University of Antwerp
  • Antwerpen, Belgium
Recent publications
We investigate non-equilibrium states created by a laser beam incident on a superconducting NbTiN filament subject to an electrical pulse at 4 K. In absence of the laser excitation, when the amplitude of the current pulse applied to the filament exceeds the critical current value, we monitored the delay time $t_{d}$ that marks the collapse of the superconducting phase which is then followed by a voltage rise. We linked the delay time to the applied current using the time-dependent Ginzburg-Landau (TDGL) theory, which enabled us to deduce the cooling (or heat-removal ) time from the fit to the experimental data. Subsequently, we exposed the filament biased with a current pulse close to its critical value to a focused laser beam, inducing a normal state in the impact region of the laser beam. We showed that the energy of the incident beam and the incurred delay time are related to each other by a simple expression, that enables direct measurement of incident beam energy by temporal monitoring of the transport response. This method can be extended for usage in single-photon detection regime, and be used for accurate calibration of an arbitrary light source.
The COVID-19 pandemic and related physical distancing measures have disproportionally affected older adults living alone due to their greater social isolation. Unlike previous studies on the subject, the current research recognizes the diversity amongst older adults living alone by considering the impact of marital history. Combining information from Wave 8 of the Survey of Health Ageing and Retirement (SHARE), with data of SHARELIFE and the SHARE Corona survey, we investigated the differential impact of the COVID-19 pandemic on loneliness in older men (N = 1504) and women (N = 4822) living alone. Logistic multilevel analyses were performed on data from 26 European countries and Israel. For men, we found that the short-term widowed were more likely to report increased loneliness than the medium- and long-term widowed and those living apart together (LAT). For women, the results indicated that the short- and medium-term widowed and the divorced were at greater risk for increased loneliness than those in a LAT relationship. Also, medium-term widowed women were more likely to report increased loneliness than their long-term widowed counterparts. The three hypothesized underlying mechanisms – i.e., (i) the opportunity mechanism, (ii) the expectation mechanism, and (iii) the vulnerability mechanism – only played a small role in explaining the observed differences. In sum, our study highlights the importance of recognizing the diversity within the group of older adults living alone when investigating the effects of the pandemic on loneliness, yet the mechanisms behind the stratifying role of marital history are not fully understood.
Methamphetamine (MA) is a synthetic psychoactive drug which is consumed both licitly and illicitly. In some countries it is prescribed for attention-deficit and hyperactivity disorder, and short-term treatment of obesity. More often though, it is abused for its psychostimulant properties. Unfortunately, the spread and abuse of this synthetic drug have increased globally, being reported as the most widely consumed synthetic psychoactive drug in the world in 2019. Attempting to overcome the shortcomings of the currently used on-site methods for MA detection in suspected cargos, the present study explores the potential of electrochemical identification of MA by means of square wave voltammetry on disposable graphite screen-printed electrodes. Hence, the analytical characterization of the method was evaluated under optimal conditions exhibiting a linear range between 50 μM and 2.5 mM MA, a LOD of 16.7 μM, a LOQ of 50.0 μM and a sensitivity of 5.3 μA mM-1. Interestingly, two zones in the potential window were identified for the detection of MA, depending on its concentration in solution. Furthermore, the oxidative pathway of MA was elucidated employing liquid chromatography - mass spectrometry to understand the change in the electrochemical profile. Thereafter, the selectivity of the method towards MA in mixtures with other drugs of abuse as well as common adulterants/cutting agents was evaluated. Finally, the described method was employed for the analysis of MA in confiscated samples and compared with forensic methods, displaying its potential as a fast and easy-to-use method for on-site analysis.
Background: Large inter-surgeon variability exists in technical anatomical resectability assessment of colorectal cancer liver-only metastases (CRLM) following induction systemic therapy. We evaluated the role of tumour biological factors in predicting resectability and (early) recurrence after surgery for initially unresectable CRLM. Methods: 482 patients with initially unresectable CRLM from the phase 3 CAIRO5 trial were selected, with two-monthly resectability assessments by a liver expert panel. If no consensus existed among panel surgeons (i.e. same vote for (un)resectability of CRLM), conclusion was based on majority. The association of tumour biological (sidedness, synchronous CRLM, carcinoembryonic antigen and RAS/BRAFV600E mutation status) and technical anatomical factors with consensus among panel surgeons, secondary resectability and early recurrence (<6 months) without curative-intent repeat local treatment was analysed by uni- and pre-specified multivariable logistic regression. Results: After systemic treatment, 240 (50%) patients received complete local treatment of CRLM of which 75 (31%) patients experienced early recurrence without repeat local treatment. Higher number of CRLM (odds ratio 1.09 [95% confidence interval 1.03-1.15]) and age (odds ratio 1.03 [95% confidence interval 1.00-1.07]) were independently associated with early recurrence without repeat local treatment. In 138 (52%) patients, no consensus among panel surgeons was present prior to local treatment. Postoperative outcomes in patients with and without consensus were comparable. Conclusions: Almost a third of patients selected by an expert panel for secondary CRLM surgery following induction systemic treatment experience an early recurrence only amenable to palliative treatment. Number of CRLM and age, but no tumour biological factors are predictive, suggesting that until there are better biomarkers; resectability assessment remains primarily a technical anatomical decision.
