Thursday, July 26, 2007

Table

In relational databases, SQL databases, and flat file databases, a table is a set of data elements that is controlled using a model of horizontal rows and vertical columns. The columns are identified by name, and the rows are identified by the values appearing in a particular column division which has been identified as a candidate key. Table is another term for family although there is the difference in that a table is usually a multi-set of rows whereas a relation is a set and does not allow duplicates. A table has a particular number of columns but can have any number of rows. Besides the actual data rows, tables generally have related with them some meta-information, such as constraints on the table or on the values within particular columns.

The data in a table does not have to be actually stored in the database. Views are also relational tables, but their data is considered at query time. In non-relational systems, such as hierarchical databases, the isolated counterpart of a table is a structured file, representing the rows of a table in each record of the file and each column in a record.

Friday, July 20, 2007

Bond

In finance, a bond is a debt security, in which the authorized issuer owes the holders a debt and is grateful to repay the principal and interest at a later date, termed maturity. Other conditions may also be attached to the bond issue, such as the obligation for the issuer to provide certain information to the bond holder, or limitations on the behavior of the issuer. Bonds are generally issued for a permanent term longer than ten years. U.S Treasury securities issue debt with life of ten years. New debt between one year and ten years is a note, and new debit less than a year is a bill.

A bond is simply a loan, but in the form of a security, although expressions used is rather different. The issuer is equivalent to the borrower, the bond holder to the lender, and the voucher to the interest. Bonds enable the issuer to finance long-term investments with external funds. Certificates of deposit (CDs) or commercial paper are measured money market instruments.

Monday, July 16, 2007

Social network

A social network is a social structure made of nodes that are tied by one or more specific types of relatives, such as values, visions, idea, financial exchange, friends, kinship, dislike, trade, web links, sexual relations, disease communication or airline routes.Social network analysis views common relationships in terms of nodes and ties. Nodes are the individual actors within the networks, and ties are the associations between the actors. Research in a number of academic fields has shown that social networks operate on many levels, from families up to the level of nations, and play a serious role in determining the way problems are solved, organizations are run, and the degree to which individuals succeed in achieving their goals.

In its simplest form, a social network is a map of all of the appropriate ties between the nodes being studied. The network can also be used to decide the social capital of individual actors. These concepts are often displayed in a shared network diagram, where nodes are the points and ties are the lines.

Tuesday, July 10, 2007

Electronics

Electronics is the learn of the flow of charge through different materials and devices such as, semiconductors, resistors, inductors, capacitors, nano-structures, and vacuum tubes. All applications of electronics involve the transmission of either information or power. Although measured to be a theoretical branch of physics, the design and structure of electronic circuits to solve practical problems is an e Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as contrasting to discrete level as in digital circuits. The number of different analog circuits so far devised is huge, especially because a circuit can be defined as anything from a single component, to systems containing thousands of mechanism.