Cenedese C.,Woods Hole Oceanographic Institution |
Adduce C.,University RomaTre
Journal of Physical Oceanography | Year: 2010
Dense overflows entrain surrounding waters at specific locations, for example, sills and constrictions, but also along the descent over the continental slope. The amount of entrainment dictates the final properties of these overflows, and thus is of fundamental importance to the understanding of the formation of deep water masses. Even when resolving the overflows, coarse resolution global circulation and climate models cannot resolve the entrainment processes that are often parameterized. A new empirical parameterization is suggested, obtained using an oceanic and laboratory dataset, which includes two novel aspects. First, the parameterization depends on both the Froude number (Fr) and Reynolds number of the flow. Second, it takes into account subcritical (Fr < 1) entrainment. A weak, but nonzero, entrainment can change the final density and, consequently, the depth and location of important water masses in the open ocean. This is especially true when the dense current follows a long path over the slope in a subcritical regime, as observed in the southern Greenland Deep Western Boundary Current. A streamtube model employing this new parameterization gives results that are more consistent with previous laboratory and oceanographic observations than when a classical parameterization is used. Finally, the new parameterization predictions compare favorably to recent oceanographic measurements of entrainment and turbulent diapycnal mixing rates, using scaling arguments to relate the entrainment ratio to diapycnal diffusivities. © 2010 American Meteorological Society.
Luisi P.L.,University RomaTre |
Allegretti M.,University RomaTre |
De Souza T.P.,Friedrich - Schiller University of Jena |
Steiniger F.,Friedrich - Schiller University of Jena |
And 2 more authors.
ChemBioChem | Year: 2010
(Figure Presented) Ferritin encapsulation inside lipid vesicles reveals the spontaneous formation of protein-rich vesicles. The solute distribution inside the vesicles follows a power law. The important conclusion for origins-of-life scenarios is that the dynamics of membrane closure allow the accumulation of solutes inside primitive cells, thus providing an explanation for the origins of early functional cells. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
Cappello A.,Italian National Institute of Geophysics and Volcanology |
Cappello A.,University of Catania |
Neri M.,Italian National Institute of Geophysics and Volcanology |
Acocella V.,University RomaTre |
And 3 more authors.
Bulletin of Volcanology | Year: 2012
We produce a spatial probability map of vent opening (susceptibility map) at Etna, using a statistical analysis of structural features of flank eruptions of the last 2 ky. We exploit a detailed knowledge of the volcano structures, including the modalities of shallow magma transfer deriving from dike and dike-fed fissure eruptions analysis on historical eruptions. Assuming the location of future vents will have the same causal factors as the past eruptions, we converted the geological and structural data in distinct and weighted probability density functions, which were included in a non-homogeneous Poisson process to obtain the susceptibility map. The highest probability of new eruptive vents opening falls within a N-S aligned area passing through the Summit Craters down to about 2,000 m a. s. l. on the southern flank. Other zones of high probability follow the North-East, East-North-East, West, and South Rifts, the latter reaching low altitudes (~400 m). Less susceptible areas are found around the faults cutting the upper portions of Etna, including the western portion of the Pernicana fault and the northern extent of the Ragalna fault. This structural-based susceptibility map is a crucial step in forecasting lava flow hazards at Etna, providing a support tool for decision makers. © 2012 Springer-Verlag.
Molin P.,University RomaTre |
Corti G.,CNR Institute of Geosciences and Earth Resources
Tectonophysics | Year: 2015
Along its length, the Main Ethiopian Rift (MER) in East Africa records a transition from early fault-dominated morphology in the South to axial magma assisted-rifting typical of continental break-up in the North. It is one of the few locations on Earth offering a complete picture of the evolution of continental rifting and thus provides a unique opportunity to directly analyze how the drainage network reorganizes under extensional tectonic forcing. In this paper we present a new analysis of the river network and relative landforms-complemented with a summary of recent geological data-at both rift margins of the Central MER, a key sector of the rift capturing the phase of drainage reorganization between incipient and mature rifting. This analysis shows that hydrography is strongly influenced by recent tectonics. Rectangular drainage patterns, windgaps, and lacustrine/swampy areas formed by structural dams document that the rivers are in continuous competition with fault activity. The irregular longitudinal profiles (with knickpoints/knickzones in correspondence with faults) also suggest that rivers are in a transient state of disequilibrium related to recent tectonic activity at rift margins, in agreement with previous geological and seismological data. A more regional analysis extended to the adjoining Northern and Southern MER indicates that rifting evolves from initial stages characterized by margins poorly incised by rivers with gentle channel gradients (except in correspondence with faults), to mature phases in which rift margins are highly incised by a well organized fluvial network composed by concave and steep rivers. Our regional analysis also indicates a stronger and/or more recent tectonic activity at the rift margins proceeding to the south, in line with previous models of rift development. © 2015 Elsevier B.V..