Abiotic factors are usually considered key drivers of species distribution at macro scales, while biotic interactions are mostly used at local scales. A few studies have explored the role of biotic interactions at macro scales, but all considered a limited number of species and obligate interactions. We examine the role of biotic interactions in large-scale SDMs by testing two main hypotheses: (1) biotic factors in SDMs can have an important role at continental scale; (2) the inclusion of biotic factors in large-scale SDMs is important also for generalist species. We used a maximum entropy algorithm to model the distribution of 177 bat species in Africa calibrating two SDMs for each species: one considering only abiotic variables (noBIO-SDMs) and the other (BIO-SDMs) including also biotic variables (trophic resource richness). We focused the interpretation of our results on variable importance and response curves. For each species, we also compared the potential distribution measuring the percentage of change between the two models in each pixel of the study area. All models gave AUC >0.7, with values on average higher in BIO-SDMs compared to noBIO-SDMs. Trophic resources showed an importance overall higher level than all abiotic predic-tors in most of the species (~68%), including generalist species. Response curves were highly interpretable in all models, confirming the ecological reliability of our models. Model comparison between the two models showed a change in potential distribution for more than 80% of the species, particularly in tropical forests and shrublands. Our results highlight the importance of considering biotic interactions in SDMs at macro scales. We demonstrated that a generic biotic proxy can be important for modeling species distribution when species-specific data are not available, but we envision that a multi-scale analysis combined with a better knowledge of the species might provide a better understanding of the role of biotic interactions.
Introduction: Terrorist attacks against hospitals and health care providers have disproportionally increased during the last decades. A significant proportion of these attacks targeted abortion clinics and abortion providers. In the light of the overturning of Roe v. Wade in 2022, an increase of anti-abortion terrorist attacks is anticipated. Therefore, it becomes imperative to gain further insight into the risk and characteristics of past terrorist attacks. This study aimed to review terrorist attacks against health care targets providing abortion services from 1970 through 2020. Methods: Data collection was performed using a retrospective database search through the Global Terrorism Database (GTD). The GTD was searched using the internal database functions for all terrorist attacks against abortion health care providers from January 1, 1970 - December 31, 2020. Temporal factors, location, attack and weapon type, and number of casualties or hostages were analyzed using descriptive statistics. Results: In total, 262 terrorist attacks were identified in five different countries. The majority (96.6%) occurred in the United States, with the highest counts during the last 20 years of the 20th century. Facility and infrastructure attacks were the most common attack types, followed by bombings and explosions. The attacks resulted in 34 injuries and nine fatalities. Kidnapping took place in three incidents. Of all successful attacks, 96.9% resulted in property damage. Conclusion: Abortion-related health care facilities and providers have repeatedly been the target of terrorists over the past decades. Nearly all of these attacks took place in the United States, with the highest counts during the last 20 years of the 20th century.
Background Neurological symptoms are common manifestation in acute COVID-19. This includes hyper- and hypokinetic movement disorders. Data on their outcome, however, is limited. Methods Cases with new-onset COVID-19-associated movement disorders were identified by searching the literature. Authors were contacted for outcome data which were reviewed and analyzed. Results Movement disorders began 12.6 days on average after the initial onset of COVID-19. 92% of patients required hospital admission (mean duration 23 days). In a fraction of patients (6 of 27; 22%; 4 males/2 females, mean age 66.8 years) the movement disorder (ataxia, myoclonus, tremor, parkinsonism) was still present after a follow-up period of 7.5 ± 3 weeks. Severe COVID-19 in general and development of encephalopathy were risk factors, albeit not strong predictors, for the persistence. Conclusions The prognosis of new-onset COVID-19-associated movement disorder appears to be generally good. The majority recovered without residual symptoms within several weeks or months. Permanent cases may be due to unmasking of a previous subclinical movement disorder or due to vascular/demyelinating damage. Given the relatively low response rate of one third only and the heterogeneity of mechanisms firm conclusions on the (long-term) outome cannot, however, be drawn.
