282 results on '"Willems J"'
Search Results
2. Uitdijende verwachtingen en verantwoordelijkheden van bestuurders.
- Author
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Roessingh, D. C., Willems, J. V., Ploeger, P. N., de Bos R. A., A., and Verdam, A. F.
- Published
- 2024
3. The diagnostic accuracy of local staging in colon cancer based on computed tomography (CT): evaluating the role of extramural venous invasion and tumour deposits.
- Author
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van den Berg, K., Wang, S., Willems, J. M. W. E., Creemers, G. J., Roodhart, J. M. L., Shkurti, J., Burger, J. W. A., Rutten, H. J. T., Beets-Tan, R. G. H., and Nederend, J.
- Subjects
COLON cancer ,PATIENT selection ,COMPUTED tomography ,TUMOR classification ,NEOADJUVANT chemotherapy ,COLORECTAL cancer - Abstract
Purpose: The shift from adjuvant to neoadjuvant treatment in colon cancer demands the radiological selection of patients for systemic therapy. The aim of this study was to evaluate the accuracy of the CT-based TNM stage and high-risk features, including extramural venous invasion (EMVI) and tumour deposits, in the identification of patients with histopathological advanced disease, currently considered for neoadjuvant treatment (T3-4 disease). Methods: All consecutive patients surgically treated for non-metastatic colon cancer between January 2018 and January 2020 in a referral centre for colorectal cancer were identified retrospectively. All tumours were staged on CT according to the TNM classification system. Additionally, the presence of EMVI and tumour deposits on CT was evaluated. The histopathological TNM classification was used as reference standard. Results: A total of 176 patients were included. Histopathological T3-4 colon cancer was present in 85.0% of the patients with CT-detected T3-4 disease. Histopathological T3-4 colon cancer was present in 96.4% of the patients with CT-detected T3-4 colon cancer in the presence of both CT-detected EMVI and CT-detected tumour deposits. Histopathological T0-2 colon cancer was present in 50.8% of the patients with CT-detected T0-2 disease, and in 32.4% of the patients without CT-detected EMVI and tumour deposits. Conclusion: The diagnostic accuracy of CT-based staging was comparable with previous studies. The presence of high-risk features on CT increased the probability of histopathological T3-4 colon cancer. However, a substantial part of the patients without CT-detected EMVI and tumour deposits was diagnosed with histopathological T3-4 disease. Hence, more accurate selection criteria are required to correctly identify patients with locally advanced disease. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
- View/download PDF
4. First-year students' social adjustment process in professional higher education: key experiences and their occurrence over time.
- Author
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Willems, J., Coertjens, L., and Donche, V.
- Subjects
SOCIAL adjustment ,SOCIAL processes ,HIGHER education ,CRITICAL incident technique ,VOCATIONAL education - Abstract
The social adjustment process is a prominent factor in the literature on the transition to higher education (HE). This vast body of research, however, has predominantly focussed on academically oriented first-year higher education (FYHE) contexts, leaving professionally oriented programs (providing vocational education that prepares students for a particular occupation) rather underexamined. Therefore, this study set out to explore what first-year students in professional HE contexts perceive to be the most important social experiences associated with their adjustment process in the first semester of FYHE. Furthermore, this study examines the extent to which the uncovered key experiences associated with social adjustment are reported at different times. Hereto, drawing on the critical incidents technique, qualitative data were collected from 104 purposively selected freshmen, enrolled in a Flemish (Dutch-speaking part of Belgium) university college which offers professional HE programs, such as social work and nursing. At the start of the second semester of FYHE, these respondents completed 'reflective logs' wherein they reflected on three critical social experiences during their first semester in HE. Firstly, a qualitative content analysis revealed that students report on five overarching themes: (1) dealing with the unknown, (2) establishing a first connection, (3) establishing a deeper connection, (4) support from peers and others, and (5) loneliness. Secondly, a quantitative analysis of code occurrence suggests that these five uncovered themes seem to be more significant at different times in the first semester of FYHE. Implications of the findings for the development of guidance and coaching initiatives are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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5. Calibration of Large Photonis Fission Chambers in Standard Neutron Fields of the BR1 Reactor.
- Author
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Kochetkov, A., Krasa, A., Borms, L., Malambu, E., Vittiglio, G., Wagemans, J., and Willems, J.
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FISSION counters ,NEUTRON flux ,NEUTRONS ,CALIBRATION ,CORRECTION factors ,NUCLEAR reactors ,RESEARCH reactors - Abstract
Small fission chambers manufactured by Photonis, Reuter-Stokes, CEA, and Centronic are routinely calibrated in standard neutron fields of the BR1 reactor at SCK CEN in Mol, Belgium. Two irradiation fields are available: fast spectrum in the MARK3 convertor and thermal spectrum in the Empty Cavity. In this work, for the first time the calibration procedure of larger fission chambers (Photonis CFUL01 and CFUM21 type) with the deposit length exceeding the length of the convertor is presented. Spatial energy correction factors taking into account the neutron flux shape beyond the convertor and radial gradient of the neutron flux were calculated with MCNP and experimentally validated. The combination of calibration (i.e., effective mass measurement) in fast and thermal irradiation fields allows for determination of the purity of 238U deposit. This is demonstrated on three CFUL01-type fission chambers with purity between 99.8% and 99.998%. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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6. The outcome of pulmonary hypertension and its association with pulmonary artery dilatation.
- Author
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Duijnhouwer, A. L., Lemmers, J., Smit, J., van Haren-Willems, J., Knaapen-Hans, H., ten Cate, T., Hagmolen of ten Have, W., de Boer, M.-J., Roos-Hesselink, J., Vonk, M., and van Dijk, A.
