Process that results in adaptation of an organism to its environment by means of selectively reproducing changes in its genotype. Variations that increase an organism's chances of survival and procreation are preserved and multiplied from generation to generation at the expense of less advantageous variations. As proposed by Charles Darwin, natural selection is the mechanism by which evolution occurs. It may arise from differences in survival, fertility, rate of development, mating success, or any other aspect of the life cycle. Mutation, gene flow, and genetic drift, all of which are random processes, also alter gene abundance. Natural selection moderates the effects of these processes because it multiplies the incidence of beneficial mutations over generations and eliminates harmful ones, since the organisms that carry them leave few or no descendants. Seealso selection.
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Principle of physics according to which the energy of interacting bodies or particles in a closed system remains constant, though it may take different forms (e.g., kinetic energy, potential energy, thermal energy, energy in an electric current, or energy stored in an electric field, in a magnetic field, or in chemical bonds [see bonding]). With the advent of relativity physics in 1905, mass was recognized as equivalent to energy. When accounting for a system of high-speed particles whose mass increases as a consequence of their speed, the laws of conservation of energy and conservation of mass become one conservation law. Seealso Hermann von Helmholtz.
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In physics, the principle that certain quantities within an isolated system do not change over time. When a substance in an isolated system changes phase, the total amount of mass does not change. When energy is changed from one form to another in an isolated system, there is no change in the total amount of energy. When a transfer of momentum occurs in an isolated system, the total amount of momentum is conserved. The same is true for electric charge in a system: charge lost by one particle is gained by another. Conservation laws make it possible to predict the macroscopic behaviour of a system without having to consider the microscopic details of a physical process or chemical reaction.
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Planned management of a natural resource or of a particular ecosystem to prevent exploitation, pollution, destruction, or neglect and to ensure the future usability of the resource. Living resources are renewable, minerals and fossil fuels are nonrenewable. In the West, conservation efforts date to 17th-century efforts to protect European forests in the face of increasing demands for fuel and building materials. National parks, first established in the 19th century, were dedicated to the preservation of uncultivated land not only to provide a safe haven to wildlife but to protect watershed areas and help ensure a clean water supply. National legislation and international treaties and regulations aim to strike a balance between the need for development and the need to conserve the environment for the future.
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Maintenance and preservation of works of art, their protection from future damage, deterioration, or neglect, and the repair or renovation of works that have deteriorated or been damaged. Research in art history has relied heavily on 20th- and 21st-century technical and scientific advances in art restoration. Modern conservation practice adheres to the principle of reversibility, which dictates that treatments should not cause permanent alteration to the object.
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(1933–42) U.S. unemployment program. One of the earliest New Deal programs, it was established to relieve unemployment during the Great Depression by providing national conservation work primarily for young unmarried men. Recruits lived in semimilitary work camps and received $30 a month as well as food and medical care. Projects included planting trees, building flood barriers, fighting forest fires, and maintaining forest roads and trails. It employed a total of 3 million men during its existence.
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In jurisprudence and political philosophy, a system of right or justice common to all humankind and derived from nature rather than from the rules of society, or positive law. The concept can be traced to Aristotle, who held that what was “just by nature” was not always the same as what was “just by law.” In one form or another, the existence of natural law was asserted by the Stoics (see Stoicism), Cicero, the Roman jurists, St. Paul, St. Augustine, Gratian, St. Thomas Aquinas, John Duns Scotus, William of Ockham, and Francisco Suárez. In the modern period, Hugo Grotius insisted on the validity of natural law even on the assumption that God does not exist, and Thomas Hobbes defined a law of nature as “a precept of general rule found out by reason, by which a man is forbidden to do that which is destructive of his life.” Hobbes attempted to construct an edifice of law by rational deduction from a hypothetical “state of nature” and a social contract of consent between rulers and subjects. John Locke departed from Hobbes in describing the state of nature as an early society in which free and equal men observe the natural law. Jean-Jacques Rousseau postulated a savage who was virtuous in isolation and actuated by two principles “prior to reason”: self-preservation and compassion. The authors of the U.S. Declaration of Independence refer only briefly to “the Laws of Nature” before citing equality and other “unalienable” rights as “self-evident.” The French Declaration of the Rights of Man and of the Citizen asserts liberty, property, security, and resistance to oppression as “imprescriptible natural rights.” Interest in the concept of natural law declined dramatically in the 19th century, partly as a result of skeptical attacks by Jeremy Bentham and other proponents of utilitarianism; it was revived in the mid-20th century in light of the crimes committed by the Nazi regime during World War II. Skepticism of natural law and natural rights remained strong, however, and later writers almost invariably talked of human rights rather than natural rights.
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Colourless, highly flammable gaseous hydrocarbon consisting primarily of methane and ethane. It may also contain heavier hydrocarbons, carbon dioxide, hydrogen, hydrogen sulfide, nitrogen, helium, and argon. It commonly occurs in association with crude oil (see petroleum). Natural gas is extracted from wells drilled into the Earth. Some natural gas can be used as it comes from the well, without any refining, but most requires processing. It is transported either in its natural gaseous state by pipeline or, after liquefaction by cooling, by tankers. Liquefied natural gas occupies only about 1/600 of the volume of the gas. It has grown steadily as a source of energy since the 1930s.
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Any of the systems (e.g., the Lamaze method) of managing birth without drugs or surgery. All begin with classes to teach pregnant women about the birth process, including when to push and what breathing and relaxation techniques to use at which stage. The goal is to reduce fear and muscle tension, which can increase the pain of labour, and to make the mother an active participant in the process. The father or another partner usually attends the classes with the mother and coaches her during the birth. Seealso midwifery; obstetrics and gynecology.
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Naturally created arch formation resembling a bridge. Most are erosion features that occur in sandstone or limestone. Some are formed by the collapse of part of a cavern roof. Others may be produced by entrenched rivers eroding through meander necks to form cutoffs. Still others are produced by exfoliation (separation of successive thin shells) and may be enlarged by wind erosion.
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Leading scientific society in Britain and the oldest national scientific society in the world. Founded in 1660, its early members included Robert Hooke, Christopher Wren, Isaac Newton, and Edmond Halley. It has long provided an impetus to scientific thought and research in the U.K., and its achievements have become internationally famous. The society's Philosophical Transactions, the oldest scientific periodical in continuous publication, has published papers since 1665. The society awards several prizes, the most prestigious being the Copley Medal. At the beginning of the 21st century, the society had some 1,300 fellows and 130 foreign members.
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National monument, southeastern Utah, U.S. Comprising three large natural bridges carved by two winding streams, it was established in 1908. The largest bridge, Sipapu, is 222 ft (68 m) high and spans 261 ft (80 m). Pictographs were carved on another of the bridges, Kachina, by early cliff dwellers.
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Major centre of research and education on the natural sciences, established in New York City in 1869. It pioneered in staging field expeditions and creating dioramas and other lifelike exhibits showing natural habitats and their plant and animal life. Its research collections contain tens of millions of specimens, and its fossil and insect collections are among the largest in the world. It conducts research in anthropology, astronomy, entomology, herpetology, ichthyology, invertebrate biology, mammalogy, mineralogy, ornithology, and vertebrate paleontology, and it maintains permanent research stations in The Bahamas and the U.S. states of New York, Florida, and Arizona. It also contains one of the world's largest planetariums.
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Natural-born citizen is a term used in some countries to describe a certain kind of citizenship in terms of a requirement for eligibility to serve as head of state of a given country. It is mentioned in the United States Constitution as a requirement for the President and Vice President of the US.
Although the United States Constitution does not explicitly define the term "natural born citizen", Section 8 of Article I confers on Congress the power: "To establish an uniform Rule of Naturalization..." This power has been construed to include defining the characteristics of a "natural born citizen", as well as the conditions of "naturalization".
Section 1 of Article II of the Constitution contains the clause:
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.Additionally, the 12th Amendment to the Constitution states that: "[N]o person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States."
It is thought the origin of the natural-born citizen clause can be traced to a letter of July 25, 1787 from John Jay (who had been born in New York City) to George Washington (who had been born in Virginia), presiding officer of the Constitutional Convention. John Jay wrote: "Permit me to hint, whether it would be wise and seasonable to provide a strong check to the admission of Foreigners into the administration of our national Government; and to declare expressly that the Commander in Chief of the American army shall not be given to nor devolve on, any but a natural born Citizen." There was no debate, and this qualification for the office of the Presidency was introduced by the drafting Committee of Eleven, and then adopted without discussion by the Constitutional Convention. (43 of the 55 delegates had been born in the Thirteen Colonies, and the others had been born on British-occupied soil: Ireland, England, Scotland, and the British West Indies. )
The 2003 Equal Opportunity to Govern Amendment, a proposed amendment to the US Constitution, would, if adopted, have removed the prohibition against naturalized citizens holding the office of the President.
"The constitutional wording has left doubts about whether those born on foreign soil are on an equal footing with those whose birth occurred inside the country's borders, and whether they have the same rights." Though every president and vice president to date (as of 2008) has either been a citizen at the adoption of the Constitution, or else born in a U.S. state or Washington D.C., a number of presidential candidates have been born elsewhere.
Barry Goldwater, who ran as the Republican party nominee in 1964, was born in Arizona while it was still a U.S. territory. Although Arizona was not a state, it was a fully organized and incorporated territory of the United States.
George Romney, who ran for the Republican party nomination in 1968, was born in Mexico to U.S. parents. Romney’s grandfather emigrated to Mexico in 1886 with his three wives and children after Utah outlawed polygamy. Romney's parents retained their U.S. citizenship and returned to the United States in 1912. Romney was 32 years old when he arrived in Michigan.
John McCain, who ran for the Republican party nomination in 2000 and is the Republican nominee in 2008, was born at the Coco Solo U.S. military base in the Panama Canal Zone to U.S. parents. Although the Panama Canal Zone was not considered to be part of the United States, federal law states: "Any person born in the Canal Zone on or after February 26, 1904, and whether before or after the effective date of this chapter, whose father or mother or both at the time of the birth of such person was or is a citizen of the United States, is declared to be a citizen of the United States. The law that conferred this status took effect on August 4, 1937, one year after John McCain was born — albeit with retroactive effect, resulting in McCain being declared a U.S. citizen.
The requirements for citizenship and the very definition thereof have changed since the Constitution was ratified in 1788. Congress first recognized the citizenship of children born to U.S. parents overseas on March 26, 1790, under the first naturalization law: "And the children of citizens of the United States that may be born beyond sea, or outside the limits of the United States, shall be considered as natural born citizens." (See ref. for the Act of 1795)
The Fourteenth Amendment mentions two types of citizenship: citizenship by birth and citizenship by law (naturalized citizens): "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside."
All persons born in the United States, except those not subject to the jurisdiction of the U.S. government (such as children of foreign diplomats) are citizens under the Fourteenth Amendment. Persons born in the United States, and persons born on foreign soil to two U.S. parents, are born American citizens and are classified as citizens at birth under 8 USC 1401. There is some debate over whether persons who were born US citizens and are classified as citizens at birth under U.S. law should also be considered citizens "by birth," whether they should all be considered to be "naturalized," or whether they should be considered "statutory citizens." There is also some debate over whether there is a meaningful legal distinction between citizens "at birth", citizens "by birth" and "statutory citizens" since U.S. law makes no such distinction, nor does the Fourteenth Amendment use the term "at birth." Current U.S. statutes define certain individuals born overseas as "citizens at birth. One side of the argument interprets the Constitution as meaning that a person either is born in the United States or is a naturalized citizen. According to this view, in order to be a "natural born citizen," a person must be born in the United States, or possibly an incorporated territory; otherwise, they are a citizen "by law" and are therefore a "statutory citizen," (not necessarily, however, a naturalized citizen, which implies a pre-existing foreign citizenship). Current State Department policy reads: "Despite widespread popular belief, U.S. military installations abroad and U.S. diplomatic or consular facilities are not part of the United States within the meaning of the 14th Amendment. A child born on the premises of such a facility is not subject to the jurisdiction of the United States and does not acquire U.S. citizenship by reason of birth. However, the State Department is of the opinion that this does not affect those who are born abroad to U.S. citizens and who otherwise meet the qualifications for statutory citizenship.