1,721,061 research outputs found
Chemical zoning and colour changes in the phases of the sodalite group from the Mt. Vulture haüynophyre lava (Potenza-Italy)
No full textConfini tra disturbo ossessivo-compulsivo e depressione: Considerazioni psicopatologiche
No full textAt first sight, obsessivity and depression seem to be two different phenomena, even opposite in some aspects. However, it is clinically common to find obsessive-compulsive features together with depressive symptoms: Whereas the discriminant power of self-report questionnaires for obsessions and compulsions is not very high when Obsessive-Compulsive Disorders and Major Depression are compared. However, clinical and biological studies suggest a clear discrimination between this two disorders. The psycopathological analisys allows both to understand the apparent analogies and to show the essential structural differences between obsessive-compulsive and depressive phenomena
Shallow magmatic and hydrothermal crystallization processes at Piton de la Fournaise (Réunion Island, Indian Ocean) inferred from subvolcanic cognate clasts, xenoliths and xenocrysts
No full textInfluence of composition and thermal history of volcanic glasses on water content determination by microRaman spectrometry
No full textDevelopment of Raman spectrometry for quantification of water content in natural glasses requires the assessment of
the dependence of the technique on glass composition and thermal history. In the low frequency domain, Raman spectra
topology varies due to glass depolymerization and substitution in the framework of (Si4+)IV by alkali-balanced (Al3+)IV
and (Fe3+)IV in calcalkaline (rhyolite to basaltic andesite) and alkaline (trachyte, phonolite to alkali basalt) glasses. These
processes result in strong dependence of previous analytical procedure (internal calibration) on glass composition. Here,
we show that an analytical procedure based on calibration to an external standard is only faintly composition-dependent
for Si-rich alkaline glasses (trachytes–phonolites). For a given glass composition, thermal history also plays a fundamental role in the choice of Raman procedure for water analysis. Repeated cycles of thermal annealing induce microcrystallization
of hydrous trachyte glasses and modify cation distribution in the glass structure. Application of these concepts to analysis
of banded obsidians suggests that small-scale heterogeneities in glasses are not simply related to magma degassing, but
could depend on thermal history and consequent relaxation paths in the melt
An expanded non Arrhenian model for silicate melt viscosity: A treatment for metaluminous, peraluminous and peralkaline liquids
No full textWe present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements,
combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the
viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in
viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the
compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully
controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the
excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative error (e.g., RMSE of 0.45 logunits)
The asthenia issue in obsessive-compulsive disorder [II problema della astenia nel disturbo ossessivo-compulsivo]
No full textOne of Pierre Janet's most important clinical intuition was to correlate the concept of psycho-asthenia to the complexity of obsessive patients and its nuclear role in obsessive-compulsive psychopathology. Clinical experience suggests that patients affected by Obsessive-Compulsive Disorder show a great sensitivity to fatigue or lack of rest: this vulnerability condition seems to have a specific effect, because all weakness states may worsen obsessions and compulsions. Starting from these considerations and from few and aspecific existing instruments, we elaborated a questionnaire to assess obsessive- compulsive characteristics-related asthenia. The questionnaire includes 31 items assessing different aspects of asthenia: fatigue, tiredness, energy, need of sleep, related to an increase of obsessive-compulsive symptoms and was administered to healthy subjects and to patients with different DSM-IV disorders (Obsessive-Compulsive Disorder, Depressive Disorders, Panic Disorder). Statistical and psychopathological analysis show that the instrument discriminates the obsessive patients from healthy individuals and from patients with panic disorder. However, it does not detect differences between Obsessive-Compulsive Disorder and Mood Disorders, suggesting, for the former, a primary weakness of cortical function and for the latter weakness of the subcortical areas
The transition from convective to collapsing eruptive regime during the 800 yars BP explosive activity of the Quilotoa volcano
No full textLife Cycle Assessment for the ISWEC Wave Energy Device
