1,302 research outputs found
Geochemistry of fluids discharged over the seismic area of the Southern Apennines (Calabria region, Southern Italy): Implications for Fluid-Fault relationships
The first comprehensive geochemical data-set of the fluids circulating over a 14,000 km2-wide seismicprone
area of the Southern Apennines, Calabria Region (Italy), is presented here. The geochemical investigations
were carried out with the twofold aim of constraining the origin and interactions of the circulating
fluids and to investigate possible relationships with local faults. Sixty samples of both thermal and cold
waters were collected, from which the dissolved gases were extracted. The geochemical features of the
water samples display different types and degrees of waterârock interactions, irrespective of the outlet
temperature. The calculated equilibrium temperatures of the thermal waters (60â160 C) and the low heat
flow of thewhole study area, are consistent with a heating process due to deep water circulation and rapid
upflow through lithospheric structures. The composition of the dissolved gases reveals that crustal-originating
gases (N2 and CO2-dominated) feed all the groundwaters. The 3He/4He ratios of the dissolved He, in
the range of 0.03â0.22Rac for the thermal waters and 0.05â0.63Rac for the cold waters (Rac = He isotope
ratio corrected for atmospheric contamination), are mainly the result of a two-component (radiogenic
and atmospheric) mixing, although indications of mantle-derived He are found in some cold waters. As
the study area had been hit by 18 of the most destructive earthquakes (magnitude ranging from 5.9 to
7.2) occurring over a 280-a time span (1626â1908) in the Southern Apennines, the reported results on
the circulating fluids may represent the reference for a better inside knowledge of the fault-fluid relationships
and for the development of long-term geochemical monitoring strategies for the area
HELIUM ISOTOPES AND TECTONICS IN SOUTHERN ITALY
Geodynamic evolution of southern Italy can
be understood within the framework of the Mediterranean-
Alpine System. Subduction of a plate along the Sicily-
Calabrian forearc under the Tyrrhenian Sea has been suggested
by many geophysicists, although it is not yet confirmed
and remains somewhat controversial. Helium isotope
ratios provide useful information on the geotectonic structure
of the region. We report here the 3He/4He ratios of
terrestrial gas samples from southern Italy. The observed
3He/4He ratios are relatively high in the Eolian volcanic arc
region and low in the other areas. Dichotomous explanations
are presented. Firstly volcanic arc-forearc hypothesis
suggests the subduction along the Sicily-Calabrian forearc.
Secondly horizontal transport hypothesis is described based
on the relationship between the ratios and radial distance
from the recent spreading basin in Southern Tyrrhenian Sea
Desempenho produtivo de ovinos deslanados da raça Santa InĂȘs no Estado do PiauĂ.
Desempenho reprodutivo; Peso das matrizes; Peso das crias.bitstream/item/35788/1/Bol19.pd
Remote detection of fumarolic gas chemistry at Vulcano, Italy, using an FT-IR spectral radiometer
An infrared absorption spectroscopy remote sensing technique was used to determine the S02/HCl ratio in fumarolic
plumes at Vulcano, Italy. The measurements were made from the southern crater rim of Fossa Grande Crater, about 400 m
from the fumarolic area in the crater. Infrared absorption spectra of HCl and SO, were observed for four fumaroles a few
tens of metres apart using the hot fumarolic surface as an infrared light source. The measured S02/HCl ratios in the FA,
F47, FW and lower parti of the F21 fumaroles were 4.5-5.4, 3.5, 9.5-11.2 and 5.8 respectively. The S02/HCl ratio of the
FA fumarole was higher than that of the gas collected directly in the fumarolic vent (S02/HCl ratio = 2.9), and was closer
to the S~,,,,,,/HCl ratio (= 4.6) of the collected gas. Our results show that the SO,/HCl ratios of two fumaroles only a few
tens of metres apart exhibits differences of about twofold. This suggests that this remote monitoring technique is capable of
detecting spatial distribution in the S02/HCl ratios of volcanic plumes. Because temporal variations in S/Cl ratios can
provide precursory signals for volcanic eruptions [l-31, this remote sensing technique can used efficiently for evaluation of
volcanic activity
Effective Edge-Fault-Tolerant Single-Source Spanners via Best (or Good) Swap Edges
Computing \emph{all best swap edges} (ABSE) of a spanning tree of a given
-vertex and -edge undirected and weighted graph means to select, for
each edge of , a corresponding non-tree edge , in such a way that the
tree obtained by replacing with enjoys some optimality criterion (which
is naturally defined according to some objective function originally addressed
by ). Solving efficiently an ABSE problem is by now a classic algorithmic
issue, since it conveys a very successful way of coping with a (transient)
\emph{edge failure} in tree-based communication networks: just replace the
failing edge with its respective swap edge, so as that the connectivity is
promptly reestablished by minimizing the rerouting and set-up costs. In this
paper, we solve the ABSE problem for the case in which is a
\emph{single-source shortest-path tree} of , and our two selected swap
criteria aim to minimize either the \emph{maximum} or the \emph{average
stretch} in the swap tree of all the paths emanating from the source. Having
these criteria in mind, the obtained structures can then be reviewed as
\emph{edge-fault-tolerant single-source spanners}. For them, we propose two
efficient algorithms running in and time, respectively, and we show that the guaranteed (either
maximum or average, respectively) stretch factor is equal to 3, and this is
tight. Moreover, for the maximum stretch, we also propose an almost linear time algorithm computing a set of \emph{good} swap edges,
each of which will guarantee a relative approximation factor on the maximum
stretch of (tight) as opposed to that provided by the corresponding BSE.
