McGill University Thèses et mémoires publiés en 2004

The term "sensor-less" in power electronic drives refers to measurement of mechanical shaft position and/or speed from the currents and voltages of the electrical machine. This thesis presents innovative sensor-less means (a Slip Frequency Phase Lock Loop (PLL) and a gamma-delta Axes Aligner) for implementing decoupled P-Q control of a doubly-fed induction generator (DFIG) for wind-turbine application. Proofs of concepts are by digital simulations. The accuracy of the Slip Frequency Phase Lock Loop in speed estimation is evaluated; the origin of a shortcoming (small phase lag) located and compensated for. The Slip Frequency Phase Lock Loop (PLL) and a gamma-delta …  Read more

The cesarean delivery rate in Canada has never been higher than it is now. To identify the contribution of pre-pregnancy adiposity and maternal weight gain to the risk of cesarean delivery, and evaluate to what extent these factors may account for temporal trends in primary cesarean delivery, we conducted an historical hospital-based cohort study of 63 390 deliveries at Montreal's Royal Victoria Hospital from 1978 to 2001. Pregravid adiposity and high net rate of gestational weight gain were associated with primary intrapartum cesarean delivery, and overweight and obese women with a previous cesarean were at higher risk for failing a …  Read more

Ligand I- along with nonionic surfactant, Triton X-100 or anionic surfactant, sodium dodecyl sulfate (SDS) were applied as soil washing agents to desorb Cd from both naturally and artificially contaminated soils. After seven consecutive washings, up to 90% of Cd was desorbed from both soils. Triton X-100 with I- showed a higher capacity to desorbing Cd than did SDS with I-. The increase of ligand concentration was a critical factor for increasing leaching capacity. Without the ligand, surfactant alone could not desorb Cd effectively from either soil. After seven consecutive washings, a sequential extraction experiment was performed for soil residuals …  Read more

The manipulation of nature using modern biotechnology has resulted in the creation of Genetically Modified (GM) foods. There are states already enacting laws requiring the mandatory labeling of GM foods so that consumers can make informed choices as to what food to eat. However, on the flip side, the mandatory labeling of GM foods can also constitute non-tariff barriers as it can impose burdens on states that export GM foods. How should these two interests be balanced? This thesis takes the ambitious challenge of exploring whether the mandatory labeling of GM foods enacted under the government's protection of the consumers' …  Read more

The classical theory of poroelasticity developed by Biot (1941) deals with the time-dependent response of the fluid-saturated porous media derived from the coupling of the mechanical deformations and the deformations of pore fluid. The classical theory of poroelasticity has been successfully applied to a range of problems of interest to geomechanics and biomechanics. The brittle poroelastic media can experience alterations in poroelasticity properties resulting from the generation and/or growth of micro-defects. The effects can be modelled by appeal to continuum damage mechanics. Damage-induced alterations can influence the consolidation behaviour of a damage-susceptible poroelastic medium. Continuum damage mechanics concepts can be …  Read more

Autism, in the manner of any chronic infantile disease, profoundly disturbs family life, generating a search for meaning. This qualitative study aims to explore the construction of interpretative models of the illness by Haitian parents of autistic children, living in Montreal. The results suggest that the majority of parents question the cause of their child's affliction and develop an assortment of meanings around this disease, allowing them to contain the feeling of absurdity that overwhelms them when confronted with their child's limitations. In spite of the fact that their experience is deep-rooted in a modern occidental world, the parents more …  Read more

The expanding use of distributed multi-processor supercomputers has made a significant impact on the speed and complexity of the problems which can be solved by the finite element (FE) method. Moreover, the use of the standard Message Passing Interface (MPI) protocol has facilitated the portability of parallel applications across a wide variety of parallel architectures. The conjugate gradient method plays an important role in solving discretized partial differential equations resulting from FE methods. In this thesis, the scalability and performance analysis of three versions of the conjugate gradient parallel solver are executed on the Sun symmetric multiprocessor system with 4 …  Read more

In the new millennium, over 500 million rechargeable battery operated and miniaturized pieces of electronic equipment will be in circulation. A battery market survey showed that the average annual growth rate of Li-ion batteries will increase by 118%. The millions of spent Li-ion batteries will cause an environmental waste management problem. The cathode metals, which have a high market value (54 US$/kg cobalt) will leach into the earth when land filled. A transferred arc process was proposed in which the Li-ion battery waste would be separated into volatile, slag and metal phases using argon as the plasma gas. A thermodynamic …  Read more

