Combining Finite Element Method and L-Systems Using Natural Information Flow Propagation to Simulate Growing Dynamical Systems

International audienceThis paper shows how to solve a system of di↵erential equa-tions controlling the development of a dynamical system based on finite element method and L-Systems. Our methods leads to solve a linear system of equations by propagating the flow of information throughout the structure of the developing system in a natural way. The method is illustrated on the growth of a branching system whose axes bend under their own weight

Selected plasma fatty acid levels in subsistence fed sled dogs along the Yukon River: a pilot study for biomonitoring

The introduction of the ‘western diet' marked a decline in omega-3 fatty acids rich foods and a concurrent increase in saturated and omega-6 fatty acids that persists today. Historically, circumpolar people have had a low incidence of obesity, diabetes and cardiovascular disease and this has been largely attributed to polyphenolic compounds and omega-3 fatty acids offered from subsistence foods. In this report, we studied sled dogs as an Arctic sentinel species for monitoring the effect of a changing diet on lipid profiles along the Yukon River. Subsistence fed village sled dogs along the Yukon River, maintained largely on salmon were compared with a control kennel maintained on commercial food. Profiles showed higher levels for long chain omega-3 fatty acids in village subsistence fed dogs compared to control dogs and an opposite trend for omega-6 fatty acids, establishing baseline levels for follow up studies. A comparison with data for previously published mercury levels from the same cohort of dogs revealed a positive correlation with alpha-linolenic fatty acid and a negative correlation with linoleic fatty acid. Food and nutritional security is a concern in the Arctic as the impacts of climate change and transport of contaminants become obvious. This study supports not only the nutritional value of a subsistence diet but also the utility of sled dogs as a sentinel for human dietary chang

Vascular smooth muscle contractility assays for inflammatory and immunological mediators

The blood vessels are one of the important target tissues for the mediators of inflammation and allergy; further cytokines affect them in a number of ways. We review the use of the isolated blood vessel mounted in organ baths as an important source of pharmacological information. While its use in the bioassay of vasoactive substances tends to be replaced with modern analytical techniques, contractility assays are effective to evaluate novel synthetic drugs, generating robust potency and selectivity data about agonists, partial agonists and competitive or insurmountable antagonists. For instance, the human umbilical vein has been used extensively to characterize ligands of the bradykinin B2 receptors. Isolated vascular segments are live tissues that are intensely reactive, notably with the regulated expression of gene products relevant for inflammation (e.g., the kinin B1 receptor and inducible nitric oxide synthase). Further, isolated vessels can be adapted as assays of unconventional proteins (cytokines such as interleukin-1, proteases of physiopathological importance, complement-derived anaphylatoxins and recombinant hemoglobin) and to the gene knockout technology. The well known cross-talks between different cell types, e.g., endothelium-muscle and nerve terminal-muscle, can be extended (smooth muscle cell interaction with resident or infiltrating leukocytes and tumor cells). Drug metabolism and distribution problems can be modeled in a useful manner using the organ bath technology, which, for all these reasons, opens a window on an intermediate level of complexity relative to cellular and molecular pharmacology on one hand, and in vivo studies on the other

Modelling of complex biological systems in the context of genomics: an account of a multidisciplinary thematic seminar held in Montpellier (France) in April 2005

International audienceno abstrac

VALIDATION OF GOMOS OZONE PROFILES USING NDSC LIDAR : STATISTICAL COMPARISONS

ABSTRACT The lidars deployed in the NDSC framework have been used for the validation of GOMOS onboard ENVISAT. During the commissioning phase around ten coincidences per site have been investigated. No significant bias, larger than ±5 %, has been reported except around 50 km and 20 km where both techniques are known to present some limitations. The estimated errors of both GOMOS and lidar are in good agreement with the standard deviation of the differences between coincidences. At higher latitude, comparisons are not so good because of the measurement conditions of bright limb during this period

Ultrasons et Vis Instrumentées pour Sécuriser vos Assemblages Boulonnés

La technologie proposée par la société AMG Intellifast permet de mesurer les efforts de serrage dans les assemblages vissés. Elle apporte des solutions concrètes pour maitriser la conception d’un produit, assurer sa validation pendant le développement et offrir une possibilité de maintenance préventive en vie courante. L’objet de cette présentation est de décrire la technologie mise en œuvre et de donner un aperçu des applications qui en bénéficient

