PubMed · 7660496
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J E Ollé-Goig. 1995. Diagnosing tuberculosis.. https://doi.org/10.1177/004947559502500325
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Species delimitation in the South American genus Polylepis is notoriously challenging due to high morphological similarity and phenotypic plasticity, likely driven by hybridization and gene flow. Previous phylogenetic studies suggested that genetic structure aligns more strongly with geography than with taxonomy, questioning existing species concepts and hampering conservation efforts. We used double-digest RAD sequencing (ddRADseq) to generate genome-wide SNP data for 11 Polylepis species sampled across multiple localities in Bolivia and Ecuador. Population genetic analyses, phylogenetic inference, and network approaches were combined to assess whether genetic structure aligns more closely with taxonomy or geography. Morphologically defined species formed largely cohesive genetic lineages across regions, with species identity explaining substantially more genetic variation than locality. While localized admixture and reticulation were detected among closely related taxa, widespread species showed strong genetic cohesion and clear separation from congeners. Our results indicate that the sampled Polylepis species from Bolivia and Ecuador maintain distinct genetic identities despite localized signals consistent with gene flow. This genome-wide support for current taxonomy highlights Polylepis as a valuable model for studying speciation under gene flow and indicates that multiple geographic sampling will be essential in reconstructing a robust phylogeny of the genus, with important implications for conservation planning in Andean montane forests.
Simple evaporation of spilled oil is usually thought to be restricted to the smaller hydrocarbons (<15 carbons). We show that aeration of oil in water, at 22 degrees C, substantially extends this evaporation, leading to the loss of alkanes up to at least hexatricosane (nC36) and of polycyclic aromatic hydrocarbons with at least four rings (e.g., chrysene and its alkylated forms). This phenomenon is apparently related to steam distillation and should be considered as an important candidate pathway to explain the observed weathering of oil spilled from the OSSA II pipeline into the Río Desaguadero on the Bolivian Altiplano (approximately 3700 m), which occurred during a very turbulent flood.
OBJECTIVES: To calculate and present the caries prevalence for some countries/states among 12-year-olds, expressed as Significant Caries Index (SiC Index) and to analyse the relationship between the mean DMFT and the SiC Index for these countries. SiC Index is the mean DMFT of the one-third of a population with the highest caries values. METHODS: An Excel(R) application for calculating SiC was developed (http://www.whocollab.od.mah.se/expl/siccalculation.xls) and indices were calculated from the data collected for 14 countries and one state from the Country/Area Profile Programme (http://www.whocollab.od.mah.se/index.html). To investigate the provinces of a country that had already reached the proposed SiC Index goal of 3 DMFT among the 12-year-olds, data for 17 counties and a city from Sweden were collected and the respective mean DMFT and SiC Indices calculated. RESULTS: The mean DMFT varied from 1.0 to 8.5 and the SiC Index varied from 2.8 to 13.7 in the national data. Jamaica, Senegal and Sweden were the only three countries that showed SiC Indices that were less than 3 DMFT. The mean DMFT varied from 0.5 to 1.4 and the SiC Index varied from 1.4 to 3.6 in the Swedish county/city data examined. A strong linear relationship between the mean DMFT and the SiC Index was found for the populations presented in this study. CONCLUSION: The SiC Index is an indicator that reflects the situation among the most caries-exposed individuals and could be included in future population-based oral health surveys together with the mean DMFT.