VictorJuiz/thesis huggingface dataset:
Insect community patterns in space: Statistical tools, simulations, and empirical data from southern Ontario coldwater springs

The purpose of this Ph.D. project was to explore spatial patterns of the species composition of insect communities theoretically using simulations as well as empirically based on an extensive field study. Additionally, the performance of current statistical tools for the analysis of multivariate spatially structured data is reviewed and suggestions for their improvement are made. The thesis is presented in three parts: In part 1, empirical data from a 3-year field study of the insect communities in 30 coldwater springs in Southern Ontario, Canada, are presented. Using bi-monthly emergence sampling, a total of 86 insect species was collected from 9 taxonomic groups. A large fraction (55%) of these species had a low frequency and/or low abundances, and the emergence record of any given study year contained on average only about 50% of the total number of species recorded, possibly suggesting a high turnover in the species composition of the local insect communities. Canonical Correspondence Analysis (CCA) indicated that among an extensive set of environmental factors water temperature and discharge were most strongly correlated with community similarity. At the same time, the data showed a 'neighborhood effect' in that spatially adjacent sites frequently had highly similar insect communities even though sites had been selected as to maximize small-scale environmental heterogeneity. This suggests that other factors, such as meta-community dynamics, might play a decisive role in shaping the species composition in coldwater spring habitats. Part II describes the architecture and implementation of the ' inter-site' simulator, a Discrete Event Simulation environment for the simulation of spatially realistic population and community dynamics written in Python, a high-level, object-oriented scripting language. A practical application of the simulator to analyzing metapopulation persistence in patchy irregular landscapes is presented and the benefits of using Python as the computer language for implementing a simulation environment are discussed. Part III is concerned with the description and refinement of statistical methods for the analysis of patterns of species distribution in space. First, PyDAS, the Python Data Analysis Servant, is introduced, a computer package that provides an extensible environment for the statistical analysis of spatially structured multivariate data. Then, two groups of methods commonly used for analyzing multivariate spatial data, Mantel-type permutation tests and spatially constrained ordinations, are introduced in detail and then evaluated using artificial data generated with the 'inter-site' simulator presented in part II as well as the empirical data presented in part I. Several suggestions for improvements for both methods are made. Finally, the effects of range restrictions and of long-term meta-community dynamics on local community similarity are explored in and Epilog, again using data generated with the 'inter-site' simulator.
Immunobiologic prognostic factors in aggressive non-Hodgkin's lymphoma: The role of proliferative index, host-immune response, and continuous lactate dehydrogenase level in predicting survival in 148 consecutive subjects

The prognostic value, with regard to survival, of proliferative index (% cells staining for Ki-67), host T-cell response (% cells staining for CD-4) in B-cell disease, and serum lactate dehydrogenase level (LDH, as a continuous variable), alone and in conjunction with the International Prognostic Index (IPI), was assessed in 148 consecutive subjects with aggressive (International Working Formulation subtypes F, G and H) non-Hodgkin's lymphoma (NHL). Cox proportional hazards regression demonstrated that continuous LDH was a useful prognostic factor in univariate analysis (relative risk of death 1.4, 'P' = 0.001), and modestly enhanced the prognostic value of the IPI on multivariate analysis (likelihood ratio test 'P' = 0.02). Neither Ki-67 nor CD-4 infiltrate provided prognostic information. Receiver operator characteristics (ROC) curve analysis demonstrated no better than poor to moderate discriminative ability in predicting death for the models generated. The reproducbility of the Ki-67 measure used was found to be questionable on reliability testing.
The behavioural genetics of olfactory associative learning in Caenorhabditis elegans

