A Symmetry Adapted Approach to Molecular Spectroscopy: The Anharmonic Oscillator Symmetry Model

We apply the Anharmonic Oscillator Symmetry Model to the description of vibrational excitations in ${\cal D}_{3h}$ and ${\cal T}_d$ molecules. A systematic procedure can be used to establish the relation between the algebraic and configuration space formulations, by means of which new interactions are found in the algebraic model, leading to reliable spectroscopic predictions. We illustrate the method for the case of ${\cal D}_{3h}$-triatomic molecules and the ${\cal T}_d$ Be-cluster.Comment: 12 pages, invited talk at XIX Oaxtepec Symposium on Nuclear Physics, January 199

The convex point of continuity property in Banach spaces not containing ℓ1

AbstractWe obtain a local characterization of the convex point of continuity property for every closed, bounded and convex subset not containing sequences equivalent to the standard unit basis of ℓ1. As a consequence, we prove, in the setting of Banach spaces without ℓ1-copies, that the convex point of continuity property is determined on subspaces with a Schauder basis, which is a partial answer to a well-known problem

Biogeographical characterization of Trichodoridae in the Iberian Peninsula

The existence of two faunistic groups has been found on analysis of the distribution patterns of the 18 species from the family Trichodoridae that have been found in representative crops and environments of the Iberian Peninsula. The first one represented by the autochthonous species, Paratrichodorus hispanus, Trichodorus azorensis, T. beirensis, T. giennensis and T. lusitanicus, is present in uncultivated and cultivated areas; T. azorensis, T. beirensis and T. giennensis have been found very localised, while P. hispanus is widespread in Spain and Northern Portugal and T. lusitanicus is common mainly in southern but also found in central Portugal. The second one is defined by the plant parasitic and virus vector species, P. minor, P. pachydermus, P. teres, T. primitivus, T. sparsus and T. viruliferus, in which P. anemones and T. similis could also be included, in spite of their very localised presence. Paratrichodorus anemones, P. pachydermus, T. similis and T. viruliferus could be regarded as characteristic species from temperate environments, while P. minor, the most widespread species in subtropical crops, has also been found in the Canary and Madeira Islands. On the other hand, P. teres, T. giennensis, T. similis, T. sparsus and T. viruliferus have only been found in Spain, while P. acutus, P. allius, P. nanus, P. porosus, T. azorensis and T. orientalis appeared very localised only in Portugal, P. acutus, P. porosus and T. azorensis appearing only in the Azores and Madeira Archipelagos. Climatic, vegetation and soil type influence are discussed.Fundação para a Ciência e a Tecnologia (FCT)CBMA, U

RNA-DNA strand exchange by the Drosophila Polycomb complex PRC2.

Polycomb Group (PcG) proteins form memory of transient transcriptional repression that is necessary for development. In Drosophila, DNA elements termed Polycomb Response Elements (PREs) recruit PcG proteins. How PcG activities are targeted to PREs to maintain repressed states only in appropriate developmental contexts has been difficult to elucidate. PcG complexes modify chromatin, but also interact with both RNA and DNA, and RNA is implicated in PcG targeting and function. Here we show that R-loops form at many PREs in Drosophila embryos, and correlate with repressive states. In vitro, both PRC1 and PRC2 can recognize R-loops and open DNA bubbles. Unexpectedly, we find that PRC2 drives formation of RNA-DNA hybrids, the key component of R-loops, from RNA and dsDNA. Our results identify R-loop formation as a feature of Drosophila PREs that can be recognized by PcG complexes, and RNA-DNA strand exchange as a PRC2 activity that could contribute to R-loop formation