VictorJuiz/thesis huggingface dataset:
EXPLORE/OC: A photometric search for transiting extrasolar planets in southern open clusters

Our eclipsing binary sample is large enough to offer a statistical view on the evolution of the fraction of eclipsing binaries in open clusters. Using our cluster contact binaries, we find evidence that the fraction of contact binaries increases on a timescale of Gyr, consistent with previous work. Extending those previous results to detached binaries, we find that detached binaries in clusters are destroyed on Gyr timescales. Pooling our detached binary detections from both clusters and the field, we find no support for the hypothesis that the binary mass ratio distribution is peaked towards equal masses. In each cluster field, we find of order one transit-like variable, and dozens of eclipsing binary stars and pulsators. This number of planet candidates is in line with the expected frequency of planet occurrence derived from other planet searches. Extrasolar Planets Occultation Research in Open Clusters (EXPLORE/OC) is a monitoring survey of eight Southern open clusters, designed to detect transits of close-in extrasolar giant planets. In total, the survey produced a sample of approximately 32000 stars with 2--10 mmag photometric precision (rms). For stars both in clusters and the Galactic field, we discriminate between planet transits and other sources that vary with amplitudes of a few percent by combining this excellent precision with high time-sampling (1000--2000 measurements per star, spread over three weeks). The survey employs special techniques to measure and characterize the tens of thousands of sources. The data reduction pipeline incorporates neighbour subtraction and a generalized aperture photometry approach for mitigation of common observational systematic errors. We evaluate distances and spectral types for our sources by spectral energy distribution fitting. Armed with distance estimates, we are able to assign robust cluster membership probabilities to our sources.
Sample preparation for femtosecond electron diffraction: Photodissociation of triiodide

Femtosecond electron diffraction is a relatively new technique used to study reaction pathways at the femtosecond (10-15 s) time scale. With this technique, it will be possible to observe reactive intermediates and short-lived transient states and the timeframe in which they occur. The photodissociation of triiodide is an ideal molecular reaction to study. The dynamics are within the time resolution range of our current setup and the iodine atoms are excellent scatterers of electrons. Before reactions can be studied by femtosecond electron diffraction studies, suitable samples of the molecule or system of interest must be prepared. The sample preparation for these experiments is not trivial, especially for molecular systems such as triiodide. Three methods of preparing samples of triiodide for these experiments were performed: dropcasting, spincoating, and melting with slowly cooling. The latter two showed promise in producing samples that give diffraction.
Attachment and subjective well-being: the mediating role of emotional processing and regulation

According to attachment theory (Bowlby, 1982/1969; Sroufe & Waters, 1977), the ability to regulate affect develops through attachment-related experiences. The attachment strategies formed in early childhood are internalized and become part of self-regulating strategies, which are important for adaptive functioning (Fonagy, Gergely, Jurist & Target, 2002; Mikulincer, Shaver & Pereg, 2003; Schore, 2003). The goals of this study were to (1) further elucidate the relationship between the two-dimensional construct of attachment (i.e., anxiety and avoidance) and the internal cognitive-affective mechanisms involved in emotional processing and regulation (i.e., negative affectivity, emotional awareness, emotional clarity, acceptance of emotional responses, access to emotion regulation strategies) and (2) examine whether these cognitive-affective mechanisms mediate the link between attachment and subjective wellbeing (i.e., positive affect, negative affect, life satisfaction and self-esteem). Online survey data (N = 213) were collected from a community sample recruited via listservs. Intercorrelations revealed that attachment anxiety was moderately to strongly related to negative affectivity, lack of emotional clarity, nonacceptance of emotional responses, limited access to emotion regulation strategies and subjective wellbeing. Attachment avoidance was moderately related to lack of emotional awareness, lack of emotional clarity, nonacceptance of emotional responses, limited access to emotion regulation strategies and subjective well-being. When the two attachment dimensions were examined simultaneously, attachment anxiety uniquely predicted negative affectivity, nonacceptance of emotional responses, limited access to emotion regulation strategies and subjective well-being. On the other hand, attachment avoidance uniquely predicted lack of emotional awareness and lack of emotional clarity. In testing for mediation, regression analyses revealed lack of emotional clarity and limited access to emotion regulation strategies as significant predictors of subjective well-being above and beyond the other cognitive-affective mechanisms of emotional processing and regulation. Hierarchical regressions and tests for indirect effects show that attachment anxiety and its link to subjective well-being was mediated through both cognitive-affective mechanisms with limited access to emotion regulation strategies as the stronger mediator. Attachment avoidance and its link to subjective well-being was mediated through emotional clarity. Insights on how assessment of attachment dimensions may be used to inform psychological practice are offered.
The effect of Ras/MAPK signaling in the mouse hippocampus: a morphological examination of synaptic and dendritic alterations in CA1 (California)

