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🔗 Mathematics 🔗 Statistics 🔗 Linguistics 🔗 Linguistics/Applied Linguistics

Zipf's law (, not as in German) is an empirical law formulated using mathematical statistics that refers to the fact that many types of data studied in the physical and social sciences can be approximated with a Zipfian distribution, one of a family of related discrete power law probability distributions. Zipf distribution is related to the zeta distribution, but is not identical.

Zipf's law was originally formulated in terms of quantitative linguistics, stating that given some corpus of natural language utterances, the frequency of any word is inversely proportional to its rank in the frequency table. Thus the most frequent word will occur approximately twice as often as the second most frequent word, three times as often as the third most frequent word, etc.: the rank-frequency distribution is an inverse relation. For example, in the Brown Corpus of American English text, the word the is the most frequently occurring word, and by itself accounts for nearly 7% of all word occurrences (69,971 out of slightly over 1 million). True to Zipf's Law, the second-place word of accounts for slightly over 3.5% of words (36,411 occurrences), followed by and (28,852). Only 135 vocabulary items are needed to account for half the Brown Corpus.

The law is named after the American linguist George Kingsley Zipf (1902–1950), who popularized it and sought to explain it (Zipf 1935, 1949), though he did not claim to have originated it. The French stenographer Jean-Baptiste Estoup (1868–1950) appears to have noticed the regularity before Zipf. It was also noted in 1913 by German physicist Felix Auerbach (1856–1933).

🔗 Mathematics

In the computer science subfield of algorithmic information theory, a Chaitin constant (Chaitin omega number) or halting probability is a real number that, informally speaking, represents the probability that a randomly constructed program will halt. These numbers are formed from a construction due to Gregory Chaitin.

Although there are infinitely many halting probabilities, one for each method of encoding programs, it is common to use the letter Ω to refer to them as if there were only one. Because Ω depends on the program encoding used, it is sometimes called Chaitin's construction instead of Chaitin's constant when not referring to any specific encoding.

Each halting probability is a normal and transcendental real number that is not computable, which means that there is no algorithm to compute its digits. Indeed, each halting probability is Martin-Löf random, meaning there is not even any algorithm which can reliably guess its digits.

🔗 Computing

SoftICE is a kernel mode debugger for DOS and Windows up to Windows XP. Crucially, it is designed to run underneath Windows such that the operating system is unaware of its presence. Unlike an application debugger, SoftICE is capable of suspending all operations in Windows when instructed. For driver debugging this is critical due to how hardware is accessed and the kernel of the operating system functions. Because of its low-level capabilities, SoftICE is also popular as a software cracking tool.

Microsoft offers two kernel-mode debuggers, WinDbg and KD, for no charge. However, the full capabilities of WinDbg and KD are available only when two interlinked computers are used. SoftICE therefore is an exceptionally useful tool for difficult driver related development. The last released version was for Windows XP.

Older versions exist for DOS and compatible operating systems. SoftICE was originally produced by a company called NuMega, and was subsequently acquired by Compuware in 1997, which in turn sold the property to Micro Focus in 2009. Currently, Micro Focus owns the source code and patents, but is not actively maintaining SoftICE.

🔗 Biography 🔗 Comedy 🔗 Poland

Stańczyk (c. 1480–1560) (Polish pronunciation: [ˈstaɲt͡ʂɨk]) was a Polish court jester, the most famous in Polish history. He was employed by three Polish kings: Alexander, Sigismund the Old and Sigismund Augustus.

🔗 Psychology

In psychology, the Zeigarnik effect occurs when an activity that has been interrupted may be more readily recalled. It postulates that people remember unfinished or interrupted tasks better than completed tasks. In Gestalt psychology, the Zeigarnik effect has been used to demonstrate the general presence of Gestalt phenomena: not just appearing as perceptual effects, but also present in cognition.

🔗 Aviation 🔗 Aviation/aircraft

A propfan, also called an open rotor engine, or unducted fan, is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. A propfan is typically designed with a large number of short, highly twisted blades, similar to a turbofan's bypass compressor (the fan itself). For this reason, the propfan has been variously described as an "unducted fan" or an "ultra-high-bypass (UHB) turbofan."

🔗 Technology 🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Aviation/aircraft 🔗 Military history/World War I 🔗 Firearms

A synchronization gear, or a gun synchronizer, sometimes rather less accurately called an interrupter, is attached to the armament of a single-engine tractor-configuration aircraft so it can fire through the arc of its spinning propeller without bullets striking the blades. The idea presupposes a fixed armament directed by aiming the aircraft in which it is fitted at the target, rather than aiming the gun independently.

There are many practical problems, mostly arising from the inherently imprecise nature of an automatic gun's firing, the great (and varying) velocity of the blades of a spinning propeller, and the very high speed at which any gear synchronizing the two has to operate.

