Science & Philosophy: Bilateral symmetry to Boolean algebra

Science Encyclopedia

Bilingualism and Multilingualism - Language Diversity, Language Diversity In Civil Society, Government Policies To Accommodate Language Diversity, Evaluation Of Language Policies

A bilingual individual, generally, is someone who speaks two languages. An ideal or balanced bilingual speaks each language as proficiently as an educated native speaker. This is often referred to as an ideal type since few people are regarded as being able to reach this standard. Otherwise, a bilingual may be anywhere on a continuum of skills. Literacy abilities may be an additional dimension to …

1 minute read

Binary Star - Importance, Visual Binaries, Study Of Orbital Motion, Astrometric Binaries, Spectroscopic Binaries, Eclipsing Binaries - Techniques of observation

Binary stars, often called double stars, refer to pairs of stars sufficiently close to each other in space to be gravitationally bound together. Following the laws of gravitation, each of the components revolves around the common center of mass of the system. At least 50% of stars are found to exist as binary systems, according to conservative statistics. There seems to be no obvious preference fo…

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Binocular

In 1823, a new optical instrument began to appear in French opera houses that allowed patrons in the distant (and less expensive) seats to view the opera as if they were in the front row. Called opera glasses, the device combined telescope lenses with stereoscopic prisms to provide a magnified, three-dimensional view. After many years (but relatively few modifications), opera glasses have evolved …

3 minute read

Binomial Theorem

The question of expanding an equation with two unknown variables called a binomial was posed early in the history of mathematics. One solution, known as Pascal's triangle, was determined in China as early as the thirteenth century by the mathematician Yang Hui. His solution was independently discovered in Europe 300 years later by Blaise Pascal whose name has been permanently associated wit…

3 minute read

Bioaccumulation

Bioaccumulation is the gradual build up over time of a chemical in a living organism. This occurs either because the chemical is taken up faster than it can be used, or because the chemical cannot be broken down for use by the organism (that is, the chemical cannot be metabolized). Bioaccumulation need not be a concern if the accumulated compound is not harmful. Compounds that are harmful to healt…

4 minute read

Bioassay

A bioassay is the use of a living organism to test for the presence of a compound or to determine the amount of the compound that is present in a sample. The organism used is sensitive to the compound for which the test is conducted. Thus, the effect observed is typically the death or deteriorated health of the test organism. Depending on the test organism, soil, air, or liquid samples can be assa…

3 minute read

Biochemical Oxygen Demand

Oxygen is the molecule used by animals as a final electron acceptor for metabolism. Two electrons (one at a time) from metabolic products can chemically bind each oxygen molecule. While numerous molecules combine with oxygen in the human body, one of the major chemical reactions involving oxygen is the synthesis of the high-energy phosphate bonds in ATP. ATP is the cell's currency for gener…

6 minute read

Biochemistry - Origins Of And Development Of Biochemistry, Modern Biochemistry

Biochemistry is the study of the molecular basis of life. The study of biochemistry includes the knowledge of the structure and function of molecules found in the biological world and an understanding of the precise biochemical pathways by which organic molecules are either put together or broken down. Biochemistry seeks to describe the structure, organization, and functions of living matter in mo…

1 minute read

Biodegradable Substances

The term biodegradable is used to describe materials that decompose through the actions of bacteria, fungi, and other living organisms. Temperature and sunlight may also play roles in the decomposition of biodegradable plastics and other substances. If such materials are not biodegradable, they remain in the environment for a long time, and, if these same substances are toxic, they may pollute the…

3 minute read

Biodiversity - Species Richness Of The Biosphere, Why Is Biodiversity Important?, Biodiversity And Extinction, Protection Of Endangered Biodiversity

Biodiversity is the total richness of biological variation. The scope of biodiversity is usually considered to range from the genetic variation of individual organisms within and among populations of a species, to different species occurring together in ecological communities. Some definitions of biodiversity also include the spatial patterns and temporal dynamics of populations and communities on…

less than 1 minute read

Bioenergy - Primary ways of using bioenergy, Sources of biomass, Advantages and disadvantages of bioenergy

Bioenergy is energy derived using organic material, especially plant matter, as fuel. The material burned or processed to produce bioenergy (the "feedstock") is called biomass. Biomass has been an energy source for as long as humans have used wood fires to warm themselves and cook food. Wood is still the most commonly used biomass fuel. In some developing countries, crop and logging …

