406 research outputs found
Carbon Dioxide Diffuse Emission from the Soil at Vesuvio and Campi Flegrei (Pozzuoli): Ten Years of Observations
Carbon dioxide flux from the soil is regularly monitored
in selected areas of Vesuvio and Solfatara (Campi Flegrei,
Pozzuoli) with the main aim of investigating if the
surface phenomena could provide information about
the processes occurring at depth. Surveyed areas include
15 fixed points around the rim of Vesuvio and 71
fixed points in the floor of Solfatara crater, where soil
CO2 flux is measured since 1998, at least once a month.
In addition, two automatic permanent stations, located
at Vesuvio and Solfatara, continually measure the CO2
flux and some environmental parameters that can potentially
influence the CO2 diffuse degassing.
We analysed, with statistical procedures, the feature
of the acquired signals, evaluating the spatial and temporal
variations of the CO2 degassing process.
Series acquired by continuous stations are characterized
by an annual periodicity that is related to the
typical periodicities of some meteorological parameters
(e.g., air temperature, air humidity, etc.). Such a kind of
signal permits to define the “reference” level of the CO2
degassing process that diffusely affects the flanks and
the base of the volcanoes.
Conversely, series of CO2 flux data arising from periodic
measurements over the arrays of Vesuvio and
Solfatara, are less dependent on external factors such
as meteorological parameters, local soil properties (porosity,
hydraulic conductivity) and topographic effects
(high or low ground). Therefore we argue that the longterm
trend of this signal contains the “best” possible
representation of the endogenous signal related to the
upflow of deep hydrothermal fluids. At Vesuvio and Solfatara,
the variations of these series have shown some correspondence with other physical changes of the volcanic systems
Thermal monitoring of hydrothermal activity by permanent infrared automatic stations: Results obtained at Solfatara di Pozzuoli, Campi Flegrei (Italy)
A permanent automatic infrared (IR) station was installed at Solfatara crater, the most active zone of Campi Flegrei caldera. After a positive in situ calibration of the IR camera, we analyze 2175 thermal IR images of the same scene from 2004 to 2007. The scene includes a portion of the steam heated hot soils of Solfatara. The experiment was initiated to detect and quantify temperature changes of the shallow thermal structure of a quiescent volcano such as Solfatara over long periods. Ambient temperature results as the main parameter affecting IR temperatures while air humidity and rain control image quality. A geometric correction of the images was necessary to remove the effects of slow movement of the camera. After a suitable correction the images give a reliable and detailed picture of the temperature changes, over the period October 2004 – January 2007, which suggests origin of the changes were linked to anthropogenic activity, vegetation growth and to the increase of the flux of hydrothermal fluids in the area of the hottest fumaroles. Two positive temperature anomalies were registered after the occurrence of two seismic swarms which affected the hydrothermal system of Solfatara in October 2005 and October 2006. It is worth noting that these signs were detected in a system characterized by a low level of activity with respect to systems affected by real volcanic crisis where more spectacular results will be expected. Results of the experiment show that this kind of monitoring system can be a suitable tool for volcanic surveillance
Risk of Guillain-Barré syndrome after 2010–2011 influenza vaccination
Influenza vaccination has been implicated in Guillain Barré Syndrome (GBS) although the evidence for this link is controversial. A case–control study was conducted between October 2010 and May 2011 in seven Italian Regions to explore the relation between influenza vaccination and GBS. The study included 176 GBS incident cases aged ≥18 years from 86 neurological centers. Controls were selected among patients admitted for acute conditions to the Emergency Department of the same hospital as cases. Each control was matched to a case by sex, age, Region and admission date. Two different analyses were conducted: a matched case–control analysis and a self-controlled case series analysis (SCCS). Case–control analysis included 140 cases matched to 308 controls. The adjusted matched odds ratio (OR) for GBS occurrence within 6 weeks after influenza vaccination was 3.8 (95 % CI: 1.3, 10.5). A much stronger association with gastrointestinal infections (OR = 23.8; 95 % CI 7.3, 77.6) and influenza-like illness or upper respiratory tract infections (OR = 11.5; 95 % CI 5.6, 23.5) was highlighted. The SCCS analysis included all 176 GBS cases. Influenza vaccination was associated with GBS, with a relative risk of 2.1 (95 % CI 1.1, 3.9). According to these results the attributable risk in adults ranges from two to five GBS cases per 1,000,000 vaccinations
Geochemical and biochemical evidence of lake overturn and fish-kill at Lake Averno, Italy.
Lake Averno is situated in the homonymous crater in the northwestern sector of the Campi Flegrei active
volcanic system in Campania region, Italy. In February 2005 a fish kill event was observed in the lake,
prompting a geochemical survey to ascertain the possible cause. In February 2005 a geochemical survey
revealed that the lake water was unstratified chemically and isotopically, presumable, as a result of lake
overturn. This fish-kill phenomenon was recorded at least two other times in the past. In contrast to the
February 2005 results, data collected in October 2005, shows the Lake Averno to be stratified, with an oxic
epilimnion (surface to 6 m) and an anoxic hypolimnion (6 m to lake bottom at about 33 m).
