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π DNA origami
DNA origami is the nanoscale folding of DNA to create non-arbitrary two- and three-dimensional shapes at the nanoscale. The specificity of the interactions between complementary base pairs make DNA a useful construction material, through design of its base sequences. DNA is a well-understood material that is suitable for creating scaffolds that hold other molecules in place or to create structures all on its own.
DNA origami was the cover story of Nature on March 16, 2006. Since then, DNA origami has progressed past an art form and has found a number of applications from drug delivery systems to uses as circuitry in plasmonic devices; however, most applications remain in a concept or testing phase.
Discussed on
- "DNA origami" | 2016-12-22 | 37 Upvotes 5 Comments
π Gimli Glider
Air Canada FlightΒ 143 was a Canadian scheduled domestic passenger flight between Montreal and Edmonton that ran out of fuel on JulyΒ 23, 1983, at an altitude of 41,000 feet (12,000Β m), midway through the flight. The crew was able to glide the Boeing 767 aircraft safely to an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba, that had been turned into a motor racing track. This unusual aviation incident earned the aircraft the nickname "Gimli Glider".
The subsequent investigation revealed that a combination of company failures, human errors and confusion over unit measures had led to the aircraft being refuelled with insufficient fuel for the planned flight.
Discussed on
- "Gimli Glider" | 2016-12-18 | 385 Upvotes 198 Comments
- "Gimli Glider" | 2014-05-01 | 176 Upvotes 80 Comments
- "Gimli Glider: When systems go wrong." | 2009-10-23 | 26 Upvotes 9 Comments
π List of wikileaks mirrors deleted on Wikipedia
Discussed on
- "List of wikileaks mirrors deleted on Wikipedia" | 2010-12-09 | 18 Upvotes 3 Comments
π Bookland
"Bookland" is the informal name for the Unique Country Code (UCC) prefix allocated in the 1980s for European Article Number (EAN) identifiers of published books, regardless of country of origin, so that the EAN namespace can catalogue books by ISBN rather than maintaining a redundant parallel numbering system. In other words, Bookland is a fictitious country that exists solely in EAN for the purposes of non-geographically cataloguing books in the otherwise geographically keyed EAN coding system.
π The Magical Number 7 plus or minus 2
"The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information" is one of the most highly cited papers in psychology. It was published in 1956 in Psychological Review by the cognitive psychologist George A. Miller of Harvard University's Department of Psychology. It is often interpreted to argue that the number of objects an average human can hold in short-term memory is 7 Β± 2. This has occasionally been referred to as Miller's law.
Discussed on
- "The Magical Number Seven, Plus or Minus Two" | 2021-07-14 | 48 Upvotes 11 Comments
- "The Magical Number 7 plus or minus 2" | 2010-11-08 | 21 Upvotes 9 Comments
π Cool stuff you can do with netcat
netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP. The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.
Its list of features includes port scanning, transferring files, and port listening, and it can be used as a backdoor.
Discussed on
- "Cool stuff you can do with netcat" | 2010-11-05 | 126 Upvotes 39 Comments
π 1961 Goldsboro B-52 crash
The 1961 Goldsboro B-52 crash was an accident that occurred near Goldsboro, North Carolina, on 23 January 1961. A Boeing B-52 Stratofortress carrying two 3β4-megaton Mark 39 nuclear bombs broke up in mid-air, dropping its nuclear payload in the process. The pilot in command, Walter Scott Tulloch, ordered the crew to eject at 9,000 feet (2,700Β m). Five crewmen successfully ejected or bailed out of the aircraft and landed safely, another ejected, but did not survive the landing, and two died in the crash. Information declassified in 2013 showed that one of the bombs came very close to detonating.
Discussed on
- "1961 Goldsboro B-52 crash" | 2016-12-16 | 10 Upvotes 3 Comments
π Burned house horizon
In the archaeology of Neolithic Europe, the burned house horizon is the geographical extent of the phenomenon of presumably intentionally burned settlements.
This was a widespread and long-lasting tradition in what is now Southeastern and Eastern Europe, lasting from as early as 6500 BCE (the beginning of the Neolithic) to as late as 2000 BCE (the end of the Chalcolithic and the beginning of the Bronze Age). A notable representative of this tradition is the Cucuteni-Trypillian culture, which was centered on the burned-house horizon both geographically and temporally.
There is still a discussion in the study of Neolithic and Eneolithic Europe whether the majority of burned houses were intentionally set alight or not.
Although there is still debate about the why house burning was practiced, the evidence seems to indicate that it was highly unlikely to have been accidental. There is also debate about why this would have been done deliberately and regularly, since these burnings could destroy the entire settlement. However, in recent years, the consensus has begun to gel around the "domicide" theory supported by Tringham, Stevanovic and others.
Cucuteni-Trypillian settlements were completely burned every 75β80 years, leaving behind successive layers consisting mostly of large amounts of rubble from the collapsed wattle-and-daub walls. This rubble was mostly ceramic material that had been created as the raw clay used in the daub of the walls became vitrified from the intense heat that would have turned it a bright orange color during the conflagration that destroyed the buildings, much the same way that raw clay objects are turned into ceramic products during the firing process in a kiln. Moreover, the sheer amount of fired-clay rubble found within every house of a settlement indicates that a fire of enormous intensity would have raged through the entire community to have created the volume of material found.
Discussed on
- "Burned House Horizon" | 2021-03-06 | 331 Upvotes 146 Comments
- "Burned house horizon" | 2016-12-07 | 180 Upvotes 62 Comments
π The German tank problem
In the statistical theory of estimation, the German tank problem consists of estimating the maximum of a discrete uniform distribution from sampling without replacement. In simple terms, suppose we have an unknown number of items which are sequentially numbered from 1 to N. We take a random sample of these items and observe their sequence numbers; the problem is to estimate N from these observed numbers.
The problem can be approached using either frequentist inference or Bayesian inference, leading to different results. Estimating the population maximum based on a single sample yields divergent results, whereas estimation based on multiple samples is a practical estimation question whose answer is simple (especially in the frequentist setting) but not obvious (especially in the Bayesian setting).
The problem is named after its historical application by Allied forces in World War II to the estimation of the monthly rate of German tank production from very few data. This exploited the manufacturing practice of assigning and attaching ascending sequences of serial numbers to tank components (chassis, gearbox, engine, wheels), with some of the tanks eventually being captured in battle by Allied forces.
Discussed on
- "German Tank Problem" | 2023-11-26 | 39 Upvotes 7 Comments
- "The German tank problem" | 2016-12-03 | 64 Upvotes 6 Comments
- "German tank problem" | 2014-02-21 | 231 Upvotes 83 Comments
- "German tank problem" | 2011-03-02 | 28 Upvotes 1 Comments
- "The German Tank Problem" | 2009-06-23 | 103 Upvotes 18 Comments
π Buy Nothing Day
Buy Nothing Day (BND) is an international day of protest against consumerism. In North America, the United Kingdom, Finland and Sweden, Buy Nothing Day is held the day after U.S. Thanksgiving, concurrent to Black Friday; elsewhere, it is held the following day, which is the last Saturday in November. Buy Nothing Day was founded in Vancouver by artist Ted Dave and subsequently promoted by Adbusters, based in Canada.
The first Buy Nothing Day was organized in Canada in September 1992 "as a day for society to examine the issue of overconsumption." In 1997, it was moved to the Friday after American Thanksgiving, also called "Black Friday", which is one of the ten busiest shopping days in the United States. In 2000, some advertisements by Adbusters promoting Buy Nothing Day were denied advertising time by almost all major television networks except for CNN. Soon, campaigns started appearing in the United States, the United Kingdom, Israel, Austria, Germany, New Zealand, Japan, the Netherlands, France, Norway and Sweden. Participation now includes more than 65 nations.
Discussed on
- "Buy Nothing Day" | 2021-11-26 | 50 Upvotes 3 Comments
- "Buy Nothing Day" | 2016-11-25 | 27 Upvotes 2 Comments