Understanding the effect of cell disruption methods on the diffusion of Chlorella vulgaris proteins and pigments in the aqueous phase

Cell disruption of microalgae is usually evaluated by microscopic observations and quantification of the target molecules before and after cell disruption. The following study considers a new approach by analysing the diffusion behaviour of proteins and pigments of Chlorella vulgaris in an aqueous medium after applying different cell disruption methods. Results were revealed by microscopic observations, quantifying the concentration of the molecules of interest, and calculating their diffusion coefficient. Microscopic observations showed intact cells after applying chemical hydrolysis and ultrasonication. However, the majority of the cells lost their globular shape after bead milling and high-pressure homogenization. The protein concentration increased in the following order: ultrasonication bead milling > ultrasonication > high-pressure homogenization. Pigments were not detected in the aqueous phase of the chemical hydrolysis treatment, but their concentration and their diffusion were in the same order as proteins in the mechanical treatments. The study implied that diffusivity of the target molecules was not directly correlated to their increase concentration in the aqueous phase. Therefore, even if the cells were completely broken, diffusivity followed the hindered molecule diffusion phenomenon, which implies that somehow cells are not completely disrupted

Implantation of Mouse Embryonic Stem Cell-Derived Cardiac Progenitor Cells Preserves Function of Infarcted Murine Hearts

Stem cell transplantation holds great promise for the treatment of myocardial infarction injury. We recently described the embryonic stem cell-derived cardiac progenitor cells (CPCs) capable of differentiating into cardiomyocytes, vascular endothelium, and smooth muscle. In this study, we hypothesized that transplanted CPCs will preserve function of the infarcted heart by participating in both muscle replacement and neovascularization. Differentiated CPCs formed functional electromechanical junctions with cardiomyocytes in vitro and conducted action potentials over cm-scale distances. When transplanted into infarcted mouse hearts, CPCs engrafted long-term in the infarct zone and surrounding myocardium without causing teratomas or arrhythmias. The grafted cells differentiated into cross-striated cardiomyocytes forming gap junctions with the host cells, while also contributing to neovascularization. Serial echocardiography and pressure-volume catheterization demonstrated attenuated ventricular dilatation and preserved left ventricular fractional shortening, systolic and diastolic function. Our results demonstrate that CPCs can engraft, differentiate, and preserve the functional output of the infarcted heart

La place des jeunes agriculteurs dans le monde rural depuis 1960

DESS d'informatique documentaireAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 11560 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

N-Synchronous Kahn Networks

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Synchronization of periodic clocks

We propose a programming model dedicated to real-time videostreaming applications for embedded media devices, including highdefinition TVs. This model is built on the synchronous programming model extended with domain-specific knowledge — periodic evolution of streams — to allow correct-by-construction properties of the application to be proven by the compiler. These properties include buffer requirements and delays between input and output streams. Such properties are tedious to analyze by hand, due to the combinatorics of video filters, multiple data rates and formats. We show how to extend a core synchronous data-flow language with a notion of periodic clocks, and to design a relaxed clock calculus (a type system for clocks) to allow non strictly synchronous processes to be composed. This relaxation is associated with a subtyping rule in the clock calculus. Delay, buffer insertion and control code for these buffers are automatically inferred from the clock types through a systematic program transformation. Categories and Subject Descriptors C.3 [Special-purpose and application-based systems]: Real-time and embedded systems; D.3.2 [Language classifications]: Data-flow language

Synchronizing Periodic Clocks in Kahn Networks

We propose a programming model and language dedicated to high-performance streaming applications. In particular, we study real-time video-streaming for embedded media devices, including high-definition TVs. This language builds on the synchronous programming model and on domain-specific knowledge --- periodic evolution of streams --- to allow correct-by-construction properties of the application to be proven by the compiler. These properties include buffer requirements and delays between input and output streams. Correctness of the implementation is difficult to assess with traditional (asynchronous) approaches. Such properties are tedious to analyze by hand, due to the combinatorics of video filters, multiple data rates and formats. For example, the design of communicating buffers between filtering processes (image scaling, quality enhancement, etc.) whose clocks do not strictly match is tedious and error-prone. Two communicating periodic processes are defined as n-synchronous if they can be implemented in the ordinary (0-)synchronous model with a FIFO buffer of size n. We extend a core synchronous data-flow language with a notion of periodic clocks, and design a relaxed clock calculus (a type system for clocks) to allow non strictly synchronous processes to be composed. This relaxation is associated with a subtyping rule in the clock calculus. Delay, buffer insertion and control code for these buffers are automatically inferred from the clock types through a systematic program transformation

Spatio-temporal control of mutualism in legumes helps spread symbiotic nitrogen fixation

Mutualism is of fundamental importance in ecosystems. Which factors help to keep the relationship mutually beneficial and evolutionarily successful is a central question. We addressed this issue for one of the most significant mutualistic interactions on Earth, which associates plants of the leguminosae family and hundreds of nitrogen (N-2)-fixing bacterial species. Here we analyze the spatio-temporal dynamics of fixers and non-fixers along the symbiotic process in the Cupriavidus taiwanensis-Mimosa pudica system. N-2-fixing symbionts progressively outcompete isogenic non-fixers within root nodules, where N-2-fixation occurs, even when they share the same nodule. Numerical simulations, supported by experimental validation, predict that rare fixers will invade a population dominated by non-fixing bacteria during serial nodulation cycles with a probability that is function of initial inoculum, plant population size and nodulation cycle length. Our findings provide insights into the selective forces and ecological factors that may have driven the spread of the N-2-fixation mutualistic trait