Langasite Based Surface Acoustic Wave Sensors for High Temperature Chemical Detection in Harsh Environment

This work presents a stand-alone portable device for high temperature assessment. The system includes a Langasite (LGS) acoustic sensor, a ceramic heater and a platform with RF connections for remote in-situ measurements. The packaging consists in a hermetic stainless steel cell which enables safe gas detection. In situ temperature measurements have been achieved thanks to the integrated heater and have been compared with finite element modeling. The thermal behavior was successfully investigated in the temperature range 25-450°C. The resulting experimental data have been compared with different theoretical models, using several sets of LGS constants, and their agreement is discussed

The role of Southern Ocean processes in orbital and millennial CO2 variations – A synthesis

International audienceRecent progress in the reconstruction of atmospheric CO2 records from Antarctic ice cores has allowed for the documentation of natural CO2 variations on orbital time scales over the last up to 800,000 years and for the resolution of millennial CO2 variations during the last glacial cycle in unprecedented detail. This has shown that atmospheric CO2 varied within natural bounds of approximately 170-300 ppmv but never reached recent CO2 concentrations caused by anthropogenic CO2 emissions. In addition, the natural atmospheric CO2 concentrations show an extraordinary correlation with Southern Ocean climate changes, pointing to a significant (direct or indirect) influence of climatic and environmental changes in the Southern Ocean region on atmospheric CO2 concentrations. Here, we compile recent ice core and marine sediment records of atmospheric CO2, temperature and environmental changes in the Southern Ocean region, as well as carbon cycle model experiments, in order to quantify the effect of potential Southern Ocean processes on atmospheric CO2 related to these orbital and millennial changes. This shows that physical and biological changes in the SO are able to explain substantial parts of the glacial/interglacial CO2 change, but that none of the single processes is able to explain this change by itself. In particular, changes in the Southern Ocean related to changes in the surface buoyancy flux, which in return is controlled by the waxing and waning of sea ice may favorably explain the high correlation of CO2 and Antarctic temperature on orbital and millennial time scales. In contrast, the changes of the position and strength of the westerly wind field were most likely too small to explain the observed changes in atmospheric CO2 or may even have increased atmospheric CO2 in the glacial. Also iron fertilization of the marine biota in the Southern Ocean contributes to a glacial drawdown of CO2 but turns out to be limited by other factors than the total dust input such as bioavailability of iron or macronutrient supply

Sperm nuclear vacuoles, as assessed by motile sperm organellar morphological examination, are mostly of acrosomal origin

Microinjection of nuclear vacuole-free spermatozoa selected by motile sperm organellar morphological examination (MSOME) has been claimed to enhance assisted reproduction treatment outcome compared with intracytoplasmic sperm injection. However, the nature of these nuclear vacuoles is unclear, since their localization at the front of the sperm head suggests they might be of acrosomal origin. To study this hypothesis, acrosomal status was evaluated using Pisum sativum agglutinin staining on a smear, together with sperm organellar morphological examination using the same optics as for MSOME on 30 sperm samples from infertile patients, yielding >3200 spermatozoa. Vacuoles were present in 61% of spermatozoa when acrosomal material or intact acrosomes were observed, versus 29% when spermatozoa were acrosome reacted (P<0.0001). Induction of the acrosomal reaction by ionophore A23587 from 17.4% to 36.1% significantly increased the percentage of vacuole-free spermatozoa from 41.2% to 63.8% (P<0.001). These data suggest that most nuclear vacuoles are of acrosomal origin. Hence, the best spermatozoa selected by MSOME are mostly acrosome-reacted spermatozoa. As microinjection of spermatozoa with a persistent acrosome drastically hampers embryo development in animal models, this suggests that the improvement in pregnancy rates reported following intracytoplasmic injection of morphologically selected sperm might be due to the procedure allowing injection of acrosome-reacted spermatozoa.

Modular architecture of the microfactories for automatic micro-assembly

International audienceThe construction of a new generation of MEMS which includes micro-assembly steps in the current microfabrication process is a big challenge. It is necessary to develop new production means named micromanufacturing systems in order to perform these new assembly steps. The classical approach called “top-down” which consists in a functional analysis and a definition of the tasks sequences is insufficient for micromanufacturing systems. Indeed, the technical and physical constraints of the microworld (e.g. the adhesion phenomenon) must be taken into account in order to design reliable micromanufacturing systems. A new method of designing micromanufacturing systems is presented in this paper. Our approach combines the general “top-down” approach with a “bottom-up” approach which takes into account technical constraints. The method enables to build a modular architecture for micromanufacturing systems. In order to obtain this modular architecture, we have devised an original identification technique of modules and an association technique of modules. This work has been used to design the controller of an experimental robotic micro-assembly station

Science, technology and innovation for economic growth: Linking policy research and practice in ‘STIG Systems’

This paper reflects on the relevance of “systems-theoretic” approaches to the interdependent policy issues relating to the dynamics of science, technology and innovation and their relationship to economic growth. Considering the approach that characterizes much of the current economics literature's treatment of technology and growth policies, we pose the critical question: what kind of systems paradigm is likely to prove particularly fruitful in that particular problem-domain? Evolutionary, neo-Schumpeterian, and complex system dynamics approaches are conceptually attractive, and we examine their respective virtues and limitations. Both qualities are readily visible when one tries to connect systems-relevant research with practical policy-making in this field.

Albedo and LAI estimates from FORMOSAT-2 data for crop monitoring

Phytocystatins: A comparative analysis of cysteine protease inhibitors in plants

Understanding plant cystatin structure/function relationships through homology modeling

In situ X-ray tomography observation of inhomogeneous deformation in semi-solid aluminium alloys

International audienceThe aim of this paper is to report the very first in situ observations of the deformation behaviour of an Al–Cu alloy in the semi-solid state by using ultrafast, high-resolution X-ray microtomography. It is shown that this deformation is non-homogeneous and involves an accumulation of liquid at an intergranular surface nearly perpendicular to the strain axis. Once the liquid is no longer able to feed such a region, micropores form and grow at this surface, finally leading to a crack

Dynamics of an estuarine nursery ground: the spatio-temporal relationship between the river flow and the food web of the juvenile common sole (Solea solea, L.) as revealed by stable isotopes analysis

Estuaries are essential fish habitats because they provide nursery grounds for a number of marine species. Previous studies in the Bay of Vilaine (part of the Bay of Biscay, France) have underlined the estuarine dependence of juvenile common sole (Solea solea, L) and shown that the extent of sole nursery grounds was positively influenced by the variability of the river flow. In the present study, stable carbon and nitrogen isotopes were used to describe the trophic network until the young-of-the-year sole and to compare interannual variations in the dominant trophic pathways in the sole nursery areas in this bay. Particulate organic matter (POM), sediment organic matter (SOM), microphytobenthos, benthic invertebrate sole prey and young-of-the-year common sole were collected during the summer over 4 years characterised by contrasting river discharges. POM isotopic signatures were used to identify the origins of nutrient and organic matter assimilated into the estuarine food web through benthic organisms to juvenile common sole. Interannual spatial variations were found in the POM carbon stable isotope signatures, with the importance of these variations depending on the interannual fluctuations of the river flow. Moreover, the spatio-temporal variability of this POM isotopic signature was propagated along the food webs up to juvenile sole, confirming the central role of river discharge and terrigeneous subsidy input in the estuarine benthic food web in determining the size of the sole nursery habitat. (C) 2009 Elsevier B.V. All rights reserved