Digital Commons Network^™

Freeze Casting Of Bioactive Glass And Ceramic Scaffolds For Bone Tissue Engineering, Qiang Fu

Doctoral Dissertations

"The main objectives of this dissertation were to explore the production of bioactive ceramic and glass scaffolds with oriented pore architectures by unidirectional freezing of suspensions, and to characterize the mechanical and biological performance of the scaffolds. Freezing of aqueous suspensions of hydroxyapatite (HA) or bioactive 13-93 glass particles resulted in the formation of scaffolds with a lamellar-type microstructure (pore width = 5-30 µm). The addition of polar organic solvents (such as 60 wt% dioxane) to the aqueous suspensions markedly changed the morphology and size of the oriented pores, giving scaffolds with a columnar-type microstructure and larger pre width (90-110 …

The Role Of Stochastic Resonance And Physical Constraints In The Evolution Of Foraging Strategy, Nathan Daniel Dees

Doctoral Dissertations

"This work represents a detailed study of the optimization of this process: foraging within a single, finite food patch for a limited amount of time. The work is an example of the computational algorithms of statistical physics being applied to the ecological field of foraging behavior. The analysis begins with an examination of the probability distributions observed in the movement parameters of the zooplankton, Daphnia. While foraging, these small aquatic organisms stochastically choose movement parameters with particular levels of variation, or noise, which are similar across several species. Here, related simulations consistently show that these noise levels may be adjusted …

Integrated Mining Of Feature Spaces For Bioinformatics Domain Discovery, Pradeep Chowriappa

Doctoral Dissertations

One of the major challenges in the field of bioinformatics is the elucidation of protein folding for the functional annotation of proteins. The factors that govern protein folding include the chemical, physical, and environmental conditions of the protein's surroundings, which can be measured and exploited for computational discovery purposes. These conditions enable the protein to transform from a sequence of amino acids to a globular three-dimensional structure. Information concerning the folded state of a protein has significant potential to explain biochemical pathways and their involvement in disorders and diseases. This information impacts the ways in which genetic diseases are characterized …

Imaging Of Buried Utilities By Ultra Wideband Sensory Systems, Arun Prakash Jaganathan

Doctoral Dissertations

Third-party damage to the buried infrastructure like natural gas pipelines, water distribution pipelines and fiber optic cables are estimated at $10 billion annually across the US. Also, the needed investment in upgrading our water and wastewater infrastructure over the next 20 years is estimated by Environmental Protection Agency (EPA) at $400 billion, however, non-destructive condition assessment technologies capable of providing quantifiable data regarding the structural integrity of our buried assets in a cost-effective manner are lacking. Both of these areas were recently identified several U.S. federal agencies as 'critical national need'. In this research ultra wideband (UWB) time-domain radar technology …

A Hyperbolic Two-Step Model Based Finite Difference Method For Studying Thermal Deformation In Three-Dimensional Micro Spheres Exposed To Ultrashort-Pulsed Lasers, Pan Wang

Doctoral Dissertations

Ultrashort-pulsed lasers with pulse durations of the order of sub-picoseconds to femtoseconds possess the capabilities in limiting the undesirable spread of the thermal process zone in a heated sample. Because of this, ultrashort-pulsed lasers have been attracting worldwide interest in science and engineering. The success of ultrashort-pulsed lasers in real application relies on: (1) well characterized pulse width, intensity and experimental techniques; (2) reliable microscale heat transfer models; and (3) prevention of thermal damage. Laser damage induced by ultrashort-pulsed lasers occurs after the heating pulse is over, since the pulse duration time is extremely short and the heat flux is …

A Finite Difference Method For Studying Thermal Deformation In Three-Dimensional Thin Films Exposed To Ultrashort Pulsed Lasers, Suyang Zhang

Doctoral Dissertations

Thermal analysis related to ultrashort-pulsed lasers has been intensely studied in science and engineering communities in recent years, because the pulse duration of ultrashort-pulsed lasers is only the order of sub-picoseconds to femtoseconds, and the lasers have exclusive capabilities in limiting the undesirable spread of the thermal process zone in the heated sample. Studying the thermal deformation induced by ultrashort-pulsed lasers is essential for preventing thermal damage. For the ultrashort-pulsed laser, the thermal damage is different from that caused by the long pulsed lasers and cracks occur after heating.

