1,721,751 research outputs found
Earthquake-reactivated landslide scenarios in Southern Italy based on spectral-matching input analysis
No full textThe Tyrrhenian portion of the Calabria region (southern Italy) is particularly prone to landslides as a consequence of intense morphodynamic processes. These processes affect the slopes that are composed of highly jointed metamorphic rock masses. Moreover, the frequent intense rainfalls and the up to Mw 7.0 regional earthquakes represent the main landslide triggering factors. An area of approximately 45km2 was selected as a test site in the context of a regional project aimed at reconstructing possible earthquake-reactivated landslide scenarios (i.e., referred to already existing landslide masses). An inventory map led to the identification of 175 landslides, including rock slides, earth slides and rock falls. Ground-motion scenarios based on a spectral-matching method were derived to evaluate the expected earthquake-induced displacements of the existing landslides. Naturally recorded acceleration time histories were selected from international ground-motion databases based on a similarity index and considered representative of the seismological features of the considered seismic sources (i.e., epicentral distance, magnitude, focal mechanism). Spectral attenuation was considered, according to well-established attenuation laws, to define the expected response spectrum at the outcropping bedrock corresponding to each existing landslide. Subsequently, the selected natural records were modified to guarantee spectral matching with the attenuated response spectra at each landslide site. The derived time histories were used to compute co-seismic displacements via the classic Newmark's sliding-block method. Different scenarios of co-seismic landslide displacements or collapse were generated for different pore-water pressure hypotheses. The strongest Mw > 6 seismic scenario (Messina Straits seismogenic source) indicated an exceedance probability of earthquake-induced co-seismic landslide collapse varying from 20 to 55 % with the increasing severity of the pore-water pressures. This probability corresponds to a percentage of co-seismic landslide displacements up to 40 % of the total inventoried landslides. The exceedance probability indicated that co-seismic landslide collapse drops below 20 % for Mw < 6 seismic scenarios. In contrast, if a uniform probability is assumed for the seismic action occurrence, i.e., return periods of 475 and 2,475 years, the total percentage of landslide co-seismic displacements could be as high as 70 and 90 %, respectively, for the considered pore-water pressures. © 2013 The Author(s)
A methodology for a comprehensive assessment of earthquake-induced landslide hazard, with an application to pilot sites in Central Italy
No full textAn integrated approach for the quantitative analysis of earthquake-induced landslide hazard is presented. The method encompasses most of the features for a comprehensive analysis of the phenomenon, such as: first-time slides and reactivations of existing landslide bodies; failures in rock and soil slopes; any kind of geometry of the failure surface; applicable to any scale, from basins to slopes; performance-oriented analysis; deterministic and probabilistic results; seismic hazard scenarios that encompasses both deterministic and probabilistic approaches; analytical computation of co-seismic displacements, through the integration of real accelerograms; results modulated in terms of given return periods and hydraulic boundary conditions. The methodology has been applied to selected sites in Central Italy where different geologic conditions exist, with different types of slope movements and where different seismic sources are responsible for different hazard scenarios and whose results are here shown through a mapping representation integrating all the conditions listed above. © 2016 Associazione Geotecnica Italiana, Rome, Italy
Probabilistic approach to provide scenarios of earthquake-induced slope failures (PARSIFAL) applied to the alcoy basin (South Spain)
No full textThe PARSIFAL (Probabilistic Approach to pRovide Scenarios of earthquake-Induced slope FAiLures) approach was applied in the basin of Alcoy (Alicante, South Spain), to provide a comprehensive scenario of earthquake-induced landslides. The basin of Alcoy is well known for several historical landslides, mainly represented by earth-slides, that involve urban settlement as well as infrastructures (i.e., roads, bridges). The PARSIFAL overcomes several limits existing in other approaches, allowing the concomitant analyses of: (i) first-time landslides (due to both rock-slope failures and shallow earth-slides) and reactivations of existing landslides, (ii) slope stability analyses of different failure mechanisms, (iii) comprehensive mapping of earthquake-induced landslide scenarios in terms of exceedance probability of critical threshold values of co-seismic displacements. Geotechnical data were used to constrain the slope stability analysis, while specific field surveys were carried out to measure jointing and strength conditions of rock masses and to inventory already existing landslides. GIS-based susceptibility analyses were performed to assess the proneness to shallow earth-slides as well as to verify kinematic compatibility to planar or wedge rock-slides and to topples. The experienced application of PARSIFAL to the Alcoy basin: (i) confirms the suitability of the approach at a municipality scale, (ii) outputs the main role of saturation in conditioning slope instabilities in this case study, (iii) demonstrates the reliability of the obtained results respect to the historical data. © 2018 by the authors. Licensee MDPI, Basel, Switzerland
Juvenile idiopathic arthritis: Current and future treatment options
No full textJuvenile idiopathic arthritis is the most common rheumatic disease in children. The management of juvenile idiopathic arthritis has improved in recent decades, and morbidity due to the disease is significantly decreased. In particular, the use of more effective drugs and their combination has changed the course of the disease in many patients. The increasing knowledge of inflammation mechanisms has lead to the development of new agents that target specific cytokines interfering with the inflammatory cascade. In particular, anti-TNF agents seem effective: etanercept is the only one licensed for juvenile idiopathic arthritis, and Phase III trials on two other anti-TNF agents, infliximab and adalimumab, are ongoing. This review discusses the current practice in the medical management of juvenile idiopathic arthritis, and potential new agents are discussed. © 2006 Ashley Publications
Childhood systemic sclerosis
No full textPURPOSE OF REVIEW: Juvenile systemic sclerosis has a variety of clinical manifestations, sometimes different from the adult form. Early recognition, proper classification and treatment may improve the long-term outcome. RECENT FINDINGS: A large multicenter study coordinated by the Pediatric Rheumatology European Society has yielded important information on the epidemiology and clinical manifestations of systemic sclerosis in childhood. An ad-hoc Committee on Classification Criteria for Juvenile Systemic Sclerosis developed the new classification criteria to help improve patient care by enabling earlier, more definite diagnoses and standardizing the conduct of clinical, epidemiologic, and outcome research for this rare disease. The overall outcome of children with systemic sclerosis is better than in adults but, in those cases with a fatal course, disease progression is rapid and an early involvement of internal organs is associated with poor outcome. SUMMARY: Studies over the past few years have highlighted the peculiar clinical features and the better outcome of juvenile systemic sclerosis compared with the adult form and propose new pediatric classification criteria. Efforts have recently been made to address the definition of evidence-based recommendations for the treatment of adult and pediatric onset systemic sclerosis. © 2007 Lippincott Williams & Wilkins, Inc
Systemic sclerosis in children
No full textJuvenile systemic sclerosis, although rare in children, represents one of the most severe chronic rheumatic conditions in pediatric rheumatology practice. In this review, the various clinical, laboratory and therapeutic aspects of systemic sclerosis in children will be presented. The overall outcome of this disease and the main distinctive features between childhood-onset and adulthood-onset disease will also be discussed. © 2007 Future Medicine Ltd
Relazioni Verticali e Determinazione del Prezzo nella Distribuzione di Carburanti in Italia
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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