Burn

A burn is an injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or ultraviolet radiation (like sunburn). 　Most burns are due to heat from hot liquids (called scalding), solids, or fire. 　Burns occur mainly in the home or the workplace. 　In the home, risks are associated with domestic kitchens, including stoves, flames, and hot liquids. 　In the workplace, risks are associated with fire and chemical and electric burns. 　Alcoholism and smoking are other risk factors. 　Burns can also occur as a result of self-harm or violence between people (assault). 　Burns that affect only the superficial skin layers are known as superficial or first-degree burns. 　They appear red without blisters and pain typically lasts around three days. 　When the injury extends into some of the underlying skin layer, it is a partial-thickness or second-degree burn. 　Blisters are frequently present and they are often very painful. 　Healing can require up to eight weeks and scarring may occur. 　In a full-thickness or third-degree burn, the injury extends to all layers of the skin. 　Often there is no pain and the burnt area is stiff. 　Healing typically does not occur on its own. 　A fourth-degree burn additionally involves injury to deeper tissues, such as muscle, tendons, or bone. 　The burn is often black and frequently leads to loss of the burned part. 　Burns are generally preventable. 　Treatment depends on the severity of the burn. 　Superficial burns may be managed with little more than simple pain medication, while major burns may require prolonged treatment in specialized burn centers. 　Cooling with tap water may help pain and decrease damage; however, prolonged cooling may result in low body temperature. 　Partial-thickness burns may require cleaning with soap and water, followed by dressings. 　It is not clear how to manage blisters, but it is probably reasonable to leave them intact if small and drain them if large. 　Full-thickness burns usually require surgical treatments, such as skin grafting. 　Extensive burns often require large amounts of intravenous fluid, due to capillary fluid leakage and tissue swelling. 　The most common complications of burns involve infection. 　Tetanus toxoid should be given if not up to date. 　In 2015, fire and heat resulted in 67 million injuries. 　This resulted in about 2.9 million hospitalizations and 176,000 deaths. 　Among women in much of the world, burns are most commonly related to the use of open cooking fires or unsafe cook stoves. 　Among men, they are more likely a result of unsafe workplace conditions. 　Most deaths due to burns occur in the developing world, particularly in Southeast Asia. 　While large burns can be fatal, treatments developed since 1960 have improved outcomes, especially in children and young adults. 　In the United States, approximately 96% of those admitted to a burn center survive their injuries. 　The long-term outcome is related to the size of burn and the age of the person affected.

Scenario

In the performing arts, a scenario (/sɪˈnɑːri.oʊ/, US also /sɪˈnɛəri.oʊ, -ˈnær-/; Italian: [ʃeˈnaːrjo]; from Italian scenario 'that which is pinned to the scenery') is a synoptical collage of an event or series of actions and events. 　In the commedia dell'arte, it was an outline of entrances, exits, and action describing the plot of a play, and was literally pinned to the back of the scenery. 　It is also known as canovaccio or "that which is pinned to the canvas" of which the scenery was constructed. 　Surviving scenarios from the Renaissance contain little other than character names, brief descriptions of action, and references to specific lazzi with no further explanation. 　It is believed that a scenario formed the basis for a fully improvisational performance, though it is also likely that they were simple reminders of the plot for those members of the cast who were literate. 　Modern commedia troupes most often make use of a script with varying degrees of additional improvisation. 　In the creation of an opera or ballet, a scenario is often developed initially to indicate how the original source, if any, is to be adapted and to summarize the aspects of character, staging, plot, etc. that can be expanded later in a fully developed libretto, or script. 　This sketch can be helpful in "pitching" the idea to a prospective producer, director or composer. 　In the filmmaking of the early 20th century, film scenarios (also called "treatments" or "synopses") were short written scripts to provide narrative coherence that had previously been improvised. 　They could consist of a simple list of scene headings or scene headings with a detailed explication of the action in each scene. 　At this time in the silent era, scripts had yet to include individual shots or dialogue. 　These scenario scripts evolved into lengthier continuity scripts, which listed a number of shots within each scene, thus providing continuity to streamline the filmmaking process.

