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🔗 Mass surveillance 🔗 Espionage 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Maritime warfare 🔗 Cold War

Operation Ivy Bells was a joint United States Navy, Central Intelligence Agency (CIA), and National Security Agency (NSA) mission whose objective was to place wire taps on Soviet underwater communication lines during the Cold War.

🔗 Technology 🔗 Canada 🔗 Guild of Copy Editors 🔗 Engineering

A screw drive is a system used to turn a screw. At a minimum, it is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. The following heads are categorized based on commonality, with some of the less-common drives being classified as "tamper-resistant".

Most heads come in a range of sizes, typically distinguished by a number, such as "Phillips #00". These sizes do not necessarily describe a particular dimension of the drive shape, but rather are arbitrary designations.

🔗 Film 🔗 Film/Filmmaking

The zoöpraxiscope (initially named zoographiscope and zoogyroscope) is an early device for displaying moving images and is considered an important predecessor of the movie projector. It was conceived by photographic pioneer Eadweard Muybridge in 1879 (and built for him by January 1880 to project his famous chronophotographic pictures in motion and thus prove that these were authentic). Muybridge used the projector in his public lectures from 1880 to 1895. The projector used 16" glass disks onto which Muybridge had an unidentified artist paint the sequences as silhouettes. This technique eliminated the backgrounds and enabled the creation of fanciful combinations and additional imaginary elements. Only one disk used photographic images, of a horse skeleton posed in different positions. A later series of 12" discs, made in 1892–1894, used outlines drawn by Erwin F. Faber that were printed onto the discs photographically, then colored by hand. These colored discs were probably never used in Muybridge's lectures. All images of the known 71 disks, including those of the photographic disk, were rendered in elongated form to compensate the distortion of the projection. The projector was related to other projecting phenakistiscopes and used some slotted metal shutter discs that were interchangeable for different picture disks or different effects on the screen. The machine was hand-cranked.

The device appears to have been one of the primary inspirations for Thomas Edison and William Kennedy Dickson's Kinetoscope, the first commercial film exhibition system. Images from all of the known seventy-one surviving zoopraxiscope discs have been reproduced in the book Eadweard Muybridge: The Kingston Museum Bequest (The Projection Box, 2004).

...it is the first apparatus ever used, or constructed, for synthetically demonstrating movements analytically photographed from life, and in its resulting effects is the prototype of the various instruments which, under a variety of names, are used for a similar purpose at the present day.

As stipulated in Muybridge's will the original machine and disks in his possession were left to Kingston upon Thames, where they are still kept in the Kingston Museum Muybridge Bequest Collection (except for four discs that are in other collections, including those of the Cinémathèque française and the National Technical Museum in Prague).

Muybridge also produced a series of 50 different paper 'Zoopraxiscope discs' (basically phenakistiscopes), again with pictures drawn by Erwin F. Faber. The discs were intended for sale at the 1893 World's Fair at Chicago, but seem to have sold very poorly and are quite rare. The discs were printed in black-and-white, with twelve different discs also produced as chromolithographed versions. Of the coloured versions only four different ones are known to still exist with a total of five or six extant copies.

🔗 Chess

Kasparov versus the World was a game of chess played in 1999 over the Internet. Conducting the white pieces, Garry Kasparov faced the rest of the world in consultation, with the World Team moves to be decided by plurality vote. Over 50,000 people from more than 75 countries participated in the game.

The host and promoter of the match was the MSN Gaming Zone, with sponsorship from First USA bank. After 62 moves played over four months, Kasparov won the game. Contrary to expectations, the game produced a mixture of deep tactical and strategic ideas, and although Kasparov won, he admitted that he had never expended as much effort on any other game in his life. He later said, "It is the greatest game in the history of chess. The sheer number of ideas, the complexity, and the contribution it has made to chess make it the most important game ever played."

🔗 Internet

🔗 Energy

The gravitation water vortex power plant is a type of micro hydro vortex turbine system which is capable of converting energy in a moving fluid to rotational energy using a low hydraulic head of 0.7–3 metres (2 ft 4 in–9 ft 10 in). The technology is based on a round basin with a central drain. Above the drain the water forms a stable line vortex which drives a water turbine.

It was first patented by Greek-Australian Lawyer & Inventor Paul Kouris in 1996, who was searching for a way to harness the power inherent in a vortex.

Later, Austrian Inventor Franz Zotlöterer created a similar turbine while attempting to find a way to aerate water without an external power source.

🔗 United States History 🔗 Past Political Scandals and Controversies

The Burr conspiracy was a suspected treasonous cabal of US planters, politicians, and army officers in the early 19th century. The alleged cabal was led by Aaron Burr, the former Vice President of the United States (1801–1805). According to the accusations against him, his goal was to create an independent country in the center of North America including the Southwestern United States and parts of Mexico. Burr's version was that he intended to farm 40,000 acres (160 km²) in the Texas Territory which had been leased to him by the Spanish Crown.

