Université Savoie Mont Blanc
Recent publications
We realized a time-domain simulator based on the electrodynamics of Cooper pairs and quasiparticles in Josephson junctions. The tool, based on the charge carriers' densities of states described by the Werthamer and Harris formalisms of Bardeen-Cooper-Schrieffer (BCS) theory, allows to analyze the behavior of current- or voltage-controlled Josephson junction-based circuits for any signal waveform, at a physical temperature comprised between the absolute temperature and the critical temperature. The simulator can account for I-V curve hysteresis depending on the McCumber parameter, or Shapiro and photo-assisted steps in the presence of a monochromatic microwave signal. We used the simulator to assess the behavior of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based Josephson junctions at THz frequencies by taking into account the presence of the two anisotropic gaps of MgB2.
Four previously unrecognized neotectonic fault scarps in southwest Namibia are described. These relatively straight, simple but segmented structures are 16–80 km long and have measured vertical separations of 0.7–10.2 m. We estimate that each is capable of producing earthquakes of Mw 6.4 or greater, indicating that large earthquakes may occur despite limited cumulative displacement. There is strong evidence that some of these scarps were formed by repeated earthquakes. Comparison with aeromagnetic and geological maps reveal that the normal faults reactivate major crustal weaknesses that are orientated north‐south and northwest‐southeast and perpendicular to the local gravitational potential energy gradient. The presence of these structures in an area with a limited record of instrumental seismicity suggests that the Mmax of this region may be much larger than generally assumed. They highlight the necessity of incorporating information from fault studies into probabilistic seismic hazard assessments in this region, in a similar way to other stable continental regions such as Australia. The fact that such major structures have gone hitherto unrecorded suggests significant further research is needed to characterize these sources of hazard. The identification of an apparent cluster of large magnitude neotectonic earthquakes in the area may be related to the exceptional preservation potential of scarps rather than indicating an area of comparatively rapid deformation. If this interpretation is correct, then these scarps represent an important indication of the potential seismic hazard across the region, and the occurrence of infrequent large‐magnitude seismicity on similar structures should be considered throughout southwestern Africa.
A petrophysical model describing spectral induced polarization has been developed for clay-rocks accounting for the Maxwell Wagner polarization. It is also used to connect the complex conductivity to the relative permeability of the material. This model is applied to the Callovo-Oxfordian (COx) clay-rock of the Paris Basin (France) where the Meuse/Haute-Marne Underground Research Laboratory (URL) is located. Laboratory experiments are performed using 8 clay-rock cores to study the effect of desiccation on their spectral induced polarization response. The measurements are performed along the foliation plane. Complex conductivity spectra are performed over the frequency range 1 mHz to 45 kHz. These spectra are fitted with a double Cole Cole model to extract the evolution of the Cole Cole parameters with the saturation during the desiccation process. The low-frequency Cole Cole model corresponds to induced polarization phenomena while the high-frequency Cole Cole model corresponds to the Maxwell-Wagner contribution. We obtain the value of the first and second Archie’s exponents and we check the relationship between the surface conductivity and the cation exchange capacity of the clay-rocks. We are also able to connect the relative permeability curve to the second (saturation) Archie’s exponent. The monitoring of the complex conductivity can be used to predict how the permeability of the clay-rock formation changes with the water content.
Static measurements are clinically useful in characterising foot morphology, but it remains unclear to what extent it can influence dynamic lower limb performance. Therefore, the purpose of this study was to investigate if foot posture or foot morphology deformation relates to ankle plantarflexion isokinetic strength and specific kinetics variables during jumping using principal component analysis (PCA). Thirty-eight physically active participants performed drop vertical jump (DVJ) onto force platforms and ankle plantarflexion contractions in different modalities on an isokinetic dynamometer. Foot posture was assessed using the Foot Posture Index-6 item, whereas foot one-, two- and three-dimensional morphological deformation was calculated using the Arch Height Index Measurement System. A PCA was applied to the ankle plantarflexion and kinetics performance data and correlations between PCs and foot parameters measured. The analysis revealed 3 PCs within the ankle plantarflexion and DVJ kinetics variables that captured more than 80% of the variability within the data, but none of them showed significant correlations (r ≤ 0.27) with any foot variables. While foot posture and foot morphological deformation remain of interest in characterising foot morphology across individuals, these findings highlight the lack of clinical relevance of these static evaluations at characterising lower limb and ankle performance.
