1,966 results on '"de Leeuw, P."'
Search Results
2. Majorizing Stress Formula Two
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de Leeuw, Jan
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Mathematics - Numerical Analysis ,Statistics - Computation ,Statistics - Machine Learning ,G.3 - Abstract
Modifications of the smacof algorithm for multidimensional scaling are proposed that provide a convergent majorization algorithm for Kruskal's stress formula two., Comment: 16 pages, 4 figures, R code
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- 2024
3. Global Minima by Penalized Full-dimensional Scaling
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de Leeuw, Jan
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Statistics - Computation ,Statistics - Machine Learning ,62-04 62-08 ,G.3 - Abstract
The full-dimensional (metric, Euclidean, least squares) multidimensional scaling stress loss function is combined with a quadratic external penalty function term. The trajectory of minimizers of stress for increasing values of the penalty parameter is then used to find (tentative) global minima for low-dimensional multidimensional scaling. This is illustrated with several one-dimensional and two-dimensional examples., Comment: 39 pages
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- 2024
4. Convergence of SMACOF
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De Leeuw, Jan
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Statistics - Computation ,62-04 62-08 ,G.3 - Abstract
To study convergence of SMACOF we introduce a modification mSMACOF that rotates the configurations from each of the SMACOF iterations to principal components. This modification, called mSMACOF, has the same stress values as SMACOF in each iteration, but unlike SMACOF it produces a sequence of configurations that properly converges to a solution. We show that the modified algorithm can be implemented by iterating ordinary SMACOF to convergence, and then rotating the SMACOF solution to principal components. The speed of linear convergence of SMACOF and mSMACOF is the same, and is equal to the largest eigenvalue of the derivative of the Guttman transform, ignoring the trivial unit eigenvalues that result from rotational indeterminacy., Comment: 18 pages, R code
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- 2024
5. Integrable Conformal Defects in N=4 SYM
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de Leeuw, Marius and Holguin, Adolfo
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High Energy Physics - Theory - Abstract
In this paper we classify integrable conformal defects in N=4 SYM theory for which the scalar fields pick up a non-trivial vacuum expectation value. Defects of this form correspond to Dirichlet boundary conditions that have a pole at the defect. These set-ups typically appear on the field theory side of probe brane set-ups in the AdS/CFT correspondence. We show that such defects, for any codimension, are related to fuzzy spheres. We discuss the properties of the different possible fuzzy spheres that can appear and present the corresponding Matrix Product States. We furthermore set-up the quantum field theoretic framework by computing the mass matrix and finding the propagators.
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- 2024
6. Integrable models on Rydberg atom chains
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Corcoran, Luke, de Leeuw, Marius, and Pozsgay, Balázs
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Statistical Mechanics ,High Energy Physics - Theory ,Mathematical Physics ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
We initiate a systematic study of integrable models for spin chains with constrained Hilbert spaces; we focus on spin-1/2 chains with the Rydberg constraint. We extend earlier results for medium-range spin chains to the constrained Hilbert space, and formulate an integrability condition. This enables us to construct new integrable models with fixed interaction ranges. We classify all time- and space-reflection symmetric integrable Rydberg-constrained Hamiltonians of range 3 and 4. At range 3, we find a single family of integrable Hamiltonians: the so-called RSOS quantum chains, which are related to the well-known RSOS models of Andrews, Baxter, and Forrester. At range 4 we find two families of models, the first of which is the constrained XXZ model. We also find a new family of models depending on a single coupling $z$. We provide evidence of two critical points related to the golden ratio $\phi$, at $z=\phi^{-1/2}$ and $z=\phi^{3/2}$. We also perform a partial classification of integrable Hamiltonians for range 5., Comment: 40 pages, 11 figures. v2: added references
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- 2024
7. The Role of Interfacial Morphology in Cu2O/TiO2 and Band Bending: Insights from Density Functional Theory
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Asadinamin, Mona, Živkovic, Aleksandar, De Leeuw, Nora H., and Lewis, Steven P.
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Condensed Matter - Materials Science ,Physics - Computational Physics - Abstract
Photocatalysis, a promising solution for environmental challenges, relies on the generation and utilization of photogenerated charge carriers within photocatalysts. However, recombination of these carriers often limits efficiency. Heterostructures, especially Cu2O/TiO2, have emerged as effective solutions to enhance charge separation. This study systematically explores the effect of interfacial morphologies on the band bending within Cu2O/TiO2 anatase heterostructures, employing density functional theory (DFT). Through this study, eight distinct interfaces are identified and analyzed, revealing a consistent staggered-type band alignment. Despite variations in band edge positions, a systematic charge transfer from Cu2O to TiO2 is observed across all interfaces. The proposed band bending configurations would suggest enhanced charge separation and photocatalytic activity under ultraviolet illumination due to a Z-scheme configuration. This theoretical investigation provides valuable insights into the interplay between interfacial morphology, band bending, and charge transfer, for advancing the understanding of fundamental electronic mechanisms in heterostructures., Comment: 57 pages, 42 figures
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- 2024
8. A perturbative approach to the non-relativistic string spectrum
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de Leeuw, Marius, Fontanella, Andrea, and García, Juan Miguel Nieto
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High Energy Physics - Theory - Abstract
In this letter we use a perturbative approach to find the spectrum of non-relativistic strings in the String Newton-Cartan (SNC) AdS$_5\times$S$^5$ spacetime. We perturb the bosonic sector of the action around a BMN-like folded string solution in light-cone gauge. We find strong evidence that the theory is described by a combination of massive and massless free fields in an anti-de Sitter background by showing that interaction terms up to six scalars vanish after field redefinitions., Comment: 11 pages
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- 2024
9. Parcel loss prediction in last-mile delivery: deep and non-deep approaches with insights from Explainable AI
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de Leeuw, Jan, Bukhsh, Zaharah, and Zhang, Yingqian
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Computer Science - Machine Learning - Abstract
Within the domain of e-commerce retail, an important objective is the reduction of parcel loss during the last-mile delivery phase. The ever-increasing availability of data, including product, customer, and order information, has made it possible for the application of machine learning in parcel loss prediction. However, a significant challenge arises from the inherent imbalance in the data, i.e., only a very low percentage of parcels are lost. In this paper, we propose two machine learning approaches, namely, Data Balance with Supervised Learning (DBSL) and Deep Hybrid Ensemble Learning (DHEL), to accurately predict parcel loss. The practical implication of such predictions is their value in aiding e-commerce retailers in optimizing insurance-related decision-making policies. We conduct a comprehensive evaluation of the proposed machine learning models using one year data from Belgian shipments. The findings show that the DHEL model, which combines a feed-forward autoencoder with a random forest, achieves the highest classification performance. Furthermore, we use the techniques from Explainable AI (XAI) to illustrate how prediction models can be used in enhancing business processes and augmenting the overall value proposition for e-commerce retailers in the last mile delivery.
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- 2023
10. ProtoExplorer: Interpretable Forensic Analysis of Deepfake Videos using Prototype Exploration and Refinement
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Bouter, Merel de Leeuw den, Pardo, Javier Lloret, Geradts, Zeno, and Worring, Marcel
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Computer Science - Artificial Intelligence - Abstract
In high-stakes settings, Machine Learning models that can provide predictions that are interpretable for humans are crucial. This is even more true with the advent of complex deep learning based models with a huge number of tunable parameters. Recently, prototype-based methods have emerged as a promising approach to make deep learning interpretable. We particularly focus on the analysis of deepfake videos in a forensics context. Although prototype-based methods have been introduced for the detection of deepfake videos, their use in real-world scenarios still presents major challenges, in that prototypes tend to be overly similar and interpretability varies between prototypes. This paper proposes a Visual Analytics process model for prototype learning, and, based on this, presents ProtoExplorer, a Visual Analytics system for the exploration and refinement of prototype-based deepfake detection models. ProtoExplorer offers tools for visualizing and temporally filtering prototype-based predictions when working with video data. It disentangles the complexity of working with spatio-temporal prototypes, facilitating their visualization. It further enables the refinement of models by interactively deleting and replacing prototypes with the aim to achieve more interpretable and less biased predictions while preserving detection accuracy. The system was designed with forensic experts and evaluated in a number of rounds based on both open-ended think aloud evaluation and interviews. These sessions have confirmed the strength of our prototype based exploration of deepfake videos while they provided the feedback needed to continuously improve the system., Comment: 15 pages, 6 figures
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- 2023
11. Searching for Argument-Counterargument Relationships in Vector Embedding Spaces
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Chang, Cherrie and de Leeuw, Josh
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Artificial Intelligence ,Natural Language Processing ,Semantics ,Computational Modeling - Abstract
Vector embedding spaces are representational structures that can capture both the similarity relationship between items and various other semantic relationships. Current state-of-the-art embedding models can generate embedding vectors for individual words and longer strings of text, enabling vector spaces to encode the similarity between entire documents of text. We investigated three embedding models to see if semantic relationships besides similarity are represented in these spaces across three embedding models, focusing on the relationship between arguments and counterarguments as a specific example. While there was not a linear subspace that captured the semantic relationship between an argument and its counterargument, we found that neural networks with a single hidden layer could partially learn the transformations between an argument's embedding and the corresponding counterargument's embedding in all three spaces. The trained models generalized across three different datasets of arguments, suggesting these partially learned transformations are applicable to arguments and counterarguments in general, not just tied to the semantic context of the models' training dataset. This approach has practical applications in designing information retrieval systems for intelligent agents and, potentially, in models of cognition that use vector embedding spaces as a representational structure.
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- 2024
12. A perturbative approach to the non-relativistic string spectrum
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Marius de Leeuw, Andrea Fontanella, and Juan Miguel Nieto García
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Gauge-Gravity Correspondence ,Sigma Models ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Abstract In this letter we use a perturbative approach to find the spectrum of non-relativistic strings in the String Newton-Cartan (SNC) AdS5×S5 spacetime. We perturb the bosonic sector of the action around a BMN-like folded string solution in light-cone gauge. We find strong evidence that the theory is described by a combination of massive and massless free fields in an anti-de Sitter background by showing that interaction terms up to six scalars vanish after field redefinitions.
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- 2024
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13. B-type anomaly coefficients for the D3-D5 domain wall
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de Leeuw, Marius, Kristjansen, Charlotte, Linardopoulos, Georgios, and Volk, Matthias
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High Energy Physics - Theory - Abstract
We compute type-B Weyl anomaly coefficients for the domain wall version of N = 4 SYM that is holographically dual to the D3-D5 probe-brane system with flux. Our starting point is the explicit expression for the improved energy momentum tensor of N = 4 SYM. We determine the two-point function of this operator in the presence of the domain wall and extract the anomaly coefficients from the result. In the same process we determine the two-point function of the displacement operator., Comment: 6 pages
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- 2023
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14. All regular $4 \times 4$ solutions of the Yang-Baxter equation
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Corcoran, Luke and de Leeuw, Marius
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High Energy Physics - Theory ,Condensed Matter - Statistical Mechanics ,Mathematical Physics ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
We complete the classification of $4\times 4$ regular solutions of the Yang-Baxter equation. Apart from previously known models, we find four new models of non-difference form. All the new models give rise to Hamiltonians and transfer matrices that have a non-trivial Jordan block structure. One model corresponds to a non-diagonalisable integrable deformation of the XXX spin chain., Comment: 18 pages. v2: references added. v3: typos corrected/references added
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- 2023
15. Hidden quasi-local charges and Gibbs ensemble in a Lindblad system
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de Leeuw, Marius, Paletta, Chiara, Pozsgay, Balázs, and Vernier, Eric
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Condensed Matter - Statistical Mechanics ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
We consider spin-1/2 chains with external driving that breaks the continuous symmetries of the Hamiltonian. We introduce a family of models described by the Lindblad equation with local jump operators. The models have hidden strong symmetries in the form of quasi-local charges, leading to multiple non-equilibrium steady states. We compute them exactly in the form of Matrix Product Operators, and argue that they are the analogues of quantum many body scars in the Lindbladian setting. We observe that the dynamics leads to the emergence of a Gibbs ensemble constructed from the hidden charges., Comment: 5 pages, v2: references added
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- 2023
16. Retrieval of hourly aerosol single scattering albedo over land using geostationary satellite data
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Jiang, Xingxing, Xue, Yong, de Leeuw, Gerrit, Jin, Chunlin, Zhang, Sheng, Sun, Yuxin, and Wu, Shuhui
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- 2024
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17. The Mood and Resilience in Offspring (MARIO) project: a longitudinal cohort study among offspring of parents with and without a mood disorder
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Vreeker, Annabel, Horsfall, Melany, Eikelenboom, Merijn, Beerthuizen, Annemerle, Bergink, Veerle, Boks, Marco P. M., Hartman, Catharina A., de Koning, Ricki, de Leeuw, Max, Maciejewski, Dominique F., Penninx, Brenda W. J. H., and Hillegers, Manon H. J.
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- 2024
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18. Three-dimensional identification of microvascular pathology and neurovascular inflammation in severe white matter hyperintensity: a case report
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Solé-Guardia, Gemma, Luijten, Matthijs, Geenen, Bram, Claassen, Jurgen A. H. R., Litjens, Geert, de Leeuw, Frank-Erik, Wiesmann, Maximilian, and Kiliaan, Amanda J.
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- 2024
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19. Genome sequencing as a generic diagnostic strategy for rare disease
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Schobers, Gaby, Derks, Ronny, den Ouden, Amber, Swinkels, Hilde, van Reeuwijk, Jeroen, Bosgoed, Ermanno, Lugtenberg, Dorien, Sun, Su Ming, Corominas Galbany, Jordi, Weiss, Marjan, Blok, Marinus J., Olde Keizer, Richelle A. C. M., Hofste, Tom, Hellebrekers, Debby, de Leeuw, Nicole, Stegmann, Alexander, Kamsteeg, Erik-Jan, Paulussen, Aimee D. C., Ligtenberg, Marjolijn J. L., Bradley, Xiangqun Zheng, Peden, John, Gutierrez, Alejandra, Pullen, Adam, Payne, Tom, Gilissen, Christian, van den Wijngaard, Arthur, Brunner, Han G., Nelen, Marcel, Yntema, Helger G., and Vissers, Lisenka E. L. M.
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- 2024
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20. The impact of mental state altering medications on preventable falls after total hip or total knee arthroplasty: a systematic review and meta-analysis
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Wesselink, Elsbeth J., van der Vegt, Marinus, Remmelzwaal, Sharon, Bossers, Sebastiaan M., Franssen, Eric J., Swart, Eleonora L., Boer, Christa, and de Leeuw, Marcel A.
