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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.
281

Effects of Water Quality, Instream Toxicity, and Habitat Variability on Fish Assemblages in the Trinity River, Texas

Arnold, Winfred R., 1960- 12 1900 (has links)
The Trinity River flows through the Dallas-Ft. Worth Metroplex in north central Texas where it receives effluents from numerous point sources including seven large regional wastewater treatment facilities. Historically, the Trinity River has been impacted by massive wastewater loadings which often constitute > 80% of the total river discharge during low flow periods. Normally, high mass loadings correspond to the summer months, compounding the effects of a naturally stressful period, characterized by high temperatures and low dissolved oxygen concentrations. Samples from 12 stations were collected quarterly over an 18 month period from the Trinity River and two tributaries. Water samples were analyzed for a variety of water quality variables, including metals, priority pollutants, pesticides, and general water quality parameters. Water samples were also tested for acute and subchronic effects with several test species. Fish were collected at each station and assemblages were characterized using traditional classification techniques and the Index of Biotic Integrity. In addition, sediment samples were assessed for toxic effects which could have adversely impacted fish recruitment and in situ biomonitoring experiments were performed. Quantitative habitat characterization analyses were performed to gain additional information that could possibly explains differences in fish assemblage structure related to habitat variability. Data were analyzed using regression, univariate, multivariate, and descriptive statistical techniques and new approaches for analyzing impact assessment data were discussed. Results indicated that the most substantial impacts on fish assemblages were confined to a segment of the river where a sequence of point sources, in close proximity to each other, were overloading the river's capacity to sufficiently dilute and/or detoxify the effluent. Data also indicated the presence of episodic toxicity from nonpoint sources. In addition, toxic effects in sediment samples and differences in habitat were detected and may have contributed to measured differences among fish assemblages in the Trinity River.
282

The First Year: Development of Preservice Teacher Beliefs About Teaching and Learning During Year One of an MA TESOL Program

Addiego, Emily Spady 28 June 2013 (has links)
This qualitative, longitudinal study followed four first-year MA TESOL students through their initial year in a teacher training program with the goal of determining whether their overall beliefs about teaching and learning changed over time as a result of program curriculum and other outside factors. An analysis of semi-structured interviews with each participant, conducted one to two times per quarter, revealed that participants' beliefs appeared to evolve as a result of coursework and teaching practice. Participants' identities as teachers also showed signs of evolution and development. The participants attributed the majority of their development to hands-on teaching practice, though there was evidence that they began to integrate more theoretical aspects of program curriculum by the end of the year. However, the participants also demonstrated a lack of interest in theoretical and research-related coursework that persisted throughout their first year. Participants' lack of interest and stress brought on by unfamiliar material may have limited the amount of integration of research and theory into their practice. Findings suggest a mismatch between program goals and student goals, with students being focused on teaching practice and the program being focused on both the practical and theoretical aspects of the curriculum.
283

Analyse des performances en langue écrite d'élèves issus de l'immigration en Région de Bruxelles Capitale: études longitudinales / Analysis of written language performance of pupils from emigrant families in Area of Brussels City: longitudinal studies

Akif, Zohra 29 November 2007 (has links)
L’objectif de la présente étude est de cerner les difficultés rencontrées en lecture et en orthographe par les enfants issus de l’immigration de 2ème et 3ème génération qui on été comparés à leurs pairs autochtones inscrits dans les même classes. L’échantillon comprend 357 élèves scolarisés dans des écoles communales en discrimination positive de la région de Bruxelles Capitale. Un suivi longitudinal de la 3ème à la 5ème année primaire a également été mené. Les résultats nous ont permis d’évaluer les performances en langue orale et en langue écrite de ces élèves, et de mettre en évidence d’une part les mécanismes de lecture et d’écriture et d’autre part les facteurs susceptibles d’expliquer les retards sur le plan psycholinguistique. Deux programmes d’entraînements, au niveau phonologique et syntaxique ont été élaborés en vue de mesurer leur effet sur les différences de compétences. / The objective of this study is to determine the difficulties encountered in reading and spelling by children from emigrant families (2nd and 3rd generation) compared with their pars autochthons registered in the same classes. The sample includes 357 pupils in positive discrimination elementary schools from the area of Brussels City. A longitudinal follow-up from 3rd to 5th primary grade was also carried out. The results enabled us to evaluate the performances in spoken and written language of these pupils and to highlight the mechanisms of reading and writing and the factors which explain psycholinguistics delays. Two training programs, one phonologic, the other syntactic were elaborate in order to measure their effect on the differential of skills. / Doctorat en Sciences Psychologiques et de l'éducation / info:eu-repo/semantics/nonPublished
284

