Spatial and temporal patterns of organophosphate Esters flame retardants and plasticizers in airborne particles over the Mediterranean sea

International audienceWe studied the co-occurrence of OPEs and other constituents in atmospheric particles at the two edges of the Mediterranean Sea, under the influence of the transport of polluted air from Europe and dust from the Sahara. The highest OPE concentrations were observed during the summer period in the East Mediterranean and in spring for the NW Mediterranean. The total average atmospheric concentration of Σ6OPEs in the NW Mediterranean was 2103 ± 2020 pg m−3 (n = 23) with EHDPP and TCPP to be the predominant OPEs, accounting on average for 46% and 37% of the total Ʃ6OPEs concentrations, respectively. The average concentration of Σ6OPEs in East Mediterranean was 156.4 ± 170.3 pg m−3 (n = 67) with TCPP showing the highest concentration (116.1 ± 92.8 pg m−3), followed by TCEP (67.5 ± 55.8 pg m−3). In both areas, OPEs were mostly associated with fossil fuel combustion and road traffic, while the air masses from Saharan desert influenced the concentration of EHDPP, TCEP in NW Mediterranean and the TCEP concentration levels in the East Mediterranean. The total annual deposition of reported OPEs to the Mediterranean basin was estimated to be 584 tonnes, accounting for about 8.5% of the total deposited anthropogenic phosphorus

Galaxy Clusters Discovered via the Thermal Sunyaev-Zel'dovich Effect in the 500-square-degree SPTpol Survey

International audienceWe present a catalog of 689 galaxy cluster candidates detected at significance $\xi>4$ via their thermal Sunyaev-Zel'dovich (SZ) effect signature in 95 and 150 GHz data from the 500-square-degree SPTpol survey. We use optical and infrared data from the Dark Energy Camera and the Wide-field Infrared Survey Explorer (WISE) and \spitzer satellites, to confirm 544 of these candidates as clusters with $\sim94\%$ purity. The sample has an approximately redshift-independent mass threshold at redshift $z>0.25$ and spans $1.5 \times 10^{14} 1$. We use external radio data from the Sydney University Molonglo Sky Survey (SUMSS) to estimate contamination to the SZ signal from synchrotron sources. The contamination reduces the recovered $\xi$ by a median value of 0.032, or $\sim0.8\%$ of the $\xi=4$ threshold value, and $\sim7\%$ of candidates have a predicted contamination greater than $\Delta \xi = 1$. With the exception of a small number of systems $(<1\%)$, an analysis of clusters detected in single-frequency 95 and 150 GHz data shows no significant contamination of the SZ signal by emission from dusty or synchrotron sources. This cluster sample will be a key component in upcoming astrophysical and cosmological analyses of clusters. The SPTpol millimeter-wave maps and associated data products used to produce this sample are available at https://pole.uchicago.edu/public/Data/Releases.html, and the NASA LAMBDA website. An interactive sky server with the SPTpol maps and Dark Energy Survey data release 2 images is also available at NCSA https://skyviewer.ncsa.illinois.edu

An updated mass-radius analysis of the 2017-2018 NICER data set of PSR J0030+0451

International audienceIn 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterising dense matter. Two independent analyses found a mass of $\sim 1.3-1.4\,\mathrm{M_\odot}$ and a radius of $\sim 13\,$km. They also both found that the hot spots were all located on the same hemisphere, opposite to the observer, and that at least one of them had a significantly elongated shape. Here we reanalyse, in greater detail, the same NICER data set, incorporating the effects of an updated NICER response matrix and using an upgraded analysis framework. We expand the adopted models and jointly analyse also XMM-Newton data, which enables us to better constrain the fraction of observed counts coming from PSR J0030+0451. Adopting the same models used in previous publications, we find consistent results, although with more stringent inference requirements. We also find a multi-modal structure in the posterior surface. This becomes crucial when XMM-Newton data is accounted for. Including the corresponding constraints disfavors the main solutions found previously, in favor of the new and more complex models. These have inferred masses and radii of $\sim [1.4 \mathrm{M_\odot}, 11.5$ km] and $\sim [1.7 \mathrm{M_\odot}, 14.5$ km], depending on the assumed model. They display configurations that do not require the two hot spots generating the observed X-rays to be on the same hemisphere, nor to show very elongated features, and point instead to the presence of temperature gradients and the need to account for them

Late Triassic initial closure of the Mongol-Okhotsk Ocean in the western segment: constraints from sedimentological, detrital zircon ages and paleomagnetic evidence