This thesis addresses the problem of automatically constructing a visual representation of an unknown environment that is useful for robotic navigation, localization and exploration. There are two main contributions. First, the concept of the visual map is developed, a representation of the visual structure of the environment, and a framework for learning this structure is provided. Second, methods for automatically constructing a visual map are presented for the case when limited information is available about the position of the camera during data collection. The core concept of this thesis is that of the visual map, which models a set of …  Read more

Eukaryotic gene regulation by members of the nuclear receptor superfamily is crucial for a vast array of cellular and physiological processes including development, differentiation, proliferation and homeostasis. Regulation of the transcriptional activity of nuclear receptors occurs through the exchange of corepressor and coactivator complexes in a ligand-dependent manner. However, this may not be the case for orphan nuclear receptors, including RORalpha. Instead, RORalpha orphan nuclear receptor activity is modulated by Ca 2+/calmodulin-dependent protein kinase IV (CAMKIV), through a yet undetermined mechanism, and RORalpha itself regulates the expression of genes involved in the calcium signaling pathway. In this study, we report …  Read more

This study reviews the policy and practice of Islamic social welfare efforts in Indonesia. Findings from this study suggest that Indonesian Islamic welfare policies are ambivalent. The ambivalent character is due, in part, to the need of the government to maintain the status of Indonesia as a secular state, while at the same time, to accommodate Muslim aspirations to practice Islamic social welfare. Some Islamic welfare organizations have succeeded in combining Islamic social welfare programs with a modern social development perspective that is relevant to large national development programs. Dompet Dhuafa Republika's (DD) experience of collecting Islamic welfare funds and …  Read more

The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)2 in a sulphate system at various temperatures and pHs. Solubility tests were performed by dissolving crystalline Ni(OH)2 at constant pH and temperature for various test conditions. These results were then utilised to design alternative precipitation strategies with the objective of producing clean and easily filterable nickel hydroxide. Homogeneous Ni(OH)2 precipitation was performed using NaOH solution and MgO slurry at various temperatures and pHs in pure and impure aqueous systems. Ni(OH)2 was also produced by using controlled supersaturation technique in order to improve product quality. …  Read more

A microwave assisted methodology was developed to modify Merrifield resins (1-2% cross-linked containing 1.0-3.5 mmol Cl-/g) with different nominal molecular weights PEG (200-1000). The synthesis was also carried out by conventional heating to assess the differences between the two procedures. The most efficient synthesis was achieved by using microwave and by using PEG with molecular weight 200 and MR 2% crosslinked containing 1.25 mmol Cl -/g. The structural elucidation was carried out using Fourier transform infrared (FTIR) spectroscopy and elemental analyses. Upon pyrolsis-GC/MS analysis of the PEGylated MR, the PEG showed the tendency to undergo thermal degradation by the loss …  Read more

Dewi Z. Phillips maintains that philosophy must have a contemplative character. Applied to religion, it takes the form of a hermeneutics of contemplation that emphasizes the role concepts play in human life. While some philosophers try to bring philosophy to bear on to religion, others try to bring religion to bear on to philosophy; seeing their task as being for or against religion. According to Phillips, both these views are confused. Instead, the philosophy of religion must strive to understand religion on its own terms: showing that a sensibility should be possible that does justice to both belief and atheism. …  Read more

The acyl-CoA reductase, LuxC, isolated from Photobacterium phosphoreum , has been found to have a low sequence identity to aldehyde dehydrogenases, particularly in the more conserved regions (i.e. motifs) containing the active site residues. Mutational studies on residues involved in cofactor binding and in catalysis conserved in both the LuxC enzyme and in Vibrio harveyi aldehyde dehydrogenase have shown that these residues may play similar roles as the effects of mutation on the kinetic parameters of the two enzymes were found to be very similar. Moreover, preliminary X-ray structural characterization of LuxC shows that its overall structure and fold is …  Read more

A Monsanto Automatic Capillary Rheometer and a sliding plate rheometer were used to study the spurt phenomenon and to discover whether it is the result of a system instability or a material property. The capillary rheometer has been the only instrument able to operate at spurt stresses up to present time, because capillary rheometers operate at shear stresses that are out of the range of rotational shear rheometers. However, a sliding plate rheometer can generate shear stresses in the spurt range. A comparative study using two linear polybutadiene samples at 50°C was carried out using these two rheometers. Special attention …  Read more

Living biological cells are highly complex, multifunctional systems whose physical attributes are relatively unknown. Critical functions involving plasticity of cell morphology, connectivity and response to stimuli are proposed to be fundamentally related to the micromechanical character and the ability of the cell to exert directed mechanical signaling. Unique abilities of atomic force microscopy in measuring cellular viscoelastic properties (on length scales from nanometers to microns) are explored with specific applications to (1) airway smooth muscle cells and (2) hippocampal neurons. Surface indentation techniques for stiffness mapping, as well as quantitative measurements of frequency-dependent complex rheology are featured. Structural and molecular …  Read more

Bell, Graham (Supervisor)  Read more

Despite its ubiquity in planetary science, analogue-based reasoning largely has remained unbounded by guidelines of use. Establishing analogical guidelines and putting them to the test is the main aim of the thesis. Towards this end, I discuss the philosophical foundations of analogical reasoning in planetary geomorphology and posit rules of use that facilitate the evaluation of analogical hypotheses. Subsequently, I present four hypotheses concerning aeolian, fluvial and periglacial processes on Mars. Each of these hypotheses is evaluated in terms of the analogical rules presented. The fourth hypothesis is original to this thesis and suggests that a periglacial landscape comprising pingos …  Read more

Optical delay line module is an important building block for advanced communication systems such as OCDMA and OTDMA. The past decade has seen a large research and development activity in this area. In this thesis, design and performance analysis of a tunable optical delay line which employs pop-up MEMS micro-mirrors have been described. The delay paths which their lengths are in binary fashion are free-space based delay lines. Micro-mirrors operate as a switch to redirect the light through delay paths. One of the main characteristic of this design is to provide constant optical power loss for different delay times. Computer …  Read more

Asparagus (Asparagus officinalis) is a perennial crop well suited to grow in Quebec. Despite high demand for this crop, asparagus production is declining because of asparagus root rot disease that is caused by Fusarium spp. Phosphorus is one of the most important nutrients for the production of healthy asparagus roots that may resist infection by Fusarium. The objective of this study was to determine the effects of phosphorus (P) applications on asparagus yield and soil microbial parameters. Plots receiving 0 to 200% of the P recommendation, based on the Centre de reference en agriculture et agroalimentaire du Quebec (CRAAQ) guidelines, …  Read more

Hindu religious culture has a rich and long-standing performance tradition containing many genres and regional types that contribute significantly to an understanding of the living vitality of the religion. Because the field of religious studies has focused on texts, the assumption exists that these are primary, and performances based on them are mere enactments and therefore derivative. This thesis will challenge this common assumption by arguing that performances themselves can be constitutive events in which religious worldviews, social histories, and group and personal identities are created or re-negotiated. In this work, I examine the history of performance cultures (understood both …  Read more

Drawing upon a review of literature and interviews with four artist-teachers, this thesis explores the implications of post-modernism on the studio teaching of painting. Additional emphasis is placed on uncovering the issue of the-death-of-painting and its links to post-modernism, and my own reflexivity as a painter and a teacher of art. The thesis presents also an attempt to respond to an apparent lack of educational research that addresses post-secondary studio teaching of art, and that engages artist-teachers in reflection on their teaching philosophies. The overall objective of this thesis is to generate a body of knowledge that could be of …  Read more

Gray-Donald, Katherine (Supervisor)  Read more

This thesis introduces a development platform especially tailored to Bioinformatics research and software development. Bias (Bioinformatics Integrated Application Software) provides the tools necessary for carrying out integrative Bioinformatics research. It follows an object-relational strategy for providing persistent objects, allows third-party tools to be easily incorporated within the system, and it supports standards and data-exchange protocols common to Bioinformatics. It is not enough to present the architecture of Bias without showing a working example for which exploits all composites of Bias, thus demonstrating the utility of Bias. We present the architecture of Bias and provide a full example based on the …  Read more

The agricultural domain is faced with the challenge of increasing amounts of collected data, multiple sources of external information and various summary reports, all tending to exist in a non-structured fashion. The formats and locations of these various data sources almost certainly differ, but profitable decision-making often depends on using and interpreting all of these inputs accurately. Based on the hypothesis that the interpretation of dairy-herd data can be aided using interactive visualization, the main goal of this research was to improve the understanding of the data-interpretation process, using such techniques, and by taking full advantage of them in the …  Read more

