Asymptotic stability and blow up for a semilinear damped wave equation with dynamic boundary conditions

In this paper we consider a multi-dimensional wave equation with dynamic boundary conditions, related to the Kelvin-Voigt damping. Global existence and asymptotic stability of solutions starting in a stable set are proved. Blow up for solutions of the problem with linear dynamic boundary conditions with initial data in the unstable set is also obtained

The axillary approach to raising the latissimus dorsi free flap for facial re-animation: a descriptive surgical technique

The latissimus dorsi flap is popular due to the versatile nature of its applications. When used as a pedicled flap it provides a robust solution when soft tissue coverage is required following breast, thoracic and head and neck surgery. Its utilization as a free flap is extensive due to the muscle's size, constant anatomy, large caliber of the pedicle and the fact it can be used for functional muscle transfers. In facial palsy it provides the surgeon with a long neurovascular pedicle that is invaluable in situations where commonly used facial vessels are not available, in congenital cases or where previous free functional muscle transfers have been attempted, or patients where a one-stage procedure is indicated and a long nerve is required to reach the contra-lateral side. Although some facial palsy surgeons use the trans-axillary approach, an operative guide of raising the flap by this method has not been provided. A clear guide of raising the flap with the patient in the supine position is described in detail and offers the benefits of reducing the risk of potential brachial plexus injury and allows two surgical teams to work synchronously to reduce operative time

A global attractor for a fluid--plate interaction model accounting only for longitudinal deformations of the plate

We study asymptotic dynamics of a coupled system consisting of linearized 3D Navier--Stokes equations in a bounded domain and the classical (nonlinear) elastic plate equation for in-plane motions on a flexible flat part of the boundary. The main peculiarity of the model is the assumption that the transversal displacements of the plate are negligible relative to in-plane displacements. This kind of models arises in the study of blood flows in large arteries. Our main result states the existence of a compact global attractor of finite dimension. We also show that the corresponding linearized system generates exponentially stable $C_0$-semigroup. We do not assume any kind of mechanical damping in the plate component. Thus our results means that dissipation of the energy in the fluid due to viscosity is sufficient to stabilize the system.Comment: 18 page

The measurement of primary productivity in a high-rate oxidation pond (HROP)

A high-rate oxidation pond is studied as a model system for comparing 14C and oxygen evolution methods as tools for measuring primary productivity in hypertrophic aquatic systems. Our results indicate that at very dense algal populations (up to 5 mg chl. a l−1) and high photosynthetic rates, 14C based results may severely underestimate primary productivity, unless a way is found to keep incubation times very short. Results obtained with our oxygen electrode were almost an order of magnitude higher than those obtained by all 14C procedures. These higher values correspond fairly well with a field-tested computer-simulation model, as well as with direct harvest data obtained at the same pond when operated under similar conditions. The examination of the size-fractionation of the photosynthetic activity underscored the important contribution of nannoplanktonic algae to the total production of the syste

Photosynthetic characteristics of five high light and low light exposed microalgaea as measured with 14C-uptake and oxygen electrode techniques

#Tetraselmis suecica, #Thalassiosira pseudonana, #Chaetoceros calcitrans, #Isochrysis galbana et #Microcystis sp.$ ont été utilisées pour déterminer leurs capacités d'adaptation et pour tester les différences entre les deux méthodes de mesure. Les cultures avaient été exposées à un éclairement fort (HL) ou à un éclairement faible (LL) pendant deux jours avant l'expérience. L'efficacité de la conversion de la lumière (...) et l'activité photosynthétique spécifique maximale par unité de chlorophylle (...) ont été généralement plus élevées pour les cultures LL. Les divers paramètres photosynthétiques mesurés par la méthode de l'électrode à oxygène ont été différents de ceux obtenus par celle du 14C. Les importantes différences de quotient photosynthétique (O2/CO2), observées aussi bien entre cultures HL et LL d'une même espèce qu'entre espèces différentes, soulignent la difficulté de convertir les productions d'oxygène en assimilation de carbone. (D'après résumé d'auteur

Risk factors associated with Rift Valley fever epidemics in South Africa in 2008–11

Rift Valley fever (RVF) is a zoonotic and vector-borne disease, mainly present in Africa, which represents a threat to human health, animal health and production. South Africa has experienced three major RVF epidemics (1950–51, 1973–75 and 2008–11). Due to data scarcity, no previous study has quantified risk factors associated with RVF epidemics in animals in South Africa. Using the 2008–11 epidemic datasets, a retrospective longitudinal study was conducted to identify and quantify spatial and temporal environmental factors associated with RVF incidence. Cox regressions with a Besag model to account for the spatial effects were fitted to the data. Coefficients were estimated by Bayesian inference using integrated nested Laplace approximation. An increase in vegetation density was the most important risk factor until 2010. In 2010, increased temperature was the major risk factor. In 2011, after the large 2010 epidemic wave, these associations were reversed, potentially confounded by immunity in animals, probably resulting from earlier infection and vaccination. Both vegetation density and temperature should be considered together in the development of risk management strategies. However, the crucial need for improved access to data on population at risk, animal movements and vaccine use is highlighted to improve model predictions

Digital dissection of the model organism Xenopus laevis using contrast-enhanced computed tomography

The African clawed frog, Xenopus laevis, is one of the most widely used model organisms in biological research. However, the most recent anatomical description of X. laevis was produced nearly a century ago. Compared with other anurans, pipid frogs – including X. laevis – exhibit numerous unusual morphological features; thus, anatomical descriptions of more ‘typical’ frogs do not detail many aspects of X. laevis skeletal and soft‐tissue morphology. The relatively new method of using iodine‐based agents to stain soft tissues prior to high‐resolution X‐ray imaging has several advantages over gross dissection, such as enabling dissection of very small and fragile specimens, and preserving the three‐dimensional topology of anatomical structures. Here, we use contrast‐enhanced computed tomography to produce a high‐resolution three‐dimensional digital dissection of a post‐metamorphic X. laevis to successfully visualize: skeletal and muscular anatomy; the nervous, respiratory, digestive, excretory and reproductive systems; and the major sense organs. Our digital dissection updates and supplements previous anatomical descriptions of this key model organism, and we present the three‐dimensional data as interactive portable document format (PDF) files that are easily accessible and freely available for research and educational purposes. The data presented here hold enormous potential for applications beyond descriptive purposes, particularly for biological researchers using this taxon as a model organism, comparative anatomy and biomechanical modelling

Stereo facial image matching to aid in Fetal Alcohol Syndrome screening

Includes abstract. Includes bibliographical references