65 research outputs found
Dynamics and rheology of vesicles in a shear flow under gravity and microgravity
International audienceThe behaviour of a vesicle suspension in a simple shear flow between plates (Couette flow) was investigated experimentally in parabolic flight and sounding rocket experiments by Digital Holographic Microscopy. The lift force which pushes deformable vesicles away from walls was quantitatively investigated and is found to be rather well described by a theoretical model by Olla [1]. At longer shearing times, vesicles reach a steady distribution about the center plane of the shear flow chamber, through a balance between the lift force and shear induced diffusion due to hydrodynamic interactions between vesicles. This steady distribution was investigated in the BIOMICS experiment in the MASER 11 sounding rocket. The results allow an estimation of self-diffusion coefficients in vesicle suspensions and reveal possible segregation phenomena in polydisperse suspensions
Protokoll for vurdering av modningsgrad hos oppdrettstorsk
Den gjeldende protokollen for vurdering av modningsnivÄet hos oppdrettstorsk skisserer distinkte modenhetsstadier hos bÄde hann- og hunntorsk (Gadus morhua). Denne protokollen hjelper til med Ä evaluere graden av modenhet hos torsk i oppdrettsanlegg. Hvert stadium involverer en makroskopisk vurdering, som inkluderer bilder av gonadene bÄde inne og utenfor fisken, detaljerte bilder, en generell beskrivelse av gonadene og fiskemÄlinger. I tillegg inkluderer det en mikroskopisk vurdering, med histologiske bilder og beskrivelser. Protokollen gir ogsÄ retningslinjer for riktig innsamling av gonadeprÞver fra hann- og hunntorsk for videre histologiske analyser.Protokoll for vurdering av modningsgrad hos oppdrettstorskpublishedVersio
Half a century of high-latitude fisheries oceanography research on the "recruitment problem" in Northeast Arctic cod (Gadus morhua)
Predicting recruitment in a reliable fashion is a great challenge within operational fisheries advice. Here, we consulted the unique but undercommunicated IMR Cod Larva Project (1975â1990), its spin-offs, placed in an international era of advancements over the last 50 years to glance into the future. Few initiatives of this kind have applied such extensive research approaches, spanning from laboratory, mesocosm, tank, and field studies to process modelling. The âcritical periodâ concept appeared misleading, covering months rather than days of the early life history stages (ELHS) of Northeast Arctic cod. Larval feeding success was strongly modified by improved encounter rates from wind-induced turbulence. In addition, the following maternal effect studies evidenced that the dynamics of stock demography prior to spawning should be upheld to promote recruitment success. Although we now have lower-trophic level models as well as ELHS individual-based models, such models are still insufficiently reflecting the needed spatiotemporal resolution. The same problem applies to climate/circulation models. Nevertheless, this long-lasting research has significantly improved the mechanistic understanding of ELHS dynamics but also of the more predictable adult reproductive parameters. Based on a âto-list list,â we suggest research avenues that should be pursued to further improve our ability predicting recruitment strength in marine fish stocks.publishedVersio
Tracking oocyte development and the timing of skipped spawning for north-east Arctic haddock (Melanogrammus aeglefinus)
The present study tracked oocyte development over 9 months and noted incidences of âskippingâ, i.e., adults terminating their upcoming reproductive cycle, in field-caught north-east Arctic (NEA) haddock (Melanogrammus aeglefinus), currently the largest stock of this species. Applications of advanced image and histological techniques revealed the presence of cortical alveoli oocytes (CAO), which prevailed as the most advanced oocyte phase for 4â5 months. This new finding of an extended and early appearance of CAOs in this gadoid was supported by that vitellogenesis first started to appear 3âmonths later. The subsequent oocyte growth trajectories indicated that larger individuals [total length (TL) = 70âcm] typically spawn in the order of 3âweeks earlier than the smaller ones (TL = 40âcm). The spawning season appeared stretched over about 3âmonths. The majority of skipping females arrested oocyte growth at the CAO phase followed by atretic reabsorption. Compared to those individuals maturing for the spawning season, âskippersâ generally exhibited lower body condition, characterized also by relatively lower liver sizes at the time of the main spawning season. This study demonstrated well-developed skipping dynamics, but also that the CAO period, i.e., when skipping takes place, may be exceedingly long in this commercially valuable gadoid and that its reproductive cycle in many ways deviates from that of the data-rich, sympatric NEA cod (Gadus morhua).publishedVersio
Disassemblability Assessment of Power Electronic Converters for Improved Circularity
