His work changed the understanding and knowledge of mathematics in the Middle Ages and mathematicians in Europe read his book. They began to use these Hindu–Arabic numerals (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...) instead of the Roman numerals (I, II, III, IV, V, VI, VII, VIII, IX, X, ...). The Arabic numeral system is easier to do mathematics with, as Roman numbers have no place values. This means that they can only deal with whole numbers and do simple equations. Roman numerals also have no number zero.
He wrote a book on algebra named "Al-Jabr Wal' Muqibla". In this book, he introduced his own number system and also introduced Arabic numerals. His books were translated into Greek and Latin. They named his books "So said Algorizmi". The word "algorithm" is derived from the word Algorizmi. The word algebra comes from the word al-jabr that is at the beginning of the title of the book.
Muhammad ibn Musa al-Khwarizmi worked at the House of Wisdom, where people worked on translating scientific works.
Ptolemy
Claudius Ptolemy ( ; ; – ) was a Greek who probably lived and worked in Alexandria, Egypt. He is famous for his work on astronomy and geography. Very little is known about his personal life.
He was an astronomer, mathematician, and geographer. He described in his writing the Greek geocentric view of the universe. Earlier Greek philosophers changed the old assumption of a flat Earth below a "vault of the heavens". They substituted a spherical Earth surrounded by a Celestial sphere. Ptolemy built these two spheres into a system of nested spheres. He also thought out and described the apparent motions of the planets as they were known in his time.
Ptolemy explained and extended Hipparchus's system of epicycles and eccentric circles to explain the Earth-centered theory of the world. Ptolemy's system involved at least 80 epicycles to explain the motions of the Sun, the Moon, and the five planets known in his time. He believed the planets and sun moved around the Earth in this order: Mercury, Venus, Sun, Mars, Jupiter, Saturn.
This system became known as the "Ptolemaic system". It predicts the positions of the planets well enough for naked-eye observations, so it seemed accurate at the time. This is described in his book "Mathematical Syntaxis" (widely called the "Almagest"), a thirteen-book mathematical treatment of the phenomena of astronomy. It contains a wide variety of information ranging from earth conceptions to sun, moon, and star movement as well as eclipses and an explanation of the length of months. The "Almagest" also included a star catalog containing 48 constellations, using the names we still use today.
In addition to his well-known works in astronomy, Claudius Ptolemy was important in the history of geography and cartography (making maps). He was influential up to the 16th century. Then his ideas were disproved by Nicolaus Copernicus. Ptolemy knew that the Earth is a sphere. Ptolemy's is the first known projection of the sphere onto a plane. His "Geography" remained the main work on the subject until the time of Christopher Columbus. But he had Asia extending much too far east, which may have been a factor in Columbus's decision to try to reach India by sailing west from Europe.
The Ptolemaic explanation of the motions of the planets was the accepted wisdom until the Polish scholar Copernicus proposed a sun-centered (heliocentric) view in 1543. Though the heliocentric idea is correct, its predictions were not better than Ptolemy's until Kepler's Laws were added.
Ptolemy may not actually have believed in the reality of his system. He may have thought of it only as a method of calculating positions.
Moctezuma II
Moctezuma II, also known as Motecuhzoma Xocoyotzin (1466-1520) and often called Montezuma in English, was the Aztec emperor ("tlahtoani") from 1502 to 1520. His name comes from the Nahuatl "Motecuhzoma", it means "he who is leader because of his fury". In Spanish, he is called Moctezuma.
When Hernán Cortés arrived in Mexico in 1519, Moctezuma thought he was the god Quetzalcoatl, and did not want to fight against him. Cortés took Moctezuma prisoner. When the Aztecs wanted Cortés to get out of their capital Tenochtitlan in 1520, Cortes told Moctezuma to calm down his people. When doing that he died. The Spaniards said he was killed by the Aztecs, while the Aztecs said Cortés killed him. The Spanish said that the Aztec people threw rocks at him, killing him. The Aztecs said that they found his body in the streets with a lot of cuts made with a sword after the Spanish left.
Antonio López de Santa Anna
Antonio López de Santa Anna Pérez de Lebrón (February 21, 1794 - June 21, 1876) was a Mexican general and dictator. Under his rule of Mexico, it lost half its territory. Santa Anna was president 11 times. He fought two wars against the United States. In the war against Texas (1835-1836), he won the famous Battle of the Alamo, but later he lost the Battle of San Jacinto and was taken prisoner by the Americans. He also lost the Mexican- American War with the United States (1846-1848),
Granzyme
A Granzyme is an enzyme contained within cytotoxic T cells and natural killer cells. These substances are used to destroy virus-infected cells.
Granzyme secretion can be detected and measured using the ELISPOT and ELISA techniques.
Apartheid
Apartheid was a political and social system in South Africa during the era of White minority rule. It enforced racial discrimination against non-Whites, mainly focused on skin colour and facial features. This existed in the twentieth century, from 1948 until the early-1990s. The word "apartheid" means "distantiation” in the Afrikaans language. Racial segregation had existed in Southern Africa for centuries. In the elections of 1948 the National Party took power and in the next few years made new apartheid laws. The new laws more strictly enforced segregation. In theory, it was to bring independence to the African majority in their own little countries to be created from South African territory.
Under this system, the people of South Africa were divided by their race and the different races were forced to live separately from each other. There were laws in place to ensure that segregation was abided by. The apartheid system in South Africa was abolished in 1994, when a new constitution was ratified which abolished the previous system of segregation. The last President who held office during the apartheid era was Frederik Willem de Klerk; who was responsible for holding negotiations with political prisoner Nelson Mandela to bring an end to apartheid. Following these successful negotiations, Nelson Mandela was elected to the Presidency of South Africa after multi-racial elections were held in April 1994, and became the first black person to hold the position. He was 75 years old The pair were awarded the Nobel Peace Prize for their efforts. Today, the term apartheid is sometimes used for similar segregational systems in other countries.
During apartheid, people were divided into four racial groups and separated by law. The system was used to deny many basic rights to non-White people, mainly Black people who lived in South Africa. The law allowed white people to be in certain areas. Black people had to carry special passes or have permission to travel outside their designated area, or work in particular areas reserved for Whites. The government separated mixed communities and forcibly moved many black people off their land (From 1960 to 1983 the Bantustan Policy was enforced to forcibly move South African blacks out of the areas designated for 'whites'). Many other laws were made, for example: interracial marriage was outlawed; Black people could not own land in White areas or vote.