Units of relativistic time scales and associated quantities

This note suggests nomenclature for dealing with the units of various astronomical quantities that are used with the relativistic time scales TT, TDB, TCB and TCG. It is suggested to avoid wordings like "TDB units" and "TT units" and avoid contrasting them to "SI units". The quantities intended for use with TCG, TCB, TT or TDB should be called "TCG-compatible", "TCB-compatible", "TT-compatible" or "TDB-compatible", respectively. The names of the units second and meter for numerical values of all these quantities should be used with out any adjectives. This suggestion comes from a special discussion forum created within IAU Commission 52 "Relativity in Fundamental Astronomy"

Genus expansion for real Wishart matrices

We present an exact formula for moments and cumulants of several real compound Wishart matrices in terms of an Euler characteristic expansion, similar to the genus expansion for complex random matrices. We consider their asymptotic values in the large matrix limit: as in a genus expansion, the terms which survive in the large matrix limit are those with the greatest Euler characteristic, that is, either spheres or collections of spheres. This topological construction motivates an algebraic expression for the moments and cumulants in terms of the symmetric group. We examine the combinatorial properties distinguishing the leading order terms. By considering higher cumulants, we give a central limit-type theorem for the asymptotic distribution around the expected value

A First Assessment of the Corrections for the Consistency of the IAU2000 and IAU2006 Precession-Nutation Models

The Earth precession-nutation model endorsed by resolutions of each the International Astronomical Union and the International Union of Geodesy and Geophysics is composed of two theories developed independently, namely IAU2006 precession and IAU2000A nutation. The IAU2006 precession was adopted to supersede the precession part of the IAU 2000A precession-nutation model and tried to get the new precession theory dynamically consistent with the IAU2000A nutation. However, full consistency was not reached, and slight adjustments of the IAU2000A nutation amplitudes at the micro arcsecond level were required to ensure consistency. The first set of formulae for these corrections derived by Capitaine et al. (Astrophys 432(1):355–367, 2005), which was not included in IAU2006 but provided in some standards and software for computing nutations. Later, Escapa et al. showed that a few additional terms of the same order of magnitude have to be added to the 2005 expressions to get complete dynamical consistency between the official precession and nutation models. In 2018 Escapa and Capitaine made a joint review of the problem and proposed three alternative ways of nutation model and its parameters to achieve consistency to certain different extents, although no estimation of their respective effects could be worked out to illustrate the proposals. Here we present some preliminary results on the assessment of the effects of each of the three sets of corrections suggested by Escapa and Capitaine (Proceedings of the Journées, des Systémes de Référence et de la Rotation Terrestre: Furthering our Knowledge of Earth Rotation, Alicante, 2018) by testing them in conjunction with the conventional celestial pole offsets given in the IERS EOP14C04 time series.The four first authors were partially supported by Spanish Project AYA2016-79775-P (AEI/FEDER, UE)

Utilisation de l'urée pour l'alimentation des veaux au sevrage

A Madagascar, au Centre de Kianjasoa, 66 jeunes bovins (3/4 brahma X 1/4 Zébu Malgache) ont été alimentés durant leur sevrage avec une ration à base de foin, donné à volonté, et additionné d'urée. Les résultats pondéraux ainsi que les bilans nutritionnel et économique sont donnés et discutés. L'effet favorable de l'urée dans une alimentation des veaux à base de foin s'est vu entièrement confirmé

Expérience d'embouche des porcs avec mise au pâturage

Deux expériences semblables, une en saison sèche et une en saison des pluies, ont été effectuées pour évaluer l'économie d'aliment concentré qui peut être réalisée en mettant sur du pâturage les porcs à l'engrais, entre les poids de 50 et 100 kg. Trois traitements alimentaires ont été appliqués à savoir : la stabulation permanente habituelle, la sortie sur pâturage artificiel et la sortie sur pâturage naturel. Les principaux résultats sont les suivants: Le pâturage naturel abaisse l'indice de consommation du concentré de 0,3 unité environ, et le pâturage artificiel de 0,4 unité réalisant une économie de 15 kg et 20 kg respectivement de concentré pour engraisser les porcs du poids de 50 à 100 k

Fluctuations of Matrix Entries of Regular Functions of Wigner Matrices

We study the fluctuations of the matrix entries of regular functions of Wigner random matrices in the limit when the matrix size goes to infinity. In the case of the Gaussian ensembles (GOE and GUE) this problem was considered by A.Lytova and L.Pastur in J. Stat. Phys., v.134, 147-159 (2009). Our results are valid provided the off-diagonal matrix entries have finite fourth moment, the diagonal matrix entries have finite second moment, and the test functions have four continuous derivatives in a neighborhood of the support of the Wigner semicircle law.Comment: minor corrections; the manuscript will appear in the Journal of Statistical Physic

Le croisement Brahman à Madagascar

On compare dans les différentes régions malgaches, la productivité des zébus malgaches avec celle de métis (zebus malgaches x zebus brahman du Texas). Fécondité égale a celle de la race locale et faible pathologie, confirment la rusticité du Brahman. La croissance est améliorée ainsi que le rendement en carcasse et les qualités organoleptiques. La climatologie est corrélée avec les performances en élevage intensif ce qui permet de prévoir les résultats avant implantation. Le croisement Brahman est à conseiller dans les zones de développement rura