Institut d'Histoire des Représentations et des Idées dans les Modernités

International audience

This work provides an overview of the recent advances in the field of two-photon absorbing chromophores active in the short-wavelength infrared (SWIR) spectral range. Herein the common strategies and main structure-property relationships that lead to near-infrared (NIR) electronic absorption of chromophores are described. A complete review of the molecules that feature two-photon absorption (2PA) beyond 1100 nm is presented for the purpose of further use in optical power limiting applications in the SWIR band. Recent progress in the development of optical power limiting in this particular spectral region is reported with emphasis on the use of the two-photon induced excited state absorption (ESA) process as an optical power limiting enhancer.

By using a combination of 32-bit and 64-bit floating point arithmetic, the performance of many sparse linear algebra algorithms can be significantly enhanced while maintaining the 64-bit accuracy of the resulting solution. These ideas can be applied to sparse multifrontal and supernodal direct techniques and sparse iterative techniques such as Krylov subspace methods. The approach presented here can apply not only to conventional processors but also to exotic technologies such as Field Programmable Gate Arrays (FPGA), Graphical Processing Units (GPU), and the Cell BE processor.

We demonstrate that a commercial confocal microscope can perform time-gated and long lifetime imaging in the μs to ms range under classical one photon or nonlinear two photon excitation.

BACKGROUND: Remote working (more appropriately, mandatory work from home) during the Covid-19 healthcare emergency has increased significantly. Amidst many critical issues, work-family conflict (WFC) remains a central topic, due to the hardships in separating different life domains, the pervasiveness of technology, and decreased opportunities for recovery, all considering new, emerging job demands. Although many studies have involved healthcare workers, less attention has been paid to technical-administrative staff (TA); moreover, previous studies about the impact of remote working on WFC have provided mixed results. OBJECTIVES: The study aims at examining the relationships between WFC and cognitive demands, off-work hours technology assisted job demands (off-TAJD) and recovery, in the TA of a hospital in northwest Italy. METHODS: A sample of 211 individuals (response rate of 58%), in line with the population, filled in an online self-report questionnaire in the second half of April 2020. RESULTS: Multiple regression analysis showed a positive relationship between WFC and perceived ICT stress, off-TAJD and cognitive demands, and a negative relationship with recovery. CONCLUSIONS: The results confirm the role of cognitive demands, technology overload and invasiveness, as potential predictors of WFC. The results also indicate the mitigating role of recovery, even in the face of a prolonged and forced experience of remote work. The study emphasises the need for transparent policies, based on trust, autonomy and right to disconnect, and the centrality of training, especially for supervisors, on topics such as evaluation of results, proper recovery management and correct use of technology.

La relation entre oralité et scripturalité au Moyen Âge est approchée par une analyse en corpus (137 textes, 4 millions de mots). Nous comparons les passages d’oral représenté (discours direct, théâtre, etc.) au reste des textes, en prenant en compte les 32 genres textuels qui les contextualisent. L’analyse factorielle des correspondances basée sur l’étiquetage morphosyntaxique met en évidence, comme première dimension de variation, un axe s’interprétant comme un gradient d’oralité, par rapport auquel chaque genre est automatiquement positionné. Elle distingue ses parties d’oral représenté et ses parties complémentaires. La statistique montre que parties d’oral représenté et parties complémentaires des textes sont distinguées, que le caractère littéraire ou oralisé d’un genre accentue ses traits d’oralité, que les façons de marquer la non-oralité sont plus dispersées et que certains genres occupent une position singulière (dialogue didactique, psautier).

Abstract Quantitative analysis of the literature of conference interpreting research (CIR) highlights interesting features of its historical evolution. Paradigm shifts in the seventies and late eighties have intensified its overall production and are associated with the disappearance of some major production centers and the emergence of others. The total population of authors has increased over the years, but only a few dozen have shown long-term productive research activity, and much CIR is conducted independently of any academic institution. Institutional and economic factors seem to account for limitations in the development of CIR so far. Empirical studies represent only a small proportion of the total CIR production, but their proportion in M.A. and graduation theses is far higher. Limitations of quantitative analysis without a qualitative component are highlighted, and suggestions are made for further explorations along the way.