Porous metals are often used in orthopaedic load-bearing applications because they promote and direct bone ingrowth while maintaining their mechanical integrity for long periods in physiological environments. However, the influence of microstructural parameters of three-dimensional metallic scaffolds on osteogenic cell response must be studied to improve their design. This study aims to study the biocompatibility and osteoconductivity of novel titanium foams with three pore sizes in vitro and to gain knowledge on the mechanisms by which bone is formed within three-dimensional structures. This is achieved through studies of the cell viability of macrophages and adhesion kinetics, proliferation, differentiation, and mineralization …  Read more

This dissertation describes a novel method for quantifying venous cerebral blood volume (CBVv) changes accompanying normal functional activation and employs quantitative functional magnetic resonance imaging (fMRI) methods to study the hemodynamic and metabolic changes accompanying neuronal inhibition. An in vivo occipital lobe relaxometry study was performed first to investigate the dependence of the spin-spin relaxation time constant of tissue, T2tissue , on the refocusing interval over the range of interest and thus test the basis of the proposed CBVv method. The small decrease of the apparent T2tissue with refocusing interval elongation is consistent with blood being the only significant source …  Read more

This study concerns the multicultural influences which shaped the architectural form and artistic decoration of the Synagogue at Dura-Europos, an ancient city located on the west bank of the upper Euphrates in Syria (244/5 C. E.) Preserving the Jewish tradition after the destruction of the Second Temple, in a location remote from Palestine, was essential in order to maintain a strong identity in the small Jewish community of Dura, engulfed by pagan and multitheistic societies. Biblical narratives were used by the Jewish community to assert their history. In chapter 1, there appears a discussion of what scholars have said about …  Read more

Stress activates dopamine (DA) transmission in the basolateral amygdala (BLA), medial prefrontal cortex (mPFC) and nucleus accumbens (NAc), and DA transmission in these regions mediates different aspects of the behavioural response to stress. Evidence indicates that a functional interdependence exists between the DA projections to these areas. mPFC DA exerts an inhibitory influence on stress-induced NAc DA release. Similarly, BLA DA modulates mPFC and NAc DA function, although it is unknown if this is also the case in response to stress. Thus, we examined whether BLA DA modulates NAc and mPFC DA release in response to stress. We first determined …  Read more

In normal cells, the p53 tumour suppressor induces cell cycle arrest or apoptosis in response to a variety of stresses, including DNA damage and ectopic oncogene expression. However, cellular pathways controlled by p53 are compromised in virtually all cancers. Defining the mechanisms regulating p53 activity in normal and tumour cells has therefore been a major priority in cell biology and cancer research. In this study, we characterized two important regulatory mechanims of p53 activity: (i) Human papillomavirus (HPV) E6 interaction and (ii) alternative splicing. Recognized as the major etiological agents for cervical cancer, the oncogenic potential of HPVs correlates with …  Read more

Interactions between diffusing impurity atoms and dislocations can occur during or following the deformation of metals. These interactions cause dislocation pinning, leading to strain aging. At lower temperatures (<400°C), the relevant solutes are interstitial (in particular, carbon and nitrogen). At higher temperatures (>800°C), substitutional impurities are expected to be most influential. The same mechanisms that result in the yield drops, increased flow stresses and increased work hardening associated with strain aging at low temperatures should result in significant modification of recovery and recrystallization behaviour at higher temperatures. The present work involves the deformation of austenitic (304) stainless steel at high …  Read more

The purpose of this research was first, to identify why males sexually abused as children under-report their experiences of child sexual abuse. Secondly, the disclosure experiences of males sexually abused as children were examined and analyzed, with a particular emphasis placed on exploring the links between low disclosure rates, gender role socialization, and homophobia. Qualitative data were gathered during semi-structured interviews of men sexually abused during childhood. Issues and themes arising during interviews were generally consistent with those identified in the literature. However, the sample size was small and additional research---employing larger samples---should be completed in order to collect further …  Read more

AI planning benefits greatly from the use of temporally-extended or macro-actions. Macro-actions allow for faster and more efficient planning as well as the reuse of knowledge from previous solutions. In recent years, a significant amount of research has been devoted to incorporating macro-actions in learned controllers, particularly in the context of Reinforcement Learning. One general approach is the use of options (temporally-extended actions) in Reinforcement Learning [22]. While the properties of options are well understood, it is not clear how to find new options automatically. In this thesis we propose two new algorithms for discovering options and compare them to …  Read more

