A search for ttbar resonances in the lepton plus jets final state with ATLAS using 4.7 fb⁻¹ of collisions at sqrt(s) = 7 TeV

A search for new particles that decay into top quark pairs (t (t) over bar) is performed with the ATLAS experiment at the LHC using an integrated luminosity of 4.7 fb(-1) of proton-proton (pp) collision data collected at a center-of-mass energy root s = 7 TeV. In the t (t) over bar) -> WbWb decay, the lepton plus jets final state is used, where one W boson decays leptonically and the other hadronically. The t (t) over bar) system is reconstructed using both small-radius and large-radius jets, the latter being supplemented by a jet substructure analysis. A search for local excesses in the number of data events compared to the Standard Model expectation in the t (t) over bar) invariant mass spectrum is performed. No evidence for a t (t) over bar) resonance is found and 95% credibility-level limits on the production rate are determined for massive states predicted in two benchmark models. The upper limits on the cross section times branching ratio of a narrow Z' resonance range from 5.1 pb for a boson mass of 0.5 TeV to 0.03 pb for a mass of 3 TeV. A narrow leptophobic topcolor Z' resonance with a mass below 1.74 TeV is excluded. Limits are also derived for a broad color-octet resonance with m 15.3%. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.07 TeV.

Search for a light charged Higgs boson in the decay channel H⁺ o c ars in t art events using collisions at sqrts = 7 TeV with the ATLAS detector

A search for a charged Higgs boson (H+) in t (t) over bar decays is presented, where one of the top quarks decays via t -> H(+)b, followed by H+ -> two jets (c (s) over bar). The other top quark decays to Wb, where the W boson then decays into a lepton (e/mu) and a neutrino. The data were recorded in pp collisions at root s = 7 TeV by the ATLAS detector at the LHC in 2011, and correspond to an integrated luminosity of 4.7 fb(-1). With no observation of a signal, 95 % confidence level (CL) upper limits are set on the decay branching ratio of top quarks to charged Higgs bosons varying between 5 % and 1 % for H+ masses between 90 GeV and 150 GeV, assuming B(H+ -> c (s) over bar) = 100 %.

Measurement of the cross-section for W boson production in association with b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

This paper reports a measurement of the W+b-jets (W+b+X and W+b (b) over bar +X) production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. These results are based on data corresponding to an integrated luminosity of 4.6 fb(-1), collected with the ATLAS detector. Cross-sections are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for both the muon and electron decay modes of the W boson. The W+b-jets cross-section, corrected for all known detector effects, is quoted in a limited kinematic range. Combining the muon and electron channels, the fiducial cross-section for W+b-jets is measured to be 7.1 +/- 0.5 (stat) +/- 1.4 (syst) pb, consistent with the next-to-leading order QCD prediction, corrected for non-perturbative and double-parton interactions (DPI) contributions, of 4.70 +/- 0.09 (stat) (+0.60)(-0.49) (scale) +/- 0.06 (PDF) +/- 0.16 (non-pert) (+0.52)(-0.38) (DPI) pb.

Measurements of Wgamma and Zgamma production in pp collisions at sqrts= 7 TeV with the ATLAS detector the LHC

The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured using pp collisions at root s = 7 TeV. The analyses use a data sample with an integrated luminosity of 4.6 fb(-1) collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons [W(e nu, mu nu) and Z(e(+)e(-), mu(+)mu(-), nu(nu) over bar)] with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WW gamma, ZZ gamma, and Z gamma gamma triple-gauge-boson couplings and to search for the production of vector resonances decaying to Z gamma and W gamma. No deviations from Standard Model predictions are observed and limits are placed on anomalous triple-gauge-boson couplings and on the production of new vector meson resonances.

