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๐Ÿ”— George Pรณlya: How to Solve It (1945)

๐Ÿ”— Mathematics ๐Ÿ”— Books ๐Ÿ”— Systems

How to Solve It (1945) is a small volume by mathematician George Pรณlya describing methods of problem solving.

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๐Ÿ”— Project Denver

๐Ÿ”— Computing

Project Denver is the codename of a microarchitecture designed by Nvidia that implements the ARMv8-A 64/32-bit instruction sets using a combination of simple hardware decoder and software-based binary translation (dynamic recompilation) where "Denver's binary translation layer runs in software, at a lower level than the operating system, and stores commonly accessed, already optimized code sequences in a 128ย MB cache stored in main memory". Denver is a very wide in-order superscalar pipeline. Its design makes it suitable for integration with other SIPs cores (e.g. GPU, display controller, DSP, image processor, etc.) into one die constituting a system on a chip (SoC).

Project Denver is targeted at mobile computers, personal computers, servers, as well as supercomputers. Respective cores have found integration in the Tegra SoC series from Nvidia. Initially Denver cores was designed for the 28nm process node (Tegra model T132 aka "Tegra K1"). Denver 2 was an improved design that built for the smaller, more efficient 16nm node. (Tegra model T186 aka "Tegra X2").

In 2018, Nvidia released an improved design (codename: "Carmel", based on ARMv8 (64-bit; variant: ARM-v8.2 with 10-way superscalar, functional safety, dual execution, parity & ECC) got integrated into the Tegra Xavier SoC offering a total of 8 cores (or 4 dual-core pairs). The Carmel CPU core supports full Advanced SIMD (ARM NEON), VFP (Vector Floating Point), and ARMv8.2-FP16. First published testings of Carmel cores integrated in the Jetson AGX development kit by third party experts took place in September 2018 and indicated a noticeably increased performance as should expected for this real world physical manifestation compared to predecessors systems, despite all doubts the used quickness of such a test setup in general an in particular implies. The Carmel design can be found in the Tegra model T194 ("Tegra Xavier") that is designed with a 12 nm structure size.

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๐Ÿ”— The eastern coyote, a wild N. American canine with coyote-wolf and dog parentage

๐Ÿ”— Dogs

The eastern coyote (Canis latrans var.) is a wild North American canine of both coyote and wolf parentage. The hybridization likely first occurred in the Great Lakes region, as western coyotes moved east. It was first noticed during the early 1930s to the late 1940s, and likely originated in the aftermath of the extirpation of the gray wolf in southeastern Ontario, Labrador and Quebec, thus allowing coyotes to colonize the former wolf ranges and mix with the remnant wolf populations. This hybrid is smaller than the eastern wolf and holds smaller territories, but is larger and holds more extensive home ranges than the typical western coyote.

๐Ÿ”— Rongorongo

๐Ÿ”— Polynesia ๐Ÿ”— Writing systems ๐Ÿ”— Chile

Rongorongo (; Rapa Nui: [หˆษพoล‹oหˆษพoล‹o]) is a system of glyphs discovered in the 19th century on Easter Island that appears to be writing or proto-writing. Numerous attempts at decipherment have been made, none successfully. Although some calendrical and what might prove to be genealogical information has been identified, none of these glyphs can actually be read. If rongorongo does prove to be writing and proves to be an independent invention, it would be one of very few independent inventions of writing in human history.

Two dozen wooden objects bearing rongorongo inscriptions, some heavily weathered, burned, or otherwise damaged, were collected in the late 19th century and are now scattered in museums and private collections. None remain on Easter Island. The objects are mostly tablets shaped from irregular pieces of wood, sometimes driftwood, but include a chieftain's staff, a bird-man statuette, and two reimiro ornaments. There are also a few petroglyphs which may include short rongorongo inscriptions. Oral history suggests that only a small elite was ever literate and that the tablets were sacred.

Authentic rongorongo texts are written in alternating directions, a system called reverse boustrophedon. In a third of the tablets, the lines of text are inscribed in shallow fluting carved into the wood. The glyphs themselves are outlines of human, animal, plant, artifact and geometric forms. Many of the human and animal figures, such as glyphs 200 and 280 , have characteristic protuberances on each side of the head, possibly representing eyes.

Individual texts are conventionally known by a single uppercase letter and a name, such as Tablet C, the Mamari Tablet. The somewhat variable names may be descriptive or indicate where the object is kept, as in the Oar, the Snuffbox, the Small Santiago Tablet, and the Santiago Staff.

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๐Ÿ”— Topological quantum computer

๐Ÿ”— Mathematics ๐Ÿ”— Physics

A topological quantum computer is a theoretical quantum computer that employs two-dimensional quasiparticles called anyons, whose world lines pass around one another to form braids in a three-dimensional spacetime (i.e., one temporal plus two spatial dimensions). These braids form the logic gates that make up the computer. The advantage of a quantum computer based on quantum braids over using trapped quantum particles is that the former is much more stable. Small, cumulative perturbations can cause quantum states to decohere and introduce errors in the computation, but such small perturbations do not change the braids' topological properties. This is like the effort required to cut a string and reattach the ends to form a different braid, as opposed to a ball (representing an ordinary quantum particle in four-dimensional spacetime) bumping into a wall. Alexei Kitaev proposed topological quantum computation in 1997. While the elements of a topological quantum computer originate in a purely mathematical realm, experiments in fractional quantum Hall systems indicate these elements may be created in the real world using semiconductors made of gallium arsenide at a temperature of near absolute zero and subjected to strong magnetic fields.

๐Ÿ”— Loose Lips Sink Ships

๐Ÿ”— United States/U.S. Government ๐Ÿ”— United States ๐Ÿ”— Philately

The Office of Censorship was an emergency wartime agency set up by the United States federal government on December 19, 1941 to aid in the censorship of all communications coming into and going out of the United States, including its territories and the Philippines. The efforts of the Office of Censorship to balance the protection of sensitive war related information with the constitutional freedoms of the press is considered largely successful. The agency's implementation of censorship was done primarily through a voluntary regulatory code that was willingly adopted by the press. The phrase "loose lips sink ships" was popularized during World War II, which is a testament to the urgency Americans felt to protect information relating to the war effort. Radio broadcasts, newspapers, and newsreels were the primary ways Americans received their information about World War II and therefore were the medium most affected by the Office of Censorship code. The closure of the Office of Censorship in November 1945 corresponded with the ending of World War II.

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๐Ÿ”— Vehicle registration plates of Native American tribes in the United States

๐Ÿ”— Indigenous peoples of North America

Several Native American tribes within the United States register motor vehicles and issue license plates to those vehicles.

The legal status of these plates varies by tribe, with some being recognized by the federal government and others not. Some nations issue plates for both tribal and personal vehicles, while others issue plates only for official tribal vehicles.

Some nations' plates indicate the U.S. state with which they are most closely associated, while others do not. This variation may even exist among the nations associated with one particular state.

Federally recognized tribes may also lease vehicles through the U.S. General Services Administration under certain circumstances. Such vehicles carry U.S. government license plates.

๐Ÿ”— Crew resource management

๐Ÿ”— Aviation ๐Ÿ”— Disaster management

Crew resource management or cockpit resource management (CRM) is a set of training procedures for use in environments where human error can have devastating effects. Used primarily for improving aviation safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit of an airliner. Its pioneer was David Beaty, a former Royal Air Force pilot and later a BOAC pilot who wrote his seminal book The Human Factor in Aircraft Accidents in the late 1950s. Despite the considerable development of electronic aids since then, many principles he developed continue to prove effective today.

Crew resource management formally began with a National Transportation Safety Board (NTSB) recommendation made during their investigation of the 1978 United Airlines Flight 173 crash. The issues surrounding that crash included a DC-8 crew running out of fuel over Portland, Oregon while troubleshooting a landing gear problem.

The term "cockpit resource management" (later generalized to "crew resource management") was coined in 1979 by NASA psychologist John Lauber who had studied communication processes in cockpits for several years. While retaining a command hierarchy, the concept was intended to foster a less authoritarian cockpit culture, where co-pilots were encouraged to question captains if they observed them making mistakes.

Crew resource management grew out of the 1977 Tenerife airport disaster where two Boeing 747 aircraft collided on the runway killing 583 people. A few weeks later, NASA held a workshop on the topic, endorsing this innovative training. United Airlines was the first airline to provide CRM training for its cockpit crews in 1981. By the 1990s, it had become a global standard.

United Airlines additionally trained their flight attendants to use CRM in conjunction with the pilots to provide another layer of enhanced communication and teamwork. Studies have shown that by both work groups using CRM together, communication barriers are reduced and problems can be solved more efficiently, leading to increased safety. CRM training concepts have been modified for application to a wide range of activities where people must make dangerous time-critical decisions. These arenas include air traffic control, ship handling, firefighting, and medical operating rooms.

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๐Ÿ”— Crookes Radiometer

๐Ÿ”— Technology ๐Ÿ”— Physics ๐Ÿ”— Energy

The Crookes radiometer (also known as a light mill) consists of an airtight glass bulb containing a partial vacuum, with a set of vanes which are mounted on a spindle inside. The vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity.

The reason for the rotation was a cause of much scientific debate in the ten years following the invention of the device, but in 1879 the currently accepted explanation for the rotation was published. Today the device is mainly used in physics education as a demonstration of a heat engine run by light energy.

It was invented in 1873 by the chemist Sir William Crookes as the by-product of some chemical research. In the course of very accurate quantitative chemical work, he was weighing samples in a partially evacuated chamber to reduce the effect of air currents, and noticed the weighings were disturbed when sunlight shone on the balance. Investigating this effect, he created the device named after him.

It is still manufactured and sold as an educational aid or for curiosity.

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๐Ÿ”— I never realized how useful netcat is

๐Ÿ”— Computing ๐Ÿ”— Computing/Software ๐Ÿ”— Computing/Free and open-source software

netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP. The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.

Its list of features includes port scanning, transferring files, and port listening, and it can be used as a backdoor.

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