Constructively describing orbit spaces of finite groups by few inequalities

Let G be a finite group acting linearly on Rn. A celebrated Theorem of Procesi and Schwarz gives an explicit description of the orbit space Rn//G as a basic closed semi-algebraic set. We give a new proof of this statement and another description as a basic closed semi-algebraic set using elementary tools from real algebraic geometry. Bröcker was able to show that the number of inequalities needed to describe the orbit space generically depends only on the group G. Here, we construct such inequalities explicitly for abelian groups and in the case where only one inequality is needed. Furthermore, we answer an open question raised by Bröcker concerning the genericity of his result.publishe

Trajectory data management : A data model and predicate logic with operators for spatio-temporal query processing

With recent sensor and tracking technology advances, the volume of available trajectory data is steadily increasing. Consequently, managing and analyzing trajectory data has seen significant interest from the research community. The challenges presented by trajectory data arise from their spatio-temporal nature as well as the uncertainty regarding locations between sampled points. In this paper, we present a formal spatio-temporal predicate logic with configurable strictness parameters and two novel operators: (1) a spatio-temporal selection operator for filtering trajectories, and (2) a spatio-temporal crop operator for extracting relevant sub-trajectories based on spatio-temporal predicates. Furthermore, we integrate a similarity-based join operators for flexible trajectory comparison. Finally, we show that our predicate logic is expressive enough to capture all spatial and temporal relations put forward by previous work.publishe

On the codimension of permanental varieties

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The texture-taste connection : Multimodal sensory neurons in fly larvae

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Programmed neurite degeneration in human central nervous system neurons driven by changes in NAD⁺ metabolism

Neurite degeneration (ND) precedes cell death in many neurodegenerative diseases. However, it remains unclear how this compartmentalized cell death process is orchestrated in the central nervous system (CNS). The establishment of a CNS axotomy model (using modified 3D LUHMES cultures) allowed us to study metabolic control of ND in human midbrain-derived neurons without the use of toxicants or other direct disturbance of cellular metabolism. Axotomy lead to a loss of the NAD+ synthesis enzyme NMNAT2 within 2 h and a depletion of NAD+ within 4-6 h. This process appeared specific, as isolated neurites maintained ATP levels and a coupled mitochondrial respiration for at least 6 h. In the peripheral nervous system (PNS) many studies observed that NAD+ metabolism, in particular by the NADase SARM1, plays a major role in the ND occurring after axotomy. Since neither ferroptosis nor necroptosis, nor caspase-dependent apoptosis seemed to be involved in neurite loss, we investigated SARM1 as potential executioner (or controller). Knock-down or expression of a dominant-negative isoform of SARM1 indeed drastically delayed ND. Various modifications of NAD+ metabolism known to modulate SARM1 activity showed the corresponding effects on ND. Moreover, supplementation with NAD+ attenuated ND. As a third approach to investigate the role of altered NAD+ metabolism, we made use of the WLD(s) protein, which has been found in a mutant mouse to inhibit Wallerian degeneration of axons. This protein, which has a stable NMNAT activity, and thus can buffer the loss of NMNAT2, protected the neurites by stabilizing neurite NAD+ levels. Thus CNS-type ND was tightly linked to neurite metabolism in multiple experimental setups. Based on this knowledge, several new strategies for treating neurodegenerative diseases can be envisaged.publishe

Gaze following in pigeons increases with the number of demonstrators

Gaze following, orienting one’s gaze in the same direction as another individual, is a key component of social attention across species, and expected to play an important role in group contexts. To investigate its collective dimension, this study tested whether the number of conspecifics providing a gaze cue influences gaze following in pigeons (Columba livia). Using motion capture to track fine-scale head and body movements, we presented attention-getting stimuli to subsets of pigeons (demonstrators), while others (observers) could not see them. Observer pigeons followed the gaze of demonstrators, specifically toward the target object rather than a perceptually similar distractor, and the frequency increased with the number of demonstrators. We found no evidence for nonlinear effects under our experimental conditions. In group-living species like pigeons, multiple individuals looking in the same direction may serve as a more reliable social signal, highlighting the critical role of collective context in animal social cognition.publishe

Indikation von Uferstrukturbelastungen durch Makrophyten und Makrozoobenthos an Seen in Brandenburg : Teil 2: Einfluss von Trophie (ACP) und Uferstruktur (HyMo) auf biologische Bewertungsmetriks und Zusammensetzung von Makrozoobenthos- (MZB) und Makrophytengemeinschaften (MPH) : Bericht der ARGE „Team Seeufer MMM“ für das Landesamt für Umwelt Brandenburg, Ref. W26, Projekt SuBoLakes (Az. 35825/01), AP 5 der Deutschen Bundesstiftung Umwelt (DBU)

