22 research outputs found
Robot Learning with Task-Parameterized Generative Models
Task-parameterized models provide a representation of movement/behavior that can adapt to a set of task parameters describing the current situation encountered by the robot, such as location of objects or landmarks in its workspace. This paper gives an overview of the task-parameterized Gaussian mixture model (TP-GMM) introduced in previous publications, and introduces a number of extensions and ongoing challenges required to move the approach toward unconstrained environments. In particular, it discusses its generalization capability and the handling of movements with a high number of degrees of freedom. It then shows that the method is not restricted to movements in task space, but that it can also be exploited to handle constraints in joint space, including priority constraints
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Development and Characterization of a Porcine Mitral Valve Scaffold for Tissue Engineering
This paper is in closed access.Decellularized scaffolds represent a promising alternative for mitral valve (MV) replacement. This work developed and characterized a protocol for the decellularization of
whole MVs. Porcine MVs were decellularized with 0.5% (w/
v) SDS and 0.5% (w/v) SD and sterilized with 0.1% (v/v) PAA.
Decellularized samples were seeded with human foreskin fibroblasts and human adipose-derived stem cells to investigate
cellular repopulation and infiltration, and with human colonyforming endothelial cells to investigate collagen IV formation.
Histology revealed an acellular scaffold with a generally conserved histoarchitecture, but collagen IV loss. Following
decellularization, no significant changes were observed in
the hydroxyproline content, but there was a significant reduction in the glycosaminoglycan content. SEM/TEM analysis
confirmed cellular removal and loss of some extracellular matrix components. Collagen and elastin were generally
preserved. The endothelial cells produced newly formed collagen IVon the non-cytotoxic scaffold. The protocol produced
acellular scaffolds with generally preserved histoarchitecture,
biochemistry, and biomechanics