29,854 research outputs found

    Assessing performance of artificial neural networks and re-sampling techniques for healthcare datasets.

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    Re-sampling methods to solve class imbalance problems have shown to improve classification accuracy by mitigating the bias introduced by differences in class size. However, it is possible that a model which uses a specific re-sampling technique prior to Artificial neural networks (ANN) training may not be suitable for aid in classifying varied datasets from the healthcare industry. Five healthcare-related datasets were used across three re-sampling conditions: under-sampling, over-sampling and combi-sampling. Within each condition, different algorithmic approaches were applied to the dataset and the results were statistically analysed for a significant difference in ANN performance. The combi-sampling condition showed that four out of the five datasets did not show significant consistency for the optimal re-sampling technique between the f1-score and Area Under the Receiver Operating Characteristic Curve performance evaluation methods. Contrarily, the over-sampling and under-sampling condition showed all five datasets put forward the same optimal algorithmic approach across performance evaluation methods. Furthermore, the optimal combi-sampling technique (under-, over-sampling and convergence point), were found to be consistent across evaluation measures in only two of the five datasets. This study exemplifies how discrete ANN performances on datasets from the same industry can occur in two ways: how the same re-sampling technique can generate varying ANN performance on different datasets, and how different re-sampling techniques can generate varying ANN performance on the same dataset

    Développement d’un système intelligent de reconnaissance automatisée pour la caractérisation des états de surface de la chaussée en temps réel par une approche multicapteurs

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    Le rôle d’un service dédié à l’analyse de la météo routière est d’émettre des prévisions et des avertissements aux usagers quant à l’état de la chaussée, permettant ainsi d’anticiper les conditions de circulations dangereuses, notamment en période hivernale. Il est donc important de définir l’état de chaussée en tout temps. L’objectif de ce projet est donc de développer un système de détection multicapteurs automatisée pour la caractérisation en temps réel des états de surface de la chaussée (neige, glace, humide, sec). Ce mémoire se focalise donc sur le développement d’une méthode de fusion de données images et sons par apprentissage profond basée sur la théorie de Dempster-Shafer. Les mesures directes pour l’acquisition des données qui ont servi à l’entrainement du modèle de fusion ont été effectuées à l’aide de deux capteurs à faible coût disponibles dans le commerce. Le premier capteur est une caméra pour enregistrer des vidéos de la surface de la route. Le second capteur est un microphone pour enregistrer le bruit de l’interaction pneu-chaussée qui caractérise chaque état de surface. La finalité de ce système est de pouvoir fonctionner sur un nano-ordinateur pour l’acquisition, le traitement et la diffusion de l’information en temps réel afin d’avertir les services d’entretien routier ainsi que les usagers de la route. De façon précise, le système se présente comme suit :1) une architecture d’apprentissage profond classifiant chaque état de surface à partir des images issues de la vidéo sous forme de probabilités ; 2) une architecture d’apprentissage profond classifiant chaque état de surface à partir du son sous forme de probabilités ; 3) les probabilités issues de chaque architecture ont été ensuite introduites dans le modèle de fusion pour obtenir la décision finale. Afin que le système soit léger et moins coûteux, il a été développé à partir d’architectures alliant légèreté et précision à savoir Squeeznet pour les images et M5 pour le son. Lors de la validation, le système a démontré une bonne performance pour la détection des états surface avec notamment 87,9 % pour la glace noire et 97 % pour la neige fondante

    Sexual violence as a form of social control : the role of hostile and benevolent sexism

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    This thesis examines the feminist hypothesis that rape functions as a tool of social control through which women are kept in subordinate social positions (Brownmiller, 1975). In examining this hypothesis, the current thesis explores the role of benevolent and hostile sexism in accounting for people's responses to different types of rape (i.e. stranger vs. acquaintance rape). An examination of the literature suggests that there are general societal beliefs in the distinction between "good" and "bad" rape victims (Pollard, 1992). Interestingly, researchers have observed that benevolent sexism (BS) is related to the idealisation of women in traditional gender roles (i.e. "good" women; Glick et aI., 2000). It is, therefore, argued that individuals who idealise women in traditional roles (i.e. high BS individuals) are more likely to negatively evaluate rape victims who can be perceived as violating these norms. Nine empirical studies are presented in this thesis. Study 1 examines the potential role of BS in accounting for previously observed differences in the amount of blame attributed to stranger and acquaintance rape victims (e.g. Pollard, 1992). Studies 2 and 3 examine the psychological mechanisms that underlie the relationship between BS and victim blame in acquaintance rape situations. Studies 2 and 4 also explore the psychological mechanisms that underlie the relationship between hostile sexism (HS) and self reported rape proclivity in acquaintance rape situations (c.f. Viki, 2000). In Study 5, the relationship between BS and paternalistic chivalry (attitudes that are simultaneously courteous and restrictive to women) is examined. Studies 6 and 7 examine the role of BS in accounting for participants' responses to stranger vs. acquaintance rape perpetrators. The last two studies (Studies 8 and 9) examine the potential role of legal verdicts in moderating the relationship between BS and victim blame in acquaintance rape cases. Taken together, the results support the argument that BS provides a psychological mechanism through which differences in the amount of blame attributed to stranger and acquaintance rape victims can be explained. In contrast, HS provides a mechanism for explaining differences in self-reported proclivity to commit stranger and acquaintance rape. The thesis concludes with a summary of the findings, a discussion of the methodological limitations of the studies and suggestions of directions for future research

    Foundations for programming and implementing effect handlers

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    First-class control operators provide programmers with an expressive and efficient means for manipulating control through reification of the current control state as a first-class object, enabling programmers to implement their own computational effects and control idioms as shareable libraries. Effect handlers provide a particularly structured approach to programming with first-class control by naming control reifying operations and separating from their handling. This thesis is composed of three strands of work in which I develop operational foundations for programming and implementing effect handlers as well as exploring the expressive power of effect handlers. The first strand develops a fine-grain call-by-value core calculus of a statically typed programming language with a structural notion of effect types, as opposed to the nominal notion of effect types that dominates the literature. With the structural approach, effects need not be declared before use. The usual safety properties of statically typed programming are retained by making crucial use of row polymorphism to build and track effect signatures. The calculus features three forms of handlers: deep, shallow, and parameterised. They each offer a different approach to manipulate the control state of programs. Traditional deep handlers are defined by folds over computation trees, and are the original con-struct proposed by Plotkin and Pretnar. Shallow handlers are defined by case splits (rather than folds) over computation trees. Parameterised handlers are deep handlers extended with a state value that is threaded through the folds over computation trees. To demonstrate the usefulness of effects and handlers as a practical programming abstraction I implement the essence of a small UNIX-style operating system complete with multi-user environment, time-sharing, and file I/O. The second strand studies continuation passing style (CPS) and abstract machine semantics, which are foundational techniques that admit a unified basis for implementing deep, shallow, and parameterised effect handlers in the same environment. The CPS translation is obtained through a series of refinements of a basic first-order CPS translation for a fine-grain call-by-value language into an untyped language. Each refinement moves toward a more intensional representation of continuations eventually arriving at the notion of generalised continuation, which admit simultaneous support for deep, shallow, and parameterised handlers. The initial refinement adds support for deep handlers by representing stacks of continuations and handlers as a curried sequence of arguments. The image of the resulting translation is not properly tail-recursive, meaning some function application terms do not appear in tail position. To rectify this the CPS translation is refined once more to obtain an uncurried representation of stacks of continuations and handlers. Finally, the translation is made higher-order in order to contract administrative redexes at translation time. The generalised continuation representation is used to construct an abstract machine that provide simultaneous support for deep, shallow, and parameterised effect handlers. kinds of effect handlers. The third strand explores the expressiveness of effect handlers. First, I show that deep, shallow, and parameterised notions of handlers are interdefinable by way of typed macro-expressiveness, which provides a syntactic notion of expressiveness that affirms the existence of encodings between handlers, but it provides no information about the computational content of the encodings. Second, using the semantic notion of expressiveness I show that for a class of programs a programming language with first-class control (e.g. effect handlers) admits asymptotically faster implementations than possible in a language without first-class control

    Digital asset management via distributed ledgers

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    Distributed ledgers rose to prominence with the advent of Bitcoin, the first provably secure protocol to solve consensus in an open-participation setting. Following, active research and engineering efforts have proposed a multitude of applications and alternative designs, the most prominent being Proof-of-Stake (PoS). This thesis expands the scope of secure and efficient asset management over a distributed ledger around three axes: i) cryptography; ii) distributed systems; iii) game theory and economics. First, we analyze the security of various wallets. We start with a formal model of hardware wallets, followed by an analytical framework of PoS wallets, each outlining the unique properties of Proof-of-Work (PoW) and PoS respectively. The latter also provides a rigorous design to form collaborative participating entities, called stake pools. We then propose Conclave, a stake pool design which enables a group of parties to participate in a PoS system in a collaborative manner, without a central operator. Second, we focus on efficiency. Decentralized systems are aimed at thousands of users across the globe, so a rigorous design for minimizing memory and storage consumption is a prerequisite for scalability. To that end, we frame ledger maintenance as an optimization problem and design a multi-tier framework for designing wallets which ensure that updates increase the ledger’s global state only to a minimal extent, while preserving the security guarantees outlined in the security analysis. Third, we explore incentive-compatibility and analyze blockchain systems from a micro and a macroeconomic perspective. We enrich our cryptographic and systems' results by analyzing the incentives of collective pools and designing a state efficient Bitcoin fee function. We then analyze the Nash dynamics of distributed ledgers, introducing a formal model that evaluates whether rational, utility-maximizing participants are disincentivized from exhibiting undesirable infractions, and highlighting the differences between PoW and PoS-based ledgers, both in a standalone setting and under external parameters, like market price fluctuations. We conclude by introducing a macroeconomic principle, cryptocurrency egalitarianism, and then describing two mechanisms for enabling taxation in blockchain-based currency systems

