pellagra, nutritional disorder caused by a dietary deficiency of niacin (also called nicotinic acid) or a failure of the body to absorb this vitamin or the amino acid tryptophan, which is converted to niacin in the body. Pellagra is characterized by skin lesions and by gastrointestinal and

goitre: …common type of goitre is endemic goitre, caused by iodine deficiency. Iodine is an essential nutrient that is required for the production of thyroid hormone. When iodine intake is low, thyroid hormone production is low, and in response the pituitary gland secretes greater quantities of the hormone thyrotropin (thyroid-stimulating hormone,…

endemic species, in ecology, any species or other taxon whose geographic range or distribution is confined to a single given area. Although the species may inhabit a very small area, such as a single lake, or its range may extend across an entire continent, it is considered endemic if it is not

bejel, chronic infection characterized by eruptions initially in the mouth and on the skin and typically later involving the bones. Bejel is a nonvenereal form of syphilis. It is caused by the bacterium Treponema pallidum endemicum, which is closely related to T. pallidum pallidum, the cause of

biogeographic region: Endemism: A taxon whose distribution is confined to a given area is said to be endemic to that area. The taxon may be of any rank, although it is usually at a family level or below, and its range of distribution may be wide, spanning…

Benedict de Spinoza: Association with Collegiants and Quakers: …likely that he stayed with Franciscus van den Enden, a political radical and former Jesuit, and taught classes at the school that van den Enden had established in Amsterdam.

Viola Davis: …drama about missing children; and Ender’s Game (2013), a science-fiction adventure movie.

Kornelia Ender is an East German swimmer who was the first woman to win four gold medals at a single Olympics. Ender’s natural ability was spotted when she was a child playing on family vacations, and she was trained from a young age by demanding East German coaches who included weight lifting in

Otto Ender was a statesman and government official who served as chancellor of Austria during the early months of the Great Depression. Ender served (1918–30, 1931–34) as governor of the Austrian state of Vorarlberg, on the Swiss border, and after World War I he negotiated unsuccessfully for the

Enderbury Atoll, one of the Phoenix Islands, part of Kiribati, in the west-central Pacific Ocean, about 1,650 miles (2,660 km) southwest of Hawaii. Its lagoon is shallow and brackish. The coral island has an area of 2.5 square miles (6.5 square km). The atoll was discovered (1823) by J.J. Coffin of

Enderbury Atoll, one of the Phoenix Islands, part of Kiribati, in the west-central Pacific Ocean, about 1,650 miles (2,660 km) southwest of Hawaii. Its lagoon is shallow and brackish. The coral island has an area of 2.5 square miles (6.5 square km). The atoll was discovered (1823) by J.J. Coffin of

Enderby Land, region of Antarctica, bordering on the Indian Ocean and extending from Prince Olav Coast of Queen Maud Land (west) to Edward VIII Bay and Kemp Coast (east). Primarily a barren, ice-capped plateau in the interior sections, it rises to rugged peaks along the coast, where the Napier

Anthony Burgess: …of Saint Venus (1964) and Enderby Outside (1968). The latter is part of a series of humorous novels centred around the lyric poet F.X. Enderby, whom many critics have seen as a stand-in for Burgess himself. His later works include Earthly Powers (1980), The End of the World News (1983),…

metalwork: 16th century to modern: …Briot was copied by Caspar Enderlein, who modelled his own Temperantia Dish directly on Briot’s. The decoration on the ewer that went with it was modelled on Briot’s Mars Dish and on a piece known as the Suzannah Dish, which is also attributed to Briot.

John Franklin Enders was an American virologist and microbiologist who, with Frederick C. Robbins and Thomas H. Weller, was awarded the Nobel Prize for Physiology or Medicine for 1954 for his part in cultivating the poliomyelitis virus in nonnervous-tissue cultures, a preliminary step to the

Turkish literature: Movements and poets: Fazıl Enderunî went even further in his development of the şehrengiz (city-description) genres, of which Hubanname (“The Book of Beauties”), Zenanname (“The Book of Women”), and Çengîname (“The Book of Dancing Boys”) were part. All of these are replete with dialogue and descriptions that are…

Endesa, Spanish energy company that is one of the largest private conglomerates in the world. Headquarters are in Madrid. Endesa’s activities are aimed at generating, transporting, distributing, and selling electrical energy and related services. The company was founded by the Spanish government in

chess: Computer extension of chess theory: …series of discoveries in basic endgames. By working backward from positions of checkmate, Thompson was able to build up an enormous number of variations showing every possible way of reaching the final ones. This has been possible with only the most elementary endgames, with no more than five pieces on…

Endgame, play in one act by Samuel Beckett, written in French as Fin de partie and produced and published in 1957. It was translated into English by the author. Endgame has four characters: Hamm, the master, who is blind, wheelchair-bound, and demanding; Clov, his resentful servant, physically

Angola: Resources and power: The National Diamond Enterprise of Angola, a parastatal company, is responsible for approving diamond concessions, and it also licenses buyers. In 1992–94 most Angolan diamonds on the market were mined and smuggled from regions controlled by UNITA. The Angolan government gained control of this area in…

John Endecott was a colonial governor of the Massachusetts Bay Colony and cofounder of Salem, Mass., under whose leadership the new colony made rapid progress. Little is known of Endecott before 1628, when, as one of the six grantees of the New England Company for a Plantation in Massachusetts, he

John Lyly: …finest is considered to be Endimion, which some critics hold a masterpiece.

African music: Fiddles: … of Ethiopia and Eritrea and endingidi of Uganda—the last being a 20th-century invention.

endive, (Cichorium endivia), edible annual leafy plant of the family Asteraceae, variously believed to have originated in Egypt and Indonesia and cultivated in Europe since the 16th century. Its many varieties form two groups, the curly-leaved, or narrow-leaved, endive (crispa), and the Batavian,

number symbolism: 11: Sandwiched between the two auspicious and important numbers 10 and 12, the number 11 generally has negative connotations. Bungus stated that 11 has no connection with the divine, and medieval theology refers to the “11 heads of error.” Because at any time one of…

Constantin Brancusi: Maturity of Constantin Brancusi: …the first version of the Endless Column. Created through the repetition of superimposed symmetrical elements, this column, inspired by the pillars of Romanian peasant houses, embodied the need for spiritual elevation that Brancusi often expressed in his works.

Frederick John Kiesler: Kiesler’s “Endless House” was never built full-scale, but a large concrete model was displayed at the Museum of Modern Art, New York City, in 1960. More sculpture than architecture, the house consisted of a group of joined, rounded, shell structures on piers that could be used…

Lawrence Ferlinghetti: …his poems were published as Endless Life (1981) and These Are My Rivers (1995). In 1988 Ferlinghetti published a short novel, Love in the Days of Rage, about a romance during the student revolution in France in 1968.

Lionel Richie: …with whom he recorded “Endless Love” in 1981. Such musical excursions accelerated Richie’s rapid rise in popularity and ultimately precipitated his split from the Commodores. Release of the album Lionel Richie in 1982 marked the start of Richie’s solo career.

James Spader: …in Franco Zeffirelli’s teen drama Endless Love, in which he played the brother of Brooke Shields’s character. In 1983 he appeared as Fenwick in the television pilot for Diner—an adaptation of the previous year’s coming-of-age film of the same name—but the series never sold.

Alejandro Jodorowsky: Later films, comic books, and psychomagic: …movie, Poesía sin fin (2016; Endless Poetry), was also autobiographical, chronicling Jodorowsky as a young man.

Pink Floyd: Split and later albums: …the final Pink Floyd album, The Endless River (2014). Pink Floyd was inducted into the Rock and Roll Hall of Fame in 1996.

the Who: …that made up part of Endless Wire (2006), which was the first album of new Who material since 1982. On it Townshend and Daltrey were supported by drummer Zak Starkey (son of Ringo Starr) and Townshend’s brother Simon on guitar, among others. A full-blown musical based on this material and…

Stephan Endlicher was an Austrian botanist who formulated a major system of plant classification. Endlicher turned from the study of theology to that of natural history and medicine while at the Universities of Budapest and Vienna (M.D., 1840). In 1836 he became curator of the Vienna Museum of

Stephan Endlicher was an Austrian botanist who formulated a major system of plant classification. Endlicher turned from the study of theology to that of natural history and medicine while at the Universities of Budapest and Vienna (M.D., 1840). In 1836 he became curator of the Vienna Museum of

