Earthquake Damage Mapping Techniques Using SAR and Optical Remote Sensing Satellite Data

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Scale Object Selection (SOS) through a hierarchical segmentation by a multi-spectral per-pixel classification

International audienceIn high resolution multispectral optical data, the spatial detail of the images are generally smaller than the dimensions of objects, and often the spectral signature of pixels is not directly representative of classes we are interested in. Thus, taking into account the relations between groups of pixels becomes increasingly important, making object­oriented approaches preferable. In this work several scales of detail within an image are considered through a hierarchical segmentation approach, while the spectral information content of each pixel is accounted for by a per­pixel classification. The selection of the most suitable spatial scale for each class is obtained by merging the hierarchical segmentation and the per­pixel classification through the Scale Object Selection (SOS) algorithm. The SOS algorithm starts processing data from the highest level of the hierarchical segmentation, which has the least amount of spatial detail, down to the last segmentation map. At each segmentation level, objects are assigned to a specific class whenever the percentage of pixels belonging to the latter, according to a pixel­based procedure, exceeds a predefined threshold, thereby automatically selecting the most appropriate spatial scale for the classification of each object. We apply our method to multispectral, panchromatic and pan­sharpened QuickBird images

Anti-asthmatics prescriptions in the paediatric population in the Lazio Region of Italy: association with socio-demographic children’s and physician’s characteristics

  Background Asthma is the most common chronic disease in childhood; inItaly its prevalence is estimated to be 9% in children (0-14 years old). Objective Estimate the use of anti-asthmatics prescriptions in the paediatric population and to evaluate its association with children’s and physician’s characteristics. Methods The study was conducted in 728,830 children 1-14 years old residing in the Lazio region,Central Italy. Individual data on AA (ATC R03) prescriptions during 2009 were used. Prevalence was calculated according to children’s gender, age and area of residence. The association, in terms of rate ratio (RR), between AA prescription with children’s and physicians’ characteristics was estimated by multi level Poisson models. Results Overall, 404,239 AA prescriptions were given to 178,850 (25%) children with the highest frequency in the 1-2 age group (39%). Boys were more likely to receive a prescription than girls. Beclomethasone was the most prescribed active ingredient (34%), followed by salbutamol (24%); 44% of children ³6 years old had only 1 box prescription in the year, 48.9% of these subjects were treated with inhaled corticosteroids alone. Children’s gender, age and area of residence were the major determinants in drug prescription while, as far as physicians’ level,  gender and number of patients in charge were associated to a greater probability of getting an AA prescription. Conclusion Prescription data provide useful information to measure prevalence use and consumption of AA drugs. Variability between age groups as well as differences in doctors’ characteristics suggests that specific strategies to optimise resource use of AA are needed

Towards a 20m global building map from Sentinel-1 SAR Data

This study introduces a technique for automatically mapping built-up areas using synthetic aperture radar (SAR) backscattering intensity and interferometric multi-temporal coherence generated from Sentinel-1 data in the framework of the Copernicus program. The underlying hypothesis is that, in SAR images, built-up areas exhibit very high backscattering values that are coherent in time. Several particular characteristics of the Sentinel-1 satellite mission are put to good use, such as its high revisit time, the availability of dual-polarized data, and its small orbital tube. The newly developed algorithm is based on an adaptive parametric thresholding that first identifies pixels with high backscattering values in both VV and VH polarimetric channels. The interferometric SAR coherence is then used to reduce false alarms. These are caused by land cover classes (other than buildings) that are characterized by high backscattering values that are not coherent in time (e.g., certain types of vegetated areas). The algorithm was tested on Sentinel-1 Interferometric Wide Swath data from five different test sites located in semiarid and arid regions in the Mediterranean region and Northern Africa. The resulting building maps were compared with the Global Urban Footprint (GUF) derived from the TerraSAR-X mission data and, on average, a 92% agreement was obtained.Peer ReviewedPostprint (published version

Did the September 2010 (Darfield) earthquake trigger the February 2011 (Christchurch) event?

We have investigated the possible cause-and-effect relationship due to stress transfer between two earthquakes that occurred near Christchurch, New Zealand, in September 2010 and in February 2011. The Mw 7.1 Darfield (Canterbury) event took place along a previously unrecognized fault. The Mw 6.3 Christchurch earthquake, generated by a thrust fault, occurred approximately five months later, 6 km south-east of Christchurch's city center. We have first measured the surface displacement field to retrieve the geometries of the two seismic sources and the slip distribution. In order to assess whether the first earthquake increased the likelihood of occurrence of a second earthquake, we compute the Coulomb Failure Function (CFF). We find that the maximum CFF increase over the second fault plane is reached exactly around the hypocenter of the second earthquake. In this respect, we may conclude that the Darfield earthquake contributed to promote the rupture of the Christchurch fault

Bias in food intake reporting in children and adolescents with type 1 diabetes: the role of body size, age and gender

