Nonlinear Control of pH System for Change Over Titration Curve

Wiener model based nonlinear controller for a pH process efficiently tackles the variations in gain. However, the controller performance deteriorates for significant change over titration curve (i.e. when the nature of the feed stream switches from a weak acid to a strong acid). To improve the performance of this controller, a nonlinear cascade controller is proposed. The nonlinear cascade structure consists of a Wiener model based nonlinear P controller in the inner loop and a linear PI controller in the outer loop. The proposed strategy is simulated for switch over titration curve from a weak acid – strong base system to strong acid – strong base system and then back to the weak acid – strong base system. The performance of the nonlinear cascade controller is compared with that of single loop Wiener model based PI controller and linear cascade (P-PI) controller

Cost-effectiveness analysis of 3-D computerized tomography colonography versus optical colonoscopy for imaging symptomatic gastroenterology patients.

BACKGROUND: When symptomatic gastroenterology patients have an indication for colonic imaging, clinicians have a choice between optical colonoscopy (OC) and computerized tomography colonography with three-dimensional reconstruction (3-D CTC). 3-D CTC provides a minimally invasive and rapid evaluation of the entire colon, and it can be an efficient modality for diagnosing symptoms. It allows for a more targeted use of OC, which is associated with a higher risk of major adverse events and higher procedural costs. A case can be made for 3-D CTC as a primary test for colonic imaging followed if necessary by targeted therapeutic OC; however, the relative long-term costs and benefits of introducing 3-D CTC as a first-line investigation are unknown. AIM: The aim of this study was to assess the cost effectiveness of 3-D CTC versus OC for colonic imaging of symptomatic gastroenterology patients in the UK NHS. METHODS: We used a Markov model to follow a cohort of 100,000 symptomatic gastroenterology patients, aged 50 years or older, and estimate the expected lifetime outcomes, life years (LYs) and quality-adjusted life years (QALYs), and costs (£, 2010-2011) associated with 3-D CTC and OC. Sensitivity analyses were performed to assess the robustness of the base-case cost-effectiveness results to variation in input parameters and methodological assumptions. RESULTS: 3D-CTC provided a similar number of LYs (7.737 vs 7.739) and QALYs (7.013 vs 7.018) per individual compared with OC, and it was associated with substantially lower mean costs per patient (£467 vs £583), leading to a positive incremental net benefit. After accounting for the overall uncertainty, the probability of 3-D CTC being cost effective was around 60 %, at typical willingness-to-pay values of £20,000-£30,000 per QALY gained. CONCLUSION: 3-D CTC is a cost-saving and cost-effective option for colonic imaging of symptomatic gastroenterology patients compared with OC

Imaging features of rare mesenychmal liver tumours: beyond haemangiomas.

Tumours arising from mesenchymal tissue components such as vascular, fibrous and adipose tissue can manifest in the liver. Although histopathology is often necessary for definitive diagnosis, many of these lesions exhibit characteristic imaging features. The radiologist plays an important role in suggesting the diagnosis, which can direct appropriate immunohistochemical staining at histology. The aim of this review is to present clinical and imaging findings of a spectrum of mesenchymal liver tumours such as haemangioma, epithelioid haemangioendothelioma, lipoma, PEComa, angiosarcoma, inflammatory myofibroblastic tumour, solitary fibrous tumour, leiomyoma, leiomyosarcoma, Kaposi sarcoma, mesenchymal hamartoma, undifferentiated embryonal sarcoma, rhabdomyosarcoma and hepatic metastases. Knowledge of the characteristic features of these tumours will aid in guiding the radiologic diagnosis and appropriate patient management

CT colonography followed by elective surgery in patients with acute diverticulitis : a radiological-pathological correlation study

