Ja Hi Som

Presentació de Dolça Tormo i Francesco Ardolin

Determination of the strong coupling alpha_s from the QCD static energy

We obtain a determination of the strong coupling alpha_s in quantum chromodynamics, by comparing perturbative calculations for the short-distance part of the static energy with lattice computations. Our result reads alpha_s(1.5GeV)=0.326\pm0.019, and when evolved to the scale M_Z (the Z-boson mass) it corresponds to alpha_s(M_Z)=0.1156^{+0.0021}_{-0.0022}.Comment: 8 pages, 2 figures. Contribution to the proceedings of Quark Confinement and the Hadron Spectrum

Overview of charmonium decays and production from Non-Relativistic QCD

I briefly review Non-Relativistic QCD and related effective theories, and discuss applications to heavy quarkonium decay, and production in electron-positron colliders.Comment: 8 pages, Invited talk at Charm 2010, Oct. 21-24, IHEP, Beijin

A low-energy determination of αs\alpha_s at three loops

We review one of the most accurate low-energy determinations of $\alpha_s$. Comparing at short distances the QCD static energy at three loops and resummation of the next-to-next-to leading logarithms with its determination in 2+1-flavor lattice QCD, we obtain $\alpha_s(1.5~{\rm GeV})=0.336^{+0.012}_{-0.008}$, which corresponds to $\alpha_s(M_Z)=0.1166^{+0.0012}_{-0.0008}$. We discuss future perspectives.Comment: 9 pages, 8 figures, 4th International Conference on New Frontiers in Physics, Crete, August 2015 and XLV International Symposium on Multiparticle Dynamics, Wildbad Kreuth, October 201

Crystallization and preliminary crystallographic analysis of dUTPase from the helper phage Φ11 of Staphylococcus aureus

Staphylococcus aureus superantigen-carrying pathogenicity islands (SaPIs) have a determinant role in spreading virulence genes among bacterial populations that constitute a major health hazard. Repressor (Stl) proteins are responsible for transcriptional regulation of pathogenicity island genes. Recently, a derepressing interaction between the repressor Stl SaPIbov1 with dUTPase from the Φ11 helper phage was suggested [Tormo-Mas et al. (2010). Nature 465, 779-782]. Towards elucidating the molecular mechanism of this interaction, this study reports expression, purification, and X-ray analysis of Φ11 dUTPase that contains a phage-specific polypeptide segment not present in other dUTPases. Crystals were obtained using the hanging-drop vapor-diffusion method at room temperature. Data were collected from one type of crystal to 2.98 Å resolution. The crystal of Φ11 dUTPase belonged to the cubic space group I23, with unit-cell parameters a=98.16 Å, α=β=γ= 90.00o

Phage inducible islands in the gram-positive cocci

The SaPIs are a cohesive subfamily of extremely common phage-inducible chromosomal islands (PICIs) that reside quiescently at specific att sites in the staphylococcal chromosome and are induced by helper phages to excise and replicate. They are usually packaged in small capsids composed of phage virion proteins, giving rise to very high transfer frequencies, which they enhance by interfering with helper phage reproduction. As the SaPIs represent a highly successful biological strategy, with many natural Staphylococcus aureus strains containing two or more, we assumed that similar elements would be widespread in the Gram-positive cocci. On the basis of resemblance to the paradigmatic SaPI genome, we have readily identified large cohesive families of similar elements in the lactococci and pneumococci/streptococci plus a few such elements in Enterococcus faecalis. Based on extensive ortholog analyses, we found that the PICI elements in the four different genera all represent distinct but parallel lineages, suggesting that they represent convergent evolution towards a highly successful lifestyle. We have characterized in depth the enterococcal element, EfCIV583, and have shown that it very closely resembles the SaPIs in functionality as well as in genome organization, setting the stage for expansion of the study of elements of this type. In summary, our findings greatly broaden the PICI family to include elements from at least three genera of cocci