Extraction, Storage and Eruption of Multiple Isolated Magma Batches in the Paired Mamaku and Ohakuri Eruption, Taupo Volcanic Zone, New Zealand

The Taupo Volcanic Zone (TVZ) is well known for its extraordinary rate of rhyolitic magma generation and caldera-forming eruptions. Less is known about how large volumes of rhyolitic magma are extracted and stored prior to eruption, and the role tectonics might play in the process of melt extraction and control of caldera eruption(s). Here we present a new model for the extraction, storage and simultaneous eruption of the >245 km3 paired Mamaku and Ohakuri magmas sourced from calderas centred ∼30 km apart (the Rotorua and Ohakuri calderas, respectively) in the central TVZ. The Mamaku and Ohakuri ignimbrites share a similar bulk pumice composition and the same phenocryst assemblage; however, bulk-rock compositions suggest several poorly mixed magma types in each erupted volume, which are randomly distributed throughout the eruptive deposits. To refine models of the pre-eruptive geometry of the magmatic system and discuss a possible origin for triggering of each eruption, we present an expanded database of matrix glass and quartz-hosted melt inclusion compositions along with the existing bulk-rock and mineral compositions. Major and trace element compositions show that the region produced five different magma batches, extracted from the same source region, and a continuous intermediate mush zone beneath the Mamaku-Ohakuri region is suggested here. These magma batches were most probably juxtaposed but isolated from each other in the upper crust, and evolved separately until eruption. The observed geochemical differences between the batches are likely to be generated by different extraction conditions of the rhyolitic melt from a slightly heterogeneous mush. The lack of evidence for more mafic recharge prior to eruption (for example, there are no bright cathodoluminescence rims on quartz crystals) suggests that a magmatic input is unlikely to be an eruption trigger. However, tectonic activity could be an efficient way to trigger the eruption of isolated magma batches, with the evacuation of one magma batch causing a disturbance to the local stress field and activating regionally linked faults, which then lead to the eruption of additional magma batches and associated caldera subsidence. In addition, the extensional tectonic regime coupled with a high heat flux could be the controlling factor in the emplacement of some of the shallowest and most SiO2-rich magmas on Eart

Guidance for Rebooting Electrophysiology Through the COVID-19 Pandemic From the Heart Rhythm Society and the American Heart Association Electrocardiography and Arrhythmias Committee of the Council on Clinical Cardiology: Endorsed by the American College of Cardiology

© 2020 The Heart Rhythm Society, the American Heart Association, Inc., and the American College of Cardiology Foundation Coronavirus disease 2019 (COVID-19) has presented substantial challenges to patient care and impacted health care delivery, including cardiac electrophysiology practice throughout the globe. Based upon the undetermined course and regional variability of the pandemic, there is uncertainty as to how and when to resume and deliver electrophysiology services for arrhythmia patients. This joint document from representatives of the Heart Rhythm Society, American Heart Association, and American College of Cardiology seeks to provide guidance for clinicians and institutions reestablishing safe electrophysiological care. To achieve this aim, we address regional and local COVID-19 disease status, the role of viral screening and serologic testing, return-to-work considerations for exposed or infected health care workers, risk stratification and management strategies based on COVID-19 disease burden, institutional preparedness for resumption of elective procedures, patient preparation and communication, prioritization of procedures, and development of outpatient and periprocedural care pathways

Redefining Simulation Fidelity for Healthcare Education

Background. Fidelity - an intrinsic property of simulation is crucial to simulation design and to educational effectiveness. Yet the term fidelity is inconsistently used, which makes it difficult to draw inferences from current literature and translate research into practice. Aim. In this article, we attempt to bring some clarity to the term simulation fidelity in healthcare education. Method. We are opposed to the notion that high-fidelity simulation requires complete and faithful replication of reality, and instead argue for an accurate representation of real-world cues and stimuli. We address a number of issues surrounding the term fidelity and how it is currently used in the literature. Result. In recognising the limitations of current methods of describing fidelity in the literature, we propose an alternative 3-dimensional framework for fidelity along the axes of the patient, clinical scenario, and healthcare facilities as a means for more precise and practical positioning of current healthcare simulation activities. Conclusion. All aspects of fidelity significantly hinge on the learners’ perceived realism of the context of the learning episode as opposed to any one particular element such as the technology used.Peer reviewe

Assessment of the population-level eff ectiveness of the Avahan HIV-prevention programme in South India: a preplanned, causal-pathway-based modelling analysis

