Physical Sciences and Mathematics Commons^™

A Stratigraphic And Geochronologic Analysis Of The Morrison Formation/Cedar Mountain Formation Boundary, Utah, Brent W. Greenhalgh

Theses and Dissertations

The Lower Cretaceous Cedar Mountain Formation preserves several vertebrate faunas and has the potential of providing critical timing information pertaining to Early Cretaceous dinosaurs and the Sierran magmatic arc. Historically, the Morrison/Cedar Mountain contact and the duration of the unconformity between them have been difficult or impossible to determine because 1) the formations were deposited in similar environments, 2) the basal Cedar Mountain Formation is composed of reworked Morrison Formation, and 3) there are no radiometric ages for the lower Cedar Mountain Formation. A stratigraphic study through central Utah reveals a diagnostic suite of pedogenic and sedimentologic characters across the …

On The Potential For Ill-Logic With Logically Defined Outcomes, Xianbin Li, Brian S. Caffo, Daniel O. Scharfstein

Johns Hopkins University, Dept. of Biostatistics Working Papers

Logically defined outcomes are commonly used in medical diagnoses and epidemiological research. When missing values in the original outcomes exist, the method of handling the missingness can have unintended consequences, even if the original outcomes are missing completely at random. Complicating the issue is that the default behavior of standard statistical packages yields different results. In this paper, we consider two binary original outcomes, which are missing completely at random. For estimating the prevalence of a logically defined "or" outcome, we discuss the properties of four estimators: complete case estimator, all-available case estimator, maximum likelihood estimator (MLE), and moment-based estimator. …

The Structural Integrity Of Anion Binding Exosite I Of Thrombin Is Required And Sufficient For Timely Cleavage And Activation Of Factor V And Factor Viii, Michael A. Bukys, Tivadar Orban, Paul Y. Kim, Daniel O. Beck, Michael E. Nesheim, Michael Kalafatis

Chemistry Faculty Publications

Alpha-thrombin has two separate electropositive binding exosites (anion binding exosite I, ABE-I and anion binding exosite II, ABE-II) that are involved in substrate tethering necessary for efficient catalysis. Alpha-thrombin catalyzes the activation of factor V and factor VIII following discrete proteolytic cleavages. Requirement for both anion binding exosites of the enzyme has been suggested for the activation of both procofactors by alpha-thrombin. We have used plasma-derived alpha-thrombin, beta-thrombin (a thrombin molecule that has only ABE-II available), and a recombinant prothrombin molecule rMZ-II (R155A/R284A/R271A) that can only be cleaved at Arg(320) (resulting in an enzymatically active molecule that has only ABE-I …

Proven Cases Of A Generalization Of Serre's Conjecture, Jonathan H. Blackhurst

Theses and Dissertations

In the 1970's Serre conjectured a correspondence between modular forms and two-dimensional Galois representations. Ash, Doud, and Pollack have extended this conjecture to a correspondence between Hecke eigenclasses in arithmetic cohomology and n-dimensional Galois representations. We present some of the first examples of proven cases of this generalized conjecture.

Non-Destructive Recovery Of Voids Within A Three Dimensional Domain Using Thermal Imaging, Victor B. Oyeyemi

Mathematical Sciences Technical Reports (MSTR)

We develop an algorithm capable of detecting the presence of spherical voids in a thermally conducting object. In addition, the process recovers both the radii and locations of each void. Our method involves the application of a known steady state heat flux to the object's boundary and measurement of the induced steady state temperature on the boundary.

Evaluating Causal Effect Predictiveness Of Candidate Surrogate Endpoints, Peter B. Gilbert, Michael Hudgens

UW Biostatistics Working Paper Series

Most methods for evaluating surrogate endpoints measure validity in terms of net effects (i.e., treatment effects adjusted for the biomarker measured after randomization). Frangakis and Rubin (2002, Biometrics) criticized these approaches because net effects may reflect selection bias, and suggested an alternative definition of a surrogate endpoint (a "principal" surrogate) based on causal effects. For evaluating principal surrogates we introduce a causal effect predictiveness (CEP) surface, which quantifies how well causal treatment effects on the biomarker predict causal treatment effects on the clinical endpoint. The CEP surface is not identifiable in general due to missing potential outcomes. However, by incorporating …

The Interface Electronic Structure Of Thiol Terminated Molecules On Cobalt And Gold Surfaces, A. N. Caruso, Ligen Wang, Sitaram Jaswal, Evgeny Y. Tsymbal, Peter A. Dowben

Peter Dowben Publications

The bonding strength and interfacial electronic properties of biphenyldimethyldithiol (HS– CH₂–C₆H₄–C₆H₄–CH₂–SH) adsorbed on Au(111) and polycrystalline cobalt are identified from combined photoemission and inverse photoemission. In order to develop a better understanding of the thiol functional group to metal surface interaction, the stable orientation, bonding site, bonding strength and interfacial electronic properties of methylthiol (S–CH₃) adsorbed on Au(111) and Co(0001) have been determined by ab initio density functional calculations. Both experiment and theory suggest that thiol bonding to cobalt surfaces is stronger compared to gold surfaces. …

A Search For Low-Amplitude Variability Among Population I Main Sequence Stars, Michael Benjamin Rose

Theses and Dissertations

The detection of variable stars in open clusters is an essential component of testing stellar structure and evolution theories. The ability to detect low-amplitude variability among cluster members is directly related to the quality of the photometric results. Point Spread Function (PSF) fitting is the best method available for measuring accurate magnitudes within crowded fields of stars, while high-precision differential photometry is the preferred technique for removing the effects of atmospheric extinction and variable seeing. In the search for new variable stars among hundreds or thousands of stars, the Robust Median Statistic (RoMS) is proven more effective for finding low-amplitude …

On The Combinatorics Of Certain Garside Semigroups, Christopher R. Cornwell

Theses and Dissertations

In his dissertation, F.A. Garside provided a solution to the word and conjugacy problems in the braid group on n-strands, using a particular element that he called the fundamental word. Others have since defined fundamental words in the generalized setting of Artin groups, and even more recently in Garside groups. We consider the problem of finding the number of representations of a power of the fundamental word in these settings. In the process, we find a Pascal-like identity that is satisfied in a certain class of Garside groups.

Enhanced Electrospray Ionization For Mass Spectrometry And Ion Mobility Spectrometry, Li Zhou

Theses and Dissertations

Electrospray ionization (ESI) has become one of the most commonly used ionization techniques for mass spectrometry (MS) and ion mobility spectrometry (IMS), and efforts continue to improve its performance. ESI-MS is most recognized for its wide application to biomacromolecules where high sensitivity is of paramount importance. However, the major limitation in sensitivity with ESI-MS is due to its low ion transmission efficiency from the ESI source into the sampling orifice and through any stages utilized for transfer of ions from atmosphere to vacuum in the MS. A series of atmospheric pressure ion focusing interfaces were designed and implemented to enhance …

List Of Publications (Through June 2006): Roger Kirby, Roger D. Kirby

Roger Kirby Publications

Chronological list of 76 articles and 90 abstracts & proceedings publications by Roger Kirby, Department of Physics and Astronomy, University of Nebraska-Lincoln.

Mean Field Effects For Counterpropagating Traveling Wave Solutions Of Reaction-Diffusion Systems, Andrew J. Bernoff, R. Kuske, B. J. Matkowsky, V. Volpert

All HMC Faculty Publications and Research

In many problems, e.g., in combustion or solidification, one observes traveling waves that propagate with constant velocity and shape in the x direction, say, are independent of y and z and describe transitions between two equilibrium states, e.g., the burned and the unburned reactants. As parameters of the system are varied, these traveling waves can become unstable and give rise to waves having additional structure, such as traveling waves in the y and z directions, which can themselves be subject to instabilities as parameters are further varied. To investigate this scenario we consider a system of reaction-diffusion equations with a …

