Electrowetting: from basics to applications

Electrowetting has become one of the most widely used tools for manipulating tiny amounts of liquids on surfaces. Applications range from 'lab-on-a-chip' devices to adjustable lenses and new kinds of electronic displays. In the present article, we review the recent progress in this rapidly growing field including both fundamental and applied aspects. We compare the various approaches used to derive the basic electrowetting equation, which has been shown to be very reliable as long as the applied voltage is not too high. We discuss in detail the origin of the electrostatic forces that induce both contact angle reduction and the motion of entire droplets. We examine the limitations of the electrowetting equation and present a variety of recent extensions to the theory that account for distortions of the liquid surface due to local electric fields, for the finite penetration depth of electric fields into the liquid, as well as for finite conductivity effects in the presence of AC voltage. The most prominent failure of the electrowetting equation, namely the saturation of the contact angle at high voltage, is discussed in a separate section. Recent work in this direction indicates that a variety of distinct physical effects¿rather than a unique one¿are responsible for the saturation phenomenon, depending on experimental details. In the presence of suitable electrode patterns or topographic structures on the substrate surface, variations of the contact angle can give rise not only to continuous changes of the droplet shape, but also to discontinuous morphological transitions between distinct liquid morphologies. The dynamics of electrowetting are discussed briefly. Finally, we give an overview of recent work aimed at commercial applications, in particular in the fields of adjustable lenses, display technology, fibre optics, and biotechnology-related microfluidic devices

La formation permanente des travailleurs handicapés : vers une nouvelle place du travail dans la mission médico-sociale ?

Les établissements et services d’aide par le travail (ESAT) accueillent 100 000 travailleurs handicapés. Fondé sur 18 monographies d’ESAT en région Rhône Alpes réalisées en 2009, cet article analyse l’impact des mesures financières d’incitation au développement de la formation. Malgré une hausse générale des dépenses de formation, les efforts de formation restent très disparates entre les établissements. Le développement de la formation est significatif notamment quand l’ESAT perçoit que sa mission ne se limite pas à la mise au travail de l’usager mais s’étend à l’accompagnement de son projet.In France, reintegration centres for disabled workers care for some 100,000 adults. Through eighteen case studies of centres located in the Rhône-Alpes Region, this article deals with the impact a recent state regulation granting financial subsidies to the centers which develop disabled workers continuing education. The results show that despite a general increase of training expenses, training efforts vary considerably from one center to the other. Centers which consider that their objective is to offer itineraries adapted to each person’s life project developed continuing education. But in centers where their main mission is limited to providing work to users, training remains marginal.Die französischen Einrichtungen zur Heranführung von Behinderten an das Erwerbsleben ‚ESAT‘ (Etablissements et services d’aide par le travail) betreuen 100 000 behinderte Arbeitskräfte. Gestützt auf 18 ESAT-Einzeldarstellungen aus der Region Rhône-Alpes aus dem Jahr 2009 wird in diesem Artikel die Wirkung finanzieller Anreize auf die Weiterentwicklung der Ausbildung untersucht. Trotz allgemeiner Ausgabenerhöhungen für die Ausbildung sind die Bemühungen je nach Einrichtung jedoch sehr unterschiedlich. Die Weiterentwicklung der Ausbildung ist besonders dann signifikant, wenn das ESAT seine Aufgabe nicht nur als Arbeitsbeschaffung für den Nutzer betrachtet, sondern ihn bei seinen beruflichen Vorhaben auch begleitet.Los establecimientos y servicios de ayuda por el trabajo (ESAT) reciben a 100.000 trabajadores discapacitados. Basado en 18 monografías de ESAT de la región Rhône Alpes realizadas en 2009, este artículo analiza el impacto de las medidas financieras de estímulo al desarrollo de la formación. A pesar de un aumento general de los gastos en formación, los esfuerzos de formación siguen siendo muy dispares entre los establecimientos. El desarrollo de la formación es significativo, especialmente cuando el ESAT percibe que su misión no se limita a poner a trabajar al usuario sino que se extiende a acompañar su proyecto

An extremal model for amorphous media plasticity

An extremal model for the plasticity of amorphous materials is studied in a simple two-dimensional anti-plane geometry. The steady-state is analyzed through numerical simulations. Long-range spatial and temporal correlations in local slip events are shown to develop, leading to non-trivial and highly anisotropic scaling laws. In particular, the plastic strain is shown to statistically concentrate over a region which tends to align perpendicular to the displacement gradient. By construction, the model can be seen as giving rise to a depinning transition, the threshold of which (i.e. the macroscopic yield stress) also reveal scaling properties reflecting the localization of the activity.Comment: 4 pages, 5 figure