10 minute read

Biofilms

A biofilm is a population of bacteria, algae, yeast, or fungi that is growing attached to a surface. The surface can be living or nonliving. Examples of living surfaces where biofilms may grow include the teeth, gums, and the cells that line the intestinal and vaginal tracts. Examples of nonliving surfaces include rocks in watercourses, and implanted medical devices such as catheters. Rudimentary …

3 minute read

Biography - Ancient Biography, Medieval And Renaissance Biography, The Seventeenth And Eighteenth Centuries, The Nineteenth And Twentieth Centuries

One of the oldest genres of literature, biography is a written account of a person's life. It is also known as "life writing," a broader term that encompasses autobiography and other narrative forms such as letters, memoirs, journals, and diaries. The term biography derives from the Greek bios (life) and graphein (to write). Latin and Greek terms for biography were used in ant…

2 minute read

Bioinformatics and Computational Biology

Bioinformatics, or computational biology, refers to the development of new database methods to store genomic information, computational software programs, and methods to extract, process, and evaluate this information, and the refinement of existing techniques to acquire the genomic data. Finding genes and determining their function, predicting the structure of proteins and RNA sequences from the …

3 minute read

Biological Community

In biology, the term species refers to all organisms of the same kind that are potentially capable, under natural conditions, of breeding and producing fertile offspring. The members of a species living in a given area at the same time constitute a population. All the populations living and interacting within a particular geographic area make up a biological (or biotic) community. The living organ…

5 minute read

Biological Warfare - Historical Perspective Of Biological Warfare, Genetically Engineered Weapons And Other Biological Weapons

Biological warfare is the use of living organisms (e.g., bacteria, virus) or biochemical agents (e.g., chemical neurotoxins) as strategic military weapons to cause harm in humans, animals, or plants. In contrast to bioterrorism, biological warfare is considered the governmentsanctioned use of biological weapons to attack a clearly defined military force or civilian population. These agents can be …

1 minute read

Biology - The Origins Of Biology, Modern Biology, Properties Of Living Organisms, Early Definitions Of Biology

Biology comes from the Greek word for life, bis, and the Greek word for thought or reasoning, logos. It denotes the science that studies life, the properties and processes that sustain life, the evolutionary history of life, and particular living organisms. It is a science of enormous diversity, breadth, and heterogeneity unified only by the conceptual framework provided by the theory of evolution…

2 minute read

Biology - Important discoveries in biological science

Biology is the scientific study of all forms of life, including plants, animals, and microorganisms. Among the numerous fields in biology are microbiology, the study of microscopic organisms like bacteria; cytology, the study of cells; embryology, the study of development; genetics, the study of heredity; biochemistry, the study of the chemical structures in living things; morphology, the study of…

4 minute read

Biomass

Biomass consists of living organisms, or parts of living organisms, as well as waste products and incompletely decomposed remains of living organisms. The term is quite encompassing and includes plants (referred to as phytomass), microbes, and animal material, or zoomass. Biomass density is a distinguishing feature of ecological systems and is usually presented as the amount of dry biomass per uni…

1 minute read

Biome - Major Biomes And Their Characteristics, Freshwater Biomes - Terrestrial biomes, Marine biomes, Human-dominated biomes

A biome is a major, geographically extensive ecosystem, structurally characterized by its dominant life forms. Terrestrial biomes are usually distinguished on the basis of the major components of their mature or climax vegetation, while aquatic biomes, especially marine ones, are often characterized by their dominant animals. Most of the oceans are considered part of a single biome, although areas…

15 minute read

Biophysics

Biophysics is the integration and application of the principles of physics to explain and explore the form and function of living things. The most familiar examples of the role of physics in biology are the use of lenses to correct visual defects and the use of x rays to reveal the structure of bones. Principles of physics have been used to explain some of the most basic processes in biology such …

2 minute read

Bioremediation - Bioremediation Of Spilled Hydrocarbons, Bioremediation Of Metal Pollution, Bioremediation Of Acidification, Bioremediation Of Sewage

Bioremediation is a type of biotechnology in which living organisms or ecological processes are utilized to deal with some environmental problem. The most common use of bioremediation is to metabolically break down or otherwise remove toxic chemicals before or after they have been discharged into the environment. In such uses, bioremediation takes advantage of the fact that certain microorganisms …

1 minute read

Biotechnology

Biotechnology is the use of any technique involving living organisms to manufacture or change products, to improve the desired characteristics of a plant or animal, or to alter microorganisms for a purpose. Biotechnology has a long history. For example, yeast microorganisms were harnessed to prepare wine by Egyptians some 4,000 years before the birth of Christ. In 1865, Gregor Mendel presented his…

