Methicillin-resistant Staphylococcus aureus: Vascular Surgeons Should Fight Back

AbstractMethicillin-resistant Staphylococcus aureus (MRSA) is now the commonest cause of serious vascular wound and graft infection in the U.K., and vascular departments in many other countries are similarly affected. There are no randomised trials that provide information about how to deal with this epidemic. There are, however, a number of clinical series that provide data that can be used to mount a logical and coherent response to the problem of preventing and managing MRSA infection. The risks and problems are different in every hospital and co-operation with local microbiologists is essential in creating individual protocols. Stratifying the risk to each patient is the first step; established antiseptic and surgical procedures are usually adequate as primary prevention. Studies into the role of targeted antibiotic therapy and isolation techniques are needed

Clinicopathological evidence that neovascularisation is a cause of recurrent varicose veins

Objectives:Recurrent varicose veins may result from poor initial surgical technique or progression of varicosities in collateral veins. In some cases new veins may develop at the saphenofemoral junction (neovascularisation) and cause recurrent saphenofemoral incompetence. This was a histological study of recurrent varicose veins.Design:This clinicopathological study included 20 patients (median age 55 years) who had surgery for recurrent saphenofemoral incompetence.Materials and methods:A total of 28 legs had groin re-exploration with repeat flush saphenofemoral ligation. The venous tissue block from the saphenofemoral region (including the proximal thigh varicosity) was excised and orientated for histological analysis. Evidence of neovascularisation was sought using routine histological sections and S100 immunohistochemistry.Results:At operation, thin-walled, serpentine neovascular veins were detected clinically as the principal cause of recurrence in 19 groins. In five groins recurrence was due to a residual missed vein at the saphenofemoral junction, and in four recurrence was caused by cross groin collaterals. On histological sections, evidence of neovascularisation was present in 27 of 28 groins. In eight it co-existed with the veins missed at the original operation but it was the sole identified cause of recurrent saphenofemoral incompetence in 19 (68%) groins.Conclusions:Neovascularisation was the principal cause of recurrent saphenofemoral incompetence in this series

Measurement of vector boson production cross sections and their ratios using pp collisions at √s = 13.6 TeV with the ATLAS detector

Abstract available from publisher's website

Software performance of the ATLAS track reconstruction for LHC run 3

Charged particle reconstruction in the presence of many simultaneous proton–proton (pp) collisions in the LHC is a challenging task for the ATLAS experiment’s reconstruction software due to the combinatorial complexity. This paper describes the major changes made to adapt the software to reconstruct high-activity collisions with an average of 50 or more simultaneous pp interactions per bunch crossing (pileup) promptly using the available computing resources. The performance of the key components of the track reconstruction chain and its dependence on pile-up are evaluated, and the improvement achieved compared to the previous software version is quantified. For events with an average of 60 pp collisions per bunch crossing, the updated track reconstruction is twice as fast as the previous version, without significant reduction in reconstruction efficiency and while reducing the rate of combinatorial fake tracks by more than a factor two

Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with charged leptons and jets in pp collisions at √s = 13 TeV with the ATLAS detector

A search for heavy right-handed Majorana or Dirac neutrinos NR and heavy right-handed gauge bosons WR is performed in events with energetic electrons or muons, with the same or opposite electric charge, and energetic jets. The search is carried out separately for topologies of clearly separated final-state products (“resolved” channel) and topologies with boosted final states with hadronic and/or leptonic products partially overlapping and reconstructed as a large-radius jet (“boosted” channel). The events are selected from pp collision data at the LHC with an integrated luminosity of 139 fb−1 collected by the ATLAS detector at √s = 13 TeV. No significant deviations from the Standard Model predictions are observed. The results are interpreted within the theoretical framework of a left-right symmetric model, and lower limits are set on masses in the heavy righthanded WR boson and NR plane. The excluded region extends to about m(WR) = 6.4 TeV for both Majorana and Dirac NR neutrinos at m(NR) < 1 TeV. NR with masses of less than 3.5 (3.6) TeV are excluded in the electron (muon) channel at m(WR) = 4.8 TeV for the Majorana neutrinos, and limits of m(NR) up to 3.6 TeV for m(WR) = 5.2 (5.0) TeV in the electron (muon) channel are set for the Dirac neutrinos. These constitute the most stringent exclusion limits to date for the model considered

Observation of four-top-quark production in the multilepton final state with the ATLAS detector

This paper presents the observation of four-top-quark (tt¯tt¯) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 fb−1 at a centre-of-mass energy of 13 TeV collected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of the measured tt¯tt¯ signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The tt¯tt¯ production cross section is measured to be 22.5+6.6−5.5 fb, consistent with the SM prediction of 12.0±2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect tt¯tt¯ production

Search for the Zγ decay mode of new high-mass resonances in pp collisions at √s = 13 TeV with the ATLAS detector

This letter presents a search for narrow, high-mass resonances in the Zγ final state with the Z boson decaying into a pair of electrons or muons. The √s = 13 TeV pp collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb−1. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into Zγ. For spin-0 resonances produced via gluon–gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon–gluon fusion (or quark–antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV