Physical Sciences and Mathematics Commons^™

Center Of Ecological Studies Feasibility Project, Suzanne Williams, Jill Leonard

Grant

No abstract provided.

Coexistence And Transition Between Cassie And Wenzel State On Pillared Hydrophobic Surface, Takahiro Koishi, Kenji Yasuoka, Shigenori Fujikawa, Toshikazu Ebisuzaki, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Water droplets on rugged hydrophobic surfaces typically exhibit one of the following two states: (i) the Wenzel state [Wenzel RN (1936) Ind Eng Chem 28:988–994] in which water droplets are in full contact with the rugged surface (referred as the wetted contact) or (ii) the Cassie state [Cassie, ABD, Baxter S (1944) Trans Faraday Soc 40:546–551] in which water droplets are in contact with peaks of the rugged surface as well as the “air pockets” trapped between surface grooves (the composite contact). Here, we show large-scale molecular dynamics simulation of transition between Wenzel state and Cassie state of water droplets …

Android Based Mobile Computing, Collaborative Project

Dyson College- Seidenberg School of CSIS : Collaborative Projects and Presentations

This entry adheres to the use of the quad chart template to provide a succinct description only of the current research project undertaken by the participants. It provides for the following information

1. Participants and Affiliations
2. Overall Project Goals
3. Illustrative picture
4. Specific research/artistic/pedagogic foci

Electron Transport And Sensor Characteristics Of Tin Dioxide Based Nanocrystalline Materials, Allen Chaparadza

Dissertations and Theses

Wide band gap, transparent semiconductor Sn0₂ is an n-type conductor and is widely used as a sensor material as well as transparent electrode material e.g. in solar cells and flat panel displays. Recent discovery of p-type doping with Li has opened exciting possibilities in new classes of sensors and transparent nanoelectronic devices. Li-doping in SnO₂ nanoparticles was explored through a gel-sol method of synthesis to examine the influence of reaction conditions such as pH, dopant concentration, and calcination temperature. The Li doping in nanoparticles was characterized using nuclear reaction analysis and the nanostructure with high-resolution electron transmission microscopy …

Economic Assessment Of Best Management Practices In The Mara River Basin : Toward Implementing Payment For Watershed Services, George Atisa

FIU Electronic Theses and Dissertations

The Mara River in East Africa is currently experiencing poor water quality and increased fluctuations in seasonal flow. This study investigated technically effective and economically viable Best Management Practices for adoption in the Mara River Basin of Kenya that can stop further water resources degradation.

A survey of 155 farmers was conducted in the upper catchment of the Kenyan side of the river basin. Farmers provided their assessment of BMPs that would best suit their farm in terms of water quality improvement, economic feasibility, and technical
suitability. Cost data on different practices from farmers and published literature was collected. The …

Simple Square Smoothing Regularization Operators, Lothar Reichel, Qiang Ye

Mathematics Faculty Publications

Tikhonov regularization of linear discrete ill-posed problems often is applied with a finite difference regularization operator that approximates a low-order derivative. These operators generally are represented by a banded rectangular matrix with fewer rows than columns. They therefore cannot be applied in iterative methods that are based on the Arnoldi process, which requires the regularization operator to be represented by a square matrix. This paper discusses two approaches to circumvent this difficulty: zero-padding the rectangular matrices to make them square and extending the rectangular matrix to a square circulant. We also describe how to combine these operators by weighted averaging …

Estimating Subject-Specific Dependent Competing Risk Profile With Censored Event Time Observations, Yi Li, Lu Tian, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.

