Produtividade estacional, melhoramento e manejo de pastagens na Ilha de Marajó.

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Time series forecasting with the WARIMAX-GARCH method

It is well-known that causal forecasting methods that include appropriately chosen Exogenous Variables (EVs) very often present improved forecasting performances over univariate methods. However, in practice, EVs are usually difficult to obtain and in many cases are not available at all. In this paper, a new causal forecasting approach, called Wavelet Auto-Regressive Integrated Moving Average with eXogenous variables and Generalized Auto-Regressive Conditional Heteroscedasticity (WARIMAX-GARCH) method, is proposed to improve predictive performance and accuracy but also to address, at least in part, the problem of unavailable EVs. Basically, the WARIMAX-GARCH method obtains Wavelet “EVs” (WEVs) from Auto-Regressive Integrated Moving Average with eXogenous variables and Generalized Auto-Regressive Conditional Heteroscedasticity (ARIMAX-GARCH) models applied to Wavelet Components (WCs) that are initially determined from the underlying time series. The WEVs are, in fact, treated by the WARIMAX-GARCH method as if they were conventional EVs. Similarly to GARCH and ARIMA-GARCH models, the WARIMAX-GARCH method is suitable for time series exhibiting non-linear characteristics such as conditional variance that depends on past values of observed data. However, unlike those, it can explicitly model frequency domain patterns in the series to help improve predictive performance. An application to a daily time series of dam displacement in Brazil shows the WARIMAX-GARCH method to remarkably outperform the ARIMA-GARCH method, as well as the (multi-layer perceptron) Artificial Neural Network (ANN) and its wavelet version referred to as Wavelet Artificial Neural Network (WANN) as in [1], on statistical measures for both in-sample and out-of-sample forecasting

Electroanalysis of Heavy Metals in the Cork of Quercus Suber

This will enable Pb(II) determination optimisation, regarding environmental aspects of the perpetuation of Quercus suber Montado (similar to Forest). It will also allow a more profound toxicological quality control of corks (barks). These two last referred aspects are very related ones, once accepted that the more advanced could the certification of the quality patterns of corks (barks) be, more will be the sustainability of Quercus suber ecosystem. Which we believe can be done, amongst other vectors, by studying such an important environmental issue as heavy metals. It is shown that Pb(II) quantification in the cork (bark) of Quercus suber tree (Cork Oak) is possible, using Differential Pulse Anodic Stripping Voltammetry (DPASV). The samples digestion was made in a mixture of H2O2 and HNO3 1:8, in a closed recipient at approximately 90 ºC. The measures were made in NaCl 0.1 M, using a Hanging Mercury Drop Electrode, a Glassy-Carbon Rod Counter Electrode, and an Ag/AgCl/KCl 3M reference electrode, after a 180 s deposition step. The results have shown the determination of a coherent stripping potential of -0.405 V (SD=0.0005 V), and a fine linear adjustment after the standard addition method (R2 = 0.997). They have also revealed the interest of further studies. The need to test other electroanalysis requisites was understood, and imposed by the proof of the complex nature of the matrix

THE IMPORTANCE OF THE CORK (BARK) OF QUERCUS SUBER IN THE

The recent absence of Lead element as catalyst in internal explosion motors, being an extremely important action for the stop of this environmental aggression, has no effect in the minimization of the harm this element does in the positions where its deposition now lays. The impact of the ubiquity of pollution, in this case Lead pollution, needs to have monitoring tools. The greatest of the tools one can have is the analysis of the content of a strong indicator. One that stands for a long time in one place, for which it is able to receive the marks of the analyte passage. Quercus suber (Cork Oak) tree is such a case. Having a life expectation ranging from 200 to 500 years (depending on the cork extraction intensity) and with a capability of regeneration of its cork coverture, it concentrates the amounts of Lead, with which it had contacted through its life, in successive layers, corresponding, the larger ones, to the high temperatures season, and the thinner ones to the low temperatures season. So, the analysis of the content of the element in a layer of cork with a given amount of years in the tree, will be a good estimator of how the content of Lead as evolved in the area. And a correct distribution of sampling trees will show much more about a greater area. The possibility of choosing years by choosing layers of cork, and the fact that the sampling will not harm the tree, if properly done, make this procedure a novel and powerful tool in the monitorization of the dispersion of heavy metals in areas populated by Quercus suber, as it is the case of big areas in Portugal, the great of the greatest in everything related with this tree, namely economically, and, in general, in the area of the Mediterranean basin. This paper announces how the electroanalytical determination of Pb(II) by Differential Pulse Anodic Stripping Voltammetry (DPASV), recently done in the Department of Chemistry of the University of Évora, already accepted for publication in Portugaliae Electrochimica Acta, has proven to allow a deeper insight into the previously discussed problematic

Endovascular Therapy of Pseudoaneurysm and Arteriovenous Fistula in a Renal Graft

A 31 year old male Caucasian received a renal cadaveric allograft. Reconstruction of an inferior polar artery was corrected pre-implantation. Delayed graft function occurred leading to dialysis support for one month. Graft biopsies(days 7, 15) showed acute tubular necrosis(ATN) and no rejection. Serial ultrasound (US), performed on average weekly, were compatible with ATN. On day 31, Doppler US and a CAT scan suggested for the first time a pseudoaneurysm adjacent to the implantation of the graft artery on the external iliac artery. For clinical and technical reasons, arteriography was only performed on day 67, when serum creatinine was 3.3 mg/dl. It showed a large pseudoaneurysm with an arteriovenous fistula to the right common iliac vein. Compression of the right external iliac artery was clear. In an attempt to close the arteriovenous fistula, the communication with the pseudoaneurysm was embolised with gelfoam and metallic coils with partial success. One week later, by right femoral approach a covered wallstent was placed immediately below the origin of the graft artery.Subsequent Doppler US and arteriography con-firmed closure of the communication with thepseudoaneurysm and of the arteriovenous fistula. The calibre of the right external iliac artery was then normal. By month 18, serum creatinine is stable at 2.1 mg/dl. We can only speculate on the origin of thepseudoaneurysm and of the AV fistula, whichwere not evident until one month post-transplantation. Backtable surgery was performed on thepolar not the main graft artery. Invasive angiography was irreplaceable in this unusual clinical situation

Melhoramento e manejo de pastagens na Ilha de Marajó: resultados e informações práticas.

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Elementos limitantes à produção de pastagens nativas consorciadas com leguminosas na Ilha de Marajó.

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Suplementação alimentar em sindi lactantes.

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