VictorJuiz/thesis huggingface dataset:
Calcium absorption in the human distal colon, effect of short chain fatty acids from fiber fermentation

Increased intake of dietary fiber is recommended by health agencies but there is a concern that it may reduce the bioavailability of minerals such as calcium (Ca) due to its ability to bind with minerals. However, it has been hypothesized that Ca is released and short chain fatty acids (SCFA) are produced upon fiber fermentation. The released Ca is absorbed in the distal colon and the absorption is enhanced by SCFA. To determine the amount of Ca potentially absorbed in the colon, Ca released in basal diets or single dairy foods with and without pectin, psyllium or cellulose were tested using an all in vitro method. Compared with the basal diet, pectin did not affect the total Ca release from food matrix but rather shifted the release of Ca from the small intestinal to the colonic conditions. Psyllium and cellulose caused an insignificant release of Ca in the colon. To determine the Ca actually absorbed in the colon with and without SCFA, four rectal infusion studies were done in humans. The serum Ca response was increased particularly in the presence of SCFA in a 3:1 acetate (Ac):propionate (Pr) ratio, indicating colonic absorption of Ca. Ca disappearance in the colon as a measure of Ca absorption showed that Pr was more effective than Ac in enhancing Ca absorption. Ca absorption increased linearly with Ca concentration with and without Ac, or Pr, suggesting a non-saturable diffusion process. Ac and Pr absorption were enhanced by the presence of Ca. A human feeding study using two stable isotopes of Ca e.g. $\sp{42}$Ca and $\sp{44}$Ca showed that Ca absorption occurs in the colon. The presence of pectin caused a reduction in the total Ca absorption but shifted the amount of Ca absorbed from the small intestine to the colon. In summary, the in vitro, rectal infusion and oral feeding studies have shown that Ca is released after fiber fermentation and can be absorbed in the human distal colon. The colonic Ca absorption is enhanced by Ac or Pr, through a non-saturable diffusion process with Pr being more effective than Ac.
Analysis of endogenous immunoglobulin gene rearrangement in the SCID mouse

The critical event in lymphoid development is the assembly of germline variable gene segments forming the variable exon of the antigen receptors. This somatic assembly occurs through a process called V(D)J recombination. Mice with severe combined immune deficiency (SCID) have a profound deficiency in lymphoid development. The scid mutation results in a defect in the ability to repair double strand DNA damage, and consequently affects normal V(D)J rearrangement. Early studies showed that endogenous rearrangements in transformed SCID cell lines exhibited large deletions in the recombined genetic elements. Indeed, the estimated frequency of normal coding joint resolution in SCID cells is $10\sp2$- to $10\sp3$-fold lower than wild type. However, the scid mutation is not absolute as older mice become "leaky", exhibiting serum immunoglobulin (Ig) and/or T cell activity. During the course of my studies, the SCID gene product was identified as the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs); a molecule implicated in ds DNA damage repair, V(D)J recombination and transcription regulation. The goal of my thesis is to acquire greater understanding of the process of V(D)J recombination and its role in B cell development. To achieve this objective, I have examined the extent of assembly of Ig variable genes in non-leaky SCID mice. In Chapter III, I show that DJ scH rearrangements are found at 1-10% the frequency observed in C.B-17 whole bone marrow. Qualitative analysis of these joins demonstrated that these junctions are indistinguishable from wild type with respect to the number of deletions. Collectively however, the SCID joins exhibited a profoundly restricted repertoire characterized by a general absence of N addition and an increase in homology mediated joining. Chapter IV provides a detailed analysis of the extent to which VDJ scH and $\kappa$ rearrangements are found in SCID B lineage. I show that SCID mice undergo normal VDJH and kappa rearrangement at an appreciable frequency (0.1-1%), and many of these rearrangements are functional (86%, 44% respectively). About 40% of the rearrangements could have arisen by homology mediated ligation, suggesting that homology is used in the resolution of coding ends in the absence of functional SCID protein. Despite the relatively high level of Ig gene rearrangement, SCID mice do not have detectable pre-B cells. Moreover, SCID mice transgenic for either fully rearranged heavy and light chain Ig do not exhibit increased leakiness. My data provides evidence which suggests that the scid defect has a profound and lasting effect on B cell development beyond deficiencies in V(D)J recombination.
Essays on executive compensation and managerial incentives

