116 research outputs found
Structural validity and classification performance of the Italian Short Negative Acts Questionnaire: A Structural Equation Modeling approach for building ROC curves
We investigated the structural (internal) validity and classification performance of the Italian Short Negative Acts Questionnaire (SNAQ), a 9-item self-report instrument assessing bullying at work. Consistent with recent attention of researchers to control measurement error in predictive models (Jacobucci & Grimm, Perspectives on Psychological Science, 15(3), 809–816 2020), classification performance was investigated through a proposed novel procedure that uses Structural Equation Modeling for building ROC curves. Participants included 357 workers (females = 50.4%) from various sectors. Our results showed that (a) the Italian SNAQ demonstrates adequate levels of structural validity; (b) its classification performance (in terms of self-labeled bullying) is outstanding; and (c) the ROC curves estimated by means of Structural Equation Modeling outperform those estimated with classical observed-variable approaches. In conclusion, we provided further evidence regarding the good psychometric properties of the Italian SNAQ and we also offered a novel approach for estimating ROC curves that does not neglect the issue of measurement quality
Experimental cannibalization of plagioclase by alkaline basalt magmas
Time-series crystallization/dissolution experiments were conducted on a natural potassic basalt seeded with bytownitic plagioclases (Plg) at atmospheric pressure, in air, at 1180- 1240 °C and isothermal dwell time up to 20 hours. Plg-seed presence promotes the early formation of new-Plg, dampening the clinopyroxene (Cpx) crystallization. New-Plgs grow at a rate from 10-6 up to 10-8 cm·s-1 as the dwell time increases. Seeds overgrow at similar rate. Cpx crystallizes with a delay of at least 3 hours; this has a significant impact on the composition of both residual melt and new-Plgs. For undercooling >35 °C the Cpx delay causes a strong supersaturation of this phase in the melt resulting in a decrease in the new-Plg nucleation rate by 2 orders of magnitude in the 3 h-experiment. In the 15h-run, Cpx coarsening and the decrease of crystallinity suggest the achievement of a near-equilibrium conditions. Cpx growth rate is in the order of 10-7 cm·s-1 showing very limited variation. Finally, for the investigated superheating (5-15 °C) only the long lasting experiments allows an estimation of Plg dissolution rate (10-9 cm·s-1) although changes in the melt composition are already detectable in the 3h-runs.
As a whole our results suggest that in natural systems, the takeover of antecrysts/ xenocrysts by a magma can induce on a short time scales, changes in its initial nucleation behavior with remarkable petrological implications for the solidification paths and eruptive dynamics of potassic magmatic systems
Unravelling work drive: A comparison between workaholism and overcommitment
Workaholism and overcommitment are often used as interchangeable constructs describing an individual’s over-involvement toward their own job. Employees with high levels in both constructs are characterized by an excessive effort and attachment to their job, with the incapability to detach from it and negative consequences in terms of poor health and job burnout. However, few studies have simultaneously measured both constructs, and their relationships are still not clear. In this study, we try to disentangle workaholism and overcommitment by comparing them with theoretically related contextual and personal antecedents, as well as their health consequences. We conducted a nonprobability mixed mode research design on 133 employees from different organizations in Italy using both self-and other-reported measures. To test our hypothesis that workaholism and overcommitment are related yet different constructs, we used partial correlations and regression analyses. The results confirm that these two constructs are related to each other, but also outline that overcommitment (and not workaholism) is uniquely related to job burnout, so that overcommitment rather than workaholism could represent the true negative aspect of work drive. Additionally, workaholism is more related to conscientiousness than overcommitment, while overcommitment shows a stronger relationship with neuroticism than workaholism. The theoretical implications are discussed
Base cation mobility in vineyard soils of the Colli Albani volcanic district (Central Italy)
The quality of the Colli Albani volcanic soils has certainly contributed to the vine cultivars hence the name of one of the oldest wines (i.e., Alban wine). The alkali up to 15 wt%, SiO2 ≤ 52 wt% and the emplacement at high temperature (≤ 600 °C) are the bedrock features that have deeply influenced the soil-forming processes in the vineyards. However, the peculiar features of the Colli Albani soils are not well known. Field survey and textural, mineralogical, and chemical data obtained with SEM, EMP, XRD, and ICP-OES were used to characterize the vineyard soils of the Colli Albani. Leucite (Lct)-bearing soils and quartz (Qz)-bearing soils occur in the studied vineyard. The Qz-bearing soils represent more weathered volcanic material, depleted in primary minerals and enriched in clays, which show a lower cation exchange capacity (CEC) than the Lct-bearing soils. CEC is a misleading definition for the Colli Albani soils because the base cation mobility in the vineyard is independent from clay mineral enrichment in the soil. Actually, the release of K, Na, Ca, and Mg depends by (i) the complete dissolution of leucite and analcime, (ii) the oxy-reaction affecting the phlogopite, which releases K + Mg, and (iii) the incongruent dissolution of clinopyroxene characterized by the “gothic texture.” This texture highlights the capacity of clinopyroxene to release Ca and Mg in volcanic soils. Quantification of the texture and abundance of the primary minerals are mandatory for the management of the vineyard soils in the Colli Albani and, in general, it is significative for the vineyards in volcanic areas
Metasomatism induced by alkaline magma in the upper mantle of northern Victoria Land (Antarctica): an experimental approach
Magma generation in the Ross Sea system is related to partial melting of strongly
metasomatised mantle sources where amphibole most probably plays a crucial role. In this
context, metasomatism induced by a mela-nephelinite melt in lithospheric mantle of the Mt.
