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Habituation to a specific practice, such as drinking alcoholic beverages or using drugs (for example, heroin, cocaine, or amphetamines), and disorders characterized by the chronic use of a drug, alcohol, or similar substance. Addiction and addictive…

A disease of the nervous system characterized by a progressive dementia that leads to profound impairment in cognition and behavior. Dementia occurs in a number of brain diseases where the impairment in cognitive abilities represents a decline from…

Any treatment or procedure that includes the in-vitro handling of oocytes (immature ova or egg cells) and sperm or embryos for the purpose of establishing a pregnancy. Assisted reproductive technology (ART) is undertaken as a treatment of…

Any of several leguminous plants, or their seeds, long utilized as food by humans or livestock. There are more than 40,000 varieties of beans, with only a small number of these being mass-produced for human or animal consumption. In particular,…

The common name for a malignant neoplasm or tumor. Cancer is a serious medical condition that develops when the orderly relationship of cell division and cell differentiation becomes disordered, leading to the development of neoplasms. Neoplasms are…

Cells within a tumor that possess the capacity to self-renew and cause the heterogeneous lineages of cancerous cells that comprise the tumor. Cancer stem cells (CSCs) typically represent a small percentage of all cells in a tumor (rarely more than…

Any member of the grass family (Poaceae or Gramineae) that produces edible grains usable as food by humans and livestock. Cereals are important cultivated crops. Common cereals include rice, wheat, barley, oats, maize (corn), sorghum, rye, and…

The administration of chemical substances for the treatment of disease, especially cancer, or for the prevention of aberrant growth of cells or tissues (neoplasms). In general, chemotherapy is the use of chemicals to treat any disease, but the term…

Any of a group of viruses that cause upper and lower respiratory tract diseases, gastroenteritis, hepatitis, and central nervous system infections in birds and mammals, including humans. Coronaviruses (Fig. 1) comprise a major group of common animal…

A genome-engineering technique that allows precise targeting of specific stretches of genetic code and editing of DNA at designated locations. The CRISPR/Cas9 system has been used as a general tool to engineer the genomes of many different…

The occurrence of cases of disease in excess of what is usually expected for a given period of time. An epidemic is a breakout of disease affecting unusually large numbers of people within a community or population. When an epidemic spreads…

The science, art, and practice of managing and using the natural resources that occur on and in association with forested lands. Forestry is the management of forested lands (see illustration). It involves the planning and implementation of…

Plants that have altered genetic material (DNA) through recombinant DNA (rDNA) manipulation. Genetic engineering of plants allows for very specific genetic changes to be made to a plant's deoxyribonucleic acid (DNA), as opposed to the random…

Commercially grown plants that have altered genetic material through artificial recombinant manipulation. Genetic modification is the latest scientific tool for developing improved crop varieties. Such genetically modified (GM) crops can help to…

An organism that has had its genetic material manipulated or altered in a laboratory setting through the use of genetic or genomic engineering techniques. Genetically modified organisms (GMOs) are microorganisms, plants, or animals that have been…

The artificial application of water to the soil to produce plant growth. Irrigation also cools the soil and atmosphere, making the environment favorable for plant growth. The use of some form of irrigation (Fig. 1) is well documented throughout the…

An emerging cancer therapy in which oncolytic viruses are used to target and destroy cancer cells without harming healthy cells. Oncolytic viruses (that is, viruses that destroy cancer cells, but not normal cells) are able to infect, replicate…

Any agent capable of causing disease. The term pathogen is usually restricted to living agents or microorganisms that produce disease. Pathogens are infectious and diverse, including bacteria (see illustration), viruses, rickettsia, fungi, yeasts,…

An annual leafy leguminous vine, Pisum sativum (order Fabales), cultivated for its smooth or wrinkled, round edible seeds, which are borne in dehiscent pods. The garden pea (Fig. 1) is one of the world's oldest cultivated crops. It is a native of…

The planning and implementation of actions to establish, protect, restore, and maintain trees and forests in cities and smaller communities. When the field of urban forestry began in the 1960s, it focused on individual trees along streets and…

A genus of Gram-negative, immotile and nonspore-forming, oval to rod-shaped, often pleomorphic bacteria that occur as parasites or pathogens in mammals (including humans), birds, and reptiles. Actinobacillus bacteria are facultatively aerobic,…

A bacterial genus in the family Vibrionaceae comprising oxidase-positive, facultatively anaerobic, monotrichously flagellated Gram-negative rods. The mesophilic species of Aeromonas are A. hydrophila, A. caviae, and A. sobria; the psychrophilic one…

A branch of meteorology that examines the effects and impacts of weather and climate on crops, rangeland, livestock, and various agricultural operations. Agricultural meteorology, or agrometeorology, addresses topics that often require an…

The pure and applied science that is concerned with botany and management of crop and ornamental plants for utilization by humankind. As it relates to plants, agricultural science concerns itself with the application of scientific methods to…

The art and science of crop and livestock production. In its broadest sense, agriculture comprises the entire range of technologies associated with the production of useful products from plants and animals, including soil cultivation, crop and…

The science and study of crops and soils. Agronomy is the umbrella term for a number of technical research and teaching activities (see illustration): crop physiology and management, soil science, plant breeding, and weed management frequently are…

Any of the organic compounds possessing one or more basic amino groups and one or more acidic carboxyl groups. Of the more than 80 amino acids that have been found in living organisms, approximately 20 serve as the building blocks for proteins.…

Any of a group of drugs of diverse chemical structure and physiological effects that are used for the relief of pain. Analgesics are drugs, including opiates, synthetic opioids, and salicylates, that are used primarily for pain relief (see…

A small infectious agent that is unable to replicate outside a living animal cell. Animal viruses infect animals and require animal cells as their host. Unlike other intracellular obligatory parasites (for example, chlamydiae and rickettsiae…

A chemical substance, produced by microorganisms, plants, marine organisms, and synthetically, that has the capacity in dilute solutions to inhibit the growth of bacteria or destroy bacteria. Antibiotics are important antibacterial agents. Most are…

The capability that a bacterium acquires to counteract an inhibitory chemical molecule or compound that was formerly effective in killing it or preventing its growth. Antibiotic resistance in bacteria (Fig. 1) is a hot topic in the media and in…

Chemical compounds biosynthetically or synthetically produced that destroy or usefully suppress the growth or metabolism of a variety of microscopic or submicroscopic forms of life. On the basis of their primary activity, antimicrobial agents (see…

A deciduous tree (genus Malus) in the order Rosales, which produces an edible, simple, fleshy, pome-type fruit. Apples (Fig. 1) belong to the family Rosaceae, which includes many other deciduous fruits, including pears, peaches, and cherries. There…

A group of diseases affecting joints or their component tissues. Arthritis is the collective term used to describe any joint disorder or process; it also typically involves inflammation. In common usage, arthritis often refers to any joint pain.…

Vegetables that are prevalent in Asian cuisines, but less well known in Western diets. Asian vegetables (Fig. 1), also referred to as Asian greens or oriental vegetables, are very important in Asian countries, but are not as popular in North America…

A nonsteroidal anti-inflammatory drug used to control pain, fever, and inflammation. Aspirin is one of the most prevalent medicines in the world and is used to reduce fever and treat minor aches, pains, and inflammation. Furthermore, it is the only…

The most common type of arrhythmia (any disorder of the heart rate or rhythm). Atrial fibrillation, often abbreviated AFib or AF, is a heart condition that can lead to potentially serious complications. It is associated with decreased quality of…

The study of bacteria. The science of bacteriology is a specialized branch of microbiology concerned with bacteria (Fig. 1). Although bacteria are different in some important respects from all other kinds of cells, their basic processes of…

A large tropical plant of the genus Musa and its edible fruit. The banana belongs to the family Musaceae (order Zingiberales). The banana of commerce (Musa acuminata), which is believed to have originated in the Asian tropics, was one of the…

The management and maintenance of colonies of honeybees for human purposes. Beekeeping is an ancient art. Although the commonly known honeybee species (Fig. 1) is native to Europe and Africa, humans have transported them to other continents. The…

The study of behavior change in response to drugs, chemicals, or other environmental conditions or agents. Behavioral toxicology investigates the effect of toxic exposure on organismal behavior. The toxic exposure can involve various chemicals,…

The use of parasitoids, predators, and pathogens to reduce injurious pest insect populations and consequently the damage that they cause. Biological insect control (or insect biocontrol) is the regulation of insect populations by biological means.…

The application of principles from applied and physical sciences to problems in healthcare and biology. As a field, biomedical engineering draws from a variety of disciplines including mechanical, chemical, electrical, and computer engineering, as…

A form of terrorism in which there is the intentional release of biological agents (viruses, bacteria, fungi, or toxins) from living organisms or agents in order to cause death or disease in humans, animals, and/or plants; also referred to as…

The practice of fertility control, including contraception, which is intended to prevent pregnancy, and the means of interrupting early pregnancy. The efficacy of the various methods of birth control and their consistency of use vary widely (see…

A genus of pathogenic gram-negative bacteria that are coccobacilli and obligate aerobes, and fail to ferment carbohydrates. Bordetella bacteria are respiratory pathogens. Bordetella pertussis, B. parapertussis, and B. bronchiseptica share greater…

The reaction that occurs when tissue (usually skin) receives more energy (heat, chemical energy, electrical energy, or radiation) than it can absorb without injury. Factors such as the duration of contact, temperature, volume of chemical, and…

A genus comprising yeasts that cause a variety of human diseases referred to as candidiasis. All Candida species are single-celled yeasts (fungal organisms) that are ovoid in shape and 3–5 μm in size, and they multiply by a process called budding.…

Any of the group of organic compounds consisting of carbon, hydrogen, and oxygen that includes sugars, starches, and cellulose. Carbohydrate compounds consist of carbon, hydrogen, and oxygen, with the general chemical formula Cm(H2O)n [Fig. 1]; the…

A biennial umbellifer (Daucus carota) of Asiatic and Mediterranean origin belonging to the plant order Apiales. The carrot (Daucus carota; Fig. 1) is grown for its edible roots, which are eaten raw or cooked. Cultivated forms of the root vegetable…