Activation Of Different Modes Research Articles

Working memory capacity does not always promote dual-task motor performance: The case of juggling in soccer.

The aim of this research was to refine our understanding of the role of working memory capacity (WMC) on motor performances that require attentional control in dual-task situations. Three studies were carried out on soccer players. Each participant had to perform a juggling task in both normal and dual-task conditions. In Study 1, the interfering task was a mental calculation test performed under time pressure (strong cognitive load). In Study 2, the interfering task was a count-down test (low cognitive load). In Study 3 an intra-individual design in which participants perform dual-tasks increasingly complex has been proposed. Results showed a positive relationship between participants' WMC and their dual-task motor performance when the cognitive load was low and a negative relationship when the cognitive load was high. This paper highlights the role of the WMC in the activation of different modes of processing and its importance on the performance in dual-task.

Solid Flow Regimes Within Dry Sliding Contacts

In this paper, we investigate the regimes of velocity accommodation and of load transmission within a dry sliding interface, in the presence of a solid and discontinuous interfacial layer (the so-called third body). To that end, an appropriate numerical framework called the multibody meshfree approach is used to implement a local model of such an interface, and a comprehensive dimensionless parametric study is performed in order to analyse the influence of the mechanical properties of the third body on the interfacial solid flow regimes, on the friction coefficient, and on the modes of energy dissipation. To that end, the concept of partial coefficient of friction is introduced. The numerical results demonstrate that the friction in the interface is limited by changes in the kinematics of the shear accommodation in the third-body layer and by the activation of different modes of energy dissipation (related either to surface area creation/destruction in the third-body layer or to bulk deformation of the solid matter composing it) which are uncorrelated in the parametric space of the mechanical properties of the third-body particles.

Shear band propagation in honeycombs: numerical and experimental

PurposeHexagonal honeycombs with meso-metric cell size show excellent load bearing and energy absorption potential, which make them attractive in many applications. However, owing to their bend-dominated structure, honeycombs are susceptible to deformation localization. The purpose of this study is to provide insight about shear band propagation in struts of 3D-printed honeycombs and its relation to the achieved macroscopic mechanical behavior.Design/methodology/approachHexagonal honeycombs and unit cell models are 3D-printed by fused deposition modeling (FDM). The samples are exposed to compression loading and digital image correlation technique and finite element analyses are incorporated.FindingsIt is found that the strain contours, which are obtained by finite element, are in agreement with experimental measurements made by DIC. In addition, three stages of shear band propagation in struts of 3D-printed honeycombs are illustrated. Then the correlation between shear band propagation stages and the achieved macroscopic mechanical responses is discussed in detail.Originality/valueFor the first time, a hierarchical activation of different modes of shear band propagation in struts of a 3D-printed honeycomb is reported. This information can be of use for designing a new generation of honeycombs with tailor-made localization and energy absorption potential.

Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Activation in Somatodendritic Compartments: Roles of Action Potentials, Frequency, and Mode of Calcium Entry

Mitogen-activated protein kinase (MAPK) has been identified as a potential element in regulating excitability, long-term potentiation (LTP), and gene expression in hippocampal neurons. The objective of the present study was to determine whether the pattern and intensity of synaptic activity could differentially regulate MAPK phosphorylation via selective activation of different modes of calcium influx into CA1 pyramidal neurons. An antibody specific for the phosphorylated (active) form of MAPK was used to stain sections from hippocampal slices, which were first stimulated in vitro. LTP-inducing stimulation [theta-burst (TBS) and 100 Hz] was effective in inducing intense staining in both dendritic and somatic compartments of CA1 neurons. Phosphorylation of MAPK was also induced, however, with stimulation frequencies (3-10 Hz) not typically effective in inducing LTP. Intensity and extent of staining was better correlated with the spread of population spikes across the CA1 subfield than with frequency (above 3 Hz). Experiments using inhibitors of NMDA receptors and voltage-sensitive calcium channels (VSCCs) revealed that, although MAPK is activated after both TBS and 5 Hz stimulation, the relative contribution of calcium through L-type calcium channels differs. Blockade of NMDA receptors alone was sufficient to prevent MAPK phosphorylation in response to 5 Hz stimulation, whereas inhibitors of both NMDA receptors and VSCCs were necessary for inhibition of the TBS-induced staining. We conclude that the intensity and frequency of synaptic input to CA1 hippocampal neurons are critically involved in determining the path by which second-messenger cascades are activated to activate MAPK.