Inhibition by ATP of hippocampal synaptic transmission requires localized extracellular catabolism by ecto-nucleotidases into adenosine and channeling to adenosine A1 receptors

© 1998 Society for NeuroscienceATP analogs substituted in the γ-phosphorus (ATPγS, β, γ-imido-ATP, and β, γ-methylene-ATP) were used to probe the involvement of P2 receptors in the modulation of synaptic transmission in the hippocampus, because their extracellular catabolism was virtually not detected in CA1 slices. ATP and γ-substituted analogs were equipotent to inhibit synaptic transmission in CA1 pyramid synapses (IC50 of 17–22 μM). The inhibitory effect of ATP and γ-phosphorus-substituted ATP analogs (30 μM) was not modified by the P2 receptor antagonist suramin (100 μM), was inhibited by 42–49% by the ecto-5’- nucleotidase inhibitor and α, β-methylene ADP (100 μM), was inhibited by 74–85% by 2 U/ml adenosine deaminase (which converts adenosine into its inactive metabolite-inosine), and was nearly prevented by the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (10 nM). Stronger support for the involvement of extracellular adenosine formation as a main requirement for the inhibitory effect of ATP and γ-substituted ATP analogs was the observation that an inhibitor of adenosine uptake, dipyridamole (20 μM), potentiated by 92–124% the inhibitory effect of ATP and γ-substituted ATP analogs (10 μM), a potentiation similar to that obtained for 10 μM adenosine (113%). Thus, the present results indicate that inhibition by extracellular ATP of hippocampal synaptic transmission requires localized extracellular catabolism by ectonucleotidases and channeling of the generated adenosine to adenosine A1 receptors.This work was supported by Junta Nacional de Investigação Cientifica e Tecnológica, Praxis XXI, Gulbenkian Foundation, and European Union (BIOMED 2 programme

The Role of Ethanol in the Brazilian Economy: Three Decades of Progress

Sustainable energy strategies require decision-makers in government, industry, academia and civil society alike to make choices among tradeoffs. Within the transport sector alone, ethanol has been shown to be the dominant solution among viable, low carbon options to date, yet questions remain over the economic and ecological impacts of this industry. In Brazil - the largest producer of sugarcane-based ethanol and a country with over three decades of ethanol development – we find a strong basis for evaluating the ethanol industry’s role in a national economy. In the mid 1970’s, Brazilian ethanol production received an important boost with the launch of the “Proálcool†program. The ethanol industry has subsequently evidenced flux until its consolidation in the period following 2000. Over the course of three decades, economic, institutional, technological and environmental determinants have factored in the success of Brazilian ethanol diffusion. In economic terms, price tradeoffs for ethanol vs. sugar and ethanol vs. gasoline played a role in scale-up of the biofuel together with balance of payment considerations. From an institutional standpoint, support for the Proálcool program, deregulation of the sugar-cane sector in the 1990’s and fuel pump adaptations also factored. With respect to technology, the development of flex fuel cars, greater use of mechanized harvesting, and launch of domestic, co-generated, electrical power were key drivers. Finally, in environmental terms, challenges associated with pollution and public health in major cities as well as questions related to climate change gained visibility. In this paper, we analyze a set of input-output tables for the Brazilian economy from 1975 to 2008, taking the above factors into consideration. Deriving a series of indicators, such as multipliers and linkages, we study the evolution of the ethanol sector’s role in the Brazilian economy and its relation to the productive structure of the country.

5G & Cybersecurity

As comunicações 5G estão previstas para alterar o ambiente de comunicação num futuro próximo. A interacção entre equipamentos com escassa ou mesmo nenhuma interferência humana introduzirá novas vulnerabilidades de segurança, algumas das quais não estão, muito provavelmente, sequer previstas neste momento. Tendo isso em mente, o projecto 3GPP está a tentar pôr em prática várias normas para que os utilizadores possam sentir-se mais confiantes quanto à privacidade dos seus dados.5G communications are previewed to change de communication’s environment in the near future. Interaction between pieces of equipment with scarce or even no human interference shall introduce new security vulnerabilities, some of which are, most likely, not even foreseen at this moment. With that in mind the 3GPP project is trying to put in place several standards so that users may feel more confident about their data privacy.Se prevé que las comunicaciones 5G cambien el entorno de la comunicación en un futuro próximo. La interacción entre equipos con escasa o incluso nula interferencia humana introducirá nuevas vulnerabilidades de seguridad, algunas de las cuales, muy probablemente, ni siquiera están previstas en este momento. Teniendo esto en cuenta, el proyecto 3GPP está tratando de establecer varios estándares para que los usuarios puedan sentirse más seguros sobre la privacidad de sus datos.info:eu-repo/semantics/acceptedVersio

Classification of skin tumours through the analysis of unconstrained images

Skin cancer is the most frequent malignant neoplasm for Caucasian individuals. According to the Skin Cancer Foundation, the incidence of melanoma, the most malignant of skin tumours, and resultant mortality, have increased exponentially during the past 30 years, and continues to grow. [1]. Although often intractable in advanced stages, skin cancer in general and melanoma in particular, if detected in an early stage, can achieve cure ratios of over 95% [1,55]. Early screening of the lesions is, therefore, crucial, if a cure is to be achieved. Most skin lesions classification systems rely on a human expert supported dermatoscopy, which is an enhanced and zoomed photograph of the lesion zone. Nevertheless and although contrary claims exist, as far as is known by the author, classification results are currently rather inaccurate and need to be verified through a laboratory analysis of a piece of the lesion’s tissue. The aim of this research was to design and implement a system that was able to automatically classify skin spots as inoffensive or dangerous, with a small margin of error; if possible, with higher accuracy than the results achieved normally by a human expert and certainly better than any existing automatic system. The system described in this thesis meets these criteria. It is able to capture an unconstrained image of the affected skin area and extract a set of relevant features that may lead to, and be representative of, the four main classification characteristics of skin lesions: Asymmetry; Border; Colour; and Diameter. These relevant features are then evaluated either through a Bayesian statistical process - both a simple k-Nearest Neighbour as well as a Fuzzy k-Nearest Neighbour classifier - a Support Vector Machine and an Artificial Neural Network in order to classify the skin spot as either being a Melanoma or not. The characteristics selected and used through all this work are, to the author’s knowledge, combined in an innovative manner. Rather than simply selecting absolute values from the images characteristics, those numbers were combined into ratios, providing a much greater independence from environment conditions during the process of image capture. Along this work, image gathering became one of the most challenging activities. In fact several of the initially potential sources failed and so, the author had to use all the pictures he could find, namely on the Internet. This limited the test set to 136 images, only. Nevertheless, the process results were excellent. The algorithms developed were implemented into a fully working system which was extensively tested. It gives a correct classification of between 76% and 92% – depending on the percentage of pictures used to train the system. In particular, the system gave no false negatives. This is crucial, since a system which gave false negatives may deter a patient from seeking further treatment with a disastrous outcome. These results are achieved by detecting precise edges for every lesion image, extracting features considered relevant according to the giving different weights to the various extracted features and submitting these values to six classification algorithms – k-Nearest Neighbour, Fuzzy k-Nearest Neighbour, Naïve Bayes, Tree Augmented Naïve Bayes, Support Vector Machine and Multilayer Perceptron - in order to determine the most reliable combined process. Training was carried out in a supervised way – all the lesions were previously classified by an expert on the field before being subject to the scrutiny of the system. The author is convinced that the work presented on this PhD thesis is a valid contribution to the field of skin cancer diagnostics. Albeit its scope is limited – one lesion per image – the results achieved by this arrangement of segmentation, feature extraction and classification algorithms showed this is the right path to achieving a reliable early screening system. If and when, to all these data, values for age, gender and evolution might be used as classification features, the results will, no doubt, become even more accurate, allowing for an improvement in the survival rates of skin cancer patients

A influência alemã e a construção da modernidade pedagógica em Portugal: o exemplo da revista Froebel (1882-1885)

Este texto propõe uma reflexão sobre o desenvolvimento de um projecto de modernização pedagógica, no final do século XIX português, em diálogo com a pedagogia alemã, tendo como referência a figura de Froebel. Para tal, analisou-se uma publicação periódica que assumiu, no âmbito da comemoração do seu centenário, o nome do educador alemão: Froebel – Revista de Instrução Primária, publicada entre os anos de 1882 e 1885. Este periódico surge ligado aos Serviços de Instrução do Município de Lisboa, numa época de grande aposta no incentivo camarário ao fomento educativo, com o objectivo de dar a conhecer algumas das iniciativas emblemáticas daquele município no campo da educação popular, concedendo destaque a ideias e práticas defendidas pelos educadores renovadores do período, como os trabalhos manuais, as excursões escolares, a instrução militar e os batalhões escolares. A revista também concede espaço à circulação de saberes em dimensão internacional, ao publicar notícias sobre as iniciativas implementadas em outros países

The role of ethanol in the brazilian economy: three decades of progress

Sustainable energy strategies require decision-makers in government, industry, academia and civil society alike to make choices among tradeoffs. Within the transport sector alone, ethanol has been shown to be the dominant solution among viable, low carbon options to date, yet questions remain over the economic and ecological impacts of this industry. In Brazil - the largest producer of sugarcane-based ethanol and a country with over three decades of ethanol development – we find a strong basis for evaluating the ethanol industry’s role in a national economy. In the mid 1970’s, Brazilian ethanol production received an important boost with the launch of the “Proálcool” program. The ethanol industry has subsequently evidenced flux until its consolidation in the period following 2000. Over the course of three decades, economic, institutional, technological and environmental determinants have factored in the success of Brazilian ethanol diffusion. In economic terms, price tradeoffs for ethanol vs. sugar and ethanol vs. gasoline played a role in scale-up of the biofuel together with balance of payment considerations. From an institutional standpoint, support for the Proálcool program, deregulation of the sugar-cane sector in the 1990’s and fuel pump adaptations also factored. With respect to technology, the development of flex fuel cars, greater use of mechanized harvesting, and launch of domestic, co-generated, electrical power were key drivers. Finally, in environmental terms, challenges associated with pollution and public health in major cities as well as questions related to climate change gained visibility. In this paper, we analyze a set of input-output tables for the Brazilian economy from 1975 to 2006, taking the above factors into consideration. Deriving a series of indicators, such as multipliers and linkages, we study the evolution of the ethanol sector’s role in the Brazilian economy and its relation to the productive structure of the countryBrazil, Ethanol, Input-Output, Productive Structure

