Take-off of small Leidenfrost droplets

We put in evidence the unexpected behaviour of Leidenfrost droplets at the later stage of their evaporation. We predict and observe that, below a critical size $R_l$, the droplets spontaneously take-off due to the breakdown of the lubrication regime. We establish the theoretical relation between the droplet radius and its elevation. We predict that the vapour layer thickness increases when the droplets become smaller. A satisfactory agreement is found between the model and the experimental results performed on droplets of water and of ethanol.Comment: Accepted for publication in Phys. Rev. Lett. (2012

Dynamics of elastically strained islands in presence of an anisotropic surface energy

The equilibrium solutions and coarsening dynamics of strained semi-conductor islands are investigated analytically and numerically. We develop an analytical model to study the effect of surface energy anisotropy on the dynamics coarsening of islands. We propose a simple model to explain the effect of this anisotropy on the coarsening time. We find that the anisotropy slows down the coarsening. This effect is rationalised using a quasi-analytical description of the island profile

Nonlinear evolution of a morphological instability in a strained epitaxial film

A strained epitaxial film deposited on a deformable substrate undergoes a morphological instability relaxing the elastic energy by surface diffusion. The nonlinear and nonlocal dynamical equations of such films with wetting interactions are derived and solved numerically in two and three dimensions. Above some critical thickness, the surface evolves towards an array of islands separated by a wetting layer. The island chemical potential decreases with its volume, so that the system experiences a non-interrupted coarsening described by power laws with a marked dimension dependence.Comment: 4 pages, 6 figure

Don't believe the hype? Imagined business futures and overpromising for a decarbonized economy

International climate governance is increasingly focusing on the role of the private sector. This article explores how companies translate the narrative of deep decarbonization into their entrepreneurial visions of the future. Based on a qualitative multiple case study, it shows that overpromising is an essential feature of imagined business futures, and identifies three forms of overpromising: contradiction, exaggeration, and commitment. The research article contributes to the emerging field of hype and overpromising by proposing a contextual and nuanced understanding of overpromising. The results illustrate the power of desirable transformation narratives, but also their limitations and side effects.Die internationale Klimapolitik nimmt zunehmend die Rolle des Privatsektors in den Blick. Der Beitrag untersucht, wie Unternehmen das Narrativ einer tiefgreifenden Dekarbonisierung in unternehmensspezifische Zukunftsvisionen übersetzen. Auf der Grundlage einer qualitativen vergleichenden Fallstudie wird gezeigt, dass Overpromising ein wesentliches Merkmal solcher Zukunftsvisionen ist. Es werden drei Formen von Overpromising herausgearbeitet: Widerspruch, Übertreibung und Selbstverpflichtung. Der Artikel leistet einen Beitrag zum noch jungen Forschungsfeld von Hype und Overpromising, indem er ein differenziertes und kontextabhängiges Verständnis von Overpromising vorschlägt. Die Ergebnisse zeigen die Macht wünschenswerter Transformationsnarrative, aber auch ihre Grenzen und Nebeneffekte

Ivory Gull Colonies on the Devon Island Ice Cap, Arctic Canada

Four small Ivory Gull colonies have been found on nunataks on the ice cap of eastern Devon Island. Mainly on the basis of their similarity to known breeding places of the Ivory Gull on Ellesmere Island, all four sites are believed to be those of nesting colonies the first to be reported from Devon Island.Key words: Ivory Gull, Pagophila eburnea, colonies, nunatak nesting site