scholarly journals Core Stability and Core Selection in a Decentralized Labor Matching Market

Games ◽  
2016 ◽  
Vol 7 (2) ◽  
pp. 10 ◽  
Author(s):  
Heinrich Nax ◽  
Bary Pradelski
Keyword(s):  
Core Stability ◽  
Matching Market ◽  
Core Selection

scholarly journals Core and stellar mass functions in massive collapsing filaments

2019 ◽  
Vol 625 ◽  
pp. A82 ◽  
Author(s):  
Evangelia Ntormousi ◽  
Patrick Hennebelle
Keyword(s):  
Star Formation ◽  
Flux Ratio ◽  
Mass Function ◽  
Initial Mass Function ◽  
Core Stability ◽  
High Mass ◽  
Core Mass ◽  
Hydrodynamical Simulation ◽  
Core Selection ◽  
Mass Functions

Context. The connection between the prestellar core mass function (CMF) and the stellar initial mass function (IMF) lies at the heart of all star formation theories, but it is inherently observationally unreachable. Aims. In this paper we aim to elucidate the earliest phases of star formation with a series of high-resolution numerical simulations that include the formation of sinks from high-density clumps. In particular, we focus on the transition from cores to sink particles within a massive molecular filament, and work towards identifying the factors that determine the shape of the CMF and the IMF. Methods. We have compared the CMF and IMF between magnetized and unmagnetized simulations, and between different resolutions. In order to study the effect of core stability, we applied different selection criteria according to the virial parameter and the mass-to-flux ratio of the cores. Results. We find that, in all models, selecting cores based on their kinematic virial parameter tends to exclude collapsing objects, because they host high velocity dispersions. Selecting only the thermally unstable magnetized cores, we observe that their mass-to-flux ratio spans almost two orders of magnitude for a given mass. We also see that, when magnetic fields are included, the CMF peaks at higher core mass values with respect to a pure hydrodynamical simulation. Nonetheless, all models produce sink mass functions with a high-mass slope consistent with Salpeter. Finally, we examined the effects of resolution and find that, in these isothermal simulations, even models with very high dynamical range fail to converge in the mass function. Conclusions. Our main conclusion is that, although the resulting CMFs and IMFs have similar slopes in all simulations, the cores have slightly different sizes and kinematical properties when a magnetic field is included, and this affects their gravitational stability. Nonetheless, a core selection based on the mass-to-flux ratio is not enough to alter the shape of the CMF, if we do not take thermal stability into account. Finally, we conclude that extreme care should be given to resolution issues when studying sink formation with an isothermal equation of state, since with each increase in resolution, fragmentation continues to smaller scales in a self-similar way.

Foot core strengthening: relevance in injury prevention and rehabilitation for runners

2016 ◽  
Vol 64 (1) ◽  
Keyword(s):  
Injury Prevention ◽  
Lower Limb ◽  
Neuromuscular Electrical Stimulation ◽  
Plantar Fascia ◽  
Core Stability ◽  
Tibialis Posterior ◽  
Lower Limb Injury ◽  
Limb Injury ◽  
Plantar Fasciopathy ◽  
Intrinsic Foot Muscles

The human foot is a flexible structure characterized by a pronounced medial longitudinal arch (MLA) that compresses and recoils during running. That process is actively driven by the intrinsic foot muscles and requires a proper stability of the MLA. This introduces the concept of foot core stability. Because the intrinsic foot muscles are often neglected by clinicians and researchers, the purpose of this article is to provide some guidelines for incorporating foot core training in prevention or rehabilitation programmes for runners. The intrinsic foot muscles play a key role in postural control and maintain balance during single leg stance by controlling the height of the MLA and the foot pronation. During running, these muscles lengthen eccentrically during the absorption phase and subsequently shorten as the arch recoils during the propulsive phase, functioning in parallel to the plantar fascia. As a consequence, the dysfunction or weakness of the MLA active support may lead to injuries (e.g. plantar fasciopathy, Achilles or Tibialis posterior tendinopathy, metatarsalgia or medial tibial stress syndrome), due to numerous biomechanical cascades and mechanisms. In order to counteract or prevent these impairments, there are two ways for enhancing the foot core stability. Firstly in terms of volitional control of the intrinsic foot muscles, the “short foot exercise” must be practiced. Secondly strengthening sessions using neuromuscular electrical stimulation of these muscles seem to be a promising strategy in order to support the MLA and control the pronation during running. Practically, the foot core strengthening protocol may beneficiate not only the runners affected by excessive pronation related injuries but also those who sustained a long term lower limb injury and may be affected by a detraining process. In addition we warmly recommend integrating this protocol in any lower limb injury prevention programme or strength and conditioning plan for runners.

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