Hasselt University
  • Hasselt, Flanders, Belgium
Recent publications
Background Sepsis is a life-threatening organ dysfunction. A fast diagnosis is crucial for patient management. Proteins that are synthesized during the inflammatory response can be used as biomarkers, helping in a rapid clinical assessment or an early diagnosis of infection. The aim of this study was to identify biomarkers of inflammation for the diagnosis and prognosis of infection in patients with suspected sepsis. Methods In total 406 episodes were included in a prospective cohort study. Plasma was collected from all patients with suspected sepsis, for whom blood cultures were drawn, in the emergency department (ED), the department of infectious diseases, or the haemodialysis unit on the first day of a new episode. Samples were analysed using a 92-plex proteomic panel based on a proximity extension assay with oligonucleotide-labelled antibody probe pairs (OLink, Uppsala, Sweden). Supervised and unsupervised differential expression analyses and pathway enrichment analyses were performed to search for inflammatory proteins that were different between patients with viral or bacterial sepsis and between patients with worse or less severe outcome. Results Supervised differential expression analysis revealed 21 proteins that were significantly lower in circulation of patients with viral infections compared to patients with bacterial infections. More strongly, higher expression levels were observed for 38 proteins in patients with high SOFA scores (> 4), and for 21 proteins in patients with worse outcome. These proteins are mostly involved in pathways known to be activated early in the inflammatory response. Unsupervised, hierarchical clustering confirmed that inflammatory response was more strongly related to disease severity than to aetiology. Conclusion Several differentially expressed inflammatory proteins were identified that could be used as biomarkers for sepsis. These proteins are mostly related to disease severity. Within the setting of an emergency department, they could be used for outcome prediction, patient monitoring, and directing diagnostics. Trail registration number: clinicaltrial.gov identifier NCT03841162.
Background Spinal cord injury (SCI) elicits a robust neuroinflammatory reaction which, in turn, exacerbates the initial mechanical damage. Pivotal players orchestrating this response are macrophages (Mφs) and microglia. After SCI, the inflammatory environment is dominated by pro-inflammatory Mφs/microglia, which contribute to secondary cell death and prevent regeneration. Therefore, reprogramming Mφ/microglia towards a more anti-inflammatory and potentially neuroprotective phenotype has gained substantial therapeutic interest in recent years. Interleukin-13 (IL-13) is a potent inducer of such an anti-inflammatory phenotype. In this study, we used genetically modified Mφs as carriers to continuously secrete IL-13 (IL-13 Mφs) at the lesion site. Methods Mφs were genetically modified to secrete IL-13 (IL-13 Mφs) and were phenotypically characterized using qPCR, western blot, and ELISA. To analyze the therapeutic potential, the IL-13 Mφs were intraspinally injected at the perilesional area after hemisection SCI in female mice. Functional recovery and histopathological improvements were evaluated using the Basso Mouse Scale score and immunohistochemistry. Neuroprotective effects of IL-13 were investigated using different cell viability assays in murine and human neuroblastoma cell lines, human neurospheroids, as well as murine organotypic brain slice cultures. Results In contrast to Mφs prestimulated with recombinant IL-13, perilesional transplantation of IL-13 Mφs promoted functional recovery following SCI in mice. This improvement was accompanied by reduced lesion size and demyelinated area. The local anti-inflammatory shift induced by IL-13 Mφs resulted in reduced neuronal death and fewer contacts between dystrophic axons and Mφs/microglia, suggesting suppression of axonal dieback. Using IL-4Rα-deficient mice, we show that IL-13 signaling is required for these beneficial effects. Whereas direct neuroprotective effects of IL-13 on murine and human neuroblastoma cell lines or human neurospheroid cultures were absent, IL-13 rescued murine organotypic brain slices from cell death, probably by indirectly modulating the Mφ/microglia responses. Conclusions Collectively, our data suggest that the IL-13-induced anti-inflammatory Mφ/microglia phenotype can preserve neuronal tissue and ameliorate axonal dieback, thereby promoting recovery after SCI.
Background The contribution of native or modified oligodendroglia-derived extracellular vesicles (OL-EVs) in controlling chronic inflammation is poorly understood. In activated microglia, OL-EVs contribute to the removal of cytotoxic proteins following a proteotoxic stress. Intracellular small heat shock protein B8 (HSPB8) sustain this function by facilitating autophagy and protecting cells against oxidative stress mediated cell death. Therefore, secretion of HSPB8 in OL-EVs could be beneficial for neurons during chronic inflammation. However, how secreted HSPB8 contribute to cellular proteostasis remains to be elucidated. Methods We produced oligodendroglia-derived EVs, either native (OL-EVs) or HSPB8 modified (OL-HSPB8-EVs), to investigate their effects in controlling chronic inflammation and cellular homeostasis. We analyzed the impact of both EV subsets on either a resting or activated microglial cell line and on primary mixed neural cell culture cells. Cells were activated by stimulating with either tumor necrosis factor-alpha and interleukin 1-beta or with phorbol-12-myristate-13-acetate. Results We show that OL-EVs and modified OL-HSPB8-EVs are internalized by C20 microglia and by primary mixed neural cells. The cellular uptake of OL-HSPB8-EVs increases the endogenous HSPB8 mRNA expression. Consistently, our results revealed that both EV subsets maintained cellular homeostasis during chronic inflammation with an increase in the formation of autophagic vesicles. Both EV subsets conveyed LC3B-II and BAG3 autophagy markers with an enhanced effect observed for OL-HSPB8-EVs. Moreover, stimulation with either native or modified OL-HSPB8-EVs showed a significant reduction in ubiquitinated protein, reactive oxygen species and mitochondrial depolarization, with OL-HSPB8-EVs exhibiting a more protective effect. Both EV subsets did not induce cell death in the C20 microglia cell line or the primary mixed neural cultures. Conclusion We demonstrate that the functions of oligodendroglia secreted EVs enriched with HSPB8 have a supportive role, comparable to the native OL-EVs. Further development of engineered oligodendroglia derived EVs could be a novel therapeutic strategy in countering chronic inflammation.
Purpose It is usually assumed that the severity of varus osteoarthritis (OA) of the knee is correlated with the axis deviation of the limb. Despite this, there is currently no clear radiographic definition to define a so-called ‘high degree’ varus knee, which is characterized by a pronounced lateral ligamentous laxity. The purpose of this study was to radiographically determine if the lateral joint line opening (LJLO) is an indicative parameter when defining so-called high grade varus knees. Methods Two hundred forty Full length radiographs of patients with end-stage varus osteoarthritis who were scheduled for Total knee arthroplasty (TKA) were evaluated. The Hip-knee-ankle-angle (HKA-angle), Joint-line-convergence-angle (JLCA) and the lateral joint line opening were measured. The lateral joint line opening is the shortest distance between the lateral tibial plateau and the deepest point of the lateral femoral condyle. Linear regression models were used to investigate the relationships between the radiographic measurements. Results Hip-knee-angle-angle, joint-line-conversion-angle, and lateral joint line opening were all positively correlated ( p < 0.001). An increase of 1 mm lateral joint line opening causes an increase of 0.6° joint-line-conversion-angle ( p = 0.029) below a cut-off point of 4.7 mm. For lateral opening values beyond 4.7 mm, the gradient increased to 1.2 ( p < 0.001). A lateral joint line opening of 4.7 mm corresponds to a hip-knee-ankle-angle of 6.0° (95% CI [5.5; 6.5]). Conclusion A lateral joint line opening of more than 5 mm in end-stage OA knees is indicative of increased lateral joint laxity. Those knees can be radiographically classified as so-called ‘high-grade’ varus knees. Level of evidence Therapeutic study, Level III.
The recent paper “Reward is Enough” by Silver, Singh, Precup and Sutton posits that the concept of reward maximisation is sufficient to underpin all intelligence, both natural and artificial, and provides a suitable basis for the creation of artificial general intelligence. We contest the underlying assumption of Silver et al. that such reward can be scalar-valued. In this paper we explain why scalar rewards are insufficient to account for some aspects of both biological and computational intelligence, and argue in favour of explicitly multi-objective models of reward maximisation. Furthermore, we contend that even if scalar reward functions can trigger intelligent behaviour in specific cases, this type of reward is insufficient for the development of human-aligned artificial general intelligence due to unacceptable risks of unsafe or unethical behaviour.
