Structure and function in primary open angle glaucoma

The study utilised a Normal group, an Ocular Hypertensive (OHT) group and a Primary Open Angle Glaucoma (POAG) group to investigate two aspects. Firstly, the within- and between-visit variability for stereometric measurements of the optic nerve head (ONH) using the Heidelberg Retina Tomograph (HRT); retinal nerve fibre layer (RNFL) thickness using the HRT and using optical coherence tomography with the Optical Coherence Tomography Scanner (OCT); the visual field using white-on-white (W-W), short-wavelength (SWAP) and Frequency Doubling perimetry (FDT); and retinal haemodynamics using the Heidelberg Retinal Flowmeter (HRF). Secondly, the association demonstrated between some of the derived variables. The within- and between-visit variability for stereometric measurements of the entire ONH and the between-visit variability for sectoral measurements were similar for Normals and OHTs but greater for POAGs. The within-visit variability of the visual field pointwise parameters for SWAP were greater than for W-W and FDT particularly with increase in eccentricity and for the OHT group. The between-visit variability increased with increase in defect depth for the POAG group, across all types of perimetry. The MS was greater, the MD and PSD smaller and the examination duration shorter in FDT compared to W-W and SWAP across all groups. The within-visit variability was less than the between-visit variability for the OCT circumferential and sector RNFL thickness using the 1.5R, 2.0R and the fixed 1.73mm circular scan radii, across the three groups. The variability increased with decrease in the RNFL thickness, and was least for the 2.0R scan radius.

Fabrication of high quality optical coherence tomography (OCT) calibration artefacts using femtosecond inscription

Optical coherence tomography (OCT) is a non-invasive three-dimensional imaging system that is capable of producing high resolution in-vivo images. OCT is approved for use in clinical trials in Japan, USA and Europe. For OCT to be used effectively in a clinical diagnosis, a method of standardisation is required to assess the performance across different systems. This standardisation can be implemented using highly accurate and reproducible artefacts for calibration at both installation and throughout the lifetime of a system. Femtosecond lasers can write highly reproducible and highly localised micro-structured calibration artefacts within a transparent media. We report on the fabrication of high quality OCT calibration artefacts in fused silica using a femtosecond laser. The calibration artefacts were written in fused silica due to its high purity and ability to withstand high energy femtosecond pulses. An Amplitude Systemes s-Pulse Yb:YAG femtosecond laser with an operating wavelength of 1026 nm was used to inscribe three dimensional patterns within the highly optically transmissive substrate. Four unique artefacts have been designed to measure a wide variety of parameters, including the points spread function (PSF), modulation transfer function (MTF), sensitivity, distortion and resolution - key parameters which define the performance of the OCT. The calibration artefacts have been characterised using an optical microscope and tested on a swept source OCT. The results demonstrate that the femtosecond laser inscribed artefacts have the potential of quantitatively and qualitatively validating the performance of any OCT system.

Three-dimensional calibration targets for optical coherence tomography

The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system and point-spread function of nanoparticles within the target was measured.

Three-dimensional calibration targets for optical coherence tomography

The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs pulse duration. A series of lines in depth were etched, varying the percentage of inscription energy and speed of the translation stage moving the target with respect to the laser. Samples were imaged with a dual wavelength spectral-domain OCT system and point-spread function of nanoparticles within the target was measured.

Are dyslexics' visual deficits limited to measures of dorsal stream function?

We tested the hypothesis that the differences in performance between developmental dyslexics and controls on visual tasks are specific for the detection of dynamic stimuli. We found that dyslexics were less sensitive than controls to coherent motion in dynamic random dot displays. However, their sensitivity to control measures of static visual form coherence was not significantly different from that of controls. This dissociation of dyslexics' performance on measures that are suggested to tap the sensitivity of different extrastriate visual areas provides evidence for an impairment specific to the detection of dynamic properties of global stimuli, perhaps resulting from selective deficits in dorsal stream functions. © 2001 Lippincott Williams & Wilkins.

Advances in characterisation, calibration and data processing speed of optical coherence tomography systems

This thesis describes advances in the characterisation, calibration and data processing of optical coherence tomography (OCT) systems. Femtosecond (fs) laser inscription was used for producing OCT-phantoms. Transparent materials are generally inert to infra-red radiations, but with fs lasers material modification occurs via non-linear processes when the highly focused light source interacts with the materials. This modification is confined to the focal volume and is highly reproducible. In order to select the best inscription parameters, combination of different inscription parameters were tested, using three fs laser systems, with different operating properties, on a variety of materials. This facilitated the understanding of the key characteristics of the produced structures with the aim of producing viable OCT-phantoms. Finally, OCT-phantoms were successfully designed and fabricated in fused silica. The use of these phantoms to characterise many properties (resolution, distortion, sensitivity decay, scan linearity) of an OCT system was demonstrated. Quantitative methods were developed to support the characterisation of an OCT system collecting images from phantoms and also to improve the quality of the OCT images. Characterisation methods include the measurement of the spatially variant resolution (point spread function (PSF) and modulation transfer function (MTF)), sensitivity and distortion. Processing of OCT data is a computer intensive process. Standard central processing unit (CPU) based processing might take several minutes to a few hours to process acquired data, thus data processing is a significant bottleneck. An alternative choice is to use expensive hardware-based processing such as field programmable gate arrays (FPGAs). However, recently graphics processing unit (GPU) based data processing methods have been developed to minimize this data processing and rendering time. These processing techniques include standard-processing methods which includes a set of algorithms to process the raw data (interference) obtained by the detector and generate A-scans. The work presented here describes accelerated data processing and post processing techniques for OCT systems. The GPU based processing developed, during the PhD, was later implemented into a custom built Fourier domain optical coherence tomography (FD-OCT) system. This system currently processes and renders data in real time. Processing throughput of this system is currently limited by the camera capture rate. OCTphantoms have been heavily used for the qualitative characterization and adjustment/ fine tuning of the operating conditions of OCT system. Currently, investigations are under way to characterize OCT systems using our phantoms. The work presented in this thesis demonstrate several novel techniques of fabricating OCT-phantoms and accelerating OCT data processing using GPUs. In the process of developing phantoms and quantitative methods, a thorough understanding and practical knowledge of OCT and fs laser processing systems was developed. This understanding leads to several novel pieces of research that are not only relevant to OCT but have broader importance. For example, extensive understanding of the properties of fs inscribed structures will be useful in other photonic application such as making of phase mask, wave guides and microfluidic channels. Acceleration of data processing with GPUs is also useful in other fields.

On the Coherence Between Probability and Possibility Measures

* This paper is supported by CICYT (Spain) under Project TIN 2005-08943-C02-01.

Formal function and phrase structure in contemporary music : Pierre Boulez’s late solo works and Sean Clarke’s "Lucretia Overture" and "4 Impromptus"

Cette thèse présente une théorie de la fonction formelle et de la structure des phrases dans la musique contemporaine, théorie qui peut être utilisée aussi bien comme outil analytique que pour créer de nouvelles œuvres. Deux concepts théoriques actuels aident à clarifier la structure des phrases : les projections temporelles de Christopher Hasty et la théorie des fonctions formelles de William Caplin, qui inclut le concept de l’organisation formelle soudée versus lâche (tight-knit vs. loose). Les projections temporelles sont perceptibles grâce à l’accent mis sur les paramètres secondaires, comme le style du jeu, l’articulation et le timbre. Des sections avec une organisation formelle soudée ont des projections temporelles claires, qui sont créées par la juxtaposition des motifs distincts, généralement sous la forme d'une idée de base en deux parties. Ces projections organisent la musique en phrases de présentation, en phrases de continuité et finalement, à des moments formels charnières, en phrases cadentielles. Les sections pourvues d’une organisation plus lâche tendent à présenter des projections et mouvements harmoniques moins clairs et moins d’uniformité motivique. La structure des phrases de trois pièces tardives pour instrument soliste de Pierre Boulez est analysée : Anthèmes I pour violon (1991-1992) et deux pièces pour piano, Incises (2001) et une page d’éphéméride (2005). Les idées proposées dans le présent document font suite à une analyse de ces œuvres et ont eu une forte influence sur mes propres compositions, en particulier Lucretia Overture pour orchestre et 4 Impromptus pour flûte, saxophone soprano et piano, qui sont également analysés en détail. Plusieurs techniques de composition supplémentaires peuvent être discernés dans ces deux œuvres, y compris l'utilisation de séquence mélodiques pour contrôler le rythme harmonique; des passages composés de plusieurs couches musicales chacun avec un structure de phrase distinct; et le relâchement de l'organisation formelle de matériels récurrents. Enfin, la composition de plusieurs autres travaux antérieurs a donné lieu à des techniques utilisées dans ces deux œuvres et ils sont brièvement abordés dans la section finale.

