Nonsuicidal Self-Injury and Suicidal Risk: An Examination among Young Adults

Nonsuicidal self-injury (NSSI), which refers to the direct and deliberate destruction of bodily tissue in the absence of suicidal intent, is a serious and widespread mental health concern. Although NSSI has been differentiated from suicidal behavior on the basis of non-lethal intent, research has shown that these two behaviors commonly co-occur. Despite increased research on the link between NSSI and suicidal behavior, however, little attention has been given as to why these two behaviors are associated. My doctoral dissertation specifically addressed this gap in the literature by examining the link between NSSI and several measures of suicidal risk (e.g., suicidal ideation, suicidal attempts, pain tolerance) among a large sample of young adults. The primary goal of my doctoral research was to identify individuals who engaged in NSSI at risk for suicidal ideation and attempts, in an effort to elucidate the processes through which psychosocial risk, NSSI, and suicidal risk may be associated. Participants were drawn from a larger sample of 1153 undergraduate students (70.3% female) at a mid-sized Canadian University. In study one, I examined whether increases in psychosocial risk and suicidal ideation were associated with changes in NSSI engagement over a one year period. Analyses revealed that beginners, relapsed injurers, and persistent injurers were differentiated from recovered injurers and desisters by increases in psychsocial risk and suicidal ideation over time. In study two, I examined whether several NSSI characteristics (e.g., frequency, number of methods) were associated with suicidal risk using latent class analysis. Three subgroups of individuals were identified: 1) an infrequent NSSI/not high risk for suicidal behavior group, 2) a frequent NSSI/not high risk for suicidal behavior group, and 3) a frequent NSSI/high risk for suicidal behavior group. Follow-up analyses indicated that individuals in the frequent NSSI/high risk for suicidal behavior group met the clinical cutoff score for high suicidal risk and reported significantly greater levels of suicidal ideation, attempts, and risk for future suicidal behavior as compared to the other two classes. Class 3 was also differentiated by higher levels of psychosocial risk (e.g., depressive symptoms, social anxiety) relative to the other two classes, as well as a comparison group of non-injuring young adults. Finally, in study three, I examined whether NSSI was associated with pain tolerance in a lab-based task, as tolerance to pain has been shown to be a strong predictor of suicidal risk. Individuals who engaged in NSSI to regulate the need to self-punish, tolerated pain longer than individuals who engaged in NSSI but not to self-punish and a non-injuring comparison group. My findings offer new insight into the associations among psychosocial risk, NSSI, and suicidal risk, and can serve to inform intervention efforts aimed at individuals at high risk for suicidal behavior. More specifically, my findings provide clinicians with several NSSI-specific risk factors (e.g., frequent self-injury, self-injuring alone, self-injuring to self-punish) that may serve as important markers of suicidal risk among individuals engaging in NSSI.

Étude comparative des trajectoires criminelles des contrevenants sous responsabilité provinciale au Québec, selon le sexe

Contexte et objectifs. La carrière criminelle est un sujet d’intérêt criminologique depuis plus de 80 ans. Les travaux sur cette question ont permis de mieux comprendre l’évolution des personnes contrevenantes et leurs crimes au fil du temps. Bien que beaucoup d’efforts aient été déployés pour étudier les hommes, les recherches portant sur les trajectoires criminelles des femmes demeurent relativement rares, ceci étant notamment attribuable à la petite taille des échantillons. L’objectif de ce mémoire est de réaliser une étude comparative de la carrière criminelle d’hommes et de femmes de 18 à 47 ans relevant de la juridiction de la province de Québec. Méthodologie. L’échantillon est composé de 3320 délinquants sous responsabilité provinciale, soit 216 femmes (6,5 %) et 3104 hommes (93,5 %). Des statistiques descriptives seront réalisées afin de dresser un portrait de la clientèle et une approche par variable latente catégorielle sera utilisée pour modéliser les parcours criminels. Plus précisément, cette analyse permet d’estimer des sous-groupes de délinquants au sein de la population qui suivent des courbes de croissance distinctes. La proportion d’individus appartenant à chacun de ces sous-groupes peut donc être estimée. Résultats. Les analyses indiquent que les femmes ont une fréquence de délits commis plus faible que les hommes, et ce, particulièrement au début de leur carrière criminelle. En effet, la différence quant à la fréquence tend à s’atténuer avec le temps, pour disparaître vers 40 ans. Également, il apparaît que les hommes et les femmes suivent un nombre de trajectoires criminelles similaires; cependant, la prévalence chez ces dernières apparaît relativement différente. En effet, il ressort que les femmes commencent plus tardivement leur carrière criminelle que les hommes, avec une proportion plus importante pour les crimes contre les biens. Finalement, les antécédents juvéniles influent sur la chronicité et la persistance, quel que soit le genre ou le type de crime. Conclusion. Les résultats démontrent que la différence selon le sexe est un sujet d’intérêt criminologique primordial puisque les femmes présentent des risques différents quant à la fréquence et au type de crime. Qui plus est, ces dernières semblent commencer leur carrière criminelle plus tardivement que les hommes.

Une typologie tridimensionnelle des pratiques de consommation d’alcool au Canada : usages, contextes et motivations de boire

Cette thèse de doctorat a pour objectif de développer une typologie socioculturelle de la consommation d’alcool à partir des mesures d’usages, de contextes et de motivations à boire pour approfondir notre connaissance sur les pratiques collectives de boire au Canada et d’explorer la variabilité des pratiques selon les caractérisations sociodémographiques et socioéconomiques des buveurs . Partant du constat des limites conceptuelles des modèles typologiques développés en alcoologie qui ne permettent pas d’observer toute la complexité des pratiques du boire dans une société puisqu’ils sont construits principalement à partir de l’usage, cette thèse propose de conceptualiser les pratiques de boire comme l’interface de l’usage, des contextes de consommation et des motivations à consommer. Les données utilisées proviennent de l’enquête GENder, Alcohol, and Culture: an international study – Canada. Uniquement les buveurs réguliers (consommant au moins une fois par mois) ont été retenus dans le cadre de cette thèse. Des analyses de correspondances et des analyses de classes latentes ont permis de dériver des typologies tridimensionnelles des pratiques de boire et de les associer à des caractéristiques sociales. Les résultats de recherche sont présentés en trois articles scientifiques qui répondent chacun à un objectif spécifique de la thèse. Le premier article présente une classification des buveurs réguliers canadiens en six grands types et établit le lien entre ces types et le genre ainsi que le groupe d’âge. Le deuxième article teste l’invariance de la typologie selon le genre et propose des classifications distinctes pour les femmes et pour les hommes en lien avec le groupe d’âge et le niveau d’éducation. Le troisième article se concentre sur les buveurs réguliers en emploi et examine l’association entre la position socioprofessionnelle dans la hiérarchie sociale et les pratiques de boire.

La sexualité des agresseurs sexuels de femmes : sont-ils tous obsédés par le sexe?

Une revue des modèles explicatifs de l’agression sexuelle (développementaux, typologiques, processus de passage à l’acte) permet de mettre en évidence la place centrale occupée par la déviance et l’hypersexualité dans les études portant sur les agresseurs sexuels. L’étude présentée dans ce mémoire investigue la sexualité des agresseurs sexuels de femmes adultes extrafamiliaux sous ses facettes déviantes et non-déviantes afin d’évaluer l’hétérogénéité des styles de vie sexuelle des violeurs. Les caractéristiques psychosexuelles et délictuelles de 160 violeurs incarcérés au Québec (Canada) ont été investiguées. Une analyse de classe latente, suivie d’une analyse factorielle, ont permis d’identifier trois styles de vie sexuelle distincts : le Déviant Internalisé (DI), le Sans Problèmes Sexuels (SPS), et l’Hypersexuel Déviant (HD). Les résultats suggèrent que les DI sont caractérisées par une insatisfaction sexuelle, la déviance sexuelle, ainsi que par la pauvreté de leur vie sexuelle. Les SPS sont caractérisés par une absence de déviance sexuelle et d’hypersexualité. Leurs distorsions cognitives, plutôt que leur style de vie sexuelle, semblent favoriser leur passage à l’acte. Finalement, les agresseurs HD sont caractérisés par l’hypersexualité, de même que par leur déviance sexuelle, lesquels favorisent leurs comportements sexuellement coercitifs. Les implications cliniques et théoriques seront discutées.

Scene Classification Using a Hybrid Generative/Discriminative Approach

We investigate whether dimensionality reduction using a latent generative model is beneficial for the task of weakly supervised scene classification. In detail, we are given a set of labeled images of scenes (for example, coast, forest, city, river, etc.), and our objective is to classify a new image into one of these categories. Our approach consists of first discovering latent ";topics"; using probabilistic Latent Semantic Analysis (pLSA), a generative model from the statistical text literature here applied to a bag of visual words representation for each image, and subsequently, training a multiway classifier on the topic distribution vector for each image. We compare this approach to that of representing each image by a bag of visual words vector directly and training a multiway classifier on these vectors. To this end, we introduce a novel vocabulary using dense color SIFT descriptors and then investigate the classification performance under changes in the size of the visual vocabulary, the number of latent topics learned, and the type of discriminative classifier used (k-nearest neighbor or SVM). We achieve superior classification performance to recent publications that have used a bag of visual word representation, in all cases, using the authors' own data sets and testing protocols. We also investigate the gain in adding spatial information. We show applications to image retrieval with relevance feedback and to scene classification in videos

Análisis del gen adra2a receptor alfa 2a adrenergico en pacientes con trastorno de hiperactividad y déficit de atención

El trastorno de hiperactividad y déficit de atención (THDA), es definido clínicamente como una alteración en el comportamiento, caracterizada por inatención, hiperactividad e impulsividad. Estos aspectos son clasificados en tres subtipos, que son: Inatento, hiperactivo impulsivo y mixto. Clínicamente se describe un espectro amplio que incluye desordenes académicos, trastornos de aprendizaje, déficit cognitivo, trastornos de conducta, personalidad antisocial, pobres relaciones interpersonales y aumento de la ansiedad, que pueden continuar hasta la adultez. A nivel global se ha estimado una prevalencia entre el 1% y el 22%, con amplias variaciones, dadas por la edad, procedencia y características sociales. En Colombia, se han realizado estudios en Bogotá y Antioquia, que han permitido establecer una prevalencia del 5% y 15%, respectivamente. La causa específica no ha sido totalmente esclarecida, sin embargo se ha calculado una heredabilidad cercana al 80% en algunas poblaciones, demostrando el papel fundamental de la genética en la etiología de la enfermedad. Los factores genéticos involucrados se relacionan con cambios neuroquímicos de los sistemas dopaminérgicos, serotoninérgicos y noradrenérgicos, particularmente en los sistemas frontales subcorticales, corteza cerebral prefrontal, en las regiones ventral, medial, dorsolateral y la porción anterior del cíngulo. Basados en los datos de estudios previos que sugieren una herencia poligénica multifactorial, se han realizado esfuerzos continuos en la búsqueda de genes candidatos, a través de diferentes estrategias. Particularmente los receptores Alfa 2 adrenérgicos, se encuentran en la corteza cerebral, cumpliendo funciones de asociación, memoria y es el sitio de acción de fármacos utilizados comúnmente en el tratamiento de este trastorno, siendo esta la principal evidencia de la asociación de este receptor con el desarrollo del THDA. Hasta la fecha se han descrito más de 80 polimorfismos en el gen (ADRA2A), algunos de los cuales se han asociado con la entidad. Sin embargo, los resultados son controversiales y varían según la metodología diagnóstica empleada y la población estudiada, antecedentes y comorbilidades. Este trabajo pretende establecer si las variaciones en la secuencia codificante del gen ADRA2A, podrían relacionarse con el fenotipo del Trastorno de Hiperactividad y el Déficit de Atención.

Image classification for a large number of object categories

L'increment de bases de dades que cada vegada contenen imatges més difícils i amb un nombre més elevat de categories, està forçant el desenvolupament de tècniques de representació d'imatges que siguin discriminatives quan es vol treballar amb múltiples classes i d'algorismes que siguin eficients en l'aprenentatge i classificació. Aquesta tesi explora el problema de classificar les imatges segons l'objecte que contenen quan es disposa d'un gran nombre de categories. Primerament s'investiga com un sistema híbrid format per un model generatiu i un model discriminatiu pot beneficiar la tasca de classificació d'imatges on el nivell d'anotació humà sigui mínim. Per aquesta tasca introduïm un nou vocabulari utilitzant una representació densa de descriptors color-SIFT, i desprès s'investiga com els diferents paràmetres afecten la classificació final. Tot seguit es proposa un mètode par tal d'incorporar informació espacial amb el sistema híbrid, mostrant que la informació de context es de gran ajuda per la classificació d'imatges. Desprès introduïm un nou descriptor de forma que representa la imatge segons la seva forma local i la seva forma espacial, tot junt amb un kernel que incorpora aquesta informació espacial en forma piramidal. La forma es representada per un vector compacte obtenint un descriptor molt adequat per ésser utilitzat amb algorismes d'aprenentatge amb kernels. Els experiments realitzats postren que aquesta informació de forma te uns resultats semblants (i a vegades millors) als descriptors basats en aparença. També s'investiga com diferents característiques es poden combinar per ésser utilitzades en la classificació d'imatges i es mostra com el descriptor de forma proposat juntament amb un descriptor d'aparença millora substancialment la classificació. Finalment es descriu un algoritme que detecta les regions d'interès automàticament durant l'entrenament i la classificació. Això proporciona un mètode per inhibir el fons de la imatge i afegeix invariança a la posició dels objectes dins les imatges. S'ensenya que la forma i l'aparença sobre aquesta regió d'interès i utilitzant els classificadors random forests millora la classificació i el temps computacional. Es comparen els postres resultats amb resultats de la literatura utilitzant les mateixes bases de dades que els autors Aixa com els mateixos protocols d'aprenentatge i classificació. Es veu com totes les innovacions introduïdes incrementen la classificació final de les imatges.

