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Master's thesis recital (percussion)
Get PDF́Sonata for two pianos and percussion / Béla Bartók (with Maria Parrini and Michael Lenahan, piano, and Erika Lin, percussion) -- Caleidoscópio / Gene Koshinski -- Burritt variations / Alejandro Viñao -- Csárdás : for piano and marimba / Vittorio Monti ; arr. Kevin Luo.MusicName of supervisor not provided on progra
Dark matter or baryons : which sets the density of low-mass galaxies?
No full textWe investigate the central density structure of dark matter halos in cold dark matter (CDM) and self-interacting dark matter (SIDM) models using simulations that are part of the Feedback In Realistic Environments (FIRE) project. The simulated halos we study are dwarf galaxy scale (M [subscript halo] (z = 0) ≈ 10¹⁰ M [subscript ⊙]), and we investigate the central structure in both dissipationless simulations and simulations with full FIRE-2 galaxy formation physics. As has been demonstrated extensively in recent years, both baryonic feedback and self-interactions can convert central cusps into cores, with the former process doing so in a manner that depends sensitively on stellar mass at fixed M [subscript halo]. Whether the two processes (baryonic feedback and self-interactions) are distinguishable, however, remains an open question. Here, we demonstrate that SIDM-induced cores transition more quickly between the constant density central region and the falling density at larger scales relative to feedback-induced cores. This result holds true even when including identical galaxy formation modeling in SIDM simulations as is used in CDM simulations, as self-interactions dominate over galaxy formation physics in establishing the central structure of SIDM halos. The change in density profile slope as a function of radius therefore holds the potential to discriminate between self-interactions and galaxy formation physics as the driver of core formation in dwarf galaxies.Astronom
Remote sensing of river kinematics and their expression in the modern and ancient stratigraphic record
Get PDFAlthough the geomorphic and stratigraphic expression of rivers are inherently linked, major disconnects remain between the mechanisms and processes governing river kinematics in the modern and expression of these processes in the stratigraphic record. This dissertation approaches this enigma from both perspectives via analysis of modern river kinematics using timelapse satellite imagery and characterization of uniquely exposed ancient river deposits using photogrammetric and numerical modeling approaches. The research described herein focuses on three central themes: (1) the geomorphic and stratigraphic impact of perturbations (bend cutoffs and channel avulsions) on the large-scale kinematics of rivers; (2) the role of flood event-scale discharge variability on fine-scale patterns of erosion, deposition, and preservation along channel banklines; and (3) the three-dimensional nature of fluvial stratigraphy. Chapter 2 focuses on the map-view impact of bend cutoffs on subsequent lateral migration rates and patterns as captured by 37 years of Landsat satellite imagery using a newly developed automated channel extraction and tracking workflow called meandergraph. Results highlight direct linkages between formative post-cutoff bend curvature and subsequent map-view bend change at the cutoff site and in adjacent bends. Modeling results highlight challenges in predicting post-cutoff bend behavior with simple kinematic models but confirm post-cutoff bend curvature as an important contributor to planform bend change. Chapter 3 examines the role of event-scale discharge variability on patterns and magnitude of erosion and deposition along the Trinity River using a 7-year record of autonomously derived banklines from PlanetScope 3-m resolution optical imagery. This study is among the first to apply PlanetScope optical imagery to track spatiotemporal map-view river kinematics quantitatively. Results indicate linkages between peak and cumulative discharge on bankline kinematics, while illustrating the potential importance point bar erosion during low discharge conditions. Floods are shown to have a significant impact on net stratigraphic preservation and represent a significant fraction of deposits preserved within the channel over the 7-year period. Chapter 4 shifts focus to characterization of ancient fluvial processes, specifically processes and products of avulsion in the ancient stratigraphic record of the Cretaceous Cedar Mountain Formation in Utah, USA. This research integrates quantitative outcrop characterization with novel 3-D stratigraphic modeling approaches to reconcile linkages between avulsion processes and their 3-D expression in the stratigraphic record. Cumulatively, this research enables more informed interpretations and predictions of the nature of sedimentary deposits hypothesized to represent river avulsions observed on Earth and other planetary surfaces.Earth and Planetary Science
Thermodynamics forces present in shaping the free energy landscape of nucleic acids
