Distinctive Alterations in Microvascular Function Due to Multiple Common Morbidities

In this thesis, we investigated the role of multiple common cardiovascular risk factors on the development of microvascular dysfunction and left ventricular diastolic dysfunctio

Characterisation of a collection of perennial Panicum species

A collection of 74 perennial Panicum accessions, belonging to 6 different species, maintained at the field genebank of the International Livestock Research Institute, was described using 49 agromorphological characters in a multivariate analysis. Fifty-four accessions, for which coordinates of the collection site were available, were further characterised using environmental data obtained through use of geographic information systems. Three drought-tolerant species, P. antidotale, P. turgidum and P. phragmitoides, were very different agro-morphologically from the other species. Of these drought-tolerant species, P. phragmitoides appeared to have the best agromorphological attributes for use as forage in dry areas. P. maximum, P. coloratum and P. infestum appeared more similar, and were not entirely separated using cluster analysis. The accessions of these 3 species could be divided into 5 different clusters with similar characteristics. The majority of the P. maximum accessions belonged to 2 clusters, mainly differing in the size and robustness of the plants. A strong correlation was found between characters describing the robustness of the P. maximum plant and the annual precipitation at the collection site. Promising P. maximum accessions for use in cut-and-carry systems were identified

Dual Arm Impact-Aware Grasping through Time-Invariant Reference Spreading Control

With the goal of increasing the speed and efficiency in robotic dual arm manipulation, a novel control approach is presented that utilizes intentional simultaneous impacts to rapidly grasp objects. This approach uses the time-invariant reference spreading framework, in which partly-overlapping ante- and post-impact reference vector fields are used. These vector fields are coupled via the impact dynamics in proximity of the expected impact area, minimizing the otherwise large velocity errors after the impact and the corresponding large control efforts. A purely spatial task is introduced to strongly encourage the synchronization of impact times of the two arms. An interim-impact control phase provides robustness in the execution against the inevitable lack of exact impact simultaneity and the corresponding unreliable velocity error. In this interim phase, a position feedback signal is derived from the ante-impact velocity reference, which is used to enforce sustained contact in all contact points without using velocity error feedback. With an eye towards real-life implementation, the approach is formulated using a QP control framework, and is validated using numerical simulations on a realistic robot model with flexible joints and low-level torque control

Dual Arm Impact-Aware Grasping through Time-Invariant Reference Spreading Control

With the goal of increasing the speed and efficiency in robotic dual arm manipulation, a novel control approach is presented that utilizes intentional simultaneous impacts to rapidly grasp objects. This approach uses the time-invariant reference spreading framework, in which partly-overlapping ante- and post-impact reference vector fields are used. These vector fields are coupled via the impact dynamics in proximity of the expected impact area, minimizing the otherwise large velocity errors after the impact and the corresponding large control efforts. A purely spatial task is introduced to strongly encourage the synchronization of impact times of the two arms. An interim-impact control phase provides robustness in the execution against the inevitable lack of exact impact simultaneity and the corresponding unreliable velocity error. In this interim phase, a position feedback signal is derived from the ante-impact velocity reference, which is used to enforce sustained contact in all contact points without using velocity error feedback. With an eye towards real-life implementation, the approach is formulated using a QP control framework, and is validated using numerical simulations on a realistic robot model with flexible joints and low-level torque control.Comment: 8 pages, 4 figures, accepted for publication to IFAC World Congress 202

Collision-free coordination of a group of unicycle mobile robots

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Quadratic Programming-based Reference Spreading Control for Dual-Arm Robotic Manipulation with Planned Simultaneous Impacts

With the aim of further enabling the exploitation of intentional impacts in robotic manipulation, a control framework is presented that directly tackles the challenges posed by tracking control of robotic manipulators that are tasked to perform nominally simultaneous impacts. This framework is an extension of the reference spreading control framework, in which overlapping ante- and post-impact references that are consistent with impact dynamics are defined. In this work, such a reference is constructed starting from a teleoperation-based approach. By using the corresponding ante- and post-impact control modes in the scope of a quadratic programming control approach, peaking of the velocity error and control inputs due to impacts is avoided while maintaining high tracking performance. With the inclusion of a novel interim mode, we aim to also avoid input peaks and steps when uncertainty in the environment causes a series of unplanned single impacts to occur rather than the planned simultaneous impact. This work in particular presents for the first time an experimental evaluation of reference spreading control on a robotic setup, showcasing its robustness against uncertainty in the environment compared to two baseline control approaches

Guideline versus non-guideline based management of rectal cancer in octogenarians

The number of octogenarians with rectal adenocarcinoma is growing. Current guidelines seem difficult to apply on octogenarians which may result in non-adherence. The aim of this retrospective cohort study is to give insight in occurrence of treatment-related complications, hospitalisations and survival among octogenarians treated according to guidelines versus octogenarians treated otherwise. 108 octogenarians with rectal adenocarcinoma were identified by screening of medical records. 22 patients were excluded for treatment process analysis because of stage IV disease or unknown stage. Baseline characteristics, diagnostic process, received treatment, motivation for deviation from guidelines, complications, hospitalisations and date of death were documented. Patients were divided in two groups depending on adherence to treatment guidelines. Differences in baseline characteristics, treatment-related complications and survival between both groups were evaluated. Diagnosis and treatment according to guidelines occurred in 95 and 54% of the patients, respectively. When documented, patient's preference and comorbidities were major reasons to deviate from guidelines. 66% of patients who were treated according to guidelines experienced complications versus 34% of those treated otherwise (p = 0.02). After adjustment for differences in age and polypharmacy, this association was not significant. Patients treated according to the guideline had better survival 18 months after diagnosis (80 versus 56%, p = 0.02). Treating octogenarians with rectal cancer according to guidelines seem to lead to better overall survival, but may lead to a high risk of complications. This may jeopardise quality of life. More and prospective studies in octogenarians with rectal cancer are needed to customize guidelines for these patients

Water vasthouden aan de bron: inzicht door modelberekeningen

De meest effectieve strategie voor de reductie van piekafvoeren, water vasthouden, is bergen van water bij de bron, waarbij de afstroming van water op perceelsniveau wordt bemoeilijkt. Om een onderbouwd inzicht in effect en relevantie van water vasthouden te krijgen zijn, in samenspraak met betrokken instanties, vijf maatregelen met behulp van de computercode SIMGRO geëvalueerd in de stroomgebieden Peelsche Loop, Groote Wetering en Raamsloop. Piekafvoeren kunnen met 3 tot 45% worden gereduceerd. De meest effectieve manier om water vast te houden is het voorkómen van maaiveldafvoer waarbij water tijdelijk op het maaiveld wordt geborgen, met als neveneffect structurele grondwaterstandverhogingen en effecten op de landbouw. Minder effectieve maatregelen hebben een marginaal effect op de regionale hydrologie. Inundaties verdwijnen sneller met goede drainage