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🔗 Graphic design

A visiting card, also known as a calling card, is a small card used for social purposes. Before the 18th century, visitors making social calls left handwritten notes at the home of friends who were not at home. By the 1760s, the upper classes in France and Italy were leaving printed visiting cards decorated with images on one side and a blank space for hand-writing a note on the other. The style quickly spread across Europe and to the United States. As printing technology improved, elaborate color designs became increasingly popular. However, by the late 1800s, simpler styles became more common.

By the 19th century, men and women needed personalized calling or visiting cards to maintain their social status or to move up in society. These small cards, about the size of a modern-day business card, usually featured the name of the owner, and sometimes an address. Calling cards were left at homes, sent to individuals, or exchanged in person for various social purposes. Knowing and following calling card “rules” signaled one’s status and intentions.

🔗 New Zealand 🔗 India 🔗 India/Tamil Nadu 🔗 Dravidian civilizations 🔗 New Zealand/Māori 🔗 Tamil civilization

The Tamil Bell is a broken bronze bell discovered in approximately 1836 by missionary William Colenso. It was being used as a pot to boil potatoes by Māori women near Whangarei in the Northland Region of New Zealand.

The bell is 13 cm long and 9 cm deep, and has an inscription. The inscription running around the rim of the bell has been identified as old Tamil. Translated, it says "Mohoyiden Buks ship’s bell". Some of the characters in the inscription are of an archaic form no longer seen in modern Tamil script, thus suggesting that the bell could be about 500 years old, possibly from the Later Pandya period. It is thus what is sometimes called an out-of-place artefact.

Indologist V. R. Ramachandra Dikshitar states in his The Origin and Spread of the Tamils that ancient Tamil sea-farers might have had a knowledge of Australia and Polynesia. The discovery of the bell has led to speculation about a possible Tamil presence in New Zealand, but the bell is not in itself proof of early Tamil contact with New Zealand'. Seafarers from Trincomalee may have reached New Zealand during the period of increased trade between the Vanni country and South East Asia. The bell might have been dropped off the shore by a Portuguese ship, whose sailors had been in touch with the Indians. Also, a number of Indian vessels had been captured by the Europeans during the period; thus, another possibility is that the bell might have belonged to such a wrecked vessel, cast away on the New Zealand shores.

The bell was bequeathed by William Colenso to the Dominion Museum – now the Museum of New Zealand Te Papa Tongarewa.

🔗 Russia 🔗 Russia/mass media in Russia 🔗 Crime 🔗 Death 🔗 Lists 🔗 Freedom of speech 🔗 Journalism 🔗 Russia/politics and law of Russia

The dangers to journalists in Russia have been well known since the early 1990s but concern over the number of unsolved killings soared after Anna Politkovskaya's murder in Moscow on 7 October 2006. While international monitors mentioned a dozen deaths, some sources within Russia talked of over two hundred fatalities. The evidence has since been examined and documented in two reports, published in Russian and English, by international organizations. These revealed a basic confusion in terminology that explained the seemingly enormous numerical discrepancy: statistics of premature death among journalists (from work accidents, crossfire incidents, and purely criminal or domestic cases of manslaughter) were repeatedly equated with the much smaller number of targeted (contract) killings or work-related murders. The Remembrance Day of Journalists Killed in the Line of Duty in Russia is observed on 15 December every year.

🔗 Electronics

An antifuse is an electrical device that performs the opposite function to a fuse. Whereas a fuse starts with a low resistance and is designed to permanently break an electrically conductive path (typically when the current through the path exceeds a specified limit), an antifuse starts with a high resistance, and programming it converts it into a permanent electrically conductive path (typically when the voltage across the antifuse exceeds a certain level). This technology has many applications.

🔗 Internet 🔗 Computing 🔗 Computing/Software 🔗 Websites 🔗 Websites/Computing 🔗 Computing/Computer Security 🔗 Computing/Websites

Evercookie is a JavaScript-based application created by Samy Kamkar that produces zombie cookies in a web browser that are intentionally difficult to delete. In 2013, a top-secret NSA document was leaked by Edward Snowden, citing Evercookie as a method of tracking Tor users.

🔗 Switzerland

🔗 Chemistry

Aqua regia (; from Latin, lit. "regal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals, gold and platinum, though not all metals.

🔗 Mathematics

In linear algebra, the singular value decomposition (SVD) is a factorization of a real or complex matrix that generalizes the eigendecomposition of a square normal matrix to any ${\displaystyle m\times n}$ matrix via an extension of the polar decomposition.

Specifically, the singular value decomposition of an ${\displaystyle m\times n}$ real or complex matrix ${\displaystyle \mathbf {M} }$ is a factorization of the form ${\displaystyle \mathbf {U\Sigma V^{*}} }$, where ${\displaystyle \mathbf {U} }$ is an ${\displaystyle m\times m}$ real or complex unitary matrix, ${\displaystyle \mathbf {\Sigma } }$ is an ${\displaystyle m\times n}$ rectangular diagonal matrix with non-negative real numbers on the diagonal, and ${\displaystyle \mathbf {V} }$ is an ${\displaystyle n\times n}$ real or complex unitary matrix. If ${\displaystyle \mathbf {M} }$ is real, ${\displaystyle \mathbf {U} }$ and ${\displaystyle \mathbf {V} =\mathbf {V^{*}} }$ are real orthonormal matrices.

The diagonal entries ${\displaystyle \sigma _{i}=\Sigma _{ii}}$ of ${\displaystyle \mathbf {\Sigma } }$ are known as the singular values of ${\displaystyle \mathbf {M} }$. The number of non-zero singular values is equal to the rank of ${\displaystyle \mathbf {M} }$. The columns of ${\displaystyle \mathbf {U} }$ and the columns of ${\displaystyle \mathbf {V} }$ are called the left-singular vectors and right-singular vectors of ${\displaystyle \mathbf {M} }$, respectively.

The SVD is not unique. It is always possible to choose the decomposition so that the singular values ${\displaystyle \Sigma _{ii}}$are in descending order. In this case, Σ (but not always U and V) is uniquely determined by M.

The term sometimes refers to the compact SVD, a similar decomposition ${\displaystyle \mathbf {M} =\mathbf {U\Sigma V^{*}} }$ in which Σ is square diagonal of size ${\displaystyle r\times r}$, where ${\displaystyle r\leq \min\{m,n\}}$ is the rank of M, and has only the non-zero singular values. In this variant, ${\displaystyle \mathbf {U} }$ is an ${\displaystyle m\times r}$ matrix and ${\displaystyle \mathbf {V} }$ is an ${\displaystyle n\times r}$ matrix, such that ${\displaystyle \mathbf {U^{*}U} =\mathbf {V^{*}V} =\mathbf {I} _{r\times r}}$.

Mathematical applications of the SVD include computing the pseudoinverse, matrix approximation, and determining the rank, range, and null space of a matrix. The SVD is also extremely useful in all areas of science, engineering, and statistics, such as signal processing, least squares fitting of data, and process control.

🔗 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.

🔗 United States 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Military history/Military science, technology, and theory 🔗 Physics 🔗 Women's History 🔗 History of Science 🔗 Tennessee 🔗 Military history/World War II 🔗 Physics/History 🔗 Science

The Calutron Girls were a group of young women, mostly high school graduates who joined the World War II efforts in Oak Ridge, Tennessee in 1945.

Although they were not allowed to know at the time, they were monitoring dials and watching meters for a calutron, a mass spectrometer that separates uranium isotopes. The enriched uranium was used to make the first atomic bomb.

Calutron Girls were trained and employed at the Y-12 National Security Complex. Wartime labor shortages forced the Tennessee Eastman Corporation to hire women to work at the Y-12 plant.

According to Gladys Owens, one of the few Calutron Girls, a manager at the facility once told them: "We can train you how to do what is needed, but cannot tell you what you are doing. I can only tell you that if our enemies beat us to it, God have mercy on us!"