Short-range exposure to airborne virus transmission and current guidelines

After the Spanish flu pandemic, it was apparent that airborne transmission was crucial to spreading virus contagion, and research responded by producing several fundamental works like the experiments of Duguid [J. P. Duguid, J. Hyg. 44, 6 (1946)] and the model of Wells [W. F. Wells, Am. J. Hyg. 20, 611\u2013618 (1934)]. These seminal works have been pillars of past and current guidelines published by health organizations. However, in about one century, understanding of turbulent aerosol transport by jets and plumes has enormously progressed, and it is now time to use this body of developed knowledge. In this work, we use detailed experiments and accurate computationally intensive numerical simulations of droplet-laden turbulent puffs emitted during sneezes in a wide range of environmental conditions. We consider the same emission\u2014number of drops, drop size distribution, and initial velocity\u2014and we change environmental parameters such as temperature and humidity, and we observe strong variation in droplets\u2019 evaporation or condensation in accordance with their local temperature and humidity microenvironment. We assume that 3% of the initial droplet volume is made of nonvolatile matter. Our systematic analysis confirms that droplets\u2019 lifetime is always about one order of magnitude larger compared to previous predictions, in some cases up to 200 times. Finally, we have been able to produce original virus exposure maps, which can be a useful instrument for health scientists and practitioners to calibrate new guidelines to prevent short-range airborne disease transmission

Suplementação da dieta de codornas com minerais nas formas orgânicas sobre o desempenho e a qualidade dos ovos

Foram realizados três experimentos com o objetivo de avaliar o efeito da suplementação de minerais na forma orgânica na dieta de codornas japonesas na fase de postura sobre o desempenho e a qualidade de ovos das aves. Os níveis de minerais utilizados por kg de ração, para cada experimento, foram: controle, 0,35, 0,70 e 1,05mg de Se orgânico (experimento 1); controle, 50, 100 e 150mg de Zn orgânico (experimento 2) e controle, 60, 120 e 180mg de Mn orgânico (experimento 3). As aves foram distribuídas em delineamento inteiramente ao acaso, sendo oito aves por parcela e seis repetições por tratamento. Foram avaliadas as características de desempenho - consumo diário de ração, peso dos ovos, porcentagem de postura, conversão alimentar por massa de ovos e por dúzia de ovos e viabilidade - e qualidade dos ovos - unidade Haugh, índice gema, porcentagens de casca, albúmen e gema, espessura de casca e gravidade específica. O Zn orgânico suplementado à dieta melhorou o desempenho das aves e a qualidade dos ovos, o Mn orgânico melhorou a qualidade da casca e reduziu o peso dos ovos e o Se não apresentou efeitos sobre as características avaliadas.Three experiments were carried out to evaluate the effect of minerals in organic form in diet supplementation in Japanese quails performance. The levels of minerals used per kg of diet for each experiment were: Experiment 1: control, 0.35; 0.70 and 1.05mg organic; Experiment 2: control, 50; 100 and 150mg organic Zn; and Experiment 3: control, 60; 120 and 180mg organic Mn. The birds were randomly allotted in treatments with eight birds per experimental unit and six replicates per treatment. Performance traits of the quails estimated by daily feed intake, egg weight, egg production, feed conversion by egg mass and per dozen eggs and viability, and egg quality measured by Haugh unit, yolk index, shell, albumen and yolk percentage, shell thickness and specific gravity were evaluated. The organic Zn diet supplementation improved bird performance and egg quality, the organic Mn diet improved eggshell quality and reduced egg weight, and the Se diet did not affect the evaluated characteristics