Physical Sciences and Mathematics Commons^™

Global Attractor Of Solutions Of A Rational System In The Plane, Miron B. Bekker, Martin Bohner, Hristo D. Voulov

Mathematics and Statistics Faculty Research & Creative Works

We consider a two-dimensional autonomous system of rational difference equations with three positive parameters. It was conjectured that every positive solution of this system converges to a finite limit. Here we confirm this conjecture, subject to an additional assumption.

Operationalizing Resilience For Adaptive Coral Reef Management Under Global Environmental Change, Kenneth R. N. Anthony, Paul A. Marshall, Ameer Abdulla, Roger Beeden, Christopher Bergh, Ryan Black, C. Mark Eakin, Edward T. Game, Margaret Gooch, Nicholas A. J. Graham, Alison Green, Scott F. Heron, Ruben Van Hooidonk, Cheryl Knowland, Sangeeta Mangubhai, Nadine Marshall, Jeffrey A. Maynard, Peter Mcginnity, Elizabeth Mcleod, Peter J. Mumby, Magnus Nystrom, David Obura, Jamie Oliver, Hugh P. Possingham, Robert L. Pressey, Gwilym Rowlands, Jerker Tamelander, David Wachenfeld, Stephanie Wear

HCAS Student Articles

Cumulative pressures from global climate and ocean change combined with multiple regional and local-scale stressors pose fundamental challenges to coral reef managers worldwide. Understanding how cumulative stressors affect coral reef vulnerability is critical for successful reef conservation now and in the future. In this review, we present the case that strategically managing for increased ecological resilience (capacity for stress resistance and recovery) can reduce coral reef vulnerability (risk of net decline) up to a point. Specifically, we propose an operational framework for identifying effective management levers to enhance resilience and support management decisions that reduce reef vulnerability. Building on a …

Ip Basics: Copyright For Digital Authors, Thomas G. Field Jr.

Law Faculty Scholarship

Written for computer artists and programmers, this paper addresses the basics, as well as the registration of multiple works, difference between works that are and are not prepared "for hire," and other matters of interest to entrepreneurs as well as to free-lance programmers and artists.

Advocating For Mother Earth In The Undergraduate Classroom: Uniting Twenty-First Century Technologies, Local Resources, Art, And Activism To Explore Our Place In Nature, Christina Triezenberg Ph.D., Ilse A. Schweitzer Vandonkelaar

The Hilltop Review

Despite the growing evidence of humanity’s impact on the natural world and the urgent need to shape citizens who understand the impact that their choices and actions have on their local and global environments, colleges and universities throughout the United States have been slow to add environmental education as a core component of their undergraduate curricula. Harnessing our shared interest in environment issues and the humanities, we designed and taught an experimental course in environmental literature for the honors program at Western Michigan University that we hope will become a template of what is possible in postsecondary environmental education. Using …

Linking Sustainability To Quality Management And Firm Performance, Rajat Mishra, Randy Napier

Faculty Publications

Environmental management practices have evolved significantly over the past two decades. During that time, sustainable operations management practices have purportedly made positive contributions to overall firm performance. This paper develops two conceptual frameworks regarding the relationships among specific elements of environmental management, quality management, and firm performance. We suggest that innovation in quality management mediates the relationship between design for environment and firm performance, and that statistical process control techniques moderate the relationship between environmental management systems and firm performance. We identify future research possibilities, based on these frameworks, to inform scholarly research and practice in environmental management and quality …

The Schwartz Space: Tools For Quantum Mechanics And Infinite Dimensional Analysis, Jeremy Becnel, Ambar Sengupta

Faculty Publications

An account of the Schwartz space of rapidly decreasing functions as a topological vector space with additional special structures is presented in a manner that provides all the essential background ideas for some areas of quantum mechanics along with infinite-dimensional distribution theory.

