University of Groningen
  • Groningen, Netherlands
Recent publications
Pursuing rural electrification in developing countries through hybrid generation systems is constrained by a lack of suitable energy modelling tools. Few tools include geographical parameters relevant to capturing specific spatial and socio-economic circumstances. Even less are openly available and find applications for rural areas of developing countries. This work presents an integrated geospatial energy modelling framework based on an extended tool, the GISEle (GIS for rural electrification) model, which aims for a least-cost energy solution. GISEle is an open-source tool supporting rural electrification planning strategies and challenges through optimal hybrid microgrid integration. The developed framework is universally applicable and explains how the extended GISEle tool can be used to become suitable for analysing decentralised hybrid generation systems within the context of rural areas of developing countries. This presented framework includes:•Advancing the approach to proper data collection to better capture local specificities and (future) demand and reporting results in rural areas of developing countries; •Adding the Remote-Areas Multi-energy systems load Profiles (RAMP) to improve load demand assessments, while considering the impact of electrification on growing demand scenarios; •Linking the Soil and Water Assessment Tool (SWAT) model to allow for hydropower sizing in GISEle.
As organizations face an aging workforce, it is crucial to understand the role of leaders’ age in their interactions with employees. Seminal theories on aging cast age as a key factor shaping individuals’ interpersonal behaviors, for example when handling conflicts. We integrate this notion with insights from generativity research to investigate the role of leaders’ age in their active conflict management strategies through two distinct pathways. Depending on a leader’s generativity, leaders’ age may differentially shape both their perceptions of leader-member exchange (LMX) quality and their emotion regulation knowledge, thereby advancing either more constructive or more destructive approaches toward employee conflicts. Results from Study 1, a time-lagged study of 303 leaders, revealed that age is negatively related to their LMX perceptions and, thus, to leaders’ constructive approaches toward employee conflicts—but only among leaders with lower generativity. Study 2, a cross-sectional study of 84 leader-employee teams, revealed that leaders’ age is positively associated with their emotion regulation knowledge, which in turn is negatively related to their destructive conflict management—but only among leaders with higher generativity. Our findings reveal key mechanisms linking leader age to conflict management and underscore leader generativity as a crucial boundary condition in these relationships.
Coherent control has been achieved in atoms and small molecules in gas phase during the past few decades. An intriguing demonstration of coherent control is a so-called “dark pulse” that cancels 2-photon transition probabilities despite exposing the target to the full power spectrum of transform-limited laser pulses. However, for larger functional molecules in condensed phase at room temperature, ensemble measurements do typically not allow exerting full control over competing pathways due to the unavoidable influence of the surrounding (mostly complex) environment. Here, we demonstrate room-temperature coherent control exploiting a nonresonant 2-photon transition into a higher excited state of single conjugated polymer chains embedded in a disordered matrix, including proof-of-principle experiments on bulk films. To manipulate the 2-photon transition probability, we exploit complex pulse sequences, created by a systematically varied cosinusoidal spectral phase applied to the excitation laser spectrum. For single molecules, the phase-dependent response varies from molecule to molecule, which reflects the spectral heterogeneity (position, linewidth) of their 2-photon transitions. These data indicate that coherent control of single molecules requires optimization of parameters for each individual molecule. The experimental data are reproduced by a simple model that allows to directly retrieve the 2-photon absorption spectrum of each single molecule. Our coherent-control approach is a powerful and robust way to obtain spectral characteristics of higher excited states of single molecules and to manipulate the excited-state dynamics in condensed phase at room temperature. It holds the potential to be useful for the characterization of complex organic functional materials.
