Physical Sciences and Mathematics Commons^™

Disko Solution In Braille, Jeremiah Farrell

Scholarship and Professional Work - LAS

A copy of a 4x4 DISKO solution in Braille. Constructed by students at the Indiana School for the Blind on magnetized squares on a "toasted", i.e. raised grid.

Evidence For Marine Influence On A Low-Gradient Coastal Plain: Ichnology And Invertebrate Paleontology Of The Lower Tongue River Member (Fort Union Formation, Middle Paleocene), Western Williston Basin, U.S.A., Edward S. Belt, Neil E. Tibert, H. Allen Curran, John A. Diemer, Joseph H. Hartman, Timothy J. Kroeger, David M. Harwood

Department of Earth and Atmospheric Sciences: Faculty Publications

The Paleocene Tongue River Member of the Fort Union Formation contains trace-fossil associations indicative of marine influence in otherwise freshwater facies. The identified ichnogenera include: Arenicolites, Diplocraterion, Monocraterion, Ophiomorpha, Rhizocorallium, Skolithos linearis, Teichichnus, Thalassinoides, and one form of uncertain affinity. Two species of the marine diatom Coscinodiscus occur a few meters above the base of the member. The burrows occur in at least five discrete, thin, rippled, fine-grained sandstone beds within the lower 85 m of the member west of the Cedar Creek anticline (CCA) in the Signal Butte, Terry Badlands, and Pine Hills areas. T wo discrete burrowed …

Calcareous Nannofossil Evidence For The Existence Of The Gulf Stream During The Late Maastrichtian, David K. Watkins, Jean M. Self-Trail

Department of Earth and Atmospheric Sciences: Faculty Publications

Upper Maastrichtian calcareous nannofossil assemblages, from eight cores on the South Carolina Coastal Plain (onshore set) and three deep sea drilling sites from the continental slope and abyssal hills (offshore set), were analyzed by correlation and principal component analysis to examine the ancient surface water thermal structure. In addition, a temperature index derived from independently published paleobiogeographic information was applied to the sample data. All three methods indicate a strong separation of the samples into onshore and offshore sets, with the offshore data set exhibiting significantly warmer paleotemperatures. The great disparity between these two sample sets indicates that there was …

Reply To Comment By H. Lough, Department Of Civil Engineering, University Of Canterbury, Christchurch, New Zealand, On The Paper “Stream Depletion Predictions Using Pumping Test Data From A Heterogeneous Stream–Aquifer System (A Case Study From The Great Plains, Usa)”, S. J. Kollet, Vitaly A. Zlotnik

Department of Earth and Atmospheric Sciences: Faculty Publications

1. General remark

2. The study by Kollet and Zlotnik (2003)

3. Remark on the explanation of the drawdown behavior

4. Remark on the re-analysis of the data from piezometer C2d

5. Summary

Vegetation And Climate Change On The Bolivian Altiplano Between 108,000 And 18,000 Years Ago, Alex Chepstow-Lusty, Mark B. Bush, Michael R. Frogley, Paul A. Baker, Sherilyn C. Fritz, James Aronson

Department of Earth and Atmospheric Sciences: Faculty Publications

A 90,000-yr record of environmental change before 18,000 cal yr B.P. has been constructed using pollen analyses from a sediment core obtained from Salar de Uyuni (3653 m above sea level) on the Bolivian Altiplano. The sequence consists of alternating mud and salt, which reflect shifts between wet and dry periods. Low abundances of aquatic species between 108,000 and 50,000 yr ago (such as Myriophyllum and Isoëtes) and marked fluctuations in Pediastrum suggest generally dry conditions dominated by saltpans. Between 50,000 yr ago and 36,000 cal yr B.P., lacustrine sediments become increasingly dominant. The transition to the formation of …

Control Of Finite-Dimensional Quantum Systems: Application To A Spin-1/2 Particle Coupled With A Finite Quantum Harmonic Oscillator, Chitra Rangan, A.M. Bloch

Physics Publications

In this paper, we consider the problem of the controllability of a finite-dimensional quantum system in both the Schrödinger and interaction pictures. Introducing a Quantum Transfer Graph, we elucidate the role of Lie algebra rank conditions and the complex nature of the control matrices. We analyze the example of a sequentially coupled N-level system: a spin-1/2 particle coupled to a finite quantum harmonic oscillator. This models an important physical paradigm of quantum computers - the trapped ion. We describe the control of the finite model obtained, under the right conditions, from the original infinite-dimensional system.

