Have a deep view into what people are curious about.

🔗 Mathematics

In mathematics, a combinatorial explosion is the rapid growth of the complexity of a problem due to how the combinatorics of the problem is affected by the input, constraints, and bounds of the problem. Combinatorial explosion is sometimes used to justify the intractability of certain problems. Examples of such problems include certain mathematical functions, the analysis of some puzzles and games, and some pathological examples which can be modelled as the Ackermann function.

🔗 California 🔗 Business 🔗 Politics 🔗 Trains 🔗 Politics/American politics 🔗 Trains/Rapid transit 🔗 Buses 🔗 Trains/Streetcars

The notion of a General Motors streetcar conspiracy emerged after General Motors (GM) and other companies were convicted of monopolizing the sale of buses and supplies to National City Lines (NCL) and its subsidiaries. In the same case, the defendants were accused of conspiring to own or control transit systems, in violation of Section 1 of the Sherman Antitrust act. The suit created lingering suspicions that the defendants had in fact plotted to dismantle streetcar systems in many cities in the United States as an attempt to monopolize surface transportation.

Between 1938 and 1950, National City Lines and its subsidiaries, American City Lines and Pacific City Lines—with investment from GM, Firestone Tire, Standard Oil of California (through a subsidiary), Federal Engineering, Phillips Petroleum, and Mack Trucks—gained control of additional transit systems in about 25 cities. Systems included St. Louis, Baltimore, Los Angeles, and Oakland. NCL often converted streetcars to bus operations in that period, although electric traction was preserved or expanded in some locations. Other systems, such as San Diego's, were converted by outgrowths of the City Lines. Most of the companies involved were convicted in 1949 of conspiracy to monopolize interstate commerce in the sale of buses, fuel, and supplies to NCL subsidiaries, but were acquitted of conspiring to monopolize the transit industry.

The story as an urban legend has been written about by Martha Bianco, Scott Bottles, Sy Adler, Jonathan Richmond, and Robert Post. It has been explored several times in print, film, and other media, notably in Who Framed Roger Rabbit, Taken for a Ride, Internal Combustion, and The End of Suburbia.

Only a handful of U.S. cities, including San Francisco, New Orleans, Newark, Cleveland, Philadelphia, Pittsburgh, and Boston, have surviving legacy rail urban transport systems based on streetcars, although their systems are significantly smaller than they once were. Other cities are re-introducing streetcars. In some cases, the streetcars do not actually ride on the street. Boston had all of its downtown lines elevated or buried by the mid-1920s, and most of the surviving lines at grade operate on their own right of way. However, San Francisco's and Philadelphia's lines do have large portions of the route that ride on the street as well as using tunnels.

🔗 Companies 🔗 Finance & Investment 🔗 Lists 🔗 Business 🔗 Business/Accounting

This page lists the largest annual and quarterly earnings and losses in corporate history. In general terms the oil and gas industry is the one generating both largest annual and quarterly earnings. In contrast, both the annual and quarterly losses are more distributed across industries.

🔗 Mathematics 🔗 Physics

Stochastic resonance (SR) is a phenomenon where a signal that is normally too weak to be detected by a sensor, can be boosted by adding white noise to the signal, which contains a wide spectrum of frequencies. The frequencies in the white noise corresponding to the original signal's frequencies will resonate with each other, amplifying the original signal while not amplifying the rest of the white noise (thereby increasing the signal-to-noise ratio which makes the original signal more prominent). Further, the added white noise can be enough to be detectable by the sensor, which can then filter it out to effectively detect the original, previously undetectable signal.

This phenomenon of boosting undetectable signals by resonating with added white noise extends to many other systems, whether electromagnetic, physical or biological, and is an area of research.

Tide-Predicting Machine No. 2, also known as Old Brass Brains, was a special-purpose mechanical computer that uses gears, pulleys, chains, and other mechanical components to compute the height and time of high and low tides for specific locations. The machine can perform tide calculations much faster than a person could do with pencil and paper. The U.S. Coast and Geodetic Survey put the machine into operation in 1910. It was used until 1965, when it was replaced by an electronic computer.

🔗 Poetry

A clerihew () is a whimsical, four-line biographical poem invented by Edmund Clerihew Bentley. The first line is the name of the poem's subject, usually a famous person put in an absurd light, or revealing something unknown or spurious about them. The rhyme scheme is AABB, and the rhymes are often forced. The line length and metre are irregular. Bentley invented the clerihew in school and then popularized it in books. One of his best known is this (1905):

🔗 Cryptography 🔗 Cryptography/Computer science

Shamir's Secret Sharing is an algorithm in cryptography created by Adi Shamir. It is a form of secret sharing, where a secret is divided into parts, giving each participant its own unique part.

To reconstruct the original secret, a minimum number of parts is required. In the threshold scheme this number is less than the total number of parts. Otherwise all participants are needed to reconstruct the original secret.

🔗 Physics

The Einstein–Szilard or Einstein refrigerator is an absorption refrigerator which has no moving parts, operates at constant pressure, and requires only a heat source to operate. It was jointly invented in 1926 by Albert Einstein and his former student Leó Szilárd, who patented it in the U.S. on November 11, 1930 (U.S. Patent 1,781,541). The three working fluids in this design are water, ammonia and butane. The Einstein refrigerator is a development of the original three-fluid patent by the Swedish inventors Baltzar von Platen and Carl Munters.

🔗 Industrial design

The Xerox 914 was the first successful commercial plain paper copier which in 1959 revolutionized the document-copying industry. The culmination of inventor Chester Carlson's work on the xerographic process, the 914 was fast and economical. The copier was introduced to the public on September 16, 1959, in a demonstration at the Sherry-Netherland Hotel in New York, shown on live television.