Design and experimentation with gun synchronization had been underway in France and Germany in 1913–1914, following the ideas of August Euler, who seems to have been the first to suggest mounting a fixed armament firing in the direction of flight (in 1910). However, the first practical—if far from reliable—gear to enter operational service was that fitted to the Eindecker monoplane fighters, which entered squadron service with the German Air Service in mid-1915. The success of the Eindecker led to numerous gun synchronization devices, culminating in the reasonably reliable hydraulic British Constantinesco gear of 1917. By the end of the war German engineers were well on the way to perfecting a gear using an electrical rather than a mechanical or hydraulic link between the engine and the gun, with the gun being triggered by a solenoid rather than by a mechanical "trigger motor".

From 1918 to the mid-1930s the standard armament for a fighter aircraft remained two synchronized rifle-calibre machine guns, firing forward through the arc of the propeller. During the late 1930s, however, the main role of the fighter was increasingly seen as the destruction of large, all-metal bombers, for which the "traditional" light armament was inadequate.

Since it was impractical to try to fit more than one or two extra guns in the limited space available in the front of a single-engine aircraft's fuselage, this led to an increasing proportion of the armament being mounted in the wings, firing outside the arc of the propeller. There were in fact some advantages in dispensing with centrally mounted guns altogether. Nevertheless, the conclusive redundancy of synchronization gears did not finally come until the introduction of jet propulsion and the absence of a propeller for guns to be synchronized with.

🔗 Computing 🔗 Computing/Computer hardware

Not to be confused with SuperDrive, a trademark used by Apple Computer for various disk drive products or the Super Disc, CD addon for the Super Nintendo Entertainment System.

The SuperDisk LS-120 is a high-speed, high-capacity alternative to the 90 mm (3.5 in), 1.44 MB floppy disk. The SuperDisk hardware was created by 3M's storage products group Imation in 1997, with manufacturing chiefly by Matsushita.

The SuperDisk had little success in North America; with Compaq, Gateway and Dell being three of only a few OEMs who supported it. It was more successful in Asia and Australia, where the second-generation SuperDisk LS-240 drive and disk was released. SuperDisk worldwide ceased manufacturing in 2003.

🔗 Novels 🔗 Novels/Science fiction

The Drowned World is a 1962 science fiction novel by British writer J. G. Ballard. The novel depicts a post-apocalyptic future in which global warming has caused the majority of the Earth to become uninhabitable. The story follows a team of scientists researching ongoing environmental developments in a flooded, abandoned London. The novel is an expansion of a novella of the same title first published in Science Fiction Adventures magazine in January 1962, Vol. 4, No. 24.

In 2010, Time Magazine named The Drowned World one of the top 10 best post-apocalyptic books. The novel has been identified as a founding text in the literary genre known as climate fiction.

🔗 Occupational Safety and Health 🔗 Disability

The DataHand keyboard was introduced in 1995 by DataHand Systems, Inc. It was invented by Dale J. Retter and was produced by Industrial Innovations as early as 1992. The keyboard consists of two completely separate "keyboards", one for the left hand and one for the right, that are molded to rest the user's hands on. This allows the user to place each hand wherever it is most comfortable to them. Each finger activates five buttons, the four compass directions as well as down. The thumbs also have five buttons, one inside and two outside as well as up and down. The button modules in which the fingers rest are adjustable to best fit the user's hands—each side can be independently moved up and down, towards the palm or farther away.

This ergonomic layout allows for all typing to occur without any wrist motion, as well as without any finger extension. The keyboard layout is initially similar to a QWERTY keyboard, but the middle two columns of keys (i.e. H,Y,G...) have been delegated to sideways finger movements, and all of the keys outside of the main three rows are accessed through two additional modes, including a mode for mousing. There are three primary modes all together: letters, number and symbols, and function / mouse mode. Some practice is required. However, eventual typing speedups are possible.

Also of note is the button design—instead of being spring-loaded, the buttons are held in place with magnets and are activated using optical sensors. This was done in order to dramatically reduce the finger workload while optimizing tactile feedback.

This unconventional keyboard was seen in the Jodie Foster movie Contact (1997) as the pilot's controls for the futuristic spaceship; and the spy movie Stormbreaker (2006). The Industrial Innovations version was featured on the television series Mighty Morphin Power Rangers. A black model is used by Agent Grasso while searching for Amanda Givens' Jeep in Shadow Conspiracy (1997), starring Charlie Sheen.

After the initial prototype was released in 1995, DataHand has released the Professional and Professional II with new bodies. The Professional II also has extended programming capabilities over the Professional, being able to record macros of keystrokes for convenient use.

DataHand Systems, Inc. announced in early 2008 that it was ceasing to market and sell its keyboards. The company web site states that due to supplier issues, the company will not sell the DataHand keyboard "until a new manufacturer can be identified". However, the company plans a final, limited production run to satisfy existing customers. In January 2009, the company's website started taking orders for a "limited number of new DataHand Pro II units".