On Active Current Selection for Lagrangian Profilers

Autonomous Lagrangian profilers are now widely used as measurement and monitoring platforms, notably in observation programs as Argo. In a typical mode of operation, the profilers drift passively at their parking depthbefore making a vertical profile to go back to the surface. This paperpresents simple and computationally-efficient control strategies to activelyselect and use ocean currents so that a profiler can autonomously reach adesired destination. After briefly presenting a typical profiler andpossible mechanical modifications for a coastal environment, we introducesimple mathematical models for the profiler and the currents it will use. Wethen present simple feedback controllers that, using the direction of thecurrents and taking into account the configuration of the environment(coastal or deep-sea), is able to steer the profiler to any desiredhorizontal location. To illustrate the approach, a few results are presentedusing both simulated currents and real current velocity profiles from theNorth Sea

Algebraic Time-derivative Estimation in the Context of Reconstructibility

Das sogenannte algebraische Verfahren zur Schätzung von Zeitableitungen gemessener Signale, wie von Fliess und Sira Ramírez vorgeschlagen, wird aus klassischen Resultaten der Optimalschätzung hergeleitet. Insbesondere wird anhand einfacher Rechnungen gezeigt, wie sich das algebraische Verfahren als ein Sonderfall der Zustandsrekonstruktion mit Hilfe von Rekonstruierbarkeits-Gramschen ergibt. Abschließend werden Verbindungen zu weiteren Verfahren, wie Least-Squares und dem Kalman-Filter, hergestellt und Implikationen für die Praxis erörtert. The so-called algebraic approach to time-derivative estimation of measurement signals, proposed by Fliess and Sira Ramírez, is developed out of classical results from optimal estimation theory. By means of simple calculations it is shown that the algebraic method may be obtained as a special case of state reconstruction using reconstructibility Gramians. The paper concludes with links to further estimation methods, as least-squares estimation and Kalman-filtering, and points out practical implications. Copyright © 2009 Oldenbourg Wissenschaftsverlag Gmb

Global entrainment of transcriptional systems to periodic inputs

This paper addresses the problem of giving conditions for transcriptional systems to be globally entrained to external periodic inputs. By using contraction theory, a powerful tool from dynamical systems theory, it is shown that certain systems driven by external periodic signals have the property that all solutions converge to a fixed limit cycle. General results are proved, and the properties are verified in the specific case of some models of transcriptional systems. The basic mathematical results needed from contraction theory are proved in the paper, making it self-contained

Genetic parameters of colostrum and calf serum antibodies in Swedish dairy cattle

BackgroundA sufficient IgG content in the colostrum is essential for the newborn calf, as it provides passive immunity which substantially affects the probability of survival during rearing. Failure of passive transfer (FPT) occurs when a calf does not absorb enough antibodies from the colostrum and is defined by an IgG concentration in calf serum lower than 10 g/L. Apart from delayed access to colostrum, FPT can be due to a low production of IgG in the mother or poor IgG absorption by the calf. The aim of this study was to estimate the genetic background of antibody levels and indicator traits for antibodies in the colostrum and calf serum, and their correlation with milk production.ResultsColostrum data were available for 1340 dairy cows with at least one calving and calf serum data were available for 886 calves from these cows. Indicator traits for antibody concentrations were estimated using refractometry (a digital Brix refractometer for colostrum and an optical refractometer for serum), and enzyme-linked immunosorbent assays (ELISA) were used to determine the levels of total IgG and natural antibodies (NAb) of various antibody isotypes in the colostrum and calf serum. Colostrum traits had heritabilities ranging from 0.16 to 0.31 with repeatabilities ranging from 0.21 to 0.55. Brix percentages had positive genetic correlations with all colostrum antibody traits including total IgG (0.68). Calf serum antibody concentrations had heritabilities ranging from 0.25 to 0.59, with a significant maternal effect accounting for 17 to 27% of the variance. When later in life calves produced their first lactation, the lactation average somatic cell score was found to be negatively correlated with NAb levels in calf serum.Conclusions​​​​​​​Our results suggest that antibody levels in the colostrum and calf serum can be increased by means of selection

