Science & Philosophy: Categorical judgement to Chimaera

Science Encyclopedia

Catfish

Catfish include some 2,500 species of mostly freshwater fish characterized by two to four pairs of whiskers or barbels around their mouth. Many species have spines on the dorsal fins and near the gills. In some species these spines may contain poison. Catfish belong to the bony fish order Siluriformes, and are mainly freshwater forms with representatives throughout the world. Most species of catfi…

4 minute read

Catheters

Catheters are long, flexible tubes that are inserted into the body for various purposes, either to remove an unwanted substance or to instill nourishment or medication. A relatively large catheter can be passed through the nose, down the throat and into the stomach to remove the contents of the stomach; for example, if someone has consumed a poisonous substance, a catheter can be used to remove a …

1 minute read

Cathode

The cathode is one of the two electrodes that are present in any system in which electricity is entering and leaving a region; the other electrode is called the anode. The electric current enters through one of the electrodes and leaves through the other. Two general kinds of systems employ electrodes: vacuum tubes (also called gas discharge tubes) and electrochemical cells. In a vacuum tube, the …

1 minute read

Cation

A cation is any atom or group of atoms that has a net positive charge. While matter is electrically neutral overall, ionic compounds are matter that is composed of positively-charged and negatively-charged particles called ions. An ion is any atom or group of atoms with an overall electrical charge. According to the laws of physics, opposite charges attract, so the oppositelycharged ions attract e…

1 minute read

Cats - Senses, Behavior, Evolution And History, Domestic Cats - Species of big cats

Cats are mammals in the family Felidae of the order Carnivora, which includes all of the carnivores. The highly predatory instincts of species in the cat family are easily seen in domestic cats, for even well-fed individuals will aggressively hunt small mammals and birds. The cat family includes both large species (jaguar, leopard, lion, and tiger) and small ones (bobcat, lynx, ocelot, and serval)…

7 minute read

Cattails

Cattails or reedmaces are about 10 species of monocotyledonous plants in the genus Typha, comprising the family Typhaceae. Cattails are tall, herbaceous, aquatic plants, growing from stout rhizomes located in shallow sediments of wetlands. The leaves of cattails are long and strap-like, sheathing at the base of the plant, while the spike-like inflorescence is borne by a long cylindrical shoot. The…

2 minute read

Cattle Family (Bovidae)

The cattle family, Bovidae, is a widespread group of mammals which also includes the goats, sheep, gazelles, antelopes, and goat-antelopes. Of the 107 species currently recognized within this family, just 12 are wild cattle. Even the large muskox (Ovibos moschatus), which looks quite cow-like, is more closely related to the goats than to cattle. Cattle are generally characterized by their large si…

15 minute read

Causation - Modern Theories Of Causation, The 1970s And Early 1980s: The Age Of Causal Analyses, Event Causation Versus Causal Generalizations

Philosophers have theorized about causation since well before Aristotle, who distinguished several types of causation: efficient, material, final, and formal. For example, a wood carving is made by an artist (the efficient cause) by chiseling a piece of wood (the material cause) for the purpose of creating a beautiful object (the final cause), arriving at something that has the properties of a woo…

2 minute read

Cauterization - History, Other applications

Cauterization is the application of heat, mechanically or chemically, to prevent or stop bleeding. It is widely used in surgery to hold bleeding to a minimum and speed the surgical process. Birthmark removal by cauterization with an argon laser. Photograph by Alexander Tsiaras. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. Searing areas of bleeding wi…

2 minute read

Cave - Cave Types, Cave Environment And Formations, Cave Life

A cave is a naturally occurring hollow area inside the earth. Most caves are formed by some type of erosional process. The most notable exception is hollow lava tubes such as those in Hawaii. The formation of caves depends upon geologic, topographic, and hydrologic factors. These factors determine where and how caves develop, as well as their structure and shape. The study of caves is called spele…

2 minute read

Cave Fish

Many species of fish have evolved to living under strange conditions, but few are more intriguing than those that have adapted to living in complete darkness. Some of these fish have developed a tendency to live at great depths in the ocean where no light penetrates, while others have found refuge in equally dim locations such as caves, wells, and subterranean streams. This specialization to livin…

4 minute read

Celestial Coordinates - Horizon Coordinates, Celestial Latitude B, Galactic Longitude - Equatorial coordinates, Right ascension a, Declination d, Hour angle, Ecliptic coordinate, Celestial longitude l

