Hydrogen line

The hydrogen line, 21 centimetre line or HI line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1420.405751786 MHz, which is equivalent to the vacuum wavelength of 21.10611405413 cm in free space. This wavelength falls within the microwave radio region of the electromagnetic spectrum, and it is observed frequently in radio astronomy, since those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light.

The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen 1s ground state that have an energy difference of 5.87433 µeV. The frequency, ν, of the quanta that are emitted by this transition between two different energy levels is given by the Planck-Einstein relation The constant of proportionality, h, is known as the Planck constant.

GeForce 700 series

The GeForce 700 Series is a family of graphics processing units developed by Nvidia, used in desktop and laptop PCs. It is mainly based on a refresh of the Kepler microarchitecture (GK-codenamed chips) used in the previous GeForce 600 Series, but also includes cards based on the previous Fermi (GF) and later Maxwell (GM) architectures. A number of GeForce 700 series chips were released for mobile devices in April 2013. GeForce 700 series cards were first released in May 2013, starting with the release of the GeForce GTX Titan on February 19, 2013, and the GeForce GTX 780 on May 23, 2013.

Overview

GK110 has been designed and is being marketed with computational performance in mind. It contains 7.1 billion transistors. This model also attempts to maximise energy efficiency through the execution of as many tasks as possible in parallel according to the capabilities of its streaming processors.

With GK110, increases in memory space and bandwidth for both the register file and the L2 cache over previous models, are seen. At the SMX level, GK110's register file space has increased to 256KB composed of 65K 32bit registers, as compared to Fermi's 33K 32bit registers totaling 128 KB. As for the L2 cache, GK110 L2 cache space increased by up to 1.5MB, 2x as big as GF110. Both the L2 cache and register file bandwidth have also doubled. Performance in register-starved scenarios is also improved as there are more registers available to each thread. This goes in hand with an increase of total number of registers each thread can address, moving from 63 registers per thread to 255 registers per thread with GK110.

Ohio State University Radio Observatory

The Ohio State University Radio Observatory was a Kraus-type radio telescope located on the grounds of the Perkins Observatory at Ohio Wesleyan University from 1963 to 1998. Known as "Big Ear", the observatory was part of The Ohio State University's Search for Extraterrestrial Intelligence (SETI) project. Construction of the Big Ear began in 1956 and was completed in 1961, and it was finally turned on for the first time in 1963.

The observatory completed the Ohio Sky Survey in 1971, and from 1973–1995, Big Ear was used to search for extraterrestrial radio signals, making it the longest running SETI project in history. In 1977, the Big Ear received the noted Wow! signal. The observatory was disassembled in 1998 when developers purchased the site from the university and used the land to expand a nearby golf course. The design of the observatory is named after American physicist John D. Kraus (1910–2004), and is also used as the basis for the Nançay Radio Telescope.

GeForce

GeForce is a brand of graphics processing units (GPUs) designed by Nvidia. As of 2013, there have been twelve iterations of the design. The first GeForce products were discrete GPUs designed for add-on graphics boards, intended for the high-margin PC gaming market, and later diversification of the product line covered all tiers of the PC graphics market, ranging from cost-sensitive GPUs integrated on motherboards, to mainstream add-in retail boards. Most recently, GeForce technology has been introduced into Nvidia's line of embedded application processors, designed for electronic handhelds and mobile handsets.

With respect to discrete GPUs, found in add-in graphics-boards, Nvidia's GeForce and AMD's Radeon GPUs are the only remaining competitors in the high-end market. Along with its nearest competitor, the AMD Radeon, the GeForce architecture is moving toward GPGPU (General Purpose-Graphics Processor Unit). GPGPU is expected to expand GPU functionality beyond the traditional rasterization of 3D graphics, to turn it into a high-performance computing device able to execute arbitrary programming code in the same way a CPU does, but with different strengths (highly parallel execution of straightforward calculations) and weaknesses (worse performance for complex decision-making code).

GeForce 200 series

The GeForce 200 Series is the 10th generation of Nvidia's GeForce graphics processing units, still based on the Tesla (microarchitecture) (GT-codenamed chips), named after the inventor and physicist Nikola Tesla.

Architecture

The GeForce 200 Series introduces Nvidia's second generation of Tesla (microarchitecture), Nvidia's unified shader architecture; the first major update to it since introduced with the GeForce 8 Series.

The GeForce GTX 280 and GTX 260 are based on the same processor core. During the manufacturing process, GTX chips are binned and separated through defect testing of the core's logic functionality. Those that fail to meet the GTX 280 hardware specification are re-tested and binned as GTX 260 (which is specified with fewer stream processors, less ROPs and a narrower memory bus).

In late 2008, Nvidia re-released the GTX 260 with 216 stream processors, up from 192. Effectively, there were two GTX 260 cards in production with non-trivial performance differences.