To keep things simple, we only consider the area of each state, twice the area of each state, and the area of the entire USA as units. We only bother with twice statesâ area thing for big countries (larger than 2,500,000 sq km). For compactness, we do not provide the reverse mapping from countries to US states. R code available upon request. Here you are.
Gallstones form from bile, the yellowish fluid that is produced in the liver and stored in the gallbladder until it is released into the small intestine to help in digestion. Bile is a mix of cholesterol, water, pigments, lecithin, and salts (electrolytes), such as calcium, that are kept in equilibrium. Gallstones form when one of the constituents of bile precipitates out and forms a solid mass that may range from the size of a grain of sand to several centimeters large.
Points to Remember. 1  Gallstones are hard particles that develop in the gallbladder. 2  Imbalances in the substances that make up bile cause gallstones. 3  Women, people over age 40, people with a family history of gallstones, American Indians, and Mexican Americans have a higher risk of developing gallstones.