Considerable evidence has accumulated demonstrating that dendritic processes involved in synaptic plasticity are critical for learning and memory. However, little research has focused on presynaptic mechanisms underling learning and memory in mammals. The laboratory of Dr. Alcino Silva at the University of California at Los Angeles developed a RasG12V mouse model, and conducted experiments which exposed novel aspects of Ras function in post-mitotic neurons, by taking advantage of this mutation to increase signaling through the mitogen-activated protein kinase (MAPK) pathway. This mutant demonstrated enhanced long-term potentiation (LTP), enhanced behavioral learning, and a primarily presynaptic localization of this Ras isomer. The current research examined changes in spine and synaptic morphology that may underlie the types of neural plasticity observed in this mutant. No changes in synapse per neuron densities for total synapses, total macular synapses or total perforated synapses were observed in RasG12V as compared to wild-type (WT) mice. Electron and light microscopy analysis of hippocampal CA1 excitatory terminals revealed that the general appearance of presynaptic terminals, spines, and postsynaptic densities was similar in WT and RasG12V mice. There was however, in the RasG12V mutant, a significant increase in the density of docked vesicles, an increased proportion of concave perforated synapses, and an increased number of mushroom shaped spines. The current research suggests that the presynaptic signaling mechanisms associated with this mutant may modulate neural plasticity by increasing the size of the readily-releasable vesicular pool. However, while alterations in presynaptic vesicular docking may be the initial and primary mechanism underlying the electrophysiological and behavioral alterations in these animals, this change apparently has downstream effects, with an associated increase in the proportion of concave perforated synapses and mushroom spines. Taken together, these alterations in the mutant may account for the enhancements in LTP and learning previously observed, and suggest that alterations in these synaptic and dendritic morphological characteristics may play a critical role in LTP, and, learning and memory processes in general.
Novel pulse compression algorithms based on Golay codes for ultrasound imaging of blood flow

Blood flow imaging is routinely used in the diagnosis of various clinical conditions. With the aid of numerous signal processing techniques and more recently ultrasound contrast agents, ultrasound is currently the diagnostic imaging modality of choice for many clinical applications. However low frame rates, signal-to-noise ratio (SNR) and penetration depth limit the potential of ultrasound imaging of blood flow in these applications and the expansion of its use to other applications. In this thesis, two novel pulse encoding algorithms based on Golay codes are presented, for diagnostic imaging of blood flow using ultrasound. These algorithms address limitations of existing techniques, providing improvements in signal-to-noise ratio, penetration depth and frame rate. Simulations and experiments were performed to validate the performance of these algorithms. The experiments confirmed that Fast B-flow can provide frame rate improvements of up to 33%, with SNR and residual sidelobe levels which are comparable to those of existing techniques at high flow velocities. A novel nonlinear coding algorithm for microbubble ultrasound contrast agent imaging is presented, which provides 6.5 dB enhancement in contrast-to-tissue ratio compared to existing techniques. Issues pertaining to the practical implementation of these codes are also discussed, as well as applications of the presented techniques.
Towards low polydispersity polyphosphazenes: Synthesis, reactivity and behavior of new phosphoranimines

Polyphosphazenes are of interest for many potential applications; however their utility has been hindered by their ease of synthesis. Work over the past decade has shown that the molecular weight of the polymer may be controlled through living cationic polymerization of the N-silylphosphoranimine Cl3P=NSiMe3, in lieu of traditional thermal ring-opening methods. While the living route, initiated by PCl5, offers greater control over molecular weight, the polydispersities obtained thus far remain too great (PDI > 1.1) for nanoscience applications. To this end we have undertaken studies to decrease the PDI through the development of new N-silyl and N-stannylphosphoranimines and new compounds of the form [R3P=N=PCl3]X, which have been shown to initiate cationic chain growth. This work has allowed for mechanistic studies that were previously hindered by the formation of polymer byproducts and the preliminary investigations of a polyferrocenylsilane-polyphosphazene diblock copolymer system.
Analysis of electrical activities in hippocampal slices using coherence measures

Studying coherence from extracellular and intracellular electrical recordings in hippocampal slices provides a way to uncover, characterize and clarify many tasks and functions associated with the hippocampus. In this thesis, a signal processing tool was developed to study coherence on nonstationary biological data from hippocampal slices. Time Delay Estimation was used to find the maximum likelihood of the location of the best match between the biological recordings. Continuous Wavelet Transform was employed to decompose the data into two groups of low and high frequency ranges. Multichannel Blind System Identification was applied on the grouped signals to find their common signal. Finally, coherence measures for nonstationary biological data from hippocampal slices were obtained by utilizing the stationary coherence function on sliding windows between the common signal and the recorded signals. The thesis shows that the signal processing tool can be used as coherence analysis of nonstationary biological signals from hippocampal slices.
Modulation of primate orofacial motor activity by sleep/wake state

