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🔗 Computing 🔗 Mathematics

The Luhn algorithm or Luhn formula, also known as the "modulus 10" or "mod 10" algorithm, named after its creator, IBM scientist Hans Peter Luhn, is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers in the United States, Canadian Social Insurance Numbers, Israel ID Numbers, South African ID Numbers, Greek Social Security Numbers (ΑΜΚΑ), and survey codes appearing on McDonald's, Taco Bell, and Tractor Supply Co. receipts. It is described in U.S. Patent No. 2,950,048, filed on January 6, 1954, and granted on August 23, 1960.

The algorithm is in the public domain and is in wide use today. It is specified in ISO/IEC 7812-1. It is not intended to be a cryptographically secure hash function; it was designed to protect against accidental errors, not malicious attacks. Most credit cards and many government identification numbers use the algorithm as a simple method of distinguishing valid numbers from mistyped or otherwise incorrect numbers.

🔗 Technology 🔗 Physics 🔗 Physics/Fluid Dynamics

Fluidics, or fluidic logic, is the use of a fluid to perform analog or digital operations similar to those performed with electronics.

The physical basis of fluidics is pneumatics and hydraulics, based on the theoretical foundation of fluid dynamics. The term fluidics is normally used when devices have no moving parts, so ordinary hydraulic components such as hydraulic cylinders and spool valves are not considered or referred to as fluidic devices.

A jet of fluid can be deflected by a weaker jet striking it at the side. This provides nonlinear amplification, similar to the transistor used in electronic digital logic. It is used mostly in environments where electronic digital logic would be unreliable, as in systems exposed to high levels of electromagnetic interference or ionizing radiation.

Nanotechnology considers fluidics as one of its instruments. In this domain, effects such as fluid-solid and fluid-fluid interface forces are often highly significant. Fluidics have also been used for military applications.

🔗 Science

In combinatorial mathematics, an Aztec diamond of order n consists of all squares of a square lattice whose centers (x,y) satisfy |x| + |y| ≤ n. Here n is a fixed integer, and the square lattice consists of unit squares with the origin as a vertex of 4 of them, so that both x and y are half-integers.

The Aztec diamond theorem states that the number of domino tilings of the Aztec diamond of order n is 2^n(n+1)/2. The Arctic Circle theorem says that a random tiling of a large Aztec diamond tends to be frozen outside a certain circle.

It is common to color the tiles in the following fashion. First consider a checkerboard coloring of the diamond. Each tile will cover exactly one black square. Vertical tiles where the top square covers a black square, is colored in one color, and the other vertical tiles in a second. Similarly for horizontal tiles.

Knuth has also defined Aztec diamonds of order n + 1/2. They are identical with the polyominoes associated with the centered square numbers.

🔗 Computing 🔗 Linux

The Tanenbaum–Torvalds debate was a written debate between Andrew S. Tanenbaum and Linus Torvalds, regarding the Linux kernel and kernel architecture in general. Tanenbaum, the creator of Minix, began the debate in 1992 on the Usenet discussion group comp.os.minix, arguing that microkernels are superior to monolithic kernels and therefore Linux was, even in 1992, obsolete.

The debate has sometimes been considered a flame war.

🔗 Medicine 🔗 Sociology 🔗 Physiology 🔗 Medicine/Cardiology 🔗 Medicine/Society and Medicine

The Roseto effect is the phenomenon by which a close-knit community experiences a reduced rate of heart disease. The effect is named for Roseto, Pennsylvania. The Roseto effect was first noticed in 1961 when the local Roseto doctor encountered Dr. Stewart Wolf, then head of Medicine of the University of Oklahoma, and they discussed, over a couple of beers, the unusually low rate of myocardial infarction in the Italian American community of Roseto compared with other locations. Many studies followed, including a 50-year study comparing Roseto to nearby Bangor. As the original authors had predicted, as the Roseto cohort shed their Italian social structure and became more Americanized in the years following the initial study, heart disease rates increased, becoming similar to those of neighboring towns.

