Opera (web browser)

Opera is a web browser developed by Opera Software. The latest version is available for Microsoft Windows, OS X, and Linux operating systems, and uses the Blink layout engine. An earlier version using the Presto layout engine is still available, and additionally runs on FreeBSD systems.

Opera siblings – Opera Mobile, Opera Mini and Opera Coast – work on devices running Android, iOS, Windows Phone, Symbian, Maemo, Bada, BlackBerry and Windows Mobile operating systems, while Opera Mini runs on Java ME-capable devices.

According to Opera Software, the browser had more than 350 million users worldwide in the 4th quarter 2014. Total Opera mobile users reached 291 million in June 2015. Opera has been noted for originating many features later adopted by other web browsers. A prominent example is Speed Dial.

History

Opera began in 1994 as a research project at Telenor, the largest Norwegian telecommunications company. In 1995, it branched out into a separate company named Opera Software ASA. Opera was first released publicly with version 2.0 in 1996, which only ran on Microsoft Windows. In an attempt to capitalize on the emerging market for Internet-connected handheld devices, a project to port Opera to mobile device platforms was started in 1998. Opera 4.0, released in 2000, included a new cross-platform core that facilitated creation of editions of Opera for multiple operating systems and platforms.

Opera (Budapest Metro)

Opera is a station of the yellow M1 (Millennium Underground) line of the Budapest Metro, in front of the Hungarian State Opera House.

Connection

Opera (magazine)

Opera is a monthly British magazine devoted to covering all things related to opera. It contains reviews and articles about current opera productions internationally, as well as articles on opera recordings, opera singers, opera companies, opera directors, and opera books. The magazine also contains major features and analysis on individual operas and people associated with opera.

The magazine employs a network of international correspondents around the world who write for the magazine. Contributors to the magazine, past and present, include William Ashbrook, Martin Bernheimer, Julian Budden, Rodolfo Celletti, Alan Blyth, Elizabeth Forbes, and J.B. Steane among many others.

Opera is printed in A5 size, with colour photos, and consists of around 130 pages. Page numbering is consecutive for a complete year (e.g. September 2009 goes from p1033-1168). All issues since August 2006 are available online to current subscribers (through Exact Editions).

Based in London, the magazine was founded in 1950 by George Lascelles, 7th Earl of Harewood. It was launched at the house of Richard Buckle, under the imprint 'Ballet Publications Ltd'.

Index

An index is an indirect shortcut derived from and pointing into a greater volume of values, data, information or knowledge. Index may refer to:

Business

Publishing

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.

Index (statistics)

In statistics and research design, an index is a composite statistic – a measure of changes in a representative group of individual data points, or in other words, a compound measure that aggregates multiple indicators. Indexes summarize and rank specific observations.

Much data in the field of social sciences is represented in various indices such as Gender Gap Index, Human Development Index or the Dow Jones Industrial Average.

Item in indexes are usually weighted equally, unless there are some reasons against it (for example, if two items reflect essentially the same aspect of a variable, they could have a weight of 0.5 each).

Constructing the items involves four steps. First, items should be selected based on their face validity, unidimensionality, the degree of specificity in which a dimension is to be measured, and their amount of variance. Items should be empirically related to one another, which leads to the second step of examining their multivariate relationships. Third, indexes scores are designed, which involves determining their score ranges and weights for the items. Finally, indexes should be validateds, which involves testing whether they can predict indicators related to the measured variable not used in their construction.