Methylphenidate is a commonly prescribed psychostimulant and works by increasing the activity of the central nervous system. It produces such effects as increasing or maintaining alertness, combating fatigue, and improving attention. The short-term benefits and cost effectiveness of methylphenidate are well established.
(image copied from here). 1  Igneous Rocks: form by crystallizing melted material (magma). 2  They can form either on the surface (extrusive igneous rocks), or deep in the crust (intrusive or plutonic igneous rocks).
Igneous rocks are classed on the basis of where they form and the compostion of the molten rock. Igneous rocks form from molten rock which is either ejected at the surface of the earth or cools off underground.When volcanoes erupt, they can eject molten rock as shown in the following picture.This hot, thick lava flows down the side of the volcano and eventually cools.gneous rocks form from molten rock which is either ejected at the surface of the earth or cools off underground. When volcanoes erupt, they can eject molten rock as shown in the following picture.