Directionality of general beams

General Physics I. Molecular Beams

1. Introduction Since the first measurements of the velocity distribution of atoms evaporating from the surface of bulk liquid helium by Johnston and King, several theories have been advanced to explain the helium evaporation process. In these theories, the excita-tions in liquid He II, phonons and rotons, play an important role in the evaporation mechanism. In this report, we discuss an experi...

General Directionality and the Local Behavior of Argumentation Semantics

In abstract argumentation, the directionality principle conveys the intuition that, for an unattacked set, the choice of arguments that are part of an extension should only depend on the restriction of the framework to that set. Furthermore, having made such a choice, one should be able to select arguments from the rest of the framework so as to get an extension. In this paper we show how this ...

Decoupling of coherent Gaussian beams with general astigmatism.

We show how to decouple a coherent Gaussian beam having general astigmatism (to transform it into a beam having only simple astigmatism, or orthogonal symmetry) by using a single rotated thin cylindrical lens. The resulting coherent orthogonal Gaussian beam may be further transformed into a stigmatic (rotationally symmetric) Gaussian beam by an orthogonal telescopic magnifier. The initial beam ...

Conflicting Directionality

Directionality of kinesin motors.

Kinesins are molecular motors that transport various cargoes along microtubule tracks using energy derived from ATP hydrolysis. Although the motor domains of kinesins are structurally similar, the family contains members that move on microtubules in opposite directions. Recent biochemical and biophysical studies of several kinesins make it possible to identify structural elements responsible fo...