Leiden University
  • Leiden, Netherlands
Recent publications
Background: Recent years have shown an increased application of prospective trajectory-oriented approaches to posttraumatic stress disorder (PTSD). Although women are generally considered at increased PTSD risk, sex and gender differences in PTSD symptom trajectories have not yet been extensively studied. Objective: To perform an in-depth investigation of differences in PTSD symptom trajectories across one-year post-trauma between men and women, by interpreting the general trends of trajectories observed in sex-disaggregated samples, and comparing within-trajectory symptom course and prevalence rates. Method: We included N = 554 participants (62.5% men, 37.5% women) from a multi-centre prospective cohort of emergency department patients with suspected severe injury. PTSD symptom severity was assessed at 1, 3, 6, and 12 months post-trauma, using the Clinician-Administered PTSD Scale for DSM-IV. Latent growth mixture modelling on longitudinal PTSD symptoms was performed within the sex-disaggregated whole samples. Bayesian modelling with informative priors was applied for reliable model estimation, considering the imbalanced prevalence of the expected latent trajectories. Results: In terms of general trends, the same trajectories were observed for men and women, i.e. resilient, recovery, chronic symptoms and delayed onset. Within-trajectory symptom courses were largely comparable, but resilient women had higher symptoms than resilient men. Sex differences in prevalence rates were observed for the recovery (higher in women) and delayed onset (higher in men) trajectories. Model fit for the sex-disaggregated samples was better than for the whole sample, indicating preferred application of sex-disaggregation. Analyses within the whole sample led to biased estimates of overall and sex-specific trajectory prevalence rates. Conclusions: Sex-disaggregated trajectory analyses revealed limited sex differences in PTSD symptom trajectories within one-year post-trauma in terms of general trends, courses and prevalence rates. The observed biased trajectory prevalence rates in the whole sample emphasize the necessity to apply appropriate statistical techniques when conducting sex-sensitive research.
Background Under strong sexual selection, certain species evolve distinct intrasexual, alternative reproductive tactics (ARTs). In many cases, ARTs can be viewed as environmentally-cued threshold traits, such that ARTs coexist if their relative fitness alternates over the environmental cue gradient. Surprisingly, the chemical ecology of ARTs has been underexplored in this context. To our knowledge, no prior study has directly quantified pheromone production for ARTs in a male-polymorphic species. Here, we used the bulb mite—in which males are either armed fighters that kill conspecifics, or unarmed scramblers (which have occasionally been observed to induce mating behavior in other males)—as a model system to gain insight into the role of pheromones in the evolutionary maintenance of ARTs. Given that scramblers forgo investment into weaponry, we tested whether scramblers produce higher quantities of the putative female sex-pheromone α-acaridial than fighters, which would improve the fitness of the scrambler phenotype through female mimicry by allowing avoidance of aggression from competitors. To this end, we sampled mites from a rich and a poor nutritional environment and quantified their production of α-acaridial through gas chromatography analysis. Results We found a positive relationship between pheromone production and body size, but males exhibited a steeper slope in pheromone production with increasing size than females. Females exhibited a higher average pheromone production than males. We found no significant difference in slope of pheromone production over body size between fighters and scramblers. However, scramblers reached larger body sizes and higher pheromone production than fighters, providing some evidence for a potential female mimic strategy adopted by large scramblers. Pheromone production was significantly higher in mites from the rich nutritional environment than the poor environment. Conclusion Further elucidation of pheromone functionality in bulb mites, and additional inter- and intrasexual comparisons of pheromone profiles are needed to determine if the observed intersexual and intrasexual differences in pheromone production are adaptive, if they are a by-product of allometric scaling, or diet-mediated pheromone production under weak selection. We argue chemical ecology offers a novel perspective for research on ARTs and other complex life-history traits.
Chinese herbal medicines (CHMs) have unique advantages in the prevention and treatment of diseases, which are widely recognized in the world. More and more CHMs are becoming increasingly popular in the international markets. However, the quality control of CHMs is a significant issue for their acceptance and recognition in the international market. This review mainly focuses on the quality requirements for CHMs to enter the European Union (EU) market. Both Chinese and European regulations and quality controls are compared. Firstly, the EU medicinal regulatory system and relevant regulations were reviewed. Secondly, the key factors of the quality control of CHMs, including Chinese herbal drugs, extracts and products were compared with those of European herbal medicines in the EU market. Subsequently, three main registration routes for herbal medicinal products including Chinese herbal medicinal products entering the EU were introduced. Furthermore, the legal status of traditional Chinese medicine granules in the EU was also discussed. Through the comparison of the key quality factors for CHMs in China and the EU, the similarities and differences in terms of quality requirements and regulations are addressed, which provides a reference for the development of CHMs into the EU market.
