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Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used as a eugeroic (wakefulness promoter) or as a mild cognitive enhancer to increase alertness and attentional performance. Caffeine acts by blocking binding of adenosine to the adenosine A 1 receptor, which enhances release of the neurotransmitter acetylcholine.
- C₈H₁₀N₄O₂
- 45 minutes–1 hour
Coffee is a beverage brewed from roasted coffee beans.Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It has the highest sales in the world market for hot drinks. The seeds of the Coffea plant's fruits are separated to produce unroasted green coffee beans. . The beans are roasted and then ground into fine particles ...
- 15th century
- Yemen
- Usually hot, can be ice-cold
- Roasted coffee beans
the free encyclopedia that anyone can edit. 6,826,055 articles in English. From today's featured article. The oyster dress is a high fashion gown created by British fashion designer Alexander McQueen for his Spring/Summer 2003 collection Irere. McQueen's design is a one-shouldered dress in bias-cut beige silk chiffon with a boned upper body and ...
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The word zero came into the English language via French zéro from the Italian zero, a contraction of the Venetian zevero form of Italian zefiro via ṣafira or ṣifr. In pre-Islamic time the word ṣifr (Arabic صفر) had the meaning "empty". Sifr evolved to mean zero when it was used to translate śūnya (Sanskrit: शून्य) from India. The first known Englis...
Ancient Near East
Ancient Egyptian numerals were of base 10. They used hieroglyphs for the digits and were not positional. In one papyrus written around 1770 BC, a scribe recorded daily incomes and expenditures for the pharaoh's court, using the nfr hieroglyph to indicate cases where the amount of a foodstuff received was exactly equal to the amount disbursed. Egyptologist Alan Gardiner suggested that the nfrhieroglyph was being used as a symbol for zero. The same symbol was also used to indicate the base leve...
Pre-Columbian Americas
The Mesoamerican Long Count calendar developed in south-central Mexico and Central America required the use of zero as a placeholder within its vigesimal (base-20) positional numeral system. Many different glyphs, including the partial quatrefoil were used as a zero symbol for these Long Count dates, the earliest of which (on Stela 2 at Chiapa de Corzo, Chiapas) has a date of 36 BC.[a] Since the eight earliest Long Count dates appear outside the Maya homeland, it is generally believed that th...
Classical antiquity
The ancient Greeks had no symbol for zero (μηδέν, pronounced 'midén'), and did not use a digit placeholder for it. According to mathematician Charles Seife, the ancient Greeks did begin to adopt the Babylonian placeholder zero for their work in astronomy after 500 BC, representing it with the lowercase Greek letter ό (όμικρον: omicron). However, after using the Babylonian placeholder zero for astronomical calculations they would typically convert the numbers back into Greek numerals. Greeks s...
Today, the numerical digit 0 is usually written as a circle or ellipse. Traditionally, many print typefaces made the capital letter O more rounded than the narrower, elliptical digit 0. Typewriters originally made no distinction in shape between O and 0; some models did not even have a separate key for the digit 0. The distinction came into promine...
The concept of zero plays multiple roles in mathematics: as a digit, it is an important part of positional notation for representing numbers, while it also plays an important role as a number in its own right in many algebraic settings.
The value zero plays a special role for many physical quantities. For some quantities, the zero level is naturally distinguished from all other levels, whereas for others it is more or less arbitrarily chosen. For example, for an absolute temperature (typically measured in kelvins), zero is the lowest possible value. (Negative temperatures can be d...
Modern computers store information in binary, that is, using an "alphabet" that contains only two symbols, usually chosen to be "0" and "1". Binary coding is convenient for digital electronics, where "0" and "1" can stand for the absence or presence of electrical current in a wire. Computer programmers typically use high-level programming languages...
Biology
In comparative zoology and cognitive science, recognition that some animals display awareness of the concept of zero leads to the conclusion that the capability for numerical abstraction arose early in the evolutionof species.
Dating systems
In the BC calendar era, the year 1BC is the first year before AD1; there is not a year zero. By contrast, in astronomical year numbering, the year 1BC is numbered 0, the year 2BC is numbered −1, and so forth.
A, or a, is the first letter and the first vowel letter of the Latin alphabet,[1][2] used in the modern English alphabet, and others worldwide. Its name in English is a (pronounced /ˈeɪ/ AY), plural aes.[nb 1][2] It is similar in shape to the Ancient Greek letter alpha, from which it derives.[3] The uppercase version consists of the two ...
Baby Reindeer is a British dark comedy[1][2] drama-thriller television miniseries created by and starring Richard Gadd, adapted from Gadd's autobiographical one-man show. Directed by Weronika Tofilska and Josephine Bornebusch, it also stars Jessica Gunning, Nava Mau and Tom Goodman-Hill. The series consists of seven episodes, which all ...
Dunkin' Donuts, doing business as Dunkin' since 2019, is an American multinational coffee and donut company, as well as a quick service restaurant.It was founded by Bill Rosenberg (1916–2002) in Quincy, Massachusetts, in 1950.The chain was acquired by Baskin-Robbins' holding company Allied Lyons in 1990; its acquisition of the Mister Donut chain and the conversion of that chain to Dunkin ...
