A High-Order Scheme for Image Segmentation via a modified Level-Set method

In this paper we propose a high-order accurate scheme for image segmentation based on the level-set method. In this approach, the curve evolution is described as the 0-level set of a representation function but we modify the velocity that drives the curve to the boundary of the object in order to obtain a new velocity with additional properties that are extremely useful to develop a more stable high-order approximation with a small additional cost. The approximation scheme proposed here is the first 2D version of an adaptive "filtered" scheme recently introduced and analyzed by the authors in 1D. This approach is interesting since the implementation of the filtered scheme is rather efficient and easy. The scheme combines two building blocks (a monotone scheme and a high-order scheme) via a filter function and smoothness indicators that allow to detect the regularity of the approximate solution adapting the scheme in an automatic way. Some numerical tests on synthetic and real images confirm the accuracy of the proposed method and the advantages given by the new velocity.Comment: Accepted version for publication in SIAM Journal on Imaging Sciences, 86 figure

The genetics of adaptive photoperiodic response in Nasonia vitripennis

De seizoencyclus veroorzaakt periodieke omgevingsveranderingen. Hoe verder verwijderd van de evenaar (toenemende breedtegraad) hoe groter de veranderingen, in bijvoorbeeld temperatuur en daglicht, waar levensvormen mee moeten kunnen omgaan. Organismen hebben verscheidene manieren ontwikkeld om deze veranderende omgevingsfactoren te overleven. Een voorbeeld is Nasonia vitripennis, een parasitaire wesp die op verschillende breedtegraden voorkomt. Volwassen vrouwtjes van deze wesp gebruiken de lengte van de dag als een aanwijzing om komende seizoensveranderingen te “voorspellen”. Als de dagen korter worden, leggen ze eitjes die zich tot larven ontwikkelen, die een soort winterslaap beginnen die “diapause” wordt genoemd. In mijn promotieproject heb ik de evolutionaire basis van deze seizoensaanpassing onderzocht. Nadat ik wespenpopulaties van Finland (hoge breedtegraad) tot Zuid Frankrijk (lage breedtegraad) had bemonsterd, stelde ik vrouwtjeswespen bloot aan verschillende daglichtcondities en bekeek de hoeveelheid diapause onder hun nakomelingen. De proeven toonden aan dat een relatief groot aantal vrouwtjes in de noordelijke populaties diapause induceren in hun nakomelingen. Bovendien wordt diapause, vergeleken met zuidelijke populaties, bij relatief langere dagen geïnduceerd. Dit duidt er op dat de aanpassing van wespen gebaseerd is op hun verschil in “interpretatie” van het lichtsignaal en weerspiegelt het feit dat op hogere breedtegraden de winter begint als de dagen nog redelijk lang zijn. Verder onderzoek toonde aan dat een gen, genaamd period betrokken is bij deze respons. Het is interessant dat van dit gen bekend is dat het mede verantwoordelijk is voor het dag-en-nacht ritme, niet alleen van wespen maar ook van mensen en andere zoogdieren. Deze resultaten geven inzicht in de genetische regulatie van dagelijkse- en seizoensritmen en in hoe organismen zich aanpassen aan een veranderend milieu

High CTLA-4 expression correlates with poor prognosis in thymoma patients

Thymomas, tumors that arise from epithelial cells of the thymus gland, are the most common neoplasms of the anterior mediastinum, with an incidence rate of approximately 2.5 per million/year. Cytotoxic T Lymphocyte Antigen 4 (CTLA-4 or CD152) exerts inhibitory activity on T cells, and since its oncogenic role in the progression of different types of tumors, it has emerged as a potential therapeutic target in cancer patients. In this study, we assessed the expression of CTLA-4 both at mRNA and protein levels in paraffin embedded-tissues from patients with thymomas. Furthermore, we evaluated the relationship between CTLA-4 expression and the clinical-pathologic characteristics and prognosis in patients with thymomas. Sixty-eight patients with median age corresponding to 62 years were included in this analysis. Thymomas were classified accordingly to the WHO and Masaoka-Koga for histochemical analysis and for prognostic significance. A statistical difference was found between CTLA-4 mRNA levels in human normal thymus compared with thymoma specimens. CTLA-4 expression was statistically found to progressively increase in A, B1, B2, AB and it was maximal in B3 thymomas. According to Masaoka-Koga pathological classification, CTLA-4 expression was lower in I, IIA and IIB, and higher in invasive III and IV stages. By confocal microscopy analysis we identified the expression of CTLA-4 both in tumor cells and in CD45+ tumor-infiltrating leukocytes, mainly in B3 and AB thymomas. Finally, CTLA-4 overexpression significantly correlates with reduced overall survival in thymoma patients and in atypical thymoma subgroup, suggesting that it represents a negative prognostic factor

