8,582 research outputs found

    Shelf-Ocean material exchange influencing the Atlantic chemical composition off NW Iberian margin since the last glaciation

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    Rivers are the main conduit of sediment to the shelf. The basin geology, the drainage area and the discharge rate are the major factors that determine their sediment load (Milliman and Syvistski, 1992). Besides suspended particles, dissolved components may also give some information on the eroded crust. Sr isotopes in carbonate shells of biological organisms have been used to study, in the geological record, the influence exerted by the chemical weathering of the continental crust on the seawater composition (Macdougall, 1991). In this work, Sr isotope ratios obtained in tests of foraminifera representing the last 40 ka are presented and discussed in the scope of the palaeogeographical evolution of NW Iberia. This work aims to present and discuss the results of Sr isotope analyses (performed, by TIMS, in the Isotope Geology Laboratory of the University of Aveiro) of tests of two species of foraminifera, from nine samples taken along the OMEX core KC 024-19 (181 cm; 42°08’98’’N, 10°29´96’’W, and 2765m), collected in the Galicia Bank area, off Galicia. Taking into account that Sr contained in the carbonate tests is usually considered as preserving the signature of the contemporaneous seawater, one planktonic species (Globigerina bulloides) and one benthic species (Cibicides wuellerstorfi) were selected in order to try to detect Sr isotope variations both through time and between two different levels of the water column. The core age model, which records the last 40 ka, is based on a combination of oxygen isotope stratigraphy, eight AMS 14C datings and the synchronisation of the last four Heinrich Events in the Iberian Margin sedimentary records. As a whole, the obtained 87Sr/86Sr ratios vary between 0.709209 and 0.709108, with a mean 2σ error of 0.000025. These values lie within the range of modern marine Sr isotope ratios (0.70910-0.70922), as previously defined using analyses of both seawater and marine carbonates (see compilation by Faure and Mensing, 2005). Despite their small variation, the 87Sr/86Sr ratios obtained in G. bulloides seem to indicate that Sr dissolved in seawater at the KC 024-19 core site became slightly less radiogenic after the Last Glacial Maximum (LGM). This decrease is concomitant with diminishing amounts of the detrital components in the sediments (Fig. 1). Therefore, both the composition of dissolved Sr, as revealed by results on tests of planktonic foraminifera, and the proportions of suspended terrigenous particulate material arriving at the KC 024-19 site point to a decreasing importance of the contribution of the erosion of the Iberian Variscan crust since the Last Glacial Maximum and in the Holocene. The 87Sr/86Sr ratios measured in tests of benthic foraminifera (C. wuellerstorfi) are more erratic and no correlation can be established with palaeogeographical/palaeoclimatic constraints. The difference between the behaviour of Sr compositions in G. bulloides and C. wuellerstorfi may indicate that whilst the planktonic foraminifera should reproduce very closely the seawater composition, the benthic organisms should, in addition to the major role of seawater, also be affected by some sort of interaction with the sediments. As such, planktonic foraminifera are probably more reliable indicators of seawater composition in studies involving very small periods and corresponding very slight variations of the 87Sr/86Sr ratios. Taking into account that G. bulloides is a common planktonic species (living mostly in the first 50m of the water column), whose tests seem to be in equilibrium with sea water composition, variations in its 87Sr/86Sr ratios can be related with changes in the chemical composition of the water of the Atlantic Ocean off NW Iberian Margin. The highest 87Sr/86Sr values are contemporaneous with a period of low sea level (about -140 m; Dias et al., 2000) during the LGM. According to Dias et al. (2000) at 18 ka BP the shoreline was close to the shelf break. The summital parts of the Gerês and Estrela mountains were covered by local glaciers and close to the coast freezing occurred frequently. The river catchments, which extended far to the shelf, received more rainfall due to a longer, compared to present day conditions, wet season, which promoted both physical and chemical weathering. Higher pluviosity combined with the effect of spring ice melting maintained high river discharge and consequently caused very important sediment supply to the coastal zone. The extremely narrow shelf was a very energetic environment due to sea bottom inclination and very limited long wave refraction. Therefore, at that time, a long wet season and very competent rivers should have caused important erosion of the Variscan basement in NW Iberia. Additionally, then, the shoreline was much closer to the KC 024-19 site. The combination of all these factors favoured an important deposition of terrigenous sediments and the local slight enrichment in radiogenic Sr of the seawater. With sea level rise, after the deglaciation and during the Holocene, the river estuaries became progressively far away from the shelf break. Their competence of transport also became progressively reduced and the offshore transport of detrital sediments became progressively lower. Conversely the biogenic carbonate proportion in the sediments increased, due to lower dilution by the terrigenous particles. Simultaneously, the values of 87Sr/86Sr in the seawater at the KC 024-19 site became lower, as a consequence of a complete homogenization with the ocean global composition, which was now more effective with the increasing distance towards shoreline

    Thrombus aspiration in patients with ST-elevation myocardial infarction: results of a national registry of interventional cardiology.

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    BACKGROUND: We aimed to evaluate the impact of thrombus aspiration (TA) during primary percutaneous coronary intervention (P-PCI) in 'real-world' settings. METHODS: We performed a retrospective study, using data from the National Registry of Interventional Cardiology (RNCI 2006-2012, Portugal) with ST-elevation myocardial infarction (STEMI) patients treated with P-PCI. The primary outcome, in-hospital mortality, was analysed through adjusted odds ratio (aOR) and 95% confidence intervals (95%CI). RESULTS: We assessed data for 9458 STEMI patients that undergone P-PCI (35% treated with TA). The risk of in-hospital mortality with TA (aOR 0.93, 95%CI:0.54-1.60) was not significantly decreased. After matching patients through the propensity score, TA reduced significantly the risk of in-hospital mortality (OR 0.58, 95%CI:0.35-0.98; 3500 patients). CONCLUSIONS: The whole cohort data does not support the routine use of TA in P-PCI, but the results of the propensity-score matched cohort suggests that the use of selective TA may improve the short-term risks of STEMI.info:eu-repo/semantics/publishedVersio

    Geoprivacy in Neighbourhoods and Health Research: A Mini-Review of the Challenges and Best Practices in Epidemiological Studies

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    Neighbourhood and health research often relies on personal location data (e.g., home address, daily itineraries), despite the risks of geoprivacy breaches. Thus, geoprivacy is an important emerging topic, contemplated in international regulations such as the General Data Protection Regulation. In this mini-review, we briefly assess the potential risks associated with the usage of personal location data and provide geoprivacy-preserving recommendations to be considered in epidemiological research. Risks include inference of personal information that the individual does not wish to disclose, reverse-identification and security breaches. Various measures should be implemented at different stages of a project (pre-data collection, data processing, data analysis/publication and data sharing) such as informed consent, pseudo-anonymization and geographical methods. Copyright © 2022 Ribeiro, Dias, Ribeiro, Silva and Barros.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalisation and national funding from the Foundation for Science and Technology—FCT (Portuguese Ministry of Science, Technology and Higher Education) under the Unidade de Investigação em Epidemiologia—Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (UIDB/04750/2020), Laboratório para a Investigação Integrativa e Translacional em Saúde Populacional (ITR) (LA/P/0064/2020) and the project “HUG: The health impacts of inner-city gentrification, displacement and housing insecurity: a quasi-experimental multi-cohort study” (PTDC/GES-OUT/1662/2020). AR was supported by National Funds through FCT, under the “Stimulus of Scientific Employment—Individual Support” programme within the contract CEECIND/02386/2018

    Desempenho de laranjeiras em Capitão Poço, PA.

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    O estudo teve como objetivo avaliar o comportamento de 13 variedades de laranjeiras (Citrus sinensis (L.) osbeck) nas condições edafoclimáticas de Capitão Poço, PA, a fim de selecionar aquelas superiores para caracteres de interesse agronômico e econômico. O trabalho foi desenvolvido em solo tipo Latossolo Amarelo distrófico, clima tipo Ami da classificação de Köppen, sendo avaliadas as variedades de laranjeiras, PêraD6; Sunstar; Pinneaple; Parson Brown; Westin; Gardner; BaianinhaIAC79; Valênciacnpmf27; Natalcnpmf112; Salustiana; Rubi; Midsweet; e Seleta. Os dados foram coletados em plantas com 4 anos de idade, sendo estes: produção de frutos por planta e por safra; peso do fruto e do suco; espessura da casca e diâmetros transversal; e longitudinal do fruto. Do suco, determinaram-se a acidez total titulável, sólidos solúveis totais, pH e relação sólidos solúveis totais/acidez total titulável. Detectaram-se diferenças significativas (p<0,05) para produção de frutos e espessura de casca, e altamente significativas (p<0,01) para peso do fruto e do suco e diâmetros transversal e longitudinal. Os resultados demonstraram que as cultivares se adaptaram bem às condições edafoclimáticas da região produtora de Capitão Poço, e que é possível produzir, na região, frutos que possam ser destinados a indústrias processadoras de suco concentrado e congelado, e que as laranjeiras Westin, BaianinhaICA 79, Pinneaple e Rubi poderão compor os sistemas de produção, cujo destino seja produzir frutos para o mercado de consumo "in natura".bitstream/item/37708/1/ORIENTAL-BPD57.pdfVersão eletrônica. 1ª impressão: 2009

    Symbolic Sequences and Tsallis Entropy

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    We address this work to investigate symbolic sequences with long-range correlations by using computational simulation. We analyze sequences with two, three and four symbols that could be repeated ll times, with the probability distribution p(l)1/lμp(l)\propto 1/ l^{\mu}. For these sequences, we verified that the usual entropy increases more slowly when the symbols are correlated and the Tsallis entropy exhibits, for a suitable choice of qq, a linear behavior. We also study the chain as a random walk-like process and observe a nonusual diffusive behavior depending on the values of the parameter μ\mu.Comment: Published in the Brazilian Journal of Physic

    Desempenho econômico de clones de cajueiro-anão-precoce em cultivo de quarto ano de produção no município de Picos, PI.

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    Avaliação de clones de cajueiro-anão-precoce no cerrado do sul maranhense.

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    Avaliação de Clones de Cajueiro-Anão-Precoce no Cerrado do Sul Maranhense; Introdução; Desenvolvimento; Biometria; Produtividade; Características do fruto; Aptidão comercial; Distribuição média mensal da produção de castanha; Características agroeconômicas; Comercialização da produção; Comparativos econômicos.bitstream/item/37219/1/Doc145.pd

    Comportamento produtivo de oito clones de cajueiro-anão-precoce em cultivo de terceiro ano sob regime de sequeiro.

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    Avaliação de clones de cajueiro-anão-precoce em cultivo de terceiro ano no semi-árido piauiense.

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    O objetivo deste trabalho foi avaliar o desempenho produtivo de oito clones de cajueiro anão precoce no semi-árido piauiense, visando identificar os mais promissores para a produção de castanha e caju para mesa..
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