During sleep, the sudden and repetitive appearance of jaw muscle contractions is termed "rhythmic masticatory muscle activity" (RMMA). RMMA is found in normal sleepers and in patients who also exhibit tooth-grinding during sleep, i.e. sleep bruxism (SB). The consequences of SB are occasional facial pain or jaw dysfunction, headache and tooth damage. However, the pathophysiology of SB is unknown. Therefore, the objectives of the present thesis were to: (1) investigate further the role of cortical events (e.g., K complexes) in the genesis of SB; (2) determine whether a sequence of events dominates in association with the appearance of RMMA-SB activity (e.g., whether brain, heart and muscles are activated simultaneously or sequentially); (3) test whether experimentally induced sleep arousal could trigger SB and tooth grinding, in order to challenge the view that SB is secondary to sleep arousal; (4) assess whether jaw muscle excitability is increased or depressed during sleep. Methods included sleep laboratory polygraphic recordings of brain, heart and jaw muscle activities in order to quantify ongoing RMMA and SB in relation to wake and sleep states in humans. Sleep-related jaw muscle excitability was studied in monkeys. The main results were: (1) the density of cortical K complexes is 2--3 X lower in SB patients than in control subjects; (2) the presence of RMMA-SB in sleep is secondary to the occurrence of micro-arousal that is characterized, in sequence, by the onset of activity in brain and heart, then contractions of the jaw-closing muscles that are coupled with tooth grinding; (3) the use of a vibrotactile stimulation induces RMMA and tooth grinding in 71% of trials in SB patients only; (4) jaw muscle excitability is depressed during sleep in monkeys. In conclusion, these data support the hypothesis that RMMA and SB are secondary to sleep arousal rather than a rise in trigeminal motoneuronal excitability during sleep. Moreover, these findings provide new insights into the pathophysiology of SB by revealing the importance of the physiological mechanisms underlying sleep and arousal as opposed to external factors which traditionally have been emphasized in its pathophysiology, i.e., stress and dental occlusion.
Secondary prevention of eating disorders: the teachers' perspective

The present investigation used a qualitative approach to research the experiences of secondary school teachers regarding the early identification of eating disorders. Ten teachers were interviewed in this study. The teachers' experiences with identifying eating disorders were found to be similar to challenges found in identifying depression. Facilitative factors of identification included a close student-teacher relationship, overt symptoms, and personal mental health issues. Barriers to identification included a distant student-teacher relationship, lack of knowledge, and hiding symptoms. The teachers who referred students for help were physical education teachers. Teachers who identified students with eating disorders but did not take action believed it was not appropriate to intervene, wanted to wait to see if the problem progressed, and were fearful of breaching trust. Further teacher training is needed to help teachers to identify student mental health issues and systemic changes need to be made to enhance teachers' comfort with referral.

Keywords: Eating disorders, Prevention
Eating disorders, Psychological aspects
Mind and body
Body image disturbance
Stress management
Control (Psychology)
Losing yourself to AIDS: the meaning of euthanasia and assisted suicide

A qualitative research study was conducted with 32 people with HIV/AIDS in order to develop a theory of decision making regarding euthanasia and assisted suicide. The participants were enrollees of the HIV Ontario Observational Database (HOOD) and were contacted using a novel anonymous recruitment technique. The participants were interviewed and the audio-tapes of the interviews were transcribed and analysed using grounded theory methods in order to determine the process of decision making, factors that affect people's decisions, and the meaning of the experience of deliberating about euthanasia and assisted suicide. The resulting theory describes a process of deliberation that involves the origin of consideration about euthanasia and assisted suicide, reflection on these options, either alone or with others, formation of specific goals and the development of plans and strategies designed to realize the goals. The main factors that influence these deliberations are the individual's disintegration and loss of community. These factors give rise to a perceived loss of self, which in turn gives rise to existential suffering. Euthanasia and assisted suicide can be understood as means of limiting the loss of self. These findings suggest that decisions regarding euthanasia and assisted suicide are primarily metaphysical in nature, as opposed to ethical. The findings also challenge the appropriateness of the prevailing medical conception of euthanasia and assisted suicide that is apparent in existing policies and legislation.

