Spatio-temporal patterns in a mechanical model for mesenchymal morphogenesis

We present an in-depth study of spatio-temporal patterns in a simplified version of a mechanical model for pattern formation in mesenchymal morphogenesis. We briefly motivate the derivation of the model and show how to choose realistic boundary conditions to make the system well-posed. We firstly consider one-dimensional patterns and carry out a nonlinear perturbation analysis for the case where the uniform steady state is linearly unstable to a single mode. In two-dimensions, we show that if the displacement field in the model is represented as a sum of orthogonal parts, then the model can be decomposed into two sub-models, only one of which is capable of generating pattern. We thus focus on this particular sub-model. We present a nonlinear analysis of spatio-temporal patterns exhibited by the sub-model on a square domain and discuss mode interaction. Our analysis shows that when a two-dimensional mode number admits two or more degenerate mode pairs, the solution of the full nonlinear system of partial differential equations is a mixed mode solution in which all the degenerate mode pairs are represented in a frequency locked oscillation

System thermal-hydraulic modelling of the phénix dissymmetric test benchmark

Phénix is a French pool-type sodium-cooled prototype reactor; before the definitive shutdown, occurred in 2009, a final set of experimental tests are carried out in order to increase the knowledge on the operation and the safety aspect of the pool-type liquid metal-cooled reactors. One of the experiments was the Dissymmetric End-of-Life Test which was selected for the validation benchmark activity in the frame of SESAME project. The computer code validation plays a key role in the safety assessment of the innovative nuclear reactors and the Phénix dissymmetric test provides useful experimental data to verify the computer codes capability in the asymmetric thermal-hydraulic behaviour into a pool-type liquid metal-cooled reactor. This paper shows the comparison of the outcomes obtained with six different System Thermal-Hydraulic (STH) codes: RELAP5-3D©, SPECTRA, ATHLET, SAS4A/SASSYS-1, ASTEC-Na and CATHARE. The nodalization scheme of the reactor was individually achieved by the participants; during the development of the thermal-hydraulic model, the pool nodalization methodology had a special attention in order to investigate the capability of the STH codes to reproduce the dissymmetric effects which occur in each loop and into pools, caused by the azimuthal asymmetry of the boundary conditions. The modelling methodology of the participants is discussed and the main results are compared in this paper to obtain useful guide lines for the future modelling of innovative liquid metal pool-type reactors

Redox Properties of Self-Assembled Gold Nanoclusters

The redox properties of a monolayer of alkanethiolate-protected gold nanoclusters (MPCs) constructed on a gold slide electrode was studied in 1,2-dichloroethane (DCE) electrolyte solutions. The influence of the electrostatic interaction between attached MPCs and the substrate electrode on the absolute standard redox potential of MPCs was theoretically considered and studied experimentally

Quantitative trait variation in ASD probands and toddler sibling outcomes at 24 months

BACKGROUND: Younger siblings of children with autism spectrum disorder (ASD) are at increased likelihood of receiving an ASD diagnosis and exhibiting other developmental concerns. It is unknown how quantitative variation in ASD traits and broader developmental domains in older siblings with ASD (probands) may inform outcomes in their younger siblings. METHODS: Participants included 385 pairs of toddler siblings and probands from the Infant Brain Imaging Study. ASD probands (mean age 5.5 years, range 1.7 to 15.5 years) were phenotyped using the Autism Diagnostic Interview-Revised (ADI-R), the Social Communication Questionnaire (SCQ), and the Vineland Adaptive Behavior Scales, Second Edition (VABS-II). Siblings were assessed using the ADI-R, VABS-II, Mullen Scales of Early Learning (MSEL), and Autism Diagnostic Observation Schedule (ADOS) and received a clinical best estimate diagnosis at 24 months using DSM-IV-TR criteria (n = 89 concordant for ASD; n = 296 discordant). We addressed two aims: (1) to determine whether proband characteristics are predictive of recurrence in siblings and (2) to assess associations between proband traits and sibling dimensional outcomes at 24 months. RESULTS: Regarding recurrence risk, proband SCQ scores were found to significantly predict sibling 24-month diagnostic outcome (OR for a 1-point increase in SCQ = 1.06; 95% CI = 1.01, 1.12). Regarding quantitative trait associations, we found no significant correlations in ASD traits among proband-sibling pairs. However, quantitative variation in proband adaptive behavior, communication, and expressive and receptive language was significantly associated with sibling outcomes in the same domains; proband scores explained 9-18% of the variation in cognition and behavior in siblings with ASD. Receptive language was particularly strongly associated in concordant pairs (ICC = 0.50, p \u3c 0.001). CONCLUSIONS: Proband ASD symptomology, indexed by the SCQ, is a predictor of familial ASD recurrence risk. While quantitative variation in social communication and restricted and repetitive behavior were not associated among sibling pairs, standardized ratings of proband language and communication explained significant variation in the same domains in the sibling at 24 months, especially among toddlers with an ASD diagnosis. These data suggest that proband characteristics can alert clinicians to areas of developmental concern for young children with familial risk for ASD

