Bifurcations and Averages in the Homoclinic Chaos of a Laser with a Saturable Absorber

The dynamical bifurcations of a laser with a saturable absorber were calculated, with the 3-2 level model, as function of the gain parameter. The average power of the laser is shown to have specific behavior at bifurcations. The succession of periodic-chaotic windows, known to occur in the homoclinic chaos, was studied numerically. A critical exponent of 1/2 is found on the tangent bifurcations from chaotic into periodic pulsations.Comment: 6 or 7 pages, 3 figures, publishe

Fluorometric method based on molecular recognition solid-phase extraction for determination of riboflavin in milk and infant formula

Riboflavin (vitamin B2) is involved in several biological processes, particularly in energy production, and it is acquired from food ingestion, principally from supplemented food during the first years of life. Therefore, a simple, fast and cost-effective high-throughput method for determination of riboflavin in milk and infant formula is proposed, based on selective extraction using commercially available molecularly imprinted polymers targeted to riboflavin, followed by direct fluorometric determination. Several aspects were studied, namely microplate assay conditions, the composition of eluting solution and the stability of riboflavin in the eluate. Hence, elution using 1% (v/v) acetic acid in methanol or in acetonitrile is recommended, followed by immediate analysis or solvent evaporation, with reconstitution and analysis within 24 h. The proposed method provided a LOD of 0.03 mg L−1, with working range for undiluted samples between 0.125 and 2 mg L−1, and sample throughput of 24 h−1. It was successfully applied to certified reference material NIST-1846 and also to commercial milk and infant formula samples.info:eu-repo/semantics/publishedVersio

Dynamic predictability and activity-location contexts in human mobility

Human travelling behaviours are markedly regular, to a large extent predictable, and mostly driven by biological necessities and social constructs. Not surprisingly, such predictability is influenced by an array of factors ranging in scale from individual preferences and choices, through social groups and households, all the way to the global scale, such as mobility restrictions in response to external shocks such as pandemics. In this work, we explore how temporal, activity and location variations in individual-level mobility - referred to as predictability states - carry a large degree of information regarding the nature of mobility regularities at the population level. Our findings indicate the existence of contextual and activity signatures in predictability states, suggesting the potential for a more nuanced approach to estimating both short-term and higher-order mobility predictions. The existence of location contexts, in particular, serves as a parsimonious estimator for predictability patterns even in the case of low resolution and missing data.</p

Sample introduction in multi-syringe flow injection systems: comparison between time-based and volume-based strategies

In multi-syringe flowinjection analysis (MSFIA), devices as selection, injection or commutation valves must be incorporated to the manifold to provide access to sample and standard solutions. Therefore, the definition of sample amount can be either volume or time-based. In the present work, four configurations for sample introduction (two for each approach) were tested in order to establish if the different strategies affect the analytical signal in MSFIA systems. The mean absorbance value from ten consecutive injections of a bromothymol blue solution obtained for the time-based strategy was lower than that provided by the volume-based approach as the exact volume delivered by each configuration was different from the “theoretical” volume. For time-based configurations, the exact volume delivered is 2–5% lower than the theoretical value while for volume-based configurations, the volume delivered was between 6 and 46% larger than the theoretical volume. Moreover, for time-based sampling, the order of steps in the analytical cycle was of utmost importance since any alteration in the flow direction affected the volume delivered in the subsequent step in the analytical cycle. The influence of the two sampling approaches was also evaluated in the MSFIA systems for the spectrophotometric determination of phenolic compounds and the potentiometric determination of chloride. There was no evidence that the use of either volume or time-based sampling would improve the analytical features of these determinations when real samples were tested.info:eu-repo/semantics/acceptedVersio

Desenvolvimento e estudo de ligantes modificados inovadores para infraestruturas de transporte

Este trabalho apresenta alguns projetos desenvolvidos pela presente equipa de investigação relativos ao desenvolvimento de novos materiais para aplicação em pavimentos rodoviários, utilizando resíduos que podem ser valorizados como uma nova matéria‑prima. Desta nova abordagem devem resultar pavimentos betuminosos com melhor desempenho, conjugando ainda vantagens ecológicas e económicas. Assim, apresentam-se três estudos distintos: o primeiro focado na substituição parcial de betume por bio-óleo proveniente da pirólise rápida de resíduos de materiais orgânicos, modificado com granulado de borracha de pneus usados; o segundo consiste na utilização de resíduos plásticos para produção de ligantes modificados, em vez de polímeros virgens, para melhorar o desempenho dos pavimentos; o terceiro também utiliza um resíduo plástico, mas tem como principal objetivo explorar a substituição de parte do betume por outro resíduo, o óleo de motor usado. Neste trabalho são apresentados os principais resultados de desempenho das misturas betuminosas produzidas com estes novos ligantes mais sustentáveis

Re-Identification in Urban Scenarios: A Review of Tools and Methods

With the widespread use of surveillance image cameras and enhanced awareness of public security, objects, and persons Re-Identification (ReID), the task of recognizing objects in non-overlapping camera networks has attracted particular attention in computer vision and pattern recognition communities. Given an image or video of an object-of-interest (query), object identification aims to identify the object from images or video feed taken from different cameras. After many years of great effort, object ReID remains a notably challenging task. The main reason is that an object's appearance may dramatically change across camera views due to significant variations in illumination, poses or viewpoints, or even cluttered backgrounds. With the advent of Deep Neural Networks (DNN), there have been many proposals for different network architectures achieving high-performance levels. With the aim of identifying the most promising methods for ReID for future robust implementations, a review study is presented, mainly focusing on the person and multi-object ReID and auxiliary methods for image enhancement. Such methods are crucial for robust object ReID, while highlighting limitations of the identified methods. This is a very active field, evidenced by the dates of the publications found. However, most works use data from very different datasets and genres, which presents an obstacle to wide generalized DNN model training and usage. Although the model's performance has achieved satisfactory results on particular datasets, a particular trend was observed in the use of 3D Convolutional Neural Networks (CNN), attention mechanisms to capture object-relevant features, and generative adversarial training to overcome data limitations. However, there is still room for improvement, namely in using images from urban scenarios among anonymized images to comply with public privacy legislation. The main challenges that remain in the ReID field, and prospects for future research directions towards ReID in dense urban scenarios, are also discussed

Using simulation to model the logistic operations of a company of the cement industry

This paper presents a discrete-event simulation model to study the logistics operations involved in a plant of the cement industry, aligned with a real project developed in partnership between Cachapuz (a company that provides international weighing solutions) and the University of Minho. The purpose of this work consists in using simulation to model several activities, involving weighing, loading and unloading of raw materials, regardless of the type of industry, e.g. cement, tomato, cereals. Thus, this paper documents the work conducted to apply the developed simulation model in a case study of the cement industry. After validating the model, a set of simulation experiments were conducted, which allowed to estimate the maximum capacity of the plant and the impact in the performance of the plant, of the arrival of a cargo vessel. In this regard, it was found that in the case study in question, it is not possible to unload all the cargo from the vessel in a working day - around 3 working days would be required. Further conclusions and future work are discussed in the last section.- (undefined

Novel Virtual Environment for Alternative Treatment of Children with Cerebral Palsy