Entropy

Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. 　The term and the concept are used in diverse fields, from classical thermodynamics, where it was first recognized, to the microscopic description of nature in statistical physics, and to the principles of information theory. 　It has found far-ranging applications in chemistry and physics, in biological systems and their relation to life, in cosmology, economics, sociology, weather science, climate change, and information systems including the transmission of information in telecommunication. 　The thermodynamic concept was referred to by Scottish scientist and engineer William Rankine in 1850 with the names thermodynamic function and heat-potential. 　In 1865, German physicist Rudolf Clausius, one of the leading founders of the field of thermodynamics, defined it as the quotient of an infinitesimal amount of heat to the instantaneous temperature. 　He initially described it as transformation-content, in German Verwandlungsinhalt, and later coined the term entropy from a Greek word for transformation. 　Referring to microscopic constitution and structure, in 1862, Clausius interpreted the concept as meaning disgregation. 　A consequence of entropy is that certain processes are irreversible or impossible, aside from the requirement of not violating the conservation of energy, the latter being expressed in the first law of thermodynamics. 　Entropy is central to the second law of thermodynamics, which states that the entropy of isolated systems left to spontaneous evolution cannot decrease with time, as they always arrive at a state of thermodynamic equilibrium, where the entropy is highest. 　Austrian physicist Ludwig Boltzmann explained entropy as the measure of the number of possible microscopic arrangements or states of individual atoms and molecules of a system that comply with the macroscopic condition of the system. 　He thereby introduced the concept of statistical disorder and probability distributions into a new field of thermodynamics, called statistical mechanics, and found the link between the microscopic interactions, which fluctuate about an average configuration, to the macroscopically observable behavior, in form of a simple logarithmic law, with a proportionality constant, the Boltzmann constant, that has become one of the defining universal constants for the modern International System of Units (SI). 　In 1948, Bell Labs scientist Claude Shannon developed similar statistical concepts of measuring microscopic uncertainty and multiplicity to the problem of random losses of information in telecommunication signals. 　Upon John von Neumann's suggestion, Shannon named this entity of missing information in analogous manner to its use in statistical mechanics as entropy, and gave birth to the field of information theory. 　This description has been identified as a universal definition of the concept of entropy.

Tourism

Tourism is travel for pleasure or business, and the commercial activity of providing and supporting such travel. 　The World Tourism Organization defines tourism more generally, in terms which go "beyond the common perception of tourism as being limited to holiday activity only", as people "travelling to and staying in places outside their usual environment for not more than one consecutive year for leisure and not less than 24 hours, business and other purposes". 　Tourism can be domestic (within the traveller's own country) or international, and international tourism has both incoming and outgoing implications on a country's balance of payments. 　Tourism numbers declined as a result of a strong economic slowdown (the late-2000s recession) between the second half of 2008 and the end of 2009, and in consequence of the outbreak of the 2009 H1N1 influenza virus, but slowly recovered until the COVID-19 pandemic put an abrupt end to the growth. 　The United Nations World Tourism Organization estimated that global international tourist arrivals might decrease by 58% to 78% in 2020, leading to a potential loss of US$0.9–1.2 trillion in international tourism receipts. 　Globally, international tourism receipts (the travel item in balance of payments) grew to US$1.03 trillion (€740 billion) in 2005, corresponding to an increase in real terms of 3.8% from 2010. 　International tourist arrivals surpassed the milestone of 1 billion tourists globally for the first time in 2012. 　Emerging source markets such as China, Russia, and Brazil had significantly increased their spending over the previous decade. 　Global tourism accounts for c. 　8% of global greenhouse-gas emissions. 　Emissions as well as other significant environmental and social impacts are not always beneficial to local communities and their economies. 　For this reason, many tourist development organizations have begun to focus on sustainable tourism to mitigate the negative effects caused by the growing impact of tourism. 　The United Nations World Tourism Organization emphasized these practices by promoting tourism as part of the Sustainable Development Goals, through programs like the International Year for Sustainable Tourism for Development in 2017, and programs like Tourism for SDGs focusing on how SDG 8, SDG 12 and SDG 14 implicate tourism in creating a sustainable economy. 　Tourism has reached new dimensions with the emerging industry of space tourism as well as the current industry with cruise ships, there are many different ways of tourism. 　Another potential new tourism industry is virtual tourism.

Warriors (anthology)

Warriors is a cross-genre, all-original fiction anthology featuring stories on the subjects of war and warriors; it was edited by George R. R. Martin and Gardner Dozois. 　The book's Introduction, "Stories from the Spinner Rack", was written by Martin. 　This anthology was first published in hardcover by Tor Books on March 16, 2010. 　It won a Locus Award for Best Anthology in 2011. 　The book was later split and republished in paperback as Warriors 1 (ISBN 9780765360267, published in 2010); Warriors 2 (ISBN 9780765360274, published in 2011) and Warriors 3 (ISBN 9780765360281, also published in 2011). 　Stories from the Spinner Rack is included in all the three split books.

Baron

Baron is a rank of nobility or title of honour, often hereditary, in various European countries, either current or historical. 　The female equivalent is baroness. 　Typically, the title denotes an aristocrat who ranks higher than a lord or knight, but lower than a viscount or count. 　Often, barons hold their fief – their lands and income – directly from the monarch. 　Barons are less often the vassals of other nobles. 　In many kingdoms, they were entitled to wear a smaller form of a crown called a coronet. 　The term originates from the Latin term barō, via Old French. 　The use of the title baron came to England via the Norman Conquest of 1066, then the Normans brought the title to Scotland and Italy. 　It later spread to Scandinavia and Slavic lands.

Cattle

Cattle (Bos taurus) are large, domesticated, cloven-hooved, herbivores. 　They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus Bos. 　Adult females are referred to as cows and adult males are referred to as bulls. 　Cattle are commonly raised as livestock for meat (beef or veal, see beef cattle), for milk (see dairy cattle), and for hides, which are used to make leather. 　They are used as riding animals and draft animals (oxen or bullocks, which pull carts, plows and other implements). 　Another product of cattle is their dung, which can be used to create manure or fuel. 　In some regions, such as parts of India, cattle have significant religious significance. 　Cattle, mostly small breeds such as the Miniature Zebu, are also kept as pets. 　Different types of cattle are common to different geographic areas. 　Taurine cattle are found primarily in Europe and temperate areas of Asia, the Americas, and Australia. 　Zebus (also called indicine cattle) are found primarily in India and tropical areas of Asia, America, and Australia. 　Sanga cattle are found primarily in sub-Saharan Africa. 　These types (which are sometimes classified as separate species or subspecies) are further divided into over 1,000 recognized breeds. 　Around 10,500 years ago, taurine cattle were domesticated from as few as 80 wild aurochs progenitors in central Anatolia, the Levant and Western Iran. 　A separate domestication event occurred in the Indian subcontinent, which gave rise to zebu. 　According to the Food and Agriculture Organization (FAO), there are approximately 1.5 billion cattle in the world as of 2018. 　Cattle are the main source of greenhouse gas emissions from livestock, and are responsible for around 10% of global greenhouse gas emissions. 　In 2009, cattle became one of the first livestock animals to have a fully mapped genome.

Fraction

A fraction (from Latin: fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. 　When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, three-quarters. 　A common, vulgar, or simple fraction (examples: 1 2 {\displaystyle {\tfrac {1}{2}}} and 17 3 {\displaystyle {\tfrac {17}{3}}} ) consists of a numerator, displayed above a line (or before a slash like 1⁄2), and a non-zero denominator, displayed below (or after) that line. 　Numerators and denominators are also used in fractions that are not common, including compound fractions, complex fractions, and mixed numerals. 　In positive common fractions, the numerator and denominator are natural numbers. 　The numerator represents a number of equal parts, and the denominator indicates how many of those parts make up a unit or a whole. 　The denominator cannot be zero, because zero parts can never make up a whole. 　For example, in the fraction 3/4, the numerator 3 indicates that the fraction represents 3 equal parts, and the denominator 4 indicates that 4 parts make up a whole. 　The picture to the right illustrates 3/4 of a cake. 　A common fraction is a numeral which represents a rational number. 　That same number can also be represented as a decimal, a percent, or with a negative exponent. 　For example, 0.01, 1%, and 10−2 are all equal to the fraction 1/100. 　An integer can be thought of as having an implicit denominator of one (for example, 7 equals 7/1). 　Other uses for fractions are to represent ratios and division. 　Thus the fraction 3/4 can also be used to represent the ratio 3:4 (the ratio of the part to the whole), and the division 3 ÷ 4 (three divided by four). 　The non-zero denominator rule, which applies when representing a division as a fraction, is an example of the rule that division by zero is undefined. 　We can also write negative fractions, which represent the opposite of a positive fraction. 　For example, if 1/2 represents a half-dollar profit, then −1/2 represents a half-dollar loss. 　Because of the rules of division of signed numbers (which states in part that negative divided by positive is negative), −1/2, −1/2 and 1/−2 all represent the same fraction – negative one-half. 　And because a negative divided by a negative produces a positive, −1/−2 represents positive one-half. 　In mathematics the set of all numbers that can be expressed in the form a/b, where a and b are integers and b is not zero, is called the set of rational numbers and is represented by the symbol Q, which stands for quotient. 　A number is a rational number precisely when it can be written in that form (i.e., as a common fraction). 　However, the word fraction can also be used to describe mathematical expressions that are not rational numbers. 　Examples of these usages include algebraic fractions (quotients of algebraic expressions), and expressions that contain irrational numbers, such as 2 2 {\textstyle {\frac {\sqrt {2}}{2}}} (see square root of 2) and π/4 (see proof that π is irrational).

Gospel

Gospel originally meant the Christian message ("the gospel"), but in the 2nd century it came to be used also for the books in which the message was set out. 　In this sense a gospel can be defined as a loose-knit, episodic narrative of the words and deeds of Jesus, culminating in his trial and death and concluding with various reports of his post-resurrection appearances. 　Modern scholars are cautious of relying on the gospels uncritically, but nevertheless, they provide a good idea of the public career of Jesus, and critical study can attempt to distinguish the original ideas of Jesus from those of the later authors. 　The four canonical gospels were probably written between AD 66 and 110. 　All four were anonymous (with the modern names added in the 2nd century), almost certainly none were by eyewitnesses, and all are the end-products of long oral and written transmission. 　Mark was the first to be written, using a variety of sources. 　The authors of Matthew and Luke both independently used Mark for their narrative of Jesus's career, supplementing it with a collection of sayings called the Q source and additional material unique to each. 　There is near-consensus that John had its origins as the hypothetical Signs Gospel thought to have been circulated within a Johannine community. 　The contradictions and discrepancies between the first three and John make it impossible to accept both traditions as equally reliable. 　Many non-canonical gospels were also written, all later than the four canonical gospels, and like them advocating the particular theological views of their various authors. 　Important examples include the gospels of Thomas, Peter, Judas, and Mary; infancy gospels such as that of James (the first to introduce the perpetual virginity of Mary); and gospel harmonies such as the Diatessaron.

Gabriel

In Abrahamic religions (Judaism, Christianity and Islam), Gabriel (/ˈɡeɪbriəl/ GAY-bree-əl) is an archangel with power to announce God's will to men. 　He is mentioned in the Hebrew Bible, the New Testament, and the Quran. 　Many Christian traditions — including Anglicanism, Eastern Orthodoxy, and Roman Catholicism — revere Gabriel as a saint. 　In the Hebrew Bible, Gabriel appears to the prophet Daniel to explain his visions (Daniel 8:15–26, 9:21–27). 　The archangel also appears in the Book of Enoch and other ancient Jewish writings not preserved in Hebrew. 　Alongside the archangel Michael, Gabriel is described as the guardian angel of Israel, defending its people against the angels of the other nations. 　In the New Testament, the Gospel of Luke relates the stories of the Annunciation, in which the angel Gabriel appears to Zechariah and the Virgin Mary, announcing to each the births of John the Baptist and Jesus, respectively (Luke 1:11–38). 　Islam regards Gabriel as an archangel sent by God to various prophets, including Muhammad. 　The first five verses of the Al-Alaq, the 96th chapter of the Quran, is believed by Muslims to have been the first verses revealed by Gabriel to Muhammad.

