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

🔗 International relations 🔗 Philately 🔗 Amateur radio

An international reply coupon (IRC) is a coupon that can be exchanged for one or more postage stamps representing the minimum postage for an unregistered priority airmail letter of up to twenty grams sent to another Universal Postal Union (UPU) member country. IRCs are accepted by all UPU member countries.

UPU member postal services are obliged to exchange an IRC for postage, but are not obliged to sell them.

The purpose of the IRC is to allow a person to send someone in another country a letter, along with the cost of postage for a reply. If the addressee is within the same country, there is no need for an IRC because a self-addressed stamped envelope (SASE) or return postcard will suffice; but if the addressee is in another country an IRC removes the necessity of acquiring foreign postage or sending appropriate currency.

🔗 Iceland 🔗 Lighthouses

Þrídrangaviti Lighthouse (transliterated as Thridrangaviti) is an active lighthouse 7.2 kilometres (4.5 miles) off the southwest coast of Iceland, in the archipelago of Vestmannaeyjar. It is often described as one of the most isolated lighthouses in the world. Þrídrangar means "three rock pillars", referring to the three named sea stacks at that location: Stóridrangur (on which the lighthouse stands), Þúfudrangur, and Klofadrangur. The lighthouse was commissioned on 5 July 1942.

🔗 Biography 🔗 Mathematics 🔗 Biography/science and academia 🔗 Chicago 🔗 Armenia

Alexander (Smbat) Abian (January 1, 1923 – July 24, 1999) was an Iranian-born Armenian-American mathematician who taught for over 25 years at Iowa State University and became notable for his frequent posts to various Usenet newsgroups, and his advocacy for the destruction of the Moon.

🔗 Psychology 🔗 Disability

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.

🔗 Computing 🔗 Computing/Computer hardware

Bubble memory is a type of non-volatile computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as bubbles or domains, each storing one bit of data. The material is arranged to form a series of parallel tracks that the bubbles can move along under the action of an external magnetic field. The bubbles are read by moving them to the edge of the material, where they can be read by a conventional magnetic pickup, and then rewritten on the far edge to keep the memory cycling through the material. In operation, bubble memories are similar to delay-line memory systems.

Bubble memory started out as a promising technology in the 1970s, offering performance similar to core memory, memory density similar to hard drives, and no moving parts. This led many to consider it a contender for a "universal memory" that could be used for all storage needs. The introduction of dramatically faster semiconductor memory chips in the early 1970s pushed bubble into the slow end of the scale and it began to be considered mostly as a replacement for disks. The equally dramatic improvements in hard-drive capacity through the early 1980s made it uncompetitive in price terms for mass storage.

Bubble memory was used for some time in the 1970s and 1980s in applications where its non-moving nature was desirable for maintenance or shock-proofing reasons. The introduction of flash storage and similar technologies rendered even this niche uncompetitive, and bubble disappeared entirely by the late 1980s.

🔗 Physics 🔗 Weather 🔗 Weather/Weather 🔗 Weather/General meteorology

A Fata Morgana (Italian: [ˈfaːta morˈɡaːna]) is a complex form of superior mirage visible in a narrow band right above the horizon. The term Fata Morgana is the Italian translation of "Morgan the Fairy" (Morgan le Fay of Arthurian legend). These mirages are often seen in the Italian Strait of Messina, and were described as fairy castles in the air or false land conjured by her magic.

Fata Morgana mirages significantly distort the object or objects on which they are based, often such that the object is completely unrecognizable. A Fata Morgana may be seen on land or at sea, in polar regions, or in deserts. It may involve almost any kind of distant object, including boats, islands, and the coastline. Often, a Fata Morgana changes rapidly. The mirage comprises several inverted (upside down) and upright images stacked on top of one another. Fata Morgana mirages also show alternating compressed and stretched zones.

The optical phenomenon occurs because rays of light bend when they pass through air layers of different temperatures in a steep thermal inversion where an atmospheric duct has formed. In calm weather, a layer of significantly warmer air may rest over colder dense air, forming an atmospheric duct that acts like a refracting lens, producing a series of both inverted and erect images. A Fata Morgana requires a duct to be present; thermal inversion alone is not enough to produce this kind of mirage. While a thermal inversion often takes place without there being an atmospheric duct, an atmospheric duct cannot exist without there first being a thermal inversion.

🔗 Archaeology 🔗 Wiltshire

The Stonehenge Archer is the name given to a Bronze Age man whose body was discovered in the outer ditch of Stonehenge. Unlike most burials in the Stonehenge Landscape, his body was not in a barrow, although it did appear to have been deliberately and carefully buried in the ditch.

Examination of the skeleton indicated that the man was local to the area and aged about 30 when he died. Radiocarbon dating suggests that he died around 2300 BCE, making his death roughly contemporary with the Amesbury Archer and the Boscombe Bowmen buried 3 miles away in Amesbury.

He came to be known as an archer because of the stone wrist-guard and a number of flint arrowheads buried with him. In fact, several of the arrowheads' tips were located in the skeleton's bones, suggesting that the man had been killed by them.

His body was excavated in 1978 by Richard Atkinson and John G. Evans who had been re-examining an older trench in the ditch and bank of Stonehenge. His remains are now housed in the Salisbury Museum in Salisbury.

🔗 Novels 🔗 Novels/Science fiction 🔗 Science Fiction 🔗 Transhumanism

Neuromancer is a 1984 science fiction novel by American-Canadian writer William Gibson. Considered one of the earliest and best-known works in the cyberpunk genre, it is the only novel to win the Nebula Award, the Philip K. Dick Award, and the Hugo Award. It was Gibson's debut novel and the beginning of the Sprawl trilogy. Set in the future, the novel follows Henry Case, a washed-up hacker hired for one last job, which brings him in contact with a powerful artificial intelligence.

🔗 Environment 🔗 Energy

Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power.

Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar, wind) and other renewables, or excess electricity from continuous base-load sources (such as coal or nuclear) to be saved for periods of higher demand. The reservoirs used with pumped storage can be quite small when contrasted with the lakes of conventional hydroelectric plants of similar power capacity, and generating periods are often less than half a day.

The round-trip efficiency of PSH generally varies between 70%–80%. Although the losses of the pumping process make the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. If the upper lake collects significant rainfall or is fed by a river then the plant may be a net energy producer in the manner of a traditional hydroelectric plant.

Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2020, PSH accounts for around 95% of all active storage installations worldwide, with a total installed throughput capacity of over 181 GW and a total installed storage capacity of over 1.6 TWh.

The main requirement for PSH is hilly country. The global greenfield pumped hydro atlas lists more than 600,000 potential sites around the world, which is about 100 times more than needed to support 100% renewable electricity. Most are closed-loop systems away from rivers. Areas of natural beauty and new dams on rivers can be avoided because of the very large number of potential sites. Some projects utilise existing reservoirs (dubbed "bluefield") such as the 350 Gigawatt-hour Snowy 2.0 scheme under construction in Australia. Some recently proposed projects propose to take advantage of "brownfield" locations such as disused mines such as the Kidston project under construction in Australia.

Water requirements for PSH are small: about 1 gigalitre of initial fill water per gigawatt-hour of storage. This water is recycled uphill and back downhill between the two reservoirs for many decades, but evaporation losses (beyond what rainfall and any inflow from local waterways provide) must be replaced. Land requirements are also small: about 10 hectares per gigawatt-hour of storage, which is much smaller than the land occupied by the solar and windfarms that the storage might support. Closed loop (off-river) pumped hydro storage has the smallest carbon emissions per unit of storage of all candidates for large-scale energy storage.