The first chapter of this dissertation examines the regulatory impact of executive compensation disclosure on managerial pay schemes. Analysing a three-level agency model among the shareholders, directors, and manager of a film, this chapter shows that before disclosure, the directors may underinvest in monitoring the manager's activities because of asymmetric information on the performance of the directors and a divergence of interests between them and other shareholders. Compensation disclosure rules mitigate this inefficiency and increase the pay-performance linkage. Empirically, this chapter examines the impact of compensation disclosure by comparing the sensitivity of CEO pay to firm performance, before and after the new Ontario disclosure regulation (1993), between groups of firms that were differentially affected by the legislation. It is found that after introducing the Ontario regulation, the pay-performance sensitivity increased much more in the firms that were affected by the regulation than in those that were unaffected by the regulation. In contrast to previous studies, these findings suggest that disclosure of executive compensation strengthens the pay-performance relationship. The second chapter provides the first systematic examination of the relationship between CEO compensation, firm size, and corporate performance for Canadian firms. Consistent with previous studies, this chapter finds that CEO pay rises with firm size and that compensation is tied to company performance. Some novel findings are also documented. First, options and stock ownership tend to play a relatively more important role for CEO incentives in small firms. And second, while CEO turnover probability is generally negatively related to the firm's stock performance, the threat of dismissal is less pronounced in small firms. The third chapter compares executive pay-performance sensitivities between Canadian firms and US firms. Examining the data for 365 Canadian firms and 678 US firms over the years 1991-1994, it is found that the pay-performance sensitivity associated with direct pay and stock ownership is smaller in Canadian firms than in US firms but that the difference diminishes as firm size increases. This finding, together with poorer corporate performance and lower CEO pay of Canadian firms, is consistent with the hypothesis that managerial incentives affect firm performance.
Clonality in field populations of Sclerotinia sclerotiorum

Given a predominantly clonal structure in populations of Sclerotinia sclerotiorum (Lib.) deBary, these studies have focused on the changes in clone frequencies during the disease cycle and the spatial distribution of clones on several scales, from the micro-geographical scale of a field population to the macro-geographical scale of a world-wide sample. Four western Canadian field populations of canola (oilseed rape; Brassica napus L. and B. rapa L.) were sampled in grids to test for the changes in clone frequencies, by chi-square tests, and for the spatial distribution of clones, by randomization tests, during the disease cycle of sclerotinia stem rot. Among 2747 isolates collected from two critical phases of the disease cycle, 594 unique genotypes were identified by DNA fingerprinting. Three attributes of S. sclerotiorum populations on Canadian canola were established: (i) there is essentially one population of S. sclerotiorum on canola across Canada with some local subdivision, (ii) significant changes in clone frequencies were observed during the disease cycle, consistent with selection, and (iii) every crop sampled was infested or infected by many clones and spatially, these clones were randomly distributed, suggesting spatial mixing of ascospore inoculum from resident or immigrant sources. The extent of clonality in S. sclerotiorum populations from Canadian canola and North Carolina cabbage was determined in tests for random association among multiple loci identified in DNA fingerprints. In tests of linkage disequilibrium, more than 40% of pairs of fingerprint fragments were in random association, suggesting that some genetic exchange and recombination, and not mutation alone, may be a source of new genotypes of S. sclerotiorum. Analysis of mitochondrial DNA (mtDNA) haplotypes of a world-wide sample of S. sclerotiorum from agricultural and wild hosts showed that while wild populations shared no haplotypes with agricultural populations, some mtDNA haplotypes were shared among agricultural populations, suggesting a common origin of these haplotypes. In agricultural populations the association of mtDNA haplotypes to clones was not one-to-one. While some clones had one mtDNA haplotype indicating association with the DNA fingerprint, some clones had more than one mtDNA haplotype and some groups of clones shared mtDNA haplotypes.
Patterns of eye movements during visual search

