Integrating trait-based empirical and modeling research to improve ecological restoration

A global ecological restoration agenda has led to ambitious programs in environmental policy to mitigate declines in biodiversity and ecosystem services. Current restoration programs can incompletely return desired ecosystem service levels, while resilience of restored ecosystems to future threats is unknown. It is therefore essential to advance understanding and better utilize knowledge from ecological literature in restoration approaches. We identified an incomplete linkage between global change ecology, ecosystem function research, and restoration ecology. This gap impedes a full understanding of the interactive effects of changing environmental factors on the long-term provision of ecosystem functions and a quantification of trade-offs and synergies among multiple services. Approaches that account for the effects of multiple changing factors on the composition of plant traits and their direct and indirect impact on the provision of ecosystem functions and services can close this gap. However, studies on this multilayered relationship are currently missing. We therefore propose an integrated restoration agenda complementing trait-based empirical studies with simulation modeling. We introduce an ongoing case study to demonstrate how this framework could allow systematic assessment of the impacts of interacting environmental factors on long-term service provisioning. Our proposed agenda will benefit restoration programs by suggesting plant species compositions with specific traits that maximize the supply of multiple ecosystem services in the long term. Once the suggested compositions have been implemented in actual restoration projects, these assemblages should be monitored to assess whether they are resilient as well as to improve model parameterization. Additionally, the integration of empirical and simulation modeling research can improve global outcomes by raising the awareness of which restoration goals can be achieved, due to the quantification of trade-offs and synergies among ecosystem services under a wide range of environmental conditions

Emancipating and developing learning activity: Systemic intervention and re-instrumentation in higher education.

The central theme of this thesis is the emancipation and further development of learning activity in higher education in the context of the ongoing digital transformation of our societies. It was developed in response to the highly problematic mainstream approach to digital re-instrumentation of teaching and studying practises in contemporary higher education. The mainstream approach is largely based on centralisation, standardisation, commoditisation, and commercialisation, while re-producing the general patterns of control, responsibility, and dependence that are characteristic for activity systems of schooling. Whereas much of educational research and development focuses on the optimisation and fine-tuning of schooling, the overall inquiry that is underlying this thesis has been carried out from an explicitly critical position and within a framework of action science. It thus conceptualises learning activity in higher education not only as an object of inquiry but also as an object to engage with and to intervene into from a perspective of intentional change. The knowledge-constituting interest of this type of inquiry can be tentatively described as a combination of heuristic-instrumental (guidelines for contextualised action and intervention), practical-phronetic (deliberation of value-rational aspects of means and ends), and developmental-emancipatory (deliberation of issues of power, self-determination, and growth) aspects. Its goal is the production of orientation knowledge for educational practise. The thesis provides an analysis, argumentation, and normative claim on why the development of learning activity should be turned into an object of individual|collective inquiry and intentional change in higher education, and why the current state of affairs in higher education actually impedes such a development. It argues for a decisive shift of attention to the intentional emancipation and further development of learning activity as an important cultural instrument for human (self-)production within the digital transformation. The thesis also attempts an in-depth exploration of what type of methodological rationale can actually be applied to an object of inquiry (developing learning activity) that is at the same time conceptualised as an object of intentional change within the ongoing digital transformation. The result of this retrospective reflection is the formulation of “optimally incomplete” guidelines for educational R&D practise that shares the practicalphronetic (value related) and developmental-emancipatory (power related) orientations that had been driving the overall inquiry. In addition, the thesis formulates the instrumental-heuristic knowledge claim that the conceptual instruments that were adapted and validated in the context of a series of intervention studies provide means to effectively intervene into existing practise in higher education to support the necessary development of (increasingly emancipated) networked learning activity. It suggests that digital networked instruments (tools and services) generally should be considered and treated as transient elements within critical systemic intervention research in higher education. It further argues for the predominant use of loosely-coupled, digital networked instruments that allow for individual|collective ownership, control, (co-)production, and re-use in other contexts and for other purposes. Since the range of digital instrumentation options is continuously expanding and currently shows no signs of an imminent slow-down or consolidation, individual and collective exploration and experimentation of this realm needs to be systematically incorporated into higher education practise.Siirretty Doriast

Educational Design Research: A primer

This editorial article introduces the overall conceptualisation of the journal EDeR - Educational Design Research and its review- and workflow model. In addition, it provides an overview of all contributions that made it into Issue 1 of EDeR, before it invites the wider Design-Based Research community to participate in the overall project in a variety of roles and functions

Revisiting the derivation of stage costs in infinite horizon discrete-time optimal control

In many applications of optimal control, the stage cost is not fixed, but rather a design choice with considerable impact on the control performance. In infinite horizon optimal control, the choice of stage cost is often restricted by the requirement of uniform cost controllability, which is nontrivial to satisfy. Here we revisit a previously proposed constructive technique for stage cost design. We generalize its setting, weaken the required assumptions and add additional flexibility. Furthermore, we show that the required assumptions essentially cannot be weakened anymore. By providing improved design options for stage costs, this work contributes to expanding the applicability of optimization-based control methodologies, in particular, model predictive control

The large core limit of spiral waves in excitable media: A numerical approach

We modify the freezing method introduced by Beyn & Thuemmler, 2004, for analyzing rigidly rotating spiral waves in excitable media. The proposed method is designed to stably determine the rotation frequency and the core radius of rotating spirals, as well as the approximate shape of spiral waves in unbounded domains. In particular, we introduce spiral wave boundary conditions based on geometric approximations of spiral wave solutions by Archimedean spirals and by involutes of circles. We further propose a simple implementation of boundary conditions for the case when the inhibitor is non-diffusive, a case which had previously caused spurious oscillations. We then utilize the method to numerically analyze the large core limit. The proposed method allows us to investigate the case close to criticality where spiral waves acquire infinite core radius and zero rotation frequency, before they begin to develop into retracting fingers. We confirm the linear scaling regime of a drift bifurcation for the rotation frequency and the core radius of spiral wave solutions close to criticality. This regime is unattainable with conventional numerical methods.Comment: 32 pages, 17 figures, as accepted by SIAM Journal on Applied Dynamical Systems on 20/03/1

On kernel-based statistical learning in the mean field limit

In many applications of machine learning, a large number of variables are considered. Motivated by machine learning of interacting particle systems, we consider the situation when the number of input variables goes to infinity. First, we continue the recent investigation of the mean field limit of kernels and their reproducing kernel Hilbert spaces, completing the existing theory. Next, we provide results relevant for approximation with such kernels in the mean field limit, including a representer theorem. Finally, we use these kernels in the context of statistical learning in the mean field limit, focusing on Support Vector Machines. In particular, we show mean field convergence of empirical and infinite-sample solutions as well as the convergence of the corresponding risks. On the one hand, our results establish rigorous mean field limits in the context of kernel methods, providing new theoretical tools and insights for large-scale problems. On the other hand, our setting corresponds to a new form of limit of learning problems, which seems to have not been investigated yet in the statistical learning theory literature.Comment: NeurIPS 202

Arthroskopische versus offene Labrumrefixation: eine katamnestisch-retrospektiv vergleichende Studie

