Reassessing the Thermal Structure of Oceanic Lithosphere With Revised Global Inventories of Basement Depths and Heat Flow Measurements

Half-space cooling and plate models of varying complexity have been proposed to account for changes in basement depth and heat flow as a function of lithospheric age in the oceanic realm. Here, we revisit this well-known problem by exploiting a revised and augmented database of 2028 measurements of depth to oceanic basement, corrected for sedimentary loading and variable crustal thickness, and 3597 corrected heat flow measurements. Joint inverse modeling of both databases shows that the half-space cooling model yields a mid-oceanic axial temperature that is >100°C hotter than permitted by petrologic constraints. It also fails to produce the observed flattening at old ages. Then, we investigate a suite of increasingly complex plate models and conclude that the optimal model requires incorporation of experimentally determined temperature- and pressure-dependent conductivity, expansivity and specific heat capacity, as well as a low conductivity crustal layer. This revised model has a mantle potential temperature of 1300 ± 50°C, which honors independent geochemical constraints and has an initial ridge depth of 2.6 ± 0.3 km with a plate thickness of 135 ± 30 km. It predicts that the maximum depth of intraplate earthquakes is bounded by the 700°C isothermal contour, consistent with laboratory creep experiments on olivine aggregates. Estimates of the lithosphere-asthenosphere boundary derived from studies of azimuthal anisotropy coincide with the 1175 ± 50°C isotherm. The model can be used to isolate residual depth and gravity anomalies generated by flexural and sub-plate convective processes.Natural Environment Research Council PhD Studentshi

Consensus Paper: Radiological Biomarkers of Cerebellar Diseases

Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS