Titel Deelnemers "Korte inhoud" "Barcoding hybrids: heterogeneous distribution of Schistosoma haematobium × Schistosoma bovis hybrids across the Senegal River Basin" "Nele Boon, Frederik Van den Broeck, Djiby Faye, Filip A M Volckaert, Souleymane Mboup, Katja Polman, Tine Huyse" "ABSTRACTHybridization events between Schistosoma species (Digenea, Platyhelminthes) are reported with increasing frequency, largely due to improved access to molecular tools. Nevertheless, little is known about the distribution and frequency of hybrid schistosomes in nature. Screening for hybrids on a large scale is complicated by the need for nuclear and mitochondrial sequence information, precluding a 'simple' barcoding approach. Here we aimed to determine and understand the spatiotemporal distribution of Schistosoma haematobium × Schistosoma bovis hybrids in the Senegal River Basin. From ten villages, distributed over the four main water basins, we genotyped a total of 1236 schistosome larvae collected from human urine samples using a partial mitochondrial cox1 fragment; a subset of 268 parasites was also genotyped using ITS rDNA. Hybrid schistosomes were unevenly distributed, with substantially higher numbers in villages bordering Lac de Guiers than in villages from the Lampsar River and the Middle Valley of the Senegal River. The frequency of hybrids per village was not linked with the prevalence of urinary schistosomiasis in that village. However, we did find a significant positive association between the frequency of hybrids per village and the prevalence of Schistosoma mansoni. We discuss the potential consequences of adopting a barcoding approach when studying hybrids in nature." "Screening of banana hybrids (phase II hybrids) for resistance to Meloidogyne incognita" "Inge Van den Bergh, Dirk De Waele" "Banana and plantains (Musa spp.), the second largest fruit crop in the world, are important staple foods in tropical regions of Africa, America, Asia and the Pacific. It is the most widely consumed and exported fruit in the world. Plant parasitic nematodes are one of the major biotic stresses affecting banana production. Breeding works carried out at the Department of Fruit Crops, Tamil Nadu Agricultural University, India. The potential diploids and hybrids developed were crossed with commercial triploids to develop primary tetraploids and improved diploids. The susceptible check cultivar used was 'Rasthali' (AAB), while the resistant reference cultivar used 'Pisang Lilin' (AA). Banana suckers of uniform size and weight were collected, pared and planted in earthen part containing 5 kg sterilized pot mixture. Egg masses of M. incognita were picked from roots, allowed to hatch in a beaker of distilled water and the hatched juveniles (J2) were inoculated in the rhizosphere of the hybrids by soil injection method at 5,000 nematodes/pot. Same set of replicated banana hybrids were also maintained as uninoculated check. The reactions of nineteen new synthetic banana phase II hybrids to M. incognita was studied under field conditions as well as in controlled inoculation tests in pots. Hybrid H 531 ('Poovan' 'Pisang Lilin') was found to be resistant and six hybrids, H-02-34, H-03-05, H-03-13, H-04-12, H-04-24 and NPH-02-01 were found to be tolerant to the root-knot nematode, M. incognita while the remaining were rated as susceptible and highly susceptible ones. Total phenols and PO, PPO, PAL and enzymatic activity of the hybrids in defense mechanism in response to nematode invasion indicated higher activities in resistant genotypes compared to susceptible ones. The total phenol in the roots was estimated using Folin Ciocalteau reagent and measuring absorption at 660 nm in a spectrophotometer. For enzyme extraction, one gram of root sample per replicate was homogenized with 2ml of 0.1 M sodium phosphate buffer (pH 7.0) at 4C. The supernatant was used as crude enzyme extract for assaying PO and PPO. Enzyme extracted in borate buffer was used for estimation of PAL. The PO activity was assessed according to Hammer-Schmidt and the PPO activity was assessed using the modified method of Mayer. Hybrid H 531 had the maximum biochemical content and enzyme activity among the hybrids included in this study. The resistant and tolerant hybrids had enhanced contents of total phenol, PO, PPO and PAL." "Screening of Banana Hybrids (Phase II Hybrids) for Resistance to Helicotylenchus multicinctus" "Inge Van den Bergh, Dirk De Waele" "Banana (Musa spp.) which is truly a tropical treasure is being targeted by many pests and diseases. Worldwide, nematodes are considered a very important pest of bananas and plantains, for which control measures are urgently requirement. By damaging the plant root system, nematodes not only hamper the uptake of water and nutrients and consequently the growth and fruit production. Helicotylenchus multicinctus is considered to be an endoparasite in banana. It completes its life cycle within the root cortex where both the sexes, all juvenile stages and eggs can be found. It produces shallow superficial lesions in banana roots which resemble pustule like eruptions. The breeding programme and experiment was carried out at Horticultural College and Research Institute, Department of Fruit Crops, Tamil Nadu Agricultural University, Coimbatore, India and screened against H. multicinctus. The potential diploids and hybrids developed were crossed with commercial triploids to develop primary tetraploids and improved diploids. Banana suckers of uniform size and weight were collected, pared and planted in earthen pot containing 5 kg sterilized pot mixture. The hybrids were evaluated along with the reference cultivars viz., 'Rasthali' (AAB, syn. 