Sub-nanomolar detection of thrombin activity on a microfluidic chip

Bioluminescence resonance energy transfer (BRET) is a form of Förster resonance energy transfer. BRET has been shown to support lower limits of detection than fluorescence resonance energy transfer (FRET) but, unlike FRET, has not been widely implemented on microfluidic devices for bioanalytical sensing. We recently reported a microscope-based microfluidic system for BRET-based biosensing, using a hybrid, high quantum-efficiency, form of BRET chemistry. This paper reports the first optical fiber-based system for BRET detection on a microfluidic chip, capable of quantifying photon emissions from the low quantum-efficiency BRET² system. We investigated the effects of varying core diameter and numerical aperture of optical fibers, as well as varying microfluidic channel design and measurement conditions. We optimized the set-up in order to maximize photon counts and minimize the response time. The optimized conditions supported measurement of thrombin activity, with a limit of detection of 20 pM, which is lower than the microscope-based system and more than 20 times lower than concentrations reported to occur in plasma clots.     

Embellishing Problem-Solving Examples with Deep Structure Information Facilitates Transfer

Appreciation of problem structure is critical to successful learning. Two experiments investigated effective ways of communicating problem structure in a computer-based learning environment and tested whether verbal instruction is necessary to specify solution steps, when deep structure is already embellished by instructional examples. Participants learned to solve algebra-like problems and then solved transfer problems that required adjustment of learned procedures. Experiment 1 demonstrated that verbal instruction helped learning by reducing learners' floundering, but its positive effect disappeared in the transfer. More importantly, students transferred better when they studied with examples that emphasized problem structure rather than solution procedure. Experiment 2 showed that verbal instruction was not necessarily more effective than nonverbal scaffolding to convey problem structure. Final understanding was determined by transparency of problem structure regardless of presence of verbal instruction. However, verbal instruction had a positive impact on learners by having them persist through the task, and optimal instructional choices were likely to differ depending on populations of learners.     

Rediscovering the political dimension of the personal life story: results from an intergenerational narrative learning project with older adults in South Westphalia

Using qualitative interviews, focus groups, storytelling and collective journaling, the life experiences of people in a local village community, in South Westphalia, Germany, born between 1930 and 1945, were analysed collaboratively. The research intention was to give the younger generations in that region access to these experiences and insights, within the context of democratic learning and civic education. The focus of this narrative learning project was on the politically relevant issues and themes they contained, above all: the significance of free information and thought, a free cultural life, access to education for all children and youth, a self-determined life for women and girls, as well as cohesion and self-help structures in the social community. Many tales were shared from the Third Reich, making references to Wilhelmine Germany and the Republic of Weimar, including how these times had been narrated to them through their forebearers and families’ archives.