415 research outputs found
Long-term effects of insulin initiation in people with Type 2 Diabetes: observational and intervention studies on disease management and patient involvement
No full textNijpels, M.G.A.A.M. [Promotor]Jansen, D. [Copromotor]Rutters, F. [Copromotor]Hugtenburg, J.G. [Copromotor
Posture normalisation of 3D body scans
No full textFor product developers that design near-body products, virtual mannequins that represent realistic body shapes, are valuable tools. With statistical shape modelling, the variability of such body shapes can be described. Shape variation captured by statistical shape models (SSMs) is often polluted by posture variations, leading to less compact models. In this paper, we propose a framework that has low computational complexity to build a posture invariant SSM, by capturing and correcting the posture of an instance. The posture-normalised SSM is shown to be substantially more compact than the non-posture-normalised SSM. Practitioner summary: Statistical shape modelling is a technique to map out the variability of (body) shapes. This variability is often polluted by variations in posture. In this paper, we propose a framework to build a posture invariant statistical shape model. Abbreviations: SSM: statistical shape model; 1D: one-dimensional; 3D: three-dimensional; DHM: digital human model; LBS: linear blend skinning; PCA: princial component analysis; PC: principal component; TTR: thumb tip reach.Accepted author manuscriptApplied Ergonomics and Desig
Predicting User’s Measurements without Manual Measuring: A Case on Sports Garment Applications
No full textAs sports garments are stretchable, different sizing tables are used than for retail clothing. However, customers measuring themselves leads to errors and unsatisfaction, since these customized branded garments cannot be returned. Using fitting sets avoids this, but this is not always feasible, especially in an online retail environment. Therefore, this research aims to use descriptive measures—parameters that do not require manual measuring because they are readily known by heart by almost any customer—to predict users’ body measurements, which can, thus, be used by customers to determine the size of their sports garment from a sizing chart. To validate if these input measures are sufficient to predict the correct size, three prediction methods are used and compared with baseline manual measurements. The methods are: (i) clothing size predictions from shape models with descriptive measures as inputs, (ii) clothing size predictions from a regression analysis, and (iii) clothing size predictions from a shape model based on extensive 3D scanned measurements as input. The conclusion is that a regression algorithm with, as input variables, the straightforward demographics of age, gender, stature, and weight is more accurate than the algorithm with the same inputs but with a shape model behind it. Moreover, chest and hip circumferences have an intraclass correlation coefficient rating above 0.9 and are, thus, suited for online retail of stretchable garments, such as cycling clothes. As validated by end-users, the regression predictions are shown to agree with preferred garment sizes of the participants, within the natural variation of personal preferences
Analytical modelling of the three-dimensional stress field induced by fluid production and injection in reservoirs with displaced faults
No full textInjection and production of fluids into/from the subsurface has been known to trigger earthquakes, referred to as induced seismicity. This seismicity may occur when anthropogenically caused changes in the in-situ stress conditions result in reactivation of pre-existing faults in the subsurface causing slip accompanied by sudden release of energy. Several studies have numerically modelled the induced stresses due to production/injection in reservoirs of various geometries. In this report we present a simplified three-dimensional reservoir with a displaced fault and derive analytical expressions for induced stresses in and outside the reservoir due to production and injection of fluids. We use the calculated stresses for the three-dimensional model and analyse onset of slip across the fault. The research builds upon the analytical two-dimensional plane-strain analysis for induced stresses and slip initiation in \citet{Jansen2019} to which our work contributed. We reaffirm the findings from the plane-strain analysis in \citet{Jansen2019} and conclude that the effects of incorporating third dimension on induced stresses and slip behaviour are limited. We find infinite peaks in resultant shear stresses at the reservoir boundaries and observe a distinctly different pattern in induced stresses and slip behaviour between production and injection scenarios. In case of production, the slip patches are predicted to grow inwards into the reservoir initially until they merge, while for injection the slip patches grow separately into the overburden and underburden. The findings in this report are in agreement with the previous analytical and numerical studies on induced seismicity. In this research we also introduce geometrical complexity in the reservoir in the form of laterally varying height of the reservoir and we observe that the effects of variation in reservoir thickness are also minimal, however the induced stress patterns and slip initiation is significantly impacted by fault throw, initial stress conditions and fault frictional characteristics
