Cristina Vargas

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Strains of the bacterium Escherichia coli harbouring genes that increase mutation rates are known to have an evolutionary advantage in chemostat competition over otherwise isogeneic strains with lower mutation rates. This advantage is frequency-dependent, the mutator strain being favoured only above a starting ratio of approximately 5 x 10(-5), and it(More)
Anaerobic enrichment cultures with sediment from an intertidal strait as inoculum were established under denitrifying, sulfate-reducing, iron-reducing and methanogenic conditions to examine the biodegradation of mono-fluorophenol and mono-fluorobenzoate isomers. Both phenol and benzoate were utilized within 2–6 weeks under all electron-accepting conditions.(More)
The biotransformation of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-tetraCDD) under anaerobic sulfate-reducing, methanogenic, and iron-reducing conditions was examined with anaerobic enrichment cultures established with sediment from an estuarine intertidal strait in the New York/New Jersey harbor. In addition, the effect of prior enrichment on(More)
Pineapple production in Costa Rica increased nearly 300-fold during the last 30 yr, and >40,000 hectares of land are currently dedicated to this crop. At the end of the pineapple cropping cycle, plants are chopped and residues incorporated into the soil in preparation for replanting. Associated with increased pineapple production has been a large increase(More)
Pineapple production in Costa Rica increased nearly 300-fold during the last 30 yr, and >40,000 hectares of land are currently dedicated to this crop. At the end of the pineapple cropping cycle, plants are chopped and residues incorporated into the soil in preparation for replanting. Associated with increased pineapple production has been a large increase(More)
In lake Titicaca, the distribution of the modern ostracod fauna appears to be controlled by a combination of two factors: a) the equilibrium between carbonates and organic matter, b) the ionic composition of the lake water and its tributaries. Therefore, the Limnocythere-Pampacythere group generally predominates on an alkaline-carbonate lake floor. In parts(More)
A new nonsymmetric As(OH)(3) species that is more stable than the C(3) structure is found at HF, Density Functional Theory (B3LYP), MP2, MP4 and CCSD(T) levels with the Stuttgart RECP-basis for As and the aug-cc-pvdz/pvtz extended basis sets. Transition state (TS) geometries are close to the C(3) one. Energy differences and interconversion barriers become(More)
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