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Abstract Automatic gaze estimation not based on commercial and expensive eye tracking hardware solutions can enable several applications in the fields of human computer interaction (HCI) and human behavior analysis. It is therefore not surprising that several related techniques and methods have been investigated in recent years. However, very few camera-based systems proposed in the literature are both real-time and robust. In this work, we propose a real-time user-calibration-free gaze estimation system that does not need person-dependent calibration, can deal with illumination changes and head pose variations, and can work with a wide range of distances from the camera. Our solution is based on a 3-D appearance-based method that processes the images from a built-in laptop camera. Real-time performance is obtained by combining head pose information with geometrical eye features to train a machine learning algorithm. Our method has been validated on a data set of images of users in natural environments, and shows promising results. The possibility of a real-time implementation, combined with the good quality of gaze tracking, make this system suitable for various HCI applications.

One of the most evident costs in cow farming is the identification of the animals. Classic identification processes are labour-intensive, prone to human errors and invasive for the animal. An automated alternative is an animal identification based on unique biometric patterns like iris recognition; in this context, correct segmentation of the region of interest becomes of critical importance. This work introduces a bovine iris segmentation pipeline that processes images taken in the wild, extracting the iris region. The solution deals with images taken with a regular visible-light camera in real scenarios, where reflections in the iris and camera flash introduce a high level of noise that makes the segmentation procedure challenging. Traditional segmentation techniques for the human iris are not applicable given the nature of the bovine eye; at this aim, a dataset composed of catalogued images and manually labelled ground truth data of Aberdeen-Angus has been used for the experiments and made publicly available. The unique ID number for each different animal in the dataset is provided, making it suitable for recognition tasks. Segmentation results have been validated with our dataset showing high reliability: with the most pessimistic metric (i.e. intersection over union), a mean score of 0.8957 has been obtained.

The transformation of light into chemical energy is a leitmotiv in the development of sustainable and environmentally concerned chemical processes. Chemists invented original concepts to address this purpose, like photoredox catalysis, which became a wonderful tool to transform simple organic compounds into high‐value products. Nevertheless, the most relevant transition metal based photocatalysts suffer from major disadvantages like toxicity, cost, and poor recyclability potential. To circumvent this, we propose a new generation of heterogeneous photoredox catalysts resulting from the combination of porous silica materials and Rose Bengal. They promote carbon–carbon bond formations under visible‐light in environmentally benign solvent using air as the only stoichiometric redox partner. The pure covalent photocatalytic system provides a robust and recyclable system for greener catalysis. This report would be of broad significance because it addresses important sustainability issues: recycling, non‐toxic metal‐free photocatalysts, and less‐waste‐producing chemical process. [ABSTRACT FROM AUTHOR]

Several 3‐pyrazolylcarbonyl‐pyrazolo[3,4‐d][1,2,3]triazin‐4‐ones have been prepared from 5‐amino‐1H‐pyrazole‐4‐carbonitriles through a simple sequence. In the first step, diazotization of the corresponding aminopyrazoles afforded pyrazolo[3,4‐d][1,2,3]triazin‐4‐ones. Next, thermal rearrangement of these compounds through nitrogen elimination gave the final products. The proposed mechanism for the ring‐opening of the pyrazolotriazinones to give the pyrazolylcarbonyl‐pyrazolotriazinones involves the generation of an iminoketene intermediate, which reacts with a second molecule of pyrazolotriazinone. The complete mechanism of product formation involving the iminoketene intermediate, and all other reasonable pathways, have been explored in detail through DFT calculations. Furthermore, additional experiments to corroborate the presence of the iminoketene intermediate were carried out. [ABSTRACT FROM AUTHOR]

Density Functional Theory (DFT) calculations have been carried out in order to unravel the governing reaction mechanism in copper-catalyzed cross-coupling Ullmann type reactions between iodobenzene (1, PhI) and aniline (2-NH, PhNH2), phenol (2-O, PhOH) and thiophenol (2-S, PhSH) with phenanthroline (phen) as the ancillary ligand. Four different pathways for the mechanism were considered namely Oxidative Addition-Reductive Elimination (OA-RE), σ-bond Metathesis (MET), Single Electron Transfer (SET), and Halogen Atom Transfer (HAT). Our results suggest that the OA-RE route, involving CuIII intermediates, is the energetically most favorable pathway for all the systems considered. Interestingly, the rate-determining step is the oxidative addition of the phenyl iodide to the metal center regardless of the nature of the heteroatom. The computed energy barriers in OA increase in the order O < S < NH. Using the Activation Strain Model (ASM) of chemical reactivity, it was found that the strain energy associated with the bending of the copper(I) complex controls the observed reactivity. [ABSTRACT FROM AUTHOR]

The result of a visualization process depends on the user’s decisions along it. With the intention of accelerating this process and guaranteeing an appropriate visualization of the data, we are looking to semi-automatize the process to help the users with the decision-making along it. To contribute to this semi-automation, it is useful to have metrics that characterize different important aspects of the visualization techniques, such as data representation visibility. Besides, scatterplots are a widely used technique to visualize scalar datasets. In this context, this work presents a metric that evaluates data representation visibility considering glyph visibility in scatterplots. We defined a metric that estimates the proportion of glyphs that will be visible regardless of the drawing order, and it depends on the number of items in the dataset, the size of the window, and the size of the glyphs that will represent the data. To define and approximate the metric, we experimented with several random datasets for which both dimensions followed a normal distribution. This metric constitutes an alternative to characterize scatterplots and collaborates in the semi-automation of the user’s decisions along the visualization process. [ABSTRACT FROM AUTHOR]