VictorJuiz/thesis huggingface dataset:
Microcellular wood-fibre thermoplastic composites, processing-structure-properties

In this study, processing-structure-property relationships in foamed wood-fibre plastic composites made with a physical blowing agent were investigated. For the polymers studied, it was found that the crystallinity and morphology have a critical effect on the foaming process. Therefore, an investigation of both semicrystalline and amorphous polymers was conducted. Several amorphous and semicrystalline polymers were selected, based on preliminary experimental results. By non-isothermal crystallisation of the semicrystalline polymers at various cooling rates, specimens with different crystallinities and crystal morphologies were made. The microstructures and sorption properties of these specimens were studied. All the specimens were foamed in a batch process using carbon dioxide as blowing agent and their structures were, investigated. The results showed a great influence of crystallinity and morphology on the solubility and diffusivity of the blowing agent in and through the polymer and especially on the cellular structure of the resulting foams. In contrast to the work of Colton (1989), who suggested that the foaming process should be conducted at a temperature above the melting point, it was shown that by controlling the crystallinity and crystal morphology it is feasible to produce microcellular foams from semicrystalline polymers in the solid state. In the second phase of the study, high density polyethylene and polystyrene were used as the matrices in a foamed wood-fibre composite. Sheets of composites were produced by compounding polymers and fibre. These samples were saturated with carbon dioxide at high pressure and the saturated specimens were foamed at elevated temperatures. Structural analysis and characterisation were performed on both foamed and unfoamed samples. The experimental results showed that the addition of wood fibre had very different effects on the mechanical properties of polystyrene (a glassy polymer) and polyethylene (a semicrystalline ductile polymer). Fibres acted as nucleating agents in the crystallisation of the matrix, and drastically changed the morphology. The impact strength of PS increased when wood fibres were added, while wood fibre diminished the impact strength of PE. The presence of wood fibres significantly changed the microstructure of the composite in the foaming process. Overall, while diminishing the tensile properties (strength and modulus), foaming caused a significant improvement of impact strength of the wood-fibre composites.
An examination of chromatin-associated hsp70 during heat shock in Drosophila

The heat shock (hs) response is activated in cells subjected to stress. It is regulated at the molecular level by the heat shock transcription factor HSF. During exposure to stress, inactive monomeric HSF trimerizes and acquires high DNA binding activity to a well-conserved sequence, the hs element (HSE). During prolonged hs, attenuation of the hs response is marked by HSF dissociation from HSEs and the return to its monomeric form. One of the products of hs genes, hsp70, has been implicated in autoregulation of the hs response. We have examined the chromosomal accumulation of hsp70 during heat shock and its possible colocalisation with several different factors. We have found a 78% colocalisation between HSF and hsp70. Subsequent experiments have demonstrated that chromosomal accumulation of hsp10 during hs does not depend on the presence of HSE-bound HSF or the presence of mRNA. A possible role of hsp70 in HSF inactivation is discussed, along with other targets of hsp70 during hs.
The characterization and modeling of a parallel batch workload

Understanding the characteristics of parallel workloads aids in the design and evaluation of parallel operating systems. At present, little is known about parallel workloads. To learn more, we study the workload observed an a group of multiprocessors at the National Center for Supercomputing Applications. We use a clustering technique to discover natural classes of parallel jobs. We analyze several workload features separately, including arrival time, number of processors, parallel efficiency, CPU tone, memory, file I/O, and interprocess communication messages. Summary statistics and graphical depictions are given for the observed distributions of each feature. We also investigate correlation amongst the features. The results of this analysis are used to support a parallel batch workload model, which incorporates probability distributions for modeling job, arrival, CPU time, runtime, efficiency, memory size, and IO demand. In addition, we show that some distributions commonly used to model workload features are not good models.
The effect of form-focused instruction on control over grammatical gender by French immersion students in grade 11

This study investigates the effect of form-focused instruction on control over grammatical gender by French immersion students in Grade 11. Previous research has shown that while native speakers of French acquire control over grammatical gender at a very early age, and seemingly with little or no instruction, anglophone learners of French have a great deal of difficulty with this concept, since it is not a feature of their first language. There is a growing body of research providing evidence that form-focused instructional strategies, when used in conjunction with a primarily experiential approach, can enhance the accuracy of immersion students' second language output. To date, most of this research has been carried out at the elementary level. The present study arose partly out of the need to address the issue of form-focused instruction at the secondary level. Sixty-two students took part. There was an experimental class and two comparison classes. The study consisted of pretests, an eight-week treatment period in the experimental class, immediate posttests and delayed posttests. The five tests used were: listening test, written endings test, agreement test, writing assignment, and oral production task. During the treatment period, the experimental group was exposed to form-focused tasks designed to make them aware of word-ending regularities as clues to the gender of French nouns, and to provide practice in making gender agreements. Other aspects of the study included teacher observations of the experimental class, and questionnaires designed to elicit the students' reactions to the treatment materials. Statistical analyses showed that the experimental group made significantly greater progress over time than the comparison classes on three measures (listening test, written endings test, agreement test). On the other two measures (writing assignment and oral production task) the experimental class outperformed the comparison classes over time; however, the differences were not found to be statistically significant. While further research is needed to follow up on these results, there is at least tentative support for the use of form-focused instruction as a means of improving French immersion students' control over grammatical gender.
The career of Gordon Murray, patterns of change in mid-twentieth century medicine in Canada

This thesis describes some aspects of mid-twentieth century developments in Canadian medicine through the exceptional career of Gordon Murray (1894-1976). His Toronto surgical career spanned over fifty years during which significant changes in medical education and training, surgery, clinical investigation, experimentation and treatment, and medical reporting occurred. Murray conducted his surgical operations and clinical investigations skillfully and independently with remarkable successes during the first thirty years of his career. His boldness and individualism were both his strengths and weaknesses, awarding him both success and failure. In the latter years of his career, Murray made several bad professional choices, misreading the future and misjudging his own abilities. It became clear that he was unable and unwilling to adapt to the new postwar medical culture and its increasingly specialized, team-oriented practices. His lone practices and experimental approach to medical problems, which had been earlier strengths, became liabilities in this new research world. He began exploring new and complex research questions independently and ineptly, and an impressive career ended tragically as a result. Murray was a talented surgeon with a fertile, creative and restless mind, who thought broadly and confidently about tackling complex medical problems. His diverse and impressive list of contributions reflects this range of interests. He investigated the clinical application of heparin, expanded the possibilities of vascular surgery, performed the first congenital heart or "blue baby" operations in Canada, pioneered heart valve and renal transplant procedures, and built the first North American artificial kidney machine. Later in his career, he pursued research on cancer sera and vaccines as well as spinal cord regeneration, controversial work that ultimately damaged his reputation. His boldness and innovation contributed to both his success and downfall as a surgeon and investigator. Confident and ambitious, Murray spent a lifetime searching for answers to some of medicine's greatest challenges during a period of tremendous surgical advances and research changes that eventually overcame him.
Detecting, measuring, and imaging the microcirculation with high-frequency Doppler ultrasound

The microcirculation plays varied and critical roles in our general well being and defects in the microcirculation manifest themselves in many important disease states. In this thesis, the extension of Doppler ultrasound to the ultrasound frequency range 20-200 MHz is investigated as a non-invasive and quantitative technique for detecting, measuring, and imaging the microcirculation. The theoretical advantages and limitations of high-frequency Doppler ultrasound (HFD) are discussed. Experimental continuous-wave and pulsed-wave HFD systems, which have been designed, constructed and optimised for detecting blood flow in the microcirculation, are described. Implementation of the systems at 40-MHz and 50-MHz in experimental investigations with phantoms show that HFD can detect and measure velocities on the order of the blood velocities found in the capillaries (<0.5 mm/s) and arterioles (<5 mm/s) with a suitable velocity resolution (30-200 [mu]m/s), although the temporal resolution (150-500 ms) had to sacrificed slightly. 'In vivo' experiments with a mouse ear model of the microcirculation demonstrate that HFD is capable of detecting and measuring blood velocities slower than 5 mm/s in arterioles of only 20 [mu]m diameter and venules of only 35 [mu]m diameter using a sample volume of only 70 [mu]m laterally * 150 [mu]m axially. ' In vivo' experiments using a rat mesentery model and intravital microscopy conclusively demonstrate that HFD can map the microcirculation in an arteriole bifurcation as well as detect the microcirculation in capillaries. The potential of high-frequency colour and power Doppler imaging is also demonstrated, and the two experimental systems are implemented in several preliminary biological and clinical investigations. This thesis has successively demonstrated that HFD is a unique and versatile technique with great potential as a tool for investigating the microcirculation in both clinical and laboratory settings.
Targeting and intracellular traffic of the epithelial isoforms of the Na§+/H§+ exchanger