Exploring the tension between the discourses of affirmative action and the knowledge economy

Waglay, Afsar Ali 03 1900 (has links)
Thesis (MEd)--Stellenbosch University, 2013. / Bibliography / ENGLISH ABSTRACT: South Africa needs to ensure equal opportunity for all to higher education, and given that it also needs to correct the drastic imbalances brought about by apartheid, affirmative action is seen as a strategy to pursue both goals. Affirmative action is comprised of programs and policies that grant favorable treatment on the basis of race or gender to government-defined “disadvantaged” individuals. However, affirmative action is not without its own challenges and difficulties. The main question that this thesis addresses is “what are the tensions between applying affirmative action policies in South African higher education institutions and the demands of a knowledge economy within a globalised world?” I argue that though universities need to be more demographically representative and broaden access to previously disadvantaged individuals by adjusting entry requirements, they cannot compromise on their quality of graduates by adjusting their exit criteria in line with racial representivity. That would undermine the very worth of higher education as a social good, the dignity of the individual graduate, as well as the economic growth of the country. Accusations that affirmative action is merely “reverse discrimination” are refuted by an appeal to Rawls’s Principle of Difference which holds that policies of inequality can be socially just. Drawing on Charles Taylor and Wally Morrow, I posit that within a democracy, affirmative action should be seen as a shared rather than a convergent good for broadening access to quality education. But whereas broadening formal access seems like a legitimate and necessary step to address the inherited inequities, the broadening of epistemological access would undermine the very aims of quality education. Furthermore, I argue that formal access should be driven by the politics of difference, but that epistemological access that ensures educational success should be driven by the politics of equal dignity. In order to see how some of these concepts and policies of affirmative action play out in an actual institution, I look at the University of Cape Town (UCT). Here the main debates relating to its affirmative action policy are whether demographic representivity is the only outcome for evaluating the success of affirmative action, and whether “disadvantaged” individuals should be selected on criteria other than race. It also considers whether its affirmative action policies could compromise its functioning and ability to supply quality qualifications to the required number of disadvantaged individuals. There is no easy and simple answer to whether affirmative action in fact promotes equal opportunity to higher education and equips all South African graduates with the necessary skills for a knowledge economy. It would be therefore important to do further research on what nonrace based affirmative action policies might entail while keeping in mind the shifts in the global economy and the need for academic rigor. Furthermore, more longitudinal research needs to be done on the complex consequences of affirmative action, on both an individual level with issues of identity and career mobility, and on a broader socio-economic level with issues of economic growth and social welfare. / AFRIKAANSE OPSOMMING: Suid-Afrika moet hom beywer tot die daarstelling van gelyke geleenthede vir almal tot hoëronderwys, en gegewe dat daar ’n behoefte is om drastiese ongelykhede van apartheid reg te stel, word regstellende aksie gesien as a strategie om beide doelstellings na te streef. Regstellende aksie bestaan uit programme en beleide wat daarop gemik is om begunstigde behandeling te dien aan “voorheen benadeelde” individue, soos deur die staat gedefineer, op grond van ras en geslag. Maar regstellende aksie is nie sonder sy eie uitdagings en swaarhede nie. Die hoofvraag wat hierdie tesis addreseer, is: “Watter gespannenhede is daar tussen die uitvoering van regstellende aksie beleide in Suid-Afrikaanse Hoëronderwys instellings en die eise van ’n kennis-ekonomie binne ’n geglobaliseerde wêreld?” Ek argumenteer dat, ofskoon daar ’n behoefte is vir universiteite om meer demografies verteenwoordigend te wees en hul toegang tot voorheen benadeelde individue te verbreed deur toelatingsvereistes te wysig, kan hulle nie kompromeer op hul gehalte van gegradueerdes deur uitgangskriteria in lyn met ras verteenwoordiging nie. Dit sal juis die waarde van hoëronderwys as ’n sosiale goedheid, die waardigheid van die individule gegradueerde asook die ekonomiese groei van die land ondermyn. Aantygings dat regstellende aksie bloot “wedergekeerde diskriminasie” is, word weerlê deur ’n verwysing na Rawls se Beginsel van Verskil wat stel dat beleide van ongelykhede maatskaplike regverdiging kan hê. Gegrond op Charles Taylor en Wally Morrow, postuleer ek dat, binne ’n demokrasie, regstellende aksie beskou moet word as ’n gedeelde eerder as ’n konvergente goedheid om gehalte onderwys verder toeganklik te maak. Maar waar verbrede formele toegang gesien kan word as ’n wettige en nodige stap om geërfde ongelykhede aan te spreek, sal die verbreding van epistemologiese toegang juis die doelstellings van gehalte onderwys ondermyn. Verder voer ek aan dat formele toegang aangedryf moet word deur die politiek van verskil, maar dat epistemologiese toegang wat opvoedkundige sukses verseker, aangedryf moet word deur die politiek van gelyke waardigheid. Ten einde te sien hoe van hierdie konsepte en beleide van regstellende aksie hulself uitspeel in eintlike inrigtings van onderwys, kyk ek na die Universiteit Kaapstad (UK). Hier draai die debat aangaande regstellende aksie beleid om of die demografiese verteenwoordiging die enigste uitkoms is ter evaluering van die sukses van regstellende aksie, en of “benadeelde” individue geselekteer moet word op grond van kriteria anders as ras. Dit (UK) oorweeg ook of sy regstellende beleide sy funksionering en vermoë om gehalte kwalifikasies aan die verlangde getal benadeelde individue kompromiteer. Daar is geen eenvoudige en maklike antwoord betreffende regstellende aksie en of dit gelyke geleenthede tot hoëronderwys promoveer en alle Suid-Afrikaanse gegradueerders toerus met die nodige bevoegdhede vir ’n kennis-ekonomie nie. Dit sal derhalwe belangrik wees om verdere navorsing te doen oor wat nie-rasgebaseerde regstellende aksie kan behels terwyl in gedagte gehou word die skuiwe in die globale ekonomie en die behoefte aan akademiese kwaliteit. Verder moet veel meer longitudinale navorsing gedoen word oor die ingewikkelde gevolge van regstellende aksie op beide die individuele vlak met kwessies van identiteit en beroepsmobiliteit en op breër sosio-ekonomiese vlak met kwessies van ekonomiese groei en maatskaaplike welsyn.
285

