Physical Sciences and Mathematics Commons^™

Final Report: Data And Assessment (Full Report), Horsley Witten Group, Inc.

Phase I Final Report

No abstract provided.

Asymptotic Behavior Of Linearized Viscoelastic Flow Problem, Yinnian He, Yi Li

Mathematics and Statistics Faculty Publications

In this article, we provide some asymptotic behaviors of linearized viscoelastic flows in a general two-dimensional domain with certain parameters small and the time variable large.

Nonlinear Magneto-Optic Polarization Rotation With Intense Laser Fields, Paul S. Hsu, Anil K. Patnaik, George R. Welch

Physics Faculty Publications

We have studied the nonlinear Faraday effect with intense linear polarized light in an optically thick atomic rubidium vapor. We demonstrate that the polarization rotation rate (rotation angle per unit magnetic field, in the limit of low field) has a maximum value as the intensity and density are increased. We also show that the optimal sensitivity of an optical magnetometer based on this system reaches a saturation value as the intensity and density are increased.

Abrupt Transition From A Free, Repulsive To A Condensed, Attractive Dna Phase, Induced By Multivalent Polyamine Cations, Xiangyun Qiu, Kurt Andresen, Jessica S. Lamb, Lisa W. Kwok, Lois Pollack

Physics and Astronomy Faculty Publications

We have investigated the energetics of DNA condensation by multivalent polyamine cations. Solution small angle x-ray scattering was used to monitor interactions between short 25 base pair dsDNA strands in the free supernatant DNA phase that coexists with the condensed DNA phase. Interestingly, when tetravalent spermine is used, significant inter-DNA repulsion is observed in the free phase, in contrast with the presumed inter-DNA attraction in the coexisting condensed phase. DNA condensation thus appears to be a discrete, first-order-like, transition from a repulsive gaseous to an attractive condensed solid phase, in accord with the reported all-or-none condensation of giant DNA. We …

Ua35/1 Doers & Deeds Vol. 7, No. 8, Wku Provost

WKU Archives Records

Newsletter created by the WKU Provost & Vice President of Academic Affairs to highlight the activities of faculty, staff and alumni.

Live Release Of A Bigeye Sand Tiger Odontaspis Noronhai (Elasmobranchii: Lamniformes) In The Western North Atlantic Ocean, David W. Kerstetter, Mae Taylor

Marine & Environmental Sciences Faculty Articles

No abstract provided.

Estimating Explanatory Power In A Simple Regression Model Via Smoothers, Rand R. Wilcox

Journal of Modern Applied Statistical Methods

Consider the regression model Y = γ(X) + ε , where γ(X) is some conditional measure of location associated with Y , given X. Let Υ̂ be some estimate of Y, given X, and let τ² (Y) be some measure of variation. Explanatory power is η² = τ² (Υ̂) /τ²(Y) . When γ(X) = β₀ + β₁X and τ²(Y) is the variance of Y , η² = ρ² , …

Multi-Group Confirmatory Factor Analysis For Testing Measurement Invariance In Mixed Item Format Data, Kim H. Koh, Bruno D. Zumbo

Journal of Modern Applied Statistical Methods

This simulation study investigated the empirical Type I error rates of using the maximum likelihood estimation method and Pearson covariance matrix for multi-group confirmatory factor analysis (MGCFA) of full and strong measurement invariance hypotheses with mixed item format data that are ordinal in nature. The results indicate that mixed item formats and sample size combinations do not result in inflated empirical Type I error rates for rejecting the true measurement invariance hypotheses. Therefore, although the common methods are in a sense sub-optimal, they don’t lead to researchers claiming that measures are functioning differently across groups – i.e., a lack of …

An Optimum Allocation With A Family Of Estimators Using Auxiliary Information In Sample Survey, Gajendra K. Vishwakarma, Housila P. Singh

Journal of Modern Applied Statistical Methods

The problem of obtaining optimum allocation using auxiliary information in stratified random sampling. An optimum allocation with a family of estimators is obtained and its efficiency is compared with that of Neyman allocation based on Srivastava (1971) class of estimators and the optimum allocation suggested by Zaidi et al., (1989). It is shown that the proposed allocation is better in the sense having smaller variance compared to other optimum allocation.

