58 research outputs found

    Synthesis of mycobacterial phenolic glycolipids

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    Het proefschrift omschrijft de chemische synthese van fenolische glycolipiden van verschillende mycobacteriën met het doel om deze te kunnen gebruiken voor immunologisch onderzoek.NWOBio-organic Synthesi

    Extension of the complete flux scheme to systems of conservation laws

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    We present the extension of the complete ¿ux scheme to advection-diffusion-reaction systems. For stationary problems, the ¿ux approximation is derived from a local system boundary value problem for the entire system, including the source term vector. Therefore, the numerical ¿ux vector consists of a homogeneous and an inhomogeneous component, corresponding to the advection-diffusion operator and the source term, respectively. For time-dependent systems, the numerical ¿ux is determined from a quasi-stationary boundary value problem containing the time-derivative in the source term. Consequently, the complete ¿ux scheme results in an implicit semidiscretisation. The complete ¿ux scheme is validated for several test problems. Keywords: Advection-diffusion-reaction systems, ¿ux (vector), ¿nite volume method, integral representation of the ¿ux, Green’s matrix, numerical ¿ux, matrix functions, Péclet matrix

    Harmonic complete flux schemes for conservation laws with discontinuous coefficients

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    In this paper we discuss several complete flux schemes for advection-diffusion-reaction problems. We consider both scalar equations as well as systems of equations. For the flux approximations in the latter case, we take into account the coupling between the constituent equations. We study conservation laws with discontinuous diffusion matrix/coefficient and show that the (matrix) harmonic average should be employed in the expressions for the numerical fluxes. The vectorial harmonic complete flux schemes are validated for a test problem

    The Complete Flux Scheme : error analysis and application to plasma simulation

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    The Complete Flux scheme (CFS) (J.H.M. ten Thije Boonkkamp et al., J. Sci. Comput. 46 (2011) 47–70) is an extension of the widely used exponential di¿erence scheme for advection-di¿usion-reaction equations. In the present paper we provide a rigorous proof that the convergence order of this scheme is 2 for all grid Péclet numbers, whereas that of the exponential scheme reduces to 1 for high grid Péclet numbers in the presence of source terms. The performance of both schemes is compared in two case studies: a model system and a real-world model of a parallel-plate glow discharge. The results indicate that the usage of CFS allows a considerable reduction of the number of grid points that is required to obtain the same accuracy. The MATLAB/Octave source code that has been used in these studies has been made available

    Why does it run in families? Explaining family similarity in help-seeking behaviour by shared circumstances, socialisation and selection

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    Why do contact frequencies with general practice of family members resemble each other? Many aspects related to the clustering of health-care utilisation within families have been studied, but the underlying mechanisms have not been addressed. This article considers whether family similarity in contact frequency with general practice can be explained as (a) a result of shared circumstances, (b) through socialisation, and (c) through homogeneity of background characteristics. Data from the second Dutch national survey of general practice were used to test these mechanisms empirically. This survey recorded all consultations in 2001 for 104 general practices in the Netherlands, serving 385 461 patients. Information about socio-demographic characteristics was collected by means of a patient survey. In a random sample, an extended health interview took place (n ¼ 12 699). Overall, we were able to show that having determinants in common through socialisation and shared circumstances can explain similarity in contact frequencies within families, but not all hypotheses could be confirmed. In specific terms, this study shows that resemblances in contact frequencies within families can be best explained by spending more time together (socialisation) and parents and children consulting a general practitioner simultaneously (circumstances of the moment). For general practitioners, the mechanisms identified can serve as a framework for a family case history. The importance of the mechanism of socialisation in explaining similarities in help-seeking behaviour between family members points to the significance of knowledge and health beliefs underlying consultation behaviour. An integrated framework including these aspects can help to better explain health behaviour

    All in the Family:Headaches and Abdominal Pain as Indicators for Consultation Patterns in Families

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    PURPOSE Headaches and abdominal pain are examples of minor ailments that are generally self-limiting. We examined the extent to which patterns of visits to family physicians for minor ailments, such as headaches or abdominal pain, cluster within families. METHODS Using information from the Second Dutch National Survey of General Practice for 96 family practices, we analyzed the visits of families with at least 1 child aged 12 years or younger during a period of 12 months. RESULTS Family patterns were clearest in the visits of mothers and children. A large part of the similarity in the frequencies of contact by mothers and daughters could be attributed to shared family factors. This fi nding was especially true for families with a child who had a headache or abdominal pain as the presenting symptom, rather than physical trauma or chronic disease. Within families, we did not fi nd any specific patterns of diagnoses. Diagnoses were recorded by family physicians. In the case of young children, family similarity may have been overestimated because parents initiated the visits and put their child’s health problem into words. CONCLUSIONS Visits to family physicians for headaches or abdominal pain can be seen as indicators of consultation patterns in families. Family patterns related to minor ailments are likely to be a result of socialization. Family consultation patterns might point toward specifi c needs of families and consequently at a different approach to treatment

    Kijk eens wat vaker onder de graszode

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    Kan de bodem negatieve gevolgen van klimaatverandering opvangen? Wat is de invloed van duurzaam bodembeheer op de vochthuishouding in de bodem? Hoe kan het functioneren van de bodem worden geoptimaliseerd om te anticiperen op droge of natte periodes? Deze vragen van provincie Utrecht en Waterschap Vallei & Veluwe waren aanleiding voor het SKB-project 'Kijk eens wat vaker onder de graszode'

    CT-based deep multi-label learning prediction model for outcome in patients with oropharyngeal squamous cell carcinoma

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    Background: Personalized treatment is increasingly required for oropharyngeal squamous cell carcinoma (OPSCC) patients due to emerging new cancer subtypes and treatment options. Outcome prediction model can help identify low or high-risk patients who may be suitable to receive de-escalation or intensified treatment approaches.Purpose: To develop a deep learning (DL)-based model for predicting multiple and associated efficacy endpoints in OPSCC patients based on computed tomography (CT).Methods: Two patient cohorts were used in this study: a development cohort consisting of 524 OPSCC patients (70% for training and 30% for independent testing) and an external test cohort of 396 patients. Pre-treatment CT-scans with the gross primary tumor volume contours (GTVt) and clinical parameters were available to predict endpoints, including 2-year local control (LC), regional control (RC), locoregional control (LRC), distant metastasis-free survival (DMFS), disease-specific survival (DSS), overall survival (OS), and disease-free survival (DFS). We proposed DL outcome prediction models with the multi-label learning (MLL) strategy that integrates the associations of different endpoints based on clinical factors and CT-scans.Results: The multi-label learning models outperformed the models that were developed based on a single endpoint for all endpoints especially with high AUCs ≥ 0.80 for 2-year RC, DMFS, DSS, OS, and DFS in the internal independent test set and for all endpoints except 2-year LRC in the external test set. Furthermore, with the models developed, patients could be stratified into high and low-risk groups that were significantly different for all endpoints in the internal test set and for all endpoints except DMFS in the external test set. Conclusion: MLL models demonstrated better discriminative ability for all 2-year efficacy endpoints than single outcome models in the internal test and for all endpoints except LRC in the external set.</p
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