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PULMONARY hypertension ,PULMONARY artery ,DIAGNOSIS ,CARDIAC catheterization ,ACQUISITION of data - Abstract
Background: Pulmonary artery (PA) dilatation is often seen in pulmonary hypertension (PH) and is considered a long-term consequence of elevated pressure. The PA dilates over time and therefore may reflect disease severity and duration. Survival is related to the stage of the disease at the time of diagnosis and therefore PA diameter might be used to predict prognosis. This study evaluates the outcome of patients with pulmonary arterial hypertension (PAH) and chronic thrombo-embolic pulmonary hypertension (CTEPH) and investigates whether PA diameter at the time of diagnosis is associated with mortality. Methods: Patients visiting an outpatient clinic of a tertiary centre between 2004 and 2018 with a cardiac catheterisation confirmed diagnosis of PAH or CTEPH and a CT scan available for PA diameter measurement were included. PA diameter and established predictors of survival were collected (New York Heart Association (NYHA) class, N‑terminal pro-brain natriuretic peptide (NT-proBNP) level and 6‑min walking distance (6MWD)). Results: In total 217 patients were included (69% female, 71% NYHA class ≥III). During a median follow-up of 50 (22–92) months, 54% of the patients died. Overall survival was 87% at 1 year, 70% at 3 years and 58% at 5 years. The mean PA diameter was 34.2 ± 6.2 mm and was not significantly different among all the diagnosis groups. We found a weak correlation between PA diameter and mean PA pressure (r = 0.23, p < 0.001). Male sex, higher age, shorter 6MWD and higher NT-proBNP level were independently associated with mortality, but PA diameter was not. Conclusion: The prognosis of PAH and CTEPH is still poor. Known predictors of survival were confirmed, but PA diameter at diagnosis was not associated with survival in PAH or CTEPH patients. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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7. Het studiekeuzeproces voor hoger onderwijs in kaart: validering van de Verkorte Vragenlijst Studiekeuzetaken (VVST).
- Author
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Demulder, L., Willems, J., Verschueren, K., Lacante, M., and Donche, V.
- Abstract
Copyright of Pedagogische Studien is the property of Vereniging Onderwijsresearch and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
8. Het studiekeuzeproces voor hoger onderwijs in kaart: validering van de Verkorte Vragenlijst Studiekeuzetaken (VVST).
- Author
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Demulder, L., Willems, J., Verschueren, K., Lacante, M., and Donche, V.
- Abstract
Copyright of Pedagogische Studien is the property of Vereniging Onderwijsresearch and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
9. Polygrafie/polysomnografie.
- Author
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van Haren-Willems, J. H. G. M.
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- 2016
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10. Are disseminated tumor cells in bone marrow and tumor-stroma ratio clinically applicable for patients undergoing surgical resection of primary colorectal cancer? The Leiden MRD study.
- Author
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Vogelaar, F., Pelt, G., Leeuwen, A., Willems, J., Tollenaar, R., Liefers, G., and Mesker, W.
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COLON cancer treatment ,BONE marrow cancer ,COLON cancer patients ,SURVIVAL analysis (Biometry) ,DATA analysis - Abstract
Purpose: Current TNM staging does not appropriately identify high-risk colorectal cancer (CRC) patients. The aim of this study was to evaluate whether the presence of disseminated tumor cells (DTCs) in the bone marrow (BM) and the presence of stroma in the primary tumor, i.e., the tumor-stroma ratio (TSR), in patients undergoing surgical resection of primary CRC provides information relevant for disease outcome. Methods: Patients with primary CRC ( n = 125), consecutively admitted for curative resection between 2001 and 2007, were included in the study. All patients underwent BM aspiration before surgery. Detection of tumor cells was performed using immunocytochemical staining for cytokeratin (CK-ICC). The TSR was determined on diagnostic H&E stained sections of primary tumors. Results: DTCs were detected in the BM of 23/125 patients (18 %). No association was found between BM status and overall survival (HR 0.97 (95 % CI 0.45-2.09), p = 0.93). Also, no significant difference was found in their 5-year survival rate (resp. 72 % and 68 % for BM-positive versus BM-negative patients). The TSR was found to be associated with a worse overall survival (HR 2.16, 95 % CI 1.02-4.57, p = 0.04) with 5-year survival rates of 84 % versus 62 % for stroma-low and stroma-high patients, respectively. No relation was found between the presence of DTCs and TSR. Conclusions: Our data indicate that the presence of DTCs in the BM of CRC patients is not associated with disease outcome. The TSR was, however, found to be associated with a worse overall survival, which indicates that for CRC the tumor microenvironment plays an important role in its behavior and prognosis. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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11. Prevalence and awareness of functional and structural foot abnormalities in children and adolescents with type 1 diabetes.
- Author
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Wever, A., Schickenberg-Werrij, B. G., Willems, J., Schaper, N. C., and Schott, D. A.
- Abstract
Background: The ISPAD guideline 2011/2014 advises annual podiatric screening to detect foot complications and identify other possible risk factors such as functional and structural foot abnormalities. The aim of this study was to assess the prevalence and awareness of neurovascular, functional and structural foot abnormalities in children and adolescents with type 1 diabetes mellitus (T1DM). Methods: All patients aged 0-18 years with T1DM were invited for a foot examination and structured questionnaire by a certified podiatrist. Results: Three of the examined patients (n = 128) showed signs of possible long-term complications. Structural and functional foot problems were observed in 71.9% (n = 92). Of all patients, 38.3% (n = 49) required further treatment by a podiatrist. Conclusions: Functional and structural foot abnormalities are a frequent problem in children with T1DM in the southern part of the Netherlands. These abnormalities are an additional risk factor for developing long-term foot complications. Education in and implementation of the guideline are necessary. [ABSTRACT FROM AUTHOR]
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- 2016
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12. Spectral Coarse Spaces in Robust Two-Level Schwarz Methods.