Data Mining Ceo Compensation, Susan M. Adams, Atul Gupta, Dominique M. Haughton, John D. Leeth

Journal of Modern Applied Statistical Methods

The need to pre-specify expected interactions between variables is an issue in multiple regression. Theoretical and practical considerations make it impossible to pre-specify all possible interactions. The functional form of the dependent variable on the predictors is unknown in many cases. Two ways are described in which the data mining technique Multivariate Adaptive Regression Splines (MARS) can be utilized: first, to obtain possible improvements in model specification, and second, to test for the robustness of findings from a regression analysis. An empirical illustration is provided to show how MARS can be used for both purposes.

On Some Properties Of Quasi-Negative-Binomial Distribution And Its Applications, Anwar Hassan, Sheikh Bilal

Journal of Modern Applied Statistical Methods

The quasi-negative-binomial distribution was applied to queuing theory for determining the distribution of total number of customers served before the queue vanishes under certain assumptions. Some structural properties (probability generating function, convolution, mode and recurrence relation) for the moments of quasi-negative-binomial distribution are discussed. The distribution’s characterization and its relation with other distributions were investigated. A computer program was developed using R to obtain ML estimates and the distribution was fitted to some observed sets of data to test its goodness of fit.

A Neural Network Model For A Hierarchical Spatio-Temporal Memory, Kiruthika Ramanathan, Luping Shi, Jianming Li, Kian Guan Lim, Zhi Ping Ang, Chong Chong Tow

Research Collection School Of Computing and Information Systems

The architecture of the human cortex is uniform and hierarchical in nature. In this paper, we build upon works on hierarchical classification systems that model the cortex to develop a neural network representation for a hierarchical spatio-temporal memory (HST-M) system. The system implements spatial and temporal processing using neural network architectures. We have tested the algorithms developed against both the MLP and the Hierarchical Temporal Memory algorithms. Our results show definite improvement over MLP and are comparable to the performance of HTM.

Three-Dimensional Modeling Of The Plasma Arc In Arc Welding, Gu Xu, J. Hu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most previous three-dimensional modeling on gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) focuses on the weld pool dynamics and assumes the two-dimensional axisymmetric Gaussian distributions for plasma arc pressure and heat flux. In this article, a three-dimensional plasma arc model is developed, and the distributions of velocity, pressure, temperature, current density, and magnetic field of the plasma arc are calculated by solving the conservation equations of mass, momentum, and energy, as well as part of the Maxwell's equations. This three-dimensional model can be used to study the nonaxisymmetric plasma arc caused by external perturbations such as …

New (E,2e) Studies Of Atomic And Molecular Targets, E. M. Staicu-Casagrande, A. Naja, A. Lahmam-Bennani, A. S. Kheifets, Don H. Madison, B. Joulakian

Physics Faculty Research & Creative Works

We report new coplanar (e,2e) measurements characterised by large energy transfer and close to minimum momentum transfer from the projectile to the target. Ionisation of the two-electron targets He and H₂ is investigated under these particular kinematics. The experimental data are compared with the predictions of the most elaborate theoretical models. The obtained good agreement motivated us to extend our research to the case of more complex targets such as Ar. Comparison with the most elaborate models in the case of multi-electron targets is excellent. Destructive and constructive interference effects in the case of H₂ are observed and …

Non-Parametric Quantile Selection For Extreme Distributions, Wan Zawiah Wan Zin, Abdul Aziz Jemain

Journal of Modern Applied Statistical Methods

The objective is to select the best non-parametric quantile estimation method for extreme distributions. This serves as a starting point for further research in quantile application such as in parameter estimation using LQ-moments method. Thirteen methods of non-parametric quantile estimation were applied on six types of extreme distributions and their efficiencies compared. Monte Carlo methods were used to generate the results, which showed that the method of Weighted Kernel estimator of Type 1 was more efficient than the other methods in many cases.

Adaptive Estimation Of Heteroscedastic Linear Regression Model Using Probability Weighted Moments, Faqir Muhammad, Muhammad Aslam, G.R. Pasha

Journal of Modern Applied Statistical Methods

An adaptive estimator is presented by using probability weighted moments as weights rather than conventional estimates of variances for unknown heteroscedastic errors while estimating a heteroscedastic linear regression model. Empirical studies of the data generated by simulations for normal, uniform, and logistically distributed error terms support our proposed estimator to be quite efficient, especially for small samples.

