19 research outputs found

    Using DEM to create a CPT based method to estimate the installation requirements of rotary installed piles in sand

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    Deep foundations maybe used in a range of soil types where significant foundation resistance is required but their installation is often associated with disturbance due to noise and vibration. Greater restrictions on use in urban and offshore environments is now commonplace. Screw piles and rotary jacked straight shafted piles are two potential methods of silent piling that could be used as alternative foundation solution, but the effects of certain geometric and installation properties such as installation pitch i.e. the ratio between vertical displacement and rotation, on the required installation torque and force in sand are not well understood. In this paper the effects of installation pitch and base geometry on the installation requirements of a straight shafted pile are simulated in 3D using the discrete element method (DEM). The installation requirements of straight shafted piles into sand have been validated against centrifuge testing, in three different relative densities. The DEM shows reductions in installation force can be achieved by increasing the installation pitch or including a conical tip. An existing cone penetration test (CPT) based prediction method for installation requirements has been improved to include the effects of installation pitch and base geometry for rotary installed piles in sand.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

    18FDG uptake in oesophageal adenocarcinoma: linking biology and outcome

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    PURPOSE: Variable uptake of 18FDG has been noticed in positron emission tomography (PET) studies of patients with oesophageal adenocarcinoma. The aim of the present study was to investigate biological parameters involved in 18FDG uptake in oesophageal adenocarcinoma for selection of patients with increased 18FDG uptake and prediction of prognostic value of 18FDG PET. PATIENTS AND METHODS: Preoperative PET scans were performed in 26 patients with histologically proven oesophageal adenocarcinoma. 18FDG uptake was semiquantitatively measured by SUV(BSAg. )Tumour sections were stained by immunohistochemistry for angiogenic markers (VEGF, CD31), glucose transporter-1 (Glut-1), hexokinase (HK) isoforms, for proliferation marker (Ki67), for macrophage marker (CD68) and for apoptosis marker (cleaved caspase-3). Cell densities, differentiation grade, degree of necrosis and mucus, T-stage and tumour size were assessed. In addition follow-up was analysed. RESULTS: No association was found between 18FDG uptake and angiogenic markers. In contrast, a significant correlation was found between 18FDG uptake and Glut-1 expression. No correlations were found between 18FDG uptake and HK isoforms, Ki67 or cleaved caspase-3. Also, no correlations were found between 18FDG uptake and cell density, differentiation grade, CD68, mucus and necrosis. However, there was a significant correlation between 18FDG uptake and tumour size and between 18FDG uptake and tumour recurrence. CONCLUSIONS: Glut-1 expression and tumour size seem parameters associated with 18FDG uptake in patients with biopsy proven oesophageal adenocarcinoma, and may be used to select oesophageal cancer patients in whom 18FDG-PET is of diagnostic value and may predict disease outcom

    The potential of imaging techniques as a screening tool for colorectal cancer: a cost-effectiveness analysis

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    Imaging may be promising for colorectal cancer (CRC) screening, since it has test characteristics comparable with colonoscopy but is less invasive. We aimed to assess the potential of CT colonography (CTC) and MR colonography (MRC) in terms of (cost-effectiveness) using the Adenoma and Serrated pathway to Colorectal CAncer model. We compared several CTC and MRC strategies with 5- or 10-yearly screening intervals with no screening, 10-yearly colonoscopy screening and biennial faecal immunochemical test (FIT) screening. We assumed trial-based participation rates in the base-case analyses and varied the rates in sensitivity analyses. Incremental lifetime costs and health effects were estimated from a healthcare perspective. The health gain of CTC and MRC was similar and ranged from 0.031 to 0.048 life-year gained compared with no screening, for 2-5 screening rounds. Lifetime costs per person for MRC strategies were €60-110 higher than those for CTC strategies with an equal number of screening rounds. All imaging-based strategies were cost-effective compared with no screening. FIT screening was the dominant screening strategy, leading to most LYG and highest cost-savings. Compared with three rounds of colonoscopy screening, CTC with five rounds was found to be cost-effective in an incremental analysis of imaging strategies. Assumptions on screening participation have a major influence on the ordering of strategies in terms of costs and effects. CTC and MRC have potential for CRC screening, compared with no screening and compared with three rounds of 10-yearly colonoscopy screening. When taking FIT screening as the reference, imaging is not cost-effective. Participation is an important driver of effectiveness and cost estimates. This is the first study to assess the cost-effectiveness of MRC screening for CR

    Long-Term Impact of the Dutch Colorectal Cancer Screening Program on Cancer Incidence and Mortality-Model-Based Exploration of the Serrated Pathway

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    We aimed to predict the long-term colorectal cancer incidence, mortality, and colonoscopy demand of the recently implemented Dutch colorectal cancer screening program. The Adenoma and Serrated pathway to Colorectal Cancer model was set up to simulate the Dutch screening program consisting of biennial fecal immunochemical testing combined with the new Dutch surveillance guidelines, between 2014 and 2044. The impact of screening and surveillance was evaluated under three sets of natural history assumptions differing in the contribution of the serrated pathway to colorectal cancer incidence. In sensitivity analyses, other assumptions concerning the serrated pathway were varied. Model-predicted outcomes were yearly colorectal cancer incidence, mortality, and colonoscopy demand per year. Assuming an aging population, colorectal cancer incidence under 30 years of screening is predicted to decrease by 35% and 31% for a contribution of 0% and 30% of the serrated pathway to colorectal cancer, respectively. For colorectal cancer mortality, reductions are 47% and 45%. In 2044, 110,000 colonoscopies will be required annually assuming no contribution of the serrated pathway (27 per 1,000 individuals in the screening age range). Including the serrated pathway influences predicted screening effectiveness if serrated lesions are neither detected nor treated at colonoscopy, and/or if colorectal cancers arising from serrated lesions have substantially lower survival rates than those arising from adenomas. The Dutch screening program will markedly decrease colorectal cancer incidence and mortality but considerable colonoscopy resources will be required. Predictions of long-term screening effectiveness are preferably based on both pathways to colorectal cancer to transparently describe the impact of uncertainties regarding the serrated pathway on long-term prediction

    Pla2g2a Attenuates Colon Tumorigenesis in Azoxymethane-Treated C57BL/6 Mice; Expression Studies Reveal Pla2g2a Target Genes and Pathways

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    Background: The group IIA secretory phospholipase A2 gene, Pla2g2a, confers resistance to intestinal tumorigenesis in the ApcMin/+ mouse model. However, it is unclear how Pla2g2a exerts its tumor-suppressive effects and whether its mode of action depends on Apc-germline mutations
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