4,355 research outputs found

    Petrography and geochemistry of Sepeda Li-rich aplite-pegmatite dyke swarm (Montalegre, N Portugal)

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    The Sepeda aplite-pegmatite dyke swarm is situated in the Barroso-Alvão region (Montalegre, Northern Portugal) and is currently a strategic Li ore deposit in Europe. Geologically, it is located in the Parautochthonous Thrust Complex of the Galicia-Trás-os-Montes Zone (Variscan Iberian Belt), more exactly on its southern edge, next to the Central-Iberian Zone. Numerous aplitic and pegmatitic bodies, considered of the LCT type (e.g. Noronha et al., 2013), that cross cut the host metasediments of Silurian age were recently targeted in a diamond drilling campaign. From 4 drill hole logs with suspected Li mineralizations, 120 samples were selected for whole-rock chemical analysis and also 13 samples for thin section preparation. Petrographically, the Sepeda pegmatitic rocks are characterized by distinctive igneous textures that include the following major crystalline phases: K-feldspar, plagioclase, quartz, muscovite, petalite and spodumene. The latter is commonly altered to other Li bearing minerals such as eucryptite and cookeite. The most common accessory minerals are the phosphates montebrasite and apatite and the opaques cassiterite and sphalerite. Aditionally, there are strong evidence of solid state deformation like the dynamic recrystalization of quartz and bent muscovites in addition to plagioclase and K-feldspar flexured twins. In relation to whole-rock geochemistry, these intrusive rocks are mainly felsic with SiO2 contents ranging between 60,97 and 85,78%. The lithologies of intermediate compositions are mostly the aplitic types occuring at shallower depths. With regards to Li2O, the concentration interval varies from 0,01 up to 4,13% where the richer samples (>1% of Li2O) are the pegmatites with aproximately 74% of Si2O in which petalite is the major constituent. Other relevant trace element is Sn reaching 2100 ppm in opposition to Cs (1,68 - 191,50 ppm) and Ta (1,10 - 97,40 ppm). They also show low concentrations in ΣREE (1,37 - 5,61 ppm) with strongly variable Eu anomalies (0,36 ≤ Eu/Eu* ≤ 2,98).publishe

    Contribution for the knowledge of mechanical characteristics of contaminated dune sand with gasoline

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    Portugal, country of the Southwest of the Europe, has extensive areas of granular lands constituted by sands of dunes that are located next to the coast. The unsustainable development of the society has lead to the intensive occupation of these lands. As consequence sometimes arise contaminated soils where are or can be built buildings or other structures. Therefore, this work presents some results of a group of classic tests in the ambit of the Soils Mechanics (identification, compaction, direct shear and oedometer), in the sense of acquiring sensibility concerning the way as these soils behave when they are contaminated with gasoline.Fundação para a Ciência e Tecnologia (FCT) - CECUBI

    Swimming abilities of temperate pelagic fish larvae prove that they may control their dispersion in coastal areas

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    The Sense Acuity and Behavioral (SAAB) Hypothesis proposes that the swimming capabilities and sensorial acuity of temperate fish larvae allows them to find and swim towards coastal nursery areas, which are crucial for their recruitment. To gather further evidence to support this theory, it is necessary to understand how horizontal swimming capability varies along fish larvae ontogeny. Therefore, we studied the swimming capability of white seabream Diplodus sargus (Linnaeus, 1758) larvae along ontogeny, and their relationship with physiological condition. Thus, critical swimming speed (U-crit) and the distance swam (km) during endurance tests were determined for fish larvae from 15 to 55 days post-hatching (DPH), and their physiological condition (RNA, DNA and protein contents) was assessed. The critical swimming speed of white seabream larvae increased along ontogeny from 1.1 cm s(-1) (15 DPH) to 23 cm s(-1) (50 and 55 DPH), and the distance swam by larvae in the endurance experiments increased from 0.01 km (15 DPH) to 86.5 km (45 DPH). This finding supports one of the premises of the SAAB hypothesis, which proposes that fish larvae can influence their transport and distribution in coastal areas due to their swimming capabilities. The relationship between larvae's physiological condition and swimming capabilities were not evident in this study. Overall, this study provides critical information for understanding the link between population dynamics and connectivity with the management and conservation of fish stocks.Funding Agency Portuguese Foundation for Science and Technology SFRH/BD/104209/2014 Portuguese Foundation for Science and Technology UID/Multi/04326/2019 FCT, under the Transitional Norm DL57/2016/CP[1361]/CT[CT0008 CLIMFISH project-A framework for assess vulnerability of coastal fisheries to climate change in Portuguese coast n2/SAICT/2017-SAICTinfo:eu-repo/semantics/publishedVersio

