112,255 research outputs found
Weathering of evaporites: natural versus anthropogenic signature on the composition of river waters
No full textWeathering of evaporites strongly influences the chemistry of continental runoff, making surface waters poorly exploitable for civil uses. In south-central Sicily, this phenomenon is worsened by the occurrence of abandoned landfills of old sulphur and salt mines. The industrial evolution of the Bosco-S. Cataldo mining site leaved two landfills from the early exploitation of a sulphur mine followed by that of a kainite deposit. In particular, the weathering of these landfills leads the dissolved salt (TDS) values up to about 200 g l−1 in the Stincone–Salito Stream waters. This process induces the V, Cr and Fe desorption from sediments and particulates in the aqueous phase under reducing conditions. At the same time, the weathering of salt minerals releases Rb and Cs, originally contained in halite. The overall processes lead to the V, Cr, Fe, Rb and Cs enrichment of waters from the Stincone–Salito Stream system accompanied by a sharp growth of As content, up to about 13 μg l−1, caused by As release from Fe-bearing solids due to the high salinity. Therefore, the scenario of the weathering of Bosco-S. Cataldo mine landfills depicts an environment strongly influenced by effects of the growing salinity and euxinic water conditions where the attained TDS, Eh and pH conditions reduce the natural scavenging capability of the interested river system, favouring a growth of residence time of toxic elements in river waters
Can we draw an identikit of cannabis smokers who may be at higher risk of developing a psychosis?
No full textThe purpose of this review is to identify somatic and environmental factors, which make some people more at risk of developing psychosis in connection with the use of cannabis.Were selected in PubMed studies of the last 20 years that have assessed the main factors of vulnerability to psychosis (premorbid personality, family history of psychosis, gender, genetic predisposition, adolescence, childhood trauma, use of other substances, social context, use of internet) and the additive effect of cannabis use.From the literature the existence of a subgroup of subjects prone to the development of psychotic disorders emerges with good evidence, which is characterized by features such as: male gender, premorbid schizotypal personality traits, early use of cannabis in adolescence, family history of psychiatric illness, personal history of abuse and childhood trauma, tendency to social anxiety. The evidences about a genetic predisposition are scarce, and there are few studies in this regard; there is a growing interest in internet addiction and its relationship with drug addiction.Despite the paucity of studies on the vulnerability to psychosis and the additive effect of cannabis use, the topic is of considerable interest, especially for the purpose of sound clinical practice aimed at preventon of psychiatric disorders, and for the correct address of social policies on the use of substances
Chlorite/smectite - alkali feldspar metasomatic xenoliths from hyblean miocenic diatremes (Sicily, Italy): evidence for early interaction between hydrothermal brines and ultramafic/mafic rocks at crustal levels.
No full textUpper-Miocene tuff-breccia pipes from the Hyblean area (south-eastern Sicily) bear a number of ultramafic and mafic xenoliths (spinel-peridotites, pyroxenites, gabbroic rocks) whose study has led to conclude that the Meso-Caenozoic carbonatic and volcanic succession stands upon a fossil oceanic core-complex, probably connected with the adjacent Ionian crust.
