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Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon
No full textInternational audienceZircon (ZrSiO4) is the oldest-known mineral of Earth and an ubiquitous silicate in geochronology. More specifically, the accumulation of alpha decay damage in zircon over time significantly affects its physical and chemical properties, and can lead to a disturbance of the ages measured in this mineral. Therefore, analytical tools that enable comprehensive structural and chemical information at the nanoscale in this compound are highly sought after. In this context, we explore the electron energy-loss fine structures resulting from the excitation of O1s and Si2p core electrons in zircon, which are interpreted from ab initio calculations in a single-particle framework. An excellent agreement is obtained between the experimental and calculated fine structures, emphasizing the large distortion of the final electronic states induced by the core-hole potential. The O-K edge is particularly rich in information, with intense peaks dominated by O2p - Zr4d and O2p - Si3sp hybrids. This work suggests that the near-edge structures from the O1s and Si2p excitations accessible from electron energy-loss spectroscopy or X-ray absorption spectroscopy could be used as tools to follow, interpret and understand structural and chemical modifications in zircon subject to natural radiation damage. We illustrate the potential of this approach through the evolution of near-edge fine structures in a zircon sample that exhibits a locally amorphized zone formed by ultrafast laser excitation
Untangling GPU Power Consumption: Job-Level Inference in Cloud Shared Settings
No full textInternational audienceAs the demand for AI-driven workloads increases, the energy consumption of Graphics Processing Units (GPUs) devices has come under intense scrutiny, particularly in hyperscale data centers where large numbers of accelerators are centralized and leased to diverse clients.In the context of cloud hyperscalers, GPUs power monitoring presents several challenges that vary depending on the product offered. The monitoring capabilities of physical devices may be limited or even absent for some products. However, given the substantial energy demands of GPUs, power monitoring is essential for both cloud providers and clients. Operators require tools to manage power distribution effectively, such as balancing workloads across Power Distribution Units (PDUs), while clients need visibility into power usage to optimize their workloads for energy efficiency.To address these challenges, we propose methods for estimating the energy consumption of jobs running on GPU devices in cloud environments, spanning from shared and managed offerings like ML-as-a-Service (MLaaS) to less managed products (e.g., Infrastructure-as-a-Service (IaaS)). Our models demonstrate the benefits of sharing GPUs for small AI workloads, as well as the current sub-optimal utilization of GPUs in cloud hyperscalers, based on insights from an IaaS GPU cluster
Management and survival of patients with cancer of unknown primary discussed by a French national multidisciplinary tumour board: a retrospective analysis
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"Du désordre dans une société trop ordonnée" : Censure, adaptation et création dans le théâtre argentin de la dernière dictature
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Les structures baptismales en Gaule hors la ville (villae, castra) : retour sur les problèmes d’identification des structures et des contextes d’implantation (Ve-VIIe siècles)
No full textCet article s’intéresse aux structures baptismales implantées hors du cadre urbain en Gaule entre le Ve et le VIIe siècle, notamment dans des villae ou des castra. Il interroge les difficultés d’identification archéologique de ces édifices ainsi que les incertitudes pesant sur leur statut, leur fonction et leur relation à l’épiscopat. Loin d’être marginales, ces fondations témoignent d’une dynamique chrétienne enracinée dans des réalités locales, souvent en lien avec des réseaux aristocratiques ou des noyaux d’habitat secondaire. La diversité des contextes invite à dépasser les oppositions entre ville et campagne, et à repenser les modalités d’implantation et de diffusion du christianisme. L’article souligne enfin la nécessité d’éclairer les formes d’encadrement religieux de ces sanctuaires, avant la normalisation conciliaire du VIe siècle, et appelle à de nouvelles enquêtes croisant données archéologiques, topographiques et contextuelles
Most incompatible measurements and sum-of-squares optimisation
No full textMeasurement incompatibility, or joint measurability, is a cornerstone of quantum theory and a useful resource. For finite-dimensional systems, quantifying this resource and establishing universal bounds valid for all measurements is a long-standing problem. In this work, we exhibit analytical universal parent measurements giving access to bounds that beat the state of the art. In particular, we can show that, for relevant robustnesses, sets of anticommuting observables give rise to the most incompatible dichotomic measurements. We also formalise the construction of such universal parent measurements in the framework of sum-of-squares optimisation and obtain preliminary numerical results demonstrating the power of the method by improving on our own analytical values. All results find direct application for demonstrating genuine high-dimensional steering, that is, certifying the dimensionality of a quantum system in a one-sided device-independent manner
Integrated modelling of sediment and organic carbon fluxes in a large catchment: quantifying riverine contributions to the Mediterranean Sea
No full textInternational audienceWithin the Land Ocean Aquatic Continuum, the export of dissolved and particulate organic carbon (DOC, POC) is crucial for various processes in aquatic ecosystems and a primary source of greenhouse gas emissions in hydrosystems. Quantifying DOC and POC fluxes at high spatiotemporal resolution is complex because numerous sources and processes influence their dynamics, including climate, geological, and anthropogenic activities. Such quantifications at the catchment scale can be performed using hydrological models that consider OC processes. This study employed the Soil and Water Assessment Tool -Carbon (SWAT-C) to simulate OC dynamics in the large Mediterranean catchment of the Rhône River from 2002 to 2020. We represent hydrological and sediment fluxes at the catchment scale by accounting for sub-catchment diversity and dam operations. The average resulting exports reach 5.52 Mt y -1 , 78.8 kt y -1 , and 95.1 kt y -1 with 54.4%, 71.5%, and 44.3% exported during the highest discharges for sediment, POC, and DOC, respectively. The contributions of the southern sub-basins to POC and DOC fluxes are significant, while the northern sub-basins do not show significant patterns. Regarding OC quality, the proportions of labile/refractory OC at the Rhône outlet are 85/15 and 5/95 for POC and DOC, respectively. Global changes could alter flows, such as the labile/refractory OC proportions, which should be quantified using the tool developed in this article to anticipate their impacts on biogeochemical dynamics in the Mediterranean Sea. Finally, our study demonstrates the potential and limitations of SWAT-C for modelling OC dynamics in a large Mediterranean catchment under multiple anthropogenic pressures
Combinatorial and algorithmic analysis of oriented hierarchies in statistical implicative analysis
No full textInternational audienceThis paper introduces a novel and more efficient method for constructing oriented hierarchies within the framework of Statistical Implicative Analysis. The primary focus of this study is the computational complexity of the original algorithm proposed by Gras, whose cubic time complexity is established in this work. To address this limitation, a detailed combinatorial analysis of hierarchical structures is performed, leveraging tools from analytic combinatorics. This methodology facilitates the enumeration of the number of possible configurations as a function of input size and enables the investigation of both the depth and width characteristics of the hierarchy’s block structure. This study then proposes a reconstruction algorithm based on a formal correspondence between the statistical implication graph and the oriented hierarchy. The proposed method achieves quadratic worst-case complexity, thereby resulting in a substantial improvement in computational performance. Moreover, the analytic framework also makes it possible to characterise the average-case behaviour of the algorithm. The findings of the comparative computational experiments demonstrate the clear advantage of the proposed method over Gras’s algorithm, both in terms of execution time and overall algorithmic efficiency