Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2005

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 5161 - 5190 of 5573

Full-Text Articles in Physical Sciences and Mathematics

Visualization Based On Interactive Clipping: Application To Confocal Data, Gaurav Khanduja Jan 2005

Visualization Based On Interactive Clipping: Application To Confocal Data, Gaurav Khanduja

LSU Master's Theses

We have explored how clipping can be exploited in an interactive manner to visualize massive three-dimensional datasets. In essence, the proposed interactive clipping approach involves the dynamic adjustment of the clipping plane to expose any cross-section of the volume data and subsequent adjustment of the clipped surface to the best view position using a combination of rotation and translation. The thesis describes the design, implementation and application of our interactive-clipping-based visualization system. The implementation is done with OpenGL and C++, thus resulting in a highly portable and flexible system. For illustration, two types of scientific datasets, confocal data of a …

Go to article

Secure 3g User Authentication In Ad-Hoc Serving Networks, Lyn L. Evans Jan 2005

Secure 3g User Authentication In Ad-Hoc Serving Networks, Lyn L. Evans

LSU Master's Theses

The convergence of cellular and IP technologies has pushed the integration of 3G and WLAN networks to the forefront. With 3G networks' failure to deliver feasible bandwidth to the customer and the emerging popularity, ease of use and high throughput of 802.11 WLANs, integrating secure access to 3G services from WLANs has become a primary focus. 3G user authentication initiated from WLANs has been defined by an enhancement to the extensible authentication protocol, EAP, used to transport user authentication requests over WLANs. The EAP-AKA protocol executes the 3G USIM user challenge and response authentication process over the IP backbone for …

Go to article

Use Of Terraced Marsh Habitats By Estuarine Nekton In Southwestern Louisiana, Bryan Paul Gossman Jan 2005

Use Of Terraced Marsh Habitats By Estuarine Nekton In Southwestern Louisiana, Bryan Paul Gossman

LSU Master's Theses

A variety of techniques have been employed in attempts to mitigate the extensive wetland loss occurring in coastal Louisiana. Marsh terracing is a wetland restoration technique that has rapidly gained in popularity in recent years. Terraces are assumed to benefit coastal restoration by providing areas for emergent plant growth, reducing wave energies, and increasing edge habitat to support nekton communities. The objectives of this study were to: 1) determine the effect of marsh terraces on adjacent water quality and sediment characteristics, 2) compare nekton abundance, species richness, and diversity in edge and open water habitats within terraced and unterraced ponds, …

Go to article

Effects Of Adding Sediment To A Fresh Water Thin Mat Floating Marsh, Kate Carpenter Jan 2005

Effects Of Adding Sediment To A Fresh Water Thin Mat Floating Marsh, Kate Carpenter

LSU Master's Theses

Floating marshes are wetlands of emergent vascular vegetation which have a significant mat of live and dead roots, decomposing and dead organic material, and mineral sediments. This mat moves vertically as ambient water levels rise and fall. These marshes have unique hydrology in that overland sheet flow is reduced or eliminated leaving no inorganic sediment input, but there is extensive belowground water exchange. The effect of significant sediment introduction into wetlands with floating marshes is unknown. The purpose of this study was to observe the marsh mat response to Mississippi River sediment addition and measure species composition change and growth …

Go to article

Quantitative Clay Mineralogy Of Several Louisiana Soils, Johan Forsman Jan 2005

Quantitative Clay Mineralogy Of Several Louisiana Soils, Johan Forsman

LSU Master's Theses

A method was developed to simplify the approach to obtaining a better quantitative representation (QR) of complex clay mineral assemblages by XRD analysis. The method has eight steps: 1) preparation of samples with preferred orientation; 2) qualitative identification of phases; 3) peak decomposition to obtain precise locations of individual peaks contained within broad diffraction bands; 4) creation of a library of theoretical XRD patterns by modeling of one-dimensional XRD patterns; 5) selection of experimental library patterns; 6) employing the LINEST function found in common spreadsheet software to fit library patterns to experimental patterns; 7) evaluation of results to determine needed …

Go to article

Simulation Study Of Routing Protocols In Wireless Sensor Networks, Vatsalya Kunchakarra Jan 2005

