Archaeobotanical investigations at the earliest horse herder site of Botai in Kazakhstan

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this recordThis paper presents new radiocarbon dates and the results of the first archaeobotanical investigations at Eneolithic Botai site, for the first time aiming to explore the plant food component in the diet of Botai population and if the inhabitants of the Botai were a part of an early crop food exchange network. Our excavation of a hut circle and associated radiocarbon dating placed its occupation within a date range commencing around 3550 and 3030 cal BC and ending between 3080 and 2670 cal BC. A separate feature (likely a stove or kiln), excavated in test trench E would seem to be younger, around 2000 cal BC. The dating of the site thus also indicates a previously unknown later occupation at Botai, opening further discussions on human subsistence and interaction as well as horse management in northern Eurasia from the Eneolithic to the Bronze Age. The archaeobotanical results, derived from systematic sampling and analysis of macrobotanical remains, plant phytoliths and molecular biomarker analysis show that the Botai populations were not part of any wider crop network. The relatively small seed count would indicate that plant foods did not constitute a substantial component of economic life. On the other hand, the presence of miliacin could suggest possible millet cultivation or consumption in this region at some point in the past, possibly after the main occupation period of Botai.European Research Council (ERC)National Science FoundationEuropean Union Horizon 202

Energy Transfer and Spectra in Simulations of Two-dimensional Compressible Turbulence

We present results of high-resolution numerical simulations of compressible 2D turbulence forced at intermediate spatial scales with a solenoidal white-in-time external acceleration. A case with an isothermal equation of state, low energy injection rate, and turbulent Mach number $M\approx0.34$ without energy condensate is studied in detail. Analysis of energy spectra and fluxes shows that the classical dual-cascade picture familiar from the incompressible case is substantially modified by compressibility effects. While the small-scale direct enstrophy cascade remains largely intact, a large-scale energy flux loop forms with the direct acoustic energy cascade compensating for the inverse transfer of solenoidal kinetic energy. At small scales, the direct enstrophy and acoustic energy cascades are fully decoupled at small Mach numbers and hence the corresponding spectral energy slopes comply with theoretical predictions, as expected. At large scales, dispersion of acoustic waves on vortices softens the dilatational velocity spectrum, while the pseudo-sound component of the potential energy associated with coherent vortices steepens the potential energy spectrum.Comment: 10 pages, 6 figures. To appear in: Turbulence in Complex Conditions, Proc. Euromech/Ercoftac Colloquium 589, ed. M. Gorokhovski, Springer, 201

f(R) theories

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe