53 research outputs found

    An Integrated Microfluidic Device For C-Elegans Early Embryogenesis Studies And Drug Assays

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    The Caenorhabditis elegans embryo is a widely used model for the functional analysis of dynamic cellular processes, such as chromosome segregation, cytokinesis or lineage analysis. However, the conventional embryo preparation method that relies on manually dissecting gravid worms to extract embryos is somewhat time consuming and does not lend itself to high throughput assays. Here, we report a fully integrated microfluidic approach for C. elegans early embryogenesis assays with unprecedented accuracy and throughput. The device consists of a compressible microfluidic pillar-array chamber for robust and fast on-chip extraction of embryos from the uterus of gravid nematodes. Subsequently, embryos are immobilized by automated fluidic transfer in a microtrap array for individual tracking of a large number of embryos, including fragile mutants with drug-permeable eggshells. Our device allows high-resolution live imaging of very early events in embryogenesis, starting from the one-cell stage. We also demonstrate the feasibility of well-controlled compound application in versatile microfluidic pharmacological assays performed on early embryos

    Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.7Calouste Gulbenkian Foundation from LisbonSwiss Fonds Kidagan, ArmeniaConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Financiadora de Estudos e Projetos (FINEP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Natural Science Foundation of China (NSFC)Chinese Ministry of Education (CMOE)Ministry of Science and Technology of China (MSTC)Ministry of Education and Youth of the Czech RepublicDanish Natural Science Research CouncilCarlsberg FoundationDanish National Research FoundationEuropean Research Council under European CommunityHelsinki Institute of PhysicsAcademy of FinlandFrench CNRS-IN2P3Region Pays de LoireRegion AlsaceRegion AuvergneCEA, FranceGerman BMBFHelmholtz AssociationGeneral Secretariat for Research and Technology, Ministry of Development, GreeceHungarian OTKANational Office for Research and Technology (NKTH)Department of Atomic EnergyDepartment of Science and Technology of the Government of IndiaIstituto Nazionale di Fisica Nucleare (INFN) of ItalyMEXT, JapanJoint Institute for Nuclear Research, DubnaNational Research Foundation of Korea (NRF)CONACYTDGAPA, MexicoALFA-ECHELEN Program (High-Energy physics Latin-American-European Network)Stichting voor Fundamenteel Onderzoek der Materie (FOM)Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), NetherlandsResearch Council of Norway (NFR)Polish Ministry of Science and Higher EducationNational Authority for Scientific Research - NASR (Autoritatea Nationala pentru Cercetare Stiintifica - ANCS)Federal Agency of Science of the Ministry of Education and Science of Russian FederationInternational Science and Technology Center, Russian Academy of SciencesRussian Federal Agency of Atomic EnergyRussian Federal Agency for Science and InnovationsCERN-INTASMinistry of Education of SlovakiaDepartment of Science and Technology, South AfricaCIEMATEELAMinisterio de Educacion y Ciencia of SpainXunta de Galicia (Conselleria de Educacion)CEADENCubaenergia, CubaIAEA (International Atomic Energy Agency)Swedish Reseach Council (VR)Knut & Alice Wallenberg Foundation (KAW)Ukraine Ministry of Education and ScienceUnited Kingdom Science and Technology Facilities Council (STFC)The United States Department of EnergyUnited States National Science FoundationState of TexasState of OhioFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

    Legacy of pre-disturbance spatial pattern determines early structural diversity following severe disturbance in mountain spruce forests in Czech Republic

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    Background Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how predisturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. Methods Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. Results Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, predisturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand’s height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights

    Measurement of quarkonium production at forward rapidity in pppp collisions at s=7\sqrt{s} = 7 TeV

