3,817 research outputs found

    Evidences of instantaneous dynamic triggering during the seismic sequence of year 2000 in South Iceland

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    We analyze the coseismic stress perturbation during the June 17th, 2000 South Iceland seismic sequence; the mainshock (MS 6.6) was followed by three large events within few tens of seconds (8, 26, and 30 s, respectively) located within 80 km. The aim of this paper is to investigate short-term fault interaction and instantaneous triggering. This happens when a fault perturbed by a stress change fails before the end of the transient stress perturbation. We compute the shear, normal, and Coulomb stress changes as functions of time in a stratified elastic half-space by using discrete wavenumber and reflectivity methods. We calculate dynamic stresses caused by the mainshock at the hypocenters of these three subsequent events. Our numerical results show that the onset of the last two events is slightly delayed with respect to the arrival time of the second positive peak of Coulomb stress variation, while the first event occurred after the first positive stress peak. We have also analysed the response of a spring-slider system representing a fault governed by a rate- and state-dependent friction law, perturbed by shear and normal stress variations caused by the mainshock. The fault response to the computed stress perturbations is always clock advanced. We have found suitable constitutive parameters of the modelled fault that allow the instantaneous dynamic triggering of these three earthquakes. If the initial sliding velocity is comparable with the tectonic loading velocity, we obtained failure times close to the observed origin times for low values of the initial effective normal stress

    Sea level change and vertical land movements since the last two millennia along the coasts of southwestern Turkey and Israel

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    This paper provides new relative sea-level data inferred from coastal archaeological sites located along the Turkish coasts of the Gulf of Fethye (8 sites), and Israel, between Akziv and Caesarea (5 sites). The structures selected are those that, for effective functioning, can be accurately related to sea level at the time of their construction. Thus their positions with respect to present sea level provide a measure of the relative sea level change since their time of construction. Useful information was obtained from the investigated sites spanning an age range of ~2.3 to ~1.6 ka BP. The inferred changes in relative sea level for the two areas are distinctly different, from a rise of 2.41 to 4.50 m in Turkey and from 0 to 0.18 m in Israel. Sea level change is the combination of several processes, including vertical tectonics, glacio–hydro-isostatic signals associated with the last glacial cycle, and changes in ocean volume. For the Israel section, the present elevations of the MIS 5.5 Tyrrhenian terraces occur at a few meters above present sea level and vertical tectonic displacements are small. Data from GPS and tide gauge measurements also indicate that any recent vertical movements are small. The MIS-5.5 shorelines are absent from the investigated section of the Turkish coast, consistent with crustal subsidence associated with the Hellenic Arc. The isostatic signals for the Israel section of the coast are also small (ranging from -0.11 mm/year to 0.14 mm/year, depending on site and earth model) and the observed (eustatic) average sea level change, corrected for this contribution, is a rise of 13.5±2.6 cm during the past ~2 ka. This is attributed to the time-integrated contribution to sea level from a combination of thermal expansion and other increases in ocean volume. The observed sea levels from the Turkish sites, in contrast, indicate a much greater rise of up to 2.2 mm/yr since 2.3 ka BP occurring in a wide area between Knidos and Kekova. The isostatic signal here is also one of a rising sea level (of up to ~ 1mm/year and site and earth-model dependent) and the corrected tectonic rate of land subsidence is ~1.48 mm/year. This is the primary cause of dramatic relative sea level rise for this part of the coast

    On the rehydration of organic layered double hydroxides to form low-ordered carbon/LDH nanocomposites

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    Low-ordered carbon/layered double hydroxide (LDH) nanocomposites were prepared by rehydration of the oxides produced by calcination of an organic LDH. While the memory effect is a widely recognized effect on oxides produced by inorganic LDH, it is unprecedented from the calcination/rehydration of organic ones. Different temperatures (400, 600, and 1100 °C) were tested on the basis of thermogravimetric data. Water, instead of a carbonate solution, was used for the rehydration, with CO2 available from water itself and/or air to induce a slower process with an easier and better intercalation of the carbonaceous species. The samples were characterized by X-ray powder diffraction (XRPD), infrared in reflection mode (IR), and Raman spectroscopies and scanning electron microscopy (SEM). XRPD indicated the presence of carbonate LDH, and of residuals of unreacted oxides. IR confirmed that the prevailing anion is carbonate, coming from the water used for the rehydration and/or air. Raman data indicated the presence of low-ordered carbonaceous species moieties and SEM and XRPD the absence of separated bulky graphitic sheets, suggesting an intimate mixing of the low ordered carbonaceous phase with reconstructed LDH. Organic LDH gave better memory effect after calcination at 400 °C. Conversely, the carbonaceous species are observed after rehydration of the sample calcined at 600 °C with a reduced memory effect, demonstrating the interference of the carbonaceous phase with LDH reconstruction and the bonding with LDH layers to form a low-ordered carbon/LDH nanocomposite

    A 2-year point-prevalence surveillance of healthcare-associated infections and antimicrobial use in Ferrara University Hospital, Italy

