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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Reduced memory and attention performance in a population-based sample of young adults with a moderate lifetime use of cannabis, ecstasy and alcohol

Indlekofer, Friedrich J., Piechatzek, Michaela, Daamen, Marcel, Glasmacher, Christoph, Lieb, Roselind, Pfister, Hildegard, Tucha, Oliver, Wittchen, Hans-Ulrich, Schütz, Christian G. January 2009 (has links)
Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or ‘ecstasy’) and δ-9-tetrahydrocannabinol (THC or ‘cannabis’). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in reaction time was found. The results are consistent with decrements of memory and attentional performance described in previous studies. These effects are relatively small; however, it must be kept in mind that this study focussed on assessing young adults with moderate drug use from a population-based study.
202

The Unsettlement of the Greek Property Regime and the Emergence of Vigilant Violence in Thessaloniki’s West End

Vrantsis, Nikolaos January 2021 (has links)
The thesis inquires into the entanglement between the unsettlement of the Greek model of social reproduction that heavily relies on self-regulated property ownership and the emergence of vigilant violence on behalf of local property owners against undocumented migrants in the relegated neighborhood of Ksiladika in Thessaloniki’s West End. It probes the extent to which incidents of vigilant violence can be used as indicators of the structural deficiencies in the Greek housing system and property paradigm. 
 First, the thesis points to the distinct historic trajectory of the Greek housing system and property regime that is carved by a strategy of minimal involvement of state authority since the end of the Greek Civil War (1949). In contrast to the (North) European paradigm, the Greek model of social reproduction is marked by a normalized laissez-faire attitude in the domain of housing and by the hypertrophy of the family institution that emerged as a substitute system of social protection vis- a-vis the atrophy of administration. The thesis then points to a political discourse investing in the figure of the householder, sketched as the ‘normal’ Greek subject par excellence, within which self- government connects up with the imperatives of good government, in times when access to housing has become scarce and social insecurity widespread. 
 I focus my study on the neighborhood of Ksiladika in Thessaloniki, where as of late a vigilant campaign of evictions of undocumented migrant squatters on behalf of local property holders was launched. I suggest that this campaign of vigilance is not an act of ‘pure racism’ but is linked with the unsettlement of the Greek model of social reproduction, the scarcity of outright homeownership as a resource of symbolic and material value and the particularity of Ksiladika, that is at once a stigmatized neighborhood and a land of promise. 
 I rely on data collected through micro-ethnographic fieldwork, participant observation and semi-structured interviews with local property holders in Ksiladika. I use the conceptual tools of social space, field of power and symbolic power found in the work of Pierre Bourdieu and Loïc Wacquant, as heuristic tools to identify the significance of property and home ownership in shaping perceptions of local property holders towards their neighborhood and in defining their actions. I present my empirical findings clarifying the diversity of choices, expectations and actions of different actors, active in this propertied field of power in the studied area. 
 The thesis draws to an end by using the findings from Ksiladika to contribute to a discussion that revolves around Wacquant’s three basic theses on the emergence of advanced urban marginality as an effect of the neoliberal state crafting on a global scale. First, I argue that in regions where the social state was inexistent, the implementation of neoliberal policies did not happen in a way identical to what can be observed in the North and do not entail a reengineering of the state. Then I suggest that Wacquant's schematization of a Janus-like Centaur state that performs liberalism for those at the top of the social scale and punitive paternalism for those at the social bottom immured in precarity does not hold, due to the expanding zone of precarity. Eventually, I suggest that neoliberal governing is not attained merely by the penal apparatus of the neoliberal Leviathan, but via a governing through subjects who internalize the postulates of the entrepreneurial ideology mediated through homeownership in times when the resource is scarce.
203

Einfluss des Vigilanzniveaus während der [18F]FDG-PET-Untersuchung auf den regionalen zerebralen Glucosestoffwechsel: Einfluss des Vigilanzniveaus während der [18F]FDG-PET-Untersuchung auf den regionalen zerebralen Glucosestoffwechsel

