29 results on '"Koens, L"'
Search Results
2. Real-time diagnostic accuracy of blue light imaging, linked color imaging and white-light endoscopy for colorectal polyp characterization
- Author
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Houwen, B., Vleugels, J.L.A., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kamiński, M.F., Rupińska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K., Fockens, P., Dekker, E., Hazewinkel, Y., Houwen, B., Vleugels, J.L.A., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kamiński, M.F., Rupińska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K., Fockens, P., Dekker, E., and Hazewinkel, Y.
- Abstract
Contains fulltext : 252188.pdf (Publisher’s version ) (Open Access), Background and study aims Fujifilm has developed a novel ELUXEO 7000 endoscope system that employs light-emitting diodes (LEDs) at four different wavelengths as light sources that enable blue light imaging (BLI), linked color imaging (LCI), and high-definition white-light endoscopy (HD-WLE). The aim of this study was to address the diagnostic accuracy of real-time polyp characterization using BLI, LCI and HD-WLE (ELUXEO 7000 endoscopy system). Patients methods This is a prespecified post-hoc analysis of a prospective study in which 22 experienced endoscopists (> 2,000 colonoscopies) from eight international centers participated. Using a combination of BLI, LCI, and HD-WLE, lesions were endoscopically characterized including a high- or low-confidence statement. Per protocol, digital images were created from all three imaging modalities. Histopathology was the reference standard. Endoscopists were familiar with polyp characterization, but did not take dedicated training for purposes of this study. Results Overall, 341 lesions were detected in 332 patients. Of the lesions, 269 histologically confirmed polyps with an optical diagnosis were included for analysis (165 adenomas, 27 sessile serrated lesions, and 77 hyperplastic polyps). Overall, polyp characterization was performed with high confidence in 82.9 %. The overall accuracy for polyp characterization was 75.1 % (95 % confidence interval [CI] 69.5-80.1 %), compared with an accuracy of 78.0 % (95 % CI 72.0-83.2 %) for high confidence assignments. The accuracy for endoscopic characterization for diminutive polyps was 74.7 % (95 %CI 68.4-80.3 %), compared with an accuracy of 78.2 % (95 % CI 71.4-84.0 %) for high-confidence assignments. Conclusions The diagnostic accuracy of BLI, LCI, and HD-WLE by experienced endoscopist for real-time polyp characterization seems limited (NCT03344289).
- Published
- 2022
3. Linked Colour imaging for the detection of polyps in patients with Lynch syndrome: a multicentre, parallel randomised controlled trial
- Author
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Houwen, B., Hazewinkel, Y., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kaminski, M.F., Rupinska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K.M., Fockens, P., Vleugels, J.L.A., Dekker, E., Houwen, B., Hazewinkel, Y., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kaminski, M.F., Rupinska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K.M., Fockens, P., Vleugels, J.L.A., and Dekker, E.
- Abstract
Contains fulltext : 252171.pdf (Publisher’s version ) (Open Access), OBJECTIVE: Despite regular colonoscopy surveillance, colorectal cancers still occur in patients with Lynch syndrome. Thus, detection of all relevant precancerous lesions remains very important. The present study investigates Linked Colour imaging (LCI), an image-enhancing technique, as compared with high-definition white light endoscopy (HD-WLE) for the detection of polyps in this patient group. DESIGN: This prospective, randomised controlled trial was performed by 22 experienced endoscopists from eight centres in six countries. Consecutive Lynch syndrome patients ≥18 years undergoing surveillance colonoscopy were randomised (1:1) and stratified by centre for inspection with either LCI or HD-WLE. Primary outcome was the polyp detection rate (PDR). RESULTS: Between January 2018 and March 2020, 357 patients were randomised and 332 patients analysed (160 LCI, 172 HD-WLE; 6 excluded due to incomplete colonoscopies and 19 due to insufficient bowel cleanliness). No significant difference was observed in PDR with LCI (44.4%; 95% CI 36.5% to 52.4%) compared with HD-WLE (36.0%; 95% CI 28.9% to 43.7%) (p=0.12). Of the secondary outcome parameters, more adenomas were found on a patient (adenoma detection rate 36.3%; vs 25.6%; p=0.04) and a colonoscopy basis (mean adenomas per colonoscopy 0.65 vs 0.42; p=0.04). The median withdrawal time was not statistically different between LCI and HD-WLE (12 vs 11 min; p=0.16). CONCLUSION: LCI did not improve the PDR compared with HD-WLE in patients with Lynch syndrome undergoing surveillance. The relevance of findings more adenomas by LCI has to be examined further. TRIAL REGISTRATION NUMBER: NCT03344289.
- Published
- 2022
4. Endoscopic full-thickness resection of T1 colorectal cancers: a retrospective analysis from a multicenter Dutch eFTR registry
- Author
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Zwager, L.W., Bastiaansen, Barbara A.J., Spek, B.W. van der, Heine, D.N., Schreuder, R.M., Perk, L.E., Weusten, B., Boonstra, J.J., Sluis, H. van der, Wolters, H.J., Bekkering, F.C., Rietdijk, S.T., Schwartz, M.P., Nagengast, W.B., Hove, W.R. ten, Droste, J.S. Terhaar Sive, Munoz, F.J. Rando, Vlug, M.S., Beaumont, H., Houben, M, Seerden, T.C., Wijkerslooth, T.R. de, Gielisse, E.A.R., Hazewinkel, Y., Ridder, R. de, Straathof, J.A., Vlugt, M. van der, Koens, L., Fockens, P., Dekker, E., Zwager, L.W., Bastiaansen, Barbara A.J., Spek, B.W. van der, Heine, D.N., Schreuder, R.M., Perk, L.E., Weusten, B., Boonstra, J.J., Sluis, H. van der, Wolters, H.J., Bekkering, F.C., Rietdijk, S.T., Schwartz, M.P., Nagengast, W.B., Hove, W.R. ten, Droste, J.S. Terhaar Sive, Munoz, F.J. Rando, Vlug, M.S., Beaumont, H., Houben, M, Seerden, T.C., Wijkerslooth, T.R. de, Gielisse, E.A.R., Hazewinkel, Y., Ridder, R. de, Straathof, J.A., Vlugt, M. van der, Koens, L., Fockens, P., and Dekker, E.
- Abstract
Item does not contain fulltext, BACKGROUND: Complete endoscopic resection and accurate histological evaluation for T1 colorectal cancer (CRC) are critical in determining subsequent treatment. Endoscopic full-thickness resection (eFTR) is a new treatment option for T1 CRC < 2 cm. We aimed to report clinical outcomes and short-term results. METHODS: Consecutive eFTR procedures for T1 CRC, prospectively recorded in our national registry between November 2015 and April 2020, were retrospectively analyzed. Primary outcomes were technical success and R0 resection. Secondary outcomes were histological risk assessment, curative resection, adverse events, and short-term outcomes. RESULTS: We included 330 procedures: 132 primary resections and 198 secondary scar resections after incomplete T1 CRC resection. Overall technical success, R0 resection, and curative resection rates were 87.0 % (95 % confidence interval [CI] 82.7 %-90.3 %), 85.6 % (95 %CI 81.2 %-89.2 %), and 60.3 % (95 %CI 54.7 %-65.7 %). Curative resection rate was 23.7 % (95 %CI 15.9 %-33.6 %) for primary resection of T1 CRC and 60.8 % (95 %CI 50.4 %-70.4 %) after excluding deep submucosal invasion as a risk factor. Risk stratification was possible in 99.3 %. The severe adverse event rate was 2.2 %. Additional oncological surgery was performed in 49/320 (15.3 %), with residual cancer in 11/49 (22.4 %). Endoscopic follow-up was available in 200/242 (82.6 %), with a median of 4 months and residual cancer in 1 (0.5 %) following an incomplete resection. CONCLUSIONS: eFTR is relatively safe and effective for resection of small T1 CRC, both as primary and secondary treatment. eFTR can expand endoscopic treatment options for T1 CRC and could help to reduce surgical overtreatment. Future studies should focus on long-term outcomes.
- Published
- 2022
5. Real-time diagnostic accuracy of blue light imaging, linked color imaging and white-light endoscopy for colorectal polyp characterization
- Author
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Houwen, B., Vleugels, J.L.A., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kamiński, M.F., Rupińska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K., Fockens, P., Dekker, E., Hazewinkel, Y., Houwen, B., Vleugels, J.L.A., Pellisé, M., Rivero-Sánchez, L., Balaguer, F., Bisschops, R., Tejpar, S., Repici, A., Ramsoekh, D., Jacobs, M., Schreuder, R.M., Kamiński, M.F., Rupińska, M., Bhandari, P., Oijen, M.G. van, Koens, L., Bastiaansen, Barbara A.J., Tytgat, K., Fockens, P., Dekker, E., and Hazewinkel, Y.
- Abstract
Contains fulltext : 252188.pdf (Publisher’s version ) (Open Access), Background and study aims Fujifilm has developed a novel ELUXEO 7000 endoscope system that employs light-emitting diodes (LEDs) at four different wavelengths as light sources that enable blue light imaging (BLI), linked color imaging (LCI), and high-definition white-light endoscopy (HD-WLE). The aim of this study was to address the diagnostic accuracy of real-time polyp characterization using BLI, LCI and HD-WLE (ELUXEO 7000 endoscopy system). Patients methods This is a prespecified post-hoc analysis of a prospective study in which 22 experienced endoscopists (> 2,000 colonoscopies) from eight international centers participated. Using a combination of BLI, LCI, and HD-WLE, lesions were endoscopically characterized including a high- or low-confidence statement. Per protocol, digital images were created from all three imaging modalities. Histopathology was the reference standard. Endoscopists were familiar with polyp characterization, but did not take dedicated training for purposes of this study. Results Overall, 341 lesions were detected in 332 patients. Of the lesions, 269 histologically confirmed polyps with an optical diagnosis were included for analysis (165 adenomas, 27 sessile serrated lesions, and 77 hyperplastic polyps). Overall, polyp characterization was performed with high confidence in 82.9 %. The overall accuracy for polyp characterization was 75.1 % (95 % confidence interval [CI] 69.5-80.1 %), compared with an accuracy of 78.0 % (95 % CI 72.0-83.2 %) for high confidence assignments. The accuracy for endoscopic characterization for diminutive polyps was 74.7 % (95 %CI 68.4-80.3 %), compared with an accuracy of 78.2 % (95 % CI 71.4-84.0 %) for high-confidence assignments. Conclusions The diagnostic accuracy of BLI, LCI, and HD-WLE by experienced endoscopist for real-time polyp characterization seems limited (NCT03344289).
- Published
- 2022
6. Endoscopic full-thickness resection of T1 colorectal cancers: a retrospective analysis from a multicenter Dutch eFTR registry
- Author
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Zwager, L.W., Bastiaansen, Barbara A.J., Spek, B.W. van der, Heine, D.N., Schreuder, R.M., Perk, L.E., Weusten, B., Boonstra, J.J., Sluis, H. van der, Wolters, H.J., Bekkering, F.C., Rietdijk, S.T., Schwartz, M.P., Nagengast, W.B., Hove, W.R. ten, Droste, J.S. Terhaar Sive, Munoz, F.J. Rando, Vlug, M.S., Beaumont, H., Houben, M, Seerden, T.C., Wijkerslooth, T.R. de, Gielisse, E.A.R., Hazewinkel, Y., Ridder, R. de, Straathof, J.A., Vlugt, M. van der, Koens, L., Fockens, P., Dekker, E., Zwager, L.W., Bastiaansen, Barbara A.J., Spek, B.W. van der, Heine, D.N., Schreuder, R.M., Perk, L.E., Weusten, B., Boonstra, J.J., Sluis, H. van der, Wolters, H.J., Bekkering, F.C., Rietdijk, S.T., Schwartz, M.P., Nagengast, W.B., Hove, W.R. ten, Droste, J.S. Terhaar Sive, Munoz, F.J. Rando, Vlug, M.S., Beaumont, H., Houben, M, Seerden, T.C., Wijkerslooth, T.R. de, Gielisse, E.A.R., Hazewinkel, Y., Ridder, R. de, Straathof, J.A., Vlugt, M. van der, Koens, L., Fockens, P., and Dekker, E.
- Abstract
Item does not contain fulltext, BACKGROUND: Complete endoscopic resection and accurate histological evaluation for T1 colorectal cancer (CRC) are critical in determining subsequent treatment. Endoscopic full-thickness resection (eFTR) is a new treatment option for T1 CRC < 2 cm. We aimed to report clinical outcomes and short-term results. METHODS: Consecutive eFTR procedures for T1 CRC, prospectively recorded in our national registry between November 2015 and April 2020, were retrospectively analyzed. Primary outcomes were technical success and R0 resection. Secondary outcomes were histological risk assessment, curative resection, adverse events, and short-term outcomes. RESULTS: We included 330 procedures: 132 primary resections and 198 secondary scar resections after incomplete T1 CRC resection. Overall technical success, R0 resection, and curative resection rates were 87.0 % (95 % confidence interval [CI] 82.7 %-90.3 %), 85.6 % (95 %CI 81.2 %-89.2 %), and 60.3 % (95 %CI 54.7 %-65.7 %). Curative resection rate was 23.7 % (95 %CI 15.9 %-33.6 %) for primary resection of T1 CRC and 60.8 % (95 %CI 50.4 %-70.4 %) after excluding deep submucosal invasion as a risk factor. Risk stratification was possible in 99.3 %. The severe adverse event rate was 2.2 %. Additional oncological surgery was performed in 49/320 (15.3 %), with residual cancer in 11/49 (22.4 %). Endoscopic follow-up was available in 200/242 (82.6 %), with a median of 4 months and residual cancer in 1 (0.5 %) following an incomplete resection. CONCLUSIONS: eFTR is relatively safe and effective for resection of small T1 CRC, both as primary and secondary treatment. eFTR can expand endoscopic treatment options for T1 CRC and could help to reduce surgical overtreatment. Future studies should focus on long-term outcomes.
- Published
- 2022
7. Order and information in the patterns of spinning magnetic micro disks at the air water interface
- Author
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Sitti, Metin (ORCID 0000-0001-8249-3854 & YÖK ID 297104), Wang, W.; Gardi, G.; Malgaretti, P.; Kishore, V.; Koens, L.; Son, D.; Gilbert, H.; Wu, Z.; Harwani, P.; Lauga, E.; Holm, C., College of Engineering; School of Medicine, Department of Mechanical Engineering, Sitti, Metin (ORCID 0000-0001-8249-3854 & YÖK ID 297104), Wang, W.; Gardi, G.; Malgaretti, P.; Kishore, V.; Koens, L.; Son, D.; Gilbert, H.; Wu, Z.; Harwani, P.; Lauga, E.; Holm, C., College of Engineering; School of Medicine, and Department of Mechanical Engineering
- Abstract
The application of the Shannon entropy to study the relationship between information and structures has yielded insights into molecular and material systems. However, the difficulty in directly observing and manipulating atoms and molecules hampers the ability of these systems to serve as model systems for further exploring the links between information and structures. Here, we use, as a model experimental system, hundreds of spinning magnetic micro-disks self-organizing at the air-water interface to generate various spatiotemporal patterns with varying degrees of order. Using the neighbor distance as the information-bearing variable, we demonstrate the links among information, structure, and interactions. We establish a direct link between information and structure without using explicit knowledge of interactions. Last, we show that the Shannon entropy by neighbor distances is a powerful observable in characterizing structural changes. Our findings are relevant for analyzing natural self-organizing systems and for designing collective robots., Max Planck Society; International Max Planck Research School for Intelligent Systems (IMPRS-IS); Alexander von Humboldt Foundation Fellowship Support
- Published
- 2022
8. Axial slicing versus bivalving in the pathological examination of pancreatoduodenectomy specimens (APOLLO): a multicentre randomized controlled trial
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Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., Verheij, J., Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., and Verheij, J.
- Abstract
Item does not contain fulltext, BACKGROUND: In pancreatoduodenectomy specimens, dissection method may affect the assessment of primary tumour origin (i.e. pancreatic, distal bile duct or ampullary adenocarcinoma), which is primarily determined macroscopically. This is the first study to prospectively compare the two commonly used techniques, i.e. axial slicing and bivalving. METHODS: In four centres, a randomized controlled trial was performed in specimens of patients with a suspected (pre)malignant tumour in the pancreatic head. Primary outcome measure was the level of certainty (scale 0-100) regarding tumour origin by four independent gastrointestinal pathologists based on macroscopic assessment. Secondary outcomes were inter-observer agreement and R1 rate. RESULTS: In total, 128 pancreatoduodenectomy specimens were randomized. The level of certainty in determining the primary tumour origin did not differ between axial slicing and bivalving (mean score 72 [sd 13] vs. 68 [sd 16], p = 0.21), nor did inter-observer agreement, both being moderate (kappa 0.45 vs. 0.47). In pancreatic cancer specimens, R1 rate (60% vs. 55%, p = 0.71) and the number of harvested lymph nodes (median 16 vs. 17, p = 0.58) were similar. CONCLUSION: This study demonstrated no differences in determining the tumour origin between axial slicing and bivalving. Both techniques performed similarly regarding inter-observer agreement, R1 rate, and lymph node harvest.
- Published
- 2021
9. Axial slicing versus bivalving in the pathological examination of pancreatoduodenectomy specimens (APOLLO): a multicentre randomized controlled trial
- Author
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van Roessel, S. (Stijn), Soer, E.C. (Eline C.), Van Dieren, S. (Susan), Koens, L. (Lianne), Velthuysen, M.L.F. (Loes) van, Doukas, M. (Michael), Groot Koerkamp, B. (Bas), Fariña-Sarasqueta, A. (Arantza), Bronkhorst, C.M. (Carolien), Raicu, G.M. (G. Mihaela), Kuijpers, K.C. (Karel C.), Seldenrijk, K.A. (Kees), Santvoort, H.C. (Hjalmar) van, Molenaar, I.Q. (I. Quintus), Van Der Post, R.S. (Rachel S.), Stommel, M.W.J. (Martijn W.J.), Busch, O.R.C. (Olivier), Besselink, M.G. (Marc), Brosens, L.A. (Lodewijk), Verheij, J. (Joanne), van Roessel, S. (Stijn), Soer, E.C. (Eline C.), Van Dieren, S. (Susan), Koens, L. (Lianne), Velthuysen, M.L.F. (Loes) van, Doukas, M. (Michael), Groot Koerkamp, B. (Bas), Fariña-Sarasqueta, A. (Arantza), Bronkhorst, C.M. (Carolien), Raicu, G.M. (G. Mihaela), Kuijpers, K.C. (Karel C.), Seldenrijk, K.A. (Kees), Santvoort, H.C. (Hjalmar) van, Molenaar, I.Q. (I. Quintus), Van Der Post, R.S. (Rachel S.), Stommel, M.W.J. (Martijn W.J.), Busch, O.R.C. (Olivier), Besselink, M.G. (Marc), Brosens, L.A. (Lodewijk), and Verheij, J. (Joanne)
- Abstract
Background: In pancreatoduodenectomy specimens, dissection method may affect the assessment of primary tumour origin (i.e. pancreatic, distal bile duct or ampullary adenocarcinoma), which is primarily determined macroscopically. This is the first study to prospectively compare the two commonly used techniques, i.e. axial slicing and bivalving. Methods: In four centres, a randomized controlled trial was performed in specimens of patients with a suspected (pre)malignant tumour in the pancreatic head. Primary outcome measure was the level of certainty (scale 0–100) regarding tumour origin by four independent gastrointestinal pathologists based on macroscopic assessment. Secondary outcomes were inter-observer agreement and R1 rate. Results: In total, 128 pancreatoduodenectomy specimens were randomized. The level of certainty in determining the primary tumour origin did not differ between axial slicing and bivalving (mean score 72 [sd 13] vs. 68 [sd 16], p = 0.21), nor did inter-observer agreement, both being moderate (kappa 0.45 vs. 0.47). In pancreatic cancer specimens, R1 rate (60% vs. 55%, p = 0.71) and the number of harvested lymph nodes (median 16 vs. 17, p = 0.58) were similar. Conclusion: This study demonstrated no differences in determining the tumour origin between axial slicing and bivalving. Both techniques performed similarly regarding inter-observer agreement, R1 rate, and lymph node harvest.
- Published
- 2021
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10. Axial slicing versus bivalving in the pathological examination of pancreatoduodenectomy specimens (APOLLO): a multicentre randomized controlled trial
- Author
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Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., Verheij, J., Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., and Verheij, J.
- Abstract
Contains fulltext : 238983.pdf (Publisher’s version ) (Open Access), BACKGROUND: In pancreatoduodenectomy specimens, dissection method may affect the assessment of primary tumour origin (i.e. pancreatic, distal bile duct or ampullary adenocarcinoma), which is primarily determined macroscopically. This is the first study to prospectively compare the two commonly used techniques, i.e. axial slicing and bivalving. METHODS: In four centres, a randomized controlled trial was performed in specimens of patients with a suspected (pre)malignant tumour in the pancreatic head. Primary outcome measure was the level of certainty (scale 0-100) regarding tumour origin by four independent gastrointestinal pathologists based on macroscopic assessment. Secondary outcomes were inter-observer agreement and R1 rate. RESULTS: In total, 128 pancreatoduodenectomy specimens were randomized. The level of certainty in determining the primary tumour origin did not differ between axial slicing and bivalving (mean score 72 [sd 13] vs. 68 [sd 16], p = 0.21), nor did inter-observer agreement, both being moderate (kappa 0.45 vs. 0.47). In pancreatic cancer specimens, R1 rate (60% vs. 55%, p = 0.71) and the number of harvested lymph nodes (median 16 vs. 17, p = 0.58) were similar. CONCLUSION: This study demonstrated no differences in determining the tumour origin between axial slicing and bivalving. Both techniques performed similarly regarding inter-observer agreement, R1 rate, and lymph node harvest.
- Published
- 2021
11. Axial slicing versus bivalving in the pathological examination of pancreatoduodenectomy specimens (APOLLO): a multicentre randomized controlled trial
- Author
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Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., Verheij, J., Roessel, S. van, Soer, E.C., Dieren, S. van, Koens, L., Velthuysen, M.L. van, Doukas, M., Groot Koerkamp, B., Sarasqueta, A.F., Bronkhorst, C.M., Raicu, G.M., Kuijpers, K.C., Seldenrijk, C.A., Santvoort, H.C. van, Molenaar, I.Q., Post, R.S. van der, Stommel, M.W.J., Busch, O.R., Besselink, M.G.H., Brosens, L.A.A., and Verheij, J.
- Abstract
Contains fulltext : 238983.pdf (Publisher’s version ) (Open Access), BACKGROUND: In pancreatoduodenectomy specimens, dissection method may affect the assessment of primary tumour origin (i.e. pancreatic, distal bile duct or ampullary adenocarcinoma), which is primarily determined macroscopically. This is the first study to prospectively compare the two commonly used techniques, i.e. axial slicing and bivalving. METHODS: In four centres, a randomized controlled trial was performed in specimens of patients with a suspected (pre)malignant tumour in the pancreatic head. Primary outcome measure was the level of certainty (scale 0-100) regarding tumour origin by four independent gastrointestinal pathologists based on macroscopic assessment. Secondary outcomes were inter-observer agreement and R1 rate. RESULTS: In total, 128 pancreatoduodenectomy specimens were randomized. The level of certainty in determining the primary tumour origin did not differ between axial slicing and bivalving (mean score 72 [sd 13] vs. 68 [sd 16], p = 0.21), nor did inter-observer agreement, both being moderate (kappa 0.45 vs. 0.47). In pancreatic cancer specimens, R1 rate (60% vs. 55%, p = 0.71) and the number of harvested lymph nodes (median 16 vs. 17, p = 0.58) were similar. CONCLUSION: This study demonstrated no differences in determining the tumour origin between axial slicing and bivalving. Both techniques performed similarly regarding inter-observer agreement, R1 rate, and lymph node harvest.
