Dissertations / Theses on the topic 'Experimenteel toneel'

The study revisits the stretched scale experiment presented in Shepard and Jordan (1984), in which they found that the major scale can act as a perceptual schema that overrides short-term pitch memory. Here, we examine the effect of musical background on listeners' pitch judgments. 72 participants from McGill University (n = 24: non-musicians, quasi-musicians, and musicians) listened to a stretched ascending major scale (spanning a minor ninth), followed by the initial tone of the sequence, or a decoy one half-step above the original starting tone. In a parallel condition, we presented a stretched descending major scale. All tones were sinusoidal. Participants were asked to judge the test tone in relation to the initial tone of the sequence, by describing the test tone as lower, the same, or higher. Overall, the results suggest that a shifting pitch template can affect listeners' pitch judgments. These results are consistent with Shepard and Jordan's (although our distributions of judgments significantly vary from theirs.) In the subgroup analysis, non-musicians and musicians did not significantly differ in their pitch judgment accuracy, however, significantly more musicians than non-musicians judged at least two of the four test tones correctly. Taken together, these results suggest that the pitch judgments of both non-musicians and musicians can be influenced by a shifting pitch template. Keywords: auditory perception, pitch, music, memory, schemas, cognition, cognitive neuroscience, psychoacoustics, musical training
Cette étude revisite l'expérience de la gamme étirée de Shepard et Jordan (1984). Ces auteurs ont observé que la gamme majeure peut agir comme un schème perceptuel qui surpasse la mémoire à court terme des hauteurs musicales. Nous avons examiné l'effet de l'expertise musicale sur les jugements de hauteur des auditeurs. Soixante-douze participants de l'Université McGill (n = 24: non-musiciens, quasi-musiciens, et musiciens) ont écouté une gamme majeure ascendante étirée (étendue sur une neuvième mineure), suivie par la note initiale de cette séquence ou par une note un demi-ton plus basse que cette note de départ. Dans une condition parallèle, nous avons présentée une gamme majeure étirée descendante. Toutes les notes étaient sinusoïdales. Les participants devaient indiquer si la note de test était plus basse, identique, ou plus haute que la note initiale de la séquence. Les résultats suggèrent que les jugements de hauteur des auditeurs peuvent être influencés par les manipulations de la gamme-contexte. Ces résultats sont cohérents avec ceux de Shepard et Jordan (bien que la distribution des jugements dans notre étude soit très différente de celle qu'ils ont observée). Dans l'analyse par sous-groupe, les non-musiciens et les musiciens ne différaient pas significativement dans l'exactitude de leurs jugements de hauteur, cependant, plus de musiciens que de non-musiciens jugeaient au moins deux des quatre notes de test correctement. Dans l'ensemble, ces résultats suggèrent que les jugements de hauteur musicale des non-musiciens et des musiciens peuvent être influencés par des manipulations de la gamme-contexte. Mots-clés: perception auditive, hauteur musicale, musique, mémoire, schèmes, cognition, neurosciences cognitives, psychoacoustique, pratique musicale

La majorité des bruits anthropiques dans les océans sont dus à la navigation motorisée commerciale, militaire ou de tourisme. Les enjeux de défense et la préservation des écosystèmes sont au cœur de ces préoccupations.Les structures portantes telles que les hydrofoils, les pales d'hélices, les gouvernails, les stabilisateurs et les barres de plongée peuvent vibrer sous écoulement et, sous certaines conditions, produire de fortes émissions sonores au caractère tonal. Diminuer les vibrations et le bruit généré par ce type de structures, très présentes dans le domaine de la construction navale, est donc un enjeu important pour limiter la pollution sonore et améliorer la furtivité des navires.Cette étude, menée à l'Institut de Recherche de l'École Navale (IRENav), a permis de mettre en évidence le mécanisme de couplage hydroélastique responsable des vibrations de bord de fuite et du bruit tonal d'un profil portant, évoluant en régime de transition laminaire-turbulent. Ces recherches expérimentales ont été réalisées dans un tunnel hydrodynamique sur un hydrofoil de profil NACA0015, pour des angles d'incidence allant de 0° à 12° et des nombres de Reynolds variant de 200 000 à 1 200 000. Des moyens expérimentaux avancés tel que la Vélocimétrie par Image de Particules Résolue en Temps (TR-PIV), la Vélocimétrie Laser par effet Doppler (LDV) ou la vibrométrie laser ont