Radius

In classical geometry, a radius (PL: radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. 　The name comes from the latin radius, meaning ray but also the spoke of a chariot wheel. 　The plural of radius can be either radii (from the Latin plural) or the conventional English plural radiuses. 　The typical abbreviation and mathematical variable name for radius is R or r. 　By extension, the diameter D is defined as twice the radius: d ≐ 2 r ⇒ r = d 2 . 　{\displaystyle d\doteq 2r\quad \Rightarrow \quad r={\frac {d}{2}}.　} If an object does not have a center, the term may refer to its circumradius, the radius of its circumscribed circle or circumscribed sphere. 　In either case, the radius may be more than half the diameter, which is usually defined as the maximum distance between any two points of the figure. 　The inradius of a geometric figure is usually the radius of the largest circle or sphere contained in it. 　The inner radius of a ring, tube or other hollow object is the radius of its cavity. 　For regular polygons, the radius is the same as its circumradius. 　The inradius of a regular polygon is also called apothem. 　In graph theory, the radius of a graph is the minimum over all vertices u of the maximum distance from u to any other vertex of the graph. 　The radius of the circle with perimeter (circumference) C is r = C 2 π {\displaystyle r={\frac {C}{2\pi }}}

Remainder

In mathematics, the remainder is the amount "left over" after performing some computation. 　In arithmetic, the remainder is the integer "left over" after dividing one integer by another to produce an integer quotient (integer division). 　In algebra of polynomials, the remainder is the polynomial "left over" after dividing one polynomial by another. 　The modulo operation is the operation that produces such a remainder when given a dividend and divisor. 　Alternatively, a remainder is also what is left after subtracting one number from another, although this is more precisely called the difference. 　This usage can be found in some elementary textbooks; colloquially it is replaced by the expression "the rest" as in "Give me two dollars back and keep the rest." 　However, the term "remainder" is still used in this sense when a function is approximated by a series expansion, where the error expression ("the rest") is referred to as the remainder term.

Welfare

Welfare, or commonly social welfare, is a type of government support intended to ensure that members of a society can meet basic human needs such as food and shelter. 　Social security may either be synonymous with welfare, or refer specifically to social insurance programs which provide support only to those who have previously contributed (e.g. most pension systems), as opposed to social assistance programs which provide support on the basis of need alone (e.g. most disability benefits). 　The International Labour Organization defines social security as covering support for those in old age, support for the maintenance of children, medical treatment, parental and sick leave, unemployment and disability benefits, and support for sufferers of occupational injury. 　More broadly, welfare may also encompass efforts to provide a basic level of well-being through free or subsidized social services such as healthcare, education, infrastructure, vocational training, and public housing. 　In a welfare state, the state assumes responsibility for the health, education, infrastructure and welfare of society, providing a range of social services such as those described. 　Some historians view systems of codified almsgiving, like the zakat policy of the seventh century (634 CE) Rashidun caliph Umar, as early examples of universal government welfare. 　The first welfare state was Imperial Germany (1871–1918), where the Bismarck government introduced social security in 1889. 　In the early 20th century, the United Kingdom introduced social security around 1913, and adopted the welfare state with the National Insurance Act 1946, during the Attlee government (1945–51). 　In the countries of western Europe, Australia, and New Zealand, social welfare is mainly provided by the government out of the national tax revenues, and to a lesser extent by non-government organizations (NGOs), and charities (social and religious). 　A right to social security and an adequate standard of living is asserted in Articles 22 and 25 of the Universal Declaration of Human Rights.

Instant

In physics and the philosophy of science, instant refers to an infinitesimal interval in time, whose passage is instantaneous. 　In ordinary speech, an instant has been defined as "a point or very short space of time," a notion deriving from its etymological source, the Latin verb instare, from in- + stare ('to stand'), meaning 'to stand upon or near.' 　The continuous nature of time and its infinite divisibility was addressed by Aristotle in his Physics, where he wrote on Zeno's paradoxes. 　The philosopher and mathematician Bertrand Russell was still seeking to define the exact nature of an instant thousands of years later. 　As of October 2020[update], the smallest time interval certify in regulated measurements is on the order of 397 zeptoseconds (397 × 10−21 seconds).

Shower

A shower is a place in which a person bathes under a spray of typically warm or hot water. 　Indoors, there is a drain in the floor. 　Most showers have temperature, spray pressure and adjustable showerhead nozzle. 　The simplest showers have a swivelling nozzle aiming down on the user, while more complex showers have a showerhead connected to a hose that has a mounting bracket. 　This allows the showerer to hold the showerhead by hand to spray the water onto different parts of their body. 　A shower can be installed in a small shower stall or bathtub with a plastic shower curtain or door. 　Showering is common due to the efficiency of using it compared with a bathtub. 　Its use in hygiene is, therefore, common practice.　[page needed]

Quark

A quark (/kwɔːrk, kwɑːrk/) is a type of elementary particle and a fundamental constituent of matter. 　Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. 　All commonly observable matter is composed of up quarks, down quarks and electrons. 　Owing to a phenomenon known as color confinement, quarks are never found in isolation; they can be found only within hadrons, which include baryons (such as protons and neutrons) and mesons, or in quark–gluon plasmas. 　For this reason, much of what is known about quarks has been drawn from observations of hadrons. 　Quarks have various intrinsic properties, including electric charge, mass, color charge, and spin. 　They are the only elementary particles in the Standard Model of particle physics to experience all four fundamental interactions, also known as fundamental forces (electromagnetism, gravitation, strong interaction, and weak interaction), as well as the only known particles whose electric charges are not integer multiples of the elementary charge. 　There are six types, known as flavors, of quarks: up, down, charm, strange, top, and bottom. 　Up and down quarks have the lowest masses of all quarks. 　The heavier quarks rapidly change into up and down quarks through a process of particle decay: the transformation from a higher mass state to a lower mass state. 　Because of this, up and down quarks are generally stable and the most common in the universe, whereas strange, charm, bottom, and top quarks can only be produced in high energy collisions (such as those involving cosmic rays and in particle accelerators). 　For every quark flavor there is a corresponding type of antiparticle, known as an antiquark, that differs from the quark only in that some of its properties (such as the electric charge) have equal magnitude but opposite sign. 　The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964. 　Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until deep inelastic scattering experiments at the Stanford Linear Accelerator Center in 1968. 　Accelerator program experiments have provided evidence for all six flavors. 　The top quark, first observed at Fermilab in 1995, was the last to be discovered.

Pulse

In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. 　The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the neck (carotid artery), wrist (radial artery), at the groin (femoral artery), behind the knee (popliteal artery), near the ankle joint (posterior tibial artery), and on foot (dorsalis pedis artery). 　Pulse (or the count of arterial pulse per minute) is equivalent to measuring the heart rate. 　The heart rate can also be measured by listening to the heart beat by auscultation, traditionally using a stethoscope and counting it for a minute. 　The radial pulse is commonly measured using three fingers. 　This has a reason: the finger closest to the heart is used to occlude the pulse pressure, the middle finger is used get a crude estimate of the blood pressure, and the finger most distal to the heart (usually the ring finger) is used to nullify the effect of the ulnar pulse as the two arteries are connected via the palmar arches (superficial and deep). 　The study of the pulse is known as sphygmology.

Switch

In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. 　The most common type of switch is an electromechanical device consisting of one or more sets of movable electrical contacts connected to external circuits. 　When a pair of contacts is touching current can pass between them, while when the contacts are separated no current can flow. 　Switches are made in many different configurations; they may have multiple sets of contacts controlled by the same knob or actuator, and the contacts may operate simultaneously, sequentially, or alternately. 　A switch may be operated manually, for example, a light switch or a keyboard button, or may function as a sensing element to sense the position of a machine part, liquid level, pressure, or temperature, such as a thermostat. 　Many specialized forms exist, such as the toggle switch, rotary switch, mercury switch, push-button switch, reversing switch, relay, and circuit breaker. 　A common use is control of lighting, where multiple switches may be wired into one circuit to allow convenient control of light fixtures. 　Switches in high-powered circuits must have special construction to prevent destructive arcing when they are opened.

Julia

Julia is usually a feminine given name. 　It is a Latinate feminine form of the name Julio and Julius. 　(For further details on etymology, see the Wiktionary entry "Julius".) 　The given name Julia had been in use throughout Late Antiquity (e.g. Julia of Corsica) but became rare during the Middle Ages, and was revived only with the Italian Renaissance. 　It became common in the English-speaking world only in the 18th century. 　Today, it is frequently used throughout the world.

Household

A household consists of two or more persons who live in the same dwelling. 　It may be of a single family or another type of person group. 　The household is the basic unit of analysis in many social, microeconomic and government models, and is important to economics and inheritance. 　Household models include families, blended families, shared housing, group homes, boarding houses, houses of multiple occupancy (UK), and single room occupancy (US). 　In feudal societies, the royal household and medieval households of the wealthy included servants and other retainers.

Oxygen

Oxygen is the chemical element with the symbol O and atomic number 8. 　It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. 　Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. 　At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O 2. 　Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. 　Oxygen makes up almost half of the Earth's crust in the form of oxides. 　All plants, animals, and fungus need oxygen for cellular respiration, which extracts energy by the reaction of oxygen with molecules derived from food and produces carbon dioxide as a waste product. 　In vetabrate animals breathing brings oxygen into the lungs where gas exchange takes place, carbon dioxide diffuses out of the blood, and oxygen diffuses into the blood. 　The body's circulatory system transports the oxygen the cells, where cellular respiration takes place. 　Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. 　Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. 　Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. 　Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. 　Another form (allotrope) of oxygen, ozone (O 3), strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. 　However, ozone present at the surface is a byproduct of smog and thus a pollutant. 　Oxygen was isolated by Michael Sendivogius before 1604, but it is commonly believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774. 　Priority is often given for Priestley because his work was published first. 　Priestley, however, called oxygen "dephlogisticated air", and did not recognize it as a chemical element. 　The name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and correctly characterized the role it plays in combustion. 　Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.

Dawn

Dawn is the time that marks the beginning of twilight before sunrise. 　It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon. 　This morning twilight period will last until sunrise (when the Sun's upper limb breaks the horizon), when direct sunlight outshines the diffused light.

Disaster

A disaster is a serious problem occurring over a short or long period of time that causes widespread human, material, economic or environmental loss which exceeds the ability of the affected community or society to cope using its own resources. 　Disasters are routinely divided into either "natural disasters" caused by natural hazards or "human-instigated disasters" caused from anthropogenic hazards. 　However, in modern times, the divide between natural, human-made and human-accelerated disasters is difficult to draw. 　Examples of natural hazards include avalanches, flooding, cold waves and heat waves, droughts, earthquakes, cyclones, landslides, lightning, tsunamis, volcanic activity, wildfires, and winter precipitation. 　Examples of anthropogenic hazards include criminality, civil disorder, terrorism, war, industrial hazards, engineering hazards, power outages, fire, hazards caused by transportation, and environmental hazards. 　Developing countries suffer the greatest costs when a disaster hits – more than 95% of all deaths caused by hazards occur in developing countries, and losses due to natural hazards are 20 times greater (as a percentage of gross domestic product) in developing countries than in industrialized countries.

Copper

Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. 　It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. 　A freshly exposed surface of pure copper has a pinkish-orange color. 　Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. 　Copper is one of the few metals that can occur in nature in a directly usable metallic form (native metals). 　This led to very early human use in several regions, from circa 8000 BC. 　Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 　4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create bronze, c. 　3500 BC. 　In the Roman era, copper was mined principally on Cyprus, the origin of the name of the metal, from aes cyprium (metal of Cyprus), later corrupted to cuprum (Latin). 　Coper (Old English) and copper were derived from this, the later spelling first used around 1530. 　Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as azurite, malachite, and turquoise, and have been used widely and historically as pigments. 　Copper used in buildings, usually for roofing, oxidizes to form a green verdigris (or patina). 　Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. 　Copper compounds are used as bacteriostatic agents, fungicides, and wood preservatives. 　Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. 　In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. 　In humans, copper is found mainly in the liver, muscle, and bone. 　The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.