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🔗 Disability

Audio induction loop systems, also called audio-frequency induction loops (AFILs) or hearing loops, are an assistive listening technology for individuals with reduced ranges of hearing.

A hearing loop consists of one or more physical loops of cable which are placed around a designated area, usually a room or a building. The cable generates an electromagnetic field throughout the looped space which can be picked up by a telecoil-equipped hearing aid, a cochlear implant (CI) processor, or a specialized hand-held hearing loop receiver for individuals without telecoil-compatible hearing aids.

The loops carry baseband audio-frequency currents; no carrier signal is used. The benefit is that it allows the sound source of interest – whether a musical performance or a ticket taker's side of the conversation – to be transmitted to the hearing-impaired listener clearly and free of other distracting noise in the environment. Typical installation sites include concert halls, ticket kiosks, high-traffic public buildings (for PA announcements), auditoriums, places of worship, courtrooms, meeting rooms, and homes.

In the United Kingdom, as an aid for disability, their provision, where reasonably possible, is required by the Equality Act 2010 and previously by the Disability Discrimination Act 1995, and they are available in "the back seats of all London taxis, which have a little microphone embedded in the dashboard in front of the driver; at 18,000 post offices in the U.K.; at most churches and cathedrals", according to Prof. David G. Myers.

In the United States, an alternative technology using FM transmission to "neck loop" receivers was more widely adopted due to economic advantages. In comparison, hearing loop systems require a greater initial investment by the facility operator, but offer greater convenience and avoid the social stigma and hygienic concerns entailed by the FM system's paraphernalia for those who have hearing aids.

Another alternative system, used primarily in theatres, uses invisible infrared radiation; compatible headsets can pick up the modulated infrared energy to reproduce sound.

🔗 Agriculture 🔗 Indigenous peoples of North America

The Three Sisters are the three main agricultural crops of various Indigenous peoples of North America: squash, maize ("corn"), and climbing beans (typically tepary beans or common beans). In a technique known as companion planting, the maize and beans are often planted together in mounds formed by hilling soil around the base of the plants each year; squash is typically planted between the mounds. The cornstalk serves as a trellis for climbing beans, the beans fix nitrogen in their root nodules and stabilize the maize in high winds, and the wide leaves of the squash plant shade the ground, keeping the soil moist and helping prevent the establishment of weeds.

Indigenous peoples throughout North America cultivated different varieties of the Three Sisters, adapted to varying local environments. The individual crops and their use in polyculture originated in Mesoamerica; where squash was domesticated first, followed by maize and then beans, over a period of 5,000–6,500 years. European records from the sixteenth century describe highly productive Indigenous agriculture based on cultivation of the Three Sisters throughout what are now the Eastern United States and Canada, where the crops were used for both food and trade. Geographer Carl O. Sauer described the Three Sisters as "a symbiotic plant complex of North and Central America without an equal elsewhere".

In 2011, Randall Munroe in his comic xkcd coined the term "citogenesis" to describe the creation of "reliable" sources through circular reporting. This is a list of some well-documented cases where Wikipedia has been the source.

🔗 France 🔗 Death

The Great Plague of Marseille was the last major outbreak of bubonic plague in western Europe. Arriving in Marseille, France in 1720, the disease killed a total of 100,000 people: 50,000 in the city during the next two years and another 50,000 to the north in surrounding provinces and towns.

While economic activity took only a few years to recover, as trade expanded to the West Indies and Latin America, it was not until 1765 that the population returned to its pre-1720 level.

🔗 Computing

The R3000 is a 32-bit RISC microprocessor chipset developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture (ISA). Introduced in June 1988, it was the second MIPS implementation, succeeding the R2000 as the flagship MIPS microprocessor. It operated at 20, 25 and 33.33 MHz.

The MIPS 1 instruction set is small compared to those of the contemporary 80x86 and 680x0 architectures, encoding only more commonly used operations and supporting few addressing modes. Combined with its fixed instruction length and only three different types of instruction formats, this simplified instruction decoding and processing. It employed a 5-stage instruction pipeline, enabling execution at a rate approaching one instruction per cycle, unusual for its time.

This MIPS generation supports up to four co-processors. In addition to the CPU core, the R3000 microprocessor includes a Control Processor (CP), which contains a Translation Lookaside Buffer and a Memory Management Unit. The CP works as a coprocessor. Besides the CP, the R3000 can also support an external R3010 numeric coprocessor and two other external coprocessors.

The R3000 CPU does not include level 1 cache. Instead, its on-chip cache controller operates external data and instruction caches of up to 256 KB each. It can access both caches during the same clock cycle.

The R3000 found much success and was used by many companies in their workstations and servers. Users included:

• Ardent Computer
• Digital Equipment Corporation (DEC) for their DECstation workstations and multiprocessor DECsystem servers
• Evans & Sutherland for their Vision (ESV) series workstations
• MIPS Computer Systems for their MIPS RISC/os Unix workstations and servers.
• NEC for their RISC EWS4800 workstations and UP4800 servers.
• Prime Computer
• Pyramid Technology
• Seiko Epson
• Silicon Graphics for their Professional IRIS, Personal IRIS and Indigo workstations, and the multiprocessor Power Series visualization systems
• Sony for their PlayStation and PlayStation 2 (SCPH-10000 to SCPH-700XX - clocked at 37.5 MHz for use as an I/O CPU and at 33.8 MHz for compatibility with PlayStation games) video game consoles, and NEWS workstations, as well as the Bemani System 573 Analog arcade unit, which runs on the R3000A.
• Tandem Computers for their NonStop Cyclone/R and CLX/R fault-tolerant servers
• Whitechapel Workstations for their Hitech-20 workstation
• New Horizons Probe

The R3000 was also used as an embedded microprocessor. When advances in technology rendered it obsolete for high-performance systems, it found continued use in lower-cost designs. Companies such as LSI Logic developed derivatives of the R3000 specifically for embedded systems.

The R3000 was a further development of the R2000 with minor improvements including larger TLB and a faster bus to the external caches. The R3000 die contained 115,000 transistors and measured about 75,000 square mils (48 mm²). MIPS was a fabless semiconductor company, so the R3000 was fabricated by MIPS partners including Integrated Device Technology (IDT), LSI Logic, NEC Corporation, Performance Semiconductor, and others. It was fabricated in a 1.2 μm complementary metal–oxide–semiconductor (CMOS) process with two levels of aluminium interconnect.

Derivatives of the R3000 for non-embedded applications include:

• R3000A - A further development by MIPS introduced in 1989. It operated at clock frequencies up to 40 MHz.
• PR3400 - Developed by Performance Semiconductor, introduced in May 1991, also at up to 40 MHz. It integrated the Performance Semiconductor PR3000A and PR3010A onto a single die.

Derivatives of the R3000 for embedded applications include:

• PR31700 - A 75 MHz microcontroller from Philips Semiconductors. Fabricated in a 0.35 μm process, delivered in a 208-pin LQFP, it operated at 3.3 V and dissipated only 0.35 W.
• RISController - A family of low-end microcontrollers from IDT. Models include the R3041, R3051, R3052, and R3081.
• TX3900 - A microcontroller from Toshiba.
• Mongoose-V - A radiation-hardened and expanded 10–15 MHz CPU for use on spacecraft, it is still in use today in applications such as NASA's New Horizons space probe.

🔗 California 🔗 Companies 🔗 California/San Francisco Bay Area 🔗 Apple Inc. 🔗 Computing 🔗 Computing/Software 🔗 Media 🔗 Music theory

Napster was a peer-to-peer (P2P) file sharing application primarily associated with digital audio file distribution. Founded by Shawn Fanning and Sean Parker, the platform originally launched on June 1, 1999. Audio shared on the service was typically encoded in the MP3 format. As the software became popular, the company encountered legal difficulties over copyright infringement. Napster ceased operations in 2001 after losing multiple lawsuits and filed for bankruptcy in June 2002.

The P2P model employed by Napster involved a centralized database that indexed a complete list of all songs being shared from connected clients. While effective, the service could not function without the central database, which was hosted by Napster and eventually forced to shutdown. Following Napster's demise, alternative decentralized methods of P2P file-sharing emerged, including Gnutella, Freenet, FastTrack, and BitTorrent.

Napster's assets were eventually acquired by Roxio, and it re-emerged as an online music store commonly known as Napster 2.0. Best Buy later purchased the service and merged it with its Rhapsody streaming service on December 1, 2011. In 2016, the original branding was restored when Rhapsody was renamed Napster.

🔗 Mathematics

The 15-puzzle (also called Gem Puzzle, Boss Puzzle, Game of Fifteen, Mystic Square and many others) is a sliding puzzle that consists of a frame of numbered square tiles in random order with one tile missing. The puzzle also exists in other sizes, particularly the smaller 8-puzzle. If the size is 3×3 tiles, the puzzle is called the 8-puzzle or 9-puzzle, and if 4×4 tiles, the puzzle is called the 15-puzzle or 16-puzzle named, respectively, for the number of tiles and the number of spaces. The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space.

The n-puzzle is a classical problem for modelling algorithms involving heuristics. Commonly used heuristics for this problem include counting the number of misplaced tiles and finding the sum of the taxicab distances between each block and its position in the goal configuration. Note that both are admissible, i.e. they never overestimate the number of moves left, which ensures optimality for certain search algorithms such as A*.

🔗 Economics 🔗 Statistics

The Herfindahl index (also known as Herfindahl–Hirschman Index, HHI, or sometimes HHI-score) is a measure of the size of firms in relation to the industry and an indicator of the amount of competition among them. Named after economists Orris C. Herfindahl and Albert O. Hirschman, it is an economic concept widely applied in competition law, antitrust and also technology management. It is defined as the sum of the squares of the market shares of the firms within the industry (sometimes limited to the 50 largest firms), where the market shares are expressed as fractions. The result is proportional to the average market share, weighted by market share. As such, it can range from 0 to 1.0, moving from a huge number of very small firms to a single monopolistic producer. Increases in the Herfindahl index generally indicate a decrease in competition and an increase of market power, whereas decreases indicate the opposite. Alternatively, if whole percentages are used, the index ranges from 0 to 10,000 "points". For example, an index of .25 is the same as 2,500 points.

The major benefit of the Herfindahl index in relationship to such measures as the concentration ratio is that it gives more weight to larger firms.

The measure is essentially equivalent to the Simpson diversity index, which is a diversity index used in ecology; the inverse participation ratio (IPR) in physics; and the effective number of parties index in politics.

🔗 Video games 🔗 Molecular Biology 🔗 Molecular Biology/Molecular and Cell Biology

Foldit is an online puzzle video game about protein folding. It is part of an experimental research project developed by the University of Washington, Center for Game Science, in collaboration with the UW Department of Biochemistry. The objective of Foldit is to fold the structures of selected proteins as perfectly as possible, using tools provided in the game. The highest scoring solutions are analyzed by researchers, who determine whether or not there is a native structural configuration (native state) that can be applied to relevant proteins in the real world. Scientists can then use these solutions to target and eradicate diseases and create biological innovations. A 2010 paper in the science journal Nature credited Foldit's 57,000 players with providing useful results that matched or outperformed algorithmically computed solutions.