Artificial neural network analyzing wearable device gait data for identifying patients with stroke unable to return to work

A potential dramatic effect of long-term disability due to stroke is the inability to return to work. An accurate prognosis and the identification of the parameters inflating the possibility of return to work after neurorehabilitation are crucial. Many factors may influence it, such as mobility and, in particular, walking ability. In this pilot study, two emerging technologies have been combined with the aim of developing a prognostic tool for identifying patients able to return to work: a wearable inertial measurement unit for gait analysis and an artificial neural network (ANN). Compared with more conventional statistics, the ANN showed a higher accuracy in identifying patients with respect to healthy subjects (90.9 vs. 75.8%) and also in identifying the subjects unable to return to work (93.9 vs. 81.8%). In this last analysis, the duration of double support phase resulted the most important input of the ANN. The potentiality of the ANN, developed also in other fields such as marketing on social networks, could allow a powerful support for clinicians that today should manage a large amount of instrumentally recorded parameters in patients with stroke

Latitudinal variation in circadian rhythmicity in <i>Nasonia vitripennis</i>

Many physiological processes of living organisms show circadian rhythms, governed by an endogenous clock. This clock has a genetic basis and is entrained by external cues, such as light and temperature. Other physiological processes exhibit seasonal rhythms, that are also responsive to light and temperature. We previously reported a natural latitudinal cline of photoperiodic diapause induction in the parasitic wasp Nasonia vitripennis in Europe and a correlated haplotype frequency for the circadian clock gene period (per). To evaluate if this correlation is reflected in circadian behaviour, we investigated the circadian locomotor activity of seven populations from the cline. We found that the proportion of rhythmic males was higher than females in constant darkness, and that mating decreased rhythmicity of both sexes. Only for virgin females, the free running period (tau) increased weakly with latitude. Wasps from the most southern locality had an overall shorter free running rhythm and earlier onset, peak, and offset of activity during the 24 h period, than wasps from the northernmost locality. We evaluated this variation in rhythmicity as a function of period haplotype frequencies in the populations and discussed its functional significance in the context of local adaptation

Estudo psicométrico do Questionário de Atitudes Socioculturais em Relação à Aparência – 4

This article reports a study on the influences that sociocultural factors have on the composition and perception of body image. The objective was to understand the psychometric properties of the Sociocultural Attitudes Towards Appearance Questionnaire (SATAQ-4). The scale was applied to 390 participants with an average age of 22.66 years (SD = 4.68). The SATAQ-4 presented five factors of sociocultural influence: three subscales evaluating sociocultural pressures and two evaluating internalization of the beauty standard in both exploratory and confirmatory analyzes. The differences found between sexes indicated that women perceive themselves as more sociocultural influenced and a correlation was found between the magnitude of sociocultural pressure/internalization of the standard of beauty and self-esteem.En este artículo, se presenta un estudio de las influencias que producen factores socioculturales en la composición y la percepción de la imagen corporal. El objetivo fue comprender las propiedades psicométricas del Cuestionario de Actitudes Socioculturales en relación a la Apariencia (SATAQ-4). La escala se aplicó a 390 participantes con una edad promedio de 22,66 años (DE = 4,68). El SATAQ-4 presentó cinco factores de influencia sociocultural: tres subescalas que evalúan las presiones socioculturales y dos de internalización del patrón de belleza, tanto en los análisis exploratorios como confirmatorios. Las diferencias encontradas entre los sexos indicaron que las mujeres están más influenciadas socioculturalmente y se encontró una correlación entre la magnitud presión internalización sociocultural del estándar de belleza y autoestima. O presente artigo relata um estudo sobre as influências que fatores socioculturais produzem na composição e na percepção da imagem corporal. O objetivo foi compreender as propriedades psicométricas do Questionário de Atitudes Socioculturais em Relação à Aparência (SATAQ-4). A escala foi aplicada em 390 participantes com idade média de 22,66 anos (DP= 4,68). O SATAQ-4 apresentou cinco fatores de influência sociocultural: três subescalas que avaliam pressões socioculturais e duas de internalização do padrão de beleza, tanto em análises exploratórias quanto confirmatórias. As diferenças encontradas entre sexos indicaram que as mulheres são mais influenciadas socioculturalmente e foi encontrada correlação entre magnitude da pressão sociocultural/internalização do padrão de beleza e autoestima.