Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Title: A traffic flow with a bottelneck Author: Adam Kovařík Department: Department of Numerical Mathematics Supervisor: prof. RNDr. Vladimír Janovský, DrSc. Supervisor's e-mail address: janovsky@karlin.mff.cuni.cz Abstract: In this paper we study a microscopic follow-the-leader traffic model on a circu- lar road with a bottleneck. We assume that all drivers are identical and overtaking is not permitted. We sketch a small part of the rich dynamics of the model including Hopf and Neimark-Sacker bifurcations. We introduce so called POM and quasi-POM solutions and an algorithm how to search them. The main goal of this work is to investigate how the optimal velocity model with a bottleneck deals with so called aggressive behavior of dri- vers. The effect of variable reaction time and a combination of both named factors is also tested. Using numerical simulations we'll find out that aggressiveness and faster reactions have positive effect on traffic flow. In the end we discuss models with two bottlenecks and with one extraordinary driver. Keywords: dynamical systems, ODEs, traffic flow, bottleneck, aggressiveness. 1

<p>The initial goal of this report was to implement and compare cosine modulated filter banks. Because of time limitations, focus shifted towards the implementation. Filter banks and multirate systems are important in a vast range of signal processing systems. When implementing a design, there are several considerations to be taken into account. Some examples are word length, number systems and type of components. The filter banks were implemented using a custom made software, especially designed to generate configurable gate level code. The generated code was then synthesized and the results were compared. Some of the results were a bit curious. For example, considerable effort was put into implementing graph multipliers, as these were expected to be smaller and faster than their CSDC (Canonic Signed Digit Code) counterparts. However, with one exception, they turned out to generate larger designs. Another conclusion drawn is that the choice of FPGA is important. There are several things left to investigate, though. For example, a more thorough comparison between CSDC and graph multipliers should be carried out, and other DCT (Discrete Cosine Transform) implementations should be investigated.</p>

This study had three purposes: (1) to identify differential item functioning (DIF) on the PPVT-III (Forms A & B) using a partial correlation method, (2) to find a consistent pattern in items identified as underestimating ability in each ethnic minority group, and (3) to compare findings from an expert judgment method and a partial correlation method. Hispanic, African American, and white subjects for the study were provided by American Guidance Service (AGS) from the standardization sample of the PPVT-III; English language learners (ELL) of Mexican descent were recruited from school districts in Central and South Texas. Content raters were all self-selected volunteers, each had advanced degrees, a career in education, and no special expertise of ELL or ethnic minorities. Two groups of teachers participated as judges for this study. The "expert" group was selected because of their special knowledge of ELL students of Mexican descent. The control group was all regular education teachers with limited exposure to ELL. Using the partial correlation method, DIF was detected within each group comparison. In all cases except with the ELL on form A of the PPVT-III, there were no significant differences in numbers of items found to have significant positive correlations versus significant negative correlations. On form A, the ELL group comparison indicated more items with negative correlation than positive correlation [χ2 (1) = 5.538; p=.019]. Among the items flagged as underestimating ability of the ELL group, no consistent trend could be detected. Also, it was found that none of the expert judges could adequately predict those items that would underestimate ability for the ELL group, despite expertise. Discussion includes possible consequences of item placement and recommendations regarding further research and use of the PPVT-III.

The initial goal of this report was to implement and compare cosine modulated filter banks. Because of time limitations, focus shifted towards the implementation. Filter banks and multirate systems are important in a vast range of signal processing systems. When implementing a design, there are several considerations to be taken into account. Some examples are word length, number systems and type of components. The filter banks were implemented using a custom made software, especially designed to generate configurable gate level code. The generated code was then synthesized and the results were compared. Some of the results were a bit curious. For example, considerable effort was put into implementing graph multipliers, as these were expected to be smaller and faster than their CSDC (Canonic Signed Digit Code) counterparts. However, with one exception, they turned out to generate larger designs. Another conclusion drawn is that the choice of FPGA is important. There are several things left to investigate, though. For example, a more thorough comparison between CSDC and graph multipliers should be carried out, and other DCT (Discrete Cosine Transform) implementations should be investigated.

The United States Department of Homeland Security reported 354, 982 deportation events in 2010. This number has fallen short, though not by much, of the 400,000 deportations per year “goal” cited by DHS. Though many have begun research on the subsequent repercussions of this well oiled deportation regime, not many have asked questions about the effects south of the border. Those questions are the subject of the pilot research study on which this thesis is based. This document is the narration of the findings and occurrences while conducting fieldwork in Jalisco, Mexico, the goal of which, was to inform on the social impacts of deportations from the U.S. to Mexico on three levels, the individual, the familial and the institutional. The particularities of this thesis stem from the perspective taken by the author. Finding the author’s very own return to Mexico as an educated Xicana, an important part of the story she would set out to find about deportees , their families, and the reality they face upon experiencing a deportation event, this thesis is heavily concentrated on the experiences of the author and the narrations of the interviewees. Discovering her own epistemological and methodological postures on social science research while in the field, the author discusses the importance of these shifts to the future of her work and that of social science research. Taking on the pivotal questions on the effects of a social phenomenon , namely deportation, from a sociological perspective was the intention of the author, yet it was those questions and the process of attempting to gain insight on those inquiries that incited questions about the forms of knowledge production, the results and usefulness of social science research as tools for activism and social change and legitimacy of the subaltern voice within the academe. While the author does draw on her own experiences and that of interviewees to discuss the situation lived in Mexico by deportees, the base of much of the analysis also lies in data-driven questions and conclusions. / text