Keywords: Euthanasia, Canada
Assisted suicide, Canada
AIDS (Disease), Patients
AIDS (Disease), Canada
HIV-positive persons, Canada
Electrospinning of collagen and an elastin-like polypeptide for vascular graft engineering

Nanofibrous scaffolds were prepared by electrospinning collagen with the elastin-like polypeptide ELP4 to evaluate their suitability for vascular graft applications. Scaffold morphology and electrospinning characteristics were optimized by varying the electrospinning parameters of flow rate and polymer concentration. It was determined that both parameters can be varied to control the average fibre diameter, which ranged from approximately 100 to 900 nm. Attempts to produce highly aligned fibres by spinning onto a rapidly rotating mandrel were unsuccessful.Composite scaffolds consisting of an ELP4 layer and a collagen-ELP4 layer were also electrospun. The materials were crosslinked for different amounts of time in glutaraldehyde vapour and subjected to static mechanical tensile testing. A spectrophotometric assay was used to determine the extent of crosslinking in the materials. Three different modes of failure were identified, although poor reproducibility made it difficult to ascertain the effects of crosslinking time on the tensile properties of the materials.
Applying discrete-event simulation to Orthopaedic Clinics: Case studies and perspectives

Discrete-event simulation is applied to three Orthopaedic Clinics across Ontario to find solutions to long patient wait times. The largest driver of patient wait time was found to be excessive overbooking. Improved patient scheduling rules, such as balancing the patient load across the entire clinic, decreased patient wait time. Using the simulation, the new scheduling algorithm decreased patient cycle time average and standard deviation by 40 minutes or 35%, and 12 minutes or 52%, respectively. Additional recommendations include balancing x-ray patients throughout the day, determining a maximum number of patients that can be seen in a clinic, implementing staggered shifts for staff, scheduling "add-on" patients towards the end of the day and referring non-operative on-call patients to the surgeon with the least patients. A study of hard-coding a minimum schedule and utilizing priority lists for patients beyond the minimum schedule has been initiated from this study.
On approximate min-max theorems for graph connectivity problems

Given an undirected graph G and a subset of vertices S ⊆ V(G), we call the vertices in S the terminal vertices and the vertices in V (G) - S the Steiner vertices. In this thesis, we study two problems whose goals are to achieve high "connectivity" among the terminal vertices. The first problem is the STEINER TREE PACKING problem, where a Steiner tree is a tree that connects the terminal vertices (Steiner vertices are optional). The goal of this problem is to find a largest collection of edge-disjoint Steiner trees. The second problem is the STEINER ROOTED-ORIENTATION problem. In this problem, there is a root vertex r among the terminal vertices. The goal is to find an orientation of all the edges in G so that the Steiner rooted-connectivity is maximized in the resulting directed graph D. The main result of the STEINER TREE PACKING problem is the following approximate min-max relation: If S is 24k-edge-connected in G, then there are k edge-disjoint Steiner trees. This answers Kriesell's conjecture affirmatively up to a constant multiple. We also generalize the above result to the STEINER FOREST PACKING problem. The main result of the STEINER ROOTED-ORIENTATION problem is the following approximate min-max relation: If S is 2k-hyperedge-connected in a hypergraph H, then there is a Steiner rooted k-hyperarc-connected orientation of H. The above result is best possible in terms of the connectivity bound. We shall start this thesis by describing the relations of the problems that we study to the network multicasting problem, which is the starting point of this work.
Designing Web services with Tropos

Web services constitute an important new class of software applications that can be programmatically invoked over the Internet. Fundamental features of web services include loosely coupled, layered, and ever-changing architectures that support user functions for large communities of users. The benefits of adopting web services include software interoperability and easy integration. Not surprisingly, much investment and effort is being drawn to the design and development of such services. In the meanwhile, goal- and agent-oriented design methodologies are getting more attention, as they enhance communication between business and technology worlds. This thesis combines these two techniques and proposes a methodology for designing web services and choreographing these services into business processes. The methodology is based on Tropos [Perini01, Castro02] that supports early and late requirements analysis, as well as architectural and detailed design. An online retailer example is used for illustration of the proposed methodology.
Asynchronous design on FPGA

The objectives have been achieved by designing three commonly used components in digital systems: (1) a self-timed completion-sensing adder, (2) an asynchronous pipelining protocol and (3) an asynchronous FIFO. The primary motivations for my research are: (1) asynchronous systems offer attractive potential advantages over synchronous systems and (2) the FPGA technology is becoming a viable alternative to the ASIC technology. The main objectives are to examine the trade-offs between synchronous and asynchronous systems and identify the difficulties and limitations of asynchronous circuit design on current synchronously-oriented FPGA design tools and architectures. The designs suggest that asynchronous designs on FPGA have some attractive potential advantages but are limited to the synchronously-oriented architecture. In conclusion, both a new asynchronous FPGA architecture and a new design tool with capabilities to understand asynchronous circuits are required in order to fully exploit the advantages of asynchronous circuits.