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A Drosophila Model for Clostridium difficile Toxin CDT Reveals Interactions with Multiple Effector Pathways.

Clostridium difficile infections (CDIs) cause severe and occasionally life-threatening diarrhea. Hyper-virulent strains produce CDT, a toxin that ADP-ribosylates actin monomers and inhibits actin polymerization. We created transgenic Drosophila lines expressing the catalytic subunit CDTa to investigate its interaction with host signaling pathways in vivo. When expressed in the midgut, CDTa reduces body weight and fecal output and compromises survival, suggesting severe impairment of digestive functions. At the cellular level, CDTa induces F-actin network collapse, elimination of the intestinal brush border, and disruption of intercellular junctions. We confirm toxin-dependent re-distribution of Rab11 to enterocytes' apical surface and observe suppression of CDTa phenotypes by a Dominant-Negative form of Rab11 or RNAi of the dedicated Rab11GEF Crag (DENND4). We also report that Calmodulin (Cam) is required to mediate CDTa activity. In parallel, chemical inhibition of the Cam/Calcineurin pathway by Cyclosporin A or FK506 also reduces CDTa phenotypes, potentially opening new avenues for treating CDIs

PERSYST, a model for ex ante assessment of cropping systems performances. Adaptation to organic farming in the Ile-de-France region

PERSYST is a web software for ex ante assessment of crop yield that takes explicitely into account the cropping system (i.e. crop rotation and crop management) perspective. Environmental and economic indicators are calculated at crop rotation scale to complete the previous yield assessment. In 2012, a research program enabled the model adaptation to organic systems, taking into account weed management and organic inputs supply. This program also allowed to parameterize the web software in the Ile-de-France region for 8 soil types and 18crops. Parameterization has been validated for the most common situations. Validation remains to be done for less common ones. When completed, validation will make it possible to test the software in promising situations of use, such as supporting organic farmers analyzing their current cropping systems, or supporting farmers thinking about converting their farms to organic farming

A V-shape superconducting artificial atom based on two inductively coupled transmons

Circuit quantum electrodynamics systems are typically built from resonators and two-level artificial atoms, but the use of multi-level artificial atoms instead can enable promising applications in quantum technology. Here we present an implementation of a Josephson junction circuit dedicated to operate as a V-shape artificial atom. Based on a concept of two internal degrees of freedom, the device consists of two transmon qubits coupled by an inductance. The Josephson nonlinearity introduces a strong diagonal coupling between the two degrees of freedom that finds applications in quantum non-demolition readout schemes, and in the realization of microwave cross-Kerr media based on superconducting circuits.Comment: 5 pages, 3 figure

Predictors of shared book reading at home with preschoolers: Are there differences between Roma and non-Roma low-income families?

Previous research highlights several benefits of shared book reading (SBR) for child development, but less studies exist about its predictors (Yarosz & Barnett, 2001). Literature on home SBR in Portugal is scarce (Araújo & Costa, 2015; Peixoto et al., 2008), and studies on its predictors in families at socioeconomic risk or Roma families in this context are, respectively, reduced (Gamelas et al., 2003) or inexistent. This study aimed to investigate the predictors of the frequency of SBR in two ethnically diverse groups of families. Specifically, we studied the associations between child and family (mother) characteristics, parental aspirations, and parental involvement in preschool events and frequency of home SBR. Two hundred and six caregivers of Portuguese Roma ( n = 101) and non-Roma ( n = 105) low-income preschoolers (109 boys; M age = 5, SD age = 0.94) living in the Metropolitan areas of Lisbon and Oporto, Portugal, completed a survey, in face-to-face meetings. A multiple regression model, using AMOS (v. 25), showed that mothers’ educational level, educational aspirations for their child, and involvement in informal (but not formal) events in preschool were positively associated with frequency of SBR. Ethnicity did not moderate these associations. The overall similar pattern results for Roma and non-Roma low income families is an important finding, suggesting that these families may experience similar challenges in engaging in SBR with their preschool children and, therefore, may benefit from interventions with similar features.info:eu-repo/semantics/acceptedVersio

Kerr non-linearity in a superconducting Josephson metamaterial

We present a detailed experimental and theoretical analysis of the dispersion and non-linear Kerr frequency shifts of plasma modes in a one-dimensional Josephson junction chain containing 500 SQUIDs in the regime of weak nonlinearity. The measured low-power dispersion curve agrees perfectly with the theoretical model if we take into account the Kerr renormalisation of the bare frequencies and the long-range nature of the island charge screening by a remote ground plane. We measured the self- and cross-Kerr shifts for the frequencies of the eight lowest modes in the chain. We compare the measured Kerr coefficients with theory and find good agreement

Optimal error estimates for non-conforming approximations of linear parabolic problems with minimal regularity

We consider a general linear parabolic problem with extended time boundary conditions (including initial value problems and periodic ones), and approximate it by the implicit Euler scheme in time and the Gradient Discretisation method in space; the latter is in fact a class of methods that includes conforming and nonconforming finite elements, discontinuous Galerkin methods and several others. The main result is an error estimate which holds without supplementary regularity hypothesis on the solution. This result states that the approximation error has the same order as the sum of the interpolation error and the conformity error. The proof of this result relies on an inf-sup inequality in Hilbert spaces which can be used both in the continuous and the discrete frameworks. The error estimate result is illustrated by numerical examples with low regularity of the solution