Relationship between piezometric level and ground deformations measured by means of DInSAR in the Vega Media of the Segura River (Spain)

Differential SAR Interferometry (DInSAR) is a remote sensing method with the well demonstrated ability to monitor geological hazards like earthquakes, landslides and subsidence. Among all these hazards, subsidence involves the settlement of the ground surface affecting wide areas. Frequently, subsidence is induced by overexploitation of aquifers and constitutes a common problem that affects developed societies. The excessive pumping of underground water decreases the piezometric level in the subsoil and, as a consequence, increases the effective stresses with depth causing a consolidation of the soil column. This consolidation originates a settlement of ground surface that must be withstood by civil structures built on these areas. In this paper we make use of an advanced DInSAR approach - the Coherent Pixels Technique (CPT) [1] - to monitor subsidence induced by aquifer overexploitation in the Vega Media of the Segura River (SE Spain) from 1993 to the present. 28 ERS-1/2 scenes covering a time interval of about 10 years were used to study this phenomenon. The deformation map retrieved with CPT technique shows settlements of up to 80 mm at some points of the studied zone. These values agree with data obtained by means of borehole extensometers, but not with the distribution of damaged buildings, well points and basements, because the occurrence of damages also depends on the structural quality of the buildings and their foundations. The most interesting relationship observed is the one existing between piezometric changes, settlement evolution and local geology. Three main patterns of ground surface and piezometric level behaviour have been distinguished for the study zone during this period: 1) areas where deformation occurs while ground conditions remain altered (recent deformable sediments), 2) areas with no deformation (old and non-deformable materials), and 3) areas where ground deformation mimics piezometric level changes (expansive soils). The temporal relationship between deformation patterns and soil characteristics has been analysed in this work, showing a delay between them. Moreover, this technique has allowed the measurement of ground subsidence for a period (1993-1995) where no instrument information was available.

Propagation, structural similarity and image quality

Póster presentado en SPIE Photonics Europe, Brussels, 16-19 April 2012.

Retinal image quality assessment through a visual similarity index

Retinal image quality is commonly analyzed through parameters inherited from instrumental optics. These parameters are defined for ‘good optics’ so they are hard to translate into visual quality metrics. Instead of using point or artificial functions, we propose a quality index that takes into account properties of natural images. These images usually show strong local correlations that help to interpret the image. Our aim is to derive an objective index that quantifies the quality of vision by taking into account the local structure of the scene, instead of focusing on a particular aberration. As we show, this index highly correlates with visual acuity and allows inter-comparison of natural images around the retina. The usefulness of the index is proven through the analysis of real eyes before and after undergoing corneal surgery, which usually are hard to analyze with standard metrics.

Internalization of quality management in service organizations

Purpose – The purpose of this paper is to analyze the internalization of quality management (QM) on the basis of quality certifiable standards – also referred to as meta-standards – in service organizations. More specifically, the paper analyzes the case of the internalization of a quality standard in the Spanish hotel industry. Design/methodology/approach – The paper examines the relationships between the measures of internalization, benefit, QM tools and motivation, using partial least squares in the framework of the structural equation modeling technique. Findings – The results show that the hotels that have internalized the standard to a greater extent are more likely to be driven by internal motivation, develop more QM tools and achieve greater benefits than the hotels with a lower degree of internalization. Originality/value – As previous studies have examined these issues in relation to the internalization of ISO standards, the present study adds to this important stream of research and contributes by advancing the understanding of these issues through the case of a specific standard for the hotel industry.

Indicators of success in the dietary management of overweight and obesity: weight, body fat loss and quality

Concepts: %WL: Percentage of weight loss; %FL: Percentage of fat loss. Objective: evaluate which unit of measurement for weight loss could determine the success or failure of dietary treatment for overweight and obesity. Method: 4,625 consultations carried out on 616 patients in the southeast of Spain from 2006 to 2012. All of the patients were over 25 years of age and suffered from overweight or obesity. The consultations were carried out every fortnight, using the Mediterranean or low-calorie diet. The patients were divided into four groups according to their %WL and %FL. Results: most of the sample consisted of: women; participants between 25-45 years of age; attended consultations for over a month and a half; obese. 80% of the patients obtained a %FL ≥ 5% (15.5 ± 12.8). The groups with a higher %FL obtained significant differences in weight loss (22.6 vs 11.2%, p = 0.000). The multinomial analysis shows significant differences between the groups with the highest %FL and the lowest %WL and %FL: sex (p = 0.006 vs p = 0.005), BMI (p = 0.010 vs p = 0.003) and attendance (p = 0.000 vs p = 0.000). Conclusion: the patients who lost < 5% of fat had higher initial parameters (percentage of weight and fat); most of the sample lost ≥ 5% of fat. This means that the method of personalised dietary treatment results in a high fat loss; fat is an indicator of the quality loss obtained. Recommendations: use the measurement of fat as a complementary unit of measurement to weight loss; establish a limit of 5% to evaluate such loss; and increase this type of research in any method of weight loss.