Nonlocal Total Variation Using the First and Second Order Derivatives and Its Application to CT Image Reconstruction.

We propose a new class of nonlocal Total Variation (TV), in which the first derivative and the second derivative are mixed. Since most existing TV considers only the first-order derivative, it suffers from problems such as staircase artifacts and loss in smooth intensity changes for textures and low-contrast objects, which is a major limitation in improving image quality. The proposed nonlocal TV combines the first and second order derivatives to preserve smooth intensity changes well. Furthermore, to accelerate the iterative algorithm to minimize the cost function using the proposed nonlocal TV, we propose a proximal splitting based on Passty's framework. We demonstrate that the proposed nonlocal TV method achieves adequate image quality both in sparse-view CT and low-dose CT, through simulation studies using a brain CT image with a very narrow contrast range for which it is rather difficult to preserve smooth intensity changes.

Association between Parity and Blood Pressure in Korean Women: Korean National Health and Nutrition Examination Survey, 2010-2012.

BACKGROUND: Pregnancy considerably alters cardiovascular dynamics, and thereby affects the transition of blood pressure after delivery in women. We aimed to analyze the association between parity and blood pressure in Korean adult women. METHODS: We included 8,890 women who participated in Korean National Health and Nutrition Examination Survey between 2010 and 2012. We divided the population according to the menopause status and analyzed the association between parity and blood pressure by using multiple regression analysis, and on hypertension, by using logistic regression analysis. RESULTS: Systolic and diastolic blood pressures were significantly associated with parity in premenopausal women (ß=-0.091 [P<0.001] and ß=-0.069 [P<0.001], respectively). In the analysis that excluded women receiving antihypertensive medication, the systolic and diastolic blood pressure of postmenopausal women were significantly associated with parity (ß=-0.059 [P=0.022] and ß=-0.054 [P=0.044], respectively). Parity was found to prevent hypertension after adjustment for confounders in postmenopausal women (odds ratio, 0.55; 95% confidence interval, 0.310-0.985). CONCLUSION: We found that parity prevented hypertension in Korean women.