Holocene earthquake-triggered mass-wasting events recorded in the sediments of Lake Puyehue (South-Central Chile)

Despite South-Central Chile’s high seismicity and the occurrence of earth’s largest instrumentally recorded earthquake (AD 1960; Mw: 9.5), paleoseismic data is still scarce for this region. In this study, very high-resolution reflection seismic profiles (3.5 kHz) in Lake Puyehue (41°S) were utilized to trace giant seismic events back into time. The seismic profiles show repeated occurrences of multiple mass-wasting deposits (slumps, debris flows, homogenites) occurring at a same seismic-stratigraphic horizon, indicating that they are coeval and caused by a single mass-wasting event of basin-wide importance. An age-depth model, based on 9 AMS radiocarbon datings and varve-counting on an 11 m-long sediment core, has been used to develop a “seismic chronostratigraphy”. It allows dating of the mass-wasting events by interpolation between dated seismic horizons to the distal parts of the mass-wasting deposits. The mass-wasting events are assumed to be earthquake-triggered because:The recentmost mass-wasting events correlate with the devastating historical earthquakes of AD 1575 and AD 1960.Synchronicity of multiple slope failures (mass-wasting events) requires a strong regional trigger, such as an earthquake. Consequently, local slope oversteepening at delta fronts or local fluid expulsion could not initiate such widespread events.South-Central Chile has been historically subjected to several strong (M > 8) subduction earthquakes and subduction processes have been constantly active since Mesozoic times.Multiple slope failures occur at water depths > 70 m, which rules out shallow instability triggers, such as storm wave action and lake-level fluctuations.This study reveals nine paleoseismic events during the Holocene with a mean recurrence rate of about 1000 yr, but with an overall relatively aperiodic occurrence (ranging between 400-2000 yrs.). The most prominent event took place around 1660 cal. yr. BP, evidenced by at least 29 simultaneous mass-movements and a homogenite deposit. Quantitative comparison of mass-wasting events related to the historical earthquakes of AD 1960 and AD 1575 showed significant differences (respectively 17 and 4 observed mass-wasting deposits) although these earthquakes are assumed to have had a comparable strength. This can be attributed to a lowered sedimentation rate on the potentially unstable slopes in the period 3000 cal. yr. BP – 500 cal. yr. BP, which would have made lacustrine earthquake recording less likely in AD 1575. The absence of mass-wasting deposits associated with other historical earthquakes (e.g.: AD 1737 (Ms: 7.5) and AD 1837 (Ms: 8)) indicates that only mega-earthquakes (Mw >8.5) within a range of about 300 km are recorded in the sedimentary sequence of Lake Puyehue.Reflection seismic profiles also show vertical fluidisation structures with large-scale sediment injections, which disturb the upper sedimentary sequences. The top of these fluidisation structures and diverse deformation levels could be spatially linked to seismically induced mass-wasting deposits and consequently indicate an additional method for lacustrine paleo-earthquake tracing.Several reconaissance seismic surveys on other glacigenic lakes in the Chilean Lake District also show promising paleoseismic records, which will offer the opportunity to correlate lacustrine records to reveal South-Central Chile’s paleoseismic history in detail and the earthquake registration capacities of its glacigenic lakes

The 600 yr eruptive history of Villarrica Volcano (Chile) revealed by annually laminated lake sediments

