Physical Sciences and Mathematics Commons^™

The State Of Eritrea Ministry Of Land, Water And Environment, Department Of Environment, Eritrea

East Africa

Increased climate variability has already been evidenced in Eritrea. Mean annual temperature has increased by 1.7 0C since 1960, an average rate of 0.370C per decade. The increase is most rapid in July, August and September at a rate of 0.550C per decade which is the most important season in Eritrea for agricultural production. Increases in the frequency of hot nights are larger and statistically significant in June, July and August as well as October, November and December and in the annual data. The average number of ‗cold‘ nights per year has decreased by 34 (9.3% of days). The 1912-2005 …

Gendered Livelihoods And The Politics Of Socio-Environmental Identity: Women’S Participation In Conservation Projects In Calakmul, Mexico, Claudia Radel

Environment and Society Faculty Publications

A livelihoods approach positions individuals, situated within households, as active agents within processes occurring at various scales. Environmental conservation efforts represent one such process with direct implications for local sustainable livelihoods and the gendered nature of livelihood strategies. In this article, I examine collective processes of socio-environmental identity construction as gendered sustainable livelihood strategies, articulated in and through the activities of women's agricultural organizations in communities bordering the Calakmul Biosphere Reserve in rural southern Mexico. I present group histories and visual evidence from group activities – adapted from participatory rural appraisal (PRA) methodology – to highlight two important concepts. These …

Potential Effects Of Altered Precipitation Regimes On Primary Production In Terrestrial Ecosystems, Joanna S. Hsu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In addition to causing an increase in mean temperatures, climate change is also altering precipitation regimes across the globe. General circulation models project both latitude-dependent changes in precipitation mean and increases in precipitation variability. These changes in water availability will impact terrestrial primary productivity, the fixation of carbon dioxide into organic matter by plants. In my thesis, I addressed the following three questions: 1.) What will be the relative effect of changes in the mean and standard deviation of annual precipitation on mean annual primary production? 2.) Which ecosystems will be the most sensitive to changes in precipitation? 3.) Will …

Pedestrian Leadership And Egress Assistance Simulation Environment (Please), Kyle D. Feuz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pedestrian simulation models are used in many different applications including, the design of safer buildings, the validation of fire codes, and automatic video surveillance and tracking. By improving the simulation model used, each of the application areas can experience similar improvements in accuracy. Current simulation models fail to address key concerns in representing pedestrian knowledge and in accurately modeling group formation. This project has at its core the goal of bringing attention these areas of concern and providing an initial look at ways to solve these problems.

The Pedestrian Leadership and Egress Assistance Simulation Environment (PLEASE) is developed specifically to …

Analyzing Common Algebra-Related Misconceptions And Errors Of Middle School Students., Sarah B. Bush

Electronic Theses and Dissertations

The purpose of this study was to examine common algebra-related misconceptions and errors of middle school students. In recent years, success in Algebra I is often considered the mathematics gateway to graduation from high school and success beyond. Therefore, preparation for algebra in the middle grades is essential to student success in Algebra I and high school. This study examines the following research question: What common algebra-related misconceptions and errors exist among students in grades six and eight as identified on student responses on an annual statewide standardized assessment? In this study, qualitative document analysis of existing data was used …

Science Today In Verse, Hope Leman

Sci-Tech News

No abstract provided.

Materials Research & Manufacturing Section, Bette Finn

Sci-Tech News

No abstract provided.

Division Officers And Boards

Sci-Tech News

No abstract provided.

Full Issue: Vol. 65, No. 4

Sci-Tech News

No abstract provided.

Chernoff Dimensionality Reduction-Where Fisher Meets Fkt, Jing Peng, Guna Seetharaman, Wei Fan, Stefan Robila, Aparna Varde

Department of Computer Science Faculty Scholarship and Creative Works

Well known linear discriminant analysis (LDA) based on the Fisher criterion is incapable of dealing with heteroscedasticity in data. However, in many practical applications we often encounter heteroscedastic data, i.e., within-class scatter matrices can not be expected to be equal. A technique based on the Chernoff criterion for linear dimensionality reduction has been proposed recently. The technique extends well-known Fisher's LDA and is capable of exploiting information about heteroscedasticity in the data. While the Chernoff criterion has been shown to outperform the Fisher's, a clear understanding of its exact behavior is lacking. In addition, the criterion, as introduced, is rather …

Message From The Senior Vice Provost And Dean Of Undergraduate Studies, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Notes From The Director, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Friends Of The Library Mcnair Scholarship Awards, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Acknowledgements, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Mcnair Scholars Program, The Mcnair Team

McNair Scholars Research Journal

No abstract provided.

