University of Konstanz
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Dual-site M1-DLPFC anodal transcranial direct current stimulation is superior to single-site stimulation in improving self-paced endurance performance of cyclists
No full textEndurance performance relies on motor and executive control, mediated by the primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC). We hypothesized that dual-site anodal transcranial direct current stimulation (M1–DLPFC) would yield stronger effects on endurance performance, psychophysiological responses, and executive function during self-paced endurance task than single-site stimulation. Fourteen trained male cyclists participated in four randomized, double-blind, sham-controlled transcranial direct current stimulation sessions (M1, DLPFC, dual-site M1–DLPFC, sham; 2 mA, 20 min). After stimulation, they performed a 15-km self-paced cycling time trial. Heart rate, rating of perceived exertion, pleasure, and arousal were measured every 3 km, and executive function every 4 km. Endurance performance was defined as the time to completion. Dual-site M1–DLPFC was superior to M1, DLPFC, and sham in endurance performance. Both single-site stimulations also improved completion time relative to sham. Dual-site stimulation lowered heart rate versus sham and elicited the lowest ratings of perceived exertion, differing significantly from both single-site and sham conditions. Dual-site stimulation further elicited higher pleasure sensation and felt arousal at several distance points compared with sham and single-site conditions. It yielded superior cognitive performance in the backward counting task compared with all other conditions. Concurrent M1–DLPFC anodal transcranial direct current stimulation enhanced self-paced endurance performance, reduced perceived exertion, improved affective responses, and preserved cognitive function during prolonged exertion more effectively than single-site stimulation.
Clinical trial registry: IRCT20230729058958N1, registration date: 03.08.2023.publishe
Pollen cones of Afrocarpus and Podocarpus (Podocarpaceae, Coniferales) in the light of conifer evolution and Zimmermann's telome theory
No full textPollen cones from various species of Podocarpaceae were investigated and a new evolutionary model of coniferous male reproductive structures is proposed. The inflorescence-like groups of pollen cones are identified as dense pollen cone clusters. These clusters result from a significant reduction in the length of the internodes of the fertile shoot axis, coupled with a shift of the cones towards the distal end. There is strong evidence that the simple structure of each pollen cone originates from a markedly reduced pseudanthial structure. The lateral hyposporangiate microsporangiophores are dorsiventral synangia comprising numerous fused, stalked microsporangia. It is highly likely that the hyposporangiate structure evolved from an ancestral radial (= perisporangiate) condition. The distal, leaf-like scutellum is formed by one or more sterile microsporangia that are fused and compressed. Contrary to the widely held view, the scutellum is not the tip of a microsporophyll. Based on Zimmermann's telome theory it is demonstrated how microsporangia can be produced in the absence of a microsporophyll.publishe
Secant varieties of Segre-Veronese varieties ℙ<sup>m</sup> × ℙ<sup>n</sup> embedded by (1, 2) are non-defective for n ≫ m<sup>3</sup>, m ≥ 3
No full textWe prove that for any m ≥ 3, n ≫ m3, all secant varieties of the Segre-Veronese variety ℙm × ℙn have the expected dimension. This was already proved by Abo and Brambilla in the subabundant case, hence we focus on the superabundant case. We generalize an approach due to Brambilla and Ottaviani into a construction we call the inductant. With a combinatorial investigation of these constructions, the proof of non-defectivity reduces to checking a finite collection of base cases, which we verify using a computer-assisted proof.publishe
Social context shapes facial dynamics : human and machine decoding of conversation topics
No full textConversation is fundamental to the human species, with facial expressions playing a crucial role in establishing shared understanding within specific conversational contexts. We hypothesized that variations in conversation topics, differing in levels of tension and personal disclosure, would elicit distinct facial behavior dynamics. We assessed facial activity during two types of natural conversations with varying tension levels in triads of unacquainted individuals: "get-to-know-each-other" and “moral dilemma” discussions. Human observers classified the conversation type with 82.11% accuracy based on facial dynamics alone. Strikingly, a machine learning model using three facial action units (AUs 4, 6, and 12) during speech-free moments achieved comparable accuracy (82.14%). Further analyses revealed that the model relied on the temporal dynamics of these AUs to distinguish conversational contexts. These findings show that machine-based facial coding, coupled with deep learning, can infer conversational context from facial expressions, offering a scalable tool for analyzing natural social interaction.publishe
Addressing Missing Data in Accelerometer Studies : Evaluating the Performance of Imputation Methods for Longitudinal Data
No full textAdequate handling of missing data on physical activity assessments is crucial in longitudinal accelerometer studies. This study aimed to evaluate the effectiveness of various imputation methods for handling missing data in an empirical application which utilizes wearable accelerometers. We employed a simulation approach to assess performance under different missing data scenarios including Missing Completely at Random, Missing at Random, and Missing Not at Random for a longer study period (6 weeks). Our findings revealed that mean imputation and hot-deck imputation applied with a fine degree of matching criteria (participant, day of the week, and time of day) outperformed discard-based methods under Missing Completely at Random and Missing at Random conditions as they produced the smallest bias and best precision. Notably, no imputation methods performed well under Missing Not at Random scenarios. We recommend conducting simulation studies tailored to specific study designs to compare imputation methods, implement strategies for improving data quality, gather information on nonwear periods, and ensure continuous monitoring and participant compliance thereby reducing bias in activity level estimates. If a simulation study is not feasible, we recommend to impute data relying on mean or hot-deck approaches with the finest possible degree of matching criteria.publishe