Power Electronics Converters (PEC) play a crucial role in the operation of many modern electrical systems and devices. Despite their widespread use, the lack of an efficient and cost-effective disassembly process can limit their repairability, refurbishability, remanufacturability and, ultimately, recyclability, thus hindering the circularity of products. In order to improve their circularity, it is important to assess their ease of disassembly. Therefore, this paper investigates the applicability of the âease of Disassembly Metricâ (eDiM), which is referenced in the material efficiency standards, Benelux repairability assessment method, and Repair Scoring System (RSS), to analyze the ease of disassembly of energy-related products. After identifying the limitations of the eDiM method, we refined and adapted it to make it more suitable for Printed Circuit Board (PCB)-based PEC, and thus propose a PCB-based disassemblability assessment method allowing the implementation of quantifiable requirements supporting their circularity. This standardized approach, at the PCB level, can improve the circularity of such products by facilitating design enhancements. With this approach, policymakers and designers can contribute more effectively to the transition to a circular economy in PCB electronics, particularly in the field of power electronics
Ăvaluation de la dĂ©montabilitĂ© des convertisseurs Ă©lectroniques de puissance pour une circularitĂ© amĂ©liorĂ©e
Les convertisseurs Ă©lectroniques de puissance (CEP) jouent un rĂŽle crucial dans le fonctionnement de nombreux systĂšmes et appareils Ă©lectriques modernes. MalgrĂ© leur utilisation rĂ©pandue, l'absence d'un processus de dĂ©montage efficace et rentable pour ces dispositifs peut limiter leur rĂ©utilisation, leur rĂ©parabilitĂ©, leur remanufacturabilitĂ© et, en fin de compte, leur recyclabilitĂ©, entravant ainsi la circularitĂ© des produits. Afin de comprendre la circularitĂ© de ces produits, il est important dâĂ©valuer la difficultĂ© du dĂ©sassemblage. Par consĂ©quent, cet article Ă©tudie l'applicabilitĂ© de la facilitĂ© de dĂ©sassemblage (eDiM), qui est rĂ©fĂ©rencĂ©e dans la norme EN 45554, pour analyser le dĂ©sassemblage des produits Ă©lectroniques Ă base de circuits imprimĂ©s (PCB). AprĂšs avoir identifiĂ© les limites de la mĂ©thode eDiM, nous avons affinĂ© et adaptĂ© la mĂ©thode pour la rendre plus appropriĂ©e pour les CEP basĂ©s sur les PCB. L'objectif de ce document est d'introduire une mĂ©thode d'Ă©valuation de la dĂ©montabilitĂ© qui est spĂ©cifique aux CEP basĂ©s sur les cartes de circuits imprimĂ©s (PCB) et de permettre la mise en Ćuvre d'exigences quantifiables pour les produits soutenant l'Ă©conomie circulaire. La mĂ©thode proposĂ©e prĂ©sente une approche normalisĂ©e pour Ă©valuer la facilitĂ© de dĂ©montage au niveau des PCB, facilitant ainsi l'identification des amĂ©liorations de conception susceptibles d'amĂ©liorer leur circularitĂ©. En utilisant cette mĂ©thode d'Ă©valuation, les dĂ©cideurs politiques et les concepteurs peuvent contribuer plus efficacement Ă la transition vers une Ă©conomie plus circulaire dans l'Ă©lectronique des PCB et plus particuliĂšrement dans l'Ă©lectronique de puissance
Highly mixed impacts of near-future climate change on stock productivity proxies in the North East Atlantic
Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resourcesâranging from data-poor to data-rich stocksâin the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region is one of the most productive waters in the world but subjected to pronounced climate change, especially in the northernmost part. In this climate impact assessment, we applied a hybrid solution combining expert opinions (scorings)âsupported by an extensive literature reviewâwith mechanistic approaches, considering stocks in three different large marine ecosystems, the North, Norwegian and Barents Seas. This approach enabled calculation of the directional effect as a function of climate exposure and sensitivity attributes (life-history schedules), focusing on local stocks (conspecifics) across latitudes rather than the species in general. The resulting synopsis (50â82°N) contributes substantially to global assessments of major fisheries (FAO, The State of World Fisheries and Aquaculture, 2020), complementing related studies off northeast United States (35â45°N) (Hare et al., PLoS One, 2016, 11, e0146756) and Portugal (37â42°N) (Bueno-Pardo et al., Scientific Reports, 2021, 11, 2958). Contrary to prevailing fisheries forecasts elsewhere, we found that most assessed stocks respond positively. However, the underlying, extensive environmental clines implied that North East Atlantic stocks will develop entirely different depending upon the encountered stressors: cold-temperate stocks at the southern and Arctic stocks at the northern fringes appeared severely negatively impacted, whereas warm-temperate stocks expanding from south were found to do well along with cold-temperate stocks currently inhabiting below-optimal temperatures in the northern subregion.publishedVersio
Ătude de la variabilitĂ© de lâembryogenĂšse chez la perche commune : dĂ©veloppement dâapproches alternatives
