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.
How Deserts are Formed. Deserts are formed when rain clouds run into wind or mountains and drop rain in one area, leaving the land further away dry. Deserts that form near bodies of water are usually caused by winds. For example, the Sahara desert, near the Mediterranean. Deserts near mountains are formed when rain clouds drop their rain on one side, and the land on the other side of the mountains stays dry.