Active Site Chemistry Of The Nadph-Dependent:7-Cyano-7-Deazaguanine (Preq0) Nitrile Oxidoreductase, An Enzyme Involved In Queuosine Biosynthesis, Bobby Wai Keung Lee

Dissertations and Theses

Queuosine (Q) is a modified nucleoside found at the wobble position of bacterial and eukaryotic transfer RNAs (tRNAs) that are specific for the amino acids tyrosine, histidine, aspartate and asparagine. A recently discovered enzyme in the biosynthetic pathway of Q, the NADPH-dependent 7-cyano-7-deazaguanine oxidoreductase (QueF), carries out the two-fold, four-electron reduction of Q precursor preQ0 to preQ1 and represents the first example of the enzymatic conversion of the nitrile functional group to an amine. Presented herein are kinetic, spectroscopic, mutational, biophysical, and isotope labeling studies directed at the elucidation of the chemical and kinetic mechanisms of this new class of …

Ionic Liquids Containing The Tris(Pentafluoroethyl)Trifluorophosphate Anion: A New Class Of Highly Selective And Ultra Hydrophobic Solvents For The Extraction Of Polycyclic Aromatic Hydrocarbons Using Single Drop Microextraction, Cong Yao, William R. Pitner, Jared L. Anderson

Jared L. Anderson

A new class of ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate (FAP) anion are paired with imidazolium, phosphonium, and pyrrolidinium cations and used as extraction solvents in direct immersion single drop microextraction (SDME) studies coupled to high performance liquid chromatography (HPLC). The selectivity and sensitivity of the extraction method can be tuned and manipulated by varying the cationic component of the IL, thereby providing larger enrichment factors for a variety of analytes, including polycyclic aromatic hydrocarbons (PAHs). Compared to other hydrophobic ILs containing the hexafluorophosphate (PF6−) and bis[(trifluoromethyl)sulfonyl]imide (NTf2−) anions, FAP-based ILs are significantly more hydrophobic and hydrolytically stable permitting them …

Mapping The Dark Side With Deimos: Globular Clusters, X-Ray Gas, And Dark Matter In The Ngc 1407 Group, Aaron J. Romanowsky, J. Strader, L. Spitler, R. Johnson, J. P. Brodie, D. A. Forbes, T. Ponman

Faculty Publications

NGC 1407 is the central elliptical in a nearby evolved group of galaxies apparently destined to become a galaxy cluster core. We use the kinematics of globular clusters (GCs) to probe the dynamics and mass profile of the group's center, out to a radius of 60 kpc (~10 galaxy effective radii)—the most extended data set to date around an early-type galaxy. This sample consists of 172 GC line-of-sight velocities, most of them newly obtained using Keck/DEIMOS, with a few additional objects identified as dwarf-globular transition objects or as intragroup GCs. We find weak rotation for the outer parts of the …

Cancellation Properties Of Direct Products Of Digraphs, Katherine Toman

Theses and Dissertations

This paper discusses the direct product cancellation of digraphs. We define the exact conditions on G such that GxK=HxK implies G=H. We focus first on simple equations such as GxK_2=HxK_2 where K_2 denotes a single arc and then extend this to the more general situation, GxK = HxK. Our results are achieved by using a “factorial” operation on graphs, which is in some sense analogous to the factorial of an integer.

Development And Investigation Of Intensity-Modulated Radiation Therapy Treatment Planning For Four-Dimensional Anatomy, Yelin Suh

Theses and Dissertations

Lung cancer is the leading cause of cancer-related deaths worldwide. Radiotherapy is one of the main treatment modalities of lung cancer. However, the achievable accuracy of radiotherapy treatment is limited for lung-based tumors due to respiratory motion. Four-dimensional radiotherapy explicitly accounts for anatomic motion by characterizing the motion, creating a treatment plan that accounts for this motion, and delivering this plan to the moving anatomy. This thesis focuses on the current problems and solutions throughout the course of four-dimensional radiotherapy. For characterization of respiratory-induced motion, patient tumor motion data were analyzed. It is shown that tumor motion can be significant …

Extremal Random Walks On Trees, Meng Wang

Mathematics, Statistics, and Computer Science Honors Projects

We study random walks on trees, where we iteratively move from one vertex to a randomly chosen adjacent vertex. We study two quantities arising in random walks: the hitting time and the mixing time. The hitting time is the expected number of steps to walk between a chosen pair of vertices. The mixing time is the expected number of steps before the distribution of the current state is proportional to its degree. For a fixed tree size, we prove that the star is the unique minimizing structure and the path is the unique maximizing structure for both quantities.