Lake sediments contain valuable information about past volcanic and seismic events that have affected the lake catchment, and they provide unique records of the recurrence interval and magnitude of such events. This study uses a multilake and multiproxy analytical approach to obtain reliable and high-resolution records of past natural catastrophes from similar to 600-yr-old annually laminated (varved) lake sediment sequences extracted from two lakes, Villarrica and Calafquen, in the volcanically and seismically active Chilean Lake District. Using a combination of micro-X-ray fluorescence (mu XRF) scanning, microfacies analysis, grain-size analysis, color analysis, and magnetic-susceptibility measurements, we detect and characterize four different types of event deposits (lacustrine turbidites, tephra-fall layers, runoff cryptotephras, and lahar deposits) and produce a revised eruption record for Villarrica Volcano, which is unprecedented in its continuity and temporal resolution. Glass geochemistry and mineralogy also reveal deposits of eruptions from the more remote Carran-Los Venados volcanic complex, Quetrupillan Volcano, and the Huanquihue Group in the studied lake sediments. Time-series analysis shows 112 eruptions with a volcanic explosivity index (VEI) >= 2 from Villarrica Volcano in the last similar to 600 yr, of which at least 22 also produced lahars. This significantly expands our knowledge of the eruptive frequency of the volcano in this time window, compared to the previously known eruptive history from historical records. The last VEI >= 2 eruption of Villarrica Volcano occurred in 1991. Based on the last similar to 500 yr, for which we have a complete record from both lakes, we estimate the probability of the occurrence of future eruptions from Villarrica Volcano and statistically demonstrate that the probability of a 22 yr repose period (anno 2013) without VEI >= 2 eruptions is <= 1.7%. This new perspective on the recurrence interval of eruptions and historical lahar activity will help improve volcanic hazard assessments for this rapidly expanding tourist region, and it highlights how lake records can be used to significantly improve historical eruption records in areas that were previously uninhabited

Phase I clinical trial of an intranodally administered mRNA-based therapeutic vaccine against HIV-1 infection

OBJECTIVE: The efficacy of therapeutic vaccines against HIV-1 infection has been modest. New inerts to redirect responses to vulnerable sites are urgently needed to improve these results.DESIGN: We performed the first-in-human clinical trial with naked mRNA (iHIVARNA) combining a dendritic cell activation strategy (TriMix:CD40L+CD70+caTLR4 RNA) with a novel HIV immunogen sequences (HTI immunogen).METHODS: A dose escalation, phase I clinical trial was performed in 21 chronic HIV-1-infected patients under ART who received three intranodal doses of mRNA (weeks 0, 2 and 4

What makes a bully a cyberbully? Unravelling the characteristics of cyberbullies across twenty-five European countries

The characteristics of bullies who act face-to-face and those who do so in cyberspace were compared directly in one sample across twenty-five countries. The role of cross-country differences in technological infrastructure was also explored. Cyberbullies compared to face-to-face bullies were more likely to engage in risky online activities, spend more time online, and found it easier to be themselves online. Private access to the internet did not make a difference. Gender differences showed girls more likely to be cyber- than face-to-face bullies if they have a profile on a social networking site. Age and internet ability beliefs were also positively but not independently associated with cyberbullying. Cross-country differences were small and patterns remained mostly stable across countries, suggesting that individual and not country-level characteristics are pivotal in explaining cyberbullying

Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19

BACKGROUND REGEN-COV (previously known as REGN-COV2), a combination of the monoclonal antibodies casirivimab and imdevimab, has been shown to markedly reduce the risk of hospitalization or death among high-risk persons with coronavirus disease 2019 (Covid-19). Whether subcutaneous REGEN-COV prevents severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and subsequent Covid-19 in persons at high risk for infection because of household exposure to a person with SARS-CoV-2 infection is unknown. METHODS We randomly assigned, in a 1:1 ratio, participants (=12 years of age) who were enrolled within 96 hours after a household contact received a diagnosis of SARSCoV- 2 infection to receive a total dose of 1200 mg of REGEN-COV or matching placebo administered by means of subcutaneous injection. At the time of randomization, participants were stratified according to the results of the local diagnostic assay for SARS-CoV-2 and according to age. The primary efficacy end point was the development of symptomatic SARS-CoV-2 infection through day 28 in participants who did not have SARS-CoV-2 infection (as measured by reverse-transcriptase- quantitative polymerase-chain-reaction assay) or previous immunity (seronegativity). RESULTS Symptomatic SARS-CoV-2 infection developed in 11 of 753 participants in the REGEN-COV group (1.5%) and in 59 of 752 participants in the placebo group (7.8%) (relative risk reduction [1 minus the relative risk], 81.4%; P104 copies per milliliter) was shorter (0.4 weeks and 1.3 weeks, respectively). No dose-limiting toxic effects of REGEN-COV were noted. CONCLUSIONS Subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. Among the participants who became infected, REGEN-COV reduced the duration of symptomatic disease and the duration of a high viral load