834 resultados para Eye pattern


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We conducted a genome-wide association study for androgenic alopecia in 1,125 men and identified a newly associated locus at chromosome 20p11.22, confirmed in three independent cohorts (n = 1,650; OR = 1.60, P = 1.1 x 10(-14) for rs1160312). The one man in seven who harbors risk alleles at both 20p11.22 and AR (encoding the androgen receptor) has a sevenfold-increased odds of androgenic alopecia (OR = 7.12, P = 3.7 x 10(-15)).

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We analyze the dynamics of a transient pattern formation in the Fréedericksz transition corresponding to a twist geometry. We present a calculation of the time-dependent structure factor based on a dynamical model which incorporates consistently the coupling of the director field with the velocity flow and also the effect of fluctuations. The appearance and development of a characteristic periodicity is described in terms of the time dependence of the maximum of the structure factor. We find a well-defined time for the appearance of the pattern and a subsequent stage of pattern development in which the characteristic periodicity tends to an asymptotic value.

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A nonlinear calculation of the dynamics of transient pattern formation in the Fréedericksz transition is presented. A Gaussian decoupling is used to calculate the time dependence of the structure factor. The calculation confirms the range of validity of linear calculations argued in earlier work. In addition, it describes the decay of the transient pattern.

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BACKGROUND: MR tissue tagging allows the noninvasive assessment of the locally and temporally resolved motion pattern of the left ventricle. Alterations in cardiac torsion and diastolic relaxation of the left ventricle were studied in patients with aortic stenosis and were compared with those of healthy control subjects and championship rowers with physiological volume-overload hypertrophy. METHODS AND RESULTS: Twelve aortic stenosis patients, 11 healthy control subjects with normal left ventricular function, and 11 world-championship rowers were investigated for systolic and diastolic heart wall motion on a basal and an apical level of the myocardium. Systolic torsion and untwisting during diastole were examined by use of a novel tagging technique (CSPAMM) that provides access to systolic and diastolic motion data. In the healthy heart, the left ventricle performs a systolic wringing motion, with a counterclockwise rotation at the apex and a clockwise rotation at the base. Apical untwisting precedes diastolic filling. In the athlete's heart, torsion and untwisting remain unchanged compared with those of the control subjects. In aortic stenosis patients, torsion is significantly increased and diastolic apical untwisting is prolonged compared with those of control subjects or athletes. CONCLUSIONS: Torsional behavior as observed in pressure- and volume-overloaded hearts is consistent with current theoretical findings. A delayed diastolic untwisting in the pressure-overloaded hearts of the patients may contribute to a tendency toward diastolic dysfunction.

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Objectives : Eye movements are necessary to stabilize the retinal picture and to find a new object. This seems useless for blind people, so why do they nevertheless have them. We report on an EOG study on 29 blind volunteers and 5 volunteers with closed eyes. Material and methods: We recorded eye movements by EOG and let the volunteers fulfill different exercises by following an acoustic running point by gaze, pointing, imagining in the room, listing words that begin with the vocal U and a finger labyrinth. Results: We found slow eye movements as well as pathological eye movements in the blind subjects. We found that blind subjects have a horizontal preferency.The duration of fixation of pictures is shorter in the blind subjects. The blind could even modulate saccade amplitudes . Discussion: Eye movements seem to be structural properties of the brain which prepare the organism for certain situations-even if they do not take place. We think that eye movements are partially independent of the experience of view. We did not expect that the blind subjects could modify gaze according to the subject. This leads to the hypothesis of a preformed dimensional system.

