Science & Philosophy: Dependency - The Intellectual Roots Of Dependency Thinking to Dirac equation

Science Encyclopedia

Dependency - The Intellectual Roots Of Dependency Thinking, Radical Dependency Theorists, Reformist Dependency Theory, Critiques Of Dependency

During the 1960s and 1970s, Latin American dependency theorists produced an important challenge to modernization and growth theories of development. Associated with a number of key intellectuals from Latin America—Andre Gunder Frank, Fernando Henrique Cardoso, and Peter Evans in Latin America, Samir Amin and Walter Rodney in Africa—the dependentistas turned modernization theory upsid…

1 minute read

Deposit

A deposit is an accumulation of Earth materials, usually loose sediment or minerals, that is laid down by a natural agent. Deposits are all around you—the sand on the beach, the soil in your backyard, the rocks in a mountain stream. All of these consist of earth materials transported and laid down (that is, deposited) by a natural agent. These natural agents may include flowing water, ice, …

2 minute read

Depression

Depression is a psychoneurotic disorder characterized by lingering sadness, inactivity, and difficulty in thinking and concentration. A significant increase or decrease in appetite and time spent sleeping, feelings of dejection and hopelessness, and sometimes suicidal tendencies may also be present. It is one of the most common psychiatric conditions encountered, and affects up to 25% of women and…

2 minute read

Depth Perception - Retinal Disparity And Stereopsis, Development Of Depth Perception, Current Research/future Developments - Monocular cues, Binocular cues, Auditory depth cues

Depth perception is the ability to see the environment in three dimensions and to estimate the spatial distances of objects from ourself and from each other. Depth perception is vital for our survival, being necessary to effectively navigate around and function in the world. Without it we would be unable to tell how far objects are from us, and thus how far we would need to move to reach or avoid …

7 minute read

Desalination

Desalination, also called desalting, is the removal of salt from seawater. It provides essential water for drinking and industry in desert regions or wherever the local water supply is brackish. In 1991, about 3.5 billion gallons of desalinated water were produced in about 4,000 desalination plants worldwide. Most of this water was produced through distillation. However, other methods, including r…

2 minute read

Desert

A desert is an arid land area where more water is lost through evaporation than is gained from precipitation. Deserts include the familiar hot, dry desert of rock and sand that is almost barren of plants, the semiarid deserts of scattered trees, scrub, and grasses, coastal deserts, and the deserts on the polar ice caps of the Antarctic and Greenland. Most desert regions are the result of large-sca…

4 minute read

Desertification - The Sahelian Drought And United Nations Convention To Combat Desertification, Desertification In North America, Processes Of Desertification

Desertification is the gradual degradation of productive arid or semi-arid land into biologically unproductive land. The French botanist, André Aubreville, coined the term in 1949 to describe to the transformation of productive agricultural land in northern Africa to desert-like, uncultivable fallowland. Loss of biological and ecological viability occurs when natural variations, like extend…

2 minute read

Determinants

A determinant, signified by two straight lines ||, is a square array of numbers or symbols that has a specific value. For a square matrix, say, A, there exists an associated determinant, |A|, which has elements identical with the corresponding elements of the matrix. When matrices are not square, they do not possess corresponding determinants. For determinants of third order, that is, n = 3, or th…

3 minute read

Determinism - Is Determinism True?, Compatibilists And Incompatibilists, Recent Thinking, Bibliography

The most general idea is that all events without exception are just effects. This idea has been associated with science since the seventeenth century, but it was put in some doubt by an interpretation of quantum theory in physics at the beginning of the twentieth century. Events are things that happen. Roughly speaking, they are such occurrences as a chair having such a property as a particular lo…

4 minute read

Development - Aristotle On Development, Ideas Of Development In The Seventeenth And Eighteenth Centuries: Preformism And Epigenesis

Development in biology refers to the process of growth and differentiation that is characteristic of living organisms. It describes the continuous changes during the life cycle of individual organisms from the early stage of a single cell until death. Development also refers to what is today known as the process of evolution, the transformation of species through time. Other meanings of developmen…

1 minute read

Dew Point

The dew point is that temperature below which the water vapor in a body of air cannot all remain vapor. When a body of air is cooled to its dew point or below, some fraction of its water vapor shifts from gaseous to liquid phase to form fog or cloud droplets. If a smooth surface is available, vapor condenses directly onto it as drops of water (dew). The dew point of a body of air depends on its wa…

1 minute read

Diabetes Mellitus - Incidence Of Diabetes, Types Of Diabetes, Pre-diabetes, Tests For Diabetes, Treatment For Diabetes - History of diabetes

Diabetes mellitus is a group of diseases characterized by high levels of glucose in the blood resulting from defects in insulin production (insulin deficiency), insulin action (insulin resistance), or both. Insulin is a hormone produced by the pancreas. When eaten, foods are converted to a type of sugar called glucose that enters the bloodstream. Insulin is needed to move glucose into the body cel…

1 minute read

Diagnosis - Patient Information, The Physical Examination, The Laboratory Examination

Diagnosis, from gnosis, the Greek word for knowledge, is the process of identifying a disease or disorder in a person by examining the person and studying the results of medical tests. The diagnosis begins when the patient is presented to the doctor with a set of symptoms or perceived abnormalities such as pain, nausea, fever, or other untoward feeling. Often the diagnosis is relatively simple, an…

less than 1 minute read

Dialogue and Dialectics - Socratic - The Literature Of Socratic Conversations, The Socratic Dialogues Of Plato, Bibliography

The Greek noun dialogos derives from the verb dialegesthai, meaning "to enter into a conversation." The term dialectic, or the art of argumentation (dialectike techne), is derived from this verb as well, but in the case of Socratic dialectic the relevant Greek term is elegkhos (elenchus). Elenchus means a testing, and, since those tested by Socratic questioning are often shown inadeq…

less than 1 minute read

Dialogue and Dialectics - Talmudic - The Role Of Dialectics In The Bavli, An Example Of A Dialectical Argument, Talmudic Dialectics And Philosophical Dialectics

Dialectical argument is a tool of systematic analysis. In the Talmudic framework, everything is in the moving, or dialectical, argument, the give–and–take of unsparing rationality, which, through their own capacity to reason, later generations are expected to reconstitute. Following the argument as set forth in the Talmud affords access to the issues, the argument, and the prevailing…

1 minute read

Dialysis

Dialysis is a process by which small molecules in a solution are separated from large molecules. The principle behind the process was discovered by the Scottish chemist Thomas Graham in about 1861. Graham found that the rate at which some substances, such as inorganic salts, pass through a semipermeable membrane is up to 50 times as great as the rate at which other substances, such as proteins, do…

2 minute read

Diamond

Diamond is a mineral with the same carbon composition as graphite, but with different structure. Diamonds are formed in the compression of coal. Photograph by Rick Gayle. Stock Market. Reproduced by permission. Diamonds are a globally traded commodity used for a variety of industrial and artistic purposes. In December 2000, the United Nations General Assembly unanimously adopted a resolutio…

4 minute read

Diasporas - African Diaspora - Defining Diasporas, African Dispersals, African Diasporas In Asia And Europe, The Atlantic Diasporas, The New African Diasporas

The African diaspora, together with the Jewish diaspora—the etymological and epistemological source of the term diaspora—enjoys pride of place in the increasingly crowded pantheon of diaspora studies. Studies of African diasporas can be divided into two broad categories. First, there are those that discuss the patterns of dispersal of African peoples around the world and the kinds of…

1 minute read

Diasporas - Jewish Diaspora - Hellenism And The Jewish Diaspora, Interpretations Of The Jewish Diaspora, Diaspora In The Twenty-first Century

The Greek term diaspora, meaning "dispersion," has been used since ancient times as a means of describing the Jewish experience as well as the fact of Jewish settlement outside of the Jewish homeland to the present day. Originally, the term diaspora was used with respect to only three groups whose populations were dispersed in classical times: the Greeks, the Jews, and the Armenians.…

4 minute read

Diatoms

Algae are a very diverse group of simple, nucleated, plant-like aquatic organisms that are primary producers. Primary producers are able to utilize photosynthesis to create organic molecules from sunlight, water, and carbon dioxide. Ecologically vital, algae account for roughly half of photosynthetic production of organic material on earth in both freshwater and marine environments. Algae exist ei…

5 minute read

Dictatorship in Latin America - Bibliography

It is a somewhat common refrain in Latin America that countries need the mano dura (strong hand) of a military dictatorship in order to get things done. Surveys in the early twenty-first century reveal a growing disenchantment with civilian governments, with a surprisingly large minority of Latin Americans stating a preference for a dictatorial form of government over democracy. Such sentiments da…

5 minute read

Diesel Engine

Diesel engines are a class of internal combustion engine in which the fuel is burned internally and the combustion products are used as the working fluid. Unlike the spark-ignited (SI) engines found in the majority of today's automobiles in which the premixed fuel-air mixture is ignited by an electric spark, diesel engines are characterized by a spontaneously initiated combustion process wh…

5 minute read

Diffraction - Fundamentals, Applications

Diffraction is the deviation from a straight path that occurs when a wave such as light or sound passes around an obstacle or through an opening. The importance of diffraction in any particular situation depends on the relative size of the obstacle or opening and the wavelength of the wave that strikes it. The diffraction grating is an important device that makes use of the diffraction of light to…

5 minute read

Diffraction Grating

A diffraction grating is an optical device consisting of many closely spaced parallel lines or grooves. In a transmission type of grating, light passes through the narrow transparent slits that lie between the dark lines on a glass or plastic plate. In a reflecting grating, light is reflected by the many parallel, narrow, smooth surfaces and absorbed or scattered by the lines cut in the reflecting…

2 minute read

Digestive System - Ingestion, Digestion In The Stomach, Gastric Juice, Alexis St. Martin's Stomach

The digestive system is a group of organs responsible for the conversion of food into absorbable chemicals which are then used to provide energy for growth and repair. The digestive system is also known by a number of other names, including the gut, the digestive tube, the alimentary canal, the gastrointestinal (GI) tract, the intestinal tract, and the intestinal tube. The digestive system consist…

1 minute read

Digitalis - How Digitalis Is Used, Risks And Side Effects

Digitalis is a drug that has been used for centuries to treat heart disease. The active ingredient in the drug is glycoside, a chemical compound that contains a sugar molecule linked to another molecule. The glycoside compound can be broken down into a sugar and nonsugar compound. Though current digitalis drugs are synthetic, that is, man-made, early forms of the drug were derived from a plant. Di…

1 minute read

Dik-Diks - Habitat And Diet, Social Organization, Territorial Behavior

Dik-diks (genus Madoqua) are small (dog-sized) African antelopes belonging to the family of Bovidae, which includes cattle, sheep, and goats, as well as antelopes, gazelles, and impalas. Like all bovids, dik-diks have even-toed hooves, horns, and a four-chambered stomach. There are five species of dik-dik—Kirk's (the largest), Günther's, Salt's, Red-bellied, and …

less than 1 minute read

Dinosaur - Biology Of Dinosaurs, Fossils And Other Evidence Of The Dinosaurs, Major Groups Of Dinosaurs, Carnivorous Dinosaurs

Dinosaurs are a group of now-extinct, terrestrial reptiles in the order Dinosauria that lived from about 225 million years ago to 66 million years ago, during the Mesozoic era. Species of dinosaurs ranged from chicken-sized creatures such as the 2 lb (1 kg) predator Compsognathus to colossal, herbivorous animals known as "sauropods," which were larger than any terrestrial animals tha…

2 minute read

Diode

A diode is an electronic device that has two electrodes arranged in such a way that electrons can flow in only one direction. Because of this ability to control the flow of electrodes, a diode is commonly used as a rectifier, a device that connects alternating current into direct current. In general, two types of diodes exist. Older diodes were vacuum tubes containing two metal components, while n…

2 minute read

Diphtheria - Incidence Of Diphtheria, Diphtheria Toxin, Symptoms, Treatment, Vaccine

Diphtheria is a serious disease caused by the bacterium Corynebacterium diptheriae. Usually, the bacteria initially infect the throat and pharynx. During the course of the infection, a membrane-like growth appearing on the throat can obstruct breathing. Some strains of this bacterium release a toxin, a substance that acts as a poison in the body. This toxin, when released into the bloodstream, tra…

less than 1 minute read

Dipole

Dipole, literally, means "two poles," two electrical charges, one negative and one positive. Dipoles are common in atoms whenever electrons (-) are unevenly distributed around nuclei (+), and in molecules whenever electrons are unevenly shared between two atoms in a covalent bond. When a dipole is present, the atom or covalent bond is said to be polarized, or divided into negative an…

2 minute read