Simulating currency substitution bias

The sign and size of estimates of the elasticity of currency substitution critically depend on the definition of the oppurtunity costs of holding money. We investigate possible biases by means of Monte Carlo experiments, as sufficient real data are not available

Strength of grass covers on dikes

Wave overtopping, in which a wave washes over the crest of a dike and damages its inner slope, is one of the many mechanisms that is found to be responsible for dike failures. As these dikes are generally covered with grass, insight into the erosion resistance of these grass covers against wave overtopping is desired. To assess the performance of dikes against wave overtopping, various concepts exist, such as the widely used cumulative overload method. However, these concepts lack a thorough understanding of the physical mechanisms at play during grass cover failure as a result of wave overtopping. Furthermore, the methods are generally not time-efficient and are labor intensive, leading to high costs. Therefore, a time-efficient and predictive method is desired that is based on the physical mechanisms of grass cover failure.The grass pull device, which is used extensively in this thesis, may serve as an alternative for the existing assessment methods. The device, which is reminiscent of a tensile test used in mechanical sciences, is able to exert various load mechanisms on the grass cover. In this thesis, the grass pull device is used to study various aspects of grass cover failure. Special attention is given to the influence of cyclic loading on the grass cover. Additionally, material properties have been derived that may serve as input for numerical grass erosion models. Furthermore, the influence of grass roots, subsoil type and pore saturation on the failure mode of grass covers was investigated. The results of this study showed a continuous growth of deformation and a decrease in stiffness when the grass cover is loaded cyclically. The behavior of grass during cyclic loading was found to be comparable to other composite materials, such as fiber-reinforced plastics. The material properties Young's and shear modulus were derived. The Young's moduli were found to be slightly overestimated, while the shear moduli were found to be comparable to what may be expected from literature. Differences in grass cover properties on different subsoils were identified, showing that grass covers on clay are generally better at resisting deformation, while having a brittle failure mode. For grass covers on sand, a large spread was observed and the material was found to deform easily, while still providing resistance at large deformations. Based on the findings of this study, recommendations were made to improve the grass pull device. It was found that the grass pull device was successful in providing insight into various physical processes. Whether the grass pull device will be able to capture all relevant erosion mechanisms remains questionable, but it has proven to be a successful addition to existing assessment methods.Civil Engineering | Hydraulic Engineering | Coastal Engineerin

The Effect of Neurodegeneration on Visuomotor Behavior in Alzheimer's Disease and Parkinson's Disease

The early stages of neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD) involve deterioration of specific (visuo)motor functions. The aim of the current study was to investigate differences in visuomotor behavior between age-matched groups of 17 patients with AD, 17 patients with PD, and 20 healthy control subjects across three eye-hand-coordination tasks of different cognitive complexity. In two of three tasks, timing and execution parameters of eyes and hand significantly differed between groups. Timing and execution parameters of the eyes and hands could potentially give a quantitative description of disease specific deficits in the spatial and temporal domains and may serve as a tool to monitor disease progression in AD and PD populations

Behavioral Inhibition Errors in Parkinson's Disease Tested Using an Antisaccade and Antitapping Task

Background: The antisaccade (AS) paradigm is frequently used to assess errors in reflexive behavioral responses in Parkinson's disease (PD) patients. Although PD pathology of frontal-striatal circuits suggests increased errors, reports on sensitivity and specificity of the AS task are lacking. We increased the level of cognitive complexity by adding to the AS task an antitapping instruction, i.e. an antisaccade and antitapping (ASAT) task. Objective: In this study, we compared saccadic error rates between PD patients and age-matched controls in 1) an AS task, using only eye movements and 2) an ASAT task, using eye and hand movements. Methods: 30 PD patients en 30 healthy age-matched controls performed an AS task and an ASAT task. The measurement setup consisted of a touch screen, an eye tracking system and a motion capture system. Error rates and eye - and hand latencies were compared between groups. Results: PD patients show higher error rates in the ASAT task, but not in the AS task compared to controls. In correctly performed ASAT task trials, PD patients are on average 60 milliseconds faster to initiate an eye movement. Subject classification based on error rates and eye latencies in the ASAT task results in a sensitivity of 0.77 and a specificity of 0.63. Conclusions: The results suggest that saccadic error rates and eye latencies in the cognitively more demanding ASAT task are sensitive measures to differentiate PD patients from controls. This task is a potentially useful addition to current methods to investigate visuomotor deficits in PD

De Routekaart naar een Meer Integrale Benadering van Wonen, Zorg en Pensioen

Het thema wonen, zorg en pensioen staat hoog op de agenda van de SER en verschillende ministeries. Het is ook onderwerp binnen de brede maatschappelijke pensioendialoog. In de Hoofdlijnennota over de toekomstige inrichting van het pensioenstelsel in Nederland van 6 juli 2015 benoemt het kabinet ‘een op maat gesneden pensioen’ als een van de zeven waarden waaraan een toekomstbestendig pensioenstelsel moet voldoen. Het kabinet is daarbij voorstander van een combinatie van meer maatwerk en keuzemogelijkheden. Op die manier sluiten pensioenregelingen beter aan op de kenmerken en voorkeuren van deelnemers. Het kabinet onderzoekt ook of een betere koppeling met wonen en zorg wenselijk is.De afgelopen jaren is vooral op macroniveau al op meerdere plekken onderzoek gedaan naar de combinatie van wonen, zorg en pensioen. Gelet op de actualiteit van het thema geeft Netspar het onderwerp hoge prioriteit op de onderzoeksagenda. Met dit rapport wil Netspar de discussie verder brengen door de financiële planning van het individuele huishouden als uitgangspunt te nemen.<br/

Effectiveness of reference signal-based methods for removal of EEG artifacts due to subtle movements during fMRI scanning

Objective: Subtle motion of an epileptic patient examined with co-registered EEG and functional MRI (EEG-fMRI) may often lead to spurious fMRI activation patterns when true epileptic spikes are contaminated with motion artefacts. In recent years, methods relying on reference signals for correcting these subtle movements in the EEG have emerged. In this study, the performance of two reference-based devices are compared to the template-based method with regard to their ability to remove movement-related artifacts in EEG measured during scanning. Methods: Measurements were performed with a novel double layer cap consisting of 29 EEG and 29 reference electrodes, and with a current loop cap consisting of 60 electrodes and three current loop wires attached to the cap. EEG was acquired inside the scanner during resting state, as well as when the subject was performing a cued movement task. For the double layer cap recordings, newly developed artifact removal algorithms are introduced and both reference signal-based methods are compared to a template-based correction method. Results: The BCG artifacts occurring at resting state could be removed successfully by both the reference signal-based methods as well as by the template-based method. However, the reference signal-based methods were also capable of removing EEG artifacts induced by subtle movements, whereas the template-based method failed to remove these artifacts. Conclusion: Reference signal-based methods enable to correct for artifacts due to subtle movements, which are not removed by commonly used template-based removal algorithms. Significance: Sensitivity of EEG-fMRI analysis in patients with focal epilepsy is improved by avoiding erroneous detections of subtle movements as epileptic spikes in the EEG

Termination of CD40L co-stimulation promotes human B cell differentiation into antibody-secreting cells

Human naïve B cells are notoriously difficult to differentiate into antibody-secreting cells (ASCs) in vitro while maintaining sufficient cell numbers to evaluate the differentiation process. B cells require T follicular helper (TFH) cell-derived signals like CD40L and IL-21 during germinal center (GC) responses to undergo differentiation into ASCs. Cognate interactions between B and TFH cells are transient; after TFH contact, B cells cycle between GC light and dark zones where TFH contact is present and absent, respectively. Here, we elucidated that the efficacy of naïve B cells in ACS differentiation is dramatically enhanced by the release of CD40L stimulation. Multiparameter phospho-flow and transcription factor (TF)-flow cytometry revealed that termination of CD40L stimulation downmodulates NF-κB and STAT3 signaling. Furthermore, the termination of CD40 signaling downmodulates C-MYC, while promoting ASC TFs BLIMP1 and XBP-1s. Reduced levels of C-MYC in the differentiating B cells are later associated with crucial downmodulation of the B cell signature TF PAX5 specifically upon the termination of CD40 signaling, resulting in the differentiation of BLIMP1 high expressing cells into ASCs. The data presented here are the first steps to provide further insights how the transient nature of CD40 signaling is in fact needed for efficient human naïve B cell differentiation to ASCs