Computing the drainage discharge and assessing the impacts of tunnels drilled in Hard Rocks

International audienceMost Hard Rocks (HR) are or were exposed to deep weathering processes. It turns out that the hydraulic conductivity of HR is mostly inherited from these weathering processes (Lachassagne et al., 2011): (i) within their permeable Stratiform Fissured Layer (SFL) located below the low hydraulic conductivity unconsolidated weathered layer (saprolite). The thickness of both layers often reaches more than 100 m (Dewandel et al., 2006), (ii) and within the permeable vertical fissured layer developed at the periphery of or within preexisting geological discontinuities (joints, dykes, veins, lithological discontinuities, etc.) (Dewandel et al., 2011, Roques et al., 2012). From this conceptual model, the drainage discharge and the surface hydrogeological (piezometry in wells) and hydrological (discharge of streams) impacts of shallow highway tunnels drilled in a metamorphic series (metasedimentary and metavolcanic rocks) intruded by granitic bodies have been forecasted. These tunnels belong to the A89 highway recently opened (2012) in France between Balbigny and La Tour de Salvagny (Monts du Lyonnais, 50 km West of Lyon city). They are up to 4 km long, and their depth below ground level ranges between 0 and 300 m. The method is based on

Systemic and central nervous system neuroinflammatory signatures of neuropsychiatric symptoms and related cognitive decline in older people.

Neuroinflammation may contribute to psychiatric symptoms in older people, in particular in the context of Alzheimer's disease (AD). We sought to identify systemic and central nervous system (CNS) inflammatory alterations associated with neuropsychiatric symptoms (NPS); and to investigate their relationships with AD pathology and clinical disease progression. We quantified a panel of 38 neuroinflammation and vascular injury markers in paired serum and cerebrospinal fluid (CSF) samples in a cohort of cognitively normal and impaired older subjects. We performed neuropsychiatric and cognitive evaluations and measured CSF biomarkers of AD pathology. Multivariate analysis determined serum and CSF neuroinflammatory alterations associated with NPS, considering cognitive status, AD pathology, and cognitive decline at follow-up visits. NPS were associated with distinct inflammatory profiles in serum, involving eotaxin-3, interleukin (IL)-6 and C-reactive protein (CRP); and in CSF, including soluble intracellular cell adhesion molecule-1 (sICAM-1), IL-8, 10-kDa interferon-γ-induced protein, and CRP. AD pathology interacted with CSF sICAM-1 in association with NPS. Presenting NPS was associated with subsequent cognitive decline which was mediated by CSF sICAM-1. Distinct systemic and CNS inflammatory processes are involved in the pathophysiology of NPS in older people. Neuroinflammation may explain the link between NPS and more rapid clinical disease progression

Cerebrospinal Fluid Cortisol and Dehydroepiandrosterone Sulfate, Alzheimer's Disease Pathology, and Cognitive Decline.

Elevated cortisol levels have been reported in Alzheimer's disease (AD) and may accelerate the development of brain pathology and cognitive decline. Dehydroepiandrosterone sulfate (DHEAS) has anti-glucocorticoid effects and it may be involved in the AD pathophysiology. To investigate associations of cerebrospinal fluid (CSF) cortisol and DHEAS levels with (1) cognitive performance at baseline; (2) CSF biomarkers of amyloid pathology (as assessed by CSF Aβ levels), neuronal injury (as assessed by CSF tau), and tau hyperphosphorylation (as assessed by CSF p-tau); (3) regional brain volumes; and (4) clinical disease progression. Individuals between 49 and 88 years (n = 145) with mild cognitive impairment or dementia or with normal cognition were included. Clinical scores, AD biomarkers, brain MRI volumetry along with CSF cortisol and DHEAS were obtained at baseline. Cognitive and functional performance was re-assessed at 18 and 36 months from baseline. We also assessed the following covariates: apolipoprotein E (APOE) genotype, BMI, and education. We used linear regression and mixed models to address associations of interest. Higher CSF cortisol was associated with poorer global cognitive performance and higher disease severity at baseline. Cortisol and cortisol/DHEAS ratio were positively associated with tau and p-tau CSF levels, and negatively associated with the amygdala and insula volumes at baseline. Higher CSF cortisol predicted more pronounced cognitive decline and clinical disease progression over 36 months. Higher CSF DHEAS predicted more pronounced disease progression over 36 months. Increased cortisol in the CNS is associated with tau pathology and neurodegeneration, and with decreased insula and amygdala volume. Both CSF cortisol and DHEAS levels predict faster clinical disease progression. These results have implications for the identification of patients at risk of rapid decline as well as for the development of interventions targeting both neurodegeneration and clinical manifestations of AD

