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Large grazing herbivores can change fire regimes by altering fuel types and abundance, particularly in savanna biomes where the dominant fuel is grass. The use of herbivores as a fire management tool is receiving increasing consideration globally, but this intervention has a limited evidence‐base and is controversial because of potential deleterious ecological effects. These issues are well illustrated by the political and scientific debate about the capacity of cattle grazing to reduce fire hazard in the Victorian Alps of Australia; there have been remarkably few scientific studies to illuminate this issue. Here we use remote sensing and geographic information system analysis to determine the effect of active grazing licences on fire severity (crown scorch) in eucalypt forests and woodlands following large fires in the Alps during the summers of 2002/2003 and 2006/2007. Our statistical analyses, which controlled for spatial autocorrelation, found crown scorch was strongly related to vegetation type but there was no evidence that cattle grazing reduced fire severity. There was some evidence that grazing could increase fire severity by possibly changing fuel arrays. Such landscape analyses are a critical approach given that large‐scale grazing × fire trials are prohibitively expensive and impractical to conduct. 相似文献
949.
Xiaoqian Cheng Jonathan Sherman William Murphy Edward Ratovitski Jerome Canady Michael Keidar 《PloS one》2014,9(5)
Previous research in cold atmospheric plasma (CAP) and cancer cell interaction has repeatedly proven that the cold plasma induced cell death. It is postulated that the reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a major role in the CAP cancer therapy. In this paper, we seek to determine a mechanism of CAP therapy on glioblastoma cells (U87) through an understanding of the composition of the plasma, including treatment time, voltage, flow-rate and plasma-gas composition. In order to determine the threshold of plasma treatment on U87, normal human astrocytes (E6/E7) were used as the comparison cell line. Our data showed that the 30 sec plasma treatment caused 3-fold cell death in the U87 cells compared to the E6/E7 cells. All the other compositions of cold plasma were performed based on this result: plasma treatment time was maintained at 30 s per well while other plasma characteristics such as voltage, flow rate of source gas, and composition of source gas were changed one at a time to vary the intensity of the reactive species composition in the plasma jet, which may finally have various effect on cells reflected by cell viability. We defined a term “plasma dosage” to summarize the relationship of all the characteristics and cell viability. 相似文献
950.
Sean V. Murphy Rebecca Lim Philip Heraud Marian Cholewa Mark Le Gros Martin D. de Jonge Daryl L. Howard David Paterson Courtney McDonald Anthony Atala Graham Jenkin Euan M. Wallace 《PloS one》2012,7(9)
Cystic fibrosis, an autosomal recessive disorder caused by a mutation in a gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), remains a leading cause of childhood respiratory morbidity and mortality. The respiratory consequences of cystic fibrosis include the generation of thick, tenacious mucus that impairs lung clearance, predisposing the individual to repeated and persistent infections, progressive lung damage and shortened lifespan. Currently there is no cure for cystic fibrosis. With this in mind, we investigated the ability of human amnion epithelial cells (hAECs) to express functional CFTR. We found that hAECs formed 3-dimensional structures and expressed the CFTR gene and protein after culture in Small Airway Growth Medium (SAGM). We also observed a polarized CFTR distribution on the membrane of hAECs cultured in SAGM, similar to that observed in polarized airway cells in vivo. Further, hAECs induced to express CFTR possessed functional iodide/chloride (I−/Cl−) ion channels that were inhibited by the CFTR-inhibitor CFTR-172, indicating the presence of functional CFTR ion channels. These data suggest that hAECs may be a promising source for the development of a cellular therapy for cystic fibrosis. 相似文献