Currently, the durability of the aquaculture developmental model is clearly challenged and one solution consists to diversify the fish production by the domestication of new species such as the Eurasian perch (P. fluviatilis), a freshwater species promising and valuable for the diversification of European aquaculture. Several aspects of its reproductive biology are well known, nevertheless, only little information is available on its development. However, early developmental impairments, whose causes are unclear, actually impact the fish production quality. In this context, the present work aimed to characterize the developmental success and impairments in Eurasian perch on three main issues: (i) determine a model of normal embryogenesis table helping to (ii) define developmental impairments, in diverse rearing conditions and (iii) identify the relationships between various parameters of embryonic ontogenesis to characterize different patterns of developmental success. The first part of this study allowed identifying the accurate timing of normal ontogenesis of this species through the definition of an alternative and flexible developmental table to describe non-model fish species, allowing the intra- and inter-specific comparisons. In the second part, the exhaustive characterization of abnormal phenotypes revealed 10 categories of deformities linked to specific organs or functions. Moreover, some of these categories seemed to be related to rearing-conditions of the breeders allowing identifying the potential effects of extrinsic factors on the development and improving the management of fish. Finally, the previous results and the parameters measured during embryogenesis help to classify the several spawns obtained with the same developmental pattern and to highlight the potential relationships between diverse phenotypes and parameters. In addition, the data analyses showed that only 3 parameters are reliable to assess the developmental success: survival rate at the onset of the organogenesis, hatching and deformities rates. Henceforth, these parameters and this classification could be generalized as a new strategy to assess the developmental success in other fish species. All of these results provide a good basic knowledge to study the potential effects of various extrinsic and/or intrinsic factors on the developmental success and the embryonic qualityAujourdâhui, la durabilitĂ© du modĂšle de dĂ©veloppement de lâaquaculture est de plus en plus questionnĂ©e et une des solutions proposĂ©es consisterait Ă diversifier la production piscicole via la domestication de nouvelles espĂšces comme la perche commune, Perca fluviatilis, une espĂšce dâeau douce tempĂ©rĂ©e trĂšs intĂ©ressante pour la diversification de lâaquaculture continentale europĂ©enne. De nombreux aspects de la biologie de sa reproduction sont connus cependant, peu dâinformations sont disponibles sur son dĂ©veloppement. Or, des dĂ©fauts de dĂ©veloppement prĂ©coce, dont les causes sont encore mal dĂ©finies, impactent actuellement la qualitĂ© de la production piscicole. Câest dans ce contexte que cette thĂšse vise Ă caractĂ©riser les succĂšs et dĂ©fauts de dĂ©veloppement embryonnaire chez la perche commune Ă travers trois axes principaux : (i) dĂ©terminer une table de rĂ©fĂ©rence de lâembryogenĂšse normale permettant (ii) dĂ©finir les dĂ©fauts de dĂ©veloppement tels que les malformations dans des conditions dâĂ©levage diffĂ©rentes et (iii) identifier les liens entre diffĂ©rents paramĂštres de dĂ©veloppement embryonnaire afin de dĂ©terminer des profils de dĂ©veloppement variables. La premiĂšre partie de ce travail a permis dâidentifier la sĂ©quence prĂ©cise de lâontogenĂšse normale de cette espĂšce Ă travers la dĂ©finition dâune table de dĂ©veloppement embryonnaire alternative et flexible pour des espĂšces non-modĂšles, facilitant les comparaisons intra- et inter-espĂšces. Dans un second temps, lâidentification la plus exhaustive possible de phĂ©notypes anormaux a rĂ©vĂ©lĂ© 10 grandes catĂ©gories de malformations associĂ©es Ă des organes ou fonctions spĂ©cifiques. De plus, certains de ces dĂ©fauts semblent fortement dĂ©pendants des conditions dâĂ©levage des gĂ©niteurs ce qui permet dâidentifier lâeffet de potentiels facteurs extrinsĂšques sur le dĂ©veloppement et dâamĂ©liorer les techniques de gestion des animaux. Enfin, lâensemble de ces rĂ©sultats et des paramĂštres mesurĂ©s durant lâembryogenĂšse ont permis dâeffectuer une classification approfondie des pontes obtenues prĂ©sentant des profils de dĂ©veloppement similaires pour mettre en Ă©vidence des liens Ă©ventuels entre les divers phĂ©notypes et paramĂštres utilisĂ©s. Les analyses de donnĂ©es effectuĂ©es ont montrĂ© que seulement 3 paramĂštres Ă©taient nĂ©cessaires Ă la caractĂ©risation de 4 profils de succĂšs de dĂ©veloppement variables : les taux de survie au dĂ©but de lâorganogenĂšse, dâĂ©closion et de malformations. A lâavenir, ces paramĂštres pourraient ĂȘtre gĂ©nĂ©ralisĂ©s permettant dâhomogĂ©nĂ©iser les critĂšres dâĂ©valuation du succĂšs de dĂ©veloppement chez dâautres espĂšces dâintĂ©rĂȘt de poisson. Lâensemble de ces rĂ©sultats constituent une base solide pour Ă©tudier lâeffet des facteurs extrinsĂšques et/ou intrinsĂšques sur la qualitĂ© et le succĂšs de dĂ©veloppement embryonnair
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