Characterization of seaweed communities using deep learning applied to UAV-based hyperspectral images

Macroalgal communities are generally found in coastal regions, close to rocks or other hard surfaces. They provide shelter and food for many organisms and are of interest to the food industry, pharmaceutical, and agriculture. They are also an indicator of environmental change. Traditionally, the process of identification and monitoring of these communities and their constituent species is based on manual methods. The use of unmanned aerial vehicles (UAVs) allows the remote collection of images with high spatial and spectral resolution and adjustable time scales. The development of methodologies allowing the processing and the analysis of UAV-based high-resolution imagery would be of economic and environmental importance. That would allow to streamline the identification of species with economic potential, the evaluation of the seasonal and spatial variation of the available biomass, and the monitoring of the coastal ecological status and its evolution. Recent technological developments in the areas of remote sensing and artificial intelligence make it possible to provide tools with great potential for these applications. Indeed, hyperspectral sensors can nowadays be coupled in UAVs allowing for high spatial and spectral resolution imagery. The data processing powered by deep learning and its increasing diversity of models and architectures is the ideal way to handle and analyze the huge volume of data acquired. In this paper, we describe a methodology to be implemented in a system to be developed to make the automatic classification of existing species in macroalgal communities, using deep learning models applied to hyperspectral images collected by UAVs.info:eu-repo/semantics/acceptedVersio

Modelling the SFRC flexural behavior using a stress-strain relationship

No presente trabalho foi desenvolvida uma estratégia numérica de forma a avaliar a possibilidade de ser definida uma lei tensão-extensão capaz de simular o comportamento fendilhado do betão de custo competitivo reforçado com fibras de aço (BRFA) concebido no âmbito de um projecto de investigação. Essa estratégia englobou dois modelos de complexidade distinta. O primeiro, designado por modelo de secção, foi utilizado para, com recurso a análise inversa e utilizando respostas força-flecha registadas em ensaios experimentais, se determinarem os parâmetros que definem uma lei trilinear tensão-extensão capaz de reproduzir as respostas experimentais com o rigor desejado. De seguida, esta lei foi utilizada para definir o modo I de fractura da lei constitutiva da fenda, no âmbito de um código computacional de análise não linear material de estruturas submetidas a estado plano de tensão, suportado no método dos elementos finitos, onde o processo de fendilhação é simulado por um modelo de fendilhação distribuída. Da aplicação dos dois modelos constatou-se que o modelo de secção não permite definir a lei tensão-extensão pós pico (lei de amolecimento) com o rigor necessário. Enquadrado numa análise inversa, o modelo baseado no MEF foi de seguida utilizado para se determinar a lei de amolecimento do BRFA, tendo-se constatado que essa lei não pode ser explicitada unicamente em função do conceito de resistência equivalente, tal como sugere o RILEM TC 162-TDF.To assess the post-cracking stress-strain relationship for a developed cost competitive steel fibre reinforced concrete (SFRC), a numerical strategy involving two numerical models of distinct complexity was carried out. Inserted into an inverse analysis framework, a cross-sectional-layer-model (CSLM) was used to evaluate the post-cracking stress-strain relationship able of reproducing, with the desired accuracy, the force-deflection relationship recorded in three-point bending tests carried out according to the RILEM TC 162-TDF recommendations. This relationship was used as the strain softening law of the fracture mode I crack constitutive law of a smeared crack model based on the strain decomposition concept, under the framework of the finite element method (FEM). Applying this model it was verified that the CSLM couldn't define a strain softening law able of simulating, with the necessary accuracy, the fracture mode I of the SFRC. Using an inverse analysis and the FEM model, the softening law for the SFRC analysed was evaluated. From the values obtained for the definition of this law it was concluded that this law cannot be exclusively dependent on the concept of equivalent flexural tensile strength, as RILEM TC 162-TDF recommends

Comportamento à tracção directa de elementos laminares de betão armado reforçado com fibras de aço

Quando comparado com o betão simples, o betão reforçado com fibras de aço, BRFA, apresenta melhor comportamento à fendilhação e maior capacidade de absorção de energia. Em consequência, a utilização de BRFA, em determinadas aplicações, pode ser uma mais valia em termos técnicos e económicos. O presente trabalho tem como principal objectivo avaliar a influência das fibras de aço no comportamento à tracção de elementos laminares de betão armado. Os principais resultados experimentais e numéricos são apresentados e discutidos