Physical activity and postural control in the elderly: Coupling between visual information and body sway

Background: Aging is characterized by a decline in the postural control performance, which is based on a coherent and stable coupling between sensory information and motor action. Therefore, changes in postural control in elderlies can be related to changes in this coupling. In addition, it has been observed that physical activity seems to improve postural control performance in elderlies. These improvements can be due to changes in the coupling between sensory information and motor action related to postural control. Objective: the purpose of this study was to verify the coupling between visual information and body sway in active and sedentary elderlies. Methods: Sixteen sedentary elderlies ( SE), 16 active elderlies ( AE) and 16 young adults ( YA) were asked to stand upright inside a moving room in two experimental conditions: ( 1) discrete movement and ( 2) continuous movement of the room. Results: In the continuous condition, the results showed that the coupling between the movement of the room and body sway was stronger and more stable for SE and AE compared to YA. In the discrete condition, SE showed larger body displacement compared to AE and YA. Conclusions: SE have more difficulty to discriminate and to integrate sensory information than AE and YA indicating that physical activity may improve sensory integration. Copyright (C) 2005 S. Karger AG, Basel.

TEMPORAL COUPLING BETWEEN EXTERNAL AUDITORY INFORMATION AND THE PHASES OF WALKING

The purpose of this study was to investigate the effects of an imposed external auditory constraint upon the temporal organization of walking. Ten subjects were videotaped walking normally (N) and with instructions to couple naturally, at mid-swing, or at toe-off to a metronome beat. Based upon an analysis of variance and post hoc Scheffe tests most temporal variables were not significantly different among conditions. The duration of swing phase was significantly different between natural coupling and toe-off. The deviation from the metronome beat was significantly different between the natural coupling and both mid-swing and toe-off. Subjects generally were not successful in achieving coupling during the latter conditions. Thigh and shank phase portraits were used to describe the system's organization to the external constraint.

Entropy, information and doubly stochastic transformations

I analyze two inequalities on entropy and information, one due to von Neumann and a recent one to Schiffer, and show that the relevant quantities in these inequalities are related by special doubly stochastic matrices (DSM). I then use generalization of the first inequality to prove algebraically a generalization of Schiffer's inequality to arbitrary DSM. I also give a second interpretation to the latter inequality, determine its domain of applicability, and illustrate it by using Zeeman splitting. This example shows that symmetric (degenerate) systems have less entropy than the corresponding split systems, if compared at the same average energy. This seemingly counter-intuitive result is explained thermodynamically. © 1991.

Visual information and body sway coupling in infants during sitting acquisition

The purpose of this study was to examine if there is any developmental change in the coupling between visual information and trunk sway in infants as they acquire the sitting position. Twenty-four infants distributed in four groups (6-, 7-, 8-, and 9-month-old) were sat inside a moving room that oscillated back and forward at frequencies of 0.2 and 0.5 Hz. The results revealed that trunk sway matched to the moving room at both frequencies but did not differ among the four age groups. Coherence and gain revealed that the coupling was weaker at 0.2 than at 0.5 Hz. Relative phase showed that at 0.2 Hz, infants were swaying with no lag but at 0.5 Hz they were lagging the room. These results showed that the coupling between visual information and trunk sway in infants varies with the visual stimulus but does not change as infants acquire the sitting position. © 2001 Elsevier B.V.

Information and mechanical models of intelligence: What can we learn from cognitive science?

The impact of new advanced technology on issues that concern meaningful information and its relation to studies of intelligence constitutes the main topic of the present paper. The advantages, disadvantages and implications of the synthetic methodology developed by cognitive scientists, according to which mechanical models of the mind, such as computer simulations or self-organizing robots, may provide good explanatory tools to investigate cognition, are discussed. A difficulty with this methodology is pointed out, namely the use of meaningless information to explain intelligent behavior that incorporates meaningful information. In this context, it is inquired what are the contributions of cognitive science to contemporary studies of intelligent behavior and how technology may play a role in the analysis of the relationships established by organisms in their natural and social environments. © John Benjamins Publishing Company.

Abductive reasoning, information, and mechanical systems

We investigate, from a philosophical perspective, the relation between abductive reasoning and information in the context of biological systems. Emphasis is given to the organizational role played by abductive reasoning in practical activities of embodied embedded agency that involve meaningful information. From this perspective, meaningful information is provisionally characterized as a selforganizing process of pattern generation that constrains coherent action. We argue that this process can be considered as a part of evolutionarily developed learning abilities of organisms in order to help with their survival. We investigate the case of inorganic mechanical systems (like robots), which deal only with stable forms of habits, rather than with evolving learning abilities. Some difficulties are considered concerning the hypothesis that mechanical systems may operate with meaningful information, present in abductive reasoning. Finally, an example of hypotheses creation in the domain of medical sciences is presented in order to illustrate the complexity of abduction in practical reasoning concerning human activities. © 2007 Springer-Verlag Berlin Heidelberg.

Collectives of humans-with-media in mathematics education: Notebooks, blackboards, calculators, computers and ... notebooks throughout 100 years of ICMI

The main aim of this study was to present evidence of the ways in which different media have conditioned and dramatically reorganized education, in general, and mathematics education, in particular. After an introduction of the theme, we discuss the epistemological perspective that provides the foundation for our analysis: the notion of humans-with-media. Then, we briefly illustrate how the medium is related to the scientific production of mathematical knowledge. We take a detour into the world of art to examine how devices and instruments have historically been associated with the production of mathematical knowledge. Then, we review studies on the history of education to show how traditional media were introduced into schools and have influenced education. In particular, we examine how devices such as blackboards and notebooks, which were novelties a 100 years ago, came to be accepted in schools and the mathematical activities that were promoted with their use. Finally, we discuss how information technology has changed education and how the Internet may have an impact on mathematics education comparable to that of the notebook over a century ago. © FIZ Karlsruhe 2009.

e-Health in Latin America and the Caribbean: progress and challenges

Includes bibliography