The factors used to determine tumor grade can vary between different types of cancer. Tumor grade is not the same as the stage of a cancer. Cancer stage refers to the size and/or extent (reach) of the original (primary) tumor and whether or not cancer cells have spread in the body. Cancer stage is based on factors such as the location of the primary tumor, tumor size, regional lymph node involvement (the spread of cancer to nearby lymph nodes), and the number of tumors present.
According to an international team of scientists reporting in the Proceedings of the National Academy of Sciences, an asteroid or comet that landed in what is now the Canadian province of Quebec might have led to a significant climate change event known as Younger Dryas.
Deserts can form for many reasons. The Mojave and Great Basin deserts in North America are dry because they are in the rain shadow of the California coastal mountain range. Moist air is blown from the oceans up the side of the mountains where it rains and snows.By the time the air has crossed the mountains there is very little moisture left.esert types. Deserts are dry places where little rain or snow falls. Some deserts get less than 25 mm (1 inch) of precipitation each year. Other deserts may get up to 250 mm (10 inches) of precipitation. Cold deserts form at higher latitudes.