543 research outputs found
Oxidative potential associated with urban aerosol deposited into the respiratory system and relevant elemental and ionic fraction contributions
Size-segregated aerosol measurements were carried out at an urban and at an industrial site. Soluble and insoluble fractions of elements and inorganic ions were determined. Oxidative potential (OP) was assessed on the soluble fraction of Particulate Matter (PM) by ascorbic acid (AA), dichlorofluorescein (DCFH) and dithiothreitol (DTT) assays. Size resolved elemental, ion and OP doses in the head (H), tracheobronchial (TB) and alveolar (Al) regions were estimated using the Multiple-Path Particle Dosimetry (MPPD) model. The total aerosol respiratory doses due to brake and soil resuspension emissions were higher at the urban than at the industrial site. On the contrary, the doses of anthropic combustion tracers were generally higher at the industrial site. In general, the insoluble fraction was more abundantly distributed in the coarse than in the fine mode and vice versa for the soluble fraction. Consequently, for the latter, the percent of the total respiratory dose deposited in TB and Al regions increased. Oxidative potential assay (OPAA) doses were distributed in the coarse region; therefore, their major contribution was in the H region. The contribution in the TB and Al regions increased for OPDTT and OPDCFH
Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei)
Long time series of fluid pressure and temperature within a hydrothermal
system feeding the Solfatara fumaroles are investigated here, on the basis
of the chemical equilibria within the CO2-H2O-H2-CO gas system. The
Pisciarelli fumarole external to Solfatara crater shows an annual cycle of
CO contents that indicates the occurrence of shallow secondary processes
that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova
fumaroles located inside Solfatara crater do not show evidence of
secondary processes, and their compositional variations are linked to the
temperature–pressure changes within the hydrothermal system. The
agreement between geochemical signals and the ground movements of the
area (bradyseismic phenomena) suggests a direct relationship between the
pressurization process and the ground uplift. Since 2007, the gas
geoindicators have indicated pressurization of the system, which is most
probably caused by the arrival of deep gases with high CO2 contents in
the shallow parts of the hydrothermal system. This pressurization process
causes critical conditions in the hydrothermal system, as highlighted by
the increase in the fumarole temperature, the opening of new vents, and
the localized seismic activity. If the pressurization process continues with
time, it is not possible to rule out the occurrence of phreatic explosions
Probing the Ultimate Limit of Fiber-Optic Strain Sensing
Enhanced Strain Sensitivity
The ability to measure tiny deformations in length is useful for many disciplines, from largescale structural engineering to DNA analysis with optical tweezers. The most sensitive strain sensors are those using optical interferometers, which can detect small changes at the scale of visible wavelengths. Using an optical frequency comb to stabilize the output of a diode laser, and as a highly accurate ruler to determine small changes in length of an optic fiber sensor,
Gagliardi
et al.
(p.
1081
, published online 28 October) showed that sensitivity can be enhanced by several orders of magnitude. Such combined technology should provide for a new generation of high-performance sensors
From Megabits to CPU Ticks: Enriching a Demand Trace in the Age of MEC
All the content consumed by mobile users, be it a web page
or a live stream, undergoes some processing along the way; as an example,
web pages and videos are transcoded to fit each device’s screen.
The recent multi-access edge computing (MEC) paradigm envisions
performing such processing within the cellular network, as opposed to
resorting to a cloud server on the Internet. Designing a MEC network,
i.e., placing and dimensioning the computational facilities therein, requires
information on how much computational power is required to
produce the contents needed by the users. However, real-world demand
traces only contain information on how much data is downloaded. In this
paper, we demonstrate how to enrich demand traces with information
about the computational power needed to process the different types of
content, and we show the substantial benefit that can be obtained from
using such enriched traces for the design of MEC-based networks.This work is supported by the European Commission through the H2020
projects 5G-TRANSFORMER (Project ID 761536) and 5G-EVE (Project ID
815074)
Improving monitoring techniques by exploiting TerraSAR-X data: an application to Campi Flegrei (Naples, Italy)
Geodetic monitoring of the Neapolitan Volcanic District, including the Campi Flegrei caldera on the west of the
city of Naples (Italy), is carried out via an integration between ground based networks and space-borne DInSAR
techniques, exploiting the SAR sensors onboard ERS1-2 and ENVISAT satellites. This allowed, for instance, to
follow the time evolution of the small uplift events which took place in 2000 and 2005-2006. Unfortunately, the
use of the ENVISAT C-band could result sometimes in no information when dealing with very low deformation
rates, as in the 2005-2006 case, when only continuous ground stations were able to detect the very beginning of
the uplift event.