This dissertation presents a new finite difference method for studying thermal …

Attitudes Related To Ceo Compensation, Donald S. White

Doctoral Dissertations

This dissertation examines attitudes of individuals related to Chief Executive Officer (CEO) compensation within the context of interactions between organizational variables (level of employee pay, firm performance, and corporate social responsibility) and individual-level variables (equity sensitivity, race similarity to CEO, and respondent's pay). Vignettes (see Appendix A) were created in which respondents will have an opportunity to express their opinions on the distributive justice of CEO pay. The CEOs presented in the vignettes represented non-specific companies and had the same level of high total compensation. The respondents provided opinions of CEO pay and information about their own pay on a …

Tin Dioxide Nanoparticle Based Sensor Integrated With Microstrip Antenna For Passive Wireless Ethylene Sensing, Mercyma Deeba Balachandran

Doctoral Dissertations

In this dissertation, we present the development and integration of a passive ethylene gas sensor with triangular microstrip patch antenna for wireless monitoring of climacteric fruit freshness. The existing ethylene sensors are mostly SnO2 resistor based active sensors, fabricated on rigid substrates requiring high fabrication temperatures and cannot be used for wireless applications. The proposed passive ethylene gas sensor is a novel nanoparticle based SnO2 capacitive sensor which, unlike the other existing SnO2resistor based active thick film and thin film sensors, consists of 10 nm to 15 nm SnO2 nanoparticles coated as a thin dielectric film of 1300 nm thickness. …

Nanoengineered Templates For Controlled Delivery Of Bioactive Compounds, Nalinkanth Ghone Veerabadran

Doctoral Dissertations

The significance of any drugs, therapeutic proteins, or any bioactive compounds, is based not only on their effects on diseases but also on how specifically, how readily, how controllable and how prolonged their effects on the disease without having any side effects. Thus the techniques involved in the drug encapsulation and its controlled release for a longer duration of time form one of the important processes of drug reformulation. In recent years nanoparticles have created overwhelming attention for delivering drugs by nanoencapsulation. The smaller size of nanoparticles has longer circulation time and higher cellular uptake when compared with larger size …

A Simulation Of The Neural Action Potential Under The Influence Of Acetylcholinesterase Inhibitors Modeled In The Neuromuscular Junction, Frank Jenkins

Doctoral Dissertations

The rise of terrorism has created an interest in better ways to detect when humans are exposed to neurotoxins, especially nerve gases developed for military use, most of which are acetylcholinesterase inhibitors. Many current methods of detection are based on mass spectrometry, a method that is cumbersome and not particularly robust when used as an early warning method. The detection of acetylcholinesterase inhibitors would benefit from a combined model of the processes occurring in the neuromuscular junction between the presynaptic action potential and the motor end-plate action potential that includes the kinetics of acetylcholine and acetylcholinesterase in the synaptic cleft. …

Poly(Ethylenedioxythiophene) Based Electronic Devices For Sensor Applications, Jie Liu

Doctoral Dissertations

Organic electronic devices, based on Poly (3,4-ethylenedioxythiophene)-Poly (styrene sulfonic acid) (PEDOT-PSS) as the active layer for sensor applications, have been studied. Two sets of sensors have been developed. In one case, sensors consisting of PEDOT-PSS resistors have been realized and demonstrated for soil moisture monitoring. The resistor model for the soil moisture sensor enables the sensor device to be fabricated at low cost and easily tested with a simple structure. Unlike the large dimension device used in Time Domain Reflectometry (TDR), the sensors are small and are capable of capturing microscale behavior of moisture in soil which is useful for …

Failure Analysis And Reliability -Aware Resource Allocation Of Parallel Applications In High Performance Computing Systems, Narasimha Raju Gottumukkala

Doctoral Dissertations

The demand for more computational power to solve complex scientific problems has been driving the physical size of High Performance Computing (HPC) systems to hundreds and thousands of nodes. Uninterrupted execution of large scale parallel applications naturally becomes a major challenge because a single node failure interrupts the entire application, and the reliability of a job completion decreases with increasing the number of nodes. Accurate reliability knowledge of a HPC system enables runtime systems such as resource management and applications to minimize performance loss due to random failures while also providing better Quality Of Service (QOS) for computational users.

