Weber's law in decision making: integrating behavioral data in humans with a neurophysiological model

Recent single-cell studies in monkeys (Romo et al., 2004) show that the activity of neurons in the ventral premotor cortex covaries with the animal's decisions in a perceptual comparison task regarding the frequency of vibrotactile events. The firing rate response of these neurons was dependent only on the frequency differences between the two applied vibrations, the sign of that difference being the determining factor for correct task performance. We present a biophysically realistic neurodynamical model that can account for the most relevant characteristics of this decision-making-related neural activity. One of the nontrivial predictions of this model is that Weber's law will underlie the perceptual discrimination behavior. We confirmed this prediction in behavioral tests of vibrotactile discrimination in humans and propose a computational explanation of perceptual discrimination that accounts naturally for the emergence of Weber's law. We conclude that the neurodynamical mechanisms and computational principles underlying the decision-making processes in this perceptual discrimination task are consistent with a fluctuation-driven scenario in a multistable regime.

Rendu-Osler-Weber syndrome: what radiologists should know. Literature review and three cases report

Rendu-Osler-Weber syndrome or hereditary hemorrhagic telangiectasia is an autosomal dominant vascular disease involving multiple systems whose main pathological change is the presence of abnormal arteriovenous communications. Most common symptoms include skin and mucosal telangiectasias, epistaxis, gastrointestinal, pulmonary and intracerebral bleeding. The key imaging finding is the presence of visceral arteriovenous malformations. The diagnosis is based on clinical criteria and can be confirmed by molecular biology techniques. Treatment includes measures for management of epistaxis, as well as surgical excision, radiotherapy and embolization of arteriovenous malformations, with emphasis on endovascular treatment. The present pictorial essay includes a report of three typical cases of this entity and a literature review.

Aplicação da Distribuição de Weber ao peso de pinhas verdes

O objetivo deste trabalho foi verificar a eficiência da Distribuição de Weber quando aplicada aos dados de frequências de pesos de pinhas. Foram coletadas e pesadas 40 pinhas verdes, na Região Metropolitana de Curitiba. Os pesos foram distribuídos em seis classes com intervalo de 90 g. A Distribuição de Weber ajustou-se aos dados dos pesos das pinhas, de acordo com o teste de Kolmogorov-Smirnov. Os valores esperados pela distribuição, a média e a moda calculadas resultaram em valores próximos aos observados, mostrando que as expressões desenvolvidas foram eficientes. A facilidade para ajustar o modelo ora apresentado, o cálculo da média, a variância, o desvio-padrão e os pontos de inflexão, por meio das expressões desenvolvidas, são vantagens dessa distribuição. Devido à sua flexibilidade, pode-se afirmar que essa técnica pode ser aplicada a diversas distribuições de dados do setor florestal, bem como a outras séries de dados biológicos.

Sinfonische Metamorphosen über Themen von C. M. von Weber

Soitinnus: orkesteri.

Weber e Schumpeter: a ação econômica do empreendedor

Weber and Schumpeter: the Economic action of the entrepreneur. Is there any specificity to be raised in the relations established between entrepreneurs and institutions? Recently, the term entrepreneurship is being widely employed. Enterprising is not anymore a restricted activity to the private sector, but also the Third Sector and the Public Administration. It does not only circumscribe the space of innovation, but also of the adapting changes. In this sense, such elastic concept runs the risk to lose consistency. It seems to be appropriate, therefore, to rescue the meaning that many authors, considered classic in Social Sciences, had attributed to the subject, to show that, although deep socioeconomic transformations occurred since Schumpeter wrote the Theory of the Economic Development, is still necessary to emphasize a basic dimension of the enterprising action: resistance and institutional conflict.

Weber, Nietzsche e as respostas éticas à crítica da modernidade

O artigo consiste num estudo comparativo entre as concepções de cultura de Friedrich Nietzsche e Max Weber, suas análises críticas da modernidade e as respostas éticas que as acompanham. Apesar das importantes afinidades encontradas entre os autores, o artigo procura mostrar que o caráter principal da comparação entre os seus pensamentos é o do desencontro e da incompatibilidade.