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🔗 Indigenous peoples of the Americas 🔗 Peru 🔗 Argentina

The Inca road system (often spelled Inka road system and known as Qhapaq Ñan meaning "royal road" in Quechua) was the most extensive and advanced transportation system in pre-Columbian South America. It was at least 40,000 kilometres (25,000 mi) long. The construction of the roads required a large expenditure of time and effort.

The network was composed of formal roads carefully planned, engineered, built, marked and maintained; paved where necessary, with stairways to gain elevation, bridges and accessory constructions such as retaining walls, and water drainage system. It was based on two north-south roads: one along the coast and the second and most important inland and up the mountains, both with numerous branches. It can be directly compared with the road network built during the Roman Empire, although the Inka road system was built one thousand years later. The road system allowed for the transfer of information, goods, soldiers and persons, without the use of wheels, within the Tawantinsuyu or Inka Empire throughout a territory with an extension was almost 2,000,000 km² (770,000 sq mi) and inhabited by about 12 million people.

The roads were bordered, at intervals, with buildings to allow the most effective usage: at short distance there were relay stations for chasquis, the running messengers; at a one-day walking interval tambos allowed support to the road users and the flocks of carrying llamas. Administrative centers with warehouses for re-distribution of goods were found along the roads. Towards the boundaries of the Inka Empire and in new conquered areas pukaras (fortresses) were found.

Part of the road network was built by cultures that precede the Inka Empire, notably the Wari culture in the northern central Peru and the Tiwanaku culture in Bolivia. Different organizations such as UNESCO and IUCN have been working to protect the network in collaboration with the governments and communities of the six countries (Colombia, Ecuador, Peru, Bolivia, Chile and Argentina) through which the Great Inka Road passes.

In modern times the roads see heavy use from tourism, such as the Inca Trail to Machu Picchu, well known by trekkers, connecting Ollantaytambo with Machu Picchu.

🔗 Lists

This is a list of countries and territories by home ownership rate, which is the ratio of owner-occupied units to total residential units in a specified area.

🔗 Companies 🔗 Video games 🔗 Lists 🔗 Business 🔗 Video games/Nintendo 🔗 Popular Culture 🔗 Industrial design 🔗 Video games/Sega

The list of commercial failures in video games includes any video game software on any platform, and any video game console hardware, of all time. As a hit-driven business, the great majority of the video game industry's software releases have been commercial failures. In the early 21st century, industry commentators made these general estimates: 10% of published games generated 90% of revenue; that around 3% of PC games and 15% of console games have global sales of more than 100,000 units per year, with even this level insufficient to make high-budget games profitable; and that about 20% of games make any profit.

Some of these failure events have drastically changed the video game market since its origin in the late 1970s. For example, the failures of E.T. and Pac-Man for the Atari 2600 contributed to the video game crash of 1983. Some games, though commercial failures, are well received by certain groups of gamers and are considered cult games.

🔗 United States 🔗 Law

Lemon laws are United States state laws that provide a remedy for purchasers of cars and other consumer goods in order to compensate for products that repeatedly fail to meet standards of quality and performance. Although many types of products can be defective, the term "lemon" is mostly used to describe defective motor vehicles, such as cars, trucks, and motorcycles.

🔗 Religion 🔗 Death 🔗 Classical Greece and Rome 🔗 Greece

The Nekromanteion (Greek: Νεκρομαντεῖον) was an ancient Greek temple of necromancy devoted to Hades and Persephone. According to tradition, it was located on the banks of the Acheron river in Epirus, near the ancient city of Ephyra. This site was believed by devotees to be the door to Hades, the realm of the dead. The site is at the meeting point of the Acheron, Pyriphlegethon and Cocytus rivers, believed to flow through and water the kingdom of Hades. The meaning of the names of the rivers has been interpreted to be "joyless", "burning coals" and "lament", respectively.

A site in Mesopotamos, Epirus was proposed as the site of the Necromanteion in 1958, but this identification is now questioned.

🔗 Biography 🔗 Systems 🔗 Biography/arts and entertainment

John Gall (September 18, 1925 – December 15, 2014) was an American author and retired pediatrician. Gall is known for his 1975 book General systemantics: an essay on how systems work, and especially how they fail..., a critique of systems theory. One of the statements from this book has become known as Gall's law.

🔗 Biography 🔗 California 🔗 California/San Francisco Bay Area 🔗 Mathematics 🔗 Iran 🔗 Women scientists 🔗 Biography/science and academia 🔗 Stanford University

Maryam Mirzakhani (Persian: مریم میرزاخانی‎, pronounced [mæɾˈjæm miːɾzɑːxɑːˈniː]; 12 May 1977 – 14 July 2017) was an Iranian mathematician and a professor of mathematics at Stanford University. Her research topics included Teichmüller theory, hyperbolic geometry, ergodic theory, and symplectic geometry. In 2005, as a result of her research, she was honored in Popular Science's fourth annual "Brilliant 10" in which she was acknowledged as one of the top 10 young minds who have pushed their fields in innovative directions.

On 13 August 2014, Mirzakhani was honored with the Fields Medal, the most prestigious award in mathematics. Thus, she became both the first, and to date, the only woman and the first Iranian to be honored with the award. The award committee cited her work in "the dynamics and geometry of Riemann surfaces and their moduli spaces".

On 14 July 2017, Mirzakhani died of breast cancer at the age of 40.

🔗 Computing 🔗 Computing/Software

86-DOS is a discontinued operating system developed and marketed by Seattle Computer Products (SCP) for its Intel 8086-based computer kit. Initially known as QDOS (Quick and Dirty Operating System), the name was changed to 86-DOS once SCP started licensing the operating system in 1980.

86-DOS had a command structure and application programming interface that imitated that of Digital Research's CP/M operating system, which made it easy to port programs from the latter. The system was licensed and then purchased by Microsoft and developed further as MS-DOS and PC DOS.

🔗 Mathematics 🔗 Statistics

In statistical hypothesis testing, a type I error is the rejection of a true null hypothesis (also known as a "false positive" finding or conclusion), while a type II error is the non-rejection of a false null hypothesis (also known as a "false negative" finding or conclusion). Much of statistical theory revolves around the minimization of one or both of these errors, though the complete elimination of either is a statistical impossibility for non-deterministic algorithms. By selecting a low threshold (cut-off) value and modifying the alpha (p) level, the quality of the hypothesis test can be increased. The knowledge of Type I errors and Type II errors is widely used in medical science, biometrics and computer science.

🔗 Computer science

HAKMEM, alternatively known as AI Memo 239, is a February 1972 "memo" (technical report) of the MIT AI Lab containing a wide variety of hacks, including useful and clever algorithms for mathematical computation, some number theory and schematic diagrams for hardware — in Guy L. Steele's words, "a bizarre and eclectic potpourri of technical trivia". Contributors included about two dozen members and associates of the AI Lab. The title of the report is short for "hacks memo", abbreviated to six upper case characters that would fit in a single PDP-10 machine word (using a six-bit character set).