993 research outputs found
New constraints for site-effect characterization from seismic noise
In the framework of ground-motion amplification analysis for southern
Italy, the main target of this study is to provide new constraints on onedimensional,
shallow-velocity profiles for a site in the San Fele area
near the city of Potenza (southern Italy) where a permanent Irpinia
Seismic Network (ISNet) seismic station is installed. Ambient noise
vibrations were recorded during a seismic survey in San Fele, and the
data acquired were used to define the shallow shear-wave velocity
profiles and thicknesses of the shallow soil layers, through analysis of
the dispersion characteristics of the surface waves. Single station and
array techniques were used to obtain robust results, which show
relatively flat curves of the H/V spectral ratios and variations in shearwave
velocities confined to the first 50 m in depth. On the basis of these
results for the San Fele site, the present study aims to delineate a
standard procedure that can be systematically applied to all of the other
ISNet stations to improve site characterization. This will allow more
accurate evaluation of peak ground-motion quantities (e.g. peak
ground acceleration, peak ground velocity) at rock sites for use in shakemap
analysis
Shear-wave velocity structure at Mt. Etna from inversion of Rayleigh-wave dispersion patterns (2 s < T < 20 s)
In the present study, we investigated the dispersion characteristics of
medium-to-long period Rayleigh waves (2 s < T < 20 s) using both singlestation
techniques (multiple-filter analysis, and phase-match filter) and
multichannel techniques (horizontal slowness [p] and angular frequency
[~] stack, and cross-correlation) to determine the velocity structure for
the Mt. Etna volcano. We applied these techniques to a dataset of
teleseisms, as regional and local earthquakes recorded by two broad-band
seismic arrays installed at Mt. Etna in 2002 and 2005, during two seismic
surveys organized by the Istituto Nazionale di Geofisica e Vulcanologia
(INGV), sezione di Napoli. The dispersion curves obtained showed phase
velocities ranging from 1.5 km/s to 4.0 km/s in the frequency band 0.05
Hz to 0.45 Hz. We inverted the average phase velocity dispersion curves
using a non-linear approach, to obtain a set of shear-wave velocity models
with maximum resolution depths of 25 km to 30 km. Moreover, the
presence of lateral velocity contrasts was checked by dividing the whole
array into seven triangular sub-arrays and inverting the dispersion curves
relative to each triangle
Automatic Classification of Seismic Signals at Mt. Vesuvius Volcano, Italy, Using Neural Networks
We present a new strategy for reliable automatic classification of local seismic signals and volcano-tectonic earthquakes (VT). The method is based on a supervised neural network in which a new approach for feature extraction from short period seismic signals is applied. To reduce the number of records required for the analysis we set up a specialized neural classifier, able to distinguish two classes of signals, for each of the selected stations. The neural network architecture is a multilayer
perceptron (MLP) with a single hidden layer. Spectral features of the signals
and the parameterized attributes of their waveform have been used as input for this
network. Feature extraction is done by using both the linear predictor coding technique for computing the spectrograms, and a function of the amplitude for characterizing waveforms. Compared to strategies that use only spectral signatures, the inclusion of properly normalized amplitude features improves the performance of the classifiers, and allows the network to better generalize. To train the MLP network we compared the performance of the quasi-Newton algorithm with the scaled conjugate gradient method. We found that the scaled conjugate gradient approach is the faster of the two, with quite equally good performance. Our method was tested on a dataset recorded by four selected stations of the Mt. Vesuvius monitoring network, for the discrimination of low magnitude VT events and transient signals caused by either artificial (quarry blasts, underwater explosions) and natural (thunder) sources. In this test application we obtained 100% correct classification for one of the possible pairs of signal types (VT versus quarry blasts). Because this method was developed independently of this particular discrimination task, it can be applied to a broad range of other applications
Analysis and interpretation of the impact of missense variants in cancer
Large scale genome sequencing allowed the identification of a massive number of genetic variations, whose impact on human health is still unknown. In this review we analyze, by an in silico-based strategy, the impact of missense variants on cancer-related genes, whose effect on protein stability and function was experimentally determined. We collected a set of 164 variants from 11 proteins to analyze the impact of missense mutations at structural and functional levels, and to assess the performance of state-of-the-art methods (FoldX and Meta-SNP) for predicting protein stability change and pathogenicity. The result of our analysis shows that a combination of experimental data on protein stability and in silico pathogenicity predictions allowed the identification of a subset of variants with a high probability of having a deleterious phenotypic effect, as confirmed by the significant enrichment of the subset in variants annotated in the COSMIC database as putative cancer-driving variants. Our analysis suggests that the integration of experimental and computational approaches may contribute to evaluate the risk for complex disorders and develop more effective treatment strategie
Balancing selection, genetic drift, and human-mediated introgression interplay to shape MHC (functional) diversity in Mediterranean brown trout
The extraordinary polymorphism of major histocompatibility complex (MHC) genes is
considered a paradigm of pathogen-mediated balancing selection, although empirical
evidence is still scarce. Furthermore, the relative contribution of balancing selection
to shape MHC population structure and diversity, compared to that of neutral forces,
as well as its interaction with other evolutionary processes such as hybridization, re mains largely unclear. To investigate these issues, we analyzed adaptive (MHC-DAB
gene) and neutral (11 microsatellite loci) variation in 156 brown trout (Salmo trutta
complex) from six wild populations in central Italy exposed to introgression from do mestic hatchery lineages (assessed with the LDH gene). MHC diversity and structur ing correlated with those at microsatellites, indicating the substantial role of neutral
forces. However, individuals carrying locally rare MHC alleles/supertypes were in bet ter body condition (a proxy of individual fitness/parasite load) regardless of the zygo sity status and degree of sequence dissimilarity of MHC, hence supporting balancing
selection under rare allele advantage, but not heterozygote advantage or divergent
allele advantage. The association between specific MHC supertypes and body condi tion confirmed in part this finding. Across populations, MHC allelic richness increased
with increasing admixture between native and domestic lineages, indicating intro gression as a source of MHC variation. Furthermore, introgression across populations
appeared more pronounced for MHC than microsatellites, possibly because initially
rare MHC variants are expected to introgress more readily under rare allele advan tage. Providing evidence for the complex interplay among neutral evolutionary forces,
balancing selection, and human-mediated introgression in shaping the pattern of
MHC (functional) variation, our findings contribute to a deeper understanding of the
evolution of MHC genes in wild populations exposed to anthropogenic disturbance
Subsurface structure of the Solfatara volcano (Campi Flegreicaldera, Italy) as deduced from joint seismic-noise array,volcanological and morphostructural analysis
The joint application of different seismological techniques for seismic noise analysis, and the results of a volcanological and morphostructural survey, have allowed us to obtain a detailed and well constrained image of the shallow crustal structure of the Solfatara volcano (Campi Flegrei caldera, Italy). Horizontal-to-vertical spectral ratios, inversion of surface wave dispersion curves and polarization analysis provided resonance frequencies and peak amplitudes, shear wave velocity profiles and polarization pattern of coherent ambient noise. These results, combined in a unique framework, indicate that the volcanic edifice is characterized by lateral and vertical discontinuities and heterogeneities in terms of shear wave velocity, lithological contrasts and structural setting. The interpretation of the seismological results, with the volcanological and morphostructural constraints, supports the hypothesis that the volcano has been characterized by a complex and intense activity, with the alternation of constructive and destructive phases, during which magmatic and phreatomagmatic explosions built a complex tuff-cone, later reworked by atmospheric agents and altered by hydrothermal activity. The differences in the velocity structure between the central and eastern parts of the crater have been interpreted as resulting from a possible eastward migration of the eruptive vent along the deformational features affecting the area, and to the presence of viscous lava and lithified tuff bodies within the feeding conduits, which are buried under a covering of reworked materials of variable thickness. The observed fault and fracture systems, partially inherited from regional structural setting and exhumed during volcanism and ground deformation episodes also seems to strongly control wave propagation, affecting the noise polarization properties
Nonhuman gamblers: lessons from rodents, primates, and robots
The search for neuronal and psychological underpinnings of pathological gambling in humans would benefit from investigating related phenomena also outside of our species. In this paper, we present a survey of studies in three widely different populations of agents, namely rodents, non-human primates, and robots. Each of these populations offers valuable and complementary insights on the topic, as the literature demonstrates. In addition, we highlight the deep and complex connections between relevant results across these different areas of research (i.e., cognitive and computational neuroscience, neuroethology, cognitive primatology, neuropsychiatry, evolutionary robotics), to make the case for a greater degree of methodological integration in future studies on pathological gambling
Integrated stratigraphy for the Late Quaternary in the eastern Tyrrhenian Sea
A high-resolution integrated stratigraphy is presented for the Late Quaternary in the southern-eastern Tyrrhenian Sea. It is based on calcareous plankton taxa (planktonic foraminifera and nannoplankton) distribution, d18OGlobigerinoides ruber record, tephrostratigraphy and radiometric dating methods (210Pb and 137Cs, AMS 14C) for a composite sediment core (from the top to the bottom, C90-1m, C90 and C836) from
the continental shelf of the Salerno Gulf. High sedimentation rates from ca 1 cm/100 y for the early Holocene, to 3.45 cm/100 y for the middle Holocene to 8.78 cm/100 y from late Holocene and to 20 cm/100 y for the last 600 AD, make this area an ideal marine archive of secular paleoclimate changes.
Quantitative distributional trend in planktonic foraminifera identify seven known (1Fe7F) eco-biozones, and several auxiliary bioevents of high potential for Mediterranean biostratigraphic correlation. Recognised
were: the acme distribution of Neogloboquadrina pachyderma r.c. between 10.800 0.400 ka BP and 5.500 0.347 ka BP, a strong increase in abundance of Globorotalia truncatulinoides r.c. and l.c. at 5.500 0.347 ka BP and at 4.571 0.96 ka BP, respectively, an acme interval of Globigerinoides quadrilobatus
(between 3.702 0.048 ka BP and 2.70 0.048 ka BP) and the acme/paracme intervals of
T. quinqueloba (acme between 3.350 0.054 ka BP and 1.492 0.016 ka BP; paracme between
1.492 0.016 ka BP and 0.657 0.025 ka BP; acme beginning 0.657 0.025 ka BP).
These results, integrated with trends of selected calcareous nannofossil species (Florisphaera profunda, Brarudosphaera bigelowii, Gephyrocapsa oceanica and Emiliania huxleyi) and d18OG. ruber signature, are consistent with the most important pre-Holocene and early Holocene paleoclimatic and paleoceanographic phases i.e., the BöllingeAllerod, the Younger Dryas and the time interval of Sapropel S1 deposition in the eastern Mediterranean Sea. These features revealed the high potential of this shallow water environment for high-resolution stratigraphy and correlation for the western Mediterranean.
In addition, the chemical characterization of seven tephra layers supplied further data about the age and the dispersal area of some well-known Campi Flegrei explosive events, inferring the possible occurrence of explosive activity at Vesuvius around the middle of the 6th century, and contributing to refine the tephrostratigraphic framework for the last 15 ka in the south-eastern Tyrrhenian Sea.Published71-852.2. Laboratorio di paleomagnetismoJCR Journalrestricte
Zn-induced interactions between SARS-CoV-2 orf7a and BST2/Tetherin
We present in this work a first X-ray Absorption Spectroscopy study of the interactions of Zn with human BST2/tetherin and SARS-CoV-2 orf7a proteins as well as with some of their complexes. The analysis of the XANES region of the measured spectra shows that Zn binds to BST2, as well as to orf7a, thus resulting in the formation of BST2-orf7a complexes. This structural information confirms the the conjecture, recently put forward by some of the present Authors, according to which the accessory orf7a (and possibly also orf8) viral protein are capable of interfering with the BST2 antiviral activity. Our explanation for this behavior is that, when BST2 gets in contact with Zn bound to the orf7a Cys(15) ligand, it has the ability of displacing the metal owing to the creation of a new disulfide bridge across the two proteins. The formation of this BST2-orf7a complex destabilizes BST2 dimerization, thus impairing the antiviral activity of the latter
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