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🔗 Spaceflight 🔗 Moon

The Apollo 11 missing tapes were those that were recorded from Apollo 11's slow-scan television (SSTV) telecast in its raw format on telemetry data tape at the time of the first Moon landing in 1969 and subsequently lost. The data tapes were recorded as a backup in case the live television broadcasts failed for any reason.

To broadcast the SSTV transmission on standard television, NASA ground receiving stations performed real-time scan conversion to the NTSC television format. The moonwalk's converted video signal was broadcast live around the world on July 21, 1969 (2:56 UTC). At the time, the NTSC broadcast was recorded on many videotapes and kinescope films. Many of these low-quality recordings remain intact. As the real-time broadcast worked and was widely recorded, preservation of the backup video was not deemed a priority in the years immediately following the mission. In the early 1980s, NASA's Landsat program was facing a severe data tape shortage and it is likely the tapes were erased and reused at this time.

A team of retired NASA employees and contractors tried to find the tapes in the early 2000s but was unable to do so. The search was sparked when several still photographs appeared in the late 1990s that showed the visually superior raw SSTV transmission on ground-station monitors. The research team conducted a multi-year investigation in the hopes of finding the most pristine and detailed video images of the moonwalk. If copies of the original SSTV format tapes were to be found, more modern digital technology could make a higher-quality conversion, yielding better images than those originally seen. The researchers concluded that the tapes containing the raw unprocessed Apollo 11 SSTV signal were erased and reused by NASA in the early 1980s, following standard procedure at the time.

Although the researchers never found the telemetry tapes, they did discover the best visual quality NTSC videotapes as well as Super 8 movie film taken of a video monitor in Australia, showing the SSTV transmission before it was converted. These visual elements were processed in 2009, as part of a NASA-approved restoration project of the first moonwalk. At a 2009 news conference in Washington, D.C., the research team released its findings regarding the tapes' disappearance. They also partially released newly enhanced footage obtained during the search. Lowry Digital completed the full moonwalk restoration project in late 2009.

🔗 Archaeology 🔗 Paranormal

A thunderstone is a flint tool or fossil turned up by farmer's plow that was thought to have fallen from the sky. They were often thought to be thunderbolts. It was not until travelers returned from far-away places where these implements were in use among primitive cultures that the origins of these objects became known. Even then, these travelers' tales received little popular credence.

🔗 Chemistry

Dry water , an unusual form of "powdered liquid", is a water–air emulsion in which tiny water droplets, each the size of a grain of sand, are surrounded by a sandy silica coating. Dry water actually consists of 95% liquid water, but the silica coating prevents the water droplets from combining and turning back into a bulk liquid. The result is a white powder that looks very similar to table salt. It is also more commonly known among researchers as empty water.

🔗 Medicine

The Krukenberg procedure, also known as the Krukenberg operation, is a surgical technique that converts a forearm stump into a pincer. It was first described in 1917 by the German army surgeon Hermann Krukenberg. It remains in use today for certain special cases but is considered controversial and some surgeons refuse to perform it.

🔗 Biology 🔗 Molecular and Cell Biology 🔗 Chemistry 🔗 Genetics

Mirror life (also called mirror-image life, chiral life, or enantiomeric life) is a hypothetical form of life with mirror-reflected molecular building blocks. The possibility of mirror life was first discussed by Louis Pasteur. Although this alternative life form has not been discovered in nature, efforts to build a mirror-image version of biology's molecular machinery are already underway.

🔗 Mathematics 🔗 Physics 🔗 Systems 🔗 Systems/Dynamical systems

The Abelian sandpile model, also known as the Bak–Tang–Wiesenfeld model, was the first discovered example of a dynamical system displaying self-organized criticality. It was introduced by Per Bak, Chao Tang and Kurt Wiesenfeld in a 1987 paper.

The model is a cellular automaton. In its original formulation, each site on a finite grid has an associated value that corresponds to the slope of the pile. This slope builds up as "grains of sand" (or "chips") are randomly placed onto the pile, until the slope exceeds a specific threshold value at which time that site collapses transferring sand into the adjacent sites, increasing their slope. Bak, Tang, and Wiesenfeld considered process of successive random placement of sand grains on the grid; each such placement of sand at a particular site may have no effect, or it may cause a cascading reaction that will affect many sites.

The model has since been studied on the infinite lattice, on other (non-square) lattices, and on arbitrary graphs (including directed multigraphs). It is closely related to the dollar game, a variant of the chip-firing game introduced by Biggs.

🔗 Computing 🔗 Computing/Computer hardware

Viewtron was an online service offered by Knight-Ridder and AT&T from 1983 to 1986. Patterned after the British Post Office's Prestel system, it started as a videotex service requiring users to have a special terminal, the AT&T Sceptre. As home computers became important in the marketplace, the development focus shifted to IBM, Apple, Commodore and other personal computers.

Viewtron differed from contemporary services like CompuServe and The Source by emphasizing news from The Miami Herald and Associated Press and e-commerce services from JCPenney and other merchants over computer-oriented services such as file downloads or online chat. Intended to be "the McDonald's of videotex," Viewtron was specifically targeted toward users who would be apprehensive about using a computer.

Viewtron also offered airline schedules from the Official Airline Guide (OAG), real estate research from Century 21, e-cards from Hallmark, product information from Consumer Reports, educational software from Scott Foresman, online auctions, financial services from American Express and EF Hutton, as well as limited online banking services as part of a research program into the uses and costs of banking online that included 20 US and Canadian banks.

At its height, Viewtron was operated in at least 15 cities by various newspaper companies. After six years of research and an investment reportedly in excess of $50 million, Viewtron never turned a profit, and, despite its developer's forecasts of breaking even in two years, Knight Ridder did not expect it ever would be profitable. AT&T had invested over $100 million in the project, but was forced to write off that investment as part of its court-ordered breakup. Viewtron closed on March 31, 1986, after an attempt by the Independent Commodore Users Group to buy the service failed.

A feature tying Viewtron to local newspapers was envisioned, with printed text instructing users how to access further information online, but it was never implemented.

In 2008, PCWorld magazine named Viewtron to a list of the biggest project failures in information technology (IT) history.

🔗 Physics

A Bessel beam is a wave whose amplitude is described by a Bessel function of the first kind. Electromagnetic, acoustic, gravitational, and matter waves can all be in the form of Bessel beams. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffract and spread out; this is in contrast to the usual behavior of light (or sound), which spreads out after being focused down to a small spot. Bessel beams are also self-healing, meaning that the beam can be partially obstructed at one point, but will re-form at a point further down the beam axis.

As with a plane wave, a true Bessel beam cannot be created, as it is unbounded and would require an infinite amount of energy. Reasonably good approximations can be made, however, and these are important in many optical applications because they exhibit little or no diffraction over a limited distance. Approximations to Bessel beams are made in practice either by focusing a Gaussian beam with an axicon lens to generate a Bessel–Gauss beam, by using axisymmetric diffraction gratings, or by placing a narrow annular aperture in the far field. High order Bessel beams can be generated by spiral diffraction gratings.

🔗 Environment 🔗 Biology 🔗 Physics 🔗 Guild of Copy Editors 🔗 Energy 🔗 Chemical and Bio Engineering

Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel (a solar fuel). Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.

Research of this topic includes the design and assembly of devices for the direct production of solar fuels, photoelectrochemistry and its application in fuel cells, and the engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight.

🔗 Linguistics 🔗 Linguistics/Applied Linguistics 🔗 Writing systems

The Shavian alphabet (also known as the Shaw alphabet) is an alphabet conceived as a way to provide simple, phonetic orthography for the English language to replace the difficulties of conventional spelling. It was posthumously funded by and named after Irish playwright Bernard Shaw. Shaw set three main criteria for the new alphabet: it should be (1) at least 40 letters; (2) as "phonetic" as possible (that is, letters should have a 1:1 correspondence to phonemes); and (3) distinct from the Latin alphabet to avoid the impression that the new spellings were simply "misspellings".