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As bleeding in the neck region is a potentially life-threatening complication, we found it imperative to concretize the frequency and to identify possible reasons for this complication. A national database of all thyroid surgery performed inside the specialty of ENT Head and Neck Surgery (THYKIR) was established in January 2001. This nationwide cohort study represents 5,490 patients included until December 2007. Overall hemorrhage frequency was 4.2% with a wide variation among departments. Multiple regression analysis identified age, male gender, malignant histology and extent of surgery as independent risk factors for hemorrhage. Increased hospital stay and infection rates were found in patients treated with drainage. The median time for onset of postoperative hemorrhage was 3 h (range 0-105). Compared with international literature our incidence of post-thyroidectomy hemorrhage is relatively high. Improvement might be reached by the exchange of experience between departments with focus on adequate surgical technique and careful hemostasis.

We put in evidence the unexpected behavior of Leidenfrost droplets at the later stage of their evaporation. We predict and observe that, below a critical size Rl, 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 vapor 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.

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In the framework of the lubrication approximation, we derive a set of equations describing the steady bottom profile of Leidenfrost drops coupled with the vapor pressure. This allows to derive scaling laws for the geometry of the concave bubble encapsulated between the drop and the hot plate under it. The results agree with experimental observations in the case of droplets with radii smaller than the capillary length R c as well as in the case of puddles with radii larger than R c .

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.PACS numbers: 81.15.Aa, 68.35.Ct The dynamics of semiconductor thin films is under active scrutiny due to its importance for both fundamental science and technological applications [1,2]. Indeed, thin film elastic instabilities lead to the self-organization of nanostructures [3] potentially useful e.g. for quantum dots, wires and electronic devices with specific confinement properties [4]. A notorious experimental example is Si/Ge films on a Si substrate which exhibit a variety of structures such as pre-pyramids, pyramids, domes and huts [5,6]. Such epitaxial films experience an elastic stress due to the misfit with the substrate which is relaxed by a morphological instability similar to the Asaro-Tiller-Grinfeld thermodynamical instability in solid-liquid interfaces [7]. This instability was first observed in experiments in helium at low temperature [8] and more generally in various solid interfaces [9,10,11].Although the evolution of epitaxial films involves many complex phenomena regarding surface energy, intermixing and kinetic processes, we focus here on the main effects ruling the dynamics of the morphological instability in strained films. The dynamics is ruled here by surface diffusion driven by the interplay between isotropic surface energy and elastic energy [12,13]. When the film is infinitely thick or when the substrate is infinitely rigid, different theoretical [14,15] and numerical [16,17,18,19] approaches revealed finite-time singularities enforced by elastic stress concentration which account for experiments in thick films [8,9] where dislocations can finally develop. However, these models can not describe experiments of thin films in the Stranski-Krastanov type of growth [5,6] where the surface organizes smoothly into islands separated by a wetting layer and evolving with a coarsening dynamics under annealing [6]. A crucial issue for these systems is the wetting of the substrate by the film [20,21] which is a good candidate for regularizing the dynamics of the instability. Indeed, crack singularities were circumvented near the instability threshold by considering slope dependent wetting effects [22]. However, the interplay between elastic relaxation, surface energy and wetting interactions is still under active study [23,24] and the description of the long term dynamics of the morphological instability in a thin strained film is an open issue. In this Letter, we present a model based on continuum elasticity which we ...

Using fluorochrome labeling and a newly validated method for bone turnover estimation, we determined absolute values for canine perilabyrinthine bone remodeling. The overall capsular bone turnover was found to be 2.1% per year, compared to 13.9% per year for the neighboring cranial bones and 7.4% per year for the humerus compacta. This gross 2.1% per year conceals a vast range, from 0.13% per year for the innermost perilymphatic zone, through a centrifugal increment toward 8% to 10% per year in the periphery. The underlying individual bone remodeling units exhibit a similar centrifugal pattern in numerical density and size. These findings indicate an inhibition of remodeling, seemingly emanating from the perilymphatic spaces, and affecting both the activation of osteoclasts and the extent of resorption by the osteoclasts. These values satisfactorily explain the preservation of such fetal remnants as the globuli ossei, the interglobular spaces, and the skein bone. In humans, local ineffective inhibition of bone resorption may play a role in the initiation of otosclerosis.