The Na+/H+ exchangers (NHE) are a ubiquitous family of membrane proteins which catalyze the counter-transport of extracellular Na+ for intracellular H+ and are important for intracellular pH and cell volume regulation. The epithelial isoforms, NHE2 and NHE3, thought to have more specialized roles in regulating Na+ and H2O absorption, are differentially regulated and exhibit differential intracellular localization. NHE2 is primarily localized to the plasma membrane whereas NHE3 is primarily intracellular, located in recycling endosomes. NHE3 is apically targeted whereas the polar localization of NHE2 remains controversial. We have localized NHE2 to the apical membrane of LLC-PK1 cells and have identified residues 732-777 to be critical for apical targeting. These residues encompass a proline-rich region which was found to interact with the SH3 domain of A-spectrin 'in vitro', an interaction which may play a role in NHE2 targeting. Although SH3 domains of other proteins were found to bind to this and a more carboxy-terminal proline-rich region ' in vitro', the functional significance of these interactions remains unclear. Deletion of all residues carboxy-terminal to 731 did not affect Na+/H+ exchange nor its response to hypertonicity and metabolic depletion. We have identified the pathway that mediates internalization of NHE3. Traffic of this isoform from the plasma membrane to the endosomes requires clathrin. Furthermore, we have shown that the normal distribution of NHE3 requires the activity of <math> <f> <g>3</g></f> </math>-COP, a component of the COPI coatomer. During the course of studies of pH regulation, a serendipitous observation led to the identification of a novel mammalian NO3-H + co-transporter. This system was characterized in detail and found to be electroneutral and voltage-insensitive. The ion selectivity and pharmacologic profile indicates that NO3--induced H+ flux occurs through a pathway different from other well characterized transporters including NHE and the anion exchanger.
Crusonia, Daniel Defoe and the Atlantic imagination

From the middle of the sixteenth century, the English economy expanded into the Atlantic, across the ocean to America and along the Atlantic coast of Africa. In 'Robinson Crusoe', Defoe invents, or, as I prefer, imagines the English Atlantic world through the story of his protagonist on Crusonia, the island colony he established in the Caribbean in the middle of the seventeenth-century. "Crusonia" is an attempt to situate Defoe's novel in the historical context of the English Atlantic world and to examine the ways that the novel becomes part of subsequent Atlantic history: it examines the history in and of 'Robinson Crusoe'. The Introduction of my dissertation maps Defoe's novel geographically, critically, historically, and theoretically. The subject of the first chapter is the English Atlantic archive: the way that colonial histories, travel narratives, colonial promotional books and pamphlets, the writings of merchants, planters and political economists order the Atlantic world through the imagination. I read texts from the English Atlantic archive in order to discover the motives and preoccupations of literary Atlanticists. Chapter 2 considers Defoe's contributions to the English Atlantic archive. The unifying theme in Defoe's Atlantic dossier is the project. Defoe was an important economic journalist, and one with a special interest in the English Atlantic world. Defoe's colonial ideas are teased out of the body of his economic writings and investigated, leading, finally, to a reading of literary texts, like 'Captain Singleton, Colonel Jack', and 'Moll Flanders', that belong to the Atlantic portion of his oeuvre. The next and most important chapter is devoted to an extended reading of 'Robinson Crusoe'. In this chapter I investigate the organization of the plantation complex on Crusoe's island. What kind of property relations are being represented in 'Robinson Crusoe'? Defoe's imaginary island is compared to other forms of colonial property such as the Carolina colony, the constitution of which was written by John Locke, theorist of private property. In this chapter I also undertake an analysis of labour relations on Crusoe's island, comparing the representation of Friday's status to the forms of colonial labour that obtained on English plantation colonies: bond servants and slaves. The examination of Crusonian political economy is the basis for a rereading of the relationship between Crusoe and Friday, the most important fictional element of the novel. Chapter 4 analyzes Crusonia from below. Beginning with a brief reception history of Robinson Crusoe as an Atlantic text, I go on to look at the way that Defoe's novel inspired reactions to the world that it represents. In this chapter, I place Thomas Spence's radical re-reading of Defoe's novel in the context of wide-spread resistance (both literary and otherwise) to the kind of colonial regime that Crusonia represents. Spence's work and activism inspired such black anti-slavery activists and writers as Robert Wedderburn, and provides a way into an examination of an alternative, other Atlantic imagination. (Abstract shortened by UMI.)
Exploring the changes in teaching strategies enabled by Internet and communications technology