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    The inclusive production cross sections at forward rapidity of J/ψ\psi, ψ\psi(2S), Υ\Upsilon(1S) and Υ\Upsilon(2S) are measured in pp collisions at s\sqrt{s} = 7 TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.35 pb1^{-1}. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ+μ\mu^+\mu^- invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pTp_T and rapidity y, over the transverse momentum range 0 < pTp_T < 20 GeV/c for J/ψ\psi and 0 < pTp_T < 12 GeV/c for all other resonances and for 2.5 < y < 4. The measured cross sections integrated over pTp_T and y, and assuming unpolarized quarkonia, are: σJ/ψ\sigma_{J/\psi}=6.69 ±\pm 0.04 ±\pm 0.61 μ\mu b, σψ(2S)\sigma_{\psi(2S)} = 1.13 ±\pm 0.07 ±\pm 0.14 μ\mub, σΥ(1S)\sigma_{\Upsilon(1S)} = 54.2 ±\pm 5.0 ±\pm 6.7 nb and σΥ(2S)\sigma_{\Upsilon(2S)}=18.4 ±\pm 3.7 ±\pm 2.2 nb, where the first uncertainty is statistical and the second one is systematic. These cross sections are obtained assuming unpolarized quarkonium production. The results are compared to measurements performed by other LHC experiments and to theoretical models.The inclusive production cross sections at forward rapidity of J/ψ\psi, ψ\psi(2S), Υ\Upsilon(1S) and Υ\Upsilon(2S) are measured in pp collisions at s=7\sqrt{s} = 7 TeV with the ALICE detector at the LHC. The analysis is based in a data sample corresponding to an integrated luminosity of 1.35 pb1^{-1}. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ+μ\mu^+\mu^- invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pTp_{\rm T} and rapidity yy, over the ranges 0<pT<200 < p_{\rm T} < 20 GeV/cc for J/ψ\psi, 0<pT<120 < p_{\rm T} < 12 GeV/cc for all other resonances and for 2.5<y<42.5 < y < 4. The measured cross sections integrated over pTp_{\rm T} and yy, and assuming unpolarized quarkonia, are: σJ/ψ=6.69±0.04±0.63\sigma_{J/\psi} = 6.69 \pm 0.04 \pm 0.63 μ\mub, σψ=1.13±0.07±0.14\sigma_{\psi^{\prime}} = 1.13 \pm 0.07 \pm 0.14 μ\mub, σΥ(1S)=54.2±5.0±6.7\sigma_{\Upsilon{\rm(1S)}} = 54.2 \pm 5.0 \pm 6.7 nb and σΥ(2S)=18.4±3.7±2.2\sigma_{\Upsilon{\rm (2S)}} = 18.4 \pm 3.7 \pm 2.2 nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.The inclusive production cross sections at forward rapidity of J/ψ{\mathrm{J}/\psi } , ψ(2S){\psi (\mathrm{2S})} , Υ\Upsilon (1S) and Υ\Upsilon (2S) are measured in pp\mathrm{pp} collisions at s=7 TeV\sqrt{s}=7~\mathrm{TeV} with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.35 pb1^{-1} . Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the μ+μ\mu ^+\mu ^- invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum pT{p_\mathrm{T}} and rapidity yy , over the ranges 0<pT<200<{p_\mathrm{T}}<20  GeV/c for J/ψ{\mathrm{J}/\psi } , 0<pT<120<{p_\mathrm{T}}<12  GeV/c for all other resonances and for 2.5<y<42.5<y<4 . The measured cross sections integrated over pT{p_\mathrm{T}} and yy , and assuming unpolarized quarkonia, are: σJ/ψ=6.69±0.04±0.63\sigma _\mathrm{{\mathrm{J}/\psi }}=6.69\pm 0.04\pm 0.63   \upmu b, σψ(2S)=1.13±0.07±0.19\sigma _{\psi (\mathrm{2S})}=1.13\pm 0.07\pm 0.19   \upmu b, σΥ(1S)=54.2±5.0±6.7\sigma _{\Upsilon (\mathrm{1S})}=54.2\,\pm \, 5.0\pm 6.7  nb and σΥ(2S)=18.4±3.7±2.9\sigma _{\Upsilon (\mathrm{2S})}=18.4\,\pm \,3.7\,\pm \, 2.9  nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models

    Measurement of charged jet suppression in Pb-Pb collisions at √sNN = 2.76 TeV

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    A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at sNN−−−√=2.76 TeV is reported. Jets are reconstructed from charged particles using the anti-kT jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |η|<0.5. The transverse momentum pT of charged particles is measured down to 0.15 GeV/c which gives access to the low pT fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R=0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high pT leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R=0.2 and R=0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R<0.3.

    Corrigendum to 'Multi-strange baryon production at mid-rapidity in Pb-Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV' [Phys. Lett. B 728 (2014) 216-227]