An assessment of total daily energy intake is helpful in planning the overall treatment of children with type 1 diabetes (T1D). However, energy intake misreporting may hinder nutritional intervention.Aims: To assess the plausibility of energy intake reporting and the potential role of gender, body mass index (BMI) z-score (z-BMI), disease duration and insulin requirement in energy intake misreporting in a sample of children and adolescents with T1D.Methods: The study included 58 children and adolescents aged 8–16 yr with T1D. Anthropometry, blood pressure and glycated hemoglobin (HbA1c) were measured. Subjects were instructed to wear a SenseWear Pro Armband (SWA) for 3 consecutive days, including a weekend day and to fill out with their parents a weighed dietary record for the same days. Predicted energy expenditure (pEE) was calculated by age and gender specific equations, including gender, age, weight, height and physical activity level (assessed by SWA). The percent reported energy intake (rEI)/pEE ratio was used as an estimate of the plausibility of dietary reporting.Results: Misreporting of food intake, especially under-reporting, was common in children and adolescents with T1D: more than one-third of participants were classified as under- reporters and 10% as over-reporters. Age, z-BMI and male gender were associated with the risk of under-reporting (model R2 = 0.5). Waist circumference was negatively associated with the risk of over-reporting (model R2 = 0.25).Conclusions: Children and adolescents with T1D frequently under-report their food intake. Age, gender and z-BMI contribute to identify potential under-reporters

The Mw 7.9Wenchuan (China) Earthquake: exploring the role of crustal heterogeneities from finite element analysis of DInSAR coseismic deformation

A destructive (Mw 7.9) earthquake struck the Sichuan province (China) on May 12, 2008. The seismic event, the largest in China in more than three decades and referred as the Wenchuan earthquake, ruptured approximately 280 km of the Yingxiu-Beichuan fault and about 70 km of the Guanxian-Anxian fault. Surface effects were suffered over a wide epicentral area (about 300 km E-W and 250 km N-S). The huge earthquake took place within the context of long term uplift of the Longmen Shan range in eastern Tibet. The Longmen Shan fault zone is the main tectonic boundary between the Sichuan basin and eastern Tibet and is characterized by a large topographic relief (from 500m a.s.l. to more than 4000m) and large variations in rheological properties. The coseismic deformation is imaged by a set of ALOS-PALSAR L-band SAR interferograms. We use an unprecedented high number of data (25 frames from 6 adjacent tracks) to encompass the entire coseismic area. The resulting mosaic of differential interferograms covers an overall area of about 340 km E-W and 240 km N-S. The complex geophysical context of Longmen Shan and the variations of the fault geometry along its length can be better handled by means of numerical methods. The fault geometry is constrained by inversions of geodetic data and by taking into account the geological features of eastern Tibet and Sichuan basin. As a result, we build a Finite Element (FE) model consisting of two non planar faults embedded in a non-homogeneous medium with real topography of the area. We develop a procedure to perform inversions of DInSAR data based on FE computed Green functions of the surface displacement field. We retrieve a complex slip distribution on the fault segments in a heterogeneous medium with realistic surface topography

An evaluation of the potential of Sentinel 1 for improving flash flood predictions via soil moisture–data assimilation

open8siThe assimilation of satellite-derived soil moisture estimates (soil moisture–data assimilation, SM–DA) into hydrological models has the potential to reduce the uncertainty of streamflow simulations. The improved capacity to moni- tor the closeness to saturation of small catchments, such as those characterizing the Mediterranean region, can be exploited to enhance flash flood predictions. When compared to other microwave sensors that have been exploited for SM– DA in recent years (e.g. the Advanced SCATterometer – AS- CAT), characterized by low spatial/high temporal resolution, the Sentinel 1 (S1) mission provides an excellent opportu- nity to monitor systematically soil moisture (SM) at high spatial resolution and moderate temporal resolution. The aim of this research was thus to evaluate the impact of S1-based SM–DA for enhancing flash flood predictions of a hydro- logical model (Continuum) that is currently exploited for civil protection applications in Italy. The analysis was car- ried out in a representative Mediterranean catchment prone to flash floods, located in north-western Italy, during the time period October 2014–February 2015. It provided some important findings: (i) revealing the potential provided by S1- based SM–DA for improving discharge predictions, espe- cially for higher flows; (ii) suggesting a more appropriate pre-processing technique to be applied to S1 data before the assimilation; and (iii) highlighting that even though high spa- tial resolution does provide an important contribution in a SM–DA system, the temporal resolution has the most crucial role. S1-derived SM maps are still a relatively new product and, to our knowledge, this is the first work published in an international journal dealing with their assimilation within a hydrological model to improve continuous streamflow simulations and flash flood predictions. Even though the reported results were obtained by analysing a relatively short time pe- riod, and thus should be supported by further research activ- ities, we believe this research is timely in order to enhance our understanding of the potential contribution of the S1 data within the SM–DA framework for flash flood risk mitigation.openCenci, Luca; Pulvirenti, Luca; Boni, Giorgio; Chini, Marco; Matgen, Patrick; Gabellani, Simone; Squicciarino, Giuseppe; Pierdicca, NazzarenoCenci, Luca; Pulvirenti, Luca; Boni, Giorgio; Chini, Marco; Matgen, Patrick; Gabellani, Simone; Squicciarino, Giuseppe; Pierdicca, Nazzaren

Can Computed Tomography Colonography Replace Optical Colonoscopy in Detecting Colorectal Lesions?: State of the Art

: Colorectal cancer is an important cause of morbidity and mortality worldwide. Optical colonoscopy (OC) is widely accepted as the reference standard for the screening of colorectal polyps and cancers, and computed tomography colonography (CTC) is a valid alternative to OC. The purpose of this review was to assess the diagnostic accuracy of OC and CTC for colorectal lesions. A literature search was performed in PubMed, Embase, and Cochrane Library, and 18 articles were included. CTC has emerged in recent years as a potential screening examination with high accuracy for the detection of colorectal lesions. However, the clinical application of CTC as a screening technique is limited because it is highly dependent on the size of the lesions and has poor performance in detecting individual lesions <5 mm or flat lesions, which, although rarely, can have a malignant potential