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πŸ”— Sleep and creativity

πŸ”— Physiology πŸ”— Physiology/neuro

The majority of studies on sleep creativity have shown that sleep can facilitate insightful behavior and flexible reasoning, and there are several hypotheses about the creative function of dreams. On the other hand, a few recent studies have supported a theory of creative insomnia, in which creativity is significantly correlated with sleep disturbance.

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πŸ”— Heisenbug

πŸ”— Computing πŸ”— Computing/Software

In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect of quantum mechanics, which states that the act of observing a system inevitably alters its state. In electronics the traditional term is probe effect, where attaching a test probe to a device changes its behavior.

Similar terms, such as bohrbug, mandelbug, hindenbug, and schrΓΆdinbug (see the section on related terms) have been occasionally proposed for other kinds of unusual software bugs, sometimes in jest; however, unlike the term heisenbug, they are not widely known or used.

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πŸ”— Pentium floating-point division bug (1994)

πŸ”— Computing πŸ”— Computing/Computer hardware

The Pentium FDIV bug is a hardware bug affecting the floating-point unit (FPU) of the early Intel Pentium processors. Because of the bug, the processor would return incorrect binary floating point results when dividing certain pairs of high-precision numbers. The bug was discovered in 1994 by Thomas R. Nicely, a professor of mathematics at Lynchburg College. Missing values in a lookup table used by the FPU's floating-point division algorithm led to calculations acquiring small errors. While these errors would in most use-cases only occur rarely and result in small deviations from the correct output values, in certain circumstances the errors can occur frequently and lead to more significant deviations.

The severity of the FDIV bug is debated. Though rarely encountered by most users (Byte magazine estimated that 1 in 9 billion floating point divides with random parameters would produce inaccurate results), both the flaw and Intel's initial handling of the matter were heavily criticized by the tech community.

In December 1994, Intel recalled the defective processors in what was the first full recall of a computer chip. In its 1994 annual report, Intel said it incurred "a $475 million pre-tax chargeΒ ... to recover replacement and write-off of these microprocessors."

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πŸ”— ISO Warning Signs

πŸ”— Occupational Safety and Health

ISO 7010 is an International Organization for Standardization technical standard for graphical hazard symbols on hazard and safety signs, including those indicating emergency exits. It uses colours and principles set out in ISO 3864 for these symbols, and is intended to provide "safety information that relies as little as possible on the use of words to achieve understanding." It is distinct from the Globally Harmonized System of Classification and Labelling of Chemicals specified by the United Nations to standardise hazardous material classification and labelling.

As of AugustΒ 2019, the latest version is ISO 7010:2019. This revision incorporates all previous corrigenda, as well as incorporates water safety signs and beach safety flags previously specified in (the now-withdrawn) ISO 20712.

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πŸ”— MD6 Message-Digest Algorithm

πŸ”— Cryptography πŸ”— Cryptography/Computer science

The MD6 Message-Digest Algorithm is a cryptographic hash function. It uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis. The source code of the reference implementation was released under MIT license.

Speeds in excess of 1 GB/s have been reported to be possible for long messages on 16-core CPU architecture.

In December 2008, Douglas Held of Fortify Software discovered a buffer overflow in the original MD6 hash algorithm's reference implementation. This error was later made public by Ron Rivest on 19 February 2009, with a release of a corrected reference implementation in advance of the Fortify Report.

MD6 was submitted to the NIST SHA-3 competition. However, on July 1, 2009, Rivest posted a comment at NIST that MD6 is not yet ready to be a candidate for SHA-3 because of speed issues, a "gap in the proof that the submitted version of MD6 is resistant to differential attacks", and an inability to supply such a proof for a faster reduced-round version, although Rivest also stated at the MD6 website that it is not withdrawn formally. MD6 did not advance to the second round of the SHA-3 competition. In September 2011, a paper presenting an improved proof that MD6 and faster reduced-round versions are resistant to differential attacks was posted to the MD6 website.

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πŸ”— Mercantilism

πŸ”— History πŸ”— Economics πŸ”— Politics πŸ”— Trade πŸ”— Politics/Libertarianism

Mercantilism is a nationalist economic policy that is designed to maximize the exports and minimize the imports of an economy. In other words, it seeks to maximize the accumulation of resources within the country and use those resources for one-sided trade.

The concept aims to reduce a possible current account deficit or reach a current account surplus, and it includes measures aimed at accumulating monetary reserves by a positive balance of trade, especially of finished goods. Historically, such policies may have contributed to war and motivated colonial expansion. Mercantilist theory varies in sophistication from one writer to another and has evolved over time.

Mercantilism promotes government regulation of a nation's economy for the purpose of augmenting and bolstering state power at the expense of rival national powers. High tariffs, especially on manufactured goods, were almost universally a feature of mercantilist policy. Before it fell into decline, mercantilism was dominant in modernized parts of Europe and some areas in Africa from the 16th to the 19th centuries, a period of proto-industrialization. Some commentators argue that it is still practised in the economies of industrializing countries in the form of economic interventionism.

With the efforts of supranational organizations such as the World Trade Organization to reduce tariffs globally, non-tariff barriers to trade have assumed a greater importance in neomercantilism.

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πŸ”— Sunflower (Mathematics)

πŸ”— Mathematics

In the mathematical fields of set theory and extremal combinatorics, a sunflower or Ξ” {\displaystyle \Delta } -system is a collection of sets whose pairwise intersection is constant. This constant intersection is called the kernel of the sunflower.

The main research question arising in relation to sunflowers is: under what conditions does there exist a large sunflower (a sunflower with many sets) in a given collection of sets? The Ξ” {\displaystyle \Delta } -lemma, sunflower lemma, and the ErdΕ‘s-Rado sunflower conjecture give successively weaker conditions which would imply the existence of a large sunflower in a given collection, with the latter being one of the most famous open problems of extremal combinatorics.

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