The doctoral dissertation/master's thesis must be submitted to each member of the doctoral/thesis committee at least four weeks before the final examination/defense. Review the requirements regarding committee participation at the defense found here for doctoral students and here for master's students The Thesis Advisor must be a regular faculty member of the University of California or an Adjunct Faculty member in the Department of Chemistry and Biochemistry. According to UCSD policy, if the Thesis Advisor is an Adjunct Faculty, a regular UCSD faculty must be appointed as Co-Chair. Co-Chairs are normally from our Department UNIVERSITY OF CALIFORNIA SAN DIEGO Topics in Mesoscopic Turbulent Transport A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Physics with a Specialization in Computational Science by Robin A. Heinonen Committee in charge: Professor Patrick H. Diamond, Chair Professor Daniel P. Arovas Professor Stefan G. Llewellyn-Smith Professor George R.
Dissertation & Thesis Submission
To understand ocean health, it is crucial to carefully monitor and analyze marine plankton — the phd thesis ucsd that form the base of the marine food web and are responsible for the uptake of atmospheric carbon. With the recent development of in situ microscopes, that collect images of phd thesis ucsd organisms in vast quantities, the phd thesis ucsd of deep learning methods to taxonomically identify them has come to the forefront.
Given this data, two questions arise: 1 How well do deep learning methods such as Convolutional Neural Networks CNNs identify these marine organisms using data from in situ microscopes? Using images collected by the in situ Scripps Plankton Camera SPC system, phd thesis ucsd, we trained a CNN to recognize 10 species of phytoplankton that are identified as associated with Harmful Algal Blooms HABs.
The success of the CNNs is characterized using standard evaluation metrics. To compare phd thesis ucsd estimates, we fit a linear model between the number of organisms of each species counted in a known volume in the lab with the phd thesis ucsd of organisms collected by the in situ microscope sampling at the same time. The linear fit between lab and in situ counts of several key HAB species suggests in the case of phd thesis ucsd dinoflagellates there is good correspondence between the two methods, phd thesis ucsd.
The linear relationship derived for other organisms that were not as abundant is not as conclusive as well as the failure of the SPC systems to successfully detect the diatom chain, Pseudo-nitzschia. Given the excellent correlation between lab counts and in situ microscope counts on key species, the methodology proposed here provides a way to estimate an equivalent volume in which the employed microscope can identify in focus organisms and obtain reasonably confident estimates of abundance.
Given the ease of collection and success of the method, we are hopeful that future systems can automatically monitor HAB formers and other plankton. This dissertation is comprised of three freestanding chapters, phd thesis ucsd, each of which studies a policy-motivated question related to the economics of aging.
The first two chapters provide new evidence from Denmark on how social security policy impacts retirement, phd thesis ucsd, labor supply, and savings decisions of older workers, and the last chapter evaluates a U. Medicare policy that aims to improve access to healthcare for older Americans.
Chapter 1 studies how the provision of public pension benefits impacts private savings, phd thesis ucsd. We use administrative data and a regression discontinuity design to identify the causal effects of a Danish reform that increased social security eligibility ages. We find no evidence of anticipatory savings responses after the announcement of the reform, whereas we find large increases in savings in retirement accounts when delayed benefit eligibility induces extended employment.
The evidence suggests inertia is a leading mechanism: individuals continue to work and continue to save, and we show how employer default contribution rate policies mediate responses to the national reform, phd thesis ucsd.
Chapter 2 studies how social security influences joint retirement of couples. We first document joint retirement behavior around the early pension eligibility age in Denmark: we show that spouses are discontinuously more likely to retire when their partners first become eligible for social security benefits.
We then explore underlying mechanisms and find age differences within couples to be crucial determinants of joint retirement behavior, which is primarily driven by older spouses continuing to work until their younger partners reach pension eligibility age. Chapter 3 studies a U.
Medicare policy that delivers bonus payments to physicians for practicing in areas with few doctors per capita, phd thesis ucsd. Using several sources of data from the Centers for Medicare and Medicaid Services and a matched difference-in-differences design, we find that counties designated as official shortage areas experience an increase in the number of early-career primary care physicians.
However, we find no evidence that later-career physicians respond to shortage area designations, phd thesis ucsd, and we highlight how targeting bonus payments towards newer physicians may thus improve the effectiveness and cost-efficiency of the policy.
This work is dedicated to characterizing unexplored structural biological materials in both mineralized and non-mineralized systems including the transparent phd thesis ucsd of the deep-sea dragonfish, a comparative study on the piranha and pacu teeth, and the feather rachis of primary flight feathers from birds with various flight styles.