Consumer concerns in food purchasing contain a number of elements, including food safety, environment, animal welfare, and other socially related issues. The purpose of this study was to examine consumer perceptions of the potential benefits of products that are produced using an environmental management system (EMS) in agriculture, and identify those factors that influence choice. The choice modeling technique uses consumer preferences to estimate Montrealers' willingness to pay (WTP) for production practices that decrease the impacts on the environment, as well as for other potential benefits of EMS production. Results indicate that consumers are willing to pay a price premium …  Read more

A combined ultra-high vacuum scanning tunneling microscope, atomic force microscope, and field ion microscope UHV (STM/AFM/FIM) system was used to study mechanical and electronic interactions at the atomic scale. A surface science system, consisting of an Auger electron spectrometer, UHV evaporators, ion sputter gun and annealing capabilities, was designed and constructed. A new force sensor preparation method was developed suitable for high stability imaging. Using this improved system, we studied W tip- Au(111) sample interactions in the regimes from weak coupling to strong interaction and simultaneously measured current changes from pA to muA. Close correlation between conductance and interaction forces …  Read more

In this dissertation, the phonetic production and perception abilities of simultaneous bilinguals exposed to both Canadian English (CE) and French (CF) from birth were tested to determine whether their abilities in the two languages are best described as autonomous or interdependent. For this purpose, the similarities and differences in production and perception of coronal stops, /d/ and /t/, in CE and CF by monolinguals and simultaneous bilinguals were investigated in three studies. Coronal stops in CE and CF are thought to differ subtly in place of articulation; CE coronal stops are transcribed as having an alveolar place of articulation whereas …  Read more

Until now, historians have devoted relatively little attention to the rich field of patients' struggles with chronic progressive disease. This study proposes to begin to fill this lacuna by examining in detail the meaning and implications of one central principle of nineteenth-century clinical medicine: incurability. Though the judgement of incurability is the product of a medical encounter, its significance extended well beyond the clinic. For being incurable in nineteenth-century France was a social event in the broadest sense, putting the individual at the centre of a complex web of people with different expectations and duties. Patients and their farnilies sought …  Read more

Thalassemia is a blood disorder requiring lifelong transfusions for survival. Erythrocytes accumulate toxic iron at their membranes, triggering an oxidative cascade that leads to their premature destruction. We hypothesized that removing this proximate iron compartment as a primary treatment using novel iron chelators, could prevent hastened red cell removal and clinically alleviate the need for transfusion. Novel, highly cell permeable iron chelators, pyridoxal isonicotinoyl hydrazone (PIH) and pyridoxal ortho-chlorobenzoyl hydrazone (o-108) were compared to the present mainstay, desferrioxamine (DFO) and deferiprone (L1), in vitro and in vivo . Treatment of human model beta-thalassemic erythrocytes with chelators resulted in significant depletion …  Read more

Human telomerase is a ribonucleoprotein complex, minimally composed of a catalytic subunit, hTERT and an RNA component, hTR that contains the template used to synthesize telomere DNA. Telomerase is present in over 80% of all cancer cells. Therefore, an understanding of telomerase regulation is important for cancer research. This thesis work was focused upon the study of telomerase regulation by telomerase associated proteins and alternatively spliced hTERT mRNA variants. Tandem affinity purification (TAP) and immunopurifications with anti-hTERT antibody were used to visualize potential telomerase associated proteins. No specific proteins were identified in TAP-hTERT transfected cells. hTERT was purified from 293 …  Read more

The flow produced by a rotating propeller is inherently unsteady and three-dimensional. Conventional design of propellers uses blade-element theory but becomes inaccurate in capturing three-dimensional vortical and compressible effects at the tips, as well as the effect on downstream bodies. A propeller is always attached to a fixed component that affects its performance, thus the need arises to couple a fixed domain to a rotating domain in an unsteady aerodynamic simulation. A finite element formulation for the simulation of propellers is presented in terms of the Reynolds-averaged Navier-Stokes equations for unsteady, three-dimensional, viscous, compressible flows. The first step consists of …  Read more

Cette etude se base sur la supposition que la globalisation est une des forces majeures qui influencent la reforme de l'enseignement superieur en Jordanie. Les changements dus a la globalisation sont d'une telle magnitude qu'ils ont un impact a travers presque tous les niveaux du systeme d'enseignement superieur. Le cadre conceptuel de cette recherche se base sur une approche methodologique qualitative guidee par le paradigme socio-contructivist en utilisant une etude de cas. Le but est d'articuler une methode d'enquete basee sur les notions post-modernes qui pronent qu'il existe plus d'une seule interpretation juste de la realite. Cette etude tente d'identifier …  Read more