Cargo ships navigating global waters are required to be sufficiently safe and compliant with international treaties. Governmental inspectorates currently assess in a rule-based manner whether a ship is potentially noncompliant and thus needs inspection. One of the dominant ship characteristics in this assessment is the ‘colour’ of the flag a ship is flying, where countries with a positive reputation have a so-called ‘white flag’. The colour of a flag may disproportionately influence the inspector, causing more frequent and stricter inspections of ships flying a non-white flag, resulting in confirmation bias in historical inspection data. In this paper, we propose an automated approach for the assessment of ship noncompliance, realising two important contributions. First, we reduce confirmation bias by using fair classifiers that decorrelate the flag from the risk classification returned by the model. Second, we extract mobility patterns from a cargo ship network, allowing us to derive meaningful features for ship classification. Crucially, these features model the behaviour of a ship, rather than its static properties. Our approach shows both a higher overall prediction performance and improved fairness with respect to the flag. Ultimately, this work enables inspectorates to better target noncompliant ships, thereby improving overall maritime safety and environmental protection.
Dissociation is a complex phenomenon, which occurs in various clinical conditions, including dissociative disorders, (complex) post-traumatic stress disorder (CPTSD, PTSD), and borderline personality disorder (BPD). Traumatic stress is considered an important risk factor, while the etiology of dissociation is still debated. Next to traumatic experiences, temperamental and neurobiological vulnerabilities seem to contribute to the development of dissociation. Stress-related dissociation is a prevalent symptom of BPD, which may interfere with psychosocial functioning and treatment outcome. More research in the field is strongly needed to improve the understanding and management of this complex phenomenon. This article collection brings together research on dissociation and trauma, with a special focus on BPD or sub-clinical expressions of BPD. In this editorial, recent conceptualizations of dissociation and relevant previous research are introduced in order to provide a framework for this novel research.
As combinatorial optimization is one of the main quantum computing applications, many methods based on parameterized quantum circuits are being developed. In general, a set of parameters are being tweaked to optimize a cost function out of the quantum circuit output. One of these algorithms, the Quantum Approximate Optimization Algorithm stands out as a promising approach to tackling combinatorial problems. However, finding the appropriate parameters is a difficult task. Although QAOA exhibits concentration properties, they can depend on instances characteristics that may not be easy to identify, but may nonetheless offer useful information to find good parameters. In this work, we study unsupervised Machine Learning approaches for setting these parameters without optimization. We perform clustering with the angle values but also instances encodings (using instance features or the output of a variational graph autoencoder), and compare different approaches. These angle-finding strategies can be used to reduce calls to quantum circuits when leveraging QAOA as a subroutine. We showcase them within Recursive-QAOA up to depth 3 where the number of QAOA parameters used per iteration is limited to 3, achieving a median approximation ratio of 0.94 for MaxCut over 200 Erdős-Rényi graphs. We obtain similar performances to the case where we extensively optimize the angles, hence saving numerous circuit calls.
Superconductivity is abundant near quantum critical points, where fluctuations suppress the formation of Fermi liquid quasiparticles and the BCS theory no longer applies. Two very distinct approaches have been developed to address this issue: quantum-critical Eliashberg theory and holographic superconductivity. The former includes a strongly retarded pairing interaction of ill-defined fermions, the latter is rooted in the duality of quantum field theory and gravity theory. We demonstrate that both are different perspectives of the same theory. We derive holographic superconductivity in form of a gravity theory with emergent space-time from a quantum many-body Hamiltonian—the Yukawa Sachdev-Ye-Kitaev model—where the Eliashberg formalism is exact. Exploiting the power of holography, we then determine the dynamic pairing susceptibility of the model. Our holographic map comes with the potential to use quantum gravity corrections to go beyond the Eliashberg regime.
The brain undergoes profound development across childhood and adolescence, including continuous changes in brain morphology, connectivity, and functioning that are, in part, dependent on one’s experiences. These neurobiological changes are accompanied by significant changes in children’s and adolescents’ cognitive learning. By drawing from studies in the domains of reading, reinforcement learning, and learning difficulties, we present a brief overview of methodological approaches and research designs that bridge brain- and behavioral research on learning. We argue that ultimately these methods and designs may help to unravel questions such as why learning interventions work, what learning computations change across development, and how learning difficulties are distinct between individuals.
Tertiary outpatient ophthalmology clinics are high-risk environments for COVID-19 transmission, especially retina clinics, where regular follow-up is needed for elderly patients with multiple comorbidities. Intravitreal injection therapy (IVT) for chronic macular diseases, is one of the most common procedures performed, associated with a significant burden of care because of the vigorous treatment regimen associated with multiple investigations. While minimizing the risk of COVID-19 infection transmission is a priority, this must be balanced against the continued provision of sight-saving ophthalmic care to patients at risk of permanent vision loss. This review aims to give evidence-based guidelines on managing IVT during the COVID-19 pandemic in common macular diseases such as age-related macular degeneration, diabetic macula edema and retinal vascular disease and to report on how the COVID-19 pandemic has affected IVT practices worldwide. To illustrate some real-world examples, 18 participants in the International Retina Collaborative, from 15 countries and across four continents, were surveyed regarding pre- and during- COVID-19 pandemic IVT practices in tertiary ophthalmic centers. The majority of centers reported a reduction in the number of appointments to reduce the risk of the spread of COVID-19 with varying changes to their IVT regimen to treat various macula diseases. Due to the constantly evolving nature of the COVID-19 pandemic, and the uncertainty about the normal resumption of health services, we suggest that new solutions for eye healthcare provision, like telemedicine, may be adopted in the future when we consider new long-term adaptations required to cope with the COVID-19 pandemic.
Concentrated solar power (CSP) can be a flexible renewable resource on electric grids. Here we assess the direct and upstream socio-economic and environmental impacts of the projected deployment of CSP in China and Europe, using Input-Output Analysis. We first quantify the CSP experience curve, finding a learning rate of ∼16%, and combine this with future projections for installed capacity from China's National Development and Reform Commission and the International Energy Agency. We find employment intensities of 4.2 and 2.3 person-year/GWh in China and Europe, respectively (higher than PV and wind). The carbon emission intensity of CSP is currently higher than alternatives but this gap may narrow through learning. Carbon intensities are estimated at 129.7 and 99.8 gCO2eq/kWh in 2020 (in China and Europe, respectively) and could drop to 40.4 and 31.1 gCO2eq/kWh by 2050 given the projected expansion. We discuss the importance of including both environmental and socio-economic dimensions when assessing the impact of energy technologies and provide context for the role of CSP in the energy transition.
Soil organic carbon (SOC) sequestration through the application of organic amendments (OAs) is considered an important strategy to offset anthropogenic Cv93..0O2 emissions while simultaneously enhancing soil quality and food security. The efficiency of SOC sequestration, however, depends on the priming effect which is influenced by interactions of OA composition with soil microbial response variables (MRVs). Yet, there remain large uncertainties surrounding the mechanisms and relationships defining these interactions, hampering the identification of OAs most effective for SOC sequestration and hindering the inclusion of OA dynamics in soil carbon models. In this study therefore, we performed an integrated assessment of these interactions for a cropland soil amended with wood chips, waterway residues, and isotopically enriched road-verge grasses, compost, and bokashi. Changes in 11 microbial properties and priming effects (for isotopically labelled OAs) were monitored for 150 days and related to 22 characterizations of OA composition. We demonstrate that i) hot water extractable to total carbon ratios of OAs are superior predictors of priming effects, ii) dissolvable to hot-water extractable carbon ratios are most closely related to variation in MRV expressions, and iii) priming effects correlate significantly with changes in several MRVs. Findings advocate for the adoption of energetic principles in modelling and predicting microbially-mediated soil carbon dynamics and suggest that application of OAs with high hot water to total carbon concentrations – potentially achievable by composting, but not fermenting, OAs prior to application – can allow for more efficient SOC sequestration.