Cloud applications based on the "Functions as a Service" (FaaS) paradigm have become very popular. Yet, due to their stateless nature, they must frequently interact with an external data store, which limits their performance. To mitigate this issue, we introduce OFC, a transparent, vertically and horizontally elastic in-memory caching system for FaaS platforms, distributed over the worker nodes. OFC provides these benefits cost-effectively by exploiting two common sources of resource waste: (i) most cloud tenants overprovision the memory resources reserved for their functions because their footprint is non-trivially input-dependent and (ii) FaaS providers keep function sandboxes alive for several minutes to avoid cold starts. Using machine learning models adjusted for typical function input data categories (e.g., multimedia formats), OFC estimates the actual memory resources required by each function invocation and hoards the remaining capacity to feed the cache. We build our OFC prototype based on enhancements to the OpenWhisk FaaS platform, the Swift persistent object store, and the RAM-Cloud in-memory store. Using a diverse set of workloads, we show that OFC improves by up to 82 % and 60 % respectively the execution time of single-stage and pipelined functions.

Myelodysplastic syndromes (MDSs) are clonal disorders of hematopoietic stem cells (HSCs) characterized by ineffective hematopoiesis. MDSs are responsible for 1 or several peripheral cytopenias. The evidence accumulated in recent years demonstrates that in addition to HSC defects, a particular role is also played by stromal microenvironment dysfunctions, which mediate the direct contact with hematopoietic precursor cells (HPCs). These interactions help regulate different adhesion-related processes, such as progenitor cell proliferation, apoptosis, clonogenic growth, and maintenance in in vitro cultures. As previously reported, these interactions are responsible for altering the microenvironment in MDS. Herein, we present a novel selection protocol for obtaining a standards-compliant mesenchymal stromal cell (MSC) preparation. This method allowed us to comparatively analyze 2 subpopulations of bone marrow MSCs (BM-MSCs) in terms of their adhesion profiles and growth abilities: BM-MSCs selected from MDS settings and their normal counterparts. Functional assays revealed that the MSCs from MDS are intrinsically pathological, thus showing a continuous decline of proliferation and a reduced clonogenic capacity during 14 days of culture and in the absence of signals from hematopoietic cells. The MSC growth defects were significantly correlated with decreases in CD44 adhesion molecules and CD49e (α5-integrin).

Since the discovery of their excellent performance as the light-absorbing semiconducting component in photovoltaic cells, the PbX3CH3NH3 (X = I, Br, Cl) perovskites have received renewed attention. The five polymorphs stable above 200 K - the tetragonal phases for X = I, Br, Cl and the cubic phases for X = I, Br - were studied using periodic DFT calculations involving hybrid functionals (PBE0 and HSE), employing Gaussian-type orbitals as well as plane waves and including relativistic effects (spin-orbit coupling). The influence of the halogen substitution and of the crystal phase on these properties is analysed by comparing the properties obtained in this study to the experimental ones and to the theoretical ones computed using other methods. We show that an accurate treatment of these systems requires the description of dispersion forces and spin-orbit coupling. The different time scales for the electronic and vibrational components of the polarizability inspire the hypothesis that several interfacial charge transfer mechanisms are encountered in the working principle of the photovoltaic devices involving these perovskite materials. The heavy elements in the structure (Pb, I) play a major role in the high polarizability and the low effective charge carrier masses and hence in the low exciton binding energies and the high charge mobility. This systematic work on the PbX3CH3NH3 family offers to theoreticians an overview of the landscape of quantum chemical methods to enable a reasonable choice of methodology for studying these systems.

in GM) in the near-infrared, making them ideal candidates for NIR-to-NIR two-photon microscopy imaging applications. We demonstrate that the molecular engineering of the hydrophilic/hydrophobic balance enables targeting of different cellular components, such as cytoplasm or cell membranes. Addition of appropriate substituents provides the molecule with high-water-solubility, affording efficient two-photon probes for angiography.

The widespread use of low-cost environmental monitoring systems, together with recent developments in the design of Internet of Things architectures and protocols, has given new impetus to smart city applications. Such progress should, in particular, considerably improve the fine characterization of a wide range of physical quantities within our cities. Indeed, the cost-effectiveness of these emerging sensors combined with their reduced size allows for high-density deployments resulting in higher spatial granularity. In this article, we briefly present the 3M'Air project that aims to explore the potential of participatory citizen measures using low-cost sensors in order to improve the local knowledge of air quality and temperature and then bridge the gap between individual exposure and regional measurements. We then present the design, implementation, and evaluation of our low-cost, small-size wireless sensor network (WSN)-based participatory monitoring system. This system is composed of mobile sensing nodes measuring temperature, humidity, and a number of pollutants (NO2, PM1, PM2.5, and PM10). The collected data are sent to a server for analysis and building temperature and air quality maps. To validate our platform, we have carried out multiple tests to compare our sensor nodes to reference stations and to each other. We have also evaluated the energy consumption of our nodes under different configurations. The results are satisfactory and show that our nodes can be used in environmental participatory monitoring.