In this paper we initiate the study of the Chebyshev property of Abelian integrals generated by a non-generic turning point in planar slow-fast systems. Such Abelian integrals generalize the Abelian integrals produced by a slow-fast Hopf point (or generic turning point), introduced in Dumortier et al. (Discrete Contin Dyn Syst Ser S 2(4):723–781, 2009), and play an important role in studying the number of limit cycles born from the non-generic turning point.
Many aspects of our life are related to our mobility patterns and individuals can exhibit strong tendencies towards routine in their daily lives. Intrapersonal day-to-day variability in mobility patterns has been associated with mental health outcomes. The study aims were: (a) calculate intrapersonal day-to-day variability in mobility metrics for three cities; (b) explore interpersonal variability in mobility metrics by sex, season and city, and (c) describe intrapersonal variability in mobility and their association with perceived stress. Data came from the Physical Activity through Sustainable Transport Approaches (PASTA) project, 122 eligible adults wore location measurement devices over 7-consecutive days, on three occasions during 2015 (Antwerp: 41, Barcelona: 41, London: 40). Participants completed the Short Form Perceived Stress Scale (PSS-4). Day-to-day variability in mobility was explored via six mobility metrics using distance of GPS point from home (meters:m), distance travelled between consecutive GPS points (m) and energy expenditure (metabolic equivalents:METs) of each GPS point collected (n = 3,372,919). A Kruskal-Wallis H test determined whether the median daily mobility metrics differed by city, sex and season. Variance in correlation quantified day-to-day intrapersonal variability in mobility. Levene's tests or Kruskal-Wallis tests were applied to assess intrapersonal variability in mobility and perceived stress. There were differences in daily distance travelled, maximum distance from home and METS between individuals by sex, season and, for proportion of time at home also, by city. Intrapersonal variability across all mobility metrics were highly correlated; individuals had daily routines and largely stuck to them. We did not observe any association between stress and mobility. Individuals are habitual in their daily mobility patterns. This is useful for estimating environmental exposures and in fuelling simulation studies.
Purpose This study aimed to assess the prevalence of chronic low back pain (CLBP) and related biopsychosocial factors in urban and rural communities in Benin. Methods This is a population-based observational cross-sectional survey. An interviewer-administered electronic questionnaire was used to collect information on demographic, socio-economic, behavioral, and psychological factors relating to CLBP risk factors and medical history of participants. The numeric pain rating scale and the Beck Depression Inventory were used to assess pain intensity and the level of depression, respectively. Bivariate analyses were performed to investigate the association between sociodemographic, behavioral, and psychological factors and CLBP. Sequential multiple regression analyses were subsequently performed to predict the occurrence of CLBP. Results A total of 4320 participants, with a mean age ± SD of 32.9 ± 13.1 years, of which 40.7% were females and 50.1% from an urban area, were enrolled in the study. We found a global prevalence rate of CLBP of 35.5% [95% CI 34.1–36.9%]. The prevalence in urban areas was 30.68% [95% CI 28.9–32.8%]) while 40.2% was found in rural areas [95% CI 38.1–42.2%]). Age (p < 0.001), level of education (p = 0.046), marital status (p < 0.001), working status (p < 0.003), tobacco use (p < 0.016) and regular physical activity (p < 0.011) were associated with CLBP. In urban areas, only the level of education was able to predict the prevalence of CLBP (R² = 61%). In rural areas, CLBP was predicted by age, marital and working status (R² = 89%). Conclusions This study showed a high prevalence of CLBP among urban and rural communities in Benin. Age, level of education, marital status, and working status were significantly associated with CLBP in Benin.