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AIMS: In patients with alcohol dependence, health-related quality of life (QOL) is reduced compared with that of a normal healthy population. The objective of the current analysis was to describe the evolution of health-related QOL in adults with alcohol dependence during a 24-month period after initial assessment for alcohol-related treatment in a routine practice setting, and its relation to drinking pattern which was evaluated across clusters based on the predominant pattern of alcohol use, set against the influence of baseline variables METHODS: The Medical Outcomes Study 36-Item Short-Form Survey (MOS-SF-36) was used to measure QOL at baseline and quarterly for 2 years among participants in CONTROL, a prospective observational study of patients initiating treatment for alcohol dependence. The sample consisted of 160 adults with alcohol dependence (65.6% males) with a mean (SD) age of 45.6 (12.0) years. Alcohol use data were collected using TimeLine Follow-Back. Based on the participant's reported alcohol use, three clusters were identified: 52 (32.5%) mostly abstainers, 64 (40.0%) mostly moderate drinkers and 44 (27.5%) mostly heavy drinkers. Mixed-effect linear regression analysis was used to identify factors that were potentially associated with the mental and physical summary MOS-SF-36 scores at each time point. RESULTS: The mean (SD) MOS-SF-36 mental component summary score (range 0-100, norm 50) was 35.7 (13.6) at baseline [mostly abstainers: 40.4 (14.6); mostly moderate drinkers 35.6 (12.4); mostly heavy drinkers 30.1 (12.1)]. The score improved to 43.1 (13.4) at 3 months [mostly abstainers: 47.4 (12.3); mostly moderate drinkers 44.2 (12.7); mostly heavy drinkers 35.1 (12.9)], to 47.3 (11.4) at 12 months [mostly abstainers: 51.7 (9.7); mostly moderate drinkers 44.8 (11.9); mostly heavy drinkers 44.1 (11.3)], and to 46.6 (11.1) at 24 months [mostly abstainers: 49.2 (11.6); mostly moderate drinkers 45.7 (11.9); mostly heavy drinkers 43.7 (8.8)]. Mixed-effect linear regression multivariate analyses indicated that there was a significant association between a lower 2-year follow-up MOS-SF-36 mental score and being a mostly heavy drinker (-6.97, P < 0.001) or mostly moderate drinker (-3.34 points, P = 0.018) [compared to mostly abstainers], being female (-3.73, P = 0.004), and having a Beck Inventory scale score ≥8 (-6.54, P < 0.001), at baseline. The mean (SD) MOS-SF-36 physical component summary score was 48.8 (10.6) at baseline, remained stable over the follow-up and did not differ across the three clusters. Mixed-effect linear regression univariate analyses found that the average 2-year follow-up MOS-SF-36 physical score was increased (compared with mostly abstainers) in mostly heavy drinkers (+4.44, P = 0.007); no other variables tested influenced the MOS-SF-36 physical score. CONCLUSION: Among individuals with alcohol dependence, a rapid improvement was seen in the mental dimension of QOL following treatment initiation, which was maintained during 24 months. Improvement was associated with the pattern of alcohol use, becoming close to the general population norm in patients classified as mostly abstainers, improving substantially in mostly moderate drinkers and improving only slightly in mostly heavy drinkers. The physical dimension of QOL was generally in the normal range but was not associated with drinking patterns.