Hintergrund Die Schulteranatomie und -Physiologie stellt den praktisch tätigen Arzt seit der Antike bis hin zur moderne Medizin auf Grund ihrer Komplexität vor große Herausforderungen. Sowohl im Alltag als auch im Arbeitsleben sind Betroffene mit posttraumatischer Instabilität deutlich eingeschränkt. Ziel der vorliegenden Arbeit war es, die postoperativen Ergebnisse der Labrumrekonstruktion bei Schulterinstabilität nach offenem und arthroskopischem Vorgehen zu vergleichen. Zusätzlich sollten die Auswirkungen der Arbeitsbelastung auf die Arbeitsunfähigkeit sowie die Erfolgsraten der beruflichen Rehabilitation erfasst werden. Patienten und Methodik Insgesamt konnten 90 Patienten (70m / 20w) eingeschlossen werden (16 offen; 74 arthroskopisch). Das mittlere Follow-up betrug 46,5 Monate (±22). Das Follow up beinhaltete eine klinische Untersuchung, Sonografie sowie einen Fragebogen. Das Outcome wurde zusätzlich mittels Constant-and-Murley Score, Rowe-Score sowie des UCLA-Shoulder-Score evaluiert. Um den Erfolg der beruflichen Rehabilitation zu erfassen, wurde die Arbeitsbelastung nach REFA Kriterien in 0-1 (gering) und 2-4 (hoch) klassifiziert. Ergebnisse Das Durchschnittsalter betrug 36,6 Jahre (±13,1). Die Reluxationsrate lag insgesamt bei 8,8%. Patienten mit und ohne knöcherne Beteiligung zeigten postoperativ keine signifikanten Unterschiede. Es bestand kein relevanter Alterseinfluss auf das postoperative Outcome. Eine geringe Arbeitsbelastung (REFA 0-1; 3,55 Tage ± 1,7) führte zu einer signifikant verkürzten stationären Verweildauer im Vergleich zu höherer Arbeitsbelastung (REFA 2-4; 4,68 Tage ± 2,52; p = 0,024). Dabei gab es allerdings keinen Einfluss auf die Reluxationsraten (p = 1,33). Bei niedriger Arbeitsbelastung (REFA 0-1; 2,06 Monate) waren kürzere Arbeitsunfähigkeiten zu verzeichnen im Vergleich zu höherer Arbeitsbelastung (REFA 2-4; 3,4 Monate; P = 0,005). Patienten mit erhöhter Arbeitsbelastung (REFA 2-4; 29,8%) konnten im Gegensatz zu Probanden mit niedriger Arbeitsbelastung (REFA 0-1; 7%; p = 0,006) ihre ursprüngliche Arbeit postoperativ häufiger nur unter Einschränkungen ausüben. Nach offener Rekonstruktion (6,47 Tage ± 3,38) ist die stationäre Verweildauer im Vergleich zur arthroskopischen Technik (4,18 Tage ± 2,25; p = 0,0015) verlängert. Gleiches gilt für die Operationsdauer (arthroskopisch: 52,3min ± 23; offen: 93,8min ± 26,9; p = 0,0001). Die Reluxationshäufigkeiten, die Dauer der AU sowie die klinischen Ergebnisse unterschieden sich nicht. Schlussfolgerung Knöcherne Bankart Läsionen hatten prognostisch keinen negativen Einfluss auf das Ergebnis und die Re-Luxationsrate. Das arthroskopische und offene Vorgehen ist klinisch gleichwertig zu bewerten. Lediglich die OP- und stationäre Verweildauer unterschieden sich. Höhere Arbeitsbelastungen (REFA 2-4) bewirken eine signifikant verlängerte Arbeitsunfähigkeit sowie ein erhöhtes Risiko, die ursprüngliche Arbeit nicht mehr uneingeschränkt ausüben zu können. Dieser Aspekt war nicht verfahrensabhängig

Practical and Rigorous Uncertainty Bounds for Gaussian Process Regression

Gaussian Process Regression is a popular nonparametric regression method based on Bayesian principles that provides uncertainty estimates for its predictions. However, these estimates are of a Bayesian nature, whereas for some important applications, like learning-based control with safety guarantees, frequentist uncertainty bounds are required. Although such rigorous bounds are available for Gaussian Processes, they are too conservative to be useful in applications. This often leads practitioners to replacing these bounds by heuristics, thus breaking all theoretical guarantees. To address this problem, we introduce new uncertainty bounds that are rigorous, yet practically useful at the same time. In particular, the bounds can be explicitly evaluated and are much less conservative than state of the art results. Furthermore, we show that certain model misspecifications lead to only graceful degradation. We demonstrate these advantages and the usefulness of our results for learning-based control with numerical examples.Comment: Contains supplementary material and corrections to the original versio