A nonparametric predictive alternative to the Imprecise Dirichlet Model: the case of a known number of categories

Nonparametric Predictive Inference (NPI) is a general methodology to learn from data in the absence of prior knowledge and without adding unjustified assumptions. This paper develops NPI for multinomial data where the total number of possible categories for the data is known. We present the general upper and lower probabilities and several of their properties. We also comment on differences between this NPI approach and corresponding inferences based on Walley's Imprecise Dirichlet Model

Aquí vienen las novias: leyendo las pinturas neolíticas de Uan Derbuaen (Tasili n’Ajer, Argelia)

The Tassil-n-Ajjer mountain range is well known for its phenomenal richness in rock-shelters and cave paintings. Generations of researchers have surveyed, mapped, drafted and discussed different facets of these Tassili paintings. The diversity and versatility of the paintings traditions of the Tassili make difficult any attempt at straightforward generalization, whether stylistic or thematic. Each painting’s station appears to be unique and conveys its own suggestions that have to be studied extensively and systematically. In the approach outlined in this paper –the iconographic approach–, paintings are viewed as complex sets of ‘artifacts’ arranged by the creative minds of the actual artists. How did these artists practice their crafts? What iconic elements did they choose to represent and why? How and why are these selected elements arranged and combined? These are some of the questions addressed in this paper. The new readings of the Uan Derbuaen paintings allow to suggest a staging and grand representation of matrimonial arrangements, the final travel of the brides.La cordillera montañosa del Tasili n’Ajer es bien conocida por su fenomenal riqueza en abrigos y cuevas pintados. Generaciones de investigadores han prospectado, cartografiado, dibujado y discutido diferentes facetas de estas pinturas del Tasili. La diversidad y versatilidad de las tradiciones pictóricas del Tasili hace difícil cualquier intento de generalización directa ya sea estilística o temática. Cada estación pintada parece ser única y expresiva de sugerencias propias que deben ser estudiadas extensa y sistemáticamente. En el enfoque esbozado en este artículo, un enfoque iconográfico, las pinturas son consideradas como series complejas de “artefactos” organizados por las mentes creativas de los artistas reales. ¿Cómo desarrollaban sus habilidades esos artistas? ¿Qué elementos icónicos escogieron para la representación y por qué? ¿Cómo y por qué esos elementos seleccionados se organizaron y combinaron? La nueva lectura de las pinturas de Uan Derbuaen permite sugerir una puesta en escena y una gran representación de los arreglos matrimoniales, el viaje final de las novias

Nonparametric predictive inference and interval probability

This paper presents the unique position of A(n)-based nonparametric predictive inference within the theory of interval probability. It provides a completely new understanding, leading to powerful new results and a well-founded justification of such inferences by proving strong internal consistency results

Sensitivity analysis of linear dynamical systems in uncertainty quantification

We consider linear dynamical systems including random parameters for uncertainty quantification. A sensitivity analysis of the stochastic model is applied to the input-output behaviour of the systems. Thus the parameters that contribute most to the variance are detected. Both intrusive and non-intrusive methods based on the polynomial chaos yield the required sensitivity coefficients. We use this approach to analyse a test example from electrical engineering

Arginina, óxido nítrico y función endotelial

Arginine is a semi-essential amino acid with major physiological functions. One of the most outstanding of such is itsrole as an amino acid precursor of nitric oxide, a molecule produced, in many tissues, from arginine by the nitric oxidesynthase enzyme. Within the vascular endothelium, nitric oxide behaves as a vasodilator, antiatherogenic, and anti-plaqueaggregation agent. The detailed study of this enzymatic reaction indicates that nitric oxide synthase presents high affinity,for its substrate, arginine, which is found in high concentrations in the endothelium. Consequently, it is surprising thatthe functionality of this enzyme is conditioned by variations in concentrations of arginine, produced by nutritional intake.This is known as «the arginine paradox». However, the existence of an endogenous nitric oxide synthase inhibitor,known as asymmetric dimethylarginine, has been recently demonstrated. This compound would decrease the formationof nitric oxide through competitive inhibition with the natural substrate, arginine. It is for this reason that dietarysupplementation with arginine would be important as a means to counteracting such an effect. In addition to arginine,there are other dietary components which may also influence the synthesis of nitric oxide by the vascular endothelium.La arginina es un aminoácido semiesencial con importantes funciones fisiológicas. Entre ellas destaca su papel comoprecursora del óxido nítrico, una molécula producida a partir de la arginina por la enzima óxido nítrico sintasa enmuchos tejidos y que en el endotelio vascular se comporta como vasodilatadora, antiaterogénica y antiagreganteplaquetaria. El estudio detallado de esta reacción enzimática indica que la óxido nítrico sintasa tiene una granafinidad por su sustrato, la arginina, que se encuentra en concentraciones altas en el endotelio. Por tanto, resultabasorprendente que el funcionamiento de esta enzima estuviera condicionado por las variaciones en las concentracionesde arginina debidas al aporte nutricional. A esto se le llamó «paradoja de la arginina». Sin embargo, se hademostrado recientemente la existencia de un inhibidor endógeno de la óxido nítrico sintasa denominado dimetilargininaasimétrica. Este compuesto disminuiría la formación del óxido nítrico por inhibición competitiva con el sustratonatural, la arginina. De ahí la importancia de la suplementación con arginina para contrarrestar este efecto. Ademásde la arginina, existen otros componentes de la dieta que pueden influir también en la síntesis de óxido nítrico porel endotelio vascular

Measurement of the Blackbody Radiation Shift of the 133Cs Hyperfine Transition in an Atomic Fountain

We used a Cs atomic fountain frequency standard to measure the Stark shift on the ground state hyperfine transiton frequency in cesium (9.2 GHz) due to the electric field generated by the blackbody radiation. The measures relative shift at 300 K is -1.43(11)e-14 and agrees with our theoretical evaluation -1.49(07)e-14. This value differs from the currently accepted one -1.69(04)e-14. The difference has a significant implication on the accuracy of frequency standards, in clocks comparison, and in a variety of high precision physics tests such as the time stability of fundamental constants.Comment: 4 pages, 2 figures, 2 table