When a train passes a red aspect, this is called a Signal Passed at Danger event or SPAD. Sometimes it is easy to identify the SPAD cause but in other cases it is unclear why the incident occurred, especially if the system operated as usual and the train driver was trained and experienced just like his or her colleagues. In previous research, train driver deceleration behaviour has been shown to be influenced by frequent exposure in the previous 14 days to less restrictive and visually similar signal aspects in the same location. Previous exposure can contribute to SPAD causation unless the initial insufficient deceleration is corrected in time. Six years of SPAD data and red aspect approaches in the Netherlands was used to test whether previous exposure to yellow:number aspects corresponds with a statistically significant increase in SPAD incidents if there is a small window for correction available to drivers. The permitted track speed and signal distance influence the size of this window. The results provide evidence for previous exposure as a cause for SPADs and details to identify locations with increased SPAD probability. Changes in infrastructure and timetable design or adding safety measures for these locations can prevent future SPADs.
Cross cultural neuroimaging work has demonstrated differences in neural correlates of some cognitive processes between individuals from different cultures, often comparing American and Chinese subjects. In contrast, a limited number of studies examined Arab and/or Filipino participants. This fMRI study aimed to demonstrate neural activations during animal and tool picture naming by 18 healthy Arabs and 18 healthy Filipino participants. In animal naming contrasted with tool naming, Arabs preferentially activated regions in the right lateral occipital and fusiform cortices, whereas Filipinos recruited bilateral visual areas. Cross-group comparisons of animal naming revealed that Arabs recruited right visual areas more than Filipinos, who in turn recruited the cerebellum more than Arabs. In tool naming, Arabs preferentially activated a predominantly left frontoparietal network, whereas no regions were identified in Filipinos, and no differences in activation between groups were found. Using a low-demand picture-naming task, this study revealed category-specific neural activations during picture naming by Arabs and Filipinos, as well as between-group differences in animal naming. The results suggest that Arabs and Filipinos may have culture-specific differences in processing animate and inanimate pictures, and caution against generalizing findings from the more commonly studied populations, especially in verbal tasks such as picture naming.
Previous studies have shown that the way in which infants perceive and explore the world changes as they transition from crawling to walking. Infant walking onset generally precedes advances in cognitive development such as accelerated language growth. However, the underlying mechanism explaining this association between walking experience and cognition is largely unknown. Selective attention is a key factor underlying learning across multiple domains. We propose that the altered visual input that infants obtain as they transition to walking relates to selective attention development and that advances in selective attention may potentially explain previously reported advances in other cognitive domains. As a first step in testing this hypothesis, we investigated how walking experience relates to selective attention. In Study 1, performance of 14-month-old crawlers, novice walkers, and expert walkers was compared on a visual search eye-tracking task (N = 47), including feature and conjunction (effortful) items. Walkers outperformed crawlers on the task in general, and effortful search was enhanced in expert walkers as compared with novice walkers, after controlling for crawling onset and general developmental differences occurring before walking onset. In Study 2, earlier walking onset was related to better visual search performance in 2-year-olds (N = 913). The association appeared to be due to the difference between the 10% latest walkers and the early/average walkers. Taken together, the results of these studies show that walking experience relates to advances in selective attention. This association shows a specific timing in development; it is mainly seen relatively close to the age of walking onset.
Offshore wind energy (OWE) is a cornerstone of future clean energy development. Yet, research into global OWE material demand has generally been limited to few materials and/or low technological resolution. In this study, we assess the primary raw material demand and secondary material supply of global OWE. It includes a wide assortment of materials, including bulk materials, rare earth elements, key metals, and other materials for manufacturing offshore wind turbines and foundations. Our OWE development scenarios consider important drivers such as growing wind turbine size, introducing new technologies, moving further to deep waters, and wind turbine lifetime extension. We show that the exploitation of OWE will require large quantities of raw materials from 2020 to 2040: 129–235 million tonnes (Mt) of steel, 8.2–14.6 Mt of iron, 3.8–25.9 Mt of concrete, 0.5–1.0 Mt of copper and 0.3–0.5 Mt of aluminium. Substantial amounts of rare earth elements will be required towards 2040, with up to 16, 13, 31 and 20 fold expansions in the current Neodymium (Nd), Dysprosium (Dy), Praseodymium (Pr) and Terbium (Tb) demand, respectively. Closed-loop recycling of end-of-life wind turbines could supply a maximum 3% and 12% of total material demand for OWE from 2020 to 2030, and 2030 to 2040, respectively. Moreover, a potential lifetime extension of wind turbines from 20 to 25 years would help to reduce material requirements by 7–10%. This study provides a basis for better understanding future OWE material requirements and, therefore, for optimizing future OWE developments in the ongoing energy transition.