Pischiutta M.,Italian National Institute of Geophysics and Volcanology |
Salvini F.,University RomaTre |
Fletcher J.,U.S. Geological Survey |
Rovelli A.,Italian National Institute of Geophysics and Volcanology |
Ben-Zion Y.,University of Southern California
Geophysical Journal International | Year: 2012
We investigate shear wave polarization in the Hayward fault zone near Niles Canyon, Fremont, CA. Waveforms of 12 earthquakes recorded by a seven-accelerometer seismic array around the fault are analysed to clarify directional site effects in the fault damage zone. The analysis is performed in the frequency domain through H/V spectral ratios with horizontal components rotated from 0° to 180°, and in the time domain using the eigenvectors and eigenvalues of the covariance matrix method employing three component records. The near-fault ground motion tends to be polarized in the horizontal plane. At two on-fault stations where the local strike is N160°, ground motion polarization is oriented N88 ± 19° and N83 ± 32°, respectively. At a third on-fault station, the motion is more complex with horizontal polarization varying in different frequency bands. However, a polarization of N86 ± 7°, similar to the results at the other two on-fault stations, is found in the frequency band 6-8Hz. The predominantly high-angle polarization from the fault strike at the Hayward Fault is consistent with similar results at the Parkfield section of the San Andreas Fault and the Val d'Agri area (a Quaternary extensional basin) in Italy. In all these cases, comparisons of the observed polarization directions with models of fracture orientation based on the fault movement indicate that the dominant horizontal polarization is near-orthogonal to the orientation of the expected predominant cracking direction. The results help to develop improved connections between fault mechanics and near-fault ground motion. © 2012 The Authors Geophysical Journal International © 2012 RAS.
Pischiutta M.,Instituto Nazionale Of Geofisica E Vulcanologi |
Rovelli A.,Instituto Nazionale Of Geofisica E Vulcanologi |
Salvini F.,University RomaTre |
Di Giulio G.,Instituto Nazionale Of Geofisica E Vulcanologi |
Ben-Zion Y.,University of Southern California
Geophysical Journal International | Year: 2013
The Pernicana Fault (PF) is the main structural element of Mt Etna and the northern boundary of a section sliding to the southeast. Observed ground motion records in the damage zone of the PF show strong variations of directional resonance in the horizontal plane. The observed resonance directions exhibit an abrupt rotation of azimuth by about 30° across the fault, varying from N166° on the north side to N139° on the south. We interpret the directional resonance observations in terms of changes in the kinematics and deformation fields on the opposite sides of the fault. The northern side is affected primarily by the left-lateral strike-slip movement, whereas the southern side, that is subjected also to sliding, is under a dominant extensional stress regime. Brittle deformation models based on the observed kinematic field predict different sets of fractures on the opposite sides of the fault: synthetic cleavages and extensional fractures are expected to dominate in the northern and southern sides, respectively. These two fracture fields have different orientations (N74° and N42°, respectively) and both show a near-orthogonal relation (~88° in the northern sector and ~83° to the south) with the azimuth of the observed directional resonance. We conclude that the direction of the largest resonance motions is sensitive to and has transversal relationship with the dominant fracture orientation. The directional amplification is inferred to be produced by stiffness anisotropy of the fault damage zone, with larger seismic motions normal to the fractures. ©The Authors 2013.Published by Oxford University Press on behalf of The Royal Astronomical Society.
