2,919 research outputs found

    Predicted rates of merging neutron stars in galaxies

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    In this work, we compute rates of merging neutron stars (MNS) in galaxies of different morphological type, as well as the cosmic MNS rate in a unitary volume of the Universe adopting different cosmological scenarios. Our aim is to provide predictions of kilonova rates for future observations both at low and high redshift. In the adopted galaxy models, we take into account the production of r-process elements either by MNS or core-collapse supernovae. In computing the MNS rates we adopt either a constant total time delay for merging (10 Myr) or a distribution function of such delays. Our main conclusions are: i) the observed present time MNS rate in our Galaxy is well reproduced either with a constant time delay or a distribution function t1\propto t^{-1}. The [Eu/Fe] vs. [Fe/H] relation in the Milky Way can be well reproduced with only MNS, if the time delay is short and constant. If the distribution function of delays is adopted, core-collapse supernovae as are also required. ii) The present time cosmic MNS rate can be well reproduced in any cosmological scenario, either pure luminosity evolution or a typical hierarchical one, and spirals are the main contributors to it. iii) The spirals are the major contributors to the cosmic MNS at all redshifts in hierarchical scenarios. In the pure luminosity evolution scenario, the spirals are the major contributors locally, whereas at high redshift ellipticals dominate. iv) The predicted cosmic MNS rate well agrees with the cosmic rate of short Gamma Ray Bursts if the distribution function of delays is adopted, in a cosmological hierarchical scenario observationally derived. v) Future observations of Kilonovae in ellipticals will allow to disentangle among constant or a distribution of time delays as well as among different cosmological scenarios

    Azimuthal transects of stream orientations: An advanced in understanding the regional morphotectonic setting of eastern Abruzzo (Central Italy)

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    The recently proposed azimuthal transects method was applied to the drainage network of the eastern Abruzzo area, in order to confirm the location and identify the kinematics of regional fault zones, supposed to characterise the boundaries between different morphotectonic sectors previously recognised in the area. This methodology consists of applying the azimuthal analysis of low order (younger) stream orientations along transects crossing inferred faults. Its usefulness in morphotectonic investigations is linked to the possibility of identify statistical progressive rotations of channels induced by strike-slip displacements, especially where the classical structural analysis is unlikely to be performed because of lacking pervasive deformations within outcropping rocks. At the boundaries between the three different morphotectonic sectors formerly mentioned, strike-slip offsets were identified along E-W oriented fault zones, whose presence is also suggested by some macroscopic geomorphological evidence, such as the deflection of several main rivers towards the E-W direction. These results are consistent with those get by structural and geophysical studies, thus allowing to infer that these shallow crust plio-quaternary deformations could be the effect of the activity of the E-W lithospheric deformation zone which, according to many Authors, would divide the Adriatic plate into two different portions

    Upgrade of the CEDIT database of earthquake-induced ground effects in Italy

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    The database related to the Italian Catalogue of EarthquakeInduced Ground Failures (CEDIT), was recently upgraded and updated to 2017 in the frame of a work-in-progress focused on the following issues: i) reorganization of the geo-database architecture; ii) revision of the earthquake parameters from the CFTI5 e CPTI15 catalogues by INGV; ii) addition of new data on effects induced by earthquakes occurred from 2009 to 2017; iv) attribution of macroseismic intensity value to each effect site, according to the CFTI5 e CPTI15 catalogues by INGV. The revised CEDIT database aims at achieving: i) the optimization of the CEDIT catalogue in order to increase its usefulness for both Public Institutions and individual users; ii) a new architecture of the geo-database in view of a future implementation of the online catalogue which implies its usability via web-app also to support post-event detection and surveying activities. Here we illustrate the new geo-database design and discuss the statistics that can be derived from the updated database. Statistical analysis was carried out on the data recorded in the last update of CEDIT to 2017 and compared with the analysis of the previous update outline that: - the most represented ground effects are the landslides with a percentage of 55% followed by ground cracks with a percentage of 23%; - the MCS intensity (IMCS) distribution of the effect sites shows a maximum in correspondence of the IMCS class 8 even if a second frequency peak appears in the IMCS class 7 only for surface faulting effects; - the distribution of the effects according to the epicentral distance shows a decrease for all the typologies of induced ground effects with increasing epicentral distance

    The use of the Stream Length-Gradient index in morphotectonic analysis of small catchments: A case study from Central Italy

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    The aim of this work is to test an integrated quantitative geomorphic approach based on Stream Length-Gradient Index (SL Index) analysis within the small catchment of the Tarugo River in the Northern Marchean Apennines (Central Italy). The Tarugo River basin, 92 km2 wide, strikes SW-NE across the Marchean Ridge and the western sector of Marchean Piedmont. The area is characterized by a series of NW-SE trending, NE verging thrust folds affecting the Meso-Cenozoic bedrock that pass upward from dominantly carbonate to dominantly terrigenous rocks. The area investigated has been affected since the Pliocene by extensional tectonics, accompanying a regional uplift decreasing in rate north-eastwards. In this work the SL Index analysis has been integrated with the spatial analysis of the Amplitude of relief (Ar) and compared to geological and geomorphological field data. Results of this work indicate that the SL Index is a valid tool to detect the long wavelength structural effect on topography as well as the incipient local response to regional processes (i.e. regional uplift) that is often undetectable by other morphotectonic parameters. In contrast, the SL Index analysis seems not be a valid tool for discriminating the local lithological influence from the tectonic one. © 2008 Elsevier B.V. All rights reserved

