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The Hierapolis sawmill was a Roman water-powered stone sawmill at Hierapolis, Asia Minor (modern-day Turkey). Dating to the second half of the 3rd century AD, the sawmill is considered the earliest known machine to combine a crank with a connecting rod to form a crank slider mechanism.

The watermill is evidenced by a raised relief on the sarcophagus of a certain Marcus Aurelius Ammianos, a local miller. On the pediment a waterwheel fed by a mill race is shown powering via a gear train two frame saws cutting rectangular blocks by the way of connecting rods and, through mechanical necessity, cranks (see diagram). The accompanying inscription is in Greek and attributes the mechanism to Ammianos' "skills with wheels".

Body doubling or parallel working is a strategy used to initiate and complete tasks, such as household chores or writing and other computer tasks. It involves the physical presence, virtual presence through a phone call, videotelephony or social media presence, of someone with whom one shares their goals, which makes it more likely to achieve them. For some people, it works best to both do similar tasks, while for others, just being in the same (virtual) room is enough.

It was partially popularized by those with attention deficit hyperactivity disorder (ADHD) to help manage symptoms. Its usefulness has also been noted by those with autism, but efficacy is not clearly known as long term studies have not been conducted on the topic. In 2023, J. Russel Ramsay, professor of clinical psychiatry at the Perelman School of Medicine and co-director of the ADHD treatment and research program of the University of Pennsylvania, noted that, while extensive research on the strategy's effect on productivity doesn't exist, "the idea of externalizing motivation is a longstanding evidence-based mechanism for managing ADHD."

ADHD body doubling comes into play allowing individuals with ADHD to perform and complete tasks more easily and with less distractions, where otherwise they might struggle more. "ADHD body doubling is a productivity strategy used by individuals with ADHD to finish possibly annoying jobs while having another person beside them."

Body doubling is said to aid individuals with focus and productivity while working. Another person, known as a 'body double' sits alongside the individual with ADHD to help them focus while completing a certain task. The role of this individual is to not partake in the task but, more importantly, serve as a support system and create a welcoming environment that allows the individual to focus by reducing any distractions. The idea of body doubling allows for specific reminders to the individual to stay on task which helps alleviate the symptoms of ADHD.

In condensed matter physics, Hofstadter's butterfly describes the spectral properties of non-interacting two dimensional electrons in a magnetic field. The fractal, self-similar, nature of the spectrum was discovered in the 1976 Ph.D. work of Douglas Hofstadter and is one of the early examples of computer graphics. The name reflects the visual resemblance of the figure on the right to a swarm of butterflies flying to infinity.

The Hofstadter butterfly plays an important role in the theory of the integer quantum Hall effect, and D.J. Thouless has been awarded the Nobel prize in physics in 2016 for the discovery that the wings of the butterfly are characterized by Chern integers, the quantized Hall conductances discovered in 1980 by Klaus von Klitzing for which he has been awarded the Nobel prize in 1985. The colors in the diagram reflect the different Chern numbers.

Better Portable Graphics (BPG) is a file format for coding digital images, which was created by programmer Fabrice Bellard in 2014. He has proposed it as a replacement for the JPEG image format as the more compression-efficient alternative in terms of image quality or file size.

It is based on the intra-frame encoding of the High Efficiency Video Coding (HEVC) video compression standard. Tests on photographic images in July 2014 found that BPG produced smaller files for a given quality than JPEG, JPEG XR and WebP.

The format has been designed to be portable and work in low memory environments, and used in portable handheld and IoT devices, where those properties are particularly important. Current research works on designing and developing more energy-efficient BPG hardware which can then be integrated in portable devices such as digital cameras.

While there is no built-in native support for BPG in any mainstream browsers, websites can still deliver BPG images to all browsers by including a JavaScript library written by Bellard.

In 1983, David H. D. Warren designed an abstract machine for the execution of Prolog consisting of a memory architecture and an instruction set. This design became known as the Warren Abstract Machine (WAM) and has become the de facto standard target for Prolog compilers.

