Fall-experiments on Merapi basaltic andesite and constraints on the generation of pyroclastic surges

International audienceWe have performed fall-experiments with basaltic andesite rock samples from Merapi volcano, using an apparatus designed to analyze samples heated up to 850°C. Relative pressure changes during impact and fragmentation of the samples were measured by a pressure transducer. From 200°C, dynamic pressure waves were formed on impact and fragmentation. Peak and duration of the pressure signal, and degree of fragmentation were found to strongly increase with increasing temperature of rock samples. The pressure waves are most likely generated by sudden heating of air forcing it to expand. We propose that the observed pressure changes are analogues to pyroclastic surges that may be generated on impact and fragmentation of large blocks during passage of a pyroclastic flow over a steep cliff. We infer that rock temperatures of ca. 400°C are sufficient for this process to occur, a temperature common in pyroclastic flows even in distal reaches

Mapping Patent Classifications: Portfolio and Statistical Analysis, and the Comparison of Strengths and Weaknesses

The Cooperative Patent Classifications (CPC) jointly developed by the European and US Patent Offices provide a new basis for mapping and portfolio analysis. This update provides an occasion for rethinking the parameter choices. The new maps are significantly different from previous ones, although this may not always be obvious on visual inspection. Since these maps are statistical constructs based on index terms, their quality--as different from utility--can only be controlled discursively. We provide nested maps online and a routine for portfolio overlays and further statistical analysis. We add a new tool for "difference maps" which is illustrated by comparing the portfolios of patents granted to Novartis and MSD in 2016.Comment: Scientometrics 112(3) (2017) 1573-1591; http://link.springer.com/article/10.1007/s11192-017-2449-

Stratigraphic reconstruction of the Víti breccia at Krafla volcano (Iceland): insights into pre-eruptive conditions priming explosive eruptions in geothermal areas

Krafla central volcano in Iceland has experienced numerous basaltic fissure eruptions through its history, the most recent examples being the Mývatn (1724‒1729) and Krafla Fires (1975-1984). The Mývatn Fires opened with a steam-driven eruption that produced the Víti crater. A magmatic intrusion has been inferred as the trigger perturbing the geothermal field hosting Víti, but the cause(s) of the explosive response remain uncertain. Here, we present a detailed stratigraphic reconstruction of the breccia erupted from Víti crater, characterize the lithologies involved in the explosions, reconstruct the pre-eruptive setting, fingerprint the eruption trigger and source depth, and reveal the eruption mechanisms. Our results suggest that the Víti eruption can be classified as a magmatic-hydrothermal type and that it was a complex event with three eruption phases. The injection of rhyolite below a pre-existing convecting hydrothermal system likely triggered the Víti eruption. Heating and pressurization of shallow geothermal fluid initiated disruption of a scoria cone \textquotedblcap\textquotedbl via an initial series of small explosions involving a pre-existing altered weak zone, with ejection of fragments from at least 60-m depth. This event was superseded by larger, broader, and dominantly shallow explosions (\~ 200~m depth) driven by decompression of hydrothermal fluids within highly porous, poorly compacted tuffaceous hyaloclastite. This second phase was triggered when pressurized fluids broke through the scoria cone complex \textquotedblcap\textquotedbl. At the same time, deep-rooted explosions (\~ 1-km depth) began to feed the eruption with large inputs of fragmented rhyolitic juvenile and host rock from a deeper zone. Shallow explosions enlarging the crater dominated the final phase. Our results indicate that at Krafla, as in similar geological contexts, shallow and thin hyaloclastite sequences hosting hot geothermal fluids and capped by low-permeability lithologies (e.g. altered scoria cone complex and/or massive, thick lava flow sequence) are susceptible to explosive failure in the case of shallow magmatic intrusion(s). Supplementary Information The online version contains supplementary material available at 10.1007/s00445-021-01502-y

Coronary atherosclerosis screening in asymptomatic adults using coronary artery calcium for cardiovascular prevention: a systematic review of randomised controlled trials and prospective cohorts.

To review the available evidence of screening for atherosclerosis in adults in a primary prevention setting with coronary artery calcium scoring (CACS) on the impact on cardiovascular (CV) risk factor control, health behaviour and clinical events. Systematic review, reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE, Embase and Cochrane Central Register of Controlled Trials through 22 January 2025. We included randomised controlled trials (RCTs) and prospective cohorts, without language restrictions, comparing adults without cardiovascular diseases undergoing CACS to a control group that either did not undergo CACS or where the participants and physicians were blinded to its result. Outcomes included changes in CV risk factor control, CV therapy, changes in health behaviour at follow-up and clinical events (all-cause and CV mortality and non-fatal CV events). Two independent reviewers extracted data and assessed the risk of bias. Due to substantial heterogeneity among the included studies, a quantitative analysis was not possible. We identified seven RCTs and one observational study, with participants ranging from 56 to 43 447 with a total of 51 554. Populations were heterogeneous with a mean age range of 42-64 years, % women ranging from 21% to 100% and mean baseline CACS from 1.37 to >100 Agatston units. Interventions following CACS were also heterogeneous, ranging from simply communicating results to participants to initiating statin therapy for detectable CACS. One RCT demonstrated improvement regarding blood pressure (BP) (n=2137; change in systolic BP: CACS: -5 mm Hg; control: -7 mm Hg; p=0.02), several an improvement in blood lipids between groups (five studies, n=3693; eg, low-density lipoprotein (LDL) cholesterol: range -6.0 to -4.9 mg/dL). Results regarding CV medication (seven studies, n=51 104) were more discrepant, with some studies showing a decrease and others an increase in indication for or usage of CV medication. Three trials (n=3338) investigated adherence to CV medication, with only one showing increased adherence to statins (CACS: 63.3%; control: 45.6%; p=0.03). Five trials (n=3692) investigated behavioural changes, with one showing an increased motivation to change lifestyle (CACS: 94%; control: 62.8%; p=0.002) and another a higher adherence in self-reported physical activity (CACS: 96%; control: 59%; p<0.01). Due to low event rates, short follow-up and/or limited sample size, none (three studies, n=6552) demonstrated an effect on clinical CV events or all-cause mortality. Heterogeneity in interventions following CACS, population and studied outcomes did not permit pooling of results. Key limitations of this review reflect the limited availability of evidence and include the omission of potential harms of CACS screening, study heterogeneity, insufficient data on clinical events, a lack of economic assessments and the moderate to high risk of bias in most studies. CACS screening with a CACS-guided intervention might have a favourable effect on CV risk factor control and potentially on adherence to CV medication and increased motivation to change lifestyle in populations at intermediate to high risk. The available evidence is insufficient to determine whether screening asymptomatic patients with CACS has an impact on all-cause mortality or CV events. Despite its known strengths in predicting outcomes in individual patients, more evidence regarding the impact on clinical outcomes is needed to determine the clinical use of CACS for screening purposes in asymptomatic patients. CRD42022377727

The evolutionary dynamics of microRNAs in domestic mammals

MiRNAs are crucial regulators of gene expression found across both the plant and animal kingdoms. While the number of annotated miRNAs deposited in miRBase has greatly increased in recent years, few studies provided comparative analyses across sets of related species, or investigated the role of miRNAs in the evolution of gene regulation. We generated small RNA libraries across 5 mammalian species (cow, dog, horse, pig and rabbit) from 4 different tissues (brain, heart, kidney and testis). We identified 1676 miRBase and 413 novel miRNAs by manually curating the set of computational predictions obtained from miRCat and miRDeep2. Our dataset spanning five species has enabled us to investigate the molecular mechanisms and selective pressures driving the evolution of miRNAs in mammals. We highlight the important contributions of intronic sequences (366 orthogroups), duplication events (135 orthogroups) and repetitive elements (37 orthogroups) in the emergence of new miRNA loci. We use this framework to estimate the patterns of gains and losses across the phylogeny, and observe high levels of miRNA turnover. Additionally, the identification of lineage-specific losses enables the characterisation of the selective constraints acting on the associated target sites. Compared to the miRBase subset, novel miRNAs tend to be more tissue specific. 20 percent of novel orthogroups are restricted to the brain, and their target repertoires appear to be enriched for neuron activity and differentiation processes. These findings may reflect an important role for young miRNAs in the evolution of brain expression plasticity. Many seed sequences appear to be specific to either the cow or the dog. Analyses on the associated targets highlight the presence of several genes under artificial positive selection, suggesting an involvement of these miRNAs in the domestication process. Altogether, we provide an overview on the evolutionary mechanisms responsible for miRNA turnover in 5 domestic species, and their possible contribution to the evolution of gene regulation