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Miner dans le désert : logiques d’association et formes spatiales de la mine artisanale en Namibie
No full textInternational audienceThis article examines the social and spatial organization of artisanal gemstone mining in Namibia, shedding light on a largely under-researched area. It delves into the power dynamics and experiences of precarity faced by miners, highlighting the associative strategies they employ daily. These strategies are shown to be responses to specific situations, shaped by various factors, with the miners' agency playing a significant yet not dominant role. Drawing on fieldwork conducted at two major artisanal mining sites in Namibia, Xoboxobos and Tubusis, the article utilizes semi-structured interviews and participant observation to propose a typology of associative modes, identifying the influential factors and organizational choices of the miners. By providing a comprehensive overview, this article paves the way for future research on the artisanal mining sector in Namibia, opening new dimensions and perspectives.Cet article examine l'organisation sociale et spatiale de l'exploitation artisanale des pierres semi-précieuses en Namibie, mettant en lumière un domaine largement sous-exploré. Il s'intéresse aux dynamiques de pouvoir et aux expériences de précarité rencontrées par les mineurs, en soulignant les stratégies associatives qu'ils mettent en œuvre au quotidien. Ces stratégies apparaissent comme des réponses à des situations spécifiques, façonnées par divers facteurs, où le libre arbitre des mineurs joue un rôle significatif mais non dominant. En s'appuyant sur un travail de terrain mené sur deux principaux sites miniers artisanaux en Namibie, Xoboxobos et Tubusis, cette analyse se base sur des entretiens semi-directifs et une observation participante pour proposer une typologie des modes d'association, identifiant les facteurs influents et les choix organisationnels des mineurs. Ainsi, en fournissant une vue d'ensemble et une analyse située, cet article ouvre la voie à de futures recherches sur le secteur minier artisanal en Namibie
Solar H2 production by a perovskite/silicon tandem cell using urea oxidation
No full textInternational audienceTransition metal-based catalyst layers for hydrogen evolution (HER) and urea oxidation (UOR) are coupled to a perovskite/silicon (PK/Si) tandem photovoltaic (PV) cell and tested for H2 production from urea-rich alkaline electrolytes under simulated sunlight. Results show that UOR significantly boosts H2 evolution performance by allowing operation at the maximum power point of the PK/Si PV under solar illumination, which is not the case when the oxygen evolution reaction (OER) occurs. This assembly maintains stable performance over two days. The high concentration of produced NO2− confirms the occurrence of urea overoxidation pathways during UOR
Putting earthworm conservation on the map: Shortfalls and solutions for developing earthworm conservation
No full textInternational audienceEarthworms are keystone organisms that influence both soil function and community assembly of other soil organisms. However, soils are increasingly threatened by global change, so there is an urgent need to consider earthworms in conservation strategies. Earthworm monitoring has been promoted in numerous European and country research programs, and the global interest in earthworm conservation is rising, resulting in a rapid increase in the availability of earthworm data. However, most research focuses on a limited number of local-scale indicators, mainly based on abundance, biomass, and species richness of assemblages along with Bouché's ecological categories. We argue that these metrics are insufficient to effectively address earthworm conservation issues. We suggest four ecological characteristics which may be more informative for the development of conservation plans. Measurement of how much a species is (i) rare or common, (ii) native/nonnative, endemic and invasive, (iii) a specialist or generalist, and (iv) a winner or loser in the Anthropocene are all promising tools to support earthworm diversity conservation. These metrics could also be applied to functional traits, but better definition of these traits is fundamental. Finally, we emphasize the need to broaden spatial scales in earthworm studies by analyzing alpha, beta and gamma components of diversity, as local diversity alone can be misleading
Search for rare decays of the Z and Higgs bosons to a J/ or (2S) meson and a photon in proton-proton collisions at = 13 TeV
No full textInternational audienceA search is presented for rare decays of the Z and Higgs bosons to a photon and a J/ or a (2S) meson, with the charmonium state subsequentially decaying to a pair of muons. The data set corresponds to an integrated luminosity of 123 fb of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. No evidence for branching fractions of these rare decay channels larger than predicted in the standard model is observed. Upper limits at 95% confidence level are set: (H J/) 2.6 10, (H (2S)) 9.9 10, (Z J/) 0.6 10, and (Z(2S)) 1.3 10. The ratio of the Higgs boson coupling modifiers is constrained to be in the interval (157, 199) at 95% confidence level. Assuming , this interval becomes (166, 208)
Dream habits in a large cohort of preteens and their relation to sleep and nocturnal awakenings
No full textInternational audienceSummary The present study examined dream habits, and their relation to sleep patterns, in 1151 preteens (597 boys; 554 girls; 11.31 ± 0.62 years old). Dream questionnaires assessed the frequency of dream recall, nightmare, and lucid dream, as well as the intensity of emotions experienced in dreams. Sleep variables included sleep duration and efficiency, but also different measurements of nocturnal awakenings. Among the preteens, 49.21% of them reported that they recalled dreams several times a week or almost every morning over the past few months. In addition, 52.00% of the preteens reported that they experienced nightmares, and 45.48% lucid dreams, less than once a month or never over the past few months. No gender differences were observed in dream variables. Nocturnal awakenings were linked to all dream variables, while sleep duration and sleep efficiency were related to nightmare frequency and emotions in dreams. Importantly, sleep duration and sleep efficiency were not associated with dream recall nor lucid dream frequency, with Bayesian analyses supporting the null hypothesis. These findings offer a comprehensive understanding of preteens’ dreams and their connection to key sleep aspects
Association between feels-like temperatures and injury risk during international outdoor athletic championships: a prospective cohort study on 29 579 athlete starts during 10 championships
No full textInternational audienceObjective To analyse associations between feels-like temperatures measured with the universal thermal climate index (UTCI) and injury rates during international athletic championships. Methods During 10 international outdoor athletic championships from 2007 to 2022, in-competition injuries were collected by medical teams and local organising committees. UTCI was extracted hourly from a global reanalysis of observed atmospheric conditions during each championship. We performed Poisson regressions with incidence rates (number of injuries per 1000 athlete starts) as outcomes and UTCI as a predictive variable adjusted for sex, for all and time-loss injuries, for different injured tissue types (ie, muscle, tendon, ligament, articular, bone and skin) and specific discipline (ie, sprints, hurdles, jumps, throws, middle distance, long distance, marathon and race walking). Results A total of 1203 in-competition injuries were reported for 29 579 athlete starts. For all in-competition injuries (ie, all injured tissue types and all disciplines), higher UTCI was associated with lower incidence rates for time-loss injuries (IRR=0.98, 95% CI 0.97 to 0.98) but not for all injuries (IRR=1.00, 95% CI 1.00 to 1.01). Based on injured tissue type with all disciplines included, higher UTCI was associated with lower incidence rates for all (IRR=0.97, 95% CI 0.97 to 0.98) and time-loss (IRR=0.96, 95% CI 0.96 to 0.96) muscle injuries. Based on the specific discipline, higher UTCI was associated with lower incidence rates for all and time-loss muscle injuries for sprints (IRR=0.95, 95% CI 0.95 to 0.96, and IRR=0.94, 95% CI 0.93 to 0.94, respectively), hurdles (IRR=0.97, 95% CI 0.96 to 97, and IRR=0.95, 95% CI 0.94 to 0.96, respectively) and throws (IRR=0.97, 95% CI 0.97 to 0.98). Conclusions Higher feels-like temperatures were associated with a decreased risk of time-loss and muscle injuries, particularly in sprints, hurdles and throws. Although the precise mechanism for lower injury rates with higher feels-like temperatures requires further investigation, adapting preparations such as warm-up or clothing to forecasted weather conditions may be of benefit
Writing and drawing tilts after right hemisphere stroke are signs of a wrong verticality representation
No full textInternational audienceBACKGROUND :Many signs of spatial dysgraphia and drawing errors after right hemispheric stroke (RHS) have been attributed to spatial neglect or impaired sensory feedback. Counterclockwise (contralesional) tilts of graphomotor productions remained to be explained.OBJECTIVE :To test whether graphomotor tilts stem from a tilted representation of verticality transposed to the top/bottom axis of the sheet of paper, from data of the DOBRAS cohort.METHODS :Handwriting and drawing orientations were measured from the writing of three lines and the drawing of the Gainotti Figure (house roof lines). Verticality perception was measured with the visual (VV) and postural (PV) verticals. Severity of extra-body (EBN) and body (BN) neglect were each quantified with composite scores (battery of 8 tests).RESULTS :We analyzed data of 133 individuals: 64 healthy individuals (median age 63 years) and 69 with a subacute RHS (median age 68 years). With respect to normal cut-offs (writing -5.4°; drawing - 8.1°), 26/69 (38%) individuals with RHS showed at least one graphomotor tilt (median[IQR] of writing tilt: -6.8°[-9.7;-1.7]; drawing tilt: -10.9°[-17.6;-6.4]). Compared to individuals without graphomotor tilts, those having both writing and drawing tilts showed greater contralesional tilts in verticality perception (VV: -1.4°[-4;0.6] vs -7.9°[-11.5;-7.5]; PV: -1°[-2.4;0.2] vs -8°[-9;-5.4], Ps ≤.001) and more severe spatial neglect (EBN: 4.2[1.8;9.3] vs 16.6[10.2;20.4]; BN: 22.7[17;28.2] vs 37.8[35.9;39.7], Ps ≤.01). Composite graphomotor z-scores on writing and drawing correlated both with verticality estimates (VV+PV, rs=.46, p <10-4 23 ) and spatial neglect scores (EBN+BN, rs=-.36, p <.01).CONCLUSION :Contralesional tilts of writing and drawing after RHS are primary related to a tilted representation of verticality, and secondary related to spatial neglect. They are easy to detect and could be considered as a first step to perform early, before conventional tests of verticality perception
