separation anxiety disorder, condition characterized by intense and prolonged concern, dread, worry, or apprehension about being separated from a loved one. Separation anxiety disorder is associated with significant distress, to the degree that it interferes with the affected individual’s ability to function, and can negatively impact mental health, academic and professional performance, and relationships with family and peers. 　　Separation anxiety...

　　sport climbing, a type of rock climbing in which climbers ascend a route that is equipped with preplaced permanent bolts, rather than placing temporary bolts as they climb and removing them on their descent, as is done in traditional rock climbing. It is a form of free climbing, meaning that upward progress is determined solely by the strength and movement...

　　Occurring every four years—provided there is no global war or pandemic—the Summer Olympic Games bring together athletes from across the world to compete for the love of country and sport. While the slate of events has changed over the years, with sports regularly being added and removed, perennially popular sports persist—including gymnastics, swimming, diving, volleyball, and track and field. The...

　　reactive attachment disorder, rare condition in which infants and young children fail to form emotional bonds with their parents or other caregivers. The disorder is associated with trauma or other stressors that typically result from neglect or physical or emotional abuse and that affect early development. An estimated 1 to 2 percent of children are affected by reactive attachment disorder....

　　 　　Proxima Centauri bArtist's impression of the surface of Proxima Centauri b, one of the closest extrasolar planets to the Sun. The planet has a mass at least 1.3 times that of Earth.(more)Proxima Centauri is the closest star to the Sun, about 4.2 light-years away in the Alpha Centauri system. As a red dwarf star—the most common type of star—Proxima...

　　rhombus, a four-sided, or quadrilateral, geometric figure in which all four sides are of the same length and each of the two pairs of opposite sides are parallel to each other. The word rhombus comes from the Greek rhombos, meaning “a spinning top” or “a piece of wood whirled on a string.” Rhombuses can be seen in everyday life, in...

　　 　　cell See all media Category: Science & Tech Related Topics: cell fluid cytoplasm cytosol (Show more) See all related content → intracellular fluid, substance within living cells that is made up primarily of water and molecules such as dissolved ions and is a major component of the cytoplasm and cytosol. A variety of chemical reactions within cells take place...

　　A geothermal heat pump (GHP) is a heating and cooling system that takes advantage of the relatively stable moderate temperature conditions within the first 300 meters (1,000 feet) below the surface of the Earth to heat a building in the winter and cool it in the summer. Unlike boilers or furnaces, GHPs do not rely on the combustion of fossil...

　　polydactyly, condition that is present at birth in which a person has more than five fingers on a hand or more than five toes on a foot. The term polydactyly is derived from the Greek words poly, meaning “many,” and daktylos, meaning “digit.” Polydactyly occurs in an estimated 1 in 500–1,000 births, with variation from 1 in roughly 1,330 births...

　　 　　Pope Francis in a PopemobilePope Francis waving to a crowd while riding in a Popemobile during World Youth Day in Portugal, 2023.(more)Popemobile, motorized vehicle used to transport the pope, the leader of the Roman Catholic Church, when he greets the public. The term has been used to describe any number of specially designed vehicles by automobile brands such as...

　　tart cherry, (Prunus cerasus), species of cherry cultivated for its acidic fruits. Tart cherries are one of three types of cherries grown commercially, the others being sweet cherries and a cross of sweet and tart cherries known as dukes. Generally considered too acidic to eat fresh, tart cherries are commonly frozen or canned for use in sauces and pastries and...

　　plantar fasciitis, swelling or degeneration of the plantar fascia, the thick band of connective tissue that runs across the bottom of the foot and connects the heel bone to the toes. Plantar fasciitis causes dull or stabbing pain, typically after a long period of rest, such as sleeping or sitting. The term fasciitis means “inflammation of the fascia”; however, because...