Background Avahan, the India AIDS initiative of the Bill & Melinda Gates Foundation, was a large-scale, targeted HIV prevention intervention. We aimed to assess its overall eff ectiveness by estimating the number and proportion of HIV infections averted across Avahan districts, following the causal pathway of the intervention. Methods We created a mathematical model of HIV transmission in high-risk groups and the general population using data from serial cross-sectional surveys (integrated behavioural and biological assessments, IBBAs) within a Bayesian framework, which we used to reproduce HIV prevalence trends in female sex workers and their clients, men who have sex with men, and the general population in 24 South Indian districts over the fi rst 4 years (2004–07 or 2005–08 dependent on the district) and the full 10 years (2004–13) of the Avahan programme. We tested whether these prevalence trends were more consistent with self-reported increases in consistent condom use after the implementation of Avahan or with a counterfactual (assuming consistent condom use increased at slower, pre-Avahan rates) using a Bayes factor, which gave a measure of the strength of evidence for the eff ectiveness estimates. Using regression analysis, we extrapolated the prevention eff ect in the districts covered by IBBAs to all 69 Avahan districts. Findings In 13 of 24 IBBA districts, modelling suggested medium to strong evidence for the large self-reported increase in consistent condom use since Avahan implementation. In the remaining 11 IBBA districts, the evidence was weaker, with consistent condom use generally already high before Avahan began. Roughly 32 700 HIV infections (95% credibility interval 17 900–61 600) were averted over the fi rst 4 years of the programme in the IBBA districts with moderate to strong evidence. Addition of the districts with weaker evidence increased this total to 62 800 (32 000–118 000) averted infections, and extrapolation suggested that 202 000 (98 300–407 000) infections were averted across all 69 Avahan districts in South India, increasing to 606 000 (290 000–1 193 000) over 10 years. Over the fi rst 4 years of the programme 42% of HIV infections were averted, and over 10 years 57% were averted. Interpretation This is the fi rst assessment of Avahan to account for the causal pathway of the intervention, that of changing risk behaviours in female sex workers and high-risk men who have sex with men to avert HIV infections in these groups and the general population. The fi ndings suggest that substantial preventive eff ects can be achieved by targeted behavioural HIV prevention initiatives

Factors Associated with Sexual Violence against Men Who Have Sex with Men and Transgendered Individuals in Karnataka, India

There is a lack of information on sexual violence (SV) among men who have sex with men and transgendered individuals (MSM-T) in southern India. As SV has been associated with HIV vulnerability, this study examined health related behaviours and practices associated with SV among MSM-T.Data were from cross-sectional surveys from four districts in Karnataka, India.Multivariable logistic regression models were constructed to examine factors related to SV. Multivariable negative binomial regression models examined the association between physician visits and SV.A total of 543 MSM-T were included in the study. Prevalence of SV was 18% in the past year. HIV prevalence among those reporting SV was 20%, compared to 12% among those not reporting SV (p = .104). In multivariable models, and among sex workers, those reporting SV were more likely to report anal sex with 5+ casual sex partners in the past week (AOR: 4.1; 95%CI: 1.2-14.3, p = .029). Increased physician visits among those reporting SV was reported only for those involved in sex work (ARR: 1.7; 95%CI: 1.1-2.7, p = .012).These results demonstrate high levels of SV among MSM-T populations, highlighting the importance of integrating interventions to reduce violence as part of HIV prevention programs and health services

Climbing the crustal ladder: Magma storage-depth evolution during a volcanic flare-up

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Science Advances 4 (2018): eaap7567, doi:10.1126/sciadv.aap7567.Very large eruptions (>50 km3) and supereruptions (>450 km3) reveal Earth’s capacity to produce and store enormous quantities (>1000 km3) of crystal-poor, eruptible magma in the shallow crust. We explore the interplay between crustal evolution and volcanism during a volcanic flare-up in the Taupo Volcanic Zone (TVZ, New Zealand) using a combination of quartz-feldspar-melt equilibration pressures and time scales of quartz crystallization. Over the course of the flare-up, crystallization depths became progressively shallower, showing the gradual conditioning of the crust. Yet, quartz crystallization times were invariably very short (<100 years), demonstrating that very large reservoirs of eruptible magma were transient crustal features. We conclude that the dynamic nature of the TVZ crust favored magma eruption over storage. Episodic tapping of eruptible magmas likely prevented a supereruption. Instead, multiple very large bodies of eruptible magma were assembled and erupted in decadal time scales.This work was supported by the NSF (EAR-1151337) and by two Vanderbilt University Discovery Grants