Probability modelling and estimation for hourly variation of air pollation concentrations

Foo, Chen-Hui Lisa University microfilms international 1978 해외박사

Probaility modeling and estimatiojn for hourly variation of air pollution concentrations

Foo, Chen Huilisa U. M. I. 1984 국내박사

Probability modeling and estimation for hourly variation of air pollution concentrations

Foo, Chen-Hui UMI 1979 해외석사

Probability modeling and estimation for hourly variation of air pollution concentrations

Foo, Chen-Hui Lisa Stanford University 1980 해외박사

Probability modeling and estimation for hourly vanation of air pollation concentrations

Foo, Chen Hui Lisa University Microfilms International 1984 국내박사

The candidate proto-oncoproteinbcl-3 can enforce cell cycle blockade in ap50-dependent manner by upregulation of the cyclin:CDK inhibitor,p21

Foo, Shi Yin Stanford University 1999 해외박사(DDOD)

The candidate proto-oncogene <italic>bcl-3</italic> was first isolated from translocation breakpoint common to a subset of B cell chronic lymphocytic leukemias (CLLs). Subsequent studies confirmed its identity as an IκB-like protein it preferentially interacts with the p50 homodimer member of the NF-κB family of transcription factors. To date, no definitive gene target for Bcl-3 activity has been identified and its mechanism of oncogenesis remains unsolved. I show that Bcl-3 can function to block the cell cycle, and may thereby rescue the cell from apoptotic signals such as Fas. Rescue from apoptosis is a known mechanism for oncogenesis. The overexpression of Bcl-3 leads to a cell cycle arrest in the G₀/G₁ phase that is dominant to the positive growth effect of a wide array of oncogenes, i.e., <italic>v-abl, k-ras, pbx-e2a</italic> and a transforming mutant of <italic>p50</italic>. In keeping with the previously elucidation functions of Bcl-3, this effect is also dependent on the concomitant presence of p50. Bcl-3 expression leads to an increase in the level of the universal cyclin:cyclin-dependent kinase inhibitor p21, and decreases the kinase activity associated with the cyclin-dependent kinase 4 protein. Bcl-3 upregulates p2l mRNA levels; however, this activation does not appear to be mediated through potential κB binding sites in the promoter of the <italic>p21</italic> gene, suggesting the possibility that the upregulation of p21 message may occur through non-classical sites at loci distant to the p21 promoter, or through indirect mechanisms. Withdrawal from the cell cycle is a frequent event in rescue from apoptosis. We examine the ability of Bcl-3 to protect cells against Fas-mediated apoptosis. The expression of Bcl-3 in p21 knockout fibroblasts leads to an increase in the percentage of cells traversing the cell cycle, suggesting that ablation of Bcl-3's ability to upregulate p21. may lead to a pro-mitogenic signal. Finally, we also examine the expression of Bcl-3 in a number of CLL lines, and show that the dysregulation of Bcl-3 expression is itself a frequent occurrence in most CLLs. These studies provide the first concrete links between a mechanism of action for Bcl-3 and aspects of cell cycle regulation that may underlie dysplastic cell growth.

Silicon carbon(001) gas-source molecular beam epitaxy from methyl silane and silicon hydride: The effects of carbon incorporation and surface segregation on growth kinetics

Foo, Yong-Lim University of Illinois at Urbana-Champaign 2003 해외박사(DDOD)

Si_1−yC_y alloys were grown on Si(001) by gas-source molecular-beam epitaxy (GS-MBE) from Si₂H₆/CH₃SiH₃ mixtures as a function of C concentration y (0 to 2.6 at %) and deposition temperature T_s (500–600°C). High-resolution x-ray diffraction reciprocal lattice maps show that all layers are in tension and fully coherent with their substrates. Film growth rates R decrease with both y and T_s, and the rate of decrease in R as a function of y increases rapidly with T_s. <italic>In-situ</italic> isotopically-tagged D₂ temperature-programmed desorption (TPD) measurements reveal that C segregates to the second-layer during steady-state Si_1−yC_y(001) growth. This, in turn, results in charge-transfer from Si surface dangling bonds to second-layer C atoms, which have a higher electronegativity than Si. From the TPD results, we obtain the coverage &thgr;_Si*(y, T_s) of Si* surface sites with C backbonds as well as H₂ desorption energies E_d from both Si and Si* surface sites. This leads to an increase in the H₂ desorption rate, and hence should yield higher film deposition rates, with increasing y and/or T_s during Si_1−yC_y(001) growth. The effect, however, is more than offset by the decrease in Si₂H₆ reactive sticking probabilities at Si* surface sites. Film growth rates R(T_s, <math> <f> <rm>J<inf>Si<inf>2</inf>H<inf>6</inf></inf>,<hsp sp="0.167">J<inf> CH<inf>3</inf>SiH<inf>3</inf></inf></rm></f> </math>) calculated using a simple transition-state kinetic model, together with measured kinetic parameters, were found to be in good agreement with the experimental data. At higher growth temperature (725 and 750°C), superlattice structures consisting of alternating Si-rich and C-rich sublayers form spontaneously during the gas-source molecular beam epitaxial growth of Si_1−yC_y layers from constant Si₂H₆ and CH₃SiH₃ precursor fluxes. The formation of a self-organized superstructure is due to a complex interaction among competing surface reactions. During growth of the initial Si-rich sublayer, C strongly segregates to the second layer resulting in charge transfer from surface Si atom dangling bonds of to C backbonds. This, in turn, decreases the Si₂H₆ sticking probability and, hence, the sublayer deposition rate. This continues until a critical C coverage is reached allowing the nucleation and growth of a C-rich sublayer until the excess C is depleted. At this point, the self-organized bilayer process repeats itself.

