Tendons have uniquely high tensile strength, critical to their function to transfer force from muscle to bone. When injured, their innate healing response results in aberrant matrix organization and functional properties. Efforts to regenerate tendon are challenged by limited understanding of its normal development. Consequently, there are few known markers to assess tendon formation and parameters to design tissue engineering scaffolds. We profiled mechanical and biological properties of embryonic tendon and demonstrated functional properties of developing tendon are not wholly reflected by protein expression and tissue morphology. Using force volume-atomic force microscopy, we found that nano-and microscale tendon elastic moduli increase nonlinearly and become increasingly spatially heterogeneous during embryonic development. When we analyzed potential biochemical contributors to modulus, we found statistically significant but weak correlation between elastic modulus and collagen content, and no correlation with DNA or glycosaminoglycan content, indicating there are additional contributors to mechanical properties. To investigate collagen cross-linking as a potential contributor, we inhibited lysyl oxidasemediated collagen cross-linking, which significantly reduced tendon elastic modulus without affecting collagen morphology or DNA, glycosaminoglycan, and collagen content. This suggests that lysyl oxidase-mediated cross-linking plays a significant role in the development of embryonic tendon functional properties and demonstrates that changes in cross-links alter mechanical properties without affecting matrix content and organization. Taken together, these data demonstrate the importance of functional markers to assess tendon development and provide a profile of tenogenic mechanical properties that may be implemented in tissue engineering scaffold design to mechanoregulate new tendon regeneration.musculoskeletal | second harmonic generation T endon is a principal tissue involved in movement, functioning primarily to transfer loads from muscle to bone. Acute and chronic tendon injuries are significant clinical problems due to poor innate healing ability and drawbacks associated with surgical repair (1, 2). In 2006, musculoskeletal symptoms were the second most frequent reason for physician visits in the United States, resulting in over 130 million visits at a cost of nearly $850 billion (3). Almost half of these visits involved tendons and ligaments, with incidence expected to rise with an aging population. Thus, efforts have focused on engineering new tissues for replacement, although this has been challenged by a paucity of markers with which to assess functional tendon development and few known cues to direct differentiation and new tissue formation.Characterization of tendon formation in embryonic or engineered tissue has typically relied on molecular markers, as well as matrix composition and organization (4-9). Although useful for assessing cell differentiation and ECM deposition during tissue formation, t...

Systems that can be reconfigured are valuable in situations where a single artifact must perform several different functions well, and are especially important in cases where system demands are not known a priori. Design of reconfigurable systems present unique challenges compared to fixed system design. Increasing reconfigurable capability improves system utility, but also increases system complexity and cost. In this article a new design strategy is presented for the design of reconfigurable systems for multiability. This study is limited to systems where all system functions are known a priori, and only continuous means of reconfiguration are considered. Designing such a system requires determination of (1) what system features should be reconfigurable, and (2) what should the range of reconfigurability of these features be. The new design strategy is illustrated using a reconfigurable delta robot, which is a parallel manipulator that can be adapted to perform a variety of manufacturing operations. In this case study the tradeoff between end effector stiffness and speed is considered over two separate manipulation tasks.