The life and fate of a bubble in a geometrically perturbed Hele-Shaw channel

Motivated by the desire to understand complex transient behaviour in fluid flows, we study the dynamics of an air bubble driven by the steady motion of a suspending viscous fluid within a Hele-Shaw channel with a centred depth perturbation. Using both experiments and numerical simulations of a depth-averaged model, we investigate the evolution of an initially centred bubble of prescribed volume as a function of flow rate and initial shape. The experiments exhibit a rich variety of organised transient dynamics, involving bubble breakup as well as aggregation and coalescence of interacting neighbouring bubbles. The long-term outcome is either a single bubble or multiple separating bubbles, positioned along the channel in order of increasing velocity. Up to moderate flow rates, the life and fate of the bubble are reproducible and can be categorised by a small number of characteristic behaviours that occur in simply connected regions of the parameter plane. Increasing the flow rate leads to less reproducible time evolutions with increasing sensitivity to initial conditions and perturbations in the channel. Time-dependent numerical simulations that allow for breakup and coalescence are found to reproduce most of the dynamical behaviour observed experimentally, including enhanced sensitivity at high flow rate. An unusual feature of this system is that the set of steady and periodic solutions can change during temporal evolution because both the number of bubbles and their size distribution evolve due to breakup and coalescence events. Calculation of stable and unstable solutions in the single- and two-bubble cases reveals that the transient dynamics is orchestrated by weakly unstable solutions of the system that can appear and disappear as the number of bubbles changes

Time travelling with Triticum: An Ecotron experiment to study the wheat of the future

2. Zero hunger3. Good health and well-being12. Responsible consumption and production13. Climate action15. Life on land17. Partnerships for the goal

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

The “Cayo” Site of Roseau: Ceramic, vertebrate and isotopic analysis of a Guadeloupe Late Ceramic archaeological assemblage

The Cayo archaeological deposits documenting the contact period between European and Amerindian populations before the colonization of the Lesser Antilles are rare. Among the few sites dated to this period, the site of Roseau, excavated by Gérard Richard in the early 2000s, remains poorly investigated, especially from a stratigraphic and zooarchaeological point of view. In this study, we performed 20 new radiocarbon datings on the collagen content of rodent dentin along with new studies of the ceramic and faunal assemblages of the site. The results indicate that the archaeological assemblage is mainly associated to the Late Troumassoid, with some admixture of Early Troumassoid and Cayo elements represented in various proportions in the whole stratigraphy. Despite these elements, a chronological trend appears preserved in the stratigraphy allowing for a research of behavioral change in subsistence pattern through time. Vertebrate faunal data indicate that the two Troumassoid layers we recognized document different subsistence strategies. Indeed, the earliest inhabitants of the site were more focused on the exploitation of aquatic resources than the latest ones who more significantly exploited terrestrial fauna, especially rodents and iguanas. Carbon and oxygen stable isotope analyses performed on fossil tooth enamel of rodents (Antillomys rayi) suggest that Amerindians hunted them in both dry and wet environments. Paleontological approaches also led to the discovery of several now-extinct taxa that were part of the Amerindian diet. Our investigations point to a strong chronological variability of subsistence behaviors and improve our understanding of the accumulation history of the site.Ecosystèmes insualires tropicaux : réponse de la biocénose animale terrestre à6 000 ans d'anthropisatio

The pre-Columbian site of Roseau (Guadeloupe, F. W. I.): intra-site chronological variability of the subsistence strategies in a Late Ceramic archaeological vertebrate assemblage

Evidence for chronological change in intra-site subsistence strategies is very rare in the Amerindian record of the Lesser Antilles. The study of the vertebrate assemblage from the archaeological site of Roseau in the Guadeloupe Islands underlines the complexity and variability of Ceramic Age Amerindian subsistence behavior. This study establishes a more precise chronology of the previously identified strata of the site, and demonstrates that the Contact period was only represented by rare archaeological artifacts dispersed in the stratigraphy. The results from this assemblage indicate that the earlier occupations of the site exhibit a more intensive exploitation of aquatic vertebrate resources compared to later occupations, which have a larger focus on terrestrial fauna, especially rodents and iguanas. This unusual pattern highlights how subsistence behaviors in the Lesser Antilles during the Late and Final Ceramic periods were highly variable. This new evidence of strong inter-site variability shows that the behaviors of Amerindians are not only dependent of large scale environmental conditions but are also influenced by more complex socio-cultural and local environmental parameters

Sociétés urbaines et déchets

La gestion des déchets est au cœur des enjeux urbains contemporains. Longtemps domaine des administrations et d’entreprises spécialisées, elle est aujourd’hui devenue l’affaire de tous : trier, récupérer et recycler est aussi une question de citoyenneté. Cette attention portée aux déchets et à leur sort a mis en lumière des acteurs peu visibles qui jouent un rôle important dans leur récupération. Ceux-ci doivent trouver leur place en fonction des évolutions des systèmes de gestion institutionnels. Lorsque ces derniers sont défaillants, l’activité des acteurs invisibles de la récupération devient fondamentale pour libérer la ville de ses rebuts. Sociétés urbaines et déchets propose une mise en perspective de dix-huit études, au nord et au sud, où ces acteurs de la récupération sont à l’œuvre. Entre marginalisation et reconnaissance, entre exclusion et intégration, les récupérateurs sont les premiers maillons de systèmes en mutation. Avec des effets très différents selon les contextes locaux, les responsables politiques tentent de contrôler, réformer et moderniser les modalités de gestion des déchets en y associant des entreprises privées, locales ou multinationales. Cet ouvrage ambitionne d’éclairer les tensions et les articulations entre les acteurs qui participent à la gestion des déchets dans l’espace urbain : les dynamiques présentées ici témoignent des inégalités socio-territoriales et des processus de marginalisation dont la récupération des déchets, de plus en plus convoités, constitue une manifestation éloquente

Time travelling with Triticum: An Ecotron experiment to study the wheat of the future

Time travelling with Triticum: An Ecotron experiment to study the wheat of the futur