Physical Sciences and Mathematics Commons^™

On The Rolling Motion Of Viscous Fluid On A Rigid Surface, Xinli Wang

Dissertations

This thesis considers two closely related problems. First, the influence of insoluble surfactant at a moving contact line is considered. This work is mostly motivated by the air entrainment during the coating process where there is a three-phase contact point (e.g., air, liquid and solid). For moving contact line problems, when the fluid is assumed to be an incompressible Newtonian fluid and a no-slip boundary condition is enforced at the solid boundary, the non-integrable stress singularity arises at the contact line, which is physically unrealistic. The contact angle of 180° is considered as a special case in which the singularity …

A Mathematical And Computational Exploration Of The Effect Of The A-Current In Determining The Activity Phase Of Follower Neurons, Yu Zhang

Dissertations

Bursting oscillations are prevalent in neurons of central pattern generators (CPGs) that produce rhythmic motor activity, and the activity phase plays an important role in determining the normal or dysfunctional network output. The activity phase is the delay time-with respect to some reference time in each cycle and normalized by the oscillation cycle period-of the onset of action potentials by a neuron. This dissertation investigates how the A-current, in conjunction with other intrinsic properties, sets the activity phase of a neuron driven by inhibition.

This dissertation is divided into two major components. In the first component, methods of dynamical systems …

Flexible Electronics : Materials And Sensor Fabrication, Katherine J. Duncan

Dissertations

This dissertation demonstrates how to fabricate piezoelectric/pyroelectric thin films by using different printing techniques. These techniques could replace vacuum techniques for manufacturing piezoelectric/pyroelectric sensors. Ink-jet, screen and stencil printing techniques were developed to print these devices.

This work outlines attempts to develop a solution processable conductive ink for ink-jet printing. It then details the printing of commercial conductive ink on flexible substrates employing the three printing methods. Raman spectroscopy and Fourier transform infrared spectroscopy, are both used to investigate the structure of the P(VDF-TrFE) films. Optical microscopy is used to investigate the thickness and uniformity of the deposited films. The …

Developing A Virtual City For Emergency Preparedness Planning And Training, Jon K. Morgan

Theses

Existing techniques for emergency preparedness planning and training fail or lack the ability to convey training on a broad scale and timely fashion. Skill sets that are required for planning, mitigation, response and recovery issues are lost through information overload or failure to identify other channels in which to convey the information. In order to resolve some of the issues with currently existing methods such as tabletop training exercises (TTX), instructional video learning and full-scale exercises we can turn to virtual environments.

In a virtual environment teams can interact with their surroundings from the comfort of the office without having …

Development Of Pharmacophore And Comfa Studies For Sigma2 Receptor Ligands, Laura Ann Wirpsza

Theses

This study describes the development of a pharmacophore and CoMIFA model for sigma 2 (σ₂) receptor ligands. CoMFA studies were performed for 32 bioactive σ₂ receptor ligands using the radioligand [H 3] (+) DTG in the presence of pentazocine. The pharmacophore was derived using Distance Comparisons (DISCOtech) from eight partially to highly active ~2 receptor ligands. All 32 compounds were calculated in three methods: AMi, HFI3~21G*, and B3LYP/3~21G* methods. These methods run in Gaussian 98 determined the geometry optimization and electrostatic charges for each molecule. CoMFA maps were developed using SYBYL ver. 7.2 to compare the electrostatic …

The Role Of Short Term Synamptic Plasticity In Temporal Coding Of Neuronal Networks, Lakshmi Chandrasekaran

Dissertations

Short term synaptic plasticity is a phenomenon which is commonly found in the central nervous system. It could contribute to functions of signal processing namely, temporal integration and coincidence detection by modulating the input synaptic strength. This dissertation has two parts. First we study the effects of short term synaptic plasticity in enhancing coincidence detecting ability of neurons in the avian auditory brainstem. Coincidence detection means a target neuron has a higher firing rate when it receives simultaneous inputs from different neurons as opposed to inputs with large phase delays. This property is used by birds in sound localization. When …

Projecting Land Use Changes Using Parcel-Level Data : Model Development And Application To Hunterdon County, New Jersey, Florencio C. Ballesteros Jr.

