Microborings in mid Cretaceous fish teeth

Fish teeth and other remains from the British Cretaceous contain abundant evidence for post-mortem colonization by endolithic organisms. The borings are here recognised as occurring in three morphotypes, including a flask-shaped form not previously recorded. There is strong evidence to suggest that each of these boring types shows a strong preference for a particular substrate histology. The damage and destruction of vertebrate remains by microborings is here considered to exert a major taphonomic control on microvertebrate assemblages. The relationships between the intensity of colonization of vertebrate material by endolithic organisms and palaeoenvironment have implications for using these bone microborings as palaeoenvironmental indicators

Towards the understanding of vertical-axis wind turbines in double-rotor configuration

Vertical-axis wind turbines (VAWTs) in double-rotor configuration, meaning two rotors in close proximity, have the ability to enhance the power performance. In this study, we work towards the understanding of vertical-axis wind turbines in double-rotor configuration. Numerical simulations are performed to gain insight in the physics behind the double-rotor concept. Furthermore, a parametric study is performed to explore the effect of the double-rotor lay-out, rotor loading, rotor spacing and wind direction on the flow characteristics and the power generation.</p

Model for the on-site matrix elements of the tight-binding hamiltonian of a strained crystal: Application to silicon, germanium and their alloys

We discuss a model for the on-site matrix elements of the sp3d5s* tight-binding hamiltonian of a strained diamond or zinc-blende crystal or nanostructure. This model features on-site, off-diagonal couplings between the s, p and d orbitals, and is able to reproduce the effects of arbitrary strains on the band energies and effective masses in the full Brillouin zone. It introduces only a few additional parameters and is free from any ambiguities that might arise from the definition of the macroscopic strains as a function of the atomic positions. We apply this model to silicon, germanium and their alloys as an illustration. In particular, we make a detailed comparison of tight-binding and ab initio data on strained Si, Ge and SiGe.Comment: Submitted to Phys. Rev.

Estimation of genetic parameters of egg production traits of laying hens by restricted maximum likelihood applied to a multiple-trait reduced animal model

International audienc

A fundamental test of the Higgs Yukawa coupling at RHIC in A+A collisions

Searches for the intermediate boson, $W^{\pm}$, the heavy quantum of the Weak Interaction, via its semi-leptonic decay, $W\to e +\nu$, in the 1970's instead discovered unexpectedly large hadron production at high $p_T$, notably $\pi^0$, which provided a huge background of $e^{\pm}$ from internal and external conversions. Methods developed at the CERN ISR which led to the discovery of direct-single-$e^{\pm}$ in 1974, later determined to be from the semi-leptonic decay of charm which had not yet been discovered, were used by PHENIX at RHIC to make precision measurements of heavy quark production in p-p and Au+Au collisions, leading to the puzzle of apparent equal suppression of light and heavy quarks in the QGP. If the Higgs mechanism gives mass to gauge bosons but not to fermions, then a proposal that all 6 quarks are nearly massless in a QGP, which would resolve the puzzle, can not be excluded. This proposal can be tested with future measurements of heavy quark correlations in A+A collisionsComment: 12 pages, 16 figures, 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica WI, January 2-9, 2010. Corrected citation of 1974 direct single lepton discover

Nouveaux résultats d'estimation de l'héritabilité des gains en course des pur-sang en France

Le logarithme du gain annuel de 232 893 chevaux en plat et de 85 145 chevaux sur les obstacles ayant couru en France au galop de 1950 à 1990 a été analysé selon un modèle animal. La méthode REML a permis d’estimer les composantes de la variance sur un ensemble de sous-fichiers établis en fonction de cohortes d’année de naissance. En plat, sur les naissances de 1960 à 1987, l’héritabilité a augmenté d’une manière hautement significative linéairement de 0,22 à 0,28, tandis que la répétabilité des performances entre 2 et 3 ans connaissait une évolution très significative parallèle passant de 0,35 à 0,40. En obstacles sur les naissances de 1962 à 1965, à cause des à-coups dus à la moindre précision des estimations, on ne perçoit pas d’évolution significative de l’héritabilité (autour de 0,25). La répétabilité entre 4 et 5 ans augmente cependant significativement. Les raisons de l’évolution de ces paramètres au cours du temps sont discutées. On retiendra deux hypothèses : i) un apport de variabilité extérieure par l’intermédiaire du sang américain dans les origines françaises, qui pourrait expliquer la variation des paramètres. Cette hypothèse se heurte cependant à la grande proximité génétique des deux populations; ii) un jeu d’équilibre entre deux sources principales de création de déséquilibre de liaison que sont la sélection et l’homogamie, dont l’intensité observée dans chaque sous échantillon permet d’expliquer assez bien les variations observées des paramètres.Logarithms of yearly earnings of 232 893 horses in flat races and 85145 horses in steeplechases and hurdle races in France from 1950 to 1990 were analysed according to an animal model. REML methodology was applied to chronological subsamples of this enormous file to estimate genetic parameters. In flat races, from the birth year 1960 to 1987, heritability increased from 0.22 to 0.28 according to a statistically highly significant linear trend, and the repeatability between 2 and 3 years changed in a similary significant manner from 0.85 to 0.40. Over the jumps, from 1962 to 1985, fluctuations appeared probably due to a lower precision of the estimates and no significant evolution could be seen for heritability (near 0.25). Repeatability between 4 and 5 years, however, increased significantly. The reasons for the evolution of these parameters over time are discussed. Two main hypotheses are mentioned: (i) introduction of external genetic variability in French pedigrees through American blood (this hypothesis however is not in agreement with the very small genetic distance between the two populations); and (ii) an equilibrium between two opposite sources generating linkage disequilibrium, selection and assortative mating. The intensity of these two forces observed in each subsampLe allows us to explain fairly well the variations of observed parameters