Thesis (Ph.D.)--York University, 2006. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 62-71). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19815

This thesis investigated the longitudinal role of defeat and entrapment in populations where these factors were expected to be particularly relevant (a sample of individuals from areas of socioeconomic deprivation and a sample of formal caregivers). The thesis then considered whether defeat and entrapment influenced reward sensitivity on a gambling task and lastly, designed a short scale measuring defeat and entrapment suitable for use in clinical populations. The research incorporated a review of the literature, two longitudinal studies, a behavioural study and the development of a scale. The literature review presented in Chapter 1 provided evidence of a well-established link between defeat, entrapment and poor mental health, suggesting that defeat and entrapment may act as a transdiagnostic process; contributing to the development and maintenance of a range of mental disorders. However, the review also demonstrated that defeat and entrapment relate to the same experiences, suggesting that logically these constructs may equally co-occur, although the structure of the constructs is currently debated. The studies presented in Chapters 3 and 4 demonstrated that perceptions of defeat and entrapment predicted poor mental health (depression and anxiety, and depression and caregiver burden) at a second time point, 12 months later. These chapters presented the first longitudinal evidence for samples recruited from the general population and occupational settings. Furthermore, these chapters provided evidence that the relationship between defeat, entrapment and poor mental health operates in a bidirectional way within a sample recruited from community settings, but a linear way within a sample of formal caregivers, suggesting that further research is needed to confirm the direction of this relationship. The research presented in Chapter 5 found a non-significant relationship between defeat and entrapment and reward sensitivity among a sample of undergraduate students. This may have arisen due to the generally low levels of defeat and entrapment within the sample despite highly varied performance on the task. Replication of this research within a sample where a wider range of defeat and entrapment experiences would be expected might be beneficial. Additionally, this thesis aimed to confirm the factor structure of defeat and entrapment amongst various populations. Exploratory and confirmatory factor analysis demonstrated that defeat and entrapment are best conceptualised as a single psychological construct (Chapters 3 and 6), supporting one-factor theories of defeat and entrapment (e.g. Taylor et al., 2011a). During the course of conducting research for this thesis, it became apparent that the length of existing scales used to measure defeat and entrapment were not suitable for use with clinical populations. Despite evidence that defeat and entrapment may reduce symptoms of mental health problems, their measurement has not yet translated to clinical practice. Although several reasons underlie this, a lack of short measurement tool is a major factor. To address this, an eight-item scale was developed, which demonstrated good psychometric properties across four samples from clinical and non-clinical settings. The current research was supported by a discussion of the clinical implications of the work, specifically identifying how defeat and entrapment could be implemented within therapeutic interventions for mental health problems. The current thesis represents a significant contribution to original research considering defeat and entrapment as predictors of mental health problems. The thesis presents the first longitudinal evidence that defeat and entrapment impact on mental health problems for individuals recruited from community and occupational settings and first application of defeat and entrapment to a behavioural task. Through development of a short scale, the thesis also presents a potential avenue to increase the measurement of defeat and entrapment in clinical settings.

<div>Recent interest in tailoring energetic materials designed to combat biological weapons agents (BWAs) has resulted in significant effort to produce and test these munitions. These energetic materials may contain agent defeat additives that enhance the capability of a munition to destroy BWAs through chemical methods in addition to heat. However, quantifying levels of agent and biocidal species and their interaction is difficult, and efforts have primarily focused on either ex-situ culturing of exposed bioagent simulants or in situ laser absorption measurements. These experiments are valuable for exploring long term agent defeat and line of sight averaged defeat. What these experiments do not provide, however, is in-situ, spatio-temporally resolved imaging in the reaction zone. To address this gap, this work develops the use of in-situ, high speed, two-dimensional optical diagnostics of fireballs and biological weapons agents simulants (BWA-S).</div><div> </div><div> Planar laser induced fluorescence (PLIF) and laser scattering have been conducted in situ. PLIF of both iodine vapor and BWA-S has demonstrated the ability to qualitatively observe species concentration in fireballs. The application of simultaneous techniques provides imaging of multiple parameters, which is invaluable to the further study of BWA-S and agent defeat interactions. These studies also provide the framework for future work in moving towards quantitative measurements, including the development of absorption and fluorescence models.</div>

