Effective-Mass Klein-Gordon-Yukawa Problem for Bound and Scattering States

Bound and scattering state solutions of the effective-mass Klein-Gordon equation are obtained for the Yukawa potential with any angular momentum $\ell$. Energy eigenvalues, normalized wave functions and scattering phase shifts are calculated as well as for the constant mass case. Bound state solutions of the Coulomb potential are also studied as a limiting case. Analytical and numerical results are compared with the ones obtained before.Comment: 13 pages, 1 figur

C. Elegans Metabolic Gene Regulatory Networks: A Dissertation

In multicellular organisms, determining when and where genes will be expressed is critical for their development and physiology. Transcription factors (TFs) are major specifiers of differential gene expression. By establishing physical contacts with the regulatory elements of their target genes, TFs often determine whether the target genes will be expressed or not. These physical and/or regulatory TF-DNA interactions can be modeled into gene regulatory networks (GRNs), which provide a systems-level view of differential gene expression. Thus far, much of the GRN delineation efforts focused on metazoan development, whereas the organization of GRNs that pertain to systems physiology remains mostly unexplored. My work has focused on delineating the first gene regulatory network of the nematode Caenorhabditis elegans metabolic genes, and investigating how this network relates to the energy homeostasis of the nematode. The resulting metabolic GRN consists of ~70 metabolic genes, 100 TFs and more than 500 protein–DNA interactions. It also includes novel protein-protein interactions involving the metabolic transcriptional cofactor MDT-15 and several TFs that occur in the metabolic GRN. On a global level, we found that the metabolic GRN is enriched for nuclear hormone receptors (NHRs). NHRs form a special class of TFs that can interact with diffusible biomolecules and are well-known regulators of lipid metabolism in other organisms, including humans. Interestingly, NHRs comprise the largest family of TFs in nematodes; the C. elegans genome encodes 284 NHRs, most of which are uncharacterized. In our study, we show that the C. elegans NHRs that we retrieved in the metabolic GRN organize into network modules, and that most of these NHRs function to maintain lipid homeostasis in the nematode. Network modularity has been proposed to facilitate rapid and robust changes in gene expression. Our results suggest that the C. elegans metabolic GRN may have evolved by combining NHR family expansion with the specific modular wiring of NHRs to enable the rapid adaptation of the animal to different environmental cues

Variations on Hammersley's interacting particle process

The longest increasing subsequence problem for permutations has been studied extensively in the last fifty years. The interpretation of the longest increasing subsequence as the longest 21-avoiding subsequence in the context of permutation patterns leads to many interesting research directions. We introduce and study the statistical properties of Hammersleytype interacting particle processes related to these generalizations and explore the finer structures of their distributions. We also propose three different interacting particle systems in the plane analogous to the Hammersley process in one dimension and obtain estimates for the asymptotic orders of the mean and variance of the number of particles in the systems.Comment: 6 pages, 6 figures, accepted for publication in Discrete Mathematics Letter

On the Low-Frequency Behavior of Vector Potential Integral Equations for Perfect Electrically Conducting Scatterers

Low-frequency behavior of vector potential integral equations (VPIEs) for perfect electrically conducting scatterers is investigated. Two equation sets are considered: The first set (VPIE-1) enforces the tangential component of the vector potential on the scatterer surface to be zero and uses the fundamental field relation on its normal component. The second set (VPIE-2) uses the same condition as VPIE-1 for the tangential component of the vector potential but enforces its divergence to be zero. In both sets, unknowns are the electric current and the normal component of the vector potential on the scatterer surface and are expanded using Rao-Wilton-Glisson (RWG) and pulse basis functions, respectively. To achieve a conforming discretization, RWG, scalar Buffa-Christiansen, and pulse testing functions are used. Theoretical and numerical analyses of the resulting matrix systems show that the electric current obtained by solving VPIE-1 has the wrong frequency scaling and is inaccurate at low frequencies

Pooled Analysis of Resistance Patterns of Escherichia coli Strains Isolated From Urine Cultures in Turkey: Comparison of 1997–2001 and 2002–2007 Periods

WOS: 00026328780028

Mixed discretization of the time-domain MFIE at low frequencies

Solution of the magnetic field integral equation, which is obtained by the classical marching-on-in-time (MOT) scheme, becomes inaccurate when the time-step is large, i.e., under low-frequency excitation. It is shown here that the inaccuracy stems from the classical MOT scheme's failure to predict the correct scaling of the current's Helmholtz components for large time-steps. A recently proposed mixed discretization strategy is used to alleviate the inaccuracy problem by restoring the correct scaling of the current's Helmholtz components under low-frequency excitation

Scattering of Woods-Saxon Potential in Schrodinger Equation

The scattering solutions of the one-dimensional Schrodinger equation for the Woods-Saxon potential are obtained within the position-dependent mass formalism. The wave functions, transmission and reflection coefficients are calculated in terms of Heun's function. These results are also studied for the constant mass case in detail.Comment: 14 page

Graphic Health Warnings and Plain Packaging in the Philippines: Results of Online and Household Surveys

In line with Article 11 of the WHO Framework Convention on Tobacco Control, the Philippines has implemented graphic health warnings on cigarette packs. To date, there has been no published literature evaluating the perceived effectiveness of GHWs in the Philippines. This study aims to contribute to the evidence on the perceived effects of graphic health warnings (GHWs) in cigarette packaging and the potential impact of plain packaging in the Philippines. The study involved an online convenience survey and a nationwide household survey. Mock-up sets of cigarette packs based on the Philippines’ law on GHWs, and Thailand’s and Singapore’s plain packaging were shown to respondents to rate their attractiveness, quality, taste, cost, social appeal, appeal to youth, noticeability, appeal to non-smokers, attempt to quit, ease of quitting, discouraging smoking, and perceived harm to health on a five-point Lickert scale. The online and household surveys recruited 2,701 respondents in total. Online and household survey respondents considered plain packaging with larger graphic health warnings and visible quitlines from Thailand and Singapore to be more effective in discouraging them from smoking. Both sets of survey respondents also found mock-ups from Thailand and Singapore more motivating for them to attempt quitting than cigarette pack mock-ups from the Philippines. The study concludes that current graphic health warnings in the Philippines are ineffective in instilling health consciousness among Filipinos. Policymakers should consider larger graphic health warnings and plain packaging of cigarettes to motivate smokers to quit and discourage Filipinos from smoking