Physical Sciences and Mathematics Commons^™

Sense Of Place In Virtual World Learning Environments: A Conceptual Exploration, Vipin Arora, Deepak Khazanchi

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

In this paper we conceptually explore the notion of sense of place and its potential use in the design of a ‗place for learning‘ in 3D immersive environments such as virtual worlds. We draw from earlier research in the fields of environmental psychology, social psychology and Human Computer Interaction. Our goal in this paper is to summarize the conceptual foundations that will form the basis for further empirical research aimed to inform institutions aspiring to create learning spaces in 3D virtual worlds.

Variations In Winter Surface High Pressure In The Northern Hemisphere And Climatological Impacts Of Diminishing Arctic Sea Ice, Kristen D. Fox

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

This study explores the role Arctic sea ice plays in determining mean sea level pressure and 1000 hPa temperatures during Northern Hemisphere winters while focusing on an extended period of October to March. This is accomplished by investigating two regions of the same size and comparable climatic zones and elevations in the Northern Hemisphere. A breakdown of 29 years of reanalysis data into average monthly values, anomalies, trends, and comparisons between regions serves as current data to compare with a computer model control run. Ensuring the control run accurately models current atmospheric patterns, altering the model inputs to have no …

Seasonal Variation In Terrestrial Insect Subsidies To Tropical Streams And Implications For The Diet Of Rivulus Hartii, David C. Owens

School of Natural Resources: Dissertations, Theses, and Student Research

Terrestrial invertebrates subsidize fish diets in lotic ecosystems. Seasonality strongly influences terrestrial invertebrate abundance in temperate regions and alters their delivery to streams. Seasonal changes in the tropics are characterized by distinct wet and dry periods, with marked variation in invertebrate abundance. However, little is known about how these seasonal changes affect invertebrate subsidies and their ecological consequences for tropical streams. We measured the effect of rainfall and canopy density on terrestrial invertebrate falling input, as well as seasonal variation in falling input, benthic and drifting invertebrate, and Rivulus hartii (Hart’s Rivulus) diet composition during both the wet and dry …

Development Of Nanomechanical Sensors For Environmental Contaminate Screening Using Protein Functionalized Microcantilevers, Kasey L. Hill

Doctoral Dissertations

The development of real time, label-free biosensors based on ligand-induced nanomechanical responses of microcantilevers (MCs) allows for sensitive and selective detection. High sensitivity is afforded by the MCs small dimensions. Immobilizing biomolecular recognition phases imparts selectivity from bioaffinity interactions. Biological sensors on a MC platform utilize various proteins, such as antibodies and nuclear receptors, which can be used to detect and screen for potential environmental contaminants.

The interaction between contaminants and immobilized receptors induces an apparent surface stress that leads to static bending of the MC, which is monitored by an optical beam bending technique. Biofunctionalized MCs can provide high …

Neutron Scattering Study Of The High Tc Superconductors, Jun Zhao

Doctoral Dissertations

We carried out systematic neutron scattering experiments to investigate the magnetic properties and their relationship to the high-$T_c$ superconductivity, when the materials are tuned from their antiferromagnetic (AF) parent compounds to the superconducting regime.

We observed resonance mode in the electron doped cuprate Nd$_{1.85}$Ce$_{0.15}$CuO$_4$, demonstrating that the resonance is a general phenomenon in cuprate superconductors regardless of hole- or electron-doping. In Pr$_{0.88}$LaCe$_{0.12}$CuO$_4$, the local susceptibility displays two distinct energy scales that are broadly consistent with the bosonic modes revealed by scanning tunneling microscopy experiments. These results indicate the presence of very strong electron spin excitations couplings in electron doped cuprates. …