été utilisés pour préciser les caractéristiques de l'écoulement en proche paroi ainsi que le comportement vibratoire de l'hydrofoil en fonction de l'incidence et du nombre de Reynolds. Les résultats obtenus ont permis de montrer que le bruit tonal était associé à un régime de couplage fort entre les ondes de Tollmien-Schlichting se développant dans la couche limite en régime de transition et un mode structurel de bord de fuite de l'hydrofoil, produisant un lâcher alterné de tourbillons dans le sillage. Ces travaux ont également permis de préciser qu’un tel couplage hydroélastique est conditionné d’une part, par l’occurrence d’une zone de transition de couche limite proche du bord de fuite et, d’autre part, par l’existence d’un mode structurel de bord de fuite dont la fréquence propre se situe dans la gamme d'amplification des ondes de Tollmien-Schlichting. Enfin des solutions de contrôle passif telles que la modification géométrique du bord de fuite et le forçage de la turbulence de la couche limite ont été comparées, autant du point de vue de leur efficacité que de leur impact sur les performances hydrodynamiques de l'hydrofoil
The majority of anthropogenic noise in the oceans is due to commercial, military or tourist motorized navigation. In that respect, defense issues and preservation of ecosystems are matters of great concerns.Lifting surfaces such as hydrofoils, propeller blades, rudders, stabilizers and dive bars can vibrate under flow and, under certain conditions, can produce tonal noise. Reducing the vibrations and noise generated by this type of structure, which are present in the field of shipbuilding, is therefore an important issue to limit noise pollution and to improve the acoustic discretion of ships.This study, carried out at the French Naval Academy Research Institute (IRENav), highlights the hydroelastic coupling mechanism responsible of trailing edge vibrations and of lifting surface tonal noise evolving in laminar to turbulent transition regime. This experimental research was carried out in a hydrodynamic tunnel on a NACA0015 hydrofoil, for angles of incidence ranging from 0° to 12° and Reynolds numbers varying from 200,000 to 1,200,000. Advanced experimental set ups such as Time-Resolved Particle Image Velocimetry (TR-PIV), Laser Doppler Velocimetry (LDV) or laser vibrometry were used to specify the characteristics of the near-wall flow as well as the vibrational behavior of the hydrofoil depending on the incidence and the Reynolds number. The results obtained show that the tonal noise was associated with a strong coupling regime between the Tollmien-Schlichting waves developing in the boundary layer regime and a structural mode of the trailing edge of the hydrofoil, producing a vortex shedding in the wake. This work also made it possible to show that such hydroelastic coupling is conditioned by the occurrence of a boundary layer transition zone close to the trailing edge and by the existence of a trailing edge structural mode whose natural frequency is in the amplification range of Tollmien-Schlichting waves. Finally, a comparison of passive control solutions such as geometric modification of the trailing edge and forcing of boundary layer turbulence was done, considering for both their effectiveness and their impact on the hydrodynamic performances of the hydrofoil

Många människor har påträngande tankar och uppfattar dessa som jobbiga. En vanligt förekommande copingstrategi är att tränga bort dessa upplevelser. Detta kallas suppression eller bortträngning och har kopplingar till psykiatriska besvär. Tidigare studier visar att bortträngning har en ironisk effekt som gör att de tankar en person önskar undvika studsar tillbaka in i medvetandet. I denna experimentella studie används en inomgruppsdesign för att undersöka huruvida denna ironiska effekt går att återfinna hos externa stimuli i form av sinustoner. Testdeltagare (n=40) instruerades att tränga undan eller fokusera på en av två toner. Den första hypotesen var att deltagarna under en tone-in-noise uppgift skulle indikera fler falska positiva på den bortträngda tonen, jämfört med den ton de fokuserade på eller vid ingen ton alls. Detta skulle då indikera på en ironisk effekt. Ytterligare hypoteser var att deltagare kommer ha fler sanna positiva på den bortträngda tonen jämfört med en kontrollton, även detta under brus. Sista hypotesen var att deltagarnas upplevelse av den bortträngda tonen skulle förändras och skattas som mer aversiv efter experimentet. Resultaten stödde ej någon av hypoteserna. Explorativa analyser visade att deltagarna upplevde båda tonerna som mer irriterande, uppjagande och att de lät högre efter en minnesuppgift. Studiens begränsningar diskuteras och förändringar i studiedesign föreslås.