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

Jallet, Sandrine 08 1900 (has links)
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. / Context and objectives. Criminal careers has been a subject of interest among criminologists for over 80 years. This research has allowed a better understanding of the evolution of criminalised individuals over time. However, research focusing on the criminal careers of women are relatively rare, this being mainly attributed to the nature of the chosen sample. While overcoming the potential limitations found in previous studies, the objective of this research is to conduct a comparative study of criminal careers among men and women (as of 18 until 47 years old) under provincial jurisdiction. Method. The sample consists of 3,320 offenders under provincial jurisdiction. The sample includes 216 female participants (6.5%) and 3104 male participants (93.5%). Descriptive statistics will be presented in order to provide a detailed portrait of offenders from 18 to 47 years old. Then, the categorical latent variable approach will be used. This type of analysis provides an estimate of sub-groups of offenders within the population that follow the growth curves separately. Thus, the proportion of individuals belonging to each of these subgroups can be estimated. Results. Women have a lower incidence of crime than men especially at the beginning of a criminal career; however this difference disappears towards the age of 40. It appears that men and women, at a certain period of time have similarities in their criminal careers. However, the prevalence of criminality among women is quite different from men. Indeed, it appears that women begin their criminal careers later than men, with a higher proportion of crimes against property. The juvenile history of criminal offence influences the perseverance in criminal careers among men and women, regardless of the type of offence. Conclusion. The results demonstrate the relevance of the difference between men and women during their criminal career. It should be one of the top interests for criminologists since women have different risks leading to offenses, as well as frequency and type of offense. Moreover, they appear to begin their criminal careers later than men.
286

