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Global Dynamics Of Some Competitive And Cooperative Discrete Dynamical Systems, Elliott J. Bertrand

Open Access Dissertations

This dissertation investigates the dynamics of some second-order difference equations and systems of difference equations whose defining functions satisfy certain monotonicity properties. In each study we utilize the theory for specific classes of monotone difference equations to establish local and global dynamics.

Manuscript 1 is an introduction that provides fundamental definitions and important results for difference equations that are used throughout the rest of the thesis.

Manuscript 2 presents some potential global dynamic scenarios for competitive systems of difference equations in the plane. These results are extended to apply to the class of second-order difference equations whose transition functions are …

Phytochemical Investigation Of A Native North American Species, “Acer Saccarinum” And An Endemic Saudi Arabian Species, “Euphorbia Saudiarabica”, Abdullatif Bin Muhsinah

Open Access Dissertations

The objectives of this work are the isolation, purification, structure elucidation, and biological evaluation of bioactive secondary metabolites, primarily tannins and diterpenoids, of two plant species: silver maple (Acer saccharinum) and Euphorbia saudiarabica, respectively.

Based on the ethnopharmacological literature, Acer saccharinum is a traditional medicinal plant that has been used by the people of North America. According to previous phytopharmacological studies by our group, over 70 phytochemicals, primarily tannins and flavonoids, have been discovered from three different maple species, including sugar (Acer saccharum), red (Acer rubrum), and sycamore (Acer pseudoplatanus) maples. …

Probing Two-Dimensional Semiconductor And Biological Tissue By Nonlinear Optical Microspectroscopy, Mohammad A. Mokim

Open Access Dissertations

Two-dimensional materials, such as graphene and semiconductor transition metal dichalcogenides (TMDCs), exhibit remarkable optical properties which are of great potential for applications in modern electronics. The first part of this dissertation focuses on the dispersion of the second order resonant nonlinearity (χ⁽²⁾) in the single layer TMDC. We begin with the study of the nonlinear optical properties of monolayer TMDC, WSe2. We experimentally obtain the χ⁽²⁾ dispersion data from the single layer sample of WSe2 by using broadband ultrashort pulse laser sources. The broadband pulse is generated by specially designed photonic crystal fiber (PCF). This PCF fiber …

Cardiovascular And Retinal Vascular Changes In Preclinical Alzheimer's Disease, Cláudia Yang Santos

Open Access Dissertations

One in three adults over 85 years old suffer from Alzheimer’s disease (AD) or other forms of dementia. This already widespread condition is expected to increase further in both incidence and prevalence in coming years. As a result, the need to understand the etiology and pathogenesis of dementia becomes ever more urgent. AD, in addition to its steep cost of care, is the most common form of dementia and the sixth leading cause of death in the United States. It is a complex disease and its mechanisms are poorly understood. The more we learn about AD, the more questions are …

The Biological Function Of Human Epididymis Protein 4 In Epithelial Ovarian Cancer, Nicole Elizabeth James

Open Access Dissertations

Epithelial ovarian cancer (EOC) is the most common gynecologic malignancy worldwide. EOC has a notably poor prognosis, owing to the fact that patients are frequently diagnosed at a late stage after the disease has significantly progressed. While many patients typically respond well to frontline platinum-based chemotherapy, the tumor becomes chemoresistant when a recurrence follows within five years. Therefore, there is an urgent need for the discovery of non-invasive early detection biomarkers and novel targeted therapies.

