University of Konstanz
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Ideas and perspectives : How sediment archives can improve model projections of marine ecosystem change
No full textGlobal warming is a major threat to marine biodiversity and ecosystem functioning, with consequences that are yet largely unknown. To frame these consequences, we need to understand how marine ecosystems respond to warming and related environmental changes. Ecosystem models have proven to be a valuable tool in this respect, but their projections vary considerably. A major limitation in current ecosystem models may be that they largely ignore evolutionary processes, which nonetheless can be relevant on the simulated timescales. In addition, ecosystem models are usually fit to contemporary data and used predictively afterwards, without further validation that they are equally applicable to past (and, by inference, future) scenarios. A promising approach to validate evolutionary ecosystem models is the use of biological archives such as natural sediments, which record long-term ecosystem changes. Since the ecosystem changes present in sediment records are affected by evolution, evolution needs to be represented in ecosystem models not only to realistically simulate the future, but also the sediment record itself. The sediment record, in turn, can provide the required constraints on long-term evolutionary changes, along with information on past environmental conditions, biodiversity, and relative abundances of taxa. Here, we present a framework to make use of such information to validate evolutionary ecosystem models and improve model projections of future ecosystem changes. Using the example of phytoplankton, key players in marine systems, we review the existing literature and discuss (I) which data can be derived from ancient sedimentary archives, (II) how we can integrate these data into evolutionary ecosystem models to improve their projections of climate-driven ecosystem changes, and (III) future perspectives and aspects that remain challenging.publishe
SPACE : Cardinality Estimation for Path Queries Using Cardinality-Aware Sequence-based Learning
No full textCardinality estimation is a central task of cost-based database query optimization. Accurate estimates enable optimizers to identify and avoid expensive plans requiring large intermediate results. While cardinality estimation has been studied extensively in relational databases, research in the setting of graph databases has been more scarce. Furthermore, recent studies have shown that machine-learning-based methods can be utilized for cardinality estimation in both relational and graph databases. In this paper, we focus on the problem of estimating the cardinality of path patterns in graph databases, and we propose the Sequence-based Path Pattern Cardinality Estimator (SPACE). Our approach treats path patterns as sequences of node labels and edge types and assign similar cardinalities to path patterns with similar node and edge order. SPACE uses a dual approach: it encodes the sequence of nodes and edges to capture structural characteristics of the path pattern, while also incorporating a cardinality-based encoding to integrate cardinality information throughout learning. In a comprehensive experimental evaluation, we show that our method outperforms the state of the art in terms of both accuracy (Q-error) and training time.publishe
"World Health Organization (WHO) and European Food Safety Authority (EFSA) risk evaluations" : Basis of TDIs and tolerable drinking water levels derived by Germany, EFSA, ECHA, and WHO
No full textVarious national and international agencies have evaluated the available information on per- and polyfluoroalkyl substances (PFAS) to determine no observed adverse effect levels (NOAELs), tolerable daily intake (TDIs) and drinking water standards. In Europe, this includes the German drinking water commission,1 the European Food Safety Agency (EFSA),2 European Chemicals Agency (ECHA)3 as well as the World Health Organization (WHO).4 Health-based guidance values e.g. tolerable weekly intake (TWI) appear to largely depend on what information was considered to be relevant and robust. For both, WHO and EFSA, there is the impression that too little consideration was given to the statistical, biological and experimental design robustness of the data sets that were employed.publishe
MultiInv : Inverting multidimensional scaling projections and computing decision maps by multilateration
No full textInverse projections enable a variety of tasks such as the exploration of classifier decision boundaries, creating counterfactual explanations, and generating synthetic data. Yet, many existing inverse projection methods are difficult to implement, challenging to predict, and sensitive to parameter settings. To address these, we propose to invert distance-preserving projections like Multidimensional Scaling (MDS) projections by using multilateration – a method used for geopositioning. Our approach finds data values for locations where no data point is projected under the key assumption that a given projection technique preserves pairwise distances among data samples in the low-dimensional space. Being based on a geometrical relationship, our technique is more interpretable than comparable machine learning-based approaches and can invert 2-dimensional projections up to |D| − 1 dimensional spaces if given at least |D| data points. We compare several strategies for multilateration point selection, show the application of our technique on three additional projection techniques apart from MDS, and use established quality metrics to evaluate its accuracy in comparison to existing inverse projections. We also show its application to computing decision maps for exploring the behavior of trained classification models. When the projection to invert captures data distances well, our inverse performs similarly to existing approaches while being interpretable and considerably simpler to compute.publishe
Crosstalk analysis in single hole-spin qubits within highly anisotropic g-tensors