International audienceThe Mesozoic evolution of the Mongol-Okhotsk Ocean (MOO) has significantly affected the configuration of the modern Asian continent. Although a scissor-like closure of the MOO has long been proposed, when and how the MOO closed are still hotly debated, especially the timing of initial closure of the MOO in its western segment, hindering our understanding of both the evolution of the MOO and tectonics of the northern Asian continent. In order to uncover the timing of initial closure of the MOO, we performed a multidisciplinary study in sedimentology, detrital zircon U-Pb dating and paleomagnetic on the Late Triassic clastic strata from the Tarvagatay Block and the Amuria Block (AMB) on the both sides of the Mongol-Okhotsk Suture. The upper Triassic strata on both sides of the suture were dominated by plant fossil-bearing alluvial-fluvial facies sediments, which unconformably overlain pre-Triassic geological units, indicating a terrestrial setting after the closure of the MOO. Detrital zircon U-Pb dating results revealed consistent age distribution patterns for samples from both sides of the suture with a predominant peak at ∼253-251 Ma and a secondary peak at ∼359-357 Ma, representing two main arc magmatic events during the bidirectional subduction of the MOO in the Late Devonian-Early Carboniferous and Late Permian-Early Triassic. Coeval Late Triassic paleomagnetic poles were obtained from the northern AMB and Tarvagatay Block, revealing a comparable paleolatitude of the AMB (∼31-33°) and Tarvagatay Block (∼32-34°) in the Late Triassic, arguing for that the western segment of the MOO should have closed at the Late Triassic. The compilation of sedimentology, detrital zircon U-Pb dating, magmatic and paleomagnetic evidence provides integrated constraints on the Late Triassic initial closure of the MOO in its western segment

Régimes dynamiques dans les noyaux planétaires : diagrammes τ-ℓ

International audiencePlanetary cores are the seat of rich and complex fluid dynamics, in which the effects of rotation and magnetic field combine. The equilibria governing the strength of the magnetic field produced by the dynamo effect, the organisation and amplitude of the flow, and those of the density field, remain debated despite remarkable progress made in their numerical simulation. This paper proposes a new approach based on the explicit consideration of the variation of time scales τ with spatial scales ℓ for the different physical phenomena involved. The τ-ℓ diagrams thus constructed constitute a very complete graphic summary of the dynamics of the object under study. We highlight the role of the available convective power in controlling this dynamics, together with the relevant force balance, for which we derive a very telling τ–ℓ translation. Several scenarios are constructed and discussed for the Earth’s core, shedding new light on the width of convective columns, and on the force equilibria to be considered. A QG-MAC scenario adapted from Aubert [2019] gives a good account of the observations. A diversion to Venus reveals the subtlety and relativity of the notion of “fast rotator”. We discuss scaling laws and their validity domain, and illustrate “path strategies”. A complete toolbox is provided, allowing everyone to construct a τ–ℓ diagram of a numerical simulation, a laboratory experiment, a theory, or a natural object.Les noyaux planétaires sont le siège d’une dynamique des fluides riche et complexe où se combinent les effets de la rotation et du champ magnétique. Les équilibres gouvernant l’intensité du champ magnétique produit par effet dynamo, l’organisation et l’amplitude de l’écoulement, et celles du champ de densité, demeurent débattus, malgré les progrès remarquables de leur simulation numérique. Cet article détaille une approche qui repose sur la prise en compte explicite de la variation des échelles de temps avec les échelles spatiales pour les différents phénomènes physiques impliqués. Les diagrammes – ainsi construits constituent un résumé graphique très complet de la dynamique de l’objet étudié. Nous soulignons le rôle que joue la puissance convective disponible dans l’établissement de cette dynamique, ainsi que l’équilibre des forces pour lequel nous dérivons une traduction – qui se révèle très parlante. Plusieurs scenarios sont ainsi construits et discutés pour le noyau terrestre, apportant un nouvel éclairage sur la largeur des colonnes convectives, et sur les équilibres de force à considérer. Un scenario QG-MAC adapté de [Aubert, 2019] rend bien compte des observations. Un détour par Vénus révèle la subtilité et la relativité de la notion de “rotateur rapide”. Nous discutons les lois d’échelle et leur domaine de validité, et illustrons le concept de “path strategy”. Une boîte à outils complète est fournie, permettant à chacun de construire le diagramme – d’une simulation numérique, d’une expérience de laboratoire, d’une théorie, ou d’un objet naturel

Using fibre-optic sensing for non-invasive, continuous dendrometry of mature tree trunks