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- 2024
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21. Making cities mental health friendly for adolescents and young adults
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Collins, Pamela Y., Sinha, Moitreyee, Concepcion, Tessa, Patton, George, Way, Thaisa, McCay, Layla, Mensa-Kwao, Augustina, Herrman, Helen, de Leeuw, Evelyne, Anand, Nalini, Atwoli, Lukoye, Bardikoff, Nicole, Booysen, Chantelle, Bustamante, Inés, Chen, Yajun, Davis, Kelly, Dua, Tarun, Foote, Nathaniel, Hughsam, Matthew, Juma, Damian, Khanal, Shisir, Kumar, Manasi, Lefkowitz, Bina, McDermott, Peter, Moitra, Modhurima, Ochieng, Yvonne, Omigbodun, Olayinka, Queen, Emily, Unützer, Jürgen, Uribe-Restrepo, José Miguel, Wolpert, Miranda, and Zeitz, Lian
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- 2024
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22. Retrieval of hourly aerosol single scattering albedo over land using geostationary satellite data
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Xingxing Jiang, Yong Xue, Gerrit de Leeuw, Chunlin Jin, Sheng Zhang, Yuxin Sun, and Shuhui Wu
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Environmental sciences ,GE1-350 ,Meteorology. Climatology ,QC851-999 - Abstract
Abstract The single scattering albedo (SSA) of aerosol particles is one of the key variables that determine aerosol radiative forcing. Herein, an Algorithm for the retrieval of Single scattering albedo over Land (ASL) is proposed for application to full-disk data from the advanced Himawari imager (AHI) sensor flying on board the Himawari-8 satellite. In this algorithm, an atmospheric radiative transfer model known as the USM (the top of the atmosphere reflectance as the sum of Un-scattered, Single-scattered, and Multiple-scattered components) is used to calculate the SSA instead of predetermining the aerosol model; the USM is constrained by the surface bidirectional reflectance distribution function shape and aerosol optical depth (AOD) in the retrieval process. Combining two consecutive observations and a 2 * 2 pixel window, the optimal estimation algorithm is adopted to obtain the optimal solution for the aerosol SSA. These SSA results are evaluated by comparing with aerosol robotic network (AERONET) data. Linear regression shows that SSAASL = 0.60*SSSAERONET + 0.38, with a correlation coefficient (0.7284), mean absolute error (0.0319), mean bias error (0.00324), root mean square error (0.0427), and ~80.11% of the ASL SSA data within an uncertainty of ±0.05 of the AERONET data. A comparison of the ASL SSA products with collocated Himawari-8 SSA products (Version 03, officially released by the Japan Meteorological Agency (JMA), referred to herein as JMA SSA) shows that the accuracy of the ASL SSA is better than that of the JMA SSA products. For the SSA retrieval in large AODs (>0.4), the validation metrics vs. AERONET data are better.
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- 2024
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23. A range three elliptic deformation of the Hubbard model
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de Leeuw, Marius, Paletta, Chiara, and Pozsgay, Balázs
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Condensed Matter - Statistical Mechanics ,High Energy Physics - Theory ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
In this paper we present a new integrable deformation of the Hubbard model. Our deformation gives rise to a range 3 interaction term in the Hamiltonian which does not preserve spin or particle number. This is the first non-trivial medium range deformation of the Hubbard model that is integrable. Our model can be mapped to a new integrable nearest-neighbour model via a duality transformation. The resulting nearest-neighbour model also breaks spin conservation. We compute the $R$-matrices for our models, and find that there is a very unusual dependence on the spectral parameters in terms of the elliptic amplitude., Comment: 20 pages, v2: minor changes
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- 2023
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24. Improved approximation and visualization of the correlation matrix
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Graffelman, Jan and de Leeuw, Jan
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Statistics - Computation ,62H25, 62-08 - Abstract
The graphical representation of the correlation matrix by means of different multivariate statistical methods is reviewed, a comparison of the different procedures is presented with the use of an example data set, and an improved representation with better fit is proposed. Principal component analysis is widely used for making pictures of correlation structure, though as shown a weighted alternating least squares approach that avoids the fitting of the diagonal of the correlation matrix outperforms both principal component analysis and principal factor analysis in approximating a correlation matrix. Weighted alternating least squares is a very strong competitor for principal component analysis, in particular if the correlation matrix is the focus of the study, because it improves the representation of the correlation matrix, often at the expense of only a minor percentage of explained variance for the original data matrix, if the latter is mapped onto the correlation biplot by regression. In this article, we propose to combine weighted alternating least squares with an additive adjustment of the correlation matrix, and this is seen to lead to further improved approximation of the correlation matrix., Comment: 20 pages, 4 figures
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- 2022
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25. Methotrexate treatment hampers induction of vaccine-specific CD4 T cell responses in patients with IMID
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Sander W Tas, Joep Killestein, Joost Raaphorst, Taco W Kuijpers, Alexandre E Voskuyl, Gertjan Wolbink, Theo Rispens, Anneke J van der Kooi, Anja Ten Brinke, Karina de Leeuw, Abraham Rutgers, Juan J Garcia-Vallejo, Frederike J Bemelman, YK Onno Teng, Phyllis I Spuls, Mark Löwenberg, Jelle de Wit, Diane van der Woude, Marcel W Bekkenk, Luuk Wieske, Esther Brusse, Laura Boekel, Filip Eftimov, Eileen W Stalman, Maurice Steenhuis, Sofie Keijzer, Olvi Cristianawati, Koos P J van Dam, Adriaan G Volkers, Annelie H Musters, Nicoline F Post, Angela L Bosma, Marc L Hilhorst, Yosta Vegting, Bo Broens, Barbara Horváth, Annabel M Ruiter, Matthias H Busch, Dirk Jan Hijnen, Niels J M Verstegen, Pieter A van Doorn, Jan JGM Verschuuren, Laura Y L Kummer, Ruth R Hagen, Christine Kreher, Lisan H Kuijper, Mariël C Duurland, Veronique A L Konijn, Carolien E van de Sandt, Laura Fernández Blanco, Amélie Bos, Charlotte Menage, Tineke Jorritsma, Jet van den Dijssel, Rivka de Jongh, Tom Ashhurst, Marit J van Gils, Mathieu Claireaux, Sija Marieke van Ham, Renée CF van Allaart, Adája E Baars, George Elias, Cécile ACM van Els, H Stephan Goedee, Geert RAM D’Haens, Papay BP Jallah, Elham S Mirfazeli, Jim BD Keijser, Lotte van Ouwerkerk, Pieter van Paassen, Agner R Parra Sanchez, W Ludo van der Pol, Corine RG Schreurs, R Bart Takkenberg, and Koos AH Zwinderman
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Medicine - Abstract
Objectives Methotrexate (MTX) is one of the most commonly used medications to treat rheumatoid arthritis (RA). However, the effect of MTX treatment on cellular immune responses remains incompletely understood. This raises concerns about the vulnerability of these patients to emerging infections and following vaccination.Methods In the current study, we investigated the impact of MTX treatment in patients with immune-mediated inflammatory disease on B and CD4 T cell SARS-CoV-2 vaccination responses. Eighteen patients with RA and two patients with psoriatic arthritis on MTX monotherapy were included, as well as 10 patients with RA without immunosuppressive treatment, and 29 healthy controls. CD4 T and B cell responses were analysed 7 days and 3–6 months after two SARS-CoV-2 messenger RNA vaccinations. High-dimensional flow cytometry analysis was used to analyse fresh whole blood, an activation-induced marker assay to measure antigen-specific CD4 T cells, and spike probes to study antigen-specific B cells.Results Seven days following two SARS-CoV-2 vaccinations, total B and T cell counts were similar between MTX-treated patients and controls. In addition, spike-specific B cell frequencies were unaffected. Remarkably, the frequency of antigen-specific CD4 T cells was reduced in patients using MTX and correlated strongly with anti-RBD IgG antibodies. These results suggest that decreased CD4 T cell activity may result in slower vaccination antibody responses in MTX-treated patients.Conclusion Taken together, MTX treatment reduces vaccine-induced CD4 T cell activation, which correlates with lower antibody responses.Trial registration number NL8900.
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- 2024
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26. Development of human innate immune responses in a humanized mouse model expressing four human myelopoiesis transgenes
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Hannah Stocks, Elisabeth De Leeuw, Bart N. Lambrecht, Linos Vandekerckhove, Geert van Loo, and Andy Wullaert
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humanized mice ,innate immunity ,myeloid cells ,cytokines ,inflammasome ,Immunologic diseases. Allergy ,RC581-607 - Abstract
BackgroundDysregulated innate immune responses underlie multiple inflammatory diseases, but clinical translation of preclinical innate immunity research in mice is hampered by the difficulty of studying human inflammatory reactions in an in vivo context. We therefore sought to establish in vivo human inflammatory responses in NSG-QUAD mice that express four human myelopoiesis transgenes to improve engraftment of a human innate immune system.MethodsWe reconstituted NSG-QUAD mice with human hematopoietic stem and progenitor cells (HSPCs), after which we evaluated human myeloid cell development and subsequent human responses to systemic and local lipopolysaccharide (LPS) challenges.ResultsNSG-QUAD mice already displayed engraftment of human monocytes, dendritic cells and granulocytes in peripheral blood, spleen and liver at 6 weeks after HSPC reconstitution, in which both classical, intermediate and non-classical monocytes were present. These huNSG-QUAD mice responded to intraperitoneal and intranasal LPS challenges with production of NF-κB-dependent human cytokines, a human type I interferon response, as well as inflammasome-mediated production of human IL-1β and IL-18. The latter were specifically abrogated by the NLRP3 inhibitor MCC950, while LPS-induced human monocyte death was not altered. Besides providing proof-of-principle for small molecule testing of human inflammatory reactions in huNSG-QUAD mice, this observation suggests that LPS-induced in vivo release of human NLRP3 inflammasome-generated cytokines occurs in a cell death-independent manner.ConclusionHuNSG-QUAD mice are competent for the NF-κB, interferon and inflammasome effectors of human innate immunity, and can thus be utilized to investigate signaling mechanisms and pharmacological targeting of human inflammatory responses in an in vivo setting.
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- 2024
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27. White matter integrity in hospitalized COVID-19 patients is not associated with short- and long-term clinical outcomes
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Theresa J. van Lith, Hao Li, Marte W. van der Wijk, Naomi T. Wijers, Wouter M. Sluis, Marieke J. H. Wermer, Frank-Erik de Leeuw, Frederick J. A. Meijer, and Anil M. Tuladhar
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COVID-19 ,white matter integrity ,NODDI ,DTI ,MRI ,DWI ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
ObjectivesSARS-CoV-2 infection is associated with a decline in functional outcomes; many patients experience persistent symptoms, while the underlying pathophysiology remains unclear. This study investigated white matter (WM) integrity on brain MRI in hospitalized COVID-19 patients and its associations with clinical outcomes, including long COVID.Materials and methodsWe included hospitalized COVID-19 patients and controls from CORONavirus and Ischemic Stroke (CORONIS), an observational cohort study, who underwent MRI-DWI imaging at baseline shortly after discharge (
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- 2024
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28. Sponge diversification in marine lakes: Implications for phylogeography and population genomic studies on sponges
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Maas, Diede L, Prost, Stefan, de Leeuw, Christiaan A, Bi, Ke, Smith, Lydia L, Purwanto, Purwanto, Aji, Ludi P, Tapilatu, Ricardo F, Gillespie, Rosemary G, and Becking, Leontine E
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Biological Sciences ,Ecology ,Genetics ,Prevention ,Human Genome ,Life Below Water ,genetic resolution ,marine biodiversity ,Porifera ,RADseq ,seascape genomics ,Suberites diversicolor ,Evolutionary Biology ,Evolutionary biology ,Ecological applications - Abstract
The relative influence of geography, currents, and environment on gene flow within sessile marine species remains an open question. Detecting subtle genetic differentiation at small scales is challenging in benthic populations due to large effective population sizes, general lack of resolution in genetic markers, and because barriers to dispersal often remain elusive. Marine lakes can circumvent confounding factors by providing discrete and replicated ecosystems. Using high-resolution double digest restriction-site-associated DNA sequencing (4826 Single Nucleotide Polymorphisms, SNPs), we genotyped populations of the sponge Suberites diversicolor (n = 125) to test the relative importance of spatial scales (1-1400 km), local environmental conditions, and permeability of seascape barriers in shaping population genomic structure. With the SNP dataset, we show strong intralineage population structure, even at scales
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- 2023
29. Flag Integrable Models and Generalized Graded Algebras
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de Leeuw, Marius, Nepomechie, Rafael I., and Retore, Ana L.
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High Energy Physics - Theory ,Mathematical Physics - Abstract
We introduce new classes of integrable models that exhibit a structure similar to that of flag vector spaces. We present their Hamiltonians, R-matrices and Bethe-ansatz solutions. These models have a new type of generalized graded algebra symmetry., Comment: 43 pages, 3 figures, v2: Bethe equations simplified, an appendix and references added, version accepted in JHEP
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- 2022
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30. Flood resilient landscapes: area-based solutions combine added value for society with flood risk management
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A. de Leeuw, E. Tromp, and F. de Boer
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Environmental sciences ,GE1-350 ,Geology ,QE1-996.5 - Abstract
Society faces challenges such as caring for sustainable agriculture, clean energy and restoring biodiversity, whilst developing housing and industries. Climate change meanwhile stresses the Dutch water management system, impacts flood risk management and fresh water supply. To ensure making the right decisions, which we will not regret in 100 years, we developed the concept of flood resilient landscapes. The concept of flood resilient landscapes confronts, with a perspective of long term development, desired socio-economic developments with carrying capacity and potential of underlying physical landscape conditions. The underlying principle is to create social added value while promoting or at least maintaining flood risk management, given (future) spatial and societal developments. The first results are so promising that the Dutch Flood Protection Programme aims to incorporate it. The flood resilient landscapes concept offers the prospect of keeping the Netherlands safe beyond 2100 at socially acceptable costs and with public support now and in the future and paves the way towards implementation throughout international deltas.
