Bradley Family Photograph Collection

MS019-199

Expanding Food Agency: Exploring the Theory and Its Scale in Philadelphia, PA

Our contemporary American food system has created complex environments for decisions and actions around food, and those decisions have implications for culture, health, natural resources, social relations, and the economy. And yet, as scholars, we do not understand the particulars of how people actually cook for themselves and their families. This study explores how race and socioeconomic class interact with individual experience of food agency, or personal capacity to plan and prepare meals within one\u27s food environment. It is one stage in a multiphase project developing a comprehensive theory of food agency, applicable in any context; a scale for measuring that agency; and a cooking pedagogy for increasing it. This research was based on an explanatory sequential mixed methods design: a qualitative follow-up to quantitative research (see Creswell & Plano Clark, 2011). It is an in-depth qualitative investigation with low-income participants of color, a population that had previously not been included in the development of food agency theory. The study\u27s population was a mix of Drexel University students and community residents of Mantua, in Philadelphia, PA, and was recruited from Drexel\u27s Healthy Cooking Techniques summer course. Data collection included semi-structured interviews and survey administration, and also utilized food agency scale survey responses. Analysis and results are divided into two papers, one narrative, and one a comparison between quantitative components of the food agency scale and corresponding qualitative data. Narrative analysis reinforces the notion that food agency is incredibly complex and self-referential. People with high self-efficacy around food may feel like they have a high level of agency, even if they can identify ways that societal structures impede them. Mixed-methods analysis reveals aspects of food agency that are not reflected by the scale: specifically, strategies for procuring food; environmental and financial impediments to that procurement; and aspiration for greater self-sufficiency and healthfulness in preparing food. Participants are intentional and skillful in resisting economic and environmental obstacles to feeding themselves. They want to be supported in building skills for that daily endeavor. The food agency scale does not gauge many of the strategies with which they resist obstacles, and therefore might be better cast as a cooking action scale, rather than a measure of comprehensive food agency

Scientific modeling & scientific realism : a view from biological morphology

In the ongoing philosophical debates between scientific realists and antirealists, scientific modeling is often taken as an exemplar antirealist scientific methodology due to the abstract, idealized, and metaphorical nature of most scientific models. I argue against the antirealist view and in favor of a realist view of scientific modeling as it is performed in biological morphology. On my view, morphological modeling is a type of what I call multiperspectival modeling, which involves multiple related models deployed to represent a single target phenomenon. I show how multiperspectival morphological modeling can be incorporated into the version of scientific realism developed by Richard Boyd, known as accommodationism, based on the role modeling plays in informing the definitions of natural kind terms and on the role theoretical judgments play in model construction and deployment. I claim that multiperspectival morphological models contribute to the inductive and explanatory successes of biological morphology by playing a central role in accommodating (on the one hand) the inferential, conceptual, and classificatory practices of morphology to (on the other hand) independently existing causal phenomena. I intend for the realist view of morphological models presented here to serve as an example for how scientific modeling can be interpreted realistically across scientific disciplines

Moisture Degradation of CTD-403: Testing the Application of Cyanate Ester Insulations to Fusion Devices

The fusion devices currently being developed present several challenges for magnet designers. One challenge lies within the electrical insulation, which must be able to withstand extreme temperatures (both cryogenic and elevated temperatures), large shear and compressive stresses, high operating voltages, and high levels of incident radiation. To address the need for better performing insulation systems, Composite Technology Development, Inc. (CTD) has developed CTD-403, a cyanate ester resin with increased radiation resistance, ease of processing and fabrication, low moisture absorption characteristics, and high mechanical and electrical strength at cryogenic and elevated temperatures. In this thesis, CTD-403 resin based insulation systems were tested under the operation guidelines of the Quasi-Poloidal Stellarator (QPS). Because the coils of QPS are water cooled, it is important to understand the effects of long term humidity exposure on the insulation. The effects of humidity on moisture absorption characteristics, dimensional stability, mechanical and electrical properties were characterized. Increasing the humidity level caused a corresponding increase in the saturation level, while increasing the temperature of exposure magnified these effects causing more pronounced non-Fickian behavior. The mechanical properties degraded with an increase in humidity level. Elevated temperature effects are more pronounced on the compressive properties than the tensile properties. The glass transition temperature was more greatly affected by elevated temperature exposure as opposed to increased humidity exposure, decreasing in both instances. The dielectric strength decreases with increased humidity level and exposure time. Based on these findings, the performance of cyanate ester resin based insulation systems is shown superior to that of traditional epoxy based resin systems in all performance measures. The degradation of the mechanical and electrical properties of the insulation from long term effects of humidity and elevated temperature exposure are shown to be within the performance criteria bounds, and the insulation is therefore recommended for use in current and future fusion programs

The Functional, Ecological, and Evolutionary Morphology of Sea Lampreys (Petromyzon marinus)

Lampreys (Petromyzontiformes) are jawless vertebrates with an evolutionary history lasting at least 360 million years and are often used in comparisons with jawed vertebrates because some of their morphological aspects, such as the segmented trunk musculature with curved myosepta and a non-mineralized skeleton fibrous skeleton, are thought to resemble the condition of early vertebrates before the evolution of jaws. Although earlier authors studied the morphology of the skeleto-muscular system of the trunk of lampreys, their studies are not detailed and complete enough to allow a functional and biomechanical analysis that is needed as a basis for modeling the mechanics of lamprey locomotion and for understanding the causal roles played by the anatomical structures within the trunk. Questions remain, such as what is the architecture of the trunk fibroskeleton, and how does it function with the musculature to bend the trunk? This dissertation studied the functional, ecological and evolutionary morphology of the trunk of Sea Lampreys (Petromyzon marinus) as well as its relevance in understanding the environmental history of landlocked lamprey populations. Functional morphology revealed that the fibroskeleton of the trunk is a self-supporting concatenated system of fibers, which creates a scaffold for the musculature and transmits forces to bend the trunk during swimming. Ecological morphology demonstrated the adaptive advantage of the fibroskeleton’s architecture, which enables the movements that are performed during migration and spawning and gives lampreys the capacity to colonize upstream realms. These results help explain the evolutionary morphology of lampreys, which likely originated in freshwater as algal feeders and evolved into parasites after going through an intermediary scavenging stage. When these insights are applied to the evolution of landlocked Sea Lampreys, it becomes evident that their entry into freshwater lakes occurred as soon as they were able to reach them and that populations likely became established in Lake Ontario, Lake Champlain, and the Finger Lakes thousands of years ago. This insight undermines the current status of landlocked Sea Lampreys as invasive species in these lakes and the case for their eradication. Hence, this dissertation provides a comprehensive and integrative analysis of lamprey biology from their anatomy to environmental policy

The Past in Present African Urban Mobility Systems: Towards a Mobilities Longue Durée

Building on the notion that mobility plays a critical role in everyday urban life in Africa as elsewhere, this editorial provides an introduction to the special collection ‘The Past in Present African Urban Mobility Systems’. As we introduce the papers in this collection, we argue for an understanding of contemporary urban mobility systems that account for their historical roots. While historians of African transport have provided insights into the origins of mobility systems on the continent, we wish to animate the contemporary experience of those systems, advocating for a mobilities longue durée

Theory of the cold collision frequency shift in 1S--2S spectroscopy of Bose-Einstein-condensed and non-condensed hydrogen

We show that a correct formulation of the cold collision frequency shift for two photon spectroscopy of Bose-condensed and cold non-Bose-condensed hydrogen is consistent with experimental data. Our treatment includes transport and inhomogeneity into the theory of a non-condensed gas, which causes substantial changes in the cold collision frequency shift for the ordinary thermal gas, as a result of the very high frequency (3.9kHz) of transverse trap mode. For the condensed gas, we find substantial corrections arise from the inclusion of quasiparticles, whose number is very large because of the very low frequency (10.2Hz) of the longitudinal trap mode. These two effects together account for the apparent absence of a "factor of two" between the two possibilities. Our treatment considers only the Doppler-free measurements, but could be extended to Doppler-sensitive measurements. For Bose-condensed hydrogen, we predict a characteristic "foot" extending into higher detunings than can arise from the condensate alone, as a result of a correct treatment of the statistics of thermal quasiparticles.Comment: 16 page J Phys B format plus 6 postscript figure

Deflagrative, Auto-ignitive, and Detonative Propagation Regimes in Engines

The paper presents a novel overall quantitative description of the major regimes of engine combustion, covering the influences of both turbulence and auto-ignition parameters on burn rates and flame extinctions. It involves two separate, yet interconnected, correlation diagrams. The first involves the normalized turbulent burning velocity, the Karlovitz stretch factor the strain rate Markstein number, and also includes possible relative auto-ignitive burn rates. The second is a complementary correlating ξ/ɛ diagram, involving the auto-ignitive parameters of ignition delay and excitation times. The ξ parameter is the acoustic speed normalized by the auto-ignition velocity, while ɛ is the acoustic wave residence time in a hot spot, normalized by the excitation, or heat release, time. It also includes an indication of the regime of normal flame propagation. The different auto-ignitive regimes, in which a variety of contrasting fuel/air mixtures might operate, are indicated on the ξ/ɛ diagram, particularly in relation to its peninsula of developing detonation at a hot spot. Operational points, measured on a variety of engines, are also shown on the two diagrams, in terms of the different regimes, including those of mild and “super-knock”, turbulent flame extinctions, and controlled auto-ignition

Quantification of avian hazards to military aircraft and implications for wildlife management

Collisions between birds and military aircraft are common and can have catastrophic effects. Knowledge of relative wildlife hazards to aircraft (the likelihood of aircraft damage when a species is struck) is needed before estimating wildlife strike risk (combined frequency and severity component) at military airfields. Despite annual reviews of wildlife strike trends with civil aviation since the 1990s, little is known about wildlife strike trends for military aircraft. We hypothesized that species relative hazard scores would correlate positively with aircraft type and avian body mass. Only strike records identified to species that occurred within the U.S. (n = 36,979) and involved United States Navy or United States Air Force aircraft were used to calculate relative hazard scores. The most hazardous species to military aircraft was the snow goose (Anser caerulescens), followed by the common loon (Gavia immer), and a tie between Canada goose (Branta canadensis) and black vulture (Coragyps atratus). We found an association between avian body mass and relative hazard score (r2 = 0.76) for all military airframes. In general, relative hazard scores per species were higher for military than civil airframes. An important consideration is that hazard scores can vary depending on aircraft type. We found that avian body mass affected the probability of damage differentially per airframe. In the development of an airfield wildlife management plan, and absent estimates of species strike risk, airport wildlife biologists should prioritize management of species with high relative hazard scores

Quantification of avian hazards to military aircraft and implications for wildlife management

Collisions between birds and military aircraft are common and can have catastrophic effects. Knowledge of relative wildlife hazards to aircraft (the likelihood of aircraft damage when a species is struck) is needed before estimating wildlife strike risk (combined frequency and severity component) at military airfields. Despite annual reviews of wildlife strike trends with civil aviation since the 1990s, little is known about wildlife strike trends for military aircraft. We hypothesized that species relative hazard scores would correlate positively with aircraft type and avian body mass. Only strike records identified to species that occurred within the U.S. (n = 36,979) and involved United States Navy or United States Air Force aircraft were used to calculate relative hazard scores. The most hazardous species to military aircraft was the snow goose (Anser caerulescens), followed by the common loon (Gavia immer), and a tie between Canada goose (Branta canadensis) and black vulture (Coragyps atratus). We found an association between avian body mass and relative hazard score (r2 = 0.76) for all military airframes. In general, relative hazard scores per species were higher for military than civil airframes. An important consideration is that hazard scores can vary depending on aircraft type. We found that avian body mass affected the probability of damage differentially per airframe. In the development of an airfield wildlife management plan, and absent estimates of species strike risk, airport wildlife biologists should prioritize management of species with high relative hazard scores