and stochastic difference equations. After giving a brief introduction to the theory of dynamic equations on time scales, we construct Brownian motion on isolated time scales and prove some of its properties. Then we define stochastic integrals on isolated time scales. The main contribution of this dissertation is to give explicit solutions of linear stochastic dynamic equations on isolated time scales. We illustrate the theoretical results for dynamic stock prices and Ornstein-Uhlenbeck dynamic equations. Finally we study almost sure …

On The Reproducing Kernel Hilbert Spaces Associated With The Fractional And Bi-Fractional Brownian Motions, Daniel Alpay, David Levanony

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present decompositions of various positive kernels as integrals or sums of positive kernels. Within this framework we study the reproducing kernel Hilbert spaces associated with the fractional and bi-fractional Brownian motions. As a tool, we define a new function of two complex variables, which is a natural generalization of the classical Gamma function for the setting we consider.

Dgm-Fd: A Finite Difference Scheme Based On The Discontinuous Galerkin Method, Anne Marguerite Fernando

Mathematics & Statistics Theses & Dissertations

Accurate and efficient numerical wave propagation is important in many areas of study such as computational aero-acoustics (CAA). While dissipation and dispersion errors influence the accuracy of a method, efficiency can be assessed by convergence rates and effective adaptability to different mesh structures. Finite difference and finite element methods are commonly used numerical schemes in CAA. Finite difference methods have the advantages of ease of use as well as high order convergence, but often require a uniform grid, and stable boundary closure can be non-trivial. Finite element methods adapt well to different mesh structures but can become difficult to implement …

Synthesis And Evaluation Of Vegetable (Soybean) Oil Based Epoxy Resin For Beverage Can Coating And Enzymatic Synthesis And Characterization Of Tailored N&C End Protected Oligopeptides, Ying Gao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is related to the development of a soybean oil based epoxy resin and its application in beverage can coatings. Interior surfaces of beverage can are invariably coated with polymer coating. The most commonly used coatings at present are derived from bisphenol A (BPA) based epoxy reins. However, due to perceived endocrine disrupting nature of BPA and consequential adverse effects on humans and wildlife concerns for the use of BPA based coatings and its leaching into beverages have been expressed. The research in the first part describes the synthesis and evaluation of …

Lsuhsc Facilities Biweekly Update: January 2008, Lsuhsc Property And Facilities Management

LSUHSC Facilities Biweekly Updates: 2008

LSUHSC Facilities Biweekly Updates from January 4 and 18, 2008.

These updates describe damage and a timeline of repairs at the LSU Health Sciences Center - New Orleans campus due to Hurricane Katrina which made landfall August 29, 2005.

Lsuhsc Facilities Daily Update: January 2008, Lsuhsc Property And Facilities Management

LSUHSC Facilities Daily Updates: 2008

LSUHSC Dailly Facilities Updates from January 2008.

These updates describe damage and a timeline of repairs at the LSU Health Sciences Center - New Orleans campus due to Hurricane Katrina which made landfall August 29, 2005.

Toward A New Social Contract: A Tripartite Mixed-Methods Analysis Of Social Sustainability At Three Land-Grant Universities, Lyndsay Josephine Agans

Electronic Theses and Dissertations

Increasingly, colleges and universities in the United States are adapting toward a model of behavior that incorporates issues of sustainability. This adaptation in universities and in society has implications on the organizational and nation-state level, the very core of which may serve to reshape the social contract between the two. In addition to supplying a strong counter-hegemonic argument that alters the competitive economic agenda-setting paradigm, this study serves as a tripartite comparative case study analysis of university adaptation toward social sustainability. By employing a social capital lens to understanding social sustainability in higher education, this study seeks to examine the …