Electric Field Gradient Focusing-Uv Detection For Protein Analysis, Shu-Ling Lin

Theses and Dissertations

Electric field gradient focusing (EFGF) utilizes a hydrodynamic flow and an electric field gradient to focus and concentrate charged analytes and order them in a separation channel according to electrophoretic mobility. Elution can be achieved by decreasing the applied voltage or increasing the hydrodynamic flow. EFGF has the advantages of concentrating a large volume (100 micro-L) of target proteins without significant band broadening and simultaneously removing unwanted components from the sample. Two types of EFGF devices have been investigated to concentrate and separate proteins: a fiber-based EFGF device and a hydrogel-based EFGF device. Using fiber-based EFGF with UV detection, a …

Structure And Enhanced Reactivity Rates Of The D 5 H Sc3n@ C80 And Lu3n@ C80 Metallofullerene Isomers: The Importance Of The Pyracylene Motif, Ting Cai, Liaosa Xu, Mark Anderson, Zhongxin Ge, Tianming Zuo, Xuelei Wang, Marilyn Olmstead, Alan Balch, Harry Gibson, Harry Dorn

Mark R. Anderson

In this paper we report enhanced reactivity of the D5h isomers in comparison with the more common Ih isomers of Sc3N@C80 and Lu3N@C80 toward Diels−Alder and 1,3-dipolar tritylazomethine ylide cycloaddition reactions. Also, the structure of the D5h isomer of Sc3N@C80 has been determined through single-crystal X-ray diffraction on D5h-Sc3N@C80·Ni(OEP)·2benzene (OEP = octaethylporphyrin). The Sc3N portion of D5h-Sc3N@C80 is strictly planar, but the plane of these four atoms is tipped out of the noncrystallographic, horizontal mirror plane of the fullerene by 30°. The combination of short bond length and high degree of pyramidization for the central carbon atoms of the pyracylene …

Regression Analysis With Categorized Regression Calibrated Exposure: Some Interesting Findings, Ingvild Dalen, John Buonaccorsi, Petter Laake, Anette Hjartaker, Magne Thorese

John Buonaccorsi

Background: Regression calibration as a method for handling measurement error is becoming increasingly well-known and used in epidemiologic research. However, the standard version of the method is not appropriate for exposure analyzed on a categorical (e.g. quintile) scale, an approach commonly used in epidemiologic studies. A tempting solution could then be to use the predicted continuous exposure obtained through the regression calibration method and treat it as an approximation to the true exposure, that is, include the categorized calibrated exposure in the main regression analysis. Methods: We use semi-analytical calculations and simulations to evaluate the performance of the proposed approach …

Markov Approximations: The Characterization Of Undermodeling Errors, Lei Lei

Theses and Dissertations

This thesis is concerned with characterizing the quality of Hidden Markov modeling when learning from limited data. It introduces a new perspective on different sources of errors to describe the impact of undermodeling. Our view is that modeling errors can be decomposed into two primary sources of errors: the approximation error and the estimation error. This thesis takes a first step towards exploring the approximation error of low order HMMs that best approximate the true system of a HMM. We introduce the notion minimality and show that best approximations of the true system with complexity greater or equal to the …

Planning For Robust Reserve Networks Using Uncertainty Analysis, Atte Moilanen, Michael Runge, Jane Elith, Andrew J. Tyre, Yohay Carmel, Eric Fegraus, Brendan A. Wintle, Mark A. Burgman, Yakov Ben-Haim

School of Natural Resources: Faculty Publications

Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence–absence in sites, or on species-specific distributions of model predicted probabilities of occurrence in grid cells. There are practically always errors in input data—erroneous species presence–absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is …

Optimization Of Online Data Integration, J. R. Getta

Faculty of Informatics - Papers (Archive)

Online data integration is a process of continuous consolidation of data transmitted over the wide area networks with data already stored at a central site of a multidatabase system. The continuity of the process requires activation of data integration procedure each time a new portion of data is received at a central site. Efficient implementation of online data integration needs a new system of elementary operations on the increments and/or decrements of data and the intermediate results of integration. This work shows how to derive a new system of elementary operations for online data integration from a system of base …