Avaliação longitudinal de alterações microestruturais cerebrais estado-dependentes em indivíduos com primeiro episódio psicótico, associadas à atividade da enzima fosfolipase A2 / Longitudinal evaluation of state-dependent microstructural brain abnormalities in first-episode psychosis patients, associated to the activity of phospholipase a2 enzyme

Serpa, Mauricio Henriques 10 March 2017 (has links)
INTRODUÇÃO: Os transtornos mentais psicóticos são condições frequentes na população geral e estão associados a grande morbidade e disfuncionalidade. Apesar disso, as bases fisiopatológicas destes transtornos ainda estão em investigação. Estudos neuropatológicos post-mortem e de neuroimagem in vivo sugerem haver comprometimento da microestrutura de substância branca (SB) cerebral nestas condições clínicas, associado a alterações da conectividade cerebral. No entanto, nenhuma investigação prévia de neuroimagem avaliou especificamente se tais anormalidades microestruturais podem ser dependentes do estado clínico do paciente, i.e., se tais alterações podem variar de acordo com a fase da doença. Outra linha de investigação biológica em psicoses aponta para alterações na atividade da fosfolipase A2 (PLA2), uma enzima essencial a diversas funções na homeostase cerebral, incluindo manutenção de membrana celular, mielinização e atividade inflamatória. Estudos prévios sugerem haver relação entre alterações na atividade desta enzima e as fases da esquizofrenia. Entretanto, não há estudos translacionais que tenham avaliado como tais alterações se relacionam com anormalidades microestruturais de SB em pacientes psicóticos. OBJETIVOS: Investigar a hipótese de que alterações de microestrutura de SB presentes em pacientes em fase aguda do primeiro episódio psicótico (PEP) sejam potencialmente reversíveis após estabilização clínica; investigar também possíveis alterações estado-dependentes da atividade de PLA2 no PEP; e examinar interações entre manifestações clínicas, microestrutura de SB cerebral e atividade de PLA2 na fisiopatologia do PEP. METODOLOGIA: Pacientes em PEP não afetivo foram avaliados em dois períodos no tempo: durante a fase aguda da doença (T0); após remissão estável de sintomas (T1). Um grupo controle de voluntários saudáveis (CS) também foi avaliado longitudinalmente. Para investigar alterações de microestrutura de SB estado-dependentes, análises voxel-a-voxel de mapas cerebrais de índices de anisotropia (fractional anisotropy, FA) e difusividade (trace, TR) foram conduzidas, assim como o cálculo de correlações entre tais índices de DTI, variáveis clínicas e atividade de PLA2. A atividade dos três principais subgrupos de PLA2 em plaquetas foi estimada através de um método radioenzimático. RESULTADOS: 25 pacientes PEP e 51 CS foram avaliados em T0, com coleta de dados clínico-demográficos, ressonância magnética (RM) e amostra de sangue. Destes, 21 PEP e 36 CS realizaram a segunda aquisição de RM. No baseline (T0), os pacientes PEP apresentaram redução difusa de FA (p < 0,05, FDR), afetando principalmente SB fronto-límbica e fascículos associativos, projetivos e comissurais. As análises longitudinais demonstraram que a remissão clínica se associou a aumentos de FA em tratos de SB acometidos em T0 (p < 0,001, não corrigido), além de robustas correlações inversas entre aumentos de FA e redução sintomas ao longo do tempo (p < 0,05, FDR). As análises de PLA2 não demostraram efeitos estado-dependentes ou correlações consistentes com os índices de DTI. CONCLUSÃO: Alterações da microestrutura de SB afetando tratos cerebrais essenciais para a integração de informação perceptual, cognição e emoções são detectáveis logo após o início do PEP e podem ser parcialmente revertidas em relação direta com a remissão de sintomas psicóticos agudos. Nossos achados reforçam a visão de que anormalidades de SB de tratos cerebrais são um componente neurobiológico central nos transtornos psicóticos agudos, e que a recuperação de tal patologia de SB pode levar à melhora clínica. Por outro lado, a atividade de PLA2 não parece ter associação direta com o estado de doença ou moderar as alterações microestruturais dinâmicas de SB aqui observadas. Estudos com amostras maiores e com um maior número de avaliações ao longo do tempo são necessários para confirmar e ampliar os resultados aqui apresentados / INTRODUCTION: Psychotic disorders are frequent conditions in the general population and are associated to severe morbidity and functional impairment. Notwithstanding, the pathophysiological basis of such disorders is still under investigation. Post-mortem neuropathologic investigations and in vivo neuroimaging studies have pointed to the occurrence of abnormalities in the microstructure of brain white matter (WM) in such clinical conditions, which are associated to changes in brain connectivity. However, no previous neuroimaging investigation has specifically examined whether such microstructural abnormalities would be state-dependent, i.e., whether such changes could relate to the illness phase. Another field of biological investigation in psychosis points to changes in the activity of phospholipase A2 enzyme (PLA2), which is essential to several functions implicated in brain homeostasis, such as the maintenance of cellular membrane, myelination and inflammatory activity. Previous studies suggest the existence of a relationship between changes on PLA2 activity and schizophrenia phase. Nonetheless, no translational study to date has examined the potential interplay between PLA2 activity and WM microstructural abnormalities in psychotic patients. OBJECTIVES: To investigate the hypothesis that WM microstructural changes observed in patients during the acute first-episode psychosis (FEP) are potentially reversible following clinical remission; to investigate possible state-dependent changes in PLA2 activity in FEP; and to examine interactions between clinical manifestations, brain WM microstructure and PLA2 activity in the pathophysiology of FEP. METODOLOGY: Patients with non-affective FEP were evaluated in two time points: during the acute phase (T0) and following sustained remission (T1). A control group of healthy volunteers (HC) was also longitudinally studied. In order to investigate state-dependent WM microstructure changes, voxelwise analyses of brain maps of anisotropy (fractional anisotropy, FA) and diffusivity (trace, TR) indexes were conducted, as well as correlations between such DTI metrics, clinical variables and PLA2 activity. The activity of the three main PLA2 subgroups was assessed in platelets using a radioenzymatic method. RESULTS: 25 FEP and 51 HC were evaluated at T0 (clinical and demographic data, MRI scanning, and blood collection). Out of these, 21 FEP and 36 HC also underwent a second MRI acquisition. At baseline (T0), FEP patients presented widespread reduction of FA (p < 0.05, FDR), affecting mainly fronto-limbic WM and associative, projective and commissural fasciculi. Longitudinal analyses showed that clinical remission was associated with FA increase in WM tracts that were affected at T0 (p < 0.001, uncorrected), besides robust inverse correlations between FA increase and symptoms reduction over time (p < 0.05, FDR). PLA2 analyses failed to show state-dependent effects or consistent correlations to DTI indexes. CONCLUSION: WM changes affecting brain tracts critical to the integration of perceptual information, cognition and emotions are detectable soon after the onset of FEP and may partially reverse in direct relation to the remission of acute psychotic symptoms. Our findings reinforce the view that WM abnormalities are a key neurobiological feature of acute psychotic disorders, and that recovery from such WM pathology can lead to amelioration of symptoms. In the other hand, it seems that PLA2 activity has no direct relationship to the disease state or modulatory effects on the dynamic WM changes observed herein. Studies with larger samples and with more time points evaluations are necessary to confirm and expand the findings reported herein
287