5 minute read

Bioterrorism

Bioterrorism is the use of a biological weapon against a civilian population. As with any form of terrorism, its purposes include the undermining of morale, creating chaos, or achieving political goals. Biological weapons use microorganisms and toxins to produce disease and death in humans, livestock, and crops. Biological, chemical, and nuclear weapons can all be used to achieve similar destructi…

6 minute read

Birch Family (Betulaceae)

The birch family is a group of flowering plants of tree or shrub form that includes the birches (Betula), alders (Alnus), hornbeams (Carpinus), and hazels (Corylus). Members of the birch family have simple and alternate leaves that bear appendages (stipules) where they join the branch. The leaves are also deciduous, generally thin and often doubly toothed along the margin. The flowers are densely …

5 minute read

Birds - Characterization

Birds are vertebrate animals in the class Aves. There are approximately 8,800 species of birds, divided among 28 living orders. Of these, slightly more than 900 species are found in North America. There has been considerable disagreement among ornithologists about the appropriate level for differentiating species, leading to multiple classification schemes. But however one distinguishes between sp…

12 minute read

Birds of Paradise - Description, Habitat And Diet, Habitat Loss - Mating behavior

The birds of paradise are some of the most fascinating birds in the world. This is due to the striking coloration of the males of most species, and the wide range of behaviors demonstrated in the group. Researchers of animal behavior are particularly interested in the elaborate mating displays performed by male birds of paradise. Birds of paradise are members of the family Paradisaeidae, which pro…

4 minute read

Birds of Prey

Birds of prey are predators that catch and eat other animals. These birds are called raptors (from the Latin rapere, meaning to snatch), a reference to their specialized, powerful feet, which are used to seize their prey. Raptorial birds eat birds, small mammals, reptiles, amphibians, fish, and large insects. Birds of prey are members of five avian families within the order Falconiformes. The Acci…

2 minute read

Birth - Viviparous Animals, Maternal Progesterone, Oxytocin, History Of Childbirth, Types Of Childbirth Preparation, Types Of Anesthesia - How does birth begin?, Fetal endocrine control, Birth in humans

Birth, or parturition, in mammals is the process in which a fully developed fetus is expelled from the mother's uterus by the force of strong, rhythmic muscle contractions. The birth of live offspring is a reproductive feature shared by mammals, some fishes, and selected invertebrates (such as scorpions), as well as some reptiles and amphibians. Animals who give birth to live offspring are …

5 minute read

Birth Defects - Causes of defects, Physical birth defects, Hereditary diseases and syndromes

Birth defects or congenital defects are present at birth. They result from heredity, environmental influences, or maternal illness. Such defects range from the very minor, such as a dark spot or birthmark that may appear anywhere on the body, to more serious conditions that may result in marked disfigurement, impaired functioning, or decreased lifespan. A number of factors individually or in combi…

17 minute read

Bison - America's Largest Mammal, Life In The Herd, The Continuing Generations, The Disappearing Bison

The American bison (Bison bison) is a large, herbivorous land mammal native to the grasslands and open forests of North America. It is a member of the family Bovidae, which also includes cattle, sheep, and goats. When French explorers first saw these large, shaggy, cow-like animals, they called them boeufs, the French word for "cattle." This later became anglicized into the word �…

1 minute read

Bitterns - Species Of Bitterns, Conservation Of Bitterns

Bitterns are about 12 species of wading birds in the subfamily Botaurinae of the family Ardeidae, which also includes herons and egrets. There are two genera: four species of the relatively large and stocky true bitterns (Botaurus spp.), and eight species of the much smaller and more slender, least bitterns (Ixobrychus). Bitterns have brown-and-black, vertically streaked plumage, which renders the…

1 minute read

Bivalves

Bivalve molluscks belong to the class Bivalvia (or Lamellibranchia) of the phylum Mollusca. Known by such common names as clams, mussels, cockles, oysters, and scallops, bivalves are among the most familiar aquatic invertebrates. They occur in large numbers in marine, estuarine, The life cycle of a typical freshwater clam. For species that do not have the parasitic larval stage, the fertilize…

3 minute read

BL Lacertae Object

BL Lacertae objects, abbreviated BL Lac, are one subclass of active galactic nuclei (AGN), the extremely energetic nuclei of active galaxies. Roughly 40 BL Lac objects are known. Perhaps the most obvious property of BL Lac objects is that they look like stars. Astronomers originally thought the prototype, BL Lac, was a star. In fact, BL Lacertae is normally a variable star designation, two letters…

1 minute read

Black Atlantic - Intellectual Antecedents, Intellectual Impact, Critiques, Bibliography

In writing The Black Atlantic: Modernity and Double Consciousness (1993), Paul Gilroy sought to devise a theoretical approach to understanding race that encompassed three crucial elements. First, the idea of race as fluid and ever-changing, rather than static; second, the idea of race as a transnational and intercultural, rather than strictly national, phenomenon; third, the focus on analyzing res…

2 minute read

Black Consciousness - Bibliography

Black consciousness is the name of a black nationalist political movement originating in South Africa during the 1960s and 1970s. It proclaimed the necessity of black South Africans to rely on themselves for liberation and to claim South Africa as an African nation. Black consciousness drew on a tradition of black nationalist thought in South Africa associated with Africanist political movements a…

9 minute read

Black Hole - The Event Horizon, Detection Of Black Holes, Centerpiece Of The Galaxy, Quantum Physics And Black Holes

A sufficiently intense gravitational field can prevent the escape not only of matter, but even of light. Such gravitational fields are produced by the bodies known as black holes. The maximum intensity of a spherical object's gravitational field is a function both of the amount of matter it contains and of its volume. The more matter is contained in an object and the smaller its volume …

1 minute read

Blackbody Radiation

The term blackbody radiation refers to electromagnetic radiation emitted by a completely opaque object. Such an object is referred to as a blackbody since it absorbs all of the radiation that falls on it and thus appears to be colorless, or black. According to Kirchoff's law, any object that qualifies as a blackbody must also be a perfect emitter of radiation. In fact, no real object fits t…

1 minute read

Blennies

Blennies are small, primarily tropical and subtropical marine fish. They are elongated and often eel-like in shape, with a dorsal fin running from the back of the head almost to the tail fin, and small abdominal fins; the pelvic fin is often completely absent. Many species also lack scales. The blenny's anatomy is well suited for hiding in cracks and crevices along shallow, rocky shorelines…

2 minute read

Blindness and Visual Impairments

Blindness is usually considered as an inability to see or a complete loss of vision, although legally, a blind person may retain some vision. In contrast, visual impairment indicates a loss of vision such that there is an impact on daily living, which usually implies partial loss of vision. There are many causes of visual impairment or blindness, and all parts of the eye (cornea, retina, lens, opt…

4 minute read

Blindsnakes

These tiny, primitive burrowers live underground and forage for ants, termites, soft-bodied insects, and insect larvae. The eyes of most blindsnakes are degenerate; they are covered by scales and do not function. However, the eyes do have light-sensitive cells (rods), so these snakes may not be completely blind. The head is large and the mouth, like a shark's, is below and behind the snout,…

2 minute read

Blood - Kinds Of Blood Found In The Animal Kingdom, Plasma - The composition of human blood, or blood cells Formed elements

Blood is a liquid connective tissue that performs many functions in the body, including transport of oxygen, Red blood cells alongside the wall of the blood vessel. Photograph by Dennis Kunkel. Phototake NYC. Reproduced by permission. carbon dioxide, nutrients, waste products, and hormones; clotting; and defense against microorganisms. Blood consists of formed elements, or blood cells su…

15 minute read

Blood Gas Analysis

Blood gas analysis is a means of determining the amount of oxygen or carbon dioxide being carried in the blood, and in some cases, of discovering the identity of a toxic gas, such as carbon monoxide, that may be present. Also, the determination can be made as to whether the blood is too acidic or too alkaline, which may help the physician in his diagnosis. Among other functions, blood carries oxyg…

1 minute read

Blood Supply - Donating Blood, Blood Components, Aids And The Blood Supply

Blood supply refers to the blood resources in blood banks and hospitals that are critical to the health care community. The blood supply consists of donated blood units (in pints) that are used to replace blood lost during surgery or from trauma. Blood transfusions were attempted as early as 1667 when Jean-Baptiste Denis, a French physician, transfused 12 fl oz (355 ml) of lamb's blood into…

less than 1 minute read

Blotting Analysis

Blotting analysis describes a series of techniques used to determine and describe protein and nucleic acid (e.g., DNA, RNA) sequences. Blotting analysis allows scientists to transfer electrophoretically separated components from a gel to a solid support. This support may then be used for probing with reagents specific for particular sequences of amino acids or nucleotides. In this way, the size an…

6 minute read

Blue Revolution (Aquaculture) - Aquaculture Production, Fish Farming, Invertebrate Culture, Environmental Impacts Of Aquaculture - Seaweed culture

The term "blue revolution" refers to the remarkable emergence of aquaculture as an important and highly productive agricultural activity. Aquaculture refers to all forms of active culturing of aquatic animals and plants, occurring in marine, brackish, or fresh waters. Aquaculture has long been practiced in China and other places in eastern Asia, where freshwater fish have been grown …

1 minute read

Bluebirds

Bluebirds are small blue-colored perching birds in the thrush family (Turdidae). There are three species of bluebirds in North America. All of these bluebirds nest in natural cavities or nest boxes. They tend to feed from perches, flying down to catch insects as they see them, and sometimes hawking insects in the air. The eastern bluebird (Sialia sialis) occurs in shrub-by habitats, old orchards, …

2 minute read

Boarfish

Boarfish is a common name, so it is not surprising that fish from two different marine families, from two different orders, with superficially similar snout-shaped faces share this name. One species that bears the common name boarfish comprises the few species of the genus Antigonia, which according to some experts is the only genus in the family Caprioidae. Others add the genus Capros to this fam…

1 minute read

Boas - True Boas, Sandboas (family Erycidae)

Boas are a group of nonvenomous, constricting snakes (family Boidae), most of which are found in tropical America and in Madagascar. Boas bear live young, and in this way they differ from the Old World pythons, which lay eggs. Boas are of ancient derivation, retaining some of the features of their lizard-like ancestors, such as paired lungs (modern snakes have only one), tiny remnants of hind limb…

1 minute read

The Body - A Brief Tour Of Western Dualism From Plato To Plastic Surgery, The Mind Embodied, Culturally Variable Bodies

What is "the body"? If the question seems ridiculous to you, you are undoubtedly not alone. At any given time, in any given culture, most people have an intuitive, if not always easy to articulate, notion of what the body is, and probably regard that notion as shared by all human beings. The fact is, however, that human cultures have not only done an amazing variety of things to huma…

1 minute read

Bohr Model

The Bohr model of atomic structure was developed by Danish physicist and Nobel laureate Niels Bohr (1885–1962). Published in 1913, Bohr's model improved the classical atomic models of physicists J. J. Thomson and Ernest Rutherford by incorporating quantum theory. While working on his doctoral dissertation at Copenhagen University, Bohr studied physicist Max Planck's quantum th…

5 minute read

Boiling Point

The boiling point of a liquid substance is the temperature at which the vapor pressure of the liquid equals the external pressure on the liquid. Vapor bubbles form in the liquid, rise to the surface and burst, causing the liquid to boil. At room temperature, in a closed system, there is an equilibrium between the liquid and its vapor phase. For example, if a glass of water is left open, the water …

2 minute read

Bond Energy

Bond energy is the strength of a chemical bond between atoms, expressed as the amount of energy required to break it apart. It is as if the bonded atoms were glued together: the stronger the glue is, the more energy would be needed to break them apart. A higher bond energy, therefore, means a stronger bond. Notice that ionic bonds are stronger than covalent bonds. Among covalent bonds, triple bond…

2 minute read

Bony Fish

Bony fish (Osteichthyes) are distinguished from other fish species that have a cartilaginous skeleton (Chondrichthyes—sharks, rays and chimaeras, for example) by the presence of true bone—a mixture of calcium phosphates and carbonates—in their skeletons. Other differences between the two groups are modifications in the structure and arrangement of the scales and fins and the p…

4 minute read

Boobies and Gannets - Species Of Gannets, Species Of Boobies, Boobies, Gannets, And People

Boobies and gannets are nine species of marine birds that make up the family Sulidae, in the order Pelecaniformes, which also includes the pelicans, cormorants, anhingas, tropic birds, and frigate birds. Boobies and gannets have a narrow, cigar-shaped body, a longish, pointed tail, and long, narrow wings. Their feet are fully webbed, and are used in swimming. The beak is strong, pointed, has a ser…

1 minute read

Boolean Algebra - Properties Of Sets, Properties Of Boolean Algebra, Applications

Boolean algebra is often referred to as the algebra of logic, because the English mathematician George Boole, who is largely responsible for its beginnings, was the first to apply algebraic techniques to logical methodology. Boole showed that logical propositions and their connectives could be expressed in the language of set theory. Thus, Boolean algebra is also the algebra of sets. Algebra, in g…

1 minute read