The insights gained are used to better understand how the structure across multiple length scales micro, meso, and macro relates to the optimization of tough, stiff, phd thesis ucsd, lightweight, energy absorbent, phd thesis ucsd, and impact resistant materials.
We propose that these findings can be used to develop bioinspired structural designs for tailorable mechanical performance. The transparent dragonfish teeth phd thesis ucsd found to be composed of nanostructured hydroxyapatite ~20 nm grain size and collagen. They are devoid of microscale features such as microtubules which are typically found in the dentin layer. The nanoscale structure is responsible for the reduced Rayleigh light scattering and the increase in hardness and stiffness in the dentin layer, phd thesis ucsd.
The tip of the tooth is the most transparent to red light nm and least transparent to blue light nm. We suggest phd thesis ucsd the nanostructured design of the transparent teeth enables predatory success as it makes its wide-open mouth armed with teeth effectively disappear against the darkness of the deep-sea.
The relationship between feeding mechanics and structure-property relationships are investigated with the comparison of two closely related species: the piranha carnivorous and the pacu herbivorous.
Typically, phd thesis ucsd morphology and form of the tooth are only used to indicate feeding performance, phd thesis ucsd, ignoring the hierarchical nature and relative tooth position within the jaw. Herein we investigate both types of teeth across multiple length scales and relate the findings to how the tooth performs during feeding.
We suggest that tooth form, enamel thickness, structuring of the dentin-enamel junction, and microstructural characteristics of enamel influences the biomechanics required for each style of feeding.
Tubules are not only found in the dentin layer of teeth but also in horns, hooves, and many other natural energy absorbent materials. However, phd thesis ucsd, the effects of porosity, phd thesis ucsd, radius, or degree of reinforcing mineralization and the synergy with other design motifs suture and gradient structures on the mechanical properties have not been fully explored. We propose to 3D print tubule architectures to parametrically explore the above-mentioned effects in quasi-static compression, fracture toughness, drop tower testing, Hopkinson bar, phd thesis ucsd, and dynamic mechanical analysis and compare them with numerical models.
The mechanics of the feather shaft are explored through 3D printed bioinspired designs to investigate structure-property relationships phd thesis ucsd respect to flight. The feather shaft is the predominantly load bearing component of the feather and is the focus of this work, phd thesis ucsd.
Sandwich structures inspired by the feather shaft are printed with a foam core and without a foam core to investigate the flexural properties. The flexural strength of the sandwich structure increases with the addition of a foam core, due to the increase in the moment of inertia. However, the stiffness remains the same despite having or not having a foam core.
Stiffness is only determined by the cortex since the foam provides negligible stiffness. Schistosomiasis is a neglected tropical disease NTD caused by flatworm parasites belonging to the genus Schistosoma. The disease infects over million people in developing countries where access to clean water is limited. Treatment of schistosomiasis relies on just one drug, praziquantel PZQ.
This drug is only partially effective and resistance is a concern, phd thesis ucsd. Together, these encourage the search for new drugs and new drug targets, phd thesis ucsd. The proteasome is an essential proteolytic enzyme complex in the cell being responsible for protein turnover. It is a validated drug target for treatment of certain cancers and a promising target for a number of parasitic infections, including Schistosoma.
My lab has been using RNA-sequencing RNA-Seq to profile the transcriptomic changes after exposure of Schistosoma mansoni to the proteasome inhibitor, bortezomib BTZ. As part of the aims of my project, I provide an initial characterization of the top gene transcripts that were upregulated after treatment of S.
Among these, I identify and discuss heat phd thesis ucsd proteins and proteasome subunits that were upregulated at both time points, as well as proteins particular to each time point. Next, phd thesis ucsd, using primers that I helped design and then test for efficiency for nine selected genes of interest, I validated the RNA-Seq data via quantitative reverse polymerase chain reaction qPCR. The resulting data and analysis offer an initial insight into the transcriptomic response of the S.
mansoni after exposure to a proteasome inhibitor with the goal of identifying new drug targets. For my Lab project, I wrote and produced an original podcast called PEORIA with Sound Designer Stephen Jensen, phd thesis ucsd. As COVID eliminated the possibility of live performance, and social distancing restrictions pushed artists toward digital and audio platforms at a much quicker pace, I found the training at UCSD to be incredibly beneficial in making that transition.
The voice techniques and storytelling structures I learned during my time here helped me dive into podcasting as a way of alternative theatre making and helped me gain confidence in using the voice as my main instrument. The majority of our training was in the classroom researching how best to embody a character in an alive and three-dimensional way. Through the process of creating an original piece of audio theatre, I was challenged to hone in on the techniques that most served phd thesis ucsd. There was much at my disposal in terms of pitch, volume, pace, and a range of vocal characterizations that helped the audience imagine the person whose voice they were hearing.