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Willems, J.
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- 2013
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13. Polysomnografie.
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Haren-Willems, J. van
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- 2011
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14. Polysomnografie.
- Author
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van Haren-Willems, J.
- Abstract
Copyright of Praktische Handleiding Longfunctietesten is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2010
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15. Runalyser: Real Time Analysis of Running Technique in Practice (P196).
- Author
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Wijnen, M., Hoppenbrouwers, M. B., and Willems, J. W. M.
- Abstract
Measurement systems are becoming more and more common in the training practice of athletes. In the lab, many parameters can be measured. On the track or on the road however, the technology is currently limited to measurement of heart rate, GPS position, and speed and distance based on acceleration measurement. These systems all focus on performance rather than technique. Running economy – the efficiency of the runner΄s movements – is largely determined by technique. So measurement of technique related parameters in the runner΄s natural environment would be a huge step forward, enabling athletes and coaches to work towards better running economy and thus also performance. In this paper a working prototype of a system is shown that has been developed to measure both technique and performance related parameters for runners during actual field training and races. The system measures various parameters: feet roll off using a foot pressure sensor, GPS speed and distance, core temperature and heart rate. The feet pressure data is used to determine ground contact time, heel off time, pace frequency, gait line, and pressure distribution during roll-off. The sensors transmit their data to a central computing unit, worn at the runner΄s back. This unit combines the data streams and sends them on to a host computer via a wireless internet link. The host computer runs data analysis software and presents the results on the internet. The system has been tested successfully during the Eindhoeven half marathon on October 14th 2007. Analysis of data shows an early and gradual increase of contact times and heel-off times which is probably related to early fatigue in (biarticular) leg muscles due to a too fast start of the runner. Future versions of the system will aim to decrease the size of the system, refine the data interpretation and incorporate new sensors such as EMG measurement. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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16. Effects of ideological and relational psychological contract breach and fulfilment on volunteers’ work effort.
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Vantilborgh, T., Bidee, J., Pepermans, R., Willems, J., Huybrechts, G., and Jegers, M.
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PSYCHOLOGICAL contracts (Employment) ,RESPONSE surfaces (Statistics) ,VOLUNTEERS ,BREACH of contract ,EMPLOYEES - Abstract
The ideological psychological contract (PC) describes perceived obligations related to an organization’s mission, values, and principles. The lack of research regarding ideological PC breach and fulfilment is surprising, as theory states that this PC type has distinct effects on outcomes. We address this gap in the literature and investigate how ideological PC breach and fulfilment influence volunteers’ work effort and whether this effect differs from relational PC breach and fulfilment. We measured promised and delivered ideological and relational inducements on two separate occasions and used polynomial regressions and response surface analyses to test our hypotheses. In the case of ideological PC fulfilment, results indicated that work effort increases in situations of mutual-low and mutual-high obligations. In the case of ideological PC breach, work effort increases in situations of under- and overfulfilment. We conclude that underfulfilment of ideological PCs differed from relational PCs, as work effort decreases in the case of the latter. Hence, our findings demonstrate the importance of considering the unique nature of ideological obligations in the PC literature. [ABSTRACT FROM PUBLISHER]
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- 2014
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17. ROBUST MULTILEVEL METHODS FOR GENERAL SYMMETRIC POSITIVE DEFINITE OPERATORS.
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WILLEMS, J.
- Subjects
ASYMPTOTIC theory of elliptic differential equations ,ROBUST stability analysis ,DISCRETIZATION methods ,EIGENVALUES ,MAXWELL equations - Abstract
A general robust multilevel method for solving symmetric positive definite systems resulting from discretizing elliptic partial differential equations is developed. The term "robust" refers to the convergence rate of the method being independent of discretization parameters, i.e., the problem size, and problem parameters. Important instances of such problem parameters are in particular (highly varying) coefficients. The method belongs to the class of (nonlinear) algebraic multilevel iterations. The crucial ingredient for obtaining robustness is the construction of a nested sequence of spaces based on local generalized eigenvalue problems. The method is analyzed in a rather general setting applying to the scalar elliptic equation, the equations of linear elasticity, and equations arising in the solution of Maxwell's equations. Numerical results for the scalar elliptic equation are presented showing its robust convergence behavior. [ABSTRACT FROM AUTHOR]
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- 2014
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18. Paediatric community-acquired septic shock: results from the REPEM network study.
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Van de Voorde, P., Emerson, B., Gomez, B., Willems, J., Yildizdas, D., Iglowstein, I., Kerkhof, E., Mullen, N., Pinto, C., Detaille, T., Qureshi, N., Naud, J., De Dooy, J., Van Lancker, R., Dupont, A., Boelsma, N., Mor, M., Walker, D., Sabbe, M., and Hachimi-Idrissi, S.