Celestial coordinates locate objects on the sky, which is considered to be an infinitely large (celestial) sphere. The four conventional celestial coordinate systems are defined. These are based on the earth's rotation, which produces an apparent westward rotation of the celestial sphere around the NCP and SCP. An object's arc distance along its hour circle from the celestial equator…

1 minute read

Celestial Mechanics - Planetary Perturbations, Resonance Phenomena, Tidal Effects, Precession, Non-gravitational Effects, The Three-body Problem

Modern celestial mechanics began with Isaac New ton's generalization of Kepler's laws published in his Principia in 1687. Newton used his three laws of motion and his law of universal gravitation to do this. The three generalized Kepler's law are: where G is the Newtonian gravitations factor, and from his second law of motion, Newton derived the following general form of …

1 minute read

Celestial Sphere: The Apparent Motions of the Sun, Moon, Planets, and Stars

The celestial sphere is an imaginary projection of the Sun, Moon, planets, stars, and all astronomical bodies upon an imaginary sphere surrounding Earth. The celestial sphere is a useful mapping and tracking remnant of the geocentric theory of the ancient Greek astronomers. Although originally developed as part of the ancient Greek concept of an Earth-centered universe (i.e., a geocentric model of…

11 minute read

Cell - Types Of Cells, Prokaryotes And Eukaryotes, Cell Size And Numbers, The Structure And Function Of Cells - The structure of eukaryotes, Plant organelles, Vacuoles, Cell wall

The cell is the smallest living component of organisms and is the basic unit of life. In multicellular living things, a collection of cells that work together to perform similar functions is called a tissue; various tissues that perform coordinated functions form organs; and organs that work together to perform general processes form body systems. The human digestive system, for example, is compos…

6 minute read

Cell Death

Like all living things, the various types of cells in plants, animals, and the many different cell types in humans must eventually die. Cell death occurs in one of two ways. Cells can be killed by the effects of physical, biological, or chemical injury. Additionally, cells are induced to kill themselves. Cell suicide is also referred to as apoptosis (from the Greek words apo, meaning from, and pto…

3 minute read

Cell Division - Eukaryotic cell division

Cell division is the process where a single living cell splits to become two or more distinct new cells. All cells divide at some point in their lives. Cell division occurs in single-celled organisms like bacteria, in which it is the major form of reproduction (binary fission), or in multicellular organisms like plants, animals, and fungi. Many cells continually divide, such as the cells that line…

8 minute read

Electrochemical Cell - Chemistry And Electricity, Voltaic Cells, Electrolytic Cells

Electrochemical cells are devices based on the principle that when a chemical oxidation-reduction reaction takes place, electrons are being transferred from one chemical species to another. In one type of electrochemical cell called a voltaic or galvanic cell, these electrons are deliberately taken outside the cell and made to flow through an electric circuit to operate some kind of electrical dev…

less than 1 minute read

Cell Membrane Transport

The cell is bound by an outer membrane that, in accord with the fluid mosaic model, is comprised of a phospholipid lipid bilayer with proteins—molecules that also act as receptor sites—interspersed within the phospholipid bilayer. Varieties of channels exist within the membrane. There are a number of internal cellular membranes that partially partition the intercellular matrix, and t…

5 minute read

Cell Staining - Staining Techniques, Standardization Of Tests

Medical science depends on the staining of cells in tissues to make accurate diagnoses of a wide range of diseases from cholera to sexually transmitted diseases, to parasitic diseases and skin infections. Staining techniques performed routinely in microbiological laboratories include gram's stain, acid-fast stains, acridine orange, calcofluor white, toluidine blue, methylene blue, silver st…

1 minute read

Cellular Respiration

Respiration occurs in three stages. The first stage is glycolysis, which is a series of enzyme-controlled reactions that degrades glucose (a 6-carbon molecule) to pyruvate (a 3-carbon molecule) which is further oxidized to acetylcoenzyme A (acetyl CoA). Amino acids and fatty acids may also be oxidized to acetyl CoA as well as glucose. During electron transport, much of the energy represented by th…

6 minute read

Cellular Telephone

Cellular telephone technology is also called cellular radio. The cellular radio network became fully operational in North America in 1978. This technology relies on the distribution of what are called cell sites over a wide geographical area. Each cell site consists of a radio transceiver and a controller that sends and receives signals from the mobile phones in the area to a telephone switch. The…