Visual learning performance in free-flying honey bees is independent of sucrose and light responsiveness and depends on training context
No full textAssociative learning plays a fundamental role in the life of honey bees, especially in the context of foraging for food sources. This learning capacity can be investigated through controlled experiments conducted under laboratory, semi-natural, and near-natural conditions, to understand the general principles of learning and motivation. Honey bees can be trained to solve different elemental and non-elemental learning tasks by pairing a conditioned stimulus such as an odor with sucrose as an unconditioned stimulus and reward. Laboratory studies with restrained bees demonstrated that sucrose responsiveness is positively correlated with both elemental olfactory learning performance and responsiveness to stimuli of different sensory modalities, such as odors and visual stimuli. Here, we tested for the first time how responsiveness to sucrose and light is related to performance in elemental and non-elemental visual learning under free-flying conditions. Sensory responsiveness and learning proficiency did not correlate, nor did sucrose responsiveness correlate with responsiveness to light. These results indicate that relationships among responsiveness to sucrose and light and learning proficiency, as established under restrained laboratory conditions, may not translate to the natural behavior of bees in the field. This finding points toward the context-dependent importance of responsiveness to light and sucrose during associative learning under restrained or free-flying conditions.publishe
Passive environmental and group-level processes drive gut microbiome composition in a wild corvid
No full textBackground: The gut microbiome is known from laboratory studies to be essential to host function and sociality, yet comparatively little is known about this association in wild animals. In wild birds, the gut microbiome seems to be broadly driven by environmental factors, and there is mixed evidence for a link with sociality. Here, we describe the gut microbiome composition of the Siberian jay (Perisoreus infaustus), a highly social group-living and food-caching corvid of the Eurasian boreal forest.
Results: We present evidence of potential environment-related variation in the gut microbiome of wild Siberian jays. Environmental acquisition of microbes may be an important process shaping their gut microbiome composition based on similarities to the local environmental microbial community, for which we propose an environment–oral–gut route as a potential underlying mechanism. We also identify an unexpected group-level convergence, wherein social horizontal transmission of gut microbes may be an incidental consequence of reciprocal cache pilfering among group members.
Conclusions: While the ecological significance of gut microbiome variation in Siberian jays is still unclear, our results paint a picture of passive microbiome assembly resulting from a combination of environmental acquisition and social transmission in a wild bird species.publishe
Amenity Traps and Safety Illusions : the California Camp Fire of 2018
No full textThis chapter analyses the origins of the California Camp Fire of 2018, named after Camp Creek Road in Butte County, and its catastrophic consequences. The death toll of 86 people, mostly residents, made it the worst fire disaster in the US in the last 100 years until the even deadlier wildfire on the Hawaiian Island of Maui in August 2023. Based on the Butte County Grand Jury Camp Fire report of 2020, the Camp Fire Case Studies of the US National Institute of Standards and Technology (NIST) of 2021 and 2023, and contemporary media coverage, the chapter addresses the paradox that previously recommended measures of risk mitigation were omitted by local and state-level authorities whose commitment to prevention and the protection of lives and property was otherwise credible and strong. The analysis identifies various types of interacting causal mechanisms as both permissive conditions and immediate trigger factors that partly aggravated, partly mitigated the impact of the Camp Fire. Specifically, the chapter sheds light on the ambivalence surrounding social cohesion and resilient local communities with regard to risk mitigation affecting desirable amenities and familiar settlement patterns as well as learning and new alliances in the process of the post-disaster recovery.publishe
The role of epistemic drift in online civic discourse about science
No full textOur societies are experiencing an epistemic drift, that is a changing understanding of what it means to be “honest” and how to arrive at “truth”. This drift has increasingly replaced reliance on evidence and facts during truth-seeking with reliance on beliefs, feelings, and intuitions alone. This is especially important in civic discourse about science, which by its very nature relies on evidence over intuition and feelings. We posit that the role of epistemic drift in civic discourse about science is observable in online discussions and can be analyzed through their digital traces. Building on observational and experimental work, we propose a model in which epistemic drift fuels low-quality information sharing through its interplay with emotions. In this view, epistemic drift also drives online toxicity, which creates apparent polarization and erodes the quality of online civic discourse on scientific topics like health and climate change.publishe