In this paper, we propose a new stabilised finite element method for the Darcy-Forchheimer model based on the jump stabilisation technique. We prove the well-posedness of the discrete scheme and develop an a priori error analysis. We provide two academic examples that support the theory and study the effect of the Forchheimer number on convergence. Finally, we adapt the method to solve the coupling of the Darcy-Forchheimer model with a heat equation and provide several numerical experiments, including an application to the simulation of wood drying and a three-dimensional example.
This study presents an advanced methodology to monitor the reactivity of the individual components in a model blended cement, and to reveal the working mechanism of an accelerating admixture such as Na2S2O3. This is achieved by solid-state nuclear magnetic resonance (NMR) measurements in a model blend using selective isotope labelling of C3S or of an aluminosilicate-glass (taken as a model supplementary cementitious material). Results were complemented with TGA, XRD and thermodynamic modelling.NMR measurements with selective 29Si isotopic labelling captured the spatial and compositional heterogeneity of the C-A-S-H phase, with different Al/Si ratio and Ca/Si. This is a consequence of the different reactivity of the C3S and of the glass phases which induces local and temporal fluctuations in Ca and Al availability. The addition of Na2S2O3 enhanced the initial reactivity of both components of the blend, thus reducing the chemical heterogeneities of the C-A-S-H. In parallel, Na2S2O3 addition enhanced the precipitation of S(II)-AFm. This reduced the concentration of aluminates in solution, as manifested by a lowered average Al/Si ratio in C-A-S-H, which lowered the passivation of C3S and glass surfaces, directly benefiting their reactivity. Finally, the impact of Na2S2O3 on the reactivity was validated on blends of Portland cements with slag.
Fluids released in subduction zones play a key role in Earth dynamics, yet their compositions and migration scales remain poorly constrained. Here we present the first investigation of primary fluid inclusions across an entire exhumed subduction complex. These inclusions, trapped in high-pressure minerals, preserve small portions of subduction fluids likely unaffected by post-entrapment modifications. Distinct fluid compositions across lithologies point to a dominant closed-system behavior, with fluid transfer at a restricted scale. In blueschist-facies metasediments, a progressive salinity decrease from low to high grade is interpreted as reflecting a dilution of the rock chlorine content by local dehydration reactions. A suspected across-grade evolution of CO2CH4 ratios in metasediment gas mixtures indicates decreasing fO2 conditions relative to the fayalite-magnetite-quartz buffer, consistent with an internally graphite-carbonate buffered system. In contrast, metamafic rocks preserve high salinity fluids inherited from oceanic hydrothermal alteration, only slightly diluted by devolatilization reactions during burial. Major dehydration reactions occurring at the blueschist- to eclogite-facies transition in metamafic rocks release large volumes of saline fluids, and are likely responsible for the relatively high salinity values observed in the surrounding eclogitic metasediments. Locally, external fluid input is also detected in metasediments near evaporite-rich margin units. Overall, our data reveal restricted fluid circulation (up to the hm-scale) in the downgoing plate, except in zones that localized strain, where subsequent km-scale fluid channelization occurs.
We used the ultra-deep GLIMPSE JWST/NIRCam survey to constrain the faint end of the [O III]+H beta luminosity function (LF) down to 10(39)erg s(-1) at z similar to 7 - 9 behind the lensed Hubble Frontier Field galaxy cluster Abell S1063. We applied a spectral energy distribution fitting on a Lyman-break galaxy selected sample of 164 lensed galaxies and measured their combined H beta+[O III]lambda lambda 4960, 5008 flux to build the emission line LF. We found a [O III]+H beta LF with a faint-end slope (alpha = -1.78(-0.06)(+0.06) for z = 7 - 8 and alpha = -1.55(-0.11)(+0.11) for z = 8 - 9), which is flatter than the UV LF at similar redshifts (alpha <= -2) and suggests a lower number density of weak [O III]+H beta emitting galaxies at fixed M-UV. We analysed several possible explanations: (i) a decrease in the [O III]+H beta-to-UV ratio due to bursty star formation histories (SFHs), (ii) the effect of metallicity on the [O III]-to-H beta ratio, or (iii) signs of a faint-end turnover in the UV LF. Under the assumption of an evolving [O III]-to-H beta ratio, we separated the contribution of [O III]lambda 5008 and H beta and obtained a flatter [O III]lambda 5008 LF (alpha = -1.66(-0.05)(+0.05) for z = 7 - 8 and alpha = -1.45(-0.10)(+0.09) for z = 8 - 9) but steeper H beta LF (alpha=-1.95-0.08+0.08 for z = 7 - 8 and alpha = -1.68(-0.14)(+0.13) for z = 8 - 9). The combination of a decreasing metallicity and bursty SFH can reconcile the observed differences between the UV and [O III]+H beta LF. By converting this LF into the ionising photon-production rate N-ion, we show that galaxies with L-H alpha >= 10(39) erg s(-1), that is, with a star formation rate (SFR) (H alpha) >= 5 & times; 10(-3) M-circle dot yr(-1)) cause 31%-90% and 46%-156% of the ionising photon budget (at 7 < z < 8 and 8 < z < 9), when we assume a constant escape fraction of Lyman-continuum photon (f(esc) = 0.14). The shape of the LF further shows the negligible contribution of faint galaxies to the N-ion. Additionally, we derived the cosmic star formation rate density (SFRD), finding results consistent with previous estimates. However, the sensitivity of GLIMPSE to lower SFRs reinforces the conclusion that very faint galaxies contribute very little to N-ion and the SFRD. Our results suggests that GLIMPSE has detected the bulk of the total [O III]+H beta emission from star-forming galaxies, and that galaxies below our detection limits are likely minor contributors to cosmic re-ionisation.
Two marine sediment cores (MDBT 557 and MDBT 561) from the southern Brazilian shelf were analyzed to reconstruct Holocene variations in terrigenous organic matter (OM) input, vegetation dynamics, and the climatic-oceanographic processes influencing sediment deposition. Using sedimentological, molecular and isotopic proxies we identified site-specific differences in OM delivery but coherent long-term regional trends. During the early Holocene, both records indicate low terrigenous input, reflecting a weakened South American Monsoon System (SAMS) over the La Plata River (LPR) basin and reduced continental runoff, which, despite lower relative sea level (RSL), likely limited effective sediment export from the LPR and smaller coastal watersheds. Molecular proxies show that vegetation in southeastern South America was dominated by C4-rich grasslands, with minimal forest contribution, consistent with drier regional conditions. In the middle Holocene, weakened monsoon precipitation combined with a sustained RSL highstand restricted sediment dispersal across the shelf, maintaining low terrigenous OM input. Nonetheless, subtle lipid biomarker shifts suggest transitional vegetation states and gradual increases in humidity at the basin margins. A marked change occurs around 6,000 cal BP, when hydrodynamic reorganizations expanded the LPR plume over the shelf, altering the provenance of terrigenous OM. This shift marks the late-Holocene onset conditions, characterized by increased precipitation driven by strengthening summer insolation, intensification of the SAMS, and the establishment of a modern ENSO-like regime after similar to 4,000 cal BP. Consequently, terrigenous OM input and forest-derived signatures increased substantially, reflecting the expansion of Araucaria and Atlantic Forest taxa across southeastern South America.