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SEPTIC shock ,PEDIATRICS ,ARTIFICIAL respiration ,SEPTICEMIA treatment ,CLINICAL trials - Abstract
Introduction and purpose of the study: With this study we aimed to describe a 'true world' picture of severe paediatric 'community-acquired' septic shock and establish the feasibility of a future prospective trial on early goal-directed therapy in children. During a 6-month to 1-year retrospective screening period in 16 emergency departments (ED) in 12 different countries, all children with severe sepsis and signs of decreased perfusion were included. Results: A 270,461 paediatric ED consultations were screened, and 176 cases were identified. Significant comorbidity was present in 35.8 % of these cases. Intensive care admission was deemed necessary in 65.7 %, mechanical ventilation in 25.9 % and vasoactive medications in 42.9 %. The median amount of fluid given in the first 6 h was 30 ml/kg. The overall mortality in this sample was 4.5 %. Only 1.2 % of the survivors showed a substantial decrease in Paediatric Overall Performance Category (POPC). 'Severe' outcome (death or a decrease ≥2 in POPC) was significantly related ( p < 0.01) to: any desaturation below 90 %, the amount of fluid given in the first 6 h, the need for and length of mechanical ventilation or vasoactive support, the use of dobutamine and a higher lactate or lower base excess but not to any variables of predisposition, infection or host response (as in the PIRO (Predisposition, Infection, Response, Organ dysfunction) concept). Conclusion: The outcome in our sample was very good. Many children received treatment early in their disease course, so avoiding subsequent intensive care. While certain variables predispose children to become septic and shocked, in our sample, only measures of organ dysfunction and concomitant treatment proved to be significantly related with outcome. We argue why future studies should rather be large multinational prospective observational trials and not necessarily randomised controlled trials. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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19. Innate recognition of apoptotic cells: novel apoptotic cell-associated molecular patterns revealed by crossreactivity of anti-LPS antibodies.
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Tennant, I, Pound, J D, Marr, L A, Willems, J J L P, Petrova, S, Ford, C A, Paterson, M, Devitt, A, and Gregory, C D
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APOPTOSIS ,PHAGOCYTES ,PATTERN recognition systems ,LIPOPOLYSACCHARIDES ,IMMUNOGLOBULINS ,LAMININS - Abstract
Cells dying by apoptosis are normally cleared by phagocytes through mechanisms that can suppress inflammation and immunity. Molecules of the innate immune system, the pattern recognition receptors (PRRs), are able to interact not only with conserved structures on microbes (pathogen-associated molecular patterns, PAMPs) but also with ligands displayed by apoptotic cells. We reasoned that PRRs might therefore interact with structures on apoptotic cells - apoptotic cell-associated molecular patterns (ACAMPs) - that are analogous to PAMPs. Here we show that certain monoclonal antibodies raised against the prototypic PAMP, lipopolysaccharide (LPS), can crossreact with apoptotic cells. We demonstrate that one such antibody interacts with a constitutively expressed intracellular protein, laminin-binding protein, which translocates to the cell surface during apoptosis and can interact with cells expressing the prototypic PRR, mCD14 as well as with CD14-negative cells. Anti-LPS cross reactive epitopes on apoptotic cells colocalised with annexin V- and C1q-binding sites on vesicular regions of apoptotic cell surfaces and were released associated with apoptotic cell-derived microvesicles (MVs). These results confirm that apoptotic cells and microbes can interact with the immune system through common elements and suggest that anti-PAMP antibodies could be used strategically to characterise novel ACAMPs associated not only with apoptotic cells but also with derived MVs. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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20. Autonomous Motivation Stimulates Volunteers' Work Effort: A Self-Determination Theory Approach to Volunteerism.
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Bidee, J., Vantilborgh, T., Pepermans, R., Huybrechts, G., Willems, J., Jegers, M., and Hofmans, J.
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VOLUNTEER service ,MOTIVATION (Psychology) ,AUTONOMY (Psychology) ,WORK ,ECONOMIC impact ,SELF-evaluation - Abstract
Copyright of Voluntas: International Journal of Voluntary & Nonprofit Organizations is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
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21. Verzekeringsgeneeskundige paradigmata 1901-2011.
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Willems, J. and Koten, J.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2012
- Full Text
- View/download PDF
22. VARIATIONAL MULTISCALE FINITE ELEMENT METHOD FOR FLOWS IN HIGHLY POROUS MEDIA.
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Iliev, O., Lazarov, R., and Willems, J.
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FINITE element method ,POROUS materials ,MULTISCALE modeling ,DARCY'S law ,FLUID dynamics ,APPROXIMATION theory ,ALGORITHMS ,NUMERICAL analysis - Abstract
We present a two-scale finite element method (FEM) for solving Brinkman's and Darcy's equations. These systems of equations model fluid flows in highly porous and porous media, respectively. The method uses a recently proposed discontinuous Galerkin FEM for Stokes' equations by Wang and Ye and the concept of subgrid approximation developed by Arbogast for Darcy's equations. In order to reduce the "resonance error" and to ensure convergence to the global fine solution, the algorithm is put in the framework of alternating Schwarz iterations using subdomains around the coarse-grid boundaries. The discussed algorithms are implemented using the Deal.II finite element library and are tested on a number of model problems. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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23. A New Deal for NPO Governance and Management: Implications for Volunteers Using Psychological Contract Theory.
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Vantilborgh, T., Bidee, J., Pepermans, R., Willems, J., Huybrechts, G., and Jegers, M.
- Abstract
Copyright of Voluntas: International Journal of Voluntary & Nonprofit Organizations is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2011
- Full Text
- View/download PDF
24. Flow around a NACA0018 airfoil with a cavity and its dynamical response to acoustic forcing.
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Olsman, W., Willems, J., Hirschberg, A., Colonius, T., and Trieling, R.
