364 research outputs found

    Non-interference for deterministic interactive programs

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    We consider the problem of defining an appropriate notion of non-interference (NI) for deterministic interactive programs. Previous work on the security of interactive programs by O'Neill, Clarkson and Chong (CSFW 2006) builds on earlier ideas due to Wittbold and Johnson (Symposium on Security and Privacy 1990), and argues for a notion of NI defined in terms of strategies modelling the behaviour of users. We show that, for deterministic interactive programs, it is not necessary to consider strategies and that a simple stream model of the users' behaviour is sufficient. The key technical result is that, for deterministic programs, stream-based NI implies the apparently more general strategy-based NI (in fact we consider a wider class of strategies than those of O'Neill et al). We give our results in terms of a simple notion of Input-Output Labelled Transition System, thus allowing application of the results to a large class of deterministic interactive programming languages

    A Risk Reduction Framework for Design of Physical Human-Robot Collaboration

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    As robots designed to physically interact with humans become common in various application areas, shared workspaces and force exchange between human and robot lead to new challenges in terms of safety. Often, a variety of safety techniques is necessary, and deciding what methods to include in a comprehensive safety framework is not an easy task. This paper is concerned with the design of robotic co-wokers that involve physical Human-Robot Collaboration (pHRC), with humans and robots in continuous direct physical contact and exchanging forces. A hierarchical risk reduction framework is presented for guiding the design of robotic co-workers to reduce the risk associated with hazards commonly found in pHRC tasks. A case study is presented to demonstrate the use of the framework in designing an Assistance-as-Needed roBOT (ANBOT) which has been extensively tested in practical industry applications

    Human User Impressions of Damping Methods for Singularity Handling in Human-Robot Collaboration

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    Kinematic singularity is a fundamental and well understood problem of robot manipulators, with many methods having been developed to ensure safe and robust operation in proximity to singularity. However little attention has been given to the scenario where the robot and human are working in physical contact to collaboratively perform a task. In such a scenario the feelings and impressions of the human operator should be considered when developing solutions for handling singularity. This work presents an experimental study comparing three modes of handling kinematic singularities with respect to the impressions of the human operator. Two of the modes are based on traditional Damped-Least-Squares. The third method uses an asymmetric damping behavior proposed as being well suited for applications involving physical human-robot interaction. The three modes are tested and compared by subjects performing a mock industrial task, and feedback from the subjects analyzed to identify the preferred mode. Results indicate that the choice of method used affects the user’s impressions of the interaction, and the asymmetrical damping behavior can produce a preferred interaction experience with human operators during tasks

    Effect of external force and bimanual operation on upper limb pose during human-robot collaboration

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    During physical Human-Robot Interaction (pHRI) in industrial applications such as human-robot collaborative abrasive blasting, the operator often interacts with the robot using two hands, exchanging forces through handle bars. For the robot to provide appropriate assistance to the operator and for safe interaction, it would be benefficial for the robot to know the pose of the user. This problem is often challenging due to environmental factors, limited sensing capability in the environment and the robot, and redundancy of the human upper-limb. This paper presents experimental study on how two-hand interaction and force exchange affect the operators upper-limb pose, which can be characterized by swivel angle. The poses of ten subjects were recorded as they interacted with a collaborative robot. Differences in the adopted upper limb pose were analyzed with respect to factors such as unimanual versus bimanual operation, and the amplitude of interaction force between an operator and the robot. The results discovered that the the effect of bimanual operation on the upper limb pose differs between individuals and the magnitude of the force had a varying effect on the pose. The requirement of applying a force forward produced an overall lower swivel angle

    Bigraphical modelling of architectural patterns

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    Selected for publication in FACS'2011 post-proceedings, to appear in Springer Lecture Notes in Computer ScienceArchery is a language for behavioural modelling of architectural patterns, supporting hierarchical composition and a type discipline. This paper extends Archery to cope with the patterns' structural dimension through a set of (re-)configuration combinators and constraints that all instances of a pattern must obey. Both types and instances of architectural patterns are semantically represented as bigraphical reactive systems and operations upon them as reaction rules. Such a bigraphical semantics provides a rigorous model for Archery patterns and reduces constraint verification in architectures to a type-checking problem.(undefined

    Insights into the effects of N-glycosylation on the characteristics of the VC1 domain of the human receptor for advanced glycation end products (RAGE) secreted by Pichia pastoris

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    Advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs), resulting from non-enzymatic modifications of proteins, are potentially harmful to human health. They directly act on proteins, affecting structure and function, or through receptor-mediated mechanisms. RAGE, a type I transmembrane glycoprotein, was identified as a receptor for AGEs. RAGE is involved in chronic inflammation, oxidative stress-based diseases and ageing. The majority of RAGE ligands bind to the VC1 domain. This domain was successfully expressed and secreted by Pichia pastoris. Out of two N-glycosylation sites, one (Asn25) was fully occupied while the other (Asn81) was under-glycosylated, generating two VC1 variants, named p36 and p34. Analysis of N-glycans and of their influence on VC1 properties were here investigated. The highly sensitive procainamide labeling method coupled to ES-MS was used for N-glycan profiling. N-glycans released from VC1 ranged from Man9GlcNAc2- to Man15GlcNAc2- with major Man10GlcNAc2- and Man11GlcNAc2- species for p36 and p34, respectively. Circular dichroism spectra indicated that VC1 maintains the same conformation also after removal of N-glycans. Thermal denaturation curves showed that the carbohydrate moiety has a small stabilizing effect on VC1 protein conformation. The removal of the glycan moiety did not affect the binding of VC1 to sugar-derived AGE- or malondialdehyde-derived ALE-human serum albumin. Given the crucial role of RAGE in human pathologies, the features of VC1 from P. pastoris will prove useful in designing strategies for the enrichment of AGEs/ALEs from plasma, urine or tissues, and in characterizing the nature of the interaction

    Advanced quantitative proteomics to evaluate molecular effects of low-molecular-weight hyaluronic acid in human dermal fibroblasts

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    Hyaluronic acid (HA) is physiologically synthesized by several human cells types but it is also a widespread ingredient of commercial products, from pharmaceuticals to cosmetics. Despite its extended use, the precise intra- and extra-cellular effects of HA at low-molecular-weight (LWM-HA) are currently unclear. At this regard, the aim of this study is to in-depth identify and quantify proteome's changes in normal human dermal fibroblasts after 24 h treatment with 0.125, 0.25 and 0.50 % LMW-HA (20 1250 kDa) respectively, vs controls. To do this, a label-free quantitative proteomic approach based on high-resolution mass spectrometry was used. Overall, 2328 proteins were identified of which 39 significantly altered by 0.125 %, 149 by 0.25 % and 496 by 0.50 % LMW-HA. Protein networking studies indicated that the biological effects involve the enhancement of intracellular activity at all concentrations, as well as the extracellular matrix reorganization, proteoglycans and collagen biosynthesis. Moreover, the cell's wellness was confirmed, although mild inflammatory and immune responses were induced at the highest concentration. The more complete comprehension of intra- and extra-cellular effects of LMW-HA here provided by an advanced analytical approach and protein networking will be useful to further exploit its features and improve current formulations
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