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The function of sleep remains unknown. To gain insight into the function of sleep in natural conditions, I assessed variation in sleep architecture and its link with fitness-related phenotypic traits. I considered melanin-based coloration because its underlying genetic basis is very well known giving an opportunity to examine whether some genes pleiotropically regulate both coloration and sleep. The melanocortin system is known to generate covariation between melanin-based coloration and other phenotypes like behaviour, physiology and life history traits. I investigated whether this system of genes could participate in the co-expression of coloration and sleep. I carried out a study with nestling barn owls (Tyto alba) in order to tackle the potential link between variation in color traits and the ontogeny of sleep under natural conditions. For this I established a suitable method for recording the brain activity (electroencephalogram) of owls in nature. Birds are especially interesting, because they convergently evolved sleep states similar to those exhibited by mammals. As in mammals, I found that in owlets time spent in rapid eye movement (REM) sleep declines with age, a relationship thought to eflect developmental changes in the brain. Thus this developmental trajectory appears to reflect a fundamental feature of sleep. Additionally, I discovered an association between a gene involved in melanism expressed in the feather follicles (proprotein convertase subtilisin/kexin type 2, PCSK2) and the age-related changes in sleep in the brain. Nestlings with higher expression levels of PCSK2 showed a more precocial pattern of sleep development and a higher degree of melanin-based coloration compared to nestlings with lower PCSK2 expression. Also sleep architecture and the development of rhythmicity in brain and physical activity was related to plumage traits of the nestlings and their biological parents. This pattern during ontogeny might reflect differences in life l history strategies, antipredator behaviour and developmental pace. Therefore, differently colored individuals may differentially deal with trade-offs between the costs and benefits of sleep which in turn lead to differences in brain organization and ultimately fitness. These results should stimulate evolutionary biologists to consider sleep as a major life history trait. Résumé La fonction du sommeil reste inconnue. Afin d'acquérir une meilleur compréhension de la fonction du sommeil dans les conditions naturelles, j'ai analysé la variation dans l'architecture du sommeil et son lien avec d'autres traits phénotypiques liés au succès reproducteur (fitness). J'ai choisi et examiné la coloration mélanique, car ses bases génétiques sont bien connues et il est ainsi possible d'étudier si certains gènes, de façon pléiotropique régulent à la fois la coloration et le sommeil. J'ai exploré si ce système génétique était impliqué dans la co-expression de la coloration et du sommeil. J'ai effectué mon étude sur des poussins de chouette effraie (Tyto alba) en condition naturelle, pour rechercher ce lien potentiel entre la variation de la coloration et l'ontogenèse du sommeil. Dans ce but, j'ai établi une méthodologie permettant d'enregistrer l'activité cérébrale (électroencéphalogramme) des chouettes dans la nature. Les oiseaux sont particulièrement intéressants car ils ont développé, par évolution convergente, des phases de sommeil similaires à celles des mammifères. De manière semblable à ce qui a été montré chez les mammifères, j'ai découvert que le temps passé dans le sommeil paradoxal diminue avec l'âge des poussins. On pense que ceci est dû aux changements développementaux au niveau du cerveau. Cette trajectoire développementale semble refléter une caractéristique fondamentale du sommeil. J'ai également découvert une association entre l'un des gènes impliqué dans le mélanisme, exprimé dans les follicules plumeux (proprotein convertase subtilisin/kexin type 2, PCSK2), et les changements dans la structure du sommeil avec l'âge. Les poussins ayant un niveau d'expression génétique élevé de la PCSK2 présentent une structure du sommeil plus précoce et un taux de coloration dû à la mélanine plus élevé que des poussins avec un niveau d'expression moindre de la PCSK2. L'architecture du sommeil et le développement de la rythmicité dans le cerveau ainsi que l'activité physique sont également liés à la coloration des plumes des poussins et pourraient ainsi refléter des différences de stratégies d'histoire de vie, de comportements anti-prédateur et de vitesses développementales. Ainsi, des individus de coloration différente sembleraient traiter différemment les coûts et les bénéfices du sommeil, ce qui aurait des conséquences sur l'organisation cérébrale et pour finir, sur le succès reproducteur. Ces résultats devraient encourager les biologistes évolutionnistes à considérer le sommeil comme un important trait d'histoire de vie. Zusammenfassung Die Funktion von Schlaf ist noch unbekannt. Um mehr Einsicht in diese unter natürlichen Bedingungen zu bekommen, habe ich die Variation in der Schlafarchitektur und die Verknüpfung mit phänotypischen Merkmalen, die mit der Fitness zusammenhängen, studiert. Ich habe mir melanin-basierte Färbung angesehen, da die zugrunde liegende genetische Basis bekannt ist und somit die Möglichkeit gegeben ist, zu untersuchen, ob einige Gene beides regulieren, Färbung und Schlaf. Das melanocortin System generiert eine Kovariation zwischen melanin-basierter Färbung und anderen phänotypischer Merkmale wie Verhalten, Physiologie und Überlebensstrategien. Ich habe untersucht, ob dieses Gensystem an einer gleichzeitigen Steuerung von Färbung und Schlaf beteiligt ist. Dazu habe ich Schleiereulen (Tyto alba) studiert um einen möglichen Zusammenhang zwischen der Variation in der Pigmentierung und der Entwicklung des Schlafs unter natürlichen Bedingungen zu entdecken. Für diese Studie entwickelte ich eine Methode um die Gehirnaktivität (Elektroenzephalogramm) bei Eulen in der Natur aufzunehmen. Vögel sind besonders interessant, da sie die gleichen Schlafstadien aufweisen wie Säugetiere und diese unabhängig konvergent entwickelt haben. Genauso wie bei Säugetieren nahm die Dauer des sogenannten ,,rapid eye movement" (REM) - Schlafes mit zunehmendem Alter ab. Es wird angenommen, dass dieser Zusammenhang die Entwicklung des Gehirns widerspiegelt. Daher scheint dieses Entwicklungsmuster ein fundamentaler Aspekt von Schlaf zu sein. Zusätzlich entdeckte ich einen Zusammenhang zwischen der Aktivität eines Gens in den Federfollikeln (proprotein convertase subtilisin/kexin type 2, PCSK2), das für die Ausprägung schwarzer Punkte auf den Federn der Eulen verantwortlich ist, und den altersabhängigen Änderungen im Schlafmuster im Gehirn. Küken mit höherer Aktivität von PCSK2 zeigten eine frühreifere Schlafentwicklung und eine dunklere Färbung als Küken mit niedriger PCSK2 Aktivität. Die Architekture des Schlafes und die Entwicklung der Rhythmik im Gehirn und die der physischen Aktivität ist mit der Färbung des Gefieders von den Küken und ihren Eltern verknüpft. Dieses Muster während der Entwicklung kann Unterschiede in Überlebensstrategien, Feindabwehrverhalten und in der Entwicklungsgeschwindigkeit reflektieren. Unterschiedlich gefärbte Individuen könnten unterschiedliche Strategien haben um zwischen den Kosten und Nutzen von Schlaf zu entscheiden, was zu Unterschieden in der Gehirnstruktur führen kann und letztendlich zur Fitness. Diese Ergebnisse sollten Evolutionsbiologen stimulieren Schlaf als einen wichtigen Bestandteil des Lebens zu behandeln.