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AEROFOILS ,REYNOLDS number ,AERODYNAMICS ,VISCOUS flow ,FLUID dynamics - Abstract
Trapping of vortices in a cavity has been explored in recent years as a drag reduction measure for thick airfoils. If, however, trapping fails, then oscillation of the cavity flow may couple with elastic vibration modes of the airfoil. To examine this scenario, the effect of small amplitude vertical motion on the oscillation of the shear layer above the cavity is studied by acoustic forcing simulating a vertical translation of a modified NACA0018 profile. At low Reynolds numbers based on the chord ( O(10)), natural instability modes of this shear layer are observed for Strouhal numbers based on the cavity width of order unity. Acoustic forcing sufficiently close to the natural instability frequency induces a strong non-linear response due to lock-in of the shear layer. At higher Reynolds numbers (above 10) for Strouhal number 0.6 or lower, no natural instabilities of the shear layer and only a linear response to forcing were observed. The dynamical pressure difference across the airfoil is then dominated by added mass effects, as was confirmed by numerical simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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25. Is the International Physical Activity Questionnaire-Short Form (IPAQ-SF) valid for assessing physical activity in chronic fatigue syndrome?
- Author
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Meeus M, Van Eupen I, Willems J, Kos D, and Nijs J
- Abstract
Purpose. To evaluate the criterion validity and internal consistency of the International Physical Activity Questionnaire-short form (IPAQ-sf) in Chronic Fatigue Syndrome (CFS) patients. Method. Fifty-six CFS patients completed the IPAQ-sf after they wore a tri-axial accelerometer and filled out activity diaries during 1 week. Spearman rank correlation coefficients and Cronbach's Alpha were calculated. Results. The IPAQ-sf correlated significantly with the energy expenditure and Metabolic Equivalents (METs) minutes spent moderately to vigorously active following the activity diary and accelerometer. These correlation coefficients were however low ( r varying between 0.282 and 0.426) and rather irrelevant, since CFS patients hardly reach moderate or vigorous activity levels. Internal consistency between the three subitems used for the total score of the IPAQ-sf was 0.337. Conclusion. The observed associations between the IPAQ-sf data and the data obtained from the accelerometer (gold standard) and the diaries were too low to be in support of the use of the IPAQ-sf in patients with CFS. The IPAQ-sf does not seem an appropriate tool to assess physical activity in CFS patients. Further study is required to seek for a valid, practical and affordable tool. [ABSTRACT FROM AUTHOR]
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- 2011
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26. Stochastic control and the second law of thermodynamics.
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Brockett, R. and Willems, J.
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- 1978
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27. Wave induced growth and evaporation of droplets in a vapour-gas mixture.
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Smolders, H. J., Willems, J. F. H., de Lange, H. C., and van Dongen, M. E. H.
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- 1990
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28. Stochastic realization of spectral density matrices which may possess symmetries.
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Van Der Schaft, A. and Willems, J.
- Published
- 1984
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29. Bedrijfsarts Let Op Uw Saeck!
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Meer, H. and Willems, J.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
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- View/download PDF
30. A SIMPLIFIED METHOD FOR UPSCALING COMPOSITE MATERIALS WITH HIGH CONTRAST OF THE CONDUCTIVITY.
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Ewing, R., Iliev, O., Lazarov, R., Rybak, I., and Willems, J.
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COMPOSITE materials ,THERMAL conductivity ,HEAT exchangers ,HEAT equation ,HEAT transfer - Abstract
A large class of industrial composite materials, such as metal foams, fibrous glass materials, mineral wools, and the like, are widely used in insulation and advanced heat exchangers. These materials are characterized by a substantial difference between the thermal properties of the highly conductive materials (glass or metal) and the insulator (air) as well as low volume fractions and complex network-like structures of the highly conductive components. In this paper we address the important issue for the engineering practice of developing fast, reliable, and accurate methods for computing the macroscopic (upscaled) thermal conductivities of such materials. We assume that the materials have constant macroscopic thermal conductivity tensors, which can be obtained by upscaling techniques based on the postprocessing of a number of linearly independent solutions of the steady-state heat equation on representative elementary volumes (REVs). We propose, theoretically justify, and computationally study a numerical method for computing the effective conductivities of materials for which the ratio δ of low and high conductivities satisfies δ ⪡ 1. We show that in this case one needs to solve the heat equation in the region occupied by the highly conductive media only. Further, we prove that under certain conditions on the microscale geometry the proposed method gives an approximation that is O(δ)-close to the upscaled conductivity. Finally, we illustrate the accuracy and the limitations of the method on a number of numerical examples. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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31. Ontwikkelingen rond arbeid en gezondheid.
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Willems, J.
- Abstract
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- Published
- 2009
- Full Text
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32. Verwijsfunctie voor de verzekeringsarts?
- Author
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Willems, J. and Meer, H.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
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33. Eén casus, twee bedrijfsartsen, en 8 lessen geleerd.
- Author
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Willems, J. and Doppegieter, R.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
- Full Text
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34. Medico-legal reasoning in disability assessment: a focus group and validation study.
- Author
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de Boer, W. E. L., Donceel, P., Brage, S., Rus, M., and Willems, J. H. B. M.
- Subjects
DISABILITY retirement ,SOCIAL security ,HEALTH insurance ,PUBLIC health ,DISABILITY insurance - Abstract
Background: Decisions on disability pensions are based, among others, on medical reports. The way these medical assessments are performed is largely unclear. The aim of the study was to determine which grounds are used by social insurance physicians (SIPs) in these assessments and to determine if the identification of these grounds can help improve the quality of assessments in social insurance practice. The article describes a focus group study and a questionnaire study with SIPs in four different countries. Method: Using focus group discussions of SIPs discussing the same case in Belgium, the Netherlands, Norway and Slovenia (N = 29) we determined the arguments and underlying grounds as used by the SIP's. We used a questionnaire study among other SIPs (N = 60) in the same countries to establish a first validation of these grounds. Results: Grounds in the focus groups were comparable between the countries studied. The grounds were also recognized by SIPs who had not participated in the focus groups. SIPs agreed most on grounds with regard to the claimant's health condition, and about the claimant's duty to explore rehabilitation and work resumption, but less on accepting permanent incapacity when all options for treatment were exhausted. Conclusion: Grounds that SIPs use refer to a limited group of key elements of disability evaluation. SIPs interpret disability in social insurance according to the handicapped role and strive at making their evaluation fair trials. ICF is relevant with regard to the health condition and to the process of evaluation. Identification of grounds is a valuable instrument for controlling the quality of disability evaluation. The grounds also appear to be internationally comparable which may enhance scientific study in this area. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
35. Probabilistic approach to polychlorinated biphenyl (PCB) exposure through eel consumption in recreational fishermen vs. the general population.
- Author
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Bilau, M., Sioen, I., Matthys, C., de Vocht, A., Goemans, G., Belpaire, C., Willems, J. L., and de Henauw, S.
- Subjects
POLYCHLORINATED biphenyls ,FISHING ,FOOD consumption ,INGESTION ,HEAT transfer ,ANALYTICAL chemistry ,DIOXINS ,EELS - Abstract
Concentrations of the sum of the seven indicator PCBs (Σ7 iPCBs) measured in non-commercial European eel (Anguilla anguilla L.) in Flanders are high: in 80% of all sampled localities, the Belgian PCB standard for fish was exceeded. The objective of this study was to assess the intake of the Σ7 iPCBs through consumption of eel by recreational fishermen and to compare it to the intake of a background population. The median estimated intake for recreational fishermen varied between 18.4 and 237.6 ng iPCBs kg-1 bw day-1, depending on the consumption scenario, while the estimated intake of the background population (consumers only) was 4.3 ng iPCBs kg-1 bw day-1. Since the levels of intake via eel for two intake scenarios were, respectively, 50 and 25 times higher than the intake of the background population, the body burden (BB) might be proportionally higher and reach levels of toxicological relevance. The intake of the seven iPCBs via consumption of self-caught eel in Flanders is at a level to cause serious concern. The Flemish catch-and-release obligation for eel, established in 2002, should be maintained and supervised (more) carefully. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
36. Prognostic factors for work ability in sicklisted employees with chronic diseases.
- Author
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Slebus, F. G., Kuijer, P. P. F. M., Willems, J. (Han) H. B. M., Sluiter, J. K., and Frings-Dresen, M. H. W.
- Abstract
Objective: Identifying prognostic factors for work ability in sicklisted employees with myocardial infarction (Ml), chronic low back pain (cLBP) and major depressive disorder (MDD) in order to establish an objective basis for work ability evaluation. Design: Systematic literature search in PubMed database (1 January 1990 to 1 July 2006) with the Yale prognostic research filter. Inclusion criteria were as follows: (1) work-disabled employees; (2) MI, cLBP or MDD patients; (3) longitudinal designs; and (4) return to work or compensation status as outcome measure. Results: Four studies on MI met the inclusion criteria and described the following prognostic factors for work ability in the acute phase of the disease and disablement: lower age; male gender; no financial basis on which to retire; lower physical job demands; fewer somatic complaints; no anxiety attacks; no diabetes; no heart failure; no atrial fibrillation; no Q waves; and a short time interval between MI and presentation at the occupational medicine clinic. Two studies on cLBP met the inclusion criteria and described the following prognostic factors for work ability after 3 months' work disablement: lower age; male gender; no treatment before sick listing; surgery in the first year of sick listing; being a breadwinner; less pain; better general health; higher job satisfaction; lower physical and/or psychological demands at work; and a higher decision latitude at work. No relevant MDD studies were found. Conclusion: In the earlier phases of work disablement in MI and cLBP patients, only a few studies describe disease-specific, environmental and personal prognostic factors for return to work. No studies describe prognostic factors for MDD. More evidence is needed on the topic of prognostic factors for return to work in employees with chronic diseases. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
37. De scheiding van ‘behandeling en controle’: aan actualisering toe?
- Author
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Willems, J. and Doppegieter, R.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2007
- Full Text
- View/download PDF
38. De beoordeling van psychische invaliditeit bij uitgezonden militairen: een voorstel voor een nieuw meetinstrument.
- Author
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Willems, J., Paulusma-de Waal, J., and Kessel, J.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2007
- Full Text
- View/download PDF
39. NUMERICAL STUDY OF TWO-GRID PRECONDITIONERS FOR 1-D ELLIPTIC PROBLEMS WITH HIGHLY OSCILLATING DISCONTINUOUS COEFFICIENTS.
- Author
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Iliev, O., Lazarov, R., and Willems, J.
- Subjects
ITERATIVE methods (Mathematics) ,GALERKIN methods ,CONJUGATE gradient methods ,MATHEMATICAL variables ,STOCHASTIC convergence - Abstract
Various advanced two-level iterative methods are studied numerically and compared with each other in conjunction with finite volume discretizations of symmetric 1-D elliptic problems with highly oscillatory discontinuous coefficients. Some of the methods considered rely on the homogenization approach for deriving the coarse grid operator. This approach is considered here as an alternative to the well-known Galerkin approach for deriving coarse grid operators. Different intergrid transfer operators are studied, primary consideration being given to the use of the so-called problem-dependent prolongation. The two-grid methods considered are used as both solvers and preconditioners for the Conjugate Gradient method. The recent approaches, such as the hybrid domain decomposition method introduced by Vassilevski and the globallocal iterative procedure proposed by Durlofsky et al. are also discussed. A two-level method converging in one iteration in the case where the right-hand side is only a function of the coarse variable is introduced and discussed. Such a fast convergence for problems with discontinuous coefficients arbitrarily varying on the fine scale is achieved by a problem-dependent selection of the coarse grid combined with problem-dependent prolongation on a dual grid. The results of the numerical experiments are presented to illustrate the performance of the studied approaches. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
40. Onderzoek in de verzekeringsgeneeskunde in de lift.
- Author
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Hoving, J., Meijer, W., Willems, J., Mechelen, W., and Frings-Dresen, M.