The oxidation of sulphamethoxazole medicine (SMX) has been studied by means of UV/H2O2 conducting at a controlled pH between 2.0 and 12.0 and oxidant ratios of 500 mol H2O2/mol SMX. It is verified that operating at pH = 2.0 the highest rates of SMX degradation (74%) and loss of aromaticity (64%) are obtained. During the process, a strong brown tint and high turbidity are generated in the water depending on the pH, as it affects the chemical speciation of the dissociable compounds. The colour intensity of the water increases from pH = 2.0 (light brown, 3.5 NTU) to a maximum value at pH = 4.0 (dark brown, 42 NTU), when the neutral SMX species is almost 100%. Under these conditions, the formation of carboxylic acids (acetic and oxalic) and nitrate ion are minor. Conducting at higher pH, hue decreases, obtaining at pH = 12.0 a light yellow water (5 NTU) when the anionic SMX predominates. Thus, the maximum formation of nitrate ion occurs under these conditions. A pseudo-first order kinetic modelling is proposed for the loss of aromaticity and colour and turbidity formation in water, where the kinetic parameters are expressed as a function of the applied pH, being the pseudo-first-order rate constants (min-1): karom=0.0005pH2-0.0106pH+0.0707; kcolour=0.0011pH2-0.02pH+0.1125 and kNTU = 0.06 min-1.
Importance: Adult telomere length (TL) is a biological marker of aging associated with vascular health. TL at birth is associated with later life TL and may contain early biological information of later life cardiovascular health and disease. Objective: To evaluate whether newborn TL is associated with early life blood pressure differences in childhood. Design, setting, and participants: This cohort study was part of the ENVIRONAGE (Environmental Influence on Aging in Early Life) study, a birth cohort of Belgian mother-child pairs with recruitment at birth and a median follow-up of 4.5 years conducted between October 2014 and July 2021. Participants included for analysis provided full data for evaluation at follow-up visit. Data analysis was conducted between August and September 2021. Main outcomes and measures: Cord blood and placental average relative TL were measured at birth using quantitative polymerase chain reaction (qPCR). Systolic, diastolic, and mean arterial pressure (MAP) were evaluated at follow-up. High childhood blood pressure (standardized for child age, sex, and height) was defined following the 2017 American Academy of Pediatrics guidelines. Multivariable adjusted linear and logistic regression models were used to associate newborn TL and blood pressure indicators in childhood. Results: This study included 485 newborn children (52.8% girls) with a mean (SD) age of 4.6 (0.4) years at the follow-up visit. Newborn TL was associated with lower blood pressure in childhood. A 1-IQR increase in cord blood TL was associated with a -1.54 mm Hg (95% CI, -2.36 to -0.72 mm Hg) lower diastolic blood pressure and -1.18 mm Hg (95% CI, -1.89 to -0.46 mm Hg) lower MAP. No association was observed with systolic blood pressure. Furthermore, a 1-IQR increase in cord blood TL was associated with lower odds of having high blood pressure at the age of 4 to 6 years (adjusted OR, 0.72; 95% CI, 0.53 to 0.98). In placenta, a 1-IQR increase in TL was associated with a -0.96 mm Hg (95% CI, -1.72 to -0.21 mm Hg) lower diastolic, -0.88 mm Hg (95% CI, -1.54 to -0.22 mm Hg) lower MAP, and a lower adjusted OR of 0.69 (95% CI, 0.52 to 0.92) for having a high blood pressure in childhood. Conclusions and relevance: In this prospective birth cohort study, variation in early life blood pressure at school-age was associated with TL at birth. Cardiovascular health may to some extent be programmed at birth, and these results suggest that TL entails a biological mechanism in this programming.
Background The association between cocaine- and amphetamine-regulated transcript prepropeptide gene (CARTPT) and obesity-related outcomes has shown in the epidemiological studies. Nevertheless, there is lack of data regarding the CARTPT gene–diet interactions in terms of antioxidant potential of diet. So, this study aimed to test CARTPT gene–dietary non-enzymatic antioxidant capacity (NEAC) interactions on cardio-metabolic risk factors in obese individuals. Methods and material The present cross-sectional study was carried out among 288 apparently healthy obese adults within age range of 20–50 years. Antioxidant capacity of diet was estimated by calculating the oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), total radical-trapping antioxidant parameter (TRAP) and Trolox equivalent antioxidant capacity (TEAC) using a semiquantitative food frequency questionnaire (FFQ). Genotyping for CARTPT rs2239670 polymorphism was conducted by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method. Results A significant interaction was revealed between CARTPT rs2239670 and dietary ORAC on BMI ( P Interaction = 0.048) and fat mass percent (FM%) ( P Interaction = 0.008); in A allele carriers, higher adherence to the dietary ORAC was related to lower level of BMI and FM%. And, the significant interactions were observed between FRAP index and rs2239670 in relation to HOMA ( P Interaction = 0.049) and QUICKI ( P Interaction = 0.048). Moreover, there were significant interactions of rs2239670 with TRAP ( P Interaction = 0.029) and TEAC ( P Interaction = 0.034) on the serum glucose level; individuals with AG genotype were more respondent to higher intake of TRAP. Conclusion The present study indicated that the relationships between CARTPT rs2239670 and obesity and its-related metabolic parameters depend on adherence to the dietary NEAC. Large prospective studies are needed to confirm our findings.
