Excitation and resonant enhancement of axisymmetric internal wave modes

To date, axisymmetric internal wave fields, which have relevance to atmospheric internal wave fields generated by storm cells and oceanic near-inertial wave fields generated by surface storms, have been experimentally realized using an oscillating sphere or torus as the source. Here, we use a novel wave generator configuration capable of exciting axisymmetric internal wave fields of arbitrary radial form to generate axisymmetric internal wave modes. After establishing the theoretical background for axisymmetric mode propagation, taking into account lateral and vertical confinement, and also accounting for the effects of weak viscosity, we experimentally generate and study modes of different order. We characterize the efficiency of the wave generator through careful measurement of the wave amplitude based upon group velocity arguments. This established, we investigate the ability of vertical confinement to induce resonance, identifying a series of experimental resonant peaks that agree well with theoretical predictions. In the vicinity of resonance, the wave fields undergo a transition to non-linear behaviour that is initiated on the central axis of the domain and proceeds to erode the wave field throughout the domain.Comment: 15 pages, 9 figure

Adhesive factor/rabbit 2, a new fimbrial adhesin and a virulence factor from Escherichia coli O103, a serogroup enteropathogenic for rabbits

Enteropathogenic Escherichia coli-like E. coli strains belonging to serovar O103:K-:H2 and rhamnose-negative biotypes are highly pathogenic diarrhea-inducing strains for weaned European rabbits. We describe here the cloning and sequencing of the major subunit gene of a new fimbrial adhesin, adhesive factor/rabbit 2 (AF/R2), which confers on these strains the ability to attach to rabbit enterocytes and to HeLa cells in a diffuse manner and which is associated with in vivo virulence. The chromosomal operon that encodes functional AF/R2 has been cloned from strain B10. The major subunit gene afr2G, as well as an adjacent open reading frame, afr2H, has been sequenced. The Afr2G protein shows homologies with FaeG and ClpG, which are the respective major subunits of fimbrial adhesin K88 (F4) and afimbrial adhesin CS31A. Plasmid carrying the operon transcomplements an AF/R2-negative TnphoA mutant for its ability to express AF/R2. As a whole, AF/R2 is a new member of the E. coli K88 adhesin family which is associated with virulence and which may serve in the design of vaccines

Pressure dependent friction on granular slopes close to avalanche

We investigate the sliding of objects on an inclined granular surface close to the avalanche threshold. Our experiments show that the stability is driven by the surface deformations. Heavy objects generate footprint-like deformations which stabilize the objects on the slopes. Light objects do not disturb the sandy surfaces and are also stable. For intermediate weights, the deformations of the surface destabilize the objects and generate sliding. A characteristic pressure for which the solid friction is minimal is evidenced. Applications to the locomotion of devices and animals on sandy slopes as a function of their mass are proposed

Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla L.)

We defined a standardized method for discriminating candidate silver eels that may undergo catadromous migration in the following season from the sedentary fraction of a population. A combination of two qualitative criteria (state of differentiation of the lateral line and colour contrast) and one quantitative criterion (Ocular Index OI) was used to determine the development toward silvering. In the non-migratory phase, we found a gradient of the three criteria between yellow (0 criterion), presilver (1 to 2 criteria) and silver (3 criteria) eels. In the migrant phase, silver eels had ended their metamorphosis process and were characterized at the same time by the presence of the 3 silvering criteria. A mark-recapture survey using PIT-tags provided evidence that only identified silver eels (3 silvering criteria present) in the catchment actually emigrated the following season. Moreover, the use of a single criterion of silvering among the three generated large variation in the estimated proportion of candidates for emigration which varied between –22% and +63 %. Such a result confirmed that a multicriteria approach is needed to characterize in a standard way the potentially migrating silver eel

From Ohio to Hong Kong: Fostering Dynamic Learning Communities Through the Building of International Partnerships

In 2017, Franciscan OFM friars from the Diocese of Hong Kong proposed the development of an international classroom exchange between Franciscan University graduates and their Kowloon, Hong Kong parish schools. This study defines the creation, cultural issues experienced, and program curriculum proposal during the building phase of this international program. The researcher proposes the use of O’Shea’s (2014) mission and identity framework as a lens for best practices, faith formation and defined social cohesion for all participants and significant impact