Automated measurements of retinal bifurcations

This paper presents an analysis of the bifurcations of retinal vessels. The angles and relative diameters of blood vessels in 230 bifurcations were measured using a new automated procedure, and used to calculate the values of several features with known theoretical properties. The measurements are compared with predictions from theoretical models, and with manual measurements. The automated measurements agree with the theoretical prediction measurements with slightly different bias. The automated method can measure a large number of retinal bifurcations very rapidly, and may be useful in correlating bifurcation geometry with clinical conditions

Reliability vs. Total Quality Cost: part selection criteria based on field data, combined optimal customer and business solution

Most privately owned businesses are formed to generate profits. Every year, manufacturers loose a portion of potential profits on covering warranty claims. To minimize warranty costs companies focus on product quality improvements. In this project real historical warranty data of three electronic sensors have been analyzed. Two-parameter Weibull distribution to measure sensors’ reliability have been used. Monte Carlo simulations have been implemented to calculate Total Quality Costs (TQC). The results show that cost of improved products may have an adverse impact on business profit – the main business objective. It has been demonstrated how reliability and TQC interact with each other and specified optimum business solutions. A new ratio representing combined business and customer objectives was introduced – Quality Cost Ratio (QCR). A new term has been proposed – Excessive Quality Cost (EQC). Improved process of selection parts and materials were proposed

Accurate methods for manually marking retinal vessel widths

This paper compares two manual measurement techniques for measuring retinal vessel segment widths: the kick-points technique and the edge marking technique. An image set of 164 clear, high-resolution segments was used. The kick-points approach uses kick points marked by observers along interpolated cross-sectional intensity profile graphs; the edge marking method allows observers to nominate the edges on a zoomed-up image, and interpolates edge positions. The edgemarking method provides more precise measurements than the kick-points method, but these are subject to more inter-observer variability; we speculate that this result is due to differing observer perceptions of the edge location

A ribbon of twins for extracting vessel boundaries

This paper presents an efficient model for automatic detection and extraction of blood vessels in ocular fundus images. The model is formed using a combination of the concept of ribbon snakes and twin snakes. On each edge, the twin concept is introduced by using two snakes, one inside and one outside the boundary. The ribbon concept integrates the pair of twins on the two vessel edges into a single ribbon. The twins maintain the consistency of the vessel width, particularly on very blurred, thin and noisy vessels. The model exhibits excellent performance in extracting the boundaries of vessels, with improved robustness compared to alternative models in the presence of occlusion, poor contrast or noise. Results are presented which demonstrate the performance of the discussed edge extraction method, and show a significant improvement compared to classical snake formulations

THEORETICAL STUDIES OF DIPOLE-BOUND ANIONS AND SMALL WATER CLUSTERS

Part I of this work deals with dipole-bound anions of moderately and highly polar molecules. High level electronic structure calculations are performed on nitrile, carbonate, and sulfite containing molecules. The results are compared against experimental data obtained from Rydberg electron transfer, photoelectron spectroscopy, and field detachment studies. Explanations to the unusual trends in the electron binding energies of the series of nitrile containing molecules are suggested. Calculation results also help in suggesting an explanation to the interesting dissociative electron attachment observed in ethylene sulfite. Part II of the thesis is devoted to theoretical studies of neutral and anionic water clusters. Neutral water clusters are important in establishing the bridge between a single water molecule and its bulk phase, while still allowing for accurate quantum mechanical calculations. Anionic water clusters on the other hand, are valuable species in the study of electron capture, solvation, and transfer, which are important chemical and biological processes. Here, we focus mainly on the energetic and spectroscopic features of water clusters. Namely, we consider the effects of anharmonicity and high-level electron correlation to the vibrational frequencies and to the binding energies of the (H2O)n, n = 2-6 neutral clusters. We also attempt to assign the vibrational spectrum of the (H2O)7-Arm cluster, which shows unusual complexity and Ar solvation dependence, when compared with smaller clusters

Manual measurement of retinal bifurcation features

This paper introduces a new computerized tool for accurate manual measurement of features of retinal bifurcation geometry, designed for use in investigating correlations between measurement features and clinical conditions. The tool uses user-placed rectangles to measure the vessel width, and lines placed along vessel center lines to measure the angles. An analysis is presented of measurements taken from 435 bifurcations. These are compared with theoretical predictions based on optimality principles presented in the literature. The new tool shows better agreement with the theoretical predictions than a simpler manual method published in the literature, but there remains a significant discrepancy between current theory and measured geometry

TURKEY'S POLICY: TOWARDS THE BALKANS AFTER THE COLD WAR

After the cold war, the civil war broke out in Balkans and intervention ofUSA/NATO ended the war with world public opinion's influence. Turkey was notindifferent to the war in Balkans because of its security and national interest perception. After the war, Turkey had an active foreign policy in security andstability studies and it played a role by sending soldiers to 'peace corps' leagued toprovide consistency in reconstructio