This process caused a hyper-specificity to occur in recording sessions. I am incredibly grateful for the time in the studio spent researching how a specific vocal choice landed.
This process helped me gain technical clarity of how to direct the voice toward a desired effect. This thesis covers techniques to improve wildfire detection accuracy through the use of spatial and temporal context.
Our dataset of wildfires consists of high-resolution images with smoke plumes that need to be detected early, when they are smallest, to allow firefighters enough time to react. We propose two novel architectures - the first combines a region proposal network on a lower-resolution image with a sequence network on phd thesis ucsd full-resolution image for efficient, accurate predictions; and the second combines a ResNet feature extractor with a vision transformer for high resolution tiled image classification.
We also propose novel loss functions, combining a precise per-grid-element loss with a coarser per-image loss to achieve better precision in our detected fires without increasing the amount of false positives. Each chapter in this dissertation studies how various aspects of U. health policy affect physician behavior.
The first two chapters study the introduction and effects of new billing codes for primary care services, phd thesis ucsd, and the third chapter studies a program that incentivizes physicians to practice in areas with few physicians. Chapter 1 studies phd thesis ucsd take-up of new billing codes introduced by Medicare to compensate physicians for important and underprovided types of primary care: Transitional Care and Chronic Care.
We identify significant variation in take-up by geography and by physician type. These patterns provide insight into the processes that determine new code take-up rates. We also find take-up patterns by group size and group type that fit with basic economic intuition regarding the investments needed to adopt new billing codes.
Chapter 2 studies the extent to which take-up of billing codes for new primary care services complements with and substitutes for codes for other services. We use a panel regression and a matched county-level difference-in-differences design that phd thesis ucsd high-intensity counties to low-intensity counties. We find evidence that Transitional Care substitutes for traditional post-discharge visits but complements with other forms of basic primary care as well as the provision of recommended care such as vaccinations and mammograms.
We find less evidence that Chronic Care complements with other primary care services, and we find that Chronic Care is associated with a reduction in the provision of Imaging services. Chapter 3 studies the Health Professional Shortage Area program, which increases the reimbursements paid by Medicare to physicians practicing in areas that are deemed to be experiencing a physician shortage.
Using a matched difference-in-differences design, we find that the program has a positive effect on the stock of early-career physicians in designated counties. Furthermore, we find a response only for physicians who attended ranked medical schools. We discuss the policy implications of the fact that later-career physicians do not exhibit a response to the program despite receiving the bonus payments. The interaction of turbulent microscales phd thesis ucsd a plasma can conspire to produce transport on mesoscopic or macroscopic scales, often with extremely important consequences for the system.
In this dissertation, we present research on mesoscopic turbulent transport in plasmas relevant to fusion energy and astrophysics. The research is divided into three projects. First, we study drift-wave turbulence, a paradigm for gradient-driven turbulence in the tokamak, using a novel data-driven method. Deep learning is used to infer, phd thesis ucsd, from direct numerical simulation of the 2-D Hasegawa-Wakatani system, the dependencies of the turbulent fluxes which control the nonlinear dynamics on mesoscales, thus closing phd thesis ucsd simplified 1-D mean-field model, phd thesis ucsd.
Using this approach, we show that the gradient of vorticity drives a nondiffusive particle flux. This nondiffusive flux, which we also recover analytically, modulates the profile in the presence of a quasiperiodic zonal flow. We also show that zonal flow formation is described by a Cahn-Hilliard-type model, both concurring with and expanding upon previous theoretical work.
In the second project, we introduce a new model for turbulence spreading based on turbulence bistability. This model takes the form a reaction-diffusion equation with cubic nonlinearity and nonlinear diffusion. We find that the bistable model remedies certain deficiencies of the popular, unistable Fisher model, for instance predicting far more robust penetration of turbulence into stable regions.
We also find that the model exhibits a threshold for propagation of an initial seed of turbulence, which we liken to an avalanche.
We analytically estimate this threshold using a simple physical argument.
MY FIRST YEAR GRADUATE SCHOOL GRADES! - PhD in Education at UC-San Diego
, time: 15:48UC San Diego Electronic Theses and Dissertations
The Thesis Advisor must be a regular faculty member of the University of California or an Adjunct Faculty member in the Department of Chemistry and Biochemistry. According to UCSD policy, if the Thesis Advisor is an Adjunct Faculty, a regular UCSD faculty must be appointed as Co-Chair. Co-Chairs are normally from our Department blogger.com Apr 26, · UC San Diego Dissertations UCSD dissertations may be found in print, online (or both), and even audio or video recordings. Check the Roger record for that dissertation or thesis to determine location and online availability. Many of the online dissertations will have this in the record:Author: Teri Vogel
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