Physical Sciences and Mathematics Commons^™

The Communicator, Volume [3], Issue [2], September 2007

The Communicator: News from the Nebraska Cooperative Fish and Wildlife Research Unit

New Director

School of Natural Resources

Changes

New Unit Logo

Welcome! (Chad Smith; Aaron Alai)

Current Research

Amphibian Monitoring Techniques (in Relation

to Wetland Qualities and the Surrounding

Landscape – Rainwater Basin Region)

An Adaptive Management Approach for Selecting

Habitat Improvement Targets in the Shortgrass

Prairie Ecosystem

Cross-Scale Structure in Ecosystems

Diversity and Ecological Functions

Evaluation of Landowner Incentives Program

(LIP) for Species at Risk

Impact of White Perch on Walleye; and

Predators of White Perch at Branched Oak and

Pawnee Reservoirs

Monitoring, Mapping and Risk Assessment for

Non-Indigenous Invasive Species in Nebraska

Graduate Student News (Aaron Alai; Elizabeth (Beth) …

The Equation, Winter 2007, College Of Science And Mathematics, Wright State University

College of Science and Mathematics Newsletters

This 26 page newsletter discusses various happenings within the College of Science and Mathematics. It begins with a letter from the dean, and continues on with news, events, alumni news, and other community news.

Fractal Characterization Of Fracture Networks: An Improved Box-Counting Technique, Ankur Roy, Edmund Perfect, William M. Dunne, Larry Mckay

Earth and Planetary Sciences Publications and Other Works

Box counting is widely used for characterizing fracture networks as fractals and estimating their fractal dimensions (D). If this analysis yields a power law distribution given by N $\propto$ r^−D, where N is the number of boxes containing one or more fractures and r is the box size, then the network is considered to be fractal. However, researchers are divided in their opinion about which is the best box‐counting algorithm to use, or whether fracture networks are indeed fractals. A synthetic fractal fracture network with a known D value was used to develop a new algorithm for the …

Secondary Neutron-Production Cross Sections From Heavy-Ion Interactions Between 230 And 600 Mev/Nucleon, Lawrence H Heilbronn

Faculty Publications and Other Works -- Nuclear Engineering

Secondary neutron-production cross-sections have been measured from interactions of 230 MeV/nucleon He, 400 MeV/nucleon N, 400 MeV/nucleon Kr, 400 MeV/nucleon Xe, 500 MeV/nucleon Fe, and 600 MeV/nucleon Ne interacting in a variety of elemental and composite targets. We report the double-differential production cross sections, angular distributions, energy spectra, and total cross sections from all systems. Neutron energies were measured using the time-of-flight technique, and were measured at laboratory angles between 5° and 80°. The spectra exhibit behavior previously reported in other heavy-ion-induced neutron production experiments; namely, a peak at forward angles near the energy corresponding to the beam velocity, with …

Natural River Restoration In Urban Ecology: The Bronx River, Samuel P. Loor

Student Theses 2001-2013

Environmental science is the systematic study of our environment and our proper place in it. A relatively new field, environmental science is highly interdisciplinary, integrating natural sciences, social sciences, and humanities in a broad, holistic study of the world around us. In contrast to more theoretical disciplines, environmental science is mission-oriented. That is, it seeks new, valid, contextual knowledge about the natural world and our impacts on it, but obtaining this information creates a responsibility to get involved in trying something about the problems we have created i.e. environmental science is an applied science. For this study the environment that …

Selective Synthesis Of Oxacalix[6]Arenes And Mixed Oxacalix[4]Arenes, Christian Crannell

Undergraduate Research Symposium (UGRS)

Calixarenesare macrocycles composed of benzene rings meta linked to each other by one carbon atom. These exotic compounds can be used for a variety of purposes including metalleaching for environmental cleanup, surface technology, luminescent probes, nuclear waste treatment, among others. A variety of calixarenesexist, including azacalix[n]arenesthiocalix[n]arenes(where n = the number of benzene rings) and oxacalix[n]arenes; these macrocycles use nitrogen, sulfur and oxygen, respectively, as the atom whichlinks the benzene rings together. My research has focused on synthesizing oxacalix[6]arenes (“hexamer”) in high yield, which is a synthetic challenge because it is generally accepted that oxacalix[n>4]arenes will thermodynamically decompose to the …

Photochemical Production Of Micromolarsuperoxidestandards In Aqueous Solutiont, T. C. Ong, D. W. King

Undergraduate Research Symposium (UGRS)

Superoxide(O2-) is a reactive free radical that rapidly undergoes disproportionation to hydrogen peroxide and oxygen. This property makes preparation of superoxide standard for instrument calibration difficult. McDowell et al. (1983) showed photolysis of ketone and alcohol as a convenient method to generate superoxide through triplet and radical intermediates reacting with molecular oxygen. This study expands on this past work and investigates detailed mechanism of the reaction.