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    Background: Healthcare-Associated Infections (HAIs) represent one of the leading issues to patient safety as well as a significant economic burden. Similarly, Antimicrobial Use (AMU) and Resistance (AMR) represent a growing threat to global public health and the sustainability of healthcare services. Methods: A Point Prevalence Survey (PPS) following the 2016 ECDC protocol for HAI prevalence and AMU was conducted at Ferrara University Hospital (FUH). Data were collected by a team of trained independent surveyors in 2016 and 2018. Risk factors independently associated with HAI were assessed by a multivariate logistic regression model. Results: Of the 1102 patients surveyed, 115 (10.4%) had an active HAI and 487 (44.2%) were on at least 1 systemic antimicrobial agent. Factors independently associated with increased HAI risk were a "Rapidly Fatal" McCabe score (expected fatal outcome within 1 year), presence of medical devices (PVC, CVC, indwelling urinary catheter or mechanically assisted ventilation) and a length of hospital stay of at least 1 week. The most frequent types of HAI were pneumonia, bloodstream infections, and urinary tract infections. Antimicrobial resistance to third-generation cephalosporins was observed in about 60% of Enterobacteriaceae. Conclusions: The survey reports a high prevalence of HAI and AMU in FUH. Repeated PPSs are useful to control HAIs and AMU in large acute-care hospitals, highlighting the main problematic factors and allowing planning for improvement actions

    Coseismic deformation and source modeling of the May 2012 Emilia (Northern Italy) earthquakes

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    On May 20th, 2012, an ML 5.9 earthquake (Table 1) occurred near the town of Finale Emilia, in the Central Po Plain, Northern Italy (Figure 1). The mainshock caused 7 casualties and the collapse of several historical buildings and industrial sheds. The earthquake sequence continued with diminishing aftershock magnitudes until May 29th, when an ML 5.8 earthquake occurred near the town of Mirandola, ~12 km WSW of the mainshock (Scognamiglio et al., 2012). This second mainshock started a new aftershock sequence in this area, and increased structural damage and collapses, causing 19 more casualties and increasing to 15.000 the number of evacuees. Shortly after the first mainshock, the Department of Civil Protection (DPC) activated the Italian Space Agency (ASI), which provided post-seismic SAR Interferometry data coverage with all 4 COSMO-SkyMed SAR satellites. Within the next two weeks, several SAR Interferometry (InSAR) image pairs were processed by the INGV-SIGRIS system (Salvi et al., 2012), to generate displacement maps and preliminary source models for the emergency management. These results included continuous GPS site displacement data, from private and public sources, located in and around the epicentral area. In this paper we present the results of the geodetic data modeling, identifying two main fault planes for the Emilia seismic sequence and computing the corresponding slip distributions. We discuss the implication of this seismic sequence on the activity of the frontal part of the Northern Apennine accretionary wedge by comparing the co-seismic data with the long term (geological) and present day (GPS) velocity fields.Published645-6551.1. TTC - Monitoraggio sismico del territorio nazionale1.9. Rete GPS nazionale1.10. TTC - Telerilevamento3.2. Tettonica attivaJCR Journalrestricte

    Methylenetetrahydrofolate reductase gene C677T polymorphism, homocysteine, vitamin B12, and DNA damage in coronary artery disease

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    Effect of moderate weight loss on hepatic, pancreatic and visceral lipids in obese subjects

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    OBJECTIVE: To compare the effects of weight loss on visceral and subcutaneous abdominal fat, liver and pancreas lipid contentand to test the effects of these changes on metabolic improvement observed after weight loss.DESIGN: Weight-loss program designed to achieve a loss of 7--10% of the initial weight.SUBJECTS: 24 obese subjects (13 males and 11 females) with age ranging from 26 to 69 years and body mass index (BMI)30.2 -- 50.5 kgm2. Measurements: weight, BMI, waist circumference, body composition as assessed by dual-energy X-rayabsorptiometry, metabolic variables, leptin, adiponectin, visceral and subcutaneous abdominal fat, liver and pancreas lipidcontent as assessed by magnetic resonance were evaluated before and after weight loss achieved by hypocaloric diet.RESULTS: After a mean body weight decrease of 8.9%, BMI, waist circumference, fat mass, all metabolic variables, homeostasismodel assessment of insulin resistance (HOMA), alanine amino transferase, gamma glutamyl transpeptidase, high-sensitivityC-reactive protein (hs-CRP) and leptin, but not adiponectin and high-density lipoprotein-cholesterol, significantly decreased (allPo0.01). Visceral and subcutaneos abdominal fat, liver and pancreas lipid content significantly decreased (all Po0.01). Percentchanges in liver lipid content were greater (84.1\ub13%) than those in lipid pancreas content (42.3\ub129%) and visceral abdominalfat (31.9\ub115.6%). After weight loss, percentage of subjects with liver steatosis decreased from 75 to 12.5%. Insulin resistanceimprovement was predicted by changes in liver lipid content independently of changes in visceral fat, pancreas lipid content,systemic inflammation, leptin and gender.CONCLUSION: Moderate weight loss determines significant decline in visceral abdominal fat, lipid content in liver andpancreas. Reduction of liver lipid content was greater than that of pancreas lipid content and visceral fat loss. Liver lipidcontent is the strongest predictor of insulin resistance improvement after weight loss

    Sea level changes in the Mediterranean: tectonic implications

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    The interpretation of sea level variations along the coasts of the Mediterranean region must be accompanied by the evaluation of vertical land movements associated with seismic and volcanic sources. This can be tentatively carried out through seismic strain analysis based on data pertaining the last 2 millennia as well as from the study of maritime archaeological structures.PublishedHersonissos, Crete island, Greece3.3. Geodinamica e struttura dell'interno della Terraope
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