In recent years, different systems have been developed in order to improve the dynamic behaviour of railway vehicles when passing through turnouts. Some of these improvements consist in varying the geometry of the switch itself and including moveable crossing vees. It is worth mentioning that they are designed by taking a certain wheel profile into consideration, i.e. it is assumed that the wheel profile does not change.The objective of the current study is to determine the influence that the turnout design has on vehicle dynamics, as well as the influence that the variability in wheel profiles can have on the effectiveness of the different systems.In order to do this, the MBS software Simpack was used to model one vehicle with two different turnouts and four different profiles. The results show that the geometrical design of the turnout has a critical influence on the vehicle/ turnout. We also concluded that the wheel profile does not have a significant influence when the vehicle passes through turnouts.
Background
Liver transplant recipients have an increased incidence of malignancies, but it is unclear whether they have a higher risk of colorectal cancer.
Aim
To investigate whether liver transplant recipients have an increased risk of developing colorectal adenomas (a surrogate marker of colorectal cancer risk).
Patients and methods
One hundred thirty‐nine liver transplant recipients (excluding primary sclerosing cholangitis) who underwent a colonoscopy and polypectomy before and after transplantation, and 367 nontransplanted patients who underwent a colonoscopy for colorectal cancer screening and a second colonoscopy later were retrospectively studied. The risks of incident colorectal adenomas and high‐risk adenomas (advanced or multiple adenomas or carcinomas) were compared between both cohorts.
Results
Incident colorectal adenomas were found in 40.3% of the transplanted patients and 30.0% of the nontransplanted patients (15.1% and 5.5%, respectively, had high‐risk adenomas). After adjusting for age, sex, presence of adenomas in the baseline endoscopy, and interval between colonoscopies, transplant recipients showed a higher risk of developing colorectal adenomas (OR: 1.61; 95% CI: 1.05‐2.47; p = .03) and high‐risk adenomas (OR: 2.87; 95% CI: 1.46‐5.65; p = .002).
Conclusions
Our results suggest that liver transplant recipients have an increased risk of developing colorectal adenomas and lesions with high risk of colorectal cancer.
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