Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations

This study presents a historical review, a meta-analysis, and recommendations for users about weight–length relationships, condition factors and relative weight equations. The historical review traces the developments of the respective concepts. The meta-analysis explores 3929 weight–length relationships of the type W = aLb for 1773 species of fishes. It shows that 82% of the variance in a plot of log a over b can be explained by allometric versus isometric growth patterns and by different body shapes of the respective species. Across species median b = 3.03 is significantly larger than 3.0, thus indicating a tendency towards slightly positive-allometric growth (increase in relative body thickness or plumpness) in most fishes. The expected range of 2.5 < b < 3.5 is confirmed. Mean estimates of b outside this range are often based on only one or two weight–length relationships per species. However, true cases of strong allometric growth do exist and three examples are given. Within species, a plot of log a vs b can be used to detect outliers in weight–length relationships. An equation to calculate mean condition factors from weight–length relationships is given as Kmean = 100aLb−3. Relative weight Wrm = 100W/(amLbm) can be used for comparing the condition of individuals across populations, where am is the geometric mean of a and bm is the mean of b across all available weight–length relationships for a given species. Twelve recommendations for proper use and presentation of weight–length relationships, condition factors and relative weight are given

The Impact of Metal Ion Exposure on the Cellular Behavior of Human Osteoblasts and PBMCs: In Vitro Analyses of Osteolytic Processes

Osteolysis in the periprosthetic tissue can be caused by metallic wear particles and ions that can originate from implant surface corrosion. These products influence cellular behavior and stimulate the expression of proinflammatory cytokines. The purpose of this study was to evaluate the impact of CoCr29Mo6 ions on cell survival, differentiation, and cytokine expression in human osteoblasts and peripheral blood mononuclear cells (PBMCs). Thus, we exposed cells with a mixture of 200 mu g/L ion solution and determined cell viability and apoptosis/necrosis. Gene expression analyses of osteoblastic and osteoclastic differentiation markers as well as pro-osteolytic mediators (IL-6, IL-8, TNF-alpha, MCP-1, MMP1, TIMP1) were performed. These markers were also investigated in mixed cultures of adherent and non-adherent PBMCs as well as in co-cultures of human osteoblasts and PBMCs. The ion solution induced necrosis in osteoblasts and PBMCs in single cultures. All examined mediators were highly expressed in the co-culture of osteoblasts and PBMCs whereas in the single cell cultures only IL-6, IL-8, and MMP1 were found to be stimulated. While the applied concentration of the CoCr29Mo6 ion solutions had only marginal effects on human osteoblasts and PBMCs alone, the co-culture may provide a comprehensive model to study osteolytic processes in response to Co and Cr ions

Improvement of mechanical and water absorption properties of plant protein based bioplastics

Bioplastics deriving from plant proteins are becoming an increasingly popular source of raw material for plastic products since they are not only biodegradable but renewable resources. However, these bioplastics require improved mechanical and water absorption properties to be suitable for many applications, such as packaging. For this reason, this study considers potato and rice proteins as a new source for the manufacture of bioplastics. The proteins were mixed with different glycerol concentrations followed by thermomoulding at temperatures from 60 to 180 degrees C. The resulting bioplastic is characterized in terms of thermo-mechanical properties, water absorption and molecular weight distribution. Compared to well-known wheat gluten, these bioplastics required higher temperatures for their thermomoulding. However, both of them were more structured materials and exhibited less water absorption (e.g. as low as 9 wt.%) than those obtained for wheat gluten blend. Potato protein-based bioplastics showed complex modulus values comparable to synthetic polymers such as Low Density Polyethylene (LDPE)

GPU parallelization of a three dimensional marine CSEM code

One of the main problem of 3D time domain controlled source electromagnetic (CSEM) inversion is the high runtimes of forward modeling codes. We reduced the runtime of the 3D time domain finite difference CSEM code TEMDDD by the GPU-parallelization of expensive algorithms. The code solves the electromagnetic diffusion equation by discretization of spatial operators and subsequent calculation of eigenpairs. These eigenpairs are found by approximation of the eigenspace in a Kiylov subspace using the spectral Lanczos decomposition Method. This algorithm was in its original form not parallelizable due to implementation of the upper boundary condition at the air-water interface. We show for the marine case that replacing the original boundary condition at the air-water surface by a discretized air layer allows GPU parallelization of every time consuming algorithm of the code in the marine case. Speedups between 20 and 60 have been achieved compared to the original code for a larger 3-D model. In this model the bathymetry from a survey area offshore Egypt is used as an example demonstrating that the parallelized version of the code is applicable to real survey scenarios