This …

Wireless Sensor Network Modeling Using Modified Recurrent Neural Network: Application To Fault Detection, Azzam Issam Moustapha

Doctoral Dissertations

Wireless Sensor Networks (WSNs) consist of a large number of sensors, which in turn have their own dynamics. They interact with each other and the base station, which controls the network. In multi-hop wireless sensor networks, information hops from one node to another and finally to the network gateway or base station. Dynamic Recurrent Neural Networks (RNNs) consist of a set of dynamic nodes that provide internal feedback to their own inputs. They can be used to simulate and model dynamic systems such as a network of sensors.

In this dissertation, a dynamic model of wireless sensor networks and its …

Fabrication Of Bioactive Osteogenic Controlled-Release Systems, Cellular Platforms, And Cellular Capsules Using Layer -By -Layer Nanoassembly, Skylar Stewart-Clark

Doctoral Dissertations

There is an ever-increasing awareness that the field of tissue engineering offers many potential solutions to clinical problems. While advances along these lines have been made, the design and implementation of an "off the shelf" tissue is yet to be realized. Thus, the objectives of this work were largely aimed at the design and fabrication of biocompatible, bioactive structures which could be integrated into existing biomaterial products.

The electrostatic layer-by-layer (LbL) self-assembly technique was used to incorporate biologically relevant molecules within controlled release systems, cell culture platforms, and 3-D cellular capsules. Two delivery systems were investigated to determine the release …

Acquisition Of Cardiac Control Parameters From Whole Vagus Nerve Recordings, Marcia A. Pool

Doctoral Dissertations

Heart rate varies continuously depending on the amount of activity being performed or the emotional state of an individual. Both branches of the autonomic nervous system work to alter heart rate depending on the needs of the body. While healthy individuals are capable of altering their heart rate, individuals with certain types of heart disease do not have this ability. For these individuals, cardiac pacemakers are used to alter heart rate. Cardiac pacemakers use sensors to determine the pacing frequency for the heart; however, there is no current optimum sensor. In order to discover a better sensor, this study investigated …

K-Means+Id3 And Dependence Tree Methods For Supervised Anomaly Detection, Kiran S. Balagani

Doctoral Dissertations

In this dissertation, we present two novel methods for supervised anomaly detection. The first method "K-Means+ID3" performs supervised anomaly detection by partitioning the training data instances into k clusters using Euclidean distance similarity. Then, on each cluster representing a density region of normal or anomaly instances, an ID3 decision tree is built. The ID3 decision tree on each cluster refines the decision boundaries by learning the subgroups within a cluster. To obtain a final decision on detection, the k-Means and ID3 decision trees are combined using two rules: (1) the nearest neighbor rule; and (2) the nearest consensus rule. The …

Antecedents Of Entrepreneurial Orientation: A Contingency Approach, Laurent Stephane Josien

Doctoral Dissertations

This research was created in order to offer a better understanding of the entrepreneurial orientation construct. Based on the literature review several antecedents of the entrepreneurial orientation construct were identified: risk, achievement, innovation, locus of control, self-esteem, opportunity, autonomy, proactiveness, and competitive aggressiveness. Relying on the contingency theory developed by Burns and Stalker (1961), it was decided to use the Carland's trichotomy of entrepreneurs as a moderator variable between the antecedents and the entrepreneurial orientation construct. As a result, three main areas of research were identified. The first area deals with determining which dimensions are underpinning the entrepreneurial orientation construct, …

Review Of Medical Imaging Devices For The Integration Of Medical Technology And Earmold Production And Grant Proposal Development, Michelle L. Saltarrelli

Doctoral Dissertations

The first purpose of this study was to assess the feasibility of a medical device to replace the current method of earmold production. The medical device would be used to scan the external ear (i.e., external auditory canal and pinna), scan the dimensions to an imaging software system, and finally send the three-dimensional image electronically to a milling machine for the production of earmolds and hearing aid shells. Currently, audiologists use an eight step process described by Dillon (2001) which due to the invasive nature of the procedure presents potential complications to both the clinician and client, The potential complications …

