When Art Moves the Eyes: A Behavioral and Eye-Tracking Study

The aim of this study was to investigate, using eye-tracking technique, the influence of bottom-up and top-down processes on visual behavior while subjects, na \u308\u131ve to art criticism, were presented with representational paintings. Forty-two subjects viewed color and black and white paintings (Color) categorized as dynamic or static (Dynamism) (bottom-up processes). Half of the images represented natural environments and half human subjects (Content); all stimuli were displayed under aesthetic and movement judgment conditions (Task) (top-down processes). Results on gazing behavior showed that content-related top-down processes prevailed over low-level visually-driven bottom-up processes when a human subject is represented in the painting. On the contrary, bottom-up processes, mediated by low-level visual features, particularly affected gazing behavior when looking at nature-content images. We discuss our results proposing a reconsideration of the definition of content-related top-down processes in accordance with the concept of embodied simulation in art perception

Impairment of Auditory-Motor Timing and Compensatory Reorganization after Ventral Premotor Cortex Stimulation

Integrating auditory and motor information often requires precise timing as in speech and music. In humans, the position of the ventral premotor cortex (PMv) in the dorsal auditory stream renders this area a node for auditory-motor integration. Yet, it remains unknown whether the PMv is critical for auditory-motor timing and which activity increases help to preserve task performance following its disruption. 16 healthy volunteers participated in two sessions with fMRI measured at baseline and following rTMS (rTMS) of either the left PMv or a control region. Subjects synchronized left or right finger tapping to sub-second beat rates of auditory rhythms in the experimental task, and produced self-paced tapping during spectrally matched auditory stimuli in the control task. Left PMv rTMS impaired auditory-motor synchronization accuracy in the first sub-block following stimulation (p<0.01, Bonferroni corrected), but spared motor timing and attention to task. Task-related activity increased in the homologue right PMv, but did not predict the behavioral effect of rTMS. In contrast, anterior midline cerebellum revealed most pronounced activity increase in less impaired subjects. The present findings suggest a critical role of the left PMv in feed-forward computations enabling accurate auditory-motor timing, which can be compensated by activity modulations in the cerebellum, but not in the homologue region contralateral to stimulation

Preliminary design of seismically isolated R/C highway overpasses- Features of relevant software and experimental testing of elastomeric bearings

The preliminary design of seismically isolated R/C highway overpasses is the tar-get of a software based on the current design provisions of Eurocode 8 (Part 2) as well as on engineering decisions included in the expert system. The features of this expert system, which is aimed to facilitate the design of a highway overpass by isolating its deck with the inclusion of elastomeric bearings, are presented and discussed. For such an upgrade scheme a number of successive checks is necessary in order to select an optimum geometry of the bearings. The developed software includes a series of checks provided by Eurocode 8 (Part 2), in order to ensure the satisfactory seismic performance of the selected upgrade scheme. In doing so, the software accesses a specially created database of the geometrical and mechanical character-istics of either cylindrical or prismatic elastometallic bearings which are commercially avail-able; this database can be easily enriched by relevant data from laboratory tests on isolation devices. The basic assumptions included in the software are (a) modeling the seismic re-sponse of the bridge overpass as a SDOF system, and (b) only the longitudinal direction re-sponse is considered; it is common practice for seismically isolated bridge systems to restrain the transverse movement of the deck by stoppers. Moreover, the results form a number of tests performed in the Laboratory of Strength of Materials and Structures of Aristotle Univer-sity, verified the quality of the production process of a local producer of elastomeric bearings subjecting production samples to the sequence of tests specified by International Standard ISO 22762-1 (2005). Strain amplitudes larger than 250% resulted in the debonding of the elastomer from the steel plating. Artificial aging resulted in a small increase of the axial (ver-tical) stiffness and a small decrease of the shear (horizontal) stiffness of the tested bearings. More specimens must be tested to validate further these findings

Shaking table study of the seismic interaction of an isolated bridge deck with the abutment utilizing small-scale models and numerical simulations

It has been recognized that an isolated deck develops horizontal displacements of considerable amplitude during a strong earthquake. In this case the possibility of mobilizing the abutments in moderating such large amplitude horizontal response is beneficial for the safety of the structure. Thus, apart from lowering the seismic forces by the low-stiffness isolator units, the interaction between the deck and the abutments in the form of pounding for large horizontal deck response amplitudes aims at limiting through this mechanism excessive horizontal deck displacements. Such a problem was examined at the laboratory of Strength of Materials and Structures of Aristotle University using a small-scale physical representation that retains in a qualitative way the following important features: 1. A relatively stiff steel platform, representing the bridge deck, which is supported on a shaking table by two flexible supports, representing the isolator units; it is subjected to simulated horizontal earthquake motions developing large amplitude horizontal displacement response. 2. The possibility of bridge deck pounding on the abutment was introduced through a connector device that became active after the deck response exceeded a certain amplitude, introducing an initial gap within this connector. Despite the fact that these two basic response mechanisms, flexibility of isolator units and connector force-displacement characteristics, are crude small-scale representations of the actual mechanisms that are mobilized in a prototype bridge deck, the qualitative characteristics of this problems are retained. A number of simulated earthquake tests provided the necessary measured acceleration and displacement response of the model steel platform of the small-scale model and the force-displacement response of the connector and the flexible supports of the steel platform with the shaking table. This was next utilized to validate numerical simulations of this small-scale experimental representation of the bridge-deck pounding problem. By comparing the numerical predictions with the measured response of this small-scale experimental representation of the bridge-deck pounding problem it can be concluded that such numerical simulations can yield quite accurate predictions provided that the force-displacement characteristics of the isolator units as well as the force-displacement characteristics of the mechanism representing the bridge deck-abutment pounding are defined with reasonable accuracy for the prototype bridge