Search for Extra Dimensions in diphoton events using proton-proton collisions recorded at sqrts=7 TeV with the ATLAS detector at the LHC

The large difference between the Planck scale and the electroweak scale, known as the hierarchy problem, is addressed in certain models through the postulate of extra spatial dimensions. A search for evidence of extra spatial dimensions in the diphoton channel has been performed using the full set of proton-proton collisions at root s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. This dataset corresponds to an integrated luminosity of 4.9 fb(-1). The diphoton invariant mass spectrum is observed to be in good agreement with the Standard Model expectation. In the context of the model proposed by Arkani-Hamed, Dimopoulos and Dvali, 95% confidence level lower limits of between 2.52 and 3.92 TeV are set on the ultraviolet cutoff scale MS depending on the number of extra dimensions and the theoretical formalism used. In the context of the Randall-Sundrum model, a lower limit of 2.06 (1.00) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/(M) over bar (Pl) = 0.1(0.01). Combining with the ATLAS dilepton searches based on the 2011 data, the 95% confidence level lower limit on the Randall-Sundrum graviton mass is further tightened to 2.23 (1.03) TeV for k/(M) over bar (Pl) = 0.1(0.01).

Search for pair production of heavy top-like quarks decaying to a high-pT W boson and a b quark in the lepton plus jets final state at sqrts=7 TeV with the ATLAS detector

A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb(-1) of pp collisions root s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton + jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the t'(t') over bar signal when m(t') greater than or similar to 400 GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t' -> W b) = I, a fourth-generation t' quark with mass lower than 656 GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass similar to 126 GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t' -> Wb) versus BR(t' -> Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses.

Search for long-lived stopped R-hadrons decaying out-of-time with pp collisions using the ATLAS detector

An updated search is performed for gluino, top squark, or bottom squark R-hadrons that have come to rest within the ATLAS calorimeter, and decay at some later time to hadronic jets and a neutralino, using 5.0 and 22.9 fb(-1) of pp collisions at 7 and 8 TeV, respectively. Candidate decay events are triggered in selected empty bunch crossings of the LHC in order to remove pp collision backgrounds. Selections based on jet shape and muon system activity are applied to discriminate signal events from cosmic ray and beam-halo muon backgrounds. In the absence of an excess of events, improved limits are set on gluino, stop, and sbottom masses for different decays, lifetimes, and neutralino masses. With a neutralino of mass 100 GeV, the analysis excludes gluinos with mass below 832 GeV (with an expected lower limit of 731 GeV), for a gluino lifetime between 10 mu s and 1000 s in the generic R-hadron model with equal branching ratios for decays to q (q) over bar(chi) over tilde (0) and g (chi) over tilde (0). Under the same assumptions for the neutralino mass and squark lifetime, top squarks and bottom squarks in the Regge R-hadron model are excluded with masses below 379 and 344 GeV, respectively.

Disposiciones espaciales y valorización del capital. El caso de Nordelta

Asistimos a la ampliación de "...una lógica estrictamente capitalista en el desarrollo metropolitano, otorgando a la plusvalía urbana el rango de criterio urbanístico básico" (de Mattos, 2002:1). El gobierno del Estado se reemplaza por la gobernancia y el sector privado revaloriza su rol como constructor y decisor, el Estado se repliega y el capital encuentra nuevos nichos para valorizarse. La redefinición normativa y la gestión privada alteran la propiedad constitutiva de la ciudad como valor de uso complejo (Topalov, 1979). El capital aprende a valorizarse adquiriendo un control parcial sobre derechos, servicios y bienes públicos, y produciendo elementos urbanos que antes le resultaban irreproducibles. Así, la planificación de la ciudad y la comercialización de un nuevo estilo de vida para los sectores privilegiados deviene en una nueva forma de valorización del capital. ¿Pueden los agentes inmobiliarios por sí solos crear mundos de la vida (Habermas, 1987), en su doble concepción de espacios de sociabilidad y horizonte de apreciación, y asegurarse consumidores? El megaemprendimiento toma cuerpo en los estilos de vida de sus habitantes; una metamorfosis sufrida en sus disposiciones y competencias espaciales reorganiza el sentido de sus prácticas y representaciones territoriales. Los habitus (Bourdieu, 1997) se conforman junto a la nueva espacialidad como estructura estructurada por emprendimientos como Nordelta y como estructura estructurante de los nuevos objetos urbanos. Es decir, los habitus no resultan de la impresión mecánica de las estructuras sociales capitalistas sino que se constituyen en un complejo proceso irreducible a las dicotomías entre objetivismo-subjetivismo, acción-estructura, etc. Las disposiciones y competencias espaciales pueden pensarse como la articulación del par dialéctico que presenta Santos (1996) al referirse al espacio geográfico como un conjunto de sistemas de objetos y sistemas de acciones, considerados como el contexto único en el que se realiza la historia.

