Showing papers by "University of Lisbon published in 1976"

Present, predicted, and hidden probabilities

Abstract: The general properties of measurements in microphysics are studied and the three types of probabilities that, according to the authors, appear in wave mechanics are set up. Such a distinction, together with the principle of the localization of the corpuscle as was laid down at the very introduction of the theory of the double solution, provides a good grasp of certain phenomena whose explanation according to the usual theory (which makes no use of permanent localization and where the three types of probabilities are intermingled) leads to paradoxical or self-contradictory situations.

Polarization Effects in DWBA Calculations

Abstract: For more than two decades the distorted wave Born approximation (DWBA) has been a very useful model for the study of direct reaction phenomena. It enables us to understand much of the physics of a direct reaction and is a glopd starting point for the investigation of higher order processes 1). The DWBA has had considerable success in the description of polarization data in transfer and charge exchange reactions where the first order process is dominant. In particular it is of great value to make2gpin assignments using, for instance, deuteron stripping reactions 2). On the other hand the time seems to be coming where the reliability of DWBA calculations is sufficient to extract information on the detailed structure of light ions used as projectiles in transfer reactions. This type of study is likely to be promising in the future and may eventually be extended to polarization phenomena in heavy ion induced reactions.

Fluorographic Aspects of Stargardt’s Disease (Juvenile Familial Macular Degeneration)

Abstract: There have been several studies and reports since Stargardt’s initial description in 1909 of this familial atrophie form of macular involvement of pigment epithelium. This retinal disorder of early onset (first and second decade) can be included in a wider group of diseases known as fundus flavimaculatus,term applied to a variety of related disorders by FRANCE-SCHETTI (1963, 1965) to describe the multiple yellow-white round or linear fishtail-like lesions affecting mainly the posterior fundus. It can occur with and without macular involvement. With the easy availability of new methods of investigation mainly the experimental studies, electron microscopy, electrophysiology, monochromatic photography and specially fluor-escein angiography, there has been increasing awareness in recent years of the role of retinal pigment epithelium (RPE) in the causation of many disease formerly thought to be localized to the sensory retina. Fluorescein angiography is a good technique known to demonstrate pigment epithelial abnormalities otherwise not visible. Such studies have been carried out, both in the localized (macular) as well as in the generalized form of fundus flavimaculatus(Ernest & Krill 1966; KRILL, NEWELL & CHISTTI 1968; Gass 1970 and others).

Mean square invariant forecasters for the weibull distribution

Abstract: : Given n initial observations constituting a sequence drawn from a set X1, ... , Xn, of n independent and identically distributed random variables with the Weibull distribution (known shape parameter), a mean square invariant forecaster has been found for the expected minimum (maximum) of a subsequent sequence of the next m observations. When the location parameter instead of the shape parameter is known, reduction to the Gumbel distribution is immediate and the same technique again gives an invariant forecaster. The formulae, although amenable to computation, are cumbersome.