New analytical solution for the study of hydraulic interaction between Alpine tunnels and groundwater

La solution analytique dite du « puits artésien » développée par Jacob et Lohman [1952] est appliquée au contexte des tunnels profonds en haute montagne pour modéliser la décroissance en fonction du temps du débit des venues d’eau. La comparaison de la solution avec un modèle numérique démontre sa validité durant les premiers instants après le percement du tunnel. Ensuite, les conditions aux limites supposées dans la résolution du cas analytique – milieu infini – ne sont plus conformes à la réalité. Les simulations numériques effectuées montrent que la durée de validité de la solution de Jacob et Lohman est notamment inversement proportionnelle à la diffusivité hydraulique du massif. Les résultats de ces simulations permettent de scinder la décroissance du débit des venues d’eau en deux phases distinctes : la première phase correspond à la période de validité de la formule de Jacob et Lohman. Elle est caractérisée par l’extension d’un cône de rabattement autour de l’ouvrage après percement. Durant la seconde phase, le cône de rabattement atteint les limites physiques de l’aquifère (latérales et supérieure) et les débits décroissent plus rapidement suite à la décroissance des potentiels hydrauliques aux limites. Sous réserve du peu de données disponibles, ce type de comportement a été mis en évidence dans les Alpes aux tunnels du Simplon et du Mont-Blanc. Dans la seconde partie de l’article, un abaque paramétrique est présenté, permettant d’évaluer, après le percement d’un tunnel, le temps nécessaire pour qu’un rabattement donné soit atteint en un point défini du massif. Bien que négligeant les effets de limites mis en évidence dans la première partie de l’article, cet abaque permet néanmoins de mettre en évidence la grande inertie, à cette échelle d’observation, des aquifères en massifs montagneux. Il peut être appliqué à la détermination du temps nécessaire pour que l’effet hydraulique du tunnel soit mesurable en surface et dès lors étendu au dimensionnement des campagnes de surveillance des sources lors du percement d’un ouvrage souterrain. Cet abaque démontre l’influence de la géométrie du tunnel (rayon, profondeur) et des caractéristiques hydrauliques de l’aquifère (diffusivité, hauteur de la nappe) sur la durée nécessaire des campagnes de surveillance. Celles-ci devraient être ajustées au cas par cas en fonction du contexte de l’ouvrage souterrain

Vaccine nationalism counterintuitively erodes public trust in leaders

Global access to resources like vaccines is key for containing the spread of infectious diseases. However, wealthy countries often pursue nationalistic policies, stockpiling doses rather than redistributing them globally. One possible motivation behind vaccine nationalism is a belief among policymakers that citizens will mistrust leaders who prioritize global needs over domestic protection. In seven experiments (total N = 4,215 adults), we demonstrate that such concerns are misplaced: Nationally representative samples across multiple countries with large vaccine surpluses (Australia, Canada, United Kingdom, and United States) trusted redistributive leaders more than nationalistic leaders—even the more nationalistic participants. This preference generalized across different diseases and manifested in both self-reported and behavioral measures of trust. Professional civil servants, however, had the opposite intuition and predicted higher trust in nationalistic leaders, and a nonexpert sample also failed to predict higher trust in redistributive leaders. We discuss how policymakers’ inaccurate intuitions might originate from overestimating others’ self-interest

