Have a deep view into what people are curious about.

🔗 Human rights 🔗 Korea 🔗 Correction and Detention Facilities 🔗 Korea/North Korea

Hwasong concentration camp (Chosŏn'gŭl: 화성 제16호 관리소, also spelled Hwasŏng or Hwaseong) is a labor camp in North Korea for political prisoners. The official name is Kwan-li-so (Penal-labor colony) No. 16.

🔗 Linguistics

Oi is an interjection used in various varieties of the English language, particularly Australian English, British English, Indian English, Irish English, New Zealand English, and South African English, as well as non-English languages such as Chinese, Tagalog, Tamil, Hindi/Urdu, Japanese, and Portuguese to get the attention of another person or to express surprise or disapproval. It is sometimes used in Canadian English and very rarely in American English. The word is also common in the Indian subcontinent, where it has varied pronunciations of "O-ee" and "O-ye".

"Oi" has been particularly associated with working class and Cockney speech. It is effectively a local pronunciation of "hoy" (see H-dropping), an older expression. A study of the Cockney dialect in the 1950s found that whether it was being used to call attention or as a challenge depended on its tone and abruptness. The study's author noted that the expression is "jaunty and self-assertive" as well as "intensely cockney".

A poll of non-English speakers by the British Council in 2004 found that "oi" was considered the 61st most beautiful word in the English language. A spokesman commented that "Oi is not a word that I would've thought turned up in English manuals all that often." "Oi" was added to the list of acceptable words in US Scrabble in 2006.

🔗 Aviation

Balloonomania was a strong public interest or fad in balloons that originated in France in the late 18th century and continued into the 19th century, during the advent of balloon flights. The interest began with the first flights of the Montgolfier brothers in 1783 (in a balloon inflated with hot air). Soon afterwards Jacques Alexandre César Charles flew another type of balloon (inflated with hydrogen) and both types of balloon were in use from then on. The fad quickly spread in France and across the channel in England.

🔗 Palaeontology

The cat gap is a period in the fossil record of approximately 25 to 18.5 million years ago in which there are few fossils of cats or cat-like species found in North America. The cause of the "cat gap" is disputed, but may have been caused by changes in the climate (global cooling), changes in the habitat and environmental ecosystem, the increasingly hypercarnivorous trend of the cats (especially the nimravids), volcanic activity, evolutionary changes in dental morphology of the Canidae species present in North America, or a periodicity of extinctions called van der Hammen cycles.

🔗 Computing 🔗 Computing/Computer hardware

PLATO (Programmed Logic for Automatic Teaching Operations) was the first generalized computer-assisted instruction system. Starting in 1960, it ran on the University of Illinois' ILLIAC I computer. By the late 1970s, it supported several thousand graphics terminals distributed worldwide, running on nearly a dozen different networked mainframe computers. Many modern concepts in multi-user computing were originally developed on PLATO, including forums, message boards, online testing, e-mail, chat rooms, picture languages, instant messaging, remote screen sharing, and multiplayer video games.

PLATO was designed and built by the University of Illinois and functioned for four decades, offering coursework (elementary through university) to UIUC students, local schools, and other universities. Courses were taught in a range of subjects, including Latin, chemistry, education, music, and primary mathematics. The system included a number of features useful for pedagogy, including text overlaying graphics, contextual assessment of free-text answers, depending on the inclusion of keywords, and feedback designed to respond to alternative answers.

Rights to market PLATO as a commercial product were licensed by Control Data Corporation (CDC), the manufacturer on whose mainframe computers the PLATO IV system was built. CDC President William Norris planned to make PLATO a force in the computer world, but found that marketing the system was not as easy as hoped. PLATO nevertheless built a strong following in certain markets, and the last production PLATO system did not shut down until 2006, coincidentally just a month after Norris died.

🔗 International relations 🔗 Disaster management 🔗 Medicine 🔗 Death

A pandemic (from Greek πᾶν pan "all" and δῆμος demos "people") is a disease epidemic that has spread across a large region, for instance multiple continents, or worldwide. A widespread endemic disease with a stable number of infected people is not a pandemic. Further, flu pandemics generally exclude recurrences of seasonal flu.

