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🔗 Technology 🔗 Computing 🔗 Mathematics

A slide rule is a hand-operated mechanical calculator consisting of slidable rulers for evaluating mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry. It is one of the simplest analog computers.

Slide rules exist in a diverse range of styles and generally appear in a linear, circular or cylindrical form. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in specialized calculations particular to those fields. The slide rule is closely related to nomograms used for application-specific computations. Though similar in name and appearance to a standard ruler, the slide rule is not meant to be used for measuring length or drawing straight lines. Nor is it designed for addition or subtraction, which is usually performed using other methods, like using an abacus. Maximum accuracy for standard linear slide rules is about three decimal significant digits, while scientific notation is used to keep track of the order of magnitude of results.

English mathematician and clergyman Reverend William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. It made calculations faster and less error-prone than evaluating on paper. Before the advent of the scientific pocket calculator, it was the most commonly used calculation tool in science and engineering. The slide rule's ease of use, ready availability, and low cost caused its use to continue to grow through the 1950s and 1960s, even as desktop electronic computers were gradually introduced. But after the handheld scientific calculator was introduced in 1972 and became inexpensive in the mid-1970s, slide rules became largely obsolete, so most suppliers departed the business.

In the United States, the slide rule is colloquially called a slipstick.

🔗 Computing 🔗 Computing/Computer hardware

The Dadda multiplier is a hardware binary multiplier design invented by computer scientist Luigi Dadda in 1965. It uses a selection of full and half adders to sum the partial products in stages (the Dadda tree or Dadda reduction) until two numbers are left. The design is similar to the Wallace multiplier, but the different reduction tree reduces the required number of gates (for all but the smallest operand sizes) and makes it slightly faster (for all operand sizes).

Dadda and Wallace multipliers have the same three steps for two bit strings ${\displaystyle w_{1}}$ and ${\displaystyle w_{2}}$ of lengths ${\displaystyle \ell _{1}}$ and ${\displaystyle \ell _{2}}$ respectively:

1. Multiply (logical AND) each bit of ${\displaystyle w_{1}}$, by each bit of ${\displaystyle w_{2}}$, yielding ${\displaystyle \ell _{1}\cdot \ell _{2}}$ results, grouped by weight in columns
2. Reduce the number of partial products by stages of full and half adders until we are left with at most two bits of each weight.
3. Add the final result with a conventional adder.

As with the Wallace multiplier, the multiplication products of the first step carry different weights reflecting the magnitude of the original bit values in the multiplication. For example, the product of bits ${\displaystyle a_{n}b_{m}}$ has weight ${\displaystyle n+m}$.

Unlike Wallace multipliers that reduce as much as possible on each layer, Dadda multipliers attempt to minimize the number of gates used, as well as input/output delay. Because of this, Dadda multipliers have a less expensive reduction phase, but the final numbers may be a few bits longer, thus requiring slightly bigger adders.

🔗 Computing 🔗 Computer graphics

The Stanford bunny is a computer graphics 3D test model developed by Greg Turk and Marc Levoy in 1994 at Stanford University. The model consists of 69,451 triangles, with the data determined by 3D scanning a ceramic figurine of a rabbit. This figurine and others were scanned to test methods of range scanning physical objects.

The data can be used to test various graphics algorithms, including polygonal simplification, compression, and surface smoothing. There are a few complications with this dataset that can occur in any 3D scan data: the model is manifold connected and has holes in the data, some due to scanning limits and some due to the object being hollow. These complications provide a more realistic input for any algorithm that is benchmarked with the Stanford bunny, though by today's standards, in terms of geometric complexity and triangle count, it is considered a simple model.

The model was originally available in .ply (polygons) file format with 4 different resolutions.

🔗 Italy 🔗 Food and drink

Radiatori are small, squat pasta shapes that are said to resemble radiators. Although it is rumored that they were created in the 1960s by an industrial designer, their invention was actually between the First and Second World War. They are often used in similar dishes as rotelle or fusilli, because their shape works well with thicker sauces. They are also used in casseroles, salads, and soups. The form is sometimes called pagoda pasta..