5 minute read

Censorship - Blasphemy, Heresy, And Atheism, Political Subversion, The Netherlands And England, From Bayle To Constant

Censorship comprises many methods of preventing the publication or dissemination of speech, printed matter, art, theater, music, electronic media, or other forms of expression. The most common subjects that are censored are religion, politics, and sex. The usual justification is that such expression is subversive, blasphemous, heretical, obscene, pornographic, or otherwise offensive or harmful. Ce…

2 minute read

Centipedes

Centipedes (phylum Arthropoda, class Chilopoda) occur throughout the world in both temperate and tropical regions where they live in soil and humus and beneath fallen logs, bark, and stones. Because they lack a hard outer skeleton, centipedes are confined to moist environments in order to maintain water balance. Many species are therefore active only at night, remaining sheltered during the day. M…

4 minute read

Centrifuge - Types Of Centrifuges, Rotating Centrifuges, Applications Of The Rotating Centrifuge, Centrifuge Studies In The Space Sciences

A centrifuge is a device for separating two or more substances from each other by using centrifugal force. Centrifugal force is the tendency of an object traveling around a central point to continue in a linear motion and fly away from that central point. Centrifugation can be used to separate substances from each other becausematerials with different masses experience different centrifugal forces…

1 minute read

Ceramics - Traditional Ceramics, Glass, Aluminum Oxide, Silicon Carbide, Silicon Nitride, Processing, Forming Processes - Hydraulic cement, Modern ceramics, Magnesium oxide, Sintering, Machining

Ceramic materials are usually understood to be compounds of metallic and nonmetallic elements, though some are actually ionic salts, and others are insulators. These materials can be very complicated, as are for example clays, spinels, and common window glass. Many ceramic compounds have very high melting points. Ceramics have a wide range of applications. They have been used as refractories, abra…

2 minute read

Cerenkov Effect

The Cerenkov effect is the emission of light from a transparent substance like water or glass when a charged particle, such as an electron, travels through the material with a speed faster than the speed of light in that material. The Cerenkov effect was discovered by Russian experimentalist P. A. Cerenkov in 1934 and explained by Russian theorists I. Y. Tamm and I. M. Frank. All three scientists …

2 minute read

Cetaceans - Mysticeti: Baleen Whales, Odontoceti: Toothed Whales, Anatomy And Physiology, Sensory Perception, Social Behavior

Modern biologists believe that life first appeared in the sea; from these marine beginnings, land-dwelling organisms such as mammals gradually evolved. Cetaceans have returned to the marine environment after an ancestral period on land. As evidence of their terrestrial pedigree, consider that a whale fetus possesses four limb buds, a pelvis, tail, and forelimbs with five fingers like any land mamm…

1 minute read

Chachalacas

Chachalacas, curassows, and guans are 42 species of birds that make up the family Cracidae. These birds are in the order Galliformes, which also includes the grouse, pheasants, quail, guinea fowl, and turkey. Curassows, chachalacas, and guans (or cracids) are believed to represent a relatively ancient and primitive lineage within this order. Fossil members of this family are known from deposits in…

1 minute read

Chaos - Revising The Newtonian World View, Current Research, Chaos May Depend On Initial Conditions And Attractors

Chaos theory is used to model the overall behavior of complex systems. Despite its name, chaos theory is used to identify order in complex and otherwise seemingly unpredictable systems. Chaos theory is used to understand explosions, complex chemical reactions (e.g., the Belousov-Zhabotinsky oscillating reaction that yields a red solution that turns blue at varying intervals of time), and many biol…

1 minute read

Chelate

A chelate is a type of coordination compound in which a single metallic ion is attached by coordinate covalent bonds to a molecule or an ion called a ligand. The term chelate comes from the Greek word chela, meaning "crab's claw." The term clearly describes the appearance of many kinds of chelates, in which the ligand surrounds the central atom in a way that can be compared to…

1 minute read

Chemical Evolution - The primitive Earth

Chemical evolution describes chemical changes on the primitive Earth that gave rise to the first forms of life. The first living things on Earth were prokaryotes with a type of cell similar to present-day bacteria. Prokaryote fossils have been found in 3.4-million-year-old rock in the southern part of Africa, and in even older rocks in Australia, including some that appear to be photosynthetic. Al…

5 minute read

Chemical Oxygen Demand

Chemical oxygen demand is related to biochemical oxygen demand (BOD), another standard test for assaying the oxygen-demanding strength of waste waters. However, biochemicaloxygen demand only measures the amount of oxygen consumed by microbial oxidation and is most relevant to waters rich in organic matter. It is important to understand that COD and BOD do not necessarily measure the same types of …

1 minute read

Chemical Reactions

Chemical reactions describe the changes between reactants (the initial substances that enter into the reaction) and products (the final substances that are present at the end of the reaction). Describing interactions among chemical species, chemical reactions involve a rearrangement of the atoms in reactants to form products with new structures in such a way as to conserve atoms. Chemical equation…

8 minute read

Chemical Warfare - Antipersonnel Agents—chemicals Used Against People, Use Of Herbicides During The Vietnam War, Use Of Petroleum As A Weapon During The Gulf War

Chemical warfare involves the use of natural or synthetic substances to incapacitate or kill an enemy or to deny them the use of resources such as agricultural products or screening foliage. The effects of the chemicals may last only a short time, or they may result in permanent damage and death. Most of the chemicals used are known to be toxic to humans or plant life. Other normally benign (mild)…

2 minute read

Chemistry

Chemistry is the science that studies why materials have their characteristic properties, how these particular qualities relate to their simplest structure, and how these properties can be modified or changed. The term chemistry is derived from the word alchemist, which finds its roots in the Arabic name for Egypt al-Kimia. The Egyptians are credited with being the first to study chemistry. They d…

5 minute read

Chemistry - Alchemy In The Scientific Revolution, Eighteenth-century Cultures Of Chemistry, From Phlogiston To Oxygen

Where and when did chemistry originate? Some chemists would identify ancient Egypt as the birthplace of chemistry because of that culture's glassworks, cosmetics, and mummification techniques. Advocates of this theory might also refer to a possible etymology of the word chemistry from the Egyptian word for black. Other historians place the origins of chemistry amid ancient Greek theories of…

1 minute read

Chemoreception

Chemoreception is the biological recognition of chemical stimuli, by which living organisms collect information about the chemistry of their internal and external environments. Chemoreception has three sequential stages: detection, amplification, and signaling. In detection, a molecule typically binds to a chemoreceptor protein on the surface of a cell, changing the shape of the chemoreceptor. All…

2 minute read

Chestnut - The Sweet Chestnut, The American Chestnut - Other chestnuts

Chestnuts are species of trees in the genus Castanea, family Fagaceae. They are species of temperate hardwood (angiosperm-dominated) forests found in the Northern Hemisphere and are indigenous to eastern North America and Eurasia. Species in the genus Castanea can grow to be 100 ft (30 m) tall. They have simple leaves with a broadly toothed margin and sweet-smelling, yellowish, insect-pollinated, …

1 minute read

Chi-Square Test

A chi-square analysis is best illustrated using an example in which data from a population is categorized with respect to two qualitative variables. Table 1 shows a sample of patients categorized with respect to two qualitative variables, namely, congenital heart defect (CHD; present or absent) and karyotype (trisomy 21, also called Down syndrome, or trisomy 13, also called Patau syndrome). The cl…

6 minute read

Chicano Movement - Contents, Cultural Context, Ideology, Gender, Universalism, Problems And Achievements, Conclusion, Bibliography

Between 1966 and 1977, members of the Mexican-American community engaged in a period of widespread political activism akin to other civil rights and antiwar movements of the 1960s. The resulting challenges and concurrent mentalities became the Chicano movement, or as it is now known in recognition of the equally important participation of Chicanas, the Chicana/o movement. During this period large-…

3 minute read

Chickenpox - Symptoms Of Chickenpox, Treatment, Complications, Chickenpox And Environmental Factors, Immunity And The New Vaccine

Chickenpox, a disease characterized by skin lesions and low-grade fever, is common in the United States and other countries located in areas with temperate climates. The incidence of chickenpox is extremely high-almost everyone living in the United States contracts chicken-pox, usually during childhood, but sometimes in adulthood. In the United States, about 3.9 million people a year contract chic…

1 minute read

Childhood Diseases - Other Infectious Childhood Diseases, Poliomyelitis, Noncontagious Childhood Diseases, Congenital Diseases - Contagious diseases

Diseases that are more common among children than among adults are referred to as childhood diseases. That is not to say that adults cannot or will not contract these illnesses; but usually children contract these diseases and form the immunity against them that will protect them as adults. In fact, some of these diseases may be quite uncomplicated in children, but may be life-threatening when con…

12 minute read