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Constraining primordial non-Gaussianity from DESI DR1 quasars and Planck PR4 CMB Lensing
No full textInternational audienceWe present the first measurement of local-type primordial non-Gaussianity from the cross-correlation between million spectroscopically confirmed quasars from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI) and the Planck PR4 CMB lensing reconstructions. The analysis is performed in three tomographic redshift bins covering , covering a sky fraction of . We adopt a catalog-based pseudo- estimator and apply linear imaging weights validated on noiseless mocks. Compared to previous analyses using photometric quasar samples, our results benefit from the high purity of the DESI spectroscopic sample, the reduced noise of PR4 lensing, and the absence of excess large-scale power in the spectroscopic quasar auto-correlation. Fitting simultaneously for the non-Gaussianity parameter and the linear bias amplitude in each redshift bin, we obtain for a response parameter , and for . These results improve the constraints on by compared to the previous analysis based on the Legacy Imaging Survey DR9. Our results demonstrate the statistical power of DESI quasars for probing inflationary physics, and highlight the promise of future DESI data releases
A year-long observational analysis of atmospheric trace gases and particulate matter in Kathmandu
No full textInternational audienceKathmandu Valley is one of the most densely populated cities in Nepal, facing significant air quality challenges. This study presents a comprehensive analysis based on twelve months of continuous air quality measurement data collected at the Khumaltar Air Quality Monitoring Station (ICIMOD AQMS), which is located in the southern part of the Kathmandu Valley. The study investigates particulate matter (PM10, PM2.5 , PMC (PM10-PM2.5)) alongside trace gases (O3, NOx, SO2, and CO), focuses on their seasonal, diurnal variations, interspecies correlations, potential sources, and the impact of regional atmospheric transport. The results reveal that the annual PM2.5 concentration (49 µg m-3) largely exceeds the WHO air quality guideline of 5 µg m -3 . Pollutant concentrations show clear seasonal variation, with peaks during the winter and pre-monsoon seasons, and a noticeable decline during the monsoon. A strong correlation (r = 0.82, p = 0.00) between PM2.5 and NOx indicates that fossil fuel combustion is a dominant source of fine particulate pollution. During the pre-monsoon season, O3 concentrations occasionally exceed 100 ppb (8-hr running average), with seasonal diurnal concentration observed close to 90 ppb in the afternoon. The study found that temperature and relative humidity significantly influence coarse PM levels, with a strong negative correlation (r = -0.89, p = 0.00) between coarse PM and the relative humidity, suggesting less resuspension under moist conditions. Furthermore, this study highlights the severe air pollution in the Kathmandu Valley throughout the year, driven primarily by local emissions, with regional atmospheric transport further contributing to poor air qualit
The lithosphere - asthenosphere system seen by surface waves: New insights from radial anisotropy
No full textInternational audienc
Insights into L4 ordinary chondrites from the Gueltat Zemmour fall, Morocco: Modal mineralogy, chondrule characteristics, and magnetic signatures
No full textInternational audienceThe Gueltat Zemmour meteorite, an L4 ordinary chondrite that fell in southern Morocco on 21 August 2018, was investigated through petrographic, mineralogical, geochemical, and magnetic analyses. X-ray diffraction indicates a modal composition dominated by forsteritic olivine (39.7(4) weight %), enstatite (32.4(3) %), plagioclase (7.3(1) %), troilite (3.7(1) %), and Fe–Ni metal phases (16.9 %, kamacite-dominated). Chondrules represent ∼82 % of the surface area, with porphyritic olivine–pyroxene and porphyritic olivine as the dominant types, and an average diameter of ∼500 μm. Gamma spectrometry confirmed the presence of short-lived cosmogenic radionuclides (e.g., 7Be, 22Na, 26Al, 48V), with a 22Na/26Al activity ratio consistent with a recent fall. Magnetic hysteresis properties and the preservation of tetrataenite in cloudy zone textures indicate slow cooling during parent-body metamorphism. The sulfide assemblage, dominated by troilite with rare pentlandite, combined with Fe/S (∼0.98) and Fe_ox/Si (∼0.36) ratios, reflects reducing redox conditions near the iron–wüstite buffer and minimal secondary alteration. These integrated results confirm the classification of Gueltat Zemmour as an equilibrated L4 chondrite and provide new insights into the thermal history and redox state of L-group parent bodies, contributing to a broader understanding of the early evolution of ordinary chondrites
Enhanced Methane Production in Anaerobic Membrane Bioreactors: The Role of In-Situ Electro-Stimulation
No full textInternational audienceThis study compared the 280-day performance of a granular anaerobic membrane bioreactor (GAnMBR) and its electro-assisted variant (eGAnMBR) treating domestic wastewater at ambient temperature across permeate fluxes of 1.7–5.9 L/m2/h. Both systems achieved >95 % chemical oxygen demand removal. At moderate flux, eGAnMBR improved methane recovery by around 15 % versus the control and produced biogas up to 94 % methane. Lower effluent methane saturation suggested reduced dissolved-methane losses and lower greenhouse-gas risk. Despite slightly higher resistance from near-electrode cake, >95 % of fouling remained reversible; targeted design and operational optimization to limit cake and enhance local shear should support scale-up. Both systems remained net-energy-positive, with energy recovery above 0.76 kWh/m3 at the highest loading and clearer eGAnMBR benefits at moderate loading and shorter hydraulic retention time. Overall, electro-stimulated GAnMBR improved methane valorization and process robustness while preserving a net-positive energy balance, indicating a practical path to scalable, low-carbon municipal treatment
Cetaceans exhibit region-specific habitat preferences across tropical waters
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Volcanoes: Composition of Emissions
No full textInternational audienceVolcanic emissions mainly consist of water vapor, carbon dioxide, and sulfur gases, with smaller amounts of halogens and other trace gases. Their composition varies depending on the magma’s source and its storage conditions in the crust. Large explosive eruptions can release gases directly into the stratosphere, affecting atmospheric composition, especially the ozone layer, and altering the global climate for years. In recent decades, most global volcanic impacts have been caused by stratospheric aerosols formed from sulfur gas oxidation, though water vapor and halogens may also contribute to atmospheric changes
Opinion note on nonlinearity in induced polarization
No full textInternational audienceThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for nonlinearities, if they exist, can further enhance the sophistication of our models. Nonlinearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the nonlinearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The nonlinearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the nonlinearities still present. We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence
Examining copper supply consistency in socioeconomic pathways: A mine-level dynamic approach
No full textInternational audiencePrimary copper production capacity is crucial given future demand and social, environmental, technical, economic, and political constraints, often overlooked in decarbonization pathway models. To address this, we propose a methodology to examine the consistency of the basic drivers of Shared Socioeconomic Pathways (SSPs) for primary copper requirements using the DyMEMDS stock-flow model. Our approach involves projecting primary copper production capacities to 2050 on a mine-by-mine basis, integrating mining industry dynamics based on commercial data. Results indicate significant concerns regarding the consistency of SSPs' basic drivers for copper requirements, revealing potential gaps exceeding 40 Mt in worst-case scenarios. Such discrepancies could impact technology deployments necessary for socioeconomic and decarbonisation assumptions. We recommend that the decarbonization modeling community align scenarios with mining industry constraints. Considering resource efficiency and circular economy strategies is essential for proposing more consistent scenarios to decision-makers, thereby mitigating risks of copper supply shortages hindering climate actio
The contributions of various calcifying plankton to the South Atlantic calcium carbonate stock
No full textInternational audiencePelagic calcifying plankton play an important role in the marine carbon cycle. However, field studies quantifying the contributions of multiple calcifying plankton groups to particulate inorganic carbon (PIC) stocks and export into the ocean interior are scarce. Most studies target one specific plankton group and adjust their sampling strategy accordingly, hampering comparisons. Furthermore, the literature is strongly biased towards foraminifera and coccolithophores, so aragonite contributions (e.g., gastropods) remain virtually unconstrained. A holistic view is required for future projections of marine carbon cycle changes. Here, we present the contributions of three main calcifying plankton groups – coccolithophores, foraminifera and planktonic gastropods (comprising heteropods and pteropods) – to PIC stocks and fluxes throughout the water column during a sampling campaign in the South Atlantic Ocean. Coccolithophore calcite dominated the depth-integrated PIC standing stock (∼ 80 %), followed by aragonite from planktonic gastropods (∼ 17 %) and calcite from foraminifera (∼ 3 %). The estimated production and export of the calcifying plankton largely depend on assumed turnover times and sinking speeds, which both have large uncertainties. Coccolithophores contributed 92 %–99 % of the produced PIC, depending on planktonic gastropod turnover time, and from 52 % to 99 % of the exported PIC, depending on their mode of sinking. Both the standing stock and export of planktonic gastropods was significantly larger than that of foraminifera. Similarity between our results and those from different ocean basins suggests that these patterns are global in nature, implying that not only coccolithophores but also gastropods may be a more important contributor to the oceans PIC inventory than foraminifera, challenging a longstanding paradigm