3,233 research outputs found

    On the quest to study polyploidy in cyanobacteria

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    This thesis investigates the nuanced interplay between polyploidy and evolvability in prokaryotes, with a focus on Synechocystis PCC 6803. Traditionally thought to be rare in prokaryotes, polyploidy has been identified across diverse bacterial and archaeal species, challenging conventional perspectives. To investigate the influence of polyploidy on evolvability, it is crucial to identify experimental conditions allowing the control of ploidy levels. Chapter 2 explores the use of phosphate limitation in continuous cultures for this purpose. Unexpectedly, the WT strain from our lab failed to thrive under these conditions, contrary to literature findings. After prolonged cultivation, a mutant strain, SynPLSS+, capable of growth in such conditions, was isolated. Chapter 3 characterizes this strain, revealing a mutation in the WT strain compared to the closest reference genome. Remarkably, this mutation, responsible for the failure to respond to phosphate limitation, was reverted in SynPLSS+. Chapter 4 employs simulations and laboratory evolution experiments to compare the evolvability of populations with different ploidy levels. Simulations reveal that the impact of polyploidy can be diverse, ranging from beneficial to detrimental, contingent on mutation likelihood and dominance. Experimental findings in this chapter underscore the positive effect of polyploidy on evolvability. Chapter 5 describes a collaborative effort to improve reproducibility in the cyanobacterial field by means of an interlaboratory study performed in eight European laboratories. This thesis provides insights into the dynamic relationship between polyploidy and evolvability, emphasizing experimental challenges and the need for standardization in cyanobacterial research

    Training for innovation in Spain

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    The capacity for innovation of an organisation largely depends on its ability to acquire and develop new knowledge. Training is particularly important in this process, as it allows employees to constantly acquire new competences. This study provides a preliminary picture of the situation of training for innovation in Spain, and identifies the characteristics of companies offering training for innovation. Results show that 35.3% of Spanish companies undertake innovation processes and 22.3% offer training related to these innovation processes. For the 82% of these companies training helped the innovation process, so training is an important tool for innovative change

    Blue-space availability, environmental quality and amenity use across contrasting socioeconomic contexts

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    Over 60% of the global population are expected to live in urban areas by 2050. Urban blue spaces are critical for biodiversity, provide a range of ecosystem services, and can promote human health and wellbeing. Despite this, access to blue space is often unequally distributed across socioeconomic gradients, and the availability of quality blue space could extend to environmental justice issues. Three stages of analysis were carried out in Mexico City, Mexico and Bristol, UK to (i) assess associations between blue space and socioeconomic metrics at a regional scale, (ii) apply a rapid assessment tool to assess amenity, access and environmental quality, (iii) consider local quality across socioeconomic gradients at a regional scale. Still water availability was indicative of higher socioeconomic status, but contrasting city evolutions underpinned differences. Locally, there were environmental gradients from more complex to disturbed habitats that influenced potential wellbeing and amenity benefits. In combination, this may exacerbate inequalities and risk increasing ecosystem disservices. If cities are to be socially, and environmentally resilient to higher levels of disturbance in the future, healthy ecosystems will be key. However, further research is needed to address various dimensions of injustice in urban areas beyond blue space distribution

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

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    A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

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    A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

    Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

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    The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO
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