Genetic plasticity of the Shigella virulence plasmid is mediated by intra- and inter-molecular events between insertion sequences

Acquisition of a single copy, large virulence plasmid, pINV, led to the emergence of Shigella spp. from Escherichia coli. The plasmid encodes a Type III secretion system (T3SS) on a 30kb pathogenicity island (PAI), and is maintained in a bacterial population through a series of toxin:antitoxin (TA) systems which mediate post-segrega tional killing (PSK). The T3SS imposes a significant cost on the bacterium, and strains which have lost the plasmid and/or genes encoding the T3SS grow faster than wild-type strains in the laboratory, and fail to bind the indicator dye Congo Red (CR). Our aim was to define the molecular events in Shigella flexneri that cause loss of Type III secretion (T3S), and to examine whether TA systems exert positional effects on pINV. During growth at 37°C, we found that deletions of regions of the plasmid including the PAI lead to the emergence of CR-negative colonies; deletions occur through intra-molecula r recombination events between insertion sequences (ISs) flanking the PAI. Furthermore, by repositioning MvpAT (which belongs to the VapBC family of TA systems) near the PAI, we demonstrate that the location of this TA system alters the rearrangements that lead to loss of T3S, indicating that MvpAT acts both globally (by reducing loss of pINV through PSK) as well as locally (by preventing loss of adjacent sequences). During growth at environmental temperatures, we show for the first time that pINV spontaneously integrates into different sites in the chromosome, and this is mediated by inter-molecular events involving IS 1294. Integration leads to reduced PAI gene expression and impaired secretion through the T3SS, while excision of pINV from the chromosome restores T3SS function. Therefore, pINV integration provides a reversible mechanism for Shigella to circumvent the metabolic burden imposed by pINV. Intra- and inter-molecular events between ISs, which are abundant in Shigella spp., mediate plasticity of S. flexneri pINV

Search for neutral color-octet weak-triplet scalar particles in proton-proton collisions at √s= 8TeV

A search for pair production of neutral color-octet weak-triplet scalar particles (Θ0) is performed in processes where one Θ0 decays to a pair of b quark jets and the other to a Z boson plus a jet, with the Z boson decaying to a pair of electrons or muons. The search is performed with data collected by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 19.7 fb−1 of proton-proton collisions at √s = 8TeV. The number of observed events is found to be in agreement with the standard model predictions. The 95% confidence level upper limit on the product of the cross section and branching fraction is obtained as a function of the Θ0 mass. The 95% confidence level lower bounds on the Θ0 mass are found to be 623 and 426 GeV, for two different octo-triplet theoretical scenarios. These are the first direct experimental bounds on particles predicted by the octo-triplet model. © 2015, The Author(s)

Search for heavy gauge W ′ bosons in events with an energetic lepton and large missing transverse momentum at √s = 13 TeV

A search is presented for W′ bosons in events with an electron or muon and large missing transverse momentum, using proton–proton collision data at √s=13 TeV collected with the CMS detector in 2015 and corresponding to an integrated luminosity of 2.3 fb−1. No evidence of an excess of events relative to the standard model expectations is observed. For a W′ boson described by the sequential standard model, upper limits at 95% confidence level are set on the product of the production cross section and branching fraction and lower limits are established on the new boson mass. Masses below 4.1 TeV are excluded combining electron and muon decay channels, significantly improving upon the results obtained with the 8 TeV data. Exclusion limits at 95% confidence level on the product of the W′ production cross section and branching fraction are also derived in combination with the 8 TeV data. Finally, exclusion limits are set for the production of generic W′ bosons decaying into this final state using a model-independent approach

Measurement of the cross section ratio in collisions at σtt¯bb¯/σtt¯jj in pp collisions at s=8 TeV

The first measurement of the cross section ratio σ t t ¯ b b ¯ / σ t t ¯ jj is presented using a data sample corresponding to an integrated luminosity of 19.6 fb−1 collected in pp collisions at s = 8   TeV with the \{CMS\} detector at the LHC. Events with two leptons (e or μ) and four reconstructed jets, including two identified as b quark jets, in the final state are selected. The ratio is determined for a minimum jet transverse momentum p T of both 20 and 40 GeV/c. The measured ratio is 0.022 ± 0.003 ( stat ) ± 0.005 ( syst ) for p T > 20   GeV / c . The absolute cross sections σ t t ¯ b b ¯ and σ t t ¯ jj are also measured. The measured ratio for p T > 40   GeV / c is compatible with a theoretical quantum chromodynamics calculation at next-to-leading order

Angular analysis of the decay B0→K*0μ+μ- from pp collisions at s=8 TeV

The angular distributions and the differential branching fraction of the decay B0→K⁎(892)0μ+μ− are studied using data corresponding to an integrated luminosity of 20.5 fb −1 collected with the CMS detector at the LHC in pp collisions at s=8 TeV . From 1430 signal decays, the forward–backward asymmetry of the muons, the K⁎(892)0 longitudinal polarization fraction, and the differential branching fraction are determined as a function of the dimuon invariant mass squared. The measurements are among the most precise to date and are in good agreement with standard model predictions

Search for neutral MSSM Higgs bosons decaying to μ+μ- in pp collisions at √s=7 and 8 TeV

A search for neutral Higgs bosons predicted in the minimal supersymmetric standard model (MSSM) for μ+μ- decay channels is presented. The analysis uses data collected by the CMS experiment at the LHC in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.3 fb-1, respectively. The search is sensitive to Higgs bosons produced either through the gluon fusion process or in association with a bb quark pair. No statistically significant excess is observed in the μ+μ- mass spectrum. Results are interpreted in the framework of several benchmark scenarios, and the data are used to set an upper limit on the MSSM parameter tanβ as a function of the mass of the pseudoscalar A boson in the range from 115 to 300 GeV. Model independent upper limits are given for the product of the cross section and branching fraction for gluon fusion and b quark associated production at s=8 TeV. They are the most stringent limits obtained to date in this channel. © 2015 The Authors

Kotitalouksien tulot suuralueittain ja väestöryhmittäin : Kotitaloustiedustelu 1971:II

Suomen virallinen tilasto (SVT

Alignment of the CMS tracker with LHC and cosmic ray data

The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multi-processor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10μm.© CERN 2014 for the benefit of the CMS collaboration.

Search for neutral MSSM Higgs bosons decaying to μ+μ−\mu^{+} \mu^{-} in pp collisions at s= \sqrt{s} = 7 and 8 TeV

see paper for full list of authorsInternational audienceA search for neutral Higgs bosons predicted in the minimal supersymmetric standard model (MSSM) for $\mu^{+} \mu^{-}$ decay channels is presented. The analysis uses data collected by the CMS experiment at the LHC in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.3 fb$^{-1}$, respectively. The search is sensitive to Higgs bosons produced through the gluon fusion process and in association with a bb quark pair. No statistically significant excess is observed in the $\mu^{+} \mu^{-}$ mass spectrum. Results are interpreted in the framework of several benchmark scenarios, and the data are used to set an upper limit on the MSSM parameter $\tan{ \beta}$ as a function of the mass of the pseudoscalar A boson in the range from 115 to 300 GeV. Model independent upper limits are given for the product of the cross section and branching fraction for gluon fusion and b quark associated production. They are the most stringent limits obtained to date in this channel