Recent thermodynamic results from lattice QCD analyzed within a quasi-particle model

The thermodynamic behavior of QCD matter at high temperature is currently studied by lattice QCD theory. The main features are the fast rise of the energy density $\epsilon$ around the critical temperature $T_c$ and the large trace anomaly of the energy momentum tensor $< \Theta_\mu^\mu >=\epsilon - 3 P$ which hints at a strongly interacting system. Such features can be accounted for by employing a massive quasi-particle model with a temperature-dependent bag constant. Recent lattice QCD calculations with physical quark masses by the Wuppertal-Budapest group have shown a slower increase of $\epsilon$ and a smaller $<\Theta_\mu^\mu>$ peak with respect to previous results from the hotQCD collaboration. We investigate the implications of such differences from the point of view of a quasi-particle model, also discussing light and strange quark number susceptibilities. Furthermore, we predict the impact of these discrepancies on the temperature-dependence of the transport properties of matter, like the shear and bulk viscosities.Comment: 18 pages, 9 figures; version accepted in Phys. Rev.D; calculation with relaxation time \tau \sim g^4 ln g has been adde

Time-resolved surveys of stellar clusters

We describe the information that can be gained when a survey is done multi-epoch, and its particular impact for open clusters. We first explain the irreplaceable information that multi-epoch observations are giving within astrometry, photometry and spectroscopy. Then we give three examples for results on open clusters from multi-epoch surveys, namely, the distance to the Pleiades, the angular momentum evolution of low mass stars and asteroseismology. Finally we mention several very large surveys, which are ongoing or planned for the future, Gaia, JASMINE, LSST, and VVV.Comment: 8 pages, 1 figure, JENAM 2010: Star Clusters in the Era of Large Surveys, Editors: A.Moitinho and J. Alves; Second initial added for R. I. Anderson, reference adde

Coexistence of two main folded G-quadruplexes within a single G-rich domain in the EGFR promoter

EGFR is an oncogene which codifies for a tyrosine kinase receptor that represents an important target for anticancer therapy. Indeed, several human cancers showed an upregulation of the activity of this protein. The promoter of this gene contains some G-rich domains, thus representing a yet unexplored point of intervention to potentially silence this gene. Here, we explore the conformational equilibria of a 30-nt long sequence located at position -272 (EGFR-272). By merging spectroscopic and electrophoretic analysis performed on the wild-type sequence as well as on a wide panel of related mutants, we were able to prove that in potassium ion containing solution this sequence folds into two main G-quadruplex structures, one parallel and one hybrid. They show comparable thermal stabilities and affinities for the metal ion and, indeed, they are always co-present in solution. The folding process is driven by a hairpin occurring in the domain corresponding to the terminal loop which works as an important stabilizing element for both the identified G-quadruplex arrangements

Searching for variable stars in Galactic Open Clusters

A long-term project, aiming at systematic search for variable stars in Galactic Open Clusters, was started at the Geneva Observatory in 2002. We have been observing regularly a sample of twenty-seven Galactic Open Clusters in the U, B, V Geneva filters. The goal is to identify and to study their variable stars, as well as the connection between the variable stars in a cluster and the cluster properties. We present the status of this work in progress, and show preliminary results for one of these clusters, IC 4651.Comment: To appear in the proceedings of Stellar Pulsation: Challenges for theory and observations Conference, Santa Fe, NM, US

Looking for variable stars in galactic open clusters

A long-term project, aiming at systematic search for variable stars in Galactic Open Clusters (OCs), was started at the Geneva Observatory in 2002. We have been observing regularly a sample of twenty-seven Galactic Open Clusters in the U, B, V Geneva filters (hereafter U, B, V). The goal is to identify and to study their variable stars, as well as the connection between the variable stars in a cluster and the cluster properties. We present the status of this work in progress, and show preliminary results for one of these clusters, IC 465

Perspectivas de los estudios de arqueomagnetismo en Sudamérica

Archaeomagnetism is the study of past geomagnetic field variations using bricks, pottery and campfire stones. This is a multidisciplinary work in which archaeologists, historians and geophysicists play important roles. For geophysicists, it contributes to the reconstruction and the study of local and global variations of the geomagnetic field, and it can serve as a dating tool for historical studies. However, this technique goes far beyond the chronological application, as it may provide information for paleoenvironmental studies and the provenance of objects. These studies are well developed in Europe, where there are records since the Middle Ages and a wide variety of recent data; on the contrary, data are scarce in the Southern Hemisphere, although several collaborative initiatives have enabled to make significant progress in recent years.El Arqueomagnetismo es el estudio de cambios y variaciones en el campo magnético terrestre en el pasado a partir de objetos, estructuras y materiales de construcción antiguos. Se trata de un trabajo multidisciplinario entre arqueólogos, historiadores y geofísicos. Para los geofísicos contribuye a la reconstrucción y al estudio de las variaciones globales y locales del campo geomagnético, mientras que para los estudios históricos, constituye fundamentalmente una herramienta de datación. Sin embargo, esta técnica va más allá de las aplicaciones cronológicas, pudiendo aportar información para los estudios paleoambientales y de procedencia de objetos. Los estudios de este tipo están muy desarrollados en Europa, donde se cuenta con registros desde el medioevo y una enorme cantidad de análisis recientes, pero hasta el momento los antecedentes en el hemisferio Sur son muy escasos, aunque se está progresando rápidamente con la colaboración entre distintas instituciones en los últimos años.Fil: Greco Mainero, Mariano Catriel. Universidad Nacional Autónoma de México; MéxicoFil: Goguichaishvili, Avto. Universidad Nacional Autónoma de México; MéxicoFil: Morales, Juan. Universidad Nacional Autónoma de México; MéxicoFil: Bocco, G.. Universidad Nacional Autónoma de México; MéxicoFil: Gogorza, Claudia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; ArgentinaFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin

Pulsating Variable Stars in the Coma Berenices dwarf spheroidal galaxy

We present B, V, I time-series photometry of the Coma Berenices dwarf spheroidal galaxy, a faint Milky Way satellite, recently discovered by the Sloan Digital Sky Survey. We have obtained V, B-V and V, V-I color-magnitude diagrams that reach V~23.0-23.2 mag showing the galaxy turnoff at V~21.7 mag, and have performed the first study of the variable star population of this new Milky Way companion. Two RR Lyrae stars (a fundamental-mode -RRab- and a first overtone -RRc- pulsator) and a short period variable with period P=0.12468 days were identified in the galaxy. The RRab star has a rather long period of P_ab=0.66971 days and is about 0.2 mag brighter than the RRc variable and other non-variable stars on the galaxy horizontal branch. In the period-amplitude diagram the RRab variable falls closer to the loci of Oosterhoff type-II systems and evolved fundamental-mode RR Lyrae stars in the Galactic globular cluster M3. The average apparent magnitude of the galaxy horizontal branch, =18.64+-0.04 mag, leads to a distance modulus for the Coma dSph mu_0=18.13+-0.08 mag, corresponding to a distance d=42^{+2}_{-1} kpc, by adopting a reddening E(B-V) = 0.045 +- 0.015 mag and a metallicity [Fe/H]=-2.53 +- 0.05 dex.Comment: 14 pages, 3 figures, Accepted for publication in ApJ