489 research outputs found

    Potential energy surfaces for cluster emitting nuclei

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    Potential energy surfaces are calculated by using the most advanced asymmetric two-center shell model allowing to obtain shell and pairing corrections which are added to the Yukawa-plus-exponential model deformation energy. Shell effects are of crucial importance for experimental observation of spontaneous disintegration by heavy ion emission. Results for 222Ra, 232U, 236Pu and 242Cm illustrate the main ideas and show for the first time for a cluster emitter a potential barrier obtained by using the macroscopic-microscopic method.Comment: 10 pages, 21 figures, revtex

    Ecklonia Maxima Extract Effect in Tissue Regeneration of Symbionts at in Vivo Heteroplasmic Grafting of Some Tomatoes

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    The research was conducted to determine the Ecklonia maxima extract effect in the symbiont accretion at the in vivo heteroplasmic grafting of some tomatoes. E. maxima or sea bamboo is a seaweed used for obtaining of organic extracts used as stimulators in horticulture because consists the natural plant hormones such as auxins and cytokinins which have optimal role in cell division, important activity for tissue regeneration. The experimental variants were grafted plants, combinations between different symbionts, cultivar fragments from Lycopersicon esculentum specie. The symbionts were two scions, F1 hybrids, 'Siriana' (Romanian cultivar), 'Abellus' (Dutch cultivar) and two rootstocks, 'Buzău' variety (Romanian cultivar), 'Emperador' F1 hybrid (Dutch cultivar). The algae extract used had auxins (11 mg/L) and cytokinins (0.3 mg/L). Two treatments were applied before grafting on scion and rootstock, 1 mL/500 mL water and a treatment at grafting on soil, 5 mL/L water. Control variant was without hormone extract. Determinations, observations and interpretations of the algae effect were made on symbionts. The best results on tissue regeneration were obtained in plants treated with sea bamboo extract compared to untreated control plants. The E. maxima extract influenced the tissue regeneration

    Cystic fibrosis mice carrying the missense mutation G551D replicate human genotype phenotype correlations

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    We have generated a mouse carrying the human G551D mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a one-step gene targeting procedure. These mutant mice show cystic fibrosis pathology but have a reduced risk of fatal intestinal blockage compared with 'null' mutants, in keeping with the reduced incidence of meconium ileus in G551D patients. The G551D mutant mice show greatly reduced CFTR-related chloride transport, displaying activity intermediate between that of cftr(mlUNC) replacement ('null') and cftr(mlHGU) insertional (residual activity) mutants and equivalent to approximately 4% of wild-type CFTR activity. The long-term survival of these animals should provide an excellent model with which to study cystic fibrosis, and they illustrate the value of mouse models carrying relevant mutations for examining genotype-phenotype correlations

    Involvement of Plasmodium falciparum protein kinase CK2 in the chromatin assembly pathway

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    <p>Abstract</p> <p>Background</p> <p>Protein kinase CK2 is a pleiotropic serine/threonine protein kinase with hundreds of reported substrates, and plays an important role in a number of cellular processes. The cellular functions of <it>Plasmodium falciparum </it>CK2 (PfCK2) are unknown. The parasite's genome encodes one catalytic subunit, PfCK2α, which we have previously shown to be essential for completion of the asexual erythrocytic cycle, and two putative regulatory subunits, PfCK2β1 and PfCK2β2.</p> <p>Results</p> <p>We now show that the genes encoding both regulatory PfCK2 subunits (PfCK2β1 and PfCK2β2) cannot be disrupted. Using immunofluorescence and electron microscopy, we examined the intra-erythrocytic stages of transgenic parasite lines expressing hemagglutinin (HA)-tagged catalytic and regulatory subunits (HA-CK2α, HA-PfCK2β1 or HA-PfCK2β2), and localized all three subunits to both cytoplasmic and nuclear compartments of the parasite. The same transgenic parasite lines were used to purify PfCK2β1- and PfCK2β2-containing complexes, which were analyzed by mass spectrometry. The recovered proteins were unevenly distributed between various pathways, with a large proportion of components of the chromatin assembly pathway being present in both PfCK2β1 and PfCK2β2 precipitates, implicating PfCK2 in chromatin dynamics. We also found that chromatin-related substrates such as nucleosome assembly proteins (Naps), histones, and two members of the Alba family are phosphorylated by PfCK2α <it>in vitro</it>.</p> <p>Conclusions</p> <p>Our reverse-genetics data show that each of the two regulatory PfCK2 subunits is required for completion of the asexual erythrocytic cycle. Our interactome study points to an implication of PfCK2 in many cellular pathways, with chromatin dynamics being identified as a major process regulated by PfCK2. This study paves the way for a kinome-wide interactomics-based approach to elucidate protein kinase function in malaria parasites.</p

    Multiplet Effects in the Quasiparticle Band Structure of the f1f2f^1-f^2 Anderson Model

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    In this paper, we examine the mean field electronic structure of the f1f2f^1-f^2 Anderson lattice model in a slave boson approximation, which should be useful in understanding the physics of correlated metals with more than one f electron per site such as uranium-based heavy fermion superconductors. We find that the multiplet structure of the f2f^2 ion acts to quench the crystal field splitting in the quasiparticle electronic structure. This is consistent with experimental observations in such metals as UPt3UPt_3.Comment: 9 pages, revtex, 3 uuencoded postscript figures attached at en

    A TQFT associated to the LMO invariant of three-dimensional manifolds

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    We construct a Topological Quantum Field Theory (in the sense of Atiyah) associated to the universal finite-type invariant of 3-dimensional manifolds, as a functor from the category of 3-dimensional manifolds with parametrized boundary, satisfying some additional conditions, to an algebraic-combinatorial category. It is built together with its truncations with respect to a natural grading, and we prove that these TQFTs are non-degenerate and anomaly-free. The TQFT(s) induce(s) a (series of) representation(s) of a subgroup Lg{\cal L}_g of the Mapping Class Group that contains the Torelli group. The N=1 truncation produces a TQFT for the Casson-Walker-Lescop invariant.Comment: 28 pages, 13 postscript figures. Version 2 (Section 1 has been considerably shorten, and section 3 has been slightly shorten, since they will constitute a separate paper. Section 4, which contained only announce of results, has been suprimated; it will appear in detail elsewhere. Consequently some statements have been re-numbered. No mathematical changes have been made.
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