Physical Sciences and Mathematics Commons^™

Ichnology Of An Intertidal Carbonate Sand Flat: Pigeon Creek, San Salvador Island, Bahamas, H. Allen Curran, Austin B. Williams

Geosciences: Faculty Publications

Reprinted from: James L. Carew (ed.), May 30–June 3, 1996, Proceedings of the 8th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Bahamian Field Station.

Bahamian Sangamonian Coral Reefs And Sea-Level Change, Brian White, H. Allen Curran, Mark A. Wilson

Geosciences: Faculty Publications

Reprinted from James L. Carew (ed.) May 30–June 3, 1996, Proceedings of the 8th Symposium on the Geology of the Bahamas and Other Carbonate Regions: Bahamian Field Station, San Salvador, Bahamas.

The Development And Use Of The Secure Electronic Transaction (Set) Protocol On The Internet, Damon James Whyte

Theses : Honours

While still in its infancy, Electronic Commerce is growing at an exponential rate each year (Walson, 1997. p.53). Although few doubt that such growth will only continue in years to come, many people still have serious reservations about the levels of security offered by currently available applications for conducting such trade. This thesis identifies some of the key areas of concern regarding Electronic Commerce on the lnternet, and looks at the ways in which the Secure Electronic Transaction (SET) model, proposed by Mastercard and Visa, succeeds or fails in addressing these concerns. It identifies and describes the key dements and …

Wiyn Data Distribution And Archiving, Rob Seaman, Ted Von Hippel

Publications

The NOAO/IRAF Save the Bits archive has been operating for over three years at Kitt Peak National Observatory and at the National Solar Observatory's nighttime program. Since that time, the W. M. Keck Observatory and the Cerro Tololo Inter-American Observatory have also adopted the software. These first generation Save the Bits installations rely on Exabyte tapes as the archival medium, typically using pairs of drives to produce duplicate copies of the data for heightened protection against data loss. The upgrade of Save the Bits that is currently in progress to support writable CD-R drives is discussed. In addition to another …

Resolution Of Local Inconsistency In Identification, Douglas Ray Anderson, Martin Zwick

Complex Systems Faculty Publications and Presentations

This paper reports an algorithm for the resolution of local inconsistency in information-theoretic identification. This problem was first pointed out by Klir as an important research area in reconstructability analysis. Local inconsistency commonly arises when an attempt is made to integrate multiple data sources, i.e., contingency tables, which have differing common margins. For example, if one ha)s an AB table and a BC table, the B margins obtained from the two tables may disagree. If the disagreement can be assigned to sampling error, then one can arrive at a compromise B margin, adjust the original AB and BC tables to …

Petrogenesis Of Mid-Proterozoic Granitic Magmas: Examples From Central And West Texas, Diane R. Smith, C. Barnes, W. Shannon, R. Roback, E. James

Earth and Environmental Geosciences Faculty Research

Circa 1.1 Ga granitic magmatism in Texas was manifested as two compositional groups: (1) the 1.12 Ga Red Bluff granitic suite in west Texas; and (2) 1.12-1.07 Ga granites of the Llano uplift of central Texas. Both suites share some characteristics typical of 'anorogenic' granites (e.g. potassium- and iron-rich bulk compositions, Fe-rich hydrous silicates, emplacement conditions involving low oxygen fugacities and water contents) and exhibit similar isotopic characteristics. However, rock associations, mineral chemistries, and trace element compositions of the two suites are distinct and no single petrogenetic model for the two suites is possible.

The Red Bluff granitic suite includes …

Eigenfunction And Harmonic Function Estimates In Domains With Horns And Cusps, Michael Cranston, Yi Li

Mathematics and Statistics Faculty Publications

No abstract provided.

Preparation Of Powder Precursors And Evaporation Of Photoconductive Indium Sulfide Films, Chris Barber, Robert Engelken, Brandon Kemp, Wasim Aleem, Imran Khan, Chris Edrington, Michael Buck, Clayton Workman, Anup Thapa, Tom Jakobs

Journal of the Arkansas Academy of Science

We have demonstrated significant photoconductance in indium sulfide thin films prepared by thermal vacuum evaporation ofIn2$3 powders synthesized in-house by chemical precipitation ofInCl3 or In(CH3COO)3, and (NH4)2S or Na2S. The Delta G lambda/Gdark values have been as high as 0.1 in the initial unoptimized films. Excess sulfur (via a mixture of polysulfide and sulfide ions in the synthesis bath) appears to be important in achieving reproducible and large photoconductivities. In2S3 is particularly attractive as a lower toxicity alternative to CdS in optoelectronic applications such as photovoltaic and photoconductive cells.

Coplanarity Test For Selecting A Pair Of Charged-Particle Tracks Resulting From A Single Neutral-Particle Decay, Edwin S. Braithwaite, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

It is hard to determine directly the position of a neutral subatomic particle, but when such a particle decays into a pair of charged particles, it is easy to determine the positions of the charged decay particles and thereby infer the position of the parent particle at the time of its decay. A minimum of two coordinate points for each of the two decay particles is needed to reconstruct the position of the parent vertex. The mathematics of the reconstruction process is inherently interesting, and it can be used to demonstrate to students the utility of some of the most …

Electron Shock Waves: Effect Of Current On Electron Temperature And Density, Mostafa Hemmati, Mathues Shane Doss

Journal of the Arkansas Academy of Science

In our attempt to find analytical solutions for breakdown waves, we employ a set of three-component fluid equations. In addition to reporting the method of integration of electron fluid dynamical equations through the dynamical transition region (sheath region), the wave profile for ionization rate, electron number density and electron temperature inside the sheath will be discussed. Also, the effect of the current on electron temperature, electron number density and ionization rate will be reported.

Acidity Studies Of Deuterated Acids And Bases Commonly Used As Buffers In Nmr Studies, Rose M. Mcconnell, Walter E. Godwin, Brant Stanley, M. Shane Green

Journal of the Arkansas Academy of Science

Structure based drug development is currently considered to be an important strategy for drug discovery. This strategy requires that critical knowledge of the three dimensional binding site on receptor molecules be known. NMR studies are frequently employed to ascertain important structural data on individual proteins as well as complexes of proteins with ligands. Deuterium labeled acids and bases are frequently used as buffers in deuterium oxide solutions for NMR studies on the structural conformations of bioactive molecules. Since pH is an important factor in any study of the conformational and stereochemical aspects of biologically active molecules, deuterated buffers are an …

Artificial Neural Networks Used To Predict Electrical Properties Of Polymers, Sanjay K. Mitra, Qing Luo, Jerry A. Darsey

Journal of the Arkansas Academy of Science

The ability to predict properties of molecules prior to their synthesis can be of great importance in optimizing their design. Substantial savings in time as well as cost can be achieved if some desired properties can be predicted prior to the synthesis of the molecule. The outer orbitals of a molecule are primarily responsible for many different properties of the molecules. These outer orbital parameters can be utilized by an intelligent computing system like an Artificial Neural Network to extract necessary knowledge about the properties of the molecule. An Artificial Neural Network was trained to extract electrical parameters of several …

Discovery Of Fossil Cretaceous Bird In Southwest Arkansas, Leo Carson Davis, Kathie Harris

Journal of the Arkansas Academy of Science

No abstract provided.

New Studies Of Polyfuran And Polymers Of 3-Substituted Furan Rings, Rose M. Mcconnell, Walter E. Godwin, Bradley Phillips

Journal of the Arkansas Academy of Science

No abstract provided.

Reductive Dechlorinatin Of A 2-Chloronicotinic Acid Under Finkelstein Conditions, Frank L. Setliff, Leslie B. Coop

Journal of the Arkansas Academy of Science

No abstract provided.

Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton

Chemistry Faculty Publications

Novel β-polyfluoroalkoxy vinamidinium salts 3 and/or 4 were synthesized in good yields by the reaction of N-(2- polyfluoroalkoxy-3 ,3-difluoro-1-propenyI)trimethylammonium iodides (2), prepared from N-(2,3,3-trifluoro-1-propenyl)trimethylammonium iodide (1), with secondary amines in MeCN at 70 °C for 1 h. The salts were also obtainable in comparable yields by the one-pot reaction of 1 with sodium polyfluoroalkoxide followed by treatment with amines.

