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UC Santa Barbara Electronic Theses and Dissertations

Cover page of Bisexuality and /s/ production

Bisexuality and /s/ production

(2020)

The folk linguistic notion that there are systematic differences in speech production as a function of sexual orientation has given rise to a vast body of work investigating the acoustic correlates of sounding queer. Although gay-sounding voices and to a lesser extent lesbian-sounding voices are well represented in this literature, bisexuality is conspicuously absent. The current study addresses this gap through an acoustic analysis of bisexuals' read speech vis-à-vis lesbian, gay, and straight speakers, specifically attending to three measures of the fricative /s/: center of gravity, skew, and duration. The results suggest that bisexual women and men do not form a cohesive group in terms of /s/ production. Moreover, the results indicate that bisexual women differ from lesbian and straight women in a way that is distinct from how bisexual men differ from gay and straight men. Given these results, I argue that (1) grouping bisexual speakers with either straight or lesbian/gay speakers is not empirically justified and (2) the lack of uniformity among the bisexual speakers is potentially explained by the different ways in which bisexual women and men experience the intersection of sexuality and gender normativity. Overall, these findings trouble the stereotype that bisexuality is simply an amalgam of lesbianness/gayness and straightness and shed light on the intersectional experiences of bisexuals.

Cover page of Travels through the Foreign Imaginary on the Plautine Stage

Travels through the Foreign Imaginary on the Plautine Stage

(2020)

This dissertation explores the ways in which Plautus’s comedies, inherently translated works, negotiate foreign characters and foreignness within their hybrid theatrical and extra-theatrical spaces. This project is part of a larger discourse on the tension between Greek, Roman, and non-Greek foreign elements in Plautus’s comedies. The three plays I analyze above display foreignness through particular theatrical elements: Curculio's stage situations, Poenulus's characters, and Persa's use of props and spatial vocabulary. In all of these elements, two things are brought into prominence: the negotiations of identity and the use of what I call “foreign imaginary,” both of which show the ultimate breakdown of any dichotomy between the foreign and the familiar. I have coined the term “foreign imaginary” to refer to the foreign parts of the world which exist just out of sight of the audience, offstage. The foreign imaginary is almost always brought into a play when a character or object appears onstage. Moreover, it is usually an object which is considered distantly foreign (a coin with an elephant on it, as seen in the Curculio, or a tiara and a pair of fancy slippers, as in the Persa), and frequently resolves a major conflict within the play. However, we must not forget that at least some of the “ordinary” Greek characters appeared from the same entrances onstage. It is therefore possible that the lines between “foreign,” “imaginary and foreign” “familiar,” “domestic,” or any other demarcations, are (or should be) blurred. This constant renegotiation of categories and boundaries is what leads me to a Bhabhaian reading of Plautine comedy.

I show through the lens of theory that elements of Plautine comedy reflect a contemporaneous discourse between the familial and the foreign. While Plautine comedy predates European colonialism by at least two millennia, hybridity as defined by Homi Bhabha offers a useful lens for examining Roman comedy. Bhabha views hybridized culture as an ever-changing phenomenon comprised of moments of negotiation between cultures. We see in the chaotic period of Plautus’s career that Plautus is not writing from within a “Graeco-Roman” landscape fixed in time from which interested parties may pick out what is Greek and what is Roman. Instead, he deals with a ‘third space’ which is constantly in flux --- a moment within which cultures communicate and are negotiated. Theater in Rome is a Greek import featuring adaptations of Greek plays ostensibly set in Greek cities peopled by “Greeks” who speak Latin and are familiar with Roman laws. The panoply of stock characters and conventions that Roman comedy has inherited from Greek comedy already has a value system that is neither exclusively Greek nor exclusively Roman. The uncertainty that surrounds Plautus’s theater makes taking the Bhabhaian approach feel particularly appropriate – the play is both Roman and foreign, its stage both present and evanescent, its context political and private by turns. My study of Plautus analyzes these singular elements to offer a new postcolonial reading of the presence of the foreign character in Roman comedy.

Cover page of The effects of parasites on the kelp-forest food web

The effects of parasites on the kelp-forest food web

(2020)

Parasites often track food web linkages through their complex life cycles, but most food webs do not systematically include parasites. Where studied, parasites have strong effects on food web structure. Kelp forests are famous for strong trophic interactions, and their dynamic and open nature make them very different relative to the systems where parasites have been thoroughly studied (salt marsh, sand flat, and lake ecosystems). The objective of this dissertation was to build a high-resolution topological kelp-forest food web that includes parasites. I used this food web to address the research question: How do parasites affect food-web structure? Chapter 1 provides background and motivation for this work by reviewing key areas of research in kelp forest ecology and the effects of parasites in food webs. Chapter 2 describes the study system and a free-living food web with 490 species across 23 Phyla, with 546 distinct life stages and 8,759 trophic interactions. Chapter 3 describes the parasites in the food web, which adds 422 species across 10 Phyla (521 life stages) and 2,745 trophic interactions between parasites and hosts to the network for a total of 11,504 links. Adding trophic interactions between predator and parasites (concomitant predation) adds a further 9,536 links to the network. Chapter 4 examines the effects parasite addition on food-web structure. The kelp-forest food web was greatly enriched through resolution of free-living species and parasites, and parasites made up a larger proportion of the kelp-forest food web than any other published food web with parasites. Some of the effects of parasite addition were related to increasing network size and contrasted patterns in other systems (e.g. decreased connectance). On the other hand, other effects (e.g. longest chain length) were consistent with predictions based on other systems and were not due to increased network size alone. Specialist parasites and concomitant links altered the degree distribution independent of network size. Parasite life cycles are embedded throughout diverse patterns of free-living species interactions and must navigate a dense network of predators to infect appropriate hosts. The kelp forest ecosystem provides a diverse source of food and a diverse set of predators for both free-living and parasitic species, and our understanding of kelp forest ecosystems is enriched by including them.

Cover page of Constraining Hydraulic Properties in Oceanic Crust near the Juan de Fuca Spreading Center

Constraining Hydraulic Properties in Oceanic Crust near the Juan de Fuca Spreading Center

(2020)

Until recently, oceanic crust aquifer properties were estimated from single-borehole experiments and mathematical modeling. This dissertation presents multi-tracer data from a cross-borehole tracer experiment in a hydrothermal system on the eastern flank of the Juan de Fuca Ridge. A rapid tracer breakthrough induced by a ~548 m3 fluid injection suggests that effective porosity is several orders of magnitude lower than bulk material porosity and ridge-parallel anisotropy may have a large effect on fluid flow in shallow ocean crust. Nine years of data suggest that chaotic local convection does not operate on the 102 – 103 m scale encompassing this field site. The low effective porosity precludes application of the conventional point-source model for tracer experiments and necessitates the development of a new conceptual model to explain observed tracer breakthroughs and derive aquifer properties. The average linear flow velocity at this site is found to be ~1 m/d. At the 102 – 103 scale, the representative elemental volume (REV) is constrained for future use in more accurately modeling oceanic crust as a porous medium.

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Cover page of Graphical Models in Financial Market and Portfolio Allocation: Applications and Considerations

Graphical Models in Financial Market and Portfolio Allocation: Applications and Considerations

(2020)

In recent years, the L-1 regularization has been extensively used to estimate a sparse precision matrix and encode an undirected graphical model. Because the regularized estimates are biased, the application of the graphical models has largely been restricted and has been ignored in many areas. In this work, we show that graphical models and their regularized estimates can be useful in the area of finance. We present our discussion in three parts. First, we propose a graphical representation model for the asset returns. The model captures observed variance in the equity market endogenously and offers a new perspective on the covariance estimation for asset returns. We show that such a model may provide a straightforward interpretation for investors regarding investment decision making. Second, we show that regularized estimates of graphical models, though biased, are useful to estimate the minimum variance portfolio and determine the portfolio rebalancing strategy. Third, we discuss the algorithms of solving one of the graphical models -- the graphical Concord. We present the software development process for the graphical Concord and illustrate the usage of the packages with some examples.

Cover page of Photodegradation Stimulates Microbial Activity Through Enhanced Water Solubility of Grass Litter Carbon

Photodegradation Stimulates Microbial Activity Through Enhanced Water Solubility of Grass Litter Carbon

(2020)

Solar radiation is an important contributing factor to decomposition in drylands. Research suggests that in the presence of water, previously irradiated plant litter experiences greater microbial decay than litter which was not exposed to radiation. It is unclear how exactly radiation alters litter to allow this photopriming of microbial decomposition. However, the relationship to water suggests that radiation may make litter more water-soluble, and therefore more accessible to decomposers once water enters the system. I tested the hypothesis that the abiotic impact of solar radiation on grass litter would (1) increase the production of dissolved organic carbon (DOC) when litter is subsequently extracted with water, and (2) produce DOC that stimulates more microbial activity compared to unexposed litter. Dried senesced grass litter from three species, Bromus diandrus, Avena fatua, and Hordeum murinum, were placed in sealed bags and subjected to abiotic decomposition in either an outdoor experiment or an indoor experiment. Treated litter was then soaked in water, and the extract was analyzed to determine the dissolved organic carbon concentration and its bioavailability. Exposure to radiation resulted in more DOC for all species in both the indoor and outdoor experiments, suggesting that solar radiation does enhance solubility of grass litter. During a microbial incubation, I observed a significant increase in CO2 production and a marginally significant increase in DOC consumption for samples exposed to more radiation in the indoor experiment. However, as a fraction of initial DOC available, radiation reduced these measures of microbial activity. This indicates that photodegradation produces compounds which are relatively difficult for microbes to decompose, but photodegradation can still stimulate microbial activity by increasing the total amount of available dissolved carbon. Taken together, these results suggest a possible mechanism for observed increases in mass loss due to photopriming: litter carbon is made more soluble by radiation, and is mobilized in the presence of water, allowing for increased microbial decomposition. This insight into decomposition mechanisms could aid in developing more mechanistic models of carbon cycling that include photopriming.

Cover page of Application of Mathematical Modeling in Cancer, Blood Clotting Abnormalities and Migraine Headaches Research

Application of Mathematical Modeling in Cancer, Blood Clotting Abnormalities and Migraine Headaches Research

(2020)

Mathematical modeling of biological processes has contributed significantly to improving our understanding of how different biological systems function, how and why different diseases start and develop, and how the diseases can be prevented or treated. In the first part of this dissertation, we use mechanistic modeling together with local and global sensitivity analyses to explore why different patients and/or different cancer types respond differently to retinoic acid (RA), an anticancer drug. Our findings indicate that the efficacy of RA treatment highly depends on intracellular levels of four main RA binding proteins namely, retinoic acid receptor (RAR), cellular retinoic acid binding proteins (CRABP1 and CRABP2) and cytochrome P450 (CYP). These proteins are expressed at different levels in different patients and/or cell types. Our results indicate that CRABP2 and RAR are the most and the least important receptors, respectively, in regulating the response to RA treatment at physiological concentrations (1–10 nM). However, at pharmacological concentrations of RA (0.1–1 μM), CYP and RAR are the most sensitive parameters of the model. These results can help in the development of pharmacological methods to increase the efficacy of the drug. In the second part of this dissertation, we study the positive side effects of RA therapy on blood clotting abnormalities in cancer patients. Although there are several lines of evidence regarding the improvement of hemostatic complications such as thrombosis and disseminated intravascular coagulation (DIC) in cancer patients undergoing RA therapy, the mechanisms underlying this improvement have yet to be understood. We build mechanistic and pharmacokinetics models and use in vitro and pharmacokinetics data from the literature to test the hypothesis that this improvement is due to RA-induced upregulation of thrombomodulin (TM) on the endothelial cells. Our results indicate that treatment with a single daily oral dose of 110 mg/m^2 RA, increases the TM concentration by almost two folds. We then show that this RA-induced TM upregulation reduces the peak thrombin levels and endogenous thrombin potential (ETP) up to 50 and 49%, respectively. Our results demonstrate that progressive reductions in plasma levels of RA, observed in continuous RA therapy with a once-daily oral dose of 110 mg/m^2 RA do not influence TM-mediated decrease in thrombin generation. This observation raises the hypothesis that continuous RA treatment will have more consistent therapeutic effects on coagulation disorders than on cancer. Our results reveal that the upregulation of TM expression on the endothelial cells over the course of RA therapy could significantly contribute to the treatment of coagulation abnormalities in cancer patients. In the last part of this dissertation, we use mechanistic modeling to study sodium homeostasis disturbance in the brain during migraines. Previous animal and human studies have revealed that migraine sufferers have higher levels of cerebrospinal fluid (CSF) and brain tissue sodium than control groups, while the underlying mechanisms of this increase are not known. Under the hypothesis that disturbances in sodium transport mechanisms at the blood-CSF barrier (BCSFB) and/or the blood-brain barrier (BBB) are the underlying cause of the elevated CSF and brain, we develop a mechanistic model of a rat’s brain to compare the significance of the BCSFB and the BBB in controlling CSF and brain tissue sodium levels. Our model consists of the ventricular system, subarachnoid space, brain tissue and blood. We model sodium transport from blood to CSF across the BCSFB, and from blood to brain tissue across the BBB by influx permeability coefficients P_BCSFB and P_BBB, respectively, while sodium movement from CSF into blood across the BCSFB, and from brain tissue to blood across the BBB were modeled by efflux permeability coefficients P_BCSFB^' and P_BBB^', respectively. We then perform a global sensitivity analysis to investigate the sensitivity of the ventricular CSF, subarachnoid CSF and brain tissue sodium levels to pathophysiological variations in P_BCSFB, P_BBB, P_BCSFB^' and P_BBB^'. Our findings indicate that the ventricular CSF sodium concentration is highly influenced by perturbations of P_BCSFB, and to a much lesser extent by perturbations of P_BCSFB^'. Brain tissue and subarachnoid CSF sodium concentrations are more sensitive to pathophysiological variations of P_BBB and P_BBB^' than variations of P_BCSFB and P_BCSFB^' within 30 minutes of the onset of the perturbations. However, P_BCSFB is the most sensitive model parameter, followed by P_BBB and P_BBB^', in controlling brain tissue and subarachnoid CSF sodium levels within 3 hours of the perturbation onset. Our findings suggest that increased influx permeability of the BCSFB to sodium caused by altered homeostasis of the enzymes which transport sodium from blood to CSF is the potential cause of elevated brain sodium levels in migraines.

Cover page of Even Children Get Older: Challenges and Potentials Adult Children of Queers Bring to Queer Theory

Even Children Get Older: Challenges and Potentials Adult Children of Queers Bring to Queer Theory

(2020)

Through interviews with adult children of queer parents, this paper begins to understand the possibilities, consequences, and limitations of queer families and to take seriously the lives and feelings of queer-raised adults as a potential site for theorizing. This project contributes to conversations in queer theory surrounding children and family – conversations that, while lively and contentious, have yet to contend with the actual experiences of adults raised by queer people. Through qualitative analysis of informal interviews with people raised by queer parents this thesis considers two main sites of tension – how adult children of queer people navigate and refuse visibility and legibility and how we respond to pressures to perform as the “happy, healthy and heterosexual” children of our parents. These themes, as well as our potential wisdom in intergenerational queer and feminist conversations, are potential entry points for taking adult children of queer seriously as thinkers in queer theory.

Cover page of Towards Segment-level Video Understanding: Detecting Activities from Untrimmed Videos

Towards Segment-level Video Understanding: Detecting Activities from Untrimmed Videos

(2020)

We generate massive amounts of video data every day. While most real-world videos are long and untrimmed with sparsely localized segments of interest, existing AI systems that can interpret videos today often rely on static image analysis or can only process temporal information in a short video snippet. To automatically understand the content of long video streams, this thesis mainly describes the efforts to design accurate, efficient, and intelligent deep learning algorithms for temporal activity detection in untrimmed videos.

Detecting segments of interest from untrimmed videos is a key step towards segment-level video understanding. Depending on the purposes of tasks being performed, we address three different activity detection tasks: detecting activities of interest from videos without specific purposes (i.e., temporal activity detection); detecting temporal segment that best corresponds to a language query (i.e., natural language moment retrieval); and detecting activities given less supervision (i.e., weakly-supervised or few-shot activity detection).

In temporal activity detection, We first propose a highly unified single-shot temporal activity detector based on fully 3D convolutional networks, by eliminating explicit temporal proposal and classification stages. Evaluations show that it achieves state-of-the-art on temporal activity detection while being super efficient to operate at 1271 FPS. We then investigate how to effectively apply a multi-scale architecture to model activities with various temporal length and frequency. We propose three novel architecture designs: (1) dynamic temporal sampling; (2) two-branch feature hierarchy; (3) multi-scale contextual feature fusion, and we combine all these components into a uniform network and achieve the state-of-the-art on a much larger temporal activity detection benchmark.

In natural language moment retrieval, we aim to localize the segment that best corresponds to a given language query. We present a language-guided temporal attention module and an iterative graph adjustment network to handle the semantic and structural misalignment between video and language. The proposed model demonstrates superior capability to handle temporal relations, thus, significantly improves the state-of-the-art by a large margin.

Finally, we study the problem of weakly-supervised and few-shot temporal activity detection to mitigate the drawbacks of huge amounts of supervision needed to train a temporal detection model. Namely, we answer the question if we can learn a temporal activity detector under weak supervision that is able to localize unseen activity classes. A novel meta-learning based detection method is accordingly proposed by adopting the few-shot learning technique of Relation Network. Results show that our method achieves performance superior or competitive to state-of-the-art approaches with stronger supervision.

In summary, we propose a suite of algorithms and solutions to automatically detect segments of interest in long untrimmed videos. We hope our studies could provide insights for researchers to explore new deep learning paradigms for future computer vision research, especially on video-related topics.

Cover page of Tailored composite microstructures via direct ink writing with acoustophoresis

Tailored composite microstructures via direct ink writing with acoustophoresis

(2020)

Additive manufacturing techniques which enable control over the placement and orientation of particles within composite inks can produce structures with tailored gradients in structural and functional properties. One such technique is direct ink writing with acoustophoresis (DIWA), wherein a composite ink is extruded through a direct-write nozzle containing a standing bulk acoustic wave which aligns and positions particles. Driving force-based scaling relationships contextualize processing-structure relationships in DIWA. In a series of experiments which progress in geometric complexity from basic primitives to complete structures, a physical framework is constructed for controlling filament microstructures and external geometries in DIWA. In isolated filaments, there are trade-offs between focusing and form holding. Increasing the ink viscosity, increasing the print speed, and decreasing the acoustic wave amplitude widen the spatial distribution of particles in agreement with scaling relationships for acoustophoresis, but more viscous inks improve form holding. In the print bead between the nozzle and substrate, digital image analysis is used to measure filament stability, nozzle wetting, and rotational flows in the low-viscosity inks required for acoustophoresis. Viscocapillary lubrication theory accurately predicts the bounds of stability, and the contact line position and angle can be used to detect the beginnings of filament rupture, allowing for algorithms which prevent rupture in-situ. In polygonal prisms, the internal structure of filaments changes during deposition into layer-by-layer and bath support gels. Filament microstructures change during deposition, during relaxation, and when the nozzle returns to write neighboring lines. Experimental flow fields and particle distributions suggest that inertia and viscoplasticity influence the filament microstructure just after deposition and the microstructure of neighboring filaments, and interfacial energy and gravity cause filaments to spread after deposition. An analytical model is proposed to diagnose sources of direction dependent microstructures as a function of acoustics, inertia, viscous dissipation, and stage calibration. The support geometry can be used to accentuate or suppress aspects of this direction dependence. Finally, inertia swells written corners, and capillarity smooths written corners, leading to distortions in filament microstructures at corners. Bath support suppresses these corner defects.