Population density shows how cramped or spread out inhabitants are. Cities with high population densities can be considered overpopulated, but the extent to which this is the case depends on factors like quality of housing and infrastructure and access to resources. Source: Wikipedia, 2017.
Livor mortis on the posterior aspects of the body is caused by settling of the blood because of gravity when the body is in a supine position. As the postmortem interval lengthens, Tardieu spots develop in areas of lividity, such as this individual's shoulder area, as decomposing capillaries rupture.
When the heart stops functioning and is no longer agitating the blood, heavy red blood cells sink through the serum by action of gravity. Livor mortis starts in twenty minutes to thirty minutes. Then color becomes purplish red in next 1-3 hours.