Günther, Thomas 02 September 2013 (has links)
Einleitung: Die Untersuchung des regionalen zerebralen Glucosestoffwechsels mittels [18F]-2-Fluor-2-desoxy-D-glucose Positronen-Emissions-Tomographie ([18F]FDG-PET) ist ein etabliertes Verfahren der molekularen Bildgebung in der Diagnostik kognitiver und affektiver Störungen. Zwischen verschiedenen Untersuchungen kann es zu intra- und interindividuellen Unterschieden im Vigilanzniveau kommen. Das Ziel dieser ersten Machbarkeitsstudie war die Untersuchung des Zusammenhangs von aktuellem Vigilanzniveau und regionalem Glucosestoffwechsel während der [18F]FDG-PET. Methoden: 14 ältere Patientinnen und Patienten mit depressiver Episode oder leichter kognitiver Beeinträchtigung (MCI, mild cognitive impairment) wurden mit simultaner Elektroenzephalographie und [18F]FDG-PET unter Ruhebedingungen untersucht. Der Zusammenhang von Vigilanzniveau und regionalem Glucosestoffwechsel wurde mittels voxelweiser einfacher linearer Regression analysiert. Ergebnisse: Der Hauptbefund war eine Zunahme des regionalen zerebralen Glucosestoffwechsels mit abnehmendem Vigilanzniveau während der [18F]FDG-PET-Untersuchung in räumlich ausgedehnten frontalen und temporalen Kortizes. Diskussion: Vigilanzbezogene Veränderungen des Glucosestoffwechsels finden sich in vergleichbaren Hirnregionen und Effektstärken wie Veränderungen des Glucosestoffwechsels bei Patientinnen und Patienten mit depressiver Störung oder MCI gegenüber Gesunden. Der Einfluss des Vigilanzniveaus auf den Glucosestoffwechsel während der [18F]FDG-PET-Untersuchung sollte in kontrollierten Studien gesunder Personen validiert werden.
204

The Influence of Anthropogenic Development of Water on Coyotes and Kit Foxes in the Great Basin and Mojave Deserts

Hall, Lucas Keith 13 March 2013 (has links) (PDF)
Anthropogenic provisioning of water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence distribution, competition dynamics, and behavior of native species. To elucidate the potential influences of water developments on native species, we tested hypotheses concerning the occurrence and behavior of native kit foxes (Vulpes macrotis). First, we tested the indirect effect of water hypothesis (IEWH) which proposes that water developments negatively affect the arid-adapted kit fox by enabling a water-dependent competitor (i.e., coyote; Canis latrans) to expand distribution in arid landscapes. We tested the two predictions of the IEWH (i.e., coyotes will visit areas with water more frequently and kit foxes will avoid coyotes) and evaluated relative use of water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet) and without (dry) water and monitored visitation by canids to scent stations and water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. There was no correlation between visits to scent stations by coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. The intense visitation to water by kit foxes in Mojave challenges our understanding that this species does not readily drink water. Our results did not support the IEWH in the Great Basin or Mojave Deserts for these two canids. Second, we tested three hypotheses that have been proposed to explain spatial variation in vigilance behavior. The predator-vigilance hypothesis (PVH) proposes that prey increase vigilance where there is evidence of predators. The visibility-vigilance hypothesis (VVH) suggests that prey increase vigilance where detection of predators is impeded or visibility is obstructed. The refuge-vigilance hypothesis (RVH) proposes that prey may perceive areas with low visibility (greater cover) as refuges and decrease vigilance. We evaluated support for these hypotheses using the kit fox, a solitary carnivore subject to intraguild predation, as a model. From 2010 to 2012, we used infrared-triggered cameras to record video of kit fox behavior at water developments in the Mojave Desert. The RVH explained more variation in vigilance behavior of kit foxes than the other two hypotheses (AICc model weight = 0.37). Kit foxes were less vigilant at water developments with low overhead cover (refuge) obstructing visibility. Based on our results, the PVH and VVH may not be applicable to all species of prey. Solitary prey, unlike gregarious prey, may use areas with concealing cover to maximize resource acquisition and minimize vigilance.
205

Cognitive dysfunction and schizophrenia : Modelling attentional impairment with psychotomimetics. Investigating attentional impairment and structural brain abnormalities following phencyclidine administration: Enhancing translatability between preclinical and clinical tests of attention utilising the modified 5-choice task in rats - the 5-Choice Continuous Performance Test.