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Facile construction of mechanically robust and highly osteogenic materials for bone regeneration

Hydrogel-based materials exhibit great potential in tissue engineering. However, their mechanical weakness limits applications in hard tissue regeneration, especially under load-bearing conditions. Although various strengthening strategies have been applied, the achieved mechanical response of hydrogels still lags behind the mechanics of natural bone. In this study, we present a novel mineralization approach to fabricate mechanically robust and highly osteogenic mineralized hydrogels. Cross-linking between deprotonated chains of poly(acrylic acid) (PAA) and divalent cations has led to formation of hydrogels with a compressive strength and elastic modulus of 0.3 ± 0.1 kPa and 1.3 ± 0.2 kPa, respectively. Subsequent in situ formation of nano-calcium hydroxide crystals remarkably increased the compressive strength and modulus to 7.9 ± 0.6 MPa and 339.3 ± 31.4 MPa, respectively, surpassing those of trabecular bone. Moreover, the mineralized hydrogels demonstrated remarkable osteogenic potential in vivo, exhibiting immunoregulatory activity, promoting early angiogenesis, and accelerating fracture healing at weeks 4 and 8. The mechanism of osteogenesis was further revealed by transcriptome sequencing, indicating that the mineralized hydrogels regulated the translation of extracellular matrix and biomineralization. Overall, our study presents a pioneering and cost-effective method for fabricating materials with exceptional mechanical strength and strong osteogenic properties, offering a promising avenue for load-bearing bone repair applications of hydrogel-based materials.publishe

Patients with borderline personality disorder show initially reduced psychophysiological relaxation levels but intact relaxation response

Introduction: Borderline Personality Disorder (BPD) is associated with psychological as well as physiological dysregulation in patients, including reduced parasympathetic activity at baseline and difficulties returning to baseline after a stressor. Whether this impacts the relaxation response independent of a stressor has so far not been investigated. Methods: In a within-subject design, we compared two relaxation interventions, a virtual reality nature video, and a paced breathing intervention. We assessed a female-only sample, with 20 BPD patients (meanage = 23.75 ± 4.39) during their inpatient treatment and 22 matched healthy controls (HC; meanage = 22.68 ± 2.68). Psychological relaxation was assessed with the Relaxation State Questionnaire (RSQ) and physiological relaxation with vagally mediated heart rate variability (HRV). Results: We employed multilevel models to test whether BPD significantly influenced the psychophysiological relaxation response. For psychological relaxation, we found an increase in RSQ scores in both groups in response to both interventions. The HC showed overall higher RSQ scores. For physiological relaxation, we found overall higher HRV values in the HC group but no differences in the relaxation response. Conclusion: BPD patients exhibit lower psychophysiological relaxation levels at baseline and throughout the experiment, while there was no significant difference in response to relaxation interventions when compared to HC. Future studies should focus on interventions targeting baseline psychophysiological relaxation in BPD patients.publishe

Testing Strategies for Metabolite-Mediated Neurotoxicity

Compounds, which rely on metabolism to exhibit toxicity, pose a challenge for next-generation risk assessment (NGRA). Since many of the currently available non-animal new approach methods (NAMs) lack metabolic activity, their use may lead to an underestimation of the true hazard to humans (false negative predictions). We explored here strategies to deal with metabolite-mediated toxicity in assays for developmental neurotoxicity. First, we present an overview of substances that may serve as potential positive controls for metabolite-related neurotoxicity. Then, we demonstrate, using the MitoMet (UKN4b) assay, which assesses the adverse effects of chemicals on neurites of human neurons, that some metabolites have a higher toxic potency than their parent compound. Next, we designed a strategy to integrate elements of xenobiotic metabolism into assays used for (developmental) neurotoxicity testing. In the first step of this approach, hepatic post-mitochondrial fractions (S9) were used to generate metabolite mixtures (“metabolisation module”). In the second step, these were applied to a NAM (exemplified by the UKN4b assay) to identify metabolite-mediated toxicity. We demonstrate the applicability and transferability of these approaches to other assays, by an exemplary study on the basis of the cMINC (UKN2) assay, another NAM of the developmental neurotoxicity in vitro battery. Based on the experience gained from these experiments, we discuss key issues to be addressed if this approach is to be used more broadly for NAM in the NGRA context.publishe