VictorJuiz/thesis huggingface dataset:
The intersection of right and good in Kant's metaphysics of morals [electronic resource]
Keywords: Philosophy

My dissertation focuses on the ways that erroneous beliefs contributing to conclusions about what we morally ought to do can and cannot be legitimately employed within a Kantian context. I approach this issue through questions about Kant's theory of conscience and the role of conscience in moral decision-making. According to the standard reading of Kant's ethics, there is a single set of objectively correct duties for all agents. On my reading, by way of contrast, an agent's duties are determined to some extent by his/her beliefs about the world. In other words, I give a defense of a kind of limited pluralism within Kant's ethics. I do this by arguing for three main claims. First, I argue (in chapters 1 and 2) that in Kant's ethics agents with similar core values but different beliefs about how the world works will arrive at very different (but nonetheless reasonable) conclusions about what they ought to do in particular situations. Second, I argue (in chapters 3 and 4) that according to Kant an agent who acts according to his/her conscience is behaving permissibly. And third, I argue (in chapters 5 and 6) that for Kant juridical duties are fundamentally different from ethical duties, so an ethical pluralism could be represented in a single (Kantian) state despite the fact that there are limits as to what counts as reasonable. In this way, I hope to show that even within Kant's system of objective value, because agents might have different beliefs about how the world works, there is no determinable set of judgments for a set of circumstances that exists independently of those agents' beliefs and intentions. To put this another way (to bring out where I diverge from the now-standard reading of Kant's ethics), I am arguing that the results of Kant's moral standard, the Categorical Imperative (CI), are radically underdetermined without information about an agent's beliefs about how the world works. One can determine whether something is permissible for an ideal agent (with only true beliefs); one can determine whether something is permissible for some given, fallible agent; but one cannot determine whether something is permissible simpliciter, for it is indeterminate. In slogan form, the underlying idea of this is that for Kant permissibility does not exist in a vacuum. We can make judgments about permissibility only for a given context, and part of that context includes information about an agent and his/her beliefs about how the world works.
Intrinsic mechanisms controlling the subcellular localization, size, and number of synapses [electronic resource]
Keywords: Biology.

Nervous system function requires the structural and functional integrity of chemical synapses, the fundamental units of neural communication. Synapse formation requires the packaging of synaptic vesicle (SV) and active zone (AZ) proteins into vesicular cargoes in the cell soma, their long-distance microtubule-dependent transport down the axon and finally, their clustering and assembly into functional complexes at specific sites. The subcellular localization, size, and number of synapses diverse greatly between different types of neurons and are critical determinants of the identity and strength of neural connections. Compared to our knowledge of extrinsic signals and cell-surface molecules that regulate synapse formation and synaptic specificity, less is known about the intrinsic regulatory mechanisms that regulate presynaptic protein transport and assembly to achieve proper spatial distribution of synapses. We have taken advantage of the powerful genetics in Caenorhabditis elegans to investigate this question. Using in vivo time-lapse fluorescence microscopy in a motor neuron DA9 in C. elegans, we show that SV and AZ proteins exhibit extensive co-trafficking and undergo frequent pauses during axonal transport. At the pause sites, the balance between the capture and dissociation of mobile transport packets determines the extent of presynaptic protein clustering. Through forward genetic screens, we identified a molecular regulatory network that controls the capture and dissociation events to dictate the spatial distribution of presynaptic specializations. First, we identified an Arf-like small G protein, ARL-8, that regulates synapse distribution by inhibiting premature clustering of presynaptic cargoes during axonal transport. arl-8 mutants accumulate presynaptic specializations within the proximal axon of several neuronal classes, with a corresponding failure to assemble presynapses distally. Time-lapse imaging analysis revealed that presynaptic cargoes in arl-8 mutants exhibit a decreased tendency to dissociate from immotile clusters and an increased probability of being captured by immotile clusters. We further performed genetic suppressor screens to isolate molecules that functionally interact with arl-8 in presynaptic patterning. We report that loss-of-function mutations in a JKK-1/JNK-1 MAP kinase pathway and several active zone assembly proteins strongly and partially suppress the abnormal distribution of presynaptic proteins in arl-8 mutants. Time-lapse imaging analysis demonstrated that the JNK kinase pathway and active zone assembly molecules inhibit presynaptic protein dissociation. In addition, we found that the kinesin motor UNC-104/KIF1A controls the capture efficiency. Furthermore, UNC-104/KIF1A functions as an effector of ARL-8 by binding specifically to the GTP-bound form of ARL-8. Together, these findings revealed novel intrinsic mechanisms that control the subcellular localization, size, and number of synapses by coordinating axonal transport with presynaptic assembly.
Investigating Wnt/ss-catenin signaling in stem cells and progenitors of the developing and adult mouse brain [electronic resource]
Keywords: Developmental Biology.