Nottiani D.G.,University RomaTre |
Leccese F.,University RomaTre
2012 11th International Conference on Environment and Electrical Engineering, EEEIC 2012 - Conference Proceedings | Year: 2012
This paper proposes a simple method for the analysis of the resonance frequency of a planar spiral coil used for wireless energy transfer via magnetic resonant coupling (Witricity), and illustrates an algorithm that was designed, through an advanced programming and computing software, to evaluate the lumped parameters of the coils. © 2012 IEEE.
Di Matteo A.,Technical University of Delft |
Pettinelli E.,University RomaTre |
Slob E.,Technical University of Delft
IEEE Transactions on Geoscience and Remote Sensing | Year: 2013
High-frequency electromagnetic (EM) surveys have shown to be valuable techniques in the study of soil water content due to the strong dependence of soil dielectric permittivity with moisture content. This quantity can be determined by analyzing the average value of the early-time instantaneous amplitude of ground-penetrating radar (GPR) traces. We demonstrate the reliability of this approach to evaluate the shallow soil water content variations from standard fixed-offset GPR data by simulating the data over different likely EM soil conditions. A linear dipole model that uses a thin-wire approximation is assumed for the transmitting and receiving antennas. The homogenous half-space model is used to calculate the waveform instantaneous amplitude values averaged over different time windows. We analyzed their correlation with the soil surface dielectric parameters, and we found a clear inverse linear dependence on the permittivity values. Moreover, we evaluated how different kinds of noise affect this correlation, and we determined the influence of the electrical conductivity on the trace attributes. Finally, through a two-layered medium, we estimated the effect on the GPR signal of a shallow reflector, we analyzed how its presence can carry out inaccuracies in the soil surface dielectric permittivity estimation, and we determined the best time window to minimize these errors. Copyright © 1980-2012 IEEE.
Iberite M.,University of Rome La Sapienza |
Iamonico D.,University of Rome La Sapienza |
Abati S.,University RomaTre |
Abbate G.,University of Rome La Sapienza
Plant Biosystems | Year: 2011
Lemna valdiviana Phil. and L. minuta Kunth are native species of the Americas. At present L. minuta colonizes in Europa and Asia, where it is often considered an invasive alien species. Recent floristic surveys in the Agro Pontino area (Lazio region, central Italy) allowed to find a population referring to L. valdiviana, supported by the recent gathering in Sardegna region. With the aim to identify correctly the two species, we carried out a morphometric study based on measurements of both qualitative and quantitative characters, made on herbarium and living specimens collected from America and Europe. The univariate and multivariate analyses clearly support the attribution of the population from Lazio to L. valdiviana. This gathering is the first record of this species for the Italian peninsula. Moreover, the checking of Herbaria allowed us to find the older specimen of L. minuta collected in Europe (around 1877). At present L. valdiviana is to be considered as a casual alien species in Agro Pontino, but the rapid colonization of the aquatic environments by Lemna species by means of vegetative reproduction allows us to recognize it as a potential invasive species. © 2011 Società Botanica Italiana.
Acconcia F.,University RomaTre |
Marino M.,University RomaTre
Frontiers in Physiology | Year: 2011
Two different isoforms of the estrogen receptors (i.e., ERα and ERβ) mediate pleiotropic 17β-estradiol (E2)-induced cellular effects.The ERs are principally localized in the nucleus where they act by globally modifying the expression of the E2-target genes. The premise that E2 effects are exclusively mediated through the nuclear localized ERs has been rendered obsolete by research over the last 15 years demonstrating that ERα and ERβ proteins are also localized at the plasma membranes and in other extra-nuclear organelles.The E2 modulation of cancer cell proliferation represents a good example of the impact of membrane-initiated signals on E2 effects. In fact, E2 via ERα elicits rapid signals driving cancer cells to proliferation (e.g., in breast cancer cells), while E2-induced ERβ rapid signaling inhibits proliferation (e.g., in colon cancer cells). In this review we provide with an overview of the complex system of E2-induced signal transduction pathways, their impact on E2-induced cancer cell proliferation, and the participation of E2-induced membrane-initiated signals in tumor environment. © 2011 Acconcia and Marino.