Simulation Study Of Routing Protocols In Wireless Sensor Networks, Vatsalya Kunchakarra

LSU Master's Theses

Wireless sensor networks, a distributed network of sensor nodes perform critical tasks in many application areas such as target tracking in military applications, detection of catastrophic events, environment monitoring, health applications etc. The routing protocols developed for these distributed sensor networks need to be energy efficient and scalable. To create a better understanding of the performance of various routing protocols proposed it is very important to perform a detailed analysis of them. Network simulators enable us to study the performance and behavior of these protocols on various network topologies. Many Sensor Network frameworks were developed to explore both the networking …

Go to article

The Importance Of Size And Shape In Imprinted Polymers, Jason Campbell Jan 2005

The Importance Of Size And Shape In Imprinted Polymers, Jason Campbell

LSU Master's Theses

The existence of shape selectivity in non-covalent molecularly imprinted polymers has been proven using molecular probes. A series of amines varying with different structural motifs and secondary amines with different sized side chains were imprinted, and binding evaluated by HPLC for each amine on polymers imprinted with similar amines. Trends in the binding relationships revealed two major contributions of cavity structure on selectivity afforded by molecularly imprinted polymers (MIPs). First, sterics play a dominant role in cases where a molecules structure is too big too fit into an imprinted site formed from a smaller template molecule. Second, molecular structures that …

Go to article

Detailed Geochronology Of The Mississippi Sound During The Late Holocene, Brian Velardo Jan 2005

Detailed Geochronology Of The Mississippi Sound During The Late Holocene, Brian Velardo

LSU Master's Theses

The Mississippi Sound is a bar-built estuary that parallels the Mississippi Coast. It is bounded on the west by the St. Bernard lobe of the Mississippi River delta, Mobile Bay to the east, and the Gulf Coast barrier islands to the south. Few studies have investigated the late Holocene history of Mississippi Sound. In the present study, historical deposition in the Sound has been investigated using core data collected throughout the western, central, and eastern Mississippi Sound. The sediments within Mississippi Sound compose a complex depositional system that have responded to changes in sea level and hydrodynamics. Two factors that …

Go to article

Exchange Of Quispisisa Obsidian In Nasca: New Evidence From Marcaya, Kevin J. Vaughn, Michael D. Glascock Jan 2005

Exchange Of Quispisisa Obsidian In Nasca: New Evidence From Marcaya, Kevin J. Vaughn, Michael D. Glascock

Andean Past

No abstract provided.

Go to article

Evaluation Of A Novel Method Of Predicting Estrogen Activity Of A Group Of Structurally Diverse Compounds, Daniel Consoer Jan 2005

Evaluation Of A Novel Method Of Predicting Estrogen Activity Of A Group Of Structurally Diverse Compounds, Daniel Consoer

LSU Master's Theses

The number of environmental chemicals found to have some level of endocrine activity has led to concern about the possible effects these compounds could have on human health and the health of other species, populations, and possibly whole ecosystems. The United States Environmental Protection Agency has been charged with testing a large number of these compounds, called endocrine-disrupting chemicals or hormonally active agents for hormonal activity. Limited testing resources have led to a call for alternate methods of screening, possibly for use in prioritizing this list to assist in efficient allocation of resources for further testing. This study describes a …

Go to article

Digital Vertical Aerial Camera System For High-Resolution Site Inspections In Conservation Easment Monitoring, Kenton Williams Jan 2005

Digital Vertical Aerial Camera System For High-Resolution Site Inspections In Conservation Easment Monitoring, Kenton Williams

Electronic Theses and Dissertations

A three-level satellite to ground monitoring scheme for conservation easement monitoring has been implemented in which high-resolution imagery serves as an intermediate step for inspecting high priority sites. A digital vertical aerial camera system was developed to fulfill the need for an economical source of imagery for this intermediate step. A method for attaching the camera system to small aircraft was designed, and the camera system was calibrated and tested. To ensure that the images obtained were of suitable quality for use in Level 2 inspections, rectified imagery was required to provide positional accuracy of 5 meters or less to …

Go to article

2005-2006 Nova Southeastern University Farquhar College Of Arts And Sciences Student Catalog, Nova Southeastern University Jan 2005

2005-2006 Nova Southeastern University Farquhar College Of Arts And Sciences Student Catalog, Nova Southeastern University

Undergraduate Programs Course Catalogs

No abstract provided.

