The importance of signs and signification has been recognized throughout much of the history of philosophy, and in psychology as well. The term derives from the Greek: σημειωτικός, "sēmeiōtikos", "observant of signs" (from σημεῖον "sēmeion", "a sign, a mark"). For the Greeks, "signs" occurred in the world of nature, and "symbols" in the world of culture. As such, Plato and Aristotle explored the relationship between signs and the world.
The general study of signs that began in Latin with Augustine culminated with the 1632 "Tractatus de Signis" of John Poinsot, and then began anew in late modernity with the attempt in 1867 by Charles Sanders Peirce to draw up a "new list of categories." More recently, Umberto Eco, in his "Semiotics and the Philosophy of Language", has argued that semiotic theories are implicit in the work of most, perhaps all, major thinkers.
Semiotics is usually divided into three parts:
The major branches of semiotics include:
Nitrogen
Nitrogen is a nonmetal chemical element. The atmosphere contains more than 78 percent of nitrogen. It has the chemical symbol N and atomic number 7. Its stable inside typically contains 14 nucleons (7 protons and 7 neutrons). It has 5 electrons in its outer shell.
Nitrogen is a colorless odorless gas at normal temperature. It is normally attached to another nitrogen atom, making a nitrogen molecule (N). This bond is very strong. That is why many explosives contain nitrogen. The bond is broken when the explosive is made. When it explodes the bond forms, releasing a lot of energy.
It turns into a liquid at -195.8°C and turns into a solid at -210°C. If it is compressed, it can be turned into a liquid without making it cold.
It usually does not combine with other atoms because its strong bond prevents it from reacting. Lithium is one of the few chemical elements that react with nitrogen without being heated. Magnesium can burn in nitrogen. Nitrogen also makes blue electric sparks. The blue color is caused by the atoms being excited. When they get normal again, they release light. When nitrogen is excited, it reacts with many things that it does not normally react with.
Many chemical compounds that are important for industrial purposes contain nitrogen ions. These include ammonia, nitric acid, nitrates and cyanides. Nitrogen comes in several oxidation states; -3, -2, -/, +1, +3, +4, and +5. Each of those oxidation states has its set of compounds.
Compounds in the -3 oxidation state are weak reducing agents. These include ammonia, ammonium, amide and nitrides. Amino acids and proteins contain nitrogen in this oxidation state. Hydrazine, a compound in the -2 oxidation state, is a strong reducing agent. Azides contain nitrogen in the -/ oxidation state. They are extremely powerful reducing agents, and most are very toxic.
Nitrous oxide contains nitrogen in the +1 oxidation state. It is used as an anesthetic. Compounds containing nitrogen in the +2 oxidation state, such as nitric oxide, are reducing agents. +3 oxidation state compounds are strong oxidizing agents and weak reducing agents. Nitrites are the most common +3 compounds. Compounds in the +4 oxidation state are strong oxidizing agents. They include nitrogen dioxide and dinitrogen tetroxide.
Compounds containing nitrogen in the +5 oxidation state are strong oxidizing agents. They are one of the more common groups of nitrogen compounds. They include nitric acid and dinitrogen pentoxide. They also include nitrates, which are used in explosives such as dynamite, nitroglycerin and trinitrotoluene.
Air is made up of about 78% nitrogen and about 20.95% oxygen, < 1% argon, and traces of other gasses such as carbon dioxide, and water vapor, among others. It is also in a few nitrates in the ground. Ammonium minerals are rare. Nitrogen is in proteins.
Pure liquid nitrogen can be made by cooling air. The nitrogen turns into a liquid at a different temperature than the oxygen. It can also be made by heating certain chemical compounds, such as sodium azide.
Nitrogen as an element is used to prevent things from reacting with the oxygen in the air. It can be used to fill crisp bags and incandescent bulbs. It is also used to fill some tires. It can be used to make electric components like transistors. Liquid nitrogen can be used to freeze things.
Nitrogen compounds have many uses, such as anesthetics (nitrous oxide), explosives (dynamite), cleaners (ammonia), and meat (protein), and planes (fuel).
Oil companies use high pressure nitrogen to help force crude oil to the surface.
Nitrogen was discovered by Daniel Rutherford in 1772, who called it "noxious gas" or "fixed gas". They discovered that part of air did not burn. It was found that animals died in it. It was known as "azote". Many nitrogen compounds also contain the "azide" or "azine" letters, such as hydrazine.
In 1910, Lord Rayleigh found out that when a spark was passed through nitrogen, it made a reactive form of nitrogen. This nitrogen reacted with many metals and compounds.
Association football
Association football is a sport played between two teams. It was invented in England, and is played in most countries. In the United States and Canada, it is called soccer. In most other countries it is called football. Association football is the most popular sport in the world.
There were various attempts to codify the rules of football in England in the mid-19th century. The present laws date from 1863 when a set of rules was adopted in Rugby, Warwickshire by the newly formed Football Association.
Each team has 11 players on the field. One of these players is the goalkeeper, and the other ten are known as "outfield players". The game is played by kicking a ball into the opponent's goal. A match has 90 minutes of play, with a break of 15 minutes during the match. The break in the middle is called "half-time". Added time may be added after half time or after 90 minutes to make up for time lost during the game because of fouls, free kicks, corner kicks, injuries, bookings, substitutions or any other time the game is stopped. If a match ends in a tie, extra-time with two halves of 15 minutes each may be played, and if there is still a tie, a penalty shootout decides the winner. Sometimes extra-time is skipped and the game goes right into the penalty shootout.
There are many competitions for football, for both football clubs and countries. Football clubs usually play other teams in their own country, with a few exceptions. Here are a list of some of those exceptions:
Football clubs also play other teams in their continent in competitions such as the CAF Champions League and the UEFA Champions League.
There are 6 associations (CONCACAF, CONMEBOL, CAF, UEFA, AFC, and OFC). Each association has their own continental competition between clubs and national teams. Some examples are the Copa América for CONMEBOL national teams and the Copa Libertadores for CONMEBOL clubs. FIFA organises international competitions between worldwide clubs and countries. Clubs play in the Club World Cup, and countries play for the FIFA World Cup.
The FIFA World Cup takes place every four years between national teams, and is the world's most popular sporting event, even more popular than the Olympic Games. In football, there are two main competition types. In a "league", all of the teams play the same number of games, but in a "cup", teams leave the competition when they lose, until the last two teams play each other to decide the winner.
Football is the world's most popular sport. It is played in more countries than any other game. In fact, FIFA (the Federation Internationale de Football Association) has more members than the United Nations. It was originally an all-male sport, but today it is played by both males and females (separately, except sometimes at primary school level).