Dissertations

This dissertation is to develop a parcel-based spatial land use change prediction model by coupling various machine learning and interpretation algorithms such as cellular automata (CA) and decision tree (DT). CA is a collection of cells that evolves through a number of discrete time steps according to a set of transition rules based on the state of each cell and the characteristics of its neighboring cells. DT is a data mining and machine learning tool that extracts the patterns of decision process from observed cell behaviors and their affecting factors. In this dissertation, CA is used to predict the future …

Roles Of Gap Junctions In Neuronal Networks, Joon Ha

Dissertations

This dissertation studies the roles of gap junctions in the dynamics of neuronal networks in three distinct problems. First, we study the circumstances under which a network of excitable cells coupled by gap junctions exhibits sustained activity. We investigate how network connectivity and refractory length affect the sustainment of activity in an abstract network. Second, we build a mathematical model for gap junctionally coupled cables to understand the voltage response along the cables as a function of cable diameter. For the coupled cables, as cable diameter increases, the electrotonic distance decreases, which cause the voltage to attenuate less, but the …

Synthesis And Characterization Of Plasma Enhanced Chemically Vapor Deposited Tantalum Films, Weizhong Chen

Dissertations

A low temperature inorganic plasma-enhanced chemical vapor deposition (PECVD) process has been developed for the growth of Ta using tantalum pentachloride (TaC15) as the preferred precursor and hydrogen as the reactant gas. Ta coatings were deposited at substrate temperature of 370-400 °C, reactor working pressures of 0.7-2 Ton, hydrogen carrier flow rate of 10-20 sccm, hydrogen reactant flow rates of 500 sccm, and plasma power ranging from 60 to 100W. Ta coatings were characterized with respect to their chemical, structural, and morphological properties by Auger electron spectroscopy (AES), x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), scanning …

Appropriation Of Privacy Management Within Social Networking Sites, Catherine Dwyer

Dissertations

Social networking sites have emerged as one of the most widely used types of interactive systems, with memberships numbering in the hundreds of millions around the globe. By providing tools for their members to manage an ever-changing set of relationships, social networking sites push a constant expansion of social boundaries. These sites place less emphasis on tools that limit social boundaries to enable privacy.

The rapid expansion of online social boundaries has caused privacy shockwaves. Privacy offline is enabled by constraints of time and space. Online, powerful search engines and long term digital storage means private data have no expiration …

Instabilities Of Volatile Films And Drops, Nebojsa Murisic

Dissertations

We report on instabilities during spreading of volatile liquids, with emphasis on the novel instability observed when isopropyl alcohol (IPA) is deposited on a monocrystalline silicon (Si) wafer. This instability is characterized by emission of drops ahead of the expanding front, with each drop followed by smaller, satellite droplets, forming the structures which we nickname “octopi” due to their appearance. A less volatile liquid, or a substrate of larger heat conductivity, suppress this instability. In addition, we examine the spreading of drops of water (DJW)-JPA mixtures on both Si wafers and plain glass slides, and describe the variety of contact …

Signal Transmission In Epithelial Layers, Filippo Posta

Dissertations

Cell signaling is at the basis of many biological processes such as development, tissue repair, and homeostasis. It can be carried out by different mechanisms. Here we are focusing on ligand mediated cell-to-cell signaling in which a molecule (ligand) is free to move into the extra-cellular medium. On the cell layer surface, it can bind to its molecule-specific receptors located on the cell plasma membrane. This mechanism is the subject of many experimental and theoretical studies on many model biological systems, such as the follicular epithelium of the Drosophila egg, which motivates this work.

Here, we present a general mathematical …

Data Allocation In Disk Arrays With Multiple Raid Levels, Jun Xu

Dissertations

There has been an explosion in the amount of generated data, which has to be stored reliably because it is not easily reproducible. Some datasets require frequent read and write access. like online transaction processing applications. Others just need to be stored safely and read once in a while, as in data mining. This different access requirements can be solved by using the RAID (redundant array of inexpensive disks) paradigm. i.e., RAIDi for the first situation and RAID5 for the second situation. Furthermore rather than providing two disk arrays with RAID 1 and RAID5 capabilities, a controller can be postulated …

The Impact Of Cultural Differences In Temporal Perception On Global Software Development Teams, Richard William Egan

Dissertations

This dissertation investigated the impact of cultural differences in temporal perception on globally dispersed software development teams. Literature and anecdotal evidence suggest that these temporal differences affect individual communication quality, which in turn will affect individual satisfaction and trust within global teams. Additionally, the temporal dispersion of the team was expected to affect an individual's sense of temporal disruption which, in turn, was expected to affect individual satisfaction and trust. Differences in temporal perception were expected to moderate this impact on perceived temporal disruption. A Fortune 100 Company that carried out software testing in Ireland, the United States, China and …

Dynamics Of Online Chat, Mihai Moldovan

Dissertations

Millions of people use online synchronous chat networks on a daily basis for work, play and education. Despite their widespread use, little is known about their user dynamics. For example, one does not know how many users are typically co-present and actively engaged in public interaction in the individual chat rooms of any of the numerous public Internet Relay Chat (IRC) networks found on the Internet; or what are the factors that constrain the boundaries of user activity inside those chat rooms. Failure to collect and present such data means there is a lack of a good understanding of the …

Perception Gaps And The Adoption Of Information Technology In The Clinical Healthcare Environment, Karen Hare

Dissertations

Implementation of information systems has lagged in many areas of clinical healthcare for a variety of reasons. Economics, data complexity and resistance are among the often quoted roadblocks. Research suggests that physicians play a major part in the adoption, use and diffusion of information technology (IT) in clinical settings. There are also other healthcare professionals, clinical and non-clinical, who play important roles in making decisions about the acquisition of information technology. In addition to these groups there are information technology professionals providing the services required within the healthcare field. Finally within this group are those IT professionals who have sufficient …

Abstraction, Extension And Structural Auditing With The Umls Semantic Network, Yan Chen

Dissertations

The Unified Medical Language System (UMLS) is a two-level biomedical terminological knowledge base, consisting of the Metathesaurus (META) and the Semantic Network (SN), which is an upper-level ontology of broad categories called semantic types (STs). The two levels are related via assignments of one or more STs to each concept of the META.

Although the SN provides a high-level abstraction for the META, it is not compact enough. Various metaschemas, which are compact higher-level abstraction networks of the SN, have been derived. A methodology is presented to evaluate and compare two given metaschemas, based on their structural properties. A consolidation …

Ontology Learning For The Semantic Deep Web, Yoo Jung An

Dissertations

Ontologies could play an important role in assisting users in their search for Web pages. This dissertation considers the problem of constructing natural ontologies that support users in their Web search efforts and increase the number of relevant Web pages that are returned. To achieve this goal, this thesis suggests combining the Deep Web information, which consists of dynamically generated Web pages and cannot be indexed by the existing automated Web crawlers, with ontologies, resulting in the Semantic Deep Web. The Deep Web information is exploited in three different ways: extracting attributes from the Deep Web data sources automatically, generating …

The Development And Evaluation Of Software To Foster Professional Development In Educational Assessment, Morgan C. Benton

Dissertations

This dissertation sought to answer the question: Is it possible to build a software tool that will allow teachers to write better multiple-choice questions? The thesis proceeded from the finding that the quality of teaching is very influential in the amount that students learn. A basic premise of this research, then, is that improving teachers will improve learning. With this foundation, the next question became what area of teaching to improve. The literature on educational assessment indicated that teachers lack competence at effective assessment, particularly in the area of multiple-choice question generation. It is likely that improvement in this area …

Taux : A System For Evaluating Sound Feedback In Navigational Tasks, Robert J. Lutz

Dissertations

This thesis presents the design and development of an evaluation system for generating audio displays that provide feedback to persons performing navigation tasks. It first develops the need for such a system by describing existing wayfinding solutions, investigating new electronic location-based methods that have the potential of changing these solutions and examining research conducted on relevant audio information representation techniques. An evaluation system that supports the manipulation of two basic classes of audio display is then described. Based on prior work on wayfinding with audio display, research questions are developed that investigate the viability of different audio displays. These are …

Some Combinational Optimization Problems On Radio Network Communication And Machine Scheduling, Xin Wang

Dissertations

The combinatorial optimization problems coming from two areas are studied in this dissertation: network communication and machine scheduling.

In the network communication area, the complexity of distributed broadcasting and distributed gossiping is studied in the setting of random networks. Two different models are considered: one is random geometric networks, the main model used to study properties of sensor and ad-hoc networks, where ri points are randomly placed in a unit square and two points are connected by an edge if they are at most a certain fixed distance r from each other. The other model is the so-called line-of-sight networks, …

User Evaluation Of The Performance Of Information Systems, Edward Mahinda

Dissertations

Information technologies (IT) are considered the primary survival factor for many organizations and the most critical success factor in businesses today. To justify the necessary investment in IT, user evaluation of information systems' performance in organizations is a key consideration. This research investigated a comprehensive and convenient means for end users to assess this performance.

Among the existing theories and models on the evaluation of information system performance based on intrinsic technological properties, the Web of System Performance (WOSP) model provides the most comprehensive basis for information system evaluation, and therefore merited further investigation. The research question was how well …

Complex Adaptive Systems Based Data Integration : Theory And Applications, Eliahu Rohn

Dissertations

Data Definition Languages (DDLs) have been created and used to represent data in programming languages and in database dictionaries. This representation includes descriptions in the form of data fields and relations in the form of a hierarchy, with the common exception of relational databases where relations are flat. Network computing created an environment that enables relatively easy and inexpensive exchange of data. What followed was the creation of new DDLs claiming better support for automatic data integration. It is uncertain from the literature if any real progress has been made toward achieving an ideal state or limit condition of automatic …

Leader Delegation And Trust In Global Software Teams, Suling Zhang

Dissertations

Virtual teams are an important work structure in global software development. The distributed team structure enables access to a diverse set of expertise which is often not available in one location, to a cheaper labor force, and to a potentially accelerated development process that uses a twenty-four hour work structure.

Many software teams are partially distributed, that is, part of the team is colocated. Such partially distributed global software teams are an important work structure in software development projects. However, little is known about what affects or improves team members’ motivation and job satisfaction in the partially distributed environment. This …

Automatic Prediction Of Solar Flares And Super Geomagnetic Storms, Hui Song

Dissertations

Space weather is the response of our space environment to the constantly changing Sun. As the new technology advances, mankind has become more and more dependent on space system, satellite-based services. A geomagnetic storm, a disturbance in Earth's magnetosphere, may produce many harmful effects on Earth. Solar flares and Coronal Mass Ejections (CMEs) are believed to be the major causes of geomagnetic storms. Thus, establishing a real time forecasting method for them is very important in space weather study.

The topics covered in this dissertation are: the relationship between magnetic gradient and magnetic shear of solar active regions; the relationship …

Rna Genome Annotation With A Focus On T. Brucei, Brett Bucci

Theses

The goal of this project is to identify untranslated regions (UTRs) and UTR-indicating patterns in the genome of T. brucei. T. brucei is an interesting organism, and as the cause of African sleeping sickness -- which infects 300,000-500,000 people and a significant number of cattle annually -- is currently the subject of considerable research. Using existing algorithms, several patterns have been found that may lead to more complete UTR annotations in the T. brucei genome. The most encouraging sequence is the 11-base sequence GAGGGIICG]TGGGG, which appears in five hypothetical genes near the tail. Discovery of several such sequences could guide …

Utr Prediction Programs For Trypanosoma Brucei, Maria Moutafis

Theses

In the past few years, the field of bioinformatics has seen a rapid increase in the need for use of various sequence analysis tools. As we advance in the fields of science and technology, new programs and software are constantly being developed in this field. Rapidly expanding gene sequence databases and rapidly evolving sequence analysis tools are providing researchers with ways to search for highly similar query sequences whether they are nucleotide, protein, or gene databases. This thesis will focus on sequence alignment tools, specifically concentrating on tools that help determine/predict non-coding regions of sequences also known as untranslated regions …

Structure And Thermochemistry Of Disulfide-Oxygen Species, Shyamala Pravin Pillai

Theses

Sulfur compounds are known to form aerosols that can counteract the greenhouse effect, and recent studies suggest that aerosols can also contribute to global warming; sulfur species are also known as major contributors to acid rain. Both of these atmospheric chemistry interactions involve SO₂, which is formed by oxidation of sulfur hydrocarbons and H₂S. This study describes the structure, internal rotor potentials, bond energies and determines thermochemical properties (Δ_fH°, S° and Cp(T)) on the S-S bridge system in the sulfur bridged molecules CH₃SSOH, CH₃SS(=O)H, HSSOH, HSS(=O)H and CH₃SSOCH …