The ecological safety problems caused by nitrogen pollution in water have attracted much attention. An organic carbon source is the key factor that restricts nitrogen removal in low COD/total nitrogen (C/N) sewage. In this study, iron‑carbon micro-electrolysis carrier was used for micro-electrolysis combined with biological denitrification (MEBD) of samples under low C/N conditions (C/N = 1.33). The nitrogen removal performance, the factors influencing nitrogen removal, and the underlying mechanisms of the removal system are studied using the response surface curve method and high-throughput sequencing. The results showed that when pH was 7, the dosage of denitrifying bacteria was 5%, and the dosage of iron‑carbon was 10%, the optimal denitrification effect for low C/N wastewater was 97.86% and 97.72% for total nitrogen and COD removal in 20 days, respectively. The addition of an iron‑carbon filler changed the community abundance and species diversity in MEBD system, and the structure of the dominant denitrifying bacteria changed. Moreover, hydrogen autotrophic denitrifying bacteria had been identified in the system. The synergistic effect of MEBD coupled denitrification system was due to the combined action of autotrophic denitrification, heterotrophic denitrification, micro–electrolysis, and electrochemical reduction. These findings provide a theoretical basis and technical support for nitrogen remediation of low C/N sewage.
Supergenes are tightly linked sets of loci that are inherited together and control complex phenotypes. While classical supergenes—governing traits such as wing patterns in Heliconius butterflies or heterostyly in Primula —have been studied since the Modern Synthesis, we still understand very little about how they evolve and persist in nature. The genetic architecture of supergenes is a critical factor affecting their evolutionary fate, as it can change key parameters such as recombination rate and effective population size, potentially redirecting molecular evolution of the supergene in addition to the surrounding genomic region. To understand supergene evolution, we must link genomic architecture with evolutionary patterns and processes. This is now becoming possible with recent advances in sequencing technology and powerful forward computer simulations. The present theme issue brings together theoretical and empirical papers, as well as opinion and synthesis papers, which showcase the architectural diversity of supergenes and connect this to critical processes in supergene evolution, such as polymorphism maintenance and mutation accumulation. Here, we summarize those insights to highlight new ideas and methods that illuminate the path forward for the study of supergenes in nature. This article is part of the theme issue ‘Genomic architecture of supergenes: causes and evolutionary consequences’.
Supergenes offer spectacular examples of long-term balancing selection in nature, but their origin and maintenance remain a mystery. Reduced recombination between arrangements, a critical aspect of many supergenes, protects adaptive multi-trait phenotypes but can lead to mutation accumulation. Mutation accumulation can stabilize the system through the emergence of associative overdominance (AOD), destabilize the system, or lead to new evolutionary outcomes. One outcome is the formation of maladaptive balanced lethal systems, where only heterozygotes remain viable and reproduce. We investigated the conditions under which these different outcomes occur, assuming a scenario of introgression after divergence. We found that AOD aided the invasion of a new supergene arrangement and the establishment of a polymorphism. However, this polymorphism was easily destabilized by further mutation accumulation, which was often asymmetric, disrupting the quasi-equilibrium state. Mechanisms that accelerated degeneration tended to amplify asymmetric mutation accumulation between the supergene arrangements and vice-versa. As the evolution of balanced lethal systems requires symmetric degeneration of both arrangements, this leaves only restricted conditions for their evolution, namely small population sizes and low rates of gene conversion. The dichotomy between the persistence of polymorphism and degeneration of supergene arrangements likely underlies the rarity of balanced lethal systems in nature. This article is part of the theme issue ‘Genomic architecture of supergenes: causes and evolutionary consequences’.
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17,846 members
Gabriel Forn-Cuni
  • Institute of Biology Leiden
Zsuzsika Sjoerds
  • Institute of Psychology
Henk Dekker
  • Institute of Political Science
Johannes Jobst
  • Department of Physics
P.O. Box 9555, 2300 RB, Leiden, Netherlands
Head of institution
Ingrid van Biezen