The Lower Danube Basin is one of the most important loess regions from Europe, which have provided excellent archives for long-term high-resolution palaeoclimate studies. The aim of this paper is to derive new information on the Middle–Late Pleistocene palaeoenvironment from a high resolution multiproxy assessment of the iron mineralogical composition at the Costines¸ti loess-palaeosol sequ…

We investigate the effects of triple-α and 12C(α, γ )16O reaction rates on the production of supernova yields for a massive star of 25 M. We combine the reaction rates to examine the rate dependence, where the rates are considered to cover the possible variation of the rates based on experiments on the earth and on theory. We adopt four combinations of the reaction rates from tw…

Tahun Terbit

2009

We introduce the Complex-Step-Finite-Difference method (CSFDM) as a generalization of the well-known Finite-Difference method (FDM) for solving the acoustic and elastic wave equations. We have found a direct relationship between modelling the second-order wave equation by the FDM and the first-order wave equation by the CSFDM in 1-D, 2-D and 3-D acoustic media. We present the numerical methodol…

We investigate the consequences of natural conjectures of Montgomery type on the non-vanishing of Dirichlet L-functions at the central point. We first justify these conjectures using probabilistic arguments. We then show using a result of Bombieri, Friedlander and Iwaniec, and a result of the author that they imply that almost all Dirichlet L-functions do not vanish at the central point. We al…

We present a strategy to thoroughly investigate the effects of prominent topography on the surface tilt due to a spherical pressure source.We use Etna’s topography as a case of study and, for different source positions, we compare the tilt fields calculated through (i) a 3-D boundary element method and (ii) analytical half-space solutions. We systematically determine (i) the source positions …

For the first time, a deep seismic data set acquired in the frame of the Algerian–French SPIRAL program provides new insights regarding the origin of the westernmost Algerian margin and basin. We performed a tomographic inversion of traveltimes along a 100-km-long wide-angle seismic profile shot over 40 ocean bottom seismometers offshore Mostaganem (Northwestern Algeria). The resu…

Fishes are well known for their remarkable maneuverability and agility. Less visible is the continuous control of stability essential for the exploitation of the full range of aquatic resources. Perturbations to posture and trajectory arise from hydrostatic and hydrodynamic forces centered in a fish (intrinsic) and from the environment (extrinsic). Hydrostatic instabilities arise from vertical …

In this article, we examine the relationship between primary school fees and education quality and access over the past forty years in seven sub-Saharan African countries. School fees were introduced as a means for revenue-constrained governments to fund the improvement and expansion of primary education. Recently there has been a move towards their abolition. We find that the introduction of f…

Tahun Terbit

2010