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🔗 Classical Greece and Rome 🔗 Turkey 🔗 Mills

The Hierapolis sawmill was a Roman water-powered stone sawmill at Hierapolis, Asia Minor (modern-day Turkey). Dating to the second half of the 3rd century AD, the sawmill is considered the earliest known machine to combine a crank with a connecting rod to form a crank slider mechanism.

The watermill is evidenced by a raised relief on the sarcophagus of a certain Marcus Aurelius Ammianos, a local miller. On the pediment a waterwheel fed by a mill race is shown powering via a gear train two frame saws cutting rectangular blocks by the way of connecting rods and, through mechanical necessity, cranks (see diagram). The accompanying inscription is in Greek and attributes the mechanism to Ammianos' "skills with wheels".

🔗 Video games 🔗 Law

Bleem! (styled as bleem!) is a commercial PlayStation emulator released by the Bleem! Company in 1999 for IBM-compatible PCs and Dreamcast. It is notable for being one of the few commercial software emulators to be aggressively marketed during the emulated console's lifetime, and was the center of multiple controversial lawsuits.

🔗 Computing 🔗 Telecommunications 🔗 Computer Security 🔗 Computer Security/Computing

Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.

The term first referred to groups who had reverse engineered the system of tones used to route long-distance calls. By re-creating these tones, phreaks could switch calls from the phone handset, allowing free calls to be made around the world. To ease the creation of these tones, electronic tone generators known as blue boxes became a staple of the phreaker community. This community included future Apple Inc. cofounders Steve Jobs and Steve Wozniak.

The blue box era came to an end with the ever-increasing use of computerized phone systems which allowed telecommunication companies to discontinue the use of in-band signaling for call routing purposes. Instead, dialing information was sent on a separate channel which was inaccessible to the telecom customer. By the 1980s, most of the public switched telephone network (PSTN) in the US and Western Europe had adopted the SS7 system which uses out-of-band signaling for call control (and which is still in use to this day). Phreaking has since become closely linked with computer hacking.

🔗 Physics 🔗 Astronomy

The berserker hypothesis, also known as the deadly probes scenario, is the idea that humans have not yet detected intelligent alien life in the universe because it has been systematically destroyed by a series of lethal Von Neumann probes. The hypothesis is named after the Berserker series of novels (1963-2005) written by Fred Saberhagen.

The hypothesis has no single known proposer, and instead is thought to have emerged over time in response to the Hart–Tipler conjecture, or the idea that an absence of detectable Von Neumann probes is contrapositive evidence that no intelligent life exists outside of the Sun's Solar System. According to the berserker hypothesis, an absence of such probes is not evidence of life's absence, since interstellar probes could "go berserk" and destroy other civilizations, before self-destructing.

In his 1983 paper "The Great Silence", astronomer David Brin summarized the frightening implications of the berserker hypothesis: it is entirely compatible with all the facts and logic of the Fermi paradox, but would mean that there exists no intelligent life left to be discovered. In the worst-case scenario, humanity has already alerted others to its existence, and is next in line to be destroyed.

There is no need to struggle to suppress the elements of the Drake equation in order to explain the Great Silence, nor need we suggest that no [intelligent aliens] anywhere would bear the cost of interstellar travel. It need only happen once for the results of this scenario to become the equilibrium conditions in the Galaxy. We would not have detected extra-terrestrial radio traffic – nor would any [intelligent aliens] have ever settled on Earth – because all were killed shortly after discovering radio.

🔗 Syria

The Hurrian songs are a collection of music inscribed in cuneiform on clay tablets excavated from the ancient Amorite-Canaanite city of Ugarit, a headland in northern Syria, which date to approximately 1400 BCE. One of these tablets, which is nearly complete, contains the Hurrian hymn to Nikkal (also known as the Hurrian cult hymn or A Zaluzi to the Gods, or simply h.6), making it the oldest surviving substantially complete work of notated music in the world. While the composers' names of some of the fragmentary pieces are known, h.6 is an anonymous work.

🔗 Law 🔗 English Language

"The exception that proves the rule" (sometimes "the exception proves the rule") is a saying whose meaning is contested. Henry Watson Fowler's Modern English Usage identifies five ways in which the phrase has been used, and each use makes some sort of reference to the role that a particular case or event takes in relation to a more general rule.

Two original meanings of the phrase are usually cited. The first, preferred by Fowler, is that the presence of an exception applying to a specific case establishes ("proves") that a general rule exists. A more explicit phrasing might be "the exception that proves the existence of the rule." Most contemporary uses of the phrase emerge from this origin, although often in a way which is closer to the idea that all rules have their exceptions. The alternative origin given is that the word "prove" is used in the archaic sense of "test". In this sense, the phrase does not mean that an exception demonstrates a rule to be true or to exist, but that it tests the rule, thereby proving its value. There is little evidence of the phrase being used in this second way.

🔗 Video games 🔗 Computer science 🔗 Mathematics

Fast inverse square root, sometimes referred to as Fast InvSqrt() or by the hexadecimal constant 0x5F3759DF, is an algorithm that estimates ​¹⁄_√x, the reciprocal (or multiplicative inverse) of the square root of a 32-bit floating-point number x in IEEE 754 floating-point format. This operation is used in digital signal processing to normalize a vector, i.e., scale it to length 1. For example, computer graphics programs use inverse square roots to compute angles of incidence and reflection for lighting and shading. The algorithm is best known for its implementation in 1999 in the source code of Quake III Arena, a first-person shooter video game that made heavy use of 3D graphics. The algorithm only started appearing on public forums such as Usenet in 2002 or 2003. At the time, it was generally computationally expensive to compute the reciprocal of a floating-point number, especially on a large scale; the fast inverse square root bypassed this step.

The algorithm accepts a 32-bit floating-point number as the input and stores a halved value for later use. Then, treating the bits representing the floating-point number as a 32-bit integer, a logical shift right by one bit is performed and the result subtracted from the number 0x5F3759DF, which is a floating point representation of an approximation of √2¹²⁷. This results in the first approximation of the inverse square root of the input. Treating the bits again as a floating-point number, it runs one iteration of Newton's method, yielding a more precise approximation.

The algorithm was originally attributed to John Carmack, but an investigation showed that the code had deeper roots in both the hardware and software side of computer graphics. Adjustments and alterations passed through both Silicon Graphics and 3dfx Interactive, with Gary Tarolli's implementation for the SGI Indigo as the earliest known use. It is not known how the constant was originally derived, though investigation has shed some light on possible methods.

With subsequent hardware advancements, especially the x86 SSE instruction rsqrtss, this method is not generally applicable to modern computing, though it remains an interesting example both historically and for more limited machines.

🔗 Education

TRIZ (; Russian: теория решения изобретательских задач, teoriya resheniya izobretatelskikh zadatch, literally: "theory of the resolution of invention-related tasks") is "a problem-solving, analysis and forecasting tool derived from the study of patterns of invention in the global patent literature". It was developed by the Soviet inventor and science-fiction author Genrich Altshuller (1926-1998) and his colleagues, beginning in 1946. In English the name is typically rendered as "the theory of inventive problem solving", and occasionally goes by the English acronym TIPS.

Following Altshuller's insight, the theory developed on a foundation of extensive research covering hundreds of thousands of inventions across many different fields to produce a theory which defines generalisable patterns in the nature of inventive solutions and the distinguishing characteristics of the problems that these inventions have overcome.

An important part of the theory has been devoted to revealing patterns of evolution and one of the objectives which has been pursued by leading practitioners of TRIZ has been the development of an algorithmic approach to the invention of new systems, and to the refinement of existing ones.

TRIZ includes a practical methodology, tool sets, a knowledge base, and model-based technology for generating innovative solutions for problem solving. It is useful for problem formulation, system analysis, failure analysis, and patterns of system evolution. There is a general similarity of purposes and methods with the field of pattern language, a cross discipline practice for explicitly describing and sharing holistic patterns of design.

The research has produced three primary findings:

1. problems and solutions are repeated across industries and sciences
2. patterns of technical evolution are also repeated across industries and sciences
3. the innovations used scientific effects outside the field in which they were developed

TRIZ practitioners apply all these findings in order to create and to improve products, services, and systems.

🔗 Telecommunications

Procedure words or prowords are words or phrases limited to radio telephone procedure used to facilitate communication by conveying information in a condensed standard verbal format. Prowords are voice versions of the much older prosigns for Morse code first developed in the 1860s for Morse telegraphy, and their meaning is identical. The NATO communications manual ACP-125 contains the most formal and perhaps earliest modern (post-WW-II) glossary of procedure words, but its definitions have been adopted by many other organizations, including the United Nations Development Programme, the U.S. Coast Guard, the Rhode Island Department of Emergency Management, Civil Air Patrol, Military Auxiliary Radio System, and others.

Procedure words are one of several structured parts of radio voice procedures, including Brevity codes and Plain language radio checks. The vast majority of the brevity codes from the U.S. military's Multiservice tactical brevity code are inappropriate for any civilian use, owing to their focus on large weapons (missiles, etc.) and other war-related issues. However, a few are used frequently enough in media to be memorable, including ABORT, BOGEY, BANDIT, FEET WET, FEET DRY, NEGATIVE CONTACT, and NO JOY.

🔗 Australia 🔗 Australia/Northern Territory 🔗 Weather 🔗 Weather/Weather 🔗 Weather/General meteorology

Hector is a cumulonimbus thundercloud cluster that forms regularly nearly every afternoon on the Tiwi Islands in the Northern Territory of Australia, from approximately September to March each year. Hector, or sometimes Hector the Convector, is known as one of the world's most consistently large thunderstorms; specifically, a small mesoscale convective system (MCS) or large multicellular thunderstorm. It reaches heights of approximately 20 kilometres (66,000 ft).