Delete key

The delete key is a key on most computer keyboards which typically is used to delete either (in text mode) the character ahead of or beneath the cursor, or (in GUI mode) the currently-selected object.

Position and labelling on keyboards

The key appears on English-language IBM-compatible PC keyboards labeled as Delete or Del, sometimes accompanied by a crossed-out right-arrow symbol. However, sometimes the key labelled Delete performs the Backspace function instead, for example on some Apple keyboards.

In other cases, the Delete key is in its original IBM notebook position of above and to the right of the Backspace key. Many laptops add rows of smaller keys above the Function key line to add keys on a non-standard size keyboard. On this row of smaller keys, the position of the Delete key is positioned at or near the right-hand end. On Apple's line of laptops (e.g. the MacBook and MacBook Pro), the forward delete function can be achieved using the Fn+← Backspace key combination.

The Delete key is typically smaller and less-conveniently located than the Backspace key, and on keyboards where space is limited, for example those omitting the numeric keypad or virtual keyboards on mobile devices, it is often omitted altogether.

Alpha Delphini

Alpha Delphini (α Del, α Delphini) is a multiple star in the constellation Delphinus. It also has the name Sualocin, which was given to it as a practical joke by the astronomer Niccolò Cacciatore; the name is the Latinized version (Nicolaus) of his given name, spelled backwards.

In Chinese, 瓠瓜 (Hù Guā), meaning Good Gourd, refers to an asterism consisting of α Delphini, γ² Delphini, δ Delphini, β Delphini and ζ Delphini. Consequently, α Delphini itself is known as 瓠瓜一 (Hù Guā yī, English: the First Star of Good Gourd.).

Properties

Alpha Delphini has seven components: A and G, a physical binary, and B, C, D, E, and F, which are optical binaries and have no physical association with A and G.

See also

References

References

Beta Delphini

Beta Delphini (Beta Del, β Delphini, β Del) is a binary star in the constellation of Delphinus. As a practical joke, the astronomer Niccolò Cacciatore gave it the name Rotanev, which is a reversal of his Latinized family name, Venator. The name first appeared in Giuseppe Piazzi's Palermo Catalogue, published in 1814. Beta Delphini was found to be a binary star system in 1873 by the American astronomer S. W. Burnham.

In Chinese, 瓠瓜 (Hù Guā), meaning Good Gourd, refers to an asterism consisting of β Delphini, α Delphini, γ² Delphini, δ Delphini, and ζ Delphini. Consequently, β Delphini itself is known as 瓠瓜二 (Hù Guā-er, English: the Second Star of Good Gourd.).

This system consists of a pair of F-type stars stars that orbit each other with a period of 26.66 years and an eccentricity of 0.36. The plane of the orbit is inclined by an angle of 61° to the line of sight from the Earth. The two stars have an angular separation of about 0.44 arcseconds, making them a challenge to resolve with a telescope. The larger member of the pair is a giant star with 1.75 times the mass and 24 times the luminosity of the Sun, while the secondary component is a subgiant star that has 1.47 times the Sun's mass and around 8 times the Sun's luminosity. The system is around 1.8 billion years old.

Keynote (presentation software)

Keynote is a presentation software application developed as a part of the iWork productivity suite by Apple Inc. Keynote 6.0 was announced on October 23, 2013 and is the most recent version for the Mac. On January 27, 2010, Apple announced a new version of Keynote for iPad with an all new touch interface.

History

Keynote began as a computer program for Apple CEO Steve Jobs to use in creating the presentations for Macworld Conference and Expo and other Apple keynote events. Prior to using Keynote, Jobs had used Concurrence, from Lighthouse Design, a similar product which ran on the NeXTSTEP and OpenStep platforms.

The program was first sold publicly as Keynote 1.0 in 2003, competing against existing presentation software, most notably Microsoft PowerPoint.

In 2005 Apple began selling Keynote 2.0 in conjunction with Pages, a new word processing and page layout application, in a software package called iWork. At the Macworld Conference & Expo 2006, Apple released iWork '06 with updated versions of Keynote 3.0 and Pages 2.0. In addition to official HD compatibility, Keynote 3 added new features, including group scaling, 3D charts, multi-column text boxes, auto bullets in any text field, image adjustments, and free form masking tools. In addition, Keynote features three-dimensional transitions, such as a rotating cube or a simple flip of the slide.

Database index

A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time a database table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records.

An index is a copy of select columns of data from a table that can be searched very efficiently that also includes a low-level disk block address or direct link to the complete row of data it was copied from. Some databases extend the power of indexing by letting developers create indices on functions or expressions. For example, an index could be created on upper(last_name), which would only store the upper case versions of the last_name field in the index. Another option sometimes supported is the use of partial indices, where index entries are created only for those records that satisfy some conditional expression. A further aspect of flexibility is to permit indexing on user-defined functions, as well as expressions formed from an assortment of built-in functions.

Key (music)

In music theory, the key of a piece is the tonic note and chord that provides a subjective sense of arrival and rest. Other notes and chords in the piece create varying degrees of tension, resolved when the tonic note or chord returns. The key may be major or minor, although major is assumed in a phrase like "this piece is in C." Popular songs are usually in a key, and so is classical music during the common practice period, about 1650–1900. Longer pieces in the classical repertoire may have sections in contrasting keys.

Methods that establish the key for a particular piece can be complicated to explain, and vary over music history. However, the chords most often used in a piece in a particular key are those that contain the notes in the corresponding scale, and conventional progressions of these chords, particularly cadences, orient the listener around the tonic.

The key signature is not a reliable guide to the key of a written piece. It does not discriminate between a major key and its relative minor; the piece may modulate to a different key; if the modulation is brief, it may not involve a change of key signature, being indicated instead with accidentals. Occasionally, a piece in a mode such as Mixolydian or Dorian is written with a major or minor key signature appropriate to the tonic, and accidentals throughout the piece.