Disposiciones espaciales y valorización del capital. El caso de Nordelta

Asistimos a la ampliación de "...una lógica estrictamente capitalista en el desarrollo metropolitano, otorgando a la plusvalía urbana el rango de criterio urbanístico básico" (de Mattos, 2002:1). El gobierno del Estado se reemplaza por la gobernancia y el sector privado revaloriza su rol como constructor y decisor, el Estado se repliega y el capital encuentra nuevos nichos para valorizarse. La redefinición normativa y la gestión privada alteran la propiedad constitutiva de la ciudad como valor de uso complejo (Topalov, 1979). El capital aprende a valorizarse adquiriendo un control parcial sobre derechos, servicios y bienes públicos, y produciendo elementos urbanos que antes le resultaban irreproducibles. Así, la planificación de la ciudad y la comercialización de un nuevo estilo de vida para los sectores privilegiados deviene en una nueva forma de valorización del capital. ¿Pueden los agentes inmobiliarios por sí solos crear mundos de la vida (Habermas, 1987), en su doble concepción de espacios de sociabilidad y horizonte de apreciación, y asegurarse consumidores? El megaemprendimiento toma cuerpo en los estilos de vida de sus habitantes; una metamorfosis sufrida en sus disposiciones y competencias espaciales reorganiza el sentido de sus prácticas y representaciones territoriales. Los habitus (Bourdieu, 1997) se conforman junto a la nueva espacialidad como estructura estructurada por emprendimientos como Nordelta y como estructura estructurante de los nuevos objetos urbanos. Es decir, los habitus no resultan de la impresión mecánica de las estructuras sociales capitalistas sino que se constituyen en un complejo proceso irreducible a las dicotomías entre objetivismo-subjetivismo, acción-estructura, etc. Las disposiciones y competencias espaciales pueden pensarse como la articulación del par dialéctico que presenta Santos (1996) al referirse al espacio geográfico como un conjunto de sistemas de objetos y sistemas de acciones, considerados como el contexto único en el que se realiza la historia.

Disposiciones espaciales y valorización del capital. El caso de Nordelta

Asistimos a la ampliación de "...una lógica estrictamente capitalista en el desarrollo metropolitano, otorgando a la plusvalía urbana el rango de criterio urbanístico básico" (de Mattos, 2002:1). El gobierno del Estado se reemplaza por la gobernancia y el sector privado revaloriza su rol como constructor y decisor, el Estado se repliega y el capital encuentra nuevos nichos para valorizarse. La redefinición normativa y la gestión privada alteran la propiedad constitutiva de la ciudad como valor de uso complejo (Topalov, 1979). El capital aprende a valorizarse adquiriendo un control parcial sobre derechos, servicios y bienes públicos, y produciendo elementos urbanos que antes le resultaban irreproducibles. Así, la planificación de la ciudad y la comercialización de un nuevo estilo de vida para los sectores privilegiados deviene en una nueva forma de valorización del capital. ¿Pueden los agentes inmobiliarios por sí solos crear mundos de la vida (Habermas, 1987), en su doble concepción de espacios de sociabilidad y horizonte de apreciación, y asegurarse consumidores? El megaemprendimiento toma cuerpo en los estilos de vida de sus habitantes; una metamorfosis sufrida en sus disposiciones y competencias espaciales reorganiza el sentido de sus prácticas y representaciones territoriales. Los habitus (Bourdieu, 1997) se conforman junto a la nueva espacialidad como estructura estructurada por emprendimientos como Nordelta y como estructura estructurante de los nuevos objetos urbanos. Es decir, los habitus no resultan de la impresión mecánica de las estructuras sociales capitalistas sino que se constituyen en un complejo proceso irreducible a las dicotomías entre objetivismo-subjetivismo, acción-estructura, etc. Las disposiciones y competencias espaciales pueden pensarse como la articulación del par dialéctico que presenta Santos (1996) al referirse al espacio geográfico como un conjunto de sistemas de objetos y sistemas de acciones, considerados como el contexto único en el que se realiza la historia.

Population pharmacokinetics of hydroxychloroquine in patients with rheumatoid arthritis

Hydroxychloroquine (HCQ) is an antimalarial drug that is also used as a second-line treatment of rheumatoid arthritis (RA). Clinically, the use of HCQ is characterized by a long delay in the onset of action, and withdrawal of treatment is often a result of inefficacy rather than from toxicity. The slow onset of action can be attributed to the pharmacokinetics (PK) of HCQ, and wide interpatient variability is evident. Tentative relationships between concentration and effect have been made, but to date, no population PK model has been developed for HCQ. This study aimed to develop a population PK model including an estimation of the oral bioavailability of HCQ. In addition, the effects of the coadministration of methotrexate on the PK of HCQ were examined. Hydroxychloroquine blood concentration data were combined from previous pharmacokinetic studies in patients with rheumatoid arthritis. A total of 123 patients were studied, giving the data cohort from four previously published studies. Two groups of patients were included: 74 received hydroxychloroquine (HCQ) alone, and 49 received HCQ and methotrexate (MTX). All data analyses were carried out using the NONMEM program. A one-compartment PK model was supported, rather than a three-compartment model as previously published, probably because of the clustering of concentrations taken at the end of a dosing interval. The population estimate of bioavailability of 0.75 (0.07), n = 9, was consistent with literature values. The parameter values from the final model were: (Cl) over bar = 9.9 +/- 0.4 L/h, (V) over bar 605 +/- 91 L, (k(d)) over bar = 0.77 +/- 0.22 hours(-1), (t(tag)) over bar = 0.44 +/- 0.02 hours. Clearance was not affected by the presence of MTX, and, hence, steady-state drug concentrations and maintenance dosage requirements were similar. A population PK model was successfully developed for HCQ.

Reproductive isolation of a new hybrid species, Senecio eboracensis Abbott & Lowe (Asteraceae)

The nature and extent of reproductive isolation was examined between a new self-compatible hybrid species Senecio eboracensis (2n = 40) and its parents, self-incompatible S. squalidus (2n = 20) and self-compatible S. vulgaris (2n = 40). The triploid F-1 of S. eboracensis x S. squalidus exhibited very low seed set ((x) over bar = 0.63%), and F-2 and F-3 progeny were able to recover nominal levels of fertility ((x) over bar = 23.9 and 9.7%), while F-1 and F-2 offspring of S. eboracensis x S. vulgaris showed reduced seed set ((x) over bar = 63.8 and 58.8%). In both cases, evidence from previous work indicates that reduced fertility is associated with meiotic chromosome mispairing, and is a likely consequence of recombining both parental genomes within this new taxon. No hybrid offspring between S. eboracensis and S. squalidus were found in the wild, and only one such hybrid was recorded among 769 progeny produced by S. eboracensis surrounded by S. squalidus on an experimental plot. Natural crossing between S. eboracensis and S. vulgaris was recorded to be very low (between 0 and 1.46%) in the wild, but rose to 18.3% when individuals of S. eboracensis were surrounded by plants of S. vulgaris. It was concluded that strong breeding barriers exist between the new hybrid species and its two parents. Prezygotic isolation between S. eboracensis and S. vulgaris is likely to be largely due to both species reproducing by predominant self-fertilisation. However, differences recorded for germination, seedling survival, time of flowering and characters associated with pollinator attraction, plus significant clumping of juvenile and adult conspecifics in the wild, probably also contribute to reproductive isolation and ecological differentiation.

