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A negative base (or negative radix) may be used to construct a non-standard positional numeral system. Like other place-value systems, each position holds multiples of the appropriate power of the system's base; but that base is negative—that is to say, the base b is equal to −r for some natural number r (r ≥ 2).

Negative-base systems can accommodate all the same numbers as standard place-value systems, but both positive and negative numbers are represented without the use of a minus sign (or, in computer representation, a sign bit); this advantage is countered by an increased complexity of arithmetic operations. The need to store the information normally contained by a negative sign often results in a negative-base number being one digit longer than its positive-base equivalent.

The common names for negative-base positional numeral systems are formed by prefixing nega- to the name of the corresponding positive-base system; for example, negadecimal (base −10) corresponds to decimal (base 10), negabinary (base −2) to binary (base 2), negaternary (base −3) to ternary (base 3), and negaquaternary (base −4) to quaternary (base 4).

.tk is the Internet country code top-level domain (ccTLD) for Tokelau, a territory of New Zealand in the South Pacific.

The Dilbert principle is a concept in management developed by Scott Adams, creator of the comic strip Dilbert, which states that companies tend to systematically promote incompetent employees to management to get them out of the workflow. The Dilbert principle is inspired by the Peter principle, which holds that employees are promoted based on success in their current position until they reach their "level of incompetence" and are no longer promoted. Under the Dilbert principle, employees who were never competent are promoted to management to limit the damage they can do. Adams first explained the principle in a 1995 Wall Street Journal article, and expanded upon it in his 1996 business book The Dilbert Principle.

The Kola Superdeep Borehole (Russian: Кольская сверхглубокая скважина) is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, on the Kola Peninsula. The project attempted to drill as deep as possible into the Earth's crust. Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. Boreholes were drilled by branching from a central hole. The deepest, SG-3, reached 12,262 metres (40,230 ft; 7.619 mi) in 1989 and is the deepest artificial point on Earth. The borehole is 23 centimetres (9 in) in diameter.

In terms of true vertical depth, it is the deepest borehole in the world. For two decades it was also the world's longest borehole in terms of measured depth along the well bore, until it was surpassed in 2008 by the 12,289-metre-long (40,318 ft) Al Shaheen oil well in Qatar, and in 2011 by the 12,345-metre-long (40,502 ft) Sakhalin-I Odoptu OP-11 Well (offshore from the Russian island of Sakhalin).

Wikipedia provides one of the more prominent resources on the Web for factual information about contemporary mathematics, with over 20,000 articles on mathematical topics. It is natural that many readers use Wikipedia for the purpose of self-study in mathematics and its applications. Some readers will be simultaneously studying mathematics in a more formal way, while others will rely on Wikipedia alone. There are certain points that need to be kept in mind by anyone using Wikipedia for mathematical self-study, in order to make the best use of what is here, perhaps in conjunction with other resources.

The Price Revolution, sometimes known as the Spanish Price Revolution, was a series of economic events that occurred between the second half of the 15th century and the first half of the 17th century, and most specifically linked to the high rate of inflation that occurred during this period across Western Europe. Prices rose on average roughly sixfold over 150 years. This level of inflation amounts to 1–1.5% per year, a relatively low inflation rate for modern-day standards, but rather high given the monetary policy in place in the 16th century.

Generally it is thought that this high inflation was caused by the large influx of gold and silver from the Spanish treasure fleet from the New World, including Mexico, Peru, and the rest of the Spanish Empire.

Specie flowed through Spain, increasing Spanish prices, and then spread over Western Europe as a result of Spanish balance of payments deficit. This enlarged the monetary supply and price levels of many European countries. Combined with this influx of gold and silver, population growth and urbanization perpetuated the price revolution. According to this theory, too many people with too much money chased too few goods.

Hair ice, also known as ice wool or frost beard, is a type of ice that forms on dead wood and takes the shape of fine, silky hair. It is somewhat uncommon, and has been reported mostly at latitudes between 45–55 °N in broadleaf forests. The meteorologist and discoverer of continental drift, Alfred Wegener, described hair ice on wet dead wood in 1918, assuming some specific fungi as the catalyst, a theory mostly confirmed by Gerhart Wagner and Christian Mätzler in 2005. In 2015, the fungus Exidiopsis effusa was identified as key to the formation of hair ice.

The Seikilos epitaph is the oldest surviving complete musical composition, including musical notation, from anywhere in the world. The epitaph has been variously dated, but seems to be either from the 1st or the 2nd century AD. The song, the melody of which is recorded, alongside its lyrics, in the ancient Greek musical notation, was found engraved on a tombstone (a stele) from the Hellenistic town Tralles near present-day Aydın, Turkey, not far from Ephesus. It is a Hellenistic Ionic song in either the Phrygian octave species or Iastian tonos. While older music with notation exists (for example the Hurrian songs), all of it is in fragments; the Seikilos epitaph is unique in that it is a complete, though short, composition.

M.2, formerly known as the Next Generation Form Factor (NGFF), is a specification for internally mounted computer expansion cards and associated connectors. M.2 replaces the mSATA standard, which uses the PCI Express Mini Card physical card layout and connectors. Employing a more flexible physical specification, the M.2 allows different module widths and lengths, and, paired with the availability of more advanced interfacing features, makes the M.2 more suitable than mSATA in general for solid-state storage applications, and particularly in smaller devices such as ultrabooks and tablets.

Computer bus interfaces provided through the M.2 connector are PCI Express 3.0 (up to four lanes), Serial ATA 3.0, and USB 3.0 (a single logical port for each of the latter two). It is up to the manufacturer of the M.2 host or module to select which interfaces are to be supported, depending on the desired level of host support and device type. The M.2 connector keying notches denote various purposes and capabilities of both M.2 hosts and devices. The unique key notches of M.2 modules also prevent them from being inserted into incompatible host connectors.

The M.2 specification supports NVM Express (NVMe) as the logical device interface for M.2 PCI Express SSDs, in addition to supporting legacy Advanced Host Controller Interface (AHCI) at the logical interface level. While the support for AHCI ensures software-level backward compatibility with legacy SATA devices and legacy operating systems, NVM Express is designed to fully utilize the capability of high-speed PCI Express storage devices to perform many I/O operations in parallel.

Veblen goods are types of luxury goods for which the quantity demanded increases as the price increases, an apparent contradiction of the law of demand, resulting in an upward-sloping demand curve. A higher price may make a product desirable as a status symbol in the practices of conspicuous consumption and conspicuous leisure. A product may be a Veblen good because it is a positional good, something few others can own.

Veblen goods are named after American economist Thorstein Veblen, who first identified conspicuous consumption as a mode of status-seeking in The Theory of the Leisure Class (1899). A corollary of the Veblen effect is that lowering the price decreases the quantity demanded.