9,637 research outputs found

    Generic model for experimenting and using a family of classifiers systems: description and basic applications.

    No full text
    International audienceClassifiers systems are tools adapted to learn interactions between autonomous agents and their environments. However, there are many kinds of classifiers systems which differ in subtle technical ways. This article presents a generic model (called GEMEAU) that is common to the major kinds of classifiers systems. GEMEAU was developed for different simple applications which are also described

    A 20-year experience with surgical management of true and false internal carotid artery aneurysms

    Get PDF
    Aim of the study: The aim of this study was to retrospectively analyse early and late results of surgical management of internal carotid artery (ICA) true and false aneurysms in a single-centre experience. Materials and methods: From January 1988 to December 2011, 50 consecutive interventions for ICA aneurismal disease were performed; interventions were performed for true ICA aneurysm in 19 cases (group 1) and for ICA post-carotid endarterectomy (CEA) pseudo-aneurysm in the remaining 31 (group 2). Early results (<30 days) were evaluated in terms of mortality, stroke and cranial nerves' injury and compared between the two groups with χ2 test. Follow-up results (stroke free-survival, freedom from ICA thrombosis and reintervention) were analysed with Kaplan-Meier curves and compared with log-rank test. Results: All the patients in group 1 had open repair of their ICA aneurysm; in group 2 open repair was performed in 30 cases, while three patients with post-CEA aneurysm without signs of infection had a covered stent placed. There were no perioperative deaths. Two major strokes occurred in group 1 and one major stroke occurred in group 2 (p = 0.1). The rates of postoperative cranial nerve injuries were 10.5% in group 1 and 13% in group 2 (p = 0.8). Median duration of follow-up was 60 months (range 1-276). Estimated 10-year stroke-free survival rates were 64% in group 1 and 37% in group 2 (p = 0.4, log rank 0.5); thrombosis-free survival at 10 years was 66% in group 1 and 34% in group 2 (p = 0.2, log rank 1.2), while the corresponding figures in terms of reintervention-free survival were 68% and 33%, respectively (p = 0.2, log rank 1.8). Conclusions: Surgical treatment of ICA aneurismal disease provided in our experience satisfactory early and long-term results, without significant differences between true and false aneurysms. In carefully selected patients with non-infected false aneurysm, the endovascular option seems to be feasible.© 2012 European Society for Vascular Surgery

    Endovascular Treatment of Aorto-iliac Aneurysms: Four-year Results of Iliac Branch Endograft

    Get PDF
    Introduction: The aim of this report was to analyse early and mid-term outcomes of endovascular treatment (endovascular aneurysm repair, EVAR) for aorto-iliac aneurysms with the use of an iliac branch device (IBD). Report: A total of 85 EVAR procedures with IBD were electively carried out in 81 patients between September 2007 and August 2012. Technical success was obtained in 98.7% of the cases. The mean follow-up duration was 20.4 months (SD ± 15.4). There was one IBD occlusion (1.2%). Estimated 48 months' survival, freedom from re-intervention and branch occlusion were 76.7%, 88.3% and 98%, respectively. Conclusions: EVAR for aorto-iliac aneurysms using IBD is an effective procedure with low complication and re-intervention rates at mid-term follow-up

    HYPERSPECTRAL DATA, CHANGE DETECTION AND THE MAD TRANSFORMATION

    Get PDF
    Abstract This paper deals with the application of the MAD transformation to change detection in bi-tempotal hyperspectral data. Several processing schemes are proposed in order to facilitate both the actual change detection, the many variables involved and the spatial nature of the data. The MAD Transformation Applied to Hyperspectral Data The multivariate alteration detection (MAD) transformatio

    Alternative hybrid reconstruction for bilateral common and internal iliac artery aneurysms associated with external iliac artery occlusion

    Get PDF
    Purpose: To describe an alternative reconstruction for bilateral common (CIA) and internal (IIA) iliac artery aneurysms associated with external iliac artery (EIA) occlusion in a patient unfit for open surgery. Case Report: A high-risk 81-year-old man presented with contained rupture of a left CIA aneurysm in the presence of bilateral CIA and IIA aneurysms associated with complete occlusion of the left EIA and normal patency of both common femoral arteries. In an emergent procedure, the left EIA was recanalized subintimally, and the right IIA was embolized with a 14-mm Amplatzer Plug. The main body of a standard Excluder endograft was deployed just distal to the origin of the left renal artery, and the ipsilateral leg was extended into the proximal right EIA. On the contralateral side, a short 10-mm-diameter limb was inserted through a 12-F sheath and deployed in the CIA, proximal to the iliac bifurcation. Via a percutaneous left brachial artery access, 3 covered stents (9359 mm, 10359 mm, 10359 mm) were deployed from the distal IIA to the endograft contralateral limb. A right-to-left femorofemoral crossover bypass graft concluded the operation. The patient was discharged on the 5th postoperative day without complications; follow-up imaging at 6 months showed patency of the stent-graft and crossover bypass, with complete exclusion of the aneurysms and no evidence of endoleak. Conclusion: This case demonstrates an effective solution for complex aortoiliac lesions using commercially available devices, underlining how an accurate knowledge of alternative endovascular techniques and materials is crucial in the management of complex cases