Absolute Wave-Number Measurements In 130te2: Reference Lines Spanning The 420.9-464.6-Nm Region, T.J. Scholl, Steven J. Rehse, R.A. Holt, S.D. Rosner

Physics Publications

We have measured the absolute wave numbers of 39 transitions of 130Te2 spanning the spectral region of 420.9-464.6 nm to an accuracy of better than 2 parts in 109 by use of saturation spectroscopy and Fabry-Pérot interferometry. These measurements provide a set of convenient and accurate transfer standards for laser wavelength calibration spanning the entire Stilbene-420 dye-tuning curve.

Theory Of Detection Of Angular Momentum States In Rydberg Atoms Using Half-Cycle Pulses, Chitra Rangan, R.J.A. Murray

Physics Publications

The creation and detection of specific angular momentum states in Rydberg atoms is a significant advance in quantum-information processing. Detection of high angular momentum states in alkali-metal atoms is difficult because they are nearly-degenerate in energy. We present theoretical results on the detection of such states using terahertz-frequency half-cycle pulses (HCPs). Calculations are done for n=15,=0,...,14 states in hydrogen and cesium using a grid-based pseudopotential method. Our results indicate that HCP redistribution is a reliable method of distinguishing angular momentum Rydberg states.

Binding Energy Of The Positronium Negative Ion: Relativistic And Qed Energy Shifts, Gordon W. F. Drake, M. Grigorescu

Physics Publications

The leading relativistic and QED corrections to the ground-state energy of the three-body system e-e+e- are calculated numerically using a Hylleraas correlated basis set. The accuracy of the nonrelativistic variational ground state is discussed with respect to the convergence of the energy with increasing size of the basis set, and also with respect to the variance of the Hamiltonian. The corrections to this energy include the lowest order Breit interaction, the vacuum polarization potential, one and two photon exchange contributions, the annihilation interaction and spin-spin contact terms. The relativistic effects and the residual interactions considered here decrease the one-electron binding …

An Unprecedented Scientific Community Response To An Unprecedented Event: Tropical Storm Agnes And The Chesapeake Bay, M. P. Lynch

VIMS Books and Book Chapters

In June 1972, the remnants of Hurricane Agnes brought destructive floods to the watershed of the Chesapeake Bay basin. Unlike Hurricane Isabel, Agnes did not strike Chesapeake Bay directly, but deposited a record amount of rainfall on the watershed. The evening that the Agnes rainfall began in earnest coincided with a meeting of the Citizens Program for the Chesapeake Bay. The directors of the three largest Chesapeake Bay research institutions, Drs. Donald W. Pritchard, L. Eugene Cronin, and William J. Hargis Jr., were in attendance at this meeting. The potential magnitude of the Agnes rainfall was readily apparent at the …

Isabel's Silent Partners: Seasonal And Secular Sea Level Change, J. D. Boon

VIMS Books and Book Chapters

Tidal conditions fail to explain a paradoxical similarity in water level extremes induced by Hurricane Isabel on 18 September 2003, and the 23 August 1933 storm of record at Hampton Roads, Virginia. Storm surge peaks occurred near astronomical high tide during both storms, but Isabel arrived during neap tides while tides during the 1933 storm were nearer to spring. In addition, Isabel produced a lesser storm surge, yet she yielded a storm tide, or high-water mark, roughly equal to that of the 1933 hurricane. The answer to the paradox lies in observed sea level—water level measured relative to the land—and …

What Has Been Learned About Storm Surge Dynamics From Hurricane Isabel Model Simulation?, Harry V. Wang, J. Cho, Jian Shen, Y. P. Wang

VIMS Books and Book Chapters

An unstructured grid hydrodynamic model was used to study storm surge in the Chesapeake Bay during Hurricane Isabel. The model-simulated, storm-induced water level compared reasonably well with the measured data collected around the Bay. Calibrated water level was extracted from the model to further analyze the dynamics of the surge as it formed and propagated along the mainstem Chesapeake. Based on time-series analysis, formation of the surge due to the pumping of coastal waters (hereafter called the primary surge) into the Chesapeake was first identified at the Bay mouth with a peak height of 1.5 m above mean sea level …

Benzocycloheptynedicobalt Complexes By Intramolecular Nicholas Reactions, Y. Ding, James R. Green

Chemistry and Biochemistry Publications

Lewis acid mediated intramolecular Nicholas reactions of aryl (Z)-enyne propargyl acetate-CO2(CO)(6) complexes 1 afford benzocycloheptenyne-CO2(CO)(6) complexes 2 and their heterocyclic analogues.