Sustainable Development Of Maritime Cultural Heritage In The Gulf Of Maine, Stefan Claesson

Doctoral Dissertations

In this study the principles of sustainable development and ecosystem-based management are applied to develop a conservation policy for maritime cultural heritage in the Gulf of Maine. This dissertation first examines the effectiveness of existing laws, policies and preservation programs available for the protection and conservation of maritime historical and archaeological resources in the region, and provides an assessment of the diversity and abundance of these resources. Then the principles of sustainability and ecosystem-based management, including inter- and intra-generational equity, precaution, system interconnectedness, and diversity, are applied to form a theoretical framework upon which policies and cultural resource management techniques …

The Venetian Blind Effect, Binocular Luster, And Binocular Rivalry, Richard S. Hetley

Doctoral Dissertations

When one views a square-wave grating and changes the average luminance or contrast of the monocular images relative to each other, at least three perceptual phenomena occur. These are the Venetian blind effect, or a perceived rotation of the bars around individual vertical axes; binocular luster, or a perceived shimmering; and binocular rivalry, or an alternating perception between the views of the two eyes. In this paper, it is shown that increasing the dichoptic luminance modulation leads to these three phenomena in sequence, while increasing dichoptic contrast modulation generally only leads to perceived rotation.

It is also shown that average …

Secondary Organic Aerosol Formation Of Relevance To The Marine Boundary Layer, Xuyi Cai

Doctoral Dissertations

The chlorine atom (Cl) is a potential oxidant of volatile organic compounds (VOCs) in the atmosphere and is hypothesized to lead to secondary organic aerosol (SOA) formation in coastal areas. The purpose of this dissertation is to test this hypothesis and quantify the SOA formation potentials of some representative biogenic and anthropogenic hydrocarbons when oxidized by Cl in laboratory chamber experiments. The chosen model compounds for biogenic and anthropogenic hydrocarbons in this study are three monoterpenes (alpha-pinene, beta-pinene, and d-limonene) and two aromatics (m-xylene and toluene), respectively. Results indicate that the oxidation of these monoterpenes and aromatics generates significant amounts …

Nanotemplate Creation And Self-Assembly On The (111) Surface Of Gold, Georgi Nenchev Nenchev

Doctoral Dissertations

Self-assembly on strained metallic interfaces is an attractive option for growing highly ordered, multi-functional nanopatterns. I performed a series of studies in UHV to investigate the processes of ordered growth and self-assembly on Au(111). I did a combined AES/STM study of the formation of ordered networks of Co islands on Au(111) and obtained the conditions for growing uniform, bi-layer Co-terminated clusters. In another STM study I obtained novel results which reveal the particular complexity of CH3SH self-assembly on Au(111). I observed dimerization of the molecules on the FCC areas of an unperturbed Au(111) reconstruction network and the formation of two …

Stratified-Drift Aquifers In New Hampshire With Potential To Serve As Future, Large Public Water-Supplies: Status, Circa 2000; Projected Losses, Circa 2025; And Data Accuracy, John Alexander Lough

Doctoral Dissertations

Given the growing national water crisis, this research quantified and refined the states of stratified-drift aquifers with potential to yield 75+ gpm (OSDA75) and 150+ gpm (OSDA150) in New Hampshire for 2000 and 2025. Surface waters, cultural features and groundwater hazards from 13 federal/state datasets were buffered according to desired well yields, and then overlain within a geographic information system onto stratified-drift aquifer (OSDA) layer. Non-buffered, highly-transmissive polygons defined the aquifer areas remaining available with potential to meet 75+gpm or 150+ gpm well yields (RSDA75 or RSDA150). Aquifer losses for 2025 were modeled by principal-components regression as function of aquifer …

Flow Through And Around Fish Farming Nets, Oystein Patursson

Doctoral Dissertations

Computational fluid dynamics (CFD) modeling, tow tank and field measurements were used to investigate current flow through and around net panels and cages. For the numerical computations a porous media model was used to represent the net allowing efficient computation of both exterior and interior flow fields. The model was calibrated using tow tank measurements on a net panel at different velocities and angles of attack. The CFD method was able to reproduce the drag- and lift coefficients of the net panel and the velocity reduction behind the net panel with satisfactory accuracy.