Aluminium phosphide as a eutectic grain nucleus in hypoeutectic Al-Si alloys

Aluminium phosphide (AlP) particles arc often suggested to be the nucleation site for eutectic silicon in Al-Si alloys, since both the crystal structure and lattice parameter of AlP (crystal structure: cubic K(4) over bar m; lattice parameter: 5.421 Angstrom) are close to that of silicon (cubic Fd3m, 5.431 Angstrom), and the melting point is higher than the Al-Si eutectic temperature. However, the crystallographic relationships between AlP particles and the surrounding eutectic silicon are seldom reported due to the difficulty in analysing the AlP particles, which react with water during sample preparation for polishing. in this study, the orientation relationships between AlP and Si are analysed by transmission electron microscopy using focused ion-beam milling for sample preparation to investigate the nucleation mechanism of eutectic silicon on AlP. The results show a clear and direct lattice relationship between centrally located AlP particles and the surrounding silicon in the hypoeutectic Al-Si alloy.

The large scale distribution of galaxies in the Shapley Supercluster

We present new results of our wide-field redshift survey of galaxies in a 182 square degree region of the Shapley Supercluster (SSC) based on observations with the FLAIR-II spectrograph on the UK Schmidt Telescope (UKST). In this paper we present new measurements to give a total sample of redshifts for 710 bright (R less than or equal to 16.6) galaxies, of which 464 are members of the SSC (8000 < υ < 18 000 km s(-1)). Our data reveal that the main plane of the SSC (upsilon approximate to 14 500 km s(-1)) extends further than previously realised, filling the whole extent of our survey region of 10 degrees by 20 degrees on the sky (35 Mpc by 70 Mpc, for H-0 = 75 km s(-1) Mpc(-1)). There is also a significant structure associated with the slightly nearer Abell 3571 cluster complex (upsilon approximate to 12 000 km s(-1)) with a caustic structure evident out to a radius of 6 Mpc. These galaxies seem to link two previously identified sheets of galaxies and establish a connection with a third one at (V) over bar = 15 000 km s(-1) near RA = 13(h). They also tend to fill the gap of galaxies between the foreground Hydra-Centaurus region and the more distant SSC. We calculate galaxy overdensities of 5.0+/-0.1 over the 182 square degree region surveyed and 3.3+.-0.1 in a 159 square degree region excluding rich clusters. Over the large region of our survey the inter-cluster galaxies make up 46 per cent of all galaxies in the SSC region and may contribute a similar amount of mass to the cluster galaxies.

Large-scale velocity structures in the Horologium-Reticulum supercluster

We present 547 optical redshifts obtained for galaxies in the region of the Horologium-Reticulum supercluster (HRS) using the 6 degrees field (6dF) multifiber spectrograph on the UK Schmidt Telescope at the Anglo-Australian Observatory. The HRS covers an area of more than 12 degrees x 12 degrees on the sky centered at approximately alpha = 03(h)19(m), delta = 50 degrees 02'. Our 6dF observations concentrate on the intercluster regions of the HRS, from which we describe four primary results. First, the HRS spans at least the redshift range from 17,000 to 22,500 km s(-1). Second, the overdensity of galaxies in the intercluster regions of the HRS in this redshift range is estimated to be 2.4, or delta rho/(rho) over bar similar to 1: 4. Third, we find a systematic trend of increasing redshift along a southeast-northwest spatial axis in the HRS, in that the mean redshift of HRS members increases by more than 1500 km s(-1) from southeast to northwest over a 12 degrees region. Fourth, the HRS is bimodal in redshift with a separation of similar to 2500 km s(-1) (35 Mpc) between the higher and lower redshift peaks. This fact is particularly evident if the above spatial-redshift trend is fitted and removed. In short, the HRS appears to consist of two components in redshift space, each one exhibiting a similar systematic spatial-redshift trend along a southeast-northwest axis. Lastly, we compare these results from the HRS with the Shapley supercluster and find similar properties and large-scale features.