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Structural settings and lithological characteristics are traditionally assumed to influence the development of erosional landforms, such as gully networks and rock couloirs, in steep mountain rock basins. The structural control of erosion of two small alpine catchments of distinctive rock types is evaluated by comparing the correspondences between the orientations of their gullies and rock couloirs with (1) the sliding orientations of potential slope failures mechanisms, and (2) the orientation of the maximum joint frequency, this latter being considered as the direction exploited primarily by erosion and mass wasting processes. These characteristic orientations can be interpreted as structural weaknesses contributing to the initiation and propagation of erosion. The morphostructural analysis was performed using digital elevation models and field observations. The catchment comprised of magmatic intrusive rocks shows a clear structural control, mostly expressed through potential wedges failure. Such joint configurations have a particular geometry that encourages the development of gullies in hard rock, e.g. through enhanced gravitational and hydrological erosional processes. In the catchment underlain by sedimentary rocks, penetrative joints that act as structural weaknesses seem to be exploited by gullies and rock couloirs. However, the lithological setting and bedding configuration prominently control the development of erosional landforms, and influence not only the local pattern of geomorphic features, but the general morphology of the catchment. The orientations of the maximum joint frequency are clearly associated with the gully network, suggesting that its development is governed by anisotropy in rock strength. These two catchments are typical of bedrock-dominated basins prone to intense processes of debris supply. This study suggests a quantitative approach for describing the relationship between bedrock jointing and geomorphic features geometry. Incorporation of bedrock structure can be relevant when studying processes governing the transfer of clastic material, for the assessment of sediment yields and in landforms evolution models.

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Retinaldehyde, an intermediate metabolite between vitamin A and retinoic acid, is present at biologically active concentrations in fat tissue, where it antagonizes PPAR- activity, inhibiting adipogenesis and improving insulin sensitivity.

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PURPOSE: Ocular anatomy and radiation-associated toxicities provide unique challenges for external beam radiation therapy. For treatment planning, precise modeling of organs at risk and tumor volume are crucial. Development of a precise eye model and automatic adaptation of this model to patients' anatomy remain problematic because of organ shape variability. This work introduces the application of a 3-dimensional (3D) statistical shape model as a novel method for precise eye modeling for external beam radiation therapy of intraocular tumors. METHODS AND MATERIALS: Manual and automatic segmentations were compared for 17 patients, based on head computed tomography (CT) volume scans. A 3D statistical shape model of the cornea, lens, and sclera as well as of the optic disc position was developed. Furthermore, an active shape model was built to enable automatic fitting of the eye model to CT slice stacks. Cross-validation was performed based on leave-one-out tests for all training shapes by measuring dice coefficients and mean segmentation errors between automatic segmentation and manual segmentation by an expert. RESULTS: Cross-validation revealed a dice similarity of 95% ± 2% for the sclera and cornea and 91% ± 2% for the lens. Overall, mean segmentation error was found to be 0.3 ± 0.1 mm. Average segmentation time was 14 ± 2 s on a standard personal computer. CONCLUSIONS: Our results show that the solution presented outperforms state-of-the-art methods in terms of accuracy, reliability, and robustness. Moreover, the eye model shape as well as its variability is learned from a training set rather than by making shape assumptions (eg, as with the spherical or elliptical model). Therefore, the model appears to be capable of modeling nonspherically and nonelliptically shaped eyes.

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AIM: To determine the extent drinking patterns (at the individual and country level) are associated with alcohol-related consequences over and above the total alcohol the person consumes. METHODS: Hierarchical linear models were estimated based on general population surveys conducted in 18 countries participating in the GENACIS project. RESULTS: In general, the positive association between drinking pattern scores and alcohol-related consequences was found at both the individual and country levels, independent of volume of drinking. In addition, a significant interaction effect indicated that the more detrimental the country's drinking pattern, the less steep the association between the volume of drinking and its consequences. CONCLUSION: Drinking patterns have an independent impact on consequences over and above the relationship between volume and consequences.

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Dysploidy and polyploidy are well documented in the large genus Centaurea, especially in sect. Acrocentron and in a small group of species from the Iberian Peninsula described as sect. Chamaecyanus, closely related to Acrocentron. We have explored two interesting cases of polyploid series in both sections: the polyploid series of Centaurea toletana in sect. Chamaecyanus and the series of C. ornata group in sect. Acrocentron. We have carried out a karyological study using both classic karyotype analyses and chromosome banding with fluorochromes.

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Light-emitting diodes (LEDs) are taking an increasing place in the market of domestic lighting because they produce light with low energy consumption. In the EU, by 2016, no traditional incandescent light sources will be available and LEDs may become the major domestic light sources. Due to specific spectral and energetic characteristics of white LEDs as compared to other domestic light sources, some concerns have been raised regarding their safety for human health and particularly potential harmful risks for the eye. To conduct a health risk assessment on systems using LEDs, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), a public body reporting to the French Ministers for ecology, for health and for employment, has organized a task group. This group consisted physicists, lighting and metrology specialists, retinal biologist and ophthalmologist who have worked together for a year. Part of this work has comprised the evaluation of group risks of different white LEDs commercialized on the French market, according to the standards and found that some of these lights belonged to the group risk 1 or 2. This paper gives a comprehensive analysis of the potential risks of white LEDs, taking into account pre-clinical knowledge as well as epidemiologic studies and reports the French Agency's recommendations to avoid potential retinal hazards.