'Silk') as the susceptible reference cultivar and 'Pisang Lilin' (AA) as the resistant reference cultivar. The screening was done based on the root and corm damage assessment as followed in INIBAP Technical Guidelines 7. The reactions of nineteen new synthetic banana phase II hybrids to H. multicinctus was studied under field as well as artificially inoculated pot conditions. The hybrid H 531 ('Poovan' 'Pisang Lilin') exhibited resistance, while hybrids H-02-34, H-03-05, H-03-13, H-03-17, H-04-12, H-04-24, NPH-02-01 and H 510 showed tolerance. The role of biochemical contents like total henols and enzymatic activity like PO, PPO and PAL revealed that they had higher levels of activities in resistant and tolerant genotypes compare to susceptible and highly susceptible ones. The total phenol in the roots was estimated using Folin Ciocalteau reagent and measuring absorption at 660 nm in a spectrophotometer. For enzyme extraction, one gram of root sample per replicate was homogenized with 2 ml of 0.1 M sodium phosphate buffer (pH 7.0) at 4C. The supernatant was used as crude enzyme extract for assaying PO and PPO. Enzyme extracted in borate buffer was used for estimation of PAL. The PO activity was assessed according to Hammerschmidt and the PPO activity was assessed using the modified method of Mayer. The hybrid H 531 (AAB) took the shortest duration of 213.00 days for shooting and recorded a moderate bunch weight of 13.50 kg." "Study on the Dynamics of Phase Formation and Degradation of 2D Layered Hybrid Perovskites and Low-dimensional Hybrids Containing Mono-functionalized Oligothiophene Cations" "Wouter VAN GOMPEL, Roald HERCKENS, Martijn MERTENS, Paul-Henry DENIS, Bart RUTTENS, Jan D'HAEN, K Van Hecke, Laurence LUTSEN, Dirk VANDERZANDE" "Low-dimensional (2D or 1D) hybrid perovskites are receiving increased attention due to their structural flexibility and enhanced stability compared to their 3D counterparts. Understanding the phase formation and degradation behavior of these materials is crucial towards their use in optoelectronic devices, since different crystal phases possess different optical and electronic properties. In this communication, we study the phase formation and degradation of a series of hybrids containing bithiophene, terthiophene and quaterthiophene derivatives. We show that two crystal phases can be formed for each of these systems, depending on the processing conditions. One phase corresponds to a 2D layered perovskite and the other phase has optical properties corresponding to a dimensionality intermediate between a 2D and a 1D hybrid." "Hybrid chemistry. Part 4: Discovery of etravirine-VRX-480773 hybrids as potent HIV-1 non-nucleoside reverse transcriptase inhibitors" "Erik De Clercq, Dirk Daelemans, Christophe Pannecouque" "A novel series of etravirine-VRX-480773 hybrids were designed using structure-guided molecular hybridization strategy and fusing the pharmacophore templates of etravirine and VRX-480773. The anti-HIV-1 activity and cytotoxicity was evaluated in MT-4 cell cultures. The most active hybrid compound in this series, N-(2-chlorophenyl)-2-((4-(4-cyano-2,6-dimethylphenoxy)pyrimidin-2-yl)thio)acetamide 3d (EC50=0.24 , SI>1225), was more potent than delavirdine (EC50=0.66μM, SI>67) in the anti-HIV-1 in vitro cellular assay. Studies of structure-activity relationships established a correlation between anti-HIV activity and the substitution pattern of the acetanilide group." "The dynamics of phase formation and degradation of 2D layered hybrid perovskites and low-dimensional hybrids containing mono-functionalized oligothiophene cations" "Wouter T.M. Van Gompel, Paul-Henry Denis, Martijn Mertens, Bart Ruttens, Jan D'Haen, Kristof Van Hecke, Laurence Lutsen, Dirk Vanderzande" "Impact of Plug-In Hybrid Electric Vehicles on the Electricity System (Invloed van plug-in hybride elektrische voertuigen op het elektriciteitssysteem)" "Plug-in hybrid electric vehicles, are rapidly gaining interest. Batteries of plug-in hybrid electric vehicles are charged by either plugging into electric outlets or by an on-board generator. For grid charging, these batteries are supplied by power from the grid at home from a standard outlet or on a corporate car park. The extra electrical load, from charging the batteries, has an impact on the electricity system in general and more specifically on the distribution grid and the electricity generation system. The impact of such vehicles on the distribution grid is analyzed in terms of power losses and voltage deviations. The impact on the electricity generation system is investigated in terms of available generation capacity. Uncoordinated charging of plug-in hybrid electric vehicles may cause local grid problems. These grid problems can be avoided by coordinated charging. The aim is to determine the optimal charge pro¯le for each vehicle and to minimize the impact on the electricity system. For the coordination, the linear or quadratic programming technique is found to be the most e±cient and is applied for this optimization problem. Plug-in hybrid electric vehicles cannot onlycharge when connected to the grid, but also discharge and thus inject power. In that way, electric vehicles may offer grid services to support the grid. It is not clear whether offering grid services is economic forthese vehicles. A voltage controller could be easily implemented in the charger and the grid services may be enabled. Such a controller avoids large voltage deviations at the household level. The vehicles may also be matched with distributed generation units such as combined heat and power units, small-scale wind turbines and photovoltaicpanels. If there is power or energy produced by these units, the batteries of the vehicle could be charged with this energy and their curtailment due to grid congestion is avoided. Charging of plug-in hybrid electric vehicles also has an impact on the electricity generationsystem. When the penetration level of these vehicles is high, charging during the evening peak must be avoided since not enough generation capacity is available. Therefore, the charging must be shifted in time. From the perspective of the distribution grid, the management or coordination of charging plug-in hybrid electric vehicles allows for grid reinforcements to be postponed. On the other hand, the introduction of smart chargers or meters is inevitable for the coordination of the charging of plug-in hybrid electric vehicles." "Model-Based Analysis of Cardiac Medical Images: Iconic, Landmark-Based and Hybrid Modeling (Model-gebaseerde analyse van cardiale medische beelden: Iconische, landmark-gebaseerde en hybride modellering)" "An Elen" "Cardiac imaging is of great importance for the diagnosis of cardiac dysfunctions. Dynamical three-dimensional (3D) imaging, acquired with either magnetic resonance (MR) imaging, computed tomography or 3D ultrasound, allows to visualize the different phases of the cardiac cycle. This enables the analysis of volume and shape changes of the left ventricle (LV; the chamber pumping oxygenated blood to the body) and the quantification of functional parameters such as myocardial wall thickening, wall strain, ejection fraction, etc. Such quantification relies on the accurate delineation or segmentation of the cardiac wall in multiple time frames. Hence, reliable (semi-) automated model-based image analysis methods are needed, that can cope with the inherent ambiguity (induced by the intrinsic limitations of the image acquisition process) and complexity (induced by variable shape and intensity appearance of anatomical objects) of medical image data. Such model-based approaches incorporate prior knowledge about the typical appearance of the objects of interest in the image data, including both photometric properties as well as geometric properties.Current state-of-the-art approaches for shape modeling in image analysis can be broadly classified as, on the one hand, either iconic or picture-based, using an implicit representation of geometry by representing a shape as a picture, i.e. a gray value image or label image, or, on the other hand, landmark-based, using an explicit representation of geometry, parameterized as points, curves or surfaces with explicitly specified space coordinates. We investigated the possibilities and limitations of both representations for cardiac image analysis. Iconic methods represent shape variability by a deformation field, that transforms one model image to another image, obtained by suitably constrained non-rigid registration. Such registration based approaches are especially useful for the modeling of intra-subject deformations and for propagating information through image sequences, but cannot easily handle image ambiguities and low contrast regions due to the lack of an explicit shape model of the object of interest. Landmark-based representations model shape variability by statistical analysis of a representative training set of shape instances on which corresponding landmarks have been annotated. These models are very suitable for capturing inter-subject shape variability in (manually annotated) 2D images, but their application for the segmentation of