Background Individuals affected with autism often suffer additional co-morbidities such as intellectual disability. The genes contributing to autism cluster on a relatively limited number of cellular pathways, including chromatin remodeling. However, limited information is available on how mutations in single genes can result in such pleiotropic clinical features in affected individuals. In this review, we summarize available information on one of the most frequently mutated genes in syndromic autism the Activity-Dependent Neuroprotective Protein (ADNP). Results Heterozygous and predicted loss-of-function ADNP mutations in individuals inevitably result in the clinical presentation with the Helsmoortel–Van der Aa syndrome, a frequent form of syndromic autism. ADNP, a zinc finger DNA-binding protein has a role in chromatin remodeling: The protein is associated with the pericentromeric protein HP1, the SWI/SNF core complex protein BRG1, and other members of this chromatin remodeling complex and, in murine stem cells, with the chromodomain helicase CHD4 in a ChAHP complex. ADNP has recently been shown to possess R-loop processing activity. In addition, many additional functions, for instance, in association with cytoskeletal proteins have been linked to ADNP. Conclusions We here present an integrated evaluation of all current aspects of gene function and evaluate how abnormalities in chromatin remodeling might relate to the pleiotropic clinical presentation in individual“s” with Helsmoortel–Van der Aa syndrome.
Cluster beam deposition is employed for fabricating well-defined bimetallic plasmonic photocatalysts to enhance their activity while facilitating a more fundamental understanding of their properties. Au x Ag 1-x clusters with compositions (x =...
Objective: High relapse rates are observed after electroconvulsive therapy (ECT) for major depression. Identifying patients who are at increased risk for relapse to intensify their treatment regimen post-ECT might reduce relapse rates. We aimed to determine clinical characteristics that are associated with relapse within two years after successful ECT. Methods: Patients who remitted to ECT in a randomised controlled trial comparing adjuvant nortriptyline and placebo during a course of bilateral ECT were followed-up prospectively for one year with open-label nortriptyline (Dutch Trial Register NTR5579). Second-year follow-up data were collected retrospectively. Thirty-four patients were included in this follow-up cohort. To examine the association between clinical characteristics and the risk of relapse, unadjusted hazard ratios (HRs) were calculated. Results: At two years post-ECT, the overall relapse rate was 50%, and the HRs for relapse in patients with psychotic features, a higher severity of depression, and medication resistance prior to ECT were 0.33 (CI 0.12-0.89; p=0.029), 0.88 (CI 0.80-0.98; p=0.014), and 4.48 (CI 1.28-15.73, p=0.019), respectively. No effect was found for age, sex or episode duration on the relapse rate. Conclusions: Depressed patients with psychotic features, with higher symptom severity and without medication resistance prior to ECT have a significantly decreased risk of relapse after successful ECT. A sustained remission rate of 50% over two years in patients with severe major depression who were treated with nortriptyline monotherapy after successful ECT is encouraging.
Culturally differing approaches to the distinction between physical and mental health contribute to cultural differences in explanatory models of what we call “mental” health in a Western context. For this reason, we use “(mental) health” in this study when referring to these models or differences in understanding. This interpretative, interview-based qualitative study focuses on Belgian mental health professionals’ perceptions of the (mental) health explanatory models held by their patients of sub-Saharan African (SSA) descent. The study goals were threefold: first, to assess professionals’ perceptions of the explanatory models of their patients of SSA descent; second, to examine how these perceptions influence treatment practices; and third, to investigate the role of the professionals’ cultural backgrounds, comparing the results between professionals with and without an SSA background. Twenty-two in-depth interviews with mental health professionals were thematically analyzed, with ten of the participants of SSA descent. Results show that all professionals perceived differences between Western and SSA explanatory models of (mental) health. Causal beliefs were mentioned as the most important difference, including their influence on coping strategies and health-seeking behavior among patients of SSA descent. Professionals’ perceptions and familiarity with SSA explanatory models of (mental) health affected their treatment practices. Language and conceptual interpretation difficulties were encountered less frequently by professionals of SSA descent. Those with a Western background applied “culturally sensitive” practices, while professionals of SSA descent implemented an integrated approach. These results contribute to ongoing discussions about what is considered “cultural competency.”
