The expression 4Pi may refer to:
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*
* 4×π = 12.56637..., the
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4Pi-Mikroskop — Schema eines 4Pi Mikroskops. Ein 4Pi Mikroskop ist eine Variante des Konfokalmikroskops, das eine höhere Auflösung besitzt als die bei normalen konfokalen Mikroskopen übliche Auflösung von etwa 200 nm in seitlicher und 500–700 nm in… … Deutsch Wikipedia
4Pi Microscope — A 4Pi microscope is a confocal microscope with two opposing lenses. It is used for high resolution imaging of fluorescence. It can be operated in three different ways:In a 4Pi microscope of type A, the coherent superposition of excitation light… … Wikipedia
4Pi STED microscopy — The 4Pi STED microscope is the result of combining the two unrelated concepts of STED and 4Pi microscopy. Here, the fluorescent sample is placed in the common focus of two opposing lenses, but excitation and detection are performed through a… … Wikipedia
4pi Systeme - Gesellschaft für Astronomie und Informationstechnologie mbH — Eine der Sonneberger Beobachtungskuppeln (um 1935) Die Sternwarte Sonneberg befindet sich auf dem Bergrücken des Erbisbühl in Neufang, dem mit 638 m über NN höchsten Punkt des bebauten Stadtgebietes von Sonneberg. Sie wurde Mitte der 1920er Jahre … Deutsch Wikipedia
Spherical multipole moments — are the coefficients in a series expansionof a potential that varies inversely with the distance R to a source, i.e., as frac{1}{R}. Examples of such potentials are the electric potential, the magnetic potential and the gravitational… … Wikipedia
Wallis product — In mathematics, Wallis product for pi;, written down in 1655 by John Wallis, states that: prod {n=1}^{infty} frac{(2n)(2n)}{(2n 1)(2n+1)} = frac{2}{1} cdot frac{2}{3} cdot frac{4}{3} cdot frac{4}{5} cdot frac{6}{5} cdot frac{6}{7} cdot frac{8}{7} … Wikipedia
Solid harmonics — In physics and mathematics, the solid harmonics are solutions of the Laplace equation in spherical polar coordinates. There are two kinds: the regular solid harmonics R^m ell(mathbf{r}), which vanish at the origin and the irregular solid… … Wikipedia
Cremer C — Christoph Cremer aus Freiburg im Breisgau ist ein deutscher Physiker und Professor an der Ruprecht Karls Universität Heidelberg, der die konventionelle lichtoptische Auflösungsgrenze („Abbe Limit“) durch unterschiedliche Methoden überwunden hat… … Deutsch Wikipedia
Christoph Cremer — (born in Freiburg im Breisgau, Germany) is a German physicist and professor at the Ruprecht Karls University Heidelberg, who has successfully overcome the conventional limit of resolution that applies to light based investigations (the Abbe… … Wikipedia
Gauss' law for gravity — In physics, Gauss law for gravity, also known as Gauss flux theorem for gravity, is a law of physics which is essentially equivalent to Newton s law of universal gravitation. Its form is mathematically similar to Gauss law for electricity; in… … Wikipedia