Simulation Of The Zero Temperature Behavior Of A 3-Dimensional Elastic Medium, Alan Middleton, David Mcnamara, Chen Zeng

Physics - All Scholarship

We have performed numerical simulation of a 3-dimensional elastic medium, with scalar displacements, subject to quenched disorder. We applied an efficient combinatorial optimization algorithm to generate exact ground states for an interface representation. Our results indicate that this Bragg glass is characterized by power law divergences in the structure factor $S(k)\sim A k^{-3}$. We have found numerically consistent values of the coefficient $A$ for two lattice discretizations of the medium, supporting universality for $A$ in the isotropic systems considered here. We also examine the response of the ground state to the change in boundary conditions that corresponds to introducing a …

Application Layer End-To-End Arguments: From Ends To Means, And Beyond Network Neutrality, Matthias Bärwolff

Matthias Bärwolff

This paper observes that the ultimate objectives of the end-to-end arguments do not necessarily entail a preference for having functions with the end hosts rather than with the network. The horizontal connotations of the end-to-end metaphor collapse when it is elevated to an application layer argument featuring strong "second order" objectives such as those pursued by network neutrality adherents. An internet that serves those ends will have to allow for ISPs to tussle with end users over economic value and surplus considerations, and acknowledge the beneficial rôle of the resulting transactions between the internet’s stakeholders.

Optimization Of A Polydimethylsiloxane Based Passive Sampler Of Common Household Volatile Organic Compounds, Jennifer Lynn Osborne

Undergraduate Honors Thesis Collection

Dangerous volatile organic compounds, or VOCs, can accumulate as indoor air pollution within homes causing health problems in the habitants. In order to determine the concentration of VOCs in such areas a field-deployable sampler is necessary. The focus of this work has been to develop an inexpensive, reusable, sensitive fielddeployable passive sampler for monitoring VOCs in indoor air. We have devised a sampler that uses polydimethylsiloxane (PDMS), which is a common inexpensive, nonpolar adsorbent. The sampler is comprised of an aluminum bottle coated with the PDMS. In operation, the coated portion is exposed to the air to be sampled. The …

Metal Contacts On Bulk Zno Crystal Treated With Remote Oxygen Plasma, Z-Q. Fang, B. Claflin, David C. Look, Y. F. Dong, L. Brillson

Physics Faculty Publications

To study the quality of thin metal/ZnO Schottky contacts (SCs), temperature-dependent current-voltage (I-V), capacitance-voltage, deep level transient spectroscopy, and photoluminescence measurements were performed using bulk, vapor-phase ZnO, treated by remote oxygen plasma (ROP). Au/ZnO and Pd/ZnO contacts on both O and Zn faces are compared as a function of the ROP processing sequence and duration. We find that (i) as the duration of ROP treatment increases from 2 to 4 h, Au/ZnO contacts on the Zn face, deposited before ROP treatment, become rectifying, while those on the O face remain Ohmic; (ii) with long-term ROP …

Implementing An Sap Transportation Management System Solution: A Case Study, Debra F. Wycoff

Regis University Student Publications (comprehensive collection)

System implementations sometimes result in unexpected system behavior. This paper is a case study focusing on an SAP transportation management system implementation that resulted in unexpected system behavior and a different user interface than the one that had been tested. Through a grounded theory approach the case study researched specific data gathered from the project documentation and from interviews with key system developers and a primary business user. The findings from the study can be applied to other similar system implementation projects and also provide some insights related to additional research that could be expanded. Please note that the name …

Shrinking The Janzen-Connell Doughnut: Consequences Of An Invasive Multiplier (Microstegium Vimineum) On The Mid-Canopy In A Mixed Pine-Oak Forest, Rebekha Shaw

