The implications of embodiment for behavior and cognition: animal and robotic case studies

In this paper, we will argue that if we want to understand the function of the brain (or the control in the case of robots), we must understand how the brain is embedded into the physical system, and how the organism interacts with the real world. While embodiment has often been used in its trivial meaning, i.e. 'intelligence requires a body', the concept has deeper and more important implications, concerned with the relation between physical and information (neural, control) processes. A number of case studies are presented to illustrate the concept. These involve animals and robots and are concentrated around locomotion, grasping, and visual perception. A theoretical scheme that can be used to embed the diverse case studies will be presented. Finally, we will establish a link between the low-level sensory-motor processes and cognition. We will present an embodied view on categorization, and propose the concepts of 'body schema' and 'forward models' as a natural extension of the embodied approach toward first representations.Comment: Book chapter in W. Tschacher & C. Bergomi, ed., 'The Implications of Embodiment: Cognition and Communication', Exeter: Imprint Academic, pp. 31-5

Robots as Powerful Allies for the Study of Embodied Cognition from the Bottom Up

A large body of compelling evidence has been accumulated demonstrating that embodiment – the agent’s physical setup, including its shape, materials, sensors and actuators – is constitutive for any form of cognition and as a consequence, models of cognition need to be embodied. In contrast to methods from empirical sciences to study cognition, robots can be freely manipulated and virtually all key variables of their embodiment and control programs can be systematically varied. As such, they provide an extremely powerful tool of investigation. We present a robotic bottom-up or developmental approach, focusing on three stages: (a) low-level behaviors like walking and reflexes, (b) learning regularities in sensorimotor spaces, and (c) human-like cognition. We also show that robotic based research is not only a productive path to deepening our understanding of cognition, but that robots can strongly benefit from human-like cognition in order to become more autonomous, robust, resilient, and safe

Non-perturbative renormalization of the axial current with improved Wilson quarks

We present a new normalization condition for the axial current, which is derived from the PCAC relation with non-vanishing mass. Using this condition reduces the O(r_0 m) corrections to the axial current normalization constant Z_A for an easier chiral extrapolation in the cases, where simulations at zero quark-mass are not possible. The method described here also serves as a preparation for a determination of Z_A in the full two-flavor theory.Comment: 3 pages, 3 figures, Lattice2003(improve

A comparison of control concepts for wind turbines in terms of energy capture

In this study, eight different control concepts for wind turbines are compared in terms of their annual energy capture. In detail, they are a stall controlled single speed concept, a stall controlled two speed concept, an active stall controlled single speed concept, an active stall controlled two speed concept, a pitch controlled single speed concept, a pitch controlled two speed concept, a stall controlled variable speed concept and finally a pitch controlled variable speed concept. In order to be able to expose all these different concepts to exactly the same wind conditions, numerical computer simulation is chosen as the appropriate method to do the comparison, as in reality it is almost impossible to achieve the same wind conditions for different turbines. This approach also prevents all possible differences in rotor layout between the individual concepts from entering into the results, as it is possible to use the same rotor design for all control concepts. Because the influence of time variant quantities such as the turbulent wind flow on a nonlinear system ( e.g. a wind turbine rotor) has to be taken into account, an analytical representation had to be found which allowed a time-step simulation. This especially set some limits on the complexity allowed for the numerical model. Therefore the modeling of all parts of the system (whether they are aerodynamic, mechanic or electric) is kept rather simplistic. As a comparison of general control concepts is the topic of this study, the controllers are not modeled as they are used by a certain manufacturer. Instead they are modeled in an idealized way, each of which covers the ideal performance of one class of control concepts. For each combination of parameters, one time domain simulation was performed. The output data was then weighted and averaged in order to obtain the energy captured from the wind within one year. These energy values are finally arranged in a way which allows an easy comparison between the relative performance of all control concepts under consideration. The results show the differences in the annual energy capture of the eight concepts as a function of site conditions (the annual mean wind speed, the turbulence and the shape parameter of the Weibull distribution assumed for the annual wind speed distribution) as well as their dependence on two design parameters (the design tip speed ratio and the choice of rotor profiles). Due to the rather crude modeling these results have to be seen more qualitatively then quantitatively. However, they show to which extent a comparison between different control concepts depends on the values of different parameters. Hopefully, they also lead to a deeper understanding of the very different results of similar comparisons found in the literature

Non-perturbative quark mass renormalization in two-flavor QCD

The running of renormalized quark masses is computed in lattice QCD with two flavors of massless O(a) improved Wilson quarks. The regularization and flavor independent factor that relates running quark masses to the renormalization group invariant ones is evaluated in the Schroedinger Functional scheme. Using existing data for the scale r_0 and the pseudoscalar meson masses, we define a reference quark mass in QCD with two degenerate quark flavors. We then compute the renormalization group invariant reference quark mass at three different lattice spacings. Our estimate for the continuum value is converted to the strange quark mass with the help of chiral perturbation theory.Comment: 25 pages, 6 figures; sections 1 and 4 rearranged, minor change to the summary plo

Interleukin-1β-Induced Inhibition of Hair Growth In Vitro Is Mediated by Cyclic AMP

Interleukin (IL)-1 has been shown to be a potent inhibitor of hair growth in vitro. We hypothesized that this cytokine might be a decisive factor causing hair loss during the lymphocytic attack in alopecia areata. Neither the intracellular pathways involved in hair growth inhibition mediated by IL-1β nor the signal transduction processes within hair follicles in general are known. We therefore investigated the intracellular signals involved in human hair growth in vitro. Hair follicles were isolated from scalp biopsies by microdissection and hair growth was measured daily by image analysis. We assessed intracellular signal transducing elements using specific inhibitors or activators either alone or in combination with IL-1β. The calcium ionophore A 23187 induced a rapid and complete arrest of hair growth and phorbol-12-myristate-13-acetate (PMA), genistein, or IL-1β decreased hair growth by approximately 60%-80%. IL-1β-elicited hair growth arrest was not antagonized by calphostin C, a specific inhibitor of protein kinase C. In contrast, coincubation of IL-1β with pertussis toxin or H 1004 neutralized the effect of IL-1β and dibutyryl-cAMP and cholera toxin, an activator of adenylate cyclase, inhibited hair growth. These data suggest that cAMP acts as a second messenger for IL-1β-induced inhibition of hair growth. Moreover, our data indicate that in vitro hair growth is dependent on intracellular Ca2+ levels and activation of tyrosine kinase as well as protein kinase C. We were unable to detect a signal transducing element responsible for enhanced hair growth in vitro