Turn (biochemistry)

A turn is an element of secondary structure in proteins where the polypeptide chain reverses its overall direction. For beta turns go to Beta turn.

Definition

According to one definition, a turn is a structural motif where the C^α atoms of two residues separated by few (usually 1 to 5) peptide bonds are close (< 7 Å), while the residues do not form a secondary structure element such as an alpha helix or beta sheet with regularly repeating backbone dihedral angles. Although the proximity of the terminal C^α atoms usually correlates with formation of a hydrogen bond between the corresponding residues, a hydrogen bond is not a requirement in this turn definition. That said, in many cases the H-bonding and C^α-distance definitions are equivalent.

Types of turns

Turns are classified according to the separation between the two end residues:

In an α-turn the end residues are separated by four peptide bonds ().

In a β-turn (the most common form), by three bonds ().

In a γ-turn, by two bonds ().

Turn (Travis song)

"Turn" is the fourth single from Indie band Travis' second studio album, The Man Who. The single peaked at the number eight position on the UK Singles Chart.

Music video

Two music videos were shot for the single. The first video, included on the group's Singles DVD, features Healy engaged in a push-up contest. This video was filmed in Hackney on a dis-used council estate. The estate has since been demolished. The second featured a staged performance by the band.

B-sides

The British release of the single was accompanied by a cover of Britney Spears's hit single "...Baby One More Time". Spears herself heard the Travis version while shopping, and commented by saying it was 'a total shock' and was 'a very good cover'.

Track listing

Turn (Roscoe Mitchell album)

Turn is an album by American jazz saxophonist Roscoe Mitchell which was recorded in 2005 and released on the French RogueArt label. He leads a new quintet with longtime rhythm section Jaribu Shahid on bass and Tani Tabbal on drums, pianist Craig Taborn and new Art Ensemble of Chicago trumpeter Corey Wilkes.

Reception

In his review for AllMusic, Alain Drouot states "This is a remarkably focused and concise date featuring Mitchell's brand of atonal jazz mixed with his interests in other musical forms."

The All About Jazz review by Kurt Gottschalk says "As a whole, the group is comfortable together, ready to let the compositions stand and while Shahid and Tabal haven't been the most exciting parts of Mitchell's groups, here they sound better than ever."

Track listing

Turn (geometry)

A turn is a unit of plane angle measurement equal to 2π radians, 360° or 400 gon. A turn is also referred to as a revolution or complete rotation or full circle or cycle or rev or rot.

A turn can be subdivided in many different ways: into half turns, quarter turns, centiturns, milliturns, binary angles, points etc.

Subdivision of turns

A turn can be divided in 100 centiturns or 1000 milliturns, with each milliturn corresponding to an angle of 0.36°, which can also be written as 21′ 36″. A protractor divided in centiturns is normally called a percentage protractor.

Binary fractions of a turn are also used. Sailors have traditionally divided a turn into 32 compass points. The binary degree, also known as the binary radian (or brad), is ¹⁄₂₅₆ turn. The binary degree is used in computing so that an angle can be represented to the maximum possible precision in a single byte. Other measures of angle used in computing may be based on dividing one whole turn into 2ⁿ equal parts for other values of n.

Beta (disambiguation)

Beta (B, β) is the second letter of the Greek alphabet.

Beta or BETA

may also refer to:

Automotive

Computing and technology

Geography

Beta (finance)

In finance, the beta (β or beta coefficient) of an investment indicates whether the investment is more or less volatile than the market. In general, a beta less than 1 indicates that the investment is less volatile than the market, while a beta more than 1 indicates that the investment is more volatile than the market. Volatility is measured as the fluctuation of the price around the mean: the standard deviation.

Beta is a measure of the risk arising from exposure to general market movements as opposed to idiosyncratic factors. The market portfolio of all investable assets has a beta of exactly 1. A beta below 1 can indicate either an investment with lower volatility than the market, or a volatile investment whose price movements are not highly correlated with the market. An example of the first is a treasury bill: the price does not go up or down a lot, so it has a low beta. An example of the second is gold. The price of gold does go up and down a lot, but not in the same direction or at the same time as the market.

Beta (time signal)

Beta is a time signal service in the VLF range in Russia, operated by the Russian Navy. There are 6 transmitter stations, which take turns transmitting time signals and other communications.

Although the transmitters are active 24 hours a day, each transmits the time code one hour per day.

Beginning on the hour is 25 minutes of 25.0 kHz, including morse code station identification and time code. This is followed by 5-minute intervals of 25.1, 25.5, 23.0 and 20.5 kHz. No time code is sent during the last quarter of an hour.

The Beta network

Beta consists of the following transmitters:

Frequency usage

The time code consists of a series of signals on multiple frequencies. Transmission starts on the hour. Each time a new frequency is selected, there is 1 minute of low power while the transmitter is adjusted, then full-power transmissions begin.

The transmitters are estimated to operate at 1000 kW, achieving 30–50 kW EIRP. (The difference is due to the low efficiency of antennas at this frequency, which must be much smaller than the 12 km wavelength.)