Theses and Dissertations

Introduction of invasive species can alter seed fate predictions made by the Janzen-Connell Escape Hypothesis (JCEH). The JCEH states that there is a suitable region around a plant that is ideal for seed germination, growth, and recruitment. Seeds dispersed too close to the maternal plant are subject to competition from the maternal individual and perhaps density-dependent predation, whereas seeds dispersed further away may end up in suboptimal habitats. Invasive species may change the amount of these suitable habitats for native plants by creating unsuitable light environments and as a result, may influence the size of the ideal recruitment zone surrounding …

Density Functional Investigations Of Pure And Ligated Clusters, Kristen Casalenuovo

Theses and Dissertations

Atomic clusters are attractive candidates for building motifs for new nano-assembled materials with desirable properties. At this nano-regime of matter, the size, shape, and composition of clusters changes their electronic structure and hence their properties. Computational modeling must work hand in hand with experiment to provide robust descriptions of the geometries and energetics of atomic clusters and how they might behave in a nano-assembled material. To this end, we have investigated three distinct species as model systems: antimony oxides SbxOy (x = 1, 2; y = 0 - 3), metal ion-solvent complexes Mm(NH3)n (M = Bi, Pb; m = 1 …

Prediction Of Persistence Of Fertilizer-Derived Cadmium In Oregon Agricultural Soils Using Equilibrium Modeling And Fertilizer Release Kinetics, Fungai Mukome

Dissertations and Theses

Organic farming has become a multimillion dollar industry and while much emphasis is put on subsequent fertilizer inputs onto these fields, very little consideration is given to the prior fertilization activities of these soils. For a farm to be certified organic it means no harmful chemicals have been applied for at least three years.

The overall hypothesis tested by this research was that equilibrium adsorption models can adequately represent the behavior of fertilizer-derived cadmium in Oregon agricultural soils and that such model results can be easily incorporated into risk assessment models, transport study models and persistence studies for organic or …

Uv Light-Induced Changes To The Surface Conduction In Hydrothermal Zno, B. Claflin, David C. Look

Physics Faculty Publications

High quality, bulk ZnO crystals grown by Tokyo Denpa using the hydrothermal process typically exhibit a room temperature carrier concentration in the 10¹³–10¹⁴ cm⁻³ range and a low mobility, conductive surface layer, observed at low temperature, with a sheet concentration on the order of 10¹²–10¹³ cm⁻². In the sample discussed here, bulk conduction is controlled by two donor levels at 50 and 400 meV with concentrations of 1.2×10¹⁶ and 1.5×10¹⁶ cm⁻³, respectively. Temperature-dependent photo-Hall-effect measurements, using blue/UV light, in vacuum show an increase in the surface sheet …

Polarity-Related Asymetry At Zno Surfaces And Metal Interfaces, Y. F. Dong, Z-Q. Fang, David C. Look, Daniel R. Doutt, M. J. Hetzer, L. J. Brillson

Physics Faculty Publications

Clean ZnO (0001) Zn- and (000(/1)) O-polar surfaces and metal interfaces have been systematically studied by depth-resolved cathodoluminescence spectroscopy, photoluminescence, current-voltage and capacitance-voltage measurements, and deep level transient spectroscopy. Zn-face shows higher near band edge emission and lower near surface defect emission. Even with remote plasma decreases of the 2.5 eV near surface defect emission, (0001)-Zn face emission quality still exceeds that of (000(/1))-O face. The two polar surfaces and corresponding metal interfaces also present very different luminescence evolution under low-energy electron beam irradiation. Ultrahigh vacuum-deposited Au and Pd diodes on as-received and O₂/He plasma-cleaned surfaces display not …

Autoscopy: Detecting Pattern-Searching Rootkits Via Control Flow Tracing, Ashwin Ramaswamy

