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.
Gallstones are pieces of solid material that form in the gallbladder. These stones develop because cholesterol and pigments in bile sometimes form hard particles. The two main types of gallstones are: 1  Cholesterol stones: Usually yellow-green in color, approximately 80% of gallstones are cholesterol stones.2  Pigment stones: These stones are smaller and darker and are made up of bilirubin. Gallstones are more common among women and older people. 2  Cholesterol drugs. 3  Some cholesterol-lowering drugs increase the amount of cholesterol in bile, which may increase the chances of developing cholesterol stones. 4  Diabetes.