The approach was validated for a small …

Dynamics Of Phytoplankton Community Composition In The Western Gulf Of Maine, Timothy S. Moore

Doctoral Dissertations

This dissertation is founded on the importance of phytoplankton community composition to marine biogeochemistry and ecosystem processes and motivated by the need to understand their distributions on regional to global scales. The ultimate goal was to predict surface phytoplankton communities using satellite remote sensing by relating marine habitats--defined through a statistical description of environmental properties--to different phytoplankton communities. While phytoplankton community composition is governed by the interplay of abiotic and biotic interactions, the strategy adopted here was to focus on the physical abiotic factors. This allowed for the detection of habitats from ocean satellites based on abiotic factors that were …

Polychlorinated Biphenyl Dechlorination With Palladized Magnesium - Development Of A Sediment Remediation Technology, Emese Hadnagy

Doctoral Dissertations

PCB contamination in sediments remains a significant problem in many rivers, harbors, and estuarine areas in the US and around the world. In this work, PCB dechlorination by palladium-coated magnesium (Mg/Pd, 0.01% by weight Pd) has been demonstrated in PCB-contaminated marine and freshwater sediments from New Bedford Harbor (NBH), MA; and the Housatonic River (HSR), MA. Experiments were also conducted in pure solvent systems (10% methanol in distilled water). In addition, the performance of an in-situ sediment remediation system capable of delivering and mixing chemical amendments into sub-aqueous sediments and at the same time providing enclosed conditions was evaluated by …

Evaluation Of An Enhanced Magneto-Chemical Process For The Removal Of Pathogens In Wastewater, Christine N. Wright

Doctoral Dissertations

New wastewater treatment technologies are a necessity as a result of increasingly stringent discharge standards, particularly concerning viruses. The traditional approach to wastewater treatment consists of biological treatment, such as trickling filters, biofilms, and activated sludge. Although these biological processes have been an adequate means of wastewater treatment, they are intrinsically limited by their biological nature. A magneto-chemical process, known as CoMag(TM), has been developed to improve coagulation and solids separation and expand upon conventional wastewater treatment techniques.

The research objective of this project was to develop and evaluate a bench-scale model of the CoMag(TM) process for the removal of …

The Activation Of Stereotypical Knowledge, Karla A. Lassonde

Doctoral Dissertations

The effects of stereotypical knowledge on behaviors and beliefs have been widely examined in psychology. Early work examined the conscious, explicit expression of stereotypes. However, it has become increasingly difficult to use explicit tasks to measure stereotypical beliefs because participants often censor their beliefs so that their responses appear socially desirable. Implicit measures that indirectly measure stereotypical knowledge have recently been used as an alternative.

The goal of the experiments presented in this dissertation was to assess the presence of stereotypical knowledge through an implicit measure of reading comprehension that does not reflect social desirability. Across several experiments, participants read …

A Fundamental Analysis Of Means Of Producing And Storing Energy, Michael S. Briggs

Doctoral Dissertations

The goal of this dissertation is to examine some of the most promising non-fossil means for producing electricity and storing energy for transportation, to provide a thorough and (hopefully) unbiased assessment of which hold the most promise, and therefore warrant further research focus. Additionally, recommendations are made for potential means for improving proposed or existing technologies, in particular the technology of a new subcritical reactor design using an electronuclear driver and thermal transmutation of transuranic actinides.

The high energy density of liquid hydrocarbon fuels is ideal for transportation applications, but our ability to sustainably produce such fuels (i.e. biofuels) is …

Biologically Inspired Composite Image Sensor For Deep Field Target Tracking, Pavlo Melnyk

Doctoral Dissertations

The use of nonuniform image sensors in mobile based computer vision applications can be an effective solution when computational burden is problematic. Nonuniform image sensors are still in their infancy and as such have not been fully investigated for their unique qualities nor have they been extensively applied in practice. In this dissertation a system has been developed that can perform vision tasks in both the far field and the near field. In order to accomplish this, a new and novel image sensor system has been developed. Inspired by the biological aspects of the visual systems found in both falcons …