57 research outputs found

    Genome prediction of PhoB regulated promoters in Sinorhizobium meliloti and twelve proteobacteria

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    In proteobacteria, genes whose expression is modulated in response to the external concentration of inorganic phosphate are often regulated by the PhoB protein which binds to a conserved motif (Pho box) within their promoter regions. Using a position weight matrix algorithm derived from known Pho box sequences, we identified 96 putative Pho regulon members whose promoter regions contained one or more Pho boxs in the Sinorhizobium meliloti genome. Expression of these genes was examined through assays of reporter gene fusions and through comparison with published microarray data. Of 96 genes, 31 were induced and 3 were repressed by Pi starvation in a PhoB dependent manner. Novel Pho regulon members included several genes of unknown function. Comparative analysis across 12 proteobacterial genomes revealed highly conserved Pho regulon members including genes involved in Pi metabolism (pstS, phnC and ppdK). Genes with no obvious association with Pi metabolism were predicted to be Pho regulon members in S.meliloti and multiple organisms. These included smc01605 and smc04317 which are annotated as substrate binding proteins of iron transporters and katA encoding catalase. This data suggests that the Pho regulon overlaps and interacts with several other control circuits, such as the oxidative stress response and iron homeostasis

    Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV

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    We report the first measurement of charged particle elliptic flow in Pb-Pb collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (|η\eta|<0.8) and transverse momentum range 0.2< pTp_{\rm T}< 5.0 GeV/cc. The elliptic flow signal v2_2, measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 ±\pm 0.002 (stat) ±\pm 0.004 (syst) in the 40-50% centrality class. The differential elliptic flow v2(pT)_2(p_{\rm T}) reaches a maximum of 0.2 near pTp_{\rm T} = 3 GeV/cc. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/389

    The Dynamics of Managerial Ideology: Analyzing the Cuban Case

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    After the collapse of state socialism in Eastern Europe, management researchers devoted considerable energy to investigate ways to smooth transition to market economies. But one country of the former Soviet bloc, Cuba resisted transition and reaffirmed loyalty to communism. Little is known about management in Cuba on the managerial impacts of the combination of two major environmental forces: the American embargo and the Soviet Union collapse, both of which have challenged the sustainability of the communist regime. This study intends to approach one particular aspect of management in Cuba: the relationship between national ideology and management practice. To analyze these topics, direct qualitative data from focus groups with Cuban managers and management professors was obtained and complemented with documentary analysis. Results suggest that the dynamics of managerial ideology can be understood as the interplay of several processes operating at distinct levels: institutional, professional, organizational and individual. The study provides a nested, multi-level understanding of management and organization as parts of a wider institutional context, which is both a source of constraint and a non-tangible resource to be used by ideological bricoleurs. The interplay between the acceptance of ideology and its use as a practical resource is a potential source of change. As such, the same professional class (managers) may be both a source of continuity and a trigger of change - a finding that is line with institutional theory’s claim that it is necessary to understand both institutionalization and de-institutionalization for understanding organizational change and continuity.N/

    K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76  TeV

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    The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76  TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4  GeV/c (0.6  GeV/c for Λ) to 12  GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3  GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9  TeV and at s√=7  TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2  GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio

    Measurement of D-s(+) product ion and nuclear modification factor in Pb-Pb collisions at root S-NN=2.76 TeV

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    phi-Meson production at forward rapidity in p-Pb collisions at root s(NN)=5.02 TeV and in pp collisions at root s=2.76 TeV

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    The first study of phi-meson production in p-Pb collisions at forward and backward rapidity, at a nucleonnucleon centre-of-mass energy root s(NN)= 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The phi-mesons have been identified in the dimuon decay channel in the transverse momentum (p(T)) range 1 <p(T) <7GeV/c, both in the p-going (2.03 <y <3.53) and the Pb-going (-4.46 <y <-2.96) directions - where ystands for the rapidity in the nucleon-nucleon centre-of-mass - the integrated luminosity amounting to 5.01 +/- 0.19nb(-1) and 5.81 +/- 0.20nb(-1), respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for f-meson production is measured for 2.96Peer reviewe

    Measurement of transverse energy at midrapidity in Pb-Pb collisions at root s(NN)=2.76 TeV

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    We report the transverse energy (ET) measured with ALICE at midrapidity in Pb-Pb collisions at root s(NN) = 2.76 TeV as a function of centrality. The transverse energy was measured using identified single-particle tracks. The measurement was cross checked using the electromagnetic calorimeters and the transverse momentum distributions of identified particles previously reported by ALICE. The results are compared to theoretical models as well as to results from other experiments. The mean ET per unit pseudorapidity (eta), , in 0%-5% central collisions is 1737 +/- 6(stat.) +/- 97(sys.) GeV. We find a similar centrality dependence of the shape of as a function of the number of participating nucleons to that seen at lower energies. The growth in at the LHC energies exceeds extrapolations of low-energy data. We observe a nearly linear scaling of with the number of quark participants. With the canonical assumption of a 1 fm/c formation time, we estimate that the energy density in 0%-5% central Pb-Pb collisions at root s(NN) = 2.76 TeV is 12.3 +/- 1.0 GeV/fm(3) and that the energy density at the most central 80 fm(2) of the collision is at least 21.5 +/- 1.7 GeV/fm(3). This is roughly 2.3 times that observed in 0%-5% central Au-Au collisions at root s(NN) = 200 GeV.Peer reviewe

    Azimuthally Differential Pion Femtoscopy in Pb-Pb Collisions at root s(NN)=2.76 TeV

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    We present the first azimuthally differential measurements of the pion source size relative to the second harmonic event plane in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of root(NN)-N-s = 2.76 TeV. The measurements have been performed in the centrality range 0%-50% and for pion pair transverse momenta 0.2 <k(T) <0.7 GeV/c. We find that the R-side and R-out radii, which characterize the pion source size in the directions perpendicular and parallel to the pion transverse momentum, oscillate out of phase, similar to what was observed at the Relativistic Heavy Ion Collider. The final-state source eccentricity, estimated via R-side oscillations, is found to be significantly smaller than the initial-state source eccentricity, but remains positive-indicating that even after a stronger expansion in the in-plane direction, the pion source at the freeze-out is still elongated in the out-of-plane direction. The 3 + 1D hydrodynamic calculations are in qualitative agreement with observed centrality and transverse momentum R-side oscillations, but systematically underestimate the oscillation magnitude.Peer reviewe

    D-meson production in p-Pb collisions at root S-NN=5.02 TeV and in pp collisions at root S=7 TeV

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    Correlated Event-by-Event Fluctuations of Flow Harmonics in Pb-Pb Collisions at root S-NN=2.76 TeV

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