Dynamic Modelling under Uncertainty: The Case of Trypanosoma brucei Energy Metabolism

Kinetic models of metabolism require detailed knowledge of kinetic parameters. However, due to measurement errors or lack of data this knowledge is often uncertain. The model of glycolysis in the parasitic protozoan Trypanosoma brucei is a particularly well analysed example of a quantitative metabolic model, but so far it has been studied with a fixed set of parameters only. Here we evaluate the effect of parameter uncertainty. In order to define probability distributions for each parameter, information about the experimental sources and confidence intervals for all parameters were collected. We created a wiki-based website dedicated to the detailed documentation of this information: the SilicoTryp wiki (http://silicotryp.ibls.gla.ac.uk/wiki/Glycolysis). Using information collected in the wiki, we then assigned probability distributions to all parameters of the model. This allowed us to sample sets of alternative models, accurately representing our degree of uncertainty. Some properties of the model, such as the repartition of the glycolytic flux between the glycerol and pyruvate producing branches, are robust to these uncertainties. However, our analysis also allowed us to identify fragilities of the model leading to the accumulation of 3-phosphoglycerate and/or pyruvate. The analysis of the control coefficients revealed the importance of taking into account the uncertainties about the parameters, as the ranking of the reactions can be greatly affected. This work will now form the basis for a comprehensive Bayesian analysis and extension of the model considering alternative topologies

Emulsion electrosynthesis in the presence of power ultrasound Biphasic Kolbe coupling processes at platinum and boron-doped diamond electrodes

The electrochemical oxidation of aliphatic carboxylic acids, hexanoic, heptanoic, and lauric acid, under biphasic conditions is studied as a model system for ultrasound enhanced Kolbe electrosynthesis processes. Power ultrasound is used to generate an in situ emulsified medium and to remove reaction products continuously from the electrode surface. A clean and highly efficient process at platinum electrodes with formation of 'one electron' products only occurs in marked contrast to processes in monophasic media. For hexanoic acid the Kolbe dimer product R-R is formed in up to 75% yield with 45% current efficiency at 0.18 A cm-2 current density and in the presence of 190 W cm-2 ultrasound. The mechanism is explained in terms of a dynamically modified electrode surface, at which hydrophobic products are immediately 'trapped' via partitioning into a non-polar organic phase and transported away into the emulsion system. Kolbe electrosynthesis is undertaken both at platinum electrodes and at free-standing polycrystalline boron-doped diamond electrodes, in order to minimize the surface erosion effect induced by power ultrasound. The type and yield of products obtained from the biphasic Kolbe electrolysis process at diamond electrodes are essentially identical to those observed at platinum and based on this observation, the presence of a biphasic reaction layer at the electrode surface is postulated to govern the process. © 2001 Elsevier Science B.V

Patterns of release of the secondary conidia of Claviceps africana, the sorghum ergot pathogen in Australia

Trials were conducted in southern Queensland, Australia between March and May 2003, 2004 and 2005 to study patterns of hourly and daily release of the secondary conidia of Claviceps africana and their relationships with weather parameters. Conidia were trapped for at least one hour on most (> 90%) days in 2003 and 2004, but only on 55% of days in 2005. Both the highest daily concentration of conidia, and the highest number of hours per day when conidia were trapped, were recorded 1-3 days after rainfall events. Although the pattern of conidial release was different every day, the highest hourly conidial concentrations occurred between 10.00 hours and 17.00 hours on 73% of all days in the three trials. Hours when conidia were trapped were characterized by higher median values of temperature, windspeed and vapour pressure deficit, lower relative humidity, and leaf wetness values of 0%, than hours when no conidia were recorded. The results indicate that fungicides need to be applied to the highly ergot-susceptible male sterile (A-) lines of sorghum in hybrid seed production blocks and breeders' nurseries as soon as possible after rainfall events to minimize ergot severity

First report of the powdery mildew Erysiphe diffusa on soybean in Australia

A powdery mildew with a Pseudoidium anamorph was found on Glycine max in south-east Queensland, Australia. Morphological examination and molecular identification determined this species as Erysiphe diffusa, which is reported for the first time from Australia

New weed hosts of Macrophomina phaseolina in Australia

Macrophomina phaseolina was isolated from the roots of symptomless plants of 23 weed species found in Australian mungbean fields. Eight of these species are new host records for the world while 14 of the remaining 15 species are new reports in Australia. Isolates of M. phaseolina from all weeds were pathogenic on mungbean seedlings. These results suggest that apparently healthy weeds infected by M. phaseolina may serve as alternative hosts of the pathogen in Australian grain production regions

Designing Ride access points for shared automated vehicles

Future oriented mobility solutions, based on digital technologies, emphasize the need for digital and flexible urban infrastructure to give guidance to users. In the case of automated mobility on-demand (AMoD) services high user experience (UX) is essential for user acceptance. One of the main challenges is to enhance the user’s competence and information supply to overcome the physical meeting problem of user and shared automated vehicle (SAV). Hence, the need for the new concept of defined virtual ride access points (RAP) derives. The objective of this study is to evaluate a first human-centered RAP design prototype regarding usability and intuitiveness. By remotely interviewing 18 participants of young age, residing in urban areas and with experience in using ride-sharing services the authors show that already a first RAP prototype was positively rated with regard to usability and intuitiveness. So the mere existence of RAP presented with means of augmented reality has the potential to improve UX of new urban mobility services. With his article the authors seek to conceive guidelines for future digital human-centered AMoD infrastructure