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🔗 Computer science 🔗 Time

In computer science, time formatting and storage bugs are a class of software bugs which may cause time and date calculation or display to be improperly handled. These are most commonly manifestations of arithmetic overflow, but can also be the result of other issues. The most well-known consequence of bugs of this type is the Y2K problem, but many other milestone dates or times exist that have caused or will cause problems depending on various programming deficiencies.

🔗 Mathematics

The Erdős number (Hungarian: [ˈɛrdøːʃ]) describes the "collaborative distance" between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers. The same principle has been applied in other fields where a particular individual has collaborated with a large and broad number of peers.

🔗 Environment 🔗 Automobiles 🔗 Environment/Green vehicle

The Flocken Elektrowagen is a four-wheeled electric car designed by Andreas Flocken (1845–1913), manufactured in 1888 by Maschinenfabrik A. Flocken in Coburg. It is regarded as the first real electric car.

🔗 Russia 🔗 Norway 🔗 Holidays 🔗 Sweden 🔗 Ethnic groups 🔗 Finland 🔗 Norse history and culture

The Sámi National Day is an ethnic national day for the Sámi (Saami) people that falls on February 6, the date when the first Sámi congress was held in 1917 in Trondheim, Norway. The congress was the first time that Norwegian and Swedish Sámi came together across national borders to work on finding solutions to common problems.

In 1992 at the 15th Sámi Conference in Helsinki, Finland, a resolution was passed that Sámi National Day should be celebrated on February 6 to commemorate the first Sámi congress in 1917, that Sami National Day is for all Sámi, regardless of where they live, and on that day the Sámi flag should be flown and the Sámi anthem sung in the local Sámi language. The first time Sami National Day was celebrated was in 1993, when the International Year of Indigenous People was proclaimed open in Jokkmokk, Sweden by the United Nations.

Since then, celebrating the day has become increasingly popular. In Norway, it is compulsory for municipal administrative buildings to fly the Norwegian flag, and optionally also the Sami flag, on February 6. Particularly notable is the celebration in Norway's capital Oslo, where the bells in the highest tower of Oslo City Hall play the Sami national anthem as the flags are raised. Some larger places have taken to arranging festivities in the week around the Sami National Day. The National Day has been included in the almanacs published by the University of Helsinki since 2004. The Norwegian, Swedish, and Finnish authorities recommend general flagging on the day.

By coincidence, February 6 was also the date representatives of the Sámi of the Kola Peninsula gathered annually to meet with Russian bureaucrats to debate and decide on issues of relevance to them. This assembly, called the Kola Sobbar, has been dubbed the "first Sámi Parliament" by the researcher Johan Albert Kalstad. However, the founding of the Kola Sobbar did not influence the choice of the date for Sámi People's Day, as the assembly existed only during the late 1800s and was largely forgotten until the early 2000s.

🔗 Australia 🔗 Insects 🔗 Australia/Australian biota

Pantala flavescens, the globe skimmer, globe wanderer or wandering glider, is a wide-ranging dragonfly of the family Libellulidae. This species and Pantala hymenaea, the "spot-winged glider", are the only members of the genus Pantala. It was first described by Johan Christian Fabricius in 1798. It is considered to be the most widespread dragonfly on the planet with good population on every continent except Antarctica although rare in Europe. Globe skimmers make an annual multigenerational journey of some 18,000 km (about 11,200 miles); to complete the migration, individual globe skimmers fly more than 6,000 km (3,730 miles)—one of the farthest known migrations of all insect species.

🔗 Biography

Anthony Peter "Tony" Buzan (; 2 June 1942 – 13 April 2019) was an English author and educational consultant.

Buzan popularised the idea of mental literacy, radiant thinking, and a technique called mind mapping, inspired by techniques used by Leonardo da Vinci, Albert Einstein, and Joseph D. Novak's "concept mapping" techniques.

🔗 Religion 🔗 Iran 🔗 Central Asia 🔗 Syria 🔗 Iraq 🔗 Turkey 🔗 Ukraine 🔗 Holidays 🔗 Pakistan 🔗 Afghanistan 🔗 Caucasia 🔗 Kurdistan 🔗 Tajikistan 🔗 Georgia (country) 🔗 Azerbaijan 🔗 North Macedonia 🔗 Bahá'í Faith 🔗 Albania

Nowruz (Persian: نوروز‎, pronounced [nowˈɾuːz]; lit.  "new day") is the Iranian New Year, also known as the Persian New Year, which is celebrated worldwide by various ethno-linguistic groups.

Nowruz has Iranian and Zoroastrian origins, however, it has been celebrated by diverse communities for over 7,000 years in Western Asia, Central Asia, the Caucasus, the Black Sea Basin, the Balkans, and South Asia. It is a secular holiday for most celebrants that is enjoyed by people of several different faiths, but remains a holy day for Zoroastrians, Bahais, and some Muslim communities.

Nowruz is the day of the vernal equinox, and marks the beginning of spring in the Northern Hemisphere. It marks the first day of the first month (Farvardin) of the Iranian calendars. It usually occurs on March 21 or the previous or following day, depending on where it is observed. The moment the Sun crosses the celestial equator and equalizes night and day is calculated exactly every year, and families gather together to observe the rituals.

While Nowruz has been celebrated since the reform of the Iranian Calendar in the 11th century CE to mark the new year, the United Nations officially recognized the "International Day of Nowruz" with the adoption of UN resolution 64/253 in 2010.

🔗 Chemistry

The vanadium redox battery (VRB), also known as the vanadium flow battery (VFB) or vanadium redox flow battery (VRFB), is a type of rechargeable flow battery that employs vanadium ions in different oxidation states to store chemical potential energy. The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. For several reasons, including their relative bulkiness, most vanadium batteries are currently used for grid energy storage, i.e., attached to power plants or electrical grids.

The possibility of creating a vanadium flow battery was explored by Pissoort in the 1930s, NASA researchers in the 1970s, and Pellegri and Spaziante in the 1970s, but none of them were successful in demonstrating the technology. The first successful demonstration of the all-vanadium redox flow battery which employed vanadium in a solution of sulfuric acid in each half was by Maria Skyllas-Kazacos at the University of New South Wales in the 1980s. Her design used sulfuric acid electrolytes, and was patented by the University of New South Wales in Australia in 1986.

The main advantages of the vanadium redox battery are that it can offer almost unlimited energy capacity simply by using larger electrolyte storage tanks; it can be left completely discharged for long periods with no ill effects; if the electrolytes are accidentally mixed, the battery suffers no permanent damage; a single state of charge between the two electrolytes avoids the capacity degradation due to a single cell in non-flow batteries; the electrolyte is aqueous and inherently safe and non-flammable; and the generation 3 formulation using a mixed acid solution developed by the Pacific Northwest National Laboratory operates over a wider temperature range allowing for passive cooling. VRFBs can be used at depth of discharge (DOD) around 90% and more, i.e. deeper DODs than solid-state batteries (e.g. lithium-based and sodium-based batteries, which are usually specified with DOD=80%). In addition, VRFBs exhibit very long cycle lives: most producers specify cycle durability in excess of 15,000-20,000 charge/discharge cycles. These values are far beyond the cycle lives of solid-state batteries, which is usually in the order of 4,000-5,000 charge/discharge cycles. Consequently, the levelized cost of energy (LCOE, i.e. the system cost divided by the usable energy, the cycle life, and round-trip efficiency) of present VRFB systems is typically in the order of a few tens of $ cents or € cents, namely much lower than the LCOEs of equivalent solid-state batteries and close to the targets of $0.05 and €0.05, stated by the US Department of Energy and the European Commission Strategic Energy Technology (SET) Plan, respectively.

The main disadvantages with vanadium redox technology are a relatively poor energy-to-volume ratio in comparison with standard storage batteries, and the relatively poor round trip efficiency. Furthermore, the aqueous electrolyte makes the battery heavy and therefore only useful for stationary applications. Another disadvantage is the relatively high toxicity of oxides of vanadium (see vanadium § Safety).

Numerous companies and organizations involved in funding and developing vanadium redox batteries include Avalon Battery, Vionx (formerly Premium Power), UniEnergy Technologies and Ashlawn Energy in the United States; Renewable Energy Dynamics Technology in Ireland; Enerox GmbH (formerly Gildemeister energy storage) in Austria; Cellennium in Thailand; Rongke Power in China; Prudent Energy in China; Sumitomo in Japan; H2, Inc. in South Korea; redT in Britain., Australian Vanadium in Australia, and the now defunct Imergy (formerly Deeya). Lately, also several smaller size vanadium redox flow batteries were brought to market (for residential applications) mainly from StorEn Technologies (USA), Schmid Group, VoltStorage and Volterion (all three from Germany), VisBlue (Denmark) or Pinflow energy storage (Czechia).

🔗 Technology 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/Military science, technology, and theory 🔗 Architecture 🔗 United Kingdom 🔗 Transport 🔗 Military history/Maritime warfare 🔗 Military history/World War II 🔗 Civil engineering 🔗 Engineering 🔗 Transport/Maritime 🔗 Military history/Canadian military history 🔗 Military history/European military history 🔗 Military history/British military history

Pykrete is a frozen ice alloy , originally made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight (6 to 1 by weight). During World War II, Geoffrey Pyke proposed it as a candidate material for a supersized aircraft carrier for the British Royal Navy. Pykrete features unusual properties, including a relatively slow melting rate due to its low thermal conductivity, as well as a vastly improved strength and toughness compared to ordinary ice. These physical properties can make the material comparable to concrete, as long as the material is kept frozen.

Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process. However, it can be repaired and maintained using seawater as a raw material. The mixture can be moulded into any shape and frozen, and it will be tough and durable, as long as it is kept at or below freezing temperature. Resistance to gradual creep or sagging is improved by lowering the temperature further, to −15 °C (5 °F).

🔗 United States 🔗 International relations 🔗 Business 🔗 Politics 🔗 Trade 🔗 Taxation 🔗 Presidents of the United States 🔗 Presidents of the United States/Donald Trump

"Trump Always Chickens Out" (TACO) is a pejorative description of the perceived tendency of US president Donald Trump to make threats, only to later delay or renege on them as a way to increase time for negotiations and for markets to rebound. The phrase was popularized in May 2025 after the many threats and reversals during the trade war he initiated with his "Liberation Day" tariffs. On Wall Street, a TACO trade is buying stocks cheaply after a tariff announcement pushes stocks lower, then selling them at a profit after the tariffs are delayed or reduced and the market rebounds.

By 2026, TACO was also used for Trump's decisions in the realm of foreign policy, specifically his reversal of threats to annex Greenland, his attempt to find an abrupt exit for the escalating 2026 Iran War as global securities began to fall due to the rise in oil prices, and his last-minute ceasefire deal for the Iran War itself before the deadline for the American bombing campaign.