Every physical body spontaneously and continuously emits electromagnetic radiation. Heartwood formation is a genetically programmed process that occurs spontaneously. Neurons become unusually sensitive and develop spontaneously pathological activity and abnormal excitability. It assists patients who can spontaneously breathe. They can explode on heating, force, drying, illumination, or sometimes spontaneously. There are elementary particles that spontaneously decay into less massive particles. This is called depolarisation and occurs spontaneously. When used inappropriately, some knots tend to capsize easily or even spontaneously. First, they are responsible for being able to spontaneously generate and send out electrical impulses. This is a group of pacemaker cells which spontaneously depolarize to create an action potential. Specifically Alopecia areata is an autoimmune disease that causes hair to spontaneously fall out. Networks can also fail and recover spontaneously. Depending on the etiology the gallop rhythm may resolve spontaneously. Thus, the vacuum is degenerate and noninvariant under the action of the spontaneously broken symmetry. Cultural assimilation can happen either spontaneously or forcibly ("see forced assimilation").