Het archeologisch project in de binnendelta van de Niger en het nut van ontwikkelingssamenwerking op sociaal-cultureel gebied

In Europe archeology often has been connected with regionalist or nationalistic interested movements. In some cases archeology thus landed in very risky fairways and in this case it certainly did not promote the development to an independent science with proper theoretical basis. In Africa this is different. Directly after the independence the first president of Mali, Modibo Keita, has sent some promising new-coming students to Europe to study historic sciences, also archeology. In that new country, of which the borders sometime had been drawn by French offices, tribes lived together who often possessed little affinity to one another. To the average inhabitant the identity as Malinesian hardly counted as opposed to the identity as member of a certain section of the population. Keita's intention was to stimulate the interest in the common past of the empires Ghana, Mali, the Songhai and the Bambara. He realized that for the development of the country a common consciousness of the Malinesian identity could not be missed. Generally speaking this thought has found acceptance at the Malinesian intelligentsia. There the interest in the own past is strongly alive. From this thought the Institute des Sciences Humaines at Bamako has started a project to take stock of the numerous old hills of settlement in the inner delta of the Niger, from an economic and demographic point of view forming the most important area in the empire of the rich. The project has been financed by D.G.I.S. and is being executed in co-operation with Dutch archeologists

Short communication Increase in metal extractability after liming of sacrificial sewage sludge disposal soils

A sandy and a sandy clay-loam soil from two dedicated (sacrificial) sewage sludge disposal sites were incubated with a total lime equivalent of 45 Mg·ha-1. Both these soils were acidified (pH 4.0 to 4.2) and had a significant accumulation of organic material (organic C of 2.9 to 3.7 %) compared to non-polluted soils (organic C of 0.6 to 1.0 %). The limed soils did not attain the desired pH of 6.5 after 6 months\' incubation due to a high buffer capacity. After incubation, soil samples were taken from the incubated pots and the levels of Al, Fe, Mn, Cu, Zn, Pb and Cd were determined by atomic absorption spectrophotometry (AAS) after extraction with NH4-EDTA and BaCl2. Most of the metals extracted with BaCl2 (except Mn in the sandy soil and Cd in both soils) decreased after liming. The EDTA-extractable Mn, Fe, and Cd in both soils and Cu and Pb in the sandy clayloam soil increased after liming, whereas Al and Zn, decreased in extractability (Statistically significant differences could not be determined for the trial due to the trial not having been designed for the results that were obtained). Similar results were reported in the literature for EDTA metal extraction but the phenomenon was not elaborated upon, except for Cr. The increased extractability of some of the metals after liming could negatively influence the use of EDTA as an extracting agent in proposed heavy-metal guidelines for similar sacrificial soils. Should liming be considered as a strategy to decrease metal mobility in sacrificial soils, the observed increase in extractability becomes a cause for concern and should receive attention in further research. Water SA Vol. 31 (2) 2005: pp.271-27

Microscopic theory for interface fluctuations in binary liquid mixtures

Thermally excited capillary waves at fluid interfaces in binary liquid mixtures exhibit simultaneously both density and composition fluctuations. Based on a density functional theory for inhomogeneous binary liquid mixtures we derive an effective wavelength dependent Hamiltonian for fluid interfaces in these systems beyond the standard capillary-wave model. Explicit expressions are obtained for the surface tension, the bending rigidities, and the coupling constants of compositional capillary waves in terms of the profiles of the two number densities characterizing the mixture. These results lead to predictions for grazing-incidence x-ray scattering experiments at such interfaces.Comment: 23 pages, 11 figure

Density functional theory of inhomogeneous liquids. I. The liquid-vapor interface in Lennard-Jones fluids

A simple model is proposed for the direct correlation function (DCF) for simple fluids consisting of a hard-core contribution, a simple parametrized core correction, and a mean-field tail. The model requires as input only the free energy of the homogeneous fluid, obtained, e.g., from thermodynamic perturbation theory. Comparison to the DCF obtained from simulation of a Lennard-Jones fluid shows this to be a surprisingly good approximation for a wide range of densities. The model is used to construct a density functional theory for inhomogeneous fluids which is applied to the problem of calculating the surface tension of the liquid-vapor interface. The numerical values found are in good agreement with simulation