Human Epididymis Protein 4 (HE4) is a secretory protein that is encoded by the gene whey acidic protein (WAP)-four disulfide core domain protein 2. The …

A Multispecies Statistical Catch-At-Age (Msscaa) Model For A Mid-Atlantic Species Complex, Jason Earl Mcnamee

Open Access Dissertations

Two of the most ecologically and economically important species in the Mid- Atlantic Bight are Atlantic menhaden and the Atlantic striped bass. These species are important for human prosecuted fisheries, but these two species are also closely linked through ecosystem dynamics that are influenced by interactions between these species such as through predation. Beyond striped bass and menhaden, there are also other important species that are linked in this ecosystem. The focus of this dissertation is to estimate the trophic interactions among several important fish species in the Mid- Atlantic Bight, with an emphasis on the interactions between menhaden and …

Facilitated Excretion Of Gold Nanoparticles By Copper Sulfide Nanoparticles Through The Atp7b Transporter, Xiaodong Wang

Open Access Dissertations

Scientific areas have utilized the exclusive qualities of nanomaterials for medicine, diagnostics, drug delivery, tissue engineering and environmental protection. Inorganic metal nanoparticles such as gold and copper have been widely studied in the past decades. Due to the strong and tunable surface plasmon resonance (SPR), nanostructures including nanoshells, nanorods, nanocages, and hollow nanospheres exhibit strong optical absorption at near-infrared (NIR) wavelengths (650–900 nm), resulting in resonance and transfer of thermal energies to the surrounding tissue to raise the temperature. The absorbance of NIR light is desirable because it minimizes thermal injury to normal tissues while providing optimal light penetration. The …

Profiling And Modification Of Silicon Nitride Based Planar Substrates And Nanopores, Nuwan Dhananjaya Bandara

Open Access Dissertations

A nanopore—typically defined as a through-hole with dimensions <100 nm in all directions that functions as the sole path between two electrolyte reservoirs—is a robust single molecule sensor element which has enjoyed a wealth of applications spanning genomics and proteomics, with fledgling contributions to glycomics over the past two decades. Two classes of nanopores exist—biological and solid state. Biological nanopores, for example, α-hemolysin, are highly reproducible and precise—with nanopore lengths and critical constriction sizes that are well known and reproducible. This is not the case with solid state nanopores. Assuming total nanopore length is equal to the nominal thickness of the membrane provided by the manufacturer is a standard practice in the nanopore field. However, given fabrication tolerances, there is some room for error, in certain instances close to 60% of the provided nominal thickness. Any error in nanopore length will couple to errors in the radius calculation. Another two key assumptions are: i) the nanopore has a cylindrical shape unless (and often even if) the shape is otherwise known and ii) a single nanopore through the membrane is formed when one is intended. These issues were addressed by developing a framework that shows errors in harboring such geometric assumptions and eventual consequences for nanopore-based sensing experiments.

The focus of nanopore-based sensing has been predominantly on DNA and protein profiling with only fledging contributions to glycomic profiling. Silicon nitride-based solid state nanopores were used to understand translocation conditions related to alginate and then to study source variability associated with alginates. The two alginates used (from two different sources) gave two distinct signal patterns. Heparin, a common anticoagulant was contaminated in 2008 with over sulfated chondroitin sulfate (OSCS)—a structurally similar adulterant—which lead to ~120 deaths in the United States. Nanopores, with sizes ranging from ~8.6 nm- ~13.6 nm were used …

Nanostructured Interfaces For Single Molecule Sensing And Molecular Fingerprinting, Buddini I. Karawdeniya

Open Access Dissertations

Nanoscale interfaces can have a profound influence on sensor performance, arising from the increased surface-area-to-volume ratio on length scales <100 nm, and often on the emergence of new phenomena on this length scale and even enhancement of existing phenomena. These interfaces can be used to form sensing devices capable of molecular sensing and fingerprinting. Attaining rapid and reliable molecular information with low analyte concentrations and minimal instrument overhead is crucial for many fields including the pharmaceutical industry, food quality analysis, biomedicine, water quality analysis, etc., to meet the current demands of sample analysis. Nanoscale elements in these nanosensors, in amalgam with other physical and chemical driving forces are useful for attaining low limits of detection with the ultimate goal of observing one molecule-at-a-time. This proposal contains two approaches to develop nanostructured sensors—one optical and one non-optical—to reach this goal. The first study is designed to develop a non-optical sensor—a solid state nanopore—for carbohydrate biopolymers—a class of abundant biomolecules that nevertheless have not been extensively characterized like other biomolecules (DNA or proteins), due to inadequate sensing capabilities to easily tackle the molecular complexity by classical methods alone. Additionally, methods to enhance and control the pore surface chemistry are investigated. Second, a series of accessible and low-cost surface enhanced Raman substrates are fabricated on a range of supports using electroless gold plating, to create optical sensors with vibrational selectivity and multifunctional capabilities.

Physical Characterization Of Warburg Effect In Cancer Cells, Da Wei

Open Access Dissertations

Cancer is the second leading cause of death in the United States after heart disease. Because the frequency of cancer diagnoses is correlated with life expectancy, we can expect the rate of cancer diagnosis to increase with the increase of life expectancy. Additionally, cancer treatments are notoriously costly and challenging due to the heterogeneity of the cancer cell population. For these reasons, devising methods to study the characteristics, efficiently diagnose and treat cancer is extremely important.

Warburg effect has been considered as the most unique mechanism that differ cancer cells from normal cells. Normally, most of the healthy cells predominantly …

Cyclodextrin-Promoted Detection Systems For Biological Matrices And Environmental Applications, Dana J. Discenza

Open Access Dissertations

The detection of persistent organic pollutants (POPs) in complex biological and environmental samples is an important research priority due to the known persistence, toxicity, and carcinogenicity of these compounds. Some examples of POPs include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, alcohols and phthalates. Human exposure to these compounds has been well-documented in the scientific literature, and can occur through a variety of mechanisms, such as through an individual’s exposure to contaminated air and soil or through the ingestion of contaminated food or water. Additionally, individuals who have been exposed to POPs contain small amounts of these compounds in …

Stimuli-Responsive Biomaterials For Drug Delivery To Improve Cancer Immunotherapy And Chronic Wound Healing, Anita E. Tolouei

Open Access Dissertations

Sequential delivery of biomolecules is very important as many biologics underlying injury and disease follow an orderly and sequenced series of events. Here we developed and introduced for the first time a dual compartment biomaterial system with an outer compartment made of gelatin and inner compartment that is a ferrogel which can be magnetically stimulated in order to provide on-demand, sequential delivery of multiple bio-instructive payload. We studied the potential application of this dual-compartment biomaterial system in different therapeutic contexts that may benefit from on-demand sequential deliveries, such as in cancer immunotherapy and in chronic wound healing.

Chronic wounds can …

A Minimal Mechanics Model For Mechanosensing Of Substrate Rigidity Gradient In Durotaxis, Bahador Marzban, Xin Yi, Hongyan Yuan

Mechanical, Industrial & Systems Engineering Faculty Publications

Durotaxis refers to the phenomenon in which cells can sense the spatial gradient of the substrate rigidity in the process of cell migration. A conceptual two-part theory consisting of the focal adhesion force generation and mechanotransduction has been proposed previously by Lo et al. to explain the mechanism underlying durotaxis. In the present work, we are concerned with the first part of the theory: how exactly is the larger focal adhesion force generated in the part of the cell adhering to the stiffer region of the substrate? Using a simple elasticity model and by assuming the cell adheres to the …

Wear Of Ultra High Molecular Weight Polyethylene Against Synthetic Sapphire As Bearing Coating For Total Joint Replacements, Kevin D. Gemmell Jr., D.M.L. Meyer

Mechanical, Industrial & Systems Engineering Faculty Publications

Materials commonly found in hip replacements are a polymer paired with metals or alloys. Tribological behavior of polyethylene bearing surfaces against synthetic sapphire are compared against other bearing combinations to evaluate sapphire as a viable means to lower the incidence of revision surgery by mitigating production of wear debris. Sapphire disks against polyethylene plates were tested utilizing a tribometer. The polyethylene wear rate was found to be 22.6mm³ per year, less than the 40-80mm³ per year typically found in traditional hip replacements. A power law function is presented correlating a decreasing friction coefficient as polyethylene volume loss increases …

An Inexpensive Microfluidic Pdms Chip For Visual Detection Of Biofilm-Forming Bacteria, Rico Kolossa, Assem Abolmaaty, D.M.L. Meyer, Zongqin Zhang

Mechanical, Industrial & Systems Engineering Faculty Publications

Aims: Design and assembly of an inexpensive microfluidic PDMS chip for visual detection of cell adhesion and biofilm formation.