- Abstract
Copyright of Tijdschrift voor Bedrijfs- En Verzekeringsgeneeskunde is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
- Full Text
- View/download PDF
41. Health-related quality of life of diabetic foot ulcer patients and their caregivers.
- Author
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Nabuurs-Franssen, M. H., Huijberts, M. S. P., Nieuwenhuijzen Kruseman, A. C., Willems, J., and Schaper, N. C.
- Subjects
ULCERS ,PEOPLE with diabetes ,SICK people ,CARE of people ,MEDICAL care ,QUALITY of life - Abstract
Aims/hypothesis: The effect of a foot ulcer on health-related quality of life (HRQoL) of patients with diabetes mellitus and their caregivers is unclear, and was therefore evaluated prospectively in this multicentre study. Methods: HRQoL according to the 36-item health-related quality of life questionnaire (SF-36) of 294 patients (ulcer duration ≥4 weeks) and 153 caregivers was analysed at baseline (time-point zero [T0]), once the ulcer was healed or after 20 weeks (time-point 1 [T1]), and 3 months later (time-point 2 [T2]). Patients with severe ischaemia were excluded. Results: The mean age of the patients was 60 years, 72% were male, and time since diagnosis of diabetes was 17 years. Patients reported a low HRQoL on all SF-36 subscales. At T1, HRQoL scores in physical and social functioning were higher in patients with a healed vs a non-healed ulcer (p«0.05). At T2, these differences were larger, with higher scores for physical and social functioning, role physical and the physical summary score (all p«0.05). Within-group analysis revealed that HRQoL improved in different subscales in patients with a healed ulcer and worsened in patients with a persistent ulcer from T0 to T2 (all p«0.05). The caregivers of patients with a persisting ulcer had more emotional difficulties at T2. Conclusions/interpretation: Diabetic patients with a healed foot ulcer had a higher HRQoL than patients with a persisting ulcer. Healing of a foot ulcer resulted in a marked improvement of several SF-36 subscales 3 months after healing (from T0 to T2). HRQoL declined progressively when the ulcer did not heal. A diabetic foot ulcer appeared to be a large emotional burden on the patients' caregivers, as well. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
42. Prostate cancer among pesticide applicators: a meta-analysis.
- Author
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Van Maele-Fabry, G. and Willems, J. L.
- Subjects
PROSTATE cancer ,MALE reproductive organs ,META-analysis ,MEDLINE ,INTERNET in medicine ,PESTICIDES - Abstract
Objectives:To analyse data from peer-reviewed, case-referent and cohort studies, studying the occurrence of prostate cancer in pesticide applicators and in some other, related, occupational categories, in order to determine a possible relationship of cancer of the prostate with pesticide exposure; to calculate a meta-rate ratio and to compare it with the meta-rate ratios obtained in a previous meta-analysis performed over a shorter time (1995-2001) in a broader exposure category, including many pesticide-related agricultural and non-agricultural occupations.Methods:Medline was searched for the years between 1966 and 2003, and relevant studies were identified from 1986 on. We conducted a meta-analysis of 22 studies complying with the inclusion criteria in order to pool their relative risk (RR) estimates. Studies were summarised and assessed for homogeneity and publication bias.Results:The meta-rate ratio, based on 22 estimates of RR, is 1.24 [95% confidence interval (95% CI) 1.06-1.45]. This pooled risk estimate for the occupational categories selected is higher than the one previously calculated for farmers in general over a shorter period of publication. Substantial heterogeneity of rate ratios exists between the different studies. The major source of heterogeneity identified is geographic location. Increased meta-rate ratios are observed for studies derived from North America as well as from Europe, the meta-rate ratios from Europe being lower than those from North America. There is no obvious indication of publication bias.Conclusion:The increased meta-rate ratio for prostate cancer in agricultural pesticide applications provides additional evidence for a possible relationship between pesticide exposure and prostate cancer. The homogeneity observed between the individual rate ratios, after we had regrouped the data according to geographic location, tends to increase the consistency of the association. However, the data available from the individual studies do not provide sufficient exposure information for firm conclusions to be drawn about pesticide exposure as the cause of prostate cancer, independently from other factors. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
43. Treatment of customary international law and use of expert evidence by the Dutch court in the Bouterse case.
- Author
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Willems, J. H. M.
- Subjects
INTERNATIONAL law ,PROSECUTION ,ACTIONS & defenses (Law) ,CONFLICT of laws ,LEGAL judgments - Abstract
The article discusses the treatment of customary international law and use of expert evidence by the Dutch Court in the Bouterse case. The case of Desi Bouterse for the execution of 15 people in Surinam on 9 December 1982, where his prosecution was quashed because of his being in the Netherlands. The effect of the Court of Appeal's order is to institute criminal proceedings is merely to oblige the Public Prosecution Service to initiate a prosecution, that does not bind the Trial Court with respect to the laws.
- Published
- 2004
- Full Text
- View/download PDF
44. Influence of collision on the flow through in-vitro rigid models of the vocal folds.
- Author
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M. Deverge, X. Pelorson, C. Vilain, P.-Y. Lagrée, Chentouf, F., Willems, J., and Hirschberg, A.