Effects of canopy gap size on recruitment and invasion of the non-indigenous Rubus alceifolius in lowland tropical rain forest on Réunion

An important challenge of invasion biology is to understand how interactions between species traits and ecosystem properties enable alien species to become invasive at particular locations. We investigated how gap dynamics in a tropical rain forest on the island of Réunion affected the invasiveness of alien plants. In the 12 000-m2 study area, alien plants occupied 24.9% of the area of gaps, which represented 5.62% of the forest area, but only 0.8% of the understorey area. The most abundant invasive species was Rubus alceifolius, which formed dense, monospecific stands in the largest gaps (> 25 m2). Although plants could persist in the shade, a germination experiment revealed that canopy openings were essential for seedling establishment. A cyclone that struck the study area in 2002 caused a temporary thinning of the canopy, increasing light levels to above the threshold needed for germination of R. alceifolius and also stimulating the growth of established plants. We conclude that the ability of this and other alien species to colonize intact lowland tropical rain forest is strongly influenced by the prevailing gap dynamics. Because gaps are also essential for the regeneration of many native trees in our study area, there is a real danger of the forest being progressively degraded by alien plants. There are no simple solutions to controlling species such as Rubus alceifolius, but efforts should be focused mainly upon the larger gaps where the species are most invasiv

Wetting Heterogeneities in Porous Media Control Flow Dissipation

Pressure-controlled displacement of an oil-water interface is studied in dense packings of functionalized glass beads with well-defined spatial wettability correlations. An enhanced dissipation is observed if the typical extension ξ of the same-type wetting domains is smaller than the average bead diameter d. Three-dimensional imaging using x-ray microtomography shows that the frequencies n(s) of residual droplet volumes s for different ξ collapse onto the same curve. This indicates that the additional dissipation for small ξ is due to contact line pinning rather than an increase of capillary break-up and coalescence events

Use of the atmospheric generators for capnophilic bacteria Genbag-CO2 for the evaluation of in vitro Plasmodium falciparum susceptibility to standard anti-malarial drugs

Background: The aim of this study was to evaluate the cultivation system in which the proper atmospheric conditions for growing Plasmodium falciparum parasites were maintained in a sealed bag. The Genbag (R) system associated with the atmospheric generators for capnophilic bacteria Genbag CO2 (R) was used for in vitro susceptibility test of nine standard anti-malarial drugs and compared to standard incubator conditions. Methods: The susceptibility of 36 pre-identified parasite strains from a wide panel of countries was assessed for nine standard anti-malarial drugs (chloroquine, quinine, mefloquine, monodesethylamodiaquine, lumefantrine, dihydroartemisinin, atovaquone and pyrimethamine) by the standard 42-hour H-3-hypoxanthine uptake inhibition method using the Genbag CO2 (R) system and compared to controlled incubator conditions (5% CO2 and 10% O-2). Results: The counts per minute values in the control wells in incubator atmospheric conditions (5% CO2 and 10% O-2) were significantly higher than those of Genbag (R) conditions (2738 cpm vs 2282 cpm, p < 0.0001). The geometric mean IC50 estimated under the incubator atmospheric conditions was significantly lower for atovaquone (1.2 vs 2.1 nM, p = 0.0011) and higher for the quinolines: chloroquine (127 vs 94 nM, p < 0.0001), quinine (580 vs 439 nM, p < 0.0001), monodesethylamodiaquine (41.4 vs 31.8 nM, p < 0.0001), mefloquine (57.5 vs 49.7 nM, p = 0.0011) and lumefantrine (23.8 vs 21.2 nM, p = 0.0044). There was no significant difference of IC50 between the 2 conditions for dihydroartemisinin, doxycycline and pyrimethamine. To reduce this difference in term of anti-malarial susceptibility, a specific cut-off was estimated for each drug under Genbag (R) conditions by regression. The cut-off was estimated at 77 nM for chloroquine (vs 100 nM in 10% O-2), 611 nM for quinine (vs 800 nM), 30 nM for mefloquine (vs 30 nM), 61 nM for monodesethylamodiaquine (vs 80 nM) and 1729 nM for pyrimethamine (vs 2000 nM). Conclusions: The atmospheric generators for capnophilic bacteria Genbag CO2 (R) is an appropriate technology that can be transferred to the field for epidemiological surveys of drug-resistant malaria. The present data suggest the importance of the gas mixture on in vitro microtest results for anti-malarial drugs and the importance of determining the microtest conditions before comparing and analysing the data from different laboratories and concluding on malaria resistance

Geological subsidence and sinking islands: the case of Manono (Samoa)

