Experimental study of the installation acetabular component with uncoverage in arthroplasty patients with severe developmental hip dysplasia.

PURPOSE: The purpose of this study was stimation of optimal percentage of lateral uncoverage of the acetabular component during total hip arthroplasty for patients with severe developmental hip dysplasia. METHODS: Mathematical computer modeling based on the finite element technique and the mechanical experiment were performed. Critical values of uncoverage enabling safe primary fixation of acetabular component were estimated in designed models. RESULTS: Using the finite element technique and the mechanical experiment on pelvis models, a possibility of mounting an acetabular component with moderate uncoverage within 25% without screws and with significant uncoverage to 35% with an additional two-screw fixation was demonstrated. CONCLUSIONS: This study provides additional guidance on optimal acetabular uncoverage assessment and fixation methods of surgeons performing THA on patients with DDH.

Entanglement of Steller sea lions (Eumetopias jubatus) in man-made marine debris on Tyuleniy Island, Sea of Okhotsk.

The present report provides data on entanglement of Steller sea lions (SSL) in marine debris on Tyuleniy Island, Sea of Okhotsk. The frequency of entanglement depending on the material, sex, and age of animals was estimated. A total of 133 SSL were recorded as having debris on their bodies, or an average of 22.2 individuals per year. The relative rate of entanglement over the observation years ranged from 1.48 to 1.97% of their total number. The entangled individuals were both males and females of all ages, but young males constituted the largest proportion among them (5.2%). The entangled SSL most frequently (43.2%) had neck collars (the material is not defined) and, less frequently, packaging bands (23.4%), nets (17.7%), and other debris. Most of marine litter found on SSL is associated with commercial fishing activities. On Tyuleniy Island, the rate of SSL entanglement is higher than in the eastern part of the species' range.

Asymptotic splitting in the three-dimensional problem of elasticity for non-homogeneous piezoelectric plates.

A novel asymptotic approach to the theory of non-homogeneous anisotropic plates is suggested. For the problem of linear static deformations we consider solutions, which are slowly varying in the plane of the plate in comparison to the thickness direction. A small parameter is introduced in the general equations of the theory of elasticity. According to the procedure of asymptotic splitting, the principal terms of the series expansion of the solution are determined from the conditions of solvability for the minor terms. Three-dimensional conditions of compatibility make the analysis more efficient and straightforward. We obtain the system of equations of classical Kirchhoff's plate theory, including the balance equations, compatibility conditions, elastic relations and kinematic relations between the displacements and strain measures. Subsequent analysis of the edge layer near the contour of the plate is required in order to satisfy the remaining boundary conditions of the three-dimensional problem. Matching of the asymptotic expansions of the solution in the edge layer and inside the domain provides four classical plate boundary conditions. Additional effects, like electromechanical coupling for piezoelectric plates, can easily be incorporated into the model due to the modular structure of the analysis. The results of the paper constitute a sound basis to the equations of the theory of classical plates with piezoelectric effects, and provide a trustworthy algorithm for computation of the stressed state in the three-dimensional problem. Numerical and analytical studies of a sample electromechanical problem demonstrate the asymptotic nature of the present theory.

ReVisE: Remote visualization environment for large numerical simulation datasets.

The paper presents a new open-source visualization system, named ReVisE, aimed to provide interactive visualization of large datasets, which are results of complex numerical simulations. These datasets are hosted on a remote server or a supercomputer. The design of the system is briefly described. Dataset representation, proposed for interactive visualization and implemented in the system, is discussed. The effectiveness of our approach is confirmed by results of performance measurements on test and real-life large datasets. A comparison with other visualization systems is presented. Future plans of system development are outlined.

Entanglement of northern fur seals (Callorhinus ursinus) in marine debris on Tyuleniy Island (Sea of Okhotsk) in 1998-2013.

The systematic annual observations of the northern fur seal rookery on Tyuleniy (= Robben) Island, Sea of Okhotsk, were started in 1958. Since 1975, all seals entangled in marine debris have been registered. Some of the data on this issue, collected on the island in the late 20th century, were published earlier. This report provides data for the period of completion of the commercial sealing (from 1998 to 2013). During this period, a total of 867 fur seals were observed entangled in marine debris, including 212 bulls, 97 half-bulls, 223 bachelors, and 335 females. The estimated mean annual number of entangled fur seals in 1998-2013 is 1113 individuals. Marine debris was found mainly on the neck and, less frequently, on the head and front flippers of the animals. This included pieces of fishing nets, packaging bands, ropes, fishing lines, and other items of anthropogenic origin.