Alternatives to Quintessence Model Building

We discuss the issue of toy model building for the dark energy component of the universe. Specifically, we consider two generic toy models recently proposed as alternatives to quintessence models, known as Cardassian expansion and the Chaplygin gas. We show that the former is enteriely equivalent to a class of quintessence models. We determine the observational constraints on the latter, coming from recent supernovae results and from the shape of the matter power spectrum. As expected, these restrict the model to a behaviour that closely matches that of a standard cosmological constant $\Lambda$.Comment: RevTex4; 7 pages, 4 figures. v2: Improved discussion of constraints on Chaplygin gas models. Other clarifications added. Phys Rev. D (in press

Hardy kiwifruit leaves (Actinidia arguta): an extraordinary source of value-added compounds for food industry

The present study reports for the first time the identification and quantification of phenolic compounds, the antioxidant and antimicrobial activities as well as the in vitro radical scavenging activity and intestinal cell effects of A. arguta leaves extracts. Extractions were carried out under water, water:ethanol (50:50) and ethanol. The highest antioxidant activity were obtained in alcoholic extract (IC50 = 53.95 ± 3.09 μg/mL for DPPH; 6628.42 ± 382.49 µmol/mg dry weight basis for FRAP) while the phenolic profile confirmed by HPLC analysis revealed highest amounts of phenolic acids (hydroxycinnamic acid derivatives) and flavonoids (flavan-3-ol and flavonols derivatives). An excellent scavenging activity against reactive oxygen and nitrogen species were determined for all extracts as well as no adverse effects on Caco-2 and HT29-MTX cells in concentrations below 100 μg/mL and 1000 μg/mL, respectively. These results highlight the potentialities of hardy kiwi leaves valorization.info:eu-repo/semantics/publishedVersio

Habilidades e interacciones sociales de los niños con síndrome de Down en la educación ordinaria

En este estudio se identifica el proceso de interacción social de los niños con síndrome de Down (SD) en el sistema educativo ordinario de una ciudad en el interior de São Paulo (Brasil). En el estudio participaron 6 niños de 3 a 6 años de edad. Se filmaron vídeos de cada niño en cuatro situaciones de interacción social en dos ambientes diferentes (interior y exterior), lo que permitió analizar las habilidades interpersonales y de autoexpresión a través de la observación de 15 tipos de conductas. Los resultados revelan que el tipo de conducta “interactúa con otros niños”, dentro de la categoría de “habilidades interpersonales”, fue la más frecuente tanto en ambiente interior como en exterior, con una media de 27,5 y 28,3, respectivamente. Teniendo en cuenta las habilidades de autoexpresión, sólo la conducta “sonríe” se dio una cantidad de veces destacable en interiores, con una media de 8,16, mientras que las conductas “sonríe” e “imita a otros niños” tuvieron una presencia significativa en exteriores, con unas medias de 5,16 y 3, respectivamente. En conclusión, incluir niños con SD en el sistema educativo ordinario promueve en ellos nuevas formas de aprendizaje e interacción mediante el contacto diario con niños con desarrollo normal, lo que les permite adquirir habilidades de interacción social

The First Magnetic Fields

We review current ideas on the origin of galactic and extragalactic magnetic fields. We begin by summarizing observations of magnetic fields at cosmological redshifts and on cosmological scales. These observations translate into constraints on the strength and scale magnetic fields must have during the early stages of galaxy formation in order to seed the galactic dynamo. We examine mechanisms for the generation of magnetic fields that operate prior during inflation and during subsequent phase transitions such as electroweak symmetry breaking and the quark-hadron phase transition. The implications of strong primordial magnetic fields for the reionization epoch as well as the first generation of stars is discussed in detail. The exotic, early-Universe mechanisms are contrasted with astrophysical processes that generate fields after recombination. For example, a Biermann-type battery can operate in a proto-galaxy during the early stages of structure formation. Moreover, magnetic fields in either an early generation of stars or active galactic nuclei can be dispersed into the intergalactic medium.Comment: Accepted for publication in Space Science Reviews. Pdf can be also downloaded from http://canopus.cnu.ac.kr/ryu/cosmic-mag1.pd

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio