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- PublikationCoexistence in the chemostat as a result of metabolic by-products(Springer, 2006) Rausenberger, Julia; Schmidt, Julia K.; Reichl, Udo; Flockerzi, Dietrich [in: Journal of Mathematical Biology]Classical chemostat models assume that competition is purely exploitative and mediated via a common, limiting and single resource. However, in laboratory experiments with pathogens related to the genetic disease Cystic Fibrosis, species specific properties of production, inhibition and consumption of a metabolic by-product, acetate, were found. These assumptions were implemented into a mathematical chemostat model which consists of four nonlinear ordinary differential equations describing two species competing for one limiting nutrient in an open system. We derive classical chemostat results and find that our basic model supports the competitive exclusion principle, the bistability of the system as well as stable coexistence. The analytical results are illustrated by numerical simulations performed with experimentally measured parameter values. As a variant of our basic model, mimicking testing of antibiotics for therapeutic treatments in mixed cultures instead of pure ones, we consider the introduction of a lethal inhibitor, which cannot be eliminated by one of the species and is selective for the stronger competitor. We discuss our theoretical results in relation to our experimental model system and find that simulations coincide with the qualitative behavior of the experimental result in the case where the metabolic by-product serves as a second carbon source for one of the species, but not the producer.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAn “Agile” project planning course. Learning by doing in process engineering education(Elsevier, 07/2024) Riedl, Wolfgang; Brown, Andrew; Rausenberger, Julia [in: Education for Chemical Engineers]Process engineering education requires a comprehensive foundation and practical application. To bridge the gap between theoretical education and market requirements, a "Project Planning Course” has been offered since 2018 as part of the MSc specialization in Chemical Engineering at the FHNW School of Life Sciences. The course didactics combines the principles of an “agile” teaching mindset and problem-based learning, which optimally support the experience of this module. Students had to work on unresolved real-world problems, make decisions based on incomplete information, and present their work in a board meeting role play with board members from industry. These situations represent typical real-world challenges for future chemical engineers. The results show that most of the students learned to cope with the unconventional teaching methodology. The students’ evaluations of the module have been very positive, especially the fact that the active participation of the students triggers the actual learning process - which means that the essential learning goal has been achieved.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationSignatures of gene expression noise in cellular systems(Elsevier, 2009) Rausenberger, Julia; Fleck, Christian; Timmer, Jens; Kollmann, Markus [in: Progress in Biophysics and Molecular Biology]Noise in gene expression, either due to inherent stochasticity or to varying inter- and intracellular environment, can generate significant cell-to-cell variability of protein levels in clonal populations. To quantify the different sources of gene expression noise, several theoretical studies have been performed using either a quasi-stationary approximation for the emerging master equation or employing a time-dependent description, when cell division is taken explicitly into account. Here, we give an overview of the different origins of gene expression noise which were found experimentally and introduce the basic stochastic modeling approaches. We extend, and apply a time-dependent description of gene expression noise to experimental data. The analysis shows that the induction level of the transcription factor can be employed to discriminate the noise profiles and their characteristic signatures. On the basis of experimentally measured cell distributions, our simulations suggest that transcription factor binding and promoter activation can be modeled independently of each other with sufficient accuracy.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationHow to strengthen today’s math skills of tomorrow’s engineers. Practical experiences with agile approaches to innovative university math lectures(Springer, 2021) Rausenberger, Julia; Gilgen, Lilian; Mülken, Oliver; Feiler, Stefanie; Burkhard, Roger; Erb, Nico; Luther, Anna; Hölscher, Meike; Bock, Silke; Pude, Frank; Hloch, Sergej; Klichová, Dagmar; Pude, Frank; Krolczyk, Grzegorz M.; Chattopadhyaya, Somnath [in: Advances in Manufacturing Engineering and Materials II. Proceedings of the International Conference on Manufacturing Engineering and Materials (ICMEM 2020), 21–25 June, 2021]How can math lectures within the life sciences curriculum take into account student heterogeneity in terms of prior mathematical knowledge and learn ing pace? And how can they do this while combining the achievement of learning goals with elements of agile working, such as self-organization in heterogeneous teams or promotion of creativity and motivation? At the start of our new “BSc In Life Sciences” curriculum, the focus was on two approaches to address stu dent heterogeneity – eduScrum as an undergraduate math learning framework and the qualification of highly motivated students as tutors. This paper reports on the motivation and development process to adapt teaching settings and presents first insights into the acceptance and impact of both approaches. In addition to achiev ing the learning objectives, both the eduScrum framework and the qualification of tutors promote skills such as collaboration, communication, creativity, IT skills and critical thinking - requirements that tomorrows’ employees will encounter in their carriers in the twenty-first-century.04B - Beitrag Konferenzschrift
- PublikationPhotoconversion and nuclear trafficking cycles determine phytochrome A's response profile to far-red light(Cell Press, 02.09.2011) Rausenberger, Julia; Tscheuschler, Anke; Nordmeier, Wiebke; Wüst, Florian; Timmer, Jens; Schäfer, Eberhard; Fleck, Christian; Hiltbrunner, Andreas [in: Cell]Phytochrome A (phyA) is the only photoreceptor in plants, initiating responses in far-red light and, as such, essential for survival in canopy shade. Although the absorption and the ratio of active versus total phyA are maximal in red light, far-red light is the most efficient trigger of phyA-dependent responses. Using a joint experimental-theoretical approach, we unravel the mechanism underlying this shift of the phyA action peak from red to far-red light and show that it relies on specific molecular interactions rather than on intrinsic changes to phyA's spectral properties. According to our model, the dissociation rate of the phyA-FHY1/FHL nuclear import complex is a principle determinant of the phyA action peak. The findings suggest how higher plants acquired the ability to sense far-red light from an ancestral photoreceptor tuned to respond to red light.01A - Beitrag in wissenschaftlicher Zeitschrift