786 research outputs found

    The upper Hauterivian Barremian (Lower Cretaceous) Arrifes section (Algarve Basin, Southern Portugal): a palynostratigraphic and palaeoenvironmental approach

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    ABSTRACT: Integrated sedimentological, palynological, and palynofacies analyses of the Arrifes section in the central Algarve Basin (southern Portugal) provided new information on the age and environments of this Lower Cretaceous sequence. The sedimentary succession at the Arrifes section consists of fossiliferous interbedded limestones, marly limestones, and marls, dated as latest Hauterivian to late Barremian age (Lower Cretaceous) based on key dinoflagellate taxa. During this interval, the Arrifes area records climatic shifts and, multiple sea-level fluctuations; overall deposition was in shallow subtidal to intertidal settings, with deposition of carbonate and marly sediments. During the latest Hauterivian to earliest Barremian interval, an evident sea-level fall culminated in the subaerial exposure of the local carbonate ramp with increased influx of clastic sediments. However, during the Barremian, both sedimentological and palynological analyses suggest an overall deepening of the water depth towards the top of the section. These overall increase in the water column are confirmed by oscillation of terrestrial/marine palynomorph groups and supported by dinosaur track levels at the top of the succession; the latter indicate that sedimentation occurred in intertidal to subtidal environments. Finally, an attempt was made to correlate the Arrifes section with other sections from the Algarve Basin, as well as with broader region. These new data suggest a setting in the Tethyan basin influenced during the latest Hauterivian to the end of the Barremian. These new data allow local correlations and new palynological ages and paleoenvironmental interpretations for the Lower Cretaceous succession of the Algarve Basin.info:eu-repo/semantics/publishedVersio

    Capacitated Center Problems with Two-Sided Bounds and Outliers

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    In recent years, the capacitated center problems have attracted a lot of research interest. Given a set of vertices VV, we want to find a subset of vertices SS, called centers, such that the maximum cluster radius is minimized. Moreover, each center in SS should satisfy some capacity constraint, which could be an upper or lower bound on the number of vertices it can serve. Capacitated kk-center problems with one-sided bounds (upper or lower) have been well studied in previous work, and a constant factor approximation was obtained. We are the first to study the capacitated center problem with both capacity lower and upper bounds (with or without outliers). We assume each vertex has a uniform lower bound and a non-uniform upper bound. For the case of opening exactly kk centers, we note that a generalization of a recent LP approach can achieve constant factor approximation algorithms for our problems. Our main contribution is a simple combinatorial algorithm for the case where there is no cardinality constraint on the number of open centers. Our combinatorial algorithm is simpler and achieves better constant approximation factor compared to the LP approach

    The age and depositional environments of the lower Karoo Moatize Coalfield of Mozambique: insights into the postglacial history of central Gondwana

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    ABSTRACT: The Moatize Coalfield belongs to a network of continental Karoo basins of central Mozambique, known as the Zambezi Basin. Palynological and sedimentological studies were performed on four coal exploration boreholes to determine the age, depositional settings, and overall geological evolution of its extensive coal deposits. Clastic formations recognised in this coalfield, in ascending order, are the Vúzi, Moatize and Matinde formations. Palynomorph assemblages indicate that the Moatize Coalfield succession ranges from Roadian (lower Guadalupian) to Changhsingian (upper Lopingian) in age. Two main depositional phases are identified, whose initiation and development are attributed to regional tectonic events and climate amelioration. The first phase formed towards the end of the deglacial period, characterised initially by fan deltas, represented by the upper Vúzi Formation, and the shift to lake–delta environments, represented by the lower part of the Moatize Formation. This phase took place from Roadian to the Wordian times. The lake–delta settings indicate a sediment aggradation trend with high subsidence rates in the lake basin, which, together with the associated post-glacial climate amelioration, led to the accumulation of coal deposits in swamps of the delta top and lake margins. The second depositional phase took place from Capitanian to Changhsingian times and related to fluvial environments initiated by uplift that reorganised the depocenter into alluvial plains characterised by bedload dominated rivers (braided) and overbank floodplains. Results obtained in this study provide critical information for the onset of the deglaciation events and the age of coal deposits in this part of Gondwana, important for wider stratigraphic correlation of these events in Africa and throughout the Gondwana.info:eu-repo/semantics/acceptedVersio

