Searching for complexity in the human pupillary light reflex

This article aims to examine the dynamical characteristics of the pupillary light reflex and to provide a contribution towards their explanation based on the nonlinear theory of dynamical systems. To introduce the necessary concepts, terminology, and relevant features of the pupillary light reflex and its associated delay, we start with an overview of the human eye anatomy and physiology with emphasis on the iris, pupil, and retina. We also present the most highly regarded models for pupil dynamics found in the current scientific literature. Then we consider the model developed by Longtin and Milton, which models the human pupillary light reflex, defined by a nonlinear differential equation with delay, and present our study carried out on the qualitative and quantitative dynamic behavior of that neurophysiological control system.info:eu-repo/semantics/publishedVersio

Effect of SO2 on the extraction of individual anthocyanins and colored matter of three Portuguese grape varieties during winemaking

Periquita, Tinta Roriz and Tinta Barroca grapes were fermented under standard conditions with 3 levels of SO2 concentration. The anthocyanin monomers were separated by HPCL and identified by DAS on the grape skin extracts. Periquita was the wine with the highest color density and the higher content in total anthocyanins. Malvidin 3-glucoside, peonidin 3-glucoside and petunidin 3-glucoside were found in largest amounts in Periquita wines, while delphinidin 3-gucoside and malvidin 3-glucoside-p-coumarate were present in higher concentrations in Tinta Barroca wines. Malvidin 3-glucoside acetate and peonidin 3-glucoside coumarate were found in the highest concentration in Tinta Roriz wines. The influence of SO2 on the extraction of total anthocyanins and the major part of monomeric anthocyanins was very evident, but the rate of the extraction depends also on the nature of the anthocyanins and the characteristics of each variety. The high concentration of SO2 slowed down the formation of polymeric pigments

Vascular Patterns and Morphology in Dermoscopy - Part II. Clinical Practice

A dermatoscopia constitui uma técnica de diagnóstico não-invasiva, in vivo, que permite complementar a observação clínica de lesões cutâneas não-pigmentadas de etiologia diversa. Nos tumores cutâneos não-pigmentados, a dermatoscopia facilita a observação de estruturas vasculares, aumentando a acuidade no seu diagnóstico, distinguindo tumores melanocíticos e não-melanocíticos, benignos e malignos. Na parte II descreve-se a variabilidade da aplicação clínica da dermatoscopia em lesões cutâneas não-pigmentadas tumorais

Vascular Patterns and Morphology in Dermoscopy - Part I. Basic Principles

A dermatoscopia constitui uma técnica de diagnóstico não-invasiva, in vivo, que permite complementar a observação clínica de lesões cutâneas não-pigmentadas de etiologia diversa. Nos tumores cutâneos não-pigmentados, a dermatoscopia facilita a observação de estruturas vasculares, aumentando a acuidade no seu diagnóstico, distinguindo tumores melanocíticos e não-melanocíticos, benignos e malignos. Na parte I deste artigo são discutidos os princípios básicos da avaliação dermatoscópica dos tumores cutâneos não-pigmentados, incluindo a morfologia vascular e os padrões de distribuição dos vasos, assim como de outras pistas adicionais

Why are US firms using more short-term debt?

We show that corporate use of long-term debt has decreased in the US over the past three decades and that this trend is heterogeneous across firms. The median percentage of debt maturing in more than 3 years decreased from 53% in 1976 to 6% in 2008 for the smallest firms but did not decrease for the largest firms. The decrease in debt maturity was generated by firms with higher information asymmetry and new firms issuing public equity in the 1980s and 1990s. Finally, we show that demand-side factors do not fully explain this trend and that public debt markets' supply-side factors play an important role. Our findings suggest that the shortening of debt maturity has increased the exposure of firms to credit and liquidity shocks

COVID-19-related studies of nonprofit management: A critical review and research agenda

