Tuesday, July 29, 2008

Locative media

Locative Media are media of communication bound to a location. They are digital media applied to real places and thus triggering real social interactions. While mobile technologies such as the Global Positioning System (GPS), laptop computers and mobile phones enable locative media, they are not the goal for the development of projects in this field. Rather:

"Locative media is many things: A new site for old discussions about the relationship of consciousness to place and other people. A framework within which to actively engage with, critique, and shape a rapid set of technological developments. A context within which to explore new and old models of communication, community and exchange. A name for the ambiguous shape of a rapidly deploying surveillance and control infrastructure." (Russell, 2004)

Monday, July 21, 2008

Relational model

The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar Codd.

Its core idea is to describe a database as a collection of predicates over a finite set of predicate variables, describing constraints on the possible values and combinations of values. The content of the database at any given time is a finite model (logic) of the database, i.e. a set of relations, one per predicate variable, such that all predicates are satisfied. A request for information from the database (a database query) is also a predicate.

The purpose of the relational model is to provide a declarative method for specifying data and queries: we directly state what information the database contains and what information we want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for getting queries answered.

Monday, July 14, 2008

Multidimensional database

Multidimensional databases are variously (depending on the context) data aggregators which combine data from a multitude of data sources; databases which offer networks, hierarchies, arrays and other data formats difficult to model in SQL; or databases which give a high degree of flexibility in the definition of dimensions, units, and unit relationships, regardless of data format.

Multi-dimensional databases are especially useful in sales and marketing applications that involve time series. Large volumes of sales and inventory data can be stored to ultimately be used for logistics and executive planning. For example, data can be more readily segregated by sales region, product, or time period.

While many of the major database vendors have recognized and implemented at least a partial solution, most frequently they rely upon a Star schema database design. However, the star design for relational databases can result in "sparse data," or sets of ordered data with large gaps between data entries. While modern database engines use strategies to limit the impact of sparse data sets on query performance, such as compressing large blocks of empty data elements for quicker access, star databases can still present worse performance than other alternatives.

Tuesday, July 08, 2008


In the thought of Vladimir Vernadsky and Teilhard de Chardin, the noosphere (sometimes spelled nöosphere) can be seen as the "sphere of human thought" being derived from the Greek νούς ("nous") meaning "mind" + σφαίρα (sfaira) meaning "sphere", in the style of "atmosphere" and "biosphere". In the original theory of Vernadsky, the noosphere is the third in a succession of phases of development of the Earth, after the geosphere (inanimate matter) and the biosphere (biological life). Just as the emergence of life fundamentally transformed the geosphere, the emergence of human cognition fundamentally transforms the biosphere. In contrast to the conceptions of the Gaia theorists, or the promoters of cyberspace, Vernadsky's noosphere emerges at the point where humankind, through the mastery of nuclear processes, begins to create resources through the transmutation of elements.

Wednesday, July 02, 2008

Transport Layer Security

The TLS protocol allows applications to communicate across a network in a way designed to prevent eavesdropping, tampering, and message forgery. TLS provides endpoint authentication and communications privacy over the Internet using cryptography. Typically, only the server is authenticated (i.e., its identity is ensured) while the client remains unauthenticated; this means that the end user (whether an individual or an application, such as a Web browser) can be sure with whom it is communicating. The next level of security — in which both ends of the "conversation" are sure with whom they are communicating — is known as mutual authentication. Mutual authentication requires public key infrastructure (PKI) deployment to clients unless TLS-PSK or the Secure Remote Password (SRP) protocol are used, which provide strong mutual authentication without needing to deploy a PKI.