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Insights into L4 ordinary chondrites from the Gueltat Zemmour fall, Morocco: Modal mineralogy, chondrule characteristics, and magnetic signatures
No full textInternational audienceThe Gueltat Zemmour meteorite, an L4 ordinary chondrite that fell in southern Morocco on 21 August 2018, was investigated through petrographic, mineralogical, geochemical, and magnetic analyses. X-ray diffraction indicates a modal composition dominated by forsteritic olivine (39.7(4) weight %), enstatite (32.4(3) %), plagioclase (7.3(1) %), troilite (3.7(1) %), and Fe–Ni metal phases (16.9 %, kamacite-dominated). Chondrules represent ∼82 % of the surface area, with porphyritic olivine–pyroxene and porphyritic olivine as the dominant types, and an average diameter of ∼500 μm. Gamma spectrometry confirmed the presence of short-lived cosmogenic radionuclides (e.g., 7Be, 22Na, 26Al, 48V), with a 22Na/26Al activity ratio consistent with a recent fall. Magnetic hysteresis properties and the preservation of tetrataenite in cloudy zone textures indicate slow cooling during parent-body metamorphism. The sulfide assemblage, dominated by troilite with rare pentlandite, combined with Fe/S (∼0.98) and Fe_ox/Si (∼0.36) ratios, reflects reducing redox conditions near the iron–wüstite buffer and minimal secondary alteration. These integrated results confirm the classification of Gueltat Zemmour as an equilibrated L4 chondrite and provide new insights into the thermal history and redox state of L-group parent bodies, contributing to a broader understanding of the early evolution of ordinary chondrites
Impact of lymph node staging on survival in presumed early-stage ovarian cancer: a multicentric retrospective study
No full textInternational audienceObjective:This study aimed to assess the impact of comprehensive staging on survival outcomes in this population.Methods:Patients who underwent surgery for epithelial ovarian cancer in one of the 14 Francogyn cancer centers between 2000 and 2020 were included in the study. The primary analysis evaluated the impact of lymphadenectomy on overall survival and recurrence-free survival. Lymph node count was analyzed as a continuous variable, and its association with survival, considered as a continuous outcome was assessed using linear regression (secondary analysis). Survival was compared using the log-rank test, and multivariate analysis was performed using a Cox model.Results:A total of 467 patients with presumed early-stage epithelial ovarian cancer were included, of which 198 underwent complete lymphadenectomy and 266 did not. No significant association was found between lymph node staging and survival in the primary analysis, possibly due to limited statistical power and a selection bias, as patients without lymphadenectomy had more favorable disease profiles (p=0.600 and p=0.700, respectively). Complete lymphadenectomy was associated with a significantly higher risk of complications (34.5% vs. 14%, p<0.001). In secondary analysis, the number of para-aortic lymph nodes harvested was identified as an independent predictor of both overall survival and recurrence-free survival (p=0.007 and p=0.002, respectively). Histological characteristics and adjuvant chemotherapy also showed a significant correlation with improved survival outcomes.Conclusion:Extensive para-aortic lymphadenectomy in early-stage epithelial ovarian cancer is associated with better overall and recurrence-free survival but comes with an increased risk of complications
Optimal excitation of single mode resonators: demonstration with a 3 T MRI metasolenoid
No full textInternational audienceWireless passive resonators have been developed to inductively couple to the birdcage body coil. Such systems have been explored in the form of ceramic resonators with high permittivity but also with metamaterial or metasurface devices that can exhibit resonant behaviour at a given Larmor frequency. The resonant focusing of the radiofrequency field is used to lower the input power during transmission and improve the sensitivity of the body coil during reception. The gain is only obtained in a limited volume located within or close to the resonant structure. Typically, such passive devices do not support parallel imaging and demonstrated limited SNR enhancement compared to dense multichannel receive arrays. Nonetheless, these resonators have seen recent development with applications to wrist or breast MRI mostly in 1.5 T MRI scanners. Here we propose to design, build, and study a metasolenoid resonator operating at 3 T. The metasolenoid was characterized on phantom to validate the B 1 efficiency increase with respect to the birdcage polarization excitation. We reported a high B 1 efficiency gain for circularly (3.2-fold) and linearly (5.8-fold) polarized excitation. Consequently, and according to analytical calculations, we demonstrated that when excited with linearly polarized excitation, the metasolenoid had a B 1 efficiency 26 % higher when excited by the default circularly polarized excitation. Numerical simulations on voxel model showed that in presence of the resonator the B 1 efficiency gain normalized by the maximum local SAR was significantly improved when introducing the metasolenoid but the influence of the excitation polarization was reduced to a few percent.</div
Across ancient oceans: Eocene dispersal routes of Asian terrestrial mammals to Europe, Afro-Arabia and South America
No full textInternational audienceDuring the middle and late Eocene, Asian terrestrial mammals dispersed to Europe, while primates and rodents dispersed across the 500-to-2000 km wide Neotethys Ocean and the 1500-to-2000 km wide Atlantic Ocean to colonize Afro-Arabia and South America. This study explores how these mammals have achieved such remarkable and enigmatic dispersals. We present high-resolution paleogeographic models for the middle to late Eocene based on updated plate kinematic reconstructions, paleo-bathymetry and paleo-topography data. With this, we evaluate landmass configurations and connectivity that may have facilitated faunal exchanges from Asia toward Europe, Afro-Arabia, and South America and discuss dispersal mechanisms between these biogeographic provinces. Our reconstructions reveal that during the Bartonian (~40–38 Ma), an overland dispersal corridor between Asia and Balkanatolia became available to terrestrial mammals and acted as a pivotal pathway for Asian faunas dispersing toward western Europe and Afro-Arabia. We identified two Balkanatolian island-hopping routes across the Western Neotethys potentially enabling the dispersal of small-bodied Asian primates, rodents and artiodactyls to Afro-Arabia. Alternatively, these taxa may have rafted across the Central Neotethys. By ~34 Ma, Balkanatolia fully connected with Western Europe, opening a southern “Grande Coupure” route for Asian faunas. In the Atlantic, we identify long-distance rafting as the most plausible mechanism for the 40–34 Ma transoceanic dispersal of the Asian-originated primates and rodents from Afro-Arabia to South America despite the likely presence of sparse islands along the Walvis Ridge and the Rio Grande Rise
Wadsley-Roth FeNb11O29 as negative electrode material for lithium solid-state batteries
No full textInternational audienceFeNb 11 O 29 and Li 6 PS 5 Cl but revealed an interfacial degradation, with a resistive Li 2 S/oxide-rich interface, consistent with impedance growth. These findings highlight the critical role of microstructural and interfacial optimisation in the electrode composites and establish FeNb 11 O 29 as a promising candidate for high-rate solidstate batteries.</div
Les Critical Legal Studies : une entreprise radicale de « déjustification »
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Comparative Analysis of Irradiation Technologies on High-Density Polyethylene (HDPE) for Biopharmaceutical Applications
No full textInternational audienceThe impacts of e-beam and X-ray irradiation on medical-grade high-density polyethylene (HDPE) are compared with that of gamma irradiation to evaluate their potential effects on pharmaceutical applications. An extensive suite of analytical techniques was employed to evaluate the chemical and physical transformations of irradiated HDPE. Key findings indicated that irradiation did not significantly alter the mechanical properties, as tensile strength and elongation at break remained stable across all irradiation types and doses. Thermal analysis via Differential Scanning Calorimetry (DSC) revealed a slight decrease in melting temperature at higher doses, with an equivalent melting temperature peak observed for all three irradiation technologies. Electron Spin Resonance (ESR) detected alkyl and allyl radicals, which decreased over time, showing no significant differences attributable to irradiation type or dose. Colorimetric analysis indicated yellowing in the samples, linked to specific additives. The quantification of methionine oxidized byproducts by High-Performance Liquid Chromatography (HPLC) demonstrated that the oxidation potential was equivalent for the three irradiation technologies for HDPE. The study concluded that there was a lack of significant impact of irradiation technologies on several physical, chemical and mechanical properties of HDPE
Codes over the Dickson Near-Field of Order Nine
No full textInternational audienceA near-field is an algebraic structure akin to a division ring where distributivity is relaxed on one side. The smallest such object is the Dickson near-field of order nine. We lay the foundations of linear codes over that near-field. This includes a systematic form for their generator matrices based on a one-sided Gauss pivot algorithm. Dual codes are defined and a formula is given for the parity check matrix. LCD codes are characterized by a direct sum property. Self-orthogonal codes are classified in short lengths