Averaging out magnetic forces with fast rf-sweeps in an optical trap for metastable chromium atoms

We introduce a novel type of time-averaged trap, in which the internal state of the atoms is rapidly modulated to modify magnetic trapping potentials. In our experiment, fast radiofrequency (rf) linear sweeps flip the spin of atoms at a fast rate, which averages out magnetic forces. We use this procedure to optimize the accumulation of metastable chomium atoms into an optical dipole trap from a magneto-optical trap. The potential experienced by the metastable atoms is identical to the bare optical dipole potential, so that this procedure allows for trapping all magnetic sublevels, hence increasing by up to 80 percent the final number of accumulated atoms.Comment: 4 pages, 4 figure

Plasma neurofilament light and phosphorylated tau 181 as biomarkers of Alzheimer's disease pathology and clinical disease progression.

BACKGROUND: To assess the performance of plasma neurofilament light (NfL) and phosphorylated tau 181 (p-tau181) to inform about cerebral Alzheimer's disease (AD) pathology and predict clinical progression in a memory clinic setting. METHODS: Plasma NfL and p-tau181, along with established cerebrospinal fluid (CSF) biomarkers of AD pathology, were measured in participants with normal cognition (CN) and memory clinic patients with cognitive impairment (mild cognitive impairment and dementia, CI). Clinical and neuropsychological assessments were performed at inclusion and follow-up visits at 18 and 36 months. Multivariate analysis assessed associations of plasma NfL and p-tau181 levels with AD, single CSF biomarkers, hippocampal volume, and clinical measures of disease progression. RESULTS: Plasma NfL levels were higher in CN participants with an AD CSF profile (defined by a CSF p-tau181/Aβ1-42 > 0.0779) as compared with CN non-AD, while p-tau181 plasma levels were higher in CI patients with AD. Plasma NfL levels correlated with CSF tau and p-tau181 in CN, and with CSF tau in CI patients. Plasma p-tau181 correlated with CSF p-tau181 in CN and with CSF tau, p-tau181, Aβ1-42, and Aβ1-42/Aβ1-40 in CI participants. Compared with a reference model, adding plasma p-tau181 improved the prediction of AD in CI patients while adding NfL did not. Adding p-tau181, but not NfL levels, to a reference model improved prediction of cognitive decline in CI participants. CONCLUSION: Plasma NfL indicates neurodegeneration while plasma p-tau181 levels can serve as a biomarker of cerebral AD pathology and cognitive decline. Their predictive performance depends on the presence of cognitive impairment

Plasma neurofilament light and phosphorylated tau 181 as biomarkers of Alzheimer's disease pathology and clinical disease progression.

To assess the performance of plasma neurofilament light (NfL) and phosphorylated tau 181 (p-tau181) to inform about cerebral Alzheimer's disease (AD) pathology and predict clinical progression in a memory clinic setting. Plasma NfL and p-tau181, along with established cerebrospinal fluid (CSF) biomarkers of AD pathology, were measured in participants with normal cognition (CN) and memory clinic patients with cognitive impairment (mild cognitive impairment and dementia, CI). Clinical and neuropsychological assessments were performed at inclusion and follow-up visits at 18 and 36 months. Multivariate analysis assessed associations of plasma NfL and p-tau181 levels with AD, single CSF biomarkers, hippocampal volume, and clinical measures of disease progression. Plasma NfL levels were higher in CN participants with an AD CSF profile (defined by a CSF p-tau181/Aβ <sub>1-42</sub> > 0.0779) as compared with CN non-AD, while p-tau181 plasma levels were higher in CI patients with AD. Plasma NfL levels correlated with CSF tau and p-tau181 in CN, and with CSF tau in CI patients. Plasma p-tau181 correlated with CSF p-tau181 in CN and with CSF tau, p-tau181, Aβ <sub>1-42</sub> , and Aβ <sub>1-42</sub> /Aβ <sub>1-40</sub> in CI participants. Compared with a reference model, adding plasma p-tau181 improved the prediction of AD in CI patients while adding NfL did not. Adding p-tau181, but not NfL levels, to a reference model improved prediction of cognitive decline in CI participants. Plasma NfL indicates neurodegeneration while plasma p-tau181 levels can serve as a biomarker of cerebral AD pathology and cognitive decline. Their predictive performance depends on the presence of cognitive impairment