International audience

On-line analytical processing (OLAP) provides tools to explore and navigate into data cubes in order to extract interesting information. Nevertheless, OLAP is not capable of explaining relationships that could exist in a data cube. Association rules are one kind of data mining techniques which finds associations among data. In this paper, we propose a framework for mining inter-dimensional association rules from data cubes according to a sum-based aggregate measure more general than simple frequencies provided by the traditional COUNT measure. Our mining process is guided by a meta-rule context driven by analysis objectives and exploits aggregate measures to revisit the definition of support and confidence. We also evaluate the interestingness of mined association rules according to Lift and Loevinger criteria and propose an efficient algorithm for mining inter-dimensional association rules directly from a multidimensional data.

Phyllotaxis, the spatio-temporal pattern of organogenesis at the shoot apical meristem, emerges in large part from inhibitory fields consisting in auxin-depleted areas centered on organs. We recently demonstrated the existence of an additional hormone-based inhibitory field generated by Arabidopsis Histidine Phosphotransfer Protein 6 (AHP6), an inhibitor of cytokinin signaling. We have shown that the spatio-temporal distribution of AHP6 in the meristem is essential for optimizing the rhythmicity of organ initiation. Here, we further analyzed AHP6 expression using fluorescent whole mount mRNA in situ hybridization and demonstrate a precise control of AHP6 level and expression domain over time. While we previously showed a regulation of AHP6 directly downstream of auxin, we show here that AHP6 transcription is unlikely influenced by cytokinin distribution in the meristem. Finally, we provide evidence that cytokinins and auxin might act synergistically during organ initiation, providing a plausible explanation for how AHP6 regulates phyllotaxis.

Pour convaincre les étudiants de l’intérêt de la déverbalisation, il importe de les sensibiliser au préalable au fait qu’en traduisant, ils accomplissent une tâche communicationnelle au service d’un client et d’un auteur. Sur cette base de loyauté professionnelle, ils comprennent l’intérêt de la correction de certaines erreurs et maladresses techniques. En interprétation, l’existence de celles-ci apparaît rapidement aux yeux des élèves-interprètes du fait de leurs propres difficultés. En traduction, l’expérimentation pédagogique aide à montrer que la variabilité est une partie intrinsèque de la production du discours, que l’auteur d’un texte n’en est pas nécessairement le maître absolu, et qu’il peut souhaiter le modifier s’il en a la possibilité. Cette expérimentation, ainsi que les explications théoriques, qui n’excluent pas les aspects spécifiques par langues et par paires de langues, ont un effet sensibilisateur, mais un suivi concret dans la pratique est indispensable.

The first pyclen based ligand bearing two picolinate intra-ligand charge transfer transition antennae and one acetate arm organized in a dissymmetric manner was synthesized for Eu(iii) and Sm(iii) complexation. The europium complex presents an excellent brightness and biphotonic imaging of T24-cells has been performed using Eu(iii) and the less common Sm(iii) bioprobes.

This study aimed at developing a new methodology for measuring tin isotope compositions in geological and cosmochemical materials.

We revisit the analysis of the Non-linear Thin Shell Instability (NTSI) numerically, including magnetic fields. The magnetic tension force is expected to work against the main driver of the NTSI -- namely transverse momentum transport. However, depending on the field strength and orientation, the instability may grow. For fields aligned with the inflow, we find that the NTSI is suppressed only when the Alfv\'en speed surpasses the (supersonic) velocities generated along the collision interface. Even for fields perpendicular to the inflow, which are the most effective at preventing the NTSI from developing, internal structures form within the expanding slab interface, probably leading to fragmentation in the presence of self-gravity or thermal instabilities. High Reynolds numbers result in local turbulence within the perturbed slab, which in turn triggers reconnection and dissipation of the excess magnetic flux. We find that when the magnetic field is initially aligned with the flow, there exists a (weak) correlation between field strength and gas density. However, for transverse fields, this correlation essentially vanishes. In light of these results, our general conclusion is that instabilities are unlikely to be erased unless the magnetic energy in clouds is much larger than the turbulent energy. Finally, while our study is motivated by the scenario of molecular cloud formation in colliding flows, our results span a larger range of applicability, from supernovae shells to colliding stellar winds.

International audience