In psychology, a state of bodily or mental tension resulting from factors that tend to alter an existent equilibrium. Stress is an unavoidable effect of living and is an especially complex phenomenon in modern technological society. It has been linked to coronary heart disease, psychosomatic disorders, and various other mental and physical problems. Treatment usually consists of a combination of counseling or psychotherapy and medication.
Learn more about stress with a free trial on Britannica.com.
Psychological reaction occurring after a highly stressful event and typically characterized by flashbacks, recurrent nightmares, and avoidance of reminders of the event; depression and anxiety are often present. Traumatic events that can lead to PTSD include automobile accidents, rape or assault, military combat, torture, and such natural disasters as floods, fires, or earthquakes. Long-term effects can include marital and family problems, difficulties at work, and abuse of alcohol and other drugs. Antidepressant medication and psychotherapy, including group therapy, are used in treating the disorder.
Learn more about post-traumatic stress disorder (PTSD) with a free trial on Britannica.com.
Property of a liquid surface that causes it to act like a stretched elastic membrane (see elasticity). Its strength depends on the forces of attraction among the particles of the liquid itself and with the particles of the gas, solid, or liquid with which it comes in contact. Surface tension allows certain insects to stand on the surface of water and can support a razor blade placed horizontally on the liquid's surface, even though the blade may be denser than the liquid and unable to float. Surface tension results in spherical drops of liquid, as the liquid tends to minimize its surface area.
Learn more about surface tension with a free trial on Britannica.com.
In the arts: