Caracterização hidráulica do tubo gotejador Hidrodrip II Hydraulic characterization of the integral dripline Hidrodrip II

O objetivo, com este trabalho realizado em laboratório, foi estudar as características hidráulicas do tubo gotejador Hidrodrip II, 2,3 L h-1, cujos emissores, inseridos nos tubos durante o processo de fabricação e espaçados a 0,3 m, apresentam formato tipo labirinto. Submeteram-se os tubos a diferentes pressões, para determinação das características hidráulicas: relação vazão-pressão dos emissores e coeficiente de variação de fabricação; também, avaliou-se o efeito da temperatura na vazão dos gotejadores. Os emissores apresentaram regime de fluxo turbulento (x = 0,51) e valor médio de 1,49% para o coeficiente de variação de fabricação, enquanto a variação de temperatura, de 30 a 60 ºC, reduziu a vazão dos gotejadores, em aproximadamente 1,75%.<br>This study was carried out in laboratory with the objective of analizing the hydraulic characterization of the integral drip tape Hidrodrip II, 2.3 L h-1, whose emitters are spaced at 0.3 m and inserted in the tubes during the manufacture process. The tubes were submitted to several pressures to determine the hydraulic characteristics: discharge-pressure relation of emitters and the manufacturing variation coefficient. The temperature effect in the emitter discharge was also evaluated. The discharge exponent calculated indicates that the emitter has a turbulent flow and the mean manufacturing variation coefficient of 1.49%. The emitter discharge decreased only 1.75% as the temperature increased from 30 to 60 ºC

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was &amp;lt;1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified. © 2023, The Author(s)