127 research outputs found
Magma recharge patterns control eruption styles and magnitudes at Popocatépetl volcano (Mexico)
This work was funded by UK Natural Environment Research Council grant NE/M014584/1, Royal Society (London) Newton International Exchanges grant IE140605, and a Natural History Museum (London) Collection Enhancement Fund, all to C.M. Petrone, and a Janet Watson Scholarship (Imperial College London) to M.F. Mangler.Diffusion chronometry has produced petrological evidence that magma recharge in mafic to intermediate systems can trigger volcanic eruptions within weeks to months. However, less is known about longer-term recharge frequencies and durations priming magma reservoirs for eruptions. We use Fe-Mg diffusion modeling in orthopyroxene to show that the duration, frequency, and timing of pre-eruptive recharge at Popocatépetl volcano (Mexico) vary systematically with eruption style and magnitude. Effusive eruptions are preceded by 9–13 yr of increased recharge activity, compared to 15–100 yr for explosive eruptions. Explosive eruptions also record a higher number of individual recharge episodes priming the plumbing system. The largest explosive eruptions are further distinguished by an ∼1 yr recharge hiatus directly prior to eruption. Our results offer valuable context for the interpretation of ongoing activity at Popocatépetl, and seeking similar correlations at other arc volcanoes may advance eruption forecasting by including constraints on potential eruption size and style.Peer reviewe
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Mush remobilisation and mafic recharge: A study of the crystal cargo of the 2013–17 eruption at Volcán de Colima, Mexico
Volcán de Colima is a highly active stratovolcano at the western end of the Trans-Mexican Volcanic Belt. Present-day activity consists of lava dome growth and destruction, lava flows, small explosions, and larger explosive Vulcanian eruptions; and it has been postulated that increased frequency of more mafic eruptions signals the run-up of c. 100-year eruptive ‘cycles’, terminating with a Plinian eruption such as those in 1818 and 1913. It is therefore important to understand the role played by mafic recharge during interplinian activity. We present new petrological and geochemical data for lava and ash from the 2013–17 phase of eruption. The uniform paragenesis and geochemical homogeneity of bulk rocks indicate efficient long-term homogenisation of magmas within the plumbing system, similar to the previous 1998–2005 eruptive products. Mineral chemistry however preserves complex patterns of magma recharge and mixing. Chemical and textural information support the interpretation of two magmatic end-members – an evolved end-member saturated with respect to Fesingle bondTi oxides and apatite and crystallising low-An plagioclase and pyroxenes in the Mg# 69–75 range; and a more primitive, mafic end-member crystallising high-An plagioclase and pyroxenes in the Mg# 77–88 range. Pyroxene textures and zoning patterns suggest mixing of the mafic melts with the evolved magma and remobilisation of the crystal mush. Two-pyroxene geothermometry constrains magmatic temperatures to c. 980–1000 °C for the evolved end-member, and c. 1020–1080 °C for the mafic end-member. Pressure estimates suggest crystallisation at 4–6 kbar, or c. 12–18 km depth. We interpret this to reflect periodic injections of mafic melts and remobilised crystals into evolved reservoirs in a mushy magma storage system in the mid-crust, in agreement with geophysical data suggesting a semi-molten, partially crystallised body at this depth. From 2015, an increase in reverse zoned crystals, indicative of mafic injection, suggests that these melts were injected into the system following the large eruption in July 2015. Our findings suggest that the intense July 2015 eruption may be linked to increased input of mafic magmas into the shallow system, indicating that mafic injections may be a key process governing the timing and style of eruption at Volcán de Colima
Effects of Hst3p inhibition in Candida albicans: a genome-wide H3K56 acetylation analysis
Candida spp. represent the third most frequent worldwide cause of infection in Intensive Care Units with a mortality rate of almost 40%. The classes of antifungals currently available include azoles, polyenes, echinocandins, pyrimidine derivatives, and allylamines. However, the therapeutical options for the treatment of candidiasis are drastically reduced by the increasing antifungal resistance. The growing need for a more targeted antifungal therapy is limited by the concern of finding molecules that specifically recognize the microbial cell without damaging the host. Epigenetic writers and erasers have emerged as promising targets in different contexts, including the treatment of fungal infections. In C. albicans, Hst3p, a sirtuin that deacetylates H3K56ac, represents an attractive antifungal target as it is essential for the fungus viability and virulence. Although the relevance of such epigenetic regulator is documented for the development of new antifungal therapies, the molecular mechanism behind Hst3p-mediated epigenetic regulation remains unrevealed. Here, we provide the first genome-wide profiling of H3K56ac in C. albicans resulting in H3K56ac enriched regions associated with Candida sp. pathogenicity. Upon Hst3p inhibition, 447 regions gain H3K56ac. Importantly, these genomic areas contain genes encoding for adhesin proteins, degradative enzymes, and white-opaque switching. Moreover, our RNA-seq analysis revealed 1330 upregulated and 1081 downregulated transcripts upon Hst3p inhibition, and among them, we identified 87 genes whose transcriptional increase well correlates with the enrichment of H3K56 acetylation on their promoters, including some well-known regulators of phenotypic switching and virulence. Based on our evidence, Hst3p is an appealing target for the development of new potential antifungal drugs
Characteristics of COVID-19 cases in Italy from a sex/gender perspective
Introduction: Coronavirus disease 19 (COVID-19) is an infectious disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To date, few data on clinical features and risk factors for disease severity and death by gender are available. Aim: The current study aims to describe from a sex/gender perspective the characteristics of the SARS-CoV-2 cases occurred in the Italian population from February 2020 until October 2021. Method and results: We used routinely collected data retrieved from the Italian National Surveillance System. The highest number of cases occurred among women between 40 and 59 years, followed by men in the same age groups. The proportion of deaths due to COVID-19 was higher in men (56.46%) compared to women (43.54%). Most of the observed deaths occurred in the elderly. Considering the age groups, the clinical outcomes differed between women and men in particular in cases over 80 years of age; with serious or critical conditions more frequent in men than in women. Conclusions: Our data clearly demonstrate a similar number of cases in women and men, but with more severe disease and outcome in men, thus confirming the importance to analyse the impact of sex and gender in new and emerging diseases
Genetic and non-genetic risk factors for early-onset pancreatic cancer
Early-onset pancreatic cancer (EOPC) represents 5-10% of all pancreatic ductal adenocarcinoma (PDAC) cases, and the etiology of this form is poorly understood. It is not clear if established PDAC risk factors have the same relevance for younger patients. This study aims to identify genetic and non-genetic risk factors specific to EOPC.A genome-wide association study was performed, analysing 912 EOPC cases and 10 222 controls, divided into discovery and replication phases. Furthermore, the associations between a polygenic risk score (PRS), smoking, alcohol consumption, type 2 diabetes and PDAC risk were also assessed.Six novel SNPs were associated with EOPC risk in the discovery phase, but not in the replication phase. The PRS, smoking, and diabetes affected EOPC risk. The OR comparing current smokers to never-smokers was 2.92 (95% CI 1.69-5.04, P = 1.44 × 10-4). For diabetes, the corresponding OR was 14.95 (95% CI 3.41-65.50, P = 3.58 × 10-4).In conclusion, we did not identify novel genetic variants associated specifically with EOPC, and we found that established PDAC risk variants do not have a strong age-dependent effect. Furthermore, we add to the evidence pointing to the role of smoking and diabetes in EOPC
Protection against severe COVID-19 after second booster dose of adapted bivalent (original/Omicron BA.4-5) mRNA vaccine in persons ≥ 60 years, by time since infection, Italy, 12 September to 11 December 2022
: Effectiveness against severe COVID-19 of a second booster dose of the bivalent (original/BA.4-5) mRNA vaccine 7-90 days post-administration, relative to a first booster dose of an mRNA vaccine received ≥ 120 days earlier, was ca 60% both in persons ≥ 60 years never infected and in those infected > 6 months before. Relative effectiveness in those infected 4-6 months earlier indicated no significant additional protection (10%; 95% CI: -44 to 44). A second booster vaccination 6 months after the latest infection may be warranted
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