Cerebral palsy is a severe condition usually caused by decreased brain oxygenation during pregnancy, at birth or soon after birth. Conventional treatments for cerebral palsy are often tiresome and expensive, leading patients to quit treatment. In this paper, we describe a virtual environment for patients to engage in a playful therapeutic game for neuropsychomotor rehabilitation, based on the experience of the occupational therapy program of the Nucleus for Integrated Medical Assistance (NAMI) at the University of Fortaleza, Brazil. Integration between patient and virtual environment occurs through the hand motion sensor “Leap Motion,” plus the electroencephalographic sensor “MindWave,” responsible for measuring attention levels during task execution. To evaluate the virtual environment, eight clinical experts on cerebral palsy were subjected to a questionnaire regarding the potential of the experimental virtual environment to promote cognitive and motor rehabilitation, as well as the potential of the treatment to enhance risks and/or negatively influence the patient’s development. Based on the very positive appraisal of the experts, we propose that the experimental virtual environment is a promising alternative tool for the rehabilitation of children with cerebral palsy.Cerebral palsy is a severe condition usually caused by decreased brain oxygenation during pregnancy, at birth or soon after birth. Conventional treatments for cerebral palsy are often tiresome and expensive, leading patients to quit treatment. In this paper, we describe a virtual environment for patients to engage in a playful therapeutic game for neuropsychomotor rehabilitation, based on the experience of the occupational therapy program of the Nucleus for Integrated Medical Assistance (NAMI) at the University of Fortaleza, Brazil. Integration between patient and virtual environment occurs through the hand motion sensor “Leap Motion,” plus the electroencephalographic sensor “MindWave,” responsible for measuring attention levels during task execution. To evaluate the virtual environment, eight clinical experts on cerebral palsy were subjected to a questionnaire regarding the potential of the experimental virtual environment to promote cognitive and motor rehabilitation, as well as the potential of the treatment to enhance risks and/or negatively influence the patient’s development. Based on the very positive appraisal of the experts, we propose that the experimental virtual environment is a promising alternative tool for the rehabilitation of children with cerebral palsy

Growth of lambs of the churraTerra Quente and Churra Badana Sheep Breeds

O presente trabalho teve como objectivo avaliar os pesos, a diferentes idades, de borregos das raças ovinas Churras da Terra Quente e Badana. Baseou-se nos registos de pesos de 140 borregos Churros da Terra Quente e 88 da raça Churra Badana. Os borregos foram pesados ao nascimento e, posteriormente, quinzenalmente, até aos 120 dias de idade, tendo-se calculado os respectivos pesos ajustados aos 15, 30, 45, 60 e 120 dias de idade (PN, P15d, P30d, P45d, P60d e P120d). Procedeu-se a uma análise de variância, com o objectivo de avaliar quais os principais efeitos ambientais que influenciam o peso dos borregos às diferentes idades, com um modelo que incluiu os efeitos do sexo (macho ou fêmea), tipo de parto (simples ou múltiplo), mês do parto (Setembro, Outubro ou Novembro) e peso da mãe ao parto (como covariável). Verificaram-se diferenças significativas entre raças (p<0,01) nos pesos ao nascimento, 90 e 120 dias de idade, observando-se uma superioridade dos borregos da raça Churra da Terra Quente, relativamente aos da raça Badana (PN: 3,51±0,05 vs. 3,22±0,08; P90d: 24,05±0,72 vs. 21,73±0,93; P120d: 28,73±0,73 vs. 26,07±0,52). Porém, não houve diferenças entre raças nos pesos durante o aleitamento, entre os 15 e os 60 dias de vida. O sexo dos borregos influenciou significativamente os pesos destes em qualquer das idades estudadas, registando-se pesos superiores nos machos relativamente aos das fêmeas (P15d: 7,00±0,14 vs. 6,35±0,14; P30d: 10,25±0,20 vs. 9,47± 0,19; P45: 13,98±0,28 vs. 12,90±0,26; P60d: 18,18±0,42 vs. 16,16±0,39; P90d: 24,57±1,21 vs. 21,21±0,57). Registou-se ainda uma superioridade nos pesos dos animais nascidos de partos simples e um efeito significativo do peso da ovelha nos pesos dos borregos até aos 45 dias de idade. Os resultados obtidos evidenciaram alguma superioridade nos pesos dos borregos da raça Churra da Terra Quente, relativamente aos da raça Churra Badana, mas apenas no período pós desmame