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🔗 Computing 🔗 Computing/Networking

Sorcerer's Apprentice Syndrome (SAS) is a network protocol flaw in the original versions of TFTP. It was named after Goethe's poem "Der Zauberlehrling" (popularized by the "Sorcerer's Apprentice" segment of the animated film Fantasia), because the details of its operation closely resemble the disaster that befalls the sorcerer's apprentice: the problem resulted in an ever-growing replication of every packet in the transfer.

The problem occurred because of a known failure mode of the internetwork which, through a mistake on the part of the TFTP protocol designers, was not taken into account when the protocol was designed; the failure mode interacted with several details of the mechanisms of TFTP to produce SAS.

🔗 Time

Solar time is a calculation of the passage of time based on the position of the Sun in the sky. The fundamental unit of solar time is the day. Two types of solar time are apparent solar time (sundial time) and mean solar time (clock time).

🔗 Climate change 🔗 Europe 🔗 Energy

The European super grid is a possible future super grid that would ultimately interconnect the various European countries and the regions around Europe's borders – including North Africa, Kazakhstan, and Turkey – with a high-voltage direct current (HVDC) power grid.

It is envisaged that a European super grid would:

• lower the cost of power in all participating countries by allowing the entire region to share the most efficient power plants;
• pool load variability and power station unreliability, reducing the margin of inefficient spinning reserve and standby that have to be supplied;
• allow for wider use of renewable energy, particularly wind energy, from the concept that "it is always windy somewhere" – in particular it tends to be windy in the summer in North Africa, and windy in the winter in Europe;
• allow wide sharing of the total European hydro power resource, which is about 6 weeks of full load European output;
• decrease Europe's dependence on imported fuels.

🔗 Japan

In Japanese culture, a hatsuyume (Japanese: 初夢) is the first dream one has in the new year. Traditionally, the contents of such a dream would foretell the luck of the dreamer in the ensuing year. In Japan, the night of December 31 was often passed without sleeping, so the hatsuyume is often experienced during the night of January 1; the day after the night of the "first dream" is also known as the hatsuyume. This day is January 2 in the Gregorian calendar, but was different in the traditional Japanese calendar.

It is considered to be particularly good luck to dream of Mount Fuji, a hawk, and an eggplant. This belief has been in place since the early Edo period but there are various theories regarding the origins as to why this particular combination was considered to be auspicious. One theory suggests that this combination is lucky because Mount Fuji is Japan's highest mountain, the hawk is a clever and strong bird, and the word for eggplant (茄子, nasu or nasubi) suggests achieving something great (成す nasu). Another theory suggests that this combination arose because Mount Fuji, falconry, and early eggplants were favorites of the shōgun Tokugawa Ieyasu.

Although this superstition is well known in Japan, often memorized in the form ichi-Fuji, ni-taka, san-nasubi (一富士、二鷹、三茄子; 1. Fuji, 2. Hawk, 3. Eggplant), the continuation of the list is not as well known. The continuation is yon-sen, go-tabako, roku-zatō (四扇、五煙草、六座頭; 4. Fan, 5. Tobacco, 6. Blind acupressurer). The origins of this trio are less well known, and it is unclear whether they were added after the original three or whether the list of six originated at the same time.

🔗 Psychology 🔗 Linguistics 🔗 History of Science 🔗 Linguistics/Applied Linguistics 🔗 Portugal 🔗 Galicia

Saudade (European Portuguese: [sɐwˈðaðɨ] ; Brazilian Portuguese: [sawˈdadʒi] ; Galician: [sawˈðaðɪ]; Northeast Brazil: [sawˈdadi]). (English: ; plural saudades) in Portuguese and Galician is an emotional state of melancholic or profoundly nostalgic longing for a beloved yet absent someone or something. It derives from the Latin word for solitude. It is often associated with a repressed understanding that one might never encounter the object of longing ever again. It is a recollection of feelings, experiences, places, or events, often elusive, that cause a sense of separation from the exciting, pleasant, or joyous sensations they once caused. Duarte Nunes Leão defines saudade as, "Memory of something with a desire for it". In Brazil, the day of saudade is officially celebrated on 30 January. It is not a widely acknowledged day in Portugal.

🔗 Dogs 🔗 Psychology

Intelligent disobedience occurs where a service animal trained to help a disabled person goes directly against the owner's instructions in an effort to make a better decision. This behavior is a part of the dog's training and is central to a service animal's success on the job. The concept of intelligent disobedience has been in use and a common part of service animals' training since at least 1936.

🔗 Astronomy 🔗 Geology 🔗 Geology/Meteorites 🔗 Solar System

The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus.

🔗 Religion 🔗 Classical Greece and Rome 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Latin 🔗 Christianity 🔗 Jewish history 🔗 Occult 🔗 Mysticism

The Sator Square (or Rotas Square) is a word square containing a five-word Latin palindrome. The earliest form has ROTAS as the top line, but in time the version with SATOR on the top line became dominant. It is a 5X5 square made up of five 5-letter words, thus consisting of 25 letters in total. These 25 letters are all derived from 8 Latin letters: 5 consonants (S, T, R, P, N) and 3 vowels (A, E, O).

In particular, this is a square 2D palindrome, which is when a square text admits four symmetries: identity, two diagonal reflections, and 180 degree rotation. As can be seen, the text may be read top-to-bottom, bottom-to-top, left-to-right, or right-to-left; and it may be rotated 180 degrees and still be read in all those ways.

The Sator Square is the earliest dateable 2D palindrome. It was found in the ruins of Pompeii, at Herculaneum, a city buried in the ash of Mount Vesuvius in 79 AD. It consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas." Its translation has been the subject of speculation with no clear consensus; see below for details.

Other 2D Palindrome examples may be found carved on stone tablets or pressed into clay before being fired.

🔗 Computing 🔗 Military history 🔗 Military history/Military science, technology, and theory

Fifth-generation warfare (5GW) is warfare that is conducted primarily through non-kinetic military action, such as social engineering, misinformation, cyberattacks, along with emerging technologies such as artificial intelligence and fully autonomous systems. Fifth generation warfare has been described by Daniel Abbot as a war of "information and perception". There is no widely agreed upon definition of fifth-generation warfare, and it has been rejected by some scholars, including William S. Lind, who was one of the original theorists of fourth-generation warfare.

🔗 Physics

Certain systems can achieve negative thermodynamic temperature; that is, their temperature can be expressed as a negative quantity on the Kelvin or Rankine scales. This should be distinguished from temperatures expressed as negative numbers on non-thermodynamic Celsius or Fahrenheit scales, which are nevertheless higher than absolute zero.

The absolute temperature (Kelvin) scale can be understood loosely as a measure of average kinetic energy. Usually, system temperatures are positive. However, in particular isolated systems, the temperature defined in terms of Boltzmann's entropy can become negative.

The possibility of negative temperatures was first predicted by Lars Onsager in 1949, in his analysis of classical point vortices confined to a finite area. Confined point vortices are a system with bounded phase space as their canonical momenta are not independent degrees of freedom from their canonical position coordinates. Bounded phase space is the essential property that allows for negative temperatures, and such temperatures can occur in both classical and quantum systems. As shown by Onsager, a system with bounded phase space necessarily has a peak in the entropy as energy is increased. For energies exceeding the value where the peak occurs, the entropy decreases as energy increases, and high-energy states necessarily have negative Boltzmann temperature.

A system with a truly negative temperature on the Kelvin scale is hotter than any system with a positive temperature. If a negative-temperature system and a positive-temperature system come in contact, heat will flow from the negative- to the positive-temperature system. A standard example of such a system is population inversion in laser physics.

Temperature is loosely interpreted as the average kinetic energy of the system's particles. The existence of negative temperature, let alone negative temperature representing "hotter" systems than positive temperature, would seem paradoxical in this interpretation. The paradox is resolved by considering the more rigorous definition of thermodynamic temperature as the tradeoff between internal energy and entropy contained in the system, with "coldness", the reciprocal of temperature, being the more fundamental quantity. Systems with a positive temperature will increase in entropy as one adds energy to the system, while systems with a negative temperature will decrease in entropy as one adds energy to the system.

Thermodynamic systems with unbounded phase space cannot achieve negative temperatures: adding heat always increases their entropy. The possibility of a decrease in entropy as energy increases requires the system to "saturate" in entropy. This is only possible if the number of high energy states is limited. For a system of ordinary (quantum or classical) particles such as atoms or dust, the number of high energy states is unlimited (particle momenta can in principle be increased indefinitely). Some systems, however (see the examples below), have a maximum amount of energy that they can hold, and as they approach that maximum energy their entropy actually begins to decrease. The limited range of states accessible to a system with negative temperature means that negative temperature is associated with emergent ordering of the system at high energies. For example in Onsager's point-vortex analysis negative temperature is associated with the emergence of large-scale clusters of vortices. This spontaneous ordering in equilibrium statistical mechanics goes against common physical intuition that increased energy leads to increased disorder.