Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

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

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

Combined portal and hepatic vein embolisation in perihilar cholangiocarcinoma

Background: Major hepatectomy in perihilar cholangiocarcinoma (pCCA) patients with a small future liver remnant (FLR) risks posthepatectomy liver failure (PHLF). This study examines combined portal and hepatic vein embolisation (PVE/HVE) to increase preoperative FLR volume and potentially decrease PHLF rates. Methods: In this retrospective, multicentre, observational study, data was collected from centres affiliated with the DRAGON Trials Collaborative and the EuroLVD registry. The study included pCCA patients who underwent PVE/HVE between July 2016 and January 2023. Results: Following PVE/HVE, 28% of patients (9/32) experienced complications, with 22% (7/32) necessitating biliary interventions for cholangitis. The median degree of hypertrophy after a median of 16 days was 16% with a kinetic growth rate of 6.8% per week. 69% of patients (22/32) ultimately underwent surgical resection. Cholangitis after PVE/HVE was associated with unresectability. After resection, 55% of patients (12/22) experienced complications, of which 23% (5/22) were Clavien-Dindo grade III or higher. The 90-day mortality after resection was 0%. Conclusion: PVE/HVE quickly enhances the kinetic growth rate in pCCA patients. Cholangitis impairs chances on resection significantly. Resection after PVE/HVE is associated with low levels of 90-day mortality. The study highlights the potential of PVE/HVE in improving safety and outcomes in pCCA undergoing resection