Pesticides, preference heterogeneity and environmental taxes

In this paper we present results from two choice experiments (CE), designed to take account of the different negative externalities associated with pesticide use in agricultural production. For cereal production, the most probable impact of pesticide use is a reduction in environmental quality. For fruit and vegetable production, the negative externality is on consumer health. Using latent class models we find evidence of the presence of preference heterogeneity in addition to reasonably high willingness to pay (WTP) estimates for a reduction in the use of pesticides for both environmental quality and consumer health. To place our WTP estimates in a policy context we convert them into an equivalent pesticide tax by type of externality. Our tax estimates suggest that pesticide taxes based on the primary externality resulting from a particular mode of agricultural production are a credible policy option that warrants further consideration.

On the response of the Antarctic Circumpolar Current transport to climate change in coupled climate models

The CMIP3 (IPCC AR4) models show a consistent intensification and poleward shift of the westerly winds over the Southern Ocean during the 21st century. However, the responses of the Antarctic Circumpolar Currents (ACC) show great diversity in these models, with many even showing reductions in transport. To obtain some understanding of diverse responses in the ACC transport, we investigate both external atmospheric and internal oceanic processes that control the ACC transport responses in these models. While the strengthened westerlies act to increase the tilt of isopycnal surfaces and hence the ACC transport through Ekman pumping effects, the associated changes in buoyancy forcing generally tend to reduce the surface meridional density gradient. The steepening of isopycnal surfaces induced by increased wind forcing leads to enhanced (parameterized) eddy-induced transports that act to reduce the isopycnal slopes. There is also considerable narrowing of the ACC that tends to reduce the ACC transport, caused mainly by the poleward shifts of the subtropical gyres and to a lesser extent by the equatorward expansions of the subpolar gyres in some models. If the combined effect of these retarding processes is larger than that of enhanced Ekman pumping, the ACC transport will be reduced. In addition, the effect of Ekman pumping on the ACC is reduced in weakly stratified models. These findings give insight into the reliability of IPCC-class model predictions of the Southern Ocean circulation, and into the observed decadal-scale steady ACC transport.

The structure of paranoia in the general population

Background: Psychotic phenomena appear to form a continuum with normal experience and beliefs, and may build on common emotional interpersonal concerns. Aims: We tested predictions that paranoid ideation is exponentially distributed and hierarchically arranged in the general population, and that persecutory ideas build on more common cognitions of mistrust, interpersonal sensitivity and ideas of reference. Method: Items were chosen from the Structured Clinical Interview for DSM-IV Axis II Disorders (SCID-II) questionnaire and the Psychosis Screening Questionnaire in the second British National Survey of Psychiatric Morbidity (n = 8580), to test a putative hierarchy of paranoid development using confirmatory factor analysis, latent class analysis and factor mixture modelling analysis. Results: Different types of paranoid ideation ranged in frequency from less than 2% to nearly 30%. Total scores on these items followed an almost perfect exponential distribution (r = 0.99). Our four a priori first-order factors were corroborated (interpersonal sensitivity; mistrust; ideas of reference; ideas of persecution). These mapped onto four classes of individual respondents: a rare, severe, persecutory class with high endorsement of all item factors, including persecutory ideation; a quasi-normal class with infrequent endorsement of interpersonal sensitivity, mistrust and ideas of reference, and no ideas of persecution; and two intermediate classes, characterised respectively by relatively high endorsement of items relating to mistrust and to ideas of reference. Conclusions: The paranoia continuum has implications for the aetiology, mechanisms and treatment of psychotic disorders, while confirming the lack of a clear distinction from normal experiences and processes.

