Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

This is a thesis on education about the issue of the uses of drugs by current youth in their festive and musical practice, parting from a field work within the scope of the reduction of illegal psychoactive drug related harm. This exploratory ethnographic research shows the obscure and paradoxical relationship that health, social and political institutions maintain towards drug users. Thus, the objective of this thesis is to show that the prohibition of recreational drugs generates hypocrisy and secrecy in the transmission of prevention messages to consumers, fact which is finally detrimental to health. Applying a qualitative methodology, we have explored the world of techno music in free parties in Aquitaine and clubs in the Spanish Basque border area, during the years 2000 to 2003. We have, accordingly, made an analysis of this contemporary festive culture and drug uses related to it. In addition, we have noted that society has maintained for generations a negative image of young people. Thus, in the current context of economic crisis, youth seems encouraged to live on the fringes of society or in an abusive hedonism. Finally, we have confirmed that the secret held by the users around the drugs is doubled by an institutional "omerta" on the subject. This law of silence prevents from communicating all age-old and new knowledge on drugs, knowledge that could be yet required for a consistent education on health and citizenship in our modern societies. / Il s’agit d’une thèse en sciences de l’éducation portant sur la question des usages de drogues de la jeunesse actuelle, dans des pratiques festives et musicales, faite à partir d’un travail de terrain dans le champs de la réduction des risques liés à l’usage de substances psychoactives illégales. Cette recherche ethnographique exploratoire montre les rapports obscurs et paradoxaux qu’entretiennent les institutions sanitaires, sociales et politiques envers les usagers de drogue. Ainsi l’objectif de cette thèse est de montrer que la prohibition des drogues récréatives, génère l’hypocrisie et le secret dans la transmission des messages de prévention adressés aux consommateurs, ainsi l’interdit finalement nuit à la santé. Grâce à une méthodologie qualitative, nous avons pu explorer le monde musical de la techno dans les free parties en Aquitaine et dans les clubs de la zone frontalière basque espagnole de 2000 à 2003. Nous avons réalisé en conséquence une analyse de cette culture festive contemporaine et des usages de drogues qui y sont associés. De plus, nous avons constaté que la société entretient depuis des générations une image négative des jeunes. Alors, dans le contexte actuel de crise économique, la jeunesse semble encouragée à vivre dans une certaine marginalité ou dans un hédonisme abusif. Finalement, nous avons pu observer que le secret détenu par les usagers autour des drogues est doublé d’une « omerta » institutionnelle sur le sujet. Cette loi du silence empêche la communication de savoirs ancestraux et nouveaux sur les drogues, connaissances, qui pourtant seraient nécessaires à une éducation à la santé et à la citoyenneté cohérente dans nos sociétés modernes. / Se trata de una tesis en ciencias de la educación sobre la cuestión de los usos de drogas de la juventud actual, en la práctica festiva y musical, realizada a partir de un trabajo de campo en el ámbito de la reducción de daños vinculados al uso de sustancias psicoactivas ilegales. Esta investigación etnográfica exploratoria muestra les relaciones indeterminadas y paradójicas que mantienen las instituciones sanitarias, sociales y políticas con respecto a los usuarios de droga. Así, el objetivo de esta tesis consiste en poner de manifiesto que la prohibición de las drogas recreativas genera hipocresía y secreto en la transmisión de los mensajes de prevención hacia los usuarios y, de esta manera, la prohibición perjudica al final la salud. Gracias a una metodología cualitativa, hemos podido explorar el mundo musical de la música techno en las free parties en Aquitania y en las discotecas de la zona fronteriza vasco-española en el periodo de 2000 a 2003. Por consiguiente, hemos realizado un análisis de esta cultura festiva contemporánea y de los usos de drogas relacionados con ella. Asimismo, hemos constatado que la sociedad mantiene desde generaciones una imagen negativa de los jóvenes. En el contexto actual de crisis económica, la juventud se ve alentada a vivir en una determinada marginalidad o en un hedonismo abusivo. Por último, hemos podido observar que el secreto mantenido por los usuarios en torno a las drogas se duplica debido a una “omerta” institucional sobre el tema. Esta ley del silencio impide la comunicación de conocimientos ancestrales y nuevos sobre las drogas, conocimientos que, sin embargo, serían necesarios para una educación en la salud y en una ciudadanía coherente con nuestras sociedades modernas.

A headteacher recruitment crisis continues in the primary education sector (Howson & Sprigate, 2011; Rhodes et al., 2008). This research offers a voice for an increasingly marginalised group and synthesises the experiences of 15 primary headteachers, including retired, experienced and new school leaders against the changing educational scenery of four decades. An extended metaphor describing a changing epistemological landscape is utilised (Pascale, 2011), including dramaturgical discourse (Goffman, 1974). The research assesses whether the lived experiences of school leaders evidence a supposed movement away from the ‘freedom’ of the ‘secret garden’ of the pre-National Curriculum era to a time of reducing freedoms for headteachers under a central panoptic gaze (Foucault 1979; Ball 2006) and then to a new ‘supported autonomy’ as suggested by ‘Education Excellence Everywhere’ (DfE, 2016). The thesis assesses the capacity of phenomenological methodology to address the research questions and distinctions are made between approaches to phenomenology. A case is made for ensuring critical rationalism within the methodology and difficulties of attaining ‘epoche’ and ‘phenomenological reduction’ are debated. Findings support the view that there have been significant changes to headship over time. Analysis of these changes does not support the concept of a linear movement from a time of freedom to a landscape defined by Panopticism. The research suggests that a new paradigmatic shift is significantly changing the nature of primary headship with new forms of executive leadership and structures for leadership progression. Recommendations call for a reduction in the frequency of change for school leaders, a simplification of the inspection grading system, provision of clearer pathways to headship and greater support for school leaders as local authority services decline and safeguarding for leaders from the growth of social media abuse. This research offers a unique insight into headship and addresses an identified gap in educational research.

Secret sharing is a fundamental notion for secure cryptographic design. In a secret sharing scheme, a set of participants shares a secret among them such that only pre-specified subsets of these shares can get together to recover the secret. This dissertation introduces a neural network approach to solve the problem of secret sharing for any given access structure. Other approaches have been used to solve this problem. However, the yet known approaches result in exponential increase in the amount of data that every participant need to keep. This amount is measured by the secret sharing scheme information rate. This work is intended to solve the problem with better information rate.

Multiparty computation is a computation between multiple players which want to compute a common function based on private input. It was first proposed over 20 years ago and has since matured into a well established science. The goal of this thesis has been to develop efficient protocols for different operations used in multiparty computation and to propose uses for multiparty computation in real world systems. This thesis therefore gives the reader an overview of multiparty computation from the simplest primitives to the current state of software frameworks for multiparty computation, and provides ideas for future applications. Included in this thesis is a proposed model of multiparty computation based on a model of communication complexity. This model provides a good foundation for the included papers and for measuring the efficiency of multiparty computation protocols. In addition to this model, a more practical approach is also included, which examines different secret sharing schemes and how they are used as building blocks for basic multiparty computation operations. This thesis identifies five basic multiparty computation operations: sharing, recombining, addition, multiplication and negation, and shows how these five operations can be used to create more complex operations. In particular two operations “less-than” and “bitwise decomposition” are examined in detail in the included papers. “less-than” performs the “<” operator on two secret shared values with a secret shared result and “bitwise decomposition” takes a secret shared value and transforms it into a vector of secret shared bitwise values. The overall goal of this thesis has been to create efficient methods for multiparty computation so that it might be used for practical applications in the future.

Visual cryptography, first introduced by Naor and Shamir, allows a secret (black and white) image to be encoded and distributed to a set of participants such that certain predefined sets of participants may reconstruct the image without any computation. In 2000, Blundo, De Santis, and Naor introduced a model for grey-level visual cryptography which is a generalization of visual cryptography for general access structures. Grey-level visual cryptography extends this model to include grey-scale images. Decoding is done by the human visual system. In this thesis we survey known results of grey-level visual cryptography and visual cryptography for general access structures. We extend several visual cryptography constructions to grey-level visual cryptography, and derive new results on the minimum possible pixel expansion for all possible access structures on at most four participants.

Secret sharing is a fundamental notion for secure cryptographic design. In a secret sharing scheme, a set of participants shares a secret among them such that only pre-specified subsets of these shares can get together to recover the secret. This dissertation introduces a neural network approach to solve the problem of secret sharing for any given access structure. Other approaches have been used to solve this problem. However, the yet known approaches result in exponential increase in the amount of data that every participant need to keep. This amount is measured by the secret sharing scheme information rate. This work is intended to solve the problem with better information rate.

Thesis (D. Min.)--Concordia Theological Seminary, Ft. Wayne, 1987. / Abstract. Includes bibliographical references (leaves 106-112).

Academisch proefschrift--Amsterdam. / Summaries in French, English, and German. Bibliography: p. 198-210.

Thesis (Master's)--Guo li zheng zhi da xue, 1978. / Cover title. Reproduced from typescript on double leaves. Includes bibliographical references.