Activation of the <i>gluteus maximus</i> during performance of the back squat, split squat and barbell hip thrust and the relationship with maximal sprinting

The purpose of this research was to compare muscle activation of the gluteus maximus and ground reaction force between the barbell hip thrust, back squat, and split squat and to determine the relationship between these outcomes and vertical and horizontal forces during maximal sprinting. Twelve male team sport athletes (age 25.0 ± 4.0 years, stature 184.1 ± 6.0 cm, body mass 82.2 ± 7.9 kg) performed separate movements of the three strength exercises at a load equivalent to their individual three repetition maximum. The ground reaction force was measured using force plates and the electromyography (EMG) activity of the upper and lower gluteus maximus was recorded in each leg and expressed as percentage of the maximum voluntary isometric contraction (MVIC). Participants then completed a single sprint on a non-motorized treadmill for the assessment of maximal velocity, horizontal and vertical forces. Although ground reaction force was lower, peak EMG activity in the gluteus maximus was higher in the hip thrust than the back squat (p = 0.024; 95%CI = 4 – 56%MVIC) and split squat (p = 0.016; 95%CI = 6 – 58%MVIC). Peak sprint velocity was correlated with both anterior-posterior horizontal force (r = 0.72) and peak ground reaction force during the barbell hip thrust (r = 0.69) but no other variables. The increased activation of gluteus maximus during the barbell hip thrust and the relationship with maximal running speed suggests that this movement may be optimal for training this muscle group in comparison to the back squat and split squat

Alien Registration- Morin, Yvonne L. (Saint Agatha, Aroostook County)

https://digitalmaine.com/alien_docs/33261/thumbnail.jp

Superparamagnetic behaviour of antiferromagnetic DyPO4 nanoparticles

We report on the low-temperature magnetic ac-susceptibility of antiferromagnetic DyPO4 nanoparticles with a very high surface to volume ratio. The results are interpreted in terms of superparamagnetic relaxation of the Neel vector arising from a relatively large number approx 0.2 Na of uncompensated spins probably existing on the surface of the nanoparticles. The activation energy of the relaxation process is found to be Ea / kB = (2.6+-0.1) K within a model taking into account the magnetic interaction between nanoparticles.Comment: 3 pages, 1 figure, Espcrc2, ICM0

Modelling stellar coronal magnetic fields

Our understanding of the structure and dynamics of stellar coronae has changed dramatically with the availability of surface maps of both star spots and also magnetic field vectors. Magnetic field extrapolations from these surface maps reveal surprising coronal structures for stars whose masses and hence internal structures and dynamo modes may be very different from that of the Sun. Crucial factors are the fraction of open magnetic flux (which determines the spin-down rate for the star as it ages) and the location and plasma density of closed-field regions, which determine the X-ray and radio emission properties. There has been recent progress in modelling stellar coronae, in particular the relative contributions of the field detected in the bright surface regions and the field that may be hidden in the dark star spots. For the Sun, the relationship between the field in the spots and the large scale field is well studied over the solar cycle. It appears, however, that other stars can show a very different relationship.Comment: 6pages, 4 figure

Cynocephalus in commentario? El carácter monstruoso o salvaje de los infieles como argumento jurídico

Desde hace unos años ha fructificado un tipo de acercamiento historiográfico a la relación cristianos-musulmanes, centrado en la percepción/construcción de la otredad. Ello se evidencia en distintos trabajos que se asientan en las "imágenes" medievales que representan al infiel en un contexto de franca hostilidad. Pero este enfoque puede ocultar la inscripción retórico-jurídica de la descripción del infiel en clave teratológica o salvaje. Lo que puede aparentar una referencia etnográfica que da pie a discurrir sobre el etnocentrismo cristiano medieval, puede en determinado contexto operar como un argumento jurídico que habilita un tipo u otro de justificación para la conquista sobre los no cristianos. Se plantea entonces la conveniencia de conjugar dos temáticas que la medievística ha desarrollado separadamente: la historia de los estereotipos cristianos de la "monstruosidad" sarracena y la del desarrollo jurídico medieval.For some years a type of historiographical approach has rendered fruits about the relation Christians-Muslims, focused on the perception/construction of alterity. This is evident in different works that analyze the medieval "images" of the unbelievers created in a hostile context. But this approach can ignore the rhetorical-juridical inscription of the description of the unbeliever in teratological or wild terms. What seems an ethnographic reference that says much about the medieval Christian ethnocentrism may in certain context operate as a juridical argument that enables one type or another of justification for the conquest on unchristians. We pose here the convenience of bringing together two subjects that medievalists had developed separately: the history of the Christian stereotypes of Saracen "monstrosity" and the history of medieval law

La négociation du temps de travail: l'emploi en jeu

International audiencePersistent high unemployment has established the labor relations system in France. Jobs have become an ever more important issue in negotiations about the time spent working. By combining legal and sociological analysis, it is shown that regulatory oversight has, since the 1980s, taken the place of a quite decentralized bargaining process that formed an exception to legal rules. Although jobs often stand at the top of the agenda in negotiations about work-time, it is less an actually targeted objective than a bargaining chip for working out agreements on other topics. The issue of jobs crops up in three types of situations. First of all, jobs may serve as a mere pretext for opening negotiations about the time spent working, Secondly, the jobs issue can also lead to solid commitments in exchange for measures allowing for more flexibility. Thirdly, it may be a formal objective for negotiators bargaining about work-time even though no party has any real interest in reaching such an objective. This diversity of cases and of forms of commitment raises question about the traditional principles of labor law.En France, la pérennité du chômage bouscule plus que jamais la dynamique du système de relations professionnelles. L'emploi est ainsi devenu un enjeu de plus en plus important dans les négociations sur le temps de travail. Croisant analyses juridiques et sociologiques, les auteurs montrent de ce point de vue qu'à un mode tutélaire de réglementation succède, depuis les années 1980, un mode négocié, largement décentralisé et dérogatoire aux règles légales. Par ailleurs, si l'emploi est souvent mis au premier plan dans les négociations sur le temps de travail, il ne l'est pas nécessairement comme un objectif à atteindre ; il est surtout utilisé comme une valeur arbitrage qui facilite la production d'autres types d 'arrangemen

Bio-inspired Tensegrity Soft Modular Robots

In this paper, we introduce a design principle to develop novel soft modular robots based on tensegrity structures and inspired by the cytoskeleton of living cells. We describe a novel strategy to realize tensegrity structures using planar manufacturing techniques, such as 3D printing. We use this strategy to develop icosahedron tensegrity structures with programmable variable stiffness that can deform in a three-dimensional space. We also describe a tendon-driven contraction mechanism to actively control the deformation of the tensegrity mod-ules. Finally, we validate the approach in a modular locomotory worm as a proof of concept.Comment: 12 pages, 7 figures, submitted to Living Machine conference 201