Implementation Of Collaborative Learning As A High-Impact Practice In A Natural Resources Management Section Of Freshman Seminar, Matthew W. Mcbroom, Steven H. Bullard, David Kulhavy, Daniel R. Unger

Faculty Publications

Forestry and environmental science students enrolled in a one credit hour freshman seminar course participated in a land management evaluation and water quality sampling excursion using canoes and water sampling equipment. The purpose of this assessment was to engage students with hands-on, field based education in order to foster connections to their chosen profession and the resource. This culminated in poster symposium of the experience. Broad competency areas for high impact practices in natural resource management were emphasized for learning. Students were engaged in the exercise and commented that the project helped them develop a sense of place and forming …

Integrating Hands-On Undergraduate Research In An Applied Spatial Science Senior Level Capstone Course, David Kulhavy, Daniel R. Unger, I-Kuai Hung, David Douglass

Faculty Publications

A senior within a spatial science Ecological Planning capstone course designed an undergraduate research project to increase his spatial science expertise and to assess the hands-on instruction methodology employed within the Bachelor of Science in Spatial Science program at Stephen F Austin State University. The height of 30 building features estimated remotely with LiDAR data, within the Pictometry remotely sensed web-based interface, and in situ with a laser rangefinder were compared to actual building feature height measurements. A comparison of estimated height with actual height indicated that all three estimation techniques tested were unbiased estimators of height. An ANOVA, conducted …

Integrating Hands-On Undergraduate Research In An Applied Spatial Science Senior Level Capstone Course, David Kulhavy, Daniel Unger, I-Kuai Hung, David Douglass

Faculty Publications

A senior within a spatial science Ecological Planning capstone course designed an undergraduate research project to increase his spatial science expertise and to assess the hands-on instruction methodology employed within the Bachelor of Science in Spatial Science program at Stephen F Austin State University. The height of 30 building features estimated remotely with LiDAR data, within the Pictometry remotely sensed web-based interface, and in situ with a laser rangefinder were compared to actual building feature height measurements. A comparison of estimated height with actual height indicated that all three estimation techniques tested were unbiased estimators of height. An ANOVA, conducted …

Sfa Weather Station-January 2015, Arthur Temple College Of Forestry And Agriculture, Stephen F. Austin State University

Weather Station Data

No abstract provided.

Evaluation Of The Performance Of A Rural Municipal Wastewater Treatment Plant In Nacogdoches, East Texas (Usa) (Abstract), Kefa Karimu Onchoke, Michael Janusa, Salomey Asantewaa Sasu

Faculty Publications

The performance of a rural wastewater treatment facility, Nacogdoches Wastewater Treatment Plant

(NWWTP), in East Texas, USA, was assessed from January 2013 through June 2014. The elemental concentrations (Na, Mg, Ca, Ni, Pb, Mn, Cr, Mo, and Cu, Al, As, B, Ba, Ag, Cd, Fe, Hg, K, Se, Zn, Co, P, and S) were measured using inductively coupled plasma optical emission spectrometry. The anion concentrations (Br−, NO3- , NO2- , PO34-,F−, Cl−, and SO24−) were measured by ion chromatography. In general, the NWWTP was found efficient in removal to ≥ 96% for metals. The removal efficiency for anions was in …

Theoretical Examination Of Solvent And R Group Dependence In Gold Thiolate Nanoparticle Synthesis, Suzanne M. Neidhart, Brian M. Barngrover, Christine M. Aikens

Faculty Publications

The growth of gold thiolate nanoparticles can be affected by the solvent and the R group on the ligand. In this work, the difference between methanol and benzene solvents as well as the effect of alkyl (methyl) and aromatic (phenyl) thiols on the reaction energies and barrier heights is investigated theoretically. Density functional theory (DFT) calculations using the BP86 functional and a triple ζ polarized basis set show that the overall reaction favors methylthiol over phenylthiol with reaction energies of −0.54 and −0.39 eV in methanol, respectively. At the same level of theory, the methanol solvent is favored over the …

Magnetism Of Hexagonal Mn1.5X0.5Sn (X = Cr, Mn, Fe, Co) Nanomaterials, R Fuglsby, Parashu Kharel, Wenyong Zhang, Shah R. Valloppilly, Yung Huh, David J. Sellmyer

David Sellmyer Publications

Mn1.5X0.5Sn (X = Cr, Mn, Fe, Co) nanomaterials in the hexagonal Ni2In-type crystal structure have been prepared using arc-melting and melt spinning. All the rapidly quenched Mn1.5X0.5Sn alloys show moderate saturation magnetizations with the highest value of 458 emu/cm3 for Mn1.5Fe0.5Sn, but their Curie temperatures are less than 300K. All samples except the Cr containing one show spin-glass-like behavior at low temperature. The magnetic anisotropy constants calculated from the high-field magnetization curves at 100K are on the order of 1 Merg/cm3. The vacuum annealing of the ribbons at 550 C significantly improved their magnetic properties with the Curie temperature increasing …