    The Impact of a Play Intervention on the Social-Emotional Development of Preschool Children in Riyadh, Saudi Arabia

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    Practitioners working with children have emphasized that play is vital to children’s development, Links between children’s social-emotional development and play have been widely documented. However, rigorous research evidence of these links remains limited. This study’s objectives were to measure the impact of play on children’s social-emotional development in the kingdom of Saudi Arabia; identify teachers’ viewpoints around the use of play intervention; and understand the children’s experience of play intervention. Fifty-nine children aged between five and six years, with mean age of 5.5 (SD 3.376) and eight teachers participated in the study. The study used a mixed-method strategy including questionnaires, interviews, and focus group discussions. Children’s social-emotional development was measured by using the Strengths and Difficulties Questioner (SDQ). A pre-/post-test counterbalanced design was used to measure the impact of the play intervention on children’s development. Teachers’ perspectives on play were obtained by interviewing eight teachers. Children’s views were gathered through focus group discussions. Repeated measures ANOVA was conducted to determine the differences in the SDQ score over three time points. Results showed that using unstructured loose parts play had positively impacted children’s social-emotional development. After participation in the play intervention, scores from the SDQ indicated that children demonstrated significantly less problematic emotional, conduct and peer relationship issues. They also scored significantly higher in their positive prosocial behaviour. These positive effects were sustained after six weeks of stopping the intervention. The play intervention did not however impact children’s hyperactivity level. The interviews analysis illustrates four main themes: concept and characteristics of play, play functions, developmental benefits of play, and play and practice. Regarding children’s discussion, affordance emerged as a main theme; this includes emotional, social, and functional affordances. Unstructured loose parts play intervention was demonstrated to have positive impacts on children’s social-emotional development. The study’s findings support the view that play is a way to increase children’s development

    Working in ministries or public organizations in Saudi Arabia : A study of career development and job satisfaction of the Saudi Arabian middle managers

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    Career development and job satisfaction studies carried out in developing countries are very limited in number. Saudi Arabia is one of those developing countries which appeared on the political scene quite recently, but striving hard to develop its human resources due to its heavy dependence on expatriate labour to initiate and execute its development plans. The genesis of the study began when General Civil Service Bureau officials noticed a large movement of employees from ministries to other sectors (i.e. public organizations and the private sector). The purpose of this dissertation is to examine and analyze the factors behind this movement and relate this to the studies of career development and job satisfaction. The position of government organizations in Saudi Arabia is rather unique. Most of their employees are drawn from Universities due to the regulations of the GCSB of compelling them to work in ministries for a period equivalent to that spent in their University education until graduation. This situation has prevented such graduates from choosing their own occupations and seem to hinder their career development. As a consequence, this study, not only analyzes career development and job satisfaction in Saudi Arabia, but (v) job satisfaction in Saudi Arabia, but also makes a comprehensive evaluation of economic, social and organisational environments which seem to have an effect of the occupational choice of the Saudis. We take the assumption that the ideology of free occupational choice is not properly applied in Saudi Arabia due to some cultural variables (e.g. nepotism and strong family ties). Hence, this thesis will develop a definition of the concept of occupational choice and career development and the process of personnel flow and the ways in which such movement can be influenced within the Saudi context. The study will be primarily concerned with middle managers in two types of organization - government ministries and public organizations. This will hopefully give a profile of the Saudi situation as far as occupational choice, career development and job satisfaction are concerned

    Gendered spaces in contemporary Irish poetry

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    The thrust of this thesis is summarized by the following questions: How does contemporary Irish poetry migrate from traditional conceptions of identity drawn on by the cultural nationalism of the Irish Literary Revival, and what effects does this have on understanding gendered and national identity formation? Chapters are on the following: Seamus Heaney, Tom Paulin, Paul Muldoon, MedbhMcGuckian, Eavan Boland and Sara Berkeley. These poets are chosen for discussion since their work most effectively engages with the relationship between woman and nation, the representation of gendered national identity, and the importance of feminist and post-colonial theorization. Focusing on poetry worth and South of the border from the last fifteen years, the thesis asks how a younger generation of poets provide a response to nationality which is significantly different from their predecessors. The thesis is composed of three parts: the first understand how the male poets depart from conventional conceptions of the nation with reference to post-colonial theorization; the second explores how feminist theorization informs readings of how the female poets respond to the nation; the final part investigates migration in the poetry and problematizes this in terms of post-nationalism. Discussing the issue of deterritorialization in Irish poetry, the thesis notice how as the poets attempt to take flight from the mythologies of nationhood, they undermine the monoliths of gendered and national identity inscribed within Irish political discourse, which is typified at a representative level by the figure of Mother Ireland or Cathleen Ni Houlihan. Investigating the ways in which gender and nation, and the body and space are reinscribed by the poets, the thesis argues that their poetry challenges authentic conceptions of Irish identity and the nation-state, so as to loosen the legacy of a colonial and nationalist inheritance
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