Parameter reference immutability: formal definition, inference tool, and comparison

Knowing which method parameters may be mutated during a method’s execution is useful for many software engineering tasks. A parameter reference is immutable if it cannot be used to modify the state of its referent object during the method’s execution. We formally define this notion, in a core object-oriented language. Having the formal definition enables determining correctness and accuracy of tools approximating this definition and unbiased comparison of analyses and tools that approximate similar definitions. We present Pidasa, a tool for classifying parameter reference immutability. Pidasa combines several lightweight, scalable analyses in stages, with each stage refining the overall result. The resulting analysis is scalable and combines the strengths of its component analyses. As one of the component analyses, we present a novel dynamic mutability analysis and show how its results can be improved by random input generation. Experimental results on programs of up to 185 kLOC show that, compared to previous approaches, Pidasa increases both run-time performance and overall accuracy of immutability inference.     

The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report

Alveolar ridge preservation following tooth extraction is important when implant-supported oral rehabilitation is considered. The ability to maintain the ridge allows implant placement in an ideal position, fulfilling both functional and esthetic demands. A deproteinized bovine bone mineral (DBBM) was used as a socket site filler material to maintain ridge configuration, without applying an occlusive membrane. The material was grafted and packed onto the socket sites immediately after extractions, and subsequently primary soft tissue closure was attempted. The ridge healed for 9 months before the second surgical procedure, in which the implant was placed. New bone formation was observed in all histological specimens. DBBM particles adhered to a highly osteocyte-rich woven and lamellar-type bone. Clinically and histologically, this report demonstrated DBBM particles to be an effective biocompatible filler agent in extraction sockets for ridge preservation prior to titanium fixture implantation. Randomized controlled clinical trials are needed to fully evaluate the usefulness of this material in ridge preservation after tooth extraction.     

In vivo and in vitro tracking of erosion in biodegradable materials using non-invasive fluorescence imaging

The design of erodible biomaterials relies on the ability to program the in vivo retention time, which necessitates real-time monitoring of erosion. However, in vivo performance cannot always be predicted by traditional determination of in vitro erosion, and standard methods sacrifice samples or animals, preventing sequential measures of the same specimen. We harnessed non-invasive fluorescence imaging to sequentially follow in vivo material-mass loss to model the degradation of materials hydrolytically (PEG:dextran hydrogel) and enzymatically (collagen). Hydrogel erosion rates in vivo and in vitro correlated, enabling the prediction of in vivo erosion of new material formulations from in vitro data. Collagen in vivo erosion was used to infer physiologic in vitro conditions that mimic erosive in vivo environments. This approach enables rapid in vitro screening of materials, and can be extended to simultaneously determine drug release and material erosion from a drug-eluting scaffold, or cell viability and material fate in tissue-engineering formulations.     

Aldehyde?Amine Chemistry Enables Tissue Adhesive Materials to Respond to Physiologic Variation and Pathologic States

Biomaterials science represents the next frontier in medical therapeutics. Innovations in materials design and formulation have helped create previously unimaginable interventions and composite devices with materials whose structure and function evolve with time. Yet, materials development has outstripped our ability to explain why, when, and how these materials work. Current characterization means are limited, especially for dynamic erodible materials that are specifically designed to fade away. This complexity and dynamism of emerging materials and the impact they have on tissue make it challenging to understand and predict material interactions with local tissues. Because tissue biomaterials interactions are determined not only by the innate properties of the materials, but also by the local microenvironment at the implantation site, we must now examine the impact of target tissue site, state, and incidence of a disease on material performance, efficacy, and biocompatibility. This issue becomes increasingly important when considering surface interacting materials, whose intimate interactions with tissues are dictated by local mechanical forces, tissue target site, and the modulation of tissue surface properties manifested by specific disease types and states. The mechanisms involved and the extent to which these parameters affect the in vivo performance of materials are mostly unknown. These open questions motivated us to explore the determinant factors that affect the efficacy of materials, using adhesive materials whose surface interactions with tissues make them an ideal material class for the assessment of tissue material interactions. As an example of this paradigm, we determined how tissue amines served as a natural binding site for material aldehydes, enabling tissue-specific binding that varied with natural changes in amine density from tissue to tissue and the physiologic environment, as well as with disease. The introduction of amines within the material also provides greater control over binding and material cohesion. This general mode will provide new tissue adhesives that can sense local tissue states and provide mechanical interactions titrated to context and need to enhance the desired effect and minimize local toxicity.