Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai'i

© 2020 Elsevier Ltd Chalcophile element concentrations in melt inclusions and matrix glasses may be used to investigate low pressure degassing processes, as well as sulfide saturation during crustal fractionation, and mantle melting. Erupted products from Kīlauea Volcano, Hawaiʻi, record three stages of sulfide saturation (in the mantle, crust, and within lava lakes), separated by episodes of sulfide resorption (i.e., sulfide undersaturation) during ascent through the thick Hawaiian lithosphere, and during syn-eruptive degassing. The presence of residual sulfides in the mantle source throughout the melting interval accounts for the high S concentrations of Kīlauean primary melts (1387–1600 ppm). Residual sulfides retain chalcophile elements during melting, decoupling the variability of these elements in high MgO melts from that of lithophile elements. Decompression associated with magma ascent through the thick Hawaiian lithosphere drives an increase in the sulfide concentration at sulfide saturation (SCSS2−), resulting in shallow storage reservoirs (∼1–5 km depth) being supplied with sulfide-undersaturated melts. A drop in temperature, coupled with major element changes during the fractionation of olivine, causes the SCSS2− to decrease. Combined with an increase in melt S contents during fractionation, this initiates a second stage of sulfide saturation at relatively high MgO contents (∼12 wt%). Syn-eruptive degassing of S drives the resorption of sulfides in contact with the carrier liquid. The covariance structure of Cu, MgO and Ni contents in melt inclusions and matrix glasses indicates that the dissolution of sulfides effectively liberates sulfide-hosted Cu and Ni back into the melt, rather than the vapour phase. The contrasting behaviour of Cu, Ni, Se and S during sulfide resorption indicates that the chalcophile element signature of the Kīlauean plume is largely controlled by silicate melt-vapour partitioning, rather than sulfide-vapour partitioning. The participation of dense sulfide liquids in shallow degassing processes may result from their direct attachment to buoyant vapour bubbles, or olivine crystals which were remobilized prior to eruption. Sulfide resorption obscures the textural and chemical record of sulfide saturation in matrix glasses, but not in melt inclusions, which are isolated from this late-stage release of chalcophile elements. The partitioning of S between the dissolving sulfide, melt and the vapour phase accounts for approximately 20% of the total S release into the atmosphere

Petrologic monitoring at Volcán de Fuego, Guatemala

Paroxysmal activity represents an end-member in the common range of activity at mafic arc volcanoes, characterised by rapid transitions across the effusive-explosive interface and thus posing significant challenges to hazard assessment. Conceptual models to explain changes in the frequency and magnitude of these paroxysmal events are based either on magma recharge or an increase in gas flux, largely framed in the context of two-phase flow. Gas- and magma-driven models are both viable mechanisms to explain the varying styles of paroxysmal behaviour observed in mafic systems; however, each has different implications for future activity. We present time series petrologic data for ash and lava samples collected at Volcán de Fuego, Guatemala, during paroxysmal eruptions between 2011 and 2018. We show that a step-change in glass composition occurred between 2015 and 2016, reflecting an increase in magma temperature and a reduction in pre-eruptive crystallisation, concurrent with an escalation in the frequency of paroxysmal activity. There was no change in the bulk or phase compositions during this period. To explain these observations, we propose that the increase in frequency of paroxysmal eruptions is modulated by the supply of exsolved volatiles from lower crustal degassing magmas, without invoking repeated transfer of new, primitive magma to a shallow reservoir. Protracted lava effusion, accompanied by more vigorous and more frequent Strombolian explosions and gas ‘chugging’, prior to the transition to sustained fountaining suggests that gas retention in crystal-rich magma may modulate the height of the magma column as gas supply increases. Slow decompression associated with effusion may determine the timing of effusive to explosive transitions in mafic arc systems more generally. A large paroxysmal eruption of Fuego on 3 June 2018, notable for the rapid escalation in eruptive intensity several hours into the eruption, produced ash with a range of textures and glass compositions consistent with magma evacuation over a range of depths and decompression rates. Given the protracted repose time between paroxysms before this event, we suggest that a shallow crystallised plug degraded, and ultimately failed, several hours into the eruption of 3 June 2018, triggering top-down decompression of magma in the conduit synchronous with the observed rapid acceleration in eruption rate. Ultimately, we propose that the frequency of paroxysms at Fuego is broadly proportional to the gas supply rate, while the range in glass compositions is related to the repose time prior to eruptive activity. Our data illustrate the potential of petrologic monitoring to distinguish between gas- and magma-driven paroxysm triggers and to anticipate future events, especially when interpreted in the context of geophysical observations and implemented within community-based ash collection initiatives

Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

Granulite facies rocks frequently show a large spread in their zircon ages, the interpretation of which raises questions: Has the isotopic system been disturbed? By what process(es) and conditions did the alteration occur? Can the dates be regarded as real ages, reflecting several growth episodes? Furthermore, under some circumstances of (ultra-)high-temperature metamorphism, decoupling of zircon U–Pb dates from their trace element geochemistry has been reported. Understanding these processes is crucial to help interpret such dates in the context of the P–T history. Our study presents evidence for decoupling in zircon from the highest grade metapelites (> 850 °C) taken along a continuous high-temperature metamorphic field gradient in the Ivrea Zone (NW Italy). These rocks represent a well-characterised segment of Permian lower continental crust with a protracted high-temperature history. Cathodoluminescence images reveal that zircons in the mid-amphibolite facies preserve mainly detrital cores with narrow overgrowths. In the upper amphibolite and granulite facies, preserved detrital cores decrease and metamorphic zircon increases in quantity. Across all samples we document a sequence of four rim generations based on textures. U–Pb dates, Th/U ratios and Ti-in-zircon concentrations show an essentially continuous evolution with increasing metamorphic grade, except in the samples from the granulite facies, which display significant scatter in age and chemistry. We associate the observed decoupling of zircon systematics in high-grade non-metamict zircon with disturbance processes related to differences in behaviour of non-formula elements (i.e. Pb, Th, U, Ti) at high-temperature conditions, notably differences in compatibility within the crystal structure

Requirement for Abasic Endonuclease Gene Homologues in Arabidopsis Seed Development

Arabidopsis thaliana has three genes, Ape1L, Ape2, and Arp, that show homology to abasic (apurinic/apyrimidinic) endonuclease genes of bacterial, yeast, or animal cells. In bacteria, yeast, and animals, abasic endonucleases function in base excision repair of oxidized and other modified DNA bases. Here we report that plants with knock-out mutations in any one of Ape1L, Ape2, or Arp show no apparent differences from wild type in growth rate, growth habit, and fertility. However, coincident knock-out mutations in Ape1L and Ape2 are lethal and lead to abortion of developing embryos. Mutations of Arp are not deleterious, even in combination with one of the other two mutations. The results are consistent with the interpretation that the process of base excision repair, involving at least one intact copy of Ape1L or Ape2, is required in the process of embryogenesis

Azimuthal anisotropy and correlations at large transverse momenta in p+pp+p and Au+Au collisions at sNN\sqrt{s_{_{NN}}}= 200 GeV

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au+Au collisions to those in $p+p$ at the same energy. Elliptic anisotropy, $v_2$, is found to reach its maximum at $p_t \sim 3$ GeV/c, then decrease slowly and remain significant up to $p_t\approx 7$ -- 10 GeV/c. Stronger suppression is found in the back-to-back high-$p_t$ particle correlations for particles emitted out-of-plane compared to those emitted in-plane. The centrality dependence of $v_2$ at intermediate $p_t$ is compared to simple models based on jet quenching.Comment: 4 figures. Published version as PRL 93, 252301 (2004

Rapidity and Centrality Dependence of Proton and Anti-proton Production from Au+Au Collisions at sqrt(sNN) = 130GeV

We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from Au+Au collisions at sqrt(sNN) = 130GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y|<0.5 and 0.35 <p_t<1.00GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y|<0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.Comment: 4 pages, 3 figures, 1 table, submitted to PR

Значение мотивации персонала на предприятии

Основная цель – систематизировать сведения о мотивации персонала и его значении на предприятии

Filaggrin Genotype Determines Functional and Molecular Alterations in Skin of Patients with Atopic Dermatitis and Ichthyosis Vulgaris

BACKGROUND: Several common genetic and environmental disease mechanisms are important for the pathophysiology behind atopic dermatitis (AD). Filaggrin (FLG) loss-of-function is of great significance for barrier impairment in AD and ichthyosis vulgaris (IV), which is commonly associated with AD. The molecular background is, however, complex and various clusters of genes are altered, including inflammatory and epidermal-differentiation genes. OBJECTIVE: The objective was to study whether the functional and molecular alterations in AD and IV skin depend directly on FLG loss-of-function, and whether FLG genotype determines the type of downstream molecular pathway affected. METHODS AND FINDINGS: Patients with AD/IV (n = 43) and controls (n = 15) were recruited from two Swedish outpatient clinics and a Swedish AD family material with known FLG genotype. They were clinically examined and their medical history recorded using a standardized questionnaire. Blood samples and punch biopsies were taken and trans-epidermal water loss (TEWL) and skin pH was assessed with standard techniques. In addition to FLG genotyping, the STS gene was analyzed to exclude X-linked recessive ichthyosis (XLI). Microarrays and quantitative real-time PCR were used to compare differences in gene expression depending on FLG genotype. Several different signalling pathways were altered depending on FLG genotype in patients suffering from AD or AD/IV. Disease severity, TEWL and pH follow FLG deficiency in the skin; and the number of altered genes and pathways are correlated to FLG mRNA expression. CONCLUSIONS: We emphasize further the role of FLG in skin-barrier integrity and the complex compensatory activation of signalling pathways. This involves inflammation, epidermal differentiation, lipid metabolism, cell signalling and adhesion in response to FLG-dependent skin-barrier dysfunction

The implementation of the serial trial intervention for pain and challenging behaviour in advanced dementia patients (STA OP!): a clustered randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Pain (physical discomfort) and challenging behaviour are highly prevalent in nursing home residents with dementia: at any given time 45-80% of nursing home residents are in pain and up to 80% have challenging behaviour. In the USA Christine Kovach developed the serial trial intervention (STI) and established that this protocol leads to less discomfort and fewer behavioural symptoms in moderate to severe dementia patients. The present study will provide insight into the effects of implementation of the Dutch version of the STI-protocol (STA OP!) in comparison with a control intervention, not only on behavioural symptoms, but also on pain, depression, and quality of life. This article outlines the study protocol.</p> <p>Methods/Design</p> <p>The study is a cluster randomized controlled trial in 168 older people (aged >65 years) with mild or moderate dementia living in nursing homes. The clusters, Dutch nursing homes, are randomly assigned to either the intervention condition (training and implementation of the STA OP!-protocol) or the control condition (general training focusing on challenging behaviour and pain, but without the step-wise approach). Measurements take place at baseline, after 3 months (end of the STA OP! training period) and after 6 months.</p> <p>Primary outcome measures are symptoms of challenging behaviour (measured with the Cohen-Mansfield Agitation Inventory (CMAI) and the Neuropsychiatric Inventory-Nursing Home version (NPI-NH)), and pain (measure with the Dutch version of the Pain Assessment Checklist for Seniors (PACSLAC-D) and the Minimum Data Set of the Resident Assessment Instrument (MDS-RAI) pain scale). Secondary outcome measures include symptoms of depression (Cornell and MDS-RAI depression scale), Quality of Live (Qualidem), changes in prescriptions of analgesics and psychotropic drugs, and the use of non-pharmacological comfort interventions (e.g. snoezelen, reminiscence therapy).</p> <p>Discussion</p> <p>The transfer from the American design to the Dutch design involved several changes due to the different organisation of healthcare systems. Specific strengths and limitations of the study are discussed.</p> <p>Trial registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1967">NTR1967</a></p