No full textIn recent years, wave renewable energy is becoming established as one of the crucial components of a diversified and successful energy mix. The Inertial Sea Wave Energy Converter (ISWEC) is a mature technology, especially designed for closed seas, as the Mediterranean Sea, which has already been deployed in full-scale. At this stage of development, since the technology has been proven successful, it is crucial to assess its environmental impact. A life cycle assessment has been performed on the ISWEC including all relevant phases, from raw material extraction, to construction, assembly, transportation, use and final dismantling. As an outcome, the LCA study allowed the calculation of a set of impacts on the environment, resources depletion and human health that allows the innovative renewable energy-based technology to be consistently compared with other solutions. One of the most popular impacts, such as climate change, has been estimated at 31.5 gCO2eq/kWh which is in line e.g. with the performance of photovoltaics
First measurements of magmatic gas composition and fluxes during an eruption (October 2010) of Piton de la Fournaise hot spot volcano, La reunion island
No full textPiton de la Fournaise (PdF), in the western Indian Ocean, is a very active hot spot basaltic volcano, with 1-2 fissure eruptions per year on average. Its magmas have been widely studied and its eruptions are well anticipated by the local seismic-geodetic monitoring network. However, no datum was yet available for its magmatic gas emissions (restricted to only eruptive phases and hardly accessible). Here we report on the first measurements of the chemical composition and mass flux of magmatic gases emitted during a PdF eruption in October 2010. Hot gases arising from different eruptive vents were remotely measured with OP-FTIR spectroscopy, using molten lava fragments as IR radiation source, which allowed simultaneous detection of H2O, CO2, SO2, HCl, HF and CO. In situ MultiGas direct analysis of H2O, CO2 and SO2 was also performed in volcanic plumes downwind of the vents. The results reveal a surprisingly H2O-rich (98-97 mol %) and CO2-poor (1.0-1.8%) magmatic gas, whose H2O/CO2 ratio however decreased while C/S (1.2-1.9), S/Cl (13-35) and Cl/F (9.7-12) ratios increased during the course of the eruption. In the same time, SO2 fluxes, measured during walking and helicopter-borne DOAS traverses under the volcanic plume, rapidly dropped from 5 to 1.8 ktons per day as the eruption intensity and lava effusion rate were lowering. From DOAS and OP-FTIR data we derive the emission rate of each gas species and the evolution of total gas flux during that event. Combining these results with available literature data for dissolved volatiles in PdF magmas allows us to draw some preliminary conclusions: (i) Contemporaneous SO2, HCl and HF fluxes and lava effusion rates are compatible with a pure syn-eruptive magma degassing process for S, Cl and F; (b) In contrast, the inferred emission rates for H2O and CO2 suggest some separate CO2 bubble transfer and a water contribution from the hydrothermal system to H2O degassing (steam entrainment during dyke propagation; (c) The changes in gas composition over time is consistent with lower external fluid addition and increasing proportion of truly magmatic volatiles in gas emissions, even though the eruption was decreasing in intensity; and (d) It remains that PdF hot spot mantle source is confirmed to be water-dominated, instead of CO2-rich. Further gas measurements during future PdF eruptions and their cross-correlation with geophysical signals should provide us with increased insight into the conditions of magma ascent and degassing during dyke propagation through the volcanic edifice
Possible involvement of opioid systems in obsessive-compulsive disorder: Psychopathological considerations [Possibile coinvolgimento del sistema oppioide nel disturbo ossessivo-compulsivo e relative considerazioni psicopatologiche]
No full textThe effects of exogenous opioids are completely opposite to anxiety symptomatology and suggest the existence of a relationship between opioid systems and Anxiety Disorders. The involvement of opioid systems in Obsessive-Compulsive Disorder (OCD) is suggested by its analogy with other Anxiety Disorders and by the role of such system in disorders of the obsessive-compulsive spectrum (Tourette's Disorder, Substance-Related Disorders, Eating Disorders, Impulse-Control Disorders); some experimental evidence in patients affected by OCD and the effect of therapy with opioid agonists and antagonists further support this hypothesis. The involvement of endogenous opioids in Posttraumatic Stress Disorder is widely supported. Opioid involvement in Panic Disorder is suggested by pharmacological evidence, such as naltrexone-induced Panic Attacks; moreover, the opioid system may decrease activity of the locus coeruleus. Finally, patients affected by Generalized Anxiety Disorder have higher beta-endorphin plasma levels than controls, before facing stressful situations. Therefore, these data suggest a possible opioid involvement in core psychopathological aspects of OCD, related to pleasure and reward systems
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