    Portuguese 16th to Early 18th Century tin Glazed Ceramics Found at the Tagus Estuary Saltpans

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    UID/NAN/50024/2019 M-ERA-MNT/0002/2015 UIDB/04209/2020 UIDP/04209/2020Salt was extracted from saltpans, in the South shore of Tagus River by evaporation of the salted sea water which penetrates into the estuary. The walls and the bottom of those saltpans were made of local clays to retain the sea water, and ceramic sherds have been used to endure those walls and also to allow people to walk on the saltpans’ walls. Those sherds constitute an example of the ceramics production in Lisbon workshops, starting in the mid-16th century and reaching high levels of quality in the 17th and 18th century. A detailed archaeometric study of 14 selected sherds dated from the 16th to the early 18th century has been made and the conjugation of the information provided by the micro-Raman, XRD and XRF experiments for those sherds and clays collected locally, allowed us the characterisation of the Lisbon ceramics in that period. Three main groups could be identified in the ceramic bodies; all made with locally collected clays of Miocene origin. In the first group, the potters used raw materials from the clay sources located at Santa Catarina area in Lisbon, most probably mixed with Lapa clays, which were fired at a high temperatures, ranging from 850ºC to 950ºC. Gehlenite and quartz are the dominant minerals of these ceramic bodies. In the second and third groups of Lisbon ceramic bodies, made with Prazeres clays, diopside was also detected but with variable amounts of gehlenite. Clay formations mineralogy mainly include kaolinite, muscovite/illite, quartz, calcite, and feldspars (albite and microcline).publishersversionpublishe

    A diversificação das receitas bancárias: seu impacto sobre o risco e o retorno dos bancos brasileiros

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    O objetivo deste estudo é determinar o impacto da diversificação das receitas bancárias sobre o risco e o retorno dos bancos brasileiros. Essa estratégia foi adotada por bancos em diversos países, inclusive no Brasil. Em 2003, as receitas noninterest (não decorrentes de juros) representavam 17,80% da receita operacional dos bancos analisados e, em 2014, essa participação havia aumentado para 27,40%. Embora muitos estudos tenham abordado a questão para bancos americanos, europeus e asiáticos, este tema ainda não foi abordado para uma amostra de bancos brasileiros. Como o setor bancário é uma variável crucial à estabilidade do sistema financeiro, é importante estudar os fatores que afetam o risco e o retorno dos bancos. Analisamos a amostra para o período entre 2003 e 2014, utilizando dados em painel dinâmico através do Método Generalizado dos Momentos para abordar questões de endogeneidade, heterocedasticidade e autocorrelação. Nossos principais resultados mostram que as receitas noninterest possuem um papel importante no desempenho dos bancos estudados; nossa análise das atividades de intermediação financeira mostrou que as operações de crédito produziram melhores resultados do que as atividades de negociação de títulos. Além disso, confirmando as hipóteses propostas, as receitas noninterest apresentaram, de maneira geral, um impacto positivo sobre o retorno e o retorno ajustado ao risco nos bancos estudados. Entretanto, ao contrário do que esperávamos, as receitas noninterest mostraram uma relação positiva com o risco desses bancos (embora estatisticamente não significativa). É importante destacar as variáveis de controle, ou seja, a taxa de juros real, o PIB e o crescimento bancário, as quais foram relevantes para a determinação do desempenho dos bancos.The present study aims to determine the impact of bank revenue diversification on Brazilian banks’ risk and return. This strategy has been adopted by banks in several countries, including Brazil. In 2003, noninterest income accounted for 17.80% of the operating revenue of the banks analyzed, and in 2014, this share increased to 27.40%. While many studies have addressed the subject in American, European and Asian banks, it still has not been approached in a sample of Brazilian banks. Since the banking industry is a key variable for the financial system’s stability, it is important to study the factors that affect banks’ risk and return. We analyzed the sample for the period from 2003 to 2014, using dynamic panel data GMM (Generalized Method of Moments) to address endogeneity, heteroscedasticity and autocorrelation problems. Our main results show that noninterest income has a major role in the performance of the banks studied; our analysis of financial intermediation activities showed that loan operations produced better results than trading. Moreover, confirming the hypotheses proposed, noninterest income showed a generally positive impact on return and risk adjusted return for the banks studied. However, against our expectation, noninterest income showed a positive relationship with the risk of these banks (although not statistically significant). It is worth highlighting the control variables, i.e., real interest rate, GDP and bank growth, which were relevant in determining bank performance

    Ovarian Hyperstimulation Syndrome in a Spontaneous Pregnancy

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    Introdução: O Síndrome de Hiperestimulação do Ovário (SHO) geralmente é descrito como uma complicação iatrogénica dos tratamentos de indução da ovulação. Raramente, pode estar associado a ciclos ovulatórios espontâneos, sendo mais frequente em gravidez múltipla, patologia molar e hipotiroidismo. A apresentação clínica é variável, podendo nos casos mais graves ser fatal. Caso clínico: Grávida de 13 semanas, nulípara, sem história de tratamentos de infertilidade, referenciada por aumento bilateral do volume ovárico e ascite. Apresentava ligeiro desconforto abdominal, tendo a ecografia revelado ovários aumentados de volume, multiquísticos e ascite ligeira. Os níveis de estradiol estavam aumentados, com hCG e TSH normais. A terapêutica foi expectante, com uma evolução favorável. Discussão: O SHO espontâneo apesar de ser uma entidade rara, deve ser equacionada como hipótese diagnóstica nas situações de massa pélvica na gravidez. Estão descritos 3 possíveis mecanismos para o SHO espontâneo, baseados na permissividade do receptor ovárico da FSH para a hCG e/ou TSH, podendo ocorrer com níveis normais ou elevados de hCG e/ou TSH.

    Local dimension and finite time prediction in spatiotemporal chaotic systems

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    We show how a recently introduced statistics [Patil et al, Phys. Rev. Lett. 81 5878 (2001)] provides a direct relationship between dimension and predictability in spatiotemporal chaotic systems. Regions of low dimension are identified as having high predictability and vice-versa. This conclusion is reached by using methods from dynamical systems theory and Bayesian modelling. We emphasize in this work the consequences for short time forecasting and examine the relevance for factor analysis. Although we concentrate on coupled map lattices and coupled nonlinear oscillators for convenience, any other spatially distributed system could be used instead, such as turbulent fluid flows.Comment: 5 pagers, 7 EPS figure

    Colour profile analysis of Port Wines by different instrumental and visual methods

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    BACKGROUND: Wine colour is an important quality parameter, being the first sensorial attribute evaluated during wine tasting. The perception of wine colour can be different depending on many factors, including the depth of the sample under observation. The main objectives of the present study were to measure the colour of Port wines, using CIE L*a*b* parameters at different depths with different instrumental techniques (spectrophotometry and colorimetry), and to compare the obtained results with the sensory (visual) perception of colour samples. RESULTS: Representative profiles of Lightness (L*), Hue (H*) and Chroma (C*) at different depths were obtained using Port wine samples from different categories and ages. In general, relatively good correlations between the colorimetric and spectrophotometric methods were obtained for the L* and H* parameters. The results of the sensory tests also showed good correlations between the visually-assessed hue scores and the colorimetric measurements of the H* parameter, particularly at the lower depths tested (up to 4.0 mm). CONCLUSIONS: Overall, the results indicate that the colorimetric method can be used for estimating wine colour parameters, providing useful information about the colour profile of wines at different depthsinfo:eu-repo/semantics/acceptedVersio

    Description of a new species of Thamnodynastes Wagler, 1830 (Serpentes, Colubridae) from northeastern Brazil, with comments on the genus

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    Thamnodynastes almae sp. nov. is described based on three specimens from Rodelas Municipality, state of Bahia, Northeastern Brazil. The new species can be diagnosed by its pale coloration and keeled dorsal scales arranged in 19 rows at midbody and 15 rows posteriorly. Characters for distinguishing T. almae from other Brazilian species of Thamnodynastes are provided

    Exactly Solvable Interacting Spin-Ice Vertex Model

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    A special family of solvable five-vertex model is introduced on a square lattice. In addition to the usual nearest neighbor interactions, the vertices defining the model also interact alongone of the diagonals of the lattice. Such family of models includes in a special limit the standard six-vertex model. The exact solution of these models gives the first application of the matrix product ansatz introduced recently and applied successfully in the solution of quantum chains. The phase diagram and the free energy of the models are calculated in the thermodynamic limit. The models exhibit massless phases and our analyticaland numerical analysis indicate that such phases are governed by a conformal field theory with central charge c=1c=1 and continuosly varying critical exponents.Comment: 14 pages, 11 figure
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