12,501 research outputs found

    Identification of Hindbrain Neural Substrates for Motor Initiation in the hatchling Xenopus laevis Tadpole

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    Animal survival profoundly depends on the ability to detect stimuli in the environment, process them and respond accordingly. In this respect, motor responses to a sensory stimulation evolved into a variety of coordinated movements, which involve the control of brain centres over spinal locomotor circuits. The hatchling Xenopus tadpole, even in its embryonic stage, is able to detect external sensory information and to swim away if the stimulus is considered noxious. To do so, the tadpole relies on well-known ascending sensory pathway, which carries the sensory information to the brain. When the stimulus is strong enough, descending interneurons are activated, leading to the excitation of spinal CPG neurons, which causes the undulatory movement of swimming. However, the activation of descending interneurons that marks the initiation of motor response appears after a long delay from the sensory stimulation. Furthermore, the long-latency response is variable in time, as observed in the slow-summating excitation measured in descending interneurons. These two features, i.e. long-latency and variability, cannot be explained by the firing time and pattern of the ascending sensory pathway of the Xenopus tadpole. Therefore, a novel neuronal population has been proposed to lie in the hindbrain of the tadpole, and being able to 'hold' the sensory information, thus accounting for the long and variable delay of swim initiation. In this work, the role of the hindbrain in the maintenance of the long and variable response to trunk skin stimulation is investigated in the Xenopustadpole at developmental stage 37/38. A multifaceted approach has been used to unravel the neuronal mechanisms underlying the delayed motor response, including behavioural experiments, electrophysiology analysis of fictive swimming, hindbrain extracellular recordings and imaging experiments. Two novel neuronal populations have been identified in the tadpole's hindbrain, which exhibit activation patterns compatible with the role of delaying the excitation of the spinal locomotor circuit. Future work on cellular properties and synaptic connections of these newly discovered populations might shed light on the mechanism of descending control active at embryonic stage. Identifying supraspinal neuronal populations in an embryonic organism could aid in understanding mechanisms of descending motor control in more complex vertebrates

    The company she keeps : The social and interpersonal construction of girls same sex friendships

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    This thesis begins a critical analysis of girls' 'private' interpersonal and social relations as they are enacted within two school settings. It is the study of these marginal subordinated worlds productivity of forms of femininity which provides the main narrative of this project. I seek to understand these processes of (best) friendship construction through a feminist multi-disciplinary frame, drawing upon cultural studies, psychoanalysis and accounts of gender politics. I argue that the investments girls bring to their homosocial alliances and boundary drawing narry a psychological compulsion which is complexly connected to their own experiences within the mother/daughter bond as well as reflecting positively an immense social debt to the permissions girls have to be nurturant and ; negatively their own reproduction of oppressive exclusionary practices. Best friendship in particular gives girls therefore, the experience of 'monogamy' continuous of maternal/daughter identification, reminiscent of their positioning inside monopolistic forms of heterosexuality. But these subcultures also represent a subversive discontinuity to the public dominance of boys/teachers/adults in schools and to the ideologies and practices of heterosociality and heterosexuality. By taking seriously their transmission of the values of friendship in their chosen form of notes and diaries for example, I was able to access the means whereby they were able to resist their surveillance and control by those in power over them. I conclude by arguing that it is through a recognition of the valency of these indivisiblly positive and negative aspects to girls cultures that Equal Opportunities practitioners must begin if they are serious about their ambitions. Methods have to be made which enable girls to transfer their 'private' solidarities into the 'public' realm, which unquestionably demands contesting with them the causes and consequences of their implication in the divisions which also contaminate their lives and weaken them

    Tales of two houses : a comparative study between some Arab and British feminist novels

