An HDG Method for Dirichlet Boundary Control of Convection Dominated Diffusion PDE

We first propose a hybridizable discontinuous Galerkin (HDG) method to approximate the solution of a \emph{convection dominated} Dirichlet boundary control problem. Dirichlet boundary control problems and convection dominated problems are each very challenging numerically due to solutions with low regularity and sharp layers, respectively. Although there are some numerical analysis works in the literature on \emph{diffusion dominated} convection diffusion Dirichlet boundary control problems, we are not aware of any existing numerical analysis works for convection dominated boundary control problems. Moreover, the existing numerical analysis techniques for convection dominated PDEs are not directly applicable for the Dirichlet boundary control problem because of the low regularity solutions. In this work, we obtain an optimal a priori error estimate for the control under some conditions on the domain and the desired state. We also present some numerical experiments to illustrate the performance of the HDG method for convection dominated Dirichlet boundary control problems

International lower limb collaborative (INTELLECT) study: a multicentre, international retrospective audit of lower extremity open fractures

Trauma remains a major cause of mortality and disability across the world1, with a higher burden in developing nations2. Open lower extremity injuries are devastating events from a physical3, mental health4, and socioeconomic5 standpoint. The potential sequelae, including risk of chronic infection and amputation, can lead to delayed recovery and major disability6. This international study aimed to describe global disparities, timely intervention, guideline-directed care, and economic aspects of open lower limb injuries

Die palmare radioscapholunäre Arthrodese als Rettungsoperation bei fehlverheilten intraartikulären Speichenfrakturen

Jan DeKoning's Dodgem - DG16 - photographed 16 September 2007

Treatment of Proximal Phalangeal Fractures by Plate and Angular Stable Unicortical Screws

Objective/Hypothesis: Fractures of the proximal phalanges are the most common phalangeal fractures. The current state-of-the-art treatment is open reduction and internal fixation with a dorsal plate. Immobilization is not required. Immediate digital motion is possible, thus preventing peritendinous adhesions as well as arthrofibrosis. Bicortical plate fixation is a commonly used procedure. However, it is known to cause irritation of flexor tendons and consequent limitation of motion. The difference between unicortical and bicortical screws has been addressed in a small number of studies. In metacarpal bones, Dona et al. found no difference between unicortical and bicortical locking screws in terms of load failure and stiffness. They also observed no screw pullout. In a biomechanical study, Khalid et al. investigated the pullout force of unicortical and bicortical screws in proximal phalanges and found that unicortical screws have significantly higher pullout strength in the mid diaphysis, but less in the proximal and distal metaphysis. However, they only used screws without a locking plate system. The principal aim of the present study was to investigate the outcome after proximal phalangeal fractures treated by open reduction and dorsal stable fixation with angular stable locking screws. Material and Methods: All proximal phalangeal fractures from 2011 to 2012, treated by open reduction and internal fixation with plate and unicortical angular stable locking screws, were analyzed retrospectively. Data concerning age, sex, follow-up interval, range of motion (ROM) of the metacarpophalangeal (MCP), the proximal interphalangeal (PIP), and the distal interphalangeal (DIP) joint were collected for statistical analysis. To assess functional outcome, the Buck-Gramcko score was calculated for the range of motion. The last x-ray examination was analyzed in respect to screw or plate loosening. Fractures were assigned to the following categories: open, closed, transverse, oblique, comminuted, intra-articular, or extra-articular. Results: In all, 15 proximal phalangeal fractures were analyzed retrospectively. Union was achieved in all cases. Eleven patients (73%) were men and 4 (27%) were women. Their mean age was 35 ± 11 years and the mean duration of follow-up was 7 ± 5 months. Triple-joint fingers were involved in 80% and the thumb in 20%. The mean ROM of triple-joint fingers in MCP was 92° ± 10°, PIP 76° ± 20°, and DIP 72° ± 20°. For the thumb, the average ROM of the MCP was 67° ± 15° and the IP 53° ± 15°. The mean Buck-Gramcko score was 14 ± 1, which indicates an excellent outcome. No complication related to the osteosynthesis equipment was observed. Conclusion: Dorsal plating with unicortical angular stable screws is suitable for proximal phalangeal fractures. It is associated with a low complications rate and excellent clinical outcome. </jats:p