564 research outputs found
Coulomb effects in tunneling through a quantum dot stack
Tunneling through two vertically coupled quantum dots is studied by means of
a Pauli master equation model. The observation of double peaks in the
current-voltage characteristic in a recent experiment is analyzed in terms of
the tunnel coupling between the quantum dots and the coupling to the contacts.
Different regimes for the emitter chemical potential indicating different peak
scenarios in the tunneling current are discussed in detail. We show by
comparison with a density matrix approach that the interplay of coherent and
incoherent effects in the stationary current can be fully described by this
approach.Comment: 6 pages, 6 figure
Volcanic Risk System (SRV): ASI Pilot Project to Support The Monitoring of Volcanic Risk In Italy by Means of EO Data
The ASI-SRV(Sistema Rischio Vulcanico) project
started at the beginning of the 2007 is funded by the Italian
Space Agency (ASI) in the frame of the National Space Plan
2003-2005 under the Earth Observations section for natural
risks management. Coordinated by the Istituto Nazionale di
Geofisica e Vulcanologia (INGV), which is responsible at national
level for the volcanic monitoring, the project has as main
objective to develop a pre-operative system based on EO data
and ground measurements integration to support the volcanic
risk monitoring of the Italian Civil Protection Department. The
project philosophy is to implement specific modules which allow
to process, store and visualize through Web GIS tools EO derived
parameters considering three activity phases: 1) knowledge and
prevention; 2) crisis; 3) post crisis. In order to combine
effectively the EO data and the ground networks measurements
the system will implement a multi-parametric analysis tool,
which represents and unique tool to analyze contemporaneously
a large data set of data in “near real time”. The SRV project will
be tested his operational capabilities on three Italian Volcanoes:
Etna,Vesuvio and Campi Flegrei
Volcanic Risk System (SRV): ASI Pilot Project to Support The Monitoring of Volcanic Risk In Italy by Means of EO Data
The ASI-SRV(Sistema Rischio Vulcanico) project
started at the beginning of the 2007 is funded by the Italian
Space Agency (ASI) in the frame of the National Space Plan
2003-2005 under the Earth Observations section for natural
risks management. Coordinated by the Istituto Nazionale di
Geofisica e Vulcanologia (INGV), which is responsible at national
level for the volcanic monitoring, the project has as main
objective to develop a pre-operative system based on EO data
and ground measurements integration to support the volcanic
risk monitoring of the Italian Civil Protection Department. The
project philosophy is to implement specific modules which allow
to process, store and visualize through Web GIS tools EO derived
parameters considering three activity phases: 1) knowledge and
prevention; 2) crisis; 3) post crisis. In order to combine
effectively the EO data and the ground networks measurements
the system will implement a multi-parametric analysis tool,
which represents and unique tool to analyze contemporaneously
a large data set of data in “near real time”. The SRV project will
be tested his operational capabilities on three Italian Volcanoes:
Etna,Vesuvio and Campi Flegrei.I.N.G.V. - O.V. SEZIONE DI NAPOLI
I.R.E.A. - C.N.R.
E.S.A.
A.S.I.PublishedNapoli1.10. TTC - Telerilevamentoope
Volcanic Risk System (SRV): ASI Pilot Project to Support The Monitoring of Volcanic Risk In Italy by Means of EO Data
The ASI-SRV(Sistema Rischio Vulcanico) project
started at the beginning of the 2007 is funded by the Italian
Space Agency (ASI) in the frame of the National Space Plan
2003-2005 under the Earth Observations section for natural
risks management. Coordinated by the Istituto Nazionale di
Geofisica e Vulcanologia (INGV), which is responsible at national
level for the volcanic monitoring, the project has as main
objective to develop a pre-operative system based on EO data
and ground measurements integration to support the volcanic
risk monitoring of the Italian Civil Protection Department. The
project philosophy is to implement specific modules which allow
to process, store and visualize through Web GIS tools EO derived
parameters considering three activity phases: 1) knowledge and
prevention; 2) crisis; 3) post crisis. In order to combine
effectively the EO data and the ground networks measurements
the system will implement a multi-parametric analysis tool,
which represents and unique tool to analyze contemporaneously
a large data set of data in “near real time”. The SRV project will
be tested his operational capabilities on three Italian Volcanoes:
Etna,Vesuvio and Campi Flegrei
Recent deformation at Campi Flegrei caldera (Italy) detected by DinSar and leveling techniques
The Campi Flegrei caldera, a volcanic and densely populated area located to the west
of Napoli (Italy), was characterized by rapid ground deformation during 1970-72 and
1982-84, for a total amount of 3.5 m in the city of Pozzuoli. Since 1985 a slow deflation
was active, with episodic microcrises of uplifts.
