A density-dependent numerical model was set up to quantify the actual and future (2050) salinization of a coastal aquifer in the Po Delta (Italy). SEAWAT 4.0 was used for this purpose, while PEST was ...used for automatic inverse parameter calibration. The use of high-resolution multi-level sampling allowed obtaining insights in the salinity stratification within the aquifer and on the vertical fluxes induced by the reclamation drainage network. The calibrated model was employed to build up a scenario investigating the effects of the projected relative sea level rise on groundwater salinity by 2050. This scenario allowed to identify the zones that resulted more affected by the relative sea level rise and to quantify the increase in salinization of groundwater, the salt loads export towards surface waters and the changing volumes of freshwater. Results show that the Po Delta will experience a significant salinization by 2050 and that the major cause is autonomous salinization via seepage of saline groundwater rather than enhanced seawater intrusion due to sea level rise.
•The conceptual models gained with Integrated Depth Sampling and Multi-Level Sampling are compared.•Very different results are obtained both for salinity and redox environment identification.•A ...misleading aquifer salinization reconstruction is given using Integrated Depth Sampling.
Saltwater intrusion in coastal aquifers is an urgent issue for the actual and future groundwater supply and a detailed characterization of groundwater quality with depth is a fundamental prerequisite to correctly distinguish salinization processes. In this study, interpolated Cl− maps of the Po River delta coastal aquifer (Italy), gained with Integrated Depth Sampling (IDS) and Multi-Level Sampling (MLS) techniques, are compared. The data set used to build up the IDS and MLS interpolated Cl− maps come from numerous monitoring campaigns on surface and ground waters, covering the time frame from 2010 to 2014. The IDS interpolated Cl− map recalls the phenomenon of actual seawater intrusion, with Cl− concentration never exceeding that of seawater and the absence of hypersaline groundwater all over the study area. On the contrary, in the MLS interpolated Cl− maps the lower portion of the unconfined aquifer presents hypersaline groundwater making it necessary to consider salinization processes other than actual seawater intrusion, like upward flux from a saline aquitard. Results demonstrate the obligation of using MLS in reconstructing a reliable representation of the distribution of salinity, especially in areas where the density contrast between fresh and saline groundwater is large. Implications of the reported field case are not limited to the local situation but have a wider significance, since the IDS technique is often employed in saltwater intrusion monitoring even in recent works, with detrimental effect on the sustainable water resource management of coastal aquifers.
The recently found association between patent foramen ovale (PFO) and transient global amnesia (TGA) has suggested that paradoxical microembolization in the terminal vertebrobasilar territory might ...underlie at least some TGA cases. Migraine with visual aura is another paroxysmal disturbance in which a sudden dysfunction of cortical areas fed by the terminal branches of the basilar artery is believed to trigger the attack. Therefore we investigated the prevalence of PFO in a consecutive unselected cohort of migraine patients.
To investigate the prevalence of PFO in a consecutive unselected cohort of migraine patients to search for a possible mechanism for the reported association of migraine with stroke.
A total of 113 patients, consecutively referred by the Headache Outpatient Clinic for migraine with aura (MA+, mean age 34+/-12 years) were compared with 53 patients with migraine without aura (MA-, mean age 36+/-13 years) and with 25 age-matched nonmigraine subjects (mean age 31+/-10 years) selected from the hospital staff. PFO was assessed with transcranial Doppler sonography with IV injection of agitated saline, a technique that is 90% sensitive and 100% specific. The prevalence of PFO was 48% (54/113) in MA+ patients, 23% (12/53) in MA- patients, and 20% (5/25) in control subjects. The difference between MA+ and MA- patients was significant (odds ratio OR = 3.13, 95% confidence interval CI = 1.41 to 7.04, chi2 = 9.52,p = 0.002) as was the difference between MA+ patients and controls (OR = 3.66, 95% CI = 1.21 to 13.25, chi2 = 6.46, p = 0.01), whereas MA- patients did not differ from controls (OR = 1.17, 95% CI = 0.32 to 4.45, chi2 = 0.07). MRI was negative in 22 MA+ and 8 MA- patients.
Patency of the foramen ovale is associated with migraine with aura but not with migraine without aura. The increased risk of stroke found in epidemiologic studies in patients with migraine with aura may be explained by an increased propensity to paradoxical cerebral embolism.
A relationship between migraine and patent foramen ovale (PFO) has been observed in relatively small series of patients so far. Furthermore, the exact mechanism underlying such an association remains ...unknown. In the present study we determined the prevalence of PFO by contrast-enhanced transcranial Doppler (TCD) in a group of 260 patients with migraine with aura (MA+), 74 patients with migraine without aura (MA-), and 38 patients with cluster headache (CH). One-hundred-sixty-one MA+subjects (61.9%), 12 MA-subjects (16.2%), and 14 CH-subjects (36.8%) were PFO-carriers. The association was independent on the frequency of migraine attacks and complexity of aura. Finally, among the 15 patients who had a history of at least one migraine attack occurring during a Valsalva maneuver only one subject turned out to be PFO-carrier. Our findings confirm previous observations of a link between MA+, CH, and PFO. They also suggest that such an association is independent on migraine clinical phenotype and is probably unrelated to the pathogenic mechanism of paradoxical embolism.
The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of
136
Xe. Out of its 50 t total natural xenon inventory, ...40 t will be the active target of a time projection chamber which thus contains about 3.6 t of
136
Xe. Here, we show that its projected half-life sensitivity is
2.4
×
10
27
year
, using a fiducial volume of 5 t of natural xenon and 10 year of operation with a background rate of less than 0.2 events/(t
·
year) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in
136
Xe.
The selection of low-radioactive construction materials is of utmost importance for the success of lowenergy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation ...of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222Rn activity concentration of 10 mu Bq/kg in 3.2 t of xenon. The knowledge of the distribution of the 222Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222Rn activity concentration in XENON1T. The final 222Rn activity concentration of (4.5 +/- 0.1) mu Bq/kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.
We correct an overestimation of the production rate of
137
Xe in the DARWIN detector operated at LNGS. This formerly dominant intrinsic background source is now at a level similar to the irreducible ...background from solar
8
B neutrinos, thus unproblematic at the LNGS depth. The projected half-life sensitivity for the neutrinoless double beta decay (
0
ν
β
β
) of
136
Xe improves by
22
%
compared to the previously reported number and is now
T
1
/
2
0
ν
=
3.0
×
10
27
yr
(90% C.L.) after 10 years of DARWIN operation.
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