"Estudo dopplervelocimétrico das artérias uterinas em três períodos de gestações normais" / Study of the uterine arteries Doppler ultrasound in three periods of normal pregnancies

Sakamoto, Kathia 02 October 2003 (has links)
Estudo longitudinal, prospectivo, comparativo de avaliação dopplervelocimétrica das artérias uterinas direita e esquerda em 37 gestantes normais em três períodos da gestação, acompanhadas na Clínica Obstétrica do HCFMUSP. Análise da relação S/D, índice de pulsatilidade e índice de resistência, relação com o número de incisuras e com posição da placenta. Foi observada redução nos valores dos índices durante a gestação. A relação S/D AUTE com placenta a direita apresentou média superior. A incidência de incisura foi maior no período entre a 16ª e a 24ª semana de gestação. A análise da relação entre os índices dopplervelocimétricos e a presença de incisura não teve resultados significativos / Prospective, longitudinal, comparative study of Doppler evaluation of the right and left uterine arteries of 37 healthy women with singleton pregnancies, performed in three periods of pregnancy, at the Pre-Natal Care Unit HCFMUSP. S/D ratio, pulsatility index and resistance index, number of notches and placental position were analysed. A decrease in the indices was observed with advancing gestation. When placenta was on the right side, the left uterine artery S/D ratio showed increased mean values. The incidence of uterine notch was higher between the 16th and 24th week of gestation in both arteries. No correlation was found between the presence of uterine notch and the placental position
288

"Estudo dopplervelocimétrico das artérias uterinas em três períodos de gestações normais" / Study of the uterine arteries Doppler ultrasound in three periods of normal pregnancies

Kathia Sakamoto 02 October 2003 (has links)
Estudo longitudinal, prospectivo, comparativo de avaliação dopplervelocimétrica das artérias uterinas direita e esquerda em 37 gestantes normais em três períodos da gestação, acompanhadas na Clínica Obstétrica do HCFMUSP. Análise da relação S/D, índice de pulsatilidade e índice de resistência, relação com o número de incisuras e com posição da placenta. Foi observada redução nos valores dos índices durante a gestação. A relação S/D AUTE com placenta a direita apresentou média superior. A incidência de incisura foi maior no período entre a 16ª e a 24ª semana de gestação. A análise da relação entre os índices dopplervelocimétricos e a presença de incisura não teve resultados significativos / Prospective, longitudinal, comparative study of Doppler evaluation of the right and left uterine arteries of 37 healthy women with singleton pregnancies, performed in three periods of pregnancy, at the Pre-Natal Care Unit HCFMUSP. S/D ratio, pulsatility index and resistance index, number of notches and placental position were analysed. A decrease in the indices was observed with advancing gestation. When placenta was on the right side, the left uterine artery S/D ratio showed increased mean values. The incidence of uterine notch was higher between the 16th and 24th week of gestation in both arteries. No correlation was found between the presence of uterine notch and the placental position
289

Avaliação longitudinal de alterações microestruturais cerebrais estado-dependentes em indivíduos com primeiro episódio psicótico, associadas à atividade da enzima fosfolipase A2 / Longitudinal evaluation of state-dependent microstructural brain abnormalities in first-episode psychosis patients, associated to the activity of phospholipase a2 enzyme