Study Design: Three different styles of microchannels (2.6, 5.0, and 11.5 μl volumes) were designed, fabricated and tested for adhesion and biofilm formation in a microfluidic system. The pressure drop measurements system includes a bio-Ferrograph connected to the PDMS microchannel via a syringe and a pressure transducer.

Methodology: Microfluidic chips were fabricated using Polydimethylsiloxane (PDMS) by means of soft lithography. Different cell densities of E.coli K12 cells were introduced to investigate adhesion and biofilm formation at different time …

Sociodemographic Disparities In Adult Child Informal Caregiving Intensity In The United States: Results From The New National Study Of Caregiving, Sarah K. Cook, Steven A. Cohen

Kinesiology Faculty Publications

The objective of the current study was to assess socioeconomic and demographic disparities in caregiving intensity among informal caregivers. Using a randomized, nationally representative sample of 1,014 adult child informal caregivers from Medicare enrollment databases, the associations between informal caregiving intensity and age, race/ethnicity, and income were examined using binary and ordinal logistic regression. Caregiving intensity varied by demographics. Activities of daily living (ADL) caregiving was highest among Black, non-Hispanic caregivers. Instrumental ADL caregiving and number of hours spent caregiving was highest in female and non-White caregivers. Although the overall association between caregiving intensity and income was not significant, when …

Affective Response To Physical Activity As An Intermediate Phenotype, Harold H. Lee, Jessica A. Emerson, Lauren Connell Bohlen, David M. Williams

Kinesiology Faculty Publications

Over the past seventy years, biomedical and epidemiological research has shown that regular physical activity (PA) is critical for physical and mental health. Despite this knowledge, physical inactivity is the fourth leading risk factor for global mortality, accounting for 9% (5.3 million) of premature deaths annually. We suggest this mismatch between knowing about the risks of PA and engaging in regular PA can be reconciled by focusing less on expected health benefits of PA and more on how people feel during PA. Specifically, in this position paper, we argue that affective response (feeling good versus bad) to PA is an …

Attraction And Repulsion Of Mobile Wild Organisms To Finfish And Shellfish Aquaculture: A Review, Myriam D. Callier, Carrie J. Byron, David A. Bengtson, Peter J. Cranford, Stephen F. Cross, Ulfert Focken, Erik Petersson, Henrice M. Jansen, Pauline Kamermans, Anders Kiessling, Thomas Landry, Francis O'Beirn, Erik Petersson, Robert B. Rheault, Ølvind Strand, Kristina Sundell, Terje Svåsand, Gary H. Wikfors, Christopher W. Mckindsey

Fisheries, Animal and Veterinary Sciences Faculty Publications

Knowledge of aquaculture–environment interactions is essential for the development of a sustainable aquaculture industry and efficient marine spatial planning. The effects of fish and shellfish farming on sessile wild populations, particularly infauna, have been studied intensively. Mobile fauna, including crustaceans, fish, birds and marine mammals, also interact with aquaculture operations, but the interactions are more complex and these animals may be attracted to (attraction) or show an aversion to (repulsion) farm operations with various degrees of effects. This review outlines the main mechanisms and effects of attraction and repulsion of wild animals to/from marine finfish cage and bivalve aquaculture, with …

Virtual Environments For The Induction Of Action, Brian Adrian Flowers

Open Access Dissertations

This dissertation is a study on the ways in which Virtual Reality can actively and reactively affect human physiology. The first manuscript describes the design of a highly generalized Virtual Reality biofeedback system. This system was developed such that, given proper design, it would be able to provide users with a highly responsive Virtual Environment to meet the criteria of embodiment, which will increase the user's responsiveness to stimuli. The system also functions as a biofeedback system that can be used for biomechanical as well as physiological feedback by using a generalized design paradigm.

The second manuscript describes a biofeedback …

Effect Of A Technology-Integrated, Nutrition Education Program On Low-Income Youths’ Dietary Intake, Kate Balestracci

Open Access Dissertations

Childhood obesity is an important public health problem as it relates to several chronic diseases and continues to be high, particularly among low-socioeconomic (SES) and racial and ethnic minority populations. In 2011-2014, 25.0% of Hispanic 6-11-year-old school-aged children were considered to be obese or extremely obese, followed by 21.4% of non-Hispanic black children and 13.6% of non-Hispanic white children. When compared to higher-SES children of the same ethnicity and race, low-SES Hispanic, white, and black children were 2.7, 1.9 and 3.2 times more likely to be obese, respectively. Contributing to the obesity epidemic among children is the excess consumption of …

Value Chain Improvements In Small-Scale Fisheries: Case Studies From West Africa, Kristine Beran

Open Access Dissertations

Seafood is one of the most traded food commodities in the world by value. Small-scale fisheries contribute significantly to the global production and supply of seafood. Yet, many small-scale fisheries in developing countries fail to maximize value of seafood products due to post-harvest loss, production, distribution, and marketing challenges. The purpose of this study is to examine how post-harvest innovations might address some of these challenges, whom they benefit along the fisheries value chain, and factors that influence adoption of innovations through two case studies in West Africa.

A multi-methods approach was used to collect extensive quantitative and qualitative data …

Increasing Critical Thinking In Personal Decision Making- A Contextual Framework For College Students, Jade A. White

Open Access Dissertations

Statement of the Problem: The need for agricultural science students to graduate from institutions of higher education with strong critical thinking skills is expressed by both educators and employers to respond to the need for strong problem-solving, decision making, and analytic skills in the 21st century. To prepare students for the changing workforce evidence-based instructional practices, such as problem-based learning, need to be implemented into college courses to increase critical thinking skills. However, there are many barriers associated with implementing these teaching practices such as time barriers, large classes, and the challenge of measuring outputs related to critical thinking. …

An Examination Of Relationships Between School Climate, Student Engagement And Student Academic Achievement In Rhode Island High Schools, Bonita S. Basnyat

Open Access Master's Theses

Different school-level factors contribute to understanding school dropout and school success (Christenson & Thurlow, 2004; Rumberger, 1995). Moving forward, schools and school-based professionals would likely benefit from improved approaches to assessing and understanding how school climate, student engagement and academic achievement relate to one another. However, while previous research has demonstrated associations between school climate, engagement and academic achievement, little is known about how these three elements of schooling interact with student/school demographic and context variables such as diversity, socioeconomic status, and urbanicity. Information collected from the study evaluates the extent to which student engagement varies within a statewide set …

The Response Of Caribbean Coral Reef Communities To The Restoration Of Acropora Corals, Sandra L. Schleier Hernández

Open Access Master's Theses

Coral reef ecosystems are biologically diverse and ecologically important communities that provide valuable ecosystem services to coastal communities, such as coastal protection, food, and tourism. In response to the progressive worldwide decline in coral cover, the active rehabilitation of coral populations by outplanting has become an increasingly common conservation strategy. In the Caribbean, however, assessments of restoration projects have been limited to the outplanted species (mostly Acropora spp). We, therefore, evaluated changes in non-restored species and ecosystem functions post-restoration. We compared six locations across the Caribbean that had been outplanted with Acropora spp. to nearby unrestored controls. Acropora densities were …

Carpenter Bee Nectar Robbery Effects On Fruit Quality And Nesting Provisions In Rhode Island, Sara K. Tucker

