Interlayer strain effects on the structural behavior of BiFeO3/LaFeO3 superlattices

Artificial (BiFeO3)0.5Λ/(LaFeO3)0.5Λ superlattices have been grown by pulsed laser deposition. The periodicity Λ was varied from 150 Å to 25 Å and the relative ratio between BiFeO3 (BFO) and LaFeO3 (LFO) is kept constant in each period. X-ray diffraction, transmission electron microscopy, and Raman spectroscopy investigations indicate antiferroelectric-like structures for large periodicity (Λ ≥ 76 Å), while Pnma LaFeO3-like structures are observed for small periodicity Λ ≤ 50 Å. Room temperature magnetic measurements were obtained by vibrating sample magnetometry and suggest antiferromagnetic ordering with weak ferromagnetism. Temperature dependent x-ray diffraction studies show an important shift of paraelectric-antiferroelectric phase transition scaling with BFO thickness. Strain and size effects explain this behavior and discussion is also made on the possible role of the oxygen octahedral rotation/tilt degree of freedom

Mechanisms for a nutrient-conserving carbon pump in a seasonally stratified, temperate continental shelf sea

Continental shelf seas may have a significant role in oceanic uptake and storage of carbon dioxide (CO2) from the atmosphere, through a ‘continental shelf pump’ mechanism. The northwest European continental shelf, in particular the Celtic Sea (50°N 8°W), was the target of extensive biogeochemical sampling from March 2014 to September 2015, as part of the UK Shelf Sea Biogeochemistry research programme (UK-SSB). Here, we use the UK-SSB carbonate chemistry and macronutrient measurements to investigate the biogeochemical seasonality in this temperate, seasonally stratified system. Following the onset of stratification, near-surface biological primary production during spring and summer removed dissolved inorganic carbon and nutrients, and a fraction of the sinking particulate organic matter was subsequently remineralised beneath the thermocline. Water column inventories of these variables throughout 1.5 seasonal cycles, corrected for air-sea CO2 exchange and sedimentary denitrification and anammox, isolated the combined effect of net community production (NCP) and remineralisation on the inorganic macronutrient inventories. Overall inorganic inventory changes suggested that a significant fraction (>50%) of the annual NCP of around 3 mol-C m–2 yr–1 appeared to be stored within a long-lived organic matter (OM) pool with a lifetime of several months or more. Moreover, transfers into and out of this pool appeared not to be in steady state over the one full seasonal cycle sampled. Accumulation of such a long-lived and potentially C-rich OM pool is suggested to be at least partially responsible for the estimated net air-to-sea CO2 flux of ∼1.3 mol-C m–2 yr–1 at our study site, while providing a mechanism through which a nutrient-conserving continental shelf pump for CO2 could potentially operate in this and other similar regions

Trait‐based analysis of subpolar North Atlantic phytoplankton and plastidic ciliate communities using automated flow cytometer

Plankton are an extremely diverse and polyphyletic group, exhibiting a large range in morphological and physiological traits. Here, we apply automated optical techniques, provided by the pulse‐shape recording automated flow cytometer—CytoSense—to investigate trait variability of phytoplankton and plastidic ciliates in Arctic and Atlantic waters of the subpolar North Atlantic. We used the bio‐optical descriptors derived from the CytoSense (light scattering [forward and sideward] and fluorescence [red, yellow/green and orange from chlorophyll a, degraded pigments, and phycobiliproteins, respectively]) and translated them into functional traits to demonstrate ecological trait variability along an environmental gradient. Cell size was the master trait varying in this study, with large photosynthetic microplankton (> 20 μm in cell diameter), including diatoms as single cells and chains, as well as plastidic ciliates found in Arctic waters, while small‐sized phytoplankton groups, such as the picoeukaryotes (< 4 μm) and the cyanobacteria Synechococcus were dominant in Atlantic waters. Morphological traits, such as chain/colony formation and structural complexity (i.e., cellular processes, setae, and internal vacuoles), appear to favor buoyancy in highly illuminated and stratified Arctic waters. In Atlantic waters, small cell size and spherical cell shape, in addition to photo‐physiological traits, such as high internal pigmentation, offer chromatic adaptation for survival in the low nutrient and dynamic mixing waters of the Atlantic Ocean. The use of automated techniques that quantify ecological traits holds exciting new opportunities to unravel linkages between the structure and function of plankton communities and marine ecosystems

VCI : a VHDL-C interface generation tool for cosimulation

International audienceThis paper deals with distributed cosimulation for heterogeneous systems prototyping. We presents a cosimulation environment who allows to handle all kinds of distributed architectures, any number of hardware or software modules, cosimulation at different abstraction levels, several cosimulation scenarios and smooth transition to the cosynthesis process. This flexibility is obtained thanks to an automatic cosimulation interface generation tool able to create the link between simulation environments. The advantages of our cosimulation methodology and more precisely the automatic cosimulation interface generation tool will be described by an example

Multi-frequency quantitative imaging of high contrat objects : canonical approximation

We consider the inverse scattering problem for three dimensional cylindrical objects which are infinite in the axial direction. Our aim being to achieve quantitative ultrasound imaging of bones, we focus at first on the simplified problem of reconstructing one section of the cylinder perpendicular to its axis. Several difficulties inherent to the bone structure and its environment (flesh) have to be dealt with, in order to solve the problem in vivo. Moreover, as in many imaging applications the problem is non-linear and the solution is not unique [l]. We focus in this paper on the quantitative reconstruction of the mechanical parameters (velocity, density) of a cylindrical object by approximating its geometry by a canonical circular cylinder according to the ICBA method (Intercepting Canonical Body Approximation) [2].We show that using the whole frequency range of the diffracted signal increases the accuracy and the robustness of the object's mechanical parameters reconstruction

1 MCI – MULTILANGUAGE DISTRIBUTED CO-SIMULATION TOOL

Nowadays the design of complex systems requires the cooperation of several teams belonging to different cultures and using different languages. It is necessary to dispose of new design and verification methods to handle multilanguage approaches. This paper presents a multilanguage co-simulation tool that allows cosimulation of multilanguage specifications for complex systems

Bacterial community analysis of contaminated soils from Chernobyl

Shortly after the Chernobyl accident in 1986, vegetation, contaminated soil and other radioactive debris were buried in situ in trenches. The aims of this work are to analyse the structure of bacterial communities evolving in this environment since 20 years, and to evaluate the potential role of microorganisms in radionuclide migration in soils. Therefore, soil samples exhibiting contrasted radionuclides content were collected in and around the trench number 2