The interpersonal and mental health implications of the coherence of coming out narratives for a sample of gay men in committed romantic relationships

The coming out process has been conceptualized as a developmental imperative for those who will eventually accept their same-sex attractions. It is widely accepted that homophobia, heterosexism, and homonegativity are cultural realities that may complicate this developmental process for gay men. The current study views coming out as an extra-developmental life task that is at best a stressful event, and at worst traumatic when coming out results in the rupture of salient relationships with parents, siblings, and/or close friends. To date, the minority stress model (Meyer, 1995; 2003) has been utilized as an organizing framework for how to empirically examine external stressors and mental health disparities for lesbians, gay men, and bisexual individuals in the United States. The current study builds on this literature by focusing on the influence of how gay men make sense of and represent the coming out process in a semi-structured interview, more specifically, by examining the legacy of the coming out process on indicators of wellness. In a two-part process, this study first employs the framework well articulated in the adult attachment literature of coherence of narratives to explore both variation and implications of the coming out experience for a sample of gay men (n = 60) in romantic relationships (n = 30). In particular, this study employed constructs identified in the adult attachment literature, namely Preoccupied and Dismissing current state of mind, to code a Coming Out Interview (COI). In the present study current state of mind refers to the degree of coherent discourse produced about coming out experiences as relayed during the COI. Multilevel analyses tested the extent to which these COI dimensions, as revealed through an analysis of coming out narratives in the COI, were associated with relationship quality, including self-reported satisfaction and observed emotional tone in a standard laboratory interaction task and self-reported symptoms of psychopathology. In addition, multilevel analyses also assessed the Acceptance by primary relationship figures at the time of disclosure, as well as the degree of Outness at the time of the study. Results revealed that participant’s narratives on the COI varied with regard to Preoccupied and Dismissing current state of mind, suggesting that the AAI coding system provides a viable organizing framework for extracting meaning from coming out narratives as related to attachment relevant constructs. Multilevel modeling revealed construct validity of the attachment dimensions assessed via the COI; attachment (i.e., Preoccupied and Dismissing current state of mind) as assessed via the Adult Attachment Interview (AAI) was significantly correlated with the corresponding COI variables. These finding suggest both methodological and conceptual convergence between these two measures. However, with one exception, COI Preoccupied and Dismissing current state of mind did not predict relationship outcomes or self-reported internalizing and externalizing symptoms. However, further analyses revealed that the degree to which one is out to others moderated the relationship between COI Preoccupied and internalizing. Specifically, for those who were less out to others, there was a significant and positive relationship between Preoccupied current state of mind towards coming out and internalizing symptoms. In addition, the degree of perceived acceptance of sexual orientation by salient relationship figures at the time of disclosure emerged as a predictor of mental health. In particular, Acceptance was significantly negatively related to internalizing symptoms. Overall, the results offer preliminary support that gay men’s narratives do reflect variation as assessed by attachment dimensions and highlights the role of Acceptance by salient relationship figures at the time of disclosure. Still, for the most part, current state of mind towards coming out in this study was not associated with relationship quality and self-reported indicators of mental health. This finding may be a function of low statistical power given the modest sample size. However, the relationship between Preoccupied current state of mind and mental health (i.e., internalizing) appears to depend on degree of Outness. In addition, the response of primary relationships figures to coming out may be a relevant factor in shaping mental health outcomes for gay men. Limitations and suggestions for future research and clinical intervention are offered.

Formal function and phrase structure in contemporary music : Pierre Boulez’s late solo works and Sean Clarke’s "Lucretia Overture" and "4 Impromptus"

Cette thèse présente une théorie de la fonction formelle et de la structure des phrases dans la musique contemporaine, théorie qui peut être utilisée aussi bien comme outil analytique que pour créer de nouvelles œuvres. Deux concepts théoriques actuels aident à clarifier la structure des phrases : les projections temporelles de Christopher Hasty et la théorie des fonctions formelles de William Caplin, qui inclut le concept de l’organisation formelle soudée versus lâche (tight-knit vs. loose). Les projections temporelles sont perceptibles grâce à l’accent mis sur les paramètres secondaires, comme le style du jeu, l’articulation et le timbre. Des sections avec une organisation formelle soudée ont des projections temporelles claires, qui sont créées par la juxtaposition des motifs distincts, généralement sous la forme d'une idée de base en deux parties. Ces projections organisent la musique en phrases de présentation, en phrases de continuité et finalement, à des moments formels charnières, en phrases cadentielles. Les sections pourvues d’une organisation plus lâche tendent à présenter des projections et mouvements harmoniques moins clairs et moins d’uniformité motivique. La structure des phrases de trois pièces tardives pour instrument soliste de Pierre Boulez est analysée : Anthèmes I pour violon (1991-1992) et deux pièces pour piano, Incises (2001) et une page d’éphéméride (2005). Les idées proposées dans le présent document font suite à une analyse de ces œuvres et ont eu une forte influence sur mes propres compositions, en particulier Lucretia Overture pour orchestre et 4 Impromptus pour flûte, saxophone soprano et piano, qui sont également analysés en détail. Plusieurs techniques de composition supplémentaires peuvent être discernés dans ces deux œuvres, y compris l'utilisation de séquence mélodiques pour contrôler le rythme harmonique; des passages composés de plusieurs couches musicales chacun avec un structure de phrase distinct; et le relâchement de l'organisation formelle de matériels récurrents. Enfin, la composition de plusieurs autres travaux antérieurs a donné lieu à des techniques utilisées dans ces deux œuvres et ils sont brièvement abordés dans la section finale.

Russian social networks on the web: cohesion and coherence in Vkontakte

In this thesis connections between messages on the public wall of the Russian social network Vkontakte are analysed and classified. A total of 1818 messages from three different Vkontakte groups were collected and analysed according to a new framework based on Halliday and Hasan’s (1976) research into cohesion and Simmons’s (1981) adaptation of their classification for Russian. The two categories of textuality, cohesion and coherence, describe the linguistic connections between messages. The main aim was to find out how far the traditional categories of cohesion are applicable to an online social network including written text as well as multimedia-files. In addition to linguistic cohesion the pragmatic and topic coherence between Vkontakte messages was also analysed. The analysis of pragmatic coherence classifies the messages with acts according to their pragmatic function in relation to surrounding messages. Topic coherence analyses the content of the messages, describes where a topic begins, changes or is abandoned. Linguistic cohesion, topic coherence and pragmatic coherence enable three different types of connections between messages and these together form a coherent communication on the message wall. The cohesion devices identified by Halliday and Hasan and Simmons were found to occur in these texts, but additional devices were also identified: these are multimodal, graphical and grammatical cohesion.

Relationship Between Orofacial Function, Dentofacial Morphology, And Bite Force In Young Subjects.

The aim was to evaluate the relationship between orofacial function, dentofacial morphology, and bite force in young subjects. Three hundred and sixteen subjects were divided according to dentition stage (early, intermediate, and late mixed and permanent dentition). Orofacial function was screened using the Nordic Orofacial Test-Screening (NOT-S). Orthodontic treatment need, bite force, lateral and frontal craniofacial dimensions and presence of sleep bruxism were also assessed. The results were submitted to descriptive statistics, normality and correlation tests, analysis of variance, and multiple linear regression to test the relationship between NOT-S scores and the studied independent variables. The variance of NOT-S scores between groups was not significant. The evaluation of the variables that significantly contributed to NOT-S scores variation showed that age and presence of bruxism related to higher NOT-S total scores, while the increase in overbite measurement and presence of closed lip posture related to lower scores. Bite force did not show a significant relationship with scores of orofacial dysfunction. No significant correlations between craniofacial dimensions and NOT-S scores were observed. Age and sleep bruxism were related to higher NOT-S scores, while the increase in overbite measurement and closed lip posture contributed to lower scores of orofacial dysfunction.

Impaired Compensatory Beta-cell Function And Growth In Response To High-fat Diet In Ldl Receptor Knockout Mice.