Go to article

An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood Jan 2005

An Assessment Of Key Aspects Of Warm And Cool Season Severe Flash Flooding In The Southern Appalachians, W. M. Baldwin, R. Mahmood

School of Natural Resources: Faculty Publications

No abstract provided.

Go to article

Pervasiveness Of Phytoliths In Prehistoric Southwestern Diet And Implications For Regional And Temporal Trends For Dental Microwear, Karl J. Reinhard, Dennis R. Danielson Jan 2005

Pervasiveness Of Phytoliths In Prehistoric Southwestern Diet And Implications For Regional And Temporal Trends For Dental Microwear, Karl J. Reinhard, Dennis R. Danielson

School of Natural Resources: Faculty Publications

Our previous analysis of phytolith content of coprolites showed that calcium oxalate phytoliths from desert food plants caused dental microwear among prehistoric Texas hunter-gatherers. We demonstrated that phytoliths from desert succulents were ubiquitous and abundant in hunter-gatherer coprolites. We found that calcium oxalate phytoliths were harder than human dental enamel. We concluded that phytoliths from desert succulent plants caused dental microwear and hypothesized that such dental microwear would be common in other desert hunter-gatherer and horticultural peoples. Presented here are further analyses of phytoliths from coprolites. Two additional hunter-gatherer sites and three Ancestral Pueblo (Anasazi) horticultural sites are included in …

Go to article

Dirac Sextic Oscillator In The Constant Magnetic Field, Ramazan Koç, Mehmet Koca Jan 2005

Dirac Sextic Oscillator In The Constant Magnetic Field, Ramazan Koç, Mehmet Koca

Turkish Journal of Physics

We introduce a Dirac equation which reproduces the usual radial sextic oscillator potential in the non-relativistic limit. We determine its energy spectrum in the presence of the magnetic field. It is shown that the equation is solved in the context of quasi-exactly-solvable problems. The equation possesses hidden sl_2-algebra and the destroyed symmetry of the equation can be recovered for specific values of the magnetic field which leads to exact determination of the eigenvalues.

Go to article

Standard Ubv Observations At The Çanakkale University Observatory (Çuo), Hi̇cran Bakiş, Volkan Bakiş, Osman Demi̇rcan, Edwin Budding Jan 2005

Standard Ubv Observations At The Çanakkale University Observatory (Çuo), Hi̇cran Bakiş, Volkan Bakiş, Osman Demi̇rcan, Edwin Budding

Turkish Journal of Physics

By using standard and comparison star observations carried out at different times of the year, at Çanakkale Onsekiz Mart University Observatory, we obtained the atmospheric extinction coefficients at the observatory. We also obtained transformation coefficients and zero-point constants for the transformation to the standard Johnson UBV system, of observations in the local system carried out with the SSP5A photometer and T40 telescope. The transmission curves and the mean wavelengths of the UBV filters as measured in the laboratory appear not much different from those of the standard Johnson system and found inside the transmission curve of the standard mean atmosphere.

Go to article

Air Moisture Sensing Properties Of Zncr_2o_4--K_2cro_4 Composites, Neşe Kavasoğlu, Murat Bayhan Jan 2005

Air Moisture Sensing Properties Of Zncr_2o_4--K_2cro_4 Composites, Neşe Kavasoğlu, Murat Bayhan

Turkish Journal of Physics

Crystalline structure, surface morphology and the response to air moisture of ceramic system of composition ZnCr_2O_4 - K_rCrO_4 formed by solid state reaction at elevated temperatures were investigated. The fired ceramic body, which proved to be mainly constructed from about 1 \mu m sized ZnCr_2O_4 spinel grains, was found to be porous. The humidity sensing behaviour of the sensors reveals that the electrical conduction is protonic and is controlled through the thin layers of water adsorbed on the surface of the grains, with charge transfer to the electrodes. Only the material containing 20\% K_2CrO_4 in ZnCr_2O_4 exhibited an exponential behaviour …

Go to article

Unsteady Flow Of A Dusty Conducting Fluid Between Parallel Porous Plates With Temperature Dependent Viscosity, Hazem Ali Attia Jan 2005

Unsteady Flow Of A Dusty Conducting Fluid Between Parallel Porous Plates With Temperature Dependent Viscosity, Hazem Ali Attia

Turkish Journal of Physics

This paper studies unsteady laminar flow of dusty conducting fluid between parallel porous plates with temperature dependent viscosity. The fluid is acted upon by a constant pressure gradient and an external uniform magnetic field is applied perpendicular to the plates. The parallel plates are assumed to be porous and subjected to a uniform suction from above and injection from below. The viscosity of the fluid is assumed to vary exponentially with temperature. The governing nonlinear partial differential equations are solved numerically and some important effects for the variable viscosity and the uniform magnetic field on the transient flow and heat …

Go to article

Synthesis And Characterization Of Co-Pb/Sba-15 Mesoporous Catalysts, Mukaddes Can, Burcu Akça, Ayşen Yilmaz, Deni̇z Üner Jan 2005

Synthesis And Characterization Of Co-Pb/Sba-15 Mesoporous Catalysts, Mukaddes Can, Burcu Akça, Ayşen Yilmaz, Deni̇z Üner

Turkish Journal of Physics

Pure SBA-15 and Co and/or Pb incorporated SBA-15 have been prepared by direct synthesis. The synthesized samples were characterized by powder X-ray diffraction and N_2 adsorption isotherms. It is observed that the surface area of pure SBA-15 mesoporous structure slowly decreases by the addition of metal oxides. By the loading of 5, 10, 15 wt % Pb into SBA-15, no characteristic peaks of metal oxide observed in the large angle XRD pattern. But loading of 20 wt % Pb in SBA-15 shows more appreciable characteristic peaks, indicating small quantity of crystallites of metal oxide existing on the surface of silica. …

Go to article

A Theoretical Study On Silicon And Iii-V Compound Nanotubes, Engi̇n Durgun, Sali̇m Çiraci Jan 2005

A Theoretical Study On Silicon And Iii-V Compound Nanotubes, Engi̇n Durgun, Sali̇m Çiraci

Turkish Journal of Physics

In this paper we present a theoretical study on single-wall silicon and III-V compound nanotubes. First principles plane wave calculations within density functional theory are used to predict energetics and electronic structures of armchair and zigzag nanotubes. The stability of tubular structures is further investigated at finite temperature by ab initio molecular dynamics calculations. Our results indicate that (n,0) zigzag and (n,n) armchair single-wall Si nanotubes are stable for n >= 6. Mechanically, the Si nanotubes are radially soft, however they are strong against axial deformations. Electronic analysis showed that zigzag nanotubes are metallic for n Keywords: silicon, nanotube, first …

Go to article

Physical Properties Of Holmium Promoted Superconductivity In Nd-Doped Ybco Ht_C-Superconductors, Morsy Abou Sekkina, Abdul Raouf Tawfik, Osama Hemeda, Mohamad Ahmad Taher Dawoud, Samy El-Attar Jan 2005

Physical Properties Of Holmium Promoted Superconductivity In Nd-Doped Ybco Ht_C-Superconductors, Morsy Abou Sekkina, Abdul Raouf Tawfik, Osama Hemeda, Mohamad Ahmad Taher Dawoud, Samy El-Attar

Turkish Journal of Physics

Samples of the nominal composition (Y_{0.5}Nd_{0.5-x}Ho_x) Ba_2Cu_3O_{7- \delta} , 0 \le x \le 0.5, have been prepared using the conventional solid state reaction. The effect of holmium and neodymium substitution on electrical resistivity, transition temperature T_c, lattice parameters, size of crystallite and grain size has been investigated. X-ray diffraction, electron micro-probe, scanning electron microscope and IR spectra, have been used in our investigation. The results show that the transition temperature T_c, electron-hole jump rate and lattice parameters (a, b) have minimum values at x = 0.2, while c increases to maximum at x = 0.2. The size of crystallite, the …