    INTERPRETANDO O LÍQUOR – COMO DADOS EPIDEMIOLÓGICOS PODEM AJUDAR NO RACIOCÍNIO CLÍNICO

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    Introdução: A meningite bacteriana sofreu grandes mudanças epidemiológicas após a introdução dos antibióticos e vacinas, passando de uma condição letal para tratável e prevenível. Compreender essas mudanças no perfil epidemiológico em nível local permitem planejar estratégias de terapia empírica. As alterações de líquor possuem papel fundamental nessa avaliação. Metodologia: Foi realizado um estudo transversal dos casos notificados de meningite entre janeiro de 2010 e junho de 2015 no Complexo Hospital de Clínicas – Universidade Federal do Paraná. Foram analisados a celularidade e citologia do líquor e os agentes etiológicos. Para as etiologias bacterianas, foi avaliado dados epidemiológicos. Resultados: Foram notificados 504 casos de meningite no período avaliado. A meningite asséptica foi a classificação epidemiológica mais comum. As meningites bacterianas com confirmação etiológica causadas por Neisseria meningitidis, Streptococcus pneumoniae ou Haemophilus influenzae ocorreram em 8,7% dos casos notificados, sendo que 30% delas ocorreram em menores de 1 ano. A N. meningitidis correspondeu a 61% desses casos, enquanto que S. pneumoniae a 34%. As meningites neutrofílicas com mais de 75% de neutrófilos são causadas por tais bactérias em mais da metade (53%). A meningite asséptica é a segunda principal etiologia (20%) seguida de perto pela meningite tuberculosa (17%). Os casos de meningite meningocócica se concentram em crianças até 1 ano (56% dos casos), a meningite pneumocócica se concentra nos adultos entre 18 e 50 anos (46%) e idosos (27%). Conclusões: O conhecimento da epidemiologia local através da interpretação do líquor, somada à avaliação da faixa etária são importantes aliados da avaliação clínica para determinação do agente etiológico mais provável e podem ajudar na decisão terapêutica

    IFNAR1-Signalling Obstructs ICOS-mediated Humoral Immunity during Non-lethal Blood-Stage Plasmodium Infection

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    Funding: This work was funded by a Career Development Fellowship (1028634) and a project grant (GRNT1028641) awarded to AHa by the Australian National Health & Medical Research Council (NHMRC). IS was supported by The University of Queensland Centennial and IPRS Scholarships. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

    Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool

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    Ethnic Belarusians make up more than 80% of the nine and half million people inhabiting the Republic of Belarus. Belarusians together with Ukrainians and Russians represent the East Slavic linguistic group, largest both in numbers and territory, inhabiting East Europe alongside Baltic-, Finno-Permic- and Turkic-speaking people. Till date, only a limited number of low resolution genetic studies have been performed on this population. Therefore, with the phylogeographic analysis of 565 Y-chromosomes and 267 mitochondrial DNAs from six well covered geographic sub-regions of Belarus we strove to complement the existing genetic profile of eastern Europeans. Our results reveal that around 80% of the paternal Belarusian gene pool is composed of R1a, I2a and N1c Y-chromosome haplogroups – a profile which is very similar to the two other eastern European populations – Ukrainians and Russians. The maternal Belarusian gene pool encompasses a full range of West Eurasian haplogroups and agrees well with the genetic structure of central-east European populations. Our data attest that latitudinal gradients characterize the variation of the uniparentally transmitted gene pools of modern Belarusians. In particular, the Y-chromosome reflects movements of people in central-east Europe, starting probably as early as the beginning of the Holocene. Furthermore, the matrilineal legacy of Belarusians retains two rare mitochondrial DNA haplogroups, N1a3 and N3, whose phylogeographies were explored in detail after de novo sequencing of 20 and 13 complete mitogenomes, respectively, from all over Eurasia. Our phylogeographic analyses reveal that two mitochondrial DNA lineages, N3 and N1a3, both of Middle Eastern origin, might mark distinct events of matrilineal gene flow to Europe: during the mid-Holocene period and around the Pleistocene-Holocene transition, respectively
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