This paper presents a method for characterizing flow systems in karst aquifers by acquiring quantitative information about the geometric and hydraulic aquifer parameters from spring hydrograph analysis. Numerical sensitivity analyses identified two fundamentally different flow domains, depending on the overall configuration of aquifer parameters. These two domains have been quantitatively characterized by deducing analytical solutions for the global hydraulic response of simple two-dimensional model geometries.During the baseflow recession of mature karst systems, the hydraulic parameters of karst conduits do not influence the drainage of the low-permeability matrix. In this case the drainage process is influenced by the size and hydraulic parameters of the low-permeability blocks alone. This flow condition has been defined as matrix-restrained flow regime (MRFR). During the baseflow recession of early karst systems and fissured systems, as well as the flood recession of mature systems, the recession process depends on the hydraulic parameters and the size of the low-permeability blocks, conduit conductivity and the total extent of the aquifer. This flow condition has been defined as conduit-influenced flow regime (CIFR).Analytical formulae demonstrated the limitations of equivalent models. While equivalent discrete-continuum models of early karst systems may reflect their real hydraulic response, there is only one adequate parameter configuration for mature systems that yields appropriate recession coefficient. Consequently, equivalent discrete-continuum models are inadequate for simulating global response of mature karst systems. The recession coefficient of equivalent porous medium models corresponds to the transition between matrix-restrained and conduit-influenced flow. Consequently, equivalent porous medium models yield corrupted hydrographs both in mature and early systems, and this approach is basically inadequate for modelling global response of karst aquifers.

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Causes of MV after surgery are heterogeneous, vary with time, and have variable impact on the duration of MV.

This prospective study was designed to address the incidence and clinical and histologic characteristics of balanitis xerotica obliterans in a large random pediatric population with phimosis. We investigated 1178 boys who presented consecutively with phimosis between 1991 and 2001. All patients who underwent complete circumcision and surgical specimens were typed histologically as early, intermediate, or late forms of this disorder or as nonspecific chronic inflammation. Patients with balanitis xerotica obliterans were controlled at 1, 6, and 12 months postoperatively, then yearly. Balanitis xerotica obliterans was found in 471 of the 1178 patients (40%), with the highest incidence in boys aged 9 to 11 years (76%). Secondary phimosis occurred in 93% of boys with balanitis xerotica obliterans and in 32% of those without the disorder. In six instances of balanitis xerotica obliterans, meatotomy and in one meatoplasty was performed, as well as circumcision. On histologic evaluation, we found 19% had early, 60% intermediate, and 21% late form of balanitis xerotica obliterans. Glanular lesions disappeared completely within 6 months in 229 out of 231 patients. Our data strongly suggest that the true incidence of childhood balanitis xerotica obliterans is higher than previously assumed. Its incidence peaks in the 9 to 11 years age group, in whom secondary phimosis was almost exclusively caused by balanitis xerotica obliterans.

Optimization of metabolic state prior to major surgery leads to improved surgical outcomes. Nutrition screening protocols should be implemented in the preoperative evaluation, possibly as part of a bundle. Strategies to minimize hyperglycemia and insulin resistance by aggressive preoperative nutrition and carbohydrate loading may promote maintenance of a perioperative anabolic state, improving healing, reducing complications, and shortening the time to recovery of bowel function and hospital discharge. Short courses of preoperative immune-modulating formulas, using combinations of arginine, ω-3 fatty acids, and other nutrients, have been associated with improved surgical outcomes. These immune-modulating nutrients are key elements of metabolic pathways that promote attenuation of the metabolic response to stress and improve both wound healing and immune function. Patients with severe malnutrition and gastrointestinal dysfunction may benefit from preoperative parenteral nutrition. Continuation of feeding through the intraoperative period for severely stressed hypermetabolic patients undergoing nongastrointestinal surgery is another strategy to optimize metabolic state and reduce prolonged nutrition deficits. In this paper, we review the importance of preoperative nutrition and strategies for effective preoperative nutrition optimization.