The nematode 'Caenorhabditis elegans' was studied as a model system for defining the molecular processes of associative learning and memory. Using an olfactory associative learning paradigm, in which wild type worms learn to avoid a previously attractive diacetyl odour after it has been paired with an aversive acetic acid solution, it is shown that the ' C. elegans' learning mutants, 'lrn-1' and ' lrn-2', are impaired in associative learning using a conditioned olfactory cue. Non-associative learning using this same olfactory cue is unaffected. ' lrn-1' and 'lrn-2', were first described as impaired in taste associative learning. The deficit in taste and olfactory associative learning suggests that associative learning in different sensory modalities converges on a common genetic pathway in 'C. elegans' that involves 'lrn-1' and 'lrn-2'. The role of glutamate neurotransmission in olfactory learning was also investigated in ' C. elegans'. Worms with a null mutation in 'glr-1', which encodes a putative AMPA type glutamate receptor, are impaired in olfactory associative and non-associative learning. Thus, associative and non-associative learning share some common molecular processes including GLR-1 neurotransmission. The data provide a behavioural characterization of three genes which play a role in 'C. elegans' learning and memory. However, ' lrn-1' and 'lrn-2', have not been mapped. ' lrn-1' and 'lrn-2', have no visible phenotype and can only be detected through behavioural analysis. Mapping these genes requires the ability to distinguish learning mutants from wild type worms with a high degree of reliability. A series of double blind experiments determined that the olfactory learning assay has low predictive power; thus limiting gene mapping with this assay. 'lrn-2', was tentatively mapped to chromosome II using the sequence-tagged site mapping strategy. However, the low predictive power of the assay does not allow any further information to be gathered about novel genes involved in 'C. elegans' learning and memory. The thesis concludes by suggesting ways in which the olfactory associative learning assay can be improved so that it will be possible to resolve the complete cellular and biochemical picture of associative learning and memory in an individual organism.
Analytical investigation of curved steel girder behaviour

Horizontally curved bridges meet an increasing demand for complex highway geometries in congested urban areas. A popular type of curved bridge consists of steel I-girders interconnected by cross-frames and a composite concrete deck slab. Prior to hardening of the concrete deck each I-girder is susceptible to a lateral torsional buckling-type failure. Unlike a straight I-girder, a curved I-girder resists major components of stress resulting from strong axis bending, weak axis bending and warping. The combination of these stresses reduce the available strength of a curved girder versus that of an equivalent straight girder. Experiments demonstrating the ultimate strength characteristics of curved girders are few in number. Of the available experimental research, few studies have used full scale-tests and boundary conditions indicative of those found in an actual bridge structure. Unlike straight girders, curved girders are characterized by nonlinear out-of-plane deformations which, depending upon the magnitude of curvature, may occur at very low load levels. Because of the inherent nonlinear behaviour, some have questioned the application of the term lateral torsional buckling to curved girders; rather curved girders behave in a manner consistent with a deflection-amplification problem. Even with the advent of sophisticated analytical techniques, there is a glaring void in the documented literature regarding calibration of these techniques with known experimental curved girder behaviour. Presented here is an analytical study of the nonlinear modelling of curved steel girders and bridges. This is accomplished by incorporating large deflection and nonlinear material behaviour into three dimensional finite element models generated using the program ANSYS. Emphasis is placed on the calibration of the finite method with known experimental ultimate strength data. It is demonstrated that accurate predictions of load deformation and ultimate strength are attainable via the finite element method. The method is then extended to study the behaviour of a number of curved girders for which no experimental data exists. The influence of assumptions on the elastic stability behaviour of a curved beam is also examined by first formulating the total potential energy equation using a nonlinear strain definition. Then, the characteristic buckling equations are determined using the second variation of the total potential energy equation. Conclusion and recommendations are documented regarding the bifurcation and ultimate strength characteristics of curved girders. The finite element method is evaluated and as a tool for assessing curved girder and curved bridge behaviour.
Identification and characterization of downstream signaling partners of the endothelial cell-specific receptor tyrosine kinase, Tek/Tie-2

Tek/Tie-2 is an endothelial cell-specific receptor tyrosine kinase that plays a pivotal role in physiological and pathological angiogenesis. A family of ligands known as the angiopoietins has recently been shown to signal through Tek although little is known about the molecules that are involved in Tek-mediated signal transduction pathways. The goal of this study was to determine exactly how Tek is eliciting its signals in endothelial cells through the identification of substrates and docking molecules that bind the activated receptor. In order to circumvent the requirement for a ligand to specifically activate the receptor, we have used the yeast two-hybrid system to identify molecules that interact with phosphorylated Tek. Using this approach, we were able to demonstrate that a number of signaling molecules could associate with Tek, including the adaptor molecules Grb2, Grb7 and Grb14, the tyrosine phosphatase Shp2, the p85 regulatory subunit of phosphatidylinositol 3' kinase and one novel docking protein known as Dok-R. Mapping of the binding sites of these molecules on Tek has revealed the presence of a multi-functional docking site on Tek that is required for binding of Grb2 and Grb7 and for tyrosine phosphorylation of Grb7 and p85. Activation of Tek by Angiopoietin-1 results in tyrosine phosphorylation of p85 as well as stimulation of endothelial cell migration and survival pathways that are partly dependent on phosphatidylinositol 3' kinase activity. These findings support the role of Tek signaling in sprouting angiogenesis and endothelial cell survival. Dok-R contains numerous sites of tyrosine phosphorylation that mediate binding to RasGAP and Nck. Interestingly, overexpression of Dok-R downstream of the epidermal growth factor receptor can attenuate mitogen activated protein kinase activation and 'Dokr' maps to a locus that is rearranged in a number of lymphoproliferative disorders. These results suggest that Dok-R may be required for negative regulation of signal transduction. Further characterization of these downstream signaling molecules should prove useful in elucidating the role of Tek within the endothelial cell lineage, and this will ultimately contribute to our understanding of vascular development in both the embryo and the adult, as well as in pathological situations such as tumour-mediated angiogenesis.
Backdriving a full motion simulator using flight recorder data

This report shows the process and describes the programs necessary to play back an incident in a full motion helicopter simulator based only on flight recorder data. This removes the dependence on programmed flight equations, thus eliminating modelling errors in extreme conditions or manoeuvers. The process involved also determines aircraft states which were not recorded on the flight recorder. The resulting simulator flight shows a good correlation with the original flight, with some expected deviations in position and accelerations due to the limited available information.
Genetic polymorphisms in AH receptor and cytochrome P450 drug-metabolizing enzymes in relation to estradiol metabolism and breast cancer susceptibility

Bioactivation of environmental procarcinogens and prolonged exposure to 17ß-estradiol and catechol estrogens have been implicated in the etiology of mammary carcinogenesis. Endogenous 17ß-estradiol is oxidized to catechol estrogens by cytochrome P450 CYP1A2 and CYP1B1 enzymes which are transcriptionally regulated by the AH receptor. These enzymes are also involved in the bioactivation of numerous environmental procarcinogens such as benzo['a']pyrene. Consequently, those genetic polymorphisms in 'CYP1A2, CYP1B1' and 'AHR' that result in changes of enzyme or receptor function may affect 17ß-estradiol clearance and metabolic activation of procarcinogens. I genotyped two populations for a total of 7 polymorphisms in the 'AHR, CYP1A2' and ' CYP1B1' genes to examine whether these gene polymorphisms modify estrogen metabolism (Project 1) and breast cancer susceptibility (Project 2). Data of our estrogen metabolism study (Project 1) suggest that the 'AHR ' 554 polymorphism is related to alterations in 17ß-estradiol metabolism. Results of our Quebec French Canadian breast cancer case-control study (Project 2) indicate that the 'AHR' 554, 'CYP1A2*1F, CYP1B1*3' and 'CYP1B1*4' polymorphisms may modify breast cancer susceptibility.
Factors affecting life history variation in insects