In this study, we investigated the effect of low density lipoprotein receptor (LDLr) deficiency on gap junctional connexin 36 (Cx36) islet content and on the functional and growth response of pancreatic beta-cells in C57BL/6 mice fed a high-fat (HF) diet. After 60 days on regular or HF diet, the metabolic state and morphometric islet parameters of wild-type (WT) and LDLr-/- mice were assessed. HF diet-fed WT animals became obese and hypercholesterolaemic as well as hyperglycaemic, hyperinsulinaemic, glucose intolerant and insulin resistant, characterizing them as prediabetic. Also they showed a significant decrease in beta-cell secretory response to glucose. Overall, LDLr-/- mice displayed greater susceptibility to HF diet as judged by their marked cholesterolaemia, intolerance to glucose and pronounced decrease in glucose-stimulated insulin secretion. HF diet induced similarly in WT and LDLr-/- mice, a significant decrease in Cx36 beta-cell content as revealed by immunoblotting. Prediabetic WT mice displayed marked increase in beta-cell mass mainly due to beta-cell hypertrophy/replication. Nevertheless, HF diet-fed LDLr-/- mice showed no significant changes in beta-cell mass, but lower islet-duct association (neogenesis) and higher beta-cell apoptosis index were seen as compared to controls. The higher metabolic susceptibility to HF diet of LDLr-/- mice may be explained by a deficiency in insulin secretory response to glucose associated with lack of compensatory beta-cell expansion.

Long-term Postoperative Atrophy Of Contralateral Hippocampus And Cognitive Function In Unilateral Refractory Mtle With Unilateral Hippocampal Sclerosis.

This study aimed to evaluate long-term atrophy in contralateral hippocampal volume after surgery for unilateral MTLE, as well as the cognitive outcome for patients submitted to either selective transsylvian amygdalohippocampectomy (SelAH) or anterior temporal lobe resection (ATL). We performed a longitudinal study of 47 patients with MRI signs of unilateral hippocampal sclerosis (23 patients with right-sided hippocampal sclerosis) who underwent surgical treatment for MTLE. They underwent preoperative/postoperative high-resolution MRI as well as neuropsychological assessment for memory and estimated IQ. To investigate possible changes in the contralateral hippocampus of patients, we included 28 controls who underwent two MRIs at long-term intervals. The volumetry using preoperative MRI showed significant hippocampal atrophy ipsilateral to the side of surgery when compared with controls (p<0.0001) but no differences in contralateral hippocampal volumes. The mean postoperative follow-up was 8.7 years (± 2.5 SD; median=8.0). Our patients were classified as Engel I (80%), Engel II (18.2%), and Engel III (1.8%). We observed a small but significant reduction in the contralateral hippocampus of patients but no volume changes in controls. Most of the patients presented small declines in both estimated IQ and memory, which were more pronounced in patients with left TLE and in those with persistent seizures. Different surgical approaches did not impose differences in seizure control or in cognitive outcome. We observed small declines in cognitive scores with most of these patients, which were worse in patients with left-sided resection and in those who continued to suffer from postoperative seizures. We also demonstrated that manual volumetry can reveal a reduction in volume in the contralateral hippocampus, although this change was mild and could not be detected by visual analysis. These new findings suggest that dynamic processes continue to act after the removal of the hippocampus, and further studies with larger groups may help in understanding the underlying mechanisms.

Doehlert Design-desirability Function Multi-criteria Optimal Separation Of 17 Phenolic Compounds From Extra-virgin Olive Oil By Capillary Zone Electrophoresis.

In Brazil, the consumption of extra-virgin olive oil (EVOO) is increasing annually, but there are no experimental studies concerning the phenolic compound contents of commercial EVOO. The aim of this work was to optimise the separation of 17 phenolic compounds already detected in EVOO. A Doehlert matrix experimental design was used, evaluating the effects of pH and electrolyte concentration. Resolution, runtime and migration time relative standard deviation values were evaluated. Derringer's desirability function was used to simultaneously optimise all 37 responses. The 17 peaks were separated in 19min using a fused-silica capillary (50μm internal diameter, 72cm of effective length) with an extended light path and 101.3mmolL(-1) of boric acid electrolyte (pH 9.15, 30kV). The method was validated and applied to 15 EVOO samples found in Brazilian supermarkets.