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🔗 Electronics

In signal processing, the Nyquist frequency (or folding frequency), named after Harry Nyquist, is a characteristic of a sampler, which converts a continuous function or signal into a discrete sequence. For a given sampling rate (samples per second), the Nyquist frequency (cycles per second) is the frequency whose cycle-length (or period) is twice the interval between samples, thus 0.5 cycle/sample. For example, audio CDs have a sampling rate of 44100 samples/second. At 0.5 cycle/sample, the corresponding Nyquist frequency is 22050 cycles/second (Hz). Conversely, the Nyquist rate for sampling a 22050 Hz signal is 44100 samples/second.

When the highest frequency (bandwidth) of a signal is less than the Nyquist frequency of the sampler, the resulting discrete-time sequence is said to be free of the distortion known as aliasing, and the corresponding sample rate is said to be above the Nyquist rate for that particular signal.

In a typical application of sampling, one first chooses the highest frequency to be preserved and recreated, based on the expected content (voice, music, etc.) and desired fidelity. Then one inserts an anti-aliasing filter ahead of the sampler. Its job is to attenuate the frequencies above that limit. Finally, based on the characteristics of the filter, one chooses a sample rate (and corresponding Nyquist frequency) that will provide an acceptably small amount of aliasing. In applications where the sample rate is pre-determined (such as the CD rate), the filter is chosen based on the Nyquist frequency, rather than vice versa.

🔗 Physics 🔗 Astronomy

Rømer's determination of the speed of light was the demonstration in 1676 that light has a finite speed and so does not travel instantaneously. The discovery is usually attributed to Danish astronomer Ole Rømer, who was working at the Royal Observatory in Paris at the time.

By timing the eclipses of the Jovian moon Io, Rømer estimated that light would take about 22 minutes to travel a distance equal to the diameter of Earth's orbit around the Sun. This would give light a velocity of about 220,000 kilometres per second, about 26% lower than the true value of 299,792 km/s.

Rømer's theory was controversial at the time that he announced it and he never convinced the director of the Paris Observatory, Giovanni Domenico Cassini, to fully accept it. However, it quickly gained support among other natural philosophers of the period such as Christiaan Huygens and Isaac Newton. It was finally confirmed nearly two decades after Rømer's death, with the explanation in 1729 of stellar aberration by the English astronomer James Bradley.

🔗 Computing 🔗 Computing/Software 🔗 Microsoft

MSX-DOS is a discontinued disk operating system developed by Microsoft for the 8-bit home computer standard MSX, and is a cross between MS-DOS v1.25 and CP/M-80 v2.2.

🔗 Human rights 🔗 Soviet Union 🔗 Crime 🔗 Death 🔗 Philosophy 🔗 Discrimination 🔗 Philosophy/Ethics 🔗 Soviet Union/history of Russia 🔗 Soviet Union/Russia 🔗 Ukraine 🔗 Ethnic groups

The Holodomor (Ukrainian: Голодомо́р; Голодомо́р в Украї́ні; derived from морити голодом, "to kill by starvation") was a man-made famine in Soviet Ukraine in 1932 and 1933 that killed millions of Ukrainians. It is also known as the Terror-Famine and Famine-Genocide in Ukraine, and sometimes referred to as the Great Famine or the Ukrainian Genocide of 1932–33. It was part of the wider Soviet famine of 1932–33, which affected the major grain-producing areas of the country. During the Holodomor, millions of inhabitants of Ukraine, the majority of whom were ethnic Ukrainians, died of starvation in a peacetime catastrophe unprecedented in the history of Ukraine. Since 2006, the Holodomor has been recognized by Ukraine and 15 other countries as a genocide of the Ukrainian people carried out by the Soviet government.

Early estimates of the death toll by scholars and government officials varied greatly. According to higher estimates, up to 12 million ethnic Ukrainians were said to have perished as a result of the famine. A U.N. joint statement signed by 25 countries in 2003 declared that 7–10 million perished. Research has since narrowed the estimates to between 3.3 and 7.5 million. According to the findings of the Court of Appeal of Kiev in 2010, the demographic losses due to the famine amounted to 10 million, with 3.9 million direct famine deaths, and a further 6.1 million birth deficits.

The term Holodomor emphasises the famine's man-made and intentional aspects, such as rejection of outside aid, confiscation of all household foodstuffs, and restriction of population movement. Whether the Holodomor was genocide is still the subject of academic debate, as are the causes of the famine and intentionality of the deaths. Some scholars believe that the famine was planned by Joseph Stalin to eliminate a Ukrainian independence movement. The loss of life has been compared to that of the Holocaust. However, some historians dispute its characterization as a genocide.

🔗 Human rights 🔗 Philosophy 🔗 Freedom of speech 🔗 Philosophy/Logic 🔗 Politics 🔗 Psychology 🔗 Sociology 🔗 Education 🔗 Popular Culture 🔗 Debating

A lie-to-children is a simplified, and often technically incorrect, explanation of technical or complex subjects employed as a teaching method. Educators who employ lies-to-children do not intend to deceive, but instead seek to 'meet the child/pupil/student where they are', in order to facilitate initial comprehension, which they build upon over time as the learner's intellectual capacity expands. The technique has been incorporated by academics within the fields of biology, evolution, bioinformatics and the social sciences.

