ANALYSIS OF THE REACTION FORCES DURING CIRCLES EXECUTION ON A GYMNASTIC MUSHROOM.

Men's gymnastics is comprised of six events, all of them produce loadings to the upper extremity but specifically, the pommel horse demands repetitive and high intensity wrist impacts on a rigid structure, with sustained periods of body weight support on the wrist (Marklof et al, 1989). In a study of elite male gymnasts (Mandelbaun et al., 1989) the pommel horse was the apparatus associated with the most wrist pain. Most of the gymnasts begin at a young age to do this sport, therefore their wrist growth plate is a zone with critical injury options. The purpose of this study was to measure the force applied by the gymnasts during the execution of circles on a mushroom apparatus used to improve techniques of the pommel horse

Resistencia de juntas secas conjugadas de puentes de dovelas prefabricadas de hormigón: propuesta para el Eurocódigo 2

This paper discusses a study on the performance of concretesegmental bridges with shear keys, focusing on theshear behaviour of castellated dry joints under ultimatelimit state conditions. The widely varying formulationused to evaluate joint shear strength were compiled,along with the experimental results published in the literatureon the subject. The various approaches were evaluatedby comparing their predictions of ultimate jointstrength to published empirical findings. The formulagiving the best prediction was adapted to the safety factorprovisions set out in Eurocode 2.Este trabajo presenta un estudio sobre el comportamientode puentes de dovelas de hormigon con llaves de cortante,centrado en el comportamiento a cortante de lasjuntas secas conjugadas en Estado Limite Ultimo. Se harealizado una exhaustiva recopilacion de la dispar formulacionexistente para evaluar la resistencia a cortante delas juntas. Se ha realizado, asimismo, una investigacionbibliografica de los resultados experimentales disponiblessobre este particular en la literatura. Los resultados recogidosen la bibliografia han sido comparados con la variadaformulacion existente para predecir la resistencia ultimade las juntas. La formula que mejor predice laresistencia ha sido identificada. Esta ha sido adaptada alformato de seguridad presente en el Eurocodigo 2

Heterohexamers Formed by CcmK3 and CcmK4 Increase the Complexity of Beta Carboxysome Shells.

Bacterial microcompartments (BMCs) encapsulate enzymes within a selectively permeable, proteinaceous shell. Carboxysomes are BMCs containing ribulose-1,5-bisphosphate carboxylase oxygenase and carbonic anhydrase that enhance carbon dioxide fixation. The carboxysome shell consists of three structurally characterized protein types, each named after the oligomer they form: BMC-H (hexamer), BMC-P (pentamer), and BMC-T (trimer). These three protein types form cyclic homooligomers with pores at the center of symmetry that enable metabolite transport across the shell. Carboxysome shells contain multiple BMC-H paralogs, each with distinctly conserved residues surrounding the pore, which are assumed to be associated with specific metabolites. We studied the regulation of β-carboxysome shell composition by investigating the BMC-H genes ccmK3 and ccmK4 situated in a locus remote from other carboxysome genes. We made single and double deletion mutants of ccmK3 and ccmK4 in Synechococcus elongatus PCC7942 and show that, unlike CcmK3, CcmK4 is necessary for optimal growth. In contrast to other CcmK proteins, CcmK3 does not form homohexamers; instead CcmK3 forms heterohexamers with CcmK4 with a 1:2 stoichiometry. The CcmK3-CcmK4 heterohexamers form stacked dodecamers in a pH-dependent manner. Our results indicate that CcmK3-CcmK4 heterohexamers potentially expand the range of permeability properties of metabolite channels in carboxysome shells. Moreover, the observed facultative formation of dodecamers in solution suggests that carboxysome shell permeability may be dynamically attenuated by "capping" facet-embedded hexamers with a second hexamer. Because β-carboxysomes are obligately expressed, heterohexamer formation and capping could provide a rapid and reversible means to alter metabolite flux across the shell in response to environmental/growth conditions

Tras los pasos de la Sílfide. Imaginarios españoles del ballet romántico a la danza moderna

La publicación que tiene la persona lectora entre sus manos realiza un recorrido de cien años de historia de la danza, un camino que toma como punto de partida la cultura visual del Romanticismo y que se ramifica fuera del ámbito geográfico de nuestro país, analizando los rasgos que definen y construyen la danza española y cómo estos se difundieron en los bailes en el extranjero.Las investigaciones contenidas en este libro son resultado del proyecto Tras los pasos de la Sílfide. Una historia de la danza en España, 1836-1936 (PGC2018-093710-A-I00)Peer reviewe