Numerical analysis of timber fracture due to mechanical and thermal loads: an approach based on invariant integral

International audienc

Stochastic analysis of mixed mode fracture in timber material using polynomial chaos expansion

International audienc

Numerical fracture analysis coupling thermo-hygro mechanical and viscoelastic behaviour

International audienc

On the evolution of decoys in plant immune systems

The Guard-Guardee model for plant immunity describes how resistance proteins (guards) in host cells monitor host target proteins (guardees) that are manipulated by pathogen effector proteins. A recently suggested extension of this model includes decoys, which are duplicated copies of guardee proteins, and which have the sole function to attract the effector and, when modified by the effector, trigger the plant immune response. Here we present a proof-of-principle model for the functioning of decoys in plant immunity, quantitatively developing this experimentally-derived concept. Our model links the basic cellular chemistry to the outcomes of pathogen infection and resulting fitness costs for the host. In particular, the model allows identification of conditions under which it is optimal for decoys to act as triggers for the plant immune response, and of conditions under which it is optimal for decoys to act as sinks that bind the pathogen effectors but do not trigger an immune response.Comment: 15 pages, 6 figure

On analytical formulation integrating mixed mode fracture and climate change in wood material

International audienc

Fissuration des rondelles de Sapin blanc du Massif Central suite au séchage naturel

National audienc

ANR JCJC2013 Projet CLIMBOIS : Essais de fissuration du bois en fluage sous environnement variable

National audienc

Numerical study of crack path by MMCG specimen using M integral

The mixed mode loading configuration occurs in many civil engineering and mechanical applications. In wood material, the study of this problem is very important due to the orthotropic character and the heterogeneity of the material. In order to study the mixed mode loading in wood material, Moutou Pitti et al [1] have proposed a new specimen called Mixed Mode Crack Growth (MMCG). The main goal of this geometry is to propose a decrease of the energy release rate during the crack growth process. In this case, the fracture parameters can be decoupled into Mode I and Mode II in order to determine the impact of time during creep crack test. The present work proposes to study the crack path stability in MMCG specimen for different sizes and thicknesses. The M? integral, combining real and virtual mechanical displacement fields is used in order to separate numerically mode I and mode II in the mixed mode ratio. The stability is shown for the opening mode (Mode I), the shear mode (Mode II), and the mixed mode of 15°, 30°, 45°, 60°, 75° by computing the energy release rate versus the crack length. Finally, it is shown that the MMCG specimen can be reduced in various shape and used for example in small climate chamber in order to perform creep test at different temperature and moisture content levels

L\u2019economia dei due angoli. Agricoltura dinamica nel Nord-Ovest e nel Sud-Est della Sicilia

Due porzioni del territorio siciliano - i due angoli del Nord-Ovest e del Sud-Est - si caratterizzano per la presenza diffusa di attivit\ue0 economiche (le filiere del vitivinicolo e dell\u2019orticolo), che hanno avuto nel passato recente un certo successo di mercato. Questa ricerca ha cercato di comprendere le motivazioni di questo dinamismo, evidenziare similitudini e differenze, combinando dati statistici ed evidenze dirette. Si \ue8 cercato di interpretare e incarnare le statistiche alla luce delle testimonianze e del racconto diretto dei protagonisti, di indagare il peso della dotazione di vantaggi competitivi naturali e di lungo saper fare e quello dell\u2019innovazione intenzionale, di ricostruire le relazioni tra gli attori e la loro capacit\ue0 di interagire con il mercato di riferimento