Go to article

Photoluminescence Characterization Of Al/Al_2o_3/Inp Mis Structures Passivated By Anodic Oxidation, Abdelhakim Mahdjoub, Hadj Bourdoucen, Abdelkader Djelloul Jan 2005

Photoluminescence Characterization Of Al/Al_2o_3/Inp Mis Structures Passivated By Anodic Oxidation, Abdelhakim Mahdjoub, Hadj Bourdoucen, Abdelkader Djelloul

Turkish Journal of Physics

Metal-insulator-semiconductor (MIS) structures were produced by electron beam evaporation of Al_2O_3 on InP. Polyphosphate thin films of thickness 100-150 Å were used to passivate the interface InP\Insulator. Photoluminescence spectra are reported at low temperature at various stages of the realization process of the MIS-InP structure. Photoluminescence topography at ambient temperature made it possible to characterize the surface state after each technological stage. The interface degradation under the effect of repeated annealing is insignificant up to temperatures of 350 °C. Radiative major defects detected by photoluminescence spectrum with energy 0.95-1.15 eV attributed to the complexes impurities of phosphorus vacancies are substantially …

Go to article

Dielectric Properties Of Industrial Polymer Composite Materials, Muhammad Akram, Athar Javed, Tasneem Zahra Rizvi Jan 2005

Dielectric Properties Of Industrial Polymer Composite Materials, Muhammad Akram, Athar Javed, Tasneem Zahra Rizvi

Turkish Journal of Physics

Frequency and temperature dependence of dielectric constant \varepsilon' and dielectric loss \varepsilon" in pure polyester resin and polymer composites with various types of glass fiber are studied in the frequency range 330 Hz-3 MHz and in the temperature range 25-150 °C. The experimental results show that \varepsilon' and \varepsilon'' increased with the addition of glass fiber in polyester resin. The value of \varepsilon' decreased with increasing frequency, which indicates that the major contribution to the polarization comes from orientation polarization. Dielectric loss peaks were also observed in the composite materials at high temperature due to T_g of polyester. The value …

Go to article

The Effect Of Preparation Conditions On The Growth Rate Of Films, The Yield Of Precipitated Powder And The Dc Conductivity Of Polypyrrole, S. A. Saafan, M. M. Ayad, E. H. El-Ghazzawy Jan 2005

The Effect Of Preparation Conditions On The Growth Rate Of Films, The Yield Of Precipitated Powder And The Dc Conductivity Of Polypyrrole, S. A. Saafan, M. M. Ayad, E. H. El-Ghazzawy

Turkish Journal of Physics

Polypyrrole (PPy) was prepared by a chemical method by using oxidizing agents ferric chloride and potassium persulphate, both as films and pellets. The effect of various variables-such as aging of the films, film thickness, ratios of the reactants and type of the sample (film or disc)-on DC conductivity were investigated. The results from samples prepared with ferric chloride exhibited an increase in conductivity with increasing concentration of oxidizing agent to a certain ratio, above which a slight decrease occurs. Whereas in the case of using potassium persulphate as the oxidizing agent, a decrease in conductivity occurs with increasing its concentration. …

Go to article

Origins Of Reverse Bias Currents In A Typical Bpw34 Photodiode, Habi̇be Bayhan, Şadan Özden Jan 2005

Origins Of Reverse Bias Currents In A Typical Bpw34 Photodiode, Habi̇be Bayhan, Şadan Özden

Turkish Journal of Physics

Measurements of the dark reverse current in a typical BPW34 silicon photodiode have been made in the temperature range 100-300 K at various reverse bias voltages ranging from 0 to 60 V. Various transport models have been applied to analyze the temperature dependence of the reverse current-voltage data. We suggest that Bardeen's model for a modified Schottky-like interfacial junction, that takes into account the effect of interfacial localized states, can be satisfactorily applied to describe the reverse current-voltage characteristics at bias voltages below 50 V.

