427 research outputs found

    Conservation challenges for mediterranean gypsophytes.

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    Se abordan los principales retos que plantean un grupo ecológico muy determinado de plantas mediterráneas (gipsófitos)

    Conservation challenges for mediterranean gypsophytes.

    Get PDF
    Se abordan los principales retos que plantean un grupo ecológico muy determinado de plantas mediterráneas (gipsófitos)

    Karyotypic Changes through Dysploidy Persist Longer over Evolutionary Time than Polyploid Changes

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    Chromosome evolution has been demonstrated to have profound effects on diversification rates and speciation in angiosperms. While polyploidy has predated some major radiations in plants, it has also been related to decreased diversification rates. There has been comparatively little attention to the evolutionary role of gains and losses of single chromosomes, which may or not entail changes in the DNA content (then called aneuploidy or dysploidy, respectively). In this study we investigate the role of chromosome number transitions and of possible associated genome size changes in angiosperm evolution. We model the tempo and mode of chromosome number evolution and its possible correlation with patterns of cladogenesis in 15 angiosperm clades. Inferred polyploid transitions are distributed more frequently towards recent times than single chromosome gains and losses. This is likely because the latter events do not entail changes in DNA content and are probably due to fission or fusion events (dysploidy), as revealed by an analysis of the relationship between genome size and chromosome number. Our results support the general pattern that recently originated polyploids fail to persist, and suggest that dysploidy may have comparatively longer-term persistence than polyploidy. Changes in chromosome number associated with dysploidy were typically observed across the phylogenies based on a chi-square analysis, consistent with these changes being neutral with respect to diversification

    Rationale and design of a multicenter, international and collaborative coronary artery aneurysm registry (CAAR)

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    Coronary artery aneurysm has been classically defined as a coronary dilation that exceeds the diameter of normal adjacent segments or the diameter of the patient’s largest coronary vessel by 1.5×. Termed by Bourgon,1 it is an uncommon disease that has been diagnosed with increasing occurrence since the advent of coronary angiography.2,3 The incidence has been reported to vary from 1.5% to 5%, with suggested male dominance and a predilection for the right coronary artery.2,3 Although several causes have been shown, atherosclerosis accounts for ≥50% of coronary aneurysms in adults. Reported complications include thrombosis and distal embolization, vasospasm, and rupture, producing ischemia, heart failure, or arrhythmias. The natural history and long-term outcomes remain unclear, as definitive data are lacking. In addition, controversies persist regarding the use of medical treatment (antithrombotic therapy) or interventional/surgical procedures.1–

    Measurement of inclusive J/ψ\psi pair production cross section in pp collisions at s=13\sqrt{s} = 13 TeV

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    International audienceThe production cross section of inclusive J/ψ\psi pairs in pp collisions at a centre-of-mass energy s=13\sqrt{s} = 13 TeV is measured with ALICE. The measurement is performed for J/ψ\psi in the rapidity interval 2.502.5 0. The production cross section of inclusive J/ψ\psi pairs is reported to be 10.3±2.3(stat.)±1.3(syst.)10.3 \pm 2.3 {\rm (stat.)} \pm 1.3 {\rm (syst.)} nb in this kinematic interval. The contribution from non-prompt J/ψ\psi (i.e. originated from beauty-hadron decays) to the inclusive sample is evaluated. The results are discussed and compared with data

    Inclusive and multiplicity dependent production of electrons from heavy-flavour hadron decays in pp and p-Pb collisions