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    This thesis is a comparative study of some of the English feminist novels by Michele Roberts and Sara Maitland on the one hand, and some of the Arab feminist novels by Hanan AlShaykh and Ahdaf Soueif on the other. It consists of a general introduction and six chapters. The "General Introduction" deals mainly with the theoretical and methodological issues which have both informed and manifested in the analyses. It also includes some background information about the intellectual strands within a feminist discourse and a purview of the major issues as tackled by specifically feminist critics. Some of the basic objectives that the study attends to are also pinpointed. Chapter one is entitled "Feminism: An Historical Context". It attempts to expose the complex relationship between an Arab feminist discourse as informed by historical relations with the West in colonial and postcolonial eras. A particular emphasis is placed on the emergence of feminism within an Arab-Islamic context. A socio-cultural and political interpretation of such relations is provided to promote a method of reading the novels as necessarily contextualised activities. Since genuine and constructive visions of transformation as pertaining to women's issues need be inherently embedded in certain political and historical realities, the second and third chapters are basically devoted to unfolding the entwining dynamics as informing the realities of both the Western and Arab "houses". How authentic both the Arab and British writers are in depicting their own distinctive realities in the different feminist novels arehighlighted and assessed. Also examined is the extent to which feminist political concerns could be seen as pursued at the expense of the aesthetic aspects of the novels. Chapter Four is devoted to analysing images of men in the feminist novels at hand. It also unravels how these images can be integrated into a comprehensive vision of change. The 111 relation between reductionist and stereotypical representations of men and the tenability of transformative visions are also discussed. Chapter Five, "Absences and Presences: Religious Icons and Ephemeral Images", is concerned with analysing the politics of certain exclusions and inclusions in the feminist novels especially in connection with some religious and other cultural forces pertaining to specific realities. Relating that politics to wider socio-cultural contexts helps in accounting for the convergences and divergences between the Arab feminist novel and its English counterpart and works to expose the nature of the intricate relationship between the two. Chapter Six, "Conclusion", underscores the most important findings of the study. The tenability of visions of change that would affect the lives of women and their societies at large as disseminated by the feminist novelists are assessed against various socio-cultural and political givens. I-low the profundity and comprehensibility of these visions are inherently linked to the novels' aesthetic value is also discussed

    Power in the health service : The effects of reorganisation on professions and bureaucracies

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    The National Health Service (NHS) has been analysed predominantly in terms dictated by a systems/functional model of organisational behaviour. Decision-making processes which did not comply with this model were regarded as pathological or dysfunctional. This study takes a different stance and looks at District Health Authorities (DHAs) to see if the NHS can be better understood by accepting Lukes' conception of a "third dimension of power". The study is not focussed around conflicts of interest because the third dimension of power involves situations in which "real" interests may remain unknown. Power may prevent conflicts becoming apparent and interests becoming realised. Because, however, Lukes had suggested that interests may become realised during periods of change, the study focusses on the restructuring which began with reorganisation of the NHS in 1982. The parts played by medical professionals, administrative staff, nursing staff, and lay-members on DHAs are examined and demonstrate the extent to which their activities were influenced by one another and by their external political environment, notably the Conservative government. The mechanisms of power used during the period 1982-1985 when new management structures were established and then replaced by a further reorganisation of management are examined. This shows the extent to which these new management changes became accepted as legitimate and how the legitimation process began with the 1982 reorganisation. Lukes' third dimension of power is confirmed as too restrictive a conception and that power is more subtle than even he had proposed. Nor is it always repressive or manipulative

    Why people tolerate transgressive leaders: Social identity advancement, group prototypicality, and charisma

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    Transgressive leaders have the potential to cause widespread disruption and damage to organisations. Not only can leaders' misconduct have economic, legal, and social ramifications for organisational functioning, but national leaders who violate established rules may also threaten the social fabric of entire societies. Despite these implications, transgressive leadership is a rampant problem within groups and organisations, and such leaders are often treated sympathetically by in-group members. This thesis aimed to identify some of the social psychological constructs and mechanisms that encourage followers to tolerate the transgressive behaviours of their leaders. Across eight studies using a variety of methods, populations, and contexts, I demonstrate the role of group prototypicality, identity advancement, and charisma in upholding the lenient treatment of transgressive leaders. Overall, findings from this thesis suggest that leaders who are perceived as having the group's best interests at heart are treated more sympathetically following their transgression. In part, this is because advancing group interests contributes towards perceptions of group prototypicality and charisma, which subsequently also encourage followers to treat their leader lightly. Additionally, perceptions of identity advancement encourage followers to rationalise the transgressive behaviour of their leader by downplaying how unethical their misconduct is, which paves the way for continued support of transgressive leaders. The research in this thesis has theoretical implications for the social identity theory of leadership, subjective group dynamics theory, and the deviance credit model. This research also provides practical insights into the difficulties faced in managing or mitigating transgressive leadership, and point to potential mechanisms that may be targeted by future interventions in resolving such a key societal problem

    Facial expression recognition and intensity estimation.

