Analysis of factors affecting length of competitive life of jumping horses

Official competition data were used to study the length of competitive life in jumping horses. The trait considered was the number of years of participation in jumping. Data included 42 393 male and gelded horses born after 1968. The competitive data were recorded from 1972 to 1991. Horses still alive in 1991 had a censored record (43% of records). The survival analysis was based on Cox’s proportional hazard model. The independent variables were year, age at record, level of performance in competition (these three first variables were time dependent), age at first competition, breed and a random sire effect. The prior density of the sire effect was a log gamma distribution. The maximization of the marginal likelihood of the γ parameter of the gamma density gave an estimate of the additive genetic variance. The baseline hazard, the fixed effects and the sire effects were then estimated simultaneously by maximizing their marginal posterior likelihood. Jumping horses were culled for either involuntary or voluntary reasons. The involuntary reasons included the management of the horse, for example, the earlier a horse starts competing the longer he lives. The voluntary reasons related to the jumping ability: the better a horse, the longer he lives (at a given time, an average horse is 1.6 times more likely to be culled than a good horse with a performance of one standard deviation above the mean). The heritability of functional stayability was 0.18. The difference in half-lives of the progeny of two extreme stallions exceeded 2 years.La durée de vie sportive des chevaux de concours hippique est analysée à partir des données des compétitions officielles. Le caractère étudié est le nombre d’années en compétition. Les données concernent 42 393 chevaux mâles et hongres nés depuis 1968 et enregistrés en compétition de 1972 à 1991. Les chevaux encore en compétition en 1991 se voient attribuer une donnée dite censurée (43 % des données). L’analyse de survie est basée sur le modèle de risque proportionnel de Cox. Les variables indépendantes sont l’année, l’âge au moment de l’enregistrement, l’âge à la première compétition, le niveau de performance en compétition, la race et un effet « père » aléatoire. La densité a priori de l’effet «père» est une distribution log gamma. La maximisation de la vraisemblance marginale du paramètre γ de la fonction de densité gamma permet une estimation de la variance génétique additive. La fonction de risque de base, les effets fixés et l’effet « père» ont été estimés de façon simultanée par la maximisation de leur vraisemblance marginale a posteriori. Les chevaux de concours hippique sont éliminés de la compétition soit pour raisons volontaires, soit pour raisons involontaires. Les premières sont dues aux circonstances (effet année) et à la valorisation : plus un cheval commence tôt la compétition, plus il y reste longtemps. Les secondes concernent l’aptitude du cheval au saut d’obstacles : meilleur est le cheval, plus longtemps il concourt (à un moment donné, un cheval moyen a 1,6 fois plus de chances d’être éliminé qu’un bon cheval de performance égale à un écart type au dessus de la moyenne). L’héritabilité de la longévité fonctionnelle est 0,18. La différence entre les demi-vies des descendants de deux étalons extrêmes dépasse 2 ans

The three skies of the Indo-Europeans

The paper aims to describe the approach that Indo-Europeans had about cosmogony and the structure of the sky. It especially relies on the Greek, Latin and Hurrian conceptions. It is shown that the Indo-European cosmogony envisions the sky as three layers: the Upper-Sky, the Middle-Sky and the Lower-Sky. The gods and celestial bodies in each sky are different and have specific roles, names, colors and attributes. An appendix at the end lists the words and roots discussed in the paper

A Formalism for Scattering of Complex Composite Structures. 2 Distributed Reference Points

Recently we developed a formalism for the scattering from linear and acyclic branched structures build of mutually non-interacting sub-units.{[}C. Svaneborg and J. S. Pedersen, J. Chem. Phys. 136, 104105 (2012){]} We assumed each sub-unit has reference points associated with it. These are well defined positions where sub-units can be linked together. In the present paper, we generalize the formalism to the case where each reference point can represent a distribution of potential link positions. We also present a generalized diagrammatic representation of the formalism. Scattering expressions required to model rods, polymers, loops, flat circular disks, rigid spheres and cylinders are derived. and we use them to illustrate the formalism by deriving the generic scattering expression for micelles and bottle brush structures and show how the scattering is affected by different choices of potential link positions.Comment: Paper no. 2 of a serie