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BackgroundElectroencephalography (EEG) is increasingly used for monitoring the depth of general anaesthesia, but EEG data from general anaesthesia monitoring are rarely reused for research. Here, we explored repurposing EEG monitoring from general anaesthesia for brain-age modelling using machine learning. We hypothesised that brain age estimated from EEG during general anaesthesia is associated with perioperative risk.MethodsWe reanalysed four-electrode EEGs of 323 patients under stable propofol or sevoflurane anaesthesia to study four EEG signatures (95% of EEG power ResultsClinical exploration in ASA 1 or 2 patients revealed that brain age was positively correlated with intraoperative burst suppression, a risk factor for general anaesthesia complications. Surprisingly, brain age was negatively correlated with burst suppression in patients with higher ASA scores, suggesting hidden confounders. Secondary analyses revealed that age-related EEG signatures were specific to propofol anaesthesia, reflected by limited model generalisation to anaesthesia maintained with sevoflurane.ConclusionsAlthough EEG from general anaesthesia may enable state-of-the-art age prediction, differences between anaesthetic drugs can impact the effectiveness and validity of brain-age models. To unleash the dormant potential of EEG monitoring for clinical research, larger datasets from heterogeneous populations with precisely documented drug dosage will be essential.

— The photoacoustic effect in liquids, generated by nanotransducers excited withshort laser pulses, offers high contrast imaging and promising medical treatment techniques.Understanding the role of the thermal boundary resistance (TBR) and the laser pulse durationin the generation mechanism of acoustic waves is essential to implement efficient photoacousticnanotransducers [1–3]. This work theoretically investigates, for the paradigmatic case ofwater-immersed gold nanoplates, gold-nanocylinders [2] and carbon nanotubes [3], the role of theTBR [4] and laser pulse duration in the competition between the launching mechanisms: thethermophone and the mechanophone. In the thermophone, the nanoparticle acts as a nanoheaterand the wave is launched by water thermal expansion. In the mechanophone, the nanoparticledirectly acts as a nanopiston. Specifically, for a laser pulse duration far exceeding the heat transfertime from the nanostructure to the surronunding water, the thermophone prevails. For theopposite case the mechanophone dominates. Activation of the mechanophone effect is sought totrigger few nanometers wavelength sound waves in water, matching the nanotransducer acousticfrequencies. This is at variance with respect to the commonly addressed case of water-immersednanotransducer excited with ns laser pulses, where only the thermophone effect significantly contributes.The present findings might be of impact in fields ranging from nanoscale non-destructivetesting to water dynamics at the meso to nanoscale. Furthermore, the results point to high-TBR,liquid-immersed nanoparticles as potentially efficient photoacoustic nanogenerators [5], with theadvantage of keeping the liquid environment temperature unaltered.REFERENCES1. Prost, A., F. Poisson, and E. Bossy, “Photoacoustic generation by a gold nano-sphere: Fromlinear to nonlinear thermoelastics in the long-pulse illumination regime,” Phys. Rev. B, Vol. 92,115450, 2015.2. Diego, M., M. Gandolfi, S. Giordano, F. Vialla, A. Crut, F. Vall´ee, P. Maioli, N. Del Fatti,and F. Banfi, “Tuning photoacoustics with nanotransducers via thermal boundary resistanceand laser pulse duration,” Appl. Phys. Lett., Vol. 121, 252201, 2022.3. Diego, M., M. Gandolfi, A. Casto, F. M. Bellussi, F. Vialla, A. Crut, S. Roddaro, M. Fasano,F. Vall´ee, N. Del Fatti, P. Maioli, and F. Banfi, “Ultrafast nano generation of acoustic wavesin water via a single carbon nanotube,” Photoacoustics, Vol. 28, 100407, 2022.4. Casto, A., F. M. Bellussi, M. Diego, N. Del Fatti, F. Banfi, P. Maioli, and M. Fasano, “Waterfilling in carbon nanotubes with different wettability and implications on nanotube/water heattransfer via atomistic simulations,” Int. J. Heat Mass Transf., Vol. 205, 123868, 2023.5. Yu, K., Y. Yang, J. Wang, G. V. Hartland, and G. P. Wang, “Nanoparticle-fluid interactionsat ultrahigh acoustic vibration frequencies studied by femtosecond time-resolved microscopy,”ACS Nano, Vol. 15, 1833–1840, 2021.

We examine the excitonic nature of the E33 optical transition of the individual free-standing index-identified (23, 7) single-walled carbon nanotube by means of the measurements of its radial-breathing-mode and G-mode Raman excitation profiles. We confirm that it is impossible to determine unambiguously the nature of its E33 optical transition (excitonic vs band to band) based only on the excitation profiles. Nevertheless, by combining Raman scattering, Rayleigh scattering, and optical absorption measurements on strictly the same individual (23, 7) single-walled carbon nanotube, we show that the absorption, Rayleigh spectra, and Raman excitation profiles of the longitudinal and transverse G modes are best fitted by considering the nature of the E33 transition as excitonic. The fit of the three sets of data gives close values of the transition energy E33 and damping parameter G33. This comparison shows that the fit of the Raman excitation profiles provides with good accuracy the energy and damping parameter of the excitonic optical transitions in single-walled carbon nanotubes.

International audience; Recently, we determined using spatial modulation spectroscopy, over a broad optical spectralrange, the spectrum and amplitude of the absorption cross-section of individual semiconductingsingle-wall carbon nanotubes.[1] Here, we will present resonant Raman excitation profiles (REP)of radial breathing modes and G modes measured on the same SWNTs. The transition energiesand full width at half-maximum (FWHM) obtained using both measurements techniques will becompared to discuss the different models commonly used to fit REP [2] as illustrated on Figure1. Furthermore, interference effects on Raman intensity [3] will also be evidenced in the case oftwo energetically close optical transitions. Finally, some recent results obtained on other systems(SWNTs homogeneous dimer and double-walled carbon nanotubes) will be briefly reported.[1] J.-C. Blancon et al., Nat. Comm. 4 (2013), 2542.[2] C. Thomsen and S. Reich, M. Cardona, R. Merlin (Eds.): Light Scattering in Solid IX,Topics Appl. 3.Physics 108 (2007), pp. 116-232.[3] V. N. Popov and Ph. Lambin, Phys. Rev. B 73 (2006), 165425.

The concentration of the fourfold and threefold ring modes of normal and densified silica has been quantitatively extracted using time-domain Raman spectroscopy. Their frequency and width are precisely determined even when they are partly masked by a broad background in spontaneous Raman spectroscopy [1,2]. Experiments performed in GeO2 also reveal the existence of a weak vibrational mode ascribed to oxygen motion in three-membered rings [3]. In permanently densified silicas, the variation of the Raman intensity upon densification is very different for bending and stretching modes. For the former we find a Raman coupling-to-light coefficient CB µ w2. This allows to derive a simple law relating the frequency of the bending modes with the Si-O-Si bond-angle in the network and in the fourfold and threefold rings [4]. The model has been applied to densified silicas and sodo-silicates glasses, and the results compare well to numerical simulations. This simple Raman-spectra analysis could become part of the routine characterization of the local and medium range structure of silica-based glasses.

9th International Conference on Laser Ablation, Tenerife, Spain, September 24-28 2007

no abstract

International audience; no abstract

The absorption of a single isolated metal cluster is directly measured using a novel far-field optical technique based on modulation of its position. Single gold nanoparticles with average diameters down to 5 nm, dispersed on a transparent substrate, are optically detected and their absolute absorption cross section determined.

National audience

La dermatophilose est une des maladies les plus importantes des ruminants domestiques des îles caraïbes, où la maladie clinique est associée à la présence de la tique Amblyomma variegatum. Des études séroépidémiologiques ont été effectuées afin d'éclaircir l'épidémiologie de la maladie dans la région, en faisant particulièrement attention au rôle d'A.variegatum. Une banque de 1300 sérums de bovins des Petites Antilles a été examinée par ELISA pour la présence d'anticorps contre Dermatophilus congolensis. II s'est avéré que des animaux séropositifs existent dans des îles non infestées par A. variegatum, et où la dermatophilose n'est jamais ou rarement observée. De plus, il n'y avait pas de différence significative entre la prévalence d'animaux séropositifs des zones infestées par la tique et des zones non infestées de la Martinique et de Sainte-Lucie, deux îles partiellement infestées et où la dermatophilose n'est observée que dans les parties infestées par la tique. La prévalence était basse dans les petites îles ayant un climat sec. Ceci confirme les résultats expérimentaux indiquant qu'A. variegatum n'est pas indispensable pour la transmission de D. congolensis, qui est très répandu dans la plupart des îles. Les concentrations élevées de prostaglandine E2 (entre 151 et 377 ng/ml) et de prostacycline (entre 124 et 134 ng/ml) trouvées dans la salive des femelles d'A. variegatum, suggèrent fortement que la tique pourrait favoriser le développement des lésions par une activité immunomodulatrice de sa salive. Néanmoins, malgré un certain succès dans la reproduction de la dermatophilose chez des chèvres simultanément infestées avec des adultes d' A. variegatum et scarifiées avec Dermatophilus, on n'a pas observé de différence entre des bovins Créole naturellement résistants et des Brahman hautement sensibles, utilisant le même modèle. Les lésions de la dermatophilose sont restées très bénignes sur les animaux des deux races. Après cette expérience, les Brahman ont développé une dermatophilose généralisée après avoir été mis au pâturage, ce qui indique que le rôle respectif des facteurs de risque identifiés comme étant d'importance majeure pour l'expression de la dermatophilose clinique, n'est pas complètement clarifié et demande d'être étudié davantage.

Un foyer de dermatophilose grave est apparu en 1985 dans un troupeau de vaches Brahman importées de la Martinique en Guadeloupe en juillet 1983. La maladie était peu connue en Guadeloupe jusqu'alors, car la race zébu locale possède une résistance naturelle élevée aux maladies transmises par tiques ou associées à elles. Les conditions de l'apparition et du développement de la maladie ont été étudiées en rapport avec la gestion du troupeau, le climat et les traitements appliqués. les résultats ont démontré l'importance économique de cette maladie grave pour les bovins de la région, ainsi que la sensibilité des races exotiques