From 1954 to 1961, Roseto had nearly no heart attacks for the otherwise high-risk group of men 55 to 64, and men over 65 had a death rate of 1% while the national average was 2%. Widowers outnumbered widows, as well.

These statistics were at odds with a number of other factors observed in the community. They smoked unfiltered stogies, drank wine "with seeming abandon" in lieu of milk and soft drinks, skipped the Mediterranean diet in favor of meatballs and sausages fried in lard with hard and soft cheeses. The men worked in the slate quarries where they contracted illnesses from gases and dust. Roseto also had no crime, and very few applications for public assistance.

Wolf attributed Rosetans' lower heart disease rate to lower stress. "'The community,' Wolf says, 'was very cohesive. There was no keeping up with the Joneses. Houses were very close together, and everyone lived more or less alike.'" Elders were revered and incorporated into community life. Housewives were respected, and fathers ran the families.

🔗 Disambiguation

Doom may refer to:

🔗 United States/U.S. Government 🔗 United States 🔗 International relations 🔗 Germany 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Europe 🔗 Italy 🔗 Sociology 🔗 Organizations 🔗 Military history/German military history 🔗 Military history/French military history 🔗 Military history/Cold War 🔗 Cold War 🔗 Military history/Dutch military history 🔗 Rome 🔗 European history 🔗 Military history/Italian military history 🔗 Military history/European military history 🔗 Military history/British military history 🔗 Military history/Post-Cold War 🔗 NATO

Operation Gladio is the codename for clandestine "stay-behind" operations of armed resistance that were organized by the Western Union (WU), and subsequently by NATO and the CIA, in collaboration with several European intelligence agencies. The operation was designed for a potential Warsaw Pact invasion and conquest of Europe. Although Gladio specifically refers to the Italian branch of the NATO stay-behind organizations, "Operation Gladio" is used as an informal name for all of them. Stay-behind operations were prepared in many NATO member countries, and some neutral countries.

During the Cold War, some anti-communist armed groups engaged in the harassment of left-wing parties, torture, terrorist attacks, and massacres in countries such as Italy. The role of the CIA and other intelligence organisations in Gladio—the extent of its activities during the Cold War era and any responsibility for terrorist attacks perpetrated in Italy during the "Years of Lead" (late 1960s–early 1980s)—is the subject of debate.

In 1990, the European Parliament adopted a resolution alleging that military secret services in certain member states were involved in serious terrorism and crime, whether or not their superiors were aware. The resolution also urged investigations by the judiciaries of the countries in which those armies operated, so that their modus operandi and actual extension would be revealed. To date, only Italy, Switzerland and Belgium have had parliamentary inquiries into the matter.

The three inquiries reached differing conclusions as regarded different countries. Guido Salvini, a judge who worked in the Italian Massacres Commission, concluded that some right-wing terrorist organizations of the Years of Lead (La Fenice, National Vanguard and Ordine Nuovo) were the trench troops of a secret army, remotely controlled by exponents of the Italian state apparatus and linked to the CIA. Salvini said that the CIA encouraged them to commit atrocities. The Swiss inquiry found that British intelligence secretly cooperated with their army in an operation named P-26 and provided training in combat, communications, and sabotage. It also discovered that P-26 not only would organize resistance in case of a Soviet invasion, but would also become active should the left succeed in achieving a parliamentary majority. The Belgian inquiry could find no conclusive information on their army. No links between them and terrorist attacks were found, and the inquiry noted that the Belgian secret services refused to provide the identity of agents, which could have eliminated all doubts. A 2000 Italian parliamentary report from the left wing coalition Gruppo Democratici di Sinistra l'Ulivo reported that terrorist massacres and bombings had been organised or promoted or supported by men inside Italian state institutions who were linked to American intelligence. The report also said the United States was guilty of promoting the strategy of tension. Operation Gladio is also suspected to have been activated to counter existing left-wing parliamentary majorities in Europe.