Absolute Standard Redox Potential of Monolayer-Protected Gold Nanoclusters

The redox properties of monolayer-protected gold nanoclusters (MPCs) are considered from both the theoretical and experimental viewpoints. The “absolute standard redox potential” ([ ]abs) of MPCs is first derived from electrostatic considerations. A linear dependence of the absolute standard redox potential on the valence state of MPCs is theoretically predicted and verified experimentally. By employing ferricinium/ferrocene (Fc+/Fc) as a reference redox couple, the average valence state of MPCs at a given potential can be estimated

Attributing and Referencing (Research) Software: Best Practices and Outlook from Inria

Software is a fundamental pillar of modern scientiic research, not only in computer science, but actually across all elds and disciplines. However, there is a lack of adequate means to cite and reference software, for many reasons. An obvious rst reason is software authorship, which can range from a single developer to a whole team, and can even vary in time. The panorama is even more complex than that, because many roles can be involved in software development: software architect, coder, debugger, tester, team manager, and so on. Arguably, the researchers who have invented the key algorithms underlying the software can also claim a part of the authorship. And there are many other reasons that make this issue complex. We provide in this paper a contribution to the ongoing eeorts to develop proper guidelines and recommendations for software citation, building upon the internal experience of Inria, the French research institute for digital sciences. As a central contribution, we make three key recommendations. (1) We propose a richer taxonomy for software contributions with a qualitative scale. (2) We claim that it is essential to put the human at the heart of the evaluation. And (3) we propose to distinguish citation from reference

Simulations of the adsorption of ionic species at polarisable liquid liquid interfaces

The adsorption of ions at the interface between two immiscible electrolyte solutions (ITIES) is primarily controlled by the potential distribution across the interface, which in turn is influenced by the adsorption process. In the present paper, we simulate the effect of the adsorption of charged species on the charge distribution at the ITIES based on the classical description of the interface employing the Gouy–Chapman model. The inner layer is considered as a charged plane, where the ionic adsorption takes place. The potential at this plane is determined by the electro-neutrality condition. Various adsorption isotherms are considered, including potential dependent isotherms based on the Langmuir and Frumkin adsorption models. The potential distribution and the charge density profile are derived by solving the Poisson–Boltzman equation numerically. We show that the charge distribution in the interfacial region is significantly affected by the adsorption of ionic species. Under certain conditions, the adsorption results in a non-monotonic potential distribution with a potential trap at the interface

Reactivity of Monolayer-Protected Gold Nanoclusters at Dye-Sensitized Liquid/Liquid Interfaces

Hexanethiolate monolayer-protected gold nanoclusters (MPCs) were used as redox quenchers at the polarizable water/1,2-dichloroethane (DCE) interface. Photocurrent responses originating from the heterogeneous quenching of photoexcited water soluble porphyrin complexes by MPCs dissolved in the DCE phase were observed. As MPCs can function as both electron acceptors and donors, the photocurrent results from the superposition of two simultaneous processes, which correspond to the oxidation and reduction of MPCs. The magnitude of the net photocurrent is essentially determined by the balance of the kinetics of these two processes, which can be controlled by tuning the Galvani potential difference between the two phases. We show that, within the available potential window, the apparent electron-transfer rate constants follow classical Butler−Volmer dependence on the applied potential difference

Voltammetry for surface-active ions at polarisable liquid|liquid interfaces

Adsorption of charged species at the interface between two immiscible electrolyte solutions (ITIES) is simulated taking into account both the mutual influence between the potential dependent surface excess charge and the potential distribution between the two phases and the partition equilibrium of the surface- active molecules. The electrical potential profiles are calculated assuming a single adsorption plane separating two electrical diffuse layers following the modified Verwey–Niessen model (MVN). The interfacial boundary potential is obtained from the electroneutrality condition. The interplay between adsorption and partition under steady-state conditions is addressed yielding voltammetric responses for the adsorption–desorption processes along with the faradaic response

CdSe Sensitized Thin Aqueous Films: Probing the Potential Distribution Inside Multilayer Assemblies

Ultrathin polypeptide multilayer films are assembled by the sequential electrostatic adsorption of monolayers of poly-L-lysine and poly-L-glutamic acid onto carboxylic acid terminated alkanethiol-modified gold surfaces. The polypeptide multilayer films are hydrophilic, can incorporate electroactive species such as ferri/ferrocyanide, and are stable when immersed in organic solvents such as 1,2-dichloroethane. Cadmium selenide quantum dots stabilized by negatively charged citrate groups are electrostatically attached to the multilayer film assembly in order to act as photoactive species. Photocurrent responses originating from the CdSe sensitized ultrathin multilayer film are investigated as functions of the applied potential, the thickness of the film and the presence of quenchers in the organic phase. A theoretical model is proposed in order to analyze the kinetics of the photoinduced electron-transfer reactions and to probe the potential distribution within the film