The effects of rotation and ice shelf topography on frazil-laden ice shelf water plumes

A model of the dynamics and thermodynamics of a plume of meltwater at the base of an ice shelf is presented. Such ice shelf water plumes may become supercooled and deposit marine ice if they rise (because of the pressure decrease in the in situ freezing temperature), so the model incorporates both melting and freezing at the ice shelf base and a multiple-size-class model of frazil ice dynamics and deposition. The plume is considered in two horizontal dimensions, so the influence of Coriolis forces is incorporated for the first time. It is found that rotation is extremely influential, with simulated plumes flowing in near-geostrophy because of the low friction at a smooth ice shelf base. As a result, an ice shelf water plume will only rise and become supercooled (and thus deposit marine ice) if it is constrained to flow upslope by topography. This result agrees with the observed distribution of marine ice under Filchner–Ronne Ice Shelf, Antarctica. In addition, it is found that the model only produces reasonable marine ice formation rates when an accurate ice shelf draft is used, implying that the characteristics of real ice shelf water plumes can only be captured using models with both rotation and a realistic topography.

Gaussian processes autoencoder for dimensionality reduction

Learning low dimensional manifold from highly nonlinear data of high dimensionality has become increasingly important for discovering intrinsic representation that can be utilized for data visualization and preprocessing. The autoencoder is a powerful dimensionality reduction technique based on minimizing reconstruction error, and it has regained popularity because it has been efficiently used for greedy pretraining of deep neural networks. Compared to Neural Network (NN), the superiority of Gaussian Process (GP) has been shown in model inference, optimization and performance. GP has been successfully applied in nonlinear Dimensionality Reduction (DR) algorithms, such as Gaussian Process Latent Variable Model (GPLVM). In this paper we propose the Gaussian Processes Autoencoder Model (GPAM) for dimensionality reduction by extending the classic NN based autoencoder to GP based autoencoder. More interestingly, the novel model can also be viewed as back constrained GPLVM (BC-GPLVM) where the back constraint smooth function is represented by a GP. Experiments verify the performance of the newly proposed model.

Eiffel assertions and the external structure of classes and objects

The “external structure” in an object oriented system refers here to the  graphs of objects and classes. The class structure graph or class model is derived from the object structure graph or object model, and in this operation structural information is lost, or never made explicit. Although object oriented programming languages capture the class model as declarations,  contradictory assumptions about object model properties may be made introducing faults into the design. Consistent assumptions about the object model can be specified in the code using assertions such as Eiffel’s  invariants, preconditions and postconditions. Three examples specifying the external structure are considered.

Investigation of population heterogeneity of diet use among middle-aged Australians

The purpose of the study was to determine patterns of diet use among middle-aged Australian men and women and the relationships between these different usage patterns and demographic characteristics, health status and health habits. A cross-sectional mail survey was conducted among a random sample of 2975 people aged 40–71 years in Victoria, Australia. A total of 1031 usable questionnaires were obtained which included information about the use of diets (e.g. low-fat and low-salt) during the past 3 months along with demographic information, health status and health habits. Based on the responses about the use of thirteen diets for both sexes, latent class analysis was employed to identify the optimal number of use of diets and the assignment of participants to particular groups. Three types of diet uses were identified and provisionally named: diet use, selected diet use and non-diet use. This classification was associated with demographics, health status and health habits, and these associations differed between men and women. The findings suggest that nutrition education programmes should be tailored to the different needs of the diet use groups.

Effects of subjective evaluation for weekday time use onto time allocation and value of activity time on weekends

This study has formulated a behavioral model of individual activity time allocation on weekends, and has extended it to incorporate the latent determinants of time use decisions during weekdays by using a latent variable model. The ultimate goals in developing this model are to improve the individual weekend activity time allocation model by introducing latent variables, and to estimate the value of activity time of different activity types. We conducted a pilot empirical investigation using a small data set regarding time use and expenditure both for weekdays and weekends, and a few indicators of the latent variables collected from individuals in Yokohama, Japan. The empirical findings suggest that the proposed model is valuable not only for modeling activity time allocation, but also in calculating the value of activity time.