Get PDFPolynucleotides like DNA and RNA are fascinating molecular systems from both a biological and material science perspective. Biologically they are the keepers and translators of the genetic code, while physically they are highly charged polymers that fold and maintain a three-dimensional shape in aqueous solution with the crucial help of counter ions. These polymers are also basic building blocks for complex constructs in material science. Here we focus on their physical properties and use computational studies to investigate the thermodynamics of conformational changes. We use statistical mechanics tools and atomically detailed modeling of short nucleic acid (NA) strands to investigate the folding and compaction process. Simulations explore the interplay between ions and NAs and provide comprehensive information about folding of highly charged systems relevant to biology and material science. Specifically, we explore the behavior of a model RNA system in two different slat conditions and find that the drive towards a collapsed phase is in part due to the entropic gain afforded by release of water molecules into a bulk solution. We then construct a lattice model that is a simplification of the RNA system but are able to analytically show that within the bounds of the model water release is the dominant force towards the collapsed phase. Finally, we examine the rotational orientation of two DNA helices held in close proximity when modifying the ion atmosphere. We compare results from Poisson-Boltzmann and Molecular Dynamics to experimental FRET signals and find that species ion entropies appear to be critical in shaping the free energy landscape when multiple ionic species are present and must be handled correctly to reconcile the predicted and observed FRET value across the intermediate ~O(10-100mM) concentration range.Chemical Engineerin
Diet and phylogenetics of omomyid primates from the Devil’s Graveyard Formation of Trans-Pecos Texas
Get PDFNear the transition from the Bridgerian to Uintan land mammal ages in North America, a major shift takes place among omomyid primates, with the virtual disappearance of the subfamily Anaptomorphinae, while the Omomyinae become much more diverse and geographically widespread, especially at southern latitudes. It has been hypothesized that dietary diversification and a shift to more fruit dominated diets, opposed to insect dominated diets, was an important factor in the success of omomyines during the Bridgerian-Uintan transition. Here I test the hypothesis of omomyine dietary diversification with a shearing quotient analysis to reconstruct the diet of the omomyines Omomys carteri, Diablomomys dalquesti, and two new species (herein “New Taxon A”, and “New Taxon B” from the Uintan age Devil’s Graveyard Formation of Texas. A phylogenetic analysis was conducted to reveal relationships of the two new species and Diablomomys dalquesti to omomyids. Shearing quotient analysis finds that Omomys carteri was a small-bodied insectivore-frugivore, Diablomomys dalquesti was a slightly larger dedicated frugivore, New Taxon A was moderately sized frugivore-folivore, and New Taxon B was a large dedicated frugivore. Phylogenetic analysis finds at least two major lineages within the Omominyae. One lineage consists of Devil’s Graveyard taxa, an assemblage of omomyines from present day California, and a collection of taxa from the Rocky Mountain Interior. The two new species share a sister relationship, and Diablomomys dalquesti shares a sister relationship with Mytonius hopsoni who altogether make a single clade. This clade of Devil’s Graveyard omomyines plus Mytonius hopsoni share a close relationship with the clade of Ourayia hopsoni, Utahia kayi, Stockia powayensis, and Chipetaia lamporea, and a more distant relationship with Gunnelltarsius, randalli, Brontomomoys cerutti, and Yaquius travisi. The second major omomyine lineage consists of Macrotarsius spp. Rooneyia, viejaensis and tarkadectines. Hemiacodon gracilis, Shoshonius cooperi, Washakius insignis, and Dyseolemur pacificus, form a clade that does not share a close relationship with traditional omomyines, and instead is recovered as sharing a close relationship with microchoerines and tarsiids. The findings here lend support to previous hypotheses of omomyine success through dietary diversification and highlights the multiple lineages and regional endemism of omomyines during the Uintan of North America.Anthropolog
Does residential mobility improve social outcomes? : the experience of neighborhood change, housing demolition, and housing vouchers in Chile