- Published
- 2021
12. Suboptimal endoscopic cancer recognition in colorectal lesions in a national bowel screening programme
- Author
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Vleugels, J.L.A., Koens, L., Dijkgraaf, M.G., Houwen, B., Hazewinkel, Y., Fockens, P., Dekker, E., Vleugels, J.L.A., Koens, L., Dijkgraaf, M.G., Houwen, B., Hazewinkel, Y., Fockens, P., and Dekker, E.
- Abstract
Contains fulltext : 220013.pdf (Publisher’s version ) (Open Access)
- Published
- 2020
13. Suboptimal endoscopic cancer recognition in colorectal lesions in a national bowel screening programme
- Author
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Vleugels, J.L.A., Koens, L., Dijkgraaf, M.G., Houwen, B., Hazewinkel, Y., Fockens, P., Dekker, E., Vleugels, J.L.A., Koens, L., Dijkgraaf, M.G., Houwen, B., Hazewinkel, Y., Fockens, P., and Dekker, E.
- Abstract
Contains fulltext : 220013.pdf (Publisher’s version ) (Open Access)
- Published
- 2020
14. Interobserver, intraobserver, and interlaboratory variability in reporting pT4a colon cancer
- Author
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Klaver, CEL, Bulkmans, N, Drillenburg, P, Grabsch, HI, van Grieken, NCT, Karrenbeld, A, Koens, L, van Lijnschoten, I, Meijer, J, Nagtegaal, ID, Sagaert, X, Seldenrijk, K, van Velthuysen, MLF (M. Loes), Bruggink, AH, Tanis, PJ, Snaebjornsson, P, Klaver, CEL, Bulkmans, N, Drillenburg, P, Grabsch, HI, van Grieken, NCT, Karrenbeld, A, Koens, L, van Lijnschoten, I, Meijer, J, Nagtegaal, ID, Sagaert, X, Seldenrijk, K, van Velthuysen, MLF (M. Loes), Bruggink, AH, Tanis, PJ, and Snaebjornsson, P
- Published
- 2020
15. Optical diagnosis expanded to small polyps: post-hoc analysis of diagnostic performance in a prospective multicenter study
- Author
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Vleugels, J.L.A., Hazewinkel, Y., Dijkgraaf, M.G., Koens, L., Fockens, P., Dekker, E., Vleugels, J.L.A., Hazewinkel, Y., Dijkgraaf, M.G., Koens, L., Fockens, P., and Dekker, E.
- Abstract
Item does not contain fulltext, BACKGROUND: Optical diagnosis can replace histopathology of diminutive (1 - 5 mm) polyps if surveillance intervals based on optical diagnosis of polyps have >/= 90 % agreement with intervals based on polyp histology and if the negative predictive value (NPV) for predicting neoplastic histology in the rectosigmoid is >/= 90 %. This study aims to assess whether small (6 - 9 mm) polyps can be included in optical diagnosis strategies. METHOD: This is a post-hoc analysis of a prospective multicenter study in which 27 endoscopists, all performing endoscopies for the Dutch screening program, were trained in optical diagnosis. For 1 year, endoscopists recorded the predicted histology for all lesions detected using narrow-band imaging during 3144 consecutive colonoscopies after a positive fecal immunochemical test, along with confidence levels. Surveillance interval agreement and NPV were calculated for high confidence predictions for polyps of 1 - 9 mm and compared with histopathology. Surveillance interval agreement was calculated using the European Society of Gastrointestinal Endoscopy surveillance guideline. RESULTS: Surveillance interval agreement was 95.4 % (confidence interval [CI] 94.2 % - 96.4 %), and NPV for predicting neoplastic histology in the rectosigmoid 90.0 % (CI 87.3 % - 92.2 %). The reduction in histology (45.9 % vs. 30.5 %) and the proportion of patients who could have received direct surveillance advice (15.6 % vs. 7.3 %) was higher when small polyps were included (P < 0.001). T1 cancer was found in seven small polyps (0.33 %), five of which would have been discarded without histopathology. CONCLUSION: Including small polyps in the optical diagnosis strategy improves its efficacy while maintaining performance thresholds. However, there is a small risk of missing T1 cancers when small polyps are included in the optical diagnosis strategy.
- Published
- 2019
16. Safety and cost analysis of selective histopathological examination following appendicectomy and cholecystectomy (FANCY study): protocol and statistical analysis plan of a prospective observational multicentre study
- Author
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Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., Bemelman, W.A., Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., and Bemelman, W.A.
- Abstract
Contains fulltext : 215707.pdf (publisher's version ) (Open Access), INTRODUCTION: Routine histopathological examination following appendicectomy and cholecystectomy has significant financial implications and comprises a substantial portion of the pathologists' workload, while the incidence of unexpected pathology is low. The aim of the selective histopathological examination Following AppeNdicectomy and CholecystectomY (FANCY) study is to investigate the oncological safety and potential cost savings of selective histopathological examination based on macroscopic assessment performed by the surgeon. METHODS AND ANALYSIS: This is a Dutch multicentre prospective observational study, in which removed appendices and gallbladders will be systematically assessed by the operating surgeon for macroscopic abnormalities suspicious for malignant neoplasms. After visual inspection and digital palpation of the removed specimen, the operating surgeon will report whether macroscopic abnormalities suspicious for a malignant neoplasm are present, and if he or she believes additional microscopic examination by the pathologist is indicated. Regardless of the surgeon's assessment, all specimens will be sent for histopathological examination. In this way, routine histopathological examination can be compared with a hypothetical situation in which specimens are routinely examined by surgeons and only sent to the pathologist on indication. The two main outcomes are oncological safety and potential cost savings of a selective policy. Oncological safety of selective histopathological examination will be assessed by calculating the number of patients in whom a histopathological diagnosis of an appendiceal neoplasm or gallbladder cancer with clinical consequences benefitting the patient would have been missed. A cost analysis will be performed to quantify the potential cost savings. ETHICS AND DISSEMINATION: The study protocol was reviewed by the Institutional Review Board of the Amsterdam UMC, location AMC, which decided that the Dutch Medical Research Involv
- Published
- 2019
17. Optical diagnosis expanded to small polyps: post-hoc analysis of diagnostic performance in a prospective multicenter study
- Author
-
Vleugels, J.L.A., Hazewinkel, Y., Dijkgraaf, M.G., Koens, L., Fockens, P., Dekker, E., Vleugels, J.L.A., Hazewinkel, Y., Dijkgraaf, M.G., Koens, L., Fockens, P., and Dekker, E.
