Fall back and forward

Fall back is a feature of a modem protocol in data communication whereby two communicating modems which experience data corruption (due to line noise, for example) can renegotiate with each other to use a lower-speed connection. Fall forward is a corresponding feature whereby two modems which have "fallen back" to a lower speed can later return to the higher speed if the connection improves.

A common feature modems was the concept of fallback, allowing them to talk to less-capable modems. During the call initiation the modem would play a series of signals into the line and wait for the remote modem to "answer" them. They would start at high speeds and progressively get slower and slower until they heard an answer. Thus, two USR modems would be able to connect at 9600 bit/s, but, when a user with a 2400-bit/s modem called in, the USR would "fall back" to the common 2400-bit/s speed. This would also happen if a V.32 modem and a HST modem were connected. Because they used a different standard at 9600 bit/s, they would fall back to their highest commonly supported standard at 2400 bit/s. The same applies to V.32bis and 14400 bit/s HST modem, which would still be able to communicate with each other at only 2400 bit/s.

Dear Jayne

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Dear Jayne is a R&B/pop trio from Atlanta, Georgia. Their debut album, Voice Message, was originally scheduled to be released in March 2008 but has been cancelled indefinitely. One single scheduled to be on the album, "Rain", broke onto the Billboard Hot R&B/Hip-Hop Songs chart, peaking at number 99.

History

Based in Atlanta, the trio consists of Ashley, 22, Jasmine, 22, and Lindsey, 19. The group was assembled by Anthony Tate, a manager and producer who also worked with Ciara, Teairra Mari and J. Holiday. Ashley is from Los Angeles' Crenshaw district; Jasmine is from Cocoa Beach, Florida; Lindsey is from Atlanta’s College Park district. The group's lead single, "Rain", was produced by Carlos McKinney, who previously worked on J. Holiday’s "Bed"; the single reached the Billboard R&B charts in January 2008. In on report it was described as an answer record to Rihanna's "Umbrella". Lindsey has now left the group and has been replaced by singer Emori Campbell.

OP

OP, O.P., Op, or Op. may refer to:

Arts

Internet and gaming

Mathematics

Organizations

Dominican Order

The Order of Preachers (Latin: Ordo Praedicatorum, hence the abbreviation OP used by members), more commonly known after the 15th century as the Dominican Order or Dominicans, is a Roman Catholic religious order founded by the Spanish priest Saint Dominic de Guzman in France and approved by Pope Honorius III (1216–27) on 22 December 1216. Membership in this "mendicant" Order includes friars, nuns, active sisters, and lay or secular Dominicans (formerly known as tertiaries, though recently there has been a growing number of Associates, who are unrelated to the tertiaries) affiliated with the Order.

Founded to preach the Gospel and to combat heresy, the teaching activity of the order and its scholastic organization placed the Preachers in the forefront of the intellectual life of the Middle Ages. The order is famed for its intellectual tradition, having produced many leading theologians and philosophers. The Dominican Order is headed by the Master of the Order, who is currently Bruno Cadoré. Members of the order generally carry the letters O.P., standing for Ordinis Praedicatorum, meaning of the Order of Preachers, after their names.

Phosphorus pentoxide

Phosphorus pentoxide is a chemical compound with molecular formula P₄O₁₀ (with its common name derived from its empirical formula, P₂O₅). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.

Structure

Phosphorus pentoxide crystallizes in at least four forms or polymorphs. The most familiar one, a metastable form, shown in the figure, comprises molecules of P₄O₁₀. Weak van der Waals forces hold these molecules together in a hexagonal lattice (However, in spite of the high symmetry of the molecules, the crystal packing is not a close packing). The structure of the P₄O₁₀ cage is reminiscent of adamantane with T_dsymmetry point group. It is closely related to the corresponding anhydride of phosphorous acid, P₄O₆. The latter lacks terminal oxo groups. Its density is 2.30 g/cm³. It boils at 423 °C under atmospheric pressure; if heated more rapidly it can sublimate. This form can be made by condensing the vapor of phosphorus pentoxide rapidly, the result is an extremely hygroscopic solid.