In order for a tissue to be properly sized and patterned, enormous care must be taken to ensure that cell proliferation and differentiation are tightly regulated. The embryonic brain must execute a temporally and spatially defined developmental scheme, resulting in the production of millions of cells of multiple lineages. These cells and their resultant functional architecture must be maintained in the homeostatic adult mouse brain. These processes are in part controlled by external signaling factors, which include Wnts, and their transcriptional programs. However, the degree to which and exact mechanisms by which cell fate choices--including self-renewal, proliferation, and differentiation--are controlled by Wnt/ss-catenin signaling are unknown. Here, I describe studies to investigate these questions. First, I show the identification of a novel target of Wnt/sscatenin signaling, Pou6f1, which mediates neural differentiation and proliferation in embryonic neural progenitor cells. Next, I illustrate the use of a lineage tracing approach using a Wnt/ss-catenin target gene, Axin2, to identify and trace sites of Wnt/ss-catenin responsiveness in the developing and adult mouse brain and central nervous system. Using this same Axin2CreERT2 mouse, I describe the functional consequences of loss of sscatenin from Axin2-expressing cells. Axin2CreERT2 labels numerous radial glial cell populations throughout the central nervous system, three of which serve as functional stem/progenitor populations. Loss of ss-catenin from adult Axin2+ populations results in tissue architecture defects and increased proliferation, presumably because Wnt serves as a self-renewal signal. These studies demonstrate the importance of Wnt/ss-catenin signaling for mediating multiple cell fate choices during the development and homeostasis of the mouse central nervous system, and suggest mechanisms by which neural stem/progenitor populations could be manipulated for therapeutic outcomes.
An investigation of liquefying hybrid rocket fuels with applications to solar system exploration [electronic resource]
Keywords: Aeronautics and Astronautics

Developments in hybrid propulsion technology over the past several decades have made these motors attractive candidates for a variety of applications. In the past, they have been overlooked due to the low regression rate of classical hybrid fuels or in favor of the heritage and commercial availability of liquid or solid propulsion systems. The slow burning rate translates into either a reduced thrust level or the requirement for a complicated, multi-port fuel grain to increase the available burning surface area. These major disadvantages can be mitigated through the use of liquefying hybrid fuels, such as paraffin. Typically, this increase is enough to achieve desired thrust levels with a simple, single port design. Benefits unique to the paraffin-based hybrid design makes it a competitive and viable option for solar system exploration missions. Two specific examples are included to illustrate the advantages of hybrids for solar system exploration. A hybrid design for a Mars Ascent Vehicle as part of a sample return campaign takes advantage of paraffin's tolerance to low and variable temperatures. Hybrid propulsion systems are well suited for planetary orbit insertion because of their ability to throttle, stop and restart at high thrust levels. The high regression rates of liquefying hybrid fuels are due to a fuel entrainment mass transfer mechanism. The design, assembly and results of an experiment to visualize this mechanism are presented. A combustion chamber with three windows allows visual access to the combustion process. A flow conditioning system is employed to create a uniform oxidizer flow at the entrance to the combustion chamber. Experimental visualization of entrainment mass transfer will enable the improvement of combustion models and therefore future hybrid designs.
Investigations of ruthenium transfer hydrogenation catalysts as electrooxidation catalysts for alcohols [electronic resource]
Keywords: Chemistry

One of the premier challenges in energy research is the development of efficient methods to convert chemical fuels into useful forms of energy with reduced greenhouse gas emissions. The reversible electrodehydrogenation of liquid fuels, such as alcohols, would provide a means for the efficient release of energy and energy storage, if electrocatalysts that operate at the appropriate potentials can be developed. Currently, even the most highly optimized alcohol electrooxidation catalysts suffer from kinetic limitations that require high overpotentials to achieve reasonable rates despite significant effort in the design of heterogeneous methanol and isopropanol electrooxidation catalysts. With the perspective that the fundamental gaps in understanding of the energetic requirements of critical chemical steps for reversible electrodehydrogenation are the major impediments to further progress, mechanistic examination of the relevant chemical and electrochemical events of molecular complexes may illuminate the properties of a catalyst required to effect energy efficient conversion of chemical fuels. A new conceptual approach to the discovery of catalysts is proposed: The approximate thermoneutrality of chemical transfer hydrogenation catalysis implicates their catalysts as viable candidates for reversible electrodehdyrogenation catalysts. In transfer hydrogenation reactions, alcohols are oxidized with zero driving force, the thermodynamic equivalent of an electrochemically reversible alcohol oxidation at the thermodynamic potential of the alcohol. Ruthenium arene transfer hydrogenation catalysts are investigated for the electrooxidation of alcohols. They are shown to serve as active electrocatalytic precursors and exhibit rapid rates for alcohol oxidation when supported on electrodes in basic aqueous solution. The first examination of organometallic reactions and of species on electrode surfaces via desorption ionization electrospray mass spectrometry are performed. These studies provide support for the proposed electrocatalytic mechanism for alcohol oxidation by the Ru-arene complexes. Additionally, Ru transfer hydrogenation catalysts are shown to reversibly and catalytically oxidize methanol to methyl formate. Mechanistic studies of octahedral ruthenium transfer hydrogenation catalysts are carried out to gain insight into the types of homogeneous reaction mechanisms are amenable to translate into catalytic electrochemical mechanisms. The octahedral complexes are studied extensively by cyclic voltammetry; however, preparative electrolysis results in the presence of alcohols did not provide clear evidence for the electrooxidation of methanol or isopropanol. Possibilities for the absence of oxidation products are discussed as well as the challenges in developing molecular electrocatalysts, particularly in translating catalytic homogeneous two electron chemistry to heterogeneous one electron electrochemistry.
Issue representation in the 107th-111th congresses [electronic resource]
Keywords: Political Science.

