<Emphasis Type="Italic">Sphagnum</Emphasis> Species Modulate their Phenolic Profiles and Mycorrhizal Colonization of Surrounding <Emphasis Type="Italic">Andromeda polifolia</Emphasis> along Peatland Microhabitats

Sphagnum mosses mediate long-term carbon accumulation in peatlands. Given their functional role as keystone species, it is important to consider their responses to ecological gradients and environmental changes through the production of phenolics. We compared the extent to which Sphagnum phenolic production was dependent on species, microhabitats and season, and how surrounding dwarf shrubs responded to Sphagnum phenolics. We evaluated the phenolic profiles of aqueous extracts of Sphagnum fallax and Sphagnum magellanicum over a 6-month period in two microhabitats (wet lawns versus dry hummocks) in a French peatland. Phenolic profiles of water-soluble extracts were measured by UHPLC-QTOF-MS. Andromeda polifolia mycorrhizal colonization was quantified by assessing the intensity of global root cortex colonization. Phenolic profiles of both Sphagnum mosses were species-, season- and microhabitat- dependant. Sphagnum-derived acids were the phenolics mostly recovered; relative quantities were 2.5-fold higher in S. fallax than in S. magellanicum. Microtopography and vascular plant cover strongly influenced phenolic profiles, especially for minor metabolites present in low abundance. Higher mycorrhizal colonization of A. polifolia was found in lawns as compared to hummocks. Mycorrhizal abundance, in contrast to environmental parameters, was correlated with production of minor phenolics in S. fallax. Our results highlight the close interaction between mycorrhizae such as those colonizing A. polifolia and the release of Sphagnum phenolic metabolites and suggest that Sphagnum-derived acids and minor phenolics play different roles in this interaction. This work provides new insight into the ecological role of Sphagnum phenolics by proposing a strong association with mycorrhizal colonization of shrubs.     

Ultrasound spatiotemporal despeckling via Kronecker wavelet-Fisz thresholding

We propose a novel framework for despeckling ultrasound image sequences while respecting the structural details. More precisely, we use thresholding in an adapted wavelet domain that jointly takes into account for the non-Gaussian statistics of the noise and the differences in spatial and temporal regularities. The spatiotemporal wavelet is obtained via the Kronecker product of two sparsifying wavelet bases acting, respectively, on the spatial and temporal domains. Besides enabling a structured sparse representation of the time–space plan, it also makes it possible to perform a variance stabilization routine on the spatial domain through a Fisz transformation. The proposed method enjoys adaptability, easy tuning and theoretical guaranties. We propose the corresponding algorithm together with results that demonstrate the benefits of the proposed spatiotemporal approach over the successive spatial treatment. Finally, we describe a data-driven extension of the proposed method that is based on temporal pre-filtering.     

A New PSO-based Algorithm for Two-Dimensional Non-Guillotine Non-Oriented Cutting Stock Problem

In this paper, a new algorithm is proposed for the two-dimensional non-guillotine non-oriented cutting stock problem. The considered problem consists of cutting small rectangular pieces of predetermined sizes from large but finite rectangular plates. The objective is to generate cutting patterns that minimize the unused area and fulfill customer orders. The proposed algorithm is a combination of a new particle swarm optimization approach with a heuristic criterion inspired from the literature. The algorithm is tested on twenty-two instances divided into two sets. Corresponding results show the algorithm efficiency in optimizing the trim loss that is comprised between 2.6% and 7.8% for all considered instances.     

Efficient hyper‐reduced‐order model (HROM) for thermal analysis in the moving frame

The hyper‐reduced‐order model (HROM) is proposed for the thermal calculation with a constant moving thermal load. Firstly, the constant velocity transient process is simplified to a steady‐state process in the moving frame. Secondly, the control volume is determined by the temperature rate, and the thermal equilibrium equation in the moving frame is derived by introducing an advective term containing the loading velocity. Thirdly, the HROM is performed on the control volume with a moving frame formulation. This HROM has been applied to the thermal loading on brick and ring disk specimens with a CPU gain of the order of 7 (10⁷). In addition, two strategies are proposed for the HROM to improve its precision. Moreover, the high efficiency and high accuracy are kept for the parametric studies on thermal conductivity and amplitude of heat flux based on the developed HROM. Copyright © 2016 John Wiley & Sons, Ltd.     

