McGill University Thèses et mémoires publiés en 2005

Fried, Gerald (Supervisor)  Read more

The objective of the thesis was to investigate the effects of nonionic surfactants on the dissolution and biodegradation of polycyclic aromatics hydrocarbons (PAHs) from a multicomponent non-aqueous phase liquids (NAPLs). The extent of solubilization of the PAHs in the surfactant micelles increased linearly with the PAH mole fraction in the NAPL. The micelle-water equilibrium partition coefficient of both PAHs was found to increase with the size of the polar shell region of the micelle rather than the hydrophobic core of the micelle and the presence of PAHs in the shell region of the micelles was confirmed by 1H-NMR analysis. Competitive …  Read more

The mass flow event resulting from the 1996 flood in the Saguenay region buried the mercury-contaminated indigenous sediments at the head of the Saguenay Fjord under up to 50 cm of postglacial deltaic sediments. This study investigated whether this deposit served as an efficient geochemical barrier to the remobilization of mercury and its availability to the benthic organisms. The vertical distributions of total mercury and methyl mercury (MeHg) in the sediments and pore waters were measured in box cores recovered at three stations along the main axis of the Saguenay Fjord and in the Baie des Ha!Ha!, in successive years …  Read more

Under the Treaty Establishing the European Community, corporations are entitled to free establishment. Recently, the European Court of Justice's Inspire Art decision has clarified its scope and has in principle introduced place of incorporation doctrine as choice-of-law rule, thus granting corporations free choice of the Member State of incorporation. In the US, free choice has caused the "Delaware Effect". This paper analyzes if Inspire Art will cause a similar development in the EU. The EU and US contexts will be compared. Germany will serve as an example. As different circumstances exist in the EU, free choice is more limited and …  Read more

Cardiovascular disease (CVD) is North America's leading killer for both men and women among all racial and ethnic groups. Almost 1 million North Americans die of CVD each year, which adds up to 42% of all deaths. Numerous investigations point out that normal blood flow (hemodynamics) is essential to good health and many studies found that there is a relationship between the genesis and the progression of CVD with the locally irregular blood flow occurring in the diseased zones. The study of hemodynamics in the cardiovascular system is therefore key to the understanding of CVD; its genesis and progression. The …  Read more

Testicular cancer (TC) is the most common cancer affecting men of reproductive age; however treatment with bleomycin, etoposide, and cis-platin (BEP) results in extremely high cure rates. The post-treatment quality of life of TC patients is therefore a major concern. The goal of this study was to determine the effects of BEP on sperm count, motility, and morphology in an animal model. Male Sprague Dawley rats were treated with BEP for 9 weeks. Rats were killed, and the numbers, motility, and morphology of the spermatozoa from the epididymides were analyzed. After BEP treatment, sperm counts decreased by almost 10-fold when …  Read more

The near-field flow structure of the tip vortex generated by a NACA 0015 wing oscillating though the attached-flow, light-stall and deep-stall regimes was investigated at Rec = 1.86 x 105. Particular emphasis was placed on the effects of oscillation frequency and mean incidence upon the spatial and temporal evolution of the unsteady vortex structure. Phase-locked, ensemble-averaged cross-flow and axial velocity fields, vorticity distributions, and turbulence structures over a full cycle of oscillation were compared to static wing-tip vortex results, and the dynamic effects upon the vortex strength, size, trajectory and associated induced drag were examined. Through the attached-flow and light-stall …  Read more

This thesis is a study of two major figures among the royal Safavid women in the sixteenth century, with a special focus on their political activities and style of leadership. I examine the socio-political careers of Pari Khan Khanum (955-985/1548-1578) and Mahd-i 'Ulya (d.987/1579) in connection with family and dynastic politics as well as the power struggle and factionalism among the qizilbash tribes. A detailed analysis of these powerful female political figures of the Safavid court leads one to conclude that first, royal women faced particularly complex social and personal restrictions, but nonetheless some managed - through their privileged status …  Read more

In Num. 21: 4-9, after complaining against God, the Israelites were punished with a plague of venomous serpents. Following their apology, God commanded Moses to fashion a bronze serpent and mount it on a standard; the bitten were to look at it to recover. The use of the serpent form is striking, as it seems to boldly negate the fundamental Torah law, which prohibits the use of any images or statues. To gain better insight into the narrative, the first section of this work explores a possible context for it, based on archaeological findings. The second section focuses on the …  Read more