    Global-scale comparison of passive (SMOS) and active (ASCAT) satellite based microwave soil moisture retrievals with soil moisture simulations (MERRA-Land)

    Get PDF
    AbstractGlobal surface soil moisture (SSM) datasets are being produced based on active and passive microwave satellite observations and simulations from land surface models (LSM). This study investigates the consistency of two global satellite-based SSM datasets based on microwave remote sensing observations from the passive Soil Moisture and Ocean Salinity (SMOS; SMOSL3 version 2.5) and the active Advanced Scatterometer (ASCAT; version TU-Wien-WARP 5.5) with respect to LSM SSM from the MERRA-Land data product. The relationship between the global-scale SSM products was studied during the 2010–2012 period using (1) a time series statistics (considering both original SSM data and anomalies), (2) a space–time analysis using Hovmöller diagrams, and (3) a triple collocation error model. The SMOSL3 and ASCAT retrievals are consistent with the temporal dynamics of modeled SSM (correlation R>0.70 for original SSM) in the transition zones between wet and dry climates, including the Sahel, the Indian subcontinent, the Great Plains of North America, eastern Australia, and south-eastern Brazil. Over relatively dense vegetation covers, a better consistency with MERRA-Land was obtained with ASCAT than with SMOSL3. However, it was found that ASCAT retrievals exhibit negative correlation versus MERRA-Land in some arid regions (e.g., the Sahara and the Arabian Peninsula). In terms of anomalies, SMOSL3 better captures the short term SSM variability of the reference dataset (MERRA-Land) than ASCAT over regions with limited radio frequency interference (RFI) effects (e.g., North America, South America, and Australia). The seasonal and latitudinal variations of SSM are relatively similar for the three products, although the MERRA-Land SSM values are generally higher and their seasonal amplitude is much lower than for SMOSL3 and ASCAT. Both SMOSL3 and ASCAT have relatively comparable triple collocation errors with similar spatial error patterns: (i) lowest errors in arid regions (e.g., Sahara and Arabian Peninsula), due to the very low natural variability of soil moisture in these areas, and Central America, and (ii) highest errors over most of the vegetated regions (e.g., northern Australia, India, central Asia, and South America). However, the ASCAT SSM product is prone to larger random errors in some regions (e.g., north-western Africa, Iran, and southern South Africa). Vegetation density was found to be a key factor to interpret the consistency with MERRA-Land between the two remotely sensed products (SMOSL3 and ASCAT) which provides complementary information on SSM. This study shows that both SMOS and ASCAT have thus a potential for data fusion into long-term data records

    Recent global and regional trends in burned area and their compensating environmental controls

    Get PDF
    The apparent decline in the global incidence of fire between 1996 and 2015, as measured by satellite- observations of burned area, has been related to socioeconomic and land use changes. However, recent decades have also seen changes in climate and vegetation that influence fire and fire-enabled vegetation models do not reproduce the apparent decline. Given that the satellite-derived burned area datasets are still relatively short (<20 years), this raises questions both about the robustness of the apparent decline and what causes it. We use two global satellite-derived burned area datasets and a data-driven fire model to (1) assess the spatio-temporal robustness of the burned area trends and (2) to relate the trends to underlying changes in temperature, precipitation, human population density and vegetation conditions. Although the satellite datasets and simulation all show a decline in global burned area over ~20 years, the trend is not significant and is strongly affected by the start and end year chosen for trend analysis and the year-to-year variability in burned area. The global and regional trends shown by the two satellite datasets are poorly correlated for the common overlapping period (2001–2015) and the fire model simulates changes in global and regional burned area that lie within the uncertainties of the satellite datasets. The model simulations show that recent increases in temperature would lead to increased burned area but this effect is compensated by increasing wetness or increases in population, both of which lead to declining burned area. Increases in vegetation cover and density associated with recent greening trends lead to increased burned area in fuel-limited regions. Our analyses show that global and regional burned area trends result from the interaction of compensating trends in controls of wildfire at regional scales

    Evolution of the ESA CCI Soil Moisture climate data records and their underlying merging methodology

    Get PDF
    The European Space Agency's Climate Change Initiative for Soil Moisture (ESA CCI SM) merging algorithm generates consistent quality-controlled long-term (1978–2018) climate data records for soil moisture, which serves thousands of scientists and data users worldwide. It harmonises and merges soil moisture retrievals from multiple satellites into (i) an active-microwave-based-only product, (ii) a passive-microwave-based-only product and (iii) a combined active–passive product, which are sampled to daily global images on a 0.25∘ regular grid. Since its first release in 2012 the algorithm has undergone substantial improvements which have so far not been thoroughly reported in the scientific literature. This paper fills this gap by reviewing and discussing the science behind the three major ESA CCI SM merging algorithms, versions 2 (https://doi.org/10.5285/3729b3fbbb434930bf65d82f9b00111c; Wagner et al., 2018), 3 (https://doi.org/10.5285/b810601740bd4848b0d7965e6d83d26c; Dorigo et al., 2018) and 4 (https://doi.org/10.5285/dce27a397eaf47e797050c220972ca0e; Dorigo et al., 2019), and provides an outlook on the expected improvements planned for the next algorithm, version 5.</p
    • …
    corecore