Barnes, Samuel January 2011 (has links)
This thesis consisted of experiments designed to explore the construct of attention and investigate the disruptive effects of psychotomimetics, with a specific focus on NMDA antagonists. Phencyclidine (PCP) was administered through a variety of treatment regimens in order to to determine the ability of inducing cognitive-specific disruptions in attentional functioning. The hypothesis that sub-chronic exposure to PCP would result in persistent attentional impairment was tested, using the 5-choice serial reaction time task (5-CSRTT). The 5-CSRTT assesses not only visuospatial attention, but also components of impulsivity, compulsivity, speed of processing and motivation. It was determined that an additional task-related intervention that increased the attentional load was required to elucidate attentional impairment following sub-chronic PCP treatment. The ability of rats to perform the modified version of the 5-CSRTT, known as the 5-choice continuous performance test (5C-CPT), was investigated. The 5C-CPT was implemented to provide a task that may have greater analogy to the human CPT, than the original 5-CSRTT. The consequence of dopaminergic D1 system activation was investigated. It was revealed that D1 partial agonism improved attentional performance in a baseline-dependent manner. Following successful acquisition of the task, it was shown that repeated PCP treatment induced cognitive disruption that was cognitive-specific, and not confounded by generalised response disruption. Furthermore, a partial attenuation of the PCP-induced performance disruption was achieved following administration of the D1 partial agonist, SKF 38393. Moreover, sub-chronic PCP treatment was shown to impair 5C-CPT performance in the drug-free state. However, an additional challenge that further increased the attentional load was needed to elucidate a performance deficit. This highlighted that sustained attention/vigilance is sensitive to persistent impairment following sub-chronic PCP administration in a manner consistent with deficits observed in schizophrenia patients. This prompted the investigation that tested the hypothesis that sub-chronic PCP treatment could induce enduring structural deficits in regions associated with attentional performance. Magnetic resonance imaging (MRI) was conducted, in conjunction with 5-CSRTT and pre-pulse inhibition (PPI). It was revealed that sub-chronic PCP treatment resulted in morphological brain abnormalities in brain regions associated with 5-CSRTT performance. This was coupled with deficits in sustained attentional performance following an increase in attentional load, yet PPI was unaffected. Taken together, these findings suggested sub-chronic PCP treatment impairs attentional functionality, an effect that dissociates between effortful and passive attentional processes.
206

Effects of Subjective Workload Measurement During a Workload Transition on Task Performance

Bowers, Drew 26 August 2014 (has links)
No description available.
207

Sensory uncertainty governs the extent of audio-visual interaction

Heron, James, McGraw, Paul V., Whitaker, David J. January 2004 (has links)
No / Auditory signals have been shown to exert a marked influence on visual perception in a wide range of tasks. However, the mechanisms of these interactions are, at present, poorly understood. Here we present a series of experiments where a temporal cue within the auditory domain can significantly affect the localisation of a moving visual target. To investigate the mechanism of this interaction, we first modulated the spatial positional uncertainty of the visual target by varying its size. When visual positional uncertainty was low (small target size), auditory signals had little or no influence on perceived visual location. However, with increasing visual uncertainty (larger target sizes), auditory signals exerted a significantly greater influence on perceived visual location. We then altered the temporal profile of the auditory signal by modulating the spread of its Gaussian temporal envelope. Introducing this temporal uncertainty to the auditory signal greatly reduced its effect on visual localisation judgements. These findings support the view that the relative uncertainty in individual sensory domains governs the perceptual outcome of multisensory integration.
208

La gestion de la menace terroriste. Le système français de prévention et de répression / Management of the terrorist threat. The French System of prevention and repression