From the association of the epsilon4 allele of apolipoprotein (apo) E with Alzheimer's disease (AD) to the more recent reports of reduced risks of developing the disease when taking cholesterol lowering agents, links seem to point for a central role for lipoprotein metabolism in the AD brain. While the association with apoE4 is the strongest and most reproduced risk factor for AD, roles for other proteins involved in lipoprotein metabolism in the periphery have not been thoroughly investigated. Using the entorhinal cortex lesion (ECL) paradigm in human apoE-targeted replacement mice we examine whether apoE4 has effects on reactive synaptogenesis in …  Read more

The courtship behavior of the brown garden snail, Cantareus aspersus , includes a bizarre component where one snail attempts to pierce its mating partner with a sharp, calcareous dart that is covered with mucus. In vitro, the mucus causes conformational changes to the reproductive tract causing sperm to be stored rather than digested. In addition, successful dart shooters have an increased relative paternity compared to unsuccessful shooters. I have tested whether this increased paternity is caused by the mucus delivered on the dart or by the mechanical action of the dart. Mating trials were conducted using dartless and glandless snails, …  Read more

A case study of collaborative storyboarding in an animation studio grounded this investigation of visual discourse---discourse about and with visual displays. The focus was on a problem occurring during a 40-minute task between the head storyboard artist and his junior colleague in reviewing a rough, conceptual storyboard. The research investigated the role of different semiotic modalities produced by the artists', i.e., speech, gesture, and drawing, in mediating spatial (frames of reference) and motion (action and path) representations and inferences from the storyboard. One aim was to determine if particular modalities were used to represent particular spatial and motion ideas. Both …  Read more

Students with learning disabilities (LD) have been found to exhibit social difficulties compared to those without LD (Wong, 2004). Recognition, expression, and understanding of facial expressions of emotions have been shown to be important for social functioning (Custrini & Feldman, 1989; Philippot & Feldman, 1990). LD subtypes have been studied (Rourke, 1999) and children with nonverbal learning disabilities (NVLD) have been observed to be worse at recognizing facial expressions compared to children with verbal learning disabilities (VLD), no learning disability (NLD; Dimitrovsky, Spector, Levy-Shiff, & Vakil, 1998; Dimitrovsky, Spector, & Levy-Shiff, 2000), and those with psychiatric difficulties without LD controls …  Read more

This thesis reports the results of an investigation of scorodite long-term solubility and stability conducted at fixed pH (5-9) and temperature (22°C, 50°C and 75°C). The decomposition of scorodite at 22°C was found to be extremely slow. At neutral pH, the arsenic concentration stabilized at 5.8 mg/L. As scorodite dissolved, the iron reprecipitated as 2-line ferrihydrite. The growth and re-crystallization of ferrihydrite was delayed by apparent arsenate adsorption. The solubility product of scorodite was calculated as 10-25.5. The dissolution rate of scorodite in a pure system was modeled with a decreasing exponential equation. The pre-exponential factor approached first order vis-a-vis …  Read more

Athletes wear mouthguards to decrease the risk of injuries. However, many athletes resist wearing mouthguards due to problems with speech and breathing during play. Breathing difficulties may suggest limitations with ventilation. The purpose of this study was to examine peak inspiratory and peak expiratory air flow at different ventilatory rates using various types of mouthguards and a no mouthguard condition. Mouthguards were fitted into a dental model and air was ventilated through the model at three flow rates (30, 45, 60 strokes·min-1) using 2 and 3 L syringes. Flows were recorded using a Medisoft Ergocard. Peak flows (L·s -1) were …  Read more

Earthships are buildings which are constructed almost entirely of recycled materials and are built to be almost totally self sufficient through the recycling of rain water, the recycling of solar energy into electrical energy, passive solar techniques and sometimes the recycling of wind through turbines, also into electrical energy. This thesis draws out and demonstrates the logic that Earthship architecture emerges from and generates amongst its inhabitants. This logic, it is argued, can be characterized as containing elements of the baroque and Neo-baroque. It is a logic of following and interfacing the elements (earth, sun, wind, rain) that folds them …  Read more

Stretch reflex excitability was measured during quiet standing by using a bilateral electro-hydraulic actuator to apply perturbations of angular position to the ankle. Subjects were instructed to stand quietly while pulse displacements were applied at random times. Position, torque, gastrocnemius-soleus EMG, tibialis anterior EMG, heel position, tibia angle, femur angle, and sacrum angle were measured. Background torque and reflex excitability varied substantially from trial to trial---reflex torque decreased as the background torque level increased; while reflex EMG increased when background torque increased. This behavior is consistent with previous findings in prone subjects. Reflex torque for a given activation level was …  Read more