In Experiments 1 and 2, eye movements were monitored while participants performed parallel and serial search tasks. In Experiment 1, participants searched for an "O" among "X"s (parallel condition) and for a "T" among "L"s (serial condition). In the parallel condition of Experiment 2, "$\rm O\!\!\!\sb\vert$" was the target and "O"s were distractors; in the serial condition, these stimuli switched roles. Displays contained 1, 12, or 24 stimuli, with both target-present and target-absent trials. RT and eye-movement measures (number of fixations and error and latency of the first saccade) indicated that search efficiency was greatest in the parallel conditions, followed by the serial condition of Experiment 1 and, finally, by the serial condition of Experiment 2. In Experiment 3, participants' eye movements were monitored during the performance of two triple conjunction search tasks. Stimuli were created by combining values on 3 stimulus dimensions: colour (red vs. blue), shape ("E" vs. "F"), and orientation (vertical vs. horizontal). In the low-similarity (LS) condition, the target stimulus shared one feature with each of 3 types of distractor stimulus, while in the high-similarity (HS) condition, it shared 2 features with each of 3 types of distractor. Stimulus displays consisted of 6, 12, or 24 stimuli. On half of the trials, the target was present, while on the other half, it was absent. The analysis of RT and eye-movement measures (number of fixations and error and latency of the first and second saccades) suggested that search was serial in both conditions but was more efficient in the LS condition. In addition, an examination of saccadic endpoints revealed that participants were more likely to fixate on distractor stimuli sharing colour (LS condition) or colour and shape (HS condition) with the target. The results of the present experiments suggest that eye movements are correlated with the attentional processes underlying visual search. Thus, studying patterns of eye movements permits a more fine-grained analysis of the search process than do global measures such as response time.
Closed model categories and monoidal categories

In this thesis we explore some uncharted areas of the theory of closed model categories and monoidal categories. We give conditions under which a set of maps, in any category, determine a closed model structure. We then observe that if such a category is monoidal its monoidal objects also often can be given the structure of a closed model category. Next we look at how we can define chains on our model categories. In the last chapter the theory that has been built up is applied to stable homotopy theory. We demonstrate an equivalence of categories between differential graded algebras over a commutative ring R and algebras over the Eilenberg-Mac Lane spectrum KR. In future work we will apply the theory to many other situations.
Mechanics of mixed-mode fatigue behaviour of cold worked adjacent holes

Fatigue failure of aircraft structures almost invariably begins at the root of geometrical discontinuities. The designer is frequently required to predict the fatigue behaviour of cracks emanating from these discontinuities so as to assess the residual life and to avoid catastrophic failure. However, the problem is complicated by the fact that these critical load bearing structures contain residual stresses and interacting stress concentration features such as holes, inhomogeneities and inclusions. It is with this in mind that the current research program was undertaken. Four aspects of the work were accordingly examined. The first was concerned with the development of an analytical model capable of predicting the stress state in a solid containing a number of interacting (adjacent) holes. In this case, a new method for treating arbitrarily shaped holes is developed. The theoretical formulation is based upon the superposition of single dislocation solutions, which reduce the original interaction problem into the solution of singular integral equations in terms of dislocation density functions. The second was concerned with the evaluation of residual stresses due to cold expansion of adjacent holes. In this case, a comprehensive elasto-plastic three-dimensional finite element analysis was conducted and the residual stress field was obtained through the thickness of the workpiece. The third was concerned with the prediction of mixed mode fatigue crack growth in the presence of residual stresses. In this case, effective stress intensity factors solutions for generalized cracks emanating from holes, using a newly developed method, were used in conjunction with the appropriate crack tracking criterion to determine the potential incremental crack growth experienced by the component under fatigue loading conditions. The fourth was concerned with the verification of the above modelling techniques as well as the determination of fatigue crack growth data for Al-Zn 7075 in the presence of residual stresses. The results reveal the importance of the location and the magnitude of the stress concentration upon the fatigue life of adjacent holes. In addition, they indicate that mixed mode fatigue crack growth in the presence of residual stresses can be reliably predicted using a newly developed model.
Rivalry and alliance, Chinese trade unions and state power in the twentieth century, with special attention to Qingdao and Shanghai

This study focuses on one aspect of China's labor movement--the relationship between trade unions as a societal force and state power as a political force in the pre-1949 and post-Mao reform years, illustrating that this relationship was characterized by alliance and rivalry and that unions, instead of being tools in the hands of political parties, represented the basic interests of workers and therefore demonstrated a considerable popular character. Chinese trade unions have been closely connected to state and other political forces. These forces needed workers' support in consolidating or striving for state power and therefore regarded it imperative to become involved in labor mobilization, particularly in organizing trade unions. Their involvement partly accounted for the proliferation of various labor organizations, including "signboard" and "yellow" as well as "red" unions, in the pre-1949 years. Such involvement also helped to shape unions' character and functions and gave them certain political orientations. However, political authorities or parties, whether warlord or GMD or CCP, were not able to transform unions into pure instruments of partisan struggles, due to contradictions, competition, or mutual check among these political forces. Competition also existed between different factions within a certain regime, such as the struggle between the city party branch and city government within the GMD. The political parties' aspiration for overriding their rivals compelled them to cultivate confidence of workers as a social group and, for this purpose, they had to show consideration for labor problems and interests, which in turn made it possible for unions to maintain some popular character and a certain degree of autonomy no matter whatever their political orientations. On the other hand, workers seem not so passive as to be easily manipulated by politicians. Having a keen sense of their own distinct interests (primarily economic), they would chose to support only those political parties that offered them the most and join and defend unions that best represented them. The restraints on the power of political authorities or forces and the ability of laborers to make choice and the possibility for them to do so determined that the union-state relationship could be a partnership or alliance. While political forces including state had to use trade unions as an ally, they also regarded the latter as a rival and a potential challenge to their efforts to monopolize and consolidate power. Therefore, every dominant political party or state power-holder attempted to harness trade unions and limit the scope of their activities.
Eating cities, the politics of everyday life in Kampala, Uganda

The central argument of this thesis is that while the approach to the study of both politics of stabilization and adjustment and the Third World has added significantly to our understanding of the nature of political systems and political cultures, it remains incomplete because the focus of most of the studies is not on the micro-level, or the level at which ordinary people struggle for survival and economic benefit. As a result, an important element in our understanding of the politics of adjustment remains obscure: the politics of everyday life. I would argue that the failure of urban adjustment in Kampala is a direct result of the vitality of the politics of everyday life and the failure of institutional reform measures adequately to address the logic of this form of politics. The politics of everyday life confronts top-down attempts at institutional reform, undermines them, and incorporates them in a fashion which conforms to its own imperatives. I explore these issues by looking at the case of market vendors in Kampala, Uganda as they struggle to improve the physical and administrative conditions within their market. The canvas upon which these struggles over space and services emerge include increasing urban poverty and insecurity in Kampala, intergovernmental jurisdictional squabbles between the Kampala City Council and the central government, and the World Bank sponsored Uganda First Urban Project. These everyday political struggles show how the urban poor undermine and resist attempts to impose restrictive regulatory frameworks upon those who cannot afford them.
Genetic variability of an uridine-diphosphoglucuronosyltransferase, UGT2B7