- Abstract
Contains fulltext : 215290.pdf (Publisher’s version ) (Closed access), BACKGROUND: Optical diagnosis can replace histopathology of diminutive (1 - 5 mm) polyps if surveillance intervals based on optical diagnosis of polyps have >/= 90 % agreement with intervals based on polyp histology and if the negative predictive value (NPV) for predicting neoplastic histology in the rectosigmoid is >/= 90 %. This study aims to assess whether small (6 - 9 mm) polyps can be included in optical diagnosis strategies. METHOD: This is a post-hoc analysis of a prospective multicenter study in which 27 endoscopists, all performing endoscopies for the Dutch screening program, were trained in optical diagnosis. For 1 year, endoscopists recorded the predicted histology for all lesions detected using narrow-band imaging during 3144 consecutive colonoscopies after a positive fecal immunochemical test, along with confidence levels. Surveillance interval agreement and NPV were calculated for high confidence predictions for polyps of 1 - 9 mm and compared with histopathology. Surveillance interval agreement was calculated using the European Society of Gastrointestinal Endoscopy surveillance guideline. RESULTS: Surveillance interval agreement was 95.4 % (confidence interval [CI] 94.2 % - 96.4 %), and NPV for predicting neoplastic histology in the rectosigmoid 90.0 % (CI 87.3 % - 92.2 %). The reduction in histology (45.9 % vs. 30.5 %) and the proportion of patients who could have received direct surveillance advice (15.6 % vs. 7.3 %) was higher when small polyps were included (P < 0.001). T1 cancer was found in seven small polyps (0.33 %), five of which would have been discarded without histopathology. CONCLUSION: Including small polyps in the optical diagnosis strategy improves its efficacy while maintaining performance thresholds. However, there is a small risk of missing T1 cancers when small polyps are included in the optical diagnosis strategy.
- Published
- 2019
18. Safety and cost analysis of selective histopathological examination following appendicectomy and cholecystectomy (FANCY study): protocol and statistical analysis plan of a prospective observational multicentre study
- Author
-
Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., Bemelman, W.A., Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., and Bemelman, W.A.
- Abstract
Contains fulltext : 215707.pdf (publisher's version ) (Open Access), INTRODUCTION: Routine histopathological examination following appendicectomy and cholecystectomy has significant financial implications and comprises a substantial portion of the pathologists' workload, while the incidence of unexpected pathology is low. The aim of the selective histopathological examination Following AppeNdicectomy and CholecystectomY (FANCY) study is to investigate the oncological safety and potential cost savings of selective histopathological examination based on macroscopic assessment performed by the surgeon. METHODS AND ANALYSIS: This is a Dutch multicentre prospective observational study, in which removed appendices and gallbladders will be systematically assessed by the operating surgeon for macroscopic abnormalities suspicious for malignant neoplasms. After visual inspection and digital palpation of the removed specimen, the operating surgeon will report whether macroscopic abnormalities suspicious for a malignant neoplasm are present, and if he or she believes additional microscopic examination by the pathologist is indicated. Regardless of the surgeon's assessment, all specimens will be sent for histopathological examination. In this way, routine histopathological examination can be compared with a hypothetical situation in which specimens are routinely examined by surgeons and only sent to the pathologist on indication. The two main outcomes are oncological safety and potential cost savings of a selective policy. Oncological safety of selective histopathological examination will be assessed by calculating the number of patients in whom a histopathological diagnosis of an appendiceal neoplasm or gallbladder cancer with clinical consequences benefitting the patient would have been missed. A cost analysis will be performed to quantify the potential cost savings. ETHICS AND DISSEMINATION: The study protocol was reviewed by the Institutional Review Board of the Amsterdam UMC, location AMC, which decided that the Dutch Medical Research Involv
- Published
- 2019
19. Safety and cost analysis of selective histopathological examination following appendicectomy and cholecystectomy (FANCY study): protocol and statistical analysis plan of a prospective observational multicentre study
- Author
-
Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., Bemelman, W.A., Bastiaenen, V.P., Corten, B.J., Savornin Lohman, E.A.J. de, Jonge, J de, Kraima, A.C., Swank, H.A., Vliet, J.L. van, Acker, G.J. van, Geloven, A. A. W. van, Hof, K.H. In 't, Koens, L., Reuver, P.R. de, Rossem, C.C. van, Slooter, G.D., Tanis, P.J., Terpstra, V., Dijkgraaf, M.G., and Bemelman, W.A.
