Crab (scratch)

A crab is a type of scratch used by turntablists. It is made from a combination of moving the record on the turntable by hand and quick movement of the crossfader.

Creation

The crab scratch was invented by DJ Qbert as a variation on DJ Excel's "twiddle." The two met up in Japan for the Vestax DJ competition in 1995 and Excel was asking Qbert how to flare. When he showed Qbert how he thought the flare was performed, he was actually doing the twiddle instead (using his thumb as a spring and "twiddling" the fader with 2 fingers). After this meeting, Qbert took the idea back to San Francisco and after showing the scratch to DJ Disk, he created a move that used 3 or 4 fingers: the crab. Later in 1995, while the DMC USA finals were being held in San Francisco, a group of DJs and judges which included The Beat Junkies, The X-Men (now called the X-ecutioners), and the rest of ISP among others got together for what would later be known as the "Famous Warehouse Session" at Yoga Frog's old mobile DJ warehouse. It was at this session that Qbert publicized the new scratch.

Scratch (horse)

Scratch, also known as Scratch II (foaled 1947) was a French Thoroughbred racehorse and sire best known for winning the Prix du Jockey Club and the classic St Leger Stakes in 1950. Scratch won the Solario Stakes in England as a two-year-old and emerged as one of the best of a very strong generation of French-trained colts in the following year. He won the Prix de Guiche and Prix Greffulhe in the early part of the year and then defeated the year's outstanding three-year-old colt Tantieme in the Prix du Jockey Club. In the autumn of 1950 he won the St Leger by defeating Vieux Manoir, who had beaten him in the Grand Prix de Paris. He won the Prix Jean Prat as a four-year-old before being retired to stud where he had an unremarkable record as a sire of winners in Europe and South America.

Background

Scratch was a chestnut horse with a white star and a white sock on his right hind leg bred by his owner Marcel Boussac. He was sired by Pharis, the undefeated winner of the 1939 Grand Prix de Paris. Scratch's dam Orlamonde was an unsuccessful racehorse but produced several other winners including Damno, who won the Prix d'Arenberg. Orlamonde's dam Naic was a half sister of the Prix du Jockey Club winner Ramus and also produced the Grand Prix de Deauville winner Jock. Scratch was sent into training with Charles Semblat at Chantilly.

Gobots

GoBots was a line of transforming robot toys produced by Tonka from 1983 to 1987, similar to Transformers. Although initially a separate and competing franchise, Tonka's Gobots became the intellectual property of Hasbro after their buyout of Tonka in 1991. Subsequently, the universe depicted in the animated series Challenge of the GoBots and follow-up film GoBots: Battle of the Rock Lords was established as an alternate universe within the Transformers franchise. While Hasbro now owns the fictional side of the property (character names, bios, storyline), the actual toys and their likenesses were only licensed from Bandai in the 80s, were not covered by the Tonka acquisition, and are not available for Hasbro use.

History

The Gobot toyline was based on figures produced by Popy of Japan (later Bandai), named Machine Robo. In another similarity to Transformers, Tonka decided to make the figures sentient robots, rather than human-piloted mecha as they had been in Japan, and divided them into two factions – the good Guardians and evil Renegades (although early figures were simply described as ‘Friendly’ or ‘Enemy’ on the packaging). The figures were all given individual names, in contrast to the simple designations they received in Japan.

Scratch (soundtrack)

Scratch is the soundtrack to the 2001 documentary Scratch directed by Doug Pray. Scratch examines cultural and historical perspectives on the birth and evolution of hip-hop disc jockeys (DJs), scratching and turntablism and includes interviews with some of hip-hop's most famous and respected DJs.

Track list

Crab

Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) (Greek: βραχύς / brachys = short,οὐρά / οura = tail), usually entirely hidden under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton and have a single pair of claws. Many other animals with similar names – such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs and crab lice – are not true crabs.

Evolution

Crabs are generally covered with a thick exoskeleton, composed primarily of calcium carbonate, and armed with a single pair of chelae (claws). Crabs are found in all of the world's oceans, while many crabs live in fresh water and on land, particularly in tropical regions. Crabs vary in size from the pea crab, a few millimetres wide, to the Japanese spider crab, with a leg span of up to 4 metres (13 ft).

About 850 species of crab are freshwater, terrestrial or semi-terrestrial species; they are found throughout the world's tropical and semi-tropical regions. They were previously thought to be a monophyletic group, but are now believed to represent at least two distinct lineages, one in the Old World and one in the New World.

Crab (unit)

A Crab is a standard astrophotometrical unit for measurement of the intensity of Astrophysical X-ray sources. One Crab is defined as the intensity of the Crab Nebula at the corresponding X-ray photon energy.

The Crab Nebula, and the Crab Pulsar within it, is an intense space X-ray source. It is used as a standard candle in the calibration procedure of X-ray instruments in space. However, because of the Crab Nebula's variable intensity at different X-ray energies, conversion of the Crab to another units depends on the X-ray energy range of interest.

In the photon energy range from 2 to 10 keV, 1 Crab equals 2.4 · 10⁻⁸erg cm⁻²s⁻¹ = 15 keV cm⁻² s⁻¹ = 2.4 · 10⁻¹¹W m⁻². For energies greater than ~30 keV, the Crab Nebula becomes unsuitable for calibration purposes, as its flux can no longer be characterized by a single coherent model.

The unit mCrab, or milliCrab, is sometimes used instead of the Crab.

References

Crab (cipher)

In cryptography, Crab is a block cipher proposed by Burt Kaliski and Matt Robshaw at the first Fast Software Encryption workshop in 1993. Not really intended for use, Crab was developed to demonstrate how ideas from hash functions could be used to create a fast cipher.

Crab has an unusually large block size of 8192 bits. Its creators suggested using an 80-bit key, but the cipher could use any key size. The authors didn't specify an actual key schedule, only that the key is used to generate two large sets of subkeys: a permutation of the numbers 0 through 255, and an array of 2048 32-bit numbers. The block is divided into 256 32-bit subblocks, which are permuted at the beginning. Then the algorithm makes four passes over the data, each time applying one of four transformations adapted from MD5.

A brief note on the cryptanalysis of Crab is included in Markku-Juhani Saarinen's paper on block ciphers based on SHA-1 and MD5, published at FSE 2003. The author demonstrates a weakness in Crab that permits a distinguisher using no more than a dozen chosen plaintexts, and speculates that this can be converted into a full key-recovery attack using no more than 2¹⁶ chosen plaintexts. Such an attack would depend on the key schedule used.