🔗 Canada 🔗 Packaging

A milk bag is a plastic bag that contains milk. Usually one of the corners is cut off to allow for pouring, and the bag is stored in a pitcher or jug.

A typical milk bag contains approximately 1 L (1.8 imp pt) of milk in South America, Iran, Israel, and continental European countries, while in Canada they contain 1+1⁄3 litres (2.3 imp pt), and in India, 0.5 L (0.9 imp pt).

In the Baltic rim countries, e.g., Estonia, and some Eastern European countries, the similar bags may also be seen used for packaging yogurt or kefir.

🔗 Serbia 🔗 Yugoslavia 🔗 Military history 🔗 Military history/Balkan military history 🔗 Croatia 🔗 Military history/European military history 🔗 Military history/Post-Cold War 🔗 Project-independent assessment

The Battle of Vukovar was an 87-day siege of Vukovar in eastern Croatia by the Yugoslav People's Army (JNA), supported by various paramilitary forces from Serbia, between August and November 1991. Before the Croatian War of Independence the Baroque town was a prosperous, mixed community of Croats, Serbs and other ethnic groups. As Yugoslavia began to break up, Serbia's President Slobodan Milošević and Croatia's President Franjo Tuđman began pursuing nationalist politics. In 1990, an armed insurrection was started by Croatian Serb militias, supported by the Serbian government and paramilitary groups, who seized control of Serb-populated areas of Croatia. The JNA began to intervene in favour of the rebellion, and conflict broke out in the eastern Croatian region of Slavonia in May 1991. In August, the JNA launched a full-scale attack against Croatian-held territory in eastern Slavonia, including Vukovar.

Vukovar was defended by around 1,800 lightly armed soldiers of the Croatian National Guard (ZNG) and civilian volunteers, against as many as 36,000 JNA soldiers and Serb paramilitaries equipped with heavy armour and artillery. During the battle, shells and rockets were fired into the town at a rate of up to 12,000 a day. At the time, it was the fiercest and most protracted battle seen in Europe since 1945, and Vukovar was the first major European town to be entirely destroyed since the Second World War. When Vukovar fell on 18 November 1991, several hundred soldiers and civilians were massacred by Serb forces and at least 20,000 inhabitants were expelled. Overall, around 3,000 people died during the battle. Most of Vukovar was ethnically cleansed of its non-Serb population and became part of the self-declared proto-state known as the Republic of Serbian Krajina. Several Serb military and political officials, including Milošević, were later indicted and in some cases jailed for war crimes committed during and after the battle.

The battle exhausted the JNA and proved a turning point in the Croatian War of Independence. A cease-fire was declared a few weeks later. Vukovar remained in Serb hands until 1998, when it was peacefully reintegrated into Croatia with the signing of the Erdut Agreement. It has since been rebuilt but has less than half of its pre-war population and many buildings are still scarred by the battle. Its two principal ethnic communities remain deeply divided and it has not regained its former prosperity.

🔗 Environment 🔗 Energy

Dry cask storage is a method of storing high-level radioactive waste, such as spent nuclear fuel that has already been cooled in a spent fuel pool for at least one year and often as much as ten years. Casks are typically steel cylinders that are either welded or bolted closed. The fuel rods inside are surrounded by inert gas. Ideally, the steel cylinder provides leak-tight containment of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public.

There are various dry storage cask system designs. With some designs, the steel cylinders containing the fuel are placed vertically in a concrete vault; other designs orient the cylinders horizontally. The concrete vaults provide the radiation shielding. Other cask designs orient the steel cylinder vertically on a concrete pad at a dry cask storage site and use both metal and concrete outer cylinders for radiation shielding. Until 2024/25, there was no long term permanent storage facility anywhere in the world, and most countries still don't have a facility; dry cask storage is designed as an interim safer solution than spent fuel pool storage.

Some of the cask designs can be used for both storage and transportation. Three companies – Holtec International, NAC International and Areva-Transnuclear NUHOMS – are marketing Independent Spent Fuel Storage Installations (ISFSI) based upon an unshielded multi-purpose canister which is transported and stored in on-site vertical or horizontal shielded storage modules constructed of steel and concrete.

