A Topological Study of Contextuality and Modality in Quantum Mechanics

Kochen-Specker theorem rules out the non-contextual assignment of values to physical magnitudes. Here we enrich the usual orthomodular structure of quantum mechanical propositions with modal operators. This enlargement allows to refer consistently to actual and possible properties of the system. By means of a topological argument, more precisely in terms of the existence of sections of sheaves, we give an extended version of Kochen-Specker theorem over this new structure. This allows us to prove that contextuality remains a central feature even in the enriched propositional system.Comment: 10 pages, no figures, submitted to I. J. Th. Phy

GUP1 and its close homologue GUP2, encoding multi-membrane-spanning proteins involved in active glycerol uptake in Saccharomyces cerevisiae

Many yeast species can utilise glycerol, both as sole carbon source and as an osmolyte. In Saccharomyces cerevisiae, physiological studies have previously shown the presence of an active uptake system driven by electrogenic proton symport. We have used transposon mutagenesis to isolate mutants affected in the transport of glycerol into the cell. Here we present the identification of YGL084c, encoding a multi-membrane-spanning protein, as being essential for proton symport of glycerol into Saccharomyces cerevisiae. The gene is named GUP1 (Glycerol UPtake) and is important for growth on glycerol as carbon and energy source, as well as for osmotic protection by added glycerol, of a strain deficient in glycerol production. Another ORF, YPL189w, presenting a high degree of homology to YGL084c, similarly appears to be involved in active glycerol uptake in salt-containing glucose-based media in strains deficient in glycerol production. Analogously, this gene is named GUP2. To our knowledge, this is the first report on a gene product involved in active transport of glycerol in yeasts. Mutations with the same phenotypes occurred in two other open reading frames of previously unknown function, YDL074c and YPL180w.Comunidade Europeia (CE) - contract BIO4-CT95-0161

Chemical and sensory changes in frozen (-18 degrees C) wild sea bass (Dicentrarchus labrax) captured at different fishing seasons

WOS: 000247398700014Wild sea bass (Dicentrarchus labrax) captured from north eastern Mediterranean in autumn and winter were stored at -18 degrees C, and their chemical and sensory quality were investigated for up to 9 months. At the end of autumn storage period, pH, total volatile basic nitrogen, thiobarbituric acid values, free and bound formaldehyde, free formaldehyde and protein solubility were 6.69, 15.59 mg 100 g(-1), 0.086 mg MA kg(-1), 1.23 mg kg(-1), 3.58 mg kg(-1) and 15.72 g 100 g(-1), respectively. The same parameters for winter storage were 6.55, 12.08 mg 100 g(-1), 0.308 mg MA kg(-1), 3.38 mg kg(-1), 4.95 mg kg(-1) and 14.39 g 100 g(-1), respectively. None of the chemical quality parameters exceeded the acceptability limits. These results were supported by the results of sensory analyses (colour, odour, flavour, texture and overall acceptability). It was also concluded that differences in initial proximate composition and chemical quality scores of wild sea bass captured in autumn and winter did not have an effect on the chemical and sensory quality during frozen storage