3,942 research outputs found

    The relationship between volatile content and the eruptive style of basaltic magma: the Etna case

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    Fourier Transform Infrared (FT-IR) spectroscopic analyses of melt inclusions from four explosive eruptions of Etna (Italy) were conducted to determine pre-eruptive dissolved volatile concentrations. The studied eruptions include the 3930 BP subplinian, the 122 B.C. plinian, and the 4 January 1990 and the 23 December 1995 fountain fire eruptions. Preliminary results indicate that H2O varies between 3.13 and 1.02 wt% and CO2 between 1404 and 200 ppm. The most basic products (3930 BP tephra) contain the highest concentrations of CO2 (1404 ppm), whereas fire fountain hawaiitic tephra present the lowest values (< 200 ppm) indicating a continuous degassing process during the differentiation and rising of the magma. Generally, similar behavior has been found for water, characterized by a decreasing content during the differentiation that is mainly found in the 3930 BP eruption, 1990 and 1995 fire fountain products. Considering the relevance of volatile content and behaviour in determining the eruptive style, we made some inferences on the eruptive mechanisms based on the initial high volatile content and the degassing dynamics inside the plumbing system. These two factors suggest the cause of the high explosive activity in this basaltic volcano

    A component-level methodology to evaluate the seismic repair costs of infills and services for Italian RC buildings

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    AbstractThe reliable estimation of seismic losses due to damage to buildings is paramount for the post-emergency management and the planning of recovery activities. For residential reinforced concrete (RC) infilled buildings, a significant role in the computation of seismic loss is played by non-structural components, above all infills, partitions and services, as shown in past earthquakes. In this work, a component-based methodology is proposed to assess seismic losses for residential RC buildings in Mediterranean region. The attention is focused on the repairing activities for masonry infills (typical enclosure or partitions elements in Italian and Mediterranean RC buildings), and for services (plumbing systems, electric equipment, floor/wall tilesā€¦), commonly enclosed within the infill panels for the considered building typology. The described methodology can be used starting from the expected damage level to infills and partitions. It adopts given repair unit costs at different damage states of infills. The loss estimation methodology has been, first, validated by comparing predicted and actual repair costs for specific case-study buildings damaged by L'Aquila (Italy) 2009 earthquake. Then, the methodology has been applied to a wide dataset of RC buildings (about 2500 residential buildings) damaged by L'Aquila earthquake available from the literature, to show its possible application at a large-scale level. A good agreement between observed and predicted costs is obtained both for specific case-study buildings and for the wider building stock, especially when damage to structural components is very limited

    Coalescing binary systems of compact objects: Dynamics of angular momenta

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    The end state of a coalescing binary of compact objects depends strongly on the final total mass M and angular momentum J. Since gravitational radiation emission causes a slow evolution of the binary system through quasi-circular orbits down to the innermost stable one, in this paper we examine the corresponding behavior of the ratio J/M^2 which must be less than 1(G/c) or about 0.7(G/c) for the formation of a black hole or a neutron star respectively. The results show cases for which, at the end of the inspiral phase, the conditions for black hole or neutron star formation are not satisfied. The inclusion of spin effects leads us to a study of precession equations valid also for the calculation of gravitational waveforms.Comment: 22 pages, AASTeX and 13 figures in PostScrip

    Tephra hazard assessment at Mt. Etna (Italy)

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    In this paper we present a probabilistic hazard assessment for tephra fallout at Mt. Etna (Italy) associated with both short- and long-lived eruptions. Eruptive scenarios and eruption source parameters were defined based on the geological record, while an advectionā€“diffusionā€“sedimentation model was used to capture the variation in wind speed and direction with time after calibration with the field data. Two different types of eruptions were considered in our analysis: eruptions associated with strong short-lived plumes and eruptions associated with weak long-lived plumes. Our probabilistic approach was based on one eruption scenario for both types and on an eruption range scenario for eruptions producing weak long-lived plumes. Due to the prevailing wind direction, the eastern flanks are the most affected by tephra deposition, with the 122 BC Plinian and 2002ā€“2003 eruptions showing the highest impact both on infrastructures and agriculture

    Opis svojstava ekstra djevičanskog maslinovog ulja dobivenog iz raznih kultivara

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    The determination of some minor components of extra virgin olive oil, and in particular of the polyphenolic fraction of pigments and fragrances, can contribute to the characterization of the monovarietal productions: the quali-quantitative assessment of these substances can in fact contribute to the valorisation of typicalities and, at the same time, consent to the optimisation of the operational techniques during the processing and the eventual blending. The analytical techniques, applied here for the characterisation of extra virgin olive oil of Abruzzo and Istria, have highlighted that chemical composition can enhance the valorisation of these typical products. Nevertheless, further sampling program is needed to evidence typical composition profile that might be used as ā€œorigin markersā€.Određivarije nekih manjih komponenata ekstra djevičanskog maslinovog ulja, naročito polifenolne frakcije pigmemta i mirisa, može doprinijeti svojstvima monovarijetetnih proizvoda: kvalitativna i kvalitativna procjena tih supstancija može zapravo doprinijeti valorizaciji tipičnosti te, istodobno omogućiti optimizaciju operativnih tehnika za vrijeme prerade i mijeÅ”anja. Analitičke tehnike, ovdje primijenjene za opis svojstava ekstra djevičanskog maslinovog ulja iz Abruzza i Istre pokazuju da kemijski sastav može popraviti vrijednost ovih tipičnih proizvoda. Ipak, potreban je dodatni program uzorkovanja da se dokaže tipični profil sasĀ¬tava, Å”to se može upotrijebiti kao "oznaka podrijetla"

