Tuesday, February 27, 2007

Gemstone

A gemstone is prized particularly for great beauty or perfection so appearance is almost always the most significant attribute of gemstones. Characteristics that make a stone beautiful or attractive are colour, unusual optical phenomena within the stone, an exciting inclusion such as a fossil, rarity, and sometimes the form of the natural crystal. Diamond is prized very much as a gemstone since it is the hardest naturally occurring substance known and is able to reflect light with fire and sparkle when faceted. However, diamonds are far from rare with millions of carats mined each year.
Traditionally, general gemstones were classified into precious stones (cardinal gems) and semi-precious stones. The former class was largely determined by a history of ecclesiastical, devotional or ceremonial use and rarity. Only five types of gemstones were considered precious: diamond, ruby, sapphire, emerald, and amethyst. In current usage by gemologists, all gems are considered precious, although four of the five original "cardinal gems" (excluding the now-common amethyst) are typically—but not always—the most valuable.
Rare or unusual gemstones, usually meant to include those gemstones which occur so infrequently in gem quality that they are only just known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite and iolite.

Thursday, February 22, 2007

Manhattan

Manhattan refers to both the Island of Manhattan and encompasses most of the Borough of Manhattan, one of the five boroughs of New York City. The viable, financial, and cultural center of the city, Manhattan has many famous landmarks, tourist attractions, museums and universities. It is also home to the control center of the United Nations and the seat of city government.The borough of Manhattan is coterminous with New York County, which is also the most densely populated county in the United States. Postal addresses within the borough are typically chosen as "New York, NY."Manhattan has the biggest central business district in the
United States and is the site of most of the city's corporate headquarters and the New York Stock Exchange. Although its population is third biggest of the five boroughs, after Brooklyn and Queens, and it is geographically the smallest, Manhattan is the borough that many visitors most personally associate with New York City.

Sunday, February 18, 2007

Soul

In Hinduism, the Sanskrit words most strongly corresponding to soul are "Jiva", meaning the individual soul or qualities, and "Atman", which can also mean spirit or even God. The Atman is seen as the section of Brahman within us. Hinduism contains many variant beliefs on the source, purpose, and fate of the soul. For example, advaita or non-dualistic conception of the soul accords it union with Brahman, the complete uncreated (roughly, the Godhead), in eventuality or in pre-existing fact. Dvaita or dualistic concepts reject this, instead identifying the soul as a different and incompatible substance.
The Bhagavad Gita, one of the most major puranic scriptures, refers to the religious body or soul as Purusha (see also Sankhya philosophy). The Purusha is division and parcel of God, is unchanging (is never born and never dies), is indestructible, and, though basically indivisible, can be described as having three characteristics:
(i) Sat (reality or existence)
(ii) Chit (realization or knowledge)
(iii) Ananda (delight)

Friday, February 09, 2007

Infrared
Infrared (IR) emission is electromagnetic emission of a wavelength longer than that of noticeable light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of detectable light of longest wavelength. Infrared radiation spans three instructions of magnitude and has wavelengths between about 750 nm and 1 mm.
These divisions are suitable by the different human response to this radiation: near infrared is the area closest in wavelength to the radiation detectable by the human eye, mid and far infrared are gradually further from the visible regime. Other definitions follow different physical mechanisms (emission peaks, vs. bands, water absorption) and the newest follow technical reasons (The common silicon detectors are sensitive to about 1,050 nm, while Inga As sensitivity starts around 950 nm and ends between 1,700 and 2,600 nm, depending on the specific configuration). Unfortunately the international standards for these specifications are not currently obtainable.
The boundary between visible and infrared light is not precisely defined. The human eye is markedly less responsive to light above 700 nm wavelength, so longer frequencies make irrelevant contributions to scenes illuminated by common light sources. But particularly strong light (e.g., from lasers, or from bright daylight with the visible light removed by colored gels [1]) can be detected up to approximately 780 nm, and will be apparent as red light. The onset of infrared is defined (according to different standards) at different values typically between 700 nm and 780 nm.