Global and local sensitivity analysis to improve the understanding of physically-based urban wash-off models from high-resolution laboratory experiments.

Physically-based urban wash-off models are a promising means of studying the transport of finer suspended solids and their associated pollutants during rain events, considering spatial and temporal heterogeneities. This study contributes to the understanding of these models through an in-depth sensitivity analysis to provide the necessary information to simplify the model and deal with parameter identifiability. First, based on twelve tailored high-resolution experiments, the accurate measurement of input variables was used to study the parameters of the Hairsine-Rose sediment transport model through a global sensitivity analysis. Using Standardized Regression Coefficients (SRC) and Extended Fourier Amplitude Sensitivity Test (EFAST) methods, the analysis showed that both the total washed-off mass and the TSS peaks concentration are highly sensitive to the critical mass, which considers the reduction in the detachment of particles when the sediment available decreases and is scattered over the surface. In addition, the rain- and flow-driven detachment parameters were presented as key for smaller and larger sediment particles, respectively. Then, those uncertainties that are associated in field studies with the determination of the model input variables were also considered by conducting a local sensitivity analysis. The initial load of sediment and the mean grain size were seen to be the most important variables, thus underlining the need for very accurate measurements here. Moreover, a precise definition of Harsine-Rose parameters is also necessary to achieve reliable results in order to work on treatment and management techniques to minimize the impact of urban surface contaminants on urban environments.

Estado nutricional, niveles de actividad física y factores de riesgo cardiovascular en estudiantes de la Universidad Santo Tomás / Nutritional status, levels of physical activity and cardiovascular risk factors in college students of Santo Tomas University

Introduction: Non-communicable chronic diseases (NCCD) increase the presence of risk factors (RF) of cardiovascular disease (CVD) in young people. Objective: To analyze the relation among the nutritional status (NS), physical activity (PA) and the prevalence of cardiovascular RF in students from Santo Tomas University in Temuco enrolled in year 2010. Subjects and methods: A cross-sectional descriptive study was carried out; 177 out of 348 students of both genders were chosen as the sample, 32.2% males and 68.8 % females. The age ranged between 18 and 25 years old. Anthropometric and blood pressure measurements, blood samples, PA surveys and obesity backgrounds were taken. The study outcomes helped to estimate the NS, the practice of PA, the prevalence of the different RF. Outcomes: The study showed that the 34.5% of the students present malnutrition by excess, 70.6% are sedentary, and a 9.6% is at risk of CVD by presence of metabolic syndrome (MS). The risk by abdominal obesity reached 53.1%. Parameters which showed significant differences were HDL cholesterol lowered in active students (p= 0.027). When the PA together with BMI variables, triglycerides, LDL cholesterol, glycaemia and blood pressure were analyzed, no significant differences were observed. Conclusions: A high prevalence of malnutrition by excess, for being sedentary and RF of CVD was present with a predominance in female students.

Introducción: Las enfermedades crónicas no transmisibles (ECNT) incrementan la presencia de factores de riesgo (FR) de enfermedad cardiovascular (ECV) en jóvenes. Objetivo: Analizar la relación entre estado nutricional (EN), actividad física (AF) y prevalencia de FR cardiovascular en estudiantes de la Universidad Santo Tomás sede Temuco, ingreso 2010. Sujetos y métodos: Se realizó un estudio descriptivo de corte trasversal; de un total de 348 estudiantes, se obtuvo una muestra de 177 sujetos, de los cuales 32,2% correspondió a hombres y 68,8% a mujeres, la edad fluctuó entre 18 y 25 años. Se realizaron mediciones antropométricas, de presión arterial, muestras sanguíneas, encuestas de AF y antecedentes de morbilidad. Los resultados permitieron estimar el EN, la práctica de AF y la prevalencia de los distintos FR. Resultados: El estudio reveló que 34,5% de los estudiantes presentaban tiene malnutrición por exceso, 70,6% eran sedentarios y 9,6% tenían riesgo de enfermedad cardiovascular por presencia de Síndrome Metabólico (SM); mientras, el riesgo por obesidad abdominal fue de 53,1%. Los parámetros que evidenciaron diferencias significativas fueron el colesterol HDL que se mostró disminuido en los estudiantes activos (p= 0,016) y el colesterol total, que se observó levemente aumentado en los sedentarios (p= 0,027). Al analizar la AF con las variables IMC, triglicéridos, colesterol LDL, glicemia y presión arterial, no se observaron diferencias significativas. Conclusiones: Se observó alta prevalencia de malnutrición por exceso, sedentarismo y factor de riesgo de ECV con predominio en las mujeres.

Trigonometric characteristics of episiotomy and risks for obstetric anal sphincter injuries in operative vaginal delivery.

INTRODUCTION AND HYPOTHESIS: The objective of this study was to investigate the association between the trigonometric properties of episiotomy in operative vaginal delivery (OVD) and obstetric anal sphincter injuries (OASIS). METHODS: The study included 72 primiparous women who had an OVD and episiotomy. Cases (n = 36) had sustained OASIS at birth, while controls (n = 36) had not. The groups were matched for instrumental delivery. The episiotomy scar was identified and its trigonometric characteristics were measured at 8-12 weeks postpartum. Data were analysed using conditional logistic analysis. RESULTS: The angle of episiotomy behaves as a factor associated with anal sphincter injury, so women with a mediolateral episiotomy and an angle greater than 20° have an 87% less risk of having an OASIS (odds ratio 0.13, 95% confidence interval 0.03-0.58). The study showed that scarred episiotomies at 8-12 weeks after OVD with an angle ≤ 20°, depth and distance between the episiotomy and anus ≤ 15 mm, total upper triangle perimeter ≤ 75 mm, para-anal triangle perimeter ≤ 15 mm and areas between scar and midline ≤ 250 mm(2) were significantly associated with higher risk of OASIS. CONCLUSIONS: When a mediolateral episiotomy is performed in OVD the technique has a strong effect on the occurrence of OASIS. Additional research is needed to determine if the optimal technique for mediolateral episiotomies produces less OASIS than deferring the performance of episiotomy.

Overland flow computations in urban and industrial catchments from direct precipitation data using a two-dimensional shallow water model.

This paper presents the experimental validation and the application to a real industrial catchment of a two-dimensional depth-averaged shallow water model used for the computation of rainfall-runoff transformation from direct precipitation data. Instead of using the common approach in flood inundation modelling, which consists in computing the water depth and velocity fields given the water discharge, in this study the rainfall intensity is imposed directly in the model, the surface runoff being generated automatically. The model considers infiltration losses simultaneously with flow simulation. Gullies are also included in the model, although the coupling between the surface runoff and the sewer network is not considered. Experimental validation of the model is presented in several simplified laboratory configurations of urban catchments, in which the surface runoff has been measured for different hyetographs. The application to a real industrial catchment includes a sewer network flow component, which is solved with the SWMM model. The numerical predictions of the discharge hydrograph generated by a 12 hours storm event are compared with field measurements, providing encouraging results.