Edith Stein: …she completed her metaphysical work Endliches und ewiges Sein (“Finite and Eternal Being”), an attempt to synthesize the diverse philosophies of Aquinas and Husserl. Other philosophical and spiritual works followed. In 1938, with the Nazi threat growing, she was transferred to the Carmelite convent at Echt in the Netherlands, where…

vanadinite: Endlichite is a highly arsenious variety; the complete substitution of arsenic for vanadium in the crystal structure forms the mineral mimetite. For detailed physical properties, see vanadate mineral (table).

final solution, Nazi plan to eliminate Europe’s Jewish population. The “final solution” was implemented from 1941 to 1945 and resulted in the systematic murder of 6 million Jews across 21 countries. The “final solution” was the culmination of a state-sponsored campaign against Jewish citizens in

final solution, Nazi plan to eliminate Europe’s Jewish population. The “final solution” was implemented from 1941 to 1945 and resulted in the systematic murder of 6 million Jews across 21 countries. The “final solution” was the culmination of a state-sponsored campaign against Jewish citizens in

Endō Shūsaku was a Japanese novelist noted for his examination of the relationship between East and West through a Christian perspective. Endō became a Roman Catholic at age 11 with the encouragement of his mother and an aunt. At Keio University he majored in French literature (B.A., 1949), a

bivalve: Size range and diversity of structure: Such a shell form and habit evolved first within sediments (endobyssate), where the byssus serves for anchorage and protection when formed into an enclosing nest. Other bivalves have used the byssus to attach securely within crevices and thus to assume a laterally flattened, circular shape. The best…

cannibalism: …his relatives, a form called endocannibalism. Some Aboriginal Australians performed such practices as acts of respect. In other cases, ritual cannibalism occurred as a part of the drama of secret societies.

endocarditis, inflammation of the heart lining, or endocardium. Endocarditis is caused by any of a number of microorganisms, including bacteria, fungi, rickettsias, and possibly viruses, that enter the bloodstream and become trapped in the heart. The disease is characterized by the presence of

animal development: Circulatory organs: …tube, which will become the endocardium, or lining of the heart. In vertebrates with complete cleavage, the endocardial tube is single and medial from its start. In higher vertebrates with meroblastic cleavage—reptiles, birds, and mammals—the embryo in early stages of development is flattened out on the surface of the yolk…

angiosperm: Fruits: …regions: the inner layer, or endocarp; the middle layer, or mesocarp; and the outer layer, or exocarp. These regions may be fleshy or dry (sclerified) or any combination of the two, but they are classified as either one or the other.

linguistics: Syntax: …described as endocentric; the only endocentric construction in the model sentence above is “poor John.” All the other constructions, according to the analysis, are exocentric. This is clear from the fact that in Figure 2 the letters at the nodes above every phrase other than the phrase A + B…

cervix: …of the cervix is the endocervical canal; the opening of the endocervical canal into the uterine cavity, the internal os. The endocervical canal transports sperm into the uterine cavity, allows the escape of blood from the uterus during menstruation, and supplies mucus (a thick lubricating protein) to the female reproductive…

bone formation: …by bone is known as endochondral ossification. Most short bones have a single ossification centre near the middle of the bone; long bones of the arms and legs typically have three, one at the centre of the bone and one at each end. Ossification of long bones proceeds until only…

human ear: Transduction of mechanical vibrations: …of this process is the endocochlear potential, which exists between the endolymph and perilymph. This direct current potential difference is about +80 millivolts and results from the difference in potassium content between the two fluids. It is thought to be maintained by the continual transport of potassium ions from the…

endocranial cast, a cast taken from the inside of the cranium (braincase), frequently used by paleoanthropologists to determine the shape and approximate size of the brains of fossil animals including extinct hominids and other primates. Since only skeletal materials are preserved in the fossil

endocrine disruptor, any chemical that mimics or interferes with the normal actions of hormones in the body. Endocrine disruptors may be synthetic or natural (e.g., phytoestrogens) in origin and are used in a wide range of products and materials, from cosmetics and plastics to pesticides and

human digestive system: Production and secretion of peptides: Eighteen different endocrine cells can be identified within the gastrointestinal tract, but it is probable that several of these and their particular peptides are evolutionary vestiges that functioned in other stages of human development, while others may represent different stages of maturation of the same endocrine cell.