Evidence for hydrothermal metasomatism is common in the Hyblean ultramafic and mafic xenoliths. In some cases, extreme metasomatic transformation and shearing have deleted original mineralogy and textures yielding unusual rocks, hereafter called “metasomatites”. These rocks generally exhibit cataclastic texture, their hydrothermal mineral assemblage consisting of Na-rich alkali feldspar, chlorite/smectite (C/S) and/or smectite/illite (S/I) mixed layers, Fe-Ti oxide/ hydroxide ± sieve-textured aegirine-augite ± titanite ± zircon. In addition, relics of Fo91 olivine, probably related to peridotite protoliths, rarely occur in these rocks. Comparing metasomatite whole chemistry to typical Hyblean oxide-gabbro, overall gain in H2O, alkalis, HFSE, U, Th, HREE and significant loss in Ca and Mg are remarkable. The studied xenoliths probably represent fragments of deep-seated, mafic/ultramafic fault-breccia, recording the effects of longlasting hypersaline hydrous fluids circulation in the Hyblean crustal basement
The behaviour of zirconium, hafnium and rare earth elements during the crystallisation of halite and other salt minerals
No full textHalite crystals from Messinian and Tortonian evaporites from Sicily and Spain and current precipitated halite crystals and the relative parent brines (active evaporation systems) were investigated in order to evaluate the Zr, Hf and Rare Earth Element (REE) behaviour. Halite crystallisation from evaporating brines fractionates Zr, Hf and REE through a two-step process. During the first step, dissolved complexes of studied elements are scavenged onto the surfaces of crystallising halite. During the second step, elements are co-precipitated into the crystal lattice as it grows. The first step mechanism is determined by the dissolved REE speciation. In saltworks where carbonate-REE complexes occur, surface complexation of REE onto halite crystals does not occur. On the contrary, surface REE-complexes onto halite crystals are forming in the Dead Sea water where aqueous REE speciation is dominated by chloride-complexes. Under the latter conditions, halite crystallises with cubic and cubic-octahedral composite habitus. Octahedral planes involve the formation of strong coulombic interactions, mainly with [Hf(H2O)3(OH)5]− rather than with [Zr(H2O)4(OH)4]0 complexes. As a consequence, newly formed halite in the Dead Sea shows strong subchondritic Zr/Hf ratios. Based on these indications, analyses carried out on salt minerals from Messinian and Tortonian evaporites in Sicily and Spain show that their overall REE content can be considered a discriminating parameter between authigenic minerals and diagenetic modified materials. However, features of shale-normalised REE patterns are driven by the mineralogical composition of evaporites rather than their authigenic or secondary nature. On the contrary, the Zr/Hf signature of salt minerals is influenced by their origin. Indeed, subchondritic Zr/Hf values are found in primary salt minerals, whereas larger Zr/Hf values are recognised in those diagenetically modified. Calculated distribution coefficients of Zr, Hf and REE are employed for modelling the REE distribution in halite equilibrated with the deep-sea brines from Typo, Medee and Thetis basins (Eastern Mediterranean). The obtained indications allow us to discriminate brines formed by dissolution of evaporites relative to those representing relics of fossil evaporated seawater
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Rare earths, zirconium and hafnium distribution in coastal areas: The example of Sabella spallanzanii (Gmelin, 1791)
No full textThe Zr, Hf, Y and lanthanide (REE) distribution in biological tissues of Sabella spallanzanii and Styela plicata species collected from two harbours from the northern Sicily is studied for providing information regarding the Zr, Hf and REE uptake from the environment. Previous studies determined the fractionation of dissolved REE scavenged on binding sites onto biological surfaces. By comparing the recognised shale-normalised REE patterns of studied samples with evidence from reference data, the observed behaviour of these elements in biological tissues of Sabella spallanzanii and Styela plicata is interpreted to result from the preferential uptake of intermediate REE onto carboxylic sites. Moreover, the relationship observed between the Fe content and Zr/Hf ratio suggests that preferential Hf accumulation occurs via siderophore-like binding sites. Features of the REE bioaccumulation factors (BAF), in addition to the absolute La, Ce and Sm contents and Zr-Hf fractionation, allow definition of the different origins of studied elements in the investigated localities. Higher BAF values for La and Ce associated with larger REE contents and lower Zr/Hf values strongly suggest that the environmental REE distribution in the Termini Imerese harbour is influenced by the delivery of particles from industrial sources and power plants. On the contrary, the REE contents of biological tissues collected in the Cala tourist harbour are affected by the dust dissolution from automotive traffic. These results suggest that the geochemical behaviour of REE and Zr/Hf signature can be used in environmental studies of biological tissues for reconstructing the nature of anthropogenic contaminations
Nonlinear coupling among heart rate, blood pressure, and respiration in patients susceptible to neuromediated syncope
No full textThe aim of this study is to evaluate the degree of coupling between the cardiovascular variability series and the respiration in subjects susceptible to neurally mediated syncope. Twenty-one informed patients susceptible to syncope and ten sex- and a.-e-matched control subjects were enrolled in the study. ECG, respiration activity, and arterial blood pressure were simultaneously recorded at rest (controlled and free breathing) and during the 70degrees head-up TILT test (free breathing). The degree of nonlinear coupling among heart rate variability (HRV), blood pressure variability (BPV), and respiration wits quantified by means of two indices according to a multivariate embedding-based approach. Eleven patients developed syncope during the TILT test. We found that during the late TILT phase, the TILT-positive group experienced a significant increase in nonlinear coupling respect to the mid TILT phase (p<0.01. Wilcoxon nonparametric test for pair data) while the TILT-negative group did not (p<0.01, Mann-Whitney U-test). If the proposed nonlinear coupling indexes can be considered expression of the coupling mechanisms involved in the vagal regulation of the cardiovascular system, an increase in vagal tone accompanied by a decrease in sympathetic activity seem to occur before a vasovagal event. (C) 2003 Biomedical Engineering Society
ECG P-Wave Smoothing and Denoising by Quadratic Variation Reduction
No full textAtrial fibrillation is the most common persistent cardiac arrhythmia and it is characterized by a disorganized atrial electrical activity. Its occurrence can be detected, and even predicted, through P-waves time-domain and morphological analysis in ECG tracings. Given the low signal-to-noise ratio associated to P-waves, such anal- ysis are possible if noise and artifacts are effectively filtered out from P-waves. In this paper a novel smoothing and denoising algorithm for P-waves is proposed. The algorithm is solution to a convex optimization problem. Smoothing and denoising are achieved reducing the quadratic variation of the measured P-waves. Simulation results confirm the effectiveness of the approach and show that the proposed algorithm is remarkably good at smoothing and denoising P-waves. The achieved SNR gain exceeds 15 dB for input SNR below 6 dB. Moreover the proposed algorithm has a computational complexity that is linear in the size of the vector to be processed. This property makes it suitable also for real-time applications
Guillain–Barré syndrome and COVID-19 vaccination: a systematic review and meta-analysis
No full textBackground: Case-reports/series and cohorts of Guillain–Barré syndrome (GBS) associated with COVID-19 vaccination have been reported. Methods: A systematic review and meta-analysis of cohort studies of GBS after COVID-19 vaccination was carried out. Incidence and incidence rate ratio for a number of vaccine doses and risk of GBS, also considering the specific vaccine technology, were calculated in a random-effects model. Results: Of 554 citations retrieved, 518 were discarded as irrelevant. We finally included 15 studies. The random effect model yielded, regardless of the vaccine technology, 1.25 (95%CI 0.21; 2.83) GBS cases per million of COVID-19 vaccine doses, 3.93 (2.54; 5.54) cases per million doses for adenovirus-vectored vaccines and 0.69 (0.38; 1.06) cases per million doses for mRNA vaccines. The GBS risk was 2.6 times increased with the first dose. Regardless of the vaccine technology, the GBS risk was not increased but disaggregating the data it was 2.37 (1.67; 3.36) times increased for adenovirus-vectored vaccines and 0.32 (0.23; 0.47) for mRNA vaccines. Mortality for GBS after vaccination was 0.10 per million doses and 4.6 per GBS cases. Conclusions: Adenovirus-vectored vaccines showed a 2.4 times increased risk of GBS that was about seven times higher compared with mRNA-based vaccines. The decreased GBS risk associated with mRNA vaccines was possibly due to an elicited reduction of infections, including SARS-CoV-2, associated with GBS during the vaccination period. How adenovirus-vectored COVID-19 vaccines may trigger GBS is unclear and further studies should investigate the relationship between vaccine technologies and GBS risk
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