Reports of genetically based variations in drug glucuronidation have essentially focused on their relation to Gilbert's Syndrome and Crigler-Najjar type I and II syndromes, which have been linked to abnormalities in the UGT1 gene complex. To date, information about the genetic variability of other UGT isozymes has been limited. Oxazepam is one of a number of C-3 hydroxylated benzodiazepines for which glucuronide conjugation is the predominant pathway of biotransformation. The drug is normally formulated as a racemic mixture of inactive (R), and active (S), enantiomers. 1. Inhibition studies suggested that the two diastereomeric glucuronidations are catalysed by different UGT isozymes. The inhibition profile of (S)oxazepam glucuronidation suggests that UGT2B7 is the catalysing enzyme. 2. (a) In vivo, the (S) glucuronide was preferentially formed and excreted in nine of eleven subjects. The ratios of (S) to (R) glucuronide metabolites (S/R ratios) were 3.87 $\pm$ 0.79 (mean $\pm$ s.d.) and 3.52 $\pm$ 0.60 in urine and plasma, respectively. However, both ratios were significantly lower in two subjects (p $<$ 0.01). In these two atypical subjects, the half-life of (R,S) oxazepam was also markedly longer (14.7 and 15.9 h) than in the other subjects (8.1 $\pm$ 3.2 h). In 66 additional subjects, the S/R glucuronide ratio was found to be bimodally distributed, with $\sim$10% of all subjects possessing ratios below an apparent antimode of 2.0. (b) In vitro formation of oxazepam glucuronides by microsomes from four of 37 Caucasian livers were characterized by low S/R glucuronide ratios, and abnormally high K$\rm\sb{m}$ values for the formation of the (S) glucuronide, but not of the (R) glucuronide. 3. (a) First-strand cDNA was synthesized from the mRNA of each liver by reverse-transcription. RFLV analyses and nucleotide sequencing showed that three of the four atypical livers were positive for a point mutation at position 802 (T for C) of the UGT2B7 cDNA coding region. The mutation results in the substitution of histidine for tyrosine at residue 268 of the UGT2B7 enzyme. The three individuals were heterozygous for the mutation. Full-length sequence analysis for the fourth atypical liver, showed no deviations from the wild type sequence of UGT2B7. (b) Expression studies in COS-1 cells showed that the V$\rm\sb{max}$ of glucuronidation of (S)oxazepam was greatly diminished with the variant form of UGT2B7. Glucuronidation efficiencies of estriol and 2-OH-estriol were also significantly reduced, whereas the glucuronidation of ketoprofen, (S)naproxen, and hyodeoxycholic acid were unaffected.
Optimizing incremental view maintenance expressions in relational databases

In the last few years, there has been significant interest in the design of incremental methods to improve the performance of view maintenance. Despite that, very little analysis or experimentation supports the predominant view that incremental methods are more efficient than their non-incremental counterparts. We argue that the performance of incremental view maintenance depends on system aspects of the database, such as the availability of indices, the sizes of the relations involved, and the sizes of the database updates. We also argue that the database query optimizer is a reasonable component of the database system to decide, at the time of view maintenance, whether a view is to be maintained incrementally or not, because the query optimizer has knowledge of, and access to, all of the parameters that may affect this choice. To support this argument, we have built the RHODES database query optimizer that supports change propagation and view maintenance for relational queries. In addition to traditional optimizations, RHODES is also responsible for the generation of the queries to be executed in order to support view maintenance. As there may be many different ways to maintain a view incrementally, the choice of which one to use may affect the performance of incremental view maintenance. Moreover, different maintenance queries are amenable to different optimizations. In this thesis, we present a repertoire of maintenance-specific optimizations, especially in the presence of key constraints and foreign key references. The underlying data model we use is relational algebra with multiset semantics. Experimental validation of the above claims has been conducted using the TPC-D benchmark database on the DB2 Parallel Edition.