Local and global inverse modelling strategies to estimate parameters for pesticide leaching from lysimeter studies.

Background: As an option for higher-tier leaching assessment of pesticides in Europe according to FOCUS, pesticide properties can be estimated from lysimeter studies by inversely fitting parameter values (substance half-life DT50 and sorption coefficient to organic matter kom ). The aim of the study was to identify adequate methods for inverse modelling.

Results: Model parameters for the PEARL (Pesticide Emission Assessment at Regional and Local scales) model were estimated with different inverse optimisation algorithms - the Levenberg-Marquardt (LM), PD_MS2 (PEST Driver Multiple Starting Points 2) and SCEM (Shuffled Complex Evolution Metropolis) algorithms.

Assessment of rare dietary risks based on analysis of food combinations.

Probabilistic methods, in particular Monte Carlo methods, have become widely used in assessment of dietary risks from plant protection products. However, if the critical exposure occurs rarely, estimating its probability with commonly used Monte Carlo approaches can require an unrealistically big number of iterations. A simple method proposed in this paper, referred to as food combination analysis (FCA), finds out subsets of input values necessary for occurrence of a critical exposure event.

Metabolic flux model for an anchorage-dependent MDCK cell line: characteristic growth phases and minimum substrate consumption flux distribution.

Up to now cell-culture based vaccine production processes only reach low productivities. The reasons are: (i) slow cell growth and (ii) low cell concentrations. To address these shortcomings, a quantitative analysis of the process conditions, especially the cell growth and the metabolic capabilities of the host cell line is required.

Comparison of metabolic flux distributions for MDCK cell growth in glutamine- and pyruvate-containing media.

In mammalian cell cultures, ammonia that is released into the medium as a result of glutamine metabolism and lactate that is excreted due to incomplete glucose oxidation are both known to essentially inhibit the growth of cells. For some cell lines, for example, hybridoma cells, excreted ammonia also has an effect on product formation. Although glutamine has been generally considered as the major energy source for mammalian cells, it was recently found that various adherent cell lines (MDCK, CHO-K1, and BHK21) can grow as well in glutamine-free medium, provided glutamine is substituted with pyruvate.