The multifunctional materials for application in organic light-emitting devices (OLEDs) based on a single structural motif are very desired but quite rare species. Such structures allow simplifying the chemical variety within OLED heterostructures and thus reducing their cost, manufacturing time, and logistic efforts. In this paper, we report the 9-(2,3,5,6-tetrafluoro-4-vinylphenyl)carbazole molecule (Cz4FS) utilized as a fluorescent emitter, host material for quantum dot based OLEDs (QLEDs), acceptor part of the exciplex active layer, and monomer that can be used for the preparation of emissive polymers and copolymers. The external quantum efficiency (EQE) of the corresponding fluorescent OLED based on a Cz4FS single emitter doped into a 1,3-bis(carbazol-9-yl)benzene matrix is 4.2%, which is close to the theoretical limit and maximum brightness at the level of 3600 cd/m 2. An OLED based on exciplex emission obtained utilizing Cz4FS as an acceptor demonstrates higher efficiency (5.3%) and much higher brightness near 25 000 cd/m 2. A QLED based on Cz4FS as a host for CdSeS/ZnS core−shell quantum dots demonstrates excellent energy transfer from the Cz4FS matrix that results in a clear spectrum of quantum dots with an EQE of 2.3%, maximum of 19 000 cd/m 2 , and narrow spectral distribution. An OLED based on a Cz4FS-based polymer and copolymer demonstrates not extraordinary efficiency but low-efficiency roll-off in a wide range of current densities.
Purpose: In children with cerebral palsy (CP), with impaired trunk control and toe-walking, trunk-focused rehabilitation (TFR) based on postural activities was hypothesized to improve trunk postural control, early trunk deceleration, and ankle dorsiflexion braking during walking. Methods: Seventeen children with CP (5-12 years) walking autonomously were randomly assigned to TFR and then usual rehabilitation (TFR-UR) or vice versa (UR-TFR). Results: Only after TFR was significant improvements in (i) the Trunk Control Measurement Scale score, postural sway on an unstable sitting device and standing, and (ii) early sternal and sacral decelerations and coupled negative ankle power due to plantar flexors. Conclusion: TFR improves trunk dynamics and consequently improves coupled toe-walking.
The Ganaveh earthquake on 2021 April 18 (Mw 5.8) occurred in the southwest of the Dezful embayment of the Zagros Mountain belt, Iran, as a mainly compressive event. The InSAR coseismic displacement maps reveal a maximum of 17 cm of surface displacement in the satellite line of sight direction. InSAR inversion indicates a low-angle NE-dipping causative fault plane with a maximum slip of 95 cm at ∼6 km depth. It highlights the occurrence of the Ganaveh earthquake within the competent layers of the Zagros sedimentary cover, beneath the Gachsaran formation. A slight sinistral slip component (2.9 cm) is retrieved which is compatible with the USGS focal mechanism. Time series analysis of SAR images after the mainshock until the end of 2021 indicates a maximum of 7 cm of postseismic surface displacement with a similar strike and pattern as the coseismic phase. This similarity and the distribution of aftershocks suggest an afterslip mechanism for the postseismic phase. The inversion of postseismic cumulative displacement evaluates a maximum of 30 cm slip at a depth of ∼5 km along the coseismic causative fault. A regional compressional stress regime (N041° E for the direction of the σ1 stress axis) is constrained by using the focal mechanisms of 39 earthquakes occurring between 1968 and 2021, including the Ganaveh mainshock and its five larger aftershocks. Applying this direction of compression on the Ganaveh fault plane also results in a minor sinistral movement, consistent with the geodetic results. The relocated mainshock and aftershocks as well as our InSAR coseismic displacement situations on the hanging wall of the Zagros Foredeep fault highlight it as the causative fault of the Ganaveh earthquake. To fit the geometry of the Ganaveh rupture plane with the Zagros Foredeep fault, we modeled a listric fault plane and its slip distribution using the available geological data. The retrieved slip variation on the listric plane is in close agreement with the slip pattern on the modeled planar geometry. The low dip angle of the rupture plane combined with a listric geometry highlights the thin-skin characteristics of the Zagros Foredeep fault as the causative fault of the Ganaveh earthquake. The occurrence of this moderate magnitude earthquake on the Zagros Foredeep fault underlines its role as the western structural boundary for the recurrence of Mb > 5 events in the Dezful embayment.