Background: Patients with multiple sclerosis (MS) experience reduced exercise tolerance that substantially reduces quality of life. The mechanisms underpinning exercise intolerance in MS are not fully clear. This study aimed to determine the contributions of the cardiopulmonary system and peripheral muscle in MS-induced exercise intolerance before and after exercise training. Methods: Twenty-three patients with MS (13 women) and 20 age-matched and sex-matched healthy controls (13 women) performed a cardiopulmonary exercise test. Muscle fibre type composition, size, succinate dehydrogenase (SDH) activity, capillarity, and gene expression and proteins related to mitochondrial density were determined in vastus lateralis muscle biopsies. Nine MS patients (five women) were re-examined following a 12 week exercise training programme consisting of high-intensity cycling interval and resistance training. Results: Patients with MS had lower maximal oxygen uptake compared with healthy controls (V̇O2peak , 25.0 ± 8.5 vs. 35.7 ± 6.4 mL/kg/min, P < 0.001). The lower gas exchange threshold (MS: 14.5 ± 5.5 vs. controls: 19.7 ± 2.9 mL/kg/min, P = 0.01) and slope of V̇O2 versus work rate (MS: 9.5 ± 1.7 vs. controls: 10.8 ± 1.1 mL/min/W, P = 0.01) suggested an intramuscular contribution to exercise intolerance in patients with MS. Muscle SDH activity was 22% lower in MS (P = 0.004), and strongly correlated with several indices of whole-body exercise capacity in MS patients (e.g. V̇O2peak , Spearman's ρ = 0.81, P = 0.002), but not healthy controls (ρ = 0.24, P = 0.38). In addition, protein levels of mitochondrial OXPHOS complexes I (-40%, P = 0.047) and II (-45%, P = 0.026) were lower in MS patients versus controls. Muscle capillary/fibre ratio correlated with V̇O2peak in healthy controls (ρ = 0.86, P < 0.001) but not in MS (ρ = 0.35, P = 0.22), and did not differ between groups (1.41 ± 0.30 vs. 1.47 ± 0.38, P = 0.65). Expression of genes involved in mitochondrial function, such as PPARA, PPARG, and TFAM, was markedly reduced in muscle tissue samples of MS patients (all P < 0.05). No differences in muscle fibre type composition or size were observed between groups (all P > 0.05). V̇O2peak increased by 23% following exercise training in MS (P < 0.001); however, no changes in muscle capillarity, SDH activity, gene or protein expression were observed (all P > 0.05). Conclusions: Skeletal muscle oxidative phenotype (mitochondrial complex I and II content, SDH activity) is lower in patients with MS, contributing to reduced exercise tolerance. However, skeletal muscle mitochondria appeared resistant to the beneficial effects of exercise training, suggesting that other physiological systems, at least in part, drive the improvements in exercise capacity following exercise training in MS.
Classical symmetric distributions like the Gaussian are widely used. However, in reality data often display a lack of symmetry. Multiple distributions, grouped under the name “skewed distributions”, have been developed to specifically cope with asymmetric data. In this paper, we present a broad family of flexible multivariate skewed distributions for which statistical inference is a feasible task. The studied family of multivariate skewed distributions is derived by taking affine combinations of independent univariate distributions. These are members of a flexible family of univariate asymmetric distributions and are an important basis for achieving statistical inference. Besides basic properties of the proposed distributions, also statistical inference based on a maximum likelihood approach is presented. We show that under mild conditions, weak consistency and asymptotic normality of the maximum likelihood estimators hold. These results are supported by a simulation study confirming the developed theoretical results, and some data examples to illustrate practical applicability.
Aims: To investigate the outcomes and associated costs of haemodynamic-guided heart failure (HF) management with a pulmonary artery pressure (PAP) sensor in a multicentre European cohort. Methods and results: Data from all consecutive patients receiving a PAP sensor in Ziekenhuis Oost-Limburg, University Hospital Zurich and Sheffield Teaching Hospitals NHS Foundation Trust before January 2021 were collected. Medication changes, total number of HF hospitalizations and HF related health care costs (composed of HF hospitalizations, outpatient cardiology visits and monitoring costs) were compared between the pre-implantation and post-implantation period at 3, 6, and 12 months. PAP evolution post-implantation were grouped according to baseline mPAP ≥25 mmHg versus <25 mmHg and changes from baseline were analyzed via an area under the curve (AUC) analysis. A total of 48 patients received a PAP sensor (29 CardioMEMS and 19 Cordella devices) with a median follow-up of 19 (13-30) months. Mean age was 71 ± 10 years, 25.0% were female, 68.8% had a left ventricular ejection fraction < 50%, median NT-proBNP was 1801 (827-4503) pg/mL, and 89.6% were in NYHA class III. The number of diuretic therapy changes were non-significantly increased after 3 months (49 vs. 82; P = 0.284) and 6 months (82 vs. 127; P = 0.093) with a significant increase noted after 12 months (118 vs. 195; P = 0.005). The mPAP AUC decreased by -1418 mmHg-days for patients with a baseline mean PAP ≥ 25 mmHg. The number of HF hospitalizations was reduced for all patients after 6 (34 vs. 17; P = 0.014) and 12 months (48 vs. 29; P = 0.032). HF related health care costs were reduced from € 6286 to € 3761 at 6 months (P = 0.012) and from € 8960 to € 6167 at 12 months (P = 0.032). Conclusion: Haemodynamic-guided HF management reduces HF hospitalizations and HF related health care costs in selected HF patients amongst different European health care systems.
Aim To gain insight into which elements of the interpersonal care relationship (IPCR) are perceived as occurring (less) frequently and as (not) disturbing from the perspective of hospitalized older patients. Design A cross‐sectional study in three Belgian hospitals. Methods A convenience sample of patients aged 75 years or older admitted to a non‐geriatric ward were recruited between May 2017 and April 2019. The Interpersonal Geriatric care relationship (InteGer) tool was used to identify elements of the IPCR and was completed by the researchers through structured patient interviews. Results The mean total scale score for frequency was 3.74 (SD 1.51) [range 0–12]. On subscale level, the highest mean score was in the accessibility and the lowest mean score in the humanization subscale. Statistically significant differences between the hypothesized and experienced disturbance were observed in 18 of the 30 items. Ten items score in the category ‘no action needed’ (not occurring, not disturbing), nine items in the category ‘remain attentive for patient experiences’ (occurring, not disturbing), 10 items in the category ‘further analyses or monitoring needed’ (not occurring, disturbing) and one item in the category ‘urgent action needed’ (occurring and disturbing). Conclusion Participants report mostly positive experiences related to the four subscales of the InteGer, that is, humanization, attentiveness, interest and accessibility. Insights from this study provide important opportunities in the context of care optimization for each category with the main focus on items with high experienced disturbance. Impact The InteGer can be used for monitoring IPCR and formulating action points at ward and hospital level to further improve the IPCR and quality of care.
The thermodynamics and kinetics of the structural phase transition from monoclinic VO2 (M) to rutile VO2 (R) and vice versa were studied for particulate materials obtained by bead milling of VO2 (M) powder. Using wet bead milling, we decreased the particle size of VO2 (M) powder from ∼1 μm to 129 nm. With progressive milling, the switching enthalpy decreased from 47 J g⁻¹ to 29 J g⁻¹ due to a loss of crystallinity. The switching kinetics were studied using Friedman's differential isoconversional method. The activation energy |Eα| decreases with increasing difference between the actual temperature of the material and its switching temperature (T0). Furthermore, |Eα| decreases with progressive milling, and kinetic asymmetry is induced. For milled particulate materials, |Eα| is lower for the switch from VO2 (R) to VO2 (M) than for the opposite switch. For hydrothermally synthesized nanoparticles, |Eα| is in the same order of magnitude, albeit with inverse switching asymmetry. Latter may result from different defects that are introduced during both preparation techniques. Applying layers of milled particulate material to glass sheets yielded thermochromic coatings with luminous transmission of 40.7% and solar modulation of 8.3%. This demonstrates that milled VO2 particles have potential for use in energy efficient thermochromic windows.
Cu(In,Ga)Se2 (CIGS) solar cells are amongst the best performing thin-film technologies, with the latest performance gains being mainly due to recent years improvements obtained with post-deposition treatments (PDT). Moreover, thinning of the absorber layer down to sub-micrometre values (ultrathin absorbers) is of extreme importance for CIGS to be even more cost-effective and sustainable. However, electrical and optical limitations, such as rear interface recombination and insufficient light absorption, prevent the widespread implementation of ultrathin CIGS devices. The recent electrical CIGS simulation baseline models have failed to keep up with the experimental developments. Here an updated and experimentally based baseline model for electrical simulations in the Solar Cell Capacitor Simulator (SCAPS) software is presented and discussed with the incorporation of the PDT effects and increased optical accuracy with the support from Finite-Difference Time-Domain (FDTD) simulation results. Furthermore, a champion solar cell with an equivalent architecture validates the developed thin-film model. The baseline model is also applied to ultrathin CIGS solar cell devices, validated with the ultrathin champion cell. Ultimately, these ultrathin models pave the way for an ultrathin baseline model. Simulations results reveal that addressing these absorbers' inherent limitations makes it possible to achieve an ultrathin solar cell with at least 21.0% power conversion efficiency, with open-circuit voltage values even higher than the recent thin-film champion cells.
The discretisation of the Laplacian results into the well-known Laplace matrix. In the case of a one dimensional problem, an explicit formula for its inverse is derived on the basis of fundamental solutions (Green’s functions) for general boundary conditions. For a linear reaction–diffusion equation, approximations of the inverse are given.
Many species‐rich ecological communities emerge from adaptive radiation events. Yet the effects of adaptive radiation on community assembly remain poorly understood. Here, we explore the well‐documented radiations of African cichlid fishes and their interactions with the flatworm gill parasites Cichlidogyrus spp., including 10,529 reported infections and 477 different host–parasite combinations collected through a survey of peer‐reviewed literature. We assess how evolutionary, ecological, and morphological parameters determine host–parasite meta‐communities affected by adaptive radiation events through network metrics, host repertoire measures, and network link prediction. The hosts' evolutionary history mostly determined host repertoires of the parasites. Ecological and evolutionary parameters predicted host–parasite interactions. Generally, ecological opportunity and fitting have shaped cichlid‐Cichlidogyrus meta‐communities suggesting an invasive potential for hosts used in aquaculture. Meta‐communities affected by adaptive radiations are increasingly specialised with higher environmental stability. These trends should be verified across other systems to infer generalities in the evolution of species‐rich host–parasite networks. Many species‐rich ecological communities result from adaptive radiation events. We investigate interactions of African cichlids and their flatworm parasites belonging to Cichlidogyrus (a) through network analyses (b), host repertoire estimation, and network link prediction (heatmaps) (c). The hosts’ evolutionary history and environment determine observed host repertoires and network structure (b) but cichlid radiations in Eastern Africa have formed more specialised host‐parasite communities (c).
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4,307 members
Steven Maesen
  • Expertise Centre for Digital Media (EDM)
Ilie-Cosmin Stancu
  • Biomedical Research Institute (BIOMED)
Ivo Lambrichts
  • Morphology Research Group (MORFO)
Sara Leroi-Werelds
  • Faculty of Business Economics (BEW)
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Address
Campus UHasselt: Martelarenlaan 42, 3500 Hasselt, Campus Diepenbeek: Agoralaan – Gebouw D, 3590 Diepenbeek, Hasselt, Flanders, Belgium
Head of institution
Prof. Dr. Luc De Schepper
Website
www.uhasselt.be
Phone
0032 (0)11 26 81 11
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0032 (0)11 26 81 99