Melbourne Volcanic Province (northern Victoria Land – NVL, Antarctica) was investigated
experimentally studying the effects of melt interaction with lherzolite at 1.5-2.0 GPa and
T=975-1300°C, and wehrlite at 1.0 GPa and T=1050-1250°C. The experiments were
designed to induce melt infiltration into the ultramafic rocks. The observed modifications in
minerals are compared with those found in mantle xenoliths from NVL. The effects of
metasomatic modifications are evaluated on the basis of run temperature, distance from the
infiltrating melt and on the diffusion rates of chemical components. Both in lherzolite and
wehrlite, clinopyroxene exhibits large compositional variations ranging from primary
diopside to high Mg-Cr-(Na) augitic and omphacitic clinopyroxenes in lherzolite, and to
low Mg and high Ti-Al-Fe-Na augites in wehrlite. Olivine (in wehrlite) and spinel (in
lherzolite) also result compositionally modified, the former shows enrichments in Fe, the
latter displays a higher Cr/(Cr+Al) ratio. The systematic variations in mineral compositions
imply modifications of the chemistry of the infiltrating melt as recorded by the glass
veinlets and patches observed in some charges. In experiments involving wehrlite
paragenesis, the glass composition approaches that of melt patches associated to both
amphibole-free and amphibole-bearing natural samples, and is related to
olivine+clinopyroxene crystallisation coupled with primary clinopyroxene dissolution at the
contact between the metasomatising melt and the solid matrix. Even if amphibole
crystallisation was not attained in the experiments, we were able to explain the occurrence
of amphibole in the natural system considering that in this case a hot metasomatising melt
infiltrates a cooler matrix
Synthesis and Properties of Sucrose- and Lactose-Based Aromatic Ester Surfactants as Potential Drugs Permeability Enhancers
The delivery of therapeutics across biological membranes (e.g., mucosal barriers) by avoiding invasive routes (e.g., injection) remains a challenge in the pharmaceutical field. As such, there is the need to discover new compounds that act as drug permeability enhancers with a favorable toxicological profile. A valid alternative is represented by the class of sugar-based ester surfactants. In this study, sucrose and lactose alkyl aromatic and aromatic ester derivatives have been synthesized with the aim to characterize them in terms of their physicochemical properties, structure–property relationship, and cytotoxicity, and to test their ability as permeability enhancer agents across Calu-3 cells. All of the tested surfactants showed no remarkable cytotoxic effect on Calu-3 cells when applied both below and above their critical micelle concentration. Among the explored molecules, lactose p-biphenyl benzoate (URB1420) and sucrose p-phenyl benzoate (URB1481) cause a reversible ~30% decrease in transepithelial electrical resistance (TEER) with the respect to the basal value. The obtained result matches with the increased in vitro permeability coefficients (Papp) calculated for FTIC-dextran across Calu-3 cells in the presence of 4 mM solutions of these surfactants. Overall, this study proposes sucrose- and lactose-based alkyl aromatic and aromatic ester surfactants as novel potential and safe permeation enhancers for pharmaceutical applications
THE ITALIAN QUATERNARY VOLCANISM
The peninsular and insular Italy are punctuated by Quaternary volcanoes and their rocks constitute an important aliquot of the Italian Quaternary sedimentary successions. Also away from volcanoes themselves, volcanic ash layers are a common and frequent feature of the Quaternary records, which provide us with potential relevant stratigraphic and chronological markers at service of a wide array of the Quaternary science issues. In this paper, a broad representation of the Italian volcano-logical community has joined to provide an updated comprehensive state of art of the Italian Quaternary volcanism. The eruptive history, style and dynamics and, in some cases, the hazard assessment of about thirty Quaternary volcanoes, from the north-ernmost Mt. Amiata, in Tuscany, to the southernmost Pantelleria and Linosa, in Sicily Channel, are here reviewed in the light of the substantial improving of the methodological approaches and the overall knowledge achieved in the last decades in the vol-canological field study. We hope that the present review can represent a useful and agile document summarising the knowledege on the Italian volcanism at the service of the Quaternary community operating in central Mediterranean area
Diamondites: evidence for a distinct tectono-thermal diamond-forming event beneath the Kaapvaal craton
The petrogenesis and relationship of diamondite to well-studied monocrystalline and fibrous diamonds are poorly understood yet would potentially reveal new aspects of how diamond-forming fluids are transported through the lithosphere and equilibrate with surrounding silicates. Of 22 silicate- and oxide-bearing diamondites investigated, most yielded garnet intergrowths (n = 15) with major element geochemistry (i.e. Ca–Cr) classifying these samples as low-Ca websteritic or eclogitic. The garnet REE patterns fit an equilibrium model suggesting the diamond-forming fluid shares an affinity with high-density fluids (HDF) observed in fibrous diamonds, specifically on the join between the saline–carbonate end-members. The δ13C values for the diamonds range from − 5.27 to − 22.48‰ (V-PDB) with δ18O values for websteritic garnets ranging from + 7.6 to + 5.9‰ (V-SMOW). The combined C–O stable isotope data support a model for a hydrothermally altered and organic carbon-bearing subducted crustal source(s) for the diamond- and garnet-forming media. The nitrogen aggregation states of the diamonds require that diamondite-formation event(s) pre-dates fibrous diamond-formation and post-dates most of the gem monocrystalline diamond-formation events at Orapa. The modelled fluid compositions responsible for the precipitation of diamondites match the fluid-poor and fluid-rich (fibrous) monocrystalline diamonds, where all grow from HDFs within the saline-silicic-carbonatitic ternary system. However, while the nature of the parental fluid(s) share a common lithophile element geochemical affinity, the origin(s) of the saline, silicic, and/or carbonatitic components of these HDFs do not always share a common origin. Therefore, it is wholly conceivable that the diamondites are evidence of a distinct and temporally unconstrained tectono-thermal diamond-forming event beneath the Kaapvaal craton
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