High exchangeable calcium concentrations in soils on Barro Colorado Island, Panama

The soils on four lithologies (basaltic conglomerates, Bohio; Andesite; volcanoclastic sediments with basaltic agglomerates, Caimito volcanic; foraminiferal limestone, Caimito marine) on Barro Colorado Island (BCI) have high exchangeable Ca concentrations and cation-exchange capacities (CEC) compared to other tropical soils on similar parent material. In the 0–10 cm layer of 24 mineral soils, pH values ranged from 5.7 (Caimito volcanic and Andesite) to 6.5 (Caimito marine), concentrations of exchangeable Ca from 134 mmolc kg− 1 (Caimito volcanic) to 585 mmolc kg− 1 (Caimito marine), and cation exchange capacities from 317 mmolc kg− 1 (Caimito volcanic) to 933 mmolc kg− 1 (Caimito marine). X-ray diffractometry of the fraction < 2 μm revealed that smectites dominated the clay mineral assemblage in soil except on Caimito volcanic, where kaolinite was the dominant clay mineral. Exchangeable Ca concentrations decreased with increasing soil depth except on Caimito marine. The weathering indices Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Weathering Index of Parker (WIP) determined for five soils on all geological formations, suggested that in contrast to expectation the topsoil (0–10 cm) appeared to be the least and the subsoil (50–70 cm) and saprolite (isomorphically weathered rock in the soil matrix) the most weathered. Additionally, the weathering indices indicated depletion of base cations and enrichment of Al-(hydr)oxides throughout the soil profile. Tree species did not have an effect on soil properties. Impeded leaching and the related occurrence of overland flow seem to be important in determining clay mineralogy. Our results suggest that (i) edaphic conditions favor the formation of smectites on most lithologies resulting in high CEC and thus high retention capacity for Ca and (ii) that there is an external source such as dust or sea spray deposition supplying Ca to the soils.

Fibrinolysis for patients with intermediate-risk pulmonary embolism

BACKGROUND The role of fibrinolytic therapy in patients with intermediate-risk pulmonary embolism is controversial. METHODS In a randomized, double-blind trial, we compared tenecteplase plus heparin with placebo plus heparin in normotensive patients with intermediate-risk pulmonary embolism. Eligible patients had right ventricular dysfunction on echocardiography or computed tomography, as well as myocardial injury as indicated by a positive test for cardiac troponin I or troponin T. The primary outcome was death or hemodynamic decompensation (or collapse) within 7 days after randomization. The main safety outcomes were major extracranial bleeding and ischemic or hemorrhagic stroke within 7 days after randomization. RESULTS Of 1006 patients who underwent randomization, 1005 were included in the intention-to-treat analysis. Death or hemodynamic decompensation occurred in 13 of 506 patients (2.6%) in the tenecteplase group as compared with 28 of 499 (5.6%) in the placebo group (odds ratio, 0.44; 95% confidence interval, 0.23 to 0.87; P=0.02). Between randomization and day 7, a total of 6 patients (1.2%) in the tenecteplase group and 9 (1.8%) in the placebo group died (P=0.42). Extracranial bleeding occurred in 32 patients (6.3%) in the tenecteplase group and 6 patients (1.2%) in the placebo group (P<0.001). Stroke occurred in 12 patients (2.4%) in the tenecteplase group and was hemorrhagic in 10 patients; 1 patient (0.2%) in the placebo group had a stroke, which was hemorrhagic (P=0.003). By day 30, a total of 12 patients (2.4%) in the tenecteplase group and 16 patients (3.2%) in the placebo group had died (P=0.42). CONCLUSIONS In patients with intermediate-risk pulmonary embolism, fibrinolytic therapy prevented hemodynamic decompensation but increased the risk of major hemorrhage and stroke. (Funded by the Programme Hospitalier de Recherche Clinique in France and others; PEITHO EudraCT number, 2006-005328-18; ClinicalTrials.gov number, NCT00639743.).

Worry activation impairs intelligence test performace only under ego depletion

Detrimental effects of anxiety on cognitive performance have been explained by the activation of worry, detracting attention away from the task at hand. However, recent research has shown that anxiety is only related to performance when self-control capacity is low (i.e., ego depletion). The aim of the present work has been to extend these findings by showing that activation of worry will interfere with cognitive performance more strongly when self-control capacity is momentarily depleted compared to intact. After manipulations of self-control capacity and worry activation, 70 undergraduates completed a standardized intelligence test. As expected, activation of worry was associated with lower performance when self-control capacity was depleted, but had no effect when self-control capacity was intact. The findings implicate that worry may play a causal role in the anxiety–performance relationship, but only when its regulation by self-control is momentarily hindered.