Intramolecular Pauson-Khand Reactions Of Cycloheptynedicobalt Complexes, Ahmed B. Mohamed, James R. Green, Jason Masuda

Chemistry and Biochemistry Publications

Cycloheptyne-Co-2(CO)(6) complexes bearing alkenes tethered by oxygen, sulfur, and nitrogen atoms undergo Pauson-Khand reactions to afford tricyclic compounds containing a fused 7,5-ring system.

Spot Detection And Image Segmentation In Dna Microarray Data, Li Qin, Luis Rueda, Ali Adnan, Alioune Ngom

Computer Science Publications

Following the invention of microarrays in 1994, the development and applications of this technology have grown exponentially. The numerous applications of microarray technology include clinical diagnosis and treatment, drug design and discovery, tumour detection, and environmental health research. One of the key issues in the experimental approaches utilising microarrays is to extract quantitative information from the spots, which represent genes in a given experiment. For this process, the initial stages are important and they influence future steps in the analysis. Identifying the spots and separating the background from the foreground is a fundamental problem in DNA microarray data analysis. …

Cmodels – Sat-Based Disjunctive Answer Set Solver, Yuliya Lierler

Computer Science Faculty Proceedings & Presentations

Disjunctive logic programming under the stable model semantics [GL91] is a new methodology called answer set programming (ASP) for solving combinatorial search problems. This programming method uses answer set solvers, such as DLV [Lea05], GNT [Jea05], SMODELS [SS05], ASSAT [LZ02], CMODELS [Lie05a]. Systems DLV and GNT are more general as they work with the class of disjunctive logic programs, while other systems cover only normal programs. DLV is uniquely designed to find the answer sets for disjunctive logic programs. On the other hand, GNT first generates possible stable model candidates and then tests the candidate on the minimality using system …

How To Overcome The Knowledge Paradox: Activate Knowledge Identity, Not Just Organize Information, Sajda Qureshi, Peter Keen

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

A paradox appears to thwart traditional knowledge sharing efforts in organizations: the greater the benefit of a piece of knowledge to an organization the less likely that it will be shared. This paper suggests that in order to mobilize knowledge where there is demand for it, it has to be activated. This paper considers the knowledge identity of the person whose knowledge is to be activated and uses these identities to analyze a case study in which highly distributed knowledge is activated. The analysis reveals activation effects needed to mobilize each of the knowledge identities.

A Sin Of Omission: Database Transactions, David Hansen

Faculty Publications - Department of Electrical Engineering and Computer Science

Database courses are under increasing pressure to include new topics which inevitably leads to a decision about which topics are essential to the course and which can be omitted to make room for others. Recent surveys have indicated that many instructors are reducing or eliminating coverage of “transaction management” from their introductory database courses. As both an academic and a practitioner, I believe that this is a mistake. This paper discusses why the semantics of transaction management should be an integral topic in any introductory database management system course.

A New Fault Information Model For Fault-Tolerant Adaptive And Minimal Routing In 3-D Meshes, Zhen Jiang, Jie Wu, Dajin Wang

Computer Science Faculty Publications

No abstract provided.

The Btev Rich Front End Electronics, Marina Artuso

Physics - All Scholarship

We report on the design and testing of novel mixed analog and digital front end ASICs custom made for the single photon detectors considered for the BTeV RICH system. The key features are reviewed, as well as results achieved using electronics bench tests and beam studies.

