Weathering rates and origin of inorganic carbon as influenced by river regulation in the boreal sub-arctic region of Sweden

International audienceMajor environmental stressors of boreal and sub-arctic rivers are hydrological changes and global warming and both factors will significantly influence the future evolution of the river chemistry in high latitudes. We tested the hypothesis whether lower concentrations of dissolved constituents observed in regulated rivers come along with lower weathering rates, though specific discharge as a major force for physical erosion and weathering is often higher in regulated river systems. In this study the river chemistry, weathering rates and related carbon dioxide consumption in two large watersheds in the sub arctic region of Sweden, one regulated river (Lule River) and one unregulated river (Kalix River), was investigated. Weathering rates of silicates in the two watersheds are shown to be different; the silicate weathering rate in Kalix River catchment is almost 30% higher than in the Lule River catchment. This is most likely a result of constructing large reservoirs in the former river valleys inundating the alluvial deposits and thus decreasing soil/water contact resulting in lower weathering rates. Furthermore, the difference observed in weathering rates between lowland regions and headwaters suggests that weathering in sub arctic boreal climates is controlled by the residence time for soil water rock interactions followed by lithology. The chemistry in the two rivers shows weathering of silicates as the origin for 68% of the inorganic carbon in the Lule River and 74% for Kalix River. The study clearly shows that river regulation significantly decreases alkalinity export to the sea because lower weathering rates gives less carbon dioxide ending up as DIC. By considering sources for inorganic carbon we here report that the inorganic carbon load that originates from respiration of organic matter in soils makes up of 30% and 35% of the total C export for the watersheds of the Kalix River and Lule River, respectively. Therefore, both the inorganic (i.e. the origin of carbon in DIC) and organic carbon load carbon must be considered when studying climate changes on the organic carbon load since effects from increased degradation of organic matter may lead to more weathering (higher production of DIC)

The effect of amoxicillin on dental enamel development in vivo

The exposure to amoxicillin has been associated with molar incisor hypomineralization. This study aimed to determine if amoxicillin disturbs the enamel mineralization in in vivo experiments. Fifteen pregnant rats were randomly assigned into three groups to received daily phosphatase-buffered saline or amoxicillin as either 100 or 500 mg/kg. Mice received treatment from day 13 of pregnancy to day 40 postnatal. After birth, the offsprings from each litter continued to receive the same treatment according to their respective group. Calcium (Ca) and phosphorus (P) content in the dental hard tissues were analyzed from 60 upper first molars and 60 upper incisors by the complexometric titration method and colorimetric analysis using a spectrophotometer at 680 nm, respectively. Lower incisors were analyzed by X-ray microtomography, it was measured the electron density of lingual and buccal enamel, and the enamel and dentin thickness. Differences in Ca and P content and electron density among the groups were analyzed by one-way ANOVA. There was no significant difference on enamel electron density and thickness among the groups (p > 0.05). However, in incisors, the higher dose of amoxicillin decreased markedly the electron density in some rats. There were no statistically significant differences in Ca (p = 0.180) or P content (p = 0.054), although the higher dose of amoxicillin could affect the enamel in some animals. The amoxicillin did not significantly alter the enamel mineralization and thickness in rats. © 2020Peer reviewe

Component-wise deuterium-tritium fusion yield predictions with neutron emission spectrometry

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Cardiopulmonary Exercise Testing Provides Additional Prognostic Information in Cystic Fibrosis

RATIONALE: The prognostic value of cardiopulmonary exercise testing (CPET) for survival in cystic fibrosis (CF) in the context of current clinical management, when controlling for other known prognostic factors, is unclear. OBJECTIVES: To determine the prognostic value of CPET-derived measures beyond peak oxygen uptake (V.o2peak) following rigorous adjustment for other predictors. METHODS: Data from 10 CF centers in Australia, Europe, and North America were collected retrospectively. A total of 510 patients completed a cycle CPET between January 2000 and December 2007, of which 433 fulfilled the criteria for a maximal effort. Time to death/lung transplantation was analyzed using Cox proportional hazards regression. In addition, phenotyping using hierarchical Ward clustering was performed to characterize high-risk subgroups. MEASUREMENTS AND MAIN RESULTS: Cox regression showed, even after adjustment for sex, FEV1% predicted, body mass index (z-score), age at CPET, Pseudomonas aeruginosa status, and CF-related diabetes as covariates in the model, that V.o2peak in % predicted (hazard ratio [HR], 0.964; 95% confidence interval [CI], 0.944–0.986), peak work rate (% predicted; HR, 0.969; 95% CI, 0.951–0.988), ventilatory equivalent for oxygen (HR, 1.085; 95% CI, 1.041–1.132), and carbon dioxide (HR, 1.060; 95% CI, 1.007–1.115) (all P < 0.05) were significant predictors of death or lung transplantation at 10-year follow-up. Phenotyping revealed that CPET-derived measures were important for clustering. We identified a high-risk cluster characterized by poor lung function, nutritional status, and exercise capacity. CONCLUSIONS: CPET provides additional prognostic information to established predictors of death/lung transplantation in CF. High-risk patients may especially benefit from regular monitoring of exercise capacity and exercise counseling

Teacher unionism in changing times: is this the real “new unionism”?

This article provides a case study of union change in an environment in which radical school restructuring is taking place, and active strategies to weaken and marginalize organized teachers are being pursued by the state. The case study union is the National Union of Teachers in England. The article explores a number of different strategies open to teacher unions, utilizing a framework provided by Turner (2004). Drawing on data collected at a national level, and in three local authority areas, I argue that the National Union of Teachers’ response to the erosion of collective bargaining is best presented as an amalgam of strategies focused on workplace organizing, political campaigning, and coalition building. The data demonstrate considerable congruence between national and local strategies, although local data reveal considerable challenges in implementation and consequently considerable unevenness in local experiences