The main goal of this research was to explore the use of benchmarking in the dairy industry. This includes descriptions of the various sectors in North America where benchmarking has been used successfully on a continuous basis or in research. Benchmarking methods that are currently used in the Quebec dairy industry are examined. An improvement to such methods is proposed through the use of visualization, coupled with interactivity, and with a focus on adaptability and usage. The advantages of such an interactive tool are discussed in light of on-farm decision-making, and a further use of visual slider applications is described …  Read more

MEIS1 (myeloid ecotropic viral integration site 1) is a member of the TALE class of homeodomain-containing proteins. MEIS1, along with related family members PBX and PREP1, bind DNA cooperatively with HOX proteins to regulate transcription. Meis1 is implicated in many developmental processes. Moreover, deregulation of Meis1 is involved in leukemogenesis. To better understand the mechanisms of Meis1 transcriptional regulation, we set out to map and characterize the Meis1 promoter. Results from RNase protection and 5' RACE suggest that Meis1 has multiple transcription start sites (TSSs) located between -608 and -751 base pairs upstream of the translational start site. Sequence analysis …  Read more

Radioligand to receptor binding assessed with Positron Emission Tomography (PET) can be used to investigate dopamine (DA) concentration in vivo . The present dissertation focuses on the use of the PET DA D 2/3 receptor ligand [11C]raclopride to study DA release following the administration of drugs of abuse: amphetamine and alcohol. A number of experimental animal paradigms have indicated that DA transmission is generally potently engaged by the acute administration of addictive drugs (Di Chiara and Imperato 1988; Weiss, Markou et al. 1992), deficient during drug withdrawal (Markou and Koob 1991; Schulteis, Markou et al. 1995; Epping-Jordan, Watkins et al. …  Read more

Arginine methylation is a post-translational modification occurring in higher eukaryotes that results in the addition of one or two methyl group on the nitrogen in the side chain of arginines. The enzymes responsible for protein arginine methylation have been classified in three groups. Type I enzymes promote the formation of both NG-monomethylated and asymmetric o-NG,NG-dimethylated arginines (aDMA). Type II enzymes catalyze the formation of monomethylated and symmetrical o-N G,N'G-dimethylated arginines (sDMA). The type III enzyme found in yeast catalyzes the monomethylation of the delta-guanidino nitrogen atom of the arginine residue. Although some abundant proteins have been described as being substrates …  Read more

The capability to perform dexterous operations in an autonomous manner would greatly enhance the productivity of space robotic operations. In the present thesis, we address this problem and propose a new methodology for vision-guided automatic grasping using SARAH, a three-fingered robotic hand. The Canadian Space Agency is planning to install SARAH on the International Space Station and we developed a methodology allowing this robotic hand to grasp objects autonomously by using a vision system in combination with an off-line grasp planner. More specifically, a new algorithm for synthesizing force-closure grasps for planar and revolute objects with SARAH is formulated. The …  Read more

Globalization has had two major implications for national merger control regimes: national competition authorities are called more and more to examine transactions with cross-border dimensions and secondly, domestic business practices may be scrutinized by foreign nations. In light of this, divergent substantive standards have become a source of international friction, notably between the two most mature merger control regimes, the European Union and the United States. Facing this new reality, it has become clear that some sort of international arrangement will be needed in order to reduce the inefficiencies created by multijurisdictional review. Various proposals have been made, ranging from …  Read more

Polymer/clay nanocomposites are materials composed of a polymer matrix and nanometer size clay particles. They exhibit significant improvements in tensile modulus and strength, reduced permeability to gases and liquids, compared to the pure polymer. These property improvements can be realized while retaining clarity of the polymer without a significant increase in density (typical clay loading is 2--5%). The aim of this research was to achieve maximum exfoliation of the clay and property enhancement in the nanocomposite by melt processing. The components of the Hansen solubility parameters and the Hamaker constants of the constituents were used to establish the compatibility between …  Read more

This study examined traditional instruction and problem-based learning (PBL) approaches to teaching and the extent to which they foster the development of desirable cognitive processes, including metacognition, critical thinking, physical intuition, and problem solving among undergraduate physics students. The study also examined students' approaches to learning and their perceived role as physics students. The research took place in the context of advanced courses of electromagnetism at a Canadian research university. The cognitive science, expertise, physics and science education, instructional psychology, and discourse processes literature provided the framework and background to conceptualize and structure this study. A within-stage mixed-model design was …  Read more

