60 research outputs found

    Actes des I Journées Francophones de l'Université d'Aveiro, 1996

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    Three-Dimensional Numerical Simulations of Equatorial Spread F: Results and Observations in the Pacific Sector

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    A three-dimensional numerical simulation of plasma density irregularities in the postsunset equatorial F region ionosphere leading to equatorial spread F (ESF) is described. The simulation evolves under realistic background conditions including bottomside plasma shear flow and vertical current. It also incorporates C/NOFS satellite data which partially specify the forcing. A combination of generalized Rayleigh-Taylor instability (GRT) and collisional shear instability (CSI) produces growing waveforms with key features that agree with C/NOFS satellite and ALTAIR radar observations in the Pacific sector, including features such as gross morphology and rates of development. The transient response of CSI is consistent with the observation of bottomside waves with wavelengths close to 30 km, whereas the steady state behavior of the combined instability can account for the 100+ km wavelength waves that predominate in the F region

    "Validity of a scale of Latin American perception of fear and concern transmitted by the media during the pandemic (MED-LAT-COVID-19)"

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    "Introduction: The pandemic has caused fear, especially due to the daily disseminated news; however, there is not an instrument to measure this fear in multiple realities. Objective: To validate a scale for Latin American perception of fear and concern transmitted by the media during the pandemic. Methodology: This is an instrumental study. The survey was based on an instrument which was pre-validated in Peru and submitted to 15 experts in almost 10 countries. Subsequently, thousands of people were surveyed in 13 Latin American countries, whose answers were used for descriptive statistics for validation. Results: Confirmatory Factor Analysis (CFA) generated two re-specifications, where four items were eliminated from the original scale. With these changes, the global goodness of fit (absolute and incremental) were satisfactory (CFI ¼ 0.978; TLI ¼ 0.964; GFI ¼ 0.976; AGFI ¼ 0.949; RMSEA ¼ 0.075 and RMR ¼ 0.029). The first factor measures the media exaggeration (three questions); the second, the fear transmitted by the media (three questions); and the third, the fear transmitted by others different from the media (two questions). The Cronbach’s alpha coefficient was higher than 0.70 for the scale and its factors. Conclusion: The MED-LAT-COVID-19 scale reported a good adjustment. It has eight items in three factors, which could be measured in an isolated way, or along with other tests that assess mental health in the current pandemic context.

    Asociación entre bajo peso al nacer y malformaciones congénitas

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    Introducción: Las anomalías congénitas son defectos estructurales o funcionales durante la vida intrauterina. Es poco conocida la relación existente entre el bajo peso al nacer y la predisposición a una anomalía congénita. Objetivo: Evaluar la asociación entre el bajo peso al nacer y la manifestación de anomalías congénitas en neonatos. Métodos: Se realizó un estudio transversal. La población de estudio fueron madres que dieron a luz a neonatos en un hospital de Asunción, Paraguay, en 2018. Se crearon fichas de recolección de datos con las características maternas y neonatales. La variable desenlace fue malformaciones congénitas al nacimiento. La variable exposición fue bajo peso al nacer, definido como el reporte clínico de peso menor a 2 500 gramos en un neonato. Resultados: De 225 mujeres, se encontró que el 26,7 % presentó infecciones de transmisión maternoneonatal (60/165); 102 (45,3 %) fueron prematuros y 79 (35,1 %) presentaron malformaciones congénitas. Se evidenció asociación positiva entre antecedente de bajo peso al nacer y malformaciones congénitas (RP= 2,32; IC 95 %: 1,68-3,20). Conclusiones: Se evidencia una asociación positiva entre el antecedente de bajo peso al nacer y la presencia de malformaciones congénitas.Campus Lima Centr
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