spitting cobra: Species, range, and conservation status: …category, though the potentially extinct Hemachatus nyangensis was confirmed as another species of ringhals, based on genetic studies done on a specimen collected in 1982. This last snake is believed to be endemic to the eastern highlands of Zimbabwe, though no specimen has been spotted in the wild for several…

Sendai virus, (genus Respirovirus), infectious agent of the genus Respirovirus in the family Paramyxoviridae. Discovered in Sendai, Japan, the Sendai virus is naturally found in mice, rats, hamsters, guinea pigs, and pigs and primarily affects the respiratory system. The virus is highly contagious

pregnancy: Symptoms and signs; biological tests: …based upon the inhibition of hemagglutination (clotting of red cells). A positive test is obtained when human chorionic gonadotropin (HCG) in the woman’s urine or blood is added to human chorionic gonadotropin antiserum (rabbit blood serum containing antibodies to HCG) in the presence of particles (or red blood cells) coated…

hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to agglutinate, or clump together. These substances are found in plants, invertebrates, and certain microorganisms. Among the best-characterized hemagglutinins are those that occur as

serological test: Hemagglutinin-inhibition tests are based on the ability of viruses to cause the red blood cells of certain animal species to agglutinate (congeal, or clump together); this agglutination will be prevented by the antibody. ELISAs make use of fluorescent, light (chemiluminescent), or colorimetric signal detection; the…

eye disease: Tumours of the lids: …of the blood vessels, called hemangiomas, may occur in the lids and give rise to soft, bluish swellings. They are most often present at birth and tend to grow in the first few years of life, sometimes contributing to obscuration of vision and amblyopia. Often they disappear spontaneously, but they…

infantile hemangioma, a congenital benign tumour made up of endothelial cells (the cells lining the inner surface of a blood vessel) that form vascular spaces, which then become filled with blood cells. Infantile hemangiomas are the most commonly occurring tumours in infants and are only rarely

Felicia Dorothea Hemans was an English poet who owed the immense popularity of her poems to a talent for treating Romantic themes—nature, the picturesque, childhood innocence, travels abroad, liberty, the heroic—with an easy and engaging fluency. Poems (1808), written when she was between 8 and 13,

Sena dynasty: Hemantasena, the founder of the dynasty, was originally a tributary of the Pala dynasty. In the mid-11th century he declared his independence and set himself up as king. His successor, Vijayasena (reigned c. 1095–1158), built an empire on the ruins of that of the Palas,…

joint disease: Hemorrhagic joint diseases: Hemarthrosis (bleeding into the joints) is a major complication of hemorrhagic disorders. Aside from the life-threatening episodes of bleeding, it constitutes the principal disability arising from the hemophilias. Most persons with these clotting defects are affected and usually within the first years of life. Bleeding…

human digestive system: Hematinics: Hematinics are substances that are essential to the proper formation of the components of blood. Examples of hematinics include folic acid, vitamin B12, and iron. In addition, vitamin D, which helps maintain the health of bones—the reservoirs of new blood cells—may also have a…

hematite, heavy and relatively hard oxide mineral, ferric oxide (Fe2O3), that constitutes the most important iron ore because of its high iron content (70 percent) and its abundance. Its name is derived from the Greek word for “blood,” in allusion to its red colour. Many of the various forms of

mineral: Oxides and hydroxides: Members of the hematite group are of the X2O3 type and have structures based on hexagonal closest packing of the oxygen atoms with octahedrally coordinated (surrounded by and bonded to six atoms) cations between them. Corundum and hematite share a common hexagonal architecture. In the ilmenite structure, iron…

hematocrit, diagnostic procedure for the analysis of blood. The name is also used for the apparatus in which this procedure is performed and for the results of the analysis. In the procedure, an anticoagulant is added to a blood sample held in a calibrated tube. The tube is allowed to stand for one

bone disease: Infectious diseases of bone: The incidence of hematogenous osteomyelitis reflects the fact that the body is more susceptible to invasion by microorganisms when nutrition and hygiene are poor. Thus, hematogenous osteomyelitis is common in South America, Asia, and Africa. In developed countries, hematogenous osteomyelitis is often associated with slum conditions or systemic…

hematology, branch of medical science concerned with the nature, function, and diseases of the blood. In the 17th century, Dutch microscopist Antonie van Leeuwenhoek, using a primitive, single-lens microscope, observed red blood cells (erythrocytes) and compared their size with that of a grain of