The US State Department published a communiqué in January 2006 that stated claims the United States ordered, supported, or authorized terrorism by stay-behind units, and US-sponsored "false flag" operations are rehashed former Soviet disinformation based on documents that the Soviets forged.

The word gladio is the Italian form of gladius, a type of Roman shortsword.

🔗 Germany 🔗 Law Enforcement 🔗 Typography

The FE-Schrift or Fälschungserschwerende Schrift (forgery-impeding typeface) is a sans serif typeface introduced for use on licence plates. Its monospaced letters and numbers are slightly disproportionate to prevent easy modification and to improve machine readability. It has been developed in Germany where it has been mandatory since November 2000.

The abbreviation "FE" is derived from the compound German adjective "fälschungserschwerend" combining the noun "Fälschung" (falsification) and the verb "erschweren" (to hinder). "Schrift" means font in German. Other countries have later introduced the same or a derived typeface for license plates taking advantage of the proven design for the FE-Schrift.

🔗 Technology 🔗 Spaceflight 🔗 Solar System/Mars 🔗 Solar System

Terraforming of Mars is a procedure that would comprise of planetary engineering project or concurrent projects, with the goal of transforming the planet from one hostile to terrestrial life to one that can sustainably host humans and other lifeforms free of protection or mediation. The process would presumably involve the rehabilitation of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, and the installation of a novel ecological system or systems.

Justifications for choosing Mars over other potential terraforming targets include the presence of water and a geological history that suggests it once harbored a dense atmosphere similar to Earth’s. Hazards and difficulties include low gravity, low light levels relative to Earth’s, and the lack of a magnetic field.

Objections to the project include questions about its feasibility, general ethical concerns about terraforming, and the considerable cost that such an undertaking would involve. Reasons for terraforming the planet include allaying concerns about resource use and depletion on Earth and arguments that the altering and subsequent or concurrent settlement of other planets decreases the odds of humanity's extinction.

Disagreement exists about whether current technology could render the planet habitable.

🔗 United States 🔗 Television 🔗 Law 🔗 Comedy 🔗 Animation 🔗 Popular Culture 🔗 South Park 🔗 United States/American television 🔗 United States/Colorado 🔗 Star Wars 🔗 United States/Animation - American animation

In a jury trial, a Chewbacca defense is a legal strategy in which a criminal defense lawyer tries to confuse the jury rather than refute the case of the prosecutor. It is an intentional distraction or obfuscation.

As a Chewbacca defense distracts and misleads, it is an example of a red herring. It is also an example of an irrelevant conclusion, a type of informal fallacy in which one making an argument fails to address the issue in question. Often an opposing counsel can legally object to such arguments by declaring them irrelevant, character evidence, or argumentative.

The name Chewbacca defense comes from "Chef Aid", an episode of the American animated series South Park. The episode, which premiered on October 7, 1998, satirizes the O. J. Simpson murder trial—particularly attorney Johnnie Cochran's closing argument for the defense. In the episode, Cochran (voiced by Trey Parker) bases his argument on a false premise about the 1983 film Return of the Jedi. He asks the jury why a Wookiee like Chewbacca would want to live on Endor with the much smaller Ewoks when "it does not make sense". He argues that if Chewbacca living on Endor does not make sense—and if even mentioning Chewbacca in the case does not make sense—then the jury must acquit.

In the Simpson murder trial, the real Johnnie Cochran tried to convince jurors that a glove found at the crime scene, alleged to have been left by the killer, could not be Simpson's because it did not fit Simpson's hand. Because the prosecution relied on the glove as evidence of Simpson's presence at the scene, Cochran argued that the lack of fit proved Simpson's innocence: "It makes no sense; it doesn't fit; if it doesn't fit, you must acquit." "If it doesn't fit, you must acquit" was a refrain that Cochran also used in response to other points of the case.