Simultaneous measurement of position and color of single fluorescent emitters using diffractive optics

We propose a method for simultaneously measuring the position and emission color of single fluorescent emitters based on the use of a large pitch diffraction grating in the emission light path. The grating produces satellite spots adjacent to the main spot; the relative distance between the spots is a measure for the emission wavelength. We present proof-of-principle experiments on beads and mixtures of quantum dots using a spatial light modulator for making a programmable diffraction grating. A wavelength precision of around 10 nm can be achieved for 1000 signal photons and practical background levels, while maintaining a localization precision of around 10 nm.ImPhys/Imaging PhysicsApplied Science

OptCouple: Joint simulation of gene knockouts, insertions and medium modifications for prediction of growth-coupled strain designs

Biological production of chemicals is an attractive alternative to petrochemical-based production, due to advantages in environmental impact and the spectrum of feasible targets. However, engineering microbial strains to overproduce a compound of interest can be a long, costly and painstaking process. If production can be coupled to cell growth it is possible to use adaptive laboratory evolution to increase the production rate. Strategies for coupling production to growth, however, are often not trivial to find. Here we present OptCouple, a constraint-based modeling algorithm to simultaneously identify combinations of gene knockouts, insertions and medium supplements that lead to growth-coupled production of a target compound. We validated the algorithm by showing that it can find novel strategies that are growth-coupled in silico for a compound that has not been coupled to growth previously, as well as reproduce known growth-coupled strain designs for two different target compounds. Furthermore, we used OptCouple to construct an alternative design with potential for higher production. We provide an efficient and easy-to-use implementation of the OptCouple algorithm in the cameo Python package for computational strain design

ICT symposium sociale processen bij computerondersteund samenwerkend leren

Verschillende onderzoeksprojecten van de ICO/ISOR onderzoeksgroep Onderwijskunde Utrecht richten zich op computerondersteuning van samenwerkend leren. Sociale processen lijken vaak van grote invloed. In het symposium proberen vijf projecten een antwoord te geven op de vraag in hoeverre sociale processen het computerondersteund samenwerkend leren bepalen. Onder leiding van de discussiant wordt dit thema vervolgens plenair uitgediept