Dendrometry is the main non-invasive macroscopic technique commonly used in plant physiology andecophysysiology studies. Over the years several types of dendrometric techniques have been developed,each with their respective strengths and drawbacks. Automatic and continuous monitoring solutionsare being developed, but are still limited, particularly for non-invasive monitoring of large-diametertrunks. In this study, we propose a new type of automated dendrometer based on distributedfibre-optic sensing that continuously measures the change in stem circumference, is non-invasive, andhas no upper limit on the trunk diameter on which it can be installed. We perform a three-monthvalidation experiment during which we deploy a fibre-optic cable at three localities around thetrunks of two specimens of Brachychiton. We verify the accuracy of this new method throughcomparison against a conventional point-dendrometer, and we observe a consistent time lag betweenthe various measurement locations that varies with the meteorological conditions. Finally, we discussthe feasibility of the fibre-based dendrometer in the context of existing dendrometric techniques andpractical experimental considerations

Toxic responses of metabolites produced by Ostreopsis cf. ovata on a panel of cell types

International audienceBlooms of the dinoflagellate Ostreopsis cf. ovata are regularly associated with human intoxications that are attributed to ovatoxins (OVTXs), the main toxic compounds produced this organism and close analogs to palytoxin (PlTX). Unlike for PlTX, information on OVTXs'toxicity are scarce due to the absence of commercial standards. Extracts from two cultures of Mediterranean strains of O. cf. ovata (MCCV54 and MCCV55), two fractions containing or not OVTXs (prepared from the MCCV54 extract) and OVTX-a and -d (isolated from the MCCV55 extract) were generated. These chemical samples and PlTX were tested on a panel of cell types from several organs and tissues (skin, intestine, lung, liver and nervous system). The MCCV55 extract, containing a 2-fold higher amount of OVTXs than MCCV54 extract, was shown to be more cytotoxic on all the cell lines and more prone to increase interleukin-8 (IL-8) release in keratinocytes. The fraction containing OVTXs was also cytotoxic on the cell lines tested but induced IL-8 release only in liver cells. Unexpectedly, the cell lines tested showed the same sensitivity to the fraction that does not contain OVTXs. With this fraction, a pro-inflammatory effect was shown both in lung and liver cells. The level of cytotoxicity was similar for OVTX-a and –d, except on intestinal and skin cells where a weak difference of toxicity was observed. Among the 3 toxins, only PlTX induced a pro-inflammatory effect mostly on keratinocytes. These results suggest that the ubiquitous Na+/K+ ATPase target of PlTX is likely shared with OVTX-a and -d, although the differences in pro-inflammatory effect must be explained by other mechanisms

Les JO 2024 permettront-ils de mieux comprendre les dangers de la température humide ?

International audienceLa cérémonie d’ouverture aura-t-elle lieu comme prévu ? Combien de touristes viendront in fine dans la capitale ? Est-ce qu’il y aura une canicule ?Alors que la France entière se pose de multiples questions sur les prochains Jeux olympiques (JO) de Paris, en tant que physiciennes de l’atmosphère, ces JO seront pour nous l’occasion de scruter un indicateur de plus en plus utilisé pour mesurer les effets de la chaleur sur le corps humain, notamment lors d’un effort : celui de la température humide.Cet indice thermique permet d’évaluer un ressenti qui vous est sans doute familier : lors des pics de chaleur, quand la température dépasse 35 °C, nous avons tous fait l’expérience d’un ressenti très différent selon le taux d’humidité : à température égale, une chaleur sèche restant bien plus supportable qu’une chaleur humide. La chaleur et l’humidité peuvent même se révéler une combinaison mortelle, rendant la vie à l’extérieur particulièrement insupportable.S’il existe de nombreuses façons de mesurer le confort thermique, notamment pendant les vagues de chaleur, le terme de température ou chaleur humide, en anglais, wet bulb temperature (WBT), est de plus en plus utilisé par les scientifiques et les médias, pour une raison simple : plus celle-ci s’approche de la température du corps humain, plus elle devient dangereuse

Quantifying Anthropogenic Influences on Global Wave Height Trend During 1961–2020 With Focus on Polar Ocean

International audienceThis study investigates the contribution of external forcings on global and regional ocean wave height change during 1961–2020. Historical significant wave height (Hs) produced for different CMIP6 external forcings and preindustrial control conditions following the Detection and Attribution Model Intercomparison Project (DAMIP) are employed. The internal variability ranges are compared with different external forcing scenario. Statistically significant linear trends in Hs computed over regional ocean basins are found to be mostly associated with anthropogenic forcings: greenhouse gas‐only (GHG) and aerosol‐only (AER) forcing. For Hs, GHG signals are robustly detected and dominant for most of the global ocean, except over North pacific and South Atlantic, where AER signals are dominant. These results are supported by multi‐model analysis for wind speed. The remarkable increase in Hs over the Arctic (22.3%) and Southern (8.2%) Ocean can be attributed to GHG induced sea‐ice depletion and larger effective fetch along with wind speed increase