396 research outputs found

    A 2D computational parametric analysis of the sheltering effect of fences on a railway vehicle standing on a bridge and experiencing crosswinds

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    In a crosswind scenario, the risk of high-speed trains overturning increases when they run on viaducts since the aerodynamic loads are higher than on the ground. In order to increase safety, vehicles are sheltered by fences that are installed on the viaduct to reduce the loads experienced by the train. Windbreaks can be designed to have different heights, and with or without eaves on the top. In this paper, a parametric study with a total of 12 fence designs was carried out using a two-dimensional model of a train standing on a viaduct. To asses the relative effectiveness of sheltering devices, tests were done in a wind tunnel with a scaled model at a Reynolds number of 1 × 105, and the train’s aerodynamic coefficients were measured. Experimental results were compared with those predicted by Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations of flow, showing that a computational model is able to satisfactorily predict the trend of the aerodynamic coefficients. In a second set of tests, the Reynolds number was increased to 12 × 106 (at a free flow air velocity of 30 m/s) in order to simulate strong wind conditions. The aerodynamic coefficients showed a similar trend for both Reynolds numbers; however, their numerical value changed enough to indicate that simulations at the lower Reynolds number do not provide all required information. Furthermore, the variation of coefficients in the simulations allowed an explanation of how fences modified the flow around the vehicle to be proposed. This made it clear why increasing fence height reduced all the coefficients but adding an eave had an effect mainly on the lift force coefficient. Finally, by analysing the time signals it was possible to clarify the influence of the Reynolds number on the peak-to-peak amplitude, the time period and the Strouhal number

    A 2D computational parametric analysis of the sheltering effect of fences on a railway vehicle standing on a bridge and experiencing crosswinds

    Full text link
    In a crosswind scenario, the risk of high-speed trains overturning increases when they run on viaducts since the aerodynamic loads are higher than on the ground. In order to increase safety, vehicles are sheltered by fences that are installed on the viaduct to reduce the loads experienced by the train. Windbreaks can be designed to have different heights, and with or without eaves on the top. In this paper, a parametric study with a total of 12 fence designs was carried out using a two-dimensional model of a train standing on a viaduct. To asses the relative effectiveness of sheltering devices, tests were done in a wind tunnel with a scaled model at a Reynolds number of 1 × 105, and the train’s aerodynamic coefficients were measured. Experimental results were compared with those predicted by Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations of flow, showing that a computational model is able to satisfactorily predict the trend of the aerodynamic coefficients. In a second set of tests, the Reynolds number was increased to 12 × 106 (at a free flow air velocity of 30 m/s) in order to simulate strong wind conditions. The aerodynamic coefficients showed a similar trend for both Reynolds numbers; however, their numerical value changed enough to indicate that simulations at the lower Reynolds number do not provide all required information. Furthermore, the variation of coefficients in the simulations allowed an explanation of how fences modified the flow around the vehicle to be proposed. This made it clear why increasing fence height reduced all the coefficients but adding an eave had an effect mainly on the lift force coefficient. Finally, by analysing the time signals it was possible to clarify the influence of the Reynolds number on the peak-to-peak amplitude, the time period and the Strouhal number

    Educational Research: Material Culture And Its Representation

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    Review of the book: Reseña del libro: Paul Smeyers y MarcDepaepe (eds.). Educational research: material culture and its representation. Cham: Springer International Publishing, 2014, 219 páginas. ISBN: 9783319030821; 9783319030838Reseña del libro: Paul Smeyers y MarcDepaepe (eds.). Educational research: material culture and its representation. Cham: Springer International Publishing, 2014, 219 páginas. ISBN: 9783319030821; 978331903083

    PROCESSOS DE TRABALHO NA ATENÇÃO PRIMÁRIA À SAÚDE E A IMPLANTAÇÃO DAS LINHAS-GUIA NOS MUNICÍPIOS DE UMA GERÊNCIA REGIONAL DE SAÚDE EM MINAS GERIAS: UMA ANÁLISE MULTICRITÉRIO

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    O trabalho objetivou verificar a relação entre processo de trabalho e implantação das Linhas Guias (LG) e propor um índice-síntese, considerando os processos de trabalho como indicador da potencialidade municipal para implantação das LG. Estudo quantitativo transversal exploratório, utilizado a Multi-Attribute Utility Theory realizado em 23 municípios de uma gerência de saúde. Os processos de trabalho: agenda (r: 0,51; p: 0,013), diagnóstico (r: 0,54. p: 0,008) e acesso (r: 0,51; p: 0,013), apresentaram correlação de moderada a alta com  implementação das LG. O índice-síntese explica 42% da implantação das LG. Os resultados contribuem para a gestão da avaliação em saúde evidenciando condicionantes para uma efetiva implantação das LG

    Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

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    Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

    Parental practices and beliefs on motor development in the first year of life

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    Introduction: In the child’s first year of life, motor development is critical for the other areas of child development. Beliefs and parenting practices influence the parents’ care and encouragement of their children, reflecting in their motor development; however, the Brazilian literature on this subject is scarce. Objective:to characterize the parental practices and beliefs associated with motor development in the first year of life; and to verify if practices and beliefs are interrelated. Methods: Two questionnaires were developed and applied, one about parenting practices and the other about parental beliefs on motor development in the first year life, to 27 caregivers of children between 12 and 24 months of age, who participated in an aquatic stimulation program. The agreement between practices and beliefs was verified by a graphical method, based on the  transformation of ordinal scores to an interval scale using Rasch analysis. Results: The participants had higher levels of education and economic status. They reported a variety of practices focused on the motor development of their children, such as family interaction through playing, toy offers, lap time and free movement space. Conclusion: Most of the practices were based on parental beliefs, for some activities, however, beliefs and practices diverged, demonstrating the complexity inherent to the formation of parental beliefs

