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

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Age differences in the responses of vervet monkeys, Chlorocebus pygerythrus, to terrestrial alarm calls

This is an author's accepted manuscript of an article published by Elsevier in Animal Behaviour on 21/05/2023, available online at: https://doi.org/10.1016/j.anbehav.2023.04.014 The accepted manuscript may differ from the final published version.The high costs of predation and the opportunity costs associated with predator avoidance are likely to select for flexibility in the development of antipredator responses based on local socioecological conditions. As group size is hypothesized to vary across populations as a function of predation risk, the development of antipredator behaviours throughout ontogeny may be influenced by the size of an individual's social group. Here, we explore the development of alarm call responses in wild vervet monkeys living at the Samara Game Reserve, South Africa. Vervet monkeys at this site live in relatively large social groups, and adult responses to alarms have previously shown less uniformity than in other sites where group sizes are smaller. We presented monkeys playback recordings of terrestrial alarm calls produced by individuals of different age–sex classes. We then videorecorded and scored the responses of receivers along an ordinal maturity scale. We used a mixed-effects ordinal logistic regression model within a Bayesian framework to explore how response intensity is affected by the age–sex of the caller, and the age of receivers. Our analysis showed that younger monkeys (<2 years old) exhibit strong evasive responses to call stimuli, regardless of the age–sex class of the caller. The intensity of these responses decreases with age, with responses to nonalarm calls decreasing earlier in development than responses to alarm calls. Adult responses to alarm calls in this population are as likely to be characterized by a general increase in vigilance as they are to consist of an evasive response. We suggest that responses in younger individuals at Samara are mediated by generalized startle responses to loud, plosive noises. Development of more specific responses throughout ontogeny is likely to be dependent on learning from adult models, whose milder responses reflect local socioecological conditions specific to Samara.Published versio