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🔗 Books 🔗 Urban studies and planning

The High Cost of Free Parking is an urban planning book by UCLA professor Donald Shoup dealing with the costs of free parking on society. It is structured as a criticism of the planning and regulation of parking and recommends that parking be built and allocated according to its fair market value. It incorporates elements of Shoup's Georgist philosophy.

The book was originally published in 2005 by the American Planning Association and the Planners Press. A revised edition was released in 2011 by Routledge.

The cryotron is a switch that operates using superconductivity. The cryotron works on the principle that magnetic fields destroy superconductivity. This simple device consists of two superconducting wires (e.g. tantalum and niobium) with different critical temperature (Tc). The cryotron was invented by Dudley Allen Buck of the Massachusetts Institute of Technology Lincoln Laboratory.

As described by Buck, a straight wire of tantalum (having lower Tc) is wrapped around with a wire of niobium in a single layer coil. Both wires are electrically isolated from each other. When this device is immersed in a liquid helium bath both wires become superconducting and hence offer no resistance to the passage of electric current. Tantalum in superconducting state can carry large amount of current as compared to its normal state. Now when current is passed through the niobium coil (wrapped around tantalum) it produces a magnetic field, which in turn reduces (kills) the superconductivity of the tantalum wire and hence reduces the amount of the current that can flow through the tantalum wire. Hence one can control the amount of the current that can flow in the straight wire with the help of small current in the coiled wire. We can think of the tantalum straight wire as a "gate" and the coiled niobium as a "control".

The article by Buck includes descriptions of several logic circuits implemented using cryotrons, including: one stage of a binary adder, carry network, binary accumulator stage, and two stages of a cryotron stepping register.

A planar cryotron using thin films of lead and tin was developed in 1957 by John Bremer at General Electric's General Engineering Lab in Schenectady, New York. This was one of the first integrated circuits, although using superconductors rather than semiconductors. In the next few years, a demonstration computer was made and arrays with 2000 devices operated. A short history of this work is in the November 2007 newsletter of the IEEE History Center.

Juri Matisoo developed a version of the cryotron incorporating a Josephson junction switched by the magnetic field from a control wire. He also explained the shortcomings of traditional cryotrons in which the superconductive material must transition between superconducting and normal states to switch the device, and thus switch relatively slowly. Matisoo's cryotron switched between a conducting state in which 'pair tunneling' of electrons through the gate took place and a 'resistive' state where only single electrons were able to tunnel. The circuit was (like the traditional cryotron) capable of some amplification (i.e gain greater than unity) had a switching rate of less than 800 picoseconds. Although the requirement for cryogenic cooling limited its practicality, it wasn't until the late 2010s that commercial transistors came close to matching this performance.

There have been periods of renewed interest in various types of cryotron, IBM experimented with using them for limited applications in supercomputers during the 1980s and (as of 2020) there has been some investigation of their potential applications both to I/O and logic in prototype quantum computers.

🔗 Mathematics

In number theory, a weird number is a natural number that is abundant but not semiperfect.

In other words, the sum of the proper divisors (divisors including 1 but not itself) of the number is greater than the number, but no subset of those divisors sums to the number itself.

🔗 Crime 🔗 Classical Greece and Rome 🔗 Greece 🔗 Egypt

Papyrus Oxyrhynchus 69 (P. Oxy. 69) is a complaint about a robbery, written in Greek. The manuscript was written on papyrus in the form of a sheet. It was discovered by Grenfell and Hunt in 1897 in Oxyrhynchus. The document was written on 21 November 190. Currently it is housed in the Haskell Oriental Institute at the University of Chicago (2061). The text was published by Grenfell and Hunt in 1898.

The beginning of the letter is lost. It is a petition to an unknown official describing the theft of some barley and asking that an investigation be carried out. The author is unknown. The measurements of the fragment are 178 by 115 mm. The description of the crime scene is quite detailed:

... they broke down a door that led into the public street and had been blocked up with bricks, probably using a log of wood as a battering-ram. They then entered the house and contented themselves with taking what was stored there, 10 artabae of barley, which they carried off by the same way. We guessed that this was removed piecemeal by the said door from the marks of a rope dragged along in that direction, and pointed out this fact to the chief of the police of that village and to the other officials.

10 artabae are equivalent to approximately 30–40 kilograms (66–88 lb) of barley.

🔗 Chess

Los Alamos chess (or anti-clerical chess) is a chess variant played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. This program was written at Los Alamos Scientific Laboratory by Paul Stein and Mark Wells for the MANIAC I computer in 1956. The reduction of the board size and the number of pieces from standard chess was due to the very limited capacity of computers at the time.

The program was very simple, containing only about 600 instructions. It was mostly a minimax tree search and could look four plies ahead. For scoring the board at the end of the four-ply lookahead, it estimates a score for material and a score for mobility, then adds them up. Pseudocode for the chess program is described in Figure 11.4 of Newell, 2019. In 1958, a revised version was written for MANIAC II for full 8×8 chess, though its pseudocode was never published. There is a record of a single game by it, circa November 1958 (Table 11.2 of Newell, 2019).

Cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore. The process is based on the principle that precious metals do not oxidise or react chemically, unlike the base metals, so when they are heated at high temperatures, the precious metals remain apart, and the others react, forming slags or other compounds.

Since the Early Bronze Age, the process was used to obtain silver from smelted lead ores. By the Middle Ages and the Renaissance, cupellation was one of the most common processes for refining precious metals. By then, fire assays were used for assaying minerals, that is, testing fresh metals such as lead and recycled metals to know their purity for jewellery and coin making. Cupellation is still in use today.

The International Meridian Conference was a conference held in October 1884 in Washington, D.C., in the United States, to determine a prime meridian for international use. The conference was held at the request of U.S. President Chester A. Arthur. The subject to discuss was the choice of "a meridian to be employed as a common zero of longitude and standard of time reckoning throughout the world". It resulted in the recommendation of the Greenwich Meridian as the international standard for zero degrees longitude.

🔗 Philately 🔗 Japan 🔗 Japan/Infrastructure 🔗 Japan/Law and government

The Japanese addressing system is used to identify a specific location in Japan. When written in Japanese characters, addresses start with the largest geographical entity and proceed to the most specific one. When written in Latin characters, addresses follow the convention used by most Western addresses and start with the smallest geographic entity (typically a house number) and proceed to the largest. The Japanese system is complex and idiosyncratic, the product of the natural growth of urban areas, as opposed to the systems used in cities that are laid out as grids and divided into quadrants or districts.

🔗 Aviation 🔗 Disaster management 🔗 Aviation/Aviation accident 🔗 Lists

This list of missing aircraft includes all of the aircraft that have disappeared in flight for reasons that have never been definitely determined. According to Annex 13 of the International Civil Aviation Organization, an aircraft is considered to be missing "when the official search has been terminated and the wreckage has not been located". However, there still remains a "grey area" on how much wreckage needs to be found for a plane to be declared "recovered". This list does not include every aviator, or air passenger that has ever gone missing as these are separate categories.

In the tables below, each missing aircraft is defined (in the Aircraft column) using one or more identifying features. If the aircraft was known by a custom or personalized name (e.g. Pathfinder), that name is presented first (in italics) followed by the aircraft type (in parentheses). The make of aircraft, although not necessarily a unique identifier, is also provided where appropriate. Aircraft registrations began to be used in the early 20th century for individual identification, so this is also included in the later tables (in parentheses).