Many people have intrusive thoughts that they experience as aversive. A common coping strategy is to suppress these thoughts. This practice has connections to psychiatric problems. Previous studies have shown that suppression has an ironic process, where the suppressed material has a rebound effect and re-enters consciousness. Furthermore, suppression can have an effect on the emotional perception of the suppressed material. In this experimental study a within-subjects design was used to examine if this ironic effect can be found when suppression is used on external stimuli such as sine tones. Participants (n=40) were instructed to either suppress or focus on two different tones. The hypothesis was that they would indicate more false positives on the suppressed tone during a tone-in-noise task, which would be a sign of a rebound effect. Furthermore, it was hypothesized that participants would have more correct identifications when the suppressed tone was present during the tone-in-noise task. Lastly it was hypothesized that participants would rate the suppressed tone as more aversive. The results did not support any of the hypotheses. Explorative analyses showed that participants rated both tones as more arousing, annoying, and loud after a recall task. Limitations of the study are discussed and changes to the study for further research design are proposed.

Le bruit tonal rayonné au bord de fuite des profils à faible nombre de Reynolds est un phénomène observé sur les ailes de drones ou micro-drones qui sont utilisés partout dans la vie quotidienne. La diminution de ce bruit va augmenter la survivabilité et l'efficacité des appareils dans le domaine militaire. De plus, cela va augmenter le champ des applications civiles et minimiser la pollution par le bruit. La réduction efficace du bruit est indispensable et, par conséquent, une compréhension complète du processus de rayonnement du bruit tonal du profil est nécessaire. Malgré le fait que des essais dédiés aient été réalisés depuis les années 70, il reste beaucoup de détails à expliquer. Le travail présenté est dédié à une étude expérimentale et analytique du bruit tonal. C'est une partie de collaboration entre l'Ecole Centrale de Lyon et Embry- Riddle Aeronautical University. Le but est de réaliser une caractérisation exhaustive des paramètres acoustiques et aérodynamiques du bruit tonal de bord de fuite d'un profil et de produire une base de données qui pourra être utilisée pour valider les simulations numériques réalisées dans le futur. Le profil symétrique NACA-0012 ainsi que le profil asymétrique SD7003 ont été testés pour une série d'angles d'incidence (de -10° à 10°) dans la soufflerie anéchoïque à jet ouvert de l'Ecole Centrale de Lyon pour des nombres de Reynolds modérés (0.6x105 < Rec < 2.6x105). Les mesures de pression aux parois et de pression acoustique en champ lointain pour différentes configurations ont permis d'observer une structure en escalier de la signature du bruit, de déterminer quelle face du profil a produit le bruit et de distinguer le rôle de la boucle de rétroaction. Des techniques supplémentaires de post-traitement comme l'analyse temps-fréquence ont montré l'existence de plusieurs régimes (un régime de commutation entre deux états, un régime d'une seul fréquence et un régime à plusieurs fréquences) de l'émission de bruit. L'analyse de bi-cohérence a montré qu'il y a des couplages nonlinéaires entre les fréquences. Une étude par l'anémométrie à fil chaud et par des techniques de visualisation de l'écoulement a montré que la formation d'une bulle de décollement est une condition nécessaire mais pas suffisante pour la génération du bruit. De plus, la localisation de la bulle est aussi importante et elle doit être suffisamment proche du bord de fuite. En outre, l'analyse de stabilité linéaire des résultats de simulations numériques a montré que des ondes de Tollmien-Schlichting sont transformées en ondes de Kelvin-Helmholtz dans la zone du décollement. Une prédiction analytique de l'amplitude des fréquences pures émises dans le champ lointain a été effectuée sur la base du modèle d'Amiet en supposant que le champ de pression pariétal est bidimensionnel. Les mesures de pression proches du bord de fuite du profil ont été prises comme données d'entrée. Les amplitudes prédites sont globalement en accord avec les mesures acoustiques. Après l'analyse de tous les résultats la description suivante du processus de rayonnement de sons purs peut être proposée. Les ondes de Tollmien-Schlichting qui se développent initialement dans la couche limite se transforment en ondes de Kelvin-Helmholtz le long de la couche de cisaillement de la bulle de décollement. Au bord de fuite du profil elles sont converties en ondes acoustiques qui forment un couplage fort avec les instabilités de couche limite plus en amont de l'écoulement, pilotant elles-mêmes le déclenchement de ces instabilités
The tonal trailing-edge noise generated by transitional airfoils is a topic of interest because of its wide area of applications. One of them is the Unmanned Air Vehicles operated at low Reynolds numbers which are widely used in our everyday life and have a lot of perspectives in future. The tonal noise reduction will increase the survivability and effectiveness of the devices in military field. Moreover it will enlarge the range of civil use and minimize noise pollution. The effective noise reduction is needed and therefore the complete understanding of the tonal noise generation process is necessary. Despite the fact that investigation of the trailing-edge noise was started since the seventies there are still a lot of details which should be explained. The present work is dedicated to the experimental and analytical investigation of the tonal noise and is a part of the collaboration project between Ecole Centrale de Lyon and Embry-Riddle Aerospace University. The aim is to conduct an exhaustive experimental characterization of the acoustic and aerodynamic parameters of the trailing-edge noise and to produce a data base which can be used for further numerical simulations conducted at Embry-Riddle Aerospace University. A symmetric NACA-0012 airfoil and a slightly cambered SD7003 airfoil at moderate angles of attack (varied from -10° à 10°) were tested in an open-jet anechoic wind tunnel of Ecole Centrale de Lyon at moderate Reynolds numbers (0.6x105 < Rec < 2.6x105). Measurements of the wall pressure and far-field acoustic pressure in different configurations allowed to observe the ladder-type structure of the noise signature, to determine which side produced tones and to distinguish the role of the acoustic feedback loop. Additional post-processing techniques such as time-frequency analysis showed the existence of several regimes (switching regime between two tones, one-tone regime and multiple-tones regime) of noise emission. The bicoherence analysis showed that there are non-linear relationships between tones. The investigation of the role of the separation area by hot-wire anemometry and flow visualization techniques showed that the separation bubble is a necessary but not a suficient condition for the noise generation. Moreover the location of the bubble is also important and should be close enough to the trailing edge. Furthermore the linear stability analysis of accompanying numerical simulation results showed that the Tollmien-Schlichting waves transform to the Kelvin-Helmholtz waves at the separation area. An analytical prediction of the tone levels in the far-field was done using Amiet's model based on the assumption of perfectly correlated sources along the span. The wall-pressure measurements close to the trailing edge were used as an input data. The comparisons of the predicted levels and measured ones showed a good agreement. After analysis of all results the following description of the tonal noise mechanism is proposed. At some initial point of the airfoil the Tollmien-Schlichting instabilities start. They are traveling downstream and continued to Kelvin-Helmholtz waves along the shear-layer of the separation bubble. These waves reach the trailing edge, scatter from it as acoustic waves, which move upstream. The acoustic waves amplify the boundary layer instabilities at some frequencies for which the phases of both motions match and creates the feedback loop needed to sustain the process

Efter operation och anestesi får patienter ofta en negativ påverkan på magsäck och tarmar. Illamående och kräkningar är ett stort problem och många har svårt att komma igång med intag av föda och normal tarmfunktion då magsäcken och tarmarna ”står stilla”. Flera faktorer bidrar- bl.a. smärtan, det kirurgiska traumat och de läkemedel vi ger i samband med anestesin. Av de senare är opioider, d.v.s morfin och morfinliknande läkemedel, starkt bidragande. I detta avhandlings- arbete har opioiders effekter på magsäckens motilitet studerats. Med ett absorptionstest (paracetamolmetoden) studerades hos frivilliga hur opioiden remifentanil påverkar magsäckstömning och om kroppspositionen har betydelse för tömningshastigheten ut i tarmen. Remifentanil fördröjde magsäcks-tömningen och under pågående opioid behandling hade kroppspositionen ingen större betydelse, vilket det däremot hade under kontrollförsöken. Med samma metod jämförde vi hos patienter två anestesimetoder och studerade magsäcks-tömning direkt efter en operation. Ingen skillnad kunde påvisas mellan en opioidbaserad och en opioidfri anestesi, men inom respektive grupp var det en stor variation i magsäckstömning mellan individerna. Med en barostat studerades tonus i övre delen av magsäcken. Hos hälften av de frivilliga orsakade remifentanil en ökning av tonus och hos den andra hälften en minskning av tonus. Vidare undersöktes hos en grupp patienter opioiden fentanyls påverkan på den elektriska aktiviteten i magsäcken. Med en elekroga-strograf (EGG) registrerades de långsamma elektriska vågor som koordinerar muskelrörelserna i magsäcken. Hos hälften av de undersökta påverkades aktiviteten av fentanyl med en sänkt vågfrekvens eller upphörande av vågor, medan aktiviteten var opåverkad hos den övriga hälften. För att finna en förklaring till variationen gjordes genetiska analyser av genen för opioidreceptorn hos de undersökta i barostat och EGG studierna. Variationer i genomet, s.k. polymorfism, var inte associerad till utfallen i studierna. Studierna har visat på att opioider har en uttalad effekt på magsäckens motilitet och att den varierar kraftigt mellan individer. Polymorfism i genen för opioid- receptorn förklarade inte skillnaden mellan individer. Direkt efter operation bidrar sannolikt andra faktorer än anestesimetod till det variabla utfallet i magsäckstömning.
After anesthesia and/or surgical procedures, gastrointestinal motility is commonly impaired. The causes are multifactorial, with surgical trauma, pain and perioperative drugs playing a major role. This thesis explores opioid effects on gastric motility in healthy volunteers and patients undergoing surgery. Gastric emptying was studied by an absorption test (paracetamol method), and in healthy volunteers a remifentanil infusion delayed gastric emptying. Body position altered emptying during the control situations, but not during the remifentanil infusion. Further, two anesthetic methods were compared and no differences were found in immediate postoperative gastric emptying between a remifentanil/propofol based intravenous anesthesia and an opioid free inhalational anesthesia, although the interindividual variability was high. Proximal gastric tone was studied using a gastric barostat. An infusion of remifentanil caused two patterns of reaction regarding gastric tone, with half of the subjects increasing and half decreasing in gastric tone. Gastric myoelectrical activity was evaluated with electrogastrography (EGG), and a bolus dose of fentanyl caused a decrease in frequency of the gastric slow waves or disrupted this activity. However, the activity was unaffected in half of the investigated subjects. Analysis of polymorphisms (A118G and G691C) in the µ-opioid receptor gene was performed to find an explanation for the great interindividual variations seen in the barostat and EGG studies, but no association could be found. These studies have shown that opioids have pronounced effects on gastric motility with variable individual responses that are difficult to predict. Polymorphisms in the µ-opioid receptor gene could not explain the variations. Postoperatively, other factors might contribute more than opioids to the impairment in gastric motility.
ISSN 1652-4063

Good tone is one of an alto saxophone player's greatest assets and consequently deserves high priority in training and pedagogy. The current pedagogical literature gives little attention to tone production on the saxophone. The mouthpiece is the link between the player and the saxophone. This study examined the effect of the normal mouthpiece pitch and the pitch range produced on the saxophone mouthpiece on alto saxophone tone quality . In this experimental study, recordings were made of forty-three student alto saxophone players who performed tasks consisting of three saxophone mouthpiece exercises and four short musical phrases on the saxophone. The tape recordings were used to provide a spectral analysis of the tone samples by Fast Fourier Transform Analysis, and to allow qualitative analysis by five expert judges. The judges used a saxophone listening profile to provide qualitative evaluation of the recordings. Cluster analysis produced three groups of subjects according to combinations of the mouthpiece pitch and range produced. The mean sustained mouthpiece pitch and mouthpiece range of the groups were: Cluster 1 - 790 Hz and 550 cents; Cluster 2 1023 Hz and 150 cents: and Cluster 3 - 820 Hz and 1203 cents. Analysis of variance was used to test for statistically significant differences between the clusters. Discriminant analysis was used to identify other variables which contributed to the formation of the three clusters. The quantitative analysis of both mouthpiece and saxophone tones provided no insight into the spectra of the student subjects. The qualitative analysis using bipolar descriptors provided valid criteria which could be applied consistently for the analysis of student saxophone tone. A Tonal Index was computed from the judges' ratings in order to test for differences in tone between the clusters. Analysis of variance tests showed significant differences in the tone produced by the clusters on both the mouthpiece and the saxophone. The tone produced by Cluster 3 was significantly different to that produced by Clusters 1 and 2 at the p < .05 level. Discriminant analysis identified the use of saxophone tone models (through comparative critical listening) and small group performance as significant predictor variables (at the p < .05 level) in the formation of the clusters. The results of this study suggest that tone production on the alto saxophone is improved through the development of control on the mouthpiece. It was concluded that routine practice with the mouthpiece can serve in the development of a flexible and responsive embouchure and oral cavity and that students need to develop a mental concept of saxophone tone as part of the development of tone production. Also, experience in small group performance needs to be sought and provided for saxophone students. Finally, this study focussed on an area of mouthpiece behaviour which can easily be included into any instructional design and monitored by teachers.

Jia, Shiwei.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references (leaves 106-114).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.

Previous research has shown that feedback tone affects users' perceptions of computer systems. This study tested the generality of this finding and explored possible interactions of feedback tone with feedback validity and user gender. The task was a multiple cue probability learning (MCPL) problem. Experiment 1was used to establish an appropriate level of task difficulty and ensure the effectiveness of cognitive feedback. In Experiment 2, cognitive feedback validity and feedback tone were manipulated as within-subjects variables. Women improved substantially over blocks of trials in both tone conditions whereas men improved only in the polite condition. Most women preferred polite feedback whereas most men preferred the opposite. These results extend the range of tasks in which feedback tone has been shown to affect users' reactions to interfaces. These results suggest dissociation between performance and preference as men improved more with polite feedback although they preferred direct feedback.

碩士
國立臺灣藝術大學
圖文傳播藝術學系
98
The Tone Value Increase (TVI) Ratios of four process colors seems to be a constant number, according to literatures. The TVI Ratios in this study means the ratios of TVI of 50% divided by TVI of 75% and TVI of 50% divided by TVI 25%. In order to meet this condition, the printing process has to be consistent. Therefore, the TVI Ratios can be used as a factor to evaluate the consistency of the printing process. In addition, the correlation between TVI Ratios and solid ink density will be evaluated. This proposed research used Descriptive Statistics, Independent Sample T Test, One-way Analysis of Variance, One-way ANOVA, Regression Analysis and Correlational Analysis. This proposed research is to define the target value and the tolerance of the TVI Ratios using Kodak/Creo Maxtone to make eleven hybrid screen combinations for offset and flexo printing processes on coated paper, uncoated paper and PVC. The best combination of the printing process and the substrate that results in a constant TVI Ratios will then be found. The next step is to use the combination to make the correlation between TVI Ratios and solid ink density is tested. If the correlation is significant, a prediction model will be established. As a result, this model will provide printers an easy and a convenient method to control their printing process, and to improve the printing quality. Specifications of the TVI Ratios will then be established to obtain a consistent printing process and help printers in Taiwan expand their markets oversea. To sum up, printers could use 1.2572±0.046 = 0.570 +0.909 ×（B Trapping）-3.518×（Y Gray）or 1.2572±0.046 = 2.453 - 0.666 × ( M density ) to measure tone value increase conveniently. This is an efficient tool to inspect stability of dot reproduction in printing production.

Bien que les rêves dysphoriques, comme les mauvais rêves et les cauchemars, surviennent du moins occasionnellement chez la majorité des adultes, les facteurs impliqués dans l’occurrence de ces rêves, d’une nuit à l’autre, demeurent incertains. Par le biais d’un devis prospectif multiniveaux, nous avons étudié l’impact interactif des facteurs d’état et de trait sur l’occurrence de rêves dysphoriques d’une nuit à l’autre. Nous avons également exploré dans quelle mesure le contenu affectif et négatif des rêves de tous les jours était affecté par les mêmes facteurs. Des femmes adultes ont complété des mesures de trait de personnalité et de psychopathologie suivies de jusqu’à quatre semaines de journaux quotidiens de rêves et d’anxiété avant le coucher, ainsi que d’inventaires hebdomadaires de stress perçu. En contrôlant pour le rappel de rêve, une hausse hebdomadaire du stress perçu a significativement augmenté la probabilité d’avoir un rêve dysphorique une nuit donnée, alors que la psychopathologie a modéré positivement cette relation. Ces résultats suggèrent que les femmes adultes ayant un niveau plus élevé de psychopathologie seraient particulièrement sensibles au stress quotidien et donc plus susceptibles de faire des mauvais rêves ou cauchemars les nuits suivantes. Les analyses ont aussi révélé des effets positifs différentiels des variables d’état et de trait sur le contenu émotionnel et négatif des rêves de tous les jours. Ces résultats concordent avec le modèle neurocognitif des rêves dysphoriques proposé récemment et l’hypothèse de continuité des rêves. Les implications de cette étude et des recommandations futures sont émises.
Although disturbing dreams, such as bad dreams and nightmares, are experienced at least occasionally by a majority of adults, the factors involved in the night-by-night occurrence of these dreams remain unclear. Using a prospective design and multilevel modeling, we investigated the interactive impact of state and trait factors on the nightly occurrence of disturbing dreams. We further explored the extent to which emotionally intense and negative everyday dream content was affected by the same variables. Adult women completed measures of personality and psychopathology followed by up to four weeks of daily dream logs, daily pre-sleep anxiety logs, and weekly perceived stress inventories. After controlling for dream recall, upsurges in weekly perceived stress significantly increased the likelihood of having a disturbing dream on a given night, whereas psychopathology positively moderated that relationship. These results suggest that adult women reporting higher levels of psychopathology are particularly sensitive to everyday stress and thus more likely to experience bad dreams or nightmares on subsequent nights. Analyses also revealed differential positive effects of state and trait variables on the emotional and negative content of everyday dreams. These findings are in line with a recently proposed neurocognitive model of disturbed dreaming and the continuity hypothesis of dreaming. The implications of this study and future recommendations are emitted.

