Eye-Hand Coordination during Dynamic Visuomotor Rotations

Background for many technology-driven visuomotor tasks such as tele-surgery, human operators face situations in which the frames of reference for vision and action are misaligned and need to be compensated in order to perform the tasks with the necessary precision. The cognitive mechanisms for the selection of appropriate frames of reference are still not fully understood. This study investigated the effect of changing visual and kinesthetic frames of reference during wrist pointing, simulating activities typical for tele-operations. Methods using a robotic manipulandum, subjects had to perform center-out pointing movements to visual targets presented on a computer screen, by coordinating wrist flexion/extension with abduction/adduction. We compared movements in which the frames of reference were aligned (unperturbed condition) with movements performed under different combinations of visual/kinesthetic dynamic perturbations. The visual frame of reference was centered to the computer screen, while the kinesthetic frame was centered around the wrist joint. Both frames changed their orientation dynamically (angular velocity\u200a=\u200a36\ub0/s) with respect to the head-centered frame of reference (the eyes). Perturbations were either unimodal (visual or kinesthetic), or bimodal (visual+kinesthetic). As expected, pointing performance was best in the unperturbed condition. The spatial pointing error dramatically worsened during both unimodal and most bimodal conditions. However, in the bimodal condition, in which both disturbances were in phase, adaptation was very fast and kinematic performance indicators approached the values of the unperturbed condition. Conclusions this result suggests that subjects learned to exploit an \u201caffordance\u201d made available by the invariant phase relation between the visual and kinesthetic frames. It seems that after detecting such invariance, subjects used the kinesthetic input as an informative signal rather than a disturbance, in order to compensate the visual rotation without going through the lengthy process of building an internal adaptation model. Practical implications are discussed as regards the design of advanced, high-performance man-machine interfaces

Angiopoietin-1 promotes functional neovascularization that relieves ischemia by improving regional reperfusion in a swine chronic myocardial ischemia model

10.1007/s11373-006-9082-xJournal of Biomedical Science134579-59

A radioimmunoassay to screen for antibodies to native conformational antigens and analyse ligand-induced structural states of antigenic proteins

A radioimmunoassay is described in which antigenic protein was immobilized by incubating nitrocellulose filters of defined diameter with antigen-containing solutions. The amount of adsorbed antigen increased in a linear fashion over a wide range of antigen concentrations. The antigen-antibody reactions and the indicator reactions were performed by incubating the filters with appropriate solutions. During the test any contact of the antigen with air was avoided. Antigenic sites which are sensitive to protein denaturation by drying could be detected with the assay. The assay was also used to screen hybridoma supernatants for antibodies directed against Na+ cotransport proteins from renal brush-border membranes. Monoclonal antibodies were selected which showed different binding characteristics depending on whether or not substrates of Na+ cotransporters were present. Since binding of several antibodies was altered by two different substrates and not by non-transported control substances, these monoclonal antibodies were believed to interact with more than one transport system. One of the antibodies, which showed different antibody binding after addition of D-glucose or L-lactate, bound to a polypeptide component of the renal Na+-D-glucose cotransporter and was able to inhibit Na+ gradient-dependent D-glucose uptake in brush-border membrane vesicles (Koepsell, Korn, Raszeja-Specht, Bernotat-Danielowski, Ollig, 1988, J. Biol. Chem., in press). To investigate the effects of D-glucose and L-lactate on the binding of this antibody concentration dependence was measured. High and low affinity binding sites for D-glucose and L-lactate were characterized thereby demonstrating that the radioimmunoassay permits investigations of the properties of high and low affinity substrate binding site

Application of multi-dimensional markov chains to model kinetics of grinding with internal classification

International audienc

Monoclonal antibodies against the renal Na⁺-D-glucose cotransporter. Identification of antigenic polypeptides and demonstration of functional coupling of different Na⁺-cotransport systems

Eight monoclonal antibodies are described which are directed against the renal Na+-D-glucose cotransporter. In porcine renal brush-border membranes, the antibodies either bind to one or to three polypeptides which have been identified as components of the Na+-D-glucose cotransporter (Neeb, M., Kunz, U., and Koepsell, H., (1987) J. Biol. Chem. 262, 10718-10727). Their molecular weights and isoelectric points are 75,000 and pH 5.5, 60,000 and pH 5.2, and 47,000 and pH 5.4. Six antibodies were able to influence Na+-dependent D-glucose uptake and/or Na+-dependent high affinity phlorizin binding. In the presence of Na+, the binding of all antibodies to native membrane proteins was altered by D-glucose but not by D-mannose. Since this effect was observed with D-glucose concentrations less than 1 x 10(-8) M, a high affinity D-glucose-binding site on the D-glucose transporter has been implied. Some of the antibodies probably interact also with other Na+-coupled transporters since their binding was altered by micromolar concentrations of L-lactate, L-alanine, or L-glutamate but not by the nontransported control substances D-alanine and D-glutamate. L-lactate increased the binding of one antibody in the absence but not in the presence of D-glucose. Effects of L-lactate and L-alanine on the binding of another antibody were only observed when D-glucose was present. Thus, some epitopes on the Na+-D-glucose cotransporter are altered by D-glucose and also by substrates of other Na+ cotransporters. This finding suggests functional coupling of different Na+-cotransport systems

Effects of classifier design on fine grinding bowl mills

Translated form German (Paper presented to the VGB Conference, Coal Handling and Ash Removal, Essen (DE), 13-14 Dec 1989)Available from British Library Document Supply Centre- DSC:6196.3(EA-OA-Trans--4139)T / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo