930 resultados para absence
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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The role of source properties in across-formant integration was explored using three-formant (F1+F2+F3) analogues of natural sentences (targets). In experiment 1, F1+F3 were harmonic analogues (H1+H3) generated using a monotonous buzz source and second-order resonators; in experiment 2, F1+F3 were tonal analogues (T1+T3). F2 could take either form (H2 or T2). Target formants were always presented monaurally; the receiving ear was assigned randomly on each trial. In some conditions, only the target was present; in others, a competitor for F2 (F2C) was presented contralaterally. Buzz-excited or tonal competitors were created using the time-reversed frequency and amplitude contours of F2. Listeners must reject F2C to optimize keyword recognition. Whether or not a competitor was present, there was no effect of source mismatch between F1+F3 and F2. The impact of adding F2C was modest when it was tonal but large when it was harmonic, irrespective of whether F2C matched F1+F3. This pattern was maintained when harmonic and tonal counterparts were loudness-matched (experiment 3). Source type and competition, rather than acoustic similarity, governed the phonetic contribution of a formant. Contrary to earlier research using dichotic targets, requiring across-ear integration to optimize intelligibility, H2C was an equally effective informational masker for H2 as for T2.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
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Stimuli that cannot be perceived (i.e., that are subliminal) can still elicit neural responses in an observer, but can such stimuli influence behavior and higher-order cognition? Empirical evidence for such effects has periodically been accepted and rejected over the last six decades. Today, many psychologists seem to consider such effects well-established and recent studies have extended the power of subliminal processing to new limits. In this thesis, I examine whether this shift in zeitgeist is matched by a shift in evidential strength for the phenomenon. This thesis consists of three empirical studies involving more than 250 participants, a simulation study, and a quantitative review. The conclusion based on these efforts is that several methodological, statistical, and theoretical issues remain in studies of subliminal processing. These issues mean that claimed subliminal effects might be caused by occasional or weak percepts (given the experimenters’ own definitions of perception) and that it is still unclear what evidence there is for the cognitive processing of subliminal stimuli. New data are presented suggesting that even in conditions traditionally claimed as “subliminal”, occasional or weak percepts may in fact influence cognitive processing more strongly than do the physical stimuli, possibly leading to reversed priming effects. I also summarize and provide methodological, statistical, and theoretical recommendations that could benefit future research aspiring to provide solid evidence for subliminal cognitive processing.
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[EN] The impact of nest predators on sea turtle hatching success is highly variable depending on predator abundance and also on interactions among different predators. Food web connectivity usually makes it difficult to understand predator-prey interactions and develop efficient conservation strategies. In the Cape Verde archipelago there is an important nesting area for loggerheads where ghost crabs are the only described nest predator. We have studied the impact of ghost crabs on loggerhead nests on this threatened population as well as the efficiency of several management practices to reduce this impact.
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Grâce à l'élaboration de sa théorie opératoire du développement cognitif, Jean Piaget fut, sans contredit, l'un des auteurs les plus écoutés dans ce domaine. Il a mis en lumière une série de stades du développement cognitif allant du niveau sensori-moteur en passant par le niveau des opérations concrètes pour finalement aboutir à celui des opérations formelles qui obéissent à des lois précises de construction (Piaget, 1964). Parmi celles-ci, Piaget affirme l'universalité du développement de ces stades en ce sens que tous les sujets passent par la même séquence. Il s'est très peu intéressé aux différences inter-individuelles. Ce qui explique que la très grande majorité de ses travaux ont portés sur l'observation de sujets normaux (Inhelder, 1963). Ce fut donc d'autres chercheurs qui ont tenté d'appliquer la pensée piagétienne à des catégories précises de sujets. Dans cette veine, la présente recherche s'intéresse à l'application de cette pensée aux déficients profonds. C'est là un moyen utile de tester l'universalité de la séquence de développement proposée par Piaget. Le relevé de documentation sur cette question proposée par Klein et Safford (1977) permet de constater qu'il est relativement aisé de trouver des recherches s’intéressant à l'étude du fonctionnement cognitif des déficients mentaux légers atteignant la période des opérations concrètes mais qu'il est beaucoup plus difficile d'en trouver qui s'attardent au fonctionnement cognitif des déficients profonds. Il est pourtant possible d'en trouver quelques-unes (Ciccheti et Sroufe, 1976; Inhelder, 1963; Kahn, 1976; Lambert et Vanderlinden, 1977; Rogers, 1977; Silverstein et al., 1975; Wohlueter et Sindberg, 1975; Woodward, 1959). Les résultats divergent. De plus, une analyse approfondie des méthodologies utilisées suffit à convaincre que le débat demeure ouvert sur cette question. Des améliorations méthodologiques sont apportées dans cette recherche. La présente étude analyse donc le fonctionnement sensori-moteur des déficients profonds en le comparant à celui de sujets normaux de même âge mental qu'eux. Les déficients mentaux sont divisés en deux groupes selon qu'il y ait ou non présence de trouble lésionnel. Tous les sujets font face aux items de l'échelle de la poursuite visuelle et de la permanence de l'objet ainsi que celle des relations entre les objets dans l'espace construits par Uzgiris et Hunt (1975). Les résultats sont ensuite tour à tour présentés et interprétés.
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In Portugal, prenatal care guidelines advocate two prenatal ultrasound scans for all pregnant women. Not following this recommendation is considered inadequate prenatal surveillance. The National Registry of Congenital Anomalies (RENAC in Portuguese) is an active population-based registry and an important instrument for the epidemiological surveillance of congenital anomalies (CA) in Portugal. Regarding pregnancies with CA, this study aims to describe the epidemiology of absent prenatal ultrasound scans and factors associated with this inadequate surveillance.
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Shigella toxin-producing Escherichia coli (STEC) is well known for its complications such as haemolytic uraemic syndrome (HUS), but neurological symptoms have also been reported. While most cases of infection with STEC occur with concurrent HUS, we describe a patient with severe neurological symptoms in the absence of HUS.
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Actinia equina, the beadlet sea anemone, is a very labile species, displaying variable colour patterns, broad habitat choice and diverse modes of reproduction. Historically, studies using genetic markers such as allozymes and differences in habitat choice lead several authors to propose that different colour morphs could represent different species. One of the species defined was A. fragacea. In this paper, the relationships between brown, red and green colour morphs of A. equina and A. fragacea were studied, using two DNA fragments (one mitochondrial and one nuclear). Individuals were sampled from three different areas in Portugal separated by a maximum distance of 500 km. This is the first study applying direct sequencing of selected gene fragments to approach the validity of Actinia morphs as different genetic entities. The results show that, at least in the Portuguese coast, these colour morphs do not correspond to the two valid species recognized in the literature. The existence of cryptic species is discussed.
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Stress serves as an adaptive mechanism and helps organisms to cope with life-threatening situations. However, individual vulnerability to stress and dysregulation of this system may precipitate stress-related disorders such as depression. The neurobiological circuitry in charge of dealing with stressors has been widely studied in animal models. Recently our group has demonstrated a role for lysophosphatidic acid (LPA) through the LPA1 receptor in vulnerability to stress, in particular the lack of this receptor relates to robust decrease of adult hippocampal neurogenesis and induction of anxious and depressive states. Nevertheless, the specific abnormalities in the limbic circuit in reaction to stress remains unclear. The aim of this study is to examine the differences in the brain activation pattern in the presence or absence of LPA1 receptor after acute stress. For this purpose, we have studied the response of maLPA1-null male mice and normal wild type mice to an intense stressor: Tail Suspension Test. Activation induced by behaviour of brain regions involved in mood regulation was analysed by stereological quantification of c-Fos immunoreactive positive cells. We also conducted multidimensional scaling analysis in order to unravel coativation between structures. Our results revealed hyperactivity of stress-related structures such as amygdala and paraventricular nucleus of the hypothalamus in the knockout model and different patterns of coactivation in both genotypes using a multidimensional map. This data provides further evidence to the engagement of the LPA1 receptors in stress regulation and sheds light on different neural pathways under normal and vulnerability conditions that can lead to mood disorders.
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This paper considers the neglected mobilities associated with a sample of UK women reported as missing.Refracted through literatures on gendered mobility and abandonment, the paper argues that the journeys of thesewomen in crisis are not well understood by police services, and that normative gender relations may infuse theirmanagement. By selectively exploring one illustrative police case file on Kim, we highlight how reported andobserved socio-spatial relationships within private and public spaces relate to search actions. We argue that Kim’smobility and spatial experiences are barely understood, except for when they appear to symbolise disorder anddanger. We address the silences in this singular case by using the voices of other women reported as missing, ascollected in a research project to explore the agency, experience and meaning of female mobility during absence.We argue that women reported as missing are not abandoned by UK policing services, but that a policy ofcontinued search for them may be at risk if they repeatedly contravene normative socio-spatial relationshipsthrough regular absence mobilities. By way of conclusion, we address recent calls for research that explores therelationships between gender and mobility.