Surprisingly, no previous results were known for these two very natural swap
problems.Comment: 15 pages, 4 figures, SIROCCO 201
Effect of COVID-19 isolation measures on physical activity of children and their parents, and role of the family environment: a cross-sectional study
Background. The rigorous isolation measures due to the COVID-19 pandemic seriously impacted childrenâs lifestyles. A descriptive cross-sectional study was carried out to collect and analyze information about physical activity habits of children and their parents during the social distancing period resulting from the COVID-19 pandemic.
Methods. An online questionnaire was administered to 363 families (507 children aged 5-13) recruited by convenience sampling, asking for physical activity type and frequency before, during, and after the lockdown period (9th March - May 3rd 2020), education, outdoor spaces, and childrenâs weight gain perception.
Results. Results show a remarkable decrease in childrenâs physical activity during lockdown (88.9 vs
39.8% active children) associated with older age and low availability of outdoor spaces (p<0.001). Parentsâ physical activity was related to educational level, and a slight but significant correlation between parentsâ education and childrenâs physical activity was found, especially with fatherâs university degree (p<0.05).
Active mothers significantly influenced childrenâs physical activity during the lockdown, especially if not
engaged in smart working. The return to an active lifestyle by children did not reach previous levels (75.9% active children) and was directly related to parentâs physical activity. Finally, the risk of weight gain was lower in active children during the lockdown (OR = 0.46; p<0.001).
Conclusions. This work highlights the importance of physical activity during a pandemic event to prevent the risk of gaining weight, and underlines the relevance of the entire family system as a source of promotion of healthy behaviors in children
Atmospheric particulate matter (PM) effect on the growth of Solanum lycopersicum cv. Roma plants
This study shows the direct effect of atmospheric particulate matter on plant growth. Tomato (Solanum lycopersicum L.) plants were grown for 18. d directly on PM10 collected on quartz fiber filters. Organic and elemental carbon and polycyclic aromatic hydrocarbons (PAHs) contents were analyzed on all the tested filters. The toxicity indicators (i.e., seed germination, root elongation, shoot and/or fresh root weight, chlorophyll and carotenoids content) were quantified to study the negative and/or positive effects in the plants via root uptake. Substantial differences were found in the growth of the root apparatus with respect to that of the control plants. A 17-58% decrease of primary root elongation, a large amount of secondary roots and a decrease in shoot (32%) and root (53-70%) weights were found. Quantitative analysis of the reactive oxygen species (ROS) indicated that an oxidative burst in response to abiotic stress occurred in roots directly grown on PM10, and this detrimental effect was also confirmed by the findings on the chlorophyll content and chlorophyll-to-carotenoid ratio
Inferences on physico-chemical conditions and gas-water interaction by new quantitative approaches: The case of Panarea (Italy)
We have developed two new quantitative approaches to
calculate temperatures in hydrothermal reservoirs by using the
CO2-CH4-CO-H2 gaseous system and to model selective
dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh
and/or air saturated seawater. The anomalous outgassing
starting November 2003 from the submarine exhalative
system offshore Panarea island (Italy), was the occasion to
apply such approaches to the extensive collection of volcanic
gases.
Gas geothermometry suggest the presence of a deep
geothermal system at temperature up to 350°C and about 12
mol% CO2 in the vapor, which feeds the submarine emissions.
Based on the fractional dissolution model, the rising
geothermal vapor interacts with air-saturated seawater at low
depths, dissolving 30-40% CO2 and even more H2S,
modifying the pH of the aqueous solution and stripping the
dissolved atmospheric volatiles (N2, Ne). Interaction of the
liquid phase of the thermal fluids with country rocks, as well
extensive mixing with seawater, have been also recognized
and quantified.
The measured output of hydrothermal fluids from Panarea
exhalative field [1] accounts for the involvement of volatiles
from an active degassing magma, nonetheless the climax of
the investigated phenomenon is probably overcome and the
system is new tending towards a steady-state. Our quantitative
approaches allow us to monitor the geochemical indicators of
the geothermal physico-chemical conditions and their
potential evolution towards phreatic events or massive gas
releases, which certainly are the main hazards to be expected
in the area. The event at Panarea has in fact highlighted how
hydrothermal systems can exhibit dramatic and sudden
changes of their physico-chemical conditions and rate of fluid
release, as a response to variable activity of feeding magmatic
systems
The Benthic Boundary Layer: geochemical and oceanographic data from the GEOSTAR-2 observatory
Geochemical and oceanographic data, acquired throughout 6 months by the GEOSTAR-2 benthic observatory in southern Tyrrhenian Sea, evidenced ocean-lithosphere interactions in the 1900-m deep Benthic Boundary Layer (BBL), distinguishing two water masses with different origin and, possibly, benthic residence time. Gas concentration, helium isotopic ratios, radioactivity, temperature, salinity and vertical component of the current converged towards the indication of a BBL characterised by a colder and fresher western water (WW), which is episodically displaced by the cascading of the warmer and saltier Eastern Overflow Water (EOW). The benthic WW has higher concentration of geochemical tracers diffusing from the seafloor sediments. The data set shows the potential of long-term, continuous and multiparametric monitoring in providing unique information which cannot be acquired by traditional, short-term or single-sensor investigations
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