During crises such as the present coronavirus disease-19 (COVID-19) pandemic, nonprofits play a key role in ensuring support to improve the most vulnerable individuals’ health, social, and economic conditions. One year into the COVID-19 pandemic, an extensive automated literature analysis was conducted of 154 academic articles on nonprofit management during the pandemic—all of which were published in 2020. This study sought to identify and systematize academics’ contributions to knowledge about the crisis’s impact on the nonprofit sector and to ascertain the most urgent directions for future research. The results provide policymakers, nonprofit practitioners, and scholars an overview of the themes addressed and highlight the important assistance academic researchers provide to nonprofits dealing with the COVID-19 pandemic.info:eu-repo/semantics/acceptedVersio

How has the literature contributed to creating effective risk management policies in nonprofit organisations?

Although risk management is critical to all sectors of society, the attention given to the business sectors initiatives in this area has obstructed the advancement of knowledge about the remaining sectors. By systematically analysing 69 academic and non-academic publications, this study sought to highlight the areas of greatest interest in the literature on non-profit organisations (NPOs). Three topics stand out more clearly: risk identification, risk management processes, and risk mitigation strategies. The first two are more likely to be discussed in academic articles, while the last topic is prevalent in non-academic publications. Two main clusters of knowledge were identified in academic articles: risk exposure and risk management strategies. This review revealed that the focus of the literature on risk has shifted from strategies for transferring risk to NPOs as risky organisations that pursue complex goals whose success depends on strategic risk management. In addition, a critical review was conducted of risk conceptualisation and characterisation and of the findings of risk studies in the non-profit sector, thereby deepening the existing understanding of the progress made in this sectors still limited application of risk management. Moreover, the similarities, divergences, and limitations of the academic and non-academic literature are addressed. Risk managements role in the non-profit sectors sustainability is an understudied subject, but this field of research can only advance if practitioners make more risk-related information available to allow academics to gather the empirically robust evidence needed to support future studies.info:eu-repo/semantics/acceptedVersio

The image of and the interest in the accounting profession: an empirical study in three social groups

This study has the following goals: to analyse the image of and the interest in the accounting profession; to identify any possible differences in perception among the respondent groups; to identify the individual characteristics influencing the perception; to propose an explanatory model of the interest in the profession. The respondents were the members of three social groups composing the profession’s value chain: 105 financial officers of the biggest 500 Portuguese companies; 412 chartered accountants; 235 students majoring in Accounting. The data collected show that there are not any significant differences in perception regarding the image of and the interest in the accounting profession. Regarding the influence of the individual characteristics, the results obtained lead to the following conclusion: the third-year students with a higher average perceive a higher level of interest in the profession; the professionals with a higher academic degree and college graduated perceive a lower level of interest in the profession.info:eu-repo/semantics/acceptedVersio

Degradation of oligomeric procyanidins and anthocyanins in a Tinta Roriz red wine during maturation

A young red Tinta Roriz wine was stored for three months at different temperatures (12, 22, 32, 42 degrees C) under anaerobic conditions and after adjusting the SO2 to 0, 50, 100 mg/l. Changes in wine phenolic composition, especially the procyanidins and anthocyanins were measured using HPLC reverse phase. Dimeric (B1, B2, B3, B4), galloylated dimeric (B1-3-O-gallate, B2-3O-gallate, B2-3'-O-gallate) and trimeric procyanidins (C1, T2) were quantified during the maturation of the red wine, and their losses were found to be logarithmic with time. Temperature exerts a marked influence on the progressive degradation of procyanidins, while the presence of SO, slows down the degradation. Comparing their activation energies the dimer procyanidins B1, B2 and B3 appear to be more stable to degradation while trimer T2 and B2-3-O-gallate are most reactive. Concerning the anthocyanins, the acylated monoglucosides degrade faster than the other monoglucosides and the p-coumaric acid acylated pigments disappear faster than the acetic acid acylated pigments