W.R. Dickinson, as part of his wide study of the geological history of the Pacific islands, has linked the unique case of the deeply submerged Lapita site of Mulifanua in western Upolu (Samoa) to the slow subsidence of Upolu island. Recent archaeological research on the neighbouring small island of Manono has yielded new and detailed data on this geological process. A series of new dates has allowed us to define the speed of the subsidence and demonstrate the massive environmental changes to which the local population has had to adapt over the past 2000 years

Contribution à l’archéologie du « séjour paisible » kanak : étude et mise en valeur du hameau de Tipéhéne, Pombeï (Nouvelle-Calédonie)

Malgré les résultats multiples obtenus par le Pr José Garanger dans les années 1960-1970 lors des programmes de recherches liant traditions orales océaniennes et données archéologiques, peu de travaux ont été depuis menés en Mélanésie insulaire sur ce thème. Cet article souhaite contribuer à ce sujet, en présentant la première étude archéologique d’un hameau kanak ancien de la Grande Terre calédonienne. Le relevé du site de Tipéhéne, la fouille des différentes structures d’habitat dans le cadre d’un programme de mise en valeur touristique et culturelle du lieu, ainsi que la réalisation d’une série de datations C14, ont permis de montrer une chronologie d’occupation confirmant dans ses grandes lignes les données des traditions orales. La mise au jour de structurations variées des seuils des tertres, dont certaines de formes non répertoriées jusqu’à ces fouilles, souligne également la diversité des aménagements traditionnels des espaces d’habitat kanak. Ce type d’étude demande à être multiplié afin de répondre aux questions adressées par la population autochtone du pays aux archéologues sur son passé traditionnel.Even if Pr José Garanger obtained a great number of results in the 1960s-1970s through research programs associating Pacific oral traditions and archaeological data, few research projects have since been conducted in Island Melanesia on this theme. This paper wishes to contribute to the topic, by presenting the first archaeological study of an old kanak settlement of New Caledonia’s Grande Terre. The mapping of the site of Tipéhéne, the excavation of a number of the house structures as part of a rehabilitation program linked to a touristic and cultural project on this site, as well as the fulfilling of a number of C14 dates, have allowed to show a settlement and occupation chronology following in its main points the data presented by oral traditions. The uncovering of various types of house entrances, some never identified prior to these excavations, enhances the diversity of traditional structuring of the kanak households. This type of study needs to be multiplied, to help answer the questions asked to archaeologists by the indigenous population of the country on its traditional past.

In vitro susceptibility to quinine and microsatellite variations of the Plasmodium falciparum Na+/H+ exchanger (Pfnhe-1) gene: the absence of association in clinical isolates from the Republic of Congo

<p>Abstract</p> <p>Background</p> <p>Quinine is still recommended as an effective therapy for severe cases of <it>Plasmodium falciparum </it>malaria, but the parasite has developed resistance to the drug in some cases. Investigations into the genetic basis for quinine resistance (QNR) suggest that QNR is complex and involves several genes, with either an additive or a pairwise effect. The results obtained when assessing one of these genes, the plasmodial Na⁺/H⁺exchanger, <it>Pfnhe-1</it>, were found to depend upon the geographic origin of the parasite strain. Most of the associations identified have been made in Asian strains; in contrast, in African strains, the influence of <it>Pfnhe </it>on QNR is not apparent. However, a recent study carried out in Kenya did show a significant association between a <it>Pfnhe </it>polymorphism and QNR. As genetic differences may exist across the African continent, more field data are needed to determine if this association exists in other African regions. In the present study, association between <it>Pfnhe </it>and QNR is investigated in a series of isolates from central Africa.</p> <p>Methods</p> <p>The sequence analysis of the polymorphisms at the <it>Pfnhe-1 </it>ms4760 microsatellite and the evaluation of <it>in vitro </it>quinine susceptibility (by isotopic assay) were conducted in 74 <it>P. falciparum </it>isolates from the Republic of Congo.</p> <p>Results</p> <p>Polymorphisms in the number of DNNND or NHNDNHNNDDD repeats in the <it>Pfnhe-1 </it>ms4760 microsatellite were not associated with quinine susceptibility.</p> <p>Conclusions</p> <p>The polymorphism in the microsatellite ms4760 in <it>Pfnhe-1 </it>that cannot be used to monitor quinine response in the regions of the Republic of Congo, where the isolates came from. This finding suggests that there exists a genetic background associated with geographic area for the association that will prevent the use of <it>Pfnhe </it>as a molecular marker for QNR. The contribution of <it>Pfnhe </it>to the <it>in vitro </it>response to quinine remains to be assessed in other regions, including in countries with different levels of drug pressure.</p