176 research outputs found
Surface groups acting on CAT(−1) spaces
Harmonic map theory is used to show that a convex cocompact surface group action on a CAT(-1) metric space fixes a convex copy of the hyperbolic plane (i.e. the action is Fuchsian) if and only if the Hausdorff dimension of the limit set of the action is equal to 1. This provides another proof of a result of Bonk and Kleiner. More generally, we show that the limit set of every convex cocompact surface group action on a CAT(-1) space has Hausdorff dimension ≥1, where the inequality is strict unless the action is Fuchsian
Investigation of the coupling asymmetries at double-slit interference experiments
Double-slit experiments inferring the phase and the amplitude of the
transmission coefficient performed at quantum dots (QD), in the Coulomb
blockade regime, present anomalies at the phase changes depending on the number
of electrons confined. This phase change cannot be explained if one neglects
the electron-electron interactions. Here, we present our numerical results,
which simulate the real sample geometry by solving the Poisson equation in 3D.
The screened potential profile is used to obtain energy eigenstates and
eigenvalues of the QD. We find that, certain energy levels are coupled to the
leads stronger compared to others. Our results give strong support to the
phenomenological models in the literature describing the charging of a QD and
the abrupt phase changes.Comment: conference paper, 50th anniversary of Aharonov-Bohm effec
La Rete Integrata Nazionale GPS (RING) dell' INGV: una infrastruttura aperta per la ricerca scientifica
Since 2004, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) is investing important
energies for the creation of a continuous GPS network dislocated all over the Italian territory. Data
transmission will occur in real time, integrating the experiences already existing in the different
INGV institutes and developing a 3-yrs strategy for the new installations. The main targets of the network are represented by active tectonics studies, including also the seismological part as strain
accumulation on faults. Within a 3-yrs funding project, it is expected, to realize for the scientific
community an infrastructure which is comparable to those existing in countries where advanced
crustal deformation studies are carried out. Thus, INGV have co-located the classical seismological
instrumentation (broad band seismometers and accelerometers) with GPS receivers to observe and
quantify the whole seismic cycle. In this short paper, we describe the CGPS network, the
technological choices for the monumentation and the data transmission, the data and metadata
management and, finally, the data policy and the deliverables.INGVUnpublishedreserve
GPS observations of coseismic deformation following the May 20 and 29, 2012, Emilia seismic events (northern Italy): data, analysis and preliminary models
In May-July 2012, a seismic sequence struck a broad area
of the Po Plain Region in northern Italy. The sequence in-
cluded two ML >5.5 mainshocks. The first one (ML 5.9) oc-
curred near the city of Finale Emilia (ca. 30 km west of
Ferrara) on May 20 at 02:03:53 (UTC), and the second (ML 5.8)
occurred on May 29 at 7:00:03 (UTC), about 12 km south-
west of the May 20 mainshock (Figure 1), near the city of
Mirandola. The seismic sequence involved an area that ex-
tended in an E-W direction for more than 50 km, and in-
cluded seven ML ≥5.0 events and more than 2,300 ML >1.5
events (http://iside.rm.ingv.it). The focal mechanisms of the
main events [Pondrelli et al. 2012, Scognamiglio et al. 2012,
this volume] consistently showed compressional kinematics
with E-W oriented reverse nodal planes.
This sector of the Po Plain is known as a region charac-
terized by slow deformation rates due to the northwards mo-
tion of the northern Apennines fold-and-thrust belt, which is
buried beneath the sedimentary cover of the Po Plain [Pi-
cotti and Pazzaglia 2008, Toscani et al. 2009]. Early global po-
sitioning system (GPS) measurements [Serpelloni et al. 2006]
and the most recent updates [Devoti et al. 2011, Bennett et al.
2012] recognized that less than 2 mm/yr of SW-NE short-
ening are accommodated across this sector of the Po Plain,
in agreement with other present-day stress indicators [Mon-
tone et al. 2012] and known active faults [Basili et al. 2008].
In the present study, we describe the GPS data used to study the coseismic deformation related to the May 20 and
29 mainshocks, and provide preliminary models of the two
seismic sources, as inverted from consensus GPS coseismic
deformation fields
The 2016–2017 earthquake sequence in Central Italy: macroseismic survey and damage scenario through the EMS-98 intensity assessment
In this paper we describe the macroseismic effects produced by the long and destructive seismic sequence that hit Central Italy from 24 August 2016 to January 2017. Starting from the procedure adopted in the complex field survey, we discuss the characteristics of the building stock and its classification in terms of EMS-98 as well as the issues associated with the intensity assessment due to the evolution of damage caused by multiple shocks. As a result, macroseismic intensity for about 300 localities has been determined; however, most of the intensities assessed for the earthquakes following the first strong shock on 24 August 2016, represent the cumulative effect of damage during the sequence. The earthquake parameters computed from the macroseismic datasets are compared with the instrumental determinations in order to highlight critical issues related to the assessment of macroseismic parameters of strong earthquakes during a seismic sequence. The results also provide indications on how location and magnitude computation can be strongly biased when dealing with historical seismic sequences.Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC)Published2407–24314T. Sismicità dell'Italia1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto5SR TERREMOTI - Convenzioni derivanti dall'Accordo Quadro decennale INGV-DPCJCR Journa
The RING GPS network: a research geodetic infrastructure to study plate boundary deformation in the Central Mediterranean
We present the INGV (Italian National Institute of Geophysics and Volcanology) geodetic research infrastructure
and related facilities, dedicated to the observation and monitoring of current deformation of the plate boundary
between Africa and Eurasia. The recent increase of continuous GPS (CGPS) stations in the Central Mediterranean
plate boundary zone offers the opportunity to study in detail the present-day kinematics of this actively deforming
region. For answering all the open questions related to this complex area, INGV deployed a permanent, integrated
and real-time monitoring CGPS network (RING) all over Italy. The RING network (http:/ring.gm.ingv.it) is now
constituted by more than 150 stations. All stations have high quality GPS monuments and most of them are
co-located with broadband or very broadband seismometers and strong motion sensors. The RING CGPS sites
acquire at 1Hz and 30s sampling rates (some of them acquire at 10 Hz) and are connected in real-time to the
INGV acquisition centers located in Roma and Grottaminarda. Real-time GPS data are transmitted using different
systems, such as satellite systems, Internet, GPRS/UMTS and wireless networks. The differentiation of data
transmission type and the integration with seismic instruments makes this network one of the most innovative
CGPS networks in Europe. Furthermore, the INGV data acquisition centers acquire, archive and analyze most
of the Italian CGPS stations managed by regional or national data providers (such as local Authorities and
nation-wide industries), integrating more than 350 stations of the CGPS scientific and commercial networks
existing in the Italian region. To manage data acquisition, storage, distribution and access we developed dedicated
facilities including new softwares for data acquisition and a web-based collaborative environment for management
of data and metadata. The GPS analysis is carried out with the three main geodetic-quality softwares used in the
GPS scientific community: Bernese GAMIT an GIPSY-OASIS. The resulting daily solutions are aligned to the
ITRF2005 reference frame. Stable plate reference frames are realized by minimizing the horizontal velocities at
sites on the Eurasia and Nubia plates, respectively. The different software-related solutions consistency RMS is
within 0.3 mm/yr (Avallone et al., 2010). The solutions are then evaluated with regard to the numerous scientific
motivations behind this presentation, ranging from the definition of strain distribution and microplate kinematics
within the plate boundary, to the evaluation of tectonic strain accumulation on active faults. The RING network
is strongly contributing to the definition of GPS velocity field in the Italian region, and now is able to furnish
a newly and up to date view of this actively deforming part of the Nubia-Eurasia plate boundary. INGV is now
aiming to make the RING (and integrated CGPS networks) data and related products publicly available for the
scientific community. We believe that our network represents an important reality in the framework of the EPOS
infrastructure and we strongly support the idea of an European research approach to data sharing among the
scientific community. We will present (a) the current CGPS site distribution, (b) the technological description of
the data acquisition, storage and distribution at INGV centers, (c) the results of CGPS data analysis, and (d) the
planned data access for the scientific community.PublishedVienna, Geophysical Research Abstracts
Vol. 13, EGU2011-8626, 20111.9. Rete GPS nazionale3.2. Tettonica attivaope
Regularity of harmonic discs in spaces with quadratic isoperimetric inequality
We study harmonic and quasi-harmonic discs in metric spaces admitting a uniformly local quadratic isoperimetric inequality for curves. The class of such metric spaces includes compact Lipschitz manifolds, metric spaces with upper or lower curvature bounds in the sense of Alexandrov, some sub-Riemannian manifolds, and many more. In this setting, we prove local Hölder continuity and continuity up to the boundary of harmonic and quasi-harmonic discs
The RING GPS network: a research geodetic infrastructure to study plate boundary deformation in the Central Mediterranean
We present the INGV (Italian National Institute of Geophysics and Volcanology) geodetic research infrastructure
