Complex impedance measurements of calorimeters and bolometers: correction for stray impedances

Impedance measurements provide a useful probe of the physics of bolometers and calorimeters. We describe a method for measuring the complex impedance of these devices. In previous work, stray impedances and readout electronics of the measurement apparatus have resulted in artifacts in the impedance data. The new technique allows experimenters to find an independent Thevenin or Norton equivalent circuit for each frequency. This method allows experimenters to easily isolate the device impedance from the effects of parasitic impedances and frequency dependent gains in amplifiers.Comment: 5 pages, 6 figure

Effect of a 2-week interruption in methotrexate treatment on COVID-19 vaccine response in people with immune-mediated inflammatory diseases (VROOM study): a randomised, open label, superiority trial

Background: Methotrexate is the first-line treatment for immune-mediated inflammatory diseases and reduces vaccine-induced immunity. We evaluated if a 2-week interruption of methotrexate treatment immediately after COVID-19 booster vaccination improved antibody response against the S1 receptor binding domain (S1-RBD) of the SARS-CoV-2 spike protein and live SARS-CoV-2 neutralisation compared with uninterrupted treatment in patients with immune-mediated inflammatory diseases. Method: We did a multicentre, open-label, parallel-group, randomised, superiority trial in secondary-care rheumatology and dermatology clinics in 26 hospitals in the UK. Adults (aged ≥18 years) with immune-mediated inflammatory diseases taking methotrexate (≤25 mg per week) for at least 3 months, who had received two primary vaccine doses from the UK COVID-19 vaccination programme were eligible. Participants were randomly assigned (1:1) using a centralised validated computer program, to temporarily suspend methotrexate treatment for 2 weeks immediately after COVID-19 booster vaccination or continue treatment as usual. The primary outcome was S1-RBD antibody titres 4 weeks after COVID-19 booster vaccination and was assessed masked to group assignment. All randomly assigned patients were included in primary and safety analyses. This trial is registered with ISRCTN, ISRCTN11442263; following a pre-planned interim analysis, recruitment was stopped early. Finding: Between Sept 30, 2021, and March 7, 2022, we screened 685 individuals, of whom 383 were randomly assigned: to either suspend methotrexate (n=191; mean age 58·8 years [SD 12·5], 118 [62%] women and 73 [38%] men) or to continue methotrexate (n=192; mean age 59·3 years [11·9], 117 [61%] women and 75 [39%] men). At 4 weeks, the geometric mean S1-RBD antibody titre was 25 413 U/mL (95% CI 22 227–29 056) in the suspend methotrexate group and 12 326 U/mL (10 538–14 418) in the continue methotrexate group with a geometric mean ratio (GMR) of 2·08 (95% CI 1·59–2·70; p<0·0001). No intervention-related serious adverse events occurred. Interpretation: 2-week interruption of methotrexate treatment in people with immune-mediated inflammatory diseases enhanced antibody responses after COVID-19 booster vaccination that were sustained at 12 weeks and 26 weeks. There was a temporary increase in inflammatory disease flares, mostly self-managed. The choice to suspend methotrexate should be individualised based on disease status and vulnerability to severe outcomes from COVID-19. Funding: National Institute for Health and Care Research