No full textSpin qubits based on valence band hole states are highly promising for quantum information processing due to their strong spin-orbit coupling and ultrafast operation speed. As these systems scale up, achieving
high-fidelity single-qubit operations becomes essential. However, mitigating crosstalk effects from neighboring qubits in larger arrays, particularly for anisotropic qubits with strong spin-orbit coupling, presents a significant challenge. We investigate the impact of crosstalk on qubit fidelities during single-qubit operations and derive an analytical equation that serves as a synchronization condition to eliminate crosstalk in anisotropic media. Our analysis proposes optimized driving field conditions that can robustly synchronize Rabi oscillations and minimize crosstalk, showing a strong dependence on qubit anisotropy and the orientation of the external magnetic field. Taking experimental data into our analysis, we identify a set of parameter values that enable nearly crosstalk-free single-qubit gates, thereby paving the way for scalable quantum computing architectures.publishe
Coevolution of cooperation and epidemic spreading
No full textPeople's cooperation in adopting protective measures is effective in epidemic control and creates herd immunity as a public good. Similarly, the presence of an epidemic is a driving factor for the formation and improvement of cooperation. Here, we study the coevolution of epidemic dynamics and the public goods game as a paradigm of cooperation dynamics. Using simulations and a mean-field description, we show that the interaction of the evolutionary dynamics of cooperation and epidemic spreading leads to a feedback loop between the two dynamics. The higher disease transmission rate can promote cooperation and lead to the reduction of disease spread; in turn, the higher benefit of cooperation leads to the more efficient control of epidemics. Additionally, our work shows that a higher altruistic effect of cooperation in controlling the disease can only be detrimental to the evolution of cooperation and disease control. Rather, individuals' choices in adopting costly preventive measures are predominantly driven by the self-interested effect of such measures in reducing the probability of getting infected.publishe
Factors shaping subjective financial well-being in emerging adults : a comparative study of Italy and Germany
No full textAcademics and policymakers recognize the growing importance of subjective financial well-being for emerging adults, yet little is known about the factors influencing the subjective financial well-being perceived by the emerging adult population. We aim to investigate the role of socio-demographic characteristics (job type, age, country of residence), individual differences in financial knowledge (financial literacy), skills (financial behavior), cognitive response styles (impulsiveness, future orientation, and maximization), and attitudinal components (trust in governmental institutions and financial professionals) in shaping subjective financial well-being among emerging adults in Italy and Germany, representing the Mediterranean and Northern models of the transitions to adulthood, respectively. A sample of 385 participants residing in Italy ( n = 193) and Germany ( n = 192) voluntarily participated in an online survey. Variables such as trust and maximization were incorporated into a prior financial well-being model to assess their relevance in predicting subjective financial well-being. In Model 1, variables from the prior theoretical model (socio-demographic characteristics, financial literacy, financial behavior, impulsiveness, and future orientation) were analyzed. In Model 2, trust and maximization were added as predictors of subjective financial well-being. Results revealed that the inclusion of these variables improved the model fit, and further confirmed the significant role of age, financial behavior (specifically, caring for financial matters), impulsiveness, future orientation, and trust in governmental institutions in subjective financial well-being.publishe
Drivers of female power in bonobos
No full textIn mammals, female dominance over males is a rare phenomenon. However, recent findings indicate that even in species with sexual dimorphism biased towards males, females sometimes occupy high status. Here we test three main hypotheses explaining intersexual power relationships, namely the self-reinforcing effects of winning and losing conflicts, the strength of mate competition, and female coalition formation. We test these for bonobos (Pan paniscus), one of our closest living relatives, where females have high status relative to males despite male-biased size dimorphism. We compiled demographic and behavioral data of 30 years and 6 wild living communities. Our results only support predictions of the female coalition hypothesis. We found that females target males in 85% of their coalitions and that females occupy higher ranks compared to males when they form more frequent coalitions. This result indicates that female coalition formation is a behavioral tool for females to gain power over males.publishe
Public Anthropology : Wissenspraktiken und gesellschaftliche Interventionen der ethnologischen Fächer
No full textpublishe
Non-Hermitian Topology in Multiterminal Superconducting Junctions
No full textRecent experimental advancements in dissipation control have yielded significant insights into non-Hermitian Hamiltonians for open quantum systems. Of particular interest are the topological characteristics exhibited by these non-Hermitian systems, that arise from exceptional points—distinct degeneracies unique to such systems. In this Letter, we focus on Andreev bound states in multiterminal Josephson junctions with non-Hermiticity induced by normal metal or ferromagnetic leads. By investigating several systems of different synthetic dimensions and symmetries, we predict fragile and stable non-Hermitian topological phases in these engineered superconducting systems.publishe