Least Squares Percentage Regression, Chris Tofallis

Journal of Modern Applied Statistical Methods

In prediction, the percentage error is often felt to be more meaningful than the absolute error. We therefore extend the method of least squares to deal with percentage errors, for both simple and multiple regression. Exact expressions are derived for the coefficients, and we show how such models can be estimated using standard software. When the relative error is normally distributed, least squares percentage regression is shown to provide maximum likelihood estimates. The multiplicative error model is linked to least squares percentage regression in the same way that the standard additive error model is linked to ordinary least squares regression.

Regulating Self-Organizing Nanostructures Via External Mechanism, Jiangyu Li, Q. G. Du, Stephen Ducharme

Stephen Ducharme Publications

Self-organizing nanostructures are ubiquitous in both natural and synthetic materials. They are not only appealing scientifically, by revealing the intrinsic atomic and molecular interactions that might be difficult to detect otherwise, but may also hold the key for the development of novel functional structures and devices. For their technological potential to be fully realized, the size, morphology, and distribution of the self-organizing nanostructures must be regulated. In this paper, we investigate the principles under which the self-organizing nanostructures can be regulated via external mechanisms. Using nanomesa and nanowell formation in polyvinylidene fluoride trifluoroethylene copolymer film as an example, we demonstrate …

Dynamical Pattern Formation During Growth Of A Dual-Species Bose-Einstein Condensate, Shai Ronen, John L. Bohn, Laura Elisa Halmo, Mark Edwards

Department of Physics and Astronomy Faculty Publications

We simulate the growth of a dual species Bose-Einstein condensate using a Gross-Pitaevskii equation with an additional gain term giving rise to the growth. Such growth occurs during simultaneous evaporative cooling of a mixture of two gases. The ground state of a dual condensate is normally either a miscible mixture, or an immiscible phase with two spatially separated components. In a cigar trap the ground state typically consists of one component in the center, and the other component flanking it. Our simulations show that when the condensates are formed in a cigar trap and the mixture is phase separated, then …

Mathematics In The Mountains: The Park City Mathematics Institute, Andrew J. Bernoff

All HMC Faculty Publications and Research

It's noon. A Fields medalist, master high school teachers from the US and abroad, aspiring undergraduate and graduate students, gifted expositors of mathematics, and mathematical artists gather at tables under a tent. Lunch and so much more is served at these meetings of the minds.

Structure Property Relationships In Organic Conjugated Systems, Luke O'Neill

Doctoral

A series of pi(п) conjugated oligomers containing 1 to 6 monomer units were studied by absorption and photoluminescence spectroscopies. The results are discussed and examined with regard to the variation of the optical properties with the increase of effective conjugation length. It was found that there was a linear relationship between the positioning of the absorption and photoluminescence maxima plotted against inverse conjugation length. The relationships are in good agreement with the simple particle in a box method, one of the earliest descriptions of the properties of one-dimensional organic molecules. Variations in the infinite chain limit band gap for a …

Progress Toward Meeting The Challenges Of Our Coastal Urban Future, Juile Pullen, Jason Ching, David J. Sailor, William Thompson, Bob Bornstein, Darko Koracin

Mechanical and Materials Engineering Faculty Publications and Presentations

The article provides information on the Seventh Conference on Coastal Atmospheric and Oceanic Prediction and Processes, and the Seventh Symposium on the Urban Environment in San Diego, California on September 9-13, 2008. Topics include the heterogeneity of urban areas, coastal vulnerabilities, urban planning, and emergency response modeling. The conference featured several speakers including Walter Dabberdt and James Voogt.

Secure Communications Over Hybrid Military Networks, Vamsi Paruchuri, Arjan Durresi, Sriram Chellappan

Computer Science Faculty Research & Creative Works

Stealthiness can be described as a disposition to be sly and to do things surreptitiously. This paper presents a new architecture for flexible and secure networking in battlefields that enables stealthy and covert communication in the presence of node mobility. Our architecture is based on the combination of optical (fiber) and wireless links. Our objective is to be able to carry on undeterred communication without the attack/eavesdropping nodes being able to detect the presence of any communication. This objective is not only crucial for successful completion of the operation, but also for the safety of our mobile nodes, by not …

Morphology Of The Dayside Ionosphere Of Venus: Implications For Ion Outflows, Jane L. Fox

