14 research outputs found

    Evolutionary Control of Infectious Disease: Prospects for Vectorborne and Waterborne Pathogens

    No full text
    Evolutionary theory may contribute to practical solutions for control of disease by identifying interventions that may cause pathogens to evolve to reduced virulence. Theory predicts, for example, that pathogens transmitted by water or arthropod vectors should evolve to relatively high levels of virulence because such pathogens can gain the evolutionary benefits of relatively high levels of host exploitation while paying little price from host illness. The entrance of Vibrio cholerae into South America in 1991 has generated a natural experiment that allows testing of this idea by determining whether geographic and temporal variations in toxigenicity correspond to variation in the potential for waterborne transmission. Preliminary studies show such correspondences: toxigenicity is negatively associated with access to uncontaminated water in Brazil; and in Chile, where the potential for waterborne transmission is particularly low, toxigenicity of strains declined between 1991 and 1998. In theory vector-proofing of houses should be similarly associated with benignity of vectorborne pathogens, such as the agents of dengue, malaria, and Chagas' disease. These preliminary studies draw attention to the need for definitive prospective experiments to determine whether interventions such as provisioning of uncontaminated water and vector-proofing of houses cause evolutionary reductions in virulenc

    Archaeometric analysis of ceramic production in Tiwanaku state ( c

    No full text
    The chemical and mineralogical characterization of seven ceramic fragments produced within Tiwanaku state (c.500-1000 ce) is reported. The instrumental techniques used included X-ray elemental and mineralogical chemical analysis, Raman spectroscopy, and scanning and light microscopy. The results indicate there are several clay types, although they show similarities, such as the use of a plant-based temper. The red colour of the decoration is hematite, and manganese oxides such as jacobsite are present in the black. The white colour is a mixture of gypsum and clay, and the orange is a mixture of hematite and clay. The use of colours, the quality of the clays and the temperatures reached during pottery firing point to expertise in ceramic production and to complex decision-making processes. The multi-elemental archaeometric approach documented here could become an important tool to shed a light on ancient ceramic technology and the internal variance of Tiwanaku pottery.Alfred Kordelin Foundation (Finland) project UTA-Mayor 4752-19 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 114052
    corecore