Subject-specific identification of three dimensional foot shape deviations using statistical shape analysis
No full textAbstract: The high prevalence of foot pain, and its relation to foot shape, indicates the need for an expert system to identify foot shape abnormalities. Yet, to date, no such expert system exists that examines the full 3D foot shape and produces an intuitive explanation of why a foot is abnormal. In this work, we present the first such expert system that satisfies those goals. The system is based on the concept of model-based outlier detection: a statistical shape model (SSM) is generated from 186 3D optical foot scans of healthy feet. This model acts as a knowledge base which is then parameterized by one's demographic characteristics (e.g., age, weight, height, shoe size) through a multivariate regression. This regression introduces model flexibility as it allows the model to be fine tuned to a specific individual. This fine tuned model is then used as a baseline to which the individual's 3D foot scan can be compared using standard statistical tests (e.g. t-tests). These statistical tests are performed at each vertex along the foot surface to identify the degree and location of shape outliers. Our expert system was validated on foot scans from patients with hallux valgus and abnormal foot arches. As expected, our results varied per patient, confirming that feet with the same clinical classification still show high shape variability. Additionally, the foot shape abnormalities identified by our system not only agreed with the expected location and severity of the tested foot deformities, but our analysis of the full 3D foot shape was able to completely characterize the extent of those abnormalities for the first time. These results show that the combination of statistical shape modelling, multivariate regression, and statistical testing is powerful enough to perform outlier detection for 3D foot shapes. The resulting insights provided by this system could prove useful in both shoe design and clinical diagnosis. (C) 2020 Elsevier Ltd. All rights reserved
Exploring the Immunomodulatory Potential of Pectins and Polysaccharides as Feed Additives for Poultry: In Vitro Insights and Gut Model Development
No full textAntimicrobial resistance in poultry has become a global public health threat, hence the need for alternatives in poultry production is warranted. Carbohydrate compounds have shown promising effects in promoting gut health in poultry as they escape enzymatic digestion in the upper gastrointestinal tract (GIT) and reach the colon to promote growth of beneficial gut microbiota and produce short chain fatty acids (SCFA). In addition to altering the gut microbiota composition, carbohydrate compounds can directly interact with immune cells such as NK cells, a major intraepithelial lymphocyte (IEL) population, and macrophages that are present in the lamina propria and modulate the immune response. This way carbohydrate compounds can promote gut health and thereby reduce the required use of antimicrobials in poultry production. In this thesis we have determined the direct interaction of several pectins and polysaccharides, that may be used as feed additives in poultry production, with chicken macrophages and NK cells and describe their immunomodulatory properties. In addition, an in vitro chicken gut model “chicken intestinal organoids” was also developed. This in vitro model can be used for large screening of several drugs, carbohydrate compounds, and for disease modeling
Study on The Effect of Production Dynamic to Fault Reactivation: A Case Study of Groningen Gas Field
No full textThe subsurface of Groningen gas field composed of several faults. The continuous production has been resulting in several micro-seismicity activities, particularly for the past decades. One of the reasons for the production-induced-seismicity is fault reactivation at depth. The fault that initially in the non-active state becomes active and starts slipping due to pore fluid extraction. The modelling of fault reactivation induced by production can be simulated by coupling of flow and geomechanics.The project studies the coupling of flow and geomechanics for an idealistic subsurface model with fault. The flow occurs due to pore pressure depletion and is predicted by solving mass conservation. The corresponding deformation is estimated by momentum balance equation.The observation will be limited to rock deformation that is quantified by effective stress and displacement on the fault due to a pressure change in the subsurface. The simulation is performed using Stanford's Automatic Differentiation General Purpose Reservoir Simulator (ADGPRS).In the proposed model, the flow equation is discretised using finite volume method, and poromechanics is discretised by finite-element Galerkin's approach. Both problems share the same grid model, and there is no error associated with the information exchange. The coupled problem is being solved fully implicitly where flow and mechanics formulation are solved simultaneously.The case study for the simulation is a simplified Groningen subsurface model with a fault zone. The impact of variability in production dynamic on fault reactivation is studied. The variations in production rate and production strategy are applied in different formation configurations. It is found that the correlation between the production rates and the stress state in the subsurface depends on the formation offset. However, the stress field does not depend on continuity of the production scheme. Several aspects including the presence of Gas-Water contact in the model was studied in this project as well. <br/