    Evolution of the seismic vulnerability of masonry buildings based on the damage data from L'Aquila 2009 event

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    AbstractThe purpose of this study is the analysis of vulnerability trends, with particular emphasis to the evolution of the seismic behaviour of masonry buildings over the years due to the improvements in construction practices and to the enhancement of building materials over the years, also related to the subsequent enactment of seismic prescriptions. To this aim, residential masonry buildings damaged after the 2009 L'Aquila earthquake are considered, coming from the online platform Da.D.O. (Database di Danno Osservato, Database of Observed Damage) recently released from the Italian Department of Civil Protection. General features of all the parameters available from the original database are thoroughly analysed, a selection of which is used for vulnerability analysis, namely the period of construction and the design type, the presence of structural interventions, the type of horizontal structure. Vulnerability curves are obtained through an optimization technique, minimizing the deviation between observed and predicted damage. PGA from ShakeMap is used for ground motion characterization. Damage levels defined according to the European Macroseismic Scale are considered, obtained from the observed damage for vertical structures collected during the inspections. Vulnerability curves are firstly obtained as a function of period of construction and horizontal structural types, limited to the irregular layout and bad quality vertical type only, highlighting their clear influence on seismic behaviour. Lastly, the effectiveness of retrofit intervention is evaluated comparing the vulnerability curves for strengthened masonry buildings compared to those not subjected to any retrofit interventions

    Opis svojstava ekstra djevičanskog maslinovog ulja dobivenog iz raznih kultivara

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    The determination of some minor components of extra virgin olive oil, and in particular of the polyphenolic fraction of pigments and fragrances, can contribute to the characterization of the monovarietal productions: the quali-quantitative assessment of these substances can in fact contribute to the valorisation of typicalities and, at the same time, consent to the optimisation of the operational techniques during the processing and the eventual blending. The analytical techniques, applied here for the characterisation of extra virgin olive oil of Abruzzo and Istria, have highlighted that chemical composition can enhance the valorisation of these typical products. Nevertheless, further sampling program is needed to evidence typical composition profile that might be used as ā€œorigin markersā€.Određivarije nekih manjih komponenata ekstra djevičanskog maslinovog ulja, naročito polifenolne frakcije pigmemta i mirisa, može doprinijeti svojstvima monovarijetetnih proizvoda: kvalitativna i kvalitativna procjena tih supstancija može zapravo doprinijeti valorizaciji tipičnosti te, istodobno omogućiti optimizaciju operativnih tehnika za vrijeme prerade i mijeÅ”anja. Analitičke tehnike, ovdje primijenjene za opis svojstava ekstra djevičanskog maslinovog ulja iz Abruzza i Istre pokazuju da kemijski sastav može popraviti vrijednost ovih tipičnih proizvoda. Ipak, potreban je dodatni program uzorkovanja da se dokaže tipični profil sasĀ¬tava, Å”to se može upotrijebiti kao "oznaka podrijetla"

    Ambulatory surgery for perianal Crohnā€™s disease. Study of feasibility

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    Background. One-third of Crohnā€™s disease (CD) patients present perianal fistula. The gold standard in the diagnosis and treatment of symptomatic perianal disease (PAD) in CD is the exploration of the anal canal and distal rectum under anesthesia (EUA). This procedure is mainly conducted as a day case surgery. Unfortunately, it is not always possible to proceed within the ideal timing and any delay may well represent a relevant clinical issue. The aim of this study was to evaluate the feasibility of outpatient treatment of symptomatic perianal fistulas in CD patients. Methods. All CD patients under regular follow-up at our inflammatory bowel disease referral center, presenting with symptomatic perianal fistulas, were offered surgical consultation. The data of patients were prospectively collected for three years (February 2014 to February 2017) for the purpose of the study. All clinical information, including previous EUA and/or records from MRI and endoscopic ultrasound, was included. Outpatient anal canal and distal rectum exploration and treatment (OE) were undertaken during the specialist surgical consultation. Fistulas were classified according to Parksā€™s classification; the type of outpatient treatment and compliance of patients were recorded. Pain was assessed by VAS at the time of the procedure and during the first control. Patients were followed up in the surgical clinic in relation to the study. Results. Ninety-two CD patients with symptomatic perianal fistulas had surgical consultation during the study period. OE was offered to all but 18 patients who fulfilled the exclusion criteria or had an extremely severe disease; six patients refused the OE (8.11%). Of the 68 patients undergoing OE, eleven (16.18%) had previous surgery for perianal disease. The OE was accomplished in sixty-one patients (89.71%), while in 7 patients, it was abandoned for scarce compliance. Nine patients (14.75%) underwent drainage of perianal abscess; in 3 of them, it was possible to probe the fistula tract, find the internal orifice, and pass a loose seton. Overall, setonage was performed in 50 patients (81.97%). Rectovaginal setons were placed in 3 patients and more than one seton (up to 3) in 6 cases. Fistulotomy was performed in 4 simple subcutaneous fistulous tracts. Concordance with the preoperative findings was found in 54 out of 61 patients. EUA was scheduled at the time of OE for the 7 patients who did not complete the procedure. All sixty-one patients who had the OE were followed up for a minimum of 12 months. Conclusions. This preliminary study indicates that OE in CD patients with symptomatic perianal fistulas is safe and feasible in a high-volume referral center. It might provide several benefits, including patientsā€™ logistics, reduce or remove patientsā€™ symptoms and discomfort, allow for a timely start of medical therapy, and avoid further complications
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