Large Motion Assessment in Soils Under Dynamic Loading

This paper presents the mathematical formulation of the nonlinear multiphase dynamic model meant for porous media, obtained by applying the finite transformation assumption. This assumption is appropriate when large motions take place either during mass wasting processes, such as large slumps and earthflows, or during earthquake events when site liquefaction occurs and results for instance in large irrecoverable settlements or lateral spreads. The weak formulation and numerical implementation of the dynamic model uses the mesh-free h-p clouds method, which is based on the more general Partition of Unity Method. The mesh-free numerical methods seem indeed to be more appropriate for large transformation problems, where geometry may change in an important manner during simulation, as usual mesh constraints no longer exist. The numerical simulations of observed liquefaction-induced lateral spreads, performed with the proposed model are not presented in this paper

Numerical Modelling Approaches for the Analysis of Earthquake Triggered Landslides

Different numerical approaches for the analysis of earthquake triggered landslides are studied. Improved simplified models are developed and their performance for evaluating the response of natural slopes subjected to earthquakes is studied. Using more sophisticated numerical techniques the influence of several factors such as the hydro mechanical behavior assumptions, 1D vs. 2D geometry, and the input motion are assessed. 2D computations have shown that the kinematics of the slope motion is largely affected by the geometry of the slope. As far as the soil behavior is concerned, the results indicate that introduction of progressive yielding in the soil model provides larger displacement, progressive pore-pressure generation and more diffuse deformation. For the input motion, the number of peaks and their amplitudes have been identified as being the mains factors for irreversible displacements

Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) and serine biosynthetic pathway genes are co-ordinately increased during anabolic agent-induced skeletal muscle growth

We aimed to identify novel molecular mechanisms for muscle growth during administration of anabolic agents. Growing pigs (Duroc/(Landrace/Large-White)) were administered Ractopamine (a beta-adrenergic agonist; BA; 20ppm in feed) or Reporcin (recombinant growth hormone; GH; 10mg/48hours injected) and compared to a control cohort (feed only; no injections) over a 27-day time course (1, 3, 7, 13 or 27-days). Longissimus Dorsi muscle gene expression was analyzed using Agilent porcine transcriptome microarrays and clusters of genes displaying similar expression profiles were identified using a modified maSigPro clustering algorithm. Anabolic agents increased carcass (p=0.002) and muscle weights (Vastus Lateralis: p<0.001; Semitendinosus: p=0.075). Skeletal muscle mRNA expression of serine/one-carbon/glycine biosynthesis pathway genes (Phgdh, Psat1 and Psph) and the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase-M (Pck2/PEPCK-M), increased during treatment with BA, and to a lesser extent GH (p<0.001, treatment x time interaction). Treatment with BA, but not GH, caused a 2-fold increase in phosphoglycerate dehydrogenase (PHGDH) protein expression at days 3 (p<0.05) and 7 (p<0.01), and a 2-fold increase in PEPCK-M protein expression at day 7 (p<0.01). BA treated pigs exhibit a profound increase in expression of PHGDH and PEPCK-M in skeletal muscle, implicating a role for biosynthetic metabolic pathways in muscle growth

Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) 3-rays. A significant correlation (&gt;3σ) between X-rays and VHE 3-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy 3-rays and radio, with the radio lagging by more than 100 days, placing the 3-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE 3-rays from mid-2017 to mid-2019 with a stable VHE flux (&gt;0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock. © 2023. The Author(s). Published by the American Astronomical Society

Multi-messenger characterization of Mrk 501 during historically low X-ray and γ\gamma-ray activity

We study the broadband emission of Mrk 501 using multi-wavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wavebands, with the highest occurring at X-rays and very-high-energy (VHE) $\gamma$-rays. A significant correlation ($>$3$\sigma$) between X-rays and VHE $\gamma$-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between Swift-XRT and Fermi-LAT. We additionally find correlations between high-energy $\gamma$-rays and radio, with the radio lagging by more than 100 days, placing the $\gamma$-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE $\gamma$-rays from mid-2017 to mid-2019 with a stable VHE flux ($>$0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2-year-long low-state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED towards the low-state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock.Comment: 56 pages, 30 figures, 14 tables, submitted. Corresponding authors are L. Heckmann, D. Paneque, S. Gasparyan, M. Cerruti, and N. Sahakya

Effets de la thermo-plasticité des argiles sur le comportement des puits de stockage.

L'analyse du comportement des puits de stockage des déchets radioactifs dans des formations argileuses présente un grand intérêt pour les concepteurs dans l'évaluation de la sûreté de ces ouvrages. Le comportement d'un sol adjacent à un puits, contenant des déchets radioactifs de hautes activités, en conditions non-homogènes et quasi-statiques, est étudié à travers des simulations numériques. Différentes configurations et conditions de drainage sont considérées pour ce puits soumis à des sollicitations thermiques engendrées par ces déchets. L'influence de la variation de la température sur le gradient hydraulique et l'écoulement transitoire de l'eau interstitielle est prise en compte dans ces analyses. Le comportement thermo-mécanique du milieu argileux se caractérise par de fortes non-linéarités. Il est modélisé avec une loi de comportement multimécanisme thermo-plastique développée par les auteurs. Cette loi de comportement tient compte de l'écrouissage thermique et de l'évolution de la surface de charge avec la température. Dans certaines conditions de chargements thermiques, nous pouvons observer une diminution du volume de sol avec l'augmentation de la température. En outre, le modèle prend en compte la variation des modules élastiques sous l'effet thermique, phénomène important dans les conditions presque non drainées (sollicitations rapides, matériaux à faible perméabilité, etc…). Parmi les principaux résultats de ces simulations, l'apport de l'utilisation de cette loi de comportement thermo-plastique par rapport aux approches plus classiques est étudié. En particulier, nos résultats montrent que, dans certains cas, une approche thermo-plastique pour les matériaux argileux prédit une réponse très différente de celle issue des méthodes plus couramment employées

Un modèle de sols saturés en dynamique non linéaire

Un modèle pour étudier l'influence des facteurs géologiques sur les réponses sismiques des sites constitués des sols déformables est présenté.La première partie est consacrée à la formulation physique des milieux biphasiques saturés et à la modélisation du comportement élastoplastique des sols. Le comportement biphasique des sols est modélisé par une théorie de Biot affinée à l'aide des méthodes d'homogénéisation. Une formulation simplifiée permettant une analyse moins coûteuse et valable pour les phénomènes à basse fréquence est mise en œuvre. Le comportement élastoplastique des sols est décrit par une loi élastoplastique multimécanisme cyclique.Dans la modélisation en éléments finis des problèmes de propagation des ondes, une attention particulière est portée sur les limites du maillage. Le développement d'éléments paraxiaux permet de construire de telles frontières absorbantes. Ils constituent également un moyen intéressant pour introduire le champ incident sismique généralisé.La présentation est achevée par quelques exemples mono et bidimensionnels pour montrer l'intérêt de cette approche pour l'évaluation directe de la réponse sismique des sites