The horse, the cowboy and the lightning modeling: A case study on a farm in the State of Minas Gerais, Brazil
Lightning provoke fear, fright and many material and personal losses in the urban environment, corroborated by the agglomeration of people and concentration of high buildings. No less terrified, however, are the inhabitants of the countryside, including the animals, in the occurrences of atmospheric discharges. This article deals with the action of lightning that victimized a horse and a cowboy, on a farm, by simulating the propagation of potentials in the soil.
Assessing the dangers of lightning to livestock, a case study of a lightning event resulting in the deaths of 22 cattle
The majority of lightning fatalities occur in outdoor environments. The application of the IEC62305-2 lightning risk standard provides little insight into the risks to living beings in open spaces. The Median Lethal Limit (MLL) provides a means of describing the dangers to living beings in open spaces. A site in Mpumalanga, South Africa was investigated after a lightning incident resulted in the deaths of 22 cattle. The IEC62305-2 methodologies are used to assess the enclosure that housed the cattle. The same area is then assessed using the MLL and the results are compared. It is found that the MLL method in conjunction with the application of the rolling sphere provides a reasonable approximation for the danger of lightning to living beings in the enclosure. It is advised that some form of protection measures be installed to protect the cattle in the enclosure during a thunderstorm.
Thermal stability of reconstituted collagen fibrils. Shrinkage characteristics upon in vitro maturation
Thermal stability measured as area shrinkage without tension during heating was determined for membranes of collagen fibrils reconstituted from solutions of highly purified rat skin collagens. Shrinkage in per cent of area at 25 degrees C and shrinkage temperature were quantitated in a standardized way and determined as a function of in vitro maturation time for 11 to 104 days after aggregation for the collagen membranes. Similar to reports on intact rat skin, shrinkage temperature remained constant and shrinkage per cent declined with a rate decreasing with time during maturation. Solubility in water at 80 degrees C for 2 hours was 95-96% and remained unchanged for the maturation time (about 2 months) studied. The decreased shrinkage reflecting a lower degree of collapse is ascribed to an increasing thermal stability of the membranes during maturation. Development of heat-stable bonds in the reconstituted collagen fibrils is taken up to be amenable to this increased stability. Similarity in changes of shrinkage characteristics during in vivo and in vitro maturation indicates that maturation changes in reconstituted collagen fibrils reflect those occurring in intact collagen during in vivo aging.