The negative stain is particularly useful for determining cell size and arrangement. It can also be used to stain cells that are too delicate to be heat-fixed. We use nigrosin as our negative stain. Nigrosin is an acidic stain.
To 2040 A.D. Until late 2006, global temperatures were more than a degree Fahrenheit warmer when compared to the 20th Century average. From August of 2007 through February of 2008, the Earthâs mean temperature dropped to near the 20th Century average of 57 degrees.
But the [climate] models are getting a lot stronger, said Jay Gulledge, a senior research at the Pew Center on Global Climate Change in Arlington, Virginia. Gulledge says some current projections point to a rise in average global temperature of 0.5Â°C (slightly less than 1Â°F) by the year 2030. The estimates are based on greenhouse gasses already in the atmosphere. While the temperature increase is small, it would be significant. Over the past century Earth has warmed about 1Â°F (0.6Â°C). (See our fast facts on global warming.) Gulledge cautions, however, that warming rates depend on many factors, some of which have yet to be discovered.