Search results for "traje"
showing 10 items of 382 documents
Investigating centre of mass stabilisation as the goal of posture and movement coordination during human whole body reaching
2000
In the light of experimental results showing significant forward centre of mass (CoM) displacements within the base of support, this study investigated if whole body reaching movements can be executed whilst keeping the CoM fixed in the horizontal axis. Using kinematic simulation techniques, angular configurations were recreated from experimental data imposing two constraints: a constant horizontal position of the CoM and an identical trajectory of the hand to grasp an object. The comparison between recorded and simulated trials showed that stabilisation of the CoM was associated with greater backward hip displacements, which became more marked with increasing object distance. This was in c…
Kinematic and dynamic processes for the control of pointing movements in humans revealed by short-term exposure to microgravity.
2004
The generation of accurate motor commands requires implicit knowledge of both limb and environmental dynamics. The action of gravity on moving limb segments must be taken into account within the motor command, and may affect the limb trajectory chosen to accomplish a given motor task. Exactly how the CNS deals with these gravitoinertial forces remains an open question. Does the CNS measure gravitational forces directly, or are they accommodated in the motor plan by way of internal models of physical laws? In this study five male subjects participated. We measured kinematic and dynamic parameters of upward and downward arm movements executed at two different speeds, in both normal Earth grav…
Did you see that? Dissociating advanced visual information and ball flight constrains perception and action processes during one-handed catching
2013
The integration of separate, yet complimentary, cortical pathways appears to play a role in visual perception and action when intercepting objects. The ventral system is responsible for object recognition and identification, while the dorsal system facilitates continuous regulation of action. This dual-system model implies that empirically manipulating different visual information sources during performance of an interceptive action might lead to the emergence of distinct gaze and movement pattern profiles. To test this idea, we recorded hand kinematics and eye movements of participants as they attempted to catch balls projected from a novel apparatus that synchronised or de-synchronised ac…
Able or unable to work? : Life trajectory after severe occupational injury
2018
Purpose: To study the probabilities and permanence of return to work, inability to work and rehabilitation, and to explore the connection between these life situations and later working after a sev...
Hand trajectory formation during whole body reaching movements in man.
1998
End-effector trajectory formation was studied during a reaching movement using the whole body. The movements of various parts of the body were measured with the optoelectronic ELITE system. Wrist reaching movement paths showed noticeable curvatures. The analysis of various marker onset latencies revealed that the wrist was the last to move, always after the head, knee or trunk, suggesting a subordinate role of the focal component with respect to the primary role of the equilibrium component. These results suggest that reaching wrist movements are subjected to whole-body equilibrium constraints in addition to constraints placed upon end-effector kinematics or the dynamic optimization of uppe…
Effect of childhood developmental coordination disorder on adulthood physical activity; Arvo Ylppö longitudinal study
2022
Publisher Copyright: © 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd. Individuals at risk of Developmental Coordination Disorder (DCD) have low levels of physical activity in childhood due to impaired motor competence; however, physical activity levels in adulthood have not been established. This study sought to determine the impact of DCD risk on physical activity levels in adults using accelerometry measurement. Participants (n = 656) from the Arvo Ylppö Longitudinal Study cohort had their motor competence assessed at the age of five years, and their physical activity quantified via device assessment at the age of 25 years. Betwe…
Climatology of the aerosol extinction-to-backscatter ratio from sun-photometric measurements
2010
The elastic lidar equation contains two unknown atmospheric parameters, namely, the particulate optical extinction and backscatter coefficients, which are related through the lidar ratio (i.e., the particulate-extinction-to-backscatter ratio). So far, independent inversion of the lidar signal has been carried out by means of Raman lidars (usually limited to nighttime measurements), high-spectral-resolution lidars, or scanning elastic lidars under the assumption of a homogeneously vertically stratified atmosphere. In this paper, we present a procedure to obtain the lidar ratio at 532 nm by a combined Sunphotometer– aerosol-model inversion, where the viability of the solution is largely reinf…
Jóvenes migrantes al habla: trayectorias educativas y vidas con género
2018
El artículo muestra la tensión biográfica y el proceso educativo de dos jóvenes menores que viajaron de África a Europa a través de construcciones biográficas marcadas por el paso de sociedad de origen a sociedad de destino. El relato y la representación gráfica de la trayectoria vivida aportan elementos de reflexión sobre el encauzamiento del alumnado de incorporación tardía en nuestra sociedad. Ambas biografías se extraen de una investigación que tiene por objeto conocer qué hace posible la progresión educativa exitosa del alumnado de incorporación tardía que vive en contextos vulnerables. A través de trayectorias encauzadas por el género y una clase social de origen media, Badra y Dakar …
On the enhancement of diffusion by chaos, escape rates and stochastic instability
1999
We consider stochastic perturbations of expanding maps of the interval where the noise can project the trajectory outside the interval. We estimate the escape rate as a function of the amplitude of the noise and compare it with the purely diffusive case. This is done under a technical hypothesis which corresponds to stability of the absolutely continuous invariant measure against small perturbations of the map. We also discuss in detail a case of instability and show how stability can be recovered by considering another invariant measure.
La préprofessionnalisation Les élèves de CAP : quelles modifications des trajectoires scolaires en 20 ans ?aux métiers de l’enseignement : un disposi…
2022
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