University of Konstanz
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Fine-Grained HDR Image Quality Assessment From Noticeably Distorted to Very High Fidelity
No full textHigh dynamic range (HDR) and wide color gamut (WCG) technologies significantly improve color reproduction compared to standard dynamic range (SDR) and standard color gamuts, resulting in more accurate, richer, and more immersive images. However, HDR increases data demands, posing challenges for bandwidth efficiency and compression techniques. Advances in compression and display technologies require more precise image quality assessment, particularly in the high-fidelity range where perceptual differences are subtle. To address this gap, we introduce AIC-HDR2025, the first such HDR dataset, comprising 100 test images generated from five HDR sources, each compressed using four codecs at five compression levels. It covers the high-fidelity range, from visible distortions to compression levels below the visually lossless threshold. A subjective study was conducted using the JPEG AIC-3 test methodology, combining plain and boosted triplet comparisons. In total, 34,560 ratings were collected from 151 participants across four fully controlled labs. The results confirm that AIC-3 enables precise HDR quality estimation, with 95\% confidence intervals averaging a width of 0.27 at 1 JND. In addition, several recently proposed objective metrics were evaluated based on their correlation with subjective ratings. The dataset is publicly available at: https://github.com/jpeg-aic/AIC-HDR2025.publishe
Integration of parallel pathways for flight control in a hawkmoth reflects prevalence and relevance of natural visual cues
No full textAn animal’s behaviour is the result of multiple neural pathways acting in parallel, receiving information across and within sensory modalities at the same time. How these pathways are integrated, particularly when their individual outputs are in conflict, is key to understanding complex natural behaviours. We investigated this question in the visually guided flight of the hummingbird hawkmoth Macroglossum stellatarum
. These insects were recently shown to partition their visual field, using ventrolateral optic-flow cues to guide their flight like most insects, while the same stimuli in the dorsal visual field evoke a novel directional response. Using behavioural experiments which set the two pathways into conflict, we tested whether and how the ventrolateral and dorsal pathway integrate to guide hawkmoth flight. Combined with environmental imaging we demonstrate that the partitioning of the visual field followed the prevalence of visual cues in the hawkmoths’ natural habitats, while the integration hierarchy of the two pathways matched the relevance of these cues for the animals’ flight safety, rather than their magnitude in the experimental setup or in natural habitats. These results provide new mechanistic insights into the vision-based flight control of insects, and link these to their natural context. We anticipate our findings to be the starting point for comparative investigations into parallel pathways for flight guidance in insects from differently structured natural habitats.publishe
(Multivariate) k-SUM as Barrier to Succinct Computation
No full textHow does the time complexity of a problem change when the input is given succinctly rather than explicitly? We study this question for several geometric problems defined on a set X of N points in ℤd. As succinct representation, we choose a sumset (or Minkowski sum) representation: Instead of receiving X explicitly, we are given sets A,B of n points that define X as A+B = {a+b∣ a ∈ A,b ∈ B}.
We investigate the fine-grained complexity of this succinct version for several Õ(N)-time computable geometric primitives. Remarkably, we can tie their complexity tightly to the complexity of corresponding k-SUM problems. Specifically, we introduce as All-ints 3-SUM(n,n,k) the following multivariate, multi-output variant of 3-SUM: given sets A,B of size n and set C of size k, determine for all c ∈ C whether there are a ∈ A and b ∈ B with a+b = c. We obtain the following results:
1) Succinct closest L∞-pair requires time N1-o(1) under the 3-SUM hypothesis, while succinct furthest L∞-pair can be solved in time Õ(n).
2) Succinct bichromatic closest L∞-Pair requires time N1-o(1) iff the 4-SUM hypothesis holds.
3) The following problems are fine-grained equivalent to All-ints 3-SUM(n,n,k): succinct skyline computation in 2D with output size k and succinct batched orthogonal range search with k given ranges. This establishes conditionally tight Õ(min{nk, N})-time algorithms for these problems. We obtain further connections with All-ints 3-SUM(n,n,k) for succinctly computing independent sets in unit interval graphs. Thus, (Multivariate) k-SUM problems precisely capture the barrier for enabling sumset-succinct computation for various geometric primitives.publishe
Grime's CSR theory revisited : A whole-plant view of vascular plant functioning across contrasting environments
No full text1. To understand how plants adapt to environmental conditions within the constraints of trait trade-offs, Grime proposed the competitor, stress-tolerator and ruderal (CSR) ecological strategy theory. This framework categorizes species based on their responses to two key environmental factors: disturbance and stress. Despite its widespread use in ecological research, CSR theory has not yet been rigorously validated against species-specific environmental preferences, particularly for species beyond Great Britain. Additionally, the typical characteristics of these strategies, particularly in relation to root and flower traits, remain poorly understood.
2. We analysed a dataset of 7037 vascular plant species to investigate the relationships between CSR strategies (quantified using the ‘StrateFy’ tool) and environmental preferences, as well as their associations with 31 plant traits, encompassing above-ground vegetative, below-ground and reproductive traits, using canonical correspondence analyses. Furthermore, we explored the potential cascading links among environmental preferences, CSR strategies and functional traits using correlation analyses.
3. Our results revealed that CSR strategies, as reflected in CSR scores, are strongly correlated with species' environmental preferences for both stress and disturbance, and support Grime's hypothesis across a broad range of species and environmental conditions. Moreover, CSR strategies exhibit robust correlations with plant traits from roots to shoots. Specifically, C-selected species, which thrive in stable, nutrient-rich environments, are characterized by large seeds and bud banks; S-selected species often grow in light-rich environments and tolerate grazing, possess thicker leaves and often exhibit self-compatibility. In contrast, R-selected species, which dominate in highly disturbed, nutrient-rich habitats, form dense seed banks to maximize regeneration potential.
4. Synthesis. Our findings provide strong empirical validation of the CSR theory using an extensive species dataset and expand the number and types of traits that are significantly associated with the CSR axes. This study highlights the broad applicability of the CSR theory for understanding plant adaptation and ecological functioning, making it a valuable tool for research in community assembly, functional trait diversity and evolutionary ecology, particularly in the context of climate change and increasing human-induced disturbances.publishe
Politics and administration : Between productive convergence and counterproductive divergence?
No full textDie Trennung von Politik und Verwaltung ist der Regelfall, Ausnahmen von der Regel sind aber alltäglich. Sie betreffen Situationen, die nicht durch Routineentscheidungen zu bewältigen sind, und Strukturveränderungen der Verwaltung selbst, die gesetzliche Regelungen und eine entsprechende politische Vorbereitung erfordern. Die Trennlinie zwischen Politik und Verwaltung wird dann zu einer operativen Schnittstelle, an der die unterschiedlichen Logiken von Politik und Verwaltung nach Möglichkeit konvergieren sollten, aber auch divergieren können. Für beide Varianten nennt der Beitrag Beispiele aus dem Bereich des politisch-administrativen Krisenmanagements und verweist auf die koordinierende Wirkung strategischer Kommunikation.publishe
The impact of microplastics on small organism dispersal : mechanisms, risks, and research gaps
No full textMicroplastics (MPs), small plastic particles under 5 mm, are increasingly recognized for their environmental persistence and ubiquity across ecosystems. While research has long focused on MPs’ toxicity, their influence on the dispersal of small organisms, including fungal, bacterial, and viral pathogens and their vector species such as insects, is gaining attention. This perspective examines how MPs could act as carriers for microorganism dispersal via the formation of unique biofilms, termed as ‘plastisphere,’ which hosts diverse microbial communities and facilitates horizontal gene exchange, including antibiotic-resistant genes. We also explore indirect impacts, as MPs influence the physiology and life history traits of organisms, which can alter dispersal dynamics. Despite increasing interest, significant research gaps remain, particularly concerning MPs in terrestrial ecosystems and the effects of biofouled versus pristine MPs in natural settings. Additionally, inconsistent methodologies, such as the use of unrealistically high MP concentrations and the lack of control materials or systematic experimental design challenge current research, limiting a comprehensive risk assessment. Addressing these limitations is essential to accurately evaluate MPs’ role in the dispersal of small organisms and to inform potential policy measures.publishe
Mechanistic prediction of community composition across resource conditions and species richness
No full textPredicting species coexistence and community assembly is a central goal in ecology. Traditional methods, based on the effect of one species on another (e.g., Lotka-Volterra competition model), are sensitive to environmental context. This is because they ignore the fundamental processes that can be applied across environments. While mechanistic approaches offer promise, empirical tests remain rare. Here, we integrate a mechanistic consumer-resource model with the growth of 12 phytoplankton species in monoculture over a range of nitrate, ammonium or phosphorous concentrations. We find that the mechanistic approach accurately predicts the composition of 960 communities across species richness and resource conditions. We confirm by simulations, species competing for substitutable resources (nitrate vs. ammonium) exhibit greater diversity than those competing for essential resources (nitrate vs. phosphorus), especially when initial species richness is high. This is because, in competition for essential resources, each species is likely to consume less of the resource that is more limiting to its growth, which violates the mechanistic rule of coexistence that states that each species must consume more of the resource that more limit it. Our study highlights the power of the mechanistic approach in understanding and predicting species loss across environments and, ultimately, mitigating its pace.publishe
Reciprocal associations between confidence in getting social support and academic expectancies and subjective task values : Stronger for first‐generation and transfer students
No full textBackground
Social support is assumed to play a key role in motivation at university, particularly for disadvantaged students, such as first-generation and community college transfer students. However, longitudinal research investigating reciprocal associations between social support and motivation is lacking.
Aims
We examined such associations between confidence in getting support from faculty and peers and students' expectancies and subjective task values in their most difficult and most important course.
Sample
Data stemmed from two cohorts of undergraduate students (n = 320/417 in Fall 2019/2020) at a diverse Southern Californian university.
Methods
Students reported on their confidence in getting support and their expectancies and subjective task values at the beginning, in the middle and (only for motivation) at the end of the academic term.
Results
Results indicated no differences in confidence in getting support based on university generation or transfer student status. Cross-lagged panel models provided some evidence for reciprocal associations between students' confidence in getting support and their expectancies and subjective task values. Findings were similar across the Fall 2019 and Fall 2020 cohorts, providing support for the generalizability across in-person vs. remote learning settings. Longitudinal associations tended to be stronger for first-generation and transfer students.
Conclusions
Future research should, therefore, examine whether university programmes targeting social support are especially effective for disadvantaged students.publishe