Age And Growth Of Larval And Juvenile Atlantic Croaker, Micropogonias Undulatus, From The Middle Atlantic Bight And Estuarine Waters Of Virginia, Stephen W. Nixon, Cynthia M. Jones

OES Faculty Publications

Sagittal otoliths were used to determine age and growth of 605 larval and juvenile Atlantic croaker, Micropogonias undulatus, collected in the Middle Atlantic Bight and estuarine waters of Virginia. This study is the first to use age-based analysis for young Atlantic croaker collected in this region. A Laird-Gompertz model (r2=0.95) was used to describe the growth of Atlantic croaker up to 65 mm standard length (SL) and 142 days (t): SL((t)) = 2.657 exp (4.656 [1-exp (-0.0081t)]); where SL((t)) = standard length at day t. Spatial and temporal patterns in the size and age of Atlantic croaker showed a …

N-Methylbenzothiazole-2(3H)-Selone, C8H7Nsse, Steinar Husebye, Sergey V. Lindeman, Martin D. Rudd

Chemistry Faculty Research and Publications

The crystal structure of N-methyl1,3-benzothiazole-2(3H)-selone, (mbts) has been studied to estimate the changes in the molecular geometry of the mbts ligand upon coordination. Hypervalent complexes of mbts with Te^II and I^I have been studied by us previously. A significant elongation of the Se=C bond [from 1.817 (7) in mbts to 1.85-1.88 Å in the complexes] was found, but there were no significant changes in the other geometric parameters of the ligand. The only other bond-length decrease of note was for SeC-NMe [from 1.35 (1) in mbts to 1.32-1.34 Å in the complexes]. Thus, only the …

Hexakis(Dimethylformamide)Bis(Hexaphenylcyclohexasiloxanehexaolato)Hexacopper(Ii) Dimethylformamide Solvate, Sergey V. Lindeman, Olga I. Shchegolikhina, Yulia A. Molodtsova, Alexandr A. Zhdanov

Chemistry Faculty Research and Publications

The sandwich-like title complex, hexakis(dimethylformamide)-1O,2O,3O,4O,5O,6O-bis[2,4,6,8,10,12-hexaphenylsiloxane-2,4,6,8,10,12-hexaolato(6-)-1:2²O¹,2:3²O²,3:4²O³,- 4:5²O⁴,5:6²O⁵,1:6²O⁶]hexacopper(II) tetrakis(dimethylformamide) solvate, [Cu₆(C₃H₇NO)₆{(C₆H₅)₆O₁₂Si₆}₂].4C₃H₇NO, is comprised of two regular crown-shaped macrocyclic hexadentate organosiloxanolate ligands chelating a flat Cu₆ hexagon, as in the ethanol-solvated analogue investigated previously. The title complex has a more distorted shape …

Preparation And Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Applications To Organic Synthesis, William A. Donaldson

Chemistry Faculty Research and Publications

No abstract provided.

Femtosecond Photoemission Study Of Ultrafast Electron Dynamics On Cu(100), J. Cao, Y. Gao, R. J. D. Miller, Hani E. Elsayed-Ali, D. A. Mantell

Electrical & Computer Engineering Faculty Publications

The energy dependence of the relaxation of photoexcited electrons in copper was measured using femtosecond time-resolved photoemission spectroscopy to within 0.3 eV above the Fermi level. By performing lifetime measurements under different surface conditions, several surface dynamical processes were investigated. In particular, an anomalous long lifetime feature, which cannot be explained with Fermi-liquid theory, was observed in the lifetime-energy curve. This feature was found originating from the photoexcitation of the strongly localized Cu 3d electrons. ©1997 American Physical Society

Microwave Plasma Chemical Vapor Deposited Diamond Tips For Scanning Tunneling Microscopy, Sacharia Albin, Jianli Zheng, John B. Cooper, Weihai Fu, Arnel C. Lavarias

Electrical & Computer Engineering Faculty Publications

Diamond microparticles were grown on etched tungsten wires using a microwave plasma-assisted chemical vapor deposition process. The apexes on cubo-octahedral particles bound by {100} and {111} facets were effectively used as tunneling tips for scanning tunneling microscopy. The atomically resolved surface image of highly oriented pyrolytic graphite was acquired. Tunneling characteristics revealed a higher electron emission from the diamond tips than that from the platinum–iridium tips. The same diamond tips were used to produce surface indentation and its image. © 1997 American Institute of Physics.

Faster Ray Tracing Using Adaptive Grids, Thomas W. Sederberg, Krysztof S. Klimaszewski

Faculty Publications

A new hybrid approach is presented which outperforms the regular grid technique in scenes with highly irregular object distributions by a factor of hundreds, and combined with an area interpolator, by a factor of thousands. Much has been said about scene independence of different acceleration techniques and the alleged superiority of one approach over another. Several theoretical and practical studies conducted in the past have led to the same conclusion: a space partitioning method that allows the fastest rendering of one scene often fails with another. Specialization may be the answer. This has always been pursued, consciously or not, in …

On The Dynamic Behaviour Of A Thermoviscoelastic Body In Frictional Contact With A Rigid Obstacle, Kenneth Kuttler, K. T. Andrews, M. Shillor

