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El artículo discurre sobre los juegos de pelota en las civilizaciones indígenas en Teotihuacan, México.

This paper looks at the gigantic turn experienced by Francis Xavier: from university student to universal man. He came to the Sorbonne University with the intention of becoming a scholar and to prepare himself for a career, probably an ecclesiastical one, desiring to recover the fame of his name and the honor of his family, humiliated by the defeat and the loss of autonomy of the Kingdom of Navarre. His open-minded character, his brilliant intelligence, his passionate personality gave a strong impulse to his project. Ignatius of Loyola came across his life, who progressively opened his mind to more universal horizons and kindled his heart with the ideal of following Christ through a total identification with him. Xavier directed the whole strength of his being, through the experience of the Exercises, and especially through the meditation of the Eternal King, to the conquest of the most remote, most different, most forgotten peoples for the Gospel. He opened to the Church the cultures of the East and died exhausted by this immense endeavor. [ABSTRACT FROM AUTHOR]

We present the working prototype of a levitation system designed for investigation of flows in cryogenic helium fluids. The current device allows the levitation of a superconducting sphere and has several provisions made for allowing precise control over its motion. We report on progress in the detection and control systems of the prototype and demonstrate how uniform circular motion can be implemented. [ABSTRACT FROM AUTHOR]

Abstract: Correlation between transport properties and free volume has been widely evidenced by several authors. We are showing through a positron annihilation study in a high barrier polymer that transport properties can be improved by means of antiplasticizers addition. We also are verifying in this paper the influence of both free volume hole size and free fractional volume in diffusion of gases, finding a relationship with solubility too. [Copyright &y& Elsevier]

In order to modify the transport properties of the amorphous polyamide Trogamid-T™, several additives with structural characteristics that produce antiplasticization have been tested. Positron annihilation lifetime spectroscopy (PALS) has been used to determine both the size of free volume holes and the number of holes (free fractional free volume). Polyvinyl phenol (PVPh), 1,5 dihydroxy naphthalene (Ndiol) and a hexafluorinated Bisphenol A (HFBA) were chosen according to the results of a preliminary study based on density and PALS measurements with 15% of additive blends. Their blends with Trogamid show different behaviours: HFBA behaves clearly as a plasticizer while the polyvinyl phenol acts as an antiplasticizer. Ndiol has a more special effect: blend densities are greater than additive whereas the hole size decreases. [Copyright &y& Elsevier]

Molecular mass and temperature dependences of the polymer–solvent interaction parameter have been investigated in the extreme interval of high polymer concentration using inverse gas chromatography (IGC). The observed molecular mass dependence has been compared with the predictions of a theoretical model, which emphasises the role of intramolecular contacts in the polymer chain. The model reproduces reasonably well the molecular mass dependence. However, enthalpic and entropic contributions of the interaction parameter, obtained from IGC measurements at different temperatures, exhibit behaviours difficult to explain in the framework of the current models. [ABSTRACT FROM AUTHOR]

Abstract: Modification of transport properties of an amorphous polyamide, poly(trymethylhexamethylene terephtalamide) by addition of a nanosilicate, montmorillonite has been studied. For this proposal, carbon dioxide, water vapor and oxygen have been investigated in different sorption and permeability devices. Transport properties have also been related to the structural features. X-ray diffraction and transmission electron microscopy have provided the morphological analysis as well as the positron annihilation lifetime spectroscopy has given the free volume characterization. [Copyright &y& Elsevier]

Abstract: The miscibility behaviour of blends of poly(styrene-co-methacrylic acide) (PSMA-12) containing 12% of methacrylic acid with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at five different compositions has been studied by inverse gas chromatography (IGC). The adequacy of two types of solvents (solvents and precipitants) has been tested in order to detect the glass transition temperature, T g. A single T g has been observed in PSMA-12/PPO blends containing less than 67wt% of PPO. Two glass transition temperatures appeared, however, in blends containing higher PPO content. The polymer–polymer interaction parameters have been calculated in the molten state (260–280°C), their values being in good agreement with the observed phase behaviour. Moreover, the methods proposed by Farooque–Deshpande and Huang for obtaining the true polymer–polymer interaction parameters have been compared. Finally, the ability of IGC in order to determine T gs has been extended to a ternary system, PSMA-12/PPO/EMV4P-8 poly(ethylmethacrylate-co-4-vinylpyridine) which, depending on the composition, gives a single, two and even three T gs. [Copyright &y& Elsevier]