No abstract

The response of meniscal tissue to axial, radial and circumferential compressive forces was measured at physiologically relevant levels of load in eight pairs of human knee joint menisci. Compression was unconfined and uniaxial. Stress strain data were fitted to a two-parameter exponential model. The tissue was found to be significantly stiffer to axial compressive forces than to radial and circumferential forces. No significant difference was found between the responses to circumferential and radial forces.

Para-virtualization ties a guest operating system and a hypervisor together, which restricts the system architecture; e.g., when Linux uses the Xen API, Linux is unable to run on alternative hypervisors such as VMware, Linux itself, or a security kernel such as EROS. Furthermore, the lock-in obstructs evolution of its own paravirtualization interface -virtual machines provide the vital ability to run obsoleted operating systems alongside new operating systems, but para-virtualization often lacks this feature, requiring all concurrent instances to be the hypervisor's supported version. Even general purpose operating systems have weaker restrictions for their applications. This lock-in discards the modularity of virtualization; modularity is an intrinsic feature of traditional virtualization, helping to add layered enhancements to operating systems, especially when enhanced by people outside the operating system's development community (e.g., Linux server consolidation provided by VMware).Virtualization and its modularity solve many systems problems; combined with the performance of paravirtualization it becomes even more compelling. We show how to achieve both together. We offer a set of design principles, which we call soft layering, that govern the modifications made to the operating system. Additionally, our approach is highly automated, thus reducing the implementation and maintenance burden of paravirtualization, which is especially useful for enabling obsoleted operating systems. We demonstrate soft layering on x86 and Itanium: we can load a single Linux binary on a variety of hypervisors (and thus substitute virtual machine environments and their enhancements), while achieving essentially the same performance as para-virtualization with less effort.

The proportions of medial and lateral knee joint menisci represented by radially orientated collagen (COL) were measured in 42 specimens from 24 hospital patients examined post-mortem. Images of the fibre bundles were obtained by the 488-nm laser confocal scanning of hydrated, fixed radial blocks taken from the anterior, middle and posterior regions of the menisci after staining with picro-Sirius red. Measurements of the percentage of each image occupied by fluorescent, doubly refractile COL were made by means of a Kontron IBAS image analyser, after interactive segmentation. In areas adjoining the outer, lateral parts of both the medial and lateral menisci, the proportion of all samples identified as radial COL was 7.56 ± 0.28%. The corresponding figure for areas near the inner, medial edges of the menisci was 17.80 ± 0.80%. However, no relationship was demonstrable between age and sex and meniscal radial fibre optical density, and there was no difference between the proportion of radial fibres in the anterior, middle or posterior regions.