and related facilities, dedicated to the observation and monitoring of current deformation of the plate boundary
between Africa and Eurasia. The recent increase of continuous GPS (CGPS) stations in the Central Mediterranean
plate boundary zone offers the opportunity to study in detail the present-day kinematics of this actively deforming
region. For answering all the open questions related to this complex area, INGV deployed a permanent, integrated
and real-time monitoring CGPS network (RING) all over Italy. The RING network (http:/ring.gm.ingv.it) is now
constituted by more than 150 stations. All stations have high quality GPS monuments and most of them are
co-located with broadband or very broadband seismometers and strong motion sensors. The RING CGPS sites
acquire at 1Hz and 30s sampling rates (some of them acquire at 10 Hz) and are connected in real-time to the
INGV acquisition centers located in Roma and Grottaminarda. Real-time GPS data are transmitted using different
systems, such as satellite systems, Internet, GPRS/UMTS and wireless networks. The differentiation of data
transmission type and the integration with seismic instruments makes this network one of the most innovative
CGPS networks in Europe. Furthermore, the INGV data acquisition centers acquire, archive and analyze most
of the Italian CGPS stations managed by regional or national data providers (such as local Authorities and
nation-wide industries), integrating more than 350 stations of the CGPS scientific and commercial networks
existing in the Italian region. To manage data acquisition, storage, distribution and access we developed dedicated
facilities including new softwares for data acquisition and a web-based collaborative environment for management
of data and metadata. The GPS analysis is carried out with the three main geodetic-quality softwares used in the
GPS scientific community: Bernese GAMIT an GIPSY-OASIS. The resulting daily solutions are aligned to the
ITRF2005 reference frame. Stable plate reference frames are realized by minimizing the horizontal velocities at
sites on the Eurasia and Nubia plates, respectively. The different software-related solutions consistency RMS is
within 0.3 mm/yr (Avallone et al., 2010). The solutions are then evaluated with regard to the numerous scientific
motivations behind this presentation, ranging from the definition of strain distribution and microplate kinematics
within the plate boundary, to the evaluation of tectonic strain accumulation on active faults. The RING network
is strongly contributing to the definition of GPS velocity field in the Italian region, and now is able to furnish
a newly and up to date view of this actively deforming part of the Nubia-Eurasia plate boundary. INGV is now
aiming to make the RING (and integrated CGPS networks) data and related products publicly available for the
scientific community. We believe that our network represents an important reality in the framework of the EPOS
infrastructure and we strongly support the idea of an European research approach to data sharing among the
scientific community. We will present (a) the current CGPS site distribution, (b) the technological description of
the data acquisition, storage and distribution at INGV centers, (c) the results of CGPS data analysis, and (d) the
planned data access for the scientific community
Pathogenic Connexin-31 Forms Constitutively Active Hemichannels to Promote Necrotic Cell Death
Mutations in Connexin-31 (Cx31) are associated with multiple human diseases including erythrokeratodermia variabilis (EKV). The molecular action of Cx31 pathogenic mutants remains largely elusive. We report here that expression of EKV pathogenic mutant Cx31R42P induces cell death with necrotic characteristics. Inhibition of hemichannel activity by a connexin hemichannel inhibitor or high extracellular calcium suppresses Cx31R42P-induced cell death. Expression of Cx31R42P induces ER stress resulting in reactive oxygen species (ROS) production, in turn, to regulate gating of Cx31R42P hemichannels and Cx31R42P induced cell death. Moreover, Cx31R42P hemichannels play an important role in mediating ATP release from the cell. In contrast, no hemichannel activity was detected with cells expressing wildtype Cx31. Together, the results suggest that Cx31R42P forms constitutively active hemichannels to promote necrotic cell death. The Cx31R42P active hemichannels are likely resulted by an ER stress mediated ROS overproduction. The study identifies a mechanism of EKV pathogenesis induced by a Cx31 mutant and provides a new avenue for potential treatment strategy of the disease
L’indagine macrosismica: metodologia, parametri del terremoto, questioni aperte
Subito dopo l’evento del 6 aprile 2009, come di consueto è stata realizzata una lunga e complessa indagine macrosismica, promossa dal gruppo operativo QUEST, che ha avuto inizialmente l’obiettivo di delimitare l’area di danneggiamento, a supporto delle attività di pronto intervento della Protezione Civile, e successivamente quello di classificare nel modo più accurato e capillare possibile, gli effetti prodotti dall’evento, particolarmente nelle aree danneggiate.
A questo scopo è stata prodotta una stima utilizzando la scala MCS (Sieberg, 1930); in un secondo momento è stata rifinita l’indagine per una cinquantina di località dell’area maggiormente danneggiata (Is MCS>VII), raccogliendo ed elaborando i dati in termini di scala macrosismica EMS98 (Grünthal, 1998).
Per la complessità e la dimensione dei problemi affrontati, questo terremoto ha costituito un banco di prova di grande importanza per la macrosismologia italiana.
In questo testo viene descritto il lavoro realizzato, discutendo in particolare alcuni aspetti che hanno messo alla prova le metodologie di indagine tradizionali (sistematiche irregolarità degli insediamenti monitorati, forti divergenze degli scenari di danno rispetto a quelli previsti dalle scale, difficile comparabilità con scenari storici, ecc.) e presentandone i risultati, in relazione ai parametri epicentrali che ne risultano e il loro contributo più diretto alla comprensione complessiva della sismicità dell’area
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