To stay up to date you can also follow on Mastodon.

🔗 Medicine 🔗 Physiology 🔗 Scuba diving 🔗 Physiology/neuro

The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It optimizes respiration by preferentially distributing oxygen stores to the heart and brain, enabling submersion for an extended time.

The diving reflex is exhibited strongly in aquatic mammals, such as seals, otters, dolphins, and muskrats, and exists as a lesser response in other animals, including adult humans, babies up to 6 months old (see infant swimming), and diving birds, such as ducks and penguins.

The diving reflex is triggered specifically by chilling and wetting the nostrils and face while breath-holding, and is sustained via neural processing originating in the carotid chemoreceptors. The most noticeable effects are on the cardiovascular system, which displays peripheral vasoconstriction, slowed heart rate, redirection of blood to the vital organs to conserve oxygen, release of red blood cells stored in the spleen, and, in humans, heart rhythm irregularities. Although aquatic animals have evolved profound physiological adaptations to conserve oxygen during submersion, the apnea and its duration, bradycardia, vasoconstriction, and redistribution of cardiac output occur also in terrestrial animals as a neural response, but the effects are more profound in natural divers.

🔗 Time

The Doomsday rule is an algorithm of determination of the day of the week for a given date. It provides a perpetual calendar because the Gregorian calendar moves in cycles of 400 years. The algorithm for mental calculation was devised by John Conway in 1973, drawing inspiration from Lewis Carroll's perpetual calendar algorithm. It takes advantage of each year having a certain day of the week, called the doomsday, upon which certain easy-to-remember dates fall; for example, 4/4, 6/6, 8/8, 10/10, 12/12, and the last day of February all occur on the same day of the week in any year. Applying the Doomsday algorithm involves three steps: Determination of the anchor day for the century, calculation of the doomsday for the year from the anchor day, and selection of the closest date out of those that always fall on the doomsday, e.g., 4/4 and 6/6, and count of the number of days (modulo 7) between that date and the date in question to arrive at the day of the week. The technique applies to both the Gregorian calendar and the Julian calendar, although their doomsdays are usually different days of the week.

The algorithm is simple enough that it can be computed mentally. Conway can usually give the correct answer in under two seconds. To improve his speed, he practices his calendrical calculations on his computer, which is programmed to quiz him with random dates every time he logs on.

🔗 Computing 🔗 Computing/Software 🔗 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.

🔗 Biography 🔗 Physics 🔗 Biography/science and academia 🔗 Astronomy 🔗 Physics/Biographies 🔗 Biophysics

Thomas Gold (also known as Tommy Gold), (May 22, 1920 – June 22, 2004) was an Austrian-born astrophysicist, a professor of astronomy at Cornell University, a member of the U.S. National Academy of Sciences, and a Fellow of the Royal Society (London). Gold was one of three young Cambridge scientists who in 1948 proposed the now mostly abandoned "steady state" hypothesis of the universe. Gold's work crossed academic and scientific boundaries, into biophysics, astronomy, aerospace engineering, and geophysics.

🔗 Computing

The CueCat, styled :CueCat with a leading colon, is a cat-shaped handheld barcode reader that was given away free to Internet users starting in 2000 by the now-defunct Digital Convergence Corporation. The CueCat was named CUE for the unique bar code which the device scanned and CAT as a play on "Keystroke Automation Technology" and it enabled a user to open a link to an Internet URL by scanning a barcode — called a "cue" by Digital Convergence — appearing in an article or catalog or on some other printed matter. In this way, a user could be directed to a web page containing related information without having to enter a URL. The company asserted that the ability of the device to direct users to a specific URL, rather than a domain name, was valuable. In addition, television broadcasters could use an audio tone in programs or commercials that, if a TV was connected to a computer via an audio cable, acted as a web address shortcut.

The CueCat connected to computers using the PS/2 keyboard port and USB, and communicated to desktop "CRQ" software running on Windows 32-bit and Mac OS 9 operating systems. Users of this software were required to register with their ZIP code, gender, and email address. This registration process enabled the device to deliver relevant content to a single or multiple users in a household.

By year-end 2001, Codes could no longer be generated for the device or scanned with the device. However, third-party software can decode the lightweight encryption in the device.

🔗 United States/U.S. Government 🔗 United States 🔗 Mass surveillance 🔗 Cryptography 🔗 Cryptography/Computer science

The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured “voice and data messages" with a built-in backdoor. It was intended to be adopted by telecommunications companies for voice transmission. It can encipher and decipher messages. It was part of a Clinton Administration program to “allow Federal, State, and local law enforcement officials the ability to decode intercepted voice and data transmissions." “Each clipper chip ha[d] a unique serial number and a secret ‘unit key,’ programmed into the chip when manufactured." This way, each device was meant to be different from the next.

It was announced in 1993 and by 1996 was entirely defunct.

🔗 Trains 🔗 Trains/Monorail

The Wuppertaler Schwebebahn (Wuppertal Suspension Railway) is a suspension railway in Wuppertal, Germany.

Its full name is Anlage einer elektrischen Hochbahn (Schwebebahn), System Eugen Langen. ("Electric Elevated Railway (Suspension Railway) Installation, Eugen Langen System") It is the oldest electric elevated railway with hanging cars in the world and is a unique system.

Designed by Eugen Langen to sell to the city of Berlin, the installation with elevated stations was built in Barmen, Elberfeld and Vohwinkel between 1897 and 1903; the first track opened in 1901. The Schwebebahn is still in use today as a normal means of local public transport, moving 25 million passengers annually (2008).

The Schwebebahn runs along a route of 13.3 kilometres (8.3 mi), at a height of about 12 metres (39 ft) above the River Wupper between Oberbarmen and Sonnborner Straße (10 kilometres or 6.2 miles) and about 8 metres (26 ft) above the valley road between Sonnborner Straße and Vohwinkel (3.3 kilometres or 2.1 miles). At one point the railway crosses the A46 motorway. The entire trip takes about 30 minutes. The Schwebebahn operates within the VRR transport association and accepts tickets issued by the VRR companies.

Due to an accident in November 2018, the Schwebebahn was closed down for nearly nine months. It re-opened on 1 August 2019.

🔗 Lists 🔗 Software 🔗 Software/Computing

This is a list of notable custom software projects which have significantly failed to achieve some or all of their objectives, either temporarily or permanently, and/or have suffered from significant cost overruns. For a list of successful major custom software projects, see Custom software#Major project successes.

Note that failed projects, and projects running over budget, are not necessarily the sole fault of the employees or businesses creating the software. In some cases, problems may be due partly to problems with the purchasing organisation, including poor requirements, over-ambitious requirements, unnecessary requirements, poor contract drafting, poor contract management, poor end-user training, or poor operational management.

🔗 Databases 🔗 Databases/Computer science

Codd's twelve rules are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS). They are sometimes jokingly referred to as "Codd's Twelve Commandments".