Purpose: To perform a radiologic-pathologic correlation analysis of sigmoid colon in patients undergoing pre-operative CT Colonography (CTC) after an episode of acute diverticulitis (AD). Methods: Fifty-nine consecutive patients (31/28 M/F; 58 \ub1 13 years) underwent CTC 55 \ub1 18 days after AD, 8 \ub1 4 weeks before surgery. Thirty-seven patients (63%) underwent conventional abdominal CT at time of AD. An experienced blinded radiologist retrospectively analyzed all images: disease severity was graded according to the Ambrosetti classification on conventional CT and according to the diverticular disease severity score (DDSS) on CTC. A GI pathologist performed a dedicated analysis, evaluating the presence of acute and chronic inflammation, and fibrosis, using 0\u20133 point scale for each variable. Results: Of 59 patients, 41 (69%) had at least one previous AD episode; twenty-six patients (44%) had a complicated AD. DDSS was mild-moderate in 34/59 (58%), and severe in 25/59 (42%). All patients had chronic inflammation, while 90% had low-to-severe fibrosis. Patients with moderate/severe fibrosis were older than those with no/mild fibrosis (61 \ub1 13 versus 54 \ub1 13). We found a significant correlation between DDSS and chronic inflammation (p = 0.004), as well as DDSS and fibrosis (p = 0.005). Furthermore, fibrosis was correlated with complicated acute diverticulitis (p = 0.0.27), and with age (p = 0.067). At multivariate analysis, complicated diverticulitis was the best predictor of fibrosis (odds ratio 4.4). Patient age and DDSS were other independent predictors. Conclusion: DDSS-based assessment on preoperative CTC was a good predictor of chronic colonic inflammation and fibrosis. In addition, the presence of complicated diverticulitis on CT during the acute episode was most predictive of fibrosis

The dynamics of internalised and extrinsic motivation in the ethical decision making of small business owners

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.We investigate the ethical behaviour of small business owners by focusing on individuals’ motivations to comply with tax obligations. In a study of 330 small business owners, we assess the role of internalised motivation to pay taxes versus extrinsic motivation in driving tax compliance. First, we find that internalised and extrinsic motivation have distinct predictors. Internalised motivation is related to strong personal moral norms to comply and a sense that the fiscal system is fair. Extrinsic motivation is related to perceptions that penalties are severe, that checks are likely, and is associated with a perceived lack of tax knowledge. Second, we find that, when considered together, internalised motivation but not extrinsic motivation predicts self-reported tax compliance. Third, we test the undermining hypothesis by which the presence of extrinsic motivation may crowd out the positive effect of internalised motivation. We find evidence of a motivation crowding effect only at very high levels of extrinsic motivation. We discuss avenues for further integration of motivation theory in research on tax compliance behaviour, and more generally the study of regulatory compliance and ethical behaviour in business settings.This work was conducted in the Tax Administration Research Centre at the University of Exeter, jointly funded by the Economic and Social Research Council, HM Revenue & Customs and HM Treasury (grant no. ES/K005944/1); we are very grateful to our funders for their support

Thoracic and Lumbar Vertebral Bone Mineral Density Changes in a Natural Occurring Dog Model of Diffuse Idiopathic Skeletal Hyperostosis

Ankylosing spinal disorders can be associated with alterations in vertebral bone mineral density (BMD). There is however controversy about vertebral BMD in patients wuse idiopathic skeletal hyperostosis (DISH). DISH in Boxer dogs has been considered a natural occurring disease model for DISH in people. The purpose of this study was to compare vertebral BMD between Boxers with and without DISH. Fifty-nine Boxers with (n=30) or without (n=29) DISH that underwent computed tomography were included. Vertebral BMD was calculated for each thoracic and lumbar vertebra by using an earlier reported and validated protocol. For each vertebral body, a region of interest was drawn on the axial computed tomographic images at three separate locations: immediately inferior to the superior end plate, in the middle of the vertebral body, and superior to the inferior end plate. Values from the three axial slices were averaged to give a mean Hounsfield Unit value for each vertebral body. Univariate statistical analysis was performed to identify factors to be included in a multivariate model. The multivariate model including all dogs demonstrated that vertebral DISH status (Coefficient 24.63; 95% CI 16.07 to 33.19; p <0.001), lumbar vertebrae (Coefficient -17.25; 95% CI -23.42 to -11.09; p < 0.01), and to a lesser extent higher age (Coefficient -0.56; 95% CI -1.07 to -0.05; p = 0.03) were significant predictors for vertebral BMD. When the multivariate model was repeated using only dogs with DISH, vertebral DISH status (Coefficient 20.67; 95% CI, 10.98 to 30.37; p < 0.001) and lumbar anatomical region (Coefficient -38.24; 95% CI, -47.75 to -28.73; p < 0.001) were again predictors for vertebral BMD but age was not. The results of this study indicate that DISH can be associated with decreased vertebral BMD. Further studies are necessary to evaluate the clinical importance and pathophysiology of this finding