The origin of white calcite silts forming 0.5 to 3-cm-thick lenses in alluvial fan deposits 14 C-dated to the Last Glacial Maximum in the Dronne Valley (Dordogne, southwest France) is investigated using microscopic imagery, chemistry, and O and C stable isotopes. The calcite silts, composed mainly of aggregates of 3-5-μm euhedral crystals, do not resemble secondary precipitations of pedological origin because of the strata-like pattern and the lack of clearly identifiable biological structures. Their association with evidence of ice formation in the soil (platy structure, involutions) suggests that they were deposited in a deep seasonal frost context. Their isotopic composition differs significantly from those of detrital carbonates and of Holocene bioprecipitation and seems to be best explained by precipitation under closed-system conditions. Calculation of the isotopic composition of calcite that would have formed in equilibrium with groundwater of regional LGM aquifers provides values that are in the range of the composition of the calcite silts for a precipitation temperature close to 0°C. Therefore, these deposits are interpreted as cryogenic calcite precipitated from waters close to saturation with respect to calcite freezing at the base of/within icings or within the ground, possibly from frost blisters. Similar calcite precipitation at the outlet of karstic springs may have been abundant in the calcareous terrains of southwest France during the LGM, although still unrecognized in the geological record.
Detrital 10Be from continental river sands or submarine sediments has been extensively used to determine the average long-term denudation rates of terrestrial catchments, based on the assumption that the rate of cosmogenic nuclide production by the interaction of source rocks with cosmic radiation balances out the loss of these nuclides by surface denudation. However, the 10Be signal recorded in sediments may be affected at the source by the response time of mountainous catchments to high-frequency forcings. In addition, transient sediment storage in piedmonts, alluvial plains and lakes or near the coast may also induce a difference between the erosive signal and its record in the sedimentary sink. Consequently, a significant part of the signal recorded in shallow-water sediments can be lost, as deep marine sediments may simultaneously record a signal coming from newly eroded source rocks along with one coming from the destabilization of previously deposited sediments. In this paper, we use the landscape evolution model Badlands to simulate erosion, deposition and detrital 10Be transfer from a source-to-sink sedimentary system (the Var River catchment, southern French Alps) over the last 100 kyr. We first compare model-based denudation rates with the ones that would be extracted from the 10Be record of local continental sediments (equivalent to river sands) and from sediments deposited offshore over time in order to examine if this record provides an accurate estimate of continental denudation rates. Then, we examine which conditions (precipitation rate, flexure, ice cover) satisfy published measured river incision rates and 10Be concentration in submarine sediments. Our results, based on the Var catchment cosmic ray exposure dating and modelling indicate that, while river sands do accurately estimate the average denudation rate of continental catchments, this is much less the case for deep submarine sediments. We find that deep-sea sediments have a different and often much smoother 10Be signature than continental ones and record a significant time lag with respect to imposed precipitation rate changes, representing the geomorphological response of the margin. A model which allows us to fit both measured 10Be concentration in marine sediments and river incision rates on land involves an increase in precipitation rates from 0.3 to 0.7 m yr−1 after 20 ka, suggesting more intense precipitation starting at the end of the Last Glacial Maximum.
Poly(arylene ether sulfone)-derived single-ion conducting (SIC) block copolymers are promising candidates as (solid) electrolytes for lithium-metal batteries owing to their high electrochemical stability and structural versatility. When incorporating small organic molecules (e.g., organic carbonates such as ethylene carbonate, EC), high ionic conductivities can be reached even at ambient temperatures. To gain further insights into the impact of the polymer backbone chemistry on the physicochemical and electrochemical properties, a series of SIC multiblock copolymers were synthesized comprising bisphenol-derived monomers for the ionophilic block. All of these SIC block copolymers (containing 55 wt % of EC) show high ionic conductivities. Remarkably, though, the electrochemical stability toward oxidation is slightly decreasing for an increasing size of the substituent at the central carbon atom of the bisphenol monomer, whereas the overpotential for lithium stripping and plating is decreasing. These results highlight the importance of carefully designing the polymer backbone for high-performance lithium battery electrolytes.