Multi-element probabilistic collocation in high dimensions: Applications to systems biology and physical systems

Foo, Jasmine Y Brown University 2008 해외박사(DDOD)

In this work we develop and apply numerical methods for quantifying parametric uncertainty in mathematical models. In Part I, we introduce the Multi-Element Probabilistic Collocation Method (ME-PCM) and investigate its convergence properties. We prove that as the parameter space mesh is refined, the convergence rate of the solution depends on the quadrature rule of each element only through its degree of exactness. In addition, the L2 error of the tensor product ME-PCM interpolant is examined and an adaptivity algorithm is provided. We test the ME-PCM on Navier-Stokes examples and a stochastic diffusion problem with various random inputs with up to 50 dimensions. The computational cost of the ME-PCM is found to be favorable when compared to the cost of other methods including stochastic Galerkin (ME-gPC), probabilistic collocation (PCM), Monte Carlo (MC) and low discrepancy sequence methods (e.g. quasi-Monte Carlo). We also introduce an extension of the ME-PCM wherein high-dimensional problems are split with an ANOVA-type decomposition into a series of lower-dimensional problems, and the ME-PCM is applied to each subproblem. We perform numerical studies to analyze the efficiency of this method in comparison to other existing methods. We also test the MEPCM-A method for integration of discontinuous functions in 100 to 500 dimensions using the GENZ testing package for high dimensional integration. In Part II we apply stochastic spectral methods to various applications from systems biology and physical systems. In particular, we demonstrate how the ME-PCM may be used to understand parametric sensitivity in cellular signaling networks. We focus specifically two models: a regulatory network model of cell apoptosis and a model of morphogen patterning in the Drosophila embryo. We also apply stochastic Galerkin and collocation methods to quantify the effect of uncertain forces and material properties on three-dimensional riser sections undergoing elastic deformations. Lastly, we apply the MEPCM-A to aid in modeling subsurface contaminant transport through heterogeneous media at the U.S. Department of Energy's Hanford Site in southeastern Washington state.

Catch-22 in humanitarian and development work: Emotional exhaustion, withdrawal, health, and work motives of these workers

Foo, Su Chuen The Pennsylvania State University 2012 해외박사(DDOD)

Humanitarian and development workers often operate in regions plagued by social, political, and economic problems where crisis and disaster characterize the context in which they operate. Working in such demanding contexts can lead to increased emotional exhaustion, which may manifest over time in the form of decreased engagement, withdrawal, and poorer health. However, not all workers who are emotionally exhausted become disengaged and withdraw but may depend on the extent to which they are driven by prosocial motives. Using the Conservation of Resources (COR) model, this study extended research in IO psychology by examining the resource loss pathway stemming from emotional exhaustion to proximal engagement and distal withdrawal and health of humanitarian and development workers. Moreover, this study examined how workers' prosocial motives and extent of contact with beneficiaries can affect this resource loss pathway. Results showed that prosocial workers experienced less withdrawal but poorer health compared to their less prosocial counterparts. The impact of contact with beneficiaries depended on workers' motivation. Among less prosocial workers, contact heightened emotional exhaustion's positive relationship with turnover intentions while among more prosocial workers, contact buffered emotional exhaustion's effect on turnover intentions. Findings from this study expanded the COR model and broadened the sample of IO psychology to include humanitarian and development workers. Moreover, findings can help inform humanitarian organizations on how to better assist their workers to cope with job stress.

Amyloid Diversity, Translation, and the Yeast Prion [PSI+]

Foo, Catherine Kuan-Chi University of California, San Francisco 2011 해외박사(DDOD)

Yeast prions have proved to be an excellent model for learning about the biophysical properties of prions. In particular, the [PSI +] prion has been invaluable for elucidating the structural basis of prion strains and the prion species barrier. The [PSI +] prion itself is an aggregated form of the translation termination factor Sup35. The aggregation of Sup35 into beta-sheet rich amyloid fibers reduces its activity levels, resulting in translational readthrough of stop codons. In this dissertation, I explore the diversity of amyloid structures formed by a chimeric Sup35 protein, and describe my work to investigate the translational effects of the [PSI+] prion. In the first section, I describe my work examining the amyloid structure of a chimeric yeast prion that is able to form two species-specific conformations. These conformations were probed by hydrogen/deuterium exchange and nuclear magnetic resonance, a technique that has been successfully applied to the study of many amyloids. I discovered that these two conformations were radically different: the residues that comprised the "amyloid core" of each conformation was entirely distinct from the other. In addition to emphasizing the diversity of amyloid formation, this result also reveals that amyloid formation in one region of a polypeptide can preclude the formation of amyloid in another amyloidogenic sequence in the same polypeptide. In the second section, I describe an investigation into the translational effects of the yeast prion [PSI+] by using a technique called ribosome profiling. Ribosome profiling takes advantage of next-generation sequencing technologies to deeply sequence the short fragments that are protected by ribosomes. We can examine the differences in translation in [PSI+] and isogenic [psi -] yeast strains to uncover the regulatory effects of this yeast prion.