Structural And Electronic Properties Of Gd@C60: All-Electron Relativistic Total-Energy Study, Jing Lu, Wai-Ning Mei, Yi Gao, Xiao Cheng Zeng, Mingwei Jing, Guangping Li, Renat F. Sabirianov, Zhengxiang Gao, Liping You, Jun Xu, Dapeng Yu, Hengqiang Ye

Xiao Cheng Zeng Publications

Water soluble Gd-based metallofullerenes have potential application as magnetic resonance imaging contrast agent due to its higher proton relaxivities and lower toxicity. In this letter, we have investigated the structural and electronic properties of Gd@ C₆₀, which is the most abundantly produced Gd-based metallofullerene in carbon arc process, by using all-electron relativistic density functional theory. It is found that the Gd³⁺ ion is bonded to a hexagonal ring of C₆₀ by electrostatic interaction. The total spin multiplicity of Gd@C₆₀ is S = 7. The Gd atomic orbitals are hybridized with the C₆₀ molecular orbitals.

Causal Comparisons In Randomized Trials Of Two Active Treatments: The Effect Of Supervised Exercise To Promote Smoking Cessation, Jason Roy, Joseph W. Hogan

COBRA Preprint Series

In behavioral medicine trials, such as smoking cessation trials, two or more active treatments are often compared. Noncompliance by some subjects with their assigned treatment poses a challenge to the data analyst. Causal parameters of interest might include those defined by subpopulations based on their potential compliance status under each assignment, using the principal stratification framework (e.g., causal effect of new therapy compared to standard therapy among subjects that would comply with either intervention). Even if subjects in one arm do not have access to the other treatment(s), the causal effect of each treatment typically can only be identified from …

Crown Ether-Metal ‘Sandwiches’ As Linking Mechanisms In Assembled Nanoparticle Films, Rebecca R. Pompano, Phillip G. Wortley, Leslie M. Moatz, D. J. Tognarelli, Kevin W. Kittredge, Michael C. Leopold

Chemistry Faculty Publications

Crown ether ligands attached to monolayer-protected clusters (MPCs) were assembled as films and the linking mechanism between the crown ether–metal ion–crown ether bridges between nanoparticles was examined. Thicker films exhibited a red shift in the absorbance maximum for the surface plasmon band which was attributed to the increasing aggregation and cross linking within the film. Quantized double layer charging peaks suggest that film growth is selective toward a specific core size or exchange rate, either of which affect the number of potential linking ligands in the periphery of the MPCs. Multi-layer growth of films was only achieved with metal ions …

Reinforcement Programming: A New Technique In Automatic Algorithm Development, Spencer Kesson White

Theses and Dissertations

Reinforcement programming is a new technique for using computers to automatically create algorithms. By using the principles of reinforcement learning and Q-learning, reinforcement programming learns programs based on example inputs and outputs. State representations and actions are provided. A transition function and rewards are defined. The system is trained until the system converges on a policy that can be directly implemented as a computer program. The efficiency of reinforcement programming is demonstrated by comparing a generalized in-place iterative sort learned through genetic programming to a sorting algorithm of the same type created using reinforcement programming. The sort learned by reinforcement …

Water Current, Volume 38, No. 3. Summer 2006

Water Current Newsletter

• Fall Colloquium Features Research, Programming By Lorrie Benson

• Seeing Toxic Algae Before it Blooms by Steve Ress

• From the Director

• Meet the Faculty

• UNL Forms Public Water Resources Advisory Panel

• Atema Joins Water Center as Student Worker

• Hardin Hall Rededicated; SNR Moves In

• Potential For Algae Blooms Continues; Test Kits Available From UNL Extension by Steve Ress

• Harder, NRDs Identify Research Needs

• 2006 Water and Natural Resources Tour

• Water News Briefs

• Internships Through the Water Resources Research Initiative

• UNL’s Jess Notes Lists Creative Uses for Instate and …

Algorithms For Sensor Chip Alignment To Blind Datums, Gary B. Hughes

Statistics

The sensor element of an imaging system should be mounted into its housing in such a way that the scene can be properly focused onto the sensor element's focal plane over the active area. Operational imaging requirements are forcing increasingly smaller tolerances on sensor alignment, and manufacturing systems must improve alignment capability to keep pace. Imaging system designs include reference datums that provide the basis for manufacturing alignment of optical components in each subassembly. Design constraints for alignment of the sensor element into the camera housing typically include x,y,z, clocking, and parallelism specifications. Measurement of z and parallelism positioning is …

Ricci Curvature Rigidity For Weakly Asymptotically Hyperbolic Manifolds, Vincent Bonini, Pengzi Miao, Jie Qing

Mathematics

A rigidity result for weakly asymptotically hyperbolic manifolds with lower bounds on Ricci curvature is proved without assuming that the manifolds are spin. The argument makes use of a quasilocal mass characterization of Euclidean balls from [9] [14] and eigenfunction compactification ideas from [12].

Factored Mdp Elicitation And Plan Display, Krol Kevin Mathias, Casey Lengacher, Derek Williams, Austin Cornett, Alex Dekhtyar, Judy Goldsmith

Computer Science and Software Engineering

The software suite we will demonstrate at AAAI ’06 was designed around planning with factored Markov decision processes (MDPs). It is a user-friendly suite that facilitates domain elicitation, preference elicitation, planning, and MDP policy display. The demo will concentrate on user interactions for domain experts and those for whom plans are made.

When Domains Require Modeling Adaptations, Krol Kevin Mathias, Cynthia Isenhour, Alex Dekhtyar, Judy Goldsmtih, Beth Goldstein

Computer Science and Software Engineering

The project described in this paper originated with an observation by the AI group at the University of Kentucky, that, individually, stochastic planning and constraint satisfaction are well-studied topics that resulted in efficient software, but stochastic planning in the presence of constraints on the domains and actions is an open area of investigation.

We were interested in an advising scenario, and chose the US social welfare system, a.k.a. “Welfare to Work” as our test domain. This required computer scientists to learn more than expected about social science as well as the local welfare system. This paper discusses the discipline specific …

Adsorption Of Transition-Metal Atoms On Boron Nitride Nanotube: A Density-Functional Study, Xiaojun Wu, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Adsorption of transition atoms on a (8,0) zigzag single-walled boron nitride (BN) nanotube has been investigated using density-functional theory methods. Main focuses have been placed on configurations corresponding to the located minima of the adsorbates, the corresponding binding energies, and the modified electronic properties of the BN nanotubes due to the adsorbates.We have systemically studied a series of metal adsorbates including all 3d transition-metal elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) and two group-VIIIA transition-metal elements (Pd and Pt). We found that many transition-metal atoms can be chemically adsorbed on the outer surface of the …

Staphylococcus Aureus Helicase But Not Escherichia Coli Helicase Stimulates S. Aureus Primase Activity And Maintains Initiation Specificity, Scott A. Koepsell, Marilynn A. Larson, Mark A. Griep, Steven H. Hinrichs

Mark Griep Publications

Bacterial primases are essential for DNA replication due to their role in polymerizing the formation of short RNA primers repeatedly on the lagging-strand template and at least once on the leading-strand template. The ability of recombinant Staphylococcus aureus DnaG primase to utilize different single-stranded DNA templates was tested using oligonucleotides of the sequence 5’-CAGA (CA) ₅ XYZ (CA) ₃-3’, where XYZ represented the variable trinucleotide. These experiments demonstrated that S. aureus primase synthesized RNA primers predominately on templates containing 5’-d(CTA)-3’ or TTA and to a much lesser degree on GTA-containing templates, in contrast to results seen with the Escherichia …

Magnetospheric Influence On The Moon's Exosphere, Jody K. Wilson, M. Mendillo, Harlan E. Spence

Physics & Astronomy

[1] Atoms in the thin lunar exosphere are liberated from the Moon's regolith by some combination of sunlight, plasma, and meteorite impact. We have observed exospheric sodium, a useful tracer species, on five nights of full Moon in order to test the effect of shielding the lunar surface from the solar wind plasma by the Earth's magnetosphere. These observations, conducted under the dark sky conditions of lunar eclipses, have turned out to be tests of the differential effects of energetic particle populations that strike the Moon's surface when it is in the magnetotail. We find that the brightness of the …