Genetic Structure Of Grass Carp Populations In The Missouri And Mississippi River Basins, Usa, Bobbi M. Adams, Katie N. Bertrand, Michael L. Brown, Donald Auger

The Prairie Naturalist

We provided an early characterization of the genetic structure of the grass carp (Ctenopharyngodon idella) population as it expands its distribution in both the Missouri and Mississippi River basins. Further, we provided initial comparisons of allelic richness at 17 polymorphic microsatellite markers between 56 grass carp from the USA, and six from the Yangtze River in China. The number of alleles per locus ranged from two to eight and size ranges of alleles for fish collected from the invaded and native ranges were similar (P ≤ 0.001; 107–226 bp) to those previously reported in the literature. Distance-based clustering …

Notes On The Distribution Of Eastern Woodrats And Hispid Cotton Rats In South-Central Nebraska, Heather D. Wills, Keith Geluso, Eric J. Smits, Joseph T. Springer, Wesley E. Newton

The Prairie Naturalist

The eastern woodrat (Neotoma floridana) and hispid cotton rat (Sigmodon hispidus) reach distributional limits in southern Nebraska (Jones 1964, Farney 1975). In the last half-century, both species have expanded their distributional ranges in the region (Kugler and Geluso 2009, Wright et al. 2010). Herein, we report new localities of occurrence for both species that extend known distributional boundaries in south-central Nebraska beyond those reported by Kugler and Geluso (2009) and Wright et al. (2010).

Associated with other studies, we captured small mammals in Sherman live-traps in south-central Nebraska. Voucher specimens were deposited in collections at the …

Comparison Of Fish Communities In Recently Constructed Side-Channel Chutes With The Main Stem Missouri River, Kasey Whiteman, Vincent H. Travnichek, Darrick L. Garner, Brandon Eder, Kirk Steffensen

The Prairie Naturalist

Two United States Army Corp of Engineers- (USACE) funded projects were conducted from 2006 to 2008 along the Missouri River to monitor fish communities in recently constructed side-channel chutes and to monitor pallid sturgeon (Scaphirhynchus albus) and the associated fish assemblage in the main stem Missouri River. Data from both monitoring projects were compared to evaluate fish assemblages among four mitigated habitats (e.g., constructed side-channel chutes) and the main-stem Missouri River. Chutes had a greater overall number of species (n = 59) and higher species richness (Margalef’s index = 5.81), but richness was not different (F1, 4 = …

Patterns Of Age-0 Gizzard Shad Abundance And Food Habits In A Nebraska Irrigation Reservoir, Christopher L. Sullivan, Casey W. Schoenebeck, Keith D. Koupal, W. Wyatt Hoback, Brian C. Peterson

The Prairie Naturalist

Gizzard shad (Dorosoma cepedianum) are prolific spawners that can influence reservoir communities. Larval gizzard shad may compete with larval recreational fish for zooplankton resources. Therefore, it is necessary to determine larval gizzard shad dynamics and food habits to better understand their potential for competition with larval recreational fish. Our study examined age-0 gizzard shad abundance in Harlan County Reservoir during late spring/summer from 2002–2010 and food habits and prey electivity of age-0 gizzard shad during late spring/summer 2008 and 2009. The annual peak age-0 gizzard shad density 3 from 2002–2010 ranged from 50 to 380/100 m , which …

Northern Harrier Hatches Mallard Nest, Jeffery W. Stackhouse, Benjamin A. Geaumont

The Prairie Naturalist

The northern harrier (Circus cyaneus) is a widespread raptor commonly found nesting throughout the Northern Great Plains. Northern harriers forage primarily on small mammals and passerines with the males providing the majority of prey to nestlings until 14–28 days of age (Redpath et al. 2006, Vukovich and Ritchison 2006). Although the genus Circus is known to predate eggs from nest of many nesting birds (Hiraldo et al. 1975, Donaszar et al. 1996, Opermanis et al. 2000), few have been recorded commandeering nests of different species (Laine 1928, Fleskes 1992). In June 2010, we observed a northern harrier that …

Late Seasonal Captures Of The Plains Pocket Mouse (Perognathus Flavescens) In Iowa, Hans W. Otto, Jeremy A. White

