Showing papers by "University of Valencia published in 1980"

A Bayesian analysis of classical hypothesis testing

Abstract: The procedure of maximizing the missing information is applied to derive reference posterior probabilities for null hypotheses. The results shed further light on Lindley’s paradox and suggest that a Bayesian interpretation of classical hypothesis testing is possible by providing a one-to-one approximate relationship between significance levels and posterior probabilities.

A Perspective on Aging in Rotifers

Abstract: Most research on aging in rotifers has been performed with populations, not with individuals. As a consequence, the dependent variable in these studies is usually either mean lifespan or rate of survivorship. After a brief consideration of the literature published since the last major review (King, 1969), the results of a series of experiments are presented. Males and females of three genetically distinct clones of Brachionus plicatilis were used for a factorial life table analysis at three different temperatures. The results of these experiments indicate several potential problems in using populations to study the aging process of individuals. These problems derive from the fact that lifespan is only one component of fitness, and its relative duration may not reflect the evolutionary success of the clone. That is, lifespan is free to vary in response to both stochastic and deterministic events without significantly reducing fitness. Under these conditions, neither mean lifespan nor pattern of survivorship will provide meaningful data on the determinants of individual senescence.

Ultrastructure of one Ewing's sarcoma of bone with endothelial character and a comparative review of the vessels in 27 cases of typical Ewing's sarcoma.

Abstract: An atypical variant of Ewing's sarcoma, located in the left hip of a nine-year-old girl, is discussed at optical, histochemical and electron microscopical level. The endothelial appearing cells seem to play a main role in its histogenesis. Tumoral cells of an undifferentiated blastemic nature show round nuclei and bright lucent cytoplasm, being organized in solid sheets or vascular-like profiles. Alkaline and acid phosphatases are very prominent in all tumoral cells, and some of them also show PAS positive material. Its ultrastructure demonstrates an active pinocytic capacity, cytoplasmic filaments and Weibel-Palade bodies. Simultaneously a review is performed on 27 cases of typical Ewing's sarcoma of bone in order to compare its vessels of a reactive nature with this tumor. A differential diagnosis with hemangioendothelioma primary to bone is established.

Regulation of chitin synthase activity inSaccharomyces cerevisiae: Effect of the inhibition of cell division and of synthesis of RNA and protein

Abstract: The effect of pronase and trypsin on the activation or deactivation (degradation?) of chitin synthase ofSaccharomyces cerevisiae occurs faster in membranous preparations than in toluene-treated cells When the temperature is raised, the former preparation is deactivated earlier than the latter one The activity found in growing cells is not modified after inhibition of protein synthesis by cycloheximide or amino acid starvation or by the inhibition of RNA synthesis It was possible to activate the chitin synthase ofS cerevisiae cdc 25 grown at 23°C by means of pronase, whereas trypsin had no effect After the cells were grown at 37°C, chitin synthase could not be activated either with trypsin or with pronase This effect occurred independently of protein synthesis but did not take place when the cells were toluenized prior to the transfer at 37°C These results suggest that the low catalytic levels and stability of the chitin synthase found in actively growing cells ofS cerevisiae may be due to the restrictions introduced in the system by its membrane location

Polymer Retention Mechanism in GPC on Active Gels

Abstract: The elution behaviour of low molecular weight polystyrene (PS) down to the monomer on spherosil gel in several eluents has been studied. In the medium range of molecular weights the elution behaviour is similar to that followed by high molecular weight PS, the differences in elution volumes among different eluents increasing monotonically with decreasing molecular weight and partition rather than adsorption probably being responsible for the shifts in retention volumes. However, at the total permeation limit, the situation is alike to that found in liquid-solid chromatography, the elution volumes of solutes with molecular sizes very close to that of styrene being determined by solvent strength (∊) and solute solubility (δ) parameters. Hydrogen bonding seems to be the main contribution to substrate-solute interactions in this case.

Two-photon exchange in muon-nuclear scattering

Abstract: We obtain a low-momentum-transfer theorem for positive- and negative-muon--nuclear scattering, in terms of the charge and the electric and magnetic polarizabilities. The result opens the way to use muons as a tool to probe the electromagnetic structure of composite objects. Predictions of this two-photon effect for the asymmetry in the angular distribution of negative and positive muons scattered by /sup 4/He are given.

Two-particle correlations in 400 GeV proton-nucleus interactions

Abstract: Two-particle inclusive correlations are studied by means of the two-particle rapidity correlation function. The data for the analysis come from an exposure of emulsion plates to a 400 GeV proton beam at FNAL. Predominant short-range correlations among shower particles are found, but this does not allow to exclude some long-range correlation behaviour, in agreement with the results obtained in lower-energy experiments.