High-precision abundances of elements have been derived from HARPS-N spectra of F and G main-sequence stars having ages determined from oscillation frequencies delivered by the Kepler mission. The tight relations between abundance ratios of refractory elements, e.g., [Mg/Fe] and [Y/Mg], and stellar age previously found for solar twin stars are confirmed. These relations provide new information on nucleosynthesis and Galactic evolution. Abundance ratios between volatile and refractory elements, e.g., [C/Fe] and [O/Fe], show on the other hand a significant scatter at a given age, which may be related to planet-star interactions. This is a potential problem for chemical tagging studies.

We derive the mixture of odd to even barium isotopes in the atmosphere of the metal-poor subgiant HD140283 from the analysis of the Ba ii transition at 4554 Å in a high-resolution high signal-to-noise spectrum of the star. The detailed shape of this spectral line depends on the relative contributions of odd and even isotopes via isotopic and hyperfine splitting. We measure the fractional abundance of odd Ba isotopes by modelling the formation of the Ba ii 4554-Å line profile with the use of both a classical 1D hydrostatic and a 3D hydrodynamical model atmosphere of HD140283. We interpret the results in terms of contributions by the slow (s) and rapid (r) neutron-capture processes to the isotopic mix. While the result of the 1D analysis of the Ba ii feature indicates a 64 ± 36% contribution of the r-process to the isotopic mix, the 3D analysis points toward a mere 15 ± 34% contribution from this process, that is consistent with a solar-like mixture of barium isotopes.

Theoretical atmosphere models provide the basis for a variety of applications in astronomy. In simplified one-dimensional (1D) atmosphere models, convection is usually treated with the mixing length theory despite its well-known insufficiency, therefore, the superadiabatic regime is poorly rendered. Due to the increasing computational power over the last decades, we are now capable to compute large grids of realistic three-dimensional (3D) hydrodynamical model atmospheres with the realistic treatment of the radiative transfer. We have computed the Stagger-grid, a comprehensive grid of 3D atmosphere models for late-type stars. In the presented contribution, we discuss initial results of the grid by exploring global properties and mean stratifications of the 3D models. Furthermore, we also depict the differences to classic 1D atmosphere models.

We study the number of visits to balls Br(x), up to time t/μ(Br(x)), for a class of non-uniformly hyperbolic dynamical systems, where μ is the Sinai–Ruelle–Bowen measure. Outside a set of ‘bad’ centers x, we prove that this number is approximately Poissonnian with a controlled error term. In particular, when r→0, we get convergence to the Poisson law for a set of centers of μ-measure one. Our theorem applies for instance to the Hénon attractor and, more generally, to systems modelled by a Young tower whose return-time function has an exponential tail and with one-dimensional unstable manifolds. Along the way, we prove an abstract Poisson approximation result of independent interest.

Samples of AA 6061 alloy and Al 5N were anodized at constant potential conditions and sealed in distilled boiling water. Immersion tests in high purity water were also carried out on AA 6061 samples at open circuit potential. EIS measurements were then performed in order to investigate the properties of the oxides obtained.

For sealed anodic oxides on AA 6061 and Al 5N, EIS experimental data was useful to differentiate between the capacitances of the two layers present in the oxide, named the barrier and porous layers. EIS data obtained for oxide layers grown at open circuit potential in AA 6061 allowed estimating the capacitance of the barrier layer, which value was greater than the barrier layer capacitance present in anodic oxides.

For a map of the unit interval with an indifferent fixed point, we prove an upper bound for the variance of all observables of n variables, K:[0,1]n→ℝ, which are separately Lipschitz. The proof is based on coupling and decay of correlation properties of the map. We also present applications of this inequality to the almost-sure central limit theorem, the kernel density estimation, the empirical measure and the periodogram.

For a large class of expanding maps of the interval, we prove that partial sums of Lipschitz observables satisfy an almost-sure central limit theorem (ASCLT). In fact, we provide a rate of convergence in the Kantorovich distance. Maxima of partial sums are also shown to obey an ASCLT. The key tool is an exponential inequality recently obtained. Then we establish (optimal) almost-sure convergence rates for the supremum of moving averages of Lipschitz observables (Erdös–Rényi-type law). This is done by refining the usual large-deviations estimates available for expanding maps of the interval. We end up with an application to entropy estimation ASCLTs that refine the Shannon–McMillan–Breiman and Ornstein–Weiss theorems.