endocrine disruptor, any chemical that mimics or interferes with the normal actions of hormones in the body. Endocrine disruptors may be synthetic or natural (e.g., phytoestrogens) in origin and are used in a wide range of products and materials, from cosmetics and plastics to pesticides and

endocrine disruptor, any chemical that mimics or interferes with the normal actions of hormones in the body. Endocrine disruptors may be synthetic or natural (e.g., phytoestrogens) in origin and are used in a wide range of products and materials, from cosmetics and plastics to pesticides and

endocrine system, any of the systems found in animals for the production of hormones, substances that regulate the functioning of the organism. Such a system may range, at its simplest, from the neurosecretory, involving one or more centres in the nervous system, to the complex array of glands

human endocrine system, group of ductless glands that regulate body processes by secreting chemical substances called hormones. Hormones act on nearby tissues or are carried in the bloodstream to act on specific target organs and distant tissues. Diseases of the endocrine system can result from the

endocrine disruptor, any chemical that mimics or interferes with the normal actions of hormones in the body. Endocrine disruptors may be synthetic or natural (e.g., phytoestrogens) in origin and are used in a wide range of products and materials, from cosmetics and plastics to pesticides and

endocrinology, medical discipline dealing with the role of hormones and other biochemical mediators in regulating bodily functions and with the treatment of imbalances of these hormones. Although some endocrine diseases, such as diabetes mellitus, have been known since antiquity, endocrinology

arthropod: The exoskeleton and molting: …outer exocuticle and an inner endocuticle. In the exocuticle there is cross-bonding of the chitin–protein chains (tanning), which provides additional strength to the skeletal material. The hardness of various parts of the exoskeleton in different arthropods is related to the thickness and degree of tanning of the exocuticle. In crustaceans,…

horizontal gene transfer: … bacteria to the protozoan parasite Trichomonas vaginalis is suspected to have facilitated the latter organism’s adaptation to its animal hosts. Likewise, the exchange of a gene from a human cell to the bacterium Neisseria gonorrhoeae—a transfer that appears to have occurred relatively recently in the bacterium’s evolution—may have enabled the…

endoderm: …used to refer to the gastrodermis, the simple tissue that lines the digestive cavity of cnidarians and ctenophores. Compare ectoderm; mesoderm.

endoderm, the innermost of the three germ layers, or masses of cells (lying within ectoderm and mesoderm), which appears early in the development of an animal embryo. The endoderm subsequently gives rise to the epithelium (tissue that covers, or lines, a structure) of the pharynx, including the

cortex: …a cell layer called the endodermis. The cell walls of the endodermis possess a woody and corky band, called the casparian strip, around all the cell walls except those facing toward the axis and the surface of the root or stem. The endodermis with its casparian strips may function in…

endodontics, in dentistry, diagnosis, treatment, and prevention of diseases of the dental pulp and the surrounding tissues. (The dental pulp is soft tissue in the centre of the tooth; it contains the nerve, blood and lymphatic vessels, and connective tissue.) The practice of endodontics is

gastropod: Classification: …mainly in Southern Hemisphere (Endodontidae); slugs (Arionidae and Philomycidae) in the Northern Hemisphere. Superfamily Limacacea Marginal teeth of radula with narrow, lengthened basal plates, usually unicuspid; zonitid snails with smooth shells and many sluglike species, common in wet, tropical areas and in temperate regions; about 12 families,

chemical reaction: Energy considerations: The opposite of endothermic is exothermic; in an exothermic reaction, energy as heat is evolved. The more general terms exoergic (energy evolved) and endoergic (energy required) are used when forms of energy other than heat are involved.