Understanding the mechanisms underlying species distributions and coexistence is both a priority and a challenge for biodiversity hotspots such as the Neotropics. Here, we highlight that Müllerian mimicry, where defended prey species display similar warning signals, is key to the maintenance of biodiversity in the c. 400 species of the Neotropical butterfly tribe Ithomiini (Nymphalidae: Danainae). We show that mimicry drives large-scale spatial association among phenotypically similar species, providing new empirical evidence for the validity of Müller's model at a macroecological scale. Additionally, we show that mimetic interactions drive the evolutionary convergence of species climatic niche, thereby strengthening the co-occurrence of co-mimetic species. This study provides new insights into the importance of mutualistic interactions in shaping both niche evolution and species assemblages at large spatial scales. Critically, in the context of climate change, our results highlight the vulnerability to extinction cascades of such adaptively assembled communities tied by positive interactions. KEYWORDS biodiversity hotspot, climatic niche, community composition, evolutionary convergence, extinction cascade, Müllerian mimicry, mutualistic interactions, Neotropical butterflies, spatial co-occurrence, species assemblages
Background: This study aimed to determine the effects of a running sprint interval training protocol (R-SIT) on the sprint acceleration mechanical properties and jump performance. Eleven young male basketball players performed 6 R-SIT sessions for 2 weeks. Methods: Each session consisted of 30-second running bouts repeated 4 to 7 times interspersed by 4 minutes of recovery. Performance was assessed from the individual power-force-velocity profiles (PVFP) over a 20-m sprint and from a countermovement jump at baseline (PRE) and after two weeks of training (POST). Results: Sprint time decreased by 2% over the first 5 and 10 meters (P<0.01) while no significant changes in the time at 20 meters (-0.8%, P=0.09) nor in maximal velocity (-1%, P=0.31) were detected. The average PFVP showed an increase in theoretical maximal force and power output of 5 and 4%, respectively (P<0.05), with no change in theoretical maximal speed (P=0.26). Jump height and power also increased after training (5 and 3% respectively, P<0.01). Players improved their maximal sprint distance covered during the 30-second bouts and became more fatigue-resistant to long sprint events. Conclusions: Six sessions of R-SIT helped to enhance short sprint times, acceleration and power output.
We deployed a dense geodetic and seismological network in the Atacama seismic gap in Chile. We derive a microseismicity catalog of >30,000 events, time series from 70 GNSS stations, and apply a transdimensional Bayesian inversion to estimate interplate locking degree. We identify two highly locked regions of different sizes whose geometries appear to control seismicity patterns. Interface seismicity concentrates beneath the coastline just downdip of the highest locking. A region of lower interplate locking around 27.5ºS coincides with higher seismicity levels, a high number of repeating earthquakes and events extending further towards the trench. Having shown numerous signs of aseismic deformation (slow-slip events and earthquake swarms), this area is situated where the Copiapó Ridge is subducted. While these findings suggest that the structure of the downgoing oceanic plate prescribes patterns of interplate locking and seismicity, we note that the Taltal Ridge further north lacks a similar signature.
In the current study, we used a multi-method approach to understand the quality of math homework-helping interactions between parents and their children and how parents’ and children’s own math achievement and math anxiety relate to the quality of the interaction. Forty Canadian parents and their children (ages 10–12 years; grades 5 to 7) completed self-report measures of math and general anxiety. Parents and children completed standardized assessments of math achievement and were then recorded as they engaged in a simulated math homework interaction. Coders assessed parent–child interaction quality during the interaction. Parent–child dyads generally performed well on the simulated math homework task. Nevertheless, task performance was correlated with the quality of the interaction, with high-quality interactions associated with high accuracy on the math task. Furthermore, the variability in the quality of the interaction was associated with parents’ and children’s math achievement and with the math anxiety of the children, but not the parents. Identifying the elements that influence parent–child interactions in math-related situations is essential to developing effective interventions to scaffold children’s math learning and attitudes.
Background HPV vaccine coverage in France remained lower than in most other high-income countries. Within the diagnostic phase of the national PrevHPV program, we carried out a mixed methods study among school staff to assess their knowledge, beliefs and attitudes regarding HPV, HPV vaccine and vaccination in general, and regarding schools’ role in promoting HPV vaccination. Methods Middle school nurses, teachers and support staff from four French regions participated between January 2020 and May 2021. We combined: (i) quantitative data from self-administered online questionnaires (n = 301), analysed using descriptive statistics; and (ii) qualitative data from three focus groups (n = 14), thematically analysed. Results Less than half of respondents knew that HPV can cause genital warts or oral cancers and only 18% that no antiviral treatment exists. Almost 90% of the respondents knew the existence of the HPV vaccine but some misunderstood why it is recommended before the first sexual relationships and for boys; 56% doubted about its safety, especially because they think there is not enough information on this topic. Schools nurses had greater knowledge than other professionals and claimed that educating pupils about HPV was fully part of their job roles; however, they rarely address this topic due to a lack of knowledge/tools. Professionals (school nurses, teachers and support staff) who participated in the focus groups were unfavourable to offering vaccination at school because of parents’ negative reactions, lack of resources, and perceived uselessness. Conclusions These results highlight the need to improve school staff knowledge on HPV. Parents should be involved in intervention promoting HPV vaccination to prevent their potential negative reactions, as feared by school staff. Several barriers should also be addressed before organizing school vaccination programs in France.
Outer Albanides experienced a seismic sequence starting on 21 September 2019, with an Mw 5.6 earthquake, considered a foreshock, and culminated with the mainshock on 26 November 2019, followed by a paramount aftershock activity. We propose a model for the co-seismic slip distribution using InSAR, permanent, and campaign GNSS measurements. We tested two hypotheses: an earthquake on a thrust plane with the direction N160° and along with a back thrust. By varying the depth and dip angle for the first hypothesis and only the dip angle for the second hypothesis, we concluded the optimal solution is a blind thrust at a 15-km depth dipping eastward 40°, a maximum slip of 1.4 m, and an Mw 6.38. A GNSS time series obtained after 2020 shows two slow slip events (SSEs): the first one is 200 days after the mainshock up to 26 days, and the second one is 300 days after the mainshock up to 28 days. We tested three hypotheses: SSE along the basement thrust where the mainshock has been localized, SSE along the flat formed by the detachment layer of the cover, and SSE along these two faults. We concluded that SSE occurred along the detachment layer or along the two faults.
Premise: Divergence of floral morphology and breeding systems are often expected to be linked to angiosperm diversification and environmental niche divergence. However, available evidence for such relationships remain idiosyncratic, due to different taxonomic, geographical and time scales. The Palearctic genus Helianthemum shows the highest diversity of the family Cistaceae in terms of breeding systems, floral traits and environmental conditions, resulting from three recent evolutionary radiations occurred since the Late Miocene. Here, we investigate the tempo and mode of evolution of floral morphology in the genus, and its link with species diversification and environmental niche divergence. Methods: We quantified eighteen floral traits from 83 taxa and applied phylogenetic comparative methods using a robust phylogenetic framework based on genotyping by sequencing data. Results: The results revealed three different floral morphologies, putatively related to three different breeding systems: (i) type I, characterized by small flowers without herkogamy and low pollen to ovule ratio; (ii) type II, represented by large flowers with approach herkogamy and intermediate pollen to ovule ratio; and (iii) type III, featured by small flowers with reverse herkogamy and the highest pollen to ovule ratio. Each morphology has been highly conserved across each radiation and has evolved independently of species diversification and ecological niche divergence. Conclusions: The combined results of trait, niche and species diversification ultimately recovered a pattern of potentially non-adaptive radiations in Helianthemum and highlight the idea that evolutionary radiations can be decoupled from floral morphology evolution even in lineages that diversified in heterogeneous environments as the Mediterranean Basin. This article is protected by copyright. All rights reserved.
Dykes are magma-filled fractures propagating through the brittle crust. Understanding the physics of dyking process is essential to mitigate the volcanic hazard associated with the opening of new eruptive fissures at the surface. Often, physics-based models view either fracturing of the host rock or viscous flow of the magma as the dominating energy sink during dyke propagation. Here, we provide a numerical model that captures the coupling of fracturing at the crack tip and the transport of a viscous fluid. Built with the boundary element technique, our model allows for computation of the shape and velocity of a growing fluid-filled crack accounting for the viscosity of the fluid: the fluid flow induces a viscous pressure drop acting at the crack walls, and modifies the shape of the crack. The energy conservation equation provides the constraints to solve for the crack growth velocity, assuming that brittle fracturing and viscous flow are the main processes that dissipate energy. Using a parameter range that represents typical magmatic intrusions, we obtain crack shapes displaying some typical characteristics, including a tear-drop head and an open tail that depend on rock rigidity,magma viscosity, and buoyancy. We show that viscous forces significantly contribute to the energy dissipated during the propagation of magmatic dykes. Applied to the 1998 intrusion at Piton de la Fournaise (La Réunion Island), we provide ranges of dyke lengths and openings by adjusting the numerical velocity to the one deduced from the migration of volcano-tectonic events.
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2,506 members
Arnaud Carre
  • Psychology Area
Fabien Arnaud
  • EDYTEM Laboratory of Environment Dynamics and Territories of the Mountain
Pascal Hot
  • Psychology Area
Eric Benoit
  • Engineering Sciences Area
Chambéry, France