Locks

Locks are advisory locks, where each thread cooperates by acquiring the lock before accessing the equivalent data. Some systems also implement mandatory locks, where attempting unauthorized access to a locked resource will force exclusion in the entity attempting to make the access.

In terms of access to the data, no difference is made between shared or exclusive modes. Other schemes provide for a shared mode, where several threads can obtain a shared lock for read-only access to the data. Other modes such as exclusive, intend-to-exclude and intend-to-upgrade are also widely implemented.

Independent of the type of lock chosen above, locks can be confidential by what happens when the lock strategy prevents progress of a thread. Most locking designs block the finishing of the process requesting the lock until it is allowed to access the locked resource. A spin lock is a lock where the thread simply waits until the lock becomes accessible. It is very efficient if threads are only likely to be uncreative for a short period of time, as it avoids the overhead of operating system process re-scheduling. It is wasteful if the padlock is held for a long period of time.

Color

Color is the visual perceptual possessions corresponding in humans to the categories called red, yellow, white, etc. Color derives from spectrum of light distribution of light energy versus wavelength interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical condition of color are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra.

Typically, only features of the composition of light that are visible by humans wavelength spectrum from 400 nm to 700 nm, roughly are included, thereby objectively relating the psychological phenomenon of color to its physical specification. Because perception of color stems from the varying sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantify by the degree to which they stimulate these cells. These physical or physiological quantifications of color, however, do not fully clarify the psychophysical perception of color appearance.

The science of color is sometimes called chromatics. It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic emission in the visible range that is, what we commonly refer to simply as light.

Television

It is a widely used telecommunication system for broadcasting and getting moving pictures and sound over a distance. The expression television may also be used to refer specifically to a television set, programming or television transmission. The word is consequent from mixed Latin and Greek roots, meaning far sight. Since it first became commercially available from the late 1940s, the television set has become a general household communications device in homes and institutions, particularly in the first world, as a source of entertainment and news. Since the 1970s, video recordings on VCR tapes and later, digital playback systems such as DVDs, have enabled the television to be used to view recorded cinema and other programs.

A television system may be made up of multiple components, so a screen which lacks an internal tuner to accept the broadcast signals is called a monitor rather than a television. A television may be built to receive different broadcast or video formats, such as High-Definition television (HDTV).In sociology and biology a population is the collection of people or organisms of a particular species living in a given geographic area or space, usually precise by a census.