Mauricio Henriques Serpa 10 March 2017 (has links)
INTRODUÇÃO: Os transtornos mentais psicóticos são condições frequentes na população geral e estão associados a grande morbidade e disfuncionalidade. Apesar disso, as bases fisiopatológicas destes transtornos ainda estão em investigação. Estudos neuropatológicos post-mortem e de neuroimagem in vivo sugerem haver comprometimento da microestrutura de substância branca (SB) cerebral nestas condições clínicas, associado a alterações da conectividade cerebral. No entanto, nenhuma investigação prévia de neuroimagem avaliou especificamente se tais anormalidades microestruturais podem ser dependentes do estado clínico do paciente, i.e., se tais alterações podem variar de acordo com a fase da doença. Outra linha de investigação biológica em psicoses aponta para alterações na atividade da fosfolipase A2 (PLA2), uma enzima essencial a diversas funções na homeostase cerebral, incluindo manutenção de membrana celular, mielinização e atividade inflamatória. Estudos prévios sugerem haver relação entre alterações na atividade desta enzima e as fases da esquizofrenia. Entretanto, não há estudos translacionais que tenham avaliado como tais alterações se relacionam com anormalidades microestruturais de SB em pacientes psicóticos. OBJETIVOS: Investigar a hipótese de que alterações de microestrutura de SB presentes em pacientes em fase aguda do primeiro episódio psicótico (PEP) sejam potencialmente reversíveis após estabilização clínica; investigar também possíveis alterações estado-dependentes da atividade de PLA2 no PEP; e examinar interações entre manifestações clínicas, microestrutura de SB cerebral e atividade de PLA2 na fisiopatologia do PEP. METODOLOGIA: Pacientes em PEP não afetivo foram avaliados em dois períodos no tempo: durante a fase aguda da doença (T0); após remissão estável de sintomas (T1). Um grupo controle de voluntários saudáveis (CS) também foi avaliado longitudinalmente. Para investigar alterações de microestrutura de SB estado-dependentes, análises voxel-a-voxel de mapas cerebrais de índices de anisotropia (fractional anisotropy, FA) e difusividade (trace, TR) foram conduzidas, assim como o cálculo de correlações entre tais índices de DTI, variáveis clínicas e atividade de PLA2. A atividade dos três principais subgrupos de PLA2 em plaquetas foi estimada através de um método radioenzimático. RESULTADOS: 25 pacientes PEP e 51 CS foram avaliados em T0, com coleta de dados clínico-demográficos, ressonância magnética (RM) e amostra de sangue. Destes, 21 PEP e 36 CS realizaram a segunda aquisição de RM. No baseline (T0), os pacientes PEP apresentaram redução difusa de FA (p < 0,05, FDR), afetando principalmente SB fronto-límbica e fascículos associativos, projetivos e comissurais. As análises longitudinais demonstraram que a remissão clínica se associou a aumentos de FA em tratos de SB acometidos em T0 (p < 0,001, não corrigido), além de robustas correlações inversas entre aumentos de FA e redução sintomas ao longo do tempo (p < 0,05, FDR). As análises de PLA2 não demostraram efeitos estado-dependentes ou correlações consistentes com os índices de DTI. CONCLUSÃO: Alterações da microestrutura de SB afetando tratos cerebrais essenciais para a integração de informação perceptual, cognição e emoções são detectáveis logo após o início do PEP e podem ser parcialmente revertidas em relação direta com a remissão de sintomas psicóticos agudos. Nossos achados reforçam a visão de que anormalidades de SB de tratos cerebrais são um componente neurobiológico central nos transtornos psicóticos agudos, e que a recuperação de tal patologia de SB pode levar à melhora clínica. Por outro lado, a atividade de PLA2 não parece ter associação direta com o estado de doença ou moderar as alterações microestruturais dinâmicas de SB aqui observadas. Estudos com amostras maiores e com um maior número de avaliações ao longo do tempo são necessários para confirmar e ampliar os resultados aqui apresentados / INTRODUCTION: Psychotic disorders are frequent conditions in the general population and are associated to severe morbidity and functional impairment. Notwithstanding, the pathophysiological basis of such disorders is still under investigation. Post-mortem neuropathologic investigations and in vivo neuroimaging studies have pointed to the occurrence of abnormalities in the microstructure of brain white matter (WM) in such clinical conditions, which are associated to changes in brain connectivity. However, no previous neuroimaging investigation has specifically examined whether such microstructural abnormalities would be state-dependent, i.e., whether such changes could relate to the illness phase. Another field of biological investigation in psychosis points to changes in the activity of phospholipase A2 enzyme (PLA2), which is essential to several functions implicated in brain homeostasis, such as the maintenance of cellular membrane, myelination and inflammatory activity. Previous studies suggest the existence of a relationship between changes on PLA2 activity and schizophrenia phase. Nonetheless, no translational study to date has examined the potential interplay between PLA2 activity and WM microstructural abnormalities in psychotic patients. OBJECTIVES: To investigate the hypothesis that WM microstructural changes observed in patients during the acute first-episode psychosis (FEP) are potentially reversible following clinical remission; to investigate possible state-dependent changes in PLA2 activity in FEP; and to examine interactions between clinical manifestations, brain WM microstructure and PLA2 activity in the pathophysiology of FEP. METODOLOGY: Patients with non-affective FEP were evaluated in two time points: during the acute phase (T0) and following sustained remission (T1). A control group of healthy volunteers (HC) was also longitudinally studied. In order to investigate state-dependent WM microstructure changes, voxelwise analyses of brain maps of anisotropy (fractional anisotropy, FA) and diffusivity (trace, TR) indexes were conducted, as well as correlations between such DTI metrics, clinical variables and PLA2 activity. The activity of the three main PLA2 subgroups was assessed in platelets using a radioenzymatic method. RESULTS: 25 FEP and 51 HC were evaluated at T0 (clinical and demographic data, MRI scanning, and blood collection). Out of these, 21 FEP and 36 HC also underwent a second MRI acquisition. At baseline (T0), FEP patients presented widespread reduction of FA (p < 0.05, FDR), affecting mainly fronto-limbic WM and associative, projective and commissural fasciculi. Longitudinal analyses showed that clinical remission was associated with FA increase in WM tracts that were affected at T0 (p < 0.001, uncorrected), besides robust inverse correlations between FA increase and symptoms reduction over time (p < 0.05, FDR). PLA2 analyses failed to show state-dependent effects or consistent correlations to DTI indexes. CONCLUSION: WM changes affecting brain tracts critical to the integration of perceptual information, cognition and emotions are detectable soon after the onset of FEP and may partially reverse in direct relation to the remission of acute psychotic symptoms. Our findings reinforce the view that WM abnormalities are a key neurobiological feature of acute psychotic disorders, and that recovery from such WM pathology can lead to amelioration of symptoms. In the other hand, it seems that PLA2 activity has no direct relationship to the disease state or modulatory effects on the dynamic WM changes observed herein. Studies with larger samples and with more time points evaluations are necessary to confirm and expand the findings reported herein
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Étude comparative des trajectoires criminelles des contrevenants sous responsabilité provinciale au Québec, selon le sexe

