Implementing Reliability: The Interaction of Requirements, Tactics and Architecture Patterns

An important way that the reliability of a software system is enhanced is through the implementation of specific run-time measures called runtime tactics. Because reliability is a system-wide property, tactic implementations affect the software structure and behavior at the system, or architectural level. For a given architecture, different tactics may be a better or worse fit for the architecture, depending on the requirements and how the architecture patterns used must change to accommodate the tactic: different tactics may be a better or worse fit for the architecture. We found three important factors that influence the implementation of reliability tactics. One is the nature of the tactic, which indicates whether the tactic influences all components of the architecture or just a subset of them. The second is the interaction between architecture patterns and tactics: specific tactics and patterns are inherently compatible or incompatible. The third is the reliability requirements which influence which tactics to use and where they should be implemented. Together, these factors affect how, where, and the difficulty of implementing reliability tactics. This information can be used by architects and developers to help make decisions about which patterns and tactics to use, and can also assist these users in learning what modifications and additions to the patterns are needed.</p

Treatment of Canine Osseous Tumors with Photodynamic Therapy: A Pilot Study

Photodynamic therapy uses nonthermal coherent light delivered via fiber optic cable to locally activate a photosensitive chemotherapeutic agent that ablates tumor tissue. Owing to the limitations of light penetration, it is unknown whether photodynamic therapy can treat large osseous tumors. We determined whether photodynamic therapy can induce necrosis in large osseous tumors, and if so, to quantify the volume of treated tissue. In a pilot study we treated seven dogs with spontaneous osteosarcomas of the distal radius. Tumors were imaged with MRI before and 48 hours after treatment, and the volumes of hypointense regions were compared. The treated limbs were amputated immediately after imaging at 48 hours and sectioned corresponding to the MR axial images. We identified tumor necrosis histologically; the regions of necrosis corresponded anatomically to hypointense tissue on MRI. The mean volume of necrotic tissue seen on MRI after photodynamic therapy was 21,305 mm3 compared with a pretreatment volume of 6108 mm3. These pilot data suggest photodynamic therapy penetrates relatively large canine osseous tumors and may be a useful adjunct for treatment of bone tumors

Flow-to-fracture transition and pattern formation in a discontinuous shear thickening fluid

Recent theoretical and experimental work suggests a frictionless-frictional transition with increasing inter-particle pressure explains the extreme solid-like response of discontinuous shear thickening suspensions. However, analysis of macroscopic discontinuous shear thickening flow in geometries other than the standard rheometry tools remain scarce. Here we use a Hele-Shaw cell geometry to visualise gas-driven invasion patterns in discontinuous shear thickening cornstarch suspensions. We plot quantitative results from pattern analysis in a volume fraction-pressure phase diagram and explain them in context of rheological measurements. We observe three distinct pattern morphologies: viscous fingering, dendritic fracturing, and system-wide fracturing, which correspond to the same packing fraction ranges as weak shear thickening, discontinuous shear thickening, and shear-jammed regimes