endogamy, custom enjoining one to marry within one’s own group. The penalties for transgressing endogamous restrictions have varied greatly among cultures and have ranged from death to mild disapproval. When marriage to an outside group is mandated, it is referred to as exogamy. Endogamy has been

gold processing: Ores: …at the Earth’s surface) and endogenetic (formed within the Earth). The best-known of the exogenetic ores is alluvial gold. Alluvial gold refers to gold found in riverbeds, streambeds, and floodplains. It is invariably elemental gold and usually made up of very fine particles. Alluvial gold deposits are formed through the…

gold processing: Ores: …at the Earth’s surface) and endogenetic (formed within the Earth). The best-known of the exogenetic ores is alluvial gold. Alluvial gold refers to gold found in riverbeds, streambeds, and floodplains. It is invariably elemental gold and usually made up of very fine particles. Alluvial gold deposits are formed through the…

economics: Growth and development: …the 1990s was labeled “endogenous growth theory” because it attempted to explain technical change as the result of profit-motivated research and development (R&D) expenditure by private firms. This was driven by competition along the lines of what Schumpeter called product innovations (as distinct from process innovations). In contrast to…

psychosis: …into two categories: organic and functional. Organic psychoses are characterized by abnormal brain function that is caused by a known physical abnormality, which in most cases is some organic disease of the brain. However, altered brain function that precipitates hallucinations and delusions is more often associated with specific psychiatric disorders,…

retrovirus: So-called endogenous retroviruses (ERVs) are persistent features of the genomes of many animals. ERVs consist of the genetic material of extinct, or “fossil,” viruses, the genomic constitution of which is similar to that of extant retroviruses. Human ERVs (HERVs) have become distributed within human DNA over…

fungus: Annotated classification: Order Endogonales Saprotrophic or mycorrhizal; filamentous; coenocytic mycelium; underground sporocarp; example genera include Endogone, Peridiospora, Sclerogone, and Youngiomyces. Order Mortierellales Parasitic or saprotrophic; fine mycelium, branched (arachnoid); sporangia with 1 or many spores; may form chlamydospores

human ear: Transmission of sound waves in the cochlea: …motion is transmitted to the endolymph inside the cochlear duct. As a result the basilar membrane vibrates, which causes the organ of Corti to move against the tectoral membrane, stimulating generation of nerve impulses to the brain.

sound reception: Sound reception in vertebrates— auditory mechanisms of fishes and amphibians: … and the saccule is the endolymphatic duct, which ends in an endolymphatic sac; this structure probably regulates fluid pressures in the labyrinth and aids in the disposal of waste materials.

Ménière disease, recurrent and generally progressive group of symptoms that include loss of hearing, ringing in the ears, dizziness, and a sense of fullness or pressure in the ears. Ménière disease can affect one or both ears. The disease causes episodic attacks that seldom last longer than 24

endometriosis: …has shown promise involves endometrial biopsy, in which tissue samples are investigated for the presence of abnormal nerve fibres. Clinical trials have indicated that this approach may be useful in the early detection of endometriosis.

uterine cancer, a disease characterized by the abnormal growth of cells in the uterus. Cancers affecting the lining of the uterus (endometrium) are the most common cancers of the female reproductive tract. Other uterine cancers, called uterine sarcomas, develop from underlying muscle or connective

endometriosis, disorder of the female reproductive system characterized by the growth of endometrial tissue (uterine lining) in an abnormal location. Rather than flowing out of the uterus by way of the vagina (during menstruation), some fragments of the endometrium may leave via the fallopian tubes

endometritis, inflammation of the endometrium, the mucous lining of the uterus. Endometritis is most commonly caused by infection with bacteria, particularly Escherichia coli, Mycobacterium tuberculosis, Enterococcus, Staphylococcus, or Streptococcus. It may also be caused by sexually transmitted

human reproductive system: Uterine structure: …is the mucous membrane, or endometrium. It lines the uterine cavity as far as the isthmus of the uterus, where it becomes continuous with the lining of the cervical canal. The endometrium contains numerous uterine glands that open into the uterine cavity and are embedded in the cellular framework or…

fern: Hybridization: …doubling of chromosomes occurs by endomitosis. In these doubled sporangia there are therefore only 8 spore mother cells rather than the usual 16, and they undergo meiosis, producing viable diploid spores. Apogamous ferns are known in a number of genera of higher ferns in various families, including Adiantum, Asplenium, Cheilanthes,…

endomorph, a human somatotype (physical type) tending toward roundness, as determined by the now discredited physique-classification system developed in the 1940s by American psychologist W.H. Sheldon. Sheldon linked endomorphy to certain character traits, including being extroverted, tolerant,

coleopteran: Annotated classification: Family Endomychidae (handsome fungus beetles) Shiny, usually brightly coloured; feed on fungi (mold); about 600 species; mostly in tropical forests; examples Endomychus, Mycetaea. Family Erotylidae (pleasing fungus beetles) Shiny; found with fungi; more than 3,500 species; many in South America.