🔗 African diaspora 🔗 Oklahoma 🔗 Oklahoma/Task-force Tulsa

The Tulsa race massacre (also called the Tulsa race riot, the Greenwood Massacre, or the Black Wall Street Massacre) of 1921 took place on May 31 and June 1, 1921, when mobs of white residents attacked black residents and businesses of the Greenwood District in Tulsa, Oklahoma. It has been called "the single worst incident of racial violence in American history." The attack, carried out on the ground and from private aircraft, destroyed more than 35 square blocks of the district – at that time the wealthiest black community in the United States, known as "Black Wall Street".

More than 800 people were admitted to hospitals and as many as 6,000 black residents were interned at large facilities, many for several days. The Oklahoma Bureau of Vital Statistics officially recorded 36 dead, but the American Red Cross declined to provide an estimate. A 2001 state commission examination of events was able to confirm 39 dead, 26 black and 13 white, based on contemporary autopsy reports, death certificates and other records. The commission gave overall estimates from 75–100 to 150–300 dead.

The massacre began over Memorial Day weekend after 19-year-old Dick Rowland, a black shoeshiner, was accused of assaulting Sarah Page, the 17-year-old white elevator operator of the nearby Drexel Building. He was taken into custody. A subsequent gathering of angry local whites outside the courthouse where Rowland was being held, and the spread of rumors he had been lynched, alarmed the local black population, some of whom arrived at the courthouse armed. Shots were fired and twelve people were killed: ten white and two black. As news of these deaths spread throughout the city, mob violence exploded. White rioters rampaged through the black neighborhood that night and morning killing men and burning and looting stores and homes, and only around noon the next day Oklahoma National Guard troops managed to get control of the situation by declaring martial law. About 10,000 black people were left homeless, and property damage amounted to more than $1.5 million in real estate and $750,000 in personal property (equivalent to $32.25 million in 2019).

Many survivors left Tulsa. Black and white residents who stayed in the city were silent for decades about the terror, violence, and losses of this event. The massacre was largely omitted from local, state, and national histories.

In 1996, seventy-five years after the massacre, a bipartisan group in the state legislature authorized formation of the Oklahoma Commission to Study the Tulsa Race Riot of 1921 (renamed Oklahoma Commission to Study the Tulsa Race Massacre, in November 2018). Members were appointed to investigate events, interview survivors, hear testimony from the public, and prepare a report of events. There was an effort toward public education about these events through the process. The Commission's final report, published in 2001, said that the city had conspired with the mob of white citizens against black citizens; it recommended a program of reparations to survivors and their descendants. The state passed legislation to establish some scholarships for descendants of survivors, encourage economic development of Greenwood, and develop a memorial park in Tulsa to the massacre victims. The park was dedicated in 2010. In 2020, the massacre became part of the Oklahoma school curriculum.

🔗 Mathematics 🔗 Statistics

The Gompertz curve or Gompertz function is a type of mathematical model for a time series, named after Benjamin Gompertz (1779–1865). It is a sigmoid function which describes growth as being slowest at the start and end of a given time period. The right-side or future value asymptote of the function is approached much more gradually by the curve than the left-side or lower valued asymptote. This is in contrast to the simple logistic function in which both asymptotes are approached by the curve symmetrically. It is a special case of the generalised logistic function. The function was originally designed to describe human mortality, but since has been modified to be applied in biology, with regard to detailing populations.

🔗 Computing

FILE_ID.DIZ is a plain text file containing a brief content description of the archive in which it is included. It was originally used in archives distributed through bulletin board systems (BBS), and still in the warez scene.

Bulletin boards commonly accept uploaded files from their users. The BBS software would prompt the user to supply a description for the uploaded file, but these descriptions were often less than useful. BBS system operators spent many hours going over the upload descriptions correcting and editing the descriptions. The FILE_ID.DIZ inclusion in archives was designed to address this problem.

FILE_ID stands for "file identification". DIZ stands for Description In Zipfile.

Clark Development and the Association of Shareware Professionals supported the idea of this becoming a standard for file descriptions. Clark rewrote the PCBDescribe program and included it with their PCBoard BBS software. The ASP urged their members to use this description file format in their distributions. Michael Leavitt, an employee of Clark Development, released the file specification and his PCBDescribe program source code to the public domain and urged other BBS software companies to support the DIZ file.

SysOps could add a common third-party script written in PPL, called "DIZ/2-PCB" that would process, rewrite, verify, and format DIZ files from archives as they were uploaded to a BBS. The software would extract the archive, examine the contents, compile a report, import the DIZ description file and then format it according to your liking. During this time, it was usual practice to add additional lines to the description, such as ads exclaiming the source of the uploaded BBS.

Traditionally, a FILE_ID.DIZ should be "up to 10 lines of text, each line being no more than 45 characters long." according to the specification v1.9.

The concept of DIZ files was to allow a concise description of uploaded files to be automatically applied. Advertisements and "high ASCII" artwork were specifically prohibited.

Even since the decline of the dial-up bulletin board system, FILE_ID.DIZ files are still utilized by the warez scene in their releases of unlicensed software. They are commonly bundled as part of the complete packaging by self-described pirate groups, and indicate the number of disks, and other basic information. Along with the NFO file, it is essential to the release. Especially in terms of unlicensed software ("warez"), it was common for each file in a sequential compressed archive (an archive intentionally split into multiple parts at creation so the parts can then be individually downloaded by slower connections like dial-up. Example: .rar, .r00, .r01, .r02, etc.), to contain this file. This probably contributed to its extended popularity after the decline of the bulletin board system in the late 1990s and early 2000s until now, since even casual consumers of unlicensed software would have stumbled upon it due to its abundance.