Accumulation of chromium metastable atoms into an Optical Trap

We report the fast accumulation of a large number of metastable 52Cr atoms in a mixed trap, formed by the superposition of a strongly confining optical trap and a quadrupolar magnetic trap. The steady state is reached after about 400 ms, providing a cloud of more than one million metastable atoms at a temperature of about 100 microK, with a peak density of 10^{18} atoms.m^{-3}. We have optimized the loading procedure, and measured the light shift of the 5D4 state by analyzing how the trapped atoms respond to a parametric excitation. We compare this result to a theoretical evaluation based on the available spectroscopic data for chromium atoms.Comment: 7 pages, 5 Figure

Potential barrier heights at metal on oxygen-terminated diamond interfaces

International audienceElectrical properties of metal-semiconductor (M/SC) and metal/oxide/SC structures built with Zr or ZrO_2 deposited on oxygen-terminated surfaces of (001)-oriented diamond films, comprising a stack of lightly p-doped diamond on a heavily doped layer itself homoepitaxially grown on a Ib substrate, are investigated experimentally and compared to different models. In Schottky barrier diodes, the interfacial oxide layer evidenced by high resolution transmission electron microscopy and electron energy losses spectroscopy before and after annealing, and barrier height inhomogeneities accounts for the measured electrical characteristics until flat bands are reached, in accordance with a model which generalizes that of R.T. Tung [Phys. Rev. B 45, 13509 (1992)] and permits to extract physically meaningful parameters of the three kinds of interface: (a) unannealed ones; (b) annealed at 350°C; (c) annealed at 450°C, with characteristic barrier heights of 2.2-2.5 V in case (a) while as low as 0.96 V in case (c). Possible models of potential barriers for several metals deposited on well defined oxygen-terminated diamond surfaces are discussed and compared to experimental data. It is concluded that interface dipoles of several kinds present at these compound interfaces and their chemical evolution due to annealing are the suitable ingredients able to account for the Mott-Schottky behavior when the effect of the metal work function is ignored, and to justify the reverted slope observed regarding metal work function, in contrast to the trend always reported for all other metal-semiconductor interfaces.Les propriétés électriques et structurales d'interfaces métal/diamant et métal/oxyde/diamant où le métal est le Zirconium et le semi-conducteur comporte un empilement de couches faiblement et fortement dopées au bore sur substrat Ib, sont étudiées expérimentalement et comparées à différents modèles. Dans le barrière de Schottky, une inter-couche d'oxyde d'environ 2 couches atomiques, mise en évidence par diverses techniques de microscopie électronique à transmission, est présente et ajoutée à la présence d'inhomogénéités de barrière de potentiel, est corrélée aux propriétés électriques simulées par un modèle qui généralise celui de R. T. Tung [Phys. Rev. B 45, 13509 (1992)] . Les paramètres physiquement caractéristiques des interfaces (a) non recuites, (b) recuite à 350°C et (c) recuite à 450°C peuvent ainsi être extraits, en particulier des hauteurs de barrière de 2.2-2.5 V dans le cas (a) et aussi basses que 0.96 V dans le cas (c). Les modèles possibles de fixation du niveau de Fermi aux interfaces métal/diamant sont examinés et confrontés aux données récemment publiées pour différents métaux sur la surface oxygénée du diamant. On conclue que les quantités physiques judicieuses sont l'affinité électronique du diamant, fonction de son état de surface, pour justifier l'allure générale conforme au modèle de Mott-Schottky et la force du dipole d'interface, dépendante des liaisons chimiques à l'interface, pour expliquer la pente de la variation de la barrière en fonction du travail de sortie du métal, qui est inversée par rapport à tous les autres semi-conducteurs