hemolysis, breakdown or destruction of red blood cells so that the contained oxygen-carrying pigment hemoglobin is freed into the surrounding medium. Hemolysis occurs normally in a small percentage of red blood cells as a means of removing aged cells from the bloodstream and freeing heme for iron

hematoma, pooling of blood in tissues or spaces outside the blood vessels that results when a vessel is cut or torn, such as through injury or other forms of trauma. Blood and other fluids leak from the damaged vessel and collect in a mass. Affected tissues often swell and are painful. A hematoma

blood cell formation, continuous process by which the cellular constituents of blood are replenished as needed. Blood cells are divided into three groups: the red blood cells (erythrocytes), the white blood cells (leukocytes), and the blood platelets (thrombocytes). The white blood cells are

therapeutics: Hematopoietic growth factors: The hematopoietic growth factors are potent regulators of blood cell proliferation and development in the bone marrow. They are able to augment hematopoiesis when bone marrow dysfunction exists. Recombinant DNA technology has made it possible to clone the genes responsible for many…

bone marrow transplant: Autologous and allogeneic transplants: …of stem cell therapy, since hematopoietic stem cells from the bone marrow are central to the recovery of the patient receiving the graft. An autologous transplant is used primarily in the case of cancer patients who are preparing to undergo high doses of chemotherapy or radiation therapy. Autologous transplant involves…

AIDS: Reported cures: …who had undergone allogeneic (nonself) hematopoietic stem cell transplantation (HSCT)—a procedure that entails the exchange of a patient’s blood-forming cells for those from a donor—for lymphoma was found to be HIV-negative following transplantation. The patient died shortly after from tumour relapse. The most-popularized case involved a 42-year-old man, Timothy Ray…

hematuria, presence of blood in the urine, an indication of injury or disease of the kidney or some other structure of the urinary tract; in males blood in the urine can also come from the reproductive tract. The blood may become apparent during urination or only upon microscopic examination.

African art: Lower Congo (Kongo) cultural area: …Yaka tudansi mask is the hemba mask of the nearby Suku, which is only slightly less grotesque. Carved Suku figures show more rounded forms than do the Yaka.

Jan van Hembyze was a Calvinist leader who overthrew Ghent’s Roman Catholic-dominated government (1577) during the Netherlands’ struggle for freedom from Spanish control. Supported by Francis van de Kuthulle, lord of Ryhove, and the leading Calvinist preacher, Petrus Dathenus, Hembyze led some

battlefield medicine: These dressings include HemCon, which is made with chitosan (an extract from shrimp shells), and QuikClot, which is made with inorganic zeolite granules.

hemoglobin: …is made up of four heme groups surrounding a globin group, forming a tetrahedral structure. Heme, which accounts for only 4 percent of the weight of the molecule, is composed of a ringlike organic compound known as a porphyrin to which an iron atom is attached. It is the iron…

blood disease: Thalassemia and hemoglobinopathies: …of the molecule called the heme pocket, which normally protects the iron against oxidation, despite the fact that oxygen is being carried at this site.

cytochrome: Hemoproteins are proteins linked to a nonprotein, iron-bearing component. It is the iron (heme) group attached to the protein that can undergo reversible oxidation and reduction reactions, thereby functioning as electron carriers within the mitochondria (the organelles that produce energy for the cell through cellular…

meat processing: Skeletal muscle contraction: …a nonprotein group called the heme ring. The heme ring consists of a porphyrin molecule bound to an iron (Fe) atom. The iron atom is responsible for the binding of oxygen to myoglobin and has two possible oxidation states: the reduced, ferrous form (Fe2+) and the oxidized, ferric form (Fe3+).…

Hemel Hempstead, town and urban area (from 2011 built-up area), Dacorum district, administrative and historic county of Hertfordshire, south-central England, northwest of London. The first charter was granted in 1539. The new town, one of eight designed by British planners to accommodate London’s

Thomas à Kempis was a Christian theologian, the probable author of Imitatio Christi (Imitation of Christ), a devotional book that, with the exception of the Bible, has been considered one of the most influential works in Christian literature. About 1392 Thomas went to Deventer, Netherlands,

neuropteran: Annotated classification: Family Hemerobiidae (brown lacewings) Adults small; antennae long, moniliform; ocelli absent; wings with few crossveins, hairy; female without projecting ovipositor. Larvae (called aphis wolves) elongated, with short incurved jaws; body smooth, fine hairs; free-living on vegetation. Family Sympherobiidae (brown lacewings) Adults small,

daylily, any plant of the genus Hemerocallis of the family Hemerocallidaceae, consisting of about 15 species of perennial herbs distributed from central Europe to eastern Asia. Members of the genus have long-stalked clusters of funnel- or bell-shaped flowers that range in colour from yellow to red

tussock moth: Some, such as the white-marked tussock moth (Hemerocampa leucostigma), lack wings.