Al kaabi, Juma 03 May 2017 (has links)
Cette thèse porte sur la gestion du risque terroriste en France.En tant que droit fondamental, la sécurité publique est prise en charge par l’État qui a le devoir d’assurer la défense et la protection des personnes et des biens publiques. Afin de protéger le pays contre tout risque et toute menace terroriste, la France, un des pays du monde les plus ciblés par les terroristes, a dû s’adapter aux nouvelles formes de terrorisme qui sévissent. Pour ce faire, elle a mis en place un important dispositif d’outils et de moyens de prévention et de répression pour lutter contre le terrorisme, tels que les fichiers de police informatisés. Des outils dérogatoires de prévention du terrorisme ont ainsi été créés, d’autres ont été perfectionnés. Dans ce contexte de lutte contre le terrorisme, de nombreux acteurs interviennent, au niveau local, national, mais aussi européen et international, au sein des institutions.De leur côté, les législateurs, devant les diverses formes de terrorisme, mais également face à la fréquence de tels actes et à leur violence toujours plus grande, ont dû créer de nouvelles lois relatives à la répression et à la prévention des actions terroristes.Ils se sont aussi attachés à la répression du financement du terrorisme en incriminant les personnes qui seraient, directement ou indirectement liées à des réseaux criminels. Enfin, grâce à une collaboration efficace des acteurs sur les plans international, européen et national, ainsi qu’à des outils opérationnels et des moyens de plus en plus performants, la sécurité des personnes et des biens publics est assurée. / This thesis focuses on terrorist risk management in France.As a fundamental right, public safety is supported by the State, it has the duty to defend and protect people and public property. To protect the country against all risks and terrorist threat, France, one of the most targeted countries of the world by the terrorists, had to adapt to new forms of terrorism. To do this, it has established an important tool device and means of prevention and enforcement to fight against terrorism, such as computerized police files. Derogatory tools to prevent terrorism have also been created, others have been improved. In this context of fight against terrorism, many actors involved, at local, national as well as European and international, within the institutions.For their part, legislators, facing the frequency of such acts and their ever-increasing violence, had to create new laws for the repression and prevention of terrorism.They also committed to the suppression of terrorist financing by criminalizing those who would be directly or indirectly linked to criminal networks. Finally, through effective collaboration of actors on the international, European and national, as well as operational tools and means of increasingly effective, the safety of persons and public goods is assured.
209

Growing up with violent fathers: conversations with daughters

Mtetwa, Thandazile Grace Nokukhanya 11 1900 (has links)
The effects of having witnessed their fathers’ violent behaviour impacts on daughters for a long period afterwards, even in adulthood. This study explores this phenomenon by means of literature review and interviews. The literature indicates that the effects of paternal violence is linked to forced maturity, secrecy, pretending, self-blame, and negative impact on the daughter’s relationships with both parents. A narrative approach was used to interview three adult participants. The conversations were analysed using thematic analysis and hermeneutics. Themes that emerged include avoidance, ambivalence towards the parents, aggression, assertiveness, and over-responsibility. There is a tendency to avoid intense, emotionally-laden, ambiguous and unpredictable situations through the use of interpersonal vigilance, an emotionally strong poise, distancing, being agreeable and devoutness. Also, there is a fear of becoming just like their abusive father. The psychological impact of being witness to a father’s violent behaviours has long-lasting effects on daughters. / Psychology / M.A. (Clinical Psychology)
210

Le sommeil des personnes atteintes de schizophrénie : résultats d’études par questionnaire, polysomnographie et analyse spectrale de l’EEG en sommeil paradoxal

Poulin, Julie 06 1900 (has links)
Les personnes atteintes de schizophrénie peuvent présenter un sommeil anormal même lorsqu’elles sont stables cliniquement sous traitements pharmacologiques. Les études présentées dans cette thèse ont pour but de mesurer le sommeil afin de mieux comprendre les dysfonctions des mécanismes cérébraux pouvant être impliqués dans la physiopathologie de la schizophrénie. Les trois études présentées dans cette thèse rapportent des résultats sur le sommeil dans la schizophrénie à trois niveaux d’analyse chez trois groupes différents de patients. Le premier niveau est subjectif et décrit le sommeil à l’aide d’un questionnaire administré chez des personnes atteintes de schizophrénie cliniquement stables sous traitements pharmacologiques. Le deuxième niveau est objectif et évalue le sommeil par une méta-analyse des études polysomnographiques chez des patients atteints de schizophrénie ne recevant pas de traitement pharmacologique. Le troisième niveau est micro-structurel et utilise l’analyse spectrale de l’électroencéphalogramme (EEG) afin de caractériser le sommeil paradoxal de patients en premier épisode aigu de schizophrénie avant le début du traitement pharmacologique. La première étude montre que, lorsqu’évaluées par un questionnaire de sommeil, les personnes atteintes de schizophrénie cliniquement stables sous traitements pharmacologiques rapportent prendre plus de temps à s’endormir, se coucher plus tôt et se lever plus tard, passer plus de temps au lit et faire plus de siestes comparativement aux participants sains. Aussi, tout comme les participants sains, les personnes atteintes de schizophrénie rapportent un nombre normal d’éveils nocturnes, se disent normalement satisfaites de leur sommeil et se sentent normalement reposées au réveil. La deuxième étude révèle qu’objectivement, lorsque les études polysomnographiques effectuées chez des patients non traités sont soumises à une méta-analyse, les personnes atteintes de schizophrénie montrent une augmentation du délai d’endormissement, une diminution du temps total en sommeil, une diminution de l’efficacité du sommeil et une augmentation de la durée des éveils nocturnes comparativement aux participants sains. Les patients en arrêt aigu de traitement ont des désordres plus sévères au niveau de ces variables que les patients jamais traités. Seulement les patients jamais traités ont une diminution du pourcentage de stade 2 comparativement aux participants sains. La méta-analyse ne révèle pas de différence significative entre les groupes en ce qui concerne le sommeil lent profond et le sommeil paradoxal. La troisième étude, portant sur l’analyse spectrale de l’EEG en sommeil paradoxal, montre une diminution de l’amplitude relative de la bande de fréquence alpha dans les régions frontales, centrales et temporales et montre une augmentation de l’amplitude relative de la bande de fréquence bêta2 dans la région occipitale chez les personnes en premier épisode de schizophrénie jamais traitées comparativement aux participants sains. L’activité alpha absolue est positivement corrélée aux symptômes négatifs dans les régions frontales, centrales et temporales et négativement corrélée aux symptômes positifs dans la région occipitale. L’activité beta2 absolue ne montre pas de corrélation significative avec les symptômes positifs et négatifs de la schizophrénie. Ces résultats sont discutés suivant la possibilité que des dysfonctions au niveau des mécanismes de la vigilance seraient impliquées dans la physiopathologie de la schizophrénie. / Patients with schizophrenia may have an abnormal sleep even when clinically stable under pharmacological treatments. In the present thesis, sleep studies aim at measuring central nervous system dysfunctions that can be involved in the pathophysiology of schizophrenia. The present thesis includes three studies. These studies report results on sleep in patients with schizophrenia in a three levels analysis with three different groups of patients. The first level is subjective and describes sleep habits using a questionnaire administered to outpatients with schizophrenia clinically stable under pharmacological treatments. The second level of analysis is objective and evaluates sleep architecture using a meta-analysis of polysomnographic studies in untreated patients with schizophrenia. The third level is microstructural and uses electroencephalogram (EEG) spectral analysis to characterize REM sleep in never-treated patients with first-episode schizophrenia. The first study shows that, when evaluated using a sleep habits questionnaire, outpatients with schizophrenia clinically stable under pharmacological treatments report increased time to fall asleep, have earlier bedtime, later risetime, spend more time in bed and do more naps compared to healthy participants. Also, similarly to healthy participants, most patients with schizophrenia report normal wake time after sleep onset, are normally satisfied about their sleep and feel normally refreshed in the morning. The second study reveals that, objectively, when polysomnographic studies evaluating untreated patients with schizophrenia are submitted to a meta-analysis, patients with schizophrenia have increased sleep latency, reduced total sleep time, reduced sleep efficiency and increased wake time after sleep onset compared to healthy participants. Patients in acute drug withdrawal show more severe sleep disturbances in these variables compared to never treated patients. Only never treated patients show decreased stage 2 sleep duration compared to healthy participants. The meta-analysis does not reveal significant differences between groups in regards to slow wave sleep and paradoxical sleep variables. The third study about REM sleep EEG spectral analysis shows decreased relative alpha spectral amplitude in frontal, central and temporal cortical regions and increased relative beta2 spectral amplitude in the occipital region in never treated patients with first-episode schizophrenia compared to healthy participants. Absolute alpha spectral amplitude correlates positively with negative symptoms in the frontal, central and temporal regions and negatively with positive symptoms in the occipital region. No significant correlation has been observed between beta2 spectral amplitude and clinical symptoms of schizophrenia. These results are discussed following the possibility that dysfunctions in the mechanisms of vigilance would be involved in the pathophysiology of schizophrenia.

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