Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

It is generally accepted that human bipedal upright stance is achieved by feedback mechanisms that generate an appropriate corrective torque based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Because orientation information from the various senses is not always available (eyes closed) or accurate (compliant support surface), the postural control system must somehow adjust to maintain stance in a wide variety of environmental conditions. This is the sensorimotor integration problem that we investigated by evoking anterior-posterior (AP) body sway using pseudorandom rotation of the visual surround and/or support surface (amplitudes 0.5-8 degrees ) in both normal subjects and subjects with severe bilateral vestibular loss (VL). AP rotation of body center-of-mass (COM) was measured in response to six conditions offering different combinations of available sensory information. Stimulus-response data were analyzed using spectral analysis to compute transfer functions and coherence functions over a frequency range from 0.017 to 2.23 Hz. Stimulus-response data were quite linear for any given condition and amplitude. However, overall behavior in normal subjects was nonlinear because gain decreased and phase functions sometimes changed with increasing stimulus amplitude. "Sensory channel reweighting" could account for this nonlinear behavior with subjects showing increasing reliance on vestibular cues as stimulus amplitudes increased. VL subjects could not perform this reweighting, and their stimulus-response behavior remained quite linear. Transfer function curve fits based on a simple feedback control model provided estimates of postural stiffness, damping, and feedback time delay. There were only small changes in these parameters with increasing visual stimulus amplitude. However, stiffness increased as much as 60% with increasing support surface amplitude. To maintain postural stability and avoid resonant behavior, an increase in stiffness should be accompanied by a corresponding increase in damping. Increased damping was achieved primarily by decreasing the apparent time delay of feedback control rather than by changing the damping coefficient (i.e., corrective torque related to body-sway velocity). In normal subjects, stiffness and damping were highly correlated with body mass and moment of inertia, with stiffness always about 1/3 larger than necessary to resist the destabilizing torque due to gravity. The stiffness parameter in some VL subjects was larger compared with normal subjects, suggesting that they may use increased stiffness to help compensate for their loss. Overall results show that the simple act of standing quietly depends on a remarkably complex sensorimotor control system.

Sensorimotor integration in human postural control

Falls in older people: risk factors and strategies for prevention.

CONTEXTUALIZACAO: A manutencao do equilibrio e da orientacao corporal em humanos e garantida pelo adequado funcionamento do sistema de controle postural. A investigacao desse controle tem despertado interesse em profissionais de diversas areas, tais como, Fisioterapia, Educacao Fisica, Engenharia, Fisica, Medicina, Psicologia, entre outras. OBJETIVOS: Revisar os metodos de analise experimental de dados utilizados para investigacao do controle postural em seres humanos e demonstrar o calculo e rotinas de programacao das principais medidas utilizadas na avaliacao desse controle. CONCLUSAO: Os procedimentos experimentais e as medidas utilizadas na avaliacao do controle postural apresentados nesta revisao poderao auxiliar na padronizacao da investigacao do controle postural.

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Revisão sobre posturografia baseada em plataforma de força para avaliação do equilíbrio

One dilemma with health claims is that too much information can confuse consumers and too little information can mislead them. Instead of using only one side of the package, a laboratory study is used to examine the effectiveness of various front-sided health claims when used in combination with a full health claim on the back panel. The results indicate that the presence of a short health claim on the front label generates more specific attribute-related thoughts, more inferences, and creates a more believable and positive image of the product in the consumers’ mind than does a longer health claim on the front label. This article concludes with a discussion of how labeling information needs to be presented to effectively allow consumers to understand and use claim information.

http://ieeexplore.ieee.org/iel5/5/31255/01454916.pdf

Information processing

Winter, David A., Aftab E. Patla, Francois Prince, Milad Ishac, and Krystyna Gielo-Perczak. Stiffness control of balance in quiet standing. J. Neurophysiol. 80: 1211–1221, 1998. Our goal was to pro...

Stiffness Control of Balance in Quiet Standing

The biomechanics of slips are an important component in the prevention of fall-related injuries The purpose of this paper is to review the available literature on the biomechanics of gait relevant to slips This knowledge can be used to develop slip resistance testing methodologies and to determine critical differences in human behaviour between slips leading to recovery and those resulting in falls Ground reaction forces at the shoe-floor interface have been extensively studied and are probably the most critical biomechanical factor in slips The ratio of the shear to normal foot forces generated during gait, known as the required coefficient of friction (RCOF) during normal locomotion on dry surfaces or 'friction used/achievable' during slips, has been one biomechanical variable most closely associated with the measured frictional properties of the shoe/floor interface (usually the coefficient of friction or COF) Other biomechanical factors that also play an important role are the kinematics of the foot at heel contact and human responses to slipping perturbations, often evident in the moments generated at the lower extremity joints and postural adaptations In addition, it must be realized that the biomechanics are dependent upon the capabilities of the postural control system, the mental set of the individual, and the perception of the environment, particularly, the danger of slipping The focus of this paper is to review what is known regarding the kinematics and kinetics of walking on surfaces under a variety of environmental conditions Finally, we discuss future biomechanical research needs to help to improve walkway-friction measurements and safety

Biomechanics of slips

A number of human-centred methodologies-subjective, objective, and combined-are used for slipperiness measurement. They comprise a variety of approaches from biomechanically-oriented experiments to psychophysical tests and subjective evaluations. The objective of this paper is to review some of the research done in the field, including such topics as awareness and perception of slipperiness, postural and balance control, rating scales for balance, adaptation to slippery conditions, measurement of unexpected movements, kinematics of slipping, and protective movements during falling. The role of human factors in slips and falls will be discussed. Strengths and weaknesses of human-centred approaches in relation to mechanical slip test methodologies are considered. Current friction-based criteria and thresholds for walking without slipping are reviewed for a number of work tasks. These include activities such as walking on a level or an inclined surface, running, stopping and jumping, as well as stair ascent and descent, manual exertion (pushing and pulling, load carrying, lifting) and particular concerns of the elderly and mobility disabled persons. Some future directions for slipperiness measurement and research in the field of slips and falls are outlined. Human-centred approaches for slipperiness measurement do have many applications. First, they are utilized to develop research hypotheses and models to predict workplace risks caused by slipping. Second, they are important alternatives to apparatus-based friction measurements and are used to validate such methodologies. Third, they are used as practical tools for evaluating and monitoring slip resistance properties of footwear, anti-skid devices and floor surfaces.

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Human-centred approaches in slipperiness measurement.

One of the important functions of the human brain is voluntary control of movements and motor activities combined with perceptual, cognitive and affective processes. This paper introduces the emerging field of study, named hereby as physical neuroergonomics, that focuses on the knowledge of human brain activities in relation to the control and design of physical tasks. Motor, cognitive and emotional aspects and their inter-relationships in connection to physical ergonomics are considered. A review of recent advances in functional electroencephalography (EEG), with special accent on the time domain analyses of the human brain activity in selected motor tasks, is also presented. The reported studies of isometric elbow-flexion contractions confirmed that the cerebral-cortex system controls the extent of muscle activation and is responsible for smoothing out high-speed motor control processes. Furthermore, the emotional attitudes of the subject to the activity can compel performance beyond acceptable loading ...

Physical neuroergonomics: The human brain in control of physical work activities

This paper proposes a complementary approach to Rasmussen's taxonomy of the human skill-, rule-, and knowledge-based performance models by combining the ecological concept of affordances with the neural concepts of human emotion and intuition. The classical cognitive engineering framework is extended through the neuro-ecological approach, including personal human attributes important in exercising control over the work environment. The proposed affordance-, emotion-, and intuition-based models correspond to the three types of human performance, namely: learning, adaptive and tuning control, respectively. The new framework is not a predictive model of the operator behaviour, but rather it describes the processes of neuro-ecological control of the human environment.

Krystyna Gielo-Perczak

Papers

Stiffness Control of Balance in Quiet Standing

Biomechanics of slips

Human-centred approaches in slipperiness measurement.

Physical neuroergonomics: The human brain in control of physical work activities

Ecological models of human performance based on affordance, emotion and intuition.