Physics Faculty Publications

The nightside ionosphere of Venus is formed mostly by day-to-night transport of ions below the ionopause, with a small contribution from precipitation of energetic electrons from the wake. This nightward flux of ions should result in dayside ionospheres that are characterized by smaller electron density scale heights at high altitudes than those that are characteristic of diffusive equilibrium. In order to determine both the maximum possible values of the upward fluxes and the upward fluxes implied by comparison of our computed ion and electron density profiles to measurements, we have constructed more than 60 models of the high solar activity …

Evaluating Online Health Information: Beyond Readability Formulas, Gondy Leroy, Stephen Helmreich, James Cowie, Trudi Miller '08, Wei Zheng '08

CGU Faculty Publications and Research

Although understanding health information is important, the texts provided are often difficult to understand. There are formulas to measure readability levels, but there is little understanding of how linguistic structures contribute to these difficulties. We are developing a toolkit of linguistic metrics that are validated with representative users and can be measured automatically. In this study, we provide an overview of our corpus and how readability differs by topic and source. We compare two documents for three groups of linguistic metrics. We report on a user study evaluating one of the differentiating metrics: the percentage of function words in a …

Cees Newsletter, No. 8, Nov. 2008, University Of Colorado Boulder. Center For Energy & Environmental Security

CEES: The Center for Energy & Environmental Security [Newsletter] (2008)

No abstract provided.

Trapping And Characterization Of A Reaction Intermediate In Carbapenem Hydrolysis By B. Cereus Metallo-Β-Lactamase, Mariana F. Tioni, Leticia L. Llarrull, Andrés A. Poeylaut-Palena, Marcelo A. Martí, Miguel Saggu, Gopal R. Periyannan, Ernesto G. Mata, Brian Bennett, Daniel H. Murgida, Alejandro J. Vila

Physics Faculty Research and Publications

Metallo-β-lactamases hydrolyze most β-lactam antibiotics. The lack of a successful inhibitor for them is related to the previous failure to characterize a reaction intermediate with a clinically useful substrate. Stopped-flow experiments together with rapid freeze−quench EPR and Raman spectroscopies were used to characterize the reaction of Co(II)−BcII with imipenem. These studies show that Co(II)−BcII is able to hydrolyze imipenem in both the mono- and dinuclear forms. In contrast to the situation met for penicillin, the species that accumulates during turnover is an enzyme−intermediate adduct in which the β-lactam bond has already been cleaved. This intermediate is a metal-bound anionic species …

Co2 Eor And Co2 Sequestration – The Case For Collaboration, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet on energy policies and how they pertain to enhanced oil recovery (EOR) and CO₂ capture and sequestration (CSS).

Defining Resonance Raman Spectral Responses To Substrate Binding By Cytochrome P450 From Pseudomonas Putida, Piotr J. Mak, Daniel Kaluka, Munyaradzi Edith Manyumwa, Haiqing Zhang, Tianjing Deng, James R. Kincaid

Chemistry Faculty Research and Publications

Resonance Raman spectra are reported for substrate-free and camphor-bound cytochrome P450cam and its isotopically labeled analogues that have been reconstituted with protoheme derivatives that bear -CD₃ groups at the 1, 3, 5, and 8-positions (d12-protoheme) or deuterated methine carbons (d4-protoheme). In agreement with previous studies of this and similar enzymes, substrate binding induces changes in the high frequency and low frequency spectral regions, with the most dramatic effect in the low frequency region being activation of a new mode near 367 cm⁻¹. This substrate-activated mode had been previously assigned as a second “propionate bending” mode (Chen et …

Seasonal Changes In A Eutrophic Lake, Wilgreen Lake, Madison County, Kentucky, Richard D. Stockwell, Walter S. Borowski

EKU Faculty and Staff Scholarship

WilgreenLake (Madison County, Kentucky) covers ~169 acres, formed in 1966 by damming Taylor Fork. The Wilgreen watershed drains residential developments, modified woodlands, cattle pasture, and some industrial/urban areas in the city of Richmond. The lake is deemed “nutrient impaired” by the EPA.

Our main objective is to document the seasonal changes in key lake parameters from summer stratification through fall overturn over 4 months of sampling, August through November, 2008. We collect temperature, oxygen, pH, and conductivity data from 19 stations at depth intervals of 1 meter using an YSI multi-probe. Concurrent with collecting these framework data, we take water …