First report of eprinomectin-resistant isolates of Haemonchus contortus in 5 dairy sheep farms from the Pyrénées Atlantiques département in France

Infection of sheep by gastrointestinal nematodes (GIN) in pastoral systems such as those found in the South Western area of France, the Pyrénées Atlantiques, is one of the main reasons for economic loss and degradation of their welfare. In the present study, the efficacy of eprinomectin (EPN) was monitored on farms from this area following suspicion of lack of anthelmintic efficacy. Suspicions were raised by veterinarians, based on clinical signs ranging from milk and body condition loss, to anaemia, and mortality. Resistance was evaluated according to the World Association for the Advancement for Veterinary Parasitology (WAAVP) guidelines using fecal egg count reduction tests reinforced by individual analysis of drug concentration in the serum of all treated ewes by high-performance liquid chromatography (HPLC). EPN was administered by subcutaneous (SC) and topical (T) route according to manufacturer's requirements, as well as by the oral route (O) with the topical solution according to off-labelled practices in the field. For the first time in France, the presence of resistant isolates of Haemonchus contortus to EPN was observed in 5 dairy sheep farms. The HPLC dosages showed exposure of worms to concentrations compatible with anthelmintic activity for animals treated by the SC and O routes. By contrast, they showed under exposure to the drug of most individuals treated by the T route. EPN is the only null milk withdrawal anthelmintic molecule currently available. The presence of resistant isolates of the pathogenic H. contortus to EPN in this important dairy region requires an urgent change in grazing, and sometimes production, systems

Environmental impact of early palaeometallurgy: pollen and geochemical analysis

International audienceInterdisciplinary research was carried out in mid-level mountain areas in France with the aim of documenting historical mining and smelting activities by means of pollen and geochemical analyses. These investigations were made on cores collected in French peatlands in the Morvan (northern Massif Central), at Mont Lozère (southern Massif Central) and in the Basque Country (Pyrénées). Different periods of mining were recognised from Prehistory to modern times through the presence of anthropogenic lead in peat. Some of these were already known from archaeological dates or historical archives, especially for mediaeval and modern periods. However prehistoric ancient mining activities, as early as the Middle Bronze Age (ca. 1700 b.c.), were also discovered. They had all led to modifications in plant cover, probably related in part to forest clearance necessary to supply energy for mining and smelting

Étude expérimentale du spectre des phonons dans le vanadium et dans l'antimoniure d'indium

Lattice vibrations curves are determinated by X-ray scattering measurements in vanadium at 300° K and in indium antimonide at 4° K, 77° K and 300° K. Compton effect scattering intensity is obtained by an experimental method for InSb ; for V it is calculated from theoretical data given by Freeman. Interaction of longitudinal phonons and plasmons are taken into account in InSb.Les courbes de dispersion des vibrations du réseau sont déterminées, au moyen de l'étude de la diffusion des rayons X, pour le vanadium à 300° K et pour l'antimoniure d'indium à 4° K, 77° K et 300° K. L'intensité de la diffusion par effet Compton est obtenue expérimentalement pour l'antimoniure d'indium, elle est déduite de données théoriques obtenues par Freeman dans le cas du vanadium. L'interaction phonon˗plasmon intervient dans l'interprétation des mesures faites sur l'antimoniure d'indium.Pons-Corbeau J., Jouffroy J. Étude expérimentale du spectre des phonons dans le vanadium et dans l'antimoniure d'indium. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 90, 4, 1967. Réunion annuelle de l'Association Française de Cristallographie, Lyon, 13-15 avril 1967

A remark on nonlinear output feedback control of underwater vehicle propellers using feedback

International audienc