entire 3D image stacks or 4D image sequences is cumbersome due to the need for a sufficiently large training set of pre-segmented images.To combine the advantages of iconic and landmark-based modeling, we developed a hybrid model that finds the optimal egmentation of an entire image sequence at once, based on statistical models for only a limited number of key image frames and linking all image frames through non-rigid registration. Our hybrid model combines an explicit geometric model of the inter-subject shape variability at the key time frames with an implicit geometric model that constrains the intra-subject frame-to-frame temporal deformations. Our method thus integrates model-based image segmentation and registration in a single unified algorithm, making optimal use of all available information simultaneously.Extending the hybrid model from 2D+time to 3D+time image sequences is trivial for imaging modalities with dense and isotropic sampling, but for 3D MR images the multi-slice 2D character of the image stacks constituted two new challenges. A 3D+time cardiac MR image is typically composed of a stack of parallel short axis (SA) and a few long axis (LA) 2D+time image slices. Each slice is acquired during a different breath hold of the patient, causing possible misalignment of the slices. Hence, we developed a method that automatically corrects the relative positioning of the SA and LA image slices, through maximization of the intensity similarity of the intersection lines. The second challenge was the sparseness of the data and the different positioning and orientation of the slices, which was taken into account for the 3D hybrid model by making a distinction between on the one hand the control points of the model, that define the fitted shape, and, on the other hand, the landmark points within the image slices, that define the local and global appearance models.The presented hybrid method combines the advantages of both iconic and landmark-based modeling approaches and makes maximal use of the available image information. The method was shown to be able to accurately segment entire MR image sequences. The incorporation of registration in the segmentation process was shown to improve the segmentation of individual frames, as all frames now contribute to the segmentation of the entire sequence. The resulting 3D segmentation and registration of the entire image sequence allow the quantification of the cardiac functionality, using parameters such as ejection fraction, local normal strain pattern, etc." "Prediction of Railway Induced Vibration by Means of Numerical, Empirical and Hybrid Methods (Voorspelling van trillingen ten gevolge van treinverkeer door middel van numerieke, empirische en hybride methodes)" "Hans Verbraken" "Ground vibration induced by railway traffic is a problem with a large environmental impact. Vibration generated at the wheel/rail contact is transferred through the soil and excites the foundation of nearby buildings where it causes disturbance of sensitive equipment, hindrance to inhabitants, or structural damage. An accurate prediction of expected vibration levels is required when designing new tracks or when changes are made to existing tracks. The study of possible vibration mitigation measures also requires accurate models.This work addresses the numerical, empirical, and hybrid prediction of railway induced vibration. For the assessment of these methods, an elaborate measurement campaign has been carried out at a site in Lincent, Belgium. First, a numerical model is presented that allows for a detailed representation of the track geometry. The influence of commonly made simplifying assumptions regarding the track and soil geometry is investigated for the site in Lincent. The dynamic track and soil characteristics are identified based on preliminary tests at the site. The predictions are compared to measured results of the transfer functions and during train pass-bys and show a reasonable agreement. Second, empirical prediction methods are discussed with a focus on the procedure presented by the U.S. Federal Railroad Administration (FRA), where the source and the propagation path are characterized experimentally. The experimental determination of these terms is critically assessed. Furthermore, the limitations of the FRA procedure are investigated by means of numerical simulations.Third, a hybrid model is presented according to the empirical FRA procedure by replacing the experimental result of either the source term or the propagation path term by a numerical prediction. The hybrid model is applied at the site in Lincent and compared to the experimental and numerical results." "Quality Control of PET/MRI systems: Consensus Recommendations from a European Network of Hybrid Imaging Sites (HYBRID)" "A Valladares, S Ahangari, T Beyer, R Boellaard, Z Chalampalakis, C Comtat, L DalToso, AE Hansen, M Koole, J Mackewn, P Marsden, Johan Nuyts, S Poth, E Solari, I Rausch"