murrelet: Most southerly is Xantus’s murrelet (Endomychura hypoleucus), which nests on the hot coast of Baja California and (like some gulls of the region) travels north in winter.

conifer: Roots: …species have vesicular-arbuscular mycorrhizae, called endomycorrhizae because the fungal hyphae actually penetrate the cells of the roots. All of the Pinaceae, and only the Pinaceae, have the other kind of root symbiosis, called ectomycorrhizal because the fungi sheath the rootlets and hyphae pass between the outer root cells without penetrating…

meat processing: Skeletal muscle structure: …connective tissue sheath called the endomysium. Each of the connective tissue sheaths found throughout skeletal muscle is composed of collagen, a structural protein that provides strength and support to the muscles.

nucleic acid: Nucleases: Endonucleases cleave in the middle of chains, while exonucleases operate selectively by degrading from the end of the chain. Nucleases that act on both single- and double-stranded DNA are known.

Plasmodiophoromycota, phylum of endoparasitic slime molds in the kingdom Chromista. Some scientists assign Plasmodiophoromycota to the kingdom Protista; the taxonomy of the group, however, remains contentious. Several species are economically significant plant pathogens, including Plasmodiophora

braconid: Braconids are either endoparasitic, living within their hosts, or ectoparasitic, living on their hosts. Endoparasitic females lay an egg or eggs in the larvae or eggs of the host. The braconid larva remains within the host’s body at least until it enters the resting stage (pupa). The pupa…

proteolytic enzyme: …ends of proteins, and the endopeptidases, which target sites within proteins. Endopeptidases employ various catalytic mechanisms; within this group are the aspartic endopeptidases, cysteine endopeptidases, glutamic endopeptidases, metalloendopeptidases, serine endopeptidases, and threonine endopeptidases. The term oligopeptidase is reserved for those enzymes that act specifically on peptides.

locomotion: Pseudopodial locomotion: …enclosing an inner mass, or endoplasm, of sol (a fluid containing suspended particles; i.e., a colloid). As a pseudopodium, part of the ectoplasmic gel is converted to sol, whereupon endoplasm begins flowing toward this area, the cell wall expands, and the pseudopodium is extended forward. When the endoplasm, which continues…

endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins . All eukaryotic cells

insect: Annotated classification: Superorder Endopterygota (Holometabola) Metamorphosis complex, accompanied by a pupal instar; immature stages differ from adult in structure and habits; wings develop internally during larval stages. Order Megaloptera (alderflies, dobsonflies)

magnetic resonance: Combined electron-spin and nuclear magnetic resonances: …is known as ENDOR (electron-nuclear double resonance), whereas driving an ESR to increase a nuclear magnetization, observed by NMR, is called DNP (dynamic nuclear polarization).

Witch of Endor, in the Hebrew Bible (Old Testament; 1 Samuel 28:3–25), a female sorcerer who was visited by Saul, the first king of Israel. Although Saul had banished all sorcerers and conjurers from his kingdom, his concern about the final outcome of Israel’s battle against the Philistines caused

inland water ecosystem: The origin of inland waters: Endorheic regions are considered closed systems because, rather than draining to the sea, surface waters drain to inland termini whence they evaporate or seep away. Typically, the termini are permanent or temporary lakes that become saline as evaporation concentrates dissolved salts that either have been…

endorphin, any of a group of opiate proteins with pain-relieving properties that are found naturally in the brain. The main substances identified as endorphins include the enkephalins, beta-endorphin, and dynorphin, which were discovered in the 1970s by Roger Guillemin and other researchers.

cancer: Diagnostic procedures: …the physician can use an endoscope to inspect the internal cavities and hollow viscera. An endoscope is a flexible optical instrument that makes it possible not only to observe the appearance of the internal linings but also to perform a biopsy, a procedure used to procure a tissue sample from…

endoscopic retrograde cholangiopancreatoscopy, medical procedure in which a flexible fibre-optic scope is used to examine the bile duct and pancreatic ducts for the presence of gallstones, tumours, or inflammation. In this procedure an endoscope is passed through the stomach into the duodenum to