Chemical Composition of the Leaves of Plants with Different Ecological Strategies from the Boreal Zone

The content of main chemical components (total nitrogen and carbon, soluble and polymeric sugars, organic acids, and mineral substances) were studied in the leaves of 73 boreal plant species with different types of Grime–Ramenskii strategies. The type of ecological strategy was demonstrated to be related to the chemical composition of the leaf, with the substances studied falling into two groups. The concentrations of the substances belonging to the first group (nitrogen, organic acids, and mineral substances) were minimum in stress-tolerant and maximum in ruderal species. With respect to the type of strategy, these concentrations increased in the following series: S C R. Conversely, the concentrations of the substances of the second group (carbon and soluble sugars) decreased in this series. The nitrogen concentration and the carbon-to-nitrogen concentration ratio in leaves may be used for identifying the types of strategies.     

Comparison between the predictions of a Gaussian plume model and a Lagrangian particle dispersion model for annual average calculations of long-range dispersion of radionuclides

This study attempts to validate the applicability of a simple Gaussian dispersion model for predicting long-range dispersion of continuous releases from an industrial site, by comparison with a Lagrangian particle dispersion model. The United Kingdom Meteorological Office model NAME has been used to predict annual average concentrations of radionuclides over Western Europe, resulting from discharges from the British Nuclear Fuels (BNFL) site at Sellafield, UK. The results are compared here to calculations performed using a conventional Gaussian type of dispersion model, PLUME. The results of the Gaussian model were compared at 14 locations within Western Europe at long range (up to 1700 km). The differences in predictions between the models were explained readily by differences in the way dispersion and deposition processes are represented in the two models. However, differences are generally small compared to the expected precision of the models. The implementation of environmental processes in NAME is more complete and realistic than in PLUME, and as such the results from this model may be considered more realistic. However, given that PLUME is much simpler to use, and appears to over-estimate, rather than under-estimate, environmental concentrations, its use for radiological assessments appears appropriate.     

Vorläufige klinische Beobachtungen mit einem neuen N-Lost-Phosphamidester in der Tumortherapie

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