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🔗 Molecular and Cell Biology 🔗 Microbiology 🔗 Genetics 🔗 Citizendium Porting 🔗 Evolutionary biology

Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the evolution of many organisms.

Horizontal gene transfer is the primary mechanism for the spread of antibiotic resistance in bacteria, and plays an important role in the evolution of bacteria that can degrade novel compounds such as human-created pesticides and in the evolution, maintenance, and transmission of virulence. It often involves temperate bacteriophages and plasmids. Genes responsible for antibiotic resistance in one species of bacteria can be transferred to another species of bacteria through various mechanisms of HGT such as transformation, transduction and conjugation, subsequently arming the antibiotic resistant genes' recipient against antibiotics. The rapid spread of antibiotic resistance genes in this manner is becoming medically challenging to deal with. Ecological factors may also play a role in the LGT of antibiotic resistant genes. It is also postulated that HGT promotes the maintenance of a universal life biochemistry and, subsequently, the universality of the genetic code.

Most thinking in genetics has focused upon vertical transfer, but the importance of horizontal gene transfer among single-cell organisms is beginning to be acknowledged.

Gene delivery can be seen as an artificial horizontal gene transfer, and is a form of genetic engineering.

🔗 Robotics 🔗 Software 🔗 Software/Computing

VxWorks is a real-time operating system (RTOS) developed as proprietary software by Wind River Systems, a wholly owned subsidiary of TPG Capital, US. First released in 1987, VxWorks is designed for use in embedded systems requiring real-time, deterministic performance and, in many cases, safety and security certification, for industries, such as aerospace and defense, medical devices, industrial equipment, robotics, energy, transportation, network infrastructure, automotive, and consumer electronics.

VxWorks supports Intel architecture, POWER architecture, ARM architectures and RISC-V. The RTOS can be used in multicore asymmetric multiprocessing (AMP), symmetric multiprocessing (SMP), and mixed modes and multi-OS (via Type 1 hypervisor) designs on 32- and 64-bit processors.

VxWorks comes with the kernel, middleware, board support packages, Wind River Workbench development suite and complementary third-party software and hardware technologies. In its latest release, VxWorks 7, the RTOS has been re-engineered for modularity and upgradeability so the OS kernel is separate from middleware, applications and other packages. Scalability, security, safety, connectivity, and graphics have been improved to address Internet of Things (IoT) needs.

🔗 Computing 🔗 Classical Greece and Rome 🔗 Greece 🔗 Astronomy 🔗 History of Science 🔗 Alternative Views 🔗 Time

The Antikythera mechanism (, ) is an ancient hand powered Greek analogue computer which has also been described as the first example of such device used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.

This artefact was retrieved from the sea in 1901, and identified on 17 May 1902 as containing a gear by archaeologist Valerios Stais, among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera. The instrument is believed to have been designed and constructed by Greek scientists and has been variously dated to about 87 BC, or between 150 and 100 BC, or to 205 BC, or to within a generation before the shipwreck, which has been dated to approximately 70–60 BC.

The device, housed in the remains of a 34 cm × 18 cm × 9 cm (13.4 in × 7.1 in × 3.5 in) wooden box, was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 14 centimetres (5.5 in) in diameter and originally had 223 teeth.

It is a complex clockwork mechanism composed of at least 30 meshing bronze gears. A team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine.

Detailed imaging of the mechanism suggests that it had 37 gear wheels enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and even to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction.

The knowledge of this technology was lost at some point in antiquity. Similar technological works later appeared in the medieval Byzantine and Islamic worlds, but works with similar complexity did not appear again until the development of mechanical astronomical clocks in Europe in the fourteenth century. All known fragments of the Antikythera mechanism are now kept at the National Archaeological Museum in Athens, along with a number of artistic reconstructions and replicas of the mechanism to demonstrate how it may have looked and worked.

🔗 Statistics 🔗 Futures studies

The Delphi method or Delphi technique ( DEL-fy; also known as Estimate-Talk-Estimate or ETE) is a structured communication technique or method, originally developed as a systematic, interactive forecasting method which relies on a panel of experts. The technique can also be adapted for use in face-to-face meetings, and is then called mini-Delphi or Estimate-Talk-Estimate (ETE). Delphi has been widely used for business forecasting and has certain advantages over another structured forecasting approach, prediction markets.

Delphi is based on the principle that forecasts (or decisions) from a structured group of individuals are more accurate than those from unstructured groups. The experts answer questionnaires in two or more rounds. After each round, a facilitator or change agent provides an anonymised summary of the experts' forecasts from the previous round as well as the reasons they provided for their judgments. Thus, experts are encouraged to revise their earlier answers in light of the replies of other members of their panel. It is believed that during this process the range of the answers will decrease and the group will converge towards the "correct" answer. Finally, the process is stopped after a predefined stop criterion (e.g., number of rounds, achievement of consensus, stability of results), and the mean or median scores of the final rounds determine the results.

Special attention has to be paid to the formulation of the Delphi theses and the definition and selection of the experts in order to avoid methodological weaknesses that severely threaten the validity and reliability of the results.

🔗 Philosophy 🔗 Politics 🔗 Psychology 🔗 Philosophy/Social and political philosophy 🔗 Sociology

A purity spiral is a theory which argues for the existence of a form of groupthink in which it becomes more beneficial to hold certain views than to not hold them, and more extreme views are rewarded while expressing doubt, nuance, or moderation is punished (a process sometimes called "moral outbidding"). It is argued that this feedback loop leads to members competing to demonstrate the zealotry or purity of their views.

A purity spiral is argued to occur when a community's primary focus becomes implementing a single value that has no upper limit, and where that value does not have an agreed interpretation.

Wikipedia offers free copies of all available content to interested users. These databases can be used for mirroring, personal use, informal backups, offline use or database queries (such as for Wikipedia:Maintenance). All text content is licensed under the Creative Commons Attribution-ShareAlike 4.0 License (CC-BY-SA), and most is additionally licensed under the GNU Free Documentation License (GFDL). Images and other files are available under different terms, as detailed on their description pages. For our advice about complying with these licenses, see Wikipedia:Copyrights.

Some of the many ways to read Wikipedia while offline:

• Kiwix: (§ Kiwix) – index of images (2024)
• XOWA: (§ XOWA) – index of images (2015)
• WikiTaxi: § WikiTaxi (for Windows)
• aarddict: § Aard Dictionary / Aard 2
• BzReader: § BzReader and MzReader (for Windows)
• WikiFilter: § WikiFilter
• Wikipedia on rockbox: § Wikiviewer for Rockbox
• Selected Wikipedia articles as a printed document: Help:Printing

Some of them are mobile applications – see "List of Wikipedia mobile applications".

🔗 Typography

A fleuron (;), also known as printers' flower, is a typographic element, or glyph, used either as a punctuation mark or as an ornament for typographic compositions. Fleurons are stylized forms of flowers or leaves; the term derives from the Old French: floron ("flower"). Robert Bringhurst in The Elements of Typographic Style calls the forms "horticultural dingbats". A commonly-encountered fleuron is the ❦, the floral heart or hedera (ivy leaf). It is also known as an aldus leaf (after Italian Renaissance printer Aldus Manutius).

🔗 International relations 🔗 Death 🔗 Law 🔗 International relations/International law

A custom of the sea is a custom said to be practiced by the officers and crew of ships and boats in the open sea, as distinguished from maritime law, which is a distinct and coherent body of law governing maritime questions and offenses.

Among these customs was the practice of cannibalism among shipwrecked survivors, by the drawing of lots to decide who would be killed and eaten so that the others might survive.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/African military history

The Vela incident, also known as the South Atlantic Flash, was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the Prince Edward Islands in the Indian Ocean.

The cause of the flash remains officially unknown, and some information about the event remains classified. While it has been suggested that the signal could have been caused by a meteoroid hitting the satellite, the previous 41 double flashes detected by the Vela satellites were caused by nuclear weapons tests. Today, most independent researchers believe that the 1979 flash was caused by a nuclear explosion — perhaps an undeclared nuclear test carried out by South Africa and Israel.