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A search for a heavy resonance decaying into a top quark and antiquark tt¯\\[ \\left(\\mathrm{t}\\overline{\\mathrm{t}}\\right) \\] pair is performed using proton-proton collisions at s=13\\[ \\sqrt{s}=13 \\] TeV. The search uses the data set collected with the CMS detector in 2016, which corresponds to an integrated luminosity of 35.9 fb−1. The analysis considers three exclusive final states and uses reconstruction techniques that are optimized for top quarks with high Lorentz boosts, which requires the use of nonisolated leptons and jet substructure techniques. No significant excess of events relative to the expected yield from standard model processes is observed. Upper limits on the production cross section of heavy resonances decaying to a tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] pair are calculated. Limits are derived for a leptophobic topcolor Z′ resonance with widths of 1, 10, and 30%, relative to the mass of the resonance, and exclude masses up to 3.80, 5.25, and 6.65 TeV, respectively. Kaluza-Klein excitations of the gluon in the Randall-Sundrum model are excluded up to 4.55 TeV. To date, these are the most stringent limits on tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] resonances.

In drug development, late stage toxicity issues of a compound are the main cause of failure in clinical trials. In silico methods are therefore of high importance to guide the early design process to reduce time, costs and animal testing. Technical advances and the ever growing amount of available toxicity data enabled machine learning, especially neural networks, to impact the field of predictive toxicology. In this study, cytotoxicity prediction, one of the earliest handles in drug discovery, is investigated using a deep learning approach trained on a highly consistent in-house data set of over 34,000 compounds with a share of less than 5% of cytotoxic molecules. The model reached a balanced accuracy of over 70%, similar to previously reported studies using Random Forest. Albeit yielding good results, neural networks are often described as a black box lacking deeper mechanistic understanding of the underlying model. To overcome this absence of interpretability, a Deep Taylor Decomposition method is investigated to identify substructures that may be responsible for the cytotoxic effects, the so-called toxicophores. Furthermore, this study introduces cytotoxicity maps which provide a visual structural interpretation of the relevance of these substructures. Using this approach could be helpful in drug development to predict the potential toxicity of a compound as well as to generate new insights into the toxic mechanism. Moreover, it could also help to de-risk and optimize compounds.

Annular structures (rings and gaps) in disks around pre-main-sequence stars have been detected in abundance towards class II protostellar objects that are approximately 1,000,000 years old 1 . These structures are often interpreted as evidence of planet formation 1 – 3 , with planetary-mass bodies carving rings and gaps in the disk 4 . This implies that planet formation may already be underway in even younger disks in the class I phase, when the protostar is still embedded in a larger-scale dense envelope of gas and dust 5 . Only within the past decade have detailed properties of disks in the earliest star-forming phases been observed 6 , 7 . Here we report 1.3-millimetre dust emission observations with a resolution of five astronomical units that show four annular substructures in the disk of the young (less than 500,000 years old) 8 protostar IRS 63. IRS 63 is a single class I source located in the nearby Ophiuchus molecular cloud at a distance of 144 parsecs 9 , and is one of the brightest class I protostars at millimetre wavelengths. IRS 63 also has a relatively large disk compared to other young disks (greater than 50 astronomical units) 10 . Multiple annular substructures observed towards disks at young ages can act as an early foothold for dust-grain growth, which is a prerequisite of planet formation. Whether or not planets already exist in the disk of IRS 63, it is clear that the planet-formation process begins in the initial protostellar phases, earlier than predicted by current planet-formation theories 11 . Dust-emission observations of the young (<500,000 years old) protostar IRS 63 show evidence of rings and gaps in its disk, a prerequisite of planet formation.

J.M.F., F.J.L.-C., J.I.M., F.X.O., J.D., and M.S.B. were supported by HAR2017-86509-P, HAR2017-87695-P, and SGR2017-11 from the Generalitat de Catalunya, AGAUR agency. C.L.-F. was supported by Obra Social La Caixa and by FEDER-MINECO (BFU2015- 64699-P). L.B.d.L.E. was supported by REDISCO-HAR2017-88035-P (Plan Nacional I+D+I, MINECO). C.L., P.R., and C.Bl. were supported by MINECO (HAR2016-77600-P). A.Esp., J.V.-V., G.D., and D.C.S.-G. were supported by MINECO (HAR2009-10105 and HAR2013-43851-P). D.J.K. and B.J.C. were supported by NSF BCS-1460367. K.T.L., A.W., and J.M. were supported by NSF BCS-1153568. J.F.-E. and J.A.M.-A. were supported by IT622-13 Gobierno Vasco, Diputación Foral de Álava, and Diputación Foral de Gipuzkoa. We acknowledge support from the Portuguese Foundation for Science and Technology (PTDC/EPH-ARQ/4164/2014) and the FEDER-COMPETE 2020 project 016899. P.S. was supported by the FCT Investigator Program (IF/01641/2013), FCT IP, and ERDF (COMPETE2020 – POCI). M.Si. and K.D. were supported by a Leverhulme Trust Doctoral Scholarship awarded to M.B.R. and M.P. D.R. was supported by an Allen Discovery Center grant from the Paul Allen Foundation, NIH grant GM100233, and the Howard Hughes Medical Institute. V.V.-M. and W.H. were supported by the Max Planck Society.

