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🔗 France 🔗 Celts 🔗 Mythology

Ys (pronounced EESS), also spelled Is or Kêr-Is in Breton, and Ville d'Ys in French, is a mythical city on the coast of Brittany that was swallowed up by the ocean. Most versions of the legend place the city in the Baie de Douarnenez.

Noblesse oblige (; French: [nɔblɛs ɔbliʒ]) is a French expression used in English meaning that nobility extends beyond mere entitlements and requires the person who holds such a status to fulfill social responsibilities. For example, a primary obligation of a nobleman could include generosity towards those around him.

The Oxford English Dictionary states that the term suggests "noble ancestry constrains to honourable behaviour; privilege entails responsibility."

The Dictionnaire de l'Académie française defines it thus:

1. Whoever claims to be noble must conduct himself nobly.
2. (Figuratively) One must act in a fashion that conforms to one's position and privileges with which one has been born, bestowed and/or has earned.

🔗 United States 🔗 Environment 🔗 Disaster management 🔗 Medicine 🔗 Occupational Safety and Health 🔗 Energy 🔗 Medicine/Toxicology 🔗 Indigenous peoples of North America 🔗 United States/New Mexico 🔗 United States/Superfund

The Church Rock uranium mill spill occurred in the U.S. state of New Mexico on July 16, 1979, when United Nuclear Corporation's tailings disposal pond at its uranium mill in Church Rock breached its dam. The spill remains the largest release of radioactive material in U.S. history, having released more radioactivity than the Three Mile Island accident four months earlier.

The mill, which operated from June 1977 to May 1982, was located on privately owned land about 17 miles (27 km) northeast of Gallup, New Mexico, and was bordered to the north and southwest by Navajo Nation Tribal Trust lands. The milling of uranium ore produced an acidic slurry of ground waste rock and fluid (tailings) that was pumped to the tailings disposal area. The breach released more than 1,100 short tons (1,000 t) of solid radioactive mill waste and 94 million US gallons (360,000 m³) of acidic, radioactive tailings solution into the Puerco River through Pipeline Arroyo. An estimated 1.36 short tons (1.23 t) of uranium and 46 curies of alpha contaminants traveled 80 miles (130 km) downstream to Navajo County, Arizona, and onto the Navajo Nation. In addition to being radioactive and acidic, the spill contained toxic metals and sulfates. The spill contaminated groundwater and rendered the Puerco unusable to local residents, mostly Navajo peoples who used the river's water for drinking, irrigation, and livestock. They were not warned for days of the toxic dangers from the spill.

The governor of New Mexico, Bruce King, refused the Navajo Nation's request that the site be declared a federal disaster area, limiting aid to affected residents. The nuclear contamination event received less media coverage than that of Three Mile Island, possibly because it occurred in a very rural area not served by major media. The spill also happened in Native American country, among a community who reportedly did not have their concerns addressed by medical authorities.

In 2003, the Church Rock Chapter of the Navajo Nation began the Church Rock Uranium Monitoring Project to assess environmental impacts of abandoned uranium mines; it found significant radiation from both natural and mining sources in the area. As of 2016, the EPA National Priorities List included the Church Rock tailings storage site, where "groundwater migration is not under control".

🔗 Environment 🔗 Urban studies and planning 🔗 Chicago 🔗 Illinois

The Tunnel and Reservoir Plan (abbreviated TARP and more commonly known as the Deep Tunnel Project or the Chicago Deep Tunnel) is a large civil engineering project that aims to reduce flooding in the metropolitan Chicago area, and to reduce the harmful effects of flushing raw sewage into Lake Michigan by diverting storm water and sewage into temporary holding reservoirs. The megaproject is one of the largest civil engineering projects ever undertaken in terms of scope, cost and timeframe. Commissioned in the mid-1970s, the project is managed by the Metropolitan Water Reclamation District of Greater Chicago. Completion of the system is not anticipated until 2029, but substantial portions of the system have already opened and are currently operational. Across 30 years of construction, over $3 billion has been spent on the project.

🔗 Physics 🔗 China 🔗 Astronomy 🔗 History of Science 🔗 Astronomy/Astronomical objects 🔗 Arab world

SN 1006 was a supernova that is likely the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude, and exceeding roughly sixteen times the brightness of Venus. Appearing between April 30 and May 1, 1006 AD in the constellation of Lupus, this "guest star" was described by observers across the modern day countries of China, Japan, Iraq, Egypt, and the continent of Europe, and possibly recorded in North American petroglyphs. Some reports state it was clearly visible in the daytime. Modern astronomers now consider its distance from Earth to be about 7,200 light-years.

🔗 Game theory

The Price of Anarchy (PoA) is a concept in economics and game theory that measures how the efficiency of a system degrades due to selfish behavior of its agents. It is a general notion that can be extended to diverse systems and notions of efficiency. For example, consider the system of transportation of a city and many agents trying to go from some initial location to a destination. Let efficiency in this case mean the average time for an agent to reach the destination. In the 'centralized' solution, a central authority can tell each agent which path to take in order to minimize the average travel time. In the 'decentralized' version, each agent chooses its own path. The Price of Anarchy measures the ratio between average travel time in the two cases.

Usually the system is modeled as a game and the efficiency is some function of the outcomes (e.g. maximum delay in a network, congestion in a transportation system, social welfare in an auction, ...). Different concepts of equilibrium can be used to model the selfish behavior of the agents, among which the most common is the Nash equilibrium. Different flavors of Nash equilibrium lead to variations of the notion of Price of Anarchy as Pure Price of Anarchy (for deterministic equilibria), Mixed Price of Anarchy (for randomized equilibria), and Bayes–Nash Price of Anarchy (for games with incomplete information). Solution concepts other than Nash equilibrium lead to variations such as the Price of Sinking.

The term Price of Anarchy was first used by Elias Koutsoupias and Christos Papadimitriou, but the idea of measuring inefficiency of equilibrium is older. The concept in its current form was designed to be the analogue of the 'approximation ratio' in an approximation algorithm or the 'competitive ratio' in an online algorithm. This is in the context of the current trend of analyzing games using algorithmic lenses (algorithmic game theory).

🔗 Game theory

Sprouts is a paper-and-pencil game that can be enjoyed simply by both adults and children. Yet it also can be analyzed for its significant mathematical properties. It was invented by mathematicians John Horton Conway and Michael S. Paterson at Cambridge University in the early 1960s. Setup is even simpler than the popular Dots and Boxes game, but game-play develops much more artistically and organically.

🔗 Computer science 🔗 Statistics

The Jaccard index, also known as the Jaccard similarity coefficient, is a statistic used for gauging the similarity and diversity of sample sets. It was developed by Grove Karl Gilbert in 1884 as his ratio of verification (v) and now is frequently referred to as the Critical Success Index in meteorology. It was later developed independently by Paul Jaccard, originally giving the French name coefficient de communauté, and independently formulated again by T. Tanimoto. Thus, the Tanimoto index or Tanimoto coefficient are also used in some fields. However, they are identical in generally taking the ratio of Intersection over Union. The Jaccard coefficient measures similarity between finite sample sets, and is defined as the size of the intersection divided by the size of the union of the sample sets:

${\displaystyle J(A,B)={{|A\cap B|} \over {|A\cup B|}}={{|A\cap B|} \over {|A|+|B|-|A\cap B|}}.}$

Note that by design, ${\displaystyle 0\leq J(A,B)\leq 1.}$ If A intersection B is empty, then J(A,B) = 0. The Jaccard coefficient is widely used in computer science, ecology, genomics, and other sciences, where binary or binarized data are used. Both the exact solution and approximation methods are available for hypothesis testing with the Jaccard coefficient.

Jaccard similarity also applies to bags, i.e., Multisets. This has a similar formula, but the symbols mean bag intersection and bag sum (not union). The maximum value is 1/2.

${\displaystyle J(A,B)={{|A\cap B|} \over {|A\uplus B|}}={{|A\cap B|} \over {|A|+|B|}}.}$

The Jaccard distance, which measures dissimilarity between sample sets, is complementary to the Jaccard coefficient and is obtained by subtracting the Jaccard coefficient from 1, or, equivalently, by dividing the difference of the sizes of the union and the intersection of two sets by the size of the union:

${\displaystyle d_{J}(A,B)=1-J(A,B)={{|A\cup B|-|A\cap B|} \over |A\cup B|}.}$

An alternative interpretation of the Jaccard distance is as the ratio of the size of the symmetric difference ${\displaystyle A\triangle B=(A\cup B)-(A\cap B)}$ to the union. Jaccard distance is commonly used to calculate an n × n matrix for clustering and multidimensional scaling of n sample sets.

This distance is a metric on the collection of all finite sets.

There is also a version of the Jaccard distance for measures, including probability measures. If ${\displaystyle \mu }$ is a measure on a measurable space ${\displaystyle X}$, then we define the Jaccard coefficient by

${\displaystyle J_{\mu }(A,B)={{\mu (A\cap B)} \over {\mu (A\cup B)}},}$

and the Jaccard distance by

${\displaystyle d_{\mu }(A,B)=1-J_{\mu }(A,B)={{\mu (A\triangle B)} \over {\mu (A\cup B)}}.}$

Care must be taken if ${\displaystyle \mu (A\cup B)=0}$ or ${\displaystyle \infty }$, since these formulas are not well defined in these cases.

The MinHash min-wise independent permutations locality sensitive hashing scheme may be used to efficiently compute an accurate estimate of the Jaccard similarity coefficient of pairs of sets, where each set is represented by a constant-sized signature derived from the minimum values of a hash function.

🔗 Education 🔗 Engineering

Regulation and licensure in engineering is established by various jurisdictions of the world to encourage public welfare, safety, well-being and other interests of the general public and to define the licensure process through which an engineer becomes authorized to practice engineering and/or provide engineering professional services to the public.

As with many other professions, the professional status and the actual practice of professional engineering is legally defined and protected by law in some jurisdictions. Additionally, some jurisdictions permit only licensed engineers (sometimes called registered engineers) to "practice engineering," which requires careful definition in order to resolve potential overlap or ambiguity with respect to certain other professions which may or may not be themselves regulated (e.g. "scientists," or "architects"). Relatedly, jurisdictions that license according to particular engineering discipline need to define those boundaries carefully as well so that practitioners understand what they are permitted to do.

In many cases, only a state or provincial licensed/registered engineer has the authority to take legal responsibility for engineering work or projects (typically via a seal or stamp on the relevant design documentation). Regulations may require that only a licensed or registered engineer can sign, seal or stamp technical documentation such as reports, plans, engineering drawings and calculations for study estimate or valuation or carry out design analysis, repair, servicing, maintenance or supervision of engineering work, process or project. In cases where public safety, property or welfare is concerned, it may be required that an engineer be licensed or registered – though some jurisdictions have an "industrial exemption" that permits engineers to work internally for an organization without licensure so long as they are not making final decisions to release product to the public or offering engineering services directly to the public (e.g. consultant).

Expert witness or opinion in courts or before government committees or commissions can be provided by experts in the respective field, which is sometimes given by a registered or licensed engineer in some jurisdictions.