Get PDFThis dissertation analyzes residential mobility trends and outcomes in Chile. In the last decade, there have been new programs that incentivize mobility, but there is little evidence of their effects. Using a life course perspective, I explore how mobility affects those who move and the places they move from, given their individual constraints and preferences, context and institutional setting. Chapter 2 describes the policy context and theoretical frameworks that help understand the current trends, policies and challenges related to residential mobility. Chapter 3 classifies municipalities in the Santiago Metropolitan Region in terms of their residential mobility rates and how they relate to poverty and crime rates. Results suggest that there is only a modest association between residential mobility and these outcomes, and that many municipalities are quite stable in terms of their mobility levels. Chapters 4 and 5 explore the mobility and immobility results of a social housing demolition program. Specifically, Chapter 4 describes the mobility processes and perceptions of movers and stayers. Using mixed methods, the chapter shows that most residents moved close, which was what they expected, apparently contradicting the expectations of some policy makers. Chapter 5 employs a two-way fixed effects analysis to study if residential mobility affected attendance and grades of school-aged children who moved due to the demolition of their apartments. Results suggest that moving is associated with a decrease in average attendance, but the decrease is reduced for students who lived close to their school. Attendance is also associated with grades, and acts as a mediator between moving and grades. Chapter 6 focuses on understanding the elements that predict take-up of a rental voucher program. The results suggest that poor housing conditions act as a barrier for voucher take-up, and that this, together with regional differences and the lack of an affordable housing market, needs to be addressed to improve the outcomes of the program. I conclude (Chapter 7) with a discussion about the policy framing and expectations behind these mobility programs, and on the constraints that appear to be impacting the outcomes, both from the perspective of individuals and policy makers.Public Polic
Towards an investigation framework for lithium-ion battery fire forensics
No full textDetermining the origin and cause of a fire involving lithium-ion batteries is an incredibly challenging task due to the lack of data on the ignition properties of Li-ion batteries. Li-ion batteries have high energy density and when they fail in thermal runaway, they eject high temperature products. The characteristics of these ejected material and their contributions to secondary ignition have not been well characterized, which complicates forensic investigations. Understanding their failure characteristics is crucial for developing battery-fire-forensic tools for investigations. Characterization of battery failures in terms of failure reconstruction/simulation, path to thermal runaway, thermal runaway responses (dynamics, ignition, flame spread, and propagation), and post-failure signatures is presented. Experimental setup and procedures for battery (thermal and electrical) failure reconstruction are discussed. Different sensor systems are implemented in the test apparatus to capture and describe a battery's path to failure and the associated thermal runaway responses. Scientific techniques and methodologies are adopted to analyze batteries in the post-failure conditions. To better guide fire investigators in approaching a fire scene involving Li-ion battery-powered devices, a battery-fire-forensic-investigation framework is proposed. The framework illustrates a systematic and investigative process starting from examining a fire scene to forming hypotheses based on findings. Investigation work such as disassembly and examination of physical evidence and analysis of battery ignition property and root cause are important procedures in an investigation to obtain meaningful findings. Assessing the likelihood of a battery powered device failure igniting adjacent fuel packets requires a crucial cell parameter, which is the cell's state-of-charge. Thus, various methodologies are explored to determine the pre-failure state-of-charge of cells based on their post-failure characteristics. It is shown that for cylindrical 18650 cells that gravimetric techniques (i.e., mass loss) correlate with the pre-failure state-of-charge. Cell teardown and computational tomography also show signatures that correlate with cell state-of-charge. A preliminary battery-fire-forensics technique is proposed using the scanning-electron-microscopy and energy-dispersive-spectroscopy analysis. The technique is mainly exercised on cells with nickel-manganese-cobalt cathode at different states-of-charge. The use and limitations of this technique for finding correlations between the post-failure cell chemical composition and pre-failure state-of-charge among different cylindrical format 18650 Samsung cells are discussed.Mechanical Engineerin
Engineering antibodies for conditional activity at the low tumor microenvironment pH
