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- SourceAvailable from: Jeremy L Wyatt[Show abstract] [Hide abstract]
ABSTRACT: We are investigating the problem of predicting how objects behave under manipulative actions. In particular, we wish to predict the workpiece motions which will result from simple pushing manipulations by a single robotic fingertip. Such interactions are themselves fundamental components of multi-fingered grasping and other complex interactions. Physics simulators can be used to do this, but they model many kinds of object interactions poorly, being dependent on detailed scene descriptions and parameters, which in practice are often difficult to tune. Additionally, we have previously investigated ways of learning to predict, by employing density estimation techniques to learn, from many example pushes, a probabilistic mapping between applied pushing motions and resulting work-piece motions. In contrast, this paper presents an alternative approach to prediction, which does not rely on learning but infers the likelihood of possible workpiece motions by using the simple physics principle of minimum energy. This approach is advantageous in situations where insufficient prior knowledge is available for training our learned predictors. In such situations, possible strategies include either training learned predictors on unrealistic simulation data, or making use of the simple physics approach which requires no training. We show that the second of these strategies performs significantly better, and approaches the performance of learned predictors are trained on observations of real object motions.
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ABSTRACT: This paper describes the potential for optimising a resonant gas sensor by using nano-textured surfaces. Initial empirical calculations determined that a device with a nano-textured active layer could have its surface area increased by an order of magnitude when compared to a device with an ideal theoretical smooth surface. These nano-textured surfaces are achieved when using the author's one step DRIE process. By carefully choosing the parameters when using the one step process the underside can be made to mimic porous silicon giving the user this vastly increased surface area on a micro and nano scale. After explaining how these surfaces are obtained this paper goes on to detail modelling work carried out to demonstrate the possible effects this new textured surface could have on the performance of future resonant gas sensors. A simple generic resonator is modelled with and without the new surface to give a clear indication of the improvement in signal performance that can be expected from future devices utilizing this new pseudo porous silicon as its active layer.Nanotec; 04/2015
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ABSTRACT: Tendon is a dynamic tissue whose structure and function is influenced by mechanical loading, but little is known about the fundamental mechanisms that regulate tendon growth and remodeling in vivo. Data from cultured tendon fibroblasts indicated that the p38 MAPK pathway plays an important role in tendon fibroblast proliferation and collagen synthesis in vitro. To gain greater insight into the mechanisms of tendon growth, and explore the role of p38 MAPK signaling in this process, we tested the hypotheses that inducing plantaris tendon growth through the ablation of the synergist Achilles tendon would result in rapid expansion of a neotendon matrix surrounding the original tendon, and that treatment with the p38 MAPK inhibitor SB203580 would prevent this growth. Rats were treated with vehicle or SB203580, and subjected to synergist ablation by bilateral tenectomy of the Achilles tendon. Changes in histological and biochemical properties of plantaris tendons were analyzed 3, 7, or 28 days after overload, and comparisons were made to non-overloaded animals. By 28 days after overload, tendon mass had increased by 30% compared to non-overloaded samples, and cross-sectional area (CSA) increased by around 50%, with most of the change occurring in the neotendon. The expansion in CSA initially occurred through the synthesis of a hyaluronic acid rich matrix that was progressively replaced with mature collagen. Pericytes were present in areas of active tendon growth, but never in the original tendon ECM. Inhibition of p38 MAPK resulted in a profound decrease in IL6 expression, and had a modest effect on the expression of other ECM and cell proliferation genes, but had a negligible impact on overall tendon growth. The combined results from this study provided novel insights into tendon mechanobiology, and suggest that p38 MAPK signaling does not appear to be necessary for tendon growth in vivo.PLoS ONE 03/2015; 10(3):e0120044. DOI:10.1371/journal.pone.0120044
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