Vertical microbubble column–A photonic lab-on-chip for cultivation and online analysis of yeast cell cultures

This paper presents a vertically positioned microfluidic system made of poly(dimethylsiloxane) (PDMS) and glass, which can be applied as a microbubble column (μBC) for biotechnological screening in suspension. In this μBC, microbubbles are produced in a cultivation chamber through an integrated nozzle structure. Thus, homogeneous suspension of biomass is achieved in the cultivation chamber without requiring additional mixing elements. Moreover, blockage due to produced carbon dioxide by the microorganisms—a problem predominant in common, horizontally positioned microbioreactors (MBRs)—is avoided, as the gas bubbles are released by buoyancy at the upper part of the microsystem. The patterned PDMS layer is based on an optimized two-lithographic process. Since the naturally hydrophobic PDMS causes problems for the sufficient production of microbubbles, a method based on polyelectrolyte multilayers is applied in order to allow continuous hydrophilization of the already bonded PDMS-glass-system. The μBC comprises various microelements, including stabilization of temperature, control of continuous bubble formation, and two optical configurations for measurement of optical density with two different sensitivities. In addition, the simple and robust application and handling of the μBC is achieved via a custom-made modular plug-in adapter. To validate the scalability from laboratory scale to microscale, and thus to demonstrate the successful application of the μBC as a screening instrument, a batch cultivation of Saccharomyces cerevisiae is performed in the μBC and compared to shake flask cultivation. Monitoring of the biomass growth in the μBC with the integrated online analytics resulted in a specific growth rate of 0.32 h⁻¹, which is almost identical to the one achieved in the shake flask cultivation (0.31 h⁻¹). Therefore, the validity of the μBC as an alternative screening tool compared to other conventional laboratory scale systems in bioprocess development is proven. In addition, vertically positioned microbioreactors show high potential in comparison to conventional screening tools, since they allow for high density of integrated online analytics and therefore minimize time and cost for screening and guarantee improved control and analysis of cultivation parameters.     

Testing a model of teaching for anxiety and success for English language teaching

Much research has shown that there is a negative relationship between high levels of anxiety and success for English language teaching. This paper aimed to test a model of teaching for anxiety and success in English language teaching to affect anxiety and success levels at the same time in a control-experiment group with pre- and post-test study design. Anxiety levels were measured by anxiety questionnaires and electroencephalograph recordings of brain waves and success was measured by grammar tests prepared by the researcher. Results of Mann–Whitney U Test, Wilcoxon Signed Ranks Test and ANOVA pointed to a statistically significant difference in anxiety and success levels between the experiment and control group. Discussion of the results as well as implications for future research is presented.     

Der Übergang von der Grundschule in die Sekundarstufe I

Zusammenfassung Zu der Frage, auf welche Weise sich Merkmale der sozialen Herkunft auf den Schulübertritt nach der Primarstufe auswirken, wird in einer L?ngsschnittstichprobe 27 bayrischer Grundschulklassen der Verlauf des übertrittsprozesses untersucht, und zwar von den Bildungsaspirationen der Eltern am Ende der dritten Jahrgangsstufe über die Schullaufbahnempfehlungen der Lehrkr?fte bis hin zu den tats?chlichen Schulanmeldungen. Neben der Frage der Leistungsangemessenheit der Abschlussnoten und der erteilten Schulempfehlungen werden die Herkunftseffekte im Entscheidungsverlauf vertieft analysiert. Die letztendlich resultierende Schülerzuteilung zu den verschiedenen Bildungsg?ngen kovariiert deutlich mit der sozialen Herkunft der Schüler. Die vorgestellten Analysen der einzelnen vorgelagerten Entscheidungsschritte verweisen dabei auf eine st?rkere Bedeutung prim?rer gegenüber sekund?rer Einflusseffekte der sozialen Herkunft auf die Schulformzuteilung.      

I am sailing—towards a transactional analysis of ‘body techniques’

In recent years there has been a growing interest in questions related to embodiment and learning. Within the field of ‘body pedagogics’ great efforts have been made to develop theory and methodology that can deal with the corporeal aspects of experience and knowledge without adopting any form of dualistic conceptions of body/mind and organism/environment. This article connects to this body of research. The purpose is to first present a synthesis of James' radical empiricism, Dewey's transactional understanding of experience and learning and Marcel Mauss' concept of ‘body techniques’ and the notion of education embedded in it. Against the background of this theoretical development, and with a Transactional Model of Analyzing Bodying (TMAB), we then show how we can analytically come to terms with different dualistic problems that research into ‘body pedagogics’ has to deal with. We use an empirical example of dinghy sailing to create knowledge about what we learn when learning embodied knowledge, and how this learning takes place. We argue that experience is an important concept for understanding the acting knowing human being, describing how experience is organized and developed and outlining how this organization can be understood as learning. We hold that situations where someone learns to embody certain knowledge are cases of overt actions, in which we can see what kinds of relations are created and how these relations become meaningful for further action.     

Bilateral practice improves dominant leg performance in long jump

Benefits of bilateral practice both for the non-dominant and for the dominant body side have been shown in several studies. Thereby, most of the studies included movement tasks of the upper extremity or investigated sports games in which the ability of acting bilaterally is an essential basis for success and, thus, a bilateral practice is reasonable anyway. Individual unilaterally performed sports including movement tasks of the lower extremity are rarely investigated. Therefore, the aim of our study was to test if contralateral transfer due to bilateral practice can be found in an unilaterally performed sport including the lower extremity. We trained and tested 61 adolescent athletes in long jump to compare the jumping performance of the dominant leg after a 12-week practice period between two groups: a bilateral practice group that practiced specific long jump exercises with both the dominant and non-dominant leg and an unilateral practice group that practiced specific long jump exercises only with the dominant leg. Results showed a superior effect of bilateral practice compared to unilateral practice regarding the jumping performance of the dominant leg. The performance increase at post-test and retention-test for the dominant limb was significantly higher for the bilateral practice group (pre-to-post: 5.2%, pre-to-retention: 7.4%) compared to the unilateral practice group (pre-to-post: 3.4%, pre-to-retention: 4.5%). Thus, bilateral practice should be established in the early practice programmes of track and field athletes to improve the performance of the dominant take-off leg.     

Secret keys from quantum correlations

Quantum mechanics allows to create information-theoretical secure key based only on observed data. We review the current status of the resulting field quantum key distribution.     

Assessment by project work in snow engineering

Assessment in the form of a large project and field- and laboratory work was shown to be successful when applied to a course in snow engineering for university students with various backgrounds. The course was interdisciplinary, with teachers representing three different engineering disciplines. The project work was assessed by a report, a short oral presentation and an optional presentation such as a home page, a poster or a physical model. The students experienced that they had learned more with this assessment strategy than from courses with a final written exam. Peer evaluation of the relative contributions to the project work was applied and was appreciated by the students. The experiences of practical engineering tasks during the project work were also appreciated.