David Hemery is an English hurdler who held the 400-metre-hurdles world record of 48.1 sec (1968–72). His father’s work took the family to the United States, where Hemery attended school, graduating from Boston University in 1969. He competed with the British team in the 1966 Commonwealth Games at

David Hemery is an English hurdler who held the 400-metre-hurdles world record of 48.1 sec (1968–72). His father’s work took the family to the United States, where Hemery attended school, graduating from Boston University in 1969. He competed with the British team in the 1966 Commonwealth Games at

coloration: Hemerythins: Iron-containing, proteinaceous pigments, hemerythrins are present in the blood of certain bottom-dwelling marine worms (notably burrowing sipunculids) and of the brachiopod Lingula; the pigments serve as oxygen-carriers.

human eye: Striate area: …lesions will be half-blindness, or hemianopia, the messages from one half of the visual field being obliterated.

human cardiovascular system: Superior vena cava and its tributaries: …the azygous, hemiazygous, and accessory hemiazygous veins. At the level of the diaphragm, the right ascending lumbar vein continues upward as the azygous vein, principal tributaries of which are the right intercostal veins, which drain the muscles of the intercostal spaces. It also receives tributaries from the esophagus, lymph nodes,…

human nervous system: Subthalamus: …of the subthalamic nucleus produce hemiballismus, a violent form of dyskinesia in which the limbs are involuntarily flung about.

human nervous system: Subthalamus: …of the subthalamic nucleus produce hemiballismus, a violent form of dyskinesia in which the limbs are involuntarily flung about.

hemicellulose, any of a group of complex carbohydrates that, with other carbohydrates (e.g., pectins), surround the cellulose fibres of plant cells. The most common hemicelluloses contain xylans (many molecules of the five-carbon sugar xylose linked together), a uronic acid (i.e., sugar acid), and

tenrec: The streaked tenrec is about the same size; its fur consists of detachable barbed spines and coarse hairs. The common, or tailless, tenrec (Tenrec ecaudatus) is the largest, weighing 2 kg (4.4 pounds) or more.

hemichordate, any of a group of wormlike marine invertebrates closely related to both chordates and echinoderms and usually considered to constitute a phylum, the Hemichordata. The term Hemichordata—from the Greek hemi, meaning “half,” and chorde, meaning “string,” thus, “half-chordate”—was first

hemichordate, any of a group of wormlike marine invertebrates closely related to both chordates and echinoderms and usually considered to constitute a phylum, the Hemichordata. The term Hemichordata—from the Greek hemi, meaning “half,” and chorde, meaning “string,” thus, “half-chordate”—was first

history of medicine: Support from other technologies: …been considering for 12 years: hemicorporectomy—surgical removal of the lower part of the body. The patient died on the 11th day. The first successful hemicorporectomy (at the level between the lowest lumbar vertebra and the sacrum) was performed 18 months later by J. Bradley Aust and Karel B. Absolon of…

sundial: Another early device was the hemispherical sundial, or hemicycle, attributed to the Greek astronomer Aristarchus of Samos about 280 bce. Made of stone or wood, the instrument consisted of a cubical block into which a hemispherical opening was cut. To this block a pointer or style was fixed with one…

Miocene Epoch: …first emergence of the bear-dog Hemicyon occurs close to the origin of the bears. The first hyenas, springing from primitive civets, appeared in the Miocene, as did the first sabre-toothed cats of the subfamily Machairodontinae. Primitive antelope, deer, and giraffes appeared in Eurasia during the Miocene. Ancestors of the modern…

Caudata: Annotated classification: …genera, placed in 2 subfamilies: Hemidactyliinae, with 21 genera (including Bolitoglossa) and about 373 species in North America, Central America, and South America, and Plethodontinae, with 7 genera (including Plethodon and Desmognathus in North America and Hydromantes in western North America and the central

lizard: General features: …of the best-known lizards, the Mediterranean gecko (Hemidactylus mabouia), is so common in houses and buildings that most Brazilians know more about it, based on their own observations, than they know about any of the endemic species. As is the case with many introduced lizards, the Mediterranean gecko appears to…

gecko: …in only one species, the flat-tailed house gecko (Hemidactylus platyurus), herpetologists argue that many other geckos may also possess it.

fern: Annotated classification: Family Hemidictyaceae Plants with a Neotropical distribution; veins are netted only halfway each leaflet across the pinnules, family consists of a single species (Hemidictyum marginatum). Family Onocleaceae Plants in soil; rhizomes short- to long-creeping or erect (occasionally trunklike in Onocleopsis), scaly, sometimes with runners;

hedgehog: …African hedgehogs (genus Atelerix), six desert hedgehogs (genus Hemiechinus), and two steppe hedgehogs (genus Mesechinus). European hedgehogs are kept as pets, as is the African pygmy hedgehog (Atelerix albiventris).

hedgehog: The desert hedgehog (Hemiechinus aethiopicus) survives in the extremely arid Sahara and on the Arabian Peninsula, where populations are concentrated around oases and vegetated wadis.

nervous system disease: Facial nerve: In hemifacial spasm repetitive twitching of one side of the face occurs. Irritation of the facial nerve as it leaves the brainstem appears to be the cause, and in many cases relief is obtained through surgical decompression.

chondrichthyan: Annotated classification: Family Hemigaleidae (weasel sharks) Intermediate in many ways between Triakidae and Carcharhinidae. Length to 2–2.4 metres (6.5–8 feet). 4 genera, 7 species; nearshore waters of tropical Atlantic, Pacific, and Indian oceans. Miocene to recent. Family Carcharhinidae (tiger sharks, blue

tetra: The Buenos Aires tetra (Hemigrammus caudovittatus) grows to 9 cm; it has reddish fins and a dark, lengthwise stripe on each side that widens to a diamond-shaped spot on each side of the tail root.

tetra: The glowlight tetra (Hemigrammus erythrozonus) is a hardy fish that grows up to 4.5 cm long and has a shining red stripe along each side of its body.

theatre: Visual and spatial aspects: …these new machines was the hemikyklion, a semicircle of canvas depicting a distant city, and a stropheion, a revolving machine, used to show heroes in heaven or battles at sea.

coffee rust: … plants caused by the fungus Hemileia vastatrix. Coffee rust has long been known in coffee-growing areas of Africa, the Near East, India, Asia, and Australasia, and it destroyed the once-flourishing coffee plantations of Ceylon (now Sri Lanka) and Java in the late 1800s. In 1970 the disease was discovered to…

malformation: Somatic characters: …incomplete or underdeveloped extremities (hemimelus, micromelus, ectromelus).

malformation: Somatic characters: …incomplete or underdeveloped extremities (hemimelus, micromelus, ectromelus).

insect: Types of metamorphosis: …hemimetabolous, are said to undergo incomplete metamorphosis. The higher orders of insects, including Lepidoptera (butterflies and moths), Coleoptera (beetles), Hymenoptera (ants, wasps, and bees), Diptera (true flies), and several others, are called holometabolous because larvae are totally unlike adults. These larvae undergo a series of molts with little change in…

insect: Types of metamorphosis: …hemimetabolous, are said to undergo incomplete metamorphosis. The higher orders of insects, including Lepidoptera (butterflies and moths), Coleoptera (beetles), Hymenoptera (ants, wasps, and bees), Diptera (true flies), and several others, are called holometabolous because larvae are totally unlike adults. These larvae undergo a series of molts with little change in…

hemimorphite, one of two minerals formerly called calamine in the U.S., a white silicate mineral that is an important zinc ore. A secondary mineral formed from the alteration of sphalerite, it is a hydrated basic zinc silicate, Zn4Si2O7(OH)2·H2O. It is associated with other zinc ores in veins and

Hans Fischer: …research into the constitution of hemin, the red blood pigment, and chlorophyll, the green pigment in plants.

measurement system: Greeks and Romans: …Roman capacity measures were the hemina, sextarius, modius, and amphora for dry products and the quartarus, sextarius, congius, urna, and amphora for liquids. Since all of these were based on the sextarius and since no two extant

