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

Disjoining Potential and Spreading of Thin Liquid Layers in the Diffuse Interface Model Coupled to Hydrodynamics

The hydrodynamic phase field model is applied to the problem of film spreading on a solid surface. The disjoining potential, responsible for modification of the fluid properties near a three-phase contact line, is computed from the solvability conditions of the density field equation with appropriate boundary conditions imposed on the solid support. The equation describing the motion of a spreading film are derived in the lubrication approximation. In the case of quasi-equilibrium spreading, is shown that the correct sharp-interface limit is obtained, and sample solutions are obtained by numerical integration. It is further shown that evaporation or condensation may strongly affect the dynamics near the contact line, and accounting for kinetic retardation of the interphase transport is necessary to build up a consistent theory.Comment: 14 pages, 5 figures, to appear in PR

Critical phenomena: 150 years since Cagniard de la Tour

Critical phenomena were discovered by Cagniard de la Tour in 1822, who died 150 years ago. In order to mark this anniversary, the context and the early history of his discovery is reviewed. We then follow with a brief sketch of the history of critical phenomena, indicating the main lines of development until the present date. Os fen\'omenos cr\'{\i}ticos foram descobertos pelo Cagniard de la Tour em Paris em 1822. Para comemorar os 150 anos da sua morte, o contexto e a hist\'oria initial da sua descoberta \'e contada. Conseguimos com uma descri\c{c}\~ao breve da hist\'oria dos fen\'emenos cr\'{\i}ticos, indicando as linhas principais do desenvolvimento at\'e o presente.Comment: Latex2e, 8 pp, 3 eps figures include

A new approach for the limit to tree height using a liquid nanolayer model

Liquids in contact with solids are submitted to intermolecular forces inferring density gradients at the walls. The van der Waals forces make liquid heterogeneous, the stress tensor is not any more spherical as in homogeneous bulks and it is possible to obtain stable thin liquid films wetting vertical walls up to altitudes that incompressible fluid models are not forecasting. Application to micro tubes of xylem enables to understand why the ascent of sap is possible for very high trees like sequoias or giant eucalyptus.Comment: In the conclusion is a complementary comment to the Continuum Mechanics and Thermodynamics paper. 21 pages, 4 figures. Continuum Mechanics and Thermodynamics 20, 5 (2008) to appea

Microscopic View on Short-Range Wetting at the Free Surface of the Binary Metallic Liquid Gallium-Bismuth: An X-ray Reflectivity and Square Gradient Theory Study

We present an x-ray reflectivity study of wetting at the free surface of the binary liquid metal gallium-bismuth (Ga-Bi) in the region where the bulk phase separates into Bi-rich and Ga-rich liquid phases. The measurements reveal the evolution of the microscopic structure of wetting films of the Bi-rich, low-surface-tension phase along different paths in the bulk phase diagram. A balance between the surface potential preferring the Bi-rich phase and the gravitational potential which favors the Ga-rich phase at the surface pins the interface of the two demixed liquid metallic phases close to the free surface. This enables us to resolve it on an Angstrom level and to apply a mean-field, square gradient model extended by thermally activated capillary waves as dominant thermal fluctuations. The sole free parameter of the gradient model, i.e. the so-called influence parameter, $\kappa$, is determined from our measurements. Relying on a calculation of the liquid/liquid interfacial tension that makes it possible to distinguish between intrinsic and capillary wave contributions to the interfacial structure we estimate that fluctuations affect the observed short-range, complete wetting phenomena only marginally. A critical wetting transition that should be sensitive to thermal fluctuations seems to be absent in this binary metallic alloy.Comment: RevTex4, twocolumn, 15 pages, 10 figure

Physically Similar Systems - A History of the Concept

PreprintThe concept of similar systems arose in physics, and appears to have originated with Newton in the seventeenth century. This chapter provides a critical history of the concept of physically similar systems, the twentieth century concept into which it developed. The concept was used in the nineteenth century in various fields of engineering (Froude, Bertrand, Reech), theoretical physics (van der Waals, Onnes, Lorentz, Maxwell, Boltzmann) and theoretical and experimental hydrodynamics (Stokes, Helmholtz, Reynolds, Prandtl, Rayleigh). In 1914, it was articulated in terms of ideas developed in the eighteenth century and used in nineteenth century mathematics and mechanics: equations, functions and dimensional analysis. The terminology physically similar systems was proposed for this new characterization of similar systems by the physicist Edgar Buckingham. Related work by Vaschy, Bertrand, and Riabouchinsky had appeared by then. The concept is very powerful in studying physical phenomena both theoretically and experimentally. As it is not currently part of the core curricula of STEM disciplines or philosophy of science, it is not as well known as it ought to be

De kolonisatie van het terpengebied : een ethno-archeologische benadering

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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

De geschiedenis van de archeologie

Wetensch. publicatieFaculty of Archeolog