Enhanced strain-hardening in newly designed Co-free austenitic high entropy alloys with an optimised nitrogen solubility
No full textInternational audienceThe effect of nitrogen on the microstructure and mechanical behavior of several Co-free high entropy alloys (HEAs) from the CrFeMnNi family was studied. Alloy design approach, based on thermodynamic computations, was implemented to obtain alloys with a high chromium content, a high nitrogen solubility as well as good austenite stability. An optimisation was made to meet selected criteria which led to three compositions with different nickel contents (Cr20Fe40Mn15Ni25, Cr20Fe44Mn15Ni21, and Cr20Fe47Mn15Ni18) optimised for, respectively, 0.4, 0.5 and 0.6 wt% N. Such optimised alloys were elaborated and compared with another Co-free HEA (Cr14Fe46Mn17Ni23) doped with 0.11–0.29 wt% N. It was shown that up to 0.56 wt% N could be dissolved in the matrixes in agreement with their computed high nitrogen solubility. The differences in chemical composition between the four studied matrixes did not lead to any change in behavior in presence of nitrogen: the lattice parameter expansion and mechanical resistances (yield strength and tensile strength) evolve linearly with nitrogen addition, up to at least 0.56 wt%. Especially, a significant effect of nitrogen content on strain-hardening was observed and was attributed to the formation of nanotwins in nitrogen-rich alloys
The Fixed Landscape Inference MethOd (flimo): a versatile alternative to Approximate Bayesian Computation, faster by several orders of magnitude
No full textModelling in biology must adapt to increasingly complex and massive data. The efficiency of the inference algorithms used to estimate model parameters is therefore questioned. Many of these are based on stochastic optimization processes that require significant computing time. We introduce the Fixed Landscape Inference MethOd (flimo), a new likelihood-free inference method for continuous state-space stochastic models. It applies deterministic gradient-based optimization algorithms to obtain a point estimate of the parameters, minimizing the difference between the data and some simulations according to some prescribed summary statistics. In this sense, it is analogous to Approximate Bayesian Computation (ABC). Like ABC, it can also provide an approximation of the distribution of the parameters. Three applications are proposed: a usual theoretical example, namely the inference of the parameters of g-and-k distributions; a population genetics problem, not so simple as it seems, namely the inference of a selective value from time series in a Wright-Fisher model; and simulations from a Ricker model, representing chaotic population dynamics. In the two first applications, the results show a drastic reduction of the computational time needed for the inference phase compared to the other methods, despite an equivalent accuracy. Even when likelihood-based methods are applicable, the simplicity and efficiency of flimo make it a compelling alternative. Implementations in Julia and in R are available on https://metabarcoding.org/flimo. To run flimo, the user must simply be able to simulate data according to the chosen model
The squat jump and sprint force–velocity profiles of elite female football players are not influenced by the menstrual cycle phases and oral contraceptive use
No full textInternational audiencePurposeForce–velocity profiling is an excellent tool for training individualization, especially in sports with well-established physical preparation practices, such as football. However, it remains unclear whether menstrual cycle phases and oral contraceptive (OC) use influence the force–velocity profile. The aim of this study was to determine whether squat jump and sprint force–velocity profiles change throughout the menstrual cycle or during the use of OC in elite female football players.MethodsThe vertical and horizontal force–velocity profiles of 21 female football players (11 eumenorrheic women and 10 OC users; mean age 26.0 ± 3.7 and 24.1 ± 1.6 years, respectively) were analysed using photocells and a radar device during loaded squat jumps and 40-m sprints. The cycle phase at each testing session was confirmed by measuring serum oestradiol and progesterone concentrations.ResultsThe menstrual cycle and OC phases were not associated with changes in the force–velocity profile parameters (p > 0.05). Maximal vertical power and theoretical (ratio between the horizontal component of the ground reaction force and the corresponding resulting maximal force and theoretical maximal running velocity) and functional (time to complete a 40-m sprint) parameters of the horizontal force–velocity profile were higher in OC users than eumenorrheic women.ConclusionThe main finding of this study is that the force–velocity profile is not influenced by the menstrual cycle phases or OC use. The differences observed between eumenorrheic athletes and OC users require further investigation but are more likely attributed to individual variations rather than to a specific hormonal environment