Fabric-mechanical property relationships of trabecular bone allografts are altered by supercritical CO2 treatment and gamma sterilization

Tissue grafts are implanted in orthopedic surgery every day. In order to minimize infection risk, bone allografts are often delipidated with supercritical CO2 and sterilized prior to implantation. This treatment may, however, impair the mechanical behavior of the bone graft tissue. The goal of this study was to determine clinically relevant mechanical properties of treated/sterilized human trabecular bone grafts, e.g. the apparent modulus, strength, and the ability to absorb energy during compaction. They were compared with results of identical experiments performed previously on untreated/fresh frozen human trabecular bone from the same anatomical site (Charlebois, 2008). We tested the hypothesis that the morphology–mechanical property relationships of treated cancellous allografts are similar to those of fresh untreated bone. The morphology of the allografts was determined by μCT. Subsequently, cylindrical samples were tested in unconfined and confined compression. To account for various morphologies, the experimental data was fitted to phenomenological mechanical models for elasticity, strength, and dissipated energy density based on bone volume fraction (BV/TV) and the fabric tensor determined by MIL. The treatment/sterilization process does not appear to influence bone graft stiffness. However, strength and energy dissipation of the bone grafts were found to be significantly reduced by 36% to 47% and 66% to 81%, respectively, for a broad range of volume fraction (0.14 < BV/TV < 0.39) and degree of anisotropy (1.24 < DA < 2.18). Since the latter properties are strongly dominated by BV/TV, the clinical consequences of this reduction can be compensated by using grafts with lower porosity. The data of this study suggests that an increase of 5–10% in BV/TV is sufficient to compensate for the reduced post-yield mechanical properties of treated/sterilized bone in monotonic compression. In applications where graft stiffness needs to be matched and strength is not a concern, treated allograft with the same BV/TV as an appropriate fresh bone graft may be used.

Rezension zu: Inge Govaere and Hanns Ulrich (eds.): Intellectual Property, Public Policy and International Trade

The contemporary intellectual property rights (IPR) system is not a simple, smoothly working block of rules but is complex and full of ambiguities, and as many argue, imperfections. Some deficits relate on the one hand to the inherent centrality of authorship, originality and mercantilism to the ‘Western’ IP model, which leaves numerous non-Western, collaborative or folkloric modes of production outside the scope of protection. On the other hand, some imperfections stem from the way IPR are granted, whereby creators acquire a temporary monopoly over their works and thus exclude the public from having access to them. In this sense, it is often uncertain whether the existent IPR model appropriately reflects the precarious balance between private and public interests, and whether the best incentives to promote creativity and innovation - the initially stated objectives of intellectual property protection - are offered. The matter becomes still more complicated when one considers that the IPR system is not domestically contained but is globalised and strongly affected by rules at the regional and international levels. The question of whether the balance between private interests and public values is sustained within the international legal framework, epitomised by the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) of the World Trade Organization (WTO), is precisely the topic of the book reviewed here. Review of Intellectual Property, Public Policy, and International Trade, edited by Inge Govaere and Hanns Ullrich, P.I.E. Peter Lang, 2007.

Intellectual Property and Traditional Cultural Expressions in a Digital Environment. Preface

In the face of increasing globalisation, there is a pressing need for innovative trans-disciplinary analyses of the value of traditional cultural expressions (TCE) that also suggest appropriate protection mechanisms for them. The book to which this preface belongs combines approaches from history, philosophy, anthropology, sociology and law, and charts previously untravelled paths for developing new policy tools and legal designs that go beyond conventional copyright models. It reflects also upon the specific features of the digital environment, which, despite enhancing the risks of misappropriation of traditional knowledge and creativity, may equally offer some opportunities for revitalising indigenous peoples' values and provide for the sustainability of TCE.

A Hennessy-Milner Property for Many-Valued Modal Logics

A Hennessy-Milner property, relating modal equivalence and bisimulations, is defined for many-valued modal logics that combine a local semantics based on a complete MTL-chain (a linearly ordered commutative integral residuated lattice) with crisp Kripke frames. A necessary and sufficient algebraic condition is then provided for the class of image-finite models of these logics to admit the Hennessy-Milner property. Complete characterizations are obtained in the case of many-valued modal logics based on BL-chains (divisible MTL-chains) that are finite or have universe [0,1], including crisp Lukasiewicz, Gödel, and product modal logics.

Why do individuals behave differently in commons dilemmas?: The case of alpine farmers using common property pastures in Grindelwald, Switzerland

The sustainable use of common-pool resources depends on users’ behaviour with regards to appropriation and provision. Most knowledge about behaviour in such situations comes from experimental research. As experiments take place in confined environments, motivational drivers and actions in the field might differ. This paper analyses farmers’ use of common property pastures in Grindelwald, Switzerland. Binary logistic regression is applied to survey data to explore the effect of farmers’ attributes on livestock endowment, appropriation and provision behaviour. Furthermore, Q methodology is used to assess the impact of broader contextual variables on the sustainability of common property pastures. It is shown that the strongest associations exist between (a) socio-economic attributes and change in livestock endowment; (b) norms and appropriation behaviour; and (c) area and pay-off and provision behaviour. Relevant contextual variables are the economic value of the resource units, off-farm income opportunities, and the subsidy structure. We conclude that with increasing farm size farmers reduce the use and maintenance of common property. Additionally, we postulate that readiness to maintain a resource increases with appropriation activities and the net returns generated from appropriation.