Jallet, Sandrine 08 1900 (has links)
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. / Context and objectives. Criminal careers has been a subject of interest among criminologists for over 80 years. This research has allowed a better understanding of the evolution of criminalised individuals over time. However, research focusing on the criminal careers of women are relatively rare, this being mainly attributed to the nature of the chosen sample. While overcoming the potential limitations found in previous studies, the objective of this research is to conduct a comparative study of criminal careers among men and women (as of 18 until 47 years old) under provincial jurisdiction. Method. The sample consists of 3,320 offenders under provincial jurisdiction. The sample includes 216 female participants (6.5%) and 3104 male participants (93.5%). Descriptive statistics will be presented in order to provide a detailed portrait of offenders from 18 to 47 years old. Then, the categorical latent variable approach will be used. This type of analysis provides an estimate of sub-groups of offenders within the population that follow the growth curves separately. Thus, the proportion of individuals belonging to each of these subgroups can be estimated. Results. Women have a lower incidence of crime than men especially at the beginning of a criminal career; however this difference disappears towards the age of 40. It appears that men and women, at a certain period of time have similarities in their criminal careers. However, the prevalence of criminality among women is quite different from men. Indeed, it appears that women begin their criminal careers later than men, with a higher proportion of crimes against property. The juvenile history of criminal offence influences the perseverance in criminal careers among men and women, regardless of the type of offence. Conclusion. The results demonstrate the relevance of the difference between men and women during their criminal career. It should be one of the top interests for criminologists since women have different risks leading to offenses, as well as frequency and type of offense. Moreover, they appear to begin their criminal careers later than men.

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