ABSTRACT
The characteristic dimensions of Bessel beams are fully determined by the corresponding Bessel functions. We consider a way of obtaining a narrower diameter of the central core of a diffractive pattern generated by the Bessel beams. The method relies on superposition of two or more Bessel beams with appropriately chosen amplitudes and widths. The disturbing influence of the aperture's edges can be eliminated by addition of the proper amplitude filter.
ABSTRACT
An exact analysis of the excess noise in a two-mirror laser that takes into account the intracavity elements and the position of the active medium is presented. The influence of the active medium's position and length of the laser cavity on the excess noise factor is shown.
ABSTRACT
The focusing of Gaussian beams is described in terms of complex rays, and a simple example is given for the case of reflection from a mirror.
ABSTRACT
In two separate studies, episodic semantic (verbal) and figural-memory abilities as measured by the Wechsler Memory Scale (Russell Method) are compared in middle-aged detoxified male alcoholics and controls. Both studies gave rise to similar findings. Alcoholics recalled significantly less verbal and figural material at both immediate recall and 30-min delayed recall than did the controls. Contrary to expectation, compared to controls, alcoholics did not have a greater differential deficit for the figural material as compared with the verbal or a greater differential deficit on delayed than on immediate memory. The percentage of material recalled at the delayed testing, when taken as a function of the amount of material recalled immediately, did not differ for the two groups on the semantic or figural tasks in either study. Thus, rates of forgetting were equivalent in alcoholics and controls suggesting that the alcoholics' deficit lies in the initial acquisition process. Whether that deficit is in encoding or initial retrieval processes remains to be investigated. Implications for future research are given.
