Topology Regulated Background Extraction (TRBE) method for eye fundus images.

One of the initial steps in the preprocessing of digital fundoscopy images is the identification of pixels containing relevant information. This can be achieved through different approaches, one of them is implementing background extraction, reducing the set of pixels to be analyzed later in the process. In this work, we present a background extraction method for digital fundoscopy images based on computational topology. By interpreting binarized images as cubical complexes and extracting their homological groups in 1 and 2 dimensions we identify a subset of luminescence values that can be used to binarize the original grayscale image, obtaining a mask to achieve background extraction. This method is robust to noise and suboptimal image quality, facilitating the analytical pipeline in the context of computer aided diagnosis approaches. This method facilitates the segmentation of the background of a digital fundoscopy image, which allows further methods to focus on pixels with relevant information (eye fundus). This tool is best suited to be implemented in the preprocessing stages of the analytical pipeline by computational ophthalmology specialists.•It is robust to noise and low-quality images.•Output provides an ideal scenario for down-the-line analysis by facilitating only relevant pixels in a digital fundoscopy.

Sun exposure practices, attitudes and knowledge among students and teachers at a University School of Health Sciences in Ecuador.

Skin cancer incidence is increasing worldwide. Late adolescence and young adulthood are fundamental stages of life to acquire good sun exposure practices, regarding both personal involvement in skin cancer prevention and being a role model for others, especially in a health education environment. This descriptive cross-sectional study is based on the validated CHACES questionnaire to study sun exposure and photoprotection behavior among students and teachers at the School of Health Sciences in the National University of Chimborazo, Riobamba (Ecuador). University members (814 students (89.8 %) and 93 teachers (10.2 %)) were studied, with a predominance of females and light-skin phototypes in both groups. Similar results were obtained regarding sun exposure, with higher recreative exposure in the teachers' group and higher occupational exposure in students. However, students significantly showed lower avoiding midday sun (41.9 % vs 60.9 %), and lower use of sunglasses (10.1 % vs. 41.6 %). Attitudes towards the sun and photoprotection knowledge issues were also equivalent between students and teachers (6.1/10 vs 6.2/10). Students' sunburn rate last year reaches 88.4 % and 52.7 % in teachers (p < 0.001). Using a multivariable logistic regression model, we identified risk factors associated with a greater risk of sunburn in our population. This study highlights areas to be improved regarding knowledge, attitudes and, especially, practices of photoprotection, among students and teachers at the University of Chimborazo. These results point out that awareness-raising campaigns should be implemented to reduce sunburns, morbidity and mortality of skin cancer in this environment.

Temperature-dependent potential for the molecular dynamics of the superionic conductor ß-PbF2.

Molecular dynamic (MD) calculations were performed to investigate the thermodynamic and structural properties of lead fluoride (PbF2) by using a proposed inter-ionic temperature-dependent potential. This potential allows calculating with high precision the linear thermal expansivity and the lattice parameter as a temperature function. In addition, the potential can be represented as a sum of two contributions, a temperature-independent potential added to another temperature-dependent potential, considered last as a correction justified by the one-dimensional Newtonian quantum equation. Two fitting regions were considered, the first region from 300 to 700 K and the other one from 700 to 900 K. These regions arise naturally due to the smooth and continuous transition that PbF2 undergoes until it reaches the superionic state and, allows us to model with high precision the anomaly in the dependence of the lattice parameter with the temperature of this material, a feature that until now under the molecular dynamic method has not been studied. These results are all in good agreement with the experimental measurements.