Direction Générale de l'Armement

Background: Submarines represent extremely confined environments where breathing air is continuously recirculated for extended periods with minimal renewal, generating complex multipollutant atmospheres. Objectives: This critical narrative review aims to (i) summarize sources and composition of submarine indoor air, (ii) evaluate respiratory and cardiovascular risks for crews, and (iii) assess current purification technologies. Methods: A narrative review was conducted following PRISMA recommendations applicable to non-systematic reviews. The PubMed search covered all years from inception to September 2025, complemented by backward citation tracking and technical reports. Results: Eligible studies consistently report elevated levels of CO2, VOCs, NOX, CO, PM2.5, and bioaerosols aboard submarines. Evidence from submariner cohorts and toxicological studies indicates risks of airway irritation, impaired mucociliary defenses, endothelial dysfunction, cardiovascular stress, and neurobehavioral alterations. Conclusions: Submarine indoor air quality is a credible determinant of crew health. Existing filtration systems mitigate some risks but do not address multipollutant mixtures adequately. Improved real-time monitoring, advanced filtration, CFD-guided airflow optimization, and longitudinal medical surveillance are necessary.

Introduction Wearing personal protective equipment that provides more protection than is necessary compromises the effectiveness of medical procedures. Using simulants, we aimed to assess the risk of secondary exposure in the operating room during surgery on patients with mustard-contaminated penetrating wounds. Methods The evaluation was performed in an operating room equipped with a laminar flow ventilation system. The damage control procedure was simulated three times using a dummy with a contaminated abdominal wound, after prehospital decontamination. First, a fluorescent marker was used to assess cross-contamination by the liquid phase. Second, methyl salicylate was used twice at increasing doses (probable and worst-case scenarios) to evaluate vapor-phase atmospheric contamination. Finally, the atmospheric concentration of methyl salicylate in the operating room was modeled. Results The transfer of the fluorescent marker to surfaces was minimal and strictly confined to the surgical area. Methyl salicylate vapor was only detected in the worst-case scenario, with the highest concentrations in the surgical area. The measured mean atmospheric concentration of methyl salicylate was close to the modeled concentration. Discussion The measured ambient and individual methyl salicylate concentrations, as well as the modeled mean atmospheric concentration, were all below the Acute Exposure Limit Level 1 for sulfur mustard over a 1 h exposure period. Therefore, the risk of secondary exposure through the vapor phase is estimated to be very low. However, the results may vary slightly in the case of poor-quality sulfur mustard, due to its slight differences in physical and chemical properties compared to pure sulfur mustard. Conclusion If a patient exposed to sulfur mustard with a contaminated penetrating wound is treated in the operating room of our facility for less than one hour, after prehospital decontamination, the personal protective equipment usually required for exposure to a chemical warfare agent could be reduced by removing the full-face air-purifying respirator.

A 37-year-old man in Chad presented with a fever and a headache. An extensive evaluation identified a mammarenavirus, close to Lassa virus, in samples of cerebrospinal fluid.

For radiation or scattering problems, the Fraunhofer distance allows us to define the far-field (FF) zone. It depends on the largest dimension of the target or aperture and the wavelength. This article shows that this distance can be expressed from this conventional Fraunhofer distance multiplied by a new function. It depends on the transmitter and receiver spherical angles and the target or aperture profile features, assumed to be a paraboloid. This function is positive and smaller than or equal to one, which means that the conventional Fraunhofer distance can be overestimated. In addition, the criterion is generalized to the case where the receiver and the transmitter must be both in FF. From the Rao-Wilton–Glisson Galerkin method of moments (MoMs), the comparison of the scattered field computed both in near and far fields validates the closed-form expressions of the new Fraunhofer criterion.

Abstract One-bit coding metasurfaces combine two basic unit cells with out-of-phase responses. Their potential in achieving diffuse scattering has already been demonstrated. These metasurfaces can subsequently be applied to radar-signature control. This paper presents a theoretical analysis linking the scattered field to the autocorrelation of the code that encodes the metasurface. This analysis leads to a focus on Minimum Peak Sidelobes codes with autocorrelation characteristics similar to the unit impulse. Advances in other research areas have greatly enhanced the search for these kind of codes, making them directly usable for coding diffuse scattering metasurfaces. This approach is compared with existing codes, specifically examining how it performs against the optimal code found through exhaustive search in small-scale scenarios. Then, it is shown that this coding strategy facilitates the design of metasurfaces with any and large electrical sizes, achieving results comparable to those obtained through optimization-based approaches, at a significantly reduced computational workload.

The new generation of non-hydrostatic and compressible numerical models of the ocean can explicitly simulate acoustic waves when and where space and time resolution is adapted. We show that these models can consequently propagate accurately acoustic waves and modes through a free-surface, stratified ocean evolving simultaneously both in space and time, bringing them to the state of the art of acoustic propagation modelling. To some extent, both numerical cost and memory footprint may temper their range of applications but they are an unprecedented tool to evaluate deterministically the effects of ocean variability on low-frequency acoustic propagation in a realistically-evolving ocean. This potential is illustrated by two examples of three-dimensional propagation: the wedge benchmark and Kelvin-Helmholtz instabilities.

Sourcing in chemical forensic science refers to the attribution of a sample to a specific source using a characteristic signature. It relies on the identification of chemical attribution signatures (CAS), including chemical markers such as residual sy

Until last years, filters for mobile operated in the 70-350 MHz frequency range with a quality factor times frequency (Q×f) product reaching values of around 9×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup>. The aim is now to reach a Q×f of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup>. Progress on quartz material is a key factor success. We worked on the synthesis of quartz to get higher purity and larger size (100mm/4-inches) to exceed characterization standard values (IEC 60 758 and JIS C 6704). Our Pure Premium Quartz (PPQ) AT wafers were compatible with fabrication of SAW devices. Multiple resonance resonators were manufactured, based on 2 interdigitated transducers, Bragg mirrors and a central cavity. The device measurements have been compared with theoretical prediction, yielding an excellent agreement between both curves. Same for the Temperature Coefficient of Frequency (TCF). Further analysis identified an attenuation constant of 1 mdB/λ providing the measured Q factors and therefore a Q×f product of 8.96×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> at air. Works in progress on our quartz should reach a Q×f product of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> on 150mm (6-inches) AT wafers.