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- 2024
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31. Opposite effects of aerosols and meteorological parameters on warm clouds in two contrasting regions over eastern China
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Y. Liu, T. Lin, J. Zhang, F. Wang, Y. Huang, X. Wu, H. Ye, G. Zhang, X. Cao, and G. de Leeuw
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Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The sensitivity (S) of cloud parameters to the influence of different aerosol and meteorological parameters has in most previous aerosol–cloud interaction (aci) studies been addressed using traditional statistical methods. In the current study, relationships between cloud droplet effective radius (CER) and aerosol optical depth (AOD, used as a proxy for cloud condensation nuclei, CCN), i.e., the sensitivity (S) of CER to AOD, are investigated with different constraints of AOD and cloud liquid water path (LWP). In addition to traditional statistical methods, the geographical detector method (GDM) is applied in this study to quantify the relative importance of the effects of aerosol and meteorological parameters, as well as their interaction, on S. Moderate Resolution Imaging Spectroradiometer (MODIS) C6 L3 data and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-5 reanalysis data, for the period from 2008 to 2022, were used to investigate aci over eastern China. Two contrasting areas were selected: the heavily polluted Yangtze River Delta (YRD) and a relatively clean area over the East China Sea (ECS). Linear regression analysis shows that CER decreases with the increase in AOD (negative S) in the moderately polluted atmosphere (0.1
0.3) over the YRD. Evaluation of S as function of the LWP shows that in the moderately polluted atmosphere over the ECS, S is negative in the LWP interval [40 g m−2, 200 g m−2], and the sensitivity of CER to AOD is substantially stronger as LWP is larger. In contrast, in the polluted atmosphere over the YRD, S is positive in the LWP interval [0 g m−2, 120 g m−2] and does not change notably as function of LWP in this interval. The study further shows that over the ECS, the CER is larger for higher low tropospheric stability (LTS) and relative humidity (RH) but lower for higher pressure vertical velocity (PVV). Over the YRD, there is no significant influence of LTS on the relationship between CER and AOD. The GDM has been used as an independent method to analyze the sensitivity of cloud parameters to AOD and meteorological parameters (RH, LTS and PVV). The GDM has also been used to analyze the effects of interactions between two parameters and thus obtain information on confounding meteorological effects on the aci. Over the ECS, cloud parameters are sensitive to almost all parameters considered except for cloud top pressure (CTP), and the sensitivity to AOD is larger than that to any of the meteorological factors. Among the meteorological factors, the cloud parameters are most sensitive to PVV and least sensitive to RH. Over the YRD, the explanatory power of the sensitivity of cloud parameters to AOD and meteorological parameters is much smaller than over the ECS, except for RH, which has a statistically significant influence on CTP and can explain 74 % of the variation of CTP. The results from the GDM analysis show that cloud parameters are more sensitive to the combination of aerosol and a meteorological parameter than to each parameter alone, but confounding effects due to co-variation of both parameters cannot be excluded. - Published
- 2024
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32. The Mood and Resilience in Offspring (MARIO) project: a longitudinal cohort study among offspring of parents with and without a mood disorder
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Annabel Vreeker, Melany Horsfall, Merijn Eikelenboom, Annemerle Beerthuizen, Veerle Bergink, Marco P. M. Boks, Catharina A. Hartman, Ricki de Koning, Max de Leeuw, Dominique F. Maciejewski, Brenda W. J. H. Penninx, and Manon H. J. Hillegers
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Mood disorder ,Major depressive disorder ,Bipolar disorder ,Intergenerational transmission ,Resilience ,Psychiatry ,RC435-571 - Abstract
Background One of the most robust risk factors for developing a mood disorder is having a parent with a mood disorder. Unfortunately, mechanisms explaining the transmission of mood disorders from one generation to the next remain largely elusive. Since timely intervention is associated with a better outcome and prognosis, early detection of intergenerational transmission of mood disorders is of paramount importance. Here, we describe the design of the Mood and Resilience in Offspring (MARIO) cohort study in which we investigate: 1. differences in clinical, biological and environmental (e.g., psychosocial factors, substance use or stressful life events) risk and resilience factors in children of parents with and without mood disorders, and 2. mechanisms of intergenerational transmission of mood disorders via clinical, biological and environmental risk and resilience factors. Methods MARIO is an observational, longitudinal cohort study that aims to include 450 offspring of parents with a mood disorder (uni- or bipolar mood disorders) and 100-150 offspring of parents without a mood disorder aged 10-25 years. Power analyses indicate that this sample size is sufficient to detect small to medium sized effects. Offspring are recruited via existing Dutch studies involving patients with a mood disorder and healthy controls, for which detailed clinical, environmental and biological data of the index-parent (i.e., the initially identified parent with or without a mood disorder) is available. Over a period of three years, four assessments will take place, in which extensive clinical, biological and environmental data and data on risk and resilience are collected through e.g., blood sampling, face-to-face interviews, online questionnaires, actigraphy and Experience Sampling Method assessment. For co-parents, information on demographics, mental disorder status and a DNA-sample are collected. Discussion The MARIO cohort study is a large longitudinal cohort study among offspring of parents with and without mood disorders. A unique aspect is the collection of granular data on clinical, biological and environmental risk and resilience factors in offspring, in addition to available parental data on many similar factors. We aim to investigate the mechanisms underlying intergenerational transmission of mood disorders, which will ultimately lead to better outcomes for offspring at high familial risk.
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- 2024
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33. Identification of a Novel CYP11B2 Variant in a Family with Varying Degrees of Aldosterone Synthase Deficiency
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Mark R. Garrelfs, Tuula Rinne, Jacquelien J. Hillebrand, Peter Lauffer, Merijn W. Bijlsma, Hedi L. Claahsen-van der Grinten, Nicole de Leeuw, Martijn J.J. Finken, Joost Rotteveel, Nitash Zwaveling-Soonawala, Max Nieuwdorp, A.S. Paul van Trotsenburg, and Christiaan F. Mooij
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aldosterone synthase ,mineralocorticoid ,cyb11b2 ,hypoaldosteronism ,Pediatrics ,RJ1-570 ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Isolated aldosterone synthase deficiency is a rare autosomal recessive disorder caused by pathogenic variants in CYP11B2, resulting in impaired aldosterone synthesis. We report on a neonate with isolated aldosterone synthase deficiency caused by a novel homozygous CYP11B2 variant Chr8: NM_000498.3: c.400G>A p.(Gly134Arg). The patient presented shortly after birth with severe signs of aldosterone deficiency. Interestingly, segregation analysis revealed that the patient's asymptomatic father was also homozygous for the CYP11B2 variant. Biochemical evaluation of the father indicated subclinical enzyme impairment, characterized by elevated aldosterone precursors. Apparently, this homozygous variant led to different clinical phenotypes in two affected relatives. In this manuscript we elaborate on the biochemical and genetic work-up performed and describe potential pitfalls in CYP11B2 sequencing due to its homology to CYP11B1.
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- 2024
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34. Three-dimensional identification of microvascular pathology and neurovascular inflammation in severe white matter hyperintensity: a case report
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Gemma Solé-Guardia, Matthijs Luijten, Bram Geenen, Jurgen A. H. R. Claassen, Geert Litjens, Frank-Erik de Leeuw, Maximilian Wiesmann, and Amanda J. Kiliaan
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Medicine ,Science - Abstract
Abstract White matter hyperintensities (WMH) are the most prevalent markers of cerebral small vessel disease (SVD), which is the major vascular risk factor for dementia. Microvascular pathology and neuroinflammation are suggested to drive the transition from normal-appearing white matter (NAWM) to WMH, particularly in individuals with hypertension. However, current imaging techniques cannot capture ongoing NAWM changes. The transition from NAWM into WMH is a continuous process, yet white matter lesions are often examined dichotomously, which may explain their underlying heterogeneity. Therefore, we examined microvascular and neurovascular inflammation pathology in NAWM and severe WMH three-dimensionally, along with gradual magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) signal (sub-)segmentation. In WMH, the vascular network exhibited reduced length and complexity compared to NAWM. Neuroinflammation was more severe in WMH. Vascular inflammation was more pronounced in NAWM, suggesting its potential significance in converting NAWM into WMH. Moreover, the (sub-)segmentation of FLAIR signal displayed varying degrees of vascular pathology, particularly within WMH regions. These findings highlight the intricate interplay between microvascular pathology and neuroinflammation in the transition from NAWM to WMH. Further examination of neurovascular inflammation across MRI-visible alterations could aid deepening our understanding on WMH conversion, and therewith how to improve the prognosis of SVD.
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- 2024
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35. Genome sequencing as a generic diagnostic strategy for rare disease
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Gaby Schobers, Ronny Derks, Amber den Ouden, Hilde Swinkels, Jeroen van Reeuwijk, Ermanno Bosgoed, Dorien Lugtenberg, Su Ming Sun, Jordi Corominas Galbany, Marjan Weiss, Marinus J. Blok, Richelle A. C. M. Olde Keizer, Tom Hofste, Debby Hellebrekers, Nicole de Leeuw, Alexander Stegmann, Erik-Jan Kamsteeg, Aimee D. C. Paulussen, Marjolijn J. L. Ligtenberg, Xiangqun Zheng Bradley, John Peden, Alejandra Gutierrez, Adam Pullen, Tom Payne, Christian Gilissen, Arthur van den Wijngaard, Han G. Brunner, Marcel Nelen, Helger G. Yntema, and Lisenka E. L. M. Vissers
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Rare disease ,Genome sequencing ,Impact modeling ,Reducing workflow complexity ,Genetic diagnostic laboratories ,Germline variant detection ,Medicine ,Genetics ,QH426-470 - Abstract
Abstract Background To diagnose the full spectrum of hereditary and congenital diseases, genetic laboratories use many different workflows, ranging from karyotyping to exome sequencing. A single generic high-throughput workflow would greatly increase efficiency. We assessed whether genome sequencing (GS) can replace these existing workflows aimed at germline genetic diagnosis for rare disease. Methods We performed short-read GS (NovaSeq™6000; 150 bp paired-end reads, 37 × mean coverage) on 1000 cases with 1271 known clinically relevant variants, identified across different workflows, representative of our tertiary diagnostic centers. Variants were categorized into small variants (single nucleotide variants and indels
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- 2024
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36. The impact of mental state altering medications on preventable falls after total hip or total knee arthroplasty: a systematic review and meta-analysis
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Elsbeth J. Wesselink, Marinus van der Vegt, Sharon Remmelzwaal, Sebastiaan M. Bossers, Eric J. Franssen, Eleonora L. Swart, Christa Boer, and Marcel A. de Leeuw
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Surgery ,RD1-811 - Abstract
Abstract Background Joint replacement surgery of the lower extremities are common procedures in elderly persons who are at increased risk of postoperative falls. The use of mental state altering medications, such as opioids, antidepressants or benzodiazepines, can further contribute to impaired balance and risk of falls. The objective of the current systematic review was to evaluate the risk of the use of mental state altering medications on postoperative falls in patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA). Methods A comprehensive search of Medline, Embase and Cochrane Controlled Trials Register was conducted from 1 October 1975 to 1 September 2021. The search was repeated in may 2023 and conducted from 1 October 1975 to 1 June 2023. Clinical trials that evaluated the risk of medication on postoperative THA and TKA falls were eligible for inclusion. Articles were evaluated independently by two researchers for risk of bias using the Newcastle-Ottawa Scale. A meta-analysis was performed to determine the potential effect of postoperative use of mental state altering medications on the risk of falls. Lastly, a qualitative synthesis was conducted for preoperative mental state altering medications use. Results Seven cohort studies were included, of which five studies focussed on the postoperative use of mental state altering medications and two investigated the preoperative use. Meta-analysis was performed for the postoperative mental state altering medications use. The postoperative use of mental state altering medications was associated with fall incidents (OR: 1.81; 95% CI: 1.04; 3.17) (p 6 months was associated with a higher risk of fall incidents, whereas a preoperative opioid prescription up to 3 months before a major arthroplasty had a similar risk as opioid-naïve patients. Conclusions The postoperative use of mental state altering medications increases the risk of postoperative falls after THA and TKA. Prior to surgery, orthopaedic surgeons and anaesthesiologists should be aware of the associated risks in order to prevent postoperative falls and associated injuries.
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- 2024
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37. The Bethe ansatz for a new integrable open quantum system
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de Leeuw, Marius and Paletta, Chiara
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Condensed Matter - Statistical Mechanics ,High Energy Physics - Theory ,Mathematical Physics ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
In this paper we apply the nested algebraic Bethe ansatz to compute the eigenvalues and the Bethe equations of the transfer matrix of the new integrable Lindbladian found in [1]. We show that it can be written as an integrable spin chain consisting of two interacting XXZ spin chains. We numerically compute the Liouville gap and its dependence on the parameters in the system such as scaling with the system length and interaction strength., Comment: 33 pages, 6 figures
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- 2022
38. Lifting integrable models and long-range interactions
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de Leeuw, Marius and Retore, Ana. L.
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High Energy Physics - Theory ,Mathematical Physics - Abstract
In this paper we discuss a constructive approach to check whether a constant Hamiltonian is Yang-Baxter integrable. We then apply our method to long-range interactions and find the Lax operator and $R$-matrix of the two-loop SU(2) sector in N=4 SYM. We show that all known integrable long-range deformations of the 6-vertex models of this type can be obtained from a Lax operator and an $R$-matrix. Finally we discuss what happens at higher loops and highlight some general structures that these models seem to exhibit., Comment: 21 pages, v2: added two references, minor corrections, v3: added few comments, minor corrections
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- 2022
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39. Visit-to-visit blood pressure variability and progression of white matter hyperintensities over 14 years
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Esther Janssen, Jan Willem van Dalen, Mengfei Cai, Mina A. Jacob, José Marques, Marco Duering, Edo Richard, Anil M. Tuladhar, Frank-Erik de Leeuw, and Nina Hilkens
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Cerebral small vessel disease ,blood pressure variability ,white matter hyperintensity ,magnetic resonance imaging ,hypertension ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
AbstractPurpose: There is evidence that blood pressure variability (BPV) is associated with cerebral small vessel disease (SVD) and may therefore increase the risk of stroke and dementia. It remains unclear if BPV is associated with SVD progression over years. We examined whether visit-to-visit BPV is associated with white matter hyperintensity (WMH) progression over 14 years and MRI markers after 14 years.Materials and methods: We included participants with SVD from the Radboud University Nijmegen Diffusion tensor Magnetic resonance-imaging Cohort (RUNDMC) who underwent baseline assessment in 2006 and follow-up in 2011, 2015 and 2020. BPV was calculated as coefficient of variation (CV) of BP at all visits. Association between WMH progression rates over 14 years and BPV was examined using linear-mixed effects (LME) model. Regression models were used to examine association between BPV and MRI markers at final visit in participants.Results: A total of 199 participants (60.5 SD 6.6 years) who underwent four MRI scans and BP measurements were included, with mean follow-up of 13.7 (SD 0.5) years. Systolic BPV was associated with higher progression of WMH (β = 0.013, 95% CI 0.005 − 0.022) and higher risk of incident lacunes (OR: 1.10, 95% CI 1.01–1.21). There was no association between systolic BPV and grey and white matter volumes, Peak Skeleton of Mean Diffusivity (PSMD) or microbleed count after 13.7 years.Conclusions: Visit-to-visit systolic BPV is associated with increased progression of WMH volumes and higher risk of incident lacunes over 14 years in participants with SVD. Future studies are needed to examine causality of this association.