We examine the following traffic model. There is a network of users who wish to route traffic to their destinations as quickly as possible. Each edge in the network has a load-dependent function specifying the delay experienced by traffic using that network link. In an optimal routing scheme the total latency incurred by all the network users is minimized. However, when users are free to route traffic according to their own interests the network traffic converges to a selfishly defined traffic assignment which can be more costly than the optimal solution. The following question then arises; how much deterioration in …  Read more

The use of steel frame/wood panel shear walls as a seismic force resisting system (SFRS) in residential and/or commercial buildings is expected to increase in the future. At the moment, in Canada, however, no specific guidelines in line with the seismic provisions of the National Building Code of Canada (NBCC) exist with which the engineer can design a building consisting of these shear walls. An extensive research program has therefore been undertaken at McGill University to develop a design method through the testing of different configurations of steel frame/wood panel shear walls loaded with monotonic and reversed cyclic protocols. A …  Read more

Research has shown that children attending immersion programs reach a native-like level in comprehension and in reading by the end of elementary level. However, in writing and speaking, they rarely achieve target-like proficiency. Some conditions seem to favor the production of output. This study presents an investigation of children's ability to notice errors in their French second language in immersion program in Montreal. The study was conducted with forty-three (43) children aged 8-9, and aimed to gather information related to the following research questions: Can we train 8 year-old second language learners to: (a) notice their errors; (b) self-correct (given …  Read more

The thesis describes a program of research that investigated the over-riding hypothesis that a clear cultural identity is associated with positive personal and collective self-esteem, and positive personal well-being. The testing of this novel hypothesis required first and foremost that a reliable measure of cultural identity generally, and the clarity of a person's cultural identity in particular, be developed. To meet this goal Study 1 introduced an innovative method in a story-telling form, the "Cultural Narrative". The Cultural Narrative method is built on McAdams' (1996, 2001) Life Story Model for assessing personal identity. In order to verify its generalizability, this …  Read more

Chu, Vincent H. (Supervisor)  Read more

Proteins are known to be post-translationally modified. This thesis will discuss arginine methylation, one of the many post-translational modifications that occur within the cell. The enzymes that catalyze this post-translational modification are called arginine methyltransferases. The three main types of methylated arginines include monomethylated arginine (MMA), asymmetric dimethylated arginine (aDMA) and symmetric dimethylated arginines (sDMA). Type I arginine methyltransferases catalyze the formation of MMA and aDMA; Type II enzyme catalyze the formation of MMA and sDMA. Protein arginine methylation has been implicated in the regulation of many different cellular processes, including transcription, cellular localization, protein-protein interaction and signal transduction. The …  Read more

Anatomically, the visual system of non-human primates shows a complicated pattern of cortico-cortical connectivity. The behavioural relevance of many of these connections is unclear, as is the similarity of connectivity with that in the human brain. We used transcranial magnetic stimulation (TMS) and psychophysics to investigate connectivity among visual areas involved in (1) modulating visual perception during saccadic eye movements and (2) perceiving visual motion. Our first study demonstrated that phosphenes induced by TMS of visual cortex are perceived as more intense shortly after the onset of a saccade. This indicates that the cortical areas responsible for saccade generation are …  Read more

In this thesis, we present an approach to finding a procedural representation of a texture to replicate a given texture image which we call image-based procedural texture matching. Procedural representations are frequently used for many aspects of computer generated imagery, however, the ability to use procedural textures is limited by the difficulty inherent in finding a suitable procedural representation to match a desired texture. More importantly, the process of determining an appropriate set of parameters necessary to approximate the sample texture is a difficult task for a graphic artist. The textural characteristics of many real world objects change over time, …  Read more

This thesis is a product of our collaboration with the National Research Council of Canada's astronomy laboratory (Dominion Radio Astrophysical Observatory) to study the control of a new radio-telescope design: the Canadian Large Adaptive Reflector. The first part consists in an identification of a parabolic reflector's direct and inverse kinematics. This reflector is made of multiple triangular sections, each of them supported by hydraulic actuators from the ground. Kinematics resulted in the creation of a trajectory generator to issue commands to the actuators. Second part consists in direct modeling and model identification of a tethered aerostat system, in order to …  Read more

This thesis compares two contemporary artists who practice institutional criticism, Marcel Broodthaers and Fred Wilson. Looking specifically at Broodthaers's fictional museum project the Musee d Art Moderne, Departement des Aigles from 1968-1972 and Wilson's 1992 installation Mining the Museum at the Maryland Historical Society, this thesis will critically analyze each artist's similar application of deconstruction as a method. Both artists employ allegory and history as aesthetic strategies of deconstruction; using allegorical structure, the artists mobilize objects that have been arrested in history, disrupting a historical continuum that would otherwise remain foreclosed. The focus of this study will be to explore …  Read more

Viruses are among the ultimate conquerors. Even the exploits of Genghis Khan and Alexander the Great seem pale when compared to viral feats. To give but one example, over the last 50 years, the human immunodeficiency virus (HIV) has swept across six continents, now claiming several million lives yearly. Despite sustained intense research efforts, there is still no treatment to eradicate HIV infection. For billions of years, viruses evolved strategies to enter and take control of organisms to generate progeny viruses. Eukaryotic cell viruses developed various means of hijacking the cellular protein synthesis machinery. Understanding these mechanisms opens a unique …  Read more

Let Kw(t) := inf∥P∥ 22≤t 01 |1 - P(theta)|2w(theta) dtheta, where w ≥ 0 is a decreasing function and P ∈ L2([0,1], Leb.). Then we have Kw ≤ Kv ↔01 1wq +l dtheta ≥ 01 1vq+l dtheta ∀ lambda ≥ 0. We present two similar proofs of this result, which are analogous to the well-known majorization theorem: Let v, w ≥ 0 be decreasing functions, and suppose 01 w(theta)dtheta = 01 v(theta)dtheta. Then Fw ≤ Fv ↔01 (w(theta) - x)+ dtheta ≥ 01 (v(theta) - x)+ dtheta ∀ x ≥ 0, where F w(t) = t1 w(theta)dtheta. Since our proofs …  Read more

The importance of developing relevant ovarian cancer models led us to test the applicability of a system comprised of epithelial ovarian cancer cell lines. The high frequency of loss of heterozygosity (LOH) and rearrangements of chromosome 17 in ovarian tumors provide evidence of a role of chromosome 17 genes in ovarian tumorigenesis. Oligonucleotide microarray expression analysis was applied to assess the expression profiles of 864 probe sets that map to chromosome 17. The TOV112D ovarian cancer cell line, a spontaneously immortalized and tumorigenic ovarian cancer cell line derived from an endometrioid histopathological subtype, which has been shown to exhibit LOH …  Read more

In Latin America, women's ability to participate in the paid workforce on equal terms as men is constrained by many cultural and political obstacles, and this reinforces women's unequal citizenship status. Even though unions have rarely supported women's rights historically, and are currently losing political power in the neoliberal economic context, I argue that union women have a crucial role to play in the social struggle to expand women's labor rights. Building on theories about the social construction of citizenship, I develop an original theoretical framework suggesting that civil society acts on three levels to expand citizenship rights: the individual …  Read more

The 45kDa isoform of TC-PTP is a ubiquitous, predominantly nuclear protein. Reports demonstrate that it can exist outside the nucleus; however, immunofluorescence and cellular fractionation techniques point to an almost exclusive residence in the nucleus, and even within the nucleolus. Though the conditions of nucleolar enrichment appear to be serum-dependent, and may involve S52 phosphorylation, the exact circumstances necessary for this localization remain unknown, though TC-PTP C216S mutant, and not an S52A/C216S double mutant had the ability to trap a phosphorylated substrate of ~105kDa, thus encouraging further research into the identity of this phosphoprotein. There is also data implicating TC-PTP …  Read more

Lower members of the glyme family CH3-(-O-CH2-CH2-)n O-CH3 are refractory to the usual biological and physicochemical treatments, do not get retained on biofilters and are hardly sorbed to activated sludge or carbon. An alternate form of elimination is hence to be devised. TiO 2 particles have been utilized in the photocatalytic degradation of organic compounds often found in contaminated waste streams. When they are exposed to UV light, an electron is excited from the TiO2 valence band into the conduction band. The photogenerated electron vacancy ("hole") can initiate the oxidation of the organic, while the photogenerated electron must be removed …  Read more

Neointima formation is the major limitation to the use of percutaneous transluminal coronary angioplasty in the treatment of coronary artery disease. It is caused by the proliferation and migration of vascular smooth muscle cells (SMCs) from the media into the intima resulting in narrowing of the luminal diameter. The ELN -/- mouse exhibits a similar phenotype in which overproliferation of SMCs into the lumen leads to obstruction of the aorta causing death at post-natal day 2.5. Based on this observation, a DNA microarray analysis of the ELN -/- aorta was conducted to identify candidate genes responsible for SMC proliferation and …  Read more

