This work presents an array of microfluidic chambers for on-chip culturing of microorganisms in static and continuous shear-free operation modes. The unique design comprises an in-situ polymerized hydrogel that forms gas and reagent permeable culture wells in a glass chip. Utilizing a hydrophilic substrate increases usability by autonomous capillary priming. The thin gel barrier enables efficient oxygen supply and facilitates on-chip analysis by chemical access through the gel without introducing a disturbing flow to the culture. Trapping the suspended microorganisms inside a gel well allows for a much simpler fabrication than in conventional trapping devices as the minimal feature size does not depend on cell size. Nutrients and drugs are provided on-chip in the gel for a self-contained and user-friendly handling. Rapid antibiotic testing in static cultures with strains of Enterococcus faecalis and Escherichia coli is presented. Cell seeding and diffusive medium supply is provided by phaseguide technology, enabling simple operation of continuous culturing with a great flexibility. Cells of Saccharomyces cerevisiae are utilized as a model to demonstrate continuous on-chip culturing. 相似文献
Maturity and citizenship in a democracy require that laypersons are able to critically evaluate experts’ use of mathematics. Learning to critically reflect on the use of mathematics, including the acquisition of the mathematical knowledge and skills required to that end, has been repeatedly postulated as an indispensable goal of compulsory education in mathematics. However, it remained unclear in how far such reflection is possible, even for the well-educated layperson in mathematics. We use different discussions in German mass media on the pandemic policy in the SARS-CoV-2 crisis in 2020 as examples with far-reaching individual and social consequences. The selected discussions build heavily on mathematical concepts such as mortality rates, casualty numbers, reproduction numbers, and exponential growth. We identify the concepts and discuss how far they can be understood by laypersons. On the one hand, we found that some mathematical models are inappropriate, which can also be determined by laypersons. On the other hand, we found uses of mathematics where ideal concepts are intermingled with complex statistical concepts. While only the ideal concepts can be understood by laypersons, only the statistical concepts lead to actual data. The identification of both types of concepts leads to a situation where the use of mathematics evades social control and opens spaces for misconceptions and manipulation. We conclude that the evaluation of experts’ use of mathematics by laypersons is not possible in all relevant cases, and we discuss possible implications of this result.
We combine estimates of the value of patent rights from a survey of patent-holders with a set of indicator variables in order to model the value of patents. Our results suggest that the number of references to the patent literature as well as the citations a patent receives are positively related to its value. References to the non-patent literature are informative about the value of pharmaceutical and chemical patents, but not in other technical fields. Patents which are upheld in opposition and annulment procedures and patents representing large international patent families are particularly valuable. 相似文献
Recent studies have concluded that American contributions to science literature have been in relative decline, whereas contributions from other parts of the world such as the European Union and Asia have increased. Is the same true for the areas of bibliometrics, informetrics and scientometrics? This study investigates the growth and geographic distribution of metrics research for the period 1987–2008. Similar to studies of other disciplines or science in general, the findings reveal that the United States continues to dominate, but there has been a recent relative decline in North American contributions overall. European and Asian contributions have grown substantially. National and institutional collaborations that contribute to this growth do not necessarily follow close geographic proximity, although European nations have been more active with international collaborations overall, both within Europe and elsewhere. 相似文献
The aim of this report is to describe the development of the student counselling system at German universities. The first chapter gives a short review of the situation in the first decades after the war. The second chapter describes the setting up of working models for student counselling systems which served as a basis for the development of counselling centres in the seventies on a larger scale. Chapter III reports on the student counselling service at Bonn University as an example for a unit integrating information, orientation and person-centred counselling facilities as well as psychological counselling, and in Chapter IV Rott gives an overview of the situation of psychological counselling in Germany. 相似文献
Empirical studies of innovation have found that end users frequently develop important product and process innovations. Defying conventional wisdom on the negative effects of uncompensated spillovers, innovative users also often openly reveal their innovations to competing users and to manufacturers. Rival users are thus in a position to reproduce the innovation in-house and benefit from using it, and manufacturers are in a position to refine the innovation and sell it to all users, including competitors of the user revealing its innovation. In this paper, we explore the incentives that users might have to freely reveal their proprietary innovations. We then develop a game-theoretic model to explore the effect of these incentives on users’ decisions to reveal or hide their proprietary information. We find that, under realistic parameter constellations, free revealing pays. We conclude by discussing some implications of our findings. 相似文献
