Digital Commons Network^™

Photometric Studies Of Cygnus X-1 From 322-473 Kev With The Solar Maximum Mission, Benjamin Vaughn Augustine Hersh

Doctoral Dissertations

We present results from three years of observations from Cygnus X-1 and the Crab Nebula using the Gamma Ray Spectrometer onboard the Solar Maximum Mission satellite. We show that using a neural network based background model, it is possible to predict the terrestrial component of the gamma-ray background to a $<$1% level. We also show that the flux from the Crab is steady over a three year period at level of 0.024 $\pm$ 0.002 $\gamma$ cm$\rm\sp{-2}\ s\sp{-1}\ MeV\sp{-1}$. Similarly, the flux from Cygnus X-1 was consistent with the flux measured in 1979 with HEAO-3 and in 1991 with BATSE. We measured a flux of 0.013 $\pm$ 0.003 $\gamma\rm\ cm\sp{-2}\ s\sp{-1}\ MeV\sp{-1}$. We discuss the electron lifetimes within the Crab Nebula and limits on temperature variations from the Cygnus X-1 accretion disk.

Snow And Ice Chemistry Study Of The Greenland Ice Sheet, Qinzhao Yang

Doctoral Dissertations

The Greenland ice sheet preserves high resolution records of environmental and climate change spanning seasons to hundreds and thousands of years. In this study, we utilize major chemical species measurements of surface snowpit samples and ice cores collected at GISP2, 20D, Mount Logan, and Sentik Glacier to investigate major chemical species spatial distribution, temporal variations, and possible sources for the major chemical species in these ice cores.

A two-sided t-distribution test (a = 0.05) was applied for the study of major chemical species spatial distribution over a portion of central Greenland. The results suggest that concentrations of major chemical species …

Meandering And Eddy Formation In Separating Western Boundary Currents, Ilson Carlos Almeida Da Silveira

Doctoral Dissertations

The dynamics of meandering and eddy detachment in separating western boundary currents are explored by considering inviscid, quasi-geostrophic current systems with both data analysis and modeling.

In chapter two, hydrographic and velocity observations of the North Brazil Current (NBC) retroflection region during the 1990-1991 Western Tropical Atlantic Experiment are examined. A three-layer quasi-geostrophic approximation to the NBC region is built. Stream function and potential vorticity (PV) fields are presented. The upper and middle layer flows simulate the retroflection of the NBC waters at surface and subthermocline levels, respectively. The deepest layer is represented by a meandering weak southward flow that …

Illusions Of Change: An Analysis Of The Fatherhood Discourse In "Parents Magazine", 1929-1994, Candice Leonard

Doctoral Dissertations

This project explores the question of women's expectations and experience across the transition to parenthood. Specifically, the source of women's unmet expectations about the genderedness of household division of labor and familywork are examined, bridging the literatures on expectation formation and information-seeking behavior.

The centerpiece of the study is a comprehensive, context-sensitive analysis of the fatherhood discourse in Parents Magazine from 1929 through 1994, which uses both quantitative and qualitative methods. Importance is placed on the fact that this is primarily a male-produced discourse that defines fatherhood for women. It was found that there are significant differences by author sex …

The Purification And Characterization Of An Extrapallial Fluid Protein From The Mollusc, Mytilus Edulis, Stephen Joseph Hattan

Doctoral Dissertations

Shell deposition within the bivalve mollusc Mytilus edulis is regulated by the macromolecules of the extrapallial fluid (EP fluid). These mineralization regulating macromolecules are thought to be responsible for the nucleation, growth regulation and growth cessation of the CaCO$\sb3$ mineral crystals that will inevitable constitute $\geq$95% of the mature shell.

This dissertation presents the results of the purification and characterization of the major EP fluid protein of the bivalve Mytilus edulis. The major EP fluid protein was determined to comprise 56% of the total fluid protein and to consist of 7.25% by weight carbohydrate. The protein was purified though a …

The Theater Of The Absurd In Europe And America: Sartre, Beckett, Pinter, Albee And Drama Criticism, Sheila O'Brien Mcguckin

Doctoral Dissertations

This study examines the significance of the post World War II Theater of the Absurd which explored new concepts of ontology and semiology and provided a vehicle for the dissemination of existentialist ideas. As a link between modernist and postmodernist drama, it also served as a catalyst for changes in drama criticism that anticipated some of the controversies of deconstructionism.

The first part of this work places the Theater of the Absurd in historical context by tracing elements of absurdity from the theater of ancient Greece into the twentieth century. Modern absurdism emerged in the 1930's as part of the …

Ecological Patterns During Ontogeny In The Bicolor Damselfish, Stegastes Partitus, Poey, Richard Stephen Nemeth

Doctoral Dissertations

This dissertation examined the ecological constraints during the early life history of the bicolor damselfish, Stegastes partitus Poey (Perciformes, Pomacentridae). A series of studies, conducted in Teague Bay, St. Croix and Discovery Bay, Jamaica between 1991 and 1996, determined the cause of variation in length of the planktonic larval period, the effect of larval history on settlement success and examined the causes behind the patterns of distribution and population structure seen throughout its geographic range. Variable growth rates in early-stage larvae established a canalized trajectory toward larval competence and provides a mechanism for determining planktonic duration. Using otolith microstructure I …

Aspects Of Particle Acceleration In Solar Flares, Yuri Eduardovich Litvinenko

Doctoral Dissertations

This is a theoretical study of the acceleration of charged particles during solar flares. An attempt is made to trace the relationship between the processes of acceleration and primary flare energy release.

Motion of charged particles in a reconnecting current sheet (RCS) is considered, including both the electric field and the magnetic field with nonzero transverse (perpendicular to the RCS plane) and longitudinal (parallel to the electric current) components. An analytical technique is developed to calculate particle trajectories and energy gain. The solution predicts a critical value of the longitudinal field beyond which it counteracts the effect of the transverse …

Structural Inequalities, Family And Cultural Factors, And Spousal Violence Among Anglo And Hispanic-Americans, Jana Lynn Jasinski

Doctoral Dissertations

There is some evidence that rates of spousal assault are higher among Hispanic Americans compared to Anglo Americans, however, very little empirical research has focused extensively on Hispanic Americans and their risks for spousal violence. There is even less research that considers different Hispanic groups. This study used the 1992 National Alcohol and Family Violence Survey to examine the relationships among structural inequalities, family relations, and spousal assault among a sample of 1,768 Anglo and Hispanic Americans.

The results indicated that Hispanic Americans were more likely to use minor or severe physical violence against their spouses, however, there were also …

Cross-Tail Current Carriers In A Two-Dimensional Equilibrium Magnetotail Model, Douglas Johnston Larson

Doctoral Dissertations

The purpose of this study is to gain physical insight into how charged particles, that violate the guiding center approximations, contribute to cross-tail current in a self-consistent plasma sheet. A technique to generate self-consistent two-dimensional (2D) current sheets is described. Groups of monoenergetic protons are followed in a model magnetic field. The sample current sheets are characterized by resonant quasiadiabatic and stochastic orbits. Several ion and electron groups are combined to produce a plasma sheet in which the charged particles carry the currents needed to generate the magnetic field in which the orbits are traced. An electric field also is …

Assessing Land Use/Cover Change In Costa Rica, Gerardo-Arturo Sanchez-Azofeifa

Doctoral Dissertations

The need for accurate estimates of forest cover and forest fragmentation is a critical issue for developing countries such as Costa Rica. Accurate estimates of forest cover can help in several sectors related to the environment and economic development. This dissertation focuses on providing an accurate and precise estimate of forest cover in Costa Rica. The year 1991 was used as a baseline. Landsat Thematic Mapper was the remote sensing sensor used in this analysis. This dissertation concludes that: (1) Twenty-nine percent ($\sim$1,400,000 ha) of the country was under primary forest (80% canopy closure) in 1991. Of the total forest …

The Relation Between Media Exposure And Body Satisfaction: An Examination Of Moderating Variables Derived From Social Comparison Theory, Shelley Rae Strowman

Doctoral Dissertations

The relation between media exposure and body satisfaction was investigated using correlational and experimental approaches. Several variables were examined as potential moderators of this relation (perceived similarity to magazine models, self-relevance of weight, perceived control over weight, tendency to compare to models, and body mass). These variables were derived primarily from past research on Festinger's (1954) social comparison theory. In Study 1, male and female subjects reported the amount of time they spent reading magazines pre-coded as having a body image or non-body image emphasis. Body image magazine exposure was unrelated to body satisfaction and self-esteem when correlations were computed …

Biped Dynamic Walking Using Reinforcement Learning, Hamid Benbrahim

Doctoral Dissertations

This thesis presents a study of biped dynamic walking using reinforcement learning. A hardware biped robot was built. It uses low gear ratio DC motors in order to provide free leg movements. The Self Scaling Reinforcement learning algorithm was developed in order to deal with the problem of reinforcement learning in continuous action domains. A new learning architecture was designed to solve complex control problems. It uses different modules that consist of simple controllers and small neural networks. The architecture allows for easy incorporation of modules that represent new knowledge, or new requirements for the desired task. Control experiments were …

Life History And Reproductive Biology Of The Estuarine Nudibranch Tenellia Adspersa (Nordmann, 1845), Charles Morgan Chester

Doctoral Dissertations

Tenellia adspersa is a small (5-7 mm) estuarine nudibranch. Tenellia lives in a highly variable environment and feeds on many gymnoblastic and calyptoblastic hydroids. I undertook a field study at four sites in the Great Bay Estuary (Durham, New Hampshire) to assess the amount of variability in abiotic and biotic factors. Environmental parameters (temperature and salinity) and the availability of hydroid prey (Cordyolophora lacustris and Obelia spp.) varied within the generation time of Tenellia and could affect its life history.

Laboratory studies compared the growth rate of the hydroid, Cordylophora to the growth rate and predation rate of Tenellia. The …

Changes In Self-Sufficiency: A Feminist Approach To Literacy Program Evaluation, Marcia Ann Makris

Doctoral Dissertations

This research was a follow-up investigation of a federally-funded literacy program which was established to assist its participants to achieve self-sufficiency through employment. The program was designed and implemented in response to the federal legislative law, the Family Support of Act of 1988 (FSA), which mandated that states provide Job Opportunities and Basic Skills (JOBS) programs to "assure that needy families with children obtain the education, training, and employment that will help them avoid long term dependency" and "assist recipients to become self-sufficient." The purpose of this study was to gain an understanding of the characteristics of the program that …

Competition And Dispersal In The Regulation Of Plant Species Richness On Carex Stricta Tussocks, Leonard Alexander Lord

Doctoral Dissertations

Many wetland plant species can be found growing on Carex stricta Lam. (tussock sedge) tussocks in freshwater marshes. Based on Grime's model of plant species richness, the objectives of this research were to: (1) examine if dispersal characteristics vary among C. stricta marshes in a manner that could potentially influence species richness on individual tussocks, and (2) examine how variation in propagule availability may interact with standing crop and leaf litter to regulate species richness on individual tussocks. All of the research was conducted in southeastern New Hampshire.

Dispersal characteristics were quantified in five wetlands representing a broad range of …

Rocket Observations Of The Hf Heated Ionosphere, William James Peria

Doctoral Dissertations

Measurements of the ion distribution function, electron density, wave activity, and convection electric field have been made in situ by a sounding rocket flown through the artificially heated F layer ionosphere over Arecibo, Puerto Rico. The ion distributions show the effect of the HF heater through elevated effective temperatures, superthermal fluctuation level, and a plume-like population of energetic ions drifting out of the HF reflection region. The electron density, from a Langmuir probe, shows meter-scale depletions of $\sim$10% in the immediate vicinity of the reflection height, both above and below (Kelley et al., 1995). A shear in the convection electric …

Giving Voice To The Spirits: Storytelling In The Service Of Belizean Literacy, Gerald Joseph Kelly

Doctoral Dissertations

This dissertation examines the participation of indigenous storytellers in a textbook project undertaken by Belizean educators. A qualitative study of these narrators, who contributed both traditional stories and personal narratives, extended from February 1991 until February 1996 in Belize's Toledo District. Featured narrators were interviewed and audio-taped by the author throughout this time period, as they contributed their oral lore to the project.

This investigation reveals the complex interrelationships of anthropological salvage and cultural renewal. Certain contemporary scholars decry what they perceive as the limited pastoral dimension of salvage, which may suggest that the true value of traditional stories lies …

Polymer Substrates For Optical Chemical Sensing, Michael Thomas Rooney

Doctoral Dissertations

Membranes for chemical sensing based on changes in light reflectance from amine-modified, porous, rubber-toughened poly(vinylbenzyl chloride-co-divinyl benzene) were prepared by bulk free radical polymerization. Xylene and dodecane were used as porogenic solvents and solutions were prepolymerized to viscous solutions prior to forming membranes. The crosslinked membranes are turbid and scatter light when unswollen. They swell in response to increases in hydrogen ion concentration, causing the membrane to reflect less light. Turbidity is ascribed mainly to scattering by water-filled macropores within the amine-functionalized membranes. Swelling decreases the refractive index of porous, hydrated polymers with 2% crosslinking by approximately 0.04 units, bringing …

Analysis And Design Of Ac Induction Motors With Squirrel Cage Rotors, Shine Ho

Doctoral Dissertations

The traditional approach to modelling the AC induction motor revolves around the well-known equivalent "T" circuit model. In this approach, the direct connection from geometry to performance is suppressed. For better understanding of magnetic, electrical, and thermal behaviors, three lumped models based on the actual geometry are developed in this dissertation. Based on these lumped models, an iterative design model is also developed.

In order to analyze and design induction motors, the relationships of basic motor variables to motor performance must be known. For determining the relationships, three new mathematical lumped models are developed. The magnetic model describes flux behavior. …

Global Terrestrial Biogeochemistry: Perturbations, Interactions, And Time Scales, Bobby H. Braswell

Doctoral Dissertations

Global biogeochemical processes are being perturbed by human activity, principally that which is associated with industrial activity and expansion of urban and agricultural complexes. Perturbations have manifested themselves at least since the beginning of the 19th Century, and include emissions of CO$\sb2$ and other pollutants from fossil fuel combustion, agricultural emissions of reactive nitrogen, and direct disruption of ecosystem function through land conversion. These perturbations yield local impacts, but there are also global consequences that are the sum of local-scale influences.

Several approaches to understanding the global-scale implications of chemical perturbations to the Earth system are discussed. The lifetime of …

Full-Scale Comparative Evaluation Of Two Slow Sand Filter Cleaning Methods, Jan A. Kem

Doctoral Dissertations

Slow sand filters are an established treatment method for water with low turbidity. They usually are effective for the removal of turbidity, microorganisms (including cysts of Giardia and Cryptosporidium), and particles, but they require significant periods of time for cleaning. In the 1950's, West Hartford, CT developed a harrowing process to reduce the time and labor required for cleaning at that plant. A 1988 study observed those filters had higher removal rates for non-particulate dissolved organic carbon and UV absorbing materials, surrogates for trihalomethane formation, than did filters at two other plants cleaned by the conventional scraping method.

This study …

Patterns Of Base Composition Within And Between Animal Mitochondrial Genomes, Nicole T. Perna

Doctoral Dissertations

Nucleotide composition of a DNA molecule is a product of base substitution. Variation in nucleotide composition indicates a change in the pattern of substitution at either the level of the underlying mutational spectrum or the constraints imposed by natural selection. This work explores patterns of nucleotide usage within and between animal mitochondrial genomes and the evolutionary mechanisms that have shaped these patterns. Fourfold degenerate sites are expected to reflect the underlying mutational spectrum. Three simple measures of compositional bias, taking into account the strand-specific nature of nucleotide distribution in mtDNA, reveal considerable variation among fourfold degenerate sites of metazoan mitochondrial …

Beyond The Postmodern Impasse Of Contemporary Composition: The Non-Foundational Alternative Of Deweyan Pragmatism, Donald Crosby Jones

Doctoral Dissertations

In their critique of the autonomous individual of foundationalism, postmodernists have rejected the epistemological assumption that a knower directly perceives reality in thought then expresses these perceptions through language. Yet as these theorists have asserted the influence of language upon an individual's thinking, they have been unable to explain an individual's agency--the ability to create, assert, examine, and maintain/or modify a belief. Once considered to be situated in prior discourses, the individual has been conceived as a postmodern subject dominated by language. Yet the subject's ability to influence as well as be influenced by discursive practices has not been explained …

Fume Generation In Gas Metal Arc Welding, Robert V. Albert

Doctoral Dissertations

This investigation studied fume generated from Gas Metal Arc Welding (GMAW). Through an extensive literature review, experimental measurements and analytical reasoning this dissertation answers four questions. Why and how does oxygen content of the shield gas effect fume generation? Why is more fume generated with helium than with argon as a shield gas? Why and how does welding mode affect fume rate? Why and how does pulsing the current lower fume generation rate?