Synthesis And Magnetism Of Single-Phase Mn-Ga Films, Wenyong Zhang, Parashu Kharel, Shah R. Valloppilly, Ralph A. Skomski, David J. Sellmyer

David Sellmyer Publications

Single-phase noncubic Mn-Ga films with a thickness of about 200 nm were fabricated by an in situ annealing of [Mn(x)/Ga(y)/Mn(x)]5 multilayers deposited by e-beam evaporation. Mn-Ga alloys prepared in three different compositions Mn2Ga5 and Mn2Ga were found to crystallize in the tetragonal tP14 and tP2 structures, respectively. Mn3Ga crystallizes in the hexagonal hp8 or tetragonal tI8 structures. All three alloys show substantial magnetocrystalline anisotropy between 7 and 10 Mergs/cm3. The samples show hard magnetic properties including coercivities of Mn2Ga5 and Mn2Ga about 12.0 kOe and of Mn3Ga about 13.4 kOe. The saturation magnetization and Curie temperature of Mn2Ga5, Mn2Ga, and …

Enhancement Of Curie Temperature In Mn2rusn By Co Substitution, A Nelson, Parashu Kharel, Yung Huh, R Fuglsby, J Guenther, Wenyong Zhang, B Staten, Pavel V. Lukashev, David J. Sellmyer

David Sellmyer Publications

The Co-substituted Mn2RuSn nanomaterials, namely, Mn2Ru0.5Co0.5Sn and Mn2Ru0.35Co0.65Sn have been synthesized and investigated. The presence of Co in the Mn2RuSn (a¼6.21A ° ) decreased the lattice parameter, where a¼6.14A ° and 6.12A ° for the as prepared Mn2Ru0.5Co0.5Sn and Mn2Ru0.35Co0.65Sn, respectively. The samples show a ferrimagnetic spin order with relatively small coercivities, similar to those of soft magnetic materials. There is a substantial increase in the Curie temperature (Tc¼448K for Mn2Ru0.5Co0.5Sn and 506K for Mn2Ru0.35Co0.65Sn) of Mn2RuSn (Tc¼272.1 K) due to Co substitution, which is a result of strengthening of the positive exchange interaction in this material. These materials are …

Novel Structures And Physics Of Nanomagnets (Invited), David J. Sellmyer, Balamurugan Balamurugan, Bhaskar Das, P Murherjee, Ralph A. Skomski, George C. Hadjipanayis

David Sellmyer Publications

Nanoscale magnets with characteristic dimensions in the range of 1–100 nm are important in several areas of nanoscience and technology. First, this length scale spans the typical important dimensions of exchange lengths and domain-wall widths, which means that significant control of magnetic properties can be obtained by varying grain or particle dimensions. Second, the nonequilibrium synthetic processes used for clusters, particles, and films, often lead to new real-space crystal structures with completely novel spin structures and magnetic properties. Third, a basic-science challenge in this class of matter involves the spin-polarized quantum mechanics of many-electron systems containing 10–10 000 atoms. Finally, …

Magnetism Of Ta Dichalcogenide Monolayers Tuned By Strain And Hydrogenation, Priyanka Manchanda, Vinit Sharma, Hongbin Yu, David J. Sellmyer, Ralph A. Skomski

David Sellmyer Publications

The effects of strain and hydrogenation on the electronic, magnetic, and optical properties of monolayers of Ta based dichalcogenides (T_aX₂; X=S, Se, and Te) are investigated using densityfunctional theory. We predict a complex scenario of strain-dependent magnetic phase transitions involving paramagnetic, ferromagnetic, and modulated antiferromagnetic states. Covering one of the two chalcogenide surfaces with hydrogen switches the antiferromagnetic/nonmagnetic T_aX₂ monolayers to a semiconductor, and the optical behavior strongly depends on strain and hydrogenation. Our research opens pathways towards the manipulation of magnetic as well as optical properties for future spintronics and optoelectronics applications

Magnetism Of Fept Nanoclusters In Polyimide, Mircea Chipara, Tom George, Yingfan Xu, Ralph Skmoski, Lanping Yue, Nasar Ali, David J. Sellmyer

David Sellmyer Publications

FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10) dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10 phase. All samples (as deposited and annealed) exhibited electron spin resonance spectra consisting of two overlapping lines. …

Exploiting Enzymatic Dynamic Reductive Kinetic Resolution (Dyrkr) In Stereocontrolled Synthesis, Gregory A. Applegate, David B. Berkowitz

David Berkowitz Publications

Over the past two decades, the domains of both frontline synthetic organic chemistry and process chemistry have seen an increase in crosstalk between asymmetric organic/organometallic approaches and enzymatic approaches to stereocontrolled synthesis. This review highlights the particularly auspicious role for dehydrogenase enzymes in this endeavor, with a focus on dynamic reductive kinetic resolutions (DYRKR) to “deracemize” building blocks, often setting two stereocenters in so doing. The scope and limitations of such dehydrogenase-mediated processes are overviewed, as are future possibilities for the evolution of enzymatic DYRKR.