Given the fitness importance of age at and size at maturity in insects, it is intriguing that in nature, there exists a large amount of variation in these traits. In this thesis, I examine the role of predator risk and time constraints on life history variation in the mayfly 'Ephemerella subvaria '. Unlike many other mayfly species, 'E. subvaria' is not known to exhibit anti-predator behaviours. This trait allows one to test for nonbehaviourally mediated life history responses. I also use a meta-analysis to examine the overall effects of predator risk on insect growth and development. While time-constrained 'E. subvaria' larvae tended to mature earlier than those that were not, there was no effect of predator risk on age at or size at maturity. In general, predator-induced life history shifts in insects were usually accompanied by changes in prey behaviour and growth rates.
Shame culture or guilt culture, the evidence of the medieval French fabliaux

Many literary critics have posited that during the Middle Ages society evolved from a shame culture, a culture in which honour was highly prized, to a guilt culture, a culture in which the Christian moral code was the predominant determiner of ethical behaviour. An examination of shame and guilt in the French fabliaux suggests otherwise. Beginning with a careful definition of shame and guilt as developed by anthropologists and psychologists, this study examines the vocabulary used to express shame and guilt. On this basis several semantic networks are constructed which reveal that shame is described not only by terms indicating diminished status and baseness but also by expressions from other realms of experience, such as terms describing staining, soiling, or filth, and expressions indicating punishment. Guilt in contrast is described only by terms which of necessity must indicate guilt given its definition: terms denoting misdeeds, transgressions, offences, recompense, forgiveness and punishment. Many terms indicative of guilt are in fact related to punishment and vengeance and are employed only in situations in which punishment is pending. An awareness of how one's actions have harmed the other is all but absent from the vocabulary of guilt. Feelings of shame occur more frequently than feelings of guilt and are typically central to the plot. Feelings of guilt in contrast are generally experienced only when characters expect to receive punishment. Intention plays a very minor part in determining whether or not a character feels guilty--all that matters is that a wrongful act has been committed. As agents of social control, both shame and guilt are frequently used in the fabliaux as sanctions against sexual impropriety. Shame is also frequently employed as a sanction against characters who seek to rise above their station, characters who demonstrate stupidity, those who are deceived or act like a fool, and those who exhibit cowardly or disloyal behavior. The sanctions of guilt are employed in more narrowly conscribed circumstances. Shame is generally an effective deterrent in the fabliaux, while guilt usually is not. All of this suggests the greater importance of shame.
Myocardial dysfunction following ruptured abdominal aortic aneurysm repair, the role of tumour necrosis factor-Ã

Rupture and repair of an abdominal aortic aneurysm, a combination of hemorrhagic shock and lower torso ischemia, is associated with a 50-70% mortality. Since myocardial dysfunction may contribute to the high mortality rate following aneurysm repair, the purpose of this thesis was to determine whether ruptured abdominal aortic aneurysm repair results in cardiac dysfunction, mediated by tumour necrosis factor-Ã (TNF-Ã). We modeled aortic rupture and repair in the rat by inducing hemorrhagic shock to a mean blood pressure of 50 mmHg for 1 hour followed by supramesenteric clamping of the aorta for 45 minutes. After 90 minutes of reperfusion, cardiac contractile function was assessed using an isolated heart perfusion apparatus. Myocardial TNF-Ã levels, myocardial energy stores (ATP and CP), neutrophil sequestration, markers of oxidant stress (F2-isoprostanes) and necrosis were measured. Cardiac function in the combined shock and clamp rats was significantly depressed compared to sham operated control rats, but was similar to that noted in animals subjected to shock alone. Myocardial TNF-Ã concentrations increased 10-fold in the combined shock and clamp rats compared to shams while there was no difference in myocardial ATP, CP, F2-isoprostanes and necrosis. Administration of a neutralizing anti-TNF-Ã antibody prior to shock improved cardiac function by 50% in the combined shock and clamp rats. Thus, Hemorrhagic shock is the primary insult inducing cardiac dysfunction in this model of ruptured abdominal aortic aneurysm repair and no synergistic effect between shock and aortic clamping was noted. An improvement in cardiac contractile function following immunoneutralization of TNF-Ã indicates that TNF-Ã mediates a significant portion of the myocardial dysfunction in this model.
A study of electrolyte melts for use in fused salt fuel cells