Theoretical Models For Wall Injected Duct Flows, Tony Saad

Doctoral Dissertations

This dissertation is concerned with the mathematical modeling of the flow in a porous cylinder with a focus on applications to solid rocket motors. After discussing the historical development and major contributions to the understanding of wall injected flows, we present an inviscid rotational model for solid and hybrid rockets with arbitrary headwall injection. Then, we address the problem of pressure integration and find that for a given divergence free velocity field, unless the vorticity transport equation is identically satisfied, one cannot find an analytic expression for the pressure by direct integration of the Navier-Stokes equations. This is followed by …

Radial Heterogeneity And Surface Properties Of Columns Used In High Performance Liquid Chromatography, Jude A. Abia

Doctoral Dissertations

The radial heterogeneity of some columns used in high performance liquid chromatography (HPLC) was investigated using an on-column microelectrochemical amperometric detector. Such a detector allowed the recording of the elution profiles at different spatial positions throughout the column exit cross-section. From this, we obtain information about the radial distribution of the mobile phase velocity, column efficiency, and analyte concentration. In all cases, the results obtained show that the spatial distribution of the mobile phase velocity does not follow a piston-flow behavior but exhibits radial heterogeneity with differences not exceeding 5% between the center and wall regions of any column. The …

A New Screening Methodology For Mixture Experiments, Maria Weese

Doctoral Dissertations

Many materials we use in daily life are comprised of a mixture; plastics, gasoline, food, medicine, etc. Mixture experiments, where factors are proportions of components and the response depends only on the relative proportions of the components, are an integral part of product development and improvement. However, when the number of components is large and there are complex constraints, experimentation can be a daunting task. We study screening methods in a mixture setting using the framework of the Cox mixture model [1]. We exploit the easy interpretation of the parameters in the Cox mixture model and develop methods for screening …

Investigations Of The Dynamical Response In Solids By Time-Dependent Density-Functional Theory, Qinghong Kou

Doctoral Dissertations

The present dissertation studies a joint theoretical-experimental investigation of the dynamical structure factor of wide-gap insulators, using lithium-fluoride as a prototype. Ground-state (energy bands and electron densities) was calculated using Linear Augmented Plane Wave (LAPW) method and local density approximation (LDA) of density functional theory (DFT). Ab-initio principal is applied to obtain a realistic description of the band structure, which is central to the current research in the condensed matter physics. Dynamical response function has been evaluated within time-dependent density functional theory (DFT) with an adiabatic approximation (TDLDA), for the exchange-correlation kernel. Our TDLDA spectra contain one adjustable parameter: a …

Development Of A Systematic And Practical Methodology For The Design Of Vehicles Semi-Active Suspension Control System, Hamidreza Bolandhemmat, Christopher M. Clark, Farid Golnaraghi

Computer Science and Software Engineering

In this paper, a novel systematic and practical methodology is presented for design of vehicle semi-active suspension systems. Typically, the semi-active control strategies developed to improve vehicle ride comfort and stability have a switching nature. This makes the design of the controlled suspension systems difficult and highly dependent on an extensive trial-and-error process. The proposed methodology maps the discontinuous control system model to a continuous linear region, where all the time and frequency design techniques, established in the conventional control system theory, can be applied. If the semi-active control system is designed to satisfy some ride and stability requirements, an …

New Standards For Providing Meteorological And Hydrographic Information Via Ais Application-Specific Messages, Lee Alexander, Schwehr Kurt

Center for Coastal and Ocean Mapping

AIS Application-specific messages transmitted in binary format will be increasingly used to digitally communicate maritime safety/security information between participating vessels and shore stations. This includes time-sensitive meteorological and hydrographic information that is critical for safe vessel transits and efficient ports/waterways management. IMO recently completed a new Safety-of-Navigation Circular (SN/Circ.) that includes a number of meteorologi-cal and hydrographic message applications and data parameters. In conjunction with the development of a new SN/Circ., IMO will establish an International Application (IA) Register for AIS Application-Specific Messages. IALA plans to establish a similar register for regional appli-cations. While there are no specific standards for …

Spinning Tubes: An Authentic Research Experience In A Three-Hour Laboratory, Arnold E. Sikkema, Steven D. Steenwyk, John Zwart

Faculty Work Comprehensive List

We discuss a three-hour laboratory that is a microcosm of physics research, starting with the discovery of an intriguing phenomenon, and including participation in “research conferences” and the interplay of theory and experiment. Students are given a small segment of PVC pipe marked at opposite ends with different symbols and asked to observe what happens when the pipe is placed on a horizontal surface and one end is pushed downward by a finger to initiate a rotation. Most students immediately recognize that the symbol at one end is visible while the other is not, and set about trying to understand …

Galactic Cosmic Ray Radiation Hazard In The Unusual Extended Solar Minimum Between Solar Cycles 23 And 24, Nathan A. Schwadron, A. J. Boyd, K. Kozarev, M. Golightly, Harlan E. Spence, L. W. Townsend, M. Owens

Physics & Astronomy

[1] Galactic cosmic rays (GCRs) are extremely difficult to shield against and pose one of the most severe long-term hazards for human exploration of space. The recent solar minimum between solar cycles 23 and 24 shows a prolonged period of reduced solar activity and low interplanetary magnetic field strengths. As a result, the modulation of GCRs is very weak, and the fluxes of GCRs are near their highest levels in the last 25 years in the fall of 2009. Here we explore the dose rates of GCRs in the current prolonged solar minimum and make predictions for the Lunar Reconnaissance …

On Directionally Dependent Subdifferentials, Ivan Ginchev, Boris S. Mordukhovich

Mathematics Research Reports

In this paper directionally contextual concepts of variational analysis, based on dual-space constructions similar to those in [4, 5], are introduced and studied. As an illustration of their usefulness, necessary and also sufficient optimality conditions in terms of directioual subdifferentials are established, and it is shown that they can be effective in the situations where known optimality conditions in terms of nondirectional subdifferentials fail.

Satellite Motion In A Non-Singular Gravitational Potential, Ioannis Haranas, Spiros Pagiatakis

Physics and Computer Science Faculty Publications

We study the effects of a non-singular gravitational potential on satellite orbits by deriving the corresponding time rates of change of its orbital elements. This is achieved by expanding the non-singular potential into power series up to second order. This series contains three terms, the first been the Newtonian potential and the other two, here R₁ (first order term) and R₂ (second order term), express deviations of the singular potential from the Newtonian. These deviations from the Newtonian potential are taken as disturbing potential terms in the Lagrange planetary equations that provide the time rates of change of …

Focusing Of A Femtosecond Vortex Light Pulse Through A High Numerical Aperture Objective, Baosuan Chen, Jixiong Pu, Olga Korotkova

Physics Articles and Papers

We investigate the focusing properties of a femtosecond vortex light pulse focused by a high numerical aperture objective. By using the Richards-Wolf vectorial diffraction method, the intensity distribution, the velocity variation and the orbital angular momentum near the focus are studied in great detail. We have discovered that the femtosecond vortex light pulse can travel at various speeds, that is, slower or faster than light with a tight focusing system. Moreover, we have found that the numerical aperture of the focusing objective and the duration of the vortex light pulse will influence the orbital angular momentum distribution in the focused …

Second-Order Statistics Of Stochastic Electromagnetic Beams Propagating Through Non-Kolmogorov Turbulence, Elena Shchepakina, Olga Korotkova

Physics Articles and Papers

We present a detailed investigation, qualitative and quantitative, on how the atmospheric turbulence with a non-Kolmogorov power spectrum affects the major statistics of stochastic electromagnetic beams, such as the spectral composition and the states of coherence and polarization. We suggest a detailed survey on how these properties evolve on propagation of beams generated by electromagnetic Gaussian Schell-model sources, depending on the fractal constant α of the atmospheric power spectrum.

