58 research outputs found
Can sexual selection drive female life histories? A comparative study on Galliform birds
Sexual selection is an important driver of many of the most spectacular morphological traits that we find in the animal kingdom (for example see Andersson, 1994). As such, sexual selection is most often emphasized as
Distribution and composition of Mg-calcite and dolomite in the water and sediments of Lake Balaton
Diagenetic history and geochemistry of the Beekmantown-Group dolomites (Sauk Sequence) of New York, USA
Imported quartz cement in aeolian sandstone grew from water of uniform composition but has complex zonation
The origins and volumes of waters which mass-transport silica in sedimentary basins remain obscure. Many previous analytical studies have illustrated cases where quartz cements in sandstones originate from complex and variable fluids. By contrast we show, by using a combination of separation and analytical techniques, that in Lower Permian sandstones of the southern North Sea the cementing fluid was isotopically uniform during growth of quartz cement with a δ1BO of 19.6 + 1.0%‰ V-SMOW. In this relatively uniform fluid quartz cements grew and developed complex cathodoluminescence (CL) zonations. Petrographic data show that 8–10% quartz cement (locally 30%) was imported into this 380 km2× 180 m thick aeolian sandstone, and cement distribution controlled by depositional permeabilities. We infer a large-scale, high volume, flux of evolved meteoric fluid during 2 km deep burial, and show that complex CL zonation may arise from relatively subtle changes in water composition
Early-replacement dolomitization and deep-burial modification and stabilization: A case study from the late precambrian of the Zawar area, Rajasthan (India)
Defining the origin of Plasmodium falciparum resistant dhfr isolates in Senegal.
We previously reported a high baseline prevalence of mutations in the dhfr and dhps genes of Plasmodium falciparum throughout Senegal. The highest prevalence of the triple dhfr pyrimethamine associated mutations were found in isolates obtained in the western part of the country near the capital city of Dakar. In this study, we sought out to determine the relatedness of dhfr wild type and mutated strains by analyzing three microsatellite regions upstream of the dhfr locus. Twenty-six of the 31 wild type strains had a unique microsatellite pattern. In contrast, of the 17 isolates containing the triple mutation in dhfr, 11 had an identical microsatellite pattern. Diverse geographical isolates in Senegal containing the triple dhfr mutation have arisen from a limited number of ancestral strains. In addition, we demonstrate that these isolates have shared ancestry with the previously reported triple mutation haplotype found in Tanzania, South Africa, and southeast Asia. This common ancestry may have implications for the malaria control strategy for reducing the spread of sulfadoxine-pyrimethamine resistance in Senegal and elsewhere in Africa
Diagenesis and geochemistry of the Aptian dolomite (cretaceous) in the Razzak Oil Field, western Desert, Egypt
Dolomite dissolution: An alternative diagenetic pathway for the formation of palygorskite clay
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