Interlingual Malapropism in a Bilingual Context: Insights from Icheoku and Masquerade

This paper investigates the linguistic defect of malapropism in two Nigerian media comedies, Icheoku and Masquerade. Using mainly qualitative content/textual analysis, the paper demonstrates that malapropism in a second-language bilingual context is a consequence not only of inadequate mastery of the vocabulary in a language (as in a monolingual’s malapropism) but also of interference from the subordinate bilingual’s first language or mother tongue with the target second language (and vice versa). In contrast with the classical pattern where lexical items in the same language are confused, in interlingual malapropism the confusion is between lexical items in two (and possibly more) languages which share some phonological affinity. The artistic element in this linguistic phenomenon as exemplified by the two series is also examined.  Thus, it is demonstrated that malapropism is a (socio-)linguistic problem that is satirized in fictional terms in the two works. The findings here complement and expand the classical notion of malapropism by taking cognisance of the incompetent bilingual in a multilingual setting. Keywords: malapropism, interlingual malapropism, perceptive malapropism, art, parody, Icheoku, Masquerade DOI: 10.7176/JLLL/65-04 Publication date: February 29th 202

Doctor of Philosophy

dissertationMuch has been done to define and characterize the mechanisms that control the fate of multipotent retinal progenitors during eye development, but our understanding of this process is still nascent. The histone methyltransferase complex PRC2 is a key regulator of differentiation during the development of organs such as skin and cortex, but its roles in vertebrate retinogenesis have not been explored. My work focused on investigating the possible involvement of PRC2 in the progression of retinal progenitors from proliferation to differentiation during eye development in Xenopus laevis embryos. In the first chapter, I report the cloning of Xenopus Suz12, and determine its expression pattern during development. Xsuz12 is provided maternally and its expression persists as development progresses, particularly in the developing central nervous system. Comparative analysis of the PRC2 core subunits Xez, Xeed, Xsuz12 and Xrbbp4 suggests that their expression largely overlaps in the nervous system. In the second chapter, I characterize in detail the retinal expression of the PRC2 core subunits, and explore its potential roles during development using a loss of function approach. I show that the transcripts of the PRC2 core subunits are coincidently expressed in retinal progenitors and are downregulated upon retinal differentiation. Surprisingly, I found that the levels of the H3K27me3 mark that is catalyzed by PRC2 greatly increase in terminally differentiated cells. Loss of PRC2 function led to a marked decrease in H3K27me3 in retinal cell types. Blocking the translation of the core subunits Xez or Xsuz12 caused a reduction in eye size, inhibition of differentiation genes and a bias toward generation of late born cell types. ChIP-seq analysis on whole embryos revealed that H3K27me3 transiently and selectively decorates a subset of genes expressed in the eye, some of which are known negative regulators of retinal differentiation. In the third chapter, I characterize the expression pattern of the newly identified binding partner of PRC2, Xjarid2, in the developing nervous system of Xenopus and found that it is particularly expressed in differentiated cells. Preliminary loss of function analysis suggests that Xjarid2 is required for neural differentiation, in agreement with data on PRC2 core subunits. Taken together, my data indicate that the PRC2 complex is an important regulator of retinal neurogenesis in Xenopus and highlights the contribution of histone methylation to the regulation of retinal proliferation and differentiation

Okun's Law amidst Crisis: Analyzing Morocco's Experience during COVID-19

Our study delves into the far-reaching impact of the COVID-19 pandemic on Morocco's economic growth and labor market. Our investigation centers on the examination of Okun's law, to assess the validity of this law in the context of Morocco, we employ both traditional OLS and an M-robust estimator. By comparing estimates before and after incorporating statistical observations associated with the COVID-19 pandemic, we gain valuable insights into how this unprecedented global crisis has affected the country's labor market dynamics, and within a rolling regression framework, we explore the stability (or lack thereof) of Okun's coefficient over time. This dynamic approach allows us to capture the evolving relationship between economic growth and unemployment during different phases of the business cycle. Our research substantiates the validity of Okun's law in the Moroccan context, indicating that the well-established principle continues to hold significance. However, our findings also reveal a noteworthy aspect - the instability of the Okun's coefficient over time in Morocco. This instability suggests that the association between changes in unemployment and economic growth in the country is subject to shifts and fluctuations, likely influenced by various economic and policy factors. One crucial discovery from our study is the identification of asymmetries in the trends and shocks associated with the magnitude of the Okun's coefficient. Specifically, when accounting for the most recent major economic slowdown caused by the COVID-19 pandemic, we observe distinct patterns that deviate from the norm. This insight can provide critical information for policymakers and economists in devising targeted strategies to address unemployment concerns during challenging economic times