A new and consistent uplift event is now going on, beginning in November 2004, as
revealed by spatial and terrestrial geodetic techniques.
In particular, we adopt almost all the available ENVISAT ASAR data acquired from
both ascending and descending orbits during 2002-2006, to generate mean deformation
velocity maps and time series with spatial resolution of about 100 m. The maps
are computed following the Small BAseline Subset (SBAS) approach (Berardino et
al., 2002), that implements an appropriate combination of differential interferograms
generated from SAR data pairs (60 SAR images for this work).
In addition to satellite observations, we show data from the high precision levelling network of the INGV-Osservatorio Vesuviano, consisting in about 320 benchmarks.
Levelling measurements are regularly carried out on both the whole network and along
the coast line; in case of a bradyseismic crisis, the temporal sampling is strongly increased.
Both DInSAR and levelling data evidence the maximum value of the vertical displacement
near the city of Pozzuoli.
We model the observed deformation by means of 3D pressurized point-source and
extended source, performing inversions to constrain their shape and location. The resulting
sources are also compared with that inverted for the 1982-84 unrest.UnpublishedWienope
Recent deformation at Campi Flegrei caldera (Italy) detected by DinSar and leveling techniques
The Campi Flegrei caldera, a volcanic and densely populated area located to the west
of Napoli (Italy), was characterized by rapid ground deformation during 1970-72 and
1982-84, for a total amount of 3.5 m in the city of Pozzuoli. Since 1985 a slow deflation
was active, with episodic microcrises of uplifts.
A new and consistent uplift event is now going on, beginning in November 2004, as
revealed by spatial and terrestrial geodetic techniques.
In particular, we adopt almost all the available ENVISAT ASAR data acquired from
both ascending and descending orbits during 2002-2006, to generate mean deformation
velocity maps and time series with spatial resolution of about 100 m. The maps
are computed following the Small BAseline Subset (SBAS) approach (Berardino et
al., 2002), that implements an appropriate combination of differential interferograms
generated from SAR data pairs (60 SAR images for this work).
In addition to satellite observations, we show data from the high precision levelling network of the INGV-Osservatorio Vesuviano, consisting in about 320 benchmarks.
Levelling measurements are regularly carried out on both the whole network and along
the coast line; in case of a bradyseismic crisis, the temporal sampling is strongly increased.
Both DInSAR and levelling data evidence the maximum value of the vertical displacement
near the city of Pozzuoli.
We model the observed deformation by means of 3D pressurized point-source and
extended source, performing inversions to constrain their shape and location. The resulting
sources are also compared with that inverted for the 1982-84 unrest
Monitoring of Land Subsidence in Ravenna Municipality Using Integrated SAR - GPS Techniques: Description and First Results
The Emilia Romagna Region (N-E Italy) and in particular the Adriatic Sea coastline of Ravenna, is affected by a noticeable subsidence that started in the 1950s, when the exploitation of on and off-shore methane reservoirs began, along with the pumping of groundwater for industrial uses. In such area the current subsidence rate, even if lower than in the past, reaches the -2 cm/y. Over the years, local Authorities have monitored this phenomenon with different techniques: spirit levelling, GPS surveys and, more recently, Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques, confirming the critical situation of land subsidence risk. In this work, we present the comparison between the results obtained with DInSAR and GPS techniques applied to the study of the land subsidence in the Ravenna territory. With regard to the DInSAR, the Small Baseline Subset (SBAS) and the Coherent Pixel Technique (CPT) techniques have been used. Different SAR datasets have been exploited: ERS-1/2, ENVISAT, TerraSAR-X and Sentinel-1. Some GPS campaigns have been also carried out in a subsidence prone area. 3D vertices have been selected very close to existing persistent scatterers in order to link the GPS measurement results to the SAR ones. GPS data were processed into the International reference system and the comparisons between the coordinates, for the first 6 months of the monitoring, provided results with the same trend of the DInSAR data, even if inside the precision of the method
Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire
Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of ±0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires
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