Efficient controls for finitely convergent sequential algorithms and their applications
Year of Dissertation:
2010
Finding a feasible point that satisfies a set of constraints or a point that optimizes a function subject to a set of constraints is a common task in scientific computing: examples are the linear/convex feasibility/optimization problems. Projection methods have been used widely in solving many such problems of large size much more efficiently than other alternatives. Finitely convergent sequential algorithms are projection methods that sequentially iterate on individual constraints, one at a time, but overall find a feasible point in a finite number of iterations. ART3 is an example using cyclic control in the sense that it repeatedly cycles through the given constraints. The skipping unnecessary checks on constraints that are likely to be satisfied, lead to the new algorithm ART3+, a variant of ART3 whose control is no longer cyclic, but which is still finitely convergent. Experiments in fitting pixel images by blob images show that ART3+ is statistically significantly faster than ART3. Furthermore, a general methodology is proposed for automatic transformation of any finitely convergent sequential algorithm in such a way that (1) finite convergence is retained and (2) the speed of finite convergence is improved. The first property is proved by mathematical theorems, the second is illustrated by applying the algorithms to practical problems. This transformation is applicable, for example, to the finitely convergent modified cyclic subgradient projection algorithm for solving convex feasibility problems.
Protein Kinase C Substrates That Drive Motility of Cancer Cells
Year of Dissertation:
2010
As the intracellular receptor of tumor promoting phorbol esters, protein kinase C (PKC) is functionally linked to carcinogenesis and metastasis. Therefore, it is crucial to identify substrates of PKC in order to understand the mechanisms by which these substrate proteins participate in cancer-related phenotypes such as motile behavior. The work to be described consists of two projects: 1) new PKC substrates that contribute to the motility phenotype of human breast cells, and 2) the role of a known PKC substrate, MARCKS (Myristoylated Alanine-Rich C-Kinase Substrate) in the motility pathway of mouse melanoma cells.
Eastern and Western Concepts in Two Taiwanese Contemporary Works for Clarinet
Year of Dissertation:
2011
In this dissertation, I examine in detail two contemporary clarinet works, Three Fantasias for solo clarinet (2006) by Yu-Hui Chang and All But Not At All for solo clarinet (2001) by Wei-Chieh Jay Lin, through the lens of performance practice. Each work reflects the composers' culture and training, and each combines Western and Eastern musical concepts. Through the use of Western compositional techniques, Chang and Lin exhibit various Chinese musical idioms, including pentatonicism, folk song quotation, traditional Chinese instrumental ornamentations and styles, and even Chinese philosophical ideas. In Three Fantasias, Chang vividly conveys her stories through a fusion of Taiwanese pentatonic folk song elements and the Western whole-tone and major scales. And in All But Not At All, Lin employs a trichordal set in various musical and conceptual dimensions through modeling the "trichordal array" techniques of his teacher Milton Babbitt. Besides theoretical and musical analyses, I include commentary from my interviews with the composers, interpretive suggestions from my own performing experience, and a CD of live performance recordings of these pieces.
THE EFFECTIVENESS OF SAFETY COUNTERMEASURES IN NEW YORK CITY
Year of Dissertation:
2012
The evaluation of the effectiveness of safety countermeasures is very important in urban transportation planning to build safe and livable communities for all residents. Over the last decade, New York City has achieved great reductions in traffic fatalities and crashes by installing safety countermeasures throughout the city. However, the effectiveness of many of the safety countermeasures remains unclear, which is, to a large extent, due to the lack of a rigorous study design and inadequate attention paid to built-environment factors. The objectives of this dissertation are: 1) to develop a safety framework for better understanding and implementing different safety countermeasures; 2) to develop and apply a rigorous study design and methodology in the evaluation of safety countermeasures; 3) to evaluate the safety countermeasures by controlling the effects of the build environment factors on traffic crashes; and 4) to make policy recommendations on the selection and implementation of various safety countermeasures to improve the safety of all road users. A rigorous quasi-experimental design, that is, a before-after analysis with a comparison group, followed by regression models using the Generalized Estimating Equations (GEE) methodology is used to evaluate the effectiveness of safety countermeasures for the safety of various road users, including motorists (e.g., left-turn signal phasing), bicyclists (e.g., bike lanes), and pedestrians (e.g., increasing cycle length, Barnes Dance, split phase timing, signal installation, and high visibility crosswalk). The study shows that: 1) the change of permissive left-turn signal phasing to protected/permissive or protected-only signal phasing does not result in a significant reduction in intersection crashes, and the reduction of left-turn crashes by the protect-only signal phasing is offset by a possible increase in over-taking crashes; 2) the installation of bike lanes does not result in an increase in crashes, despite a likely increase in the number of bicyclists after installation of bike lanes; and 3) the four signal-related countermeasures are found to be more effective in reducing crashes than high visibility crosswalks. Based on the safety framework and the evaluation results, recommendations are proposed for transportation planners and policy makers in the practice of improving traffic safety in large urban area.
Uniqueness Theorems for Some Nonlinear Parabolic Equations
Year of Dissertation:
2012
We study the uniqueness of solutions of the Cauchy problem of two nonlinear parabolic equations in this thesis.
Thermal Regulation of Human Mesenchymal Stem Cell Differentiation toward Bone and Cartilage Lineages
Year of Dissertation:
2013
In USA alone, osteoarthritis affects about 70 million people and over 65 billion dollars are spent each year to treat the disease and related conditions. The late stage of joint repair in arthritis patients usually requires to regenerate both cartilage and bone tissues. Human mesenchymal stem cells (hMSCs) are multipotent. Human MSCs seeded with bioengineered scaffolds, combined with growth factors and/or mechanical stress during osteogenesis and chondrogenesis have been intensively studied. However, despite these efforts, the osteoblasts and chondrocytes differentiated from hMSCs are still not as
Morphological Development and Taxonomy of Cortical Neurons in Mouse Barrel Cortex: The Effect of Sensory Deprivation During the Critical Period
Year of Dissertation:
2013
Neurons are the basic processing units and the fundamental building blocks of the nervous system, and understanding neuronal morphology provides a necessary first step towards comprehending the composition of the cortical microcircuits that perform cognitive computations within the cerebral cortex. Utilizing a histological impregnation technique that labels neurons in their entirety, detailed morphologies of barrel cortical neurons were investigated and the effect of chronic sensory deprivation explored. This research produced a number of key findings: 1) neurons in layer VI of the barrel cortex, which receives inputs from the contralateral facial whiskers, are composed of six geometrically distinct and morphologically heterogeneous populations; 2) chronic sensory deprivation of whisker-related input spanning across early neonatal development can considerably influence neurons' geometric properties, with structural alterations observed in somatic, apical and basilar dendritic features in layer VI of barrel cortex; 3) cortical response to disruption and restoration of sensation, as assessed by quantifying and categorizing dendritic protrusions, is cortex-layer specific and age-dependent, and a key protein regulating the content of extracellular matrix is upregulated following disruption of sensory experience. The main conclusions drawn from this research were that the composition within cerebral cortex is definable yet highly complex, and neurons respond to the ever-updating sensory environment by modifying their morphology and molecular content within the cerebral cortex. Characterizing neuronal elements provides a framework for better understanding of structure-function relationships within neocortical circuits in general, and how the sensory input provides the essential mechanisms for the appropriate development of cerebral cortex, an important prerequisite for proper perceptual functioning.
COLLABORATIVE RANKING AND COLLABORATIVE CLUSTERING
Year of Dissertation:
2013
Ranking and clustering are two important problems in machine learning and have
PATHWAYS TO HIGH-LETHALITY SUICIDE ATTEMPTS
Year of Dissertation:
2012
The purpose of this study was to develop a model of the trajectory to high-lethality suicidal behavior for individuals with Major Depressive Disorder (MDD) and Borderline Personality Disorder (BPD). An increased number of previous suicide attempts, substance use immediately prior to the attempt, and objective planning were proposed to lead directly to an attempt of higher lethality. Meanwhile, aggression and impulsivity were hypothesized to lead indirectly, through their association with past suicidal behavior, to a higher lethality attempt. Path analysis revealed a revised model that applied only to individuals with BPD. In this final model, impulsivity was found to be significantly associated with higher-lethality suicide attempts and the frequency of an individual's past suicidal behavior. Additionally, the traits of impulsivity and aggression were found to be significantly correlated in the multivariate model. Pathways linking alcohol use at the time of the attempt to the lethality of suicidal behavior and aggression to the frequency of an individual's past suicidal behavior were not found to be significant, and no model using the variables of interest in this study could be determined for individuals with MDD. These results are discussed in light of current theories of suicidal behavior and in terms of their implications for clinical practice.
The Affective Uses of Dogs: Pet-Keeping in Nineteenth-Century England and America
Year of Dissertation:
2012
By focusing on the human-dog bond, The Affective Uses of Dogs: Pet-Keeping in Nineteenth-Century England and America studies how gendered subjectivities are formed through the management of the interspecies intimacies. In the course of the nineteenth century, petted animals became, particularly for the middle-classes, deeply important for their affective uses, reflecting a new ethos of "humaneness" that earned the dog a central place in the affective economies of the family. In their relationships with humans, dogs elicited love, terror, and loathing, and the regulation of these powerful interspecies affects produced bourgeois Anglo-American masculinities and femininities and transformed the dynamics of domesticity itself.