Dartmouth College Master’s Theses

Traditional approaches to rootkit detection assume the execution of code at a privilege level below that of the operating system kernel, with the use of virtual machine technologies to enable the detection system itself to be immune from the virus or rootkit code. In this thesis, we approach the problem of rootkit detection from the standpoint of tracing and instrumentation techniques, which work from within the kernel and also modify the kernel's run-time state to detect aberrant control flows. We wish to investigate the role of emerging tracing frameworks (Kprobes, DTrace etc.) in enforcing operating system security without the reliance …

My Guild, My Team: Applying The Technology Capabilities Of Massively Multiplayer Online Games To Virtual Project Teams, Dawn Owens, Deepak Khazanchi

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

Millions of people are playing Massively Multiplayer Online Games (MMOGs), a computer game genre where thousands of players interact daily in highly complex virtual world environments. These players self-organize, develop skills, and acquire various roles. MMOGs appear to mirror the complexity of the business context while offering unique technology capabilities that appear to encourage group participation and emergent leadership. Managing a remote workforce across different time zones, geography and culture requires effective virtual collaboration and management of communication, coordination challenges and control issues. Therefore, the purpose of this paper is to explore the unique technology capabilities of MMOGs and propose …

Biogeochemical Behavior Of Dissolved Arsenic And Uranium Concentrations In Public Water Supply Wells, Kevin J. Mcvey

School of Natural Resources: Dissertations, Theses, and Student Research

Public water supply (PWS) wells currently contain dissolved uranium concentrations above the federally mandated maximum contaminant level (MCL) of 30 ppb (parts per billion) and dissolved arsenic concentrations above the 10 ppb MCL. Both uranium and arsenic are known to cause various forms of cancer in humans. Variations in total uranium concentrations in PWS wells in Nebraska indicate a relationship to the duration and rate of pumping in specific wells. Although total arsenic concentrations show some variability over time in specific wells, the relationship to pumping is not as clear. Previous studies show that iron and sulfur bacteria present in …

Novel Approach To Ocular Photoscreening, Kevin Charles Baker

Doctoral Dissertations

Photoscreening is a technique that is typically applied in mass pediatric vision screening due to advantage of its objective, binocular, and cost-effective nature. Through the retinal reflex image, ocular alignment and refractive status are evaluated. In the USA, this method has screened millions of preschool children in the past years. Nevertheless, the efficiency of the screening has been contentious. In this dissertation, the technique is reviewed and reexamined. Revisions of photoscreening technique are developed to detect and quantify strabismus, refractive errors, and high-order ocular aberrations. These new optical designs overcome traditional design deficiencies in three areas:

First, a Dynamic Hirschberg …

Towards Traceable Test-Driven Development, Jane Huffman Hayes, Alex Dekhtyar, David S. Janzen

Computer Science and Software Engineering

Key among the grand challenges in traceability are those that lead to achieving traceability as a by-product of the natural software development life cycle. This position paper profiles test-driven development (TDD), an emerging software development practice, in which automated tests and code satisfying them are developed in rapid succession over multiple iterations. Our position is that the nature of TDD offers unique opportunities for collecting traceability information throughout the TDD life cycle and that the provision of traceability information to the software developers during TDD will improve the process and the resulting software. We discuss the opportunities, challenges, and plans …

Quel Test For Two Linear Restrictions In The Nonlinear Models, Krishna K. Saha

Journal of Modern Applied Statistical Methods

An alternative Wald type test called the quel test is developed for two linear restrictions by finding the critical region based on the quel utilizing the repeated values of estimated parameters of interest under the null. Simulation shows evidence that the full quel test performs best in that it holds nominal level well and shows monotonic increasing power properties.

The Comparison Of Model Selection Criteria When Selecting Among Competing Hierarchical Linear Models, Tiffany A. Whittaker, Carolyn F. Furlow

Journal of Modern Applied Statistical Methods

Little is known about the use and accuracy of model selection criteria when selecting among a set of competing multilevel models. The practices of applied researchers and the performance of five model selection criteria are examined when selecting the correct multilevel model using simulation techniques.