This study explored the changes in teaching strategies enabled by Internet and communications technology (ICT). I interviewed eleven schoolteachers who were using network-based technologies in their classrooms. I also conducted a series of informal classroom observations. All interview and observation data were recorded and transcribed. The prevailing themes that emerged from the data illustrated the impact of ICT on the changing role of the teacher, classroom dynamics, teacher predictions of ICT in the school and the concept of the classroom. From the findings it may be inferred that as teachers further integrated ICT into their classrooms, they adopted different teaching strategies to counter balance the attraction of ICT. The teachers interviewed agreed that ICT in the classroom fundamentally influenced the process of learning. As a result, they were required to adjust their teaching strategies in terms of the delivery of curriculum content. The teachers also said they had to accommodate for the power shift in the classroom because often students had more knowledge of ICT than their teachers. The findings also revealed that the physical structure and dynamic of the traditional classroom was changing. ICT brought in a vast amount of external information and allowed for the increased communication and learning with other people from sources outside the direct control of the teacher. Boundaries between subject matter and physical locations where students could learn were diminishing. As a result, the domain of the classroom, where teachers were typically in control, was being directly challenged. The teachers also identified the need to focus on teaching new skills in how to read, reply to (write) and analyse information delivered from ICT. Finally, the teachers needed time to learn about the technology and to understand how to integrate ICT into the curriculum. Further studies in this area should continue to focus on meaningful uses of ICT in the classroom, new skills needed to effectively use ICT, as well as criteria for effective teacher training.
Mantle flow and the geological record, dynamical mechanisms for continental epeirogeny

The geologic record shows that continents have periodically experienced episodes of large-scale subsidence and uplift which result in widespread marine transgressions. The focus of my thesis is to consider the dynamic topography caused by fluid convection in the mantle as a mechanism for these enigmatic epeirogenic motions. The first part of the thesis examines subsidence at continental margins and the role of subduction-induced flow in producing the surface deflections. Numerical simulations of mantle convection in a Cartesian geometry are adopted to model the flow dynamics associated with stiff subducting slabs. An analysis of the stratigraphy and paleotectonics of the Russian Platform during the Paleozoic reveals a correlation between subsidence of the platform and subduction events at the continental margin. Numerical models of mantle flow and dynamic topography are computed and the predictions are able to reconcile the observed sedimentation history. The Late Paleozoic subsidence of the Karoo Basin is also considered in this context. Numerical simulations indicate that dynamic tilting caused by subduction-induced mantle flow works in tandem with flexural loading of the lithosphere to explain the subsidence and uplift history of the basin. The latter half of the thesis focuses on the interaction of various classes of mantle flow with the endothermic phase change at 660 km depth and investigates the associated surface manifestations. A model of fluid convection in axisymmetric spherical geometry is introduced to simulate flow regimes in a multi-phase mantle. My numerical simulations show that 'mantle avalanche' events are capable of causing long-wavelength lithospheric subsidence with vertical amplitudes of ~2500 m over timescales of 150-200 m.y. Based on these results, it is speculated that an avalanche event may provide a plausible explanation for the Devonian evolution of the Laurussian supercontinent. I also consider the dynamic topography associated with more 'generic' mantle flow regimes, namely 'stiff' descending plumes and slabs. The plume/slab flow models are found to induce wide (~1000 km) topographic deflections of amplitude ~1 km which persist over timescales of 100-150 m.y. Simple models of sedimentation in these dynamic depressions suggest that these classes of mantle flow may be a plausible mechanism for the enigmatic development of transient intracratonic basins.