Open Access Master's Theses

Eastern carpenter bees, Xylocopa virginica L., are among the most abundant native bee visitors to highbush blueberry flowers in Rhode Island, and they frequently slit corollas to rob nectar. My objective was to assess if nectar robbery offsets the possible value of X. virginica as a native pollinator of blueberries in Rhode Island. I studied foraging behavior of X. virginica at the Rhode Island Agricultural Experiment Station planting which consists of 14 highbush blueberry cultivars. I assessed plant and environmental factors related to slitting behavior, and the effects of slitting on fruit set and blueberry quality. The average number of …

Measurements Of Modal Attenuation Using Broadband Sources In The New England Mud Patch, Kerry Unrein

Open Access Master's Theses

Measurements of underwater acoustic signals were made on a bottom-mounted horizontal line array during the Seabed Characterization Experiment (SBCEX) in the New England Mud Patch south of Martha’s Vineyard in about 70 m of water. The signals were generated by Signals, Underwater Sound (SUS) charges detonated at various locations in the experimental area at a depth of 18 m, during nearly-isovelocity conditions. The broadband signals were analyzed for modal arrival time and amplitude using time-frequency techniques. Ratios of modal amplitudes at the individual hydrophones were used to estimate the modal attenuation coefficients. Hence, these estimates are independent of any uncertainty …

The Effects Of Urbanization On Performance, Habitat Selection, And Persistence Of Anolis Lizards, Andrew Clark Battles

Open Access Dissertations

Urbanization is a global change phenomenon that is increasing in frequency and magnitude worldwide. As a greater proportion of the human population resides in urban areas, cities must grow, therefore exposing an increasing number of species to human-modified habitat. While some species become extirpated when their habitat is urbanized, others persist and even spread throughout cities. Furthermore, human activity increases the rates of species invasions around the world, and many introductions occur in urban areas. The objective of this dissertation is to evaluate the consequences of some major environmental changes caused by urbanization for non-human urban dwellers. Specifically, I measure …

Residual Strength Of Composite Materials After Exposure To Blast Loading, Monica L. Black

Open Access Master's Theses

This research investigates the effects of shock loading on a composite structure’s compressive residual strength. The research develops a methodology for evaluating and quantifying such damage using non-destructive imaging technologies, and develops a prediction equation for compressive residual strength of the damaged composite structure.

Experiments and imaging of Cyply 1002 glass-fiber/epoxy laminate panels were conducted at the University of Rhode Island (URI) and the Naval Undersea Warfare Center Division, Newport (NUWCDIVNPT), respectively. Controlled air blast experiments were conducted using the shock tube at URI’s Dynamic Photomechanics Laboratory (DPML), inducing non-catastrophic damage on the panels. 3D Digital Image Correlation (DIC) was …

Impact Of Hemlock Woolly Adelgid And Elongate Hemlock Scale On Early Seasonal Development Of Eastern Hemlock, Elizabeth Whitney

Open Access Master's Theses

Herbivores can have a significant impact on plant host development. While altered plant development most commonly results from defoliation, some causes are more cryptic. Effects on development can be difficult to detect in long-lived woody plant species. Hemlock woolly adelgid is a piercing-sucking herbivore that has been previously been observed to have substantial effects on eastern hemlock. Observations of bud break were carried out on a three-day-on, one-day-off rotation from April through May in 2016 and 2017. We found that hemlock woolly adelgid delayed bud break in eastern hemlock. Our findings suggest that piercing-sucking herbivores can also significantly affect the …

Isolation And Identification Of Probiotic Bacteria For The Management Of Epizootic Shell Disease, Grace Underwood

Open Access Master's Theses

Epizootic shell disease (ESD) is an emerging disease in the American lobster (Homarus americanus) characterized by lesions, mainly on the carapace. The diseased appearance of the shell due to the lesions has had significant negative impact upon the lobster fisheries in New York, Connecticut, Rhode Island, and Massachusetts, since fishers are not able to sell affected lobsters to the more lucrative live market. ESD lesions are different from other shell diseases found in the American lobster populations because they are due to a poly-microbial infection that degrades the epicuticle layer, while the pillars of the chitin matrix remain …