John Heminge was an English actor who, with Henry Condell, prepared and oversaw the First Folio (1623), a collection of Shakespeare’s plays. Heminge was an integral and prosperous member of the theatrical company that eventually became the King’s Men in 1603. Though not an exceptional actor, he

John Heminge was an English actor who, with Henry Condell, prepared and oversaw the First Folio (1623), a collection of Shakespeare’s plays. Heminge was an integral and prosperous member of the theatrical company that eventually became the King’s Men in 1603. Though not an exceptional actor, he

Sally Hemings was an American slave who was owned by U.S. Pres. Thomas Jefferson and is widely believed to have had a relationship with him that resulted in several children. (Read Joseph Ellis’s Britannica essay on the Sally Heming’s affair.) Hemings, known as Sally but who was likely named Sarah,

Ken Burns: Muhammad Ali, Leonardo, and The Central Park Five: …then codirected the multipart series Hemingway (2021), about the life and work of the literary giant; Muhammad Ali (2021), an in-depth look at the legendary boxer; and The U.S. and the Holocaust (2022), which explores how racism and anti-Semitism contributed to America’s slow response to the

Philip Kaufman: Films in the 21st century: …Kaufman made the television movie Hemingway & Gellhorn (2012). The HBO production featured Clive Owen as the mercurial author and Nicole Kidman as the equally formidable journalist Martha Gellhorn.

Kenny Chesney: …Lucky Old Sun (2008), and Hemingway’s Whiskey (2010)—were evocative of life in the tropics. Between 2000 and 2010, 10 of his albums reached the top spot on Billboard’s country albums chart. Indeed, by the second decade of the 21st century, Chesney had become one of the most popular musicians of…

Ernest Hemingway was an American novelist and short-story writer who was awarded the Nobel Prize for Literature in 1954. He was noted both for the intense masculinity of his writing and for his adventurous and widely publicized life. His succinct and lucid prose style exerted a powerful influence

Ernest Hemingway was an American novelist and short-story writer who was awarded the Nobel Prize for Literature in 1954. He was noted both for the intense masculinity of his writing and for his adventurous and widely publicized life. His succinct and lucid prose style exerted a powerful influence

Ernest Hemingway was an American novelist and short-story writer who was awarded the Nobel Prize for Literature in 1954. He was noted both for the intense masculinity of his writing and for his adventurous and widely publicized life. His succinct and lucid prose style exerted a powerful influence

Carlos Baker: His widely acclaimed Hemingway: The Writer as Artist (1952) is regarded as one of the definitive works on the writer. It provides a portrait of an artist and his generation and a critique of Hemingway’s novels in moral and aesthetic terms. Baker’s Ernest Hemingway: A Life Story (1969)…

ostariophysan: Annotated classification: Family Hemiodontidae (hemiodontid pencil fishes) Lower jaw toothless. Tail-standing posture. Herbivorous. Aquarium fishes. Size to 20 cm (8 inches). Family Parodontidae is similar. South and Central America. 5 genera, about 28 species. Family Parodontidae (parodontids) Panama and South America. 3 genera,

Orobanchaceae: Physical description: Many species are hemiparasites; that is, they have green foliage and are photosynthetic but supplement their nutritional needs by siphoning the products of photosynthesis from their hosts. Such plants usually have opposite leaves and commonly feature glandular hairs. Other members of the family are holoparasites and have little…

lapwing: …of eastern Asia, and the long-toed lapwing (Hemiparra crassirostris), of Africa.

marine sediment: …rises, frequently referred to as hemipelagic sediments, ordinarily accumulate too rapidly to react chemically with seawater. In most cases, individual grains thus retain characteristics imparted to them in the area where they formed. As a rule, sediments deposited near coral reefs in shallow tropical waters contain abundant carbonate material. Calcareous,…

reptile: Courtship and fertilization: … [order Crocodylia, or Crocodilia]) or hemipenes (as in lizards and snakes [order Squamata]). The penis is a homologue of the mammalian penis, and its presence in reptiles indicates that this organ arose early in the evolution of the amniotes and prior to the origin of reptiles and synapsids. In contrast,…

bee fly: Several African species of Villa and Thyridanthrax are parasitic on the covering of the pupa of tsetse flies. Villa (Hemipenthes) morio is parasitic on the beneficial ichneumonid, Banchus femoralis. Some bee mimics in the family Syrphidae are also known as bee flies.

frog and toad: Annotated classification: …Phyllomedusinae (Central and South America), Hemiphractinae (Central and South America), and Hylinae (North and South America, Europe, Asia except Indian subregion, and Africa north of Sahara). Family Leptodactylidae Eocene to present; 8 presacral vertebrae; pectoral girdle arciferal; maxillary teeth present; Bidder’s organ and intercalary cartilages absent; omosternum cartilaginous or

frog and toad: Direct development from egg to froglet: In Hemiphractus gill-like structures and cords similar to those in Gastrotheca are present. At hatching, the expanded gill adheres to the modified skin of the maternal depression and is attached to the young by the pair of cords. The female carries the young until they are…

hemiplegia, paralysis of the muscles of the lower face, arm, and leg on one side of the body. The most common cause of hemiplegia is stroke, which damages the corticospinal tracts in one hemisphere of the brain. The corticospinal tracts extend from the lower spinal cord to the cerebral cortex. They

hemipode, (Greek: “half foot”), generally any bird of the suborder Turnices (order Gruiformes), which includes the plains wanderer (q.v.; family Pedionomidae), the button quail, and the lark quail (family Turnicidae), but especially Turnix species, such as the Andalusian hemipode, or striped button

crested swift: A widespread species is the crested tree swift (Hemiprocne longipennis), ranging from Southeast Asia eastward to the Celebes. It is about 20 cm (8 inches) long and has pale blue-gray upperparts, dark brown wings and tail, and reddish cheeks. The 29-centimetre-long whiskered tree swift (H. mystacea) of Southeast Asia is…

crested swift: The 29-centimetre-long whiskered tree swift (H. mystacea) of Southeast Asia is mostly black.

crested swift, (family Hemiprocnidae), any of three or four species of fork-tailed forest birds ranging from Southeast Asia and Australia to the Solomon Islands. Crested swifts differ from all other members of the order Apodiformes (e.g., hummingbirds) in having feet developed for effective

Ulmaceae: Major genera and species: Thorn-elm (Hemiptelea davidii) is the sole member of its genus and is native to Asia. Members of the genus Holoptelea are found in Asia and Africa and are used locally as medicinal plants.

heteropteran, any member of the insect order Heteroptera, which comprises the so-called true bugs. (Some authorities use the name Hemiptera; others consider both the heteropterans and the homopterans to be suborders of the Hemiptera.) This large group of insects, consisting of more than 40,000

scorpion: Annotated classification: Family Hemiscorpiidae 7 dangerous species of eastern Africa and southwestern Asia. Family Microcharmidae 7 species of Central Africa and Madagascar. Family Troglotayosicidae 2 species found only in caves of France, Spain, and Ecuador.

chondrichthyan: Annotated classification: Family Hemiscylliidae (longtail carpet sharks) Length to 1 metre (about 3 feet) long, slender body and elongated upper lobe of tail. 2 genera, 12 species; tropical Indo-Pacific. Family Stegostomatidae (zebra sharks) Young are black-and-yellow-striped, adults light with dark spots. Upper lobe of tail

San Antonio: The contemporary city: HemisFair Park, the site of the world’s fair, is linked to the central city by the River Walk and is used for conventions and exhibitions; the park’s Institute of Texan Cultures traces nationalities of Texas, and its Tower of the Americas, 750 feet (229 metres)…

frog and toad: Annotated classification: Family Hemisotidae No fossil record; 7 presacral vertebrae; vertebral procoelous with Presacrals I and II fused; body globular with pointed snout; inner metatarsal tubercle large and spadelike; aquatic larvae; 1 genus, 8 species; adult size 4–8 cm (1.5–3 inches); Africa. Family Hyperoliidae No fossil record; 8…

hemisphere, in geometry and geography, half of a sphere. Although any spherical body can be divided into an infinite number of hemispheres, geographers often divide Earth’s surface into four hemispheres that are separated by two great circle routes—that is, lines that represent the shortest

human nervous system: Cerebral hemispheres: Basic organizations of movement, such as reciprocal innervation, are organized at levels of the central nervous system lower than the cerebral hemispheres—at both the spinal and the brainstem level. Examples of brainstem reflexes are turning of the eyes and head toward a light…

Ben Carson: …refined a technique known as hemispherectomy, in which one-half of the brain is removed to prevent seizures in persons with severe epilepsy. He later became active in politics and served as U.S. secretary of housing and urban development (HUD; 2017–21) in the administration of U.S. Pres. Donald Trump.