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Nanoflares are thought to be one of the prime candidates that can heat the solar corona to its multimillion kelvin temperature. Individual nanoflares are difficult to detect with the present generation of instruments, but their presence can be inferred by comparing simulated nanoflare-heated plasma emissions with the observed emission. Using HYDRAD coronal loop simulations, we model the emission from an X-ray bright point (XBP) observed by the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS), along with the nearest available observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the X-Ray Telescope (XRT) on board the Hinode observatory. The length and magnetic field strength of the coronal loops are derived from the linear force-free extrapolation of the observed photospheric magnetogram by the Helioseismic and Magnetic Imager on board SDO. Each loop is assumed to be heated by random nanoflares, whose magnitude and frequency are determined by the loop length and magnetic field strength. The simulation results are then compared and matched against the measured intensity from AIA, XRT, and MaGIXS. Our model results indicate the observed emission from the XBP under study could be well matched by a distribution of nanoflares with average delay times 1500–3000 s. Further, we demonstrate the high sensitivity of MaGIXS and XRT for diagnosing the heating frequency using this method, while AIA passbands are found to be the least sensitive.

Introduction Patients with erosive hand osteoarthritis (EHOA) experience pain and inflammation, two features that can be targeted by vagus nerve stimulation using electrical auricular transcutaneous vagus nerve stimulation (tVNS). A pilot study demonstrated the feasibility of the procedure, so we designed a randomised sham-controlled trial to determine the safety and efficacy of tVNS in EHOA.Methods and analysis ESTIVAL Study (Essai randomisé comparant la STImulation auriculaire transcutanée du nerf Vague versus sham stimulation dans l’Arthrose DigitaLe Érosive symptomatique et inflammatoire) is a superiority, randomised, double-blind sham-controlled trial comparing two parallel arms: active and sham tVNSs in a 1:1 ratio. Patients with symptomatic EHOA (score ≥40/100 mm on a visual analogue scale (VAS) for pain of 0–100 mm) and inflammatory EHOA (≥1 clinical and ultrasonography-determined interphalangeal synovitis) are included in 18 hospital centres (17 rheumatology and 1 rehabilitation departments) in France. Active and sham tVNSs use an auricular electrode connected to the Vagustim device, with no electric current delivered in the sham group. Patients undergo stimulation for 20 min/day for 12 weeks. The follow-up visits take place at weeks 4, 8 and 12. The enrolment duration is 2 years and started in April 2021; 156 patients are scheduled to be included. The primary outcome is the difference in self-reported hand pain in the previous 48 hours measured on a VAS of 0–100 mm between baseline and week 12. Secondary outcomes include other pain outcomes, function, quality of life, serum biomarker levels, compliance and tolerance. For a subset of patients, MRI of the hand is performed at baseline and week 12 to compare the change in Outcome Measures in Rheumatology/Hand Osteoarthritis MRI Scoring System subscores. The primary analysis will be performed at the end of the study according to the intent-to-treat principle.Ethics and dissemination Ethics approval was obtained from the institutional review board (Comité de Protection des Personnes, 2020-A02213-36). All participants will be required to provide written informed consent. The findings will be published in peer-reviewed journals.Trial registration number NCT04520516; Pre-results.Protocol version and number V.2 of 11 March 2021.

The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) sounding rocket experiment launched on 2021 July 30 from the White Sands Missile Range in New Mexico. MaGIXS is a unique solar observing telescope developed to capture X-ray spectral images of coronal active regions in the 6–24 Å wavelength range. Its novel design takes advantage of recent technological advances related to fabricating and optimizing X-ray optical systems, as well as breakthroughs in inversion methodologies necessary to create spectrally pure maps from overlapping spectral images. MaGIXS is the first instrument of its kind to provide spatially resolved soft X-ray spectra across a wide field of view. The plasma diagnostics available in this spectral regime make this instrument a powerful tool for probing solar coronal heating. This paper presents details from the first MaGIXS flight, the captured observations, the data processing and inversion techniques, and the first science results.