A DNA sequencer is a scientific instrument used to automate the DNA sequencing process. Given a sample of DNA, a DNA sequencer is used to determine the order of the four bases: G (guanine), C (cytosine), A (adenine) and T (thymine). This is then reported as a text string, called a read. Some DNA sequencers can be also considered optical instruments as they analyze light signals originating from fluorochromes attached to nucleotides. The first automated DNA sequencer, invented by Lloyd M. Smith, was introduced by Applied Biosystems in 1987. It used the Sanger sequencing method, a technology which formed the basis of the "first generation" of DNA sequencers and enabled the completion of the human genome project in 2001. This first generation of DNA sequencers are essentially automated electrophoresis systems that detect the migration of labelled DNA fragments. Therefore, these sequencers can also be used in the genotyping of genetic markers where only the length of a DNA fragment(s) needs to be determined (e.g. microsatellites, AFLPs). The Human Genome Project spurred the development of cheaper, high throughput and more accurate platforms known as Next Generation...

Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The earliest known form of printing as applied to paper was woodblock printing, which appeared in China before 220 AD for cloth printing. However, it would not be applied to paper until the seventh century. Later developments in printing technology include the movable type invented by Bi Sheng around 1040 AD and the printing press invented by Johannes Gutenberg in the 15th century. The technology of printing played a key role in the development of the Renaissance and the Scientific Revolution and laid the material basis for the modern knowledge-based economy and the spread of learning to the masses. History...

The history of printing starts as early as 3000 BCE, when the proto-Elamite and Sumerian civilizations used cylinder seals to certify documents written in clay tablets . Other early forms include block seals, hammered coinage, pottery imprints, and cloth printing. Initially a method of printing patterns on cloth such as silk, woodblock printing for texts on paper originated in China by the 7th century during the Tang dynasty, leading to the spread of book production and woodblock printing in other parts of Asia such as Korea and Japan. The Chinese Buddhist Diamond Sutra, printed by woodblock on 11 May 868, is the earliest known printed book with a precise publishing date. Movable type was invented by Chinese artisan Bi Sheng in the 11th century during the Song dynasty, but it received limited use compared to woodblock printing. Nevertheless, the technology spread outside China, as the oldest printed book using metal movable type was the Jikji, printed in Korea in 1377 during the Goryeo era. Woodblock printing was also used in Europe until the mid-15th century. Late medieval...

Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely.The parents of the affected individual are usually genetically normal. The probability increases from less than 0.1% in 20-year-old mothers to 3% in those of age 45. The extra chromosome is believed to occur by chance, with no known behavioral activity or environmental factor that changes the probability. Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing. Since the introduction of screening, Down syndrome pregnancies are often aborted (rates varying from 50%-85% depending on maternal age, gestational age, and maternal race/ethnicity).There is no cure for Down syndrome. Education...

The Nine Worthies are nine historical, scriptural, and legendary men of distinction who personify the ideals of chivalry established in the Middle Ages, whose lives were deemed a valuable study for aspirants to chivalric status. All were commonly referred to as 'Princes', regardless of their historical titles. In French they are called Les Neuf Preux or "Nine Valiants", giving a more specific idea of the moral virtues they exemplified: those of soldierly courage and generalship. In Italy they are i Nove Prodi. The Nine Worthies include three pagans (Hector, Alexander the Great and Julius Caesar), three Jews (Joshua, David and Judas Maccabeus) and three Christians (King Arthur, Charlemagne and Godfrey of Bouillon). Origin They were first described in the early fourteenth century, by Jacques de Longuyon in his Voeux du Paon (1312). Their selection, as Johan Huizinga pointed out, betrays a close connection with the romance genre of chivalry. Neatly divided into a triad of triads, these men were considered to be paragons of chivalry within their particular traditions, whether Pagan, Jewish, or Christian...

Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement.Cholecalciferol is made in the skin following UVB light exposure. It is converted in the liver to calcifediol (25-hydroxyvitamin D) which is then converted in the kidney to calcitriol (1,25-dihydroxyvitamin D). One of its actions is to increase calcium uptake by the intestines. It is found in food such as some fish, beef liver, eggs, and cheese. Plant and cow milk, fruit juice, yogurt, and margarine also may have cholecalciferol added to them in some countries, including the United States.Cholecalciferol can be taken as an oral dietary supplement to prevent vitamin D deficiency or as a medication to treat associated diseases, including rickets. It is also used for familial hypophosphatemia, hypoparathyroidism that is causing low blood calcium, and Fanconi syndrome. Vitamin-D supplements may not be effective in people with severe kidney disease. Excessive doses in humans can result in vomiting, constipation...

Earth's circumference is the distance around Earth. Measured around the Equator, it is 40,075.017 km (24,901.461 mi). Measured around the poles, the circumference is 40,007.863 km (24,859.734 mi).Measurement of Earth's circumference has been important to navigation since ancient times. The first known scientific measurement and calculation was done by Eratosthenes, who achieved a great degree of precision in his computation. Treating the Earth as a sphere, its circumference would be its single most important measurement. Earth deviates from spherical by about 0.3%, as characterized by flattening. In modern times, Earth's circumference has been used to define fundamental units of measurement of length: the nautical mile in the seventeenth century and the metre in the eighteenth. Earth's polar circumference is very near to 21,600 nautical miles because the nautical mile was intended to express one minute of latitude (see meridian arc), which is 21,600 partitions of the polar circumference (that is 60 minutes × 360 degrees). The polar circumference is also close to 40,000 kilometres because the metre was originally defined to be one...

An organic product is made from materials produced by organic agriculture. Most well known organic products are organic food items, however clothing and personal care items can also be made with organic agriculture. Many countries have strict consumer safety regulations to protect consumers from consuming harmful products. These agencies often certify cultivated products as organic. The United States uses USDA certification through the National Organic Program to define products as organic. According to USDA, in order for a product to be considered organic, several standards must be met. The National List of Allowed and Prohibited Substances details synthetic and non-synthetic substances that can be used in the process of producing organic products. [1] Operations involving these organic products must be "protecting natural resources, conserving biodiversity, and using only approved substances." Organic food products Organic food products are grown under a system of agriculture without the use of harmful chemical fertilizers and pesticides with an environmentally and socially responsible approach. This is...

Humans (Homo sapiens) are the most abundant and widespread species of primate. They are a type of great ape who are characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. Humans are highly social and tend to live in complex social structures composed of many cooperating and competing groups, from families and kinship networks to political states. As such, social interactions between humans have established a wide variety of values, social norms, language, and rituals, each of which bolster human society. The desire to understand and influence phenomena have motivated humanity's development of science, technology, philosophy, mythology, religion, and other fields of study. Although some scientists equate the term humans with all members of the genus Homo, in common usage, it generally refers to Homo sapiens, the only extant member. Anatomically modern humans emerged around 300,000 years ago in Africa, evolving from Homo heidelbergensis or a similar species and migrating out of Africa, gradually replacing or interbreeding with local populations of archaic...

Machine learning (ML) is a field of inquiry devoted to understanding and building methods that 'learn', that is, methods that leverage data to improve performance on some set of tasks. It is seen as a part of artificial intelligence. Machine learning algorithms build a model based on sample data, known as training data, in order to make predictions or decisions without being explicitly programmed to do so. Machine learning algorithms are used in a wide variety of applications, such as in medicine, email filtering, speech recognition, agriculture, and computer vision, where it is difficult or unfeasible to develop conventional algorithms to perform the needed tasks.A subset of machine learning is closely related to computational statistics, which focuses on making predictions using computers, but not all machine learning is statistical...