Apoptosis is a genetically programmed form of cell death that plays an essential role in the tissue homeostasis and development of multicellular organisms. Apoptotic cellular suicide is tightly regulated by both pro-apoptotic and anti-apoptotic proteins. The dysregulation of apoptosis manifests in a number of pathologies, such as cancer, autoimmunity and neurodegenerative disorders. Thus further insight into these mechanisms may provide a basis for therapeutic opportunities. The primary executioners of cell death belong to a family of cysteine proteases known as caspases that cleave numerous substrates resulting in the morphological characteristics of apoptosis. Caspase8 is the apical caspase involved in death …  Read more

The primary focus of the present thesis is the exploration of factors that influence the dopamine (DA) neuron by examining the expression of the dopamine transporter (DAT), a marker of the DA neuron. The secondary focus of this thesis is on the serotonin neuron and in particular the serotonin transporter (SERT), a marker of the serotonin neuron. To this end three distinct and separate models have been employed. The goals of this thesis were: (1) to test the hypothesis that monoamine oxidase inhibition during development alters serotonergic innervation in the cortex and raphe, while not affecting relative DA innervation of …  Read more

This thesis examines the role of the Manichean dualism, the pervasive colour symbolism of white as good and black as evil. It looks at the manifestation of this symbolism in representations of Christianity, and the subsequent implications for race and racism in Western society. Through images of Jesus Christ and the Virgin Mary, I posit that the Western conflation of holiness with whiteness is a primary means through which whiteness retains hegemony. I argue that Renaissance painting has had a pivotal role in privileging the white body through its hyper-whitening of both Jesus and Mary. Both figures emerge as improbable …  Read more

Canadian artist Helen McNicoll (1879-1915) has long been neglected in art historical scholarship. Although well-known and well-regarded during her lifetime, her work has since been marginalized as feminine and dismissed as old-fashioned. Through the lens of a modernist art historical tradition that has privileged the urban and masculine above all else, McNicoll's Impressionist depictions of sunlit beaches, open fields, and rural women at work may indeed seem quaintly nostalgic. In this thesis, I argue that these images can and should be seen as both representations of modernity and assertions of feminist thought. McNicoll travelled throughout England and Europe, and across …  Read more

In the wake of September 11th and following an overemphasis on passenger air travel security, the air cargo system potentially has become the primary target for terrorists. States have undertaken various regulatory approaches that involve technology and operational measures aimed at addressing the perceived security threats in the air cargo industry. This thesis presents both an overview of the potential risks and best security practices identified within several international, regional and national initiatives, including the "authorized economic operator" and "secure supply chain" mechanisms. The main challenge in designing an adequate security system appears to be ensuring that security improvements are …  Read more

The Zen (Ch'an) poets Han-shan (circa 6th-9 thC.) and Ryokan (1758-1831) participate in literary activity, reclusion, and ordinary emotions in a manner that questions their typical image as models of transcendence. They participate in literary activity without attachment to either linguistic adequacy or a dualistic notion of "beyond words," and poetry serves as their mode of communication from reclusion. Reclusion is a context to realize the nature of the conventional world rather than a means of transcendence to an ultimate realm and is significant as a social and political act. Interpreted through the functional model of language, the poets' expressions …  Read more

Two research problems involving the class of discrete-time signals bounded in magnitude are addressed in this thesis. The first problem concerns robust stability of systems with repeated, structured, linear time-varying, and induced-ℓinfinity-norm bounded perturbations. The second problem consists in the design of an ℓ₁-optimal controller that allows for flexible management of the tradeoff between the ability of a system to attenuate disturbance signals versus its expected worst peak-to-peak amplification. Original solutions to both problems are provided and their efficiency is assessed with examples and applications.  Read more

My PhD work focuses on the study of the layer-specific targeting of photoreceptor (R-cell) axons in the developing Drosophila visual system. More specifically, I have studied the roles of two molecules, the receptor tyrosine kinase Off-track (Otk) and the transmembrane protein Semaphorin1a (Sema1a) in R-cell axon guidance and target selection. The Drosophila adult visual system is comprised of the compound eye and the optic lobe. The compound eye is comprised of ~800 ommatidia, each containing eight different R-cells. As the visual system develops, R-cells project axons through the optic stalk toward two different layers of the optic lobe. R1-6 axons …  Read more