VictorJuiz/thesis huggingface dataset:
Investigations of ABA insensitive revertants of era1 in Arabidopsis thaliana

A screen for suppressors of the ABA 'era1' supersensitive mutant in 'Arabidopsis thaliana' had previously been performed in an effort to identify targets of the ERA1 farnesyl transferase and to identify downstream components of the ERA1 ABA-dependent signalling pathway. Out of 124 lines that retested, eight suppressors of 'era1' are ABA-insensitive, and have been designated 'i_nsensitive r_evertants of e_ra1'. Genetic analysis revealed that 'ire' mutants suppress 'era1' dominantly, but their insensitive phenotype is recessive. 'ire' mutants represent three complementation groups, one of which is a new mutation in the seed-specific ABI3 transcription factor that has previously been shown to mediate ABA responses during seed development. In addition to the seed supersensitivity of 'era1, ire ' mutants suppress adult phenotypes of 'era1', including drought tolerance. This is the first demonstration that AB1I3 has a genetic role outside of the seed.
Thyroid hormones and goitrogen-induced metamorphosis in the sea lamprey (Petromyzon marinus)

The larval sea lamprey undergoes a true metamorphosis from a sedentary, filter-feeding larva to a free-swimming, parasitic juvenile that feeds on the blood and body fluids of teleost fishes. As is the case with amphibians and teleosts, thyroid hormones (TH) are believed to be involved in lamprey metamorphosis. However, the onset of lamprey metamorphosis is characterized by a sharp decline in serum TH titers rather than the typical increase observed in all other vertebrates known to undergo this type of postembryonic developmental event. Furthermore, the goitrogen potassium perchlorate (KClO4), which lowers serum TH titers and prevents metamorphosis in most vertebrates, can induce precocious metamorphosis in larval lampreys. The primary goals of this thesis were to elucidate the role of depressed serum TH titers in the goitrogen-induced metamorphosis of lampreys and to provide some insight into the mechanisms involved in this induction. I have shown that KClO 4-induced lamprey metamorphosis can be blocked by using exogenous TH to prevent the decline in serum TH titers associated with induced metamorphosis. The ability to induce metamorphosis was not unique to KClO4. The goitrogens sodium perchlorate, potassium thiocyanate and methimazole also induced metamorphosis in larval sea lampreys, and the incidence of metamorphosis was positively correlated to the magnitude of the decline in serum TH concentrations. These data are consistent with the proposed ideas that either a decline in serum TH concentrations is essential for the onset of metamorphosis in lampreys, or elevated serum TH concentrations are inhibitory to metamorphosis (i.e., high TH titers have an anti-metamorphic effect in lampreys). In addition, I have shown that KClO4 administered to larval lamprey endostyles ' in vitro' reduces iodide uptake and organification, as well as total endostylar thyroglobulin. The fact that the goitrogen KClO4 acts directly on the endostyle to inhibit thyroidal activity further supports the notion that goitrogens induce metamorphosis via their effects on TH synthesis. In summary, I have shown that goitrogens act directly on the larval lamprey endostyle to inhibit thyroidal activity, thus resulting in a decline in serum TH titers that is linked to and essential for the onset of metamorphosis in lampreys.
Facilitating courses by computer-mediated communication and the role of the teacher, the community college teacher's perceptions

The main purpose of this study was to investigate the experience of community college teachers who use computer mediated communication in their teaching. Semi-structured interviews were conducted with ten teachers from three community colleges. The data collection was conducted in two stages: an initial round of six interviews, with concurrent analysis, and a second round of four interviews to further investigate emerging themes. The teachers reported that using computer mediated communication assisted them in moving out of the role of sole content provider toward a learning support role. They found that the characteristics of the medium helped them implement learner-centred strategies such as giving students more independence and decision-making opportunities, facilitating more active learning, and encouraging critical thinking. All of the participants saw online learning, which included the use of both Web resources and conferencing, as empowering for students. Teachers experienced substantial change through designing online course sites and implementing new strategies suitable for online learning. Four teachers said their perception of their role had changed, and they indicated that the changes were founded mainly in constructivist or adult learning theory and were confirmed by the online teaching experience. Interest in new learning and enjoyment of experimenting with technology were personal characteristics common to all participants. Most participants were seeking, and found, a sense of renewal and reward in mid to late career. This study demonstrated how teacher development processes occur in community colleges as teachers implement computer mediated communication in their courses. Some were engaged in personal vision building and all were engaged in inquiry, mastery, and collaboration. The necessity of collaboration and its contribution to professional development were especially strong themes. Several participants had become mentors, and some of these mentors reported that they used the opportunity to guide peers toward a learner-centred approach. The patterns of individual and institutional change in the three colleges provide examples of continuous, integrated change processes.
Gaseous reduction of nickel calcines in H¦2 and CO between 400°C and 850°C

The behaviour of two roasted nickel sulphide concentrates when heated in argon, hydrogen and carbon monoxide atmospheres was characterized by combining thermogravimetric analysis with off-gas analysis. Mass changes in inert atmospheres were attributed to sulphur dioxide evolution from solid state reactions between pyrrhotite and iron oxides (above 300°C) and from the decomposition of sulphates (above 550°C). In reducing atmospheres, sulphate decomposition was achieved at lower temperatures (250°C in H2; 350°C in CO; reduction of the hematite phase prevented SO2 emissions from the solid state reactions. Direct reduction of metal sulphides yielding H2S and COS was detected above 500°C. The rate of oxygen removal from two roasted nickel concentrates by H 2 and CO reductants was measured using thermogravimetric analysis. Non-isothermal and isothermal techniques were applied. It was found that hydrogen reduction obeyed a uniform internal reduction model. The temperature dependence of the rate constant obeyed an Arrhenius expression. Using isothermal analysis, different rate constants expressions were measured for the two calcines, however their activation energies were statistically the same (55 kJ/mol). The difference between the two expressions was attributed to the difficulty in measuring the degree of conversion in complex solids. Isothermal and non-isothermal thermogravimetric analysis failed to provide consistent rate expressions for CO reduction of calcines. The reduction rate was noticeably retarded above 600°C. In addition the deposition of carbon on the calcine pores was observed. It was concluded that carbon deposition had interfered with access of the gaseous reductant to the solid oxide, and hence lowered the reaction rate. Reoxidation of deeply reduced calcines in air was measured. Above 500°C, reoxidation caused samples to gain mass at a rate of &ap;8%/min. Calcines pre-reduced in H2 reoxidized approximately 20% faster than calcine pre-reduced in CO. From the relatively low activation energy of 12 kJ/mol, it was concluded that oxidation was diffusion controlled. This was in agreement with other researchers.
Factors affecting susceptibility of urban ravine forests to invasion by non-native vegetation

The relationship between ravine edge characteristics and the incidence of invasion by nonnative vegetation into local urban ravine forests was identified using plot sampling and multivariate data analysis. Survey data were collected from 41 urban ravine sites across the Greater Toronto Bioregion in 1999. Detrended Correspondence Analysis (DCA) was performed on canopy and ground vegetation for the 166 subplot dataset. DCA indicated that invasive vegetation was highly abundant in disturbed ravine versus mature stable forests. Canonical Correspondence Analysis (CCA) and Detrended Canonical Correspondence Analysis (DCCA) indicated that aspect, adjacent land use type, and edge characteristics were highly correlated with the ground and canopy species composition. Two-Way-INdicator-SPecies-ANalysis (TWINSPAN) clustered similar forest types together based on ground flora that are indicative of disturbed habitats, or exotic species. Results indicate that anthropogenic impacts to ravine forest structure is increasing the likelihood of invasion by non-native vegetation and that top-of-stable bank buffers would alleviate much of the disturbance within these ecosystems.
The effect of ingesting caffeine, ephedrine, and their combination on repeated strength performance

This study has investigated the effects of acute ingestion of caffeine (C) (4 mg·kg-1), ephedrine (E) (0.8 mg·kg -1), and their combination (C+E) on muscular endurance, using a double blind, repeated measures design. After ingesting either a placebo (P) or one of the three treatments cited above, 13 male subjects performed a weight training circuit consisting of three supersets of leg press (at 80% of 1RM to exhaustion) followed by bench press (at 70% 1RM to exhaustion). The mean number (±SD) of repetitions for leg press was significantly (p < 0.05) higher after both the E (17.4 ± 6.2) and C+E (19.8 ± 7.3) treatments than after either C (14.3 ± 6.4) or P (14.1 ± 4.8), but in the first set only. Similarly, the ingestion of E (13.3 ± 2.9) and of C+E (14.3 ± 3.1) was followed by significantly higher repetitions for bench press than was the case with the ingestion of either C (12.4 ± 2.7) or of P (12.7 ± 3.1). The total weight lifted during all three sets, both for leg press and bench press, did not change significantly after any of the three treatments when compared to P. Systolic blood pressure, measured both pre- and post-exercise, showed an increase with C+E (156 ± 29) and with E (150 ± 14) as compared to C (141 ± 16) and P (138 ± 14). It was concluded that acute ingestion of C+E and E increases muscular endurance, but only during the first of multiple bouts of exercise.
Subconscious control to reduce object slip in paediatric myoelectric hands

Although tactile sensing is fundamental to dextrous manipulation, this level of control has been previously unattainable in children's prosthetic hands. This is due to high costs and unachievable energy and computation requirements. The following thesis addresses these problems using a practical system to avert slip, with ideas from the hierarchical control models of dextrous robotic hands. A pre-existing slip detection algorithm was adapted for use with the myoelectric control circuitry and the standard mechanics of the hand. First, the algorithm for identifying slip was coded, then linked with a slip-motor controller. An interface circuit between the slip and myoelectric controllers was designed, built and tested. The slip controller gives the user precedence of control, and slip prevention acts as a 'subconscious' to the system. Preliminary testing showed that the system responded appropriately to a slipping object by increasing the hand's grip, force. Several experimental limitations are identified and discussed.
Individuals, thick and thin

My topic is the nature of individuality, at the intersection of metaphysics and biology. My approach in the first half of the thesis is in the spirit of what P. F. Strawson calls "descriptive metaphysics", in that it is an attempt to make explicit the most general features of our "common sense" understanding of individuality. In the second half of the thesis, I look at some issues in the philosophy of biology and Artificial Life. I first offer a defence of the "etiological" account of biological functions, and then turn to the question of the relationship between life and individuality. I argue for a broadly "externalist" conception of biological individuality, in that what something 'is', i.e., the real kind to which it belongs, is not determined by anything proper to the individual narrowly conceived; we must take into consideration the wider ecological context in which the organism finds itself. I apply the lessons of these later chapters to some problems in Artificial Life, and close with an exploration of the alleged distinction between a 'simulation' and a 'realisation'. I conclude with some speculations about the possibility of genuine computer-based life.
Word division in the transcription of Chinese script in the title fields of bibliographic records

In online bibliographic databases, Romanization of Chinese script can enhance access by facilitating filing, searching, and browsing of records. Recently the Library of Congress announced the replacement of the Wade-Giles Romanization system with the pinyin Romanization system for transcribing Chinese data in its bibliographic records. This decision will have a great impact throughout the North American library community. In its canonical form, pinyin, as opposed to Wade-Giles, aggregates Chinese "words" into single linguistic units. Since Chinese characters represent monosyllabic morphemes rather than words, Chinese text, in its original form, does not provide visual cues as to where a word starts or ends, and, therefore, does not provide guidance for joining syllables when the script is Romanized. In this respect, pinyin entries in bibliographic records could be constructed following either a monosyllabic, or a polysyllabic pattern. Although the former is easier and less costly to implement, the latter method is potentially more beneficial for end-users, since combining single syllables into linguistic units greatly reduces ambiguity, and generates a much larger variety of indexable terms, thus improving precision in online retrieval. The goal of the current study was to investigate if following the polysyllabic method significantly improves retrieval efficiency and effectiveness in item-specific searching within online bibliographic databases. Analysis of the results revealed that aggregation of monosyllables does improve efficiency significantly ('p' < .05), especially during keyword-based searches, and that effectiveness is unaffected by the inconsistencies observed in the aggregation format between cataloguer-generated records, and user-input queries.
The influence of sensor dynamics and navigation errors on E/SVS

This thesis presents the results of a study conducted in March and April of 1999 at the University of Toronto Institute for Aerospace Studies (UTIAS) Flight Research Lab. This work is part of a continuing study into the human factors aspects of Enhanced/Synthetic Vision Systems (E/SVS). In particular, the influence of sensor dynamics and the presence of navigation errors on pilot performance were investigated. Sensor dynamic models and a navigation error generator were developed and implemented in the real-time simulation. Six helicopter pilots with military backgrounds were used as subjects in an experiment to evaluate their performance using six different combinations of sensor dynamics and navigation errors. Objective performance measures were recorded and analysed along with subjective measures of workload. It was discovered that although pilot performance was not influenced by the presence of sensor dynamics and/or navigation errors, the time required to perform specific tasks as well as pilot workload ratings were affected.
Character animation using transformation based linear dynamics

In this thesis we show that physically based animation of deformable objects can be applied to character animation in a way that is compatible with existing computer graphics modeling and animation techniques. This is accomplished through the use of a low degree of freedom physical model based on transformations which are commonly applied to geometric models in computer graphics. We make contributions towards using B-spline based free-form deformations in this context, and show the benefits of embedding the geometric model in a predeformed transformation domain. We also make contributions towards a general treatment of potential functions for shape and volume preservation. We further show that the characteristics of the physical model can be synthesized from surface based geometry, and that constraints can be used to directly control models and construct motion hierarchies. Finally, we illustrate how character animation can be efficiently specified in an animation system based on these techniques.
Breath acetone as an indicator of ketosis while consuming a ketogenic diet

The ketogenic diet is a high fat, low carbohydrate diet used to treat children with intractable epilepsy. The maintenance of blood ß-hydroxybutyrate above 2 mM and acetoacetate above 0.6 mM is important to the diet's effectiveness. The objectives of this thesis were to determine whether the Ketostix urinary test for ketosis reflects plasma ketones and whether breath acetone is a better measure of plasma ketones than the urinary ketone test. It was hypothesised that breath acetone would be a more reliable indicator of the plasma ketones than the urinary ketone test. In adults in acute ketosis, urinary acetoacetate was significantly correlated with plasma acetoacetate (r2 = 0.72, p = 0.0003) and plasma ß-hydroxybutyrate (r2 = 0.52, p = 0.0057). Breath acetone was significantly correlated with plasma acetoacetate (r2 = 0.88, p < 0.0001) and plasma ß-hydroxybutyrate (r2 = 0.66, p < 0.0001). In rats in chronic ketosis, breath acetone was significantly correlated with plasma ß-hydroxybutyrate (r 2 = 0.73, p < 0.0001). Breath acetone and Ketostix urinary acetoacetate are both significantly correlated with the plasma ketones.
Decision analysis for Bangladesh coastal afforestation

Bangladesh is known as a country of natural disasters. Disasters have become a regular phenomenon and have caused suffering to millions of people for many decades. The coastal areas frequently experience cyclones and water surges. The importance of sustainable, forest management in relation to Bangladesh is discussed. The role of coastal afforestation in protecting the country from natural hazards like floods is emphasised. Equations for the estimation of flooded area in terms of the altitude of the area, the wind speed, the maximum surge height and width of the forest of that area. Models that relate flooded area to wind speed, sea level and maximum surge height were developed for dams, and protective forests. It was observed that a coastal afforestation program could significantly reduce the flooded area by creating a drag force But this will depend on the width of the forest, the number of stems per unit area and the size of the trees. Effect of branches or the roughness of the land were not considered. Finally, a decision analysis was carried out for coastal afforestation in Bangladesh. The analysis based the information available suggested that the government should support coastal afforestation. In addition to protecting against natural calamities like surges, coastal afforestation has the potential to improve the socio-economic condition of the people, especially the coastal people. It was recommended that the Government of Bangladesh should proceed with both coastal afforestation and dams. If there is budget constraint then the government should proceed with coastal afforestation alone.
Cancer among Ontario electric utility workers, the evaluation of alternate indices of exposure to 60Hz electric and magnetic fields

Three research objectives were addressed within this thesis. First, the relationships between indices of 60 Hz electric and magnetic field exposures measured in Ontario electric utility workers were evaluated to identify a series of independent exposure metrics for cancer risk assessment. Second, using these exposure indices, cancer risks were estimated using data from a nested case-control study of Ontario Hydro workers assembled as a component of a previous Tri-Utility Study. Cancers examined included: leukemia, brain cancer, malignant melanoma and Non-Hodgkin's lymphoma. Third, a simulation study was undertaken to investigate the gains in power that could be achieved by performing additional sampling to reduce the variance of the mean exposure estimate assigned to each job category, or alternatively, by increasing the number of cases and controls. The principal components and correlational analyses revealed that aspects of field strength, other than those of a central tendency, should be examined when performing cancer risk assessment in this population. In particular, metrics that capture fluctuations in field strength, and exposures above threshold cut-points warrant consideration. Moreover, the poor correlations observed between electric and magnetic field exposure indicate that risk assessment should be undertaken separately for both field entities. The percentage of time spent above an electric field within the range of 10-39 V/m was found to be associated with an increased risk of leukemia and Non-Hodgkin's lymphoma over and above associations explained by either the geometric or arithmetic mean. Duration of employment was associated with an elevated risk of leukemia and malignant melanoma. Magnetic field exposures were not significantly associated with any cancers examined, however, analyses of brain cancer cases were limited by small sample sizes. Taken together, the results are consistent with the hypothesis that electric fields act as a promoting agent in the process of carcinogenesis of adult leukemia and Non-Hodgkin's lymphoma. The simulation study revealed that greater improvements in power were realised by increasing the number of cases and controls rather than by conducting additional exposure assessments on an equivalent number of workers. No appreciable gains in power were achieved by sampling more than 15 workers in each occupational grouping.