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🔗 Australia 🔗 Insects 🔗 Australia/Australian biota

Pantala flavescens, the globe skimmer, globe wanderer or wandering glider, is a wide-ranging dragonfly of the family Libellulidae. This species and Pantala hymenaea, the "spot-winged glider", are the only members of the genus Pantala. It was first described by Johan Christian Fabricius in 1798. It is considered to be the most widespread dragonfly on the planet with good population on every continent except Antarctica although rare in Europe. Globe skimmers make an annual multigenerational journey of some 18,000 km (about 11,200 miles); to complete the migration, individual globe skimmers fly more than 6,000 km (3,730 miles)—one of the farthest known migrations of all insect species.

🔗 Statistics

In statistics, Halton sequences are sequences used to generate points in space for numerical methods such as Monte Carlo simulations. Although these sequences are deterministic, they are of low discrepancy, that is, appear to be random for many purposes. They were first introduced in 1960 and are an example of a quasi-random number sequence. They generalize the one-dimensional van der Corput sequences.

🔗 Physics

The X17 particle is a hypothetical subatomic particle proposed by Attila Krasznahorkay and his colleagues to explain certain anomalous measurement results. The particle has been proposed to explain wide angles observed in the trajectory paths of particles produced during a nuclear transition of beryllium-8 atoms and in stable helium atoms. The X17 particle could be the force carrier for a postulated fifth force, possibly connected with dark matter, and has been described as a protophobic (i.e., ignoring protons) X boson with a mass near 17 MeV.

🔗 Automobiles

A hemispherical combustion chamber is a type of combustion chamber in a reciprocating internal combustion engine with a domed cylinder head. An engine featuring this type of hemispherical chamber is known as a hemi engine.

🔗 Geology

Geothermal gradient is the rate of increasing temperature with respect to increasing depth in Earth's interior. Away from tectonic plate boundaries, it is about 25–30 °C/km (72–87 °F/mi) of depth near the surface in most of the world. Strictly speaking, geo-thermal necessarily refers to Earth but the concept may be applied to other planets.

Earth's internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, latent heat from core crystallization, and possibly heat from other sources. The major heat-producing isotopes in Earth are potassium-40, uranium-238, uranium-235, and thorium-232. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa (3.6 million atm). Because much of the heat is provided by radioactive decay, scientists believe that early in Earth history, before isotopes with short half-lives had been depleted, Earth's heat production would have been much higher. Heat production was twice that of present-day at approximately 3 billion years ago, resulting in larger temperature gradients within the Earth, larger rates of mantle convection and plate tectonics, allowing the production of igneous rocks such as komatiites that are no longer formed.

🔗 Ancient Egypt 🔗 Maps 🔗 Geology

The Turin Papyrus Map is an ancient Egyptian map, generally considered the oldest surviving map of topographical interest from the ancient world. It is drawn on a papyrus reportedly discovered at Deir el-Medina in Thebes, collected by Bernardino Drovetti (known as Napoleon's Proconsul) in Egypt sometime before 1824 AD and now preserved in Turin's Museo Egizio. The map was drawn about 1150 BC by the well-known Scribe-of-the-Tomb Amennakhte, son of Ipuy. It was prepared for Ramesses IV's quarrying expedition to the Wadi Hammamat in the Eastern Desert, which exposes Precambrian rocks of the Arabian-Nubian Shield. The purpose of the expedition was to obtain blocks of bekhen-stone (metagraywacke sandstone) to be used for statues of the king.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

The MIM-104 Patriot is a surface-to-air missile (SAM) system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar component of the weapon system. The AN/MPQ-53 at the heart of the system is known as the "Phased Array Tracking Radar to Intercept on Target" which is a backronym for PATRIOT. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium Air Defense (HIMAD) system, and replaced the MIM-23 Hawk system as the U.S. Army's medium tactical air defense system. In addition to these roles, Patriot has been given the function of the U.S. Army's anti-ballistic missile (ABM) system, which is now Patriot's primary mission. The system is expected to stay fielded until at least 2040.

Patriot uses an advanced aerial interceptor missile and high-performance radar systems. Patriot was developed at Redstone Arsenal in Huntsville, Alabama, which had previously developed the Safeguard ABM system and its component Spartan and hypersonic speed Sprint missiles. The symbol for Patriot is a drawing of a Revolutionary War-era Minuteman.

Patriot systems have been sold to the Netherlands, Poland, Germany, Egypt, Japan, Israel, Saudi Arabia, Kuwait, Republic of China (Taiwan), Greece, Spain, United Arab Emirates, Qatar and Romania. South Korea purchased several second-hand Patriot systems from Germany after North Korea test-launched ballistic missiles to the Sea of Japan and proceeded with underground nuclear testing in 2006. Jordan also purchased several second-hand Patriot systems from Germany. Poland hosts training rotations of a battery of U.S. Patriot launchers. This started in the town of Morąg in May 2010 but was later moved further from the Russian border to Toruń and Ustka due to Russian objections. On December 4, 2012, NATO authorized the deployment of Patriot missile launchers in Turkey to protect the country from missiles fired in the civil war in neighboring Syria. Patriot was one of the first tactical systems in the U.S. Department of Defense's (DoD) to employ lethal autonomy in combat.

The Patriot system gained notoriety during the Persian Gulf War of 1991 with the claimed engagement of over 40 Iraqi Scud missiles, but those claims became a source of controversy. The system was successfully used against Iraqi missiles in 2003 Iraq War, and has been also used by Saudi and Emirati forces in the Yemen conflict against Houthi missile attacks. The Patriot system achieved its first undisputed shootdowns of enemy aircraft in the service of the Israeli Air Defense Command. Israeli MIM-104D batteries shot down two Hamas UAVs during Operation Protective Edge on August 31, 2014 and later, on September 23, 2014, an Israeli Patriot battery shot down a Syrian Air Force Sukhoi Su-24 which had penetrated Israeli airspace, achieving the first shootdown of a manned enemy aircraft in the world for the system.

🔗 Electronics

Resistor–transistor logic (RTL) (sometimes also transistor–resistor logic (TRL)) is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices. RTL is the earliest class of transistorized digital logic circuit; it was succeeded by diode–transistor logic (DTL) and transistor–transistor logic (TTL).

RTL circuits were first constructed with discrete components, but in 1961 it became the first digital logic family to be produced as a monolithic integrated circuit. RTL integrated circuits were used in the Apollo Guidance Computer, whose design begun in 1961 and which first flew in 1966.

🔗 Computing 🔗 Mathematics 🔗 Computing/Software 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Computing/Computer Security

Homomorphic encryption is a form of encryption that allows computation on ciphertexts, generating an encrypted result which, when decrypted, matches the result of the operations as if they had been performed on the plaintext.

Homomorphic encryption can be used for privacy-preserving outsourced storage and computation. This allows data to be encrypted and out-sourced to commercial cloud environments for processing, all while encrypted. In highly regulated industries, such as health care, homomorphic encryption can be used to enable new services by removing privacy barriers inhibiting data sharing. For example, predictive analytics in health care can be hard to apply due to medical data privacy concerns, but if the predictive analytics service provider can operate on encrypted data instead, these privacy concerns are diminished.

🔗 Russia 🔗 History 🔗 Skepticism 🔗 Sociology 🔗 Russia/language and literature of Russia 🔗 Russia/history of Russia

In politics and economics, a Potemkin village is any construction (literal or figurative) whose sole purpose is to provide an external façade to a country which is faring poorly, making people believe that the country is faring better, although statistics and charts would state otherwise. The term comes from stories of a fake portable village built solely to impress Empress Catherine II by her former lover Grigory Potemkin, during her journey to Crimea in 1787. While modern historians claim accounts of this portable village are exaggerated, the original story was that Potemkin erected phony portable settlements along the banks of the Dnieper River in order to impress the Russian Empress; the structures would be disassembled after she passed, and re-assembled farther along her route to be viewed again as if another example. The term is a translation of the Russian: потёмкинские деревни (IPA: /pɐˈtʲɵmkʲɪnskʲɪɪ dʲɪˈrʲɛvnʲɪ/; romanization: potyómkinskiye derévni).