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π Andreev Bay nuclear accident of 1982
The Andreev Bay nuclear accident took place at Soviet naval base 569 in February 1982. Andreev Bay is a radioactive waste repository, located 55Β km (34 mi) northwest of Murmansk and 60Β km (37 mi) from the Norwegian border on the western shore of the Zapadnaya Litsa (Kola Peninsula). The repository entered service in 1961. In February 1982, a nuclear accident occurred in which radioactive water was released from a pool in building #5. Cleanup of the accident took place from 1983 to 1989. About 700,000 tonnes (770,000 tons) of highly radioactive water leaked into the Barents Sea during that time period. About 1,000 people took part in the cleanup effort. Vladimir Konstantinovich Bulygin, who was in charge of the naval fleet's radiation accidents, received the Hero of the Soviet Union distinction for his work.
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- "Andreev Bay nuclear accident of 1982" | 2017-10-08 | 58 Upvotes 16 Comments
π Self-Replicating Machine
A self-replicating machine is a type of autonomous robot that is capable of reproducing itself autonomously using raw materials found in the environment, thus exhibiting self-replication in a way analogous to that found in nature. The concept of self-replicating machines has been advanced and examined by Homer Jacobson, Edward F. Moore, Freeman Dyson, John von Neumann, Konrad Zuse and in more recent times by K. Eric Drexler in his book on nanotechnology, Engines of Creation (coining the term clanking replicator for such machines) and by Robert Freitas and Ralph Merkle in their review Kinematic Self-Replicating Machines which provided the first comprehensive analysis of the entire replicator design space. The future development of such technology is an integral part of several plans involving the mining of moons and asteroid belts for ore and other materials, the creation of lunar factories, and even the construction of solar power satellites in space. The von Neumann probe is one theoretical example of such a machine. Von Neumann also worked on what he called the universal constructor, a self-replicating machine that would be able to evolve and which he formalized in a cellular automata environment. Notably, Von Neumann's Self-Reproducing Automata scheme posited that open-ended evolution requires inherited information to be copied and passed to offspring separately from the self-replicating machine, an insight that preceded the discovery of the structure of the DNA molecule by Watson and Crick and how it is separately translated and replicated in the cell.
A self-replicating machine is an artificial self-replicating system that relies on conventional large-scale technology and automation. Although suggested earlier than in the late 1940's by Von Neumann, no self-replicating machine has been seen until today. Certain idiosyncratic terms are occasionally found in the literature. For example, the term clanking replicator was once used by Drexler to distinguish macroscale replicating systems from the microscopic nanorobots or "assemblers" that nanotechnology may make possible, but the term is informal and is rarely used by others in popular or technical discussions. Replicators have also been called "von Neumann machines" after John von Neumann, who first rigorously studied the idea. However, the term "von Neumann machine" is less specific and also refers to a completely unrelated computer architecture that von Neumann proposed and so its use is discouraged where accuracy is important. Von Neumann himself used the term universal constructor to describe such self-replicating machines.
Historians of machine tools, even before the numerical control era, sometimes figuratively said that machine tools were a unique class of machines because they have the ability to "reproduce themselves" by copying all of their parts. Implicit in these discussions is that a human would direct the cutting processes (later planning and programming the machines), and would then assemble the parts. The same is true for RepRaps, which are another class of machines sometimes mentioned in reference to such non-autonomous "self-replication". In contrast, machines that are truly autonomously self-replicating (like biological machines) are the main subject discussed here.
π Virtual queue
Virtual queuing is a concept used in inbound call centers. Call centers use an Automatic Call Distributor (ACD) to distribute incoming calls to specific resources (agents) in the center. ACDs hold queued calls in First In, First Out order until agents become available. From the callerβs perspective, without virtual queuing they have only two choices: wait until an agent resource becomes available, or abandon (hang up) and try again later. From the call centerβs perspective, a long queue results in many abandoned calls, repeat attempts, and customer dissatisfaction.
Virtual queuing systems allow customers to receive callbacks instead of waiting in an ACD queue. This solution is analogous to the βfast laneβ option (e.g. Disney's FASTPASS) used at amusement parks, which often have long queues to ride the various coasters and attractions. A computerized system allows park visitors to secure their place in a βvirtual queueβ rather than waiting in a physical queue.
In the brick-and-mortar retail and business world, virtual queuing for large organizations similar to the FASTPASS and Six Flags' Flash Pass, have been in use successfully since 1999 and 2001 respectively. For small businesses, the virtual queue management solutions come in two types: (a) based on SMS text notification and (b) apps on smartphones and tablet devices, with in-app notification and remote queue status views.
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- "Virtual queue" | 2015-12-26 | 73 Upvotes 23 Comments
π Project Highwater
Project Highwater was an experiment carried out as part of two of the test flights of NASA's Saturn I launch vehicle (using battleship upper stages), successfully launched into a sub-orbital trajectory from Cape Canaveral, Florida. The Highwater experiment sought to determine the effect of a large volume of water suddenly released into the ionosphere. The project answered questions about the effect of the diffusion of propellants in the event that a rocket was destroyed at high altitude.
The first flight, SA-2, took place on April 25, 1962. After the flight test of the rocket was complete and first stage shutdown occurred, explosive charges on the dummy upper stages destroyed the rocket and released 23,000 US gallons (87,000Β L) of ballast water weighing 95 short tons (86,000Β kg) into the upper atmosphere at an altitude of 65 miles (105Β km), eventually reaching an apex of 90 miles (145Β km).
The second flight, SA-3, launched on November 16, 1962, and involved the same payload. The ballast water was explosively released at the flight's peak altitude of 104 miles (167Β km). For both of these experiments, the resulting ice clouds expanded to several miles in diameter and lightning-like radio disturbances were recorded.
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- "Project Highwater" | 2022-08-29 | 66 Upvotes 9 Comments
π XZ Utils Backdoor
In February 2024, a malicious backdoor was introduced to the Linux build of the xz utility within the liblzma library in versions 5.6.0 and 5.6.1 by an account using the name "Jia Tan". The backdoor gives an attacker who possesses a specific Ed448 private key remote code execution through OpenSSH (a suite of secure networking utilities) on the affected Linux system. The issue has been given the Common Vulnerabilities and Exposures number CVE-2024-3094 and has been assigned a CVSS score of 10.0, the highest possible score.
While xz is commonly present in most Linux distributions, at the time of discovery the backdoored version had not yet been widely deployed to production systems, but was present in development versions of major distributions. The backdoor was discovered by the software developer Andres Freund, who announced his findings on 29 March 2024.
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- "XZ Utils Backdoor" | 2025-12-19 | 25 Upvotes 21 Comments
π Great Grain Robbery (1972)
The great grain robbery was the July 1972 purchase of 10 million tons of grain (mainly wheat and corn) from the United States by the Soviet Union at subsidized prices, which caused global grain prices to soar. Crop shortfalls in 1971 and 1972 forced the Soviet Union to look abroad for grain, hoping to prevent famine or crisis. Soviet negotiators worked out a deal to buy grain on credit, but quickly exceeded their credit limit. The American negotiators did not realize that both the Soviets and the world grain market had suffered shortfalls, and thus chose to subsidize the purchase. The strategy backfired and intensified the crisis with global food prices rose at least 30%, and grain stockpiles were decimated.
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- "Great Grain Robbery (1972)" | 2020-04-25 | 47 Upvotes 26 Comments
π Constraint Programming
Constraint programming (CP) is a paradigm for solving combinatorial problems that draws on a wide range of techniques from artificial intelligence, computer science, and operations research. In constraint programming, users declaratively state the constraints on the feasible solutions for a set of decision variables. Constraints differ from the common primitives of imperative programming languages in that they do not specify a step or sequence of steps to execute, but rather the properties of a solution to be found. In addition to constraints, users also need to specify a method to solve these constraints. This typically draws upon standard methods like chronological backtracking and constraint propagation, but may use customized code like a problem specific branching heuristic.
Constraint programming takes its root from and can be expressed in the form of constraint logic programming, which embeds constraints into a logic program. This variant of logic programming is due to Jaffar and Lassez, who extended in 1987 a specific class of constraints that were introduced in Prolog II. The first implementations of constraint logic programming were Prolog III, CLP(R), and CHIP.
Instead of logic programming, constraints can be mixed with functional programming, term rewriting, and imperative languages. Programming languages with built-in support for constraints include Oz (functional programming) and Kaleidoscope (imperative programming). Mostly, constraints are implemented in imperative languages via constraint solving toolkits, which are separate libraries for an existing imperative language.
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- "Constraint Programming" | 2022-09-11 | 125 Upvotes 58 Comments
π Scramble for Africa
The Scramble for Africa, also called the Partition of Africa or the Conquest of Africa, was the invasion, occupation, division, and colonisation of African territory by European powers during a short period known to historians as the New Imperialism (between 1881 and 1914). In 1870, only 10 percent of Africa was under formal European control; by 1914 this had increased to almost 90 percent of the continent, with only Ethiopia (Abyssinia), the Dervish state (a portion of present-day Somalia) and Liberia still being independent. There were multiple motivations for European colonizers, including desire for valuable resources available throughout the continent, the quest for national prestige, tensions between pairs of European powers, religious missionary zeal and internal African native politics.
The Berlin Conference of 1884, which regulated European colonisation and trade in Africa, is usually referred to as the ultimate point of the Scramble for Africa. Consequent to the political and economic rivalries among the European empires in the last quarter of the 19th century, the partitioning, or splitting up of Africa was how the Europeans avoided warring amongst themselves over Africa. The later years of the 19th century saw the transition from "informal imperialism" by military influence and economic dominance, to direct rule, bringing about colonial imperialism.
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- "Scramble for Africa" | 2019-01-31 | 26 Upvotes 14 Comments
π List of Cognitive Biases
Cognitive biases are systematic patterns of deviation from norm or rationality in judgment, and are often studied in psychology and behavioral economics.
Although the reality of most of these biases is confirmed by reproducible research, there are often controversies about how to classify these biases or how to explain them. Some are effects of information-processing rules (i.e., mental shortcuts), called heuristics, that the brain uses to produce decisions or judgments. Biases have a variety of forms and appear as cognitive ("cold") bias, such as mental noise, or motivational ("hot") bias, such as when beliefs are distorted by wishful thinking. Both effects can be present at the same time.
There are also controversies over some of these biases as to whether they count as useless or irrational, or whether they result in useful attitudes or behavior. For example, when getting to know others, people tend to ask leading questions which seem biased towards confirming their assumptions about the person. However, this kind of confirmation bias has also been argued to be an example of social skill: a way to establish a connection with the other person.
Although this research overwhelmingly involves human subjects, some findings that demonstrate bias have been found in non-human animals as well. For example, loss aversion has been shown in monkeys and hyperbolic discounting has been observed in rats, pigeons, and monkeys.
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- "List of Cognitive Biases" | 2019-07-02 | 214 Upvotes 64 Comments
- "List of cognitive biases" | 2017-10-09 | 18 Upvotes 4 Comments
- "List of cognitive biases" | 2013-12-04 | 168 Upvotes 62 Comments
- "List of cognitive biases" | 2012-03-26 | 101 Upvotes 17 Comments
π Glenn Greenwald on Wikipedia's Neutrality
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- "Glenn Greenwald on Wikipedia's Neutrality" | 2023-08-15 | 14 Upvotes 14 Comments