The Prairie Naturalist

The plains pocket mouse, Perognathus flavescens, is a nocturnal granivore that inhabits friable soils in sparsely vegetated areas (Monk and Jones 1996). In the United States, the distribution of the plains pocket mouse extends from Arizona, New Mexico, and Texas through the Great Plains to North Dakota and Minnesota (Hall 1981). This species reaches its easternmost limits in Iowa, where it has been documented from a limited number of grassland sites in eastern, central, and western parts of the state (Bowles 1975, Wilson et al. 1996). Due to loss of grassland habitat, the plains pocket mouse is currently listed …

Rainbow: An R Package For Visualizing Functional Time Series, Han Lin Shang

The R Journal

Recent advances in computer technology have tremendously increased the use of functional data, whose graphical representation can be infinite-dimensional curves, images or shapes. This article describes four methods for visualizing functional time series using an R add-on package. These methods are demonstrated using age-specific Australian fertility data from 1921 to 2006 and monthly sea surface temperatures from January 1950 to December 2006.

Implementing The Compendium Concept With Sweave And Docstrip, Michael Lundholm

The R Journal

This article suggests an implementation of the compendium concept by combining Sweave and the LATEX literate programming environment DOCSTRIP.

Watch Your Spelling!, Kurt Hornik, Duncan Murdoch

The R Journal

We discuss the facilities in base R for spell checking via Aspell, Hunspell or Ispell, which are useful in particular for conveniently checking the spelling of natural language texts in package Rd files and vignettes. Spell checking performance is illustrated using the Rd files in package stats. This example clearly indicates the need for a domain-specific statistical dictionary. We analyze the results of spell checking all Rd files in all CRAN packages and show how these can be employed for building such a dictionary.

Portable C++ For R Packages, Martyn Plummer

The R Journal

Package checking errors are more common on Solaris than Linux. In many cases, these errors are due to non-portable C++ code. This article reviews some commonly recurring problems in C++ code found in R packages and suggests solutions.

Glm2: Fitting Generalized Linear Models With Convergence Problems, Ian C. Marschner

The R Journal

The R function glm uses step-halving to deal with certain types of convergence problems when using iteratively reweighted least squares to fit a generalized linear model. This works well in some circumstances but non-convergence remains a possibility, particularly with a non standard link function. In some cases this is be cause step-halving is never invoked, despite a lack of convergence. In other cases step-halving is invoked but is unable to induce convergence. One remedy is to impose a stricter form of step halving than is currently available in glm, so that the deviance is forced to decrease in every iteration. …

Creating And Deploying An Application With (R)Excel And R, Thomas Baier, Erich Neuwirth, Michele De Meo

The R Journal

We present some ways of using R in Excel and build an example application using the package rpart. Starting with simple interactive use of rpart in Excel, we eventually package the code into an Excel-based application, hiding all details (including R itself) from the end user. In the end, our application implements a service oriented architecture (SOA) with a clean separation of presentation and computation layer

Complex Dynamics Of Discrete Seis Models With Simple Demography, Hui Cao, Yicang Zhou, Baojun Song

Department of Applied Mathematics and Statistics Faculty Scholarship and Creative Works

We investigate bifurcations and dynamical behaviors of discrete SEIS models with exogenous reinfections and a variety of treatment strategies. Bifurcations identified from the models include period doubling, backward, forward-backward, and multiple backward bifurcations. Multiple attractors, such as bistability and tristability, are observed. We also estimate the ultimate boundary of the infected regardless of initial status. Our rigorously mathematical analysis together with numerical simulations show that epidemiological factors alone can generate complex dynamics, though demographic factors only support simple equilibrium dynamics. Our model analysis supports and urges to treat a fixed percentage of exposed individuals.

Electron Screening And Disorder-Induced Heating In Ultracold Neutral Plasmas, Mary Elizabeth Lyon

Theses and Dissertations

Disorder-induced heating (DIH) is a nonequilibrium, ultrafast relaxation process that occurs when laser-cooled atoms are photoionized to make an ultracold plasma. Its effects dominate the ion motion during the first 100 ns of the plasma evolution. Using tools of atomic physics we study DIH with ns time resolution for different plasma densities and temperatures. By changing the frequency of the laser beam we use to probe the ions, we map out the time evolution of the velocity distribution. We can compare this to a fluorescence simulation in order to more clearly determine the relationship between the fluorescence signal and the …

Chemical Modification On Gold Slides To Gain Better Control Of Patterning Techniques, Ragini Vuppalapati

Masters Theses & Specialist Projects

Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip.

This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern …