Powers and the Metaphysics of Fundamentality

In this dissertation, I address the question of whether ground, the relation that obtains between entities e1...en and a further entity e when e ontologically depends on, and is metaphysically explained by, e1...en, should be understood causally and, if so, whether this has any substantive implications. I answer both in the affirmative. I argue that ground and causation are similar enough to motivate characterizing ground as a special kind of causation, and that this can be done if we adopt a powers-theoretic account of causation. Moreover, I argue that the resultant view of ground, what I call “powerful, existential causation,” has important consequences for the debate between foundationalists, according to whom there must exist something fundamental that grounds all else, and infinitists, according to whom being might descend infinitely with nothing fundamental. Drawing on arguments and insights of medieval philosophers such as Ibn- Sīnā, Thomas Aquinas, and John Duns Scotus, I argue that if ground is understood as powerful, existential causation a strong argument can be formulated for foundationalism over infinitism. Thus, there must exist something fundamental whose existence is ungrounded, but which grounds the existence of everything else

Investigating Autophagy, Extracellular Vesicles, and Glycobiology

Autophagy is a cellular process of degradation which degrades cellular materials in acidic organelles called lysosomes. Impairment of lysosomal degradation can lead to lysosomal storage disorders such as Parkinson\u27s Disease. In Parkinson\u27s Disease neurotoxic α-synuclein can spread from cell-to-cell via extracellular vesicles. We investigated the changes in extra vesicular glycans upon perturbation of autophagy using a class of glycan binding molecules termed lectins. We found that upon induction of autophagy causes EV glycans to increase while others remained consistent. Additionally, we found that specific glycans are increased more than others. Conversely, when lysosomal degradation was impaired, we observed a decrease in EV glycans and that specific glycans decreased more than others

Design Considerations of a Magnus Effect Flettner Rotorcraft

Airfoils have dominated the development of aircraft since the Wright brothers’ first flight. There are very few (if any) functional alternative mechanisms for heavier-than-air flight. However, in exploring the Magnus effect phenomenon applied to Flettner rotors in a rotorcraft configuration, a new and significantly underdeveloped method of heavier-than-air flight may be accomplished. Considering the aerodynamic context of the Magnus effect and its implementation in existing applications, this research principally concerns a single proposed mechanism and its design, viability, and lift-surface optimization. The proposed mechanism employs at least two 180o offset rotating cylinders rotating about a central vertical axis, like a helicopter rotor, with the backspin of the cylinders generating lift according to Bernoulli’s principle, Newton’s third law, and the Magnus effect

Structural Characterization of HIP2 Enzyme Interactions in Ubiquitination

The ubiquitin proteolysis pathway utilizes three enzymes, an E1 activating enzyme, an E2 conjugating enzyme and an E3 ligating enzyme, to respectively activate, transfer and ligate ubiquitin (Ub) onto a substrate protein. The creation of a K48-linked poly-Ub chain on a substrate will target this protein to be degraded by the 26S proteosome. E2 conjugating enzymes are central proteins in this pathway and interact with the E1 and E3 enzymes to perform Ub transfer. The mechanism by which Ub molecules are interconnected remains poorly understood. The E2 enzymes HIP2 and Ubc1 have been shown to create poly-Ub chains in the absence of E3 enzymes and substrates. In this thesis, HIP2 and Ubc1 were investigated through physical and structural methods to clarify their mechanism of poly-Ub chain assembly. The study of HIP2 and Ubc1 was aided by the formation and purification of stable HIP2-Ub and Ubc1-Ub disulphide linked complexes that closely resemble the HIP2~Ub and Ubc1~Ub thiolester intermediates. The physical techniques of sedimentation equilibrium and SAXS determined that HIP2 and Ubc1 as well as their disulphide complexes are predominantly monomeric. Activity assays were also performed on these enzymes indicating that the E2~Ub thiolester is the sole species required to create poly-Ub chains. Additionally, these assays determined that both free Ub and E2-Ub complexes could act as Ub acceptors for poly-ubiquitin chain extension. NMR experiments were also performed through the use of isotopically labelled HIP2, HIP2-Ub and HIP2-Ub2 complexes. NMR chemical shift perturbation experiments identified significant intramolecular interactions between HIP2 and Ub in both HIP2-Ub and HIP2-Ub2 complexes. The intramolecular interaction within HIP2-Ub2 utilizes a C-terminal Ub-associated (UBA) domain and this domain is not present in other human E2 enzymes. These intramolecular interactions indicate the HIP2-Ub and HIP2-Ub2 complexes behave predominantly as Ub donors within poly-Ub chain formation. These results have allowed the formulation of mechanisms to describe HIP2 and Ubc1 function. The determination of these mechanisms is especially important for HIP2, as its function has been associated with the progression of both Huntington’s and Alzheimer’s disease

Students\u27 Perceptions of Learning Course Objectives: On Campus Versus Virtual Sections of One Course

The college course used in this project is required for students majoring in the Elementary Education and Early Childhood Unified Programs. Sections of the course are offered virtually as well as on the campus. This paper examines students\u27 scores on an assignment called the Course Objective Reflection to determine if course format made a difference in the candidates\u27 perceived learning of the six course objectives. Preliminary results indicate that virtual students achieved higher aggregate scores on the assignment than students completing the class on campus

Experimentation and Analysis of Composite Scarf Joint

Composite bonded scarf repairs were examined by experimentally measuring and analytically predicting the residual curing strains and strains due to mechanical loading. To accomplish this a three prong approach was used: a full strain field through a repaired laminate\u27s thickness was measured for both a loaded specimen and a specimen with the residual strain released, models were developed for comparison to both states, and data was collected for large tensile test specimens at various stages of being scarf repaired. A ~14:1 straight scarfed one-inch wide specimen was used to collect Moire interferometry data to calculate a full strain field due to mechanical loading and strain release. A three-dimensional thermo mechanical linear elastic analysis using an Air Force Research Laboratory in-house stress analysis program B-Spline Analysis Method (BSAM) results were correlated to the Moire interferometry test results. Three large tensile test specimens were tested as manufactured, three were tested with a scarfed hole in the center, and the remaining were tested with a scarf repair centered on a hole in the center. The strain gage results from the panels are presented. An additional feature of this work was to document each of the difficulties present in the given methods incorporated in this research

A Global Assessment of Long-Term Greening and Browning Trends in Pasture Lands Using the GIMMS LAI3g Dataset

Pasture ecosystems may be particularly vulnerable to land degradation due to the high risk of human disturbance (e.g., overgrazing, burning, etc.), especially when compared with natural ecosystems (non-pasture, non-cultivated) where direct human impacts are minimal. Using maximum annual leaf area index (LAImax) as a proxy for standing biomass and peak annual aboveground productivity, we analyze greening and browning trends in pasture areas from 1982-2008. Inter-annual variability in pasture productivity is strongly controlled by precipitation (positive correlation) and, to a lesser extent, temperature (negative correlation). Linear temporal trends are significant in 23% of pasture cells, with the vast majority of these areas showing positive LAImax trends. Spatially extensive productivity declines are only found in a few regions, most notably central Asia, southwest North America, and southeast Australia. Statistically removing the influence of precipitation reduces LAImax trends by only 13%, suggesting that precipitation trends are only a minor contributor to long-term greening and browning of pasture lands. No significant global relationship was found between LAImax and pasture intensity, although the magnitude of trends did vary between cells classified as natural versus pasture. In the tropics and Southern Hemisphere, the median rate of greening in pasture cells is significantly higher than for cells dominated by natural vegetation. In the Northern Hemisphere extra-tropics, conversely, greening of natural areas is 2-4 times the magnitude of greening in pasture areas. This analysis presents one of the first global assessments of greening and browning trends in global pasture lands, including a comparison with vegetation trends in regions dominated by natural ecosystems. Our results suggest that degradation of pasture lands is not a globally widespread phenomenon and, consistent with much of the terrestrial biosphere, there have been widespread increases in pasture productivity over the last 30 years

Pacific Ocean Forcing and Atmospheric Variability are the Dominant Causes of Spatially Widespread Droughts in the Contiguous United States

The contributions of oceanic and atmospheric variability to spatially widespread summer droughts in the contiguous United States (hereafter, pan-CONUS droughts) are investigated using 16-member ensembles of the Community Climate Model version 3 (CCM3) forced with observed sea surface temperatures (SSTs) from 1856 to 2012. The employed SST forcing fields are either (i) global or restricted to the (ii) tropical Pacific or (iii) tropical Atlantic to isolate the impacts of these two ocean regions on pan-CONUS droughts. Model results show that SST forcing of pan-CONUS droughts originates almost entirely from the tropical Pacific because of atmospheric highs from the northern Pacific to eastern North America established by La Nia conditions, with little contribution from the tropical Atlantic. Notably, in all three model configurations, internal atmospheric variability influences pan-CONUS drought occurrence by as much or more than the ocean forcing and can alone cause pan-CONUS droughts by establishing a dominant high centered over the US montane West. Similar results are found for the Community Atmosphere Model version 5 (CAM5). Model results are compared to the observational record, which supports model-inferred contributions to pan-CONUS droughts from La Nias and internal atmospheric variability. While there may be an additional association with warm Atlantic SSTs in the observational record, this association is ambiguous due to the limited number of observed pan-CONUS. The ambiguity thus opens the possibility that the observational results are limited by sampling over the 20th-century and not at odds with the suggested dominance of Pacific Ocean forcing in the model ensembles

Design principles for shift current photovoltaics

While the basic principles and limitations of conventional solar cells are well understood, relatively little attention has gone toward maximizing the potential efficiency of photovoltaic devices based on shift currents. In this work, we outline simple design principles for the optimization of shift currents for frequencies near the band gap, derived from the analysis of a general effective model. The use of a novel sum rule allows us to express the band edge shift current in terms of a few model parameters and to show it depends explicitly on wavefunctions via Berry connections in addition to standard band structure. We use our approach to identify two new classes of shift current photovoltaics, ferroelectric polymer films and single-layer orthorhombic monochalcogenides such as GeS. We introduce tight-binding models for these systems, and show that they exhibit the largest shift current responsivities at the band edge reported so far. Moreover, exploring the parameter space of these models we find photoresponsivities that can exceed $100$ mA/W. Our results show how the study of the shift current via effective models allows one to improve the possible efficiency of devices based on this mechanism and better grasp their potential to compete with conventional solar cells.Comment: 10 pages, 4 figures, AC and BMF share equal contributions. Published in Nature Communication