Faculty Publications

We consider the dynamic behaviour of a thermoviscoelastic body which may come into frictional contact with a rigid obstacle. The frictional contact is modelled by general contact and friction laws which include as special cases the power law normal compliance condition and the corresponding generalization of Coulomb's law of dry friction. The stress-strain constitutive relation is assumed to be of Kelvin-Voigt type and the frictional heat generation on the contact surface is taken into account. In this setting we establish the existence of a solution to a weak version of the energy-elasticity system which consists of a parabolic equation coupled …

Damped Diocotron Quasi-Modes Of Non-Neutral Plasmas And Inviscid Fluids, S. Neil Rasband, Ross L. Spencer

Faculty Publications

Computations of damped diocotron oscillations (quasi-modes) are described for non-neutral plasmas and inviscid fluids. The numerical method implements a suggestion made by Briggs, Daugherty, and Levy some 25 years ago [Phys. Fluids 13, 421 (1970)] to push the branch line that forms the continuum into the complex w-plane by solving the mode equation in the complex r-plane. For the special case of power-law density profiles the calculation finds the same quasi-mode frequencies found recently by Corngold [Phys. Plasmas 2, 620 (1995)]. It is found that the feature of the continuum eigenfunctions which indicates the presence of a nearby quasi-mode is …

Improved Heterogeneous Distance Functions, Tony R. Martinez, D. Randall Wilson

Faculty Publications

Instance-based learning techniques typically handle continuous and linear input values well, but often do not handle nominal input attributes appropriately. The Value Difference Metric (VDM) was designed to find reasonable distance values between nominal attribute values, but it largely ignores continuous attributes, requiring discretization to map continuous values into nominal values. This paper proposes three new heterogeneous distance functions, called the Heterogeneous Value Difference Metric (HVDM), the Interpolated Value Difference Metric (IVDM), and the Windowed Value Difference Metric (WVDM). These new distance functions are designed to handle applications with nominal attributes, continuous attributes, or both. In experiments on 48 applications …

Monotone Iterations For Differential Equations With A Parameter, Tadeusz Jankowski, V. Lakshmikantham

Mathematics and System Engineering Faculty Publications

Consider the problem {y′(t)=f(t,y(t),λ),t∈J=[0,b],y(0)=k0,G(y,λ)=0. Employing the method of upper and lower solutions and the monotone iterative technique, existence of extremal solutions for the above equation are proved.

Turbulence Modeling Of The Toroidal Wall Heat Load Due To Shear Flows Over Cavities In The Neutral Gas Blanket Divertor Regime, George Vahala, Linda L. Vahala, Joseph Morrison

Electrical & Computer Engineering Faculty Publications

Heat loads to the target plate in reactor tokamaks are estimated to be orders of magnitude higher than those that can be withstood by known materials. In regimes of plasma detachment, there is strong evidence that plasma recombination occurs near the divertor plate, leading to a cold neutral gas blanket. Because of the strong coupling between the plasma and the neutrals within the divertor region, there is significant neutral flows along field lines up to Mach 1.2 and Reynolds numbers over 1000. The effects of three dimensional (3D) neutral turbulence within the gas blanket on heat deposition to the toroidal …

Randomised Shuffle And Applied Misinformation: An Enhanced Model For Contact-Based Smart-Card Serial Data Transfer, Michael Collins

Theses: Doctorates and Masters

Contact-based smart-cards, which comply to the International Standard IS0-7816, communicate with their associated read/write machines via a single bi-directional serial link. This link is easy to monitor with inexpensive equipment and resources, enabling captured data to be removed for later examination. In many contact-based smart-cards the logical abilities are provided by eight-bit microcontroller units (MCU) which are slow at performing effective cryptographic functions. Consequently, for expediency, much data may be transferred in plain-text across the vulnerable communications link, further easing an eavesdropper's task. Practitioners in military communications protect transmitted information by varying a link's carrier frequency in an apparently random …

An Approach To Display Layout Of Dynamic Windows, Nihar Trivedi

Theses: Doctorates and Masters

The development of windows based user interface has introduced a new dimension to the field of human computer interaction. Now a user is able to perform multiple tasks at a time, often switching from one task to another. However windows environment also imposes the burden of manual windows management on the user. Several studies have suggested that manual window management is an unproductive chore often resulting in clutter and confusion on the display screen. Therefore we need a automatic windows layout generator to free the user to perform other useful tasks. This thesis introduces SPORDAC {Shadow Propagation for Overlap Removal …