To develop a novel algorithm based on ray tracing, simulated visual performance and through-focus optimization for an accurate intraocular lens (IOL) power calculation. Custom-developed algorithms for ray tracing optimization (RTO) were used to combine the natural corneal higher-order aberrations (HOAs) with multiple sphero-cylindrical corrections in 210 higher order statistical eye models for developing keratoconus. The magnitude of defocus and astigmatism producing the maximum Visual Strehl was considered as the optimal sphero-cylindrical target for IOL power calculation. Corneal astigmatism and the RMS HOAs ranged from − 0.64 ± 0.35D and 0.10 ± 0.04 μm (0-months) to − 3.15 ± 1.38D and 0.82 ± 0.47 μm (120-months). Defocus and astigmatism target was close to neutral for eyes with low amount of HOAs (0 and 12-months), where 91.66% of eyes agreed within ± 0.50D in IOL power calculation (RTO vs. SRK/T). However, corneas with higher amounts of HOAs presented greater visual improvement with an optimized target. In these eyes (24- to 120-months), only 18.05% of eyes agreed within ± 0.50D (RTO vs. SRK/T). The power difference exceeded 3D in 42.2% while the cylinder required adjustments larger than 3D in 18.4% of the cases. Certain amounts of lower and HOAs may interact favourably to improve visual performance, shifting therefore the refractive target for IOL power calculation.
Background: The surgical treatment of otosclerosis consists of the replacement of the stapes using a piston. Aims/objectives: The objective of this study is to assess the audiometric results and quality of life (QOL) of patients who underwent surgery for otosclerosis by stapedectomy with fascia interposition (STIP) or by stapedotomy using CO2 laser (SLaser) without fascia interposition. Material and methods: Ninety-one patients operated on for otosclerosis by STIP (40 patients) and by SLaser (51 patients) were included. Audiometric results were graphically displayed using the Amsterdam Hearing Evaluation Plot and were compared to the Common Otology Database (COD) comprising 660 patients. The patients' QOL was assessed with an otological validated survey. The significance level was p < .05. Results: There was no significant difference in hearing improvement between SLaser and STIP-operated patients. There was no significant difference between our results and that of COD. QOL was significantly improved (+3.5/10) postoperatively for both STIP and SLaser in both social and professional fields. Conclusions and significance: By comparing QOL and hearing gain of STIP and SLaser, our results suggest that both surgical techniques are a safe and successful treatment for otosclerotic stapes fixation. Further studies aiming at comparing larger series may confirm and refine these results.
Reduced free time and increased fees for demurrage and detention create organizational challenges with respect to intermodal transport. As a result, actors within the maritime supply chains are confronted with greater complexity and higher risk of costs; and, therefore, often fall back on transportation by truck to and from the hinterland. That is why the present research examines the impact of this evolution on the bottom line of the involved actors from a maritime supply chain perspective. The research approach consists of reviewing the relevant literature, analyzing the available sector data obtained through interviews and professional experience, and validating the proposed solutions. Starting from the research results, the problem-solving discussions resulted in the following top three as feasible solutions: digitalization, extra ‘free time’ for hinterland locations, and more attention during the negotiation process.
The self-limited (familial) epilepsies with onset in neonates or infants, formerly called benign familial neonatal and/or infantile epilepsies, are autosomal dominant disorders characterized by neonatal- or infantile-onset focal motor seizures and the absence of neurodevelopmental complications. Seizures tend to remit during infancy or early childhood and are therefore called "self-limited". A positive family history for epilepsy usually suggests the genetic etiology, but incomplete penetrance and de novo inheritance occur. Here, we review the phenotypic spectrum and the genetic architecture of the self-limited (familial) epilepsies with onset in neonates or infants. By using an illustrative case study, we describe important clues in recognition of these syndromes, diagnostic steps including genetic testing, management, and genetic counseling.