Get PDFMonoclonal antibodies enjoy clinical and commercial successes for the treatment of various cancers but also often suffer from undesirable side effects due to recognition of the target antigen in healthy tissues. These “on-target, off-tumor” effects have been observed for multiple FDA-approved antibody therapies. Engineering antibodies that preferentially bind antigen at the weakly acidic pH characteristic of the tumor microenvironment could restrict activity to tumor tissues and improve therapeutic indices. Accordingly, we used mammalian cell display to identify human IgG1 Fc variants with pH-selective binding to FcγRIIIa and conditional activation of antibody-dependent cellular cytotoxicity (ADCC). While the wild-type Fc shows minimal pH-selective FcγRIIIa binding, our engineered acid-Fc variant contains three residue changes which reduce FcγRIIIa affinity ~2-fold at pH 7.4 but not at pH 6.5. In vitro ADCC assays with human FcγRIIIa-positive NK92 effector and SKBR3 target cells demonstrated similar ADCC activities for anti-human epidermal growth factor receptor 2 (HER2) antibodies bearing both Fcs at pH 6.5 but nearly 20-fold reduced activity for acid-Fc compared to wild-type Fc at pH 7.4, based on EC₅₀ values. This work shows the promise of mammalian cell display for Fc engineering and the feasibility of pH-selective Fc activation to provide two dimensions of selective tumor cell targeting. We also engineered the anti-HER2 antibody hu4D5 to selectively bind HER2 in the acidic tumor microenvironment. We used the phage display platform, designed a structure-guided histidine-scanning scFv library, and identified scFv variants with the desired pH- dependent binding behavior. The current lead variant RV345 exhibited a 2-fold binding selectivity toward acidic pH based on equilibrium dissociation constants measured by BLI. In vitro experiments confirmed that RV345 could bind strongly to membrane bound HER2 on SKBR3 cells at acidic pH while the binding at neutral pH was reduced. The ability of RV345 to elicit in vitro anti-proliferative effects on human tumor cell lines with varying levels of HER-2-expression is currently under investigation. Future steps of this work include combining the Fc engineering and paratope engineering efforts, as well as determining the alibility of these engineered next generation therapeutics to elicit anti-tumor activity with better toxicity profile in vivo.Chemical Engineerin
Rhinoclemmys areolata (Furrowed Wood Turtle). Copulation.
No full textThis video demonstrates behavior. Most videos in this collection have no audible language and for those that do, the language isn't necessary to understand the behavior. For that reason, transcripts are not provided.Integrative Biolog
Fatigue and diabetes self-management in adults with type 2 diabetes in Taiwan : a structural equation modeling approach
Get PDFAccording to the International Diabetes Federation in 2019, type 2 diabetes mellitus (T2DM) is a global epidemic affecting over 463 million people worldwide. In Taiwan, diabetes is the 5th leading cause of death. To delay the onset of severe complications, this chronic illness requires regular and effective diabetes self-management (DSM). However, fatigue, the most commonly reported symptom in people with T2DM, hinders DSM. This study is guided by the Theory of Unpleasant Symptoms. A cross-sectional, correlational, predictive design was used to describe the relationships among the influencing factors, fatigue, and DSM. The subtypes of fatigue quality were identified by using latent profile analysis. The predictive relationships among the variables were examined using structural equation modeling and mediation analyses. The participants were recruited from two diabetes outpatient departments in Taiwan using convenience sampling. This study used structured questionnaires to collect data. Data were analyzed using SPSS version 24.0 and Mplus version 8.6. Missing data were handled using full information maximum likelihood. An alternative model was tested to lower the risk of confirmation bias. A sample of 150 participants was recruited in the study. On average, the participants reported a mild intensity and disturbance of fatigue and were experiencing fatigue for about 22% of the day and about three days per week. For people who experienced fatigue, the majority reported having worse fatigue in the afternoon and the evening. The latent profile analysis of fatigue quality revealed two distinct classes of fatigue in adults with T2DM. In the “high fatigue” class (11% of the participants), the participants reported high scores across the general, physical, and mental fatigue indicators with a high reduction in activity and a moderate decrease in motivation. The “low fatigue” class (89% of the participants), on the other hand, was characterized by low fatigue scores across all the indicators. For the results of examining the conceptual model of fatigue in adults with T2DM, the measurement model of fatigue and the full structural model fit the data well. Participants who had T2DM for a longer duration, reported less diabetes distress, and had higher sleep quality performed more DSM activities in the past week. Higher fatigue was related to less performance of DSM activities. Fatigue mediated the relationship between depressive symptoms and DSM and the link between sleep quality and DSM. Lastly, the model fit results of the alternative model did not fit as well as the original model that we tested in this study. The establishment of a theoretically and empirically sound framework on fatigue in adults with type 2 diabetes is the first step to understand this phenomenon comprehensively. The knowledge from this study has the potential to further guide the development of a theory-guided fatigue intervention for adults with T2DM that aims to improve the health outcome in this population.Nursin