An Injection-Locked Diode Laser For Cold Rydberg Atom Experiments, Margaret S. Martei, Anders P. Wood, Duncan A. Tate

Undergraduate Research Symposium (UGRS)

A free-running, temperature stabilized diode laser has been injection-locked to an external cavity diode laser for use in cold Rydberg atom experiments. Cold rubidium atoms in a magneto-optical trap (MOT) are excited to Rydberg states using a 10 ns laser pulse. The Rydberg atoms spontaneously ionize due to dipole forces, and the collisional ionization dynamics are observed as a function of atom density and principal quantum number of the Rydberg state, n. The injection-locked diode laser will be used as a repumper in conjunction with a dark spontaneous-force optical trap (SPOT) to increase the Rydberg state density. We report on …

Methods To Convert Local Sampling Coordinates Into Geographic Information System/Global Positioning Systems (Gis/Gps)-Compatible Coordinate Systems, Mark Rudnicki, Thomas H. Meyer

Department of Natural Resources and the Environment Articles

Laying out a sampling transect in the field is a common task when researching natural systems and resources. With widespread availability of global navigation satellite systems (GNSS), such as the US global positioning system (GPS), it is becoming more common to resurvey legacy transects to establish them in globally referenced coordinate systems such as geodetic latitude/longitude or planimetric systems such as the Universal Transverse Mercator (UTM) or the State Plane Coordinate System (SPCS). Transforming local coordinates into a globally referenced coordinate system allows (1) disparate legacy surveys to be combined into a common geographic information system (GIS) database, (2) new …

The Center Of Some Braid Groups And The Farrell Cohomology Of Certain Pure Mapping Class Groups, Craig A. Jensen, Yu Qing Chen, Henry H. Glover

Mathematics Faculty Publications

In this paper we first show that many braid groups of low genus surfaces have their centers as direct factors. We then give a description of centralizers and normalizers of prime order elements in pure mapping class groups of surfaces with spherical quotients using automorphism groups of fundamental groups of the quotient surfaces. As an application, we use these to show that the primary part of the Farrell cohomology groups of certain mapping class groups are elementary abelian groups. At the end we compute the primary part of the Farrell cohomology of a few pure mapping class groups.

The Euler Characteristic Of The Whitehead Automorphism Group Of A Free Product, Craig A. Jensen, Jon Mccammond, John Meier

Mathematics Faculty Publications

A combinatorial summation identity over the lattice of labelled hypertrees is established that allows one to gain concrete information on the Euler characteristics of various automorphism groups of free products of groups. In particular, we establish formulae for the Euler characteristics of: the group of Whitehead automorphisms...

Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek Malkinski, Leonard Spinu, Weillie Zhou, Scott Whittenburg

Physics Faculty Publications

Permalloy antidot arrays with different square hole sizes (1200×1200, 800×800, and 400×400 nm²) have been fabricated by means of electron-beam lithography and lift-off techniques. The smaller square hole size results in enhanced remanence and reduced coercivity in the antidot array. Multiple resonance modes were clearly observed for the magnetic field applied normal to the array plane, and double uniform resonance modes occurred when the field deviated more than 30° from the normal to the plane. Two distinct dipolar field patterns with different orientations and magnitudes split the uniform resonance into double resonance modes. The double resonance modes show …

Enhanced Spin-Dependent Tunneling Magnetoresistance In Magnetite Films Coated By Polystyrene, Wendong Wang, Leszek Malkinski, Jinke Tang

Physics Faculty Publications

Hematite films were deposited by magnetron sputtering. A phase transformation from hematite to magnetite occurred when polystyrene (PS) coated hematite films were annealed above 200 °C in hydrogen flow. Giant negative magnetoresistance (MR) was observed with the best MR ratio of over 8% (at room temperature and in a field of 5.5 T) found in samples annealed at 230 °C. The temperature dependence of the resistivity is characteristic of intergranular tunneling. After the PS layer was removed and the films annealed again at 230 °C in hydrogen flow, the resistivity increased by about one order of magnitude and the MR …

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Y. Voyk, Donald J. Scherer Ii, Leonard Spinu, Weillie Zhou, Scott Whittenburg, Zachary Davis, Jin-Seung Jung

