Search

Abstract Magnetically shielded rooms (MSRs) use multiple layers of materials such as MuMetal to screen external magnetic fields that would otherwise interfere with high precision magnetic field measurements such as magnetoencephalography (MEG). Optically pumped magnetometers (OPMs) have enabled the development of wearable MEG systems which have the potential to provide a motion tolerant functional brain imaging system with high spatiotemporal resolution. Despite significant promise, OPMs impose stringent magnetic shielding requirements, operating around a zero magnetic field resonance within a dynamic range of ± 5 nT. MSRs developed for OPM-MEG must therefore effectively shield external sources and provide a low remnant magnetic field inside the enclosure. Existing MSRs optimised for OPM-MEG are expensive, heavy, and difficult to site. Electromagnetic coils are used to further cancel the remnant field inside the MSR enabling participant movements during OPM-MEG, but present coil systems are challenging to engineer and occupy space in the MSR limiting participant movements and negatively impacting patient experience. Here we present a lightweight MSR design (30% reduction in weight and 40–60% reduction in external dimensions compared to a standard OPM-optimised MSR) which takes significant steps towards addressing these barriers. We also designed a ‘window coil’ active shielding system, featuring a series of simple rectangular coils placed directly onto the walls of the MSR. By mapping the remnant magnetic field inside the MSR, and the magnetic field produced by the coils, we can identify optimal coil currents and cancel the remnant magnetic field over the central cubic metre to just |B|= 670 ± 160 pT. These advances reduce the cost, installation time and siting restrictions of MSRs which will be essential for the widespread deployment of OPM-MEG.

The article offers a revisionist account of the early circulation of copies of the Madonna of Santa Maria Maggiore, known since the nineteenth century as the Salus Populi Romani. Traditionally, the propulsion of the image into global circulation has been attributed variously to Pius V or Francisco Borja, the third Superior General of the Society of Jesus. The article argues that the circulation of the Saint Luke Madonna, as it was known at the time, was closely tied to the martyr’s cult that grew up around the Jesuit missionary Inácio de Azevedo and the so-called Brazil Martyrs, a group of Jesuits murdered by Calvinist corsairs off the Canary Islands in 1570. Azevedo had intended to carry a copy of the Roman icon to Brazil, a copy that perished at sea with Azevedo and the party of Jesuit missionaries. The article suggests that the popularity of the image among Jesuits in Europe and the overseas missions was fueled by the nascent martyr’s cult that followed Azevedo’s death. Painted copies of the Saint Luke Madonna came to function, together with relics of the Eleven Thousand Virgins of Cologne, as proxies for the missing material remains of the martyred Jesuits. The article argues that while the distribution of the image was globally extensive, circulation was restricted to an internal Jesuit martyr’s cult.

La circulación de cartas, instrucciones y noticias jugó un papel esencial en la expansión de la Compañía de Jesús y en la coordinación a la larga distancia de los esfuerzos de los jesuitas. La comunicación dentro de la orden ignaciana dependería de la reproducción de normas homogéneas de escritura a la hora de producir y enviar cartas, instrucciones y otros documentos. El presente artículo analiza toda una serie de prácticas sociales organizadas y de técnicas de escritura que estructuraron la comunicación jesuita durante las primeras décadas de existencia de la Compañía. La circulación y difusión de noticias manuscritas desempeñó entonces una función de enorme importancia a la hora de consolidar normas de comunicación. Se plantea así que la circulación de la información dentro de la orden estuvo determinada por prácticas materiales, sociales y culturales específicas que se desarrollaron sobre todo en el seno de los colegios jesuitas.