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Research investigating the role of two evolutionary constructs – perceptions of defeat and entrapment – in various psychological problems and processes has burgeoned over recent years. This meta-analysis quantitatively summarised the findings from 38 studies (11,343 participants) which examined relationships between perceptions of defeat and entrapment and four psychological problems commonly encountered in NHS clinical services: depression, suicidality, anxiety problems and Post-Traumatic Stress Disorder (PTSD). All correlations between defeat and entrapment and the four psychological problems were large by Cohen’s (1988) criterion. Correlations between defeat and entrapment and depression were larger than those for the other psychological problem groups, and significantly larger than those for anxiety problems and PTSD. The magnitude of the observed correlations introduces the possibility that defeat and entrapment, and perhaps other evolutionary constructs, may be integral components or driving forces behind all psychological problems. A robust approach to sensitivity analysis provided confidence that the population effect size estimates are robust and were not severely inflated by unpublished studies not included in the meta-analysis. As there was no significant between-study heterogeneity, moderator analyses were undertaken on an exploratory basis. Findings are generally consistent with theoretical predictions from the Involuntary Defeat Strategy, the theoretical model underpinning the literature. Overall, perceptions of defeat and entrapment appear to be strong risk factors for the four psychological problems examined, perhaps representing transdiagnostic processes that are common across various psychological problems. The potential role of defeat and entrapment in mental health assessment, formulation, intervention and evaluation, is considered in detail and limitations of this meta-analysis and of the literature on which it is based are discussed, highlighting areas of research where future work is needed.

Stress is a major risk factor for substance abuse. Intermittent social defeat stress increases drug self-administration (SA) and elevates brain-derived neurotrophic factor (BDNF) expression in the ventral tegmental area (VTA) in rats. Intra-VTA BDNF overexpression enhances social defeat stress-induced cross-sensitization to psychostimulants and induces nucleus accumbens (NAc) ΔFosB expression. Therefore, increased VTA BDNF may mimic or augment the development of drug abuse-related behavior following social stress. To test this hypothesis, adeno-associated virus (AAV) was infused into the VTA to overexpress either GFP alone (control) or GFP + BDNF. Rats were then either handled or exposed to intermittent social defeat stress before beginning cocaine SA training. The SA acquisition and maintenance phases were followed by testing on a progressive ratio (PR) schedule of cocaine reinforcement, and then during a 12-h access "binge" cocaine SA session. BDNF and ΔFosB were quantified postmortem in regions of the mesocorticolimbic circuitry using immunohistochemistry. Social defeat stress increased cocaine intake on a PR schedule, regardless of virus treatment. While stress alone increased intake during the 12-h binge session, socially-defeated rats that received VTA BDNF overexpression exhibited even greater cocaine intake compared to the GFP-stressed group. However, VTA BDNF overexpression alone did not alter binge intake. BDNF expression in the VTA was also positively correlated with total cocaine intake during binge session. VTA BDNF overexpression increased ΔFosB expression in the NAc, but not in the dorsal striatum. Here we demonstrate that VTA BDNF overexpression increases long-access cocaine intake, but only under stressful conditions. Therefore, enhanced VTA-BDNF expression may be a facilitator for stress-induced increases in drug abuse-related behavior specifically under conditions that capture compulsive-like drug intake.

Cette thèse est l'aboutissement de huit années de travail qui ont portés sur la représentation de la défaite dans le théâtre du dix-septième siècle. Notre corpus comprend 75 pièces, 60 tragédies, 14 tragi-comédies et une comédie-heroïque jouées entre 1634 et 1663 et mettant en avant le thème de la défaite, telle que la définissent les dictionnaires de l'époque, c'est-à-dire la perte d'une bataille après une intervention armée qui peut aller des guerres externes ou internes, internationales, civiles ou religieuses, qui dominent dans les tragédies de la première période étudiée, soit les années 1634-1643, aux complots militaires ou privés qui seront plutôt l'apanage des pièces de la dernière période, soit les années 1653-1663. / This thesis is the outcome of eight working years wich concerned the representation of the defeat in the theater of the seventeenth century. Our corpus includes 75 plays, 60 tragedies, 14 tragicomedies and a heroic comedy played between 1634 and 1663 and putting forward the theme of the defeat, such as defined in the dictionaries of this time, that is the loss of a battle after an armed intervention which can go external or internal, internaltional, civil or religious years 1634-1643, in the military or private plots dominate in the tragedies of the first studied period, or which will be rather the priviledge of the plays of the last period, or the years 1653-1663.

A adolescência é caracterizada como um período de grande estresse na vida humana, sendo o bullying um dos principais estressores desencadeantes de distúrbios psiquiátricos. Modelos animais de depressão usam o estresse social prolongado como indutores de depressão. Utilizamos o modelo de subjugação (ou derrota) social prolongada em camundongos machos adolescentes para estudar a regulação do BDNF neste contexto. Os animais submetidos ao estresse psicossocial apresentaram anedonia no teste de preferência por sacarose e esquiva social no teste de interação social. Explorando a variabilidade comportamental, identificamos grupos suscetíveis e resilientes ao estresse. Animais suscetíveis apresentaram uma redução na expressão do transcrito Bdnf4 e dos níveis proteicos de BDNF total e sua isoforma truncada somente no estriado dorsal, área ainda pouco relacionada à depressão, enquanto que não ocorreram alterações no córtex pré-frontal e hipocampo, áreas comumente afetadas durante a depressão. / Adolescence is characterized by a period of life with great amount of stress, being the bullying one of the main stressors leading to psychiatry disorders. Animal models of depression use prolonged social stress to model depression. We used the prolonged social defeat model in adolescent male mice to study BDNF regulation in this context. Defeated mice showed anhedonia in the sucrose preference test, and social avoidance in the social interaction test. We took advantage of the behavioral outcome variability to identify susceptible and resilient groups to the stress. The susceptible mice showed a reduction in Bdnf4 transcripts, and in total BDNF protein levels, as well as its truncated form in the dorsal striatum, a brain area not much related to depression. However, BDNF gene or protein expression did not differ in the prefrontal cortex and hippocampus, areas commonly associated with depression.

A adolescência é caracterizada como um período de grande estresse na vida humana, sendo o bullying um dos principais estressores desencadeantes de distúrbios psiquiátricos. Modelos animais de depressão usam o estresse social prolongado como indutores de depressão. Utilizamos o modelo de subjugação (ou derrota) social prolongada em camundongos machos adolescentes para estudar a regulação do BDNF neste contexto. Os animais submetidos ao estresse psicossocial apresentaram anedonia no teste de preferência por sacarose e esquiva social no teste de interação social. Explorando a variabilidade comportamental, identificamos grupos suscetíveis e resilientes ao estresse. Animais suscetíveis apresentaram uma redução na expressão do transcrito Bdnf4 e dos níveis proteicos de BDNF total e sua isoforma truncada somente no estriado dorsal, área ainda pouco relacionada à depressão, enquanto que não ocorreram alterações no córtex pré-frontal e hipocampo, áreas comumente afetadas durante a depressão. / Adolescence is characterized by a period of life with great amount of stress, being the bullying one of the main stressors leading to psychiatry disorders. Animal models of depression use prolonged social stress to model depression. We used the prolonged social defeat model in adolescent male mice to study BDNF regulation in this context. Defeated mice showed anhedonia in the sucrose preference test, and social avoidance in the social interaction test. We took advantage of the behavioral outcome variability to identify susceptible and resilient groups to the stress. The susceptible mice showed a reduction in Bdnf4 transcripts, and in total BDNF protein levels, as well as its truncated form in the dorsal striatum, a brain area not much related to depression. However, BDNF gene or protein expression did not differ in the prefrontal cortex and hippocampus, areas commonly associated with depression.