Athlon 64 X2The Athlon 64 X2 is the first native dual-core desktop central processing unit (CPU) designed by Advanced Micro Devices (AMD). It was designed from scratch as native dual-core by using an already multi-CPU enabled Athlon 64, joining it with another functional core on one die, and connecting both via a shared dual-channel memory controller/north bridge and additional control logic. The initial versions are based on the E stepping model of the Athlon 64 and, depending on the model, have either 512 or 1024 KB of L2 cache per core.
Limit inferior and limit superiorIn mathematics, the limit inferior and limit superior of a sequence can be thought of as limiting (that is, eventual and extreme) bounds on the sequence. They can be thought of in a similar fashion for a function (see limit of a function). For a set, they are the infimum and supremum of the set's limit points, respectively. In general, when there are multiple objects around which a sequence, function, or set accumulates, the inferior and superior limits extract the smallest and largest of them; the type of object and the measure of size is context-dependent, but the notion of extreme limits is invariant.
Edmund LandauEdmund Georg Hermann Landau (14 February 1877 – 19 February 1938) was a German mathematician who worked in the fields of number theory and complex analysis. Edmund Landau was born to a Jewish family in Berlin. His father was Leopold Landau, a gynecologist, and his mother was Johanna Jacoby. Landau studied mathematics at the University of Berlin, receiving his doctorate in 1899 and his habilitation (the post-doctoral qualification required to teach in German universities) in 1901. His doctoral thesis was 14 pages long.
Georg ScheffersGeorg Scheffers (21 November 1866 – 12 August 1945) was a German mathematician specializing in differential geometry. Scheffers was born on 21 November 1866 in the village of Altendorf near Holzminden (today incorporated into Holzminden). Scheffers began his university career at the University of Leipzig where he studied with Felix Klein and Sophus Lie. Scheffers was a coauthor with Lie for three of the earliest expressions of Lie theory: Lectures on Differential equations with known Infinitesimal transformations (1893), Lectures on Continuous groups (1893), and Geometry of Contact Transformations (1896).
Emanuel CzuberEmanuel Czuber (Prague, 19 January 1851 – Gnigl, 22 August 1925) was an Austrian mathematician. He graduated from a German secondary school (Realschule) in 1869 and continued his studies at the German Technical University in Prague, where he played an active part in the Association for Free Lectures on Mathematics - a student association and the predecessor of the Union of Czech Mathematicians and Physicists. From 1872 to 1874, while he was still a student, he acted as an assistant to Karel Koristka.
Quaternary ammonium cationIn chemistry, quaternary ammonium cations, also known as quats, are positively-charged polyatomic ions of the structure , where R is an alkyl group, an aryl group or organyl group. Unlike the ammonium ion () and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged, independent of the pH of their solution. Quaternary ammonium salts or quaternary ammonium compounds (called quaternary amines in oilfield parlance) are salts of quaternary ammonium cations.