High-precision ¹³C isotopic analyses in life sciences by gas and liquid chromatography coupled to isotope ratio mass spectrometry

Une nouvelle ère s'ouvre dans les mesures isotopiques de haute précision avec la commercialisation, en 2004, de la première interface permettant le couplage entre la chromatographie liquide (CL) et la spectrométrie de masse de rapport isotopique (SMRI) dédiée à l'analyse isotopique du carbone 13. Dans ce contexte, la nouveauté de ce travail réside dans l'utilisation de la CL-SMRI pour mesurer des enrichissements isotopiques d'acides aminés et glucose marqués au carbone 13 issu d'échantillons biologiques ou sur des standards à l'abondance naturelle (peptides, protéines, acides organiques et phénoliques). Entre autres, nous avons caractérisé cette interface en étudiant les rapports isotopiques à différents débits. Nous avons également comparé les enrichissements isotopiques relatifs et absolus de la valine mesurée par chromatographie gazeuse-SMRI (méthode conventionnelle) et par CL-SMRI. Enfin, nous avons exploré la mesure de rapports isotopiques (en particulier la précision et la justesse) en utilisant la chromatographie liquide à haute température

Temperature-programmed high-performance liquid chromatography coupled to isotope ratio mass spectrometry

The utility of liquid chromatography coupled to the isotope ratio mass spectrometry technique (LC-IRMS) has already been established through a variety of successful applications. However, the analytical constraint related to the use of aqueous mobile phases limits the LC separation mechanism. We report here a new strategy for high-precision (13)C isotopic analyses based on temperature-programmed LC-IRMS using aqueous mobile phases. Under these conditions, the isotopic precision and accuracy were studied. On one hand, experiments were carried out with phenolic acids using isothermal LC conditions at high temperature (170 degrees C); on the other hand, several experiments were performed by ramping the temperature, as conventionally used in a gas chromatography-based method with hydrosoluble fatty acids and pulses of CO 2 reference gas. In isothermal conditions at 170 degrees C, despite the increase of the CO 2 background, p-coumaric acid and its glucuronide conjugate gave reliable isotopic ratios compared to flow injection analysis-isotopic ratio mass spectrometry (FIA-IRMS) analyses (isotopic precision and accuracy are lower than 0.3 per thousand). On the opposite, for its sulfate conjugate, the isotopic accuracy is affected by its coelution with p-coumaric acid. Not surprisingly, this study also demonstrates that at high temperature (170 degrees C), a compound eluting with long residence time (i.e., ferulic acid) is degraded, affecting thus the delta (13)C (drift of 3 per thousand) and the peak area (compared to FIA-IRMS analysis at room temperature). Quantitation is also reported in isothermal conditions for p-coumaric acid in the range of 10-400 ng/mL and with benzoic acid as an internal standard. For temperature gradient LC-IRMS, in the area of the LC gradient (set up at 20 degrees C/min), the drift of the background observed produces a nonlinearity of SD (delta (13)C) approximately 0.01 per thousand/mV. To circumvent this drift, which impacts severely the precision and accuracy, an alternative approach, i.e., eluting the compound on the plateau of temperature studied was reported here. Other experiments with temperature-programmed LC-IRMS experiments are also reported with the presence of methanol in the injected solution to mimic residual solvent originating from the sample preparation or to slightly increase the solubility of the targeted compound for high-precision measurement

Supply chains for emerging renewable polymers: analysis of interactive sectors and complementary assets

Revitalized interest in biobased or renewable ingredients in manufacturing has emerged in recent years due to rising real petroleum prices, concerns regarding environmental impacts of crude oil, and national security issues related to petroleum resources. This research analyzes the complexities of renewable supply chains. In particular, polymers manufactured from renewable feedstocks will augment various industrial markets, such as plant material used as a renewable ingredient in paint manufacture, partially substituting for crude oil derivative ingredients. Then analysis defines polymer industrial supply chains and estimates the market opportunity for renewable polymers. A section of the analysis is devoted to complementary assets as a new product development bridge to supply chain issues