Recently, debris flow has occurred so frequently due to abnormal heavy rainfall. Although various studies have been conducted to simulate the topographic behavior of debris flow, geometric effect such as the shapes of slope side has been insufficient. In this study, simulations were conducted with FLO-2D, the commercial software to be recommended by FEMA to simulate debris flow. And target geometries are selected as flatbed, square shape, trapezoidal shape and V-shape. Firstly FLO-2D was verified by the comparison with USGS debris flow experiments (Iverson, 2010). The comparisons showed good agreements in term of the velocity range and the propagation length of debris flows. Furthermore, the concept of HAZUS-HM risk analysis was used to assess the vulnerabilities of the structures by the impact of the debris flow. Simulated results were confirmed debris flow behavior to be changed due to the geometry type. Behavior of debris flows were analyzed according to the maximum depth, velocity, propagation length and vulnerabilities of the structures by the debris flow. This study would be practical to provide quantitatively the spatial distribution of hazard caused by debris flow.

No abstract

End-stage renal disease (ESRD) is a multifactorial disease linked to socioeconomic status and associated with worse surgical outcomes. We explore intraoperative and postoperative outcomes in patients with cholecystitis undergoing laparoscopic cholecystectomy (LC). The Nationwide Inpatient Sample from 2005 to 2012 was used to identify patients undergoing LC for cholecystitis using ICD-9 codes. Outcomes of interest were mortality, common bile duct injury, conversion to open, intraoperative complications, postoperative complications, length of stay (LOS), and total charge. Univariate analysis was performed using t test for continuous variables and chi-squared test for categorical variables. Multivariable models were created that adjusted for age, demographics, year of admission, comorbidities, and presence of ESRD. Of 225,058 patients that underwent LC, 2,115 had ESRD. On univariate analysis, the ESRD cohort had a higher incidence of mortality and complications: intraoperative, mechanical wound, respiratory, cardiovascular, and postoperative infections. ESRD patients had higher median LOS and total charge. Multi-variate analysis showed ESRD as an independent risk factor for mortality, mechanical wound complications, and intraoperative complications. Negative binomial regression analysis showed that ESRD patients had LOS 50.4 per cent longer than non-ESRD patients. Linear regression analysis showed that, after adjustment, ESRD patients had total charge 6.82 per cent higher than non-ESRD patients. In this large retrospective analysis, we find that after adjusting for clinical, socioeconomic, and demographic variables, ESRD is an independent risk factor for increased mortality, intraoperative complications, mechanical wound complications, increased LOS, and cost for patients undergoing LC. Prospective studies exploring risk optimization strategies for patients with ESRD are warranted.

The amount of released water (discharge) in a levee breach is a primary input variable to establish an emergency action plan for the area next to the levee. However, although several studies have been conducted, there is still no widely applicable discharge coefficient formula; this needs to be known to estimate discharge amount through an opening caused by a levee breach. Sometimes, the discharge coefficient developed for a sharp crested side weir is used to rate the discharge, but, in case of a levee breach, the resulting geometry and flow types are similar to that over a broad crested weir. Thus, in this study, two different openings—rectangular and trapezoidal shape—are constructed in the center of a levee at a height of 0.6m to replicate levee breach scenarios, and the effect of two different approach flow types—the river type approach and reservoir type approach—are explored to suggest a discharge coefficient formula applicable for discharge rating for a levee breach. The results show that the ratio of head above the bottom of an opening and the opening width is a key variable for calculating the discharge coefficient of a reservoir type, but the approach Froude number should also be considered for a river type approach. The measured data are used to improve rating equations and will be useful in the future to validate computational fluid dynamics simulations of wave propagation during levee failure into the inundation area.