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    International audienceMeasurements of the production of electrons from heavy-flavour hadron decays in pp collisions at s=13\sqrt{s} = 13 TeV at midrapidity with the ALICE detector are presented down to a transverse momentum (pTp_{\rm T}) of 0.2 GeV/c/c and up to pT=35p_{\rm T} = 35 GeV/c/c, which is the largest momentum range probed for inclusive electron measurements in ALICE. In p-Pb collisions, the production cross section and the nuclear modification factor of electrons from heavy-flavour hadron decays are measured in the pTp_{\rm T} range 0.5<pT<260.5 < p_{\rm T} < 26 GeV/c/c at sNN=8.16\sqrt{s_{\rm NN}} = 8.16 TeV. The nuclear modification factor is found to be consistent with unity within the statistical and systematic uncertainties. In both collision systems, first measurements of the yields of electrons from heavy-flavour hadron decays in different multiplicity intervals normalised to the multiplicity-integrated yield (self-normalised yield) at midrapidity are reported as a function of the self-normalised charged-particle multiplicity estimated at midrapidity. The self-normalised yields in pp and p-Pb collisions grow faster than linear with the self-normalised multiplicity. A strong pTp_{\rm T} dependence is observed in pp collisions, where the yield of high-pTp_{\rm T} electrons increases faster as a function of multiplicity than the one of low-pTp_{\rm T} electrons. The measurement in p-Pb collisions shows no pTp_{\rm T} dependence within uncertainties. The self-normalised yields in pp and p-Pb collisions are compared with measurements of other heavy-flavour, light-flavour, and strange particles, and with Monte Carlo simulations

    Observation of medium-induced yield enhancement and acoplanarity broadening of low-pTp_\mathrm{T} jets from measurements in pp and central Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

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    International audienceThe ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high pTp_{\rm T}) hadron trigger in proton-proton and central Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02 TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions. Recoil jet distributions are reported for jet resolution parameter R=0.2R=0.2, 0.4, and 0.5 in the range 7<pT,jet<1407 < p_{\rm T,jet} < 140 GeV/c/c and trigger-recoil jet azimuthal separation π/2<Δφ<π\pi/2 < \Delta\varphi < \pi. The measurements exhibit a marked medium-induced jet yield enhancement at low pTp_{\rm T} and at large azimuthal deviation from Δφπ\Delta\varphi\sim\pi. The enhancement is characterized by its dependence on Δφ\Delta\varphi, which has a slope that differs from zero by 4.7σ\sigma. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation

    Probing the Chiral Magnetic Wave with charge-dependent flow measurements in Pb-Pb collisions at the LHC

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    International audienceThe Chiral Magnetic Wave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotropic flow coefficients are studied in Pb-Pb collisions at center-of-mass energy per nucleon-nucleon collision sNN=\sqrt{s_{\mathrm{NN}}}= 5.02 TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic (v2v_{2}) and triangular (v3v_{3}) flow coefficients of positively and negatively charged particles as a function of their event-wise normalized number difference, is reported for inclusive and identified particles. The slope r3Normr_{3}^{\rm Norm} is found to be larger than zero and to have a magnitude similar to r2Normr_{2}^{\rm Norm}, thus pointing to a large background contribution for these measurements. Furthermore, r2Normr_{2}^{\rm Norm} can be described by a blast wave model calculation that incorporates local charge conservation. In addition, using the event shape engineering technique yields a fraction of CMW (fCMWf_{\rm CMW}) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit for fCMWf_{\rm CMW}, and in the 10-60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level

    Charged-particle production as a function of the relative transverse activity classifier in pp, p-Pb, and Pb-Pb collisions at the LHC

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    International audienceMeasurements of charged-particle production in pp, p-Pb, and Pb-Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum (pTtrigp_{\mathrm{T}}^{\rm trig}) in the range 8<pTtrig<158<p_{\mathrm{T}}^{\rm trig}<15 GeV/c/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, RT=NchT/NchTR_{\mathrm{T}}=N_{\mathrm{ch}}^{\mathrm{T}}/\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle, is used to group events according to their UE activity, where NchTN_{\mathrm{ch}}^{\mathrm{T}} is the charged-particle multiplicity per event in the transverse region and NchT\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle is the mean value over the whole analysed sample. The energy dependence of the RTR_{\mathrm{T}} distributions in pp collisions at s=2.76\sqrt{s}=2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particle pTp_{\rm T} spectra as a function of RTR_{\mathrm{T}} in the three azimuthal regions in pp, p-Pb, and Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p-Pb)
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