Complex coacervation is the phase separation of oppositely charged polyelectrolytes, resulting in a polymer-dense coacervate phase and a polymer-depleted supernatant phase. Coacervation is crucial for many biological processes and novel synthetic materials, where the environment is often filled with other neutral molecules (crowders). Yet, the complex role of crowders in complex coacervation has not been studied systematically under controlled conditions. We performed coarse-grained molecular dynamics simulations of coacervation in the presence of polymeric crowders of varying concentrations and chain lengths. While short crowders do not have any significant effect on coacervation, larger crowders stabilize the coacervate against added salt, increasing its critical salt concentration. The change in critical salt concentration saturates for long crowders at a value determined by the crowder concentration. Rescaling all phase diagrams by their critical salt concentration leads to a collapse of the data, which demonstrates a universal phase behavior. Our simulation indicates that the inability of crowder chains to mix with the polyelectrolytes is the driving force behind crowding effects. These testable predictions provide a first step toward a comprehensive understanding of crowding effects in complex coacervation.
Self-assembling amphiphilic cyanine dyes, such as C8S3, are promising candidates for energy storage and optoelectronic applications due to their efficient energy transport properties. C8S3 is known to self-assemble in water into double-walled J-aggregates. Thus far, the molecular self-assembly steps remain shrouded in mystery. Here, we employ a multiscale approach to unravel the first self-assembly step: dimerization. Our multiscale approach combines molecular dynamics simulations with quantum chemistry calculations to obtain a Frenkel exciton Hamiltonian, which we then use in spectral calculations to determine the absorption and two-dimensional electronic spectra of C8S3 monomer and dimer systems. We model these systems solvated in both water and methanol, validating our model with experiments in methanol solution. Our theoretical results predict a measurable anisotropy decay upon dimerization, which is experimentally confirmed. Our approach provides a tool for the experimental probing of dimerization. Moreover, molecular dynamics simulations reveal that the dimer conformation is characterized by the interaction between the hydrophobic aliphatic tails rather than the π–π stacking previously reported for other cyanine dyes. Our results pave the way for future research into the mechanism of molecular self-assembly in similar light-harvesting complexes, offering valuable insights for understanding and optimizing self-assembly processes for various (nano)technological applications.
Purpose Pancreatoduodenectomy (PD) is a challenging procedure which is associated with high morbidity rates. This study was performed to make an overview of risk factors included in risk stratification methods both logistic regression models and models based on artificial intelligence algorithms to predict postoperative pancreatic fistula (POPF) and other complications following PD and to provide insight in the extent to which these tools were validated. Methods Five databases were searched to identify relevant studies. Calculators, equations, nomograms, and artificial intelligence models that addressed POPF and other complications were included. Only PD resections were considered eligible. There was no exclusion of the minimally invasive techniques reporting PD resections. All other pancreatic resections were excluded. Results 90 studies were included. Thirty-five studies were related to POPF, thirty-five studies were related to other complications following PD and twenty studies were related to artificial intelligence predication models after PD. Among the identified risk factors, the most used factors for POPF risk stratification were the main pancreatic duct diameter (MPD) (80%) followed by pancreatic texture (51%), whereas for other complications the most used factors were age (34%) and ASA score (29.4%). Only 26% of the evaluated risk stratification tools for POPF and other complications were externally validated. This percentage was even lower for the risk models using artificial intelligence which was 20%. Conclusion The MPD was the most used factor when stratifying the risk of POPF followed by pancreatic texture. Age and ASA score were the most used factors for the stratification of other complications. Insight in clinically relevant risk factors could help surgeons in adapting their surgical strategy and shared decision-making. This study revealed that the focus of research still lies on developing new risk models rather than model validation, hampering clinical implementation of these tools for decision support.
Though there is mounting evidence that climate warming is altering trophic interactions between organisms, its effects on non-trophic interactions remain relatively undocumented. In seagrass systems, the bioturbating activity of infauna influences annual seagrass patch development by influencing seed burial depth and germination success as well as sediment properties. If bioturbation is altered by warming, consequences on seagrass may result. Here, we assessed how heatwaves alter seagrass seed burial depth and germination rates when no bioturbators (control), single bioturbators and mixtures of bioturbators of contrasting feeding activities are present. The three bioturbators manipulated were surface (top 1-2 cm of sediment) biodiffusor, the brown shrimp (Crangon crangon), the shallow (top 3–8 cm) diffusor, the common cockle, (Cerastoderma edule) and the upward (5–15 cm) conveyor, the polychaete, Cappitellidae spp. We applied two temperature treatments: (1) a present-day scenario set at the average summer temperature of seagrass habitat (17ºC); and (2) a heatwave scenario modelled on the maximum recorded temperature (26.6ºC). Under present-day conditions, seed burial was greater in the presence of bioturbators than the control where no infauna was added (42–74% vs. 33 ± 7%, respectively). Cockles had the greatest impact on seed burial amongst all the bioturbators. Under the heatwave scenario, seed burial in the mixed bioturbator treatment increased to match that of the cockle treatment. Cockles and polychaetes elevated the germination rates of buried seeds under present-day temperature, but not under the heatwave scenario. Overall, these results indicate that heatwaves have the potential both to amplify and disrupt non-trophic interactions, with implications for seagrass seed germination. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-025-05662-y.
The interconnecting links between individuals in an animal social network are often defined by discrete, directed behaviours, but where these are difficult to observe, a network link (edge) may instead be defined by individuals sharing a space at the same time, which can then be used to infer a social association. The method by which these associations are defined should be informed by the biological significance of edges, and therefore often vary between studies. Identifying an appropriate measure of association remains a challenge to behavioural ecologists. Here, we use automatically recorded feeder visit data from four bird systems to compare three methods to identify a social association: (1) strict time-window, (2) co-occurrence in a group, and (3) arrival-time. We tested the similarity of the resulting networks by comparing the repeatability and sensitivity of individuals’ social traits (network degree, strength, betweenness). We found that networks constructed using different methods but applying similar, ecologically relevant definitions of associations based on individuals’ spatio-temporal co-occurrence, showed similar characteristics. Our findings suggest that the different methods to construct animal social networks are comparable, but result in subtle differences driven by species biology and feeder design. We urge researchers to carefully evaluate the ecological context of their study systems when making methodological decisions. Specifically, researchers in ecology and evolution should carefully consider the biological relevance of an edge in animal social networks, and the implications of adopting different definitions.
Background Diagnosis in psychiatry faces familiar challenges. Validity and utility remain elusive, and confusion regarding the fluid and arbitrary border between mental health and illness is increasing. The mainstream strategy has been conservative and iterative, retaining current nosology until something better emerges. However, this has led to stagnation. New conceptual frameworks are urgently required to catalyze a genuine paradigm shift. Methods We outline candidate strategies that could pave the way for such a paradigm shift. These include the Research Domain Criteria (RDoC), the Hierarchical Taxonomy of Psychopathology (HiTOP), and Clinical Staging, which all promote a blend of dimensional and categorical approaches. Results These alternative still heuristic transdiagnostic models provide varying levels of clinical and research utility. RDoC was intended to provide a framework to reorient research beyond the constraints of DSM. HiTOP began as a nosology derived from statistical methods and is now pursuing clinical utility. Clinical Staging aims to both expand the scope and refine the utility of diagnosis by the inclusion of the dimension of timing. None is yet fit for purpose. Yet they are relatively complementary, and it may be possible for them to operate as an ecosystem. Time will tell whether they have the capacity singly or jointly to deliver a paradigm shift. Conclusions Several heuristic models have been developed that separately or synergistically build infrastructure to enable new transdiagnostic research to define the structure, development, and mechanisms of mental disorders, to guide treatment and better meet the needs of patients, policymakers, and society.
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30,641 members
Roelof A. Hut
  • Groningen Institute of Evolutionary Life Sciences (GELIFES)
Cristina Paulino
  • Groningen Biomolecular Sciences and Biotechnology Institute (GBB)
Michel MRF Struys
  • Department of Anaesthesiology
Roos Nieweg
  • Department of History
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