- Abstract
Contains fulltext : 215707.pdf (publisher's version ) (Open Access), INTRODUCTION: Routine histopathological examination following appendicectomy and cholecystectomy has significant financial implications and comprises a substantial portion of the pathologists' workload, while the incidence of unexpected pathology is low. The aim of the selective histopathological examination Following AppeNdicectomy and CholecystectomY (FANCY) study is to investigate the oncological safety and potential cost savings of selective histopathological examination based on macroscopic assessment performed by the surgeon. METHODS AND ANALYSIS: This is a Dutch multicentre prospective observational study, in which removed appendices and gallbladders will be systematically assessed by the operating surgeon for macroscopic abnormalities suspicious for malignant neoplasms. After visual inspection and digital palpation of the removed specimen, the operating surgeon will report whether macroscopic abnormalities suspicious for a malignant neoplasm are present, and if he or she believes additional microscopic examination by the pathologist is indicated. Regardless of the surgeon's assessment, all specimens will be sent for histopathological examination. In this way, routine histopathological examination can be compared with a hypothetical situation in which specimens are routinely examined by surgeons and only sent to the pathologist on indication. The two main outcomes are oncological safety and potential cost savings of a selective policy. Oncological safety of selective histopathological examination will be assessed by calculating the number of patients in whom a histopathological diagnosis of an appendiceal neoplasm or gallbladder cancer with clinical consequences benefitting the patient would have been missed. A cost analysis will be performed to quantify the potential cost savings. ETHICS AND DISSEMINATION: The study protocol was reviewed by the Institutional Review Board of the Amsterdam UMC, location AMC, which decided that the Dutch Medical Research Involv
- Published
- 2019
20. Dilemmas for the pathologist in the oncologic assessment of pancreatoduodenectomy specimens
- Author
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Soer, E. (Eline), Brosens, L. (Lodewijk), Vijver, M.J. (Marc ), Dijk, F. (Frederike), Velthuysen, M.L.F. (Loes) van, Fariña-Sarasqueta, A. (Arantza), Morreau, H. (Hans), Offerhaus, J. (Johan), Koens, L. (Lianne), Verheij, J. (Joanne), Soer, E. (Eline), Brosens, L. (Lodewijk), Vijver, M.J. (Marc ), Dijk, F. (Frederike), Velthuysen, M.L.F. (Loes) van, Fariña-Sarasqueta, A. (Arantza), Morreau, H. (Hans), Offerhaus, J. (Johan), Koens, L. (Lianne), and Verheij, J. (Joanne)
- Abstract
A pancreatoduodenectomy specimen is complex, and there is much debate on how it is best approached by the pathologist. In this review, we provide an overview of topics relevant for current clinical practice in terms of gross dissection, and macro- and microscopic assessment of the pancreatoduodenectomy specimen with a suspicion of suspected pancreatic cancer. Tumor origin, tumor size, degree of differentiation, lymph node status, and resection margin status are universally accepted as prognostic for survival. However, different guidelines diverge on important issues, such as the diagnostic criteria for evaluating the completeness of resection. The macroscopic assessment of the site of origin in periampullary tumors and cystic lesions is influenced by the grossing method. Bi-sectioning of the head of the pancreas may offer an advantage in this respect, as this method allows for optimal visualization of the periampullary area. However, a head-to-head comparison of the assessment of clinically relevant parameters, using axial slicing versus bi-sectioning, is not available yet and the gold standard to compare both techniques prospectively might be subject of debate. Further studies are required to validate the various dissection protocols used for pancreatoduodenectomy specimens and their specific value in the assessment of pathological parameters relevant for prognosis.
- Published
- 2018
- Full Text
- View/download PDF
21. Dilemmas for the pathologist in the oncologic assessment of pancreatoduodenectomy specimens
- Author
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Soer, E, Brosens, L, van de Vijver, M, van Dijk, F, van Velthuysen, MLF (M. Loes), Farina-Sarasqueta, A, Morreau, H, Offerhaus, J, Koens, L, Verheij, J, Soer, E, Brosens, L, van de Vijver, M, van Dijk, F, van Velthuysen, MLF (M. Loes), Farina-Sarasqueta, A, Morreau, H, Offerhaus, J, Koens, L, and Verheij, J
- Published
- 2018
22. RCSLenS: A new estimator for large-scale galaxy-matter correlations
- Author
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Buddendiek, A., Schneider, P., Hildebrandt, H., Blake, C., Choi, A., Erben, T., Heymans, C., van Waerbeke, L., Viola, M., Harnois-Deraps, J., Koens, L., Nakajima, R., Buddendiek, A., Schneider, P., Hildebrandt, H., Blake, C., Choi, A., Erben, T., Heymans, C., van Waerbeke, L., Viola, M., Harnois-Deraps, J., Koens, L., and Nakajima, R.
- Abstract
We present measurements of the galaxy bias $b$ and the galaxy-matter cross-correlation coefficient $r$ for the BOSS LOWZ luminous red galaxy sample. Using a new statistical weak lensing analysis of the Red Sequence Cluster Lensing Survey (RCSLenS) we find the bias properties of this sample to be higher than previously reported with $b=2.45^{+0.05}_{-0.05}$ and $r=1.64^{+0.17}_{-0.16}$ on scales between $3'$ and $20'$. We repeat the measurement for angular scales of $20'\leq \vartheta \leq70'$, which yields $b=2.39^{+0.07}_{-0.07}$ and $r=1.24^{+0.26}_{-0.25}$. This is the first application of a data compression analysis using a complete set of discrete estimators for galaxy-galaxy lensing and galaxy clustering. As cosmological data sets grow, our new method of data compression will become increasingly important in order to interpret joint weak lensing and galaxy clustering measurements and to estimate the data covariance. In future studies this formalism can be used as a tool to study the large-scale structure of the Universe to yield a precise determination of cosmological parameters., Comment: 14 pages, 14 figures, accepted for publication in MNRAS
- Published
- 2015
- Full Text
- View/download PDF
23. RCSLenS: A new estimator for large-scale galaxy-matter correlations
- Author
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Buddendiek, A., Schneider, P., Hildebrandt, H., Blake, C., Choi, A., Erben, T., Heymans, C., van Waerbeke, L., Viola, M., Harnois-Deraps, J., Koens, L., Nakajima, R., Buddendiek, A., Schneider, P., Hildebrandt, H., Blake, C., Choi, A., Erben, T., Heymans, C., van Waerbeke, L., Viola, M., Harnois-Deraps, J., Koens, L., and Nakajima, R.
- Abstract
We present measurements of the galaxy bias $b$ and the galaxy-matter cross-correlation coefficient $r$ for the BOSS LOWZ luminous red galaxy sample. Using a new statistical weak lensing analysis of the Red Sequence Cluster Lensing Survey (RCSLenS) we find the bias properties of this sample to be higher than previously reported with $b=2.45^{+0.05}_{-0.05}$ and $r=1.64^{+0.17}_{-0.16}$ on scales between $3'$ and $20'$. We repeat the measurement for angular scales of $20'\leq \vartheta \leq70'$, which yields $b=2.39^{+0.07}_{-0.07}$ and $r=1.24^{+0.26}_{-0.25}$. This is the first application of a data compression analysis using a complete set of discrete estimators for galaxy-galaxy lensing and galaxy clustering. As cosmological data sets grow, our new method of data compression will become increasingly important in order to interpret joint weak lensing and galaxy clustering measurements and to estimate the data covariance. In future studies this formalism can be used as a tool to study the large-scale structure of the Universe to yield a precise determination of cosmological parameters., Comment: 14 pages, 14 figures, accepted for publication in MNRAS
- Published
- 2015
- Full Text
- View/download PDF
24. Verstand op Veilig: de waarde van publieke kennisinstellingen voor de veiligheid van Nederland
- Author
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Blankesteijn, M.L., Faasse, P., Koens, L., van der Meulen, B., Blankesteijn, M.L., Faasse, P., Koens, L., and van der Meulen, B.
- Published
- 2014
25. Verstand op Veilig: de waarde van publieke kennisinstellingen voor de veiligheid van Nederland
- Author
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Blankesteijn, M.L., Faasse, P., Koens, L., van der Meulen, B., Blankesteijn, M.L., Faasse, P., Koens, L., and van der Meulen, B.
- Published
- 2014
26. Vibrations of a columnar vortex in a trapped Bose-Einstein condensate
- Author
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Koens, L, Simula, TP, Martin, AM, Koens, L, Simula, TP, and Martin, AM
- Abstract
We derive a governing equation for a Kelvin wave supported on a vortex line in a Bose-Einstein condensate, in a rotating cylindrically symmetric parabolic trap. From this solution the Kelvin wave dispersion relation is determined. In the limit of an oblate trap and in the absence of longitudinal trapping our results are consistent with previous work. We show that the derived Kelvin wave dispersion in the general case is in quantitative agreement with numerical calculations of the Bogoliubov spectrum and offer a significant improvement upon previous analytical work.
- Published
- 2013
27. The WARPS Survey. VIII. Evolution of the Galaxy Cluster X-ray Luminosity Function
- Author
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Koens, L. A., Maughan, B. J., Jones, L. R., Ebeling, H., Horner, D. J., Perlman, E. S., Phillipps, S., Scharf, C. A., Koens, L. A., Maughan, B. J., Jones, L. R., Ebeling, H., Horner, D. J., Perlman, E. S., Phillipps, S., and Scharf, C. A.
- Abstract
We present measurements of the galaxy cluster X-ray Luminosity Function (XLF) from the Wide Angle ROSAT Pointed Survey (WARPS) and quantify its evolution. WARPS is a serendipitous survey of the central region of ROSAT pointed observations and was carried out in two phases (WARPS-I and WARPS-II). The results here are based on a final sample of 124 clusters, complete above a flux limit of 6.5 10E-15 erg/s/cm2, with members out to redshift z ~ 1.05, and a sky coverage of 70.9 deg2. We find significant evidence for negative evolution of the XLF, which complements the majority of X-ray cluster surveys. To quantify the suggested evolution, we perform a maximum likelihood analysis and conclude that the evolution is driven by a decreasing number density of high luminosity clusters with redshift, while the bulk of the cluster population remains nearly unchanged out to redshift z ~ 1.1, as expected in a low density Universe. The results are found to be insensitive to a variety of sources of systematic uncertainty that affect the measurement of the XLF and determination of the survey selection function. We perform a Bayesian analysis of the XLF to fully account for uncertainties in the local XLF on the measured evolution, and find that the detected evolution remains significant at the 95% level. We observe a significant excess of clusters in the WARPS at 0.1 < z < 0.3 and LX ~ 2 10E42 erg/s compared with the reference low-redshift XLF, or our Bayesian fit to the WARPS data. We find that the excess cannot be explained by sample variance, or Eddington bias, and is unlikely to be due to problems with the survey selection function., Comment: 13 pages, 12 figures, accepted for publication in MNRAS
- Published
- 2012
- Full Text
- View/download PDF
28. Perturbative behavior of a vortex in a trapped Bose-Einstein condensate
- Author
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Koens, L, Martin, AM, Koens, L, and Martin, AM
- Abstract
We derive a set of equations that describe the shape and behaviour of a single perturbed vortex line in a Bose-Einstein condensate. Through the use of a matched asymptotic expansion and a unique coordinate transform a relation for a vortex's velocity, anywhere along the line, is found in terms of the trapping, rotation, and distortion of the line at that location. This relation is then used to find a set of differential equations that give the line's specific shape and motion. This work corrects a previous similar derivation by Anatoly A. Svidzinsky and Alexander L. Fetter [Phys. Rev. A \textbf{62}, 063617 (2000)], and enables a comparison with recent numerical results.
- Published
- 2012
29. The WARPS Survey. VIII. Evolution of the Galaxy Cluster X-ray Luminosity Function
- Author
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Koens, L. A., Maughan, B. J., Jones, L. R., Ebeling, H., Horner, D. J., Perlman, E. S., Phillipps, S., Scharf, C. A., Koens, L. A., Maughan, B. J., Jones, L. R., Ebeling, H., Horner, D. J., Perlman, E. S., Phillipps, S., and Scharf, C. A.
- Abstract
We present measurements of the galaxy cluster X-ray Luminosity Function (XLF) from the Wide Angle ROSAT Pointed Survey (WARPS) and quantify its evolution. WARPS is a serendipitous survey of the central region of ROSAT pointed observations and was carried out in two phases (WARPS-I and WARPS-II). The results here are based on a final sample of 124 clusters, complete above a flux limit of 6.5 10E-15 erg/s/cm2, with members out to redshift z ~ 1.05, and a sky coverage of 70.9 deg2. We find significant evidence for negative evolution of the XLF, which complements the majority of X-ray cluster surveys. To quantify the suggested evolution, we perform a maximum likelihood analysis and conclude that the evolution is driven by a decreasing number density of high luminosity clusters with redshift, while the bulk of the cluster population remains nearly unchanged out to redshift z ~ 1.1, as expected in a low density Universe. The results are found to be insensitive to a variety of sources of systematic uncertainty that affect the measurement of the XLF and determination of the survey selection function. We perform a Bayesian analysis of the XLF to fully account for uncertainties in the local XLF on the measured evolution, and find that the detected evolution remains significant at the 95% level. We observe a significant excess of clusters in the WARPS at 0.1 < z < 0.3 and LX ~ 2 10E42 erg/s compared with the reference low-redshift XLF, or our Bayesian fit to the WARPS data. We find that the excess cannot be explained by sample variance, or Eddington bias, and is unlikely to be due to problems with the survey selection function., Comment: 13 pages, 12 figures, accepted for publication in MNRAS
- Published
- 2012
- Full Text
- View/download PDF
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