Commonplace books (or commonplaces) are a way to compile knowledge, usually by writing information into books. They have been kept from antiquity, and were kept particularly during the Renaissance and in the nineteenth century. Such books are essentially scrapbooks filled with items of every kind: recipes, quotes, letters, poems, tables of weights and measures, proverbs, prayers, legal formulas. Commonplaces are used by readers, writers, students, and scholars as an aid for remembering useful concepts or facts. Each one is unique to its creator's particular interests but they almost always include passages found in other texts, sometimes accompanied by the compiler's responses. They became significant in Early Modern Europe.

"Commonplace" is a translation of the Latin term locus communis (from Greek tópos koinós, see literary topos) which means "a general or common topic", such as a statement of proverbial wisdom. In this original sense, commonplace books were collections of such sayings, such as John Milton's example. Scholars now understand them to include manuscripts in which an individual collects material which have a common theme, such as ethics, or exploring several themes in one volume. Commonplace books are private collections of information, but they are not diaries or travelogues.

In 1685 the English Enlightenment philosopher John Locke wrote a treatise in French on commonplace books, translated into English in 1706 as A New Method of Making Common-Place-Books, "in which techniques for entering proverbs, quotations, ideas, speeches were formulated. Locke gave specific advice on how to arrange material by subject and category, using such key topics as love, politics, or religion. Commonplace books, it must be stressed, are not journals, which are chronological and introspective."

By the early eighteenth century they had become an information management device in which a note-taker stored quotations, observations and definitions. They were used in private households to collate ethical or informative texts, sometimes alongside recipes or medical formulae. For women, who were excluded from formal higher education, the commonplace book could be a repository of intellectual references. The gentlewoman Elizabeth Lyttelton kept one from the 1670s to 1713 and a typical example was published by Mrs Anna Jameson in 1855, including headings such as Ethical Fragments; Theological; Literature and Art. Commonplace books were used by scientists and other thinkers in the same way that a database might now be used: Carl Linnaeus, for instance, used commonplacing techniques to invent and arrange the nomenclature of his Systema Naturae (which is the basis for the system used by scientists today). The commonplace book was often a lifelong habit: for example the English-Australian artist Georgina McCrae kept a commonplace book from 1828-1865.

Working memory training is intended to improve a person's working memory. Working memory is a central intellectual faculty, linked to IQ, ageing, and mental health. It has been claimed that working memory training programs are effective means, both for treating specific medical conditions associated with working memory deficit, and for general increase in cognitive capacity among healthy neurotypical adults.

Individual studies of the topic show different, and sometime contradictory, results, and as one meta study puts it, asking the question “Does cognitive training improve intelligence?” is as inappropriate as asking “Does medicine cure disease?”, since none of them specify which particular intervention (which medicine or working memory training program) is being evaluated, for alleviating which condition is it applied (ADHD, stroke, general cognitive improvement etc.), and under what circumstances is it administered (selection criteria, adherence rate, outcome variables etc.).

In an influential metastudy from 2012, highly critical to cognitive training, analysed 23 studies with 30 group comparisons, and concluded that clinical memory training programs produce reliable short-term improvements in working memory skills in children and adults with ADHD, but also that there is no evidence that such effects can be maintained long-term without additional follow-up training. Three years later, another metastudy reached the opposite conclusion, that working memory training does have consistent and useful effects, not just on the type of working memory tests that are practiced, but also at other non-trained tasks and everyday life. Since then, a range of additional clinical experiments have been completed, with larger sample sizes, clearly defined control groups, and more uniform treatment of outcome variables. While the evidence is still far from unanimous, there are several experimental studies of working memory training that have shown beneficial effects for people with ADHD, those who have suffered stroke or traumatic brain injury, children who have undergone cancer treatment, as well as for normally developing children.

The word mamihlapinatapai is derived from the Yaghan language of Tierra del Fuego, listed in The Guinness Book of World Records as the "most succinct word", and is considered one of the hardest words to translate. It has been translated as "a look that without words is shared by two people who want to initiate something, but that neither will start" or "looking at each other hoping that the other will offer to do something which both parties desire but are unwilling to do".

A romantic interpretation of the meaning has also been given, as "that look across the table when two people are sharing an unspoken but private moment. When each knows the other understands and is in agreement with what is being expressed. An expressive and meaningful silence."

In German folklore, a wolpertinger (also called wolperdinger or woiperdinger) is an animal said to inhabit the alpine forests of Bavaria and Baden-Württemberg in Germany.