Opiates are ligands that bind opium-binding receptors and exist endogenously and synthetically. Neural ensembles can generate oscillatory activity endogenously through local interactions between excitatory and inhibitory neurons. The endogenously designated -molecule for a particular receptor is referred to as its endogenous ligand. Bases may be modified endogenously by normal cellular molecules. Chrysophyceae is the presence of a siliceous cyst that is formed endogenously. Studies have shown that in-group favoritism arises endogenously, through the formation of cultural groups. Thus, human bodies contain some quantity of alcohol endogenously produced by these bacteria. The karmic theory in Jainism operates endogenously. However, under modern-day monetary systems, the supply of money is largely determined endogenously. It has not been found to occur endogenously. The dextrorotary form, -xylose, is the one that usually occurs endogenously in living things. Endogenously produced intestinal gases make up 74 percent of flatus in normal subjects.