Channel restoration design for meandering rivers

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Assessment of hydrodynamic simulation results for eco-hydraulic and eco-hydrological applications: a spatial semivariance approach

Output from a three-dimensional numerical flow model (SSIIM) is used in conjunction with high-resolution topographic and velocity data to assess such models for eco-hydraulic applications in river channel design and habitat appraisal. A new methodology for the comparison between field measurement and model output is detailed. This involves a comparison between conventional goodness-of-fit approaches applied to a spatially structured (riffle and pool) sample of model and field data, and a relaxation method based upon the spatial semivariance of model/field departures. Conventional assessment indicates that the model predicts point-by-point velocity characteristics on a 0·45 m mesh to within ±0·1 m s-1 over 80% of the channel area at low flow, and 50% of the area at high in-bank flow. When a relative criterion of model fit is used, however, the model appears to perform less well: 60-70% of channel area has predicted velocities that depart from observed velocities by more than 10%. Regression analysis of observed and predicted velocities gives more cause for optimism, but all of these conventional indicators of goodness of fit neglect important spatial characteristics of model performance. Spatial semivariance is a means of supplementing model appraisal in this respect. In particular, using the relaxation approach, results are greatly improved: at a high in-bank flow, the model results match field measurements to within 0·1 m s-1 for more than 95% of the total channel area, provided that model and field comparisons are allowed within a radius of approximately 1 m from the original point of measurement. It is suggested that this revised form of model assessment is of particular relevance to eco-hydraulic applications, where some degree of spatial and temporal dynamism (or uncertainty) is a characteristic. The approach may also be generalized to other environmental science modelling applications where the spatial attributes of model fits are of interest

The effect of a liberal approach to glucose control in critically ill patients with type 2 diabetes: a multicenter, parallel-group, open-label randomized clinical trial

Rationale: Blood glucose concentrations affect outcomes in critically ill patients, but the optimal target blood glucose range in those with type 2 diabetes is unknown. Objectives: To evaluate the effects of a “liberal” approach to targeted blood glucose range during ICU admission. Methods: This mutlicenter, parallel-group, open-label randomized clinical trial included 419 adult patients with type 2 diabetes expected to be in the ICU on at least three consecutive days. In the intervention group intravenous insulin was commenced at a blood glucose >252 mg/dl and titrated to a target range of 180–252 mg/dl. In the comparator group insulin was commenced at a blood glucose >180 mg/dl and titrated to a target range of 108–180 mg/dl. The primary outcome was incident hypoglycemia (<72 mg/dl). Secondary outcomes included glucose metrics and clinical outcomes. Measurements and Main Results: By Day 28, at least one episode of hypoglycemia occurred in 10 of 210 (5%) patients assigned the intervention and 38 of 209 (18%) patients assigned the comparator (incident rate ratio, 0.21 [95% confidence interval (CI), 0.09 to 0.49]; P < 0.001). Those assigned the intervention had greater blood glucose concentrations (daily mean, minimum, maximum), less glucose variability, and less relative hypoglycemia (P < 0.001 for all comparisons). By Day 90, 62 of 210 (29.5%) in the intervention and 52 of 209 (24.9%) in the comparator group had died (absolute difference, 4.6 percentage points [95% CI, −3.9% to 13.2%]; P = 0.29). Conclusions: A liberal approach to blood glucose targets reduced incident hypoglycemia but did not improve patient-centered outcomes. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN 12616001135404)