    Geomorphic signal of active faulting at the northern edge of Lut Block. Insights on the kinematic scenario of Central Iran

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    Recent works documented Neogene to Quaternary dextral strike-slip tectonics along the Kuh-e-Sarhangi and Kuh-e-Faghan intraplate strike-slip faults at the northern edge of the Lut Block of Central Iran, previously thought to be dominated by sinistral strike-slip deformation. This work focuses on the evidence of Quaternary activity of one of these fault systems, in order to provide new spatio-temporal constraints on their role in the active regional kinematic scenario. Through geomorphological and structural investigation, integrated with Optically Stimulated Luminescence (OSL) dating of three generations of alluvial fans and fluvial terraces (at ~53, ~25 and ~6 ka), this study documents (i) the topographic inheritance of the long-term (Myr) punctuated history of fault nucleation, propagation, and exhumation along the northern edge of Lut Block; (ii) the tectonic control on drainage network evolution, pediment formation, fluvial terraces, and alluvial-fan architecture; (iii) the minimum Holocene age of Quaternary dextral strike-slip faulting; and (iv) the evidence of Late Quaternary fault-related uplift localized along the different fault strands. The documented spatial and temporal constraints on the active dextral strike-slip tectonics at the northern edge of Lut Block provided new insights on the kinematic model for active faulting in Central Iran, which has been reinterpreted in an escape tectonic scenario

    Geological constraints for a conceptual evolutionary model of the slope deformations affecting Mt. Nuovo at Ischia (Italy)

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    ischia island was the scenario of several Holocene slope in- stability events occurred at different scales, from shallow mass movements, triggered by meteo-climatic forcing, up to massive rock slope failures such as large debris avalanches these last ones related to the volcano-tectonic dynamics of a resurgent caldera. the present study focuses on the gravitational deformation that in- volves Mt. nuovo, located in the western portion of Mt. epomeo resurgent block. a high-resolution engineering-geological model was reconstructed according to a multi-modelling approach sup- ported by field geo-structural evidences and constrained by pas- sive seismic investigations. it revealed a complex morpho-struc- tural setting and led to the identification of a multiple compound mechanism, involving a rock mass volume of about 190 million of cubic meters. the obtained geological model shows a partial structural control of the pre-existing tectonic pattern on slope deformation mechanisms, highlighting geometric and volumetric similarities between the Mt. nuovo ongoing deformation and an already oc- curred rock avalanche. the defined conceptual evolutionary mod- el allows to hypothesize the role of inner pressures constraining the shear zone initiation and propagation and making reliable a future scenario of generalized collapse. Starting from these new field and laboratory data, numerical models will be reconstructed in order to depict the evolution of the gravitational slope deformation, evaluate its sensitivity and constrain future evolutionary instability scenarios

    Field trip to the Ischia resurgent caldera, a journey across an active volcano in the Gulf of Naples

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    Ischia is one of the most impressive examples of post-caldera resurgence in the world, with its almost 1,000 m of uplift in less than 30 ka. This three-days field trip will lead the participants through the geological and volcanological history of the island, illustrating the volcanic and related hazardous phenomena threatening about 50,000 inhabitants. Effusive and explosive eruptions, catastrophic earthquakes and huge debris-avalanches struck the island that, since Neolithic times, experienced a complex history of alternating human colonization and natural disasters. The field trip consists of three routes: 1) the circumnavigation of the island, aimed to outline its main volcanological, geomorphological and tectonic features and to observe the oldest volcanic rocks exposed, stimulating discussions about coastal evolution and the relationships between volcanism, volcano-tectonism and slope instability; 2) an onland excursion on peculiar aspects of the products related to Ischia more recent period of volcanic activity; 3) a route focusing on the Mt. Epomeo Green Tuff caldera forming eruptions (55-60 ka), encouraging a discussion on the dynamics of the intracalderic resurgence and the geomorphological evolution of the Mt. Epomeo slopes, with ongoing Mass Rock Creep (MRC) processes culminating in rockavalanche, debris-avalanche and lahar deposits

    Addressing the selective role of distinct prefrontal areas in response suppression: A study with brain tumor patients

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    The diverging evidence for functional localization of response inhibition within the prefrontal cortex might be justified by the still unclear involvement of other intrinsically related cognitive processes like response selection and sustained attention. In this study, the main aim was to understand whether inhibitory impairments, previously found in patients with both left and right frontal lesions, could be better accounted for by assessing these potentially related cognitive processes. We tested 37 brain tumor patients with left prefrontal, right prefrontal and non-prefrontal lesions and a healthy control group on Go/No-Go and Foreperiod tasks. In both types of tasks inhibitory impairments are likely to cause false alarms, although additionally the former task requires response selection and the latter target detection abilities. Irrespective of the task context, patients with right prefrontal damage showed frequent Go and target omissions, probably due to sustained attention lapses. Left prefrontal patients, on the other hand, showed both Go and target omissions and high false alarm rates to No-Go and warning stimuli, suggesting a decisional rather than an inhibitory impairment. An exploratory whole-brain voxel-based lesion-symptom mapping analysis confirmed the association of left ventrolateral and dorsolateral prefrontal lesions with target discrimination failure, and right ventrolateral and medial prefrontal lesions with target detection failure. Results from this study show how left and right prefrontal areas, which previous research has linked to response inhibition, underlie broader cognitive control processes, particularly involved in response selection and target detection. Based on these findings, we suggest that successful inhibitory control relies on more than one functionally distinct process which, if assessed appropriately, might help us to better understand inhibitory impairments across different pathologies
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