1,739 research outputs found

    Frequency-Dependent Streaming Potential of Porous Media—Part 2: Experimental Measurement of Unconsolidated Materials

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    Frequency-dependent streaming potential coefficient measurements have been made upon Ottawa sand and glass bead packs using a new apparatus that is based on an electromagnetic drive. The apparatus operates in the range 1 Hz to 1 kHz with samples of 25.4 mm diameter up to 150 mm long. The results have been analysed using theoretical models that are either (i) based upon vibrational mechanics, (ii) treat the geological material as a bundle of capillary tubes, or (iii) treat the material as a porous medium. The best fit was provided by the Pride model and its simplification, which is satisfying as this model was conceived for porous media rather than capillary tube bundles. Values for the transition frequency were derived from each of the models for each sample and were found to be in good agreement with those expected from the independently measured effective pore radius of each material. The fit to the Pride model for all four samples was also found to be consistent with the independently measured steady-state permeability, while the value of the streaming potential coefficient in the low-frequency limit was found to be in good agreement with other steady-state streaming potential coefficient data

    Auditory spatial deficits following hemispheric lesions: Dissociation of explicit and implicit processing.

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    Auditory spatial deficits occur frequently after hemispheric damage; a previous case report suggested that the explicit awareness of sound positions, as in sound localisation, can be impaired while the implicit use of auditory cues for the segregation of sound objects in noisy environments remains preserved. By assessing systematically patients with a first hemispheric lesion, we have shown that (1) explicit and/or implicit use can be disturbed; (2) impaired explicit vs. preserved implicit use dissociations occur rather frequently; and (3) different types of sound localisation deficits can be associated with preserved implicit use. Conceptually, the dissociation between the explicit and implicit use may reflect the dual-stream dichotomy of auditory processing. Our results speak in favour of systematic assessments of auditory spatial functions in clinical settings, especially when adaptation to auditory environment is at stake. Further, systematic studies are needed to link deficits of explicit vs. implicit use to disability in everyday activities, to design appropriate rehabilitation strategies, and to ascertain how far the explicit and implicit use of spatial cues can be retrained following brain damage

    A new brain segmentation framework

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    Potential impact of the 2017 ACC/AHA guideline on high blood pressure in normotensive patients with stable coronary artery disease: insights from the CLARIFY registry

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    Aims: The 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline on high blood pressure (BP) lowered the threshold defining hypertension and BP target in high-risk patients to 130/80 mmHg. Patients with coronary artery disease and systolic BP 130-139 mmHg or diastolic BP 80-89 mmHg should now receive medication to achieve this target. We aimed to investigate the relationship between BP and cardiovascular events in 'real-life' patients with coronary artery disease considered as having normal BP until the recent guideline. Methods and results: Data from 5956 patients with stable coronary artery disease, no history of hypertension or heart failure, and average BP <140/90 mmHg, enrolled in the CLARIFY registry (November 2009 to June 2010), were analysed. In a multivariable-adjusted Cox proportional hazards model, after a median follow-up of 5.0 years, diastolic BP 80-89 mmHg, but not systolic BP 130-139 mmHg, was associated with increased risk of the primary endpoint, a composite of cardiovascular death, myocardial infarction, or stroke (hazard ratio 2.15, 95% confidence interval 1.22-3.81 vs. 70-79 mmHg and 1.12, 0.64-1.97 vs. 120-129 mmHg). No significant increase in risk for the primary endpoint was observed for systolic BP <120 mmHg or diastolic BP <70 mmHg. Conclusion: In patients with stable coronary artery disease defined as having normal BP according to the 140/90 mmHg threshold, diastolic BP 80-89 mmHg was associated with increased cardiovascular risk, whereas systolic BP 130-139 mmHg was not, supporting the lower diastolic but not the lower systolic BP hypertension-defining threshold and treatment target in coronary artery disease. ClinicalTrials identifier: ISRCTN43070564

    Cross-Sectional Comparison of Health-Span Phenotypes in Young versus Geriatric Marmosets

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    The development of the marmoset as a translational model for healthspan and lifespan studies relies on the characterization of health parameters in young and geriatric marmosets. This cross‐sectional study examined health phenotypes in marmosets for five domains of interest for human health and aging: mobility, cognition, metabolism, homeostasis, and immune function. Geriatric marmosets were found to have significant executive function impairment when compared to young animals. While geriatric animals did not show gross abnormalities in mobility and measures of locomotion, their types of movement were altered from young animals. Geriatric marmosets had alterations in cardiac function, with significantly increased mean arterial pressures; metabolism, with significantly lower VO2; and suppressed immune function. Further, this study sought to characterize and describe histopathology for both young and geriatric healthy marmosets. Overall this study provides a characterization of health parameters for young and geriatric marmosets which will greatly enhance future aging and interventional testing in marmosets

    Limites e possibilidades da formação inicial para o desenvolvimento de práticas docentes autônomas

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    RESUMO Este artigo reúne bases empíricas de dois projetos de pesquisa mais amplos que focalizam as relações entre formação e profissão docente em cursos de Pedagogia e de Licenciatura em Ciências Biológicas. Objetivamos investigar os saberes mobilizados e&#8260;ou produzidos por professores especialistas e polivalentes para o desenvolvimento de práticas autônomas e sua relação com a formação inicial. Mobilizamos referenciais teóricos dos Saberes Docentes para a análise da autonomia docente sob um enfoque relacional em depoimentos de professores da educação básica. As informações sobre experiências formativas na graduação e na fase inicial da carreira do magistério foram adquiridas por meio de entrevistas e discussão coletiva e as análises buscaram problematizar relações entre formação, profissão e condicionantes que favorecem o desenvolvimento de práticas autônomas. Os resultados evidenciam fragilidades relativas à formação no que tange às práticas docentes, com destaque para: domínio de conteúdos e metodologias de ensino. Os depoimentos apontam, também, que determinados temas foram mal compreendidos ou despertaram pouco interesse na ocasião da graduação, mas passaram a fazer sentido ou a gerar inquietações após os embates com as exigências da escola. As interpretações dos depoimentos apontam para a necessidade de valorização da dimensão profissional da docência durante a formação inicial, como condição para o desenvolvimento de práticas autônomas
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