To overcome this problem, from December 2009 we decided to use an high resolution SAR sensor operating in
the X band, i.e. TerraSAR-X from DLR.
TerraSAR-X High Resolution Spotlight scenes covering the main part of the Campi Flegrei caldera and centred on
the Solfatara crater were used for a DInSAR analysis, using the GENESIS DLR’s software. The first two scenes
(Dec. 15 and 26) were acquired with a temporal baseline of only one repetition cycle (11 days) and formed an
interferogram with a very small perpendicular baseline (16.5 m).
Apart from some minor atmospheric effects, the interferogram shows a small but clear deformation signal in the
Pisciarelli area, close to the east side of the Solfatara crater. The ellipse shaped uplift area extends approximately
30 meters in E-W and 20 meters in N-S directions and the maximum deformation is up to 10 mm in the centre of
the uplifted area.
The availability of a new scene (06/01/2010) allowed three possible combinations.
The deformation event highlighted by this analysis is consistent with geochemical observations carried out in
Pisciarelli by INGV-OV.
Pisciarelli area is seat of a fumarolic field systematically monitored in the frame of the volcanic surveillance of
the Campi Flegrei caldera. Two field surveys highlighted that, during the period of SAR images acquisition, a
new and strong fumarolic vent appeared in the centre of the uplifted area. In fact the vent, firstly observed on
Dec. 21, was absent on Dec. 16. The two independent observations, field surveys and SAR data, suggest that the
opening of the fumarolic vent was preceded by the pressurization of a small part of the fumarolic field highlighted
by the documented uplift. The correlation between the dynamics of the fumarolic field and the deformation
signal is confirmed by the fact that in the 26/12/2009-06/01/2010 interferogram the deformation signal is no more
detectable.
Finally, this case proves the high potentiality of TerraSAR-X High Resolution Spotlight data in monitoring
volcanic activity with a resolution suitable for detecting also minor, but possibly dangerous, changes of the
systems, as it could be in the early recognition of the signals generated by impending phreatic eruptions.
TerraSAR-X High Resolution Spotlight acquisitions will continue every cycle and PS-InSAR and SBAS algorithms
will be applied to carefully monitor any further changes in the activity of the Campi Flegrei volcanic system
Long time-series of chemical and isotopic compositions of Vesuvius fumaroles: evidence for deep and shallow processes
Long time-series of chemical and isotopic compositions of Vesuvius
fumaroles were acquired in the framework of the volcanic surveillance in
the 1998-2010 period. These allow the identification of processes that
occur at shallow levels in the hydrothermal system, and variations that are
induced by deep changes in volcanic activity. Partial condensation
processes of fumarolic water under near-discharge conditions can explain
the annual 18O and deuterium variabilities that are observed at Vesuvius
fumaroles. Significant variations in the chemical compositions of
fumaroles occurred over the 1999-2002 period, which accompanied the
seismic crisis of autumn 1999, when Vesuvius was affected by the most
energetic earthquakes of its last quiescence period. A continuous increase
in the relative concentrations of CO2 and He and a general decrease in the
CH4 concentrations are interpreted as the consequence of an increment in
the relative amount of magmatic fluids in the hydrothermal system. Gas
equilibria support this hypothesis, showing a PCO2 peak that culminated in
2002, increasing from values of ~40 bar in 1998 to ~55-60 bar in 2001-
2002. We propose that the seismic crisis of 1999 marked the arrival of the
magmatic fluids into the hydrothermal system, which caused the observed
geochemical variations that started in 1999 and culminated in 2002
New insights into Mt. Vesuvius hydrothermal system and its dynamic based on a critical review of seismic tomography and geochemical features
The seismic velocity and attenuation tomography images, calculated inverting
respectively P-wave travel times and amplitude spectra of local
VT quakes at Mt. Vesuvius have been reviewed and graphically represented
using a new software recently developed using Mathematica8TM.
The 3-D plots of the interpolated velocity and attenuation fields obtained
through this software evidence low-velocity volumes associated with high
attenuation anomalies in the depth range from about 1 km to 3 km below
the sea level. The heterogeneity in the distribution of the velocity and attenuation
values increases in the volume centred around the crater axis
and laterally extended about 4 km, where the geochemical interpretation
of the data from fumarole emissions reveals the presence of a hydrothermal
system with temperatures as high as 400-450°C roughly in the same
depth range (1.5 km to 4 km). The zone where the hydrothermal system
is space-confined possibly hosted the residual magma erupted by Mt. Vesuvius
during the recent eruptions, and is the site where most of the seismic
energy release has occurred since the last 1944 eruption
Long Time Series Of Fumarolic Compositions At Volcanoes: The Key To Understand The Activity Of Quiescent Volcanoes
Long time series of fumarolic chemical and isotopic
compositions at Campi Flegrei, Vulcano, Panarea,
Nisyros and Mammoth volcanoes highlight the occurrence
of mixing processes among magmatic and hydrothermal
fluids. At Campi Flegrei temperatures of
about 360°C of the hydrothermal system are inferred by
chemical and isotopic geoindicators. These high temperatures
are representative of a deep zone where magmatic
gases mix with hydrothermal liquids forming the gas plume feeding the fumaroles. Similar mixing processes
between magmatic fluids and a hydrothermal
component of marine origin have been recognized at
Vulcano high temperature fumaroles. In both the system
a typical ‘andesitic’ water type composition and high
CO2 contents characterizes the magmatic component.
Our hypothesis is that pulsing injections of these CO2-
rich magmatic fluids at the bottom of the hydrothermal
systems trigger the bradyseismic crises, periodically
affecting Campi Flegrei, and the periodical volcanic
unrest periods of Vulcano. At Campi Flegrei a strong
increase of the fraction of the magmatic component
marked the bradyseismic crisis (seismicity and ground
uplift) of 1982-84 and four minor episodes occurred in
1989, 1994 and 2000 and 2006. Increases of the magmatic
component in the fumaroles of Vulcano were recorded
in 1979-1981, 1985, 1988, 1996, 2004 and 2005
concurrently with anomalous seismic activity. Physicalnumerical
simulations of the injection of hot, CO2 rich
fluids at the base of a hydrothermal system, asses the
physical feasibility the process. Ground deformations,
gravitational anomalies and seismic crisis can be well
explained by the complex fluid dynamic processes
caused by magma degassing episodes. Sporadic data
on the fumaroles of other volcanoes, for example Panarea,
Nisyros (Greece), Mammoth (California), suggest
that magma degassing episodes frequently occur in
dormant volcanoes causing volcanic unrest processes
not necessarily linked to magma movement but rather
to pulsating degassing processes from deep pressurized,
possibly stationary, magma bodies
Performance Analysis of C-V2I-Based Automotive Collision Avoidance
One of the key applications envisioned for C-V2I (Cellular Vehicle-to-Infrastructure) networks pertains to safety on the road. Thanks to the exchange of Cooperative Awareness Messages (CAMs), vehicles and other road users (e.g., pedestrians) can advertise their position, heading and speed and sophisticated algorithms can detect potentially dangerous situations leading to a crash. In this paper, we focus on the safety application for automotive collision avoidance at intersections, and study the effectiveness of its deployment in a C-V2I-based infrastructure. In our study, we also account for the location of the server running the application as a factor in the system design. Our simulation-based results, derived in real-world scenarios, provide indication on the reliability of algorithms for car-to-car and car-to-pedestrian collision avoidance, both when a human driver is considered and when automated vehicles (with faster reaction times) populate the streets.This work was partially supported by TIM through the research contract “Multi-access Edge Computing”, and by the European Commission through the H2020 5GTRANSFORMER
project (Project ID 761536
Carbon dixide emission in Italy: Shallow crustal sources or subduction related fluid recycling?
Anomalous non-volcanic CO2 release in central and
southern Italy has been highlighted by ten years of detailed
investigations on Earth degassing processes. Two regional
degassing structures are located in the Tyrrhenian sector
where more then 200 emissions of CO2 are located and has
been recently included in the first web based catalogue of
degassing sites (http://googas.ov.ingv.it). The total amount of
CO2 released by the two structures were evaluated to be >
2×1011 mol a-1 ( >10% of the estimated global volcanic CO2
emission). The anomalous flux of CO2 suddenly disappears in
the Apennine in correspondence of a narrow band where most
of the Italian seismicity concentrates. Here, at depth, the gas
accumulates in crustal traps generating CO2 overpressurised
reservoirs. These overpressured structures are, in our opinion,
one of the main cause of Apennine earthquake activation
processes. The results of these investigations suggested that
Earth degassing in Italy may have an active primary role in the
geodynamics of the region. What is the origin of gas? The
large extension of the degassing structures and petrologic data
suggested that the main source of gas is a mantle
metasomatised by the fluids produced in the subdacted slabs.
However, has been also hypothesised the presence of localised
crustal source of the gas. This matter will be discussed on the
base of unpublished isotopic data of the main gas emissions
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