Rapid mask prototyping for microfluidics

With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks.     

Warum scheiterte 1920 August Biers Antrag auf einen „Doktor der Leibesübungen“?

This article deals with the first years of foundation of the private Deutsche Hochschule für Leibesübungen (DHfL). It focuses on the question of why August Bier’s application for a Doktor der Leibesübungen in 1920 was refused. In the same year the DHfL also made an application for the education in state-run schools which was already task of the state-run Preußische Landesturnanstalt at Spandau. As the DHfL combined this application with its insistence on its autonomous status an application for a Doktor der Leibesübungen had implied financial, conceptual and institutional obligations for Prussia and at the same time a renuncitation of its sovereign rights. This thesis was proved by a comparison between the doctorate in physical education and the doctorate for businessmen at Cologne University.     

The relative age effect on physical fitness in preschool children

ABSTRACT

The aim of the present study was to investigate the existence of a relative age effect (RAE) on physical fitness of preschoolers. Anthropometry and physical fitness were assessed in 3147 children (3–5 years old) using the PREFIT battery. Based on the birth year, participants were divided into 3year groups (3-, 4- and 5-years). Within each year group, 4quarter groups were created: quarter 1, preschoolers born from January to March; quarter 2, from April to June; quarter 3, from July to September; quarter 4, from October to December. The MANCOVA analysis revealed a main effect of year group (Wilks’ λ = 0.383; F_10,5996 = 369.64; p < 0.001, η_p ² = 0.381) and of quarter (Wilks’ λ = 0.874; F_15,8276.6 = 27.67; p < 0.001; η_p ² = 0.044) over the whole battery of tests. To the best of our knowledge, this is the first study to report the existence of RAE at the preschool stage. In general, performance improved as the relative age increased (i.e., those born in quarter 1 performed better than those in the other quarters). Individualization strategies should be addressed within the same academic year not only in elementary or secondary years but also in preschoolers.