🔗 Korea 🔗 Food and drink 🔗 Korea/one or more inactive working groups

A kimchi refrigerator is a refrigerator designed specifically to meet the storage requirements of kimchi and facilitate different fermentation processes. The kimchi refrigerator aims to be colder, with more consistent temperature, more humidity, and less moving air than a conventional refrigerator, providing the ideal environment for fermentation of kimchi. Some models may include features such as a UV Sterilizer.

In a consumer survey aimed at South Korean homemakers conducted by a top-ranking Korean media agency in 2004, the kimchi refrigerator was ranked first for most wanted household appliance.

🔗 Poetry 🔗 Bible

An acrostic is a poem (or other form of writing) in which the first letter (or syllable, or word) of each line (or paragraph, or other recurring feature in the text) spells out a word, message or the alphabet. The word comes from the French acrostiche from post-classical Latin acrostichis, from Koine Greek ἀκροστιχίς, from Ancient Greek ἄκρος "highest, topmost" and στίχος "verse". As a form of constrained writing, an acrostic can be used as a mnemonic device to aid memory retrieval.

Relatively simple acrostics may merely spell out the letters of the alphabet in order; such an acrostic may be called an 'alphabetical acrostic' or abecedarius. These acrostics occur in the first four of the five chapters that make up the Book of Lamentations, in the praise of the good wife in Proverbs 31:10-31, and in Psalms 25, 34, 37, 111, 112, 119 and 145 of the Hebrew Bible. Notable among the acrostic Psalms is the long Psalm 119, which typically is printed in subsections named after the 22 letters of the Hebrew alphabet, each section consisting of 8 verses, each of which begins with the same letter of the alphabet and the entire psalm consisting of 22 x 8 = 176 verses; and Psalm 145, which is recited three times a day in the Jewish services. Some acrostic psalms are technically imperfect. E.g. Psalm 9 and Psalm 10 appear to constitute a single acrostic psalm together, but the length assigned to each letter is unequal and five of the 22 letters of the Hebrew alphabet are not represented and the sequence of two letters is reversed. In Psalm 25 one Hebrew letter is not represented, the following letter (Resh) repeated. In Psalm 34 the current final verse, 23, does fit verse 22 in content, but adds an additional line to the poem. In Psalms 37 and 111 the numbering of verses and the division into lines are interfering with each other; as a result in Psalm 37, for the letters Daleth and Kaph there is only one verse, and the letter Ayin is not represented. Psalm 111 and 112 have 22 lines, but 10 verses. Psalm 145 does not represent the letter Nun, having 21 one verses, but one Qumran manuscript of this Psalm does have that missing line, which agrees with the Septuagint.

Acrostics are common in medieval literature, where they usually serve to highlight the name of the poet or his patron, or to make a prayer to a saint. They are most frequent in verse works but can also appear in prose. The Middle High German poet Rudolf von Ems for example opens all his great works with an acrostic of his name, and his world chronicle marks the beginning of each age with an acrostic of the key figure (Moses, David, etc.). In chronicles, acrostics are common in German and English but rare in other languages.

Often the ease of detectability of an acrostic can depend on the intention of its creator. In some cases an author may desire an acrostic to have a better chance of being perceived by an observant reader, such as the acrostic contained in the Hypnerotomachia Poliphili (where the key capital letters are decorated with ornate embellishments). However, acrostics may also be used as a form of steganography, where the author seeks to conceal the message rather than proclaim it. This might be achieved by making the key letters uniform in appearance with the surrounding text, or by aligning the words in such a way that the relationship between the key letters is less obvious. This is referred to as null ciphers in steganography, using the first letter of each word to form a hidden message in an otherwise innocuous text. Using letters to hide a message, as in acrostic ciphers, was popular during the Renaissance, and could employ various methods of enciphering, such as selecting other letters than initials based on a repeating pattern (equidistant letter sequences), or even concealing the message by starting at the end of the text and working backwards.