Grasping soft, irregular material is challenging both for animals and robots. The feeding systems of many animals have adapted to this challenge. In particular, the feeding system of the marine mollusk Aplysia californica, a generalist herbivore, allows it to grasp and ingest seaweeds of varying shape, texture and toughness. On the surface of the grasper of A. californica is a structure known as the radula, a thin flexible cartilaginous sheet with fine teeth. Previous in vitro studies suggested that intrinsic muscles, I7, are responsible for opening the radula. Lesioning I7 in vivo does not prevent animals from grasping and ingesting food. New in vitro studies demonstrate that a set of fine muscle fibers on the ventral surface of the radula – the sub-radular fibers (SRFs) – mediate opening movements even if the I7 muscles are absent. Both in vitro and in vivo lesions demonstrate that removing the SRFs leads to profound deficits in radular opening, and significantly reduces feeding efficiency. A theoretical biomechanical analysis of the actions of the SRFs suggests that they induce the radular surface to open around a central crease in the radular surface and to arch the radular surface, allowing it to softly conform to irregular material. A three-dimensional model of the radular surface, based on in vivo observations and magnetic resonance imaging of intact animals, provides support for the biomechanical analysis. These results suggest how a soft grasper can work during feeding, and suggest novel designs for artificial soft graspers.

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Background and Hypothesis: The impact of chronic liver diseases on patients and their family member is often understated and understudied. Chronic liver diseases can sometimes progress to a need for Liver transplant (LT). While recent studies have described quality of life (QOL) at different stages of liver disease, the impact of the patient’s QOL in LT survivors has not been examined. The importance of studying QOL in patients is due to its effect on the survivorship of LT recipients. We hypothesize that QOL in LT patients is lower than the general population. Our aim was to describe predictors of QOL in a well-described cohort of LT patients. Methods: Patients were enrolled at the Digestive and Liver Disease Liver clinic at Indiana University Hospital. All patients over the age of 18 were approached, if patients consented to the study, they were then enrolled during their liver follow up visit. The PROMIS survey was administered on an iPad and completed during the clinic visit. Survey were then scored and analyzed. Results: The T-scores for post liver transplant patients are lower in physical function, anxiety and depression, but higher in general life satisfaction compared to the general population. LT recipients have similar T-scores in Fatigue, Sleep disturbance, ability to participate in social activities, and pain interference compared to the general population. Conclusion and Potential Impact: Previous diagnosis of PBC, HCC, diagnosis of depression, household income, insurance status, Charlson Comorbid Index and number of non-transplant related medications have the highest association with quality of life. Further enrollment is needed to increase the power of the study. However, this can inform physicians the importance to taking these factors in to consideration in order to improve the QOL in LT recipients.

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