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- 2024
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40. Australian and Canadian financial wellbeing policy landscape during COVID-19: An equity-informed policy scan
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Ana Paula Belon, Aryati Yashadhana, Krystyna Kongats, Kayla Atkey, Nicole M. Glenn, Karla Jaques, Laura Nieuwendyk, Patrick Harris, Evelyne de Leeuw, and Candace I.J. Nykiforuk
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Poverty ,Financial stress ,COVID-19 ,Policy ,Government programs ,Equity ,Public aspects of medicine ,RA1-1270 - Abstract
Background: This targeted and comprehensive policy scan examined how different levels of governments in Australia and Canada responded to the financial crisis brought on by the COVID-19 pandemic. We mapped the types of early policy responses addressing financial strain and promoting financial wellbeing. We also examined their equity considerations. Methods: Through a systematic search, snowballing, and manual search, we identified Canadian and Australian policies at all government levels related to financial strain or financial wellbeing enacted or amended in 2019–2020. Using a deductive-inductive approach, policies were categorized by jurisdiction level, focal areas, and target population groups. Results: In total, 213 and 97 policies in Canada and Australia, respectively, were included. Comparisons between Canadian and Australian policies indicated a more diversified and equity-targeted policy landscape in Canada. In both countries, most policies focused on individual and family finances, followed by housing and employment areas. Conclusions: The policy scan identified gaps and missed opportunities in the early policies related to financial strain and financial wellbeing. While fast, temporary actions addressed individuals’ immediate needs, we recommend governments develop a longer-term action plan to tackle the root causes of financial strain and poor financial wellbeing for better health and non-health crisis preparedness. Statement on Ethics and Informed Consent: This research reported in this paper did not require ethical clearance or patient informed consent as the data sources were published policy documents. This study did not involve data collection with humans (or animals), nor any secondary datasets involving data provided by humans (or from animal studies).
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- 2024
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41. Improved approximation and visualization of the correlation matrix.
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Graffelman, Jan and De Leeuw, Jan
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biplot ,correlogram ,multidimensional scaling ,principal component analysis ,principal factor analysis ,weighted alternating least squares - Abstract
The graphical representation of the correlation matrix by means of different multivariate statistical methods is reviewed, a comparison of the different procedures is presented with the use of an example data set, and an improved representation with better fit is proposed. Principal component analysis is widely used for making pictures of correlation structure, though as shown a weighted alternating least squares approach that avoids the fitting of the diagonal of the correlation matrix outperforms both principal component analysis and principal factor analysis in approximating a correlation matrix. Weighted alternating least squares is a very strong competitor for principal component analysis, in particular if the correlation matrix is the focus of the study, because it improves the representation of the correlation matrix, often at the expense of only a minor percentage of explained variance for the original data matrix, if the latter is mapped onto the correlation biplot by regression. In this article, we propose to combine weighted alternating least squares with an additive adjustment of the correlation matrix, and this is seen to lead to further improved approximation of the correlation matrix.
- Published
- 2023
42. The added value of a face-to-face pan-European course—what makes it worth it?
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Robert de Leeuw, Judith A. F. Huirne, Christiano Rositto, Mohammed Mabrouk, Pierre Barri, Marlies Bongers, Andreas Thurkow, Ahmed El-Balat, Nikon Vlahos, and Hans Brolmann
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continuous education ,European education ,intercultural competence ,skills education ,digital education ,Medicine (General) ,R5-920 - Abstract
IntroductionOver the past decade, digital education has seen widespread adoption, particularly accentuated during the COVID-19 pandemic. The post-COVID era has further emphasized the advantages of digital education in terms of cost, availability, and sustainability. However, concerns regarding the efficacy of digital education, particularly in skills-based learning and the absence of social interaction, have been raised. This paper will look at the added value of international, face-to-face, skills-based courses.MethodThis study evaluates the potential added value of face-to-face international skills courses using the European “Gynecology Experts Training for Upcoming Professionals” (GET-UP) course. Focus group discussions were conducted with participants and faculty members to explore beliefs, attitudes, and perceptions regarding face-to-face learning. Qualitative analysis was performed using thematic analysis to identify domains of added value.ResultsThe GET-UP course, conducted over 4 days with a diverse European faculty and participants, highlighted several added-value domains. Themes including diversity, role models, preparation, live interaction, and community emerged from the analysis, emphasizing the significance of face-to-face interaction in enriching the learning experience beyond attaining learning goals.DiscussionThe study underscores the importance of face-to-face interaction in educational settings, offering insights into diverse teaching methods, role modeling opportunities, enhanced preparation, live interactions, and fostering a sense of community. While digital education continues to evolve with interactive features, this study suggests that the inherent pressure and dynamics of face-to-face learning provide unique benefits that may not be easily replicated in digital environments. Future research should investigate and validate these findings further to inform educational practices effectively.
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- 2024
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43. Introducing and discussing the virtual special issue on using Q methodology in higher education
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Adrian Lundberg and Renske Ria de Leeuw
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Q methodology ,Higher education ,Subjectivity ,Pedagogical applications ,Theory and practice of education ,LB5-3640 - Abstract
This is the editorial paper for the virtual special issue “Using Q methodology in higher education: Opportunities and challenges”, consisting of nine original research studies from different international contexts. In addition to presenting novel findings, contributors were invited to discuss the following two questions at the center of the special issue call: In what sense has Q methodology served as a fitting approach to investigate subjectivity in higher education? What methodological opportunities and challenges arise with Q methodology in higher education settings? This editorial provides an overview and discussion of the various justifications mentioned for Q methodology. Furthermore, it collates the opportunities and challenges contributors discuss in relation to their studies using this almost 90-year-old methodological approach. The editorial paper concludes with recommendations for future Q methodological studies in higher education and beyond.
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- 2024
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44. The role of dendritic cells in respiratory viral infection
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Elisabeth De Leeuw and Hamida Hammad
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Diseases of the respiratory system ,RC705-779 - Abstract
Respiratory viral infections represent one of the major causes of death worldwide. The recent coronavirus disease 2019 pandemic alone claimed the lives of over 6 million people around the globe. It is therefore crucial to understand how the immune system responds to these threats and how respiratory infection can be controlled and constrained. Dendritic cells (DCs) are one of the key players in antiviral immunity because of their ability to detect pathogens. They can orchestrate an immune response that will, in most cases, lead to viral clearance. Different subsets of DCs are present in the lung and each subset can contribute to antiviral responses through various mechanisms. In this review, we discuss the role of the different lung DC subsets in response to common respiratory viruses, with a focus on respiratory syncytial virus, influenza A virus and severe acute respiratory syndrome coronavirus 2. We also review how lung DC-mediated responses to respiratory viruses can lead to the worsening of an existing chronic pulmonary disease such as asthma. Throughout the review, we discuss results obtained from animal studies as well as results generated from infected patients.
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- 2024
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45. Evaluation of the first year of Pandora NO2 measurements over Beijing and application to satellite validation
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O. Liu, Z. Li, Y. Lin, C. Fan, Y. Zhang, K. Li, P. Zhang, Y. Wei, T. Chen, J. Dong, and G. de Leeuw
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Environmental engineering ,TA170-171 ,Earthwork. Foundations ,TA715-787 - Abstract
Nitrogen dioxide (NO2) is a highly photochemically reactive gas, has a lifetime of only a few hours, and at high concentrations is harmful to human beings. Therefore, it is important to monitor NO2 with high-precision, time-resolved instruments. To this end, a Pandora spectrometer has been installed on the roof of the laboratory building of the Aerospace Information Research Institute of the Chinese Academy of Sciences in the Olympic Park, Beijing, China. The concentrations of trace gases (including NO2, HCHO, O3) measured with Pandora are made available through the open-access Pandora database (https://data.pandonia-global-network.org/Beijing-RADI/Pandora171s1/, last access: 11 July 2023). In this paper, an overview is presented of the Pandora total and tropospheric NO2 vertical column densities (VCDs) and surface concentrations collected during the first year of operation, i.e., from August 2021 to July 2022. The data show that NO2 concentrations were high in the winter and low in the summer, with a diurnal cycle where the concentrations reached a minimum during the daytime. The concentrations were significantly lower during the 2022 Winter Olympics in Beijing, showing the effectiveness of the emission control measures during that period. The Pandora observations show that during northerly winds, clean air is transported to Beijing with low NO2 concentrations, whereas during southerly winds, pollution from surrounding areas is transported to Beijing and NO2 concentrations are high. The contribution of tropospheric NO2 to the total NO2 VCD varies significantly on daily to seasonal timescales; i.e., monthly averages vary between 50 % and 60 % in the winter and between 60 % and 70 % in the spring and autumn. A comparison of Pandora-measured surface concentrations with collocated in situ measurements using a Thermo Scientific 42i-TL analyzer shows that the Pandora data are low and that the relationship between Pandora-derived surface concentrations and in situ measurements is different for low and high NO2 concentrations. Explanations for these differences are offered in terms of measurement techniques and physical (transport) phenomena. The use of Pandora total and tropospheric NO2 VCDs for validation of collocated TROPOspheric Monitoring Instrument (TROPOMI) data, resampled to 100 m × 100 m, shows that although on average the TROPOMI VCDs are slightly lower, they are well within the expected error for TROPOMI of 0.5 Pmolec.cm-2 + (0.2 to 0.5) ⋅ VCDtrop (1 Pmolec.cm-2 = 1 × 1015 molec cm−2). The location of the Pandora instrument within a sub-orbital TROPOMI pixel of 3.5 km × 5.5 km may result in an error in the TROPOMI-derived tropospheric NO2 VCD between 0.223 and 0.282 Pmolec.cm-2, i.e., between 1.7 % and 2 %. In addition, the data also show that the Pandora observations at the Beijing-RADI site are representative of an area with a radius of 10 km.
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- 2024
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46. The Generative Mechanisms of Financial Strain and Financial Well-Being: A Critical Realist Analysis of Ideology and Difference
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Nicole M. Glenn, Aryati Yashadhana, Karla Jaques, Ana Belon, Evelyne de Leeuw, Candace I. J. Nykiforuk, and Patrick Harris
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critical realism ,financial well-being ,financial strain ,covid-19 ,inequities ,public health ,Public aspects of medicine ,RA1-1270 - Abstract
Background Rapid, strategic action is required to mitigate the negative and unequal impact of the coronavirus disease 2019 (COVID-19) pandemic on the financial well-being (FWB) of global populations. Personal financial strain (FS) worsened most significantly among systematically excluded groups. Targeted government- and community-led initiatives are needed to address these inequities. The purpose of this applied research was to identify what works for whom, under what conditions, and why in relation to community and government initiatives that promote personal and household FWB and/or address FS in high income economies. Methods We employed a critical realist analysis to literature that reported on FWB/FS initiatives in high income countries. This included initiatives introduced in response to the pandemic as well as those that began prior to the pandemic. We included sources based on a rapid review. We coded academic, published literature (n = 39) and practicebased (n = 36) reports abductively to uncover generative mechanisms – ie, underlying, foundational factors related to community or government initiatives that either constrained and/or enabled FWB and FS. Results We identified two generative mechanisms: (1) neoliberal ideology; and (2) social equity ideology. A third mechanism, social location (eg, characteristics of identity, location of residence), cut across the two ideologies and demonstrated for whom the initiatives worked (or did not) in what circumstances. Neoliberal ideology (ie, individual responsibility) dominated initiative designs, which limited the positive impact on FS. This was particularly true for people who occupied systematically excluded social locations (eg, low-income young mothers). Social equity-based initiatives were less common within the literature, yet mostly had a positive impact on FWB and produced equitable outcomes. Conclusion Equity-centric initiatives are required to improve FWB and reduce FS among systemically excluded and marginalized groups. These findings are of relevance now as nations strive for financial recovery in the face of the ongoing global pandemic.
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- 2023
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47. Evaluation of Cobalt, Nickel, and Palladium Complexes as Catalysts for the Hydrogenation and Improvement of Oxidative Stability of Biodiesel
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Fortunate P. Sejie, Olayinka A. Oyetunji, Banothile C. E. Makhubela, James Darkwa, and Nora H. de Leeuw
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biodiesel hydrogenation ,oxidative stability ,Rancimat method ,homogeneous catalysis ,Chemical technology ,TP1-1185 ,Chemistry ,QD1-999 - Abstract
Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)pyridin-2-ylmethylimine and N-(3-(triethoxysilyl)propyl)picolinamide were synthesized, characterized, and used as pre-catalysts in the transfer hydrogenation of C=C bonds in fatty acid methyl esters. The active catalysts from the Co, Ni, and Pd complexes sequentially hydrogenate the C18:2 chains to C18:1, which is further converted to C18:0 in the FAMEs of both methyl linoleate and jatropha biodiesel. The hydrogenation process was kinetically controlled, and after 3 h it yielded a biodiesel sample that contained 25.83% C16:0, 12.52% C18:2, 41.54% C18:1, 14.47% C18:0 and 3.0% C18:2 isomers. The un-hydrogenated jatropha diesel, hydrogenated jatropha diesel, and a B20 blend of jatropha were tested for susceptibility to oxidation reactions using the Rancimat method and FTIR spectroscopy, and the partial hydrogenation had improved the induction period by 3 h.
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- 2024
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48. Integrable deformations of AdS/CFT
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de Leeuw, Marius, Pribytok, Anton, Retore, Ana L., and Ryan, Paul
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High Energy Physics - Theory ,Mathematical Physics - Abstract
In this paper we study in detail the deformations introduced in [1] of the integrable structures of the AdS$_{2,3}$ integrable models. We do this by embedding the corresponding scattering matrices into the most general solutions of the Yang-Baxter equation. We show that there are several non-trivial embeddings and corresponding deformations. We work out crossing symmetry for these models and study their symmetry algebras and representations. In particular, we identify a new elliptic deformation of the $\rm AdS_3 \times S^3 \times M^4$ string sigma model., Comment: v2: We corrected typos and added some references; v3: corrected crossing for AdS2 deformation
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- 2021
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49. Multispecies fish tracking across newly created shallow and deep habitats in a forward-restored lake
- Author
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van Leeuwen, Casper H. A., de Leeuw, Joep J., van Keeken, Olvin A., Volwater, Joey J. J., Seljee, Ferdi, van Aalderen, Roland, van Emmerik, Willie A. M., and Bakker, Elisabeth S.
- Published
- 2023
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50. Rare variant aggregation in 148,508 exomes identifies genes associated with proxy dementia
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Wightman, Douglas P., Savage, Jeanne E., de Leeuw, Christiaan A., Jansen, Iris E., and Posthuma, Danielle
- Published
- 2023
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