Persoonlijk privaatrecht:Over de rol van personen en hun belangen in het privaatrecht
No full textHet privaatrecht richt zich op de rechtsverhoudingen tussen particulieren; zowel natuurlijke personen als rechtspersonen. Het omvat normen die specifieke individuele situaties en behoeften beïnvloeden. Hiermee is het privaatrecht persoonlijk van aard – het woord ‘privaat’ heeft dat ook in zich. Maar hoe ‘persoonlijk’ is het privaatrecht nu echt? Houdt het privaatrecht voldoende rekening met de (rechts)personen voor wie het is bedoeld? Moet het op bepaalde punten wellicht ‘persoonlijker’ worden? Of zijn de personen die het privaatrecht beoogt te beschermen (soms) juist gebaat bij een ‘onpersoonlijkere’ benadering? Deze vragen staan centraal in Persoonlijk privaatrecht
Persoonlijk privaatrecht:Over de rol van personen en hun belangen in het privaatrecht
No full textHet privaatrecht richt zich op de rechtsverhoudingen tussen particulieren; zowel natuurlijke personen als rechtspersonen. Het omvat normen die specifieke individuele situaties en behoeften beïnvloeden. Hiermee is het privaatrecht persoonlijk van aard – het woord ‘privaat’ heeft dat ook in zich. Maar hoe ‘persoonlijk’ is het privaatrecht nu echt? Houdt het privaatrecht voldoende rekening met de (rechts)personen voor wie het is bedoeld? Moet het op bepaalde punten wellicht ‘persoonlijker’ worden? Of zijn de personen die het privaatrecht beoogt te beschermen (soms) juist gebaat bij een ‘onpersoonlijkere’ benadering? Deze vragen staan centraal in Persoonlijk privaatrecht
Tuning tolerance: Modulating adaptive immune responses for therapeutic purposes
No full textRheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in the joints, leading to pain, stiffness and cartilage damage. Immune regulatory failure or imbalance in anti- and pro-inflammatory responses could lead towards autoimmune diseases. However, the initial trigger that causes this faulty immune regulation is often unknown which is also the case in RA. Therefore, it is not possible yet to treat the initiation of disease in an antigen specific way, which means that current medication is directed towards relief of symptoms. To cure disease, restoring immune tolerance is required. For this reason, therapies that restore the immune balance are being explored. In this thesis we investigated two possible approaches: tolerogenic dendritic cells and nanoparticles containing TNF siRNA. Tolerogenic dendritic cells Dendritic cells (DCs) are important players in the immune system for their ability to activate and dampen the immune system. DCs can be modulated in the laboratory into tolerogenic dendritic cells (tolDCs), these tolDCs could restore immune tolerance. In this thesis, we have shown that tolDCs, induced by dexamethasone and 1,25-dihydroxyvitamin D3, do not induce new regulatory T cells but dampen the activation and proliferation of CD4+ T cells. This results in overall more Tregs and an immune-regulatory state. Since the autoantigen in RA is unknown, we sought possible alternative autoantigens. We investigated HSPs as possible surrogate autoantigens. Since roughly eighty percent of both healthy donors and inflammatory arthritis patients showed a CD4+ T cellresponse towards HSPs, we reasoned that HSPs could be used to modulate CD4+ T cell responses in humans. Furthermore, tolDCs pulsed with HSP or control peptides induced a Tr1 phenotype in the CD4+ T cells. Nanoparticles TNF is a pro-inflammatory cytokine that plays an important role in the pathogenesis of RA. RNA interference therapy could be a solution to inhibit excessive TNF production and dampen inflammation in RA. However, to get TNF siRNA across the cell membrane a drug delivery system such as nanoparticles are needed. Especially in autoimmunity, the delivery system itself should not induce any additional (pro-inflammatory) immune responses. Two nanoparticle types were designed to deliver TNF siRNA without extra immune activation. After showing that TNF siRNA is able to inhibit TNF production in a macrophage cell line, we tested the nanoparticles in an in vivo experimental arthritis model. Both the nanoparticle types containing TNF siRNA restrained arthritic symptoms after local administration, indicating that TNF was silenced in vivo. Since the route of administration of these tolerogenic therapies can influence the outcome, we compared two non-traditional routes (intradermal and intranasal) of vaccination. We noticed differences in immune cell activation and cytokine production, which illustrates that the micromilieu and immune response differ greatly between the several administration routes. The results described in this thesis may bring us a step closer towards developing immune tolerance-inducing therapies for Rheumatoid arthritis and possibly also other auto immune diseases
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