President Thomas Jefferson ordered Burr arrested and indicted for treason, despite a lack of firm evidence. Burr's true intentions remain unclear to historians; some claim that he intended to take parts of Texas and the Louisiana Purchase for himself, others, that he intended to conquer Mexico, and yet others, that he planned to conquer most of the North American continent. The number of men backing him is also unclear, with accounts varying from fewer than forty to over seven thousand. He was acquitted of treason, but the trial destroyed his already faltering political career.

🔗 Video games 🔗 Computer science 🔗 Mathematics

Fast inverse square root, sometimes referred to as Fast InvSqrt() or by the hexadecimal constant 0x5F3759DF, is an algorithm that estimates ​¹⁄_√x, the reciprocal (or multiplicative inverse) of the square root of a 32-bit floating-point number x in IEEE 754 floating-point format. This operation is used in digital signal processing to normalize a vector, i.e., scale it to length 1. For example, computer graphics programs use inverse square roots to compute angles of incidence and reflection for lighting and shading. The algorithm is best known for its implementation in 1999 in the source code of Quake III Arena, a first-person shooter video game that made heavy use of 3D graphics. The algorithm only started appearing on public forums such as Usenet in 2002 or 2003. At the time, it was generally computationally expensive to compute the reciprocal of a floating-point number, especially on a large scale; the fast inverse square root bypassed this step.

The algorithm accepts a 32-bit floating-point number as the input and stores a halved value for later use. Then, treating the bits representing the floating-point number as a 32-bit integer, a logical shift right by one bit is performed and the result subtracted from the number 0x5F3759DF, which is a floating point representation of an approximation of √2¹²⁷. This results in the first approximation of the inverse square root of the input. Treating the bits again as a floating-point number, it runs one iteration of Newton's method, yielding a more precise approximation.

The algorithm was originally attributed to John Carmack, but an investigation showed that the code had deeper roots in both the hardware and software side of computer graphics. Adjustments and alterations passed through both Silicon Graphics and 3dfx Interactive, with Gary Tarolli's implementation for the SGI Indigo as the earliest known use. It is not known how the constant was originally derived, though investigation has shed some light on possible methods.

With subsequent hardware advancements, especially the x86 SSE instruction rsqrtss, this method is not generally applicable to modern computing, though it remains an interesting example both historically and for more limited machines.

🔗 Computing 🔗 Computing/Early computers

The IBM 7950, also known as Harvest, was a one-of-a-kind adjunct to the Stretch computer which was installed at the United States National Security Agency (NSA). Built by IBM, it was delivered in 1962 and operated until 1976, when it was decommissioned. Harvest was designed to be used for cryptanalysis.

🔗 Pharmacology

Eroom's law is the observation that drug discovery is becoming slower and more expensive over time, despite improvements in technology (such as high-throughput screening, biotechnology, combinatorial chemistry, and computational drug design), a trend first observed in the 1980s. The cost of developing a new drug roughly doubles every nine years (inflation-adjusted). In order to highlight the contrast with the exponential advancements of other forms of technology (such as transistors) over time, the law was deliberately spelled as Moore's law spelled backwards.

The article proposing and naming the law attributes it to four main causes.

• the 'better than the Beatles' problem: the sense that new drugs only have modest incremental benefit over drugs already widely considered as successful, such as Lipitor, and treatment effects on top of already effective treatments are smaller than treatment effects versus placebo. The smaller size of these treatment effects mandates an increase in clinical trial sizes to show the same level of efficacy. This problem was phrased as "better than the Beatles" to highlight the fact that it would be difficult to come up with new successful pop songs if all new songs had to be better than the Beatles.
• the 'cautious regulator' problem: the progressive lowering of risk tolerance seen by drug regulatory agencies that makes R&D both costlier and harder. After older drugs (such as Thalidomide or Vioxx) are removed from the market due to safety reasons, the bar on safety for new drugs is increased.
• the 'throw money at it' tendency: the tendency to add human resources and other resources to R&D, which may lead to project overrun.
• the 'basic research–brute force' bias: the tendency to overestimate the ability of advances in basic research and brute force screening methods to show a molecule as safe and effective in clinical trials. From the 1960s to the 1990s (and later), drug discovery has shifted from whole-animal classical pharmacology testing methods (phenotypic screening) to reverse pharmacology target-approaches that result in the discovery of drugs that may tightly bind with high-affinity to target proteins, but which still often fail in clinical trials due to an under-appreciation of the complexity of the whole organism. Furthermore, drug discovery techniques have shifted from small-molecule and iterative low-throughput search strategies to target-based high-throughput screening (HTS) of large compound libraries. But despite being faster and cheaper, HTS approaches may be less productive.

While some suspect a lack of "low-hanging fruit" as a significant contribution to Eroom's law, this may be less important than the four main causes, as there are still many decades' worth of new potential drug targets relative to the number of targets which already have been exploited, even if the industry exploits 4 to 5 new targets per year. There is also space to explore selectively non-selective drugs (or "dirty drugs") that interact with several molecular targets, and which may be particularly effective as central nervous system (CNS) therapeutics, even though few of them have been introduced in the last few decades.