In order to assess the quality of our democracy, it is important to understand how often, and in what circumstances, legislators follow the will of their constituents. But scholars still have only a limited understanding about the degree to which legislators follow their constituents' preferences on individual issues. In this dissertation, I develop new techniques to accurately measure the policy preferences of the American public at a variety of geographic levels, including states, congressional districts, and state legislative districts. I use this approach to evaluate the degree to which members of the United States House represent the preferences of their constituents on a wide range of issues. I find that representatives are highly responsive to issue-specific public opinion, but they are more responsive to their partisan sub-constituencies than independents. Next, I examine whether vigorous electoral competition improves the link between legislators and their constituents. I find that legislators are more responsive to their constituents in electorally competitive districts. Moreover, they are less responsive to their partisan sub-constituency. Finally, I examine whether there is a stronger link between legislators and their constituents on the most salient, important issues. I find that greater issue salience does not increase legislators' responsiveness to their average constituent. Instead, representatives are more responsive to their partisan sub-constituency on salient issues. In addition, legislators' roll calls are more likely to be congruent with the opinion of a majority of their partisans on salient issues. Taken together, this dissertation deepens our understanding of representative democracy in the United States.
Jet substructure for the LHC [electronic resource]
Keywords: Physics

The discovery of new physics at the LHC hinges on our ability to discriminate the old (the Standard Model) from the new. The study of the substructure of jets offers a powerful set of techniques for improving the reach of new physics searches at the LHC. Moreover, jet substructure observables are a sensitive probe of QCD dynamics and motivate a variety of tests of QCD. This thesis explores several jet substructure techniques with a particular focus on applications to event discrimination. First, a jet observable is introduced that probes the color structure of pairs of subjets. This observable is incorporated into a top tagging algorithm, where it is shown to improve discrimination between top jets and QCD jets. Second, an alternative approach to jet substructure is introduced that is distinct from the prevailing methods based on the clustering trees induced by sequential jet algorithms. This approach makes use of two-particle angular correlations to identify substructure within jets. In one application, this approach is used to construct a top tagging algorithm that is competitive with existing methods. In another application, ensemble averages of angular correlations are used to study the underlying event and pile-up effects.
Knowing what follows [electronic resource] : epistemic closure and epistemic logic
Keywords: Philosophy

The starting point of this dissertation is a simple but central question in epistemology and epistemic logic: roughly, if an agent knows that a proposition P follows from some other propositions, must she know P if she knows the others? In other words, must the set of propositions she knows be "closed under known implication"? This idea of full epistemic closure raises a tension with an attractive idea of fallibilism about knowledge. According to fallibilism, knowing a true proposition Q does not require ruling out every remote possibility of error or deception with respect to Q. If it did, we would know almost nothing. The tension between fallibilism and closure arises when a proposition S picks out a class of remote possibilities in which Q is false, so we know Q implies not-S. While fallibilism may say that we can know Q without ruling out the possibilities picked out by S, closure says that we know Q only if we know not-S. Although not a formal contradiction, this is a tension to say the least. In this dissertation, I explore the extent to which it is possible to make fallibilism compatible with closure. I begin by formalizing a family of fallibilist theories of knowledge in models for epistemic logic. Model-theoretic techniques are used to characterize the closure properties of knowledge according to different fallibilist pictures, identify the structural features of these pictures that correspond to closure properties, transform models of one theory into models of another, prove impossibility results, and ultimately find a middle way between full closure and no closure for fallibilism. I argue that the standard versions of "Fallibilism 1.0" each face one of three serious problems related to closure: the Problem of Vacuous Knowledge, the Problem of Containment, and the Problem of Knowledge Inflation. To solve these problems, I propose a new framework for Fallibilism 2.0: the Multipath Picture of Knowledge. This picture is based on taking seriously the idea that there can be multiple paths to knowing a complex claim about the world. An overlooked consequence of fallibilism is that these multiple paths to knowledge may involve ruling out different sets of alternatives, which should be represented in our picture of knowledge. I argue that the Multipath Picture of Knowledge is a better picture for all fallibilists, whether for or against full closure. Yet I also argue that only by accepting less than full closure can we solve the closure-related problems that plague previous versions of fallibilism.
Landing and perching on vertical surfaces [electronic resource]
Keywords: Mechanical Engineering

