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

Elément de planchers composites bois-béton léger

Les éléments composites de planchers bois-béton léger connaissent de plus en plus de popularité dans la réhabilitation et dans les constructions neuves des structures de génie civil. En partenariat avec des industriels, nous avons mis au point un procédé de construction de planchers mixtes, composés d'éléments porteurs en bois et d'une chape de béton confectionnée à partir de fibres de bois. Une étude expérimentale conduite sur les matériaux constituant cette mixité et leurs liaisons ainsi que les approches réglementaires nécessaires à leur dimensionnement sont présentées

Investigation of a Staphylococcus aureus sequence type 72 food poisoning outbreak associated with food-handler contamination in Italy

On August 2019 a staphylococcal food poisoning outbreak occurred in an elderly home in Piedmont, Italy. The epidemiological investigation performed among the per- sons that consumed the meal identified chicken salad as the most likely source of the outbreak. Staphylococcus aureus was isolated from a total of seven samples, namely one vomit sample from a guest of the nursing home, two food samples (chicken salad with and without mayonnaise) and nasal swabs collected from a total of four persons working in the kitchen of the nursing home. The maximum likelihood tree obtained using single nucleotide polymorphisms analysis revealed that the isolates from the aforementioned samples clustered together. Multilocus sequence typing revealed that they belonged to Sequence Type 72. Fourier transform infrared spectroscopy (FTIR) was used in parallel to single nucleotide polymorphisms and whole genome sequencing for the determination of the degree of relatedness of the isolates. The results of the FTIR showed the same clustering obtained with single nucleotide poly- morphisms and whole genome sequencing and revealed the source of infection. This study underlines the importance of both laboratory evidence and epidemiological data for outbreak investigation and further confirms that FTIR is a suitable support for the short-term epidemiological investigation on source attribution in case of a S. aureus infection

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

On Numerical Evaluation of Mixed Mode Crack Propagation Coupling Mechanical and Thermal Loads in Wood Material

The mixed-mode crack growth coupling mechanical and thermal loads in wood material is investigated in this numerical work. The analytical formulation the crack driving force, namely the energy release rate, is introduced by T-integral that takes into account mixed mode fracture, thermal process in orthotropic material and pressure applied on the crack lips. This new formulation is based on Nother’s theorem and the definition of the strain energy density according to Lagrangian’s and Eulerian’s configurations. Moreover, this analytical formulation is implemented in finite element software Cast3m. First of all, several numerical examples, dealing with isotropic material, are provided to illustrate the accuracy of the FEM model. Then, the crack resistance of a timber CTS (Compact Tension Specimen) is investigated to show the efficiency of the proposed approach in the case of orthotropic material

A protocol for Italian validation of DEMQoL-Proxy Scale: assessing the Quality of Life of people with moderate or mild dementia

In this paper, we propose an adaptation of a protocol for a tool's validation. We have utilized this phases-theory to validate in Italian language an instrument to assess Quality of Life for people with moderate or mild dementia. We will explain the example of our Italian validation of DEMQoL-Proxy considering each De Vellis's phase. We will explain our application of De Vellis's model to Italian example described. For the first three phases, we reproduced the original validating study in which authors (Smith et al., 2005) defined what to measure, how generate a set of items and the structure of the scale. Indeed, for the last five phases we explained the adaptation of De Vellis's model to Italian validation. We hope that this model could be effective to validating goals, for researchers and in particular for all professionals who deal with caregivers and patients with moderate and mild dementia. Furthermore, the measurement of the Quality of Life makes the scale widely useful within the various professional specialties and setting. Finally, thanks to the methodological assumptions adopted following the De Vellis's eight-phase model, we can affirm that this first Italian pre-validation of the DEMQoL-Proxy seems to be an excellent forerunner for its effective validation in the Italian context

Generalization of Integral Parameters to Fatigue Loading in Room Temperature

In this paper a numerical approach coupling independent path integrals, such as M-integral, to compute the crack driving forces namely the stress intensity factors, and empirical models, for instance Paris-Erdogan’s law, to assess the cumulative fatigue damage (i.e. crack size) during the crack growth process, is proposed. The M-integral derived from Nother’s theorem combines the real and virtual mechanical deformation and stress fields. A finite element routine is developed in order to compute the energy release rate according to the stress intensity factors. Results are given for a simple standard Al7075-T6 tensile test specimen. Finally, numerical estimates are compared to experimental data for various crack length in order to prove the efficiency and the accuracy of the proposed model

Generalization of Integral Parameters to Fatigue Loading in Room Temperature

In this paper a numerical approach coupling independent path integrals, such as M-integral, to compute the crack driving forces namely the stress intensity factors, and empirical models, for instance Paris-Erdogan’s law, to assess the cumulative fatigue damage (i.e. crack size) during the crack growth process, is proposed. The M-integral derived from Nother’s theorem combines the real and virtual mechanical deformation and stress fields. A finite element routine is developed in order to compute the energy release rate according to the stress intensity factors. Results are given for a simple standard Al7075-T6 tensile test specimen. Finally, numerical estimates are compared to experimental data for various crack length in order to prove the efficiency and the accuracy of the proposed model

Numerical Fracture Analysis Under Temperature Variation by Energetic Method

It is known that temperature change can induce sudden crack propagation especially when the material is composed of fibers. In this fact, the crack growth process under mixed-mode coupling mechanical and thermal loads in orthotropic materials like wood is investigated in this work. The analytical formulation of A integral’s combines the real and virtual mechanical and thermal stress/strain fields under transient diet in 2D. The Mixed Mode Crack Growth specimen providing the decrease of energy release rate during crack propagation is considered in order to compute the various mixed mode ratios. By using three specific routines, the analytical formulation is implemented in finite element software Cast3m. The efficiency of the proposed model is justified by showing the evolution of energy release rate and the stress intensity factors versus crack length and versus temperature variation in time dependent materia

Biological Stoichiometry in Human Cancer

A growing tumor in the body can be considered a complex ecological and evolutionary system. A new eco-evolutionary hypothesis (the "Growth Rate Hypothesis", GRH) proposes that tumors have elevated phosphorus (P) demands due to increased allocation to P-rich nucleic acids, especially ribosomal RNA, to meet the protein synthesis demands of accelerated proliferation.We determined the elemental (C, N, P) and nucleic acid contents of paired malignant and normal tissues from colon, lung, liver, or kidney for 121 patients. Consistent with the GRH, lung and colon tumors were significantly higher (by approximately two-fold) in P content (fraction of dry weight) and RNA content and lower in nitrogen (N):P ratio than paired normal tissue, and P in RNA contributed a significantly larger fraction of total biomass P in malignant relative to normal tissues. Furthermore, patient-specific differences for %P between malignant and normal tissues were positively correlated with such differences for %RNA, both for the overall data and within three of the four organ sites. However, significant differences in %P and %RNA between malignant and normal tissues were not seen in liver and kidney and, overall, RNA contributed only approximately 11% of total tissue P content.Data for lung and colon tumors provide support for the GRH in human cancer. The two-fold amplification of P content in colon and lung tumors may set the stage for potential P-limitation of their proliferation, as such differences often do for rapidly growing biota in ecosystems. However, data for kidney and liver do not support the GRH. To account for these conflicting observations, we suggest that local environments in some organs select for neoplastic cells bearing mutations increasing cell division rate ("r-selected," as in colon and lung) while conditions elsewhere may select for reduced mortality rate ("K-selected," as in liver and kidney)