The use of social contact rates is widespread in infectious disease modeling since it has been shown that they are key driving forces of important epidemiological parameters. Quantification of contact patterns is crucial to parameterize dynamic transmission models and to provide insights on the (basic) reproduction number. Information on social interactions can be obtained from population-based contact surveys, such as the European Commission project POLYMOD. Estimation of age-specific contact rates from these studies is often done using a piecewise constant approach or bivariate smoothing techniques. For the latter, typically, smoothness is introduced in the dimensions of the respondent’s and contact’s age (i.e., the rows and columns of the social contact matrix). We propose a smoothing constrained approach—taking into account the reciprocal nature of contacts—introducing smoothness over the diagonal (including all subdiagonals) of the social contact matrix. This modeling approach is justified assuming that when people age their contact behavior changes smoothly. We call this smoothing from a cohort perspective. Two approaches that allow for smoothing over social contact matrix diagonals are proposed, namely (i) reordering of the diagonal components of the contact matrix and (ii) reordering of the penalty matrix ensuring smoothness over the contact matrix diagonals. Parameter estimation is done in the likelihood framework by using constrained penalized iterative reweighted least squares. A simulation study underlines the benefits of cohort-based smoothing. Finally, the proposed methods are illustrated on the Belgian POLYMOD data of 2006. Code to reproduce the results of the article can be downloaded on this GitHub repository
Everyday lives at the borders have lately been of interest in academic research. Drawing on visual elicitation interviews, this study analyses how ethnic Lithuanians living on the Polish borderland interpret images of the landscape which they inhabit. The aim of this analysis is to understand how these borderlanders position themselves vis-à-vis socio-spatial borderland realities, and how visual materials can instigate extensive plotted narratives. The results demonstrate that the Lithuanian minority in Poland not only challenges or accepts the public narratives, but that they also use them as props to create a unified narrative about their identification and belonging, which transgresses time, place and situated events.
Objective: In a secondary prevention of coronary artery disease (CAD), nutritional management is an integral part of lifestyle optimisation. However, few studies have investigated the potential of remote nutritional follow-up using digital solutions. This study investigates the effectiveness of a smartphone application for nutrition education and feedback with pictures of meals by a dietitian for patients with CAD. Methods: Sixty participants with CAD were randomised to either a TeleDiet group or a control group. Participants in the TeleDiet group participated in dietary education using a messaging application. The primary outcome was the change of the Mediterranean diet score (MedDietScore). The Nutrition-Score, a modification of the MedDietScore, blood tests (blood lipids, blood glucose and kidney function), body mass index, self-efficacy, medication adherence and health-related quality of life during the observation period were analysed as secondary outcomes. Results: Sixty participants participated in the study. The difference in the MedDietScore in the TeleDiet group was greater than in the control group, but not significant (2.0 [−1.0, 4.0] vs. 0.0 [−3.0, 1.5], p = 0.066). The difference in the Nutrition-Score in the TeleDiet group was significantly greater than in the control group (3.0 [1.0, 3.5] vs. 0.0 [−3.0, 2.0], p = 0.029). Nutrition knowledge of the TeleDiet group improved significantly compared to the control group (1.9 ± 1.7 vs. 0.8 ± 2.1, p = 0.048). Conclusions: A feedback system using a simple messaging application that allows patients with CAD to simply send a picture of their food has a positive effect on nutrition knowledge. It could be a hint for the implementation of the Mediterranean diet.
Research indicates that the uptake of formal childcare for children under age 3 is lower among migrant origin parents than among native parents in most European countries, and that these differentials extend to the second generation. Despite considerable investments in formal childcare availability in many European countries, it remains unclear whether and to what extent expanding local childcare availability effectively diminishes migrant-native uptake differentials due to the lack of longitudinal research. Therefore, this study assesses for Belgium to what extent expansions in childcare availability within municipalities in the period 2010–2014 has increased the uptake of formal childcare for children under age 3 among households where the mother has a second generation Southern European, Maghreb or Turkish background, versus no migration background. We use longitudinal census and register data for Belgium that were linked to longitudinal tax return data on childcare expenses and municipality-level data on childcare availability for children aged 0–3. Our results show that Southern European and Turkish origin mothers become more likely to use formal childcare when childcare places become more widely available within their municipalities, but also that the uptake gap with native mothers persists, since there is no differential effect of increasing local childcare availability. Since local childcare expansions entail a slightly stronger increase in formal childcare uptake among Maghreb origin mothers compared to native mothers, this results in slightly decreasing migrant-native uptake gaps, although considerable uptake gaps remain. To our knowledge, this is the first longitudinal study addressing the relationship between local childcare availability and uptake differentials by migration background. This study can inspire avenues for follow-up research which could provide additional insight into the possible mechanisms behind the varying effects of increasing local childcare availability by migration background and the persisting migrant-native uptake gaps.
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12,852 members
Joke Hadermann
  • Department of Physics
Maria Batuk
  • Department of Physics
Wilhelm Mistiaen
  • Faculty of Medicine
Prinsstraat 13, B-2000, Antwerpen, Belgium
Head of institution
Herman Van Goethem