Perching combines the best of both climbing and flying platforms. While flying, the vehicle is agile and can cover long distances quickly. When perched, the same vehicle now has reduced energy expenditure, is quiet and can wait for better flying conditions. Perching could be used in search-and-rescue or surveillance operations, and opens the way to many new applications including reconfigurable sensor networks, close proximity inspection of structure or sample-and-return missions. In this thesis, we discuss an approach allowing small airplanes to land on rough vertical surfaces using micro-spines. The technique presented consists in flying toward the wall at cruise speed (10m/s), triggering a pitch up maneuver at the appropriate distance from the wall to rapidly slow down and absorb the remaining kinetic energy at impact with a suspension that also favors the engagements of the micro-spines. This suspension creates a landing envelope of successful touchdown conditions, which can be easily reached by the airplane assuming a properly designed airframe. This thesis proposes and validates an hybrid model of the suspension used to determine the size of the landing envelope. Furthermore, to create the largest landing envelope possible, an extension to current region of attraction estimation techniques is proposed. This extension uses sums-of-squares optimization, which combines polynomial approximations of barrier constraints with the traditional Lyapunov methods to achieve tight estimation in the presence of barriers. Finally, the flying dynamics are analyzed and a simple model is developed by approximating the maneuver in three distinct phases based on the angle of attack of the wing (AoA). The results presented provide a better understanding of the parameters determining the shape of the landing envelope created by the suspension, but also the parameters of the airframes shaping the funnel that brings the airplane from normal flying conditions to the landing envelope. Furthermore, the region of attraction extension was tested on a simple model of the airplane and showed a 12x improvement in the area size estimated. Ultimately, the airplane designed with the insights gained with that work was able to perform 20 consecutive autonomous landings in outdoor conditions using only onboard sensors (i.e. laser range finder, accelerometers and gyroscopes).
Large data algorithmics [electronic resource]
Keywords: Electrical Engineering

In this thesis, we will explore the algorithmic aspect of large data applications on distributed frameworks. In the distributed batched processing setting, I will present highly scalable algorithms for the densest subgraph detection primitive in massive networks, as well as an efficient scalable algorithm called k-means [vertical line][vertical line] for the k-means clustering problem. In the distributed real-time processing setting, I will present algorithms for two important applications: incremental PageRank computation, and real-time social search.
Large eddy simulation of soot evolution in turbulent reacting flows [electronic resource]
Keywords: Mechanical Engineering

Soot particles are nanoparticles consisting primarily of carbon that are formed during the combustion of fuel-rich mixtures. Due to environmental and health concerns, soot emissions from combustion systems are tightly regulated, and this regulation will only become stricter in the future. To enable the design of the next generation of low-emission combustion systems, predictive numerical simulations will be required. However, soot is a particularly difficult modeling problem due to the needs for high-fidelity models for soot itself in addition to chemistry and turbulence. This dissertation seeks to develop an integrated modeling framework based on Large Eddy Simulation (LES) for soot evolution in turbulent reacting flows. The final objective is the demonstration and evaluation of the model in an actual aircraft combustor. In order to enable these high-fidelity simulations, three component models have been developed. First, a detailed soot model is developed within the framework of the Method of Moments. New models for soot aggregation and fragmentation are proposed, and closure of the moment source terms is achieved with the Hybrid Method of Moments (HMOM), an accurate yet computationally efficient method. Second, a new turbulent combustion model is developed based on the Radiation Flamelet/Progress Variable (RFPV) model that can account for the removal of precursors from the gas-phase to form soot particles. Third, a subfilter PDF model is developed to account for the unresolved small-scale interactions between soot, turbulence, and chemistry. The subfilter PDF approach is validated a priori against a recent DNS database of soot evolution in a turbulent nonpremixed flame. The integrated modeling approach is then validated against experimental measurements in two laboratory-scale turbulent nonpremixed flames: a natural gas piloted jet flame and an ethylene bluff body flame. Differences in soot evolution due to the differences in the large-scale mixing in the two flames are discussed. The validated model is then applied to the simulation of a Pratt & Whitney aircraft combustor. Two operating points are simulated to assess the ability of the integrated model to reproduce quantitative trends in soot emissions.