Go to article

Flavonoids From The Leaves Of Impatiens Bicolor, Aurangzeb Hasan, Muhammad Nawaz Tahir Jan 2005

Flavonoids From The Leaves Of Impatiens Bicolor, Aurangzeb Hasan, Muhammad Nawaz Tahir

Turkish Journal of Chemistry

Three new flavanone glycosides, naringenin 4'-O-\beta-D-glucuronopyranoside, naringenin 4'-O-\alpha-L rham\-nopyranoside and naringenin 4'-O-\beta-D-xylopyranoside, were characterized from the leaves of Impatiens bicolor, together with 6 known glycosides: naringenin 4'-O-\beta-D-glucopyranoside, kaempferol 7-O-\beta-D-glucuronopyranoside, quercetin 3-O-\beta-D-glucopyranoside, kaempferol 5-O-\beta-D-xylopyranoside, kaempferol 3-O-\beta-D-galactopyranoside and kaempferol 7-O-\beta-D-xylopyranoside. The structures were determined by means of co-chromatography, UV, HPLC, EI-MS, FAB-MS and ^1H NMR.

Go to article

Kinetics Study Of Lead Ion Adsorption On Active Carbon, Riaz Qadeer, Sohail Akhtar Jan 2005

Kinetics Study Of Lead Ion Adsorption On Active Carbon, Riaz Qadeer, Sohail Akhtar

Turkish Journal of Chemistry

The kinetics of the adsorption of lead ions on active carbon from aqueous solutions was studied at room temperature at different lead ion concentrations (i.e. 0.1-0.5 g/L). The kinetics of the lead ion adsorption on active carbon is explained through mass transfer adsorption phenomena and the rate determining step was found to be film diffusion

Go to article

Terpenoids And Steroids From The Roots Of Salvia Blepharochlaena, Ufuk Kolak, Gülaçti Topçu, Seher Bi̇rteksöz, Gülten Ötük, Ayhan Ulubelen Jan 2005

Terpenoids And Steroids From The Roots Of Salvia Blepharochlaena, Ufuk Kolak, Gülaçti Topçu, Seher Bi̇rteksöz, Gülten Ötük, Ayhan Ulubelen

Turkish Journal of Chemistry

From the roots of Salvia blepharochlaena Hedge and Hub. Mor. 4 triterpenoids, 4 steroids, 6 diterpenoids, and an aromatic ester were isolated. The structures of these compounds were established by spectroscopic methods. Formosanolide was isolated for the first time from the genus Salvia.

Go to article

Catalytic Spectrophotometric Determination Of Chromium, Angelina Miltcheva Stoyanova Jan 2005

Catalytic Spectrophotometric Determination Of Chromium, Angelina Miltcheva Stoyanova

Turkish Journal of Chemistry

The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL^{-1}, and for chromium(VI) up to 200 ng mL^{-1}) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL^{-1} and 3.8 ng mL^{-1}, respectively. The results suggest that at the reaction conditions chromium(VI) is reduced and chromium(III) is oxidized to an intermediate oxidation state and the catalytic action of …

Go to article

Design And Characterization Of Amino And Chloro Functionalized Rhombohedral Silsesquioxanes, Ahmet Gültek, Turgay Seçki̇n, Hali̇l İbrahi̇m Adigüzel Jan 2005

Design And Characterization Of Amino And Chloro Functionalized Rhombohedral Silsesquioxanes, Ahmet Gültek, Turgay Seçki̇n, Hali̇l İbrahi̇m Adigüzel

Turkish Journal of Chemistry

A more rapid and a versatile synthetic approach for the preparation of polyhedral silsesquioxanes (POSS) by hydrolytic condensation of organosilicon monomers in the presence of a Pt catalyst was studied. The structural properties of POSS molecules were determined by X-ray powder diffraction analysis, yielding a rhombohedral unit cell with a = 11,52796Å and \alpha = 94,9754° for octaaminopropyl-POSS, and a rhombohedral unit cell with a = 11,51421Å, \alpha = 96,7214° for octachloropropyl-POSS. The activation energies were found to be 64.8, and 89.1 kJ/mol for octaaminopropyl-POSS and octachloropropyl-POSS, respectively. The products were also characterized by Fourier transform infrared spectroscopy, ^1H and …

Go to article

First Prev Next Last