Efficient parallel edge-centric approach for relaxed graph pattern matching

Prior algorithms on graph simulation for distributed graphs are not scalable enough as they exhibit heavy message passing. Moreover, they are dependent on the graph partitioning quality that can be a bottleneck due to the natural skew present in real-world data. As a result, their degree of parallelism becomes limited. In this paper, we propose an efficient parallel edge-centric approach for distributed graph pattern matching. We design a novel distributed data structure called ST that allows a fine-grain parallelism, and hence guarantees linear scalability. Based on ST, we develop a parallel graph simulation algorithm called PGSim. Furthermore, we propose PDSim, an edge-centric algorithm that efficiently evaluates dual simulation in parallel. PDSim combines ST and PGSim in a Split-and-Combine approach to accelerate the computation stages. We prove the effectiveness and efficiency of these propositions through theoretical guarantees and extensive experiments on massive graphs. The achieved results confirm that our approach outperforms existing algorithms by more than an order of magnitude.

     

Smart places: Multi-agent based smart mobile virtual community management system

Now-a-days advances in mobile device technology aim to build complex computational systems providing a maximum level of flexibility, decentralization, simplest form of interactivity, and ease of use. Recently, the launch of the agent-oriented platform JaCaMo and its Android client based platform JaCa-Android have provided an appropriate level of abstraction to build smart mobile client server systems providing these attributes. By using these platforms, we have developed a multi-agent based Smart Mobile Virtual Community Management System (SMVCMS) that makes it possible to provide a decentralized and open management of virtual communities. This paper addresses the design and architecture of our multi-agent server and client application. It elaborates different features of our system; such as how a participant in virtual communities is supported by a Jason agent that encapsulates the logic and the control of the participation in a virtual community (such as publishing posts, notifying members, making recommendations for the user, etc.). It also discusses how the set of CArtAgOartifacts provides the basic functionalities and operations giving access to the functionalities for knowledge exchange in virtual communities, and personal agents onAndroid exploit these artifacts to execute their tasks while achieving their individual and collective goals. We have employed SMVCMS in the context of Smart Cities and found that the system fulfills the desired goals, such as decentralization of community management, personalized automatic management and discovery of communities, autonomy of agents and flexibility so that any agent can create its own community with the maximum level of ease.     

Cocontinuous morphology in vinylidene fluoride based polymers/poly(ethylene oxide) blends

In this work, blends of three different vinylidene fluoride (VdF) based homopolymers and copolymers with poly(ethylene oxide) were investigated. We focused on the continuity domain and, more particularly, on the cocontinuous morphology of these systems. The melt‐mixed blends were characterized by different techniques. The morphology was identified through a selective extraction technique and was confirmed by scanning electron microscopy. Dynamic oscillatory shear measurements were performed with a constant stress rheometer in the linear viscoelastic domain in the whole composition range. Because of the high viscosities and long relaxation times of the VdF‐based polymers, the interfacial effects were hidden by the intrinsic behavior of the neat components. Nevertheless, the combination of the different techniques highlighted the similarity of the systems toward morphological development, whatever the VdF monomers. The experiments and theoretical analysis indicated that the rheological behavior dominated the interfacial effects in such systems with a large viscosity ratio and that it also dictated the boundaries of the continuity domain. The originality of this study came from the use of three different VdF‐based polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Ionic nanocomposite networks in poly(styrene‐co‐methacrylic acid) copolymers with calcium carbonate

To create reversible supramolecular ionic networks, ionic cross‐links were formed from acid pendant functions in poly(styrene‐co‐methacrylic acid) copolymers by the addition of calcium carbonate. The random dispersion of acid functions in the polystyrene chain is ensured by NMR analysis. The partial reaction of the calcium carbonate with the carboxylic acids is highlighted by a limewater test. The influence of methacrylic acid and calcium‐carbonate contents on the formation of an ionic network has been studied through solubility tests. Two main effects were obtained: the exfoliation of the unreacted calcium carbonate characterized by TEM is due to ionic interactions at the surface of nanometric particles that form the first level of organization of the calcium carbonate. Another part of the calcium carbonate reacts with carboxylic acid and is detached from particles to form clusters as shown by x‐ray analysis. Finally, by analyzing the dynamic rheological spectrum, the conclusion that the strength of the ionic bonds arises with the calcium content is made. The interest of such an approach with a wide range of observed phenomena in the material is a one‐batch process to make thermoreversible nanocomposite networks. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013