Protoplanetary disks are known to possess a variety of substructures in the distribution of their millimetre-sized grains, predominantly seen as rings and gaps 1 , which are frequently interpreted as arising from the shepherding of large grains by either hidden, still-forming planets within the disk 2 or (magneto-)hydrodynamic instabilities 3 . The velocity structure of the gas offers a unique probe of both the underlying mechanisms driving the evolution of the disk—such as movement of planet-building material from volatile-rich regions to the chemically inert midplane—and the details of the required removal of angular momentum. Here we report radial profiles of the three velocity components of gas in the upper layers of the disk of the young star HD 163296, as traced by emission from 12 CO molecules. These velocities reveal substantial flows from the surface of the disk towards its midplane at the radial locations of gaps that have been argued to be opened by embedded planets 4 – 7 : these flows bear a striking resemblance to meridional flows, long predicted to occur during the early stages of planet formation 8 – 12 . In addition, a persistent radial outflow is seen at the outer edge of the disk that is potentially the base of a wind associated with previously detected extended emission 12 . Three-dimensional gas velocities in the gapped disk around the young star HD 163296 show meridional flows from the surface of the disk towards its midplane at gap locations.

New sets of CMS underlying-event parameters (“tunes”) are presented for the pythia 8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisons are made for observables measured in various specific processes, such as multijet, Drell–Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from pythia 8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets.

Wood and stone have different damping ratios. The seismic analysis of wood-stone structures is important. The vertical wood-stone structure is regarded as a three degree of freedom system. Based on Caughey damping model of substructures, the whole damping matrix was constructed. Then combined with Newmark-β method, a numerical method was proposed to calculate dynamic responses of wood-stone structures. Numerical results showed that the seismic performance of wood-stone structures was stronger than that of stone structures, and it was weaker than that of wood structures. During the process of earthquake action, the middle wood substructure can obviously improve seismic performance of the wood-stone structure. The bottom structure has greater stiffness, but weaker seismic performance.

FastJet is a C++ package that provides a broad range of jet finding and analysis tools. It includes efficient native implementations of all widely used 2 → 1 sequential recombination jet algorithms for pp and [e.sup.+][e.sup.-] collisions, as well as access to 3rd party jet algorithms through a plugin mechanism, including all currently used cone algorithms. FastJet also provides means to facilitate the manipulation of jet substructure, including some common boosted heavy-object taggers, as well as tools for estimation of pileup and underlying-event noise levels, determination of jet areas and subtraction or suppression of noise in jets.

The evolution of the Milky Way disk, which contains most of the stars in the Galaxy, is affected by several phenomena. For example, the bar and the spiral arms of the Milky Way induce radial migration of stars 1 and can trap or scatter stars close to orbital resonances 2 . External perturbations from satellite galaxies can also have a role, causing dynamical heating of the Galaxy 3 , ring-like structures in the disk 4 and correlations between different components of the stellar velocity 5 . These perturbations can also cause ‘phase wrapping’ signatures in the disk 6 – 9 , such as arched velocity structures in the motions of stars in the Galactic plane. Some manifestations of these dynamical processes have already been detected, including kinematic substructure in samples of nearby stars 10 – 12 , density asymmetries and velocities across the Galactic disk that differ from the axisymmetric and equilibrium expectations 13 , especially in the vertical direction 11 , 14 – 16 , and signatures of incomplete phase mixing in the disk 7 , 12 , 17 , 18 . Here we report an analysis of the motions of six million stars in the Milky Way disk. We show that the phase-space distribution contains different substructures with various morphologies, such as snail shells and ridges, when spatial and velocity coordinates are combined. We infer that the disk must have been perturbed between 300 million and 900 million years ago, consistent with estimates of the previous pericentric passage of the Sagittarius dwarf galaxy. Our findings show that the Galactic disk is dynamically young and that modelling it as time-independent and axisymmetric is incorrect. An analysis of the motions of six million stars in the Milky Way disk reveals substructures such as snail shells and ridges, indicating that our Galaxy has been recently perturbed.

A bstract We introduce a new jet substructure technique called “soft drop declustering”, which recursively removes soft wide-angle radiation from a jet. The soft drop algorithm depends on two parameters — a soft threshold z cut and an angular exponent β — with the β = 0 limit corresponding roughly to the (modified) mass drop procedure. To gain an analytic understanding of soft drop and highlight the β dependence, we perform resummed calculations for three observables on soft-dropped jets: the energy correlation functions, the groomed jet radius, and the energy loss due to soft drop. The β = 0 limit of the energy loss is particularly interesting, since it is not only “Sudakov safe” but also largely insensitive to the value of the strong coupling constant. While our calculations are strictly accurate only to modified leading-logarithmic order, we also include a discussion of higher-order effects such as multiple emissions and (the absence of) non-global logarithms. We compare our analytic results to parton shower simulations and find good agreement, and we also estimate the impact of non-perturbative effects such as hadronization and the underlying event. Finally, we demonstrate how soft drop can be used for tagging boosted W bosons, and we speculate on the potential advantages of using soft drop for pileup mitigation.