Physics Faculty Publications

Arrays consisting of nanosized stripes of Permalloy with different length-to-width ratios have been fabricated using electron beam nanolithography, magnetron sputtering, and lift-off process. These stripes have a thickness of 100 nm, a width of 300 nm, and different lengths ranging from 300 nm to 100 μm. The stripes are separated by a distance of 1 μm. Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at 9.8 GHz was determined by means of ferromagnetic resonance technique. The dependence of the resonant field on the angle between the nanostructure and the in-plane dc magnetic …

Quantitative Method For Measurement Of The Goos-Hanchen Effect Based On Source Divergence Considerations, Jeffrey F. Gray, Ashok Puri

Physics Faculty Publications

In this paper we report on a method for quantitative measurement and characterization of the Goos-Hanchen effect based upon the real world performance of optical sources. A numerical model of a nonideal plane wave is developed in terms of uniform divergence properties. This model is applied to the Goos-Hanchen shift equations to determine beam shift displacement characteristics, which provides quantitative estimates of finite shifts near critical angle. As a potential technique for carrying out a meaningful comparison with experiments, a classical method of edge detection is discussed. To this end a line spread Green’s function is defined which can be …

Dynamic And Temperature Effects In Toggle Magnetic Random Access Memory, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu

Physics Faculty Publications

In this paper we have studied the dynamic switching in magnetic random access memory (MRAM) and its dependence on thermal effects due to a finite temperature. The model is based on the Landau-Lifshitz-Gilbert equation and the stochastic Landau-Lifshitz-Gilbert equation which are numerically integrated. The magnetic layers are assumed to be ellipsoid shaped with each magnetic layer single domain. In addition, we have taken into account the uniaxial intrinsic anisotropy. Simulations were performed for both balanced and nonbalanced synthetic antiferromagnetic elements. The switching properties are discussed as a function of applied field pulses’ length and shape. In this paper we present …

Physics Of Complex Transverse Susceptibility Of Magnetic Particulate Systems, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu

Physics Faculty Publications

Complex transverse susceptibility is a recent proposed method for the determination of anisotropy and volume distributions in particulate magnetic media. So far, only thermal fluctuations and rate-dependent damped dynamics of the magnetic moment have been identified as reasons for the existence of the imaginary transverse susceptibility. In this paper, we apply a more general approach to derive the complex transverse susceptibility, and we show that the hysteresis phenomenon is the most general concept behind the existence of complex transverse susceptibility. In this paper, the physical origins of the imaginary part of transverse susceptibility are analyzed: rate-independent hysteresis, viscous-type rate-dependent hysteresis, …

Data Integration, Meenakshi Nagarajan

Kno.e.sis Publications

No abstract provided.

Sensor Networks Survey, Cory Andrew Henson, Satya S. Sahoo

Kno.e.sis Publications

No abstract provided.

2007 Hampton Roads Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

2007 Gloucester Point Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

2007 Wachapreague Station Tide Prediction Calendars, Virginia Institute Of Marine Science, David A. Evans

Miscellaneous

These calendars are produced monthly using David Evans' Tidecal.

Tr-2007002: Additive Preconditioning And Aggregation In Matrix Computations, Victor Y. Pan, Brian Murphy, Rhys Eric Rosholt, Dmitriy Ivolgin, Yuqing Tang, Xiaodong Yan

Computer Science Technical Reports

No abstract provided.

Tr-2007003: Additive Preconditioning For Matrix Computations, Victor Y. Pan, Dmitriy Ivolgin, Brian Murphy, Rhys Eric Rosholt, Yuqing Tang, Xiaodong Yan

Computer Science Technical Reports

No abstract provided.

Tr-2007005: Interpreting Knowledge Into Belief In The Presence Of Negative Introspection, Evan Goris

Computer Science Technical Reports

No abstract provided.

Tr-2007008: The Satisfiability Problem—From The Theory Of Np-Completeness To State-Of-The-Art Sat Solvers, Rave Harpaz

Computer Science Technical Reports

No abstract provided.

Tr-2007011: Numerical Computation Of Determinants With Additive Preconditioning, V. Y. Pan, B. Murphy, G. Qian, R. E. Rosholt, I. Taj-Eddin

Computer Science Technical Reports

No abstract provided.

Tr-2007012: The Relative Expressivity Of Public And Private Communication In Bms Logic, Bryan Renne

Computer Science Technical Reports

No abstract provided.

Tr-2007013: Error-Free Computations Via Floating-Point Operations: The Code, V. Y. Pan, B. Murphy, G. Qian, R. E. Rosholt

Computer Science Technical Reports

No abstract provided.

Tr-2007018: Peak Shaving Through Resource Buffering, Amotz Bar-Noy, Matthew P. Johnson, Ou Liu

Computer Science Technical Reports

No abstract provided.