A molten salt electrolyte with an oxygen ion conductor for use in fuel cell developed starting from the simplest alkali-halide system. The constraints which had to be met by the proposed electrolyte system were: (1) Intermediate operating temperature. between that of current fuel cell systems, 250 to 450°C. (2) Halide melt should be stable in the presence of oxidizing and reducing gases. (3) Incorporate an oxygen ion conductor into the alkali-halide melt capable of regeneration from oxygen cathode gas (air) and the reducing anode gas and possess high ionic conductivity. A systematic approach was used beginning with thermodynamic paper studies, verified from thermal analysis, to select potentially stable systems. Once this was achieved, the halide melt was further discriminated by choosing the system with the highest conductivity between 250°C and 450°C. Then, an oxygen ion conductor was added to the halide in the form of a multi-valent oxide. The final electrolyte system consisted of a LiCl-KCl eutectic mixture with 5 mass % V2O5. This electrolyte was found to exhibit a single phase melt at 400°C and conductivity superior to that of the Alkaline Fuel Cell (5N KOH, @ 23°C) and the Molten Carbonate Fuel Cell (62 mole % Li2CO3 - 38 mole % K2CO3 , @ 650°C). It is perceived that this system will provide improved power generating properties, over current fuel cell systems, due to its more favorable polarization characteristics. The merits of this electrolyte system will only be fully realized when a proper fuel cell unit is examined.
Oropharyngeal dysphagia, reported assessment practice patterns of speech-language pathologists

This research comprised the first phase of a two-phase project to describe reported dysphagia assessment practices of speech-language pathologists across Canada and the United States. Specific objectives were to: (a) develop a self-administered mail questionnaire; (b) conduct a pilot survey using the questionnaire with Canadian speech-language pathologists to obtain preliminary descriptive practice information and evaluate questionnaire reliability. Questionnaire development included: literature review, expert consensus and pre-testing. Pilot testing of the questionnaire was conducted with a group of Canadian speech-language Pathologists, both experts and non-experts with dysphagia, involvement, registered with their national association. Survey success was achieved with high survey and item response rates. Clinicians were reliable reporters of their practice behaviours. Utilization was unanimously reported to be high for most physiological parameters. General practice was relatively more varied and appeared influenced by at least geography. A pattern of progressively decreasing utilization was noted, potentially related to stages of diagnostic work-up.
The NUMAchine I/O system

I/O facilities are a necessary part of any computing system. This work focuses on the design of the hardware that implements the I/O subsystem for the NUMAchine multiprocessor. The NUMAchine I/O subsystem is intended to provide all of the I/O capability that is required for the system, including disks, networking, and video display. The design centers on use of an embedded processor to drive the I/O subsystem, the software running on it performs many actions that are normally associated with a hardware controller. A PCI bus offers connectivity to standard peripherals, and multiple SCSI controllers allow access to high performance disks. The I/O subsystem has been built and tested with the rest of the NUMAchine system.
Evaluation of a virtual campus, Bell University Labs

Virtual communities are established to facilitate non-collocated collaborative work. Usability evaluations for single-user applications are insufficient to evaluate virtual communities. The evaluation method have to assess the usability of the interface as well as the effectiveness of group communication. This thesis presents an evaluation methodology to improve the infrastructure and participation of virtual communities. Three evaluation studies on the Bell University Labs website were used as a framework for evaluation. The studies discovered that the participation of the website was low, members used the website as a file sharing space, and there were usability and functionality problems in the website. Three types of user profiles were identified: one type with negative attitudes, a second type with different views on different components, and a third group with neutral opinions on the website. Suggestive steps for the user interface redesign and the evaluation methodology are recommended.