An extensive literature survey was conducted. The current view of GMAW indicates that four modes exist in metal transfer across the arc. Each mode selects from several …

Investigation Of Pd(A)(20)Pd(T)(20) In The Analytical Electrophoresis Apparatus, John Oliver Wooll

Doctoral Dissertations

The analytical electrophoresis apparatus (AEA) is capable of generating and monitoring the electrophoretic migration of macroions. The oligonucleotide pd(A)$\sb{20}\cdot$pd(T)$\sb{20}$ was use as a model to compound to evaluate the range and validity of AEA measurements under a variety of electric fields and solvent conditions. A broad range of electric fields yield consistent, reproducible values. The charge determination from different procedures, steady state electrophoresis (SSE) and electrophoretic mobility, have not been consolidated into a consistent theory but advancements in the scope and understanding of the AEA's potential have been made. The apparent charge from the AEA measured electrophoretic mobility, $\mu$, of …

Time Evolution Of The Chiral Phase Transition During A Spherical Expansion, Melissa Anne Lampert

Doctoral Dissertations

We examine the nonequilibrium time evolution of the hadronic plasma produced in a relativistic heavy ion collision, assuming a spherical expansion into the vacuum. We study the O(4) linear $\sigma$ model to leading order in a large-N expansion. Starting in the high temperature unbroken chiral symmetry phase, the system expands and cools, finally settling into the broken symmetry vacuum state. We consider the proper time evolution of the effective pion mass, the order parameter $\langle\sigma\rangle,$ and the particle number distribution. We examine several different initial conditions and look for instabilities (exponentially growing long wavelength modes) which can lead to the …

Molecular Identification, Coastal Distribution And Recruitment Of Cucmaria Frondosa Larvae In The Western Gulf Of Maine, Dorothy E. Medeiros-Bergen

Doctoral Dissertations

Understanding of the physical transport of larvae requires information on adult source populations, larval distributions, larval behavior and physical oceanography. Identification of three species (Cucumaria frondosa, Psolus fabricii and Chiridota laevis) of holothurian larvae in the western Gulf of Maine was done with a simple detection protocol, using oligonucleotide probes, for the 16S rRNA portion of the mitochondrial DNA genome. More than 2000 larvae and new recruits were analyzed. This technique revealed that of the three species present in the plankton, Cucumaria larvae dominated the samples comprising $>$90% of the larvae and 95% of new recruits during 1993. Cucumaria …

Friend Of Government Or Damned Tory: The Creation Of The Loyalist Identity In Revolutionary New Hampshire, 1774-1784, James Leslie Walsh

Doctoral Dissertations

The dissertation examines the creation of loyalist identity during the American Revolution. Two distinct identities were fashioned, one by the loyalists themselves and a second competing identity which was created for them by their opponents, the radical faction of the revolutionary movement. Both identities were created consciously and for political or economic motives.

The identity created by the loyalists through their actions and words is to be found in a close reading of the claims filed with the Claims Commission created by Parliament in 1783. The dissertation argues that loyalists self-fashioned an individual political identity, as part of the creation …

Profiles Of Reform In The Teaching Of Calculus: A Study Of The Implementation Of Materials Developed By The Calculus Consortium Based At Harvard (Cch) Curriculum Project, Alice Darien Lauten

Doctoral Dissertations

The research question addressed in this study is: What profiles of interpretation and implementation of reform in the teaching of calculus emerge from data obtained from mathematics faculty members using Calculus Consortium Based at Harvard (CCH) Curriculum Project materials? Site liaisons from mathematics departments using CCH Curriculum Project materials in 117 academic institutions, consisting of 13 secondary schools, 30 two-year colleges, 19 doctoral and research universities, and 55 other colleges and universities, completed Initial and Site Liaison Surveys. Site liaisons and 266 other instructors from 117 academic institutions completed a Faculty Survey. Six clustering scales were developed from the survey …