Chemical and isotopic composition of Lake Averno waters suggests an origin by mixing of shallow waters
with a Na-Cl hydrothermal component coupled with an active evaporation process. The isotopic composition
of Dissolved Inorganic Carbon, as well as the composition of the non-reactive dissolved gas species again
supports the occurrence of this mixing process.
Decreasing levels of SO4 and increasing levels of H2S and CH4 contents in lake water with depth, strongly
suggests anaerobic bacterial processes are occurring through decomposition of organic matter under anoxic
conditions in the sediment and in the water column. Sulfate reduction and methanogenesis processes coexist
and play a pivotal role in the anaerobic environment of the Lake Averno. The sulfate reducing bacterial
activity has been estimated in the range of 14-22 μmol.m-2.day-1.
Total gas pressure of dissolved gases ranges between 800 and 1400 mbar, well below the hydrostatic
pressure throughout the water column, excluding the possibility, at least at the survey time, of a limnic
eruption.
Vertical changes in the density of lake waters indicate that overturn may be triggered by cooling of
epilimnetic waters below 7°C. This is a possible phenomenon in winter periods if atmospheric temperatures
remain frosty for enough time, as occurred in February 2005.
The bulk of these results strongly support the hypothesis that fish kill was caused by a series of events that
began with the cooling of the epilimnetic waters with breaking of the thermal stratification, followed by lake
overturn and the rise of toxic levels of H2S from the reduced waters near the lake bottom
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
Stability Analysis of the LHC Cables for Transient Heat Depositions
The commissioning and the exploitation of the LHC require a good knowledge of the stability margins of the superconducting magnets with respect to beam induced heat depositions. Previous studies showed that simple numerical models are suitable to carry out stability calculations of multi-strands cables, and highlighted the relevance of the heat transfer model with the surrounding helium. In this paper we present a systematic scan of the stability margin of all types of LHC cables working at 1.9 Kagainst transient heat depositions. We specifically discuss the dependence of the stability margin on the parameters of the model, which provide an estimate of the uncertainty of the values quoted. The stability margin calculations have been performed using a zero-dimensional (0-D) numerical model, and a cooling model taking into account the relevant helium phases which may appear during a stability experiment: it includes Kapitza thermal resistance in superfluid He, boundary layer formation and heat transfer in He I, and considers the transition from nucleating boiling to film boiling during He gas formation
Novel anti-obesity quercetin-derived Q2 prevents metabolic disorders in rats fed with high-fat diet
Objective: Obesity is often accompanied by an increased morbidity and mortality due to an increase of the cardiovascular disease risk factors, diabetes mellitus and dyslipidemia. Research is constantly working on protective molecules against obesity. In the present study, a novel Quercetin derivative Q2 was synthesized to overcome the poor bioavailability and low stability of Quercetin, a natural flavonoid with antioxidative and antiobesity properties.
Methods: Rats were fed (12ws) with normodiet (fat:INS; 6.2%), High Fat Diet (fat:60%), HFDINS; +INS; Q2 in water (500INS; nM). Metabolic and anthropometric parameters were measured. 3T3-L1 preadipocytes were incubated with Q2 (1-25μM) and the differentiation program was evaluated by lipid accumulation through ORO staining. Gene and protein expression levels were assessed by RT-PCR and Western blot analysis.
Results: Compared to HFD, HFDINS; +INS; Q2 rats showed reduced body weight, abdominal obesity, dyslipidemia and improved glucose tolerance. This is associated to lower adipose and liver modifications compared to hypertrophy and steatosis observed in HFD. In 3T3-L1 cells, lipid accumulation was significantly impaired by treatment with Q2. Indeed, Q2 significantly decreased the expression of the main adipogenic markers, c/EBPα and PPARγ both at mRNA and protein level.
Conclusions: Our results indicate that Q2 markedly decreases differentiation of 3T3-L1 preadipocytes and contributes to prevent metabolic disorders as well as adipose and liver alterations typical of severe obesity induced by a HFD
Personalità, pensiero e abbandono scolastico: tra ricerca empirica e riflessione teorica.
Long term variations at Campi Flegrei (Italy) volcanic system highlighted by the monitoring of hydrothermal activity
Long time-series of chemical composition of fumaroles and of soil CO2 flux reveal that important variations in the
activity of Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000-
2008 period. A continuous increase of the CO2 concentration and a general decrease of the CH4 concentration are
interpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor in
CH4, hosted by the hydrothermal system. Contemporaneously the H2O-CO2-He-N2 gas system shows remarkable
compositional variations in the samples collected after July 2000 with respect to the previous ones, indicating the
progressive arrival at the surface of a magmatic component different from that involved in the 1983-84 bradyseism.
The change starts in 2000 concurrently with the occurrence of relatively deep long periods seismic events which, in
our interpretation, were the indicator of the opening of an easy pathway for the transfer of magmatic fluids towards
the shallower, brittle domain hosting the hydrothermal system. Since 2000 this magmatic gas source is active and
causes ground deformations, seismicity as well as the expansion of the area interested by diffuse soil degassing of
deeply derived CO2
- …