Throughout history, there have been a number of pandemics of diseases such as smallpox and tuberculosis. One of the most devastating pandemics was the Black Death (also known as The Plague), which killed an estimated 75–200 million people in the 14th century. Other notable pandemics include the 1918 influenza pandemic (Spanish flu) and the 2009 flu pandemic (H1N1). Current pandemics include HIV/AIDS and the 2019 coronavirus disease, which was declared a pandemic on 11 March 2020 by the World Health Organization (WHO).

🔗 United States 🔗 Mathematics 🔗 Education 🔗 United States/Massachusetts 🔗 Higher Education

Math 55 is a two-semester long first-year undergraduate mathematics course at Harvard University, founded by Lynn Loomis and Shlomo Sternberg. The official titles of the course are Honors Abstract Algebra (Math 55a) and Honors Real and Complex Analysis (Math 55b). Previously, the official title was Honors Advanced Calculus and Linear Algebra.

🔗 Computer science

Floyd–Steinberg dithering is an image dithering algorithm first published in 1976 by Robert W. Floyd and Louis Steinberg. It is commonly used by image manipulation software, for example when an image is converted into GIF format that is restricted to a maximum of 256 colors.

The algorithm achieves dithering using error diffusion, meaning it pushes (adds) the residual quantization error of a pixel onto its neighboring pixels, to be dealt with later. It spreads the debt out according to the distribution (shown as a map of the neighboring pixels):

${\displaystyle {\begin{bmatrix}&&*&{\frac {\displaystyle 7}{\displaystyle 16}}&\ldots \\\ldots &{\frac {\displaystyle 3}{\displaystyle 16}}&{\frac {\displaystyle 5}{\displaystyle 16}}&{\frac {\displaystyle 1}{\displaystyle 16}}&\ldots \\\end{bmatrix}}}$

The pixel indicated with a star (*) indicates the pixel currently being scanned, and the blank pixels are the previously-scanned pixels. The algorithm scans the image from left to right, top to bottom, quantizing pixel values one by one. Each time the quantization error is transferred to the neighboring pixels, while not affecting the pixels that already have been quantized. Hence, if a number of pixels have been rounded downwards, it becomes more likely that the next pixel is rounded upwards, such that on average, the quantization error is close to zero.

The diffusion coefficients have the property that if the original pixel values are exactly halfway in between the nearest available colors, the dithered result is a checkerboard pattern. For example, 50% grey data could be dithered as a black-and-white checkerboard pattern. For optimal dithering, the counting of quantization errors should be in sufficient accuracy to prevent rounding errors from affecting the result.

In some implementations, the horizontal direction of scan alternates between lines; this is called "serpentine scanning" or boustrophedon transform dithering.

In the following pseudocode we can see the algorithm described above. This works for any approximately linear encoding of pixel values, such as 8-bit integers, 16-bit integers or real numbers in the range [0,1].

for each y from top to bottom do
    for each x from left to right do
        oldpixel := pixel[x][y]
        newpixel := find_closest_palette_color(oldpixel)
        pixel[x][y] := newpixel
        quant_error := oldpixel - newpixel
        pixel[x + 1][y    ] := pixel[x + 1][y    ] + quant_error × 7 / 16
        pixel[x - 1][y + 1] := pixel[x - 1][y + 1] + quant_error × 3 / 16
        pixel[x    ][y + 1] := pixel[x    ][y + 1] + quant_error × 5 / 16
        pixel[x + 1][y + 1] := pixel[x + 1][y + 1] + quant_error × 1 / 16

When converting 16 bit greyscale to 8 bit, find_closest_palette_color() may perform just a simple rounding, for example:

find_closest_palette_color(oldpixel) = round(oldpixel / 256)

The pseudocode can result in pixel values exceeding the valid values (such as greater than 1 in a [0,1] representation). Such values should ideally be clipped by the find_closest_palette_color() function, rather than clipping the intermediate values, since a subsequent error may bring the value back into range. However, if fixed-width integers are used, wrapping of intermediate values would cause inversion of black and white, and so should be avoided.