Polyps are a common finding during recommended screening exams of the colon and rectum, occurring in approximately 20 to 30% of American adults. Polyps are abnormal growths arising from the inner lining of the colon or rectum. Some polyps are flat; others have a stalk. Polyps can occur throughout the large intestine, but are more commonly found in the left colon, sigmoid colon and rectum. The large majority of polyps will not become cancers; however, certain types of polyps are precursors to cancer development.
DEFINITION of 'Nonrenewable Resource'. A resource of economic value that cannot be readily replaced by natural means on a level equal to its consumption. Most fossil fuels, such as oil, natural gas and coal are considered nonrenewable resources in that their use is not sustainable because their formation takes billions of years.
Non-Renewable Energy. Non-renewable fossil fuels (crude oil, natural gas, coal, oil shales and tar sands) currently supply Australia with more than 95 percent of our electrical energy needs. Non-renewable energy is energy produced by burning fossil fuels such as coal. They are non-renewable because there are finite resources of fossil fuels on the planet. If they are continually used, one day they will run out. The Source of Fossil Fuels. Just as plants do today, those living millions of years ago converted the sun's light energy into food (chemical) energy through the process of photosynthesis.