An exfoliated fragment of a rock painting from Lesotho was analyzed by differentiated backscatter spectrometry to obtain the paint thickness, which ranged from about 2 to 6.5 m, and its empirical formula for stopping power calculations. Elemental composition was determined by PIXE. Fe-rich paint spots were red in color and Ca-rich ones, pinkish. Because of the chemical mobility of calcium, this paint component should become the focus to which conservation techniques should be directed.
Authors:M. Peisach, C. Pineda, L. Jacobson and J. Loubser
Potsherds from north and south of the Soutpansberg mountain range in Transvaal were analyzed by PIXE to establish possible trade patterns between the two regions, over the last thousand years. Correspondence analysis based on the content of 12 elements made it possible to distinguish pottery from the two regions, irrespective of where they were found. A model combining elemental and stylistic analysis was developed to explain both the physical movement of pots and the diffusion of ideas.
Authors:R. Faudree, R. Gould, M. Jacobson, L. Lesniak and T. Lindquester
It is known that if a 2-connected graphG of sufficiently large ordern satisfies the property that the union of the neighborhoods of each pair of vertices has cardinality at leastn/2, thenG is hamiltonian. In this paper, we obtain a similar generalization of Dirac’s Theorem forK(1,3)-free graphs. In particular, we show that ifG is a 2-connectedK(1,3)-free graph of ordern with the cardinality of the union of the neighborhoods of each pair of vertices at least (n+1)/3, thenG is hamiltonian. We also investigate several other related properties inK(1,3)-free graphs such as traceability, hamiltonian-connectedness, and pancyclicity.
Authors:M. Peisach, L. Jacobson, G. Boulle, D. Gihwala and L. Underhill
Data on the concentrations of K, Ca, Ti, Fe, Cu, Zn, Ga, Rb, Sr and Zr obtained by PIXE and of B, F, Na, Mg, Al, Si and Cu
obtained by proton-induced prompt gamma-ray spectrometry were used to characterize archaeological artefacts and source materials
by multivariate analysis. The mathematical approaches employed were cluster analysis using nearest-neighbour data, multidimensional
scaling and correspondence analysis.