Isotope

Isotopes are variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. The number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number.

For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that the neutron numbers of these isotopes are 6, 7 and 8 respectively.

Isotope (band)

Isotope was a British jazz-rock band fronted by guitarist Gary Boyle.

Boyle founded the band in June 1972 and a first album, Isotope, was largely composed by keyboardist Brian Miller. Jeff Clyne played bass and Nigel Morris played drums. Clyne and Miller left in 1974, however, and were replaced by Hugh Hopper and Laurence Scott (b. 7 Feb 1946) respectively. After touring, this new line-up recorded the band's second album Illusion. In late 1974 the band appeared on film on BBC 2's The Old Grey Whistle Test playing "Spanish Sun" from the album.

Further touring followed and there were various personnel changes. Deep End was recorded in 1976 with two keyboardists Zoe Kronberger and Frank Roberts. Hopper played on one track, but the bass was otherwise played by Dan K. Brown. Morris Pert also played percussion.

Boyle subsequently focused on a solo career.

Discography

Isohedral figure

In geometry, a polytope of dimension 3 (a polyhedron) or higher is isohedral or face-transitive when all its faces are the same. More specifically, all faces must be not merely congruent but must be transitive, i.e. must lie within the same symmetry orbit. In other words, for any faces A and B, there must be a symmetry of the entire solid by rotations and reflections that maps A onto B. For this reason, convex isohedral polyhedra are the shapes that will make fair dice.

Isohedral polyhedra are called isohedra. They can be described by their face configuration. A form that is isohedral and has regular vertices is also edge-transitive (isotoxal) and is said to be a quasiregular dual: some theorists regard these figures as truly quasiregular because they share the same symmetries, but this is not generally accepted.

A polyhedron which is isohedral has a dual polyhedron that is vertex-transitive (isogonal). The Catalan solids, the bipyramids and the trapezohedra are all isohedral. They are the duals of the isogonal Archimedean solids, prisms and antiprisms, respectively. The Platonic solids, which are either self-dual or dual with another Platonic solid, are vertex, edge, and face-transitive (isogonal, isotoxal, and isohedral). A polyhedron which is isohedral and isogonal is said to be noble.

Greeks (finance)

In mathematical finance, the Greeks are the quantities representing the sensitivity of the price of derivatives such as options to a change in underlying parameters on which the value of an instrument or portfolio of financial instruments is dependent. The name is used because the most common of these sensitivities are denoted by Greek letters (as are some other finance measures). Collectively these have also been called the risk sensitivities,risk measures or hedge parameters.

Use of the Greeks

The Greeks are vital tools in risk management. Each Greek measures the sensitivity of the value of a portfolio to a small change in a given underlying parameter, so that component risks may be treated in isolation, and the portfolio rebalanced accordingly to achieve a desired exposure; see for example delta hedging.

The Greeks in the Black–Scholes model are relatively easy to calculate, a desirable property of financial models, and are very useful for derivatives traders, especially those who seek to hedge their portfolios from adverse changes in market conditions. For this reason, those Greeks which are particularly useful for hedging—such as delta, theta, and vega—are well-defined for measuring changes in Price, Time and Volatility. Although rho is a primary input into the Black–Scholes model, the overall impact on the value of an option corresponding to changes in the risk-free interest rate is generally insignificant and therefore higher-order derivatives involving the risk-free interest rate are not common.

Gamma (store)

Gamma is a Dutch Hardware store-chain. It started in May 11, 1978 in Breda. The headquarters of the franchise-organisation Intergamma is located in Leusden and as of 2011 it has 245 stores, of which 164 are located in the Netherlands and 81 in Belgium. Intergamma also owns the Hardware store-chain Karwei.

History

In 2008 Gamma had a revenue of 606 million euro.

Gamma commercials have been broadcast in the Netherlands on radio and television since 1994, and have made the actors John Buijsman and Martin van Waardenberg well known in the Netherlands. In Flanders Luk Wyns is the face of the company.

External links

References

Gamma (disambiguation)

Gamma is the third letter of the Greek alphabet.

Gamma may also refer to:

Science and mathematics

General

Lower case, γ