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    Doctoral Degree. University of KwaZulu-Natal, Durban.Facial Expression is one of the profound non-verbal channels through which human emotion state is inferred from the deformation or movement of face components when facial muscles are activated. Facial Expression Recognition (FER) is one of the relevant research fields in Computer Vision (CV) and Human-Computer Interraction (HCI). Its application is not limited to: robotics, game, medical, education, security and marketing. FER consists of a wealth of information. Categorising the information into primary emotion states only limit its performance. This thesis considers investigating an approach that simultaneously predicts the emotional state of facial expression images and the corresponding degree of intensity. The task also extends to resolving FER ambiguous nature and annotation inconsistencies with a label distribution learning method that considers correlation among data. We first proposed a multi-label approach for FER and its intensity estimation using advanced machine learning techniques. According to our findings, this approach has not been considered for emotion and intensity estimation in the field before. The approach used problem transformation to present FER as a multilabel task, such that every facial expression image has unique emotion information alongside the corresponding degree of intensity at which the emotion is displayed. A Convolutional Neural Network (CNN) with a sigmoid function at the final layer is the classifier for the model. The model termed ML-CNN (Multilabel Convolutional Neural Network) successfully achieve concurrent prediction of emotion and intensity estimation. ML-CNN prediction is challenged with overfitting and intraclass and interclass variations. We employ Visual Geometric Graphics-16 (VGG-16) pretrained network to resolve the overfitting challenge and the aggregation of island loss and binary cross-entropy loss to minimise the effect of intraclass and interclass variations. The enhanced ML-CNN model shows promising results and outstanding performance than other standard multilabel algorithms. Finally, we approach data annotation inconsistency and ambiguity in FER data using isomap manifold learning with Graph Convolutional Networks (GCN). The GCN uses the distance along the isomap manifold as the edge weight, which appropriately models the similarity between adjacent nodes for emotion predictions. The proposed method produces a promising result in comparison with the state-of-the-art methods.Author's List of Publication is on page xi of this thesis

    Constructing Cassandra: The social construction of strategic surprise at the Central Intelligence Agency 1947-2001

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    This dissertation takes a post-positivist approach to strategic surprise, and examines the identity and internal culture of the US Central Intelligence Agency (CIA) through the lens of social constructivism. It identifies numerous social mechanisms that created and maintained four key, persistent attributes of the CIA’s identity and culture between 1947 and 2001. These features are: 1) homogeneity of personnel; 2) scientism and the reification of a narrow form of ‘reason’; 3) an overwhelming preference for ‘secrets’ over openly-available information; and, 4) a relentless drive for consensus. It then documents the influence of these elements of the CIA’s identity and culture in each phase of the intelligence cycle (Tasking, Collection, Analysis, Production and Dissemination), prior to four strategic surprises: the Cuban Missile Crisis, the Iranian Islamic Revolution of 1979, the collapse of the USSR, and al-Qa’ida’s terrorist attacks on September 11th, 2001. It concludes that these key aspects of the CIA’s identity and culture created the antecedent conditions that allowed these four strategic surprises to occur, and thus prevented the CIA from fulfilling its mandate to ‘prevent another Pearl Harbor’. This conclusion is supported by contrasting the majority views at the CIA prior to these events with the views of ‘Cassandras’ (i.e. individuals inside or outside the Agency who anticipated the approximate course of events based on reasoned threat assessments that differed sharply from the Agency’s, but who were ignored or sidelined). In so doing, this work shifts the burden of proof for explaining strategic surprises back to the characteristics and actions of intelligence producers like the CIA, and away from errors by intelligence consumers like politicians and policymakers. This conclusion also allows this work to posit that understanding strategic surprise as a social construction is logically prior to previously proposed, entirely positivist, attempts to explain or to prevent it
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