Is Shallow Water A Suitable Surrogate For Assessing Efforts To Address Pallid Sturgeon Population Declines?, T R. Gemeinhardt, N.J C. Gosch, D M. Morris, M L. Miller, T L. Welker, J L. Bonneau

US Army Corps of Engineers

It is hypothesized that slow, shallow water habitats benefit larval pallid sturgeon Scaphirhynchus albus; however, testing this hypothesis is difficult, given the low number of larval pallid sturgeon present in large rivers. In contrast, relatively large numbers of age-0 shovelnose sturgeon Scaphirhynchus platorynchus have been sampled, providing a potentially useful baseline to assess the importance of slow, shallow water to age-0 sturgeon of both species (hereafter age-0 sturgeon) in the lower Missouri River. Thus, we investigated the potential relationships between the prevalence of shallow water <1.5m and the age-0 sturgeon catch rates at multiple scales. Age-0 sturgeon were usually sampled in water >1.5 m, and catch rates were usually highest in the upper half [i.e. river kilometer …

Nephrotoxic Contaminants In Drinking Water And Urine, And Chronic Kidney Disease In Rural Sri Lanka, Tewodros Rango, Marc Jeuland, Herath Manthrithilake, Peter G. Mccornick

Daugherty Water for Food Global Institute: Faculty Publications

Chronic kidney disease of unknown (“u”) cause (CKDu) is a growing public health concern in Sri Lanka. Prior research has hypothesized a link with drinking water quality, but rigorous studies are lacking. This study assesses the relationship between nephrotoxic elements (namely arsenic (As), cadmium (Cd), lead (Pb), and uranium (U)) in drinking water, and urine samples collected from individuals with and/or without CKDu in endemic areas, and from individuals without CKDu in nonendemic areas. All water samples—from a variety of source types (i.e., shallow and deep wells, springs, piped, and surface water)—contained extremely low concentrations of nephrotoxic elements, and all …

Demonstration Of A Daily High-Resolution (375-M) Alexi Evapotranspiration Product For The Nena Region, Christopher Hain, Martha C. Anderson, Mitch Schull, Christopher M.U. Neale

Daugherty Water for Food Global Institute: Faculty Publications

While the current constellation of geostationary sensors provides near-global coverage (60N to 60S) – it requires merging data from 7 satellites [resolving time differences; view angles; atmospheric correction]. Polar orbiting sensors such as MODIS and VIIRS provide daily global coverage of LST at higher resolutions than GEO sensors but at only two times per day.

Assessment Of Village Chicken Production Systems In Kambata Tambaro And Wolaita Zones, Snnpr, Ethiopia, Aman Getiso, Fitsum Tessema, Mesfin Mekonnen, Addisu Jimma, Bereket Zeleke

Daugherty Water for Food Global Institute: Faculty Publications

The study was conducted in four woredas (Damot Gale,Of a, Angacha and Hadero Tunto) the first two of them found in Wolaita zone and two of them in Kambata Tambaro Zone of SNNPR, Ethiopia respectively. A cross-sectional survey was conducted in the study areas to assess village chicken production systems, productive and reproductive performance of village chicken and identifying constraints to village chicken production. Stratified random sampling technique was used to select 240 farming households and administer a pre-tested and structured questionnaire. The results showed that the mean age of interviewed farmers was 37.8±9.3 years; average family size & chicken …

Tomographic Imaging Of Nonsymmetric Multicomponent Tailored Supersonic Flows From Structured Gas Nozzles, Grigory V. Golovin, Sudeep Banerjee, J Zhang, Shouyuan Chen, Cheng Liu, Baozhen Zhao, J Mills, Kevin J. Brown, C Petersen, Donald P. Umstadter

Donald Umstadter Publications

We report experimental results on the production and characterization of asymmetric and composite supersonic gas flows, created by merging independently controllable flows from multiple nozzles. We demonstrate that the spatial profiles are adjustable over a large range of parameters, including gas density, density gradient, and atomic composition. The profiles were precisely characterized using three-dimensional tomography. The creation and measurement of complex gas flows is relevant to numerous applications, ranging from laser-produced plasmas to rocket thrusters.

Compact Source Of Narrowband And Tunable X-Rays For Radiography, Sudeep Banerjee, Shouyuan Chen, Nathan D. Powers, Daniel Haden, Cheng Liu, Grigory V. Golovin, Jun Zhang, Baozhen Zhao, S. Clarke, Sara Pozzi, Jack Silano, H. Karwowski, Donald Umstadter

Donald Umstadter Publications

We discuss the development of a compact X-ray source based on inverse-Compton scattering with a laser-driven electron beam. This source produces a beam of high-energy X-rays in a narrow cone angle (5–10 mrad), at a rate of 108 photons-s_1. Tunable operation of the source over a large energy range, with energy spread of ~50%, has also been demonstrated. Photon energies >10 MeV have been obtained. The narrowband nature of the source is advantageous for radiography with low dose, low noise, and minimal shielding.

All-Laser-Driven Thomson X-Ray Sources, Donald Umstadter

Donald Umstadter Publications

We discuss the development of a new generation of accelerator-based hard X-ray sources driven exclusively by laser light. High-intensity laser pulses serve the dual roles: first, accelerating electrons by laser-driven plasma wakefields, and second, generating X-rays by inverse Compton scattering. Such all-laser-driven X-rays have recently been demonstrated to be energetic, tunable, relatively narrow in bandwidth, short pulsed and well collimated. Such characteristics, especially from a compact source, are highly advantageous for numerous advanced X-ray applications—in metrology, biomedicine, materials, ultrafast phenomena, radiology and fundamental physics.

Electrostatic Charge On Flying Hummingbirds And Its Potential Role In Pollination, Marc Badger, Victor Manuel Ortega-Jimenez, Lisa Von Ribenau, Ashley Smiley, Robert Dudley, Alexei Gruverman , Editor

Alexei Gruverman Publications

Electrostatic phenomena are known to enhance both wind- and insect-mediated pollination, but have not yet been described for nectar-feeding vertebrates. Here we demonstrate that wild Anna's Hummingbirds (Calypte anna) can carry positive charges up to 800 pC while in flight (mean ± s.d.: 66 ± 129 pC). Triboelectric charging obtained by rubbing an isolated hummingbird wing against various plant structures generated charges up to 700 pC. A metal hummingbird model charged to 400 pC induced bending of floral stamens in four plants (Nicotiana, Hemerocallis, Penstemon, and Aloe spp.), and also attracted falling Lycopodium spores at distances of < 2 mm. Electrostatic forces may therefore influence pollen transfer onto nectar-feeding birds.

Yield Gap Analysis Of Field Crops: Methods And Case Studies, V. O. Sadras, Kenneth Cassman, Patricio Grassini, W. G.M. Bastiaanssen, A. G. Laborte, A. E. Milne, G. Sileshi, P. Steduto

Daugherty Water for Food Global Institute: Faculty Publications

The challenges of global agriculture have been analysed exhaustively and the need has been established for sustainable improvement in agricultural production aimed at food security in a context of increasing pressure on natural resources. Whereas the importance of R&D investment in agriculture is increasingly recognised, better allocation of limited funding is essential to improve food production. In this context, the common and often large gap between actual and attainable yield is a critical target. Realistic solutions are required to close yield gaps in both small and large scale cropping systems worldwide; to make progress in this direction, we need (1) …

Increasing Access To Natural Areas: Connecting Physical And Social Dimensions, Bradford S. Gentry, Jazmine Da Costa, Katie Christiansen Holsinger, W. Colby Tucker, Matthew R. Viens

Yale School of the Environment Publications Series

Report of the 2015 Berkley Workshop

Held at the Asticou Inn, Northeast Harbor, Maine - July 2015

Almost Sure Asymptotic Stabilization Of Differential Equations With Time-Varying Delay By Lévy Noise, Dezhi Liu, Weiqun Wang, Jose Luis Menaldi

Mathematics Faculty Research Publications

This paper aims to determine that the Lévy noise can stabilize the given differential equations with time-varying delay, which has generalized the Brownian motion case. An analysis is developed and sufficient conditions on the stabilization for stochastic differential equations with time-varying delay are presented. Our stabilization criteria is in terms of linear matrix inequalities (LMIs), whence the feedback controls can be designed more easily in practice.