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🔗 Physics 🔗 Soil

The angle of repose, or critical angle of repose, of a granular material is the steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without slumping. At this angle, the material on the slope face is on the verge of sliding. The angle of repose can range from 0° to 90°. The morphology of the material affects the angle of repose; smooth, rounded sand grains cannot be piled as steeply as can rough, interlocking sands. The angle of repose can also be affected by additions of solvents. If a small amount of water is able to bridge the gaps between particles, electrostatic attraction of the water to mineral surfaces will increase the angle of repose, and related quantities such as the soil strength.

When bulk granular materials are poured onto a horizontal surface, a conical pile will form. The internal angle between the surface of the pile and the horizontal surface is known as the angle of repose and is related to the density, surface area and shapes of the particles, and the coefficient of friction of the material. Material with a low angle of repose forms flatter piles than material with a high angle of repose.

The term has a related usage in mechanics, where it refers to the maximum angle at which an object can rest on an inclined plane without sliding down. This angle is equal to the arctangent of the coefficient of static friction μ_s between the surfaces.

Interactive EasyFlow was one of the first diagramming and flow charting software packages available for personal computers. This product was the flagship software produced by HavenTree Software Limited, of Kingston, Ontario Canada. HavenTree software, formed in 1981, offered predecessor non-interactive products "EasyFlow" (1983) and "EasyFlow-Plus" (1984). Interactive EasyFlow - so named to distinguish it from the preceding products - was offered from 1985 until the early 1990s, when the company dropped the "Interactive" adjective in favour of simply "HavenTree EasyFlow". It offered the software for sale until it filed for protection under Canada's Bankruptcy and Insolvency Act in April 1996. The assets of the company were purchased by SPSS Inc. in 1998.

🔗 Computing 🔗 Economics 🔗 Apps

A super-app (also written as super app or superapp) is a mobile or web application that can provide multiple services including payment and financial transaction processing, effectively becoming an all-encompassing self-contained commerce and communication online platform that embraces many aspects of personal and commercial life. Notable examples of super-apps include Tencent's WeChat in China, and Grab in Southeast Asia.

🔗 Biography 🔗 Mathematics 🔗 Germany 🔗 Physics 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Women writers 🔗 Physics/Biographies 🔗 Toys

🔗 Mathematics

The ant on a rubber rope is a mathematical puzzle with a solution that appears counterintuitive or paradoxical. It is sometimes given as a worm, or inchworm, on a rubber or elastic band, but the principles of the puzzle remain the same.

The details of the puzzle can vary, but a typical form is as follows:

An ant starts to crawl along a taut rubber rope 1 km long at a speed of 1 cm per second (relative to the rubber it is crawling on). At the same time, the rope starts to stretch uniformly at a constant rate of 1 km per second, so that after 1 second it is 2 km long, after 2 seconds it is 3 km long, etc. Will the ant ever reach the end of the rope?

At first consideration it seems that the ant will never reach the end of the rope, but in fact it does. (In the form stated above, it would take 8.9×10⁴³⁴²¹ years.) Whatever the length of the rope and the relative speeds of the ant and the stretching, provided that the ant's speed and the stretching remain steady, the ant will always be able to reach the end given sufficient time. Once the ant has begun moving, the rubber rope is stretching both in front of and behind the ant, conserving the proportion of the rope already walked by the ant and enabling the ant to make continual progress.

🔗 Psychology 🔗 Education

Bloom's 2 sigma problem refers to an educational phenomenon observed by educational psychologist Benjamin Bloom and initially reported in 1984 in the journal Educational Researcher. Bloom found that the average student tutored one-to-one using mastery learning techniques performed two standard deviations better than students who learn via conventional instructional methods — that is, "the average tutored student was above 98% of the students in the control class". Additionally, the variation of the students' achievement changed: "about 90% of the tutored students ... attained the level of summative achievement reached by only the highest 20%" of the control class. Bloom's graduate students J. Anania and A. J. Burke conducted studies of this effect at different grade levels and in different schools, observing students with "great differences in cognitive achievement, attitudes, and academic self-concept".

🔗 Apple Inc. 🔗 Software 🔗 Software/Computing

A/UX is a Unix-based operating system from Apple Computer for Macintosh computers, integrated with System 7's graphical interface and application compatibility. It is Apple's first official Unix-based operating system, launched in 1988 and discontinued in 1995 with version 3.1.1. A/UX requires select 68k-based Macintosh models with an FPU and a paged memory management unit (PMMU), including the Macintosh II, SE/30, Quadra, and Centris series.

Described by InfoWorld as "an open systems solution with the Macintosh at its heart", A/UX is based on UNIX System V Release 2.2, with features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It is POSIX- and System V Interface Definition (SVID)-compliant and includes TCP/IP networking since version 2. Having a Unix-compatible, POSIX-compliant operating system enabled Apple to bid for large contracts to supply computers to U.S. federal government institutes.

🔗 United States 🔗 Business 🔗 Marketing & Advertising 🔗 Food and drink 🔗 Food and drink/Beverages

Between 1886 and 1959, the price of a 6.5-oz glass or bottle of Coca-Cola was set at five cents, or one nickel, and remained fixed with very little local fluctuation. The Coca-Cola Company was able to maintain this price for several reasons, including bottling contracts the company signed in 1899, advertising, vending machine technology, and a relatively low rate of inflation. The fact that the price of the drink was able to remain the same for over seventy years is especially significant considering the events that occurred during that period, including the founding of Pepsi, World War I, Prohibition, changing taxes, a caffeine and caramel shortage, World War II, and the company's desire to raise its prices. Much of the research on this subject comes from "The Real Thing": Nominal Price Rigidity of the Nickel Coke, 1886–1959, a 2004 paper by economists Daniel Levy and Andrew Young.

🔗 Technology 🔗 Computing 🔗 France 🔗 Computing/Computer hardware 🔗 Telecommunications 🔗 Popular Culture 🔗 Computing/Networking

Minitel, officially known as TELETEL, was an interactive videotex online service accessible through telephone lines. It was the world's first and most successful mass-market online service prior to the World Wide Web. It was developed in Cesson-Sévigné, Brittany, by government-owned France Télécom.

The service was initially launched on an experimental basis in July 1980 in Saint-Malo and extended to other regions in late 1980. It was commercially introduced throughout France in 1982 by the Postes, Télégraphes et Téléphones (PTT), since 1991, divided into France Télécom and La Poste. From its inception, users were able to make online purchases, book train tickets, access business information services, search the telephone directory, maintain a mailbox, and utilize chat functionalities similar to those now supported by the World Wide Web.

In February 2009, France Télécom reported that the Minitel network still maintained 10 million monthly connections. The service was discontinued by France Télécom on 30 June 2012.