Orbital Observations of Dust Lofted by Daytime Convective Turbulence

Over the past several decades, orbital observations of lofted dust have revealed the importance of mineral aerosols as a climate forcing mechanism on both Earth and Mars. Increasingly detailed and diverse data sets have provided an ever-improving understanding of dust sources, transport pathways, and sinks on both planets, but the role of dust in modulating atmospheric processes is complex and not always well understood. We present a review of orbital observations of entrained dust on Earth and Mars, particularly that produced by the dust-laden structures produced by daytime convective turbulence called “dust devils”. On Earth, dust devils are thought to contribute only a small fraction of the atmospheric dust budget; accordingly, there are not yet any published accounts of their occurrence from orbit. In contrast, dust devils on Mars are thought to account for several tens of percent of the planet’s atmospheric dust budget; the literature regarding martian dust devils is quite rich. Because terrestrial dust devils may temporarily contribute significantly to local dust loading and lowered air quality, we suggest that martian dust devil studies may inform future studies of convectively-lofted dust on Earth

Influência do grão de sorgo como fonte de amido em ovinos alimentados com feno: parâmetros plasmáticos Influence of sorghum grain as a source of starch in sheep fed hay: plasma parameters

O objetivo deste trabalho experimental foi verificar a influência de diferentes níveis de grão de sorgo, como fonte de amido, nos parâmetros plasmáticos em ovinos alimentados com feno de capim-elefante (Pennisetum purpureum Schum). O sorgo foi utilizado em quatro níveis na dieta: 0, 15, 30 e 45%. Foram usados 12 ovinos machos castrados distribuídos em quatro tratamentos com três repetições. Foram coletadas seis amostras de sangue por animal logo antes da refeição da manhã (hora zero) e 1, 2, 3, 4, 6 e 8 horas após. O delineamento experimental foi o completamente casualizado. A 1ª hora após a refeição apresentou a maior concentração plasmática de uréia (53,3 mg/100 mL) e foi superior à 6ª e 8ª hora (49,5 e 49,3 mg/100 mL). A maior concentração de uréia no plasma coincidiu com a maior concentração de amônia no líquido ruminal. O tratamento com 30% de sorgo na dieta apresentou concentração plasmática de glicose de 81,0 mg/100 mL e foi superior ao tratamento testemunha (60,4 mg/100 mL). A concentração de insulina variou entre tratamentos para cada hora de coleta após a refeição, de acordo com os níveis de sorgo na dieta. O tratamento com 45% de sorgo apresentou a maior concentração do hormônio no plasma. Observou-se para todos os tratamentos um pico de produção do hormônio na 4ª hora após a refeição.<br>The objective of this experimental work was to evaluate the influence of different levels of sorghum grain, as a source of starch, on the plasma parameters of sheep fed elephant grass hay (Pennisetum purpureum Schum). Sorghum grain was included in the diet at four levels: 0, 15, 30 e 45%. Twelve castrated male sheep were assigned to four treatments with three replicates. Six samples of blood per animal were collected just before the morning feeding (zero hour) and after 1, 2, 3, 4, 6 and 8 hours. A completely randomized design was used. The first hour after feeding showed the highest plasma concentration of urea (53.3 mg/100 mL) and was higher than the six and eight-hour samples (49.5 and 49.3 mg/100 mL). The higher concentration of urea in the plasma coincided with the highest concentration of ammonia in the ruminal liquor. Treatment including 30% sorghum in the diet showed a glucose plasmatic concentration of 81,0 mg/100 mL and was superior to the control treatment (60.4 mg/100 mL). Insulin concentration varied among treatments for each hour of collection after feeding according to the levels of sorghum in the diet. The treatment that included 45% sorghum grain showed the highest concentration of this hormone in the plasma. It was observed a peak of the insulin production at the four-hour after feeding