Degree Of Paraxiality Of A Partially Coherent Field, Fei Wang, Yangjian Cai, Olga Korotkova

Physics Articles and Papers

We extend the concept of the degree of paraxiality, introduced recently for monochromatic fields, to the domain of stochastic fields. As an example we analytically evaluate the degree of paraxiality for a broad class of model stochastic fields, the Gaussian Schell-model fields, without and with truncation and twist phase. The dependence of the degree of paraxiality on the size and the state of coherence of the source as well as on the truncation parameter and the magnitude of twist phase is analyzed by a number of numerical examples.

Prospective Type Ia Supernova Surveys From Dome A, A. Kim, A. Bonissent, Jodi L. Christiansen, A. Ealet, L. Faccioli, L. Gladney, G. Kushner, E. Linder, C. Stoughton, L. Wang

Physics

Dome A, the highest plateau in Antarctica, is being developed as a site for an astronomical observatory. The planned telescopes and instrumentation and the unique site characteristics are conducive toward Type Ia supernova surveys for cosmology. A self-contained search and survey over five years can yield a spectro-photometric time series of ∼1000 z < 0.08 supernovae. These can serve to anchor the Hubble diagram and quantify the relationship between luminosities and heterogeneities within the Type Ia supernova class, reducing systematics. Larger aperture (>4-m) telescopes are capable of discovering supernovae shortly after explosion out to z ∼ 3. These can be fed to space telescopes, and can isolate systematics and extend the redshift range over which we measure the expansion history of the universe.

Certain Two-Parameter Representations Of The Lie Algebra Sl(2,C), Scott Sidoli

Mathematics and Statistics

Classical Lie algebras, like sl(2,C) can be represented using differential operators that act on polynomial space. These operators will take a different form when they are used on the space of polynomials of several variables and when the differentials are taken to be of higher order. We recall some known realizations and discuss possible deformations. In our two-parameter case we describe decomposition into indecomposable components.

Rapid Cooling Of The Neutron Star In The Quiescent Super-Eddington Transient Xte J1701-462, Joel K. Fridriksson, Jeroen Homan, Rudy Wijnands, Mariano Méndez, Diego Altamirano, Edward M. Cackett, Edward F. Brown, Tomaso M. Belloni, Nathalie Degenaar, Walter H. G. Lewin

Physics and Astronomy Faculty Research Publications

We present Rossi X-Ray Timing Explorer and Swift observations made during the final three weeks of the 2006-2007 outburst of the super-Eddington neutron star (NS) transient XTE J1701-462, as well as Chandra and XMM-Newton observations covering the first sime800 days of the subsequent quiescent phase. The source transitioned quickly from active accretion to quiescence, with the luminosity dropping by over 3 orders of magnitude in sime13 days. The spectra obtained during quiescence exhibit both a thermal component, presumed to originate in emission from the NS surface, and a non-thermal component of uncertain origin, which has shown large and irregular variability. …

Using Advancements In Cable-Trapping To Overcome Barriers To Furbearer Management In The United States, Stephen Vantassel, Tim L. Hiller, Kelly D. J. Powell, Scott E. Hygnstrom

School of Natural Resources: Faculty Publications

Harvest of furbearers through trapping has been challenged by anti-trapping organizations for centuries, with organizational goals often including prohibition of all forms of trapping. Challenges to trapping may also include dissention among state wildlife agencies, pro-hunting organizations, and pro-trapping organizations. Despite recent efforts by anti-trapping organizations and occasional dissention among consumptive-use groups, national trends in snaring regulations included less restrictive regulations through time. This positive trend may offer opportunities for state wildlife agencies and pro-trapping organizations to enhance the public image of trapping, increase recruitment of trappers, and reverse the increasing trend of wildlife damage and associated costs. We offer …

Winter Ecology Of Buggy Creek Virus (Togaviridae, Alphavirus) In The Central Great Plains, Charles R. Brown, Stephanie A. Strickler, Amy T. Moore, Sarah A. Knutie, Abinash Padhi, Mary Bomberger Brown, Ginger R. Young, Valerie A. O'Brien, Jerome E. Foster, Nicholas Komar

School of Natural Resources: Faculty Publications

A largely unanswered question in the study of arboviruses is the extent to which virus can overwinter in adult vectors during the cold winter months and resume the transmission cycle in summer. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an unusual arbovirus that is vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) and amplified by the ectoparasitic bug’s main avian hosts, the migratory cliff swallow (Petrochelidon pyrrhonota) and resident house sparrow (Passer domesticus). Bugs are sedentary and overwinter in the swallows’ mud nests. We evaluated the prevalence of BCRV and extent of …

Sfa Weather Station-May 2010, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University

Weather Station Data

No abstract provided.

Fisher Was Right, Ronald C. Serlin

Journal of Modern Applied Statistical Methods

Invited address presented to the Educational Statistician’s Special Interest Group at the annual meeting of the American Educational Research Association, Denver, May 1, 2010.

Inferences About The Population Mean: Empirical Likelihood Versus Bootstrap-T, Rand R. Wilcox

Journal of Modern Applied Statistical Methods

The problem of making inferences about the population mean, μ, is considered. Known theoretical results suggest that a Bartlett corrected empirical likelihood method is preferable to two basic bootstrap techniques: a symmetric two-sided bootstrap-t and an equal-tailed bootstrap-t. However, simulations in this study indicate that, when the sample size is small, these two bootstrap methods are generally better in terms of Type I errors and probability coverage. As the sample size increases, situations are found where the Bartlett corrected empirical likelihood method performs better than the equal-tailed bootstrap-t, but the symmetric bootstrap-t gives the best results. None of the four …

The Influence Of Data Generation On Simulation Study Results: Tests Of Mean Differences, Tim Moses, Alan Klockars

Journal of Modern Applied Statistical Methods

Type I error and power of the standard independent samples t-test were compared with the trimmed and Winsorized t-test with respect to continuous distributions and various discrete distributions known to occur in applied data. The continuous and discrete distributions were generated with similar levels of skew and kurtosis but the discrete distributions had a variety of structural features not reflected in the continuous distributions. The results showed that the Type I error rates of the t-tests were not seriously affected, but the power rate of the trimmed and Winsorized t-test varied greatly across the considered distributions.

The Effectiveness Of Stepwise Discriminant Analysis As A Post Hoc Procedure To A Significant Manova, Erik L. Heiny, Daniel J. Mundform

Journal of Modern Applied Statistical Methods

The effectiveness of SWDA as a post hoc procedure in a two-way MANOVA was examined using various numbers of dependent variables, sample sizes, effect sizes, correlation structures, and significance levels. The procedure did not work well in general except with small numbers of variables, larger samples and low correlations between variables.

The Small-Sample Efficiency Of Some Recently Proposed Multivariate Measures Of Location, Marie Ng, Rand R. Wilcox

Journal of Modern Applied Statistical Methods

Numerous multivariate robust measures of location have been proposed and many have been found to be unsatisfactory in terms of their small-sample efficiency. Several new measures of location have recently been derived, however, nothing is known about their small-sample efficiency or how they compare to the sample mean under normality. This research compared the efficiency for p = 2, 5, and 8 with sample sizes n = 20 and 50 for p-variate data. Although previous studies indicate that so-called skipped estimators are efficient, this study found that variations of this approach can perform poorly when n is small and p …

Model Based Vs. Model Independent Tests For Cross-Correlation, H.E.T. Holgersson, Peter S. Karlsson

Journal of Modern Applied Statistical Methods

This article discusses the issue of whether cross correlation should be tested by model dependent or model independent methods. Several different tests are proposed and their main properties are investigated analytically and with simulations. It is argued that model independent tests should be used in applied work.