    Equipamento inderbitzen modificado para simulação da erosão hídrica em amostras de solo indeformado

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    Several devices have been developed to assess soil losses by water erosion. However, they rarely assess the combined effects of raindrop impact and surface runoff together with vegetation cover on varying slopes. This study aimed to design and validate an equipment, on laboratory scale, to evaluate the effect of water erosion on undisturbed soil samples with and without plant cover, as well as to assess the kinetic energy of simulated rain and the resultant shear stress at varying runoff intensities. The equipment is composed of a rainfall simulator, an adjustable stand for different slopes and falling heights, and a runoff ramp for testing undisturbed soil samples measuring 15 x 20 x 40 cm (height, width, and length). In this study, the equipment simulated and evaluated the effect of precipitation and runoff on soil losses, allowing to obtain different values of the kinetic energy of precipitation and runoff. For a f low rate of 12 L min-1 and slope of 35%, the shear stress could reach up to 8 Pa. Furthermore, the equipment showed the effect of vegetation cover and slope on soil losses in different granulometric fractions (< 0.106 mm, 0.106 to 0.25 mm, 0.25 to 0.5 mm, 0.5 to 1.0 mm, 1.0 to 2.0 mm, and > 2.0 mm), revealing the potential of its use in several erosion studies on a laboratory scale.Diversos equipamentos foram desenvolvidos para a avaliação das perdas de solo por erosão hídrica. No entanto, raramente eles avaliam o efeito do impacto das gotas de chuva e do escoamento superficial em conjunto com a cobertura vegetal em diferentes declividades. Este estudo objetivou projetar e validar um equipamento, em escala de laboratório, para avaliar o efeito da erosão hídrica em amostras indeformadas de solo, bem como avaliar a velocidade de queda e tamanho das gotas de chuva simulada na superfície do solo e a intensidade do escoamento superficial em amostras com e sem cobertura vegetal. O equipamento é composto de um simulador de chuva, um suporte ajustável para diferentes declividades e alturas de queda e uma rampa de escoamento para testar amostras de solo indeformadas, com 15 x 20 x 40 cm (altura, largura e comprimento). Neste estudo, o equipamento simulou e avaliou o efeito da precipitação e do escoamento superficial nas perdas de solo, possibilitando a obtenção de diferentes valores de energia cinética de precipitação e escoamento. Para uma vazão de 12 L min-1 e inclinação de 35%, a tensão de cisalhamento pode chegar a 8 Pa. Além disso, o equipamento evidenciou o efeito da cobertura vegetal e da declividade nas perdas de solo em diferentes frações granulométricas (< 0,106 mm, 0,106 a 0,25 mm, 0,25 a 0,5 mm, 0,5 a 1,0 mm, 1,0 a 2,0 mm, e > 2,0 mm), demonstrando o potencial do seu uso em diversos estudos de erosão em escala de laboratório

    Bioprinting Decellularized Breast Tissue for the Development of Three-Dimensional Breast Cancer Models

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    The tumor extracellular matrix (ECM) plays a vital role in tumor progression and drug resistance. Previous studies have shown that breast tissue-derived matrices could be an important biomaterial to recreate the complexity of the tumor ECM. We have developed a method for decellularizing and delipidating a porcine breast tissue (TDM) compatible with hydrogel formation. The addition of gelatin methacrylamide and alginate allows this TDM to be bioprinted by itself with good printability, shape fidelity, and cytocompatibility. Furthermore, this bioink has been tuned to more closely recreate the breast tumor by incorporating collagen type I (Col1). Breast cancer cells (BCCs) proliferate in both TDM bioinks forming cell clusters and spheroids. The addition of Col1 improves the printability of the bioink as well as increases BCC proliferation and reduces doxorubicin sensitivity due to a downregulation of HSP90. TDM bioinks also allow a precise three-dimensional printing of scaffolds containing BCCs and stromal cells and could be used to fabricate artificial tumors. Taken together, we have proven that these novel bioinks are good candidates for biofabricating breast cancer models

    From secondary school to university: associations between sport participation and total and domain-specific sedentary behaviours in Spanish students

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    Effective ways to reduce sedentary behaviour in adolescents are needed to mitigate the risk of chronic disease and poor mental health. Organised sport participation is the most practiced physical activity during adolescence. However, the influence sport participation has on sedentary behaviours remains unclear. This study investigated the associations between sport participation, total and domain-specific sedentary behaviour and physical activity during the transition from secondary school to university. A 3-year longitudinal survey followed Spanish secondary school students (n = 113) to their first year of university. Generalized linear models, adjusted by gender and year, assessed the relationships between sport participation, total and domain-specific sedentary behaviour and physical activity. Compared with non-sport participants, teenagers who played individual sports from baseline during secondary school spent significantly less total time sitting (− 110.5 min/day at weekends), watching television (− 18.7 min/day at weekends) or using the computer for leisure (− 37.4 min/day weekdays). Those who played team sports from baseline at secondary school spent less time sitting (− 126.4 min/day at weekends) or socialising (− 37 min/day at weekends). Conclusion: From secondary school to university, sport participation–based interventions might be an effective strategy to reduce sitting time spent on some domain-specific behaviours. Promoting sports could reduce the rise of sedentary behaviour during adolescence, a stage where sedentary behaviour evolves
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