Childhood emotional maltreatment is associated with damaging consequences, although relatively little is known about the mechanisms underlying its effects. This dissertation investigated the concurrent influences of adult attachment and mindfulness on internalizing symptoms and emotional processing in young adults with and without a history of emotional maltreatment. Study 1 revealed that a sequential mediation model, with adult attachment orientations as first-step mediators and mindfulness as a second-step mediator, fit the data better than a simultaneous mediation model. In addition, moderation analyses revealed that high self-reported levels of mindfulness protected against the development of internalizing symptoms, even in at-risk individuals. Study 2 replicated these findings in a new sample, while also extending the results beyond a self-report outcome, using behavioural measures of emotional processing. Emotional maltreatment, adult attachment, and mindfulness predicted the amount of perceptual information required to correctly identify fearful faces and the amount of interference demonstrated in response to positive and negative emotional words. Cumulatively, these findings suggest that childhood emotional maltreatment can disrupt attachment relationships and encumber the development of mindfulness, contributing to internalizing symptoms and the biased processing of emotional information. However, alternative outcomes are possible, given the presence of high levels of mindfulness and secure attachment representations. This has implications for clarifying developmental theories and evaluating clinical interventions that may mitigate the negative effects of childhood emotional maltreatment.

Initially digital communication was used primarily as a digital advertisement. Digital communication has matured and serves a valuable role for politicians and governments alike, through such campaigns as Calgary Mayor Naheed Nenshi’s 2010 election campaign. Digital communications continue to be used for new means, including sharing information and fundraising, with increased levels of success. The historical challenge of engaging youth aged 18-30 in civic activity and the documented high adoption rates among youth of digital communication tools such as social media, smart phones and Web 2.0 has created opportunities to engage youth by entering their digital environments. The study explores Nenshi’s campaign as a case study, exploring primary and secondary data to assess the ability to engage youth through the implementation of a digital communication strategy.

Le contrôle immunitaire des infections virales est effectué, en grande partie, par les lymphocytes T CD8+ cytotoxiques. Pour y parvenir, les lymphocytes T CD8+ doivent être en mesure de reconnaître les cellules infectées et de les éliminer. Cette reconnaissance des cellules infectées s’effectue par l’interaction du récepteur T (TCR) des lymphocytes T CD8+ et des peptides viraux associés au complexe majeur d’histocompatibilité (CMH) de classe I à la surface des cellules hôtes. Cette interaction constitue l’élément déclencheur permettant l’élimination de la cellule infectée. On comprend donc toute l’importance des mécanismes cellulaires menant à la génération des peptides antigéniques à partir des protéines virales produites au cours d’une infection. La vision traditionnelle de cet apprêtement protéique menant à la présentation d’antigènes par les molécules du CMH propose deux voies cataboliques distinctes. En effet, il est largement admis que les antigènes endogènes sont apprêtés par la voie dite ‘‘classique’’ de présentation antigénique par les CMH de classe I. Cette voie implique la dégradation des antigènes intracellulaires par le protéasome dans le cytoplasme, le transport des peptides résultant de cette dégradation à l’intérieur du réticulum endoplasmique, leur chargement sur les molécules du CMH de classe I et finalement le transport des complexes peptide-CMH à la surface de la cellule où ils pourront activer les lymphocytes T CD8+. Dans la seconde voie impliquant des antigènes exogènes, le dogme veut que ceux-ci soient apprêtés par les protéases du compartiment endovacuolaire. Les peptides ainsi générés sont directement chargés sur les molécules de CMH de classe II à l’intérieur de ce compartiment. Par la suite, des mécanismes de recyclage vésiculaire assurent le transport des complexes peptide-CMH de classe II à la surface de la cellule afin de stimuler les lymphocytes T CD4+. Cependant, cette stricte ségrégation des voies d’apprêtement antigénique a été durement éprouvée par la capacité des cellules présentatrices d’antigènes à effectuer l’apprêtement d’antigènes exogènes et permettre leur présentation sur des molécules de CMH de classe I. De plus, l’identification récente de peptides d’origine intracellulaire associés à des molécules de CMH de classe II a clairement indiqué la présence d’interactions entre les deux voies d’apprêtement antigénique permettant de transgresser le dogme préalablement établi. L’objectif du travail présenté ici était de caractériser les voies d’apprêtement antigénique menant à la présentation d’antigènes viraux par les molécules du CMH de classe I lors d’une infection par le virus de l’Herpès simplex de type I (HSV-1). Dans les résultats rapportés ici, nous décrivons une nouvelle voie d’apprêtement antigénique résultant de la formation d’autophagosomes dans les cellules infectées. Cette nouvelle voie permet le transfert d’antigènes viraux vers un compartiment vacuolaire dégradatif dans la phase tardive de l’infection par le virus HSV-1. Cette mise en branle d’une seconde voie d’apprêtement antigénique permet d’augmenter le niveau de présentation de la glycoprotéine B (gB) virale utilisée comme modèle dans cette étude. De plus, nos résultats décrivent la formation d’une nouvelle forme d’autophagosomes dérivés de l’enveloppe nucléaire en réponse à l’infection par le virus HSV-1. Ces nouveaux autophagosomes permettent le transfert d’antigènes viraux vers un compartiment vacuolaire lytique, action également assurée par les autophagosomes dits classiques. Dans la deuxième partie du travail présenté ici, nous utilisons l’infection par le virus HSV-1 et la production de la gB qui en résulte pour étudier le trafic membranaire permettant le transfert de la gB vers un compartiment vacuolaire dégradatif. Nos résultats mettent en valeur l’importance du réticulum endoplasmique, et des compartiments autophagiques qui en dérivent, dans ces mécanismes de transfert antigénique permettant d’amplifier la présentation antigénique de la protéine virale gB sur des CMH de classe I via une voie vacuolaire. L’ensemble de nos résultats démontrent également une étroite collaboration entre la voie classique de présentation antigénique par les CMH de classe I et la voie vacuolaire soulignant, encore une fois, la présence d’interaction entre les deux voies. / Immune control of viral infections is mainly carried out by cytotoxic CD8+ T lymphocytes. To achieve this, CD8+ T lymphocytes must be able to recognize infected cells and eliminate them. This recognition of infected cells occurs by the interaction of the T cell receptor (TCR) of CD8+ T lymphocytes and viral peptides associated with major histocompatibility complex (MHC) class I on the surface of host cells. This interaction is the key element triggering the elimination of infected cells. This emphasizes the major role of cellular mechanisms leading to the generation of antigenic peptides from viral proteins. The traditional view of antigen presentation by MHC molecules proposes two segregated pathways. Indeed, it is widely accepted that endogenous antigens are processed by the ''classical'' MHC class I presentation pathway. This pathway involves the degradation of intracellular antigens by the proteasome complex in the cytoplasm of the cell, the resulting peptides are then translocated in the endoplasmic reticulum where they are loaded on MHC class I molecules, and finally peptide-MHC complex are exported at the cell surface to activate CD8+ T lymphocytes. In contrast, exogenous antigens internalized by endocytosis or phagocytosis are processed by hydrolases in the lytic endovacuolar compartment and the resulting peptides are loaded on MHC class II molecules. Thereafter, vesicle recycling mechanisms transport the peptide-MHC class II complex on the cell surface where they can stimulate CD4+ T lymphocytes. However, the strict segregation of these two pathways has been revisited to account for the ability of antigen presenting cells to present exogenous antigens on MHC class I molecules by a process called cross-presentation. Moreover, the recent finding that intracellular peptides might also be presented by MHC class II molecules clearly emphasized the presence of interactions between these two antigen processing pathways that transgress the previously established dogma. The objective of the work presented here was to characterize the antigen processing pathways leading to antigen MHC class I presentation during herpes simplex type I (HSV-1) infection. In the results reported here, we describe a new antigen processing pathway resulting from the formation of autophagosomes in HSV-1 infected cells. This new pathway allows the transfer of viral antigens in a lytic vacuolar compartment during the late phase of infection. The development and activation of this second pathway of antigen processing leads to an increased MHC class I presentation of the viral glycoprotein B (gB) used as a model in this study. Moreover, our results describe the establishment of a new form of autophagosomes derived from the nuclear envelope in response to HSV-1 infection. This new form of autophagosomes also contributes to viral antigen transfer to lytic vacuolar compartment in parallel to the action of classical autophagy. Our results also show a close collaboration between the classical MHC class I presentation pathway and vacuolar pathway induced by the formation of autophagosomes, still reinforcing the idea that these two pathways interact together to ensure optimal antigens processing during viral infection. In the second part of the work presented here, we use HSV-1 infection and the resulting viral glycoprotein B to study membrane trafficking allowing the transfer of gB to degradative vacuolar compartments. Our results highlight the role of the endoplasmic reticulum in antigen transfer mechanisms that induce an amplified MHC class I presentation of the viral glycoprotein B.

A recent hypothesis for explaining blue-green eggs in birds suggests that they may be a sexually selected signal of female (and thus nestling) quality that males use to make parental investment decisions. Although this hypothesis has found mixed correlational support in a few species, well-controlled experimental support has been lacking in non-cavity-nesting species with vivid blue eggs. In this study, we isolate the influence of egg colour on male behaviour by replacing natural American robin Turdus migratorius clutches with four artificial eggs (all of the same colour) representing extremes in natural colour intensity. After incubation, three unrelated nestlings were fostered into each experimental nest immediately after the normal incubation period and parental behaviour was monitored when nestlings were 3, 6, and 9 days old. For the youngest nestlings, male provisioning rate significantly increased in the dark egg treatment, but the effect of egg colour disappeared at the older nestling stages. This result remains significant when controlling for variation in female behaviour. Male feeding rate at unmanipulated nests was also significantly related to natural egg colour. These results suggest that blue-green egg colour acts as post-mating signal of female quality in at least some cup-nesting species, but does not exclude the possibility that the blue-green pigment also serves other adaptive purposes. / Thesis (Master, Biology) -- Queen's University, 2009-05-28 13:21:06.941

The fundamental physics governing wildland fire spread are still largely misunderstood. This thesis was motivated by the need to better understand the role of radiative and convective heat transfer in the ignition and spread of wildland fires. The focus of this work incorporated the use of infrared thermographic imaging techniques to investigate fuel particle response from three different heating sources: convective dominated heating from an air torch, radiative dominated heating from a crib fire, and an advancing flame front in a laboratory wind tunnel test. The series of experiments demonstrated the uniqueness and valuable characteristics of infrared thermography to reveal the hidden nature of heat transfer and combustion aspects which are taking place in the condensed phase of wildland fuelbeds. In addition, infrared thermal image-based temperature history and ignition behavior of engineered cardboard fuel elements subjected to convective and radiative heating supported experimental findings that millimeter diameter pine needles cannot be ignited by radiation alone even under long duration fire generated radiant heating. Finally, fuel characterization using infrared thermography provided a better understanding of the condensed phase fuel pyrolysis and heat transfer mechanisms governing the response of wildland fuel particles to an advancing flame front.

No description available.

The workdescribed here was undertaken at the University ofBrighton between 1986 and 2006 in order to assist Computer Science students to acquire practical software development skills, primarily in the areas of real-time systems and object-oriented programming. The contribution to knowledge represented by this work is the development of a set of design principles for educational software, and a variety of software artefacts which demonstrate the applicability ofthese principles. The publications span two decades and describe artefacts covering a number of areas in the curriculum related to software development. They address a range of topics within Computer Science due to the rapidly-evolving nature of the discipline, but they have led to the development of a common philosophy towards the development of educational software, and they each provide an original approach to the topics they address. The success of this philosophy and the originality of the work is evidenced by the fact that they have each been adopted by other educationaf institutions, have been widely praised by students and educators, and have in many cases led to related work by others. This critical appraisal concentrates on describing the evolution of a coherent educational rationale which underpins the various artefacts described here, and on placing this more firmly within the context ofestablished educational theory.

No description available.

Recognition-based graphical passwords are a suggested alternative authentication mechanism which have received substantial attention in research literature. The literature often presents new schemes, usability studies or propose countermeasures for specific attacks. Whilst this is beneficial, it does not allow for consistent comparison of the security of recognition-based graphical password schemes. This thesis contributes a proposed solution to this problem. Presented in this thesis are models for estimating the number of attacks required before success for four aspects of the security of a recognition-based graphical password scheme. This includes two types of guessing attacks and two types of observation attacks. These models combine to provide an overall metric of the security of recognition-based graphical password schemes. Attacks to be incorporated into the metric were established by reviewing the literature and establishing the scope and context. The literature review allowed extraction of the variables of a recognition-based graphical password scheme which represent the scheme. The first aspect examined was that of guessing attacks. The first guessing attack considered was random guessing, the model for this aspect was an adaption of the frequently reported mathematical model. The second guessing attack was a newly proposed attack which prioritised images from more popular semantic categories e.g. animals. The model for this attack was constructed as a further adaption of the random guessing model based on the success rates for the attack which were established by simulations which incorporated user selected images. The observability attacks modelled were shoulder surfing and frequency attacks. The observability attack models were constructed by simulation of the attacks for a wide range of potential configurations of the recognition-based graphical password schemes. A mathematical model was fitted to the resulting data. The final metric combined these models and was evaluated against a list of metric requirements established from relevant literature. The metric results in a consistent, repeatable, and quantitative method for comparing recognition-based graphical password schemes. It can be directly applied to a subset of schemes which allows their security levels to be compared in a way not possible previously. Also presented are details on how the metric could be extended to incorporate other recognition-based graphical password schemes. The approach detailed also allows the possibility of extension to incorporate different attack types and authentication contexts. The metric allows appropriate selection of a recognition-based scheme and contributes to a detailed analysis of the security aspects of recognition-based graphical passwords.

As part of the Greenland Sea Project Woods Hole Oceanographic Institution and Scripps Institute of Oceanography deployed six acoustic tomography transceiver moorings to measure variability of the Greenland Sea gyre through a cooling cycle from September 1988 to August 1989. Using a set of Greenland Sea acoustic tomography data provided by Woods Hole Oceanographic Institution this thesis investigated the importance of incorporating acoustic path changes in the construction of the tomographic inverse solution. A comparison of the inverse solutions for changes in sound speed using non-corrected and corrected acoustic multipaths was conducted. Although the two inverse solutions are qualitatively similar, significant quantitative differences exist. These differences indicate that it is necessary to account for changes in the acoustic multipaths for the generation of accurate Greenland Sea acoustic tomography maps. Acoustic Tomograph, Multipath Variability