9 research outputs found

    A connectome and analysis of the adult Drosophila central brain.

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    The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly's brain

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13\sqrt{s}=13\, TeV using the ATLAS detector

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    Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and ttˉt\bar{t} system kinematic observables using proton--proton collisions at a center-of-mass energy of s=13\sqrt{s} = 13 TeV. The data set corresponds to an integrated luminosity of 36.136.1 fb1^{-1}, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum pT>500p_{\rm T} > 500 GeV and a second with pT>350p_{\rm T}>350 GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a bb-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated χ2\chi^2 values. The cross-section for ttˉt\bar{t} production in the fiducial phase-space region is 292±7 (stat)±76(syst)292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)} fb, to be compared to the theoretical prediction of 384±36384 \pm 36 fb

    Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13\sqrt{s}=13\, TeV using the ATLAS detector

    No full text
    Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and ttˉt\bar{t} system kinematic observables using proton--proton collisions at a center-of-mass energy of s=13\sqrt{s} = 13 TeV. The data set corresponds to an integrated luminosity of 36.136.1 fb1^{-1}, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum pT>500p_{\rm T} > 500 GeV and a second with pT>350p_{\rm T}>350 GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a bb-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated χ2\chi^2 values. The cross-section for ttˉt\bar{t} production in the fiducial phase-space region is 292±7 (stat)±76(syst)292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)} fb, to be compared to the theoretical prediction of 384±36384 \pm 36 fb
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