Preliminary design of seismically isolated R/C highway overpasses- Features of relevant software and experimental testing of elastomeric bearings

The preliminary design of seismically isolated R/C highway overpasses is the tar-get of a software based on the current design provisions of Eurocode 8 (Part 2) as well as on engineering decisions included in the expert system. The features of this expert system, which is aimed to facilitate the design of a highway overpass by isolating its deck with the inclusion of elastomeric bearings, are presented and discussed. For such an upgrade scheme a number of successive checks is necessary in order to select an optimum geometry of the bearings. The developed software includes a series of checks provided by Eurocode 8 (Part 2), in order to ensure the satisfactory seismic performance of the selected upgrade scheme. In doing so, the software accesses a specially created database of the geometrical and mechanical character-istics of either cylindrical or prismatic elastometallic bearings which are commercially avail-able; this database can be easily enriched by relevant data from laboratory tests on isolation devices. The basic assumptions included in the software are (a) modeling the seismic re-sponse of the bridge overpass as a SDOF system, and (b) only the longitudinal direction re-sponse is considered; it is common practice for seismically isolated bridge systems to restrain the transverse movement of the deck by stoppers. Moreover, the results form a number of tests performed in the Laboratory of Strength of Materials and Structures of Aristotle Univer-sity, verified the quality of the production process of a local producer of elastomeric bearings subjecting production samples to the sequence of tests specified by International Standard ISO 22762-1 (2005). Strain amplitudes larger than 250% resulted in the debonding of the elastomer from the steel plating. Artificial aging resulted in a small increase of the axial (ver-tical) stiffness and a small decrease of the shear (horizontal) stiffness of the tested bearings. More specimens must be tested to validate further these findings

Shaking table study of the seismic interaction of an isolated bridge deck with the abutment utilizing small-scale models and numerical simulations

It has been recognized that an isolated deck develops horizontal displacements of considerable amplitude during a strong earthquake. In this case the possibility of mobilizing the abutments in moderating such large amplitude horizontal response is beneficial for the safety of the structure. Thus, apart from lowering the seismic forces by the low-stiffness isolator units, the interaction between the deck and the abutments in the form of pounding for large horizontal deck response amplitudes aims at limiting through this mechanism excessive horizontal deck displacements. Such a problem was examined at the laboratory of Strength of Materials and Structures of Aristotle University using a small-scale physical representation that retains in a qualitative way the following important features: 1. A relatively stiff steel platform, representing the bridge deck, which is supported on a shaking table by two flexible supports, representing the isolator units; it is subjected to simulated horizontal earthquake motions developing large amplitude horizontal displacement response. 2. The possibility of bridge deck pounding on the abutment was introduced through a connector device that became active after the deck response exceeded a certain amplitude, introducing an initial gap within this connector. Despite the fact that these two basic response mechanisms, flexibility of isolator units and connector force-displacement characteristics, are crude small-scale representations of the actual mechanisms that are mobilized in a prototype bridge deck, the qualitative characteristics of this problems are retained. A number of simulated earthquake tests provided the necessary measured acceleration and displacement response of the model steel platform of the small-scale model and the force-displacement response of the connector and the flexible supports of the steel platform with the shaking table. This was next utilized to validate numerical simulations of this small-scale experimental representation of the bridge-deck pounding problem. By comparing the numerical predictions with the measured response of this small-scale experimental representation of the bridge-deck pounding problem it can be concluded that such numerical simulations can yield quite accurate predictions provided that the force-displacement characteristics of the isolator units as well as the force-displacement characteristics of the mechanism representing the bridge deck-abutment pounding are defined with reasonable accuracy for the prototype bridge

A knowledge-based software for the preliminary design of seismically isolated bridges

Seismic design of isolated bridges involves conceptual, preliminary and detailed structural design. However, despite the variety of commercial software currently available for the analysis and design of such systems, conceptual and preliminary design can prove to be a non-straightforward procedure because of the sensitivity of bridge response on the initial decisions made by the designer of the location, number and characteristics of the bearings placed, as well as on a series of broader criteria such as serviceability, target performance level and cost-effectiveness of the various design alternatives. Given the lack of detailed design guidelines to ensure, at this preliminary stage, compliance with the above requirements, a "trial and error" procedure is typically followed in the design office to decide on the most appropriate design scheme in the number and location of the bearing systems; the latter typically based on engineering judgment to balance performance with cost. To this end, the particular research effort aims to develop a decision-making system for the optimal preliminary design of seismically isolated bridges, assumed to respond as single degree of freedom (SDOF) systems. The proposed decision-making process is based on the current design provisions of Eurocode 8, but is complemented by additional criteria set according to expert judgment, laboratory testing and recent research findings, while using a combined cost/performance criterion to select from a database of bearings available on the international market. Software is also developed for the implementation of the system. The paper concludes with the application, and essentially the validation of the methodology and software developed through more rigorous MDOF numerical analysis for the case of a real bridge. © Springer Science+Business Media B.V. 2011