博士
長庚大學
臨床醫學研究所
94
The management of septic patients posts a professional challenge because of the reduction in systemic vascular resistance and the progressively diminished response to sympathomimetic pressor agents. The refractory hypotension remains a significant cause of morbidity and mortality in septic patients. Under physiological conditions, neurogenic vasomotor tone plays an important role in the maintenance of normal blood pressure. A better understanding of the regulatory machinery on neurogenic vasomotor tone during sepsis is therefore of vital importance. The integrity of rostral ventrolateral medulla (RVLM), bulbospinal tract, and intermediolateral cell column (IML) plays an important role in maintaining resting vasomotor tone. The vasomotor components of the systemic arterial pressure (SAP) spectrum reflect the activities of the sympathetic premotor neurons in RVLM, and the vasomotor signals are transmitted through activation of glutamate receptors on sympathetic preganglionic neurons (SPN) in IML. However, the relative contribution of the two major subtypes of glutamate receptors, NMDA and non-NMDA receptors, to the generation of neurogenic vasomotor tone under physiological conditions or during experimental endotoxemia is basically unknown. We addressed this issue by using a combination of physiological, pharmacological and double immunofluorescence approaches to delineate the relative contribution of NMDA and non-NMDA receptors on SPN to the generation of neurogenic vasomotor tone under physiological conditions and during experimental endotoxemia. For more accurate distribution of drugs over the specific IML region, a pre-implanted catheter in the thoracic subarachnoid space is mandatory. The currently available methods for catheterization of the thoracic spinal subarachnoid space in rats have been associated with relatively high postoperative mortality and morbidity. In our study, we developed a better method of catheterization. An intrathecal catheter was fabricated with a small silicon bead at one end of a PE-10 catheter, which was cannulated with a 4/0 suture that served as a guide. Using the L-shape hook of the suture guide as an anchorage, the catheter was advanced into the subarachnoid space until the silicon bead was lodged on a drilled hole (2 x 2 mm) over the lamina proper on the T13 vertebrae. The applicability of the implanted catheter was demonstrated by myelogram and pharmacological studies. Adult male Sprague-Dawley rats maintained under propofol anesthesia were used. Intrathecal administration of equimolar concentrations (75, 150 or 300 nmol) of a NMDA antagonist, dizocilpine (MK801) or a non-NMDA antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) into T10-T12 spinal cord elicited a reduction in resting vasomotor tone that was comparable in time-course and in magnitude. At the same time, both glutamate receptor antagonists exacerbated mortality and potentiated the elicited hypotension, bradycardia or reduction in vasomotor tone during experimental endotoxemia induced by intravenous administration of Escherichia coli lipopolysaccharide (30 mg/kg). Results comparable to CNQX at 150 nmol were obtained only when MK801 was given at 300 nmol. Confocal microscopy further showed that augmented immunoreactivity of NR1 subunit of the NMDA receptor on IML neurons coincided with the phase of endotoxemia when vasomotor tone was augmented; the immunoreactivity GluR1 subunit of the non-NMDA receptor remained stable throughout experimental endotoxemia. Correct localization and identification of SPN was crucial to the interpretation of our results. We thus have to be familiar with the location, morphology, and distribution of SPN in IML for accurate location of glutamate receptor expression on SPN. c-fos protein was induced in SPN through electrical stimulation to RVLM and visualized by immunohistochemical method. It was found that c-fos positive cells were not present in the spinal cord except within the IML region. We concluded that NMDA and non-NMDA receptors on IML neurons contribute equally to the generation of resting sympathetic vasomotor tone. However, upregulation of NMDA receptors on IML neurons plays a crucial role in the maintenance of vasomotor tone during endotoxemia.

L’amusie congénitale est un trouble neuro-développemental qui s’exprime par un déficit de discrimination tonale fine. Le cerveau des amusiques ne répond pas aux petites différences de hauteur, tel que révélé par l’absence de la composante de potentiel évoqué P3b, qui est associée aux processus de discrimination tonale tardifs et conscients. Peu d’études se sont penchées sur les mécanismes précoces et préconscients de discrimination tonale chez les amusiques, qui peuvent être étudiés par l’entremise d’une composante de potentiel évoqué appelée la négativité de discordance (MMN). Certaines études ont démontré qu’il est possible d’enregistrer la MMN pendant la présentation d’un film avec la trame sonore en simultané aux sons visant à évoquer la composante. Toutefois, une étude a démontré que la présentation de la trame sonore réduisait l’amplitude de la MMN, sans néanmoins clarifier la nature de l’effet d’interférence en cause. Les objectifs du présent projet sont d’abord, d’investiguer les effets à l’origine de la réduction d’amplitude de la MMN observée lors de la présentation d’un film avec la trame sonore, puis d’évaluer cette même composante chez les amusiques. La première étude visait à déterminer si un effet d’interférence attentionnelle ou acoustique était en cause dans la réduction d’amplitude observée sur la MMN lors de la présentation de la trame sonore d’un film. Les résultats ont montré qu’un effet de masquage acoustique, attribuable à la trame sonore, était responsable de la réduction d’amplitude de la MMN, cette dernière augmentant au fur et à mesure que l’intensité sonore de la trame du film était réduite. La seconde étude a été conduite dans le but d’investiguer la MMN chez les amusiques et de vérifier si le complexe d’ondes anormales N2b-P3b, observé en réponse aux grandes différences tonales chez les amusiques, pouvait être attribuable à un effet de saillance des stimuli. Dans un premier temps, nous avons comparé la MMN des amusiques à celle des contrôles, puis nous avons modifié le paradigme expérimental visant à évoquer la N2b-P3b en ajustant les probabilités d’occurrence des sons présentés aux contrôles en fonction des sons perçus par les amusiques. Les résultats ont montré que le cerveau des amusiques parvient à discriminer les différences de hauteur à un niveau précoce et préconscient, tel que révélé par une MMN normale, mais que les réponses cérébrales plus tardives, associées au processus de discrimination des hauteurs conscient, sont anormales chez les amusiques, et ce, uniquement pour les petites différences de hauteur, tel que révélé par l’absence de la P3b. En conclusion, ces résultats démontrent que l’amplitude de la MMN est affectée de manière significative par la présentation de la trame sonore d’un film et que cela est attribuable à un effet d’interférence acoustique. Dans un deuxième temps, nous avons démontré que les mécanismes précoces et préconscients de discrimination tonale sont préservés chez les amusiques, et que le déficit sous-jacent à l’amusie congénitale est attribuable à une atteinte du processus de discrimination tonale fine associé à un niveau de traitement cérébral tardif et conscient, le complexe d’ondes anormales N2b-P3b étant pour sa part attribuable à un effet de saillance des stimuli.
Congenital amusia is a neurodevelopmental disorder which is characterized by a deficit in fine-grained pitch discrimination. In fact, the amusic brain does not respond to small pitch changes, such as reflected by the absence of the event-related (ERP) component P3b, which is associated to late and conscious pitch discrimination processes. Until now, very few studies focused on early preconscious levels of processing in amusia, which can be studied through an ERP component called the mismatch negativity (MMN). Some studies have demonstrated that the MMN can be recorded while playing the soundtrack of a movie in concurrence with the MMN-critical tones. However, one study demonstrated that playing the movie soundtrack reduced MMN amplitude, but did not investigate the origin of this effect. The main goals of this project are, first, to investigate the nature of the effect responsible for the MMN reduction observed when playing a movie soundtrack, and secondly, to evaluate the MMN in congenital amusia. The first study aimed to investigate if an attentionnal or acoustical interference effect could account for the reduction in MMN amplitude observed when playing the movie soundtrack. The results showed that an acoustical masking effect of the movie soundtrack was responsible for the reduction in MMN amplitude. In fact, MMN amplitude increased as the intensity level of the movie soundtrack decreased. The goal of the second study was to investigate the MMN in congenital amusia, but also to explore if the abnormal N2b-P3b complex observed in amusics in a previous study could be accounted for by an effect of salience of the stimuli. Thus, we first compared the MMN results between amusics and controls, and then, we modified the experimental paradigm meant to evoke the N2b-P3b by adjusting the probabilities of occurrence of the sounds presented to the controls as a function of the sounds perceived by their matched amusics. The results showed that the amusic brain can detect all pitch changes at an early and preconscious level of processing, such as demonstrated by a normal MMN in both groups. Furthermore, our results showed that the amusic brain does not respond normally solely to small pitch changes at a later conscious level of processing, such as revealed by the absence of the P3b, thus showing that the abnormal N2b-P3b complex of ERP components observed in a previous study is better explained by a saliency effect of the stimuli and does not represent an electrophysiological anomaly specific to congenital amusia. In conclusion, our results have first shown that MMN amplitude is decreased by presenting a movie soundtrack and this is due to a masking effect at the acoustical level of the soundtrack over the MMN-critical tones. Finally, our second study showed that the early preconscious mechanisms of pitch discrimination are preserved in congenital amusia, and that the pitch deficit underlying congenital amusia is limited to an anomaly in the late and conscious processing of small pitch changes, the abnormal N2b-P3b complex being rather explained by an effect of salience of the stimuli.