Conducting Polymer And Hydrogenated Amorphous Silicon Hybrid Solar Cells, Evan L. Williams, Ghassan E. Jabbour, Qi Wang, Sean E. Shaheen, Eric A. Schiff

Physics - All Scholarship

An organic-inorganic hybrid solar cell with a p-i-n stack structure has been investigated. The p-layer was a spin coated film of PEDOT:PSS poly 3,4-ethylenedioxythiophene polystyrenesulfonate. The i-layer was hydrogenated amorphous silicon a-Si:H, and the n-layer was microcrystalline silicon c-Si. The inorganic layers were deposited on top of the organic layer by the hot-wire chemical vapor deposition technique at 200 °C. These hybrid devices exhibited open circuit voltages VOC as large as 0.88 V and solar conversion efficiencies as large as 2.1%. Comparison of these devices with those incorporating a-SiC:H:B p-layers indicates that the organic layer is acting as an electrically …

Hole Drift-Mobility Measurements In Microcrystalline Silicon, T. Dylla, F. Finger, Eric A. Schiff

Physics - All Scholarship

We have measured transient photocurrents on several p-i-n solar cells based on microcrystalline silicon. For two of these samples, we were able to obtain conclusive hole drift-mobility measurements. Despite the predominant crystallinity of these samples, temperature-dependent measurements were consistent with an exponential-bandtail trapping model for transport, which is usually associated with noncrystalline materials. We estimated valence bandtail widths of about 31 meV and hole band mobilities of 1–2 cm2 /V s. The measurements support mobility-edge transport for holes in these microcrystalline materials, and broaden the range of materials for which mobility-edge transport corresponds to an apparently universal band mobility of …

Temperature-Dependent Open-Circuit Voltage Measurements And Light-Soaking In Hydrogenated Amorphous Silcon Solar Cells, Jianjun Liang, Eric A. Schiff, S. Guha, Baojie Yan, Jeff Yang

Physics - All Scholarship

We present temperature-dependent measurements of the open-circuit voltage VOC(T) in hydrogenated amorphous silicon nip solar cells prepared at United Solar. At room-temperature and above, VOC measured using near-solar illumination intensity differs by as much as 0.04 V for the as-deposited and light-soaked states; the values of VOC for the two states converge below 250 K. Models for VOC based entirely on recombination through deep levels (dangling bonds) do not account for the convergence effect. The convergence is present in a model that assumes the recombination traffic in the as-deposited state involves only bandtails, but which splits the recombination traffic fairly …

Light-Soaking Effects On The Open-Circuit Voltage Of A-Si:H Solar Cells, Jianjun Liang, Eric A. Schiff, S. Guha, Baojie Yan, J. Yang

Physics - All Scholarship

We present measurements on the decline of the open-circuit voltage VOC in a-Si:H solar cells during extended illumination (light-soaking) at 295 K. We used a near-infrared laser that was nearly uniformly absorbed in the intrinsic layer of the cell. At the highest photogeneration rate (about 2x1021 cm-3), a noticeable decline (0.01 V) occurred within about 10 minutes; VOC stabilized at 0.04 V below its initial value after about 200 hours. We found that both the kinetics and the magnitudes of VOC are reasonably consistent with the predictions of a calculation combining a bandtail+defect picture for recombination and a hydrogen-collision model …

Evidence For Multiple Polytypes Of Semiconducting Boron Carbide (C2B10) From Electronic Structure, Petru Lunca-Popa, Jennifer I. Brand, Snjezana Balaz, Luis G. Rosa, Neil M. Boag, Mengjun Bai, Brian W. Robertson, Peter A. Dowben

Peter Dowben Publications

Boron carbides fabricated via plasma enhanced chemical vapor deposition from different isomeric source compounds with the same C₂B₁₀H₁₂ closo-icosahedral structure result in materials with very different direct (optical) band gaps. This provides compelling evidence for the existence of multiple polytypes of C₂B₁₀ boron carbide and is consistent with electron diffraction results.

Water Current, Volume 37, No. 1. Winter 2005

Water Current Newsletter

Contents

• Gleick Headlines April Water Management and Policy Conference by Steve Ress

• From the Director

• Meet the Faculty

• Planning for June Water and Natural Resources Tour Taking Shape by Steve Ress

• UNL Water and Natural Resources Research Lectures Continue Through April by Steve Ress

• UNL Water Center Passes USGS Five-Year Review Process

• Report Emphasizes Areas for Water Research in Coming Years

• Missouri Water Research Center, University of Missouri-Columbia

• Water News Briefs

• 2004 Gains in Water Science Lab Capabilities and Methods by Daniel D. Snow, Ph.D.

Characterization Of Gas Chemistry And Noble-Gas Isotope Ratios Of Inclusion Fluids In Magmatic-Hydrothermal And Magmatic-Steam Alunite, Robert O. Rye, G.P. Landis

Geochemistry of Sulfate Minerals: A Tribute to Robert O. Rye

Chemical and isotope data were obtained for the active gas and noble gas of inclusion fluids in coarse-grained samples of magmatic-hydrothermal and magmatic-steam alunite from well-studied deposits (Marysvale, Utah; Tambo, Chile; Tapajo´s, Brazil; Cactus, California; Pierina, Peru), most of which are discussed in this Volume. Primary fluid inclusions in the alunite typically are less than 0.2 µm but range up to several micrometers. Analyses of the active-gas composition of these alunitehosted inclusion fluids released in vacuo by both crushing and heating indicate consistent differences in the compositions of magmatic-hydrothermal and magmatic-steam fluids. The compositions of fluids released by crushing were …

Evolution Of The Magmatic-Hydrothermal Acid-Sulfate System At Summitville, Colorado: Integration Of Geological, Stable-Isotope, And Fluid-Inclusion Evidence, Philip M. Bethke, Robert O. Rye, Roger E. Stoffregen, Peter G. Vikre

Geochemistry of Sulfate Minerals: A Tribute to Robert O. Rye

The Summitville Au–Ag–Cu deposit is a classic volcanic dome-hosted high-sulfidation deposit. It occurs in the Quartz Latite of South Mountain, a composite volcanic dome that was emplaced along the coincident margins of the Platoro and Summitville calderas at 22.5±0.5 Ma, penecontemporaneous with alteration and mineralization. A penecontemporaneous quartz monzonite porphyry intrusion underlies the district and is cut and overlain by pyrite–quartz stockwork veins with traces of chalcopyrite and molybdenite. Alteration and mineralization proceeded through three hypogene stages and a supergene stage, punctuated by at least three periods of hydrothermal brecciation. Intense acid leaching along fractures in the quartz latite produced …

A Review Of The Stable-Isotope Geochemistry Of Sulfate Minerals In Selected Igneous Environments And Related Hydrothermal Systems, Robert O. Rye

Geochemistry of Sulfate Minerals: A Tribute to Robert O. Rye

The stable-isotope geochemistry of sulfate minerals that form principally in I-type igneous rocks and in the various related hydrothermal systems that develop from their magmas and evolved fluids is reviewed with respect to the degree of approach to isotope equilibrium between minerals and their parental aqueous species. Examples illustrate classical stable-isotope systematics and principles of interpretation in terms of fundamental processes that occur in these systems to produce (1) sulfate in igneous apatite, (2) igneous anhydrite, (3) anhydrite in porphyry-type deposits, (4) magmatic-hydrothermal alunite and closely related barites in high-sulfidation mineral deposits, (5) coarse-banded alunite in magmatic-steam systems, (6) …

The Stability And Oxidation Resistance Of Iron- And Cobalt-Based Magnetic Nanoparticle Fluids Fabricated By Inert-Gas Condensation, Nguyen H. Hai, Raymond Lemoine, Shaina Remboldt, Michelle A. Strand, Steve Wignall, Jeffrey E. Shield, Diandra Leslie-Pelecky

Diandra Leslie-Pelecky Publications

Magnetic nanoparticle fluids have numerous biomedical applications, including magnetic imaging, drug delivery, and hyperthemia treatment for cancer. Ideal magnetic nanoparticle fluids have well-separated, biocompatible nanoparticles with a small size distribution that form a stable colloid. We have combined inert-gas condensation, which produces nanoparticles with low polydispersity, with deposition directly into a surfactant-laden fluid to prevent agglomeration. Iron, cobalt, and iron-nitride nanoparticle fluids fabricated using inert-gas condensation have with mean particle sizes from 5-50 nm and remain stable over long periods of time. Iron and cobalt nanoparticles oxidize on exposure to air, with oxidation rates dependent on surfactant type and concentration. …