This study had three purposes: (1) to identify differential item functioning (DIF) on the PPVT-III (Forms A & B) using a partial correlation method, (2) to find a consistent pattern in items identified as underestimating ability in each ethnic minority group, and (3) to compare findings from an expert judgment method and a partial correlation method. Hispanic, African American, and white subjects for the study were provided by American Guidance Service (AGS) from the standardization sample of the PPVT-III; English language learners (ELL) of Mexican descent were recruited from school districts in Central and South Texas. Content raters were all self-selected volunteers, each had advanced degrees, a career in education, and no special expertise of ELL or ethnic minorities. Two groups of teachers participated as judges for this study. The "expert" group was selected because of their special knowledge of ELL students of Mexican descent. The control group was all regular education teachers with limited exposure to ELL. Using the partial correlation method, DIF was detected within each group comparison. In all cases except with the ELL on form A of the PPVT-III, there were no significant differences in numbers of items found to have significant positive correlations versus significant negative correlations. On form A, the ELL group comparison indicated more items with negative correlation than positive correlation [χ2 (1) = 5.538; p=.019]. Among the items flagged as underestimating ability of the ELL group, no consistent trend could be detected. Also, it was found that none of the expert judges could adequately predict those items that would underestimate ability for the ELL group, despite expertise. Discussion includes possible consequences of item placement and recommendations regarding further research and use of the PPVT-III.

Standardized testing has been part of the American educational system for decades. Controversy from the beginning has plagued standardized testing, is plaguing testing today, and will continue to be controversial. Given the current federal educational policies supporting increased standardized testing, psychometricians, educators and policy makers must seek ways to ensure that tests are not biased towards one group over another. In measurement theory, if a test item behaves differently for two different groups of examinees, this test item is considered a differential functioning test item (DIF). Differential item functioning, often conceptualized in the context of item response theory (IRT) is a term used to describe test items that may favor one group over another after matched on ability. It is important to determine whether an item is functioning significantly different for one group over another regardless as to why. Hypothesis testing is used to determine statistical significant DIF items; an effect size measure quantifies a statistical significant difference. This study investigated the addition of reporting an effect size measure for differential item functioning of items and tests’ (DFIT) noncompensatory differential item functioning (NCDIF), and reporting empirically observed power. The Mantel-Haenszel (MH) parameter served as the benchmark for developing NCDIF’s effect size measure, for reporting moderate and large differential item functioning in test items. In addition, by modifying NCDIF’s unique method for determining statistical significance, NCDIF will be the first DIF statistic of test items where in addition to reporting an effect size measure, empirical power can also be reported. Furthermore, this study added substantially to the body of literature on effect size by also investigating the behavior of two other DIF measures, Simultaneous Item Bias Test (SIBTEST) and area measure. Finally, this study makes a significant contribution to the body of literature by verifying in a large-scale simulation study, the accuracy of software developed by Roussos, Schnipke, and Pashley (1999) to calculate the true MH parameter. The accuracy of this software had not been previously verified.

Differential item functioning (DIF) occurs when individuals from different groups who have equal levels of a latent trait fail to earn commensurate scores on a testing instrument. Type I error occurs when DIF-detection methods result in unbiased items being excluded from the test while a Type II error occurs when biased items remain on the test after DIF-detection methods have been employed. Both errors create potential issues of injustice amongst examinees and can result in costly and protracted legal action. The purpose of this research was to evaluate two methods for detecting DIF: logistic regression (LR) and Mantel-Haenszel (MH). To accomplish this, meta-analysis was employed to summarize Monte Carlo quantitative studies that used these methods in published and unpublished literature. The criteria employed for comparing these two methods were Type I error rates, the Type I error proportion, which was also the Type I error effect size measure, deviation scores, and power rates. Monte Carlo simulation studies meeting inclusion criteria, with typically 15 Type I error effect sizes per study, were compared to assess how the LR and MH statistical methods function to detect DIF. Studied variables included DIF magnitude, nature of DIF (uniform or non-uniform), number of DIF items, and test length. I found that MH was better at Type I error control while LR was better at controlling Type II error. This study also provides a valuable summary of existing DIF methods and a summary of the types of variables that have been manipulated in DIF simulation studies with LR and MH. Consequently, this meta-analysis can serve as a resource for practitioners to help them choose between LR and MH for DIF detection with regard to Type I and Type II error control, and can provide insight for parameter selection in the design of future Monte Carlo DIF studies.

Faithful DNA replication is essential for the maintenance of genetic information. This complex process consists of 3 steps: initiation, elongation and termination. Although the first two steps are quite well understood in both eukaryotes and prokaryotes, many aspects of the termination of replication remain unclear. Escherichia coli is an ideal organism to study termination of DNA replication. In E. coli, DNA replication starts by bidirectional firing of two replication forks from a unique origin and terminates when those forks collide in the terminus region of the circular chromosome. The terminus region is flanked by specific ter sequences, which ensure that termination of replication occurs within specific boundaries. Due to the circularity of the E. coli chromosome, once the replication is finished the dimers can be formed. To resolve the dimers, the dif sequences are aligned together and two chromosomes are then separated into two daughter cells. Previous members of Prof. Leach laboratory have observed a stimulation of both double-strand break repair (DSBR) and DNA over-replication in the terminus region when DSBR was induced in the lacZ locus, half way between the origin and the terminus. In this work, I propose that these two phenomena, elevated levels of DSBR and DNA over-replication, are linked to each other. I confirm that the DSBs arise from the dif site and that the dif site is the source of DNA over-replication in the terminus. My results suggest that an attempted DSBR at dif leads to over-replication between terA and terB. Here, using next generation sequencing methods, I show that TopoIV and TopoIII topoisomerases introduce breaks in chromosome dimers that were not resolved by the XerCD/dif system, leading to DSBR and DNA over-replication.