- Subjects
HUMAN voice ,SPEECH ,GLOTTIS ,VOCAL cords ,AUDITORY perception - Abstract
Measurements of pressure in oscillating rigid replicas of vocal folds are presented. The pressure upstream of the replica is used as input to various theoretical approximations to predict the pressure within the glottis. As the vocal folds collide the classical quasisteady boundary layer theory fails. It appears however that for physiologically reasonable shapes of the replicas, viscous effects are more important than the influence of the flow unsteadiness due to the wall movement. A simple model based on a quasisteady Bernoulli equation corrected for viscous effect, combined with a simple boundary layer separation model does globally predict the observed pressure behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
45. Occupation related pesticide exposure and cancer of the prostate: a meta-analysis.
- Author
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Van Maele-Fabry, G. and Willems, J. L.
- Abstract
Presents a study that examined epidemiological studies published between 1995 and 2001 that investigated the possible relation between prostate cancer and exposure to pesticides in farming and other pesticide-related working environments. Evaluation of homogeneity; Assessment of publication bias; Possible reasons for heterogeneity; Analysis of different occupational categories in relation to quantitative and qualitative differences in pesticide exposure.
- Published
- 2003
- Full Text
- View/download PDF
46. Response by Groningen Statisticians.
- Author
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Kardaun, O. J. W. F., Salomé, D., Schaafsma, W., Steerneman, A. G. M., and Willems, J. C.
- Published
- 2003
- Full Text
- View/download PDF
47. Reflections on Fourteen Cryptic Issues Concerning the Nature of Statistical Inference.
- Author
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Kardaun, O. J. W. F., Salomè, D., Schaafsma, W., Steerneman, A. G. M., Willems, J. C., and Cox, D.R.
- Published
- 2003
- Full Text
- View/download PDF
48. Simplified models of flue instruments: Influence of mouth geometry on the sound source.
- Author
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Dequand, S., Willems, J. F. H., Leroux, M., Vullings, R., van Weert, M., Thieulot, C., and Hirschberg, A.
- Subjects
FLUTE ,RECORDER (Musical instrument) ,ACOUSTICAL engineering ,SOUND ,MOUTH ,SOUND pressure - Abstract
Flue instruments such as the recorder flute and the transverse flute have different mouth geometries and acoustical response. The effect of the mouth geometry is studied by considering the aeroacoustical response of a simple whistle. The labium of a transverse flute has a large edge angle (60°) compared to that of a recorder flute (15°). Furthermore, the ratio W/h of the mouth width W to the jet thickness h can be varied in the transverse flute (lips of the musician) while it is fixed to a value W/h≈4 in a recorder flute. A systematic experimental study of the steady oscillation behavior has been carried out. Results of acoustical pressure measurements and flow visualization are presented. The sharp edge of the recorder provides a sound source which is rich in harmonics at the cost of stability. The larger angle of the labium of the flute seems to be motivated by a better stability of the oscillations for thick jets but could also be motivated by a reduction of broadband turbulence noise. We propose two simplified sound source models which could be used for sound synthesis: a jet-drive model for W/h>2 and a discrete-vortex model for W/h<2. © 2003 Acoustical Society of America. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
49. A rigorous framework for interactive robot control.
- Author
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Stramigioli, S., Fasse, E. D., and Willems, J. C.
- Subjects
ROBOT control systems ,MECHANICAL impedance - Abstract
This paper presents a rigorous, analytical framework for interactive control methods such as stiffness and impedance control. This paper does not present a novel synthesis method for robot control design. Rather, it presents a proper framework to analyse controllers for robots whose purpose is to interact energetically with the environment. First geometrical tools are introduced that are used in kinematic and dynamic analysis of the spatio-mechanical systems common in robotics. 'Port behaviour' and 'behavioural deviation' are then defined both intuitively and rigorously. The utility of this framework is demonstrated by a non-trivial example. Concepts of the behavioural approach are used. [ABSTRACT FROM AUTHOR]
- Published
- 2002
- Full Text
- View/download PDF
50. Probabilistic intake assessment and body burden estimation of dioxin-like substances in background conditions and during a short food contamination episode.
- Author
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Vrijens, B., De Henauw, S., Dewettinck, K., Talloen, W., Goeyens, L., De Backer, G., and Willems, J. L.
- Subjects
FOOD contamination ,DIOXINS - Abstract
The objective was to perform a dioxin body burden estimate based on a probabilistic intake assessment of PCDDs, PCDFs and dioxin-like PCBs because of the so-called 1999 'Belgian dioxin incident'. Monte Carlo simulation techniques were used to combine detailed 7-day food intake data on the individual level from a sample of 14-18-year-old adolescents with 'background' and 'incident-related' food contamination data. In background conditions, 3% of the adolescents had an intake <1 pg TEQ kg[sup -1] bw day[sup -1], while 85% had <4 pg TEQ kg[sup -1] bw day[sup -1]. Milk and other dairy products were the basic source of dioxin-like contaminants, while fish constituted the main source at the higher percentiles of intake. During the dioxin incident, the estimated median dioxin intake showed a moderate increase. At the 99th percentile, the highest intake level, and the 95% upper bound uncertainty level, peak body burden—23.73 ng TEQ kg[sup -1] bw—remained below body burdens that in the experimental animal or in man are accompanied by a population-based observable increase in the incidence of adverse effects. The 1999 Belgian dioxin incident most likely did not affect public health in Belgium in a measurable way, although exceptions remain possible on the individual level. [ABSTRACT FROM AUTHOR]
- Published
- 2002
- Full Text
- View/download PDF
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