On 18 June 2002, the anomalous X-ray pulsar 1E 2259+586 underwent a major X-ray outburst that lasted several hours and consequently linked AXPs to the class of magnetar-candidates known as soft gamma repeaters (SGRs). Three days after the outburst, observations with the Gemini Observatory showed a near-infrared flux enhancement, presumably associated with the X-ray activity. We have since performed a ~1.5 year monitoring program of the Ks band (2.5 mum) photometry, and find that the flux decreased continually, reaching its pre-burst level after about one year. Comparing both the near-IR flux increase and subsequent decay to those of the X-ray …  Read more

Several methods can be used in cluster-randomized studies with binary outcome, including GLMM, GEE, and ordinary logistic regression. In this thesis, we study cluster-randomized data with large cluster sizes relative to the number of clusters (for example, the PROBIT study). We compared GLMM, GEE, and ordinary logistic regression approaches in terms of parameter interpretation, magnitude, and standard errors of model parameters. A simulation study was performed to evaluate the performance of these methods. GLMM implemented with penalized quasi-likelihood performed well. It gave the highest empirical confidence interval coverage of the true coefficients at 95% level of confidence. GEE was robust …  Read more

This research project aimed at the development of a PECVD process for the deposition of C60-PPPE (plasma polymerized polyethylene) NC thin films. A continuous throughput PECVD system was designed for the co-deposition of a polymer matrix and C60 particles, in effect, yielding composite thin films on 1" quartz and silicon substrates. In this process, the C 60 molecules are sublimated from their solid powder form, transported to the plasma chamber, pre-coated in-flight before being dispersed and co-deposited in the polymeric matrix. The plasma polymerization of ethane in the low pressure, radio frequency (RF) plasma was studied with a mapping of …  Read more

The market life of many fruits and vegetables can be extended through storage at low temperatures. Chilling injury (CI) is a major postharvest storage problem for tropical commodities. Storing these products at temperatures below their critical temperature may result in severe physiological disorders known as CI symptoms. Mangoes (Mangifera indica. L) are susceptible to CI when stored below 12 °C. Visual CI symptoms include uneven ripening, surface pitting, discoloration, shriveling and scalding. Research has been conducted to overcome these serious problems using various postharvest treatments such as hot water, methyl jasmonate (MJ) or diphenylamine (DPA) with some reduction of the …  Read more

The prevalence of obesity in the paediatric population is on the increase and there is speculation that suboptimal breastfeeding patterns may be contributing to the present obesity epidemic. We described the prevalence and trends in underweight and overweight among 3 052 school aged children over a ten year period, and patterns of exclusive and any infant breastfeeding among 671 mothers over a 6 year period on Montserrat a small British colony which forms part of the chain of Caribbean islands, and experienced the eruption of the Soufriere Hills volcano in July 1995. The results revealed for 11 year old children …  Read more

The use of chemically modified oligonucleotides (AON) to selectively inhibit the expression of genes involved in pathological processes, offers a rational approach for the prevention and treatment of some disorders. Phosphorothioate oligonucleotides (PS-DNA), in which one of the non-bridging oxygen atoms of the internucleotide linkage is replaced by a sulfur atom, have been extensively studied and are among the most widely used "antisense" oligonucleotides (AON). However, the isomeric analogue, in which one of the two bridging oxygen atom is replaced by sulfur has not been extensively investigated, as such, this prompted our interest towards the construction of oligonucleotides containing the …  Read more

Virus infection represents an intracellular invasion of host cells for the sole purpose of multiplication. Successful virus replication requires entry into tropic cells, usurping of the cellular machinery, and the production of progeny virions to initiate further rounds of infection. Establishment of the antiviral state in response to virus begins at the site of infection and requires the initiation of a preexisting signaling network designed to inhibit virus replication and aid in the establishment of this coordinated immune response. Integral components of this network include the IRF-3 and IRF-7 transcription factors that play essential roles in the cellular response to …  Read more

The effect of the molecular weight distribution of both the soluble and the insoluble blocks on the solution self-assembly of the amphiphilic block copolymer polystyrene-block-poly(acrylic acid) was studied. Copolymers of a variety of block lengths but with narrow molecular weight distributions were synthesized by sequential anionic synthesis. Mixing two or more copolymers of differing block length (while the second block length was identical) artificially increased the polydispersity index (PDI) of one block. Self-assembly was induced by adding water slowly to a copolymer solution until a desired solvent composition was attained. The resulting aggregates were compared using transmission electron microscopy and …  Read more