University of Alcalá

About: University of Alcalá is a education organization based out in Alcalá de Henares, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 10795 authors who have published 20718 publications receiving 410089 citations. The organization is also known as: University of Alcala & University of Alcala de Henares.

GLOBAL sensitivity analysis, GIS and multi‐criteria evaluation for a sustainable planning of a hazardous waste disposal site in Spain

Abstract: A novel application of Sensitivity Analysis is presented. Useful applications of Global SA (GSA) already exist in the field of numerical modelling. In this paper, we explore the joint use of GSA, Geographical Information Systems (GIS) and Multi‐Criteria Evaluation. In this preliminary case study, 11 factors have been used to find the best place to locate a hazardous waste landfill. Two variance‐based methods (Sobol' and E‐FAST) are used to compute sensitivity indices in order to identify the factors that determine the variance of the model output. The results show that only three factors jointly account for 97% of the output variance. This information is employed to make a simplification of the original model, retaining only these three influential factors. In addition, if the SA is carried out in a pilot area where the spatial properties are similar to those of the whole region, we can infer the results to the whole area. This procedure achieves the goal of the study with an optimized allocation of resou...

Minimal Clinically Important Difference in Quality of Life for Patients With Low Back Pain

Abstract: Study design Multicenter, prospective, cohort study. Objective To estimate the Minimal Clinically Important Difference (MCID) for the physical (PCS) and mental (MCS) component summaries of Short Form SF-12 (SF-12), in patients with low back pain (LBP). Summary of background data Quality of life is one of the core domains recommended to be assessed in patients with LBP. SF-12 is the most widely used instrument for this purpose, but its MCID was unknown. Methods A total of 458 patients with subacute and chronic LBP were consecutively recruited across 21 practices. LBP, referred pain, disability, PCS, and MCS were assessed upon recruitment and 12 months later. Self-reported health status change between baseline and 12 month-assessment, was used as the external criterion. The MCID for SF-12 was estimated following four anchor-based methods; minimal detectable change (MDC); average change (AC); change difference (CD); and receiver operating characteristic curve (ROC), for which the area under the curve (AUC) was calculated. The effect on MCID values of pain duration and baseline scores was assessed. Results Values for PCS were: MDC: 0.56, AC: 2.71, CD: 3.29, and ROC: 1.14. Values for MCS were: MDC: 3.77, AC: 3.54, CD: 1.13, and ROC: 4.23. AUC values were Conclusion Different methods for MCID calculation lead to different results. In patients with subacute and chronic LBP, improvements >3.77 in MCS and >3.29 in PCS, can be considered clinically relevant. MCID is smaller in patients with longer pain duration and better baseline quality of life. Level of evidence 2.

Carbon accumulation in aboveground and belowground biomass and soil of different age native forest plantations in the humid tropical lowlands of Costa Rica

Abstract: Generic or default values to account for biomass and carbon accumulation in tropical forest ecosystems are generally recognized as a major source of errors, making site and species specific data the best way to achieve precise and reliable estimates. The objective of our study was to determine carbon in various components (leaves, branches, stems, structural roots and soil) of single-species plantations of Vochysia guatemalensis and Hieronyma alchorneoides from 0 to 16 years of age. Carbon fraction in the biomass, mean (±standard deviation), for the different pools varied between 38.5 and 49.7% (±3 and 3.8). Accumulated carbon in the biomass increased with the plantation age, with mean annual increments of 7.1 and 5.3 Mg ha -1 year -1 for forest plantations of V. guatemal- ensis and H. alchorneoides, respectively. At all ages, 66.3% (±10.6) of total biomass was found within the aboveground tree components, while 18.6% (±20.9) was found in structural roots. The soil (0-30 cm) contained 62.2 (±13) and 71.5% (±17.1) of the total carbon (biomass plus soil) under V. guatemalensis and H. alchorneoides, respectively. Mean annual increment for carbon in the soil was 1.7 and 1.3 Mg ha -1 year -1 in V. guatemalensis and H. alchorneoides. Allometric equations were constructed to estimate total biomass and carbon in the biomass which had an R 2 aj (adjusted R square) greater than 94.5%. Finally, we compare our results to those that could have resulted from the use of default values, showing how site and species specific data contribute to the overall goal of improving carbon estimates and providing a more reliable account of the mitigation potential of forestry activities on climate change.

Vision-based drowsiness detector for real driving conditions

Abstract: This paper presents a non-intrusive approach for drowsiness detection, based on computer vision. It is installed in a car and it is able to work under real operation conditions. An IR camera is placed in front of the driver, in the dashboard, in order to detect his face and obtain drowsiness clues from their eyes closure. It works in a robust and automatic way, without prior calibration. The presented system is composed of 3 stages. The first one is preprocessing, which includes face and eye detection and normalization. The second stage performs pupil position detection and characterization, combining it with an adaptive lighting filtering to make the system capable of dealing with outdoor illumination conditions. The final stage computes PERCLOS from eyes closure information. In order to evaluate this system, an outdoor database was generated, consisting of several experiments carried out during more than 25 driving hours. A study about the performance of this proposal, showing results from this testbench, is presented.