Timescales for pluton growth, magma-chamber formation and super-eruptions.

Generation of silicic magmas leads to emplacement of granite plutons, huge explosive volcanic eruptions and physical and chemical zoning of continental and arc crust1-7. Whereas timescales for silicic magma generation in the deep and middle crust are prolonged8, magma transfer into the upper crust followed by eruption is episodic and can be rapid9-12. Ages of inherited zircons and sanidines from four Miocene ignimbrites in the Central Andes indicate a gap of 4.6 Myr between initiation of pluton emplacement and onset of super-eruptions, with a 1-Myr cyclicity. We show that inherited zircons and sanidine crystals were stored at temperatures <470 °C in these plutons before incorporation in ignimbrite magmas. Our observations can be explained by silicic melt segregation in a middle-crustal hot zone with episodic melt ascent from an unstable layer at the top of the zone with a timescale governed by the rheology of the upper crust. After thermal incubation of growing plutons, large upper-crustal magma chambers can form in a few thousand years or less by dike transport from the hot-zone melt layer. Instability and disruption of earlier plutonic rock occurred in a few decades or less just before or during super-eruptions.

Continental flood basalts drive Phanerozoic extinctions.

Refinements of the geological timescale driven by the increasing precision and accuracy of radiometric dating have revealed an apparent correlation between large igneous provinces (LIPs) and intervals of Phanerozoic faunal turnover that has been much discussed at a qualitative level. However, the extent to which such correlations are likely to occur by chance has yet to be quantitatively tested, and other kill mechanisms have been suggested for many mass extinctions. Here, we show that the degree of temporal correlation between continental LIPs and faunal turnover in the Phanerozoic is unlikely to occur by chance, suggesting a causal relationship linking extinctions and continental flood basalts. The relationship is stronger for LIPs with higher estimated eruptive rates and for stage boundaries with higher extinction magnitudes. This suggests LIP magma degassing as a primary kill mechanism for mass extinctions and other intervals of faunal turnover, which may be related to [Formula: see text], Cl, and F release. Our results suggest continental LIPs as a major, direct driver of extinctions throughout the Phanerozoic.

Thermochronologic constraints on the origin of the Great Unconformity.

The origin of the phenomenon known as the Great Unconformity has been a fundamental yet unresolved problem in the geosciences for over a century. Recent hypotheses advocate either global continental exhumation averaging 3 to 5 km during Cryogenian (717 to 635 Ma) snowball Earth glaciations or, alternatively, diachronous episodic exhumation throughout the Neoproterozoic (1,000 to 540 Ma) due to plate tectonic reorganization from supercontinent assembly and breakup. To test these hypotheses, the temporal patterns of Neoproterozoic thermal histories were evaluated for four North American locations using previously published medium- to low-temperature thermochronology and geologic information. We present inverse time-temperature simulations within a Bayesian modeling framework that record a consistent signal of relatively rapid, high-magnitude cooling of ∼120 to 200 °C interpreted as erosional exhumation of upper crustal basement during the Cryogenian. These models imply widespread, synchronous cooling consistent with at least ∼3 to 5 km of unroofing during snowball Earth glaciations, but also demonstrate that plate tectonic drivers, with the potential to cause both exhumation and burial, may have significantly influenced the thermal history in regions that were undergoing deformation concomitant with glaciation. In the cratonic interior, however, glaciation remains the only plausible mechanism that satisfies the required timing, magnitude, and broad spatial pattern of continental erosion revealed by our thermochronological inversions. To obtain a full picture of the extent and synchroneity of such erosional exhumation, studies on stable cratonic crust below the Great Unconformity must be repeated on all continents.

A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts.

The oxygenation of the deep ocean in the geological past has been associated with a rise in the partial pressure of atmospheric molecular oxygen (O2) to near-present levels and the emergence of modern marine biogeochemical cycles. It has also been linked to the origination and diversification of early animals. It is generally thought that the deep ocean was largely anoxic from about 2,500 to 800 million years ago, with estimates of the occurrence of deep-ocean oxygenation and the linked increase in the partial pressure of atmospheric oxygen to levels sufficient for this oxygenation ranging from about 800 to 400 million years ago. Deep-ocean dissolved oxygen concentrations over this interval are typically estimated using geochemical signatures preserved in ancient continental shelf or slope sediments, which only indirectly reflect the geochemical state of the deep ocean. Here we present a record that more directly reflects deep-ocean oxygen concentrations, based on the ratio of Fe3+ to total Fe in hydrothermally altered basalts formed in ocean basins. Our data allow for quantitative estimates of deep-ocean dissolved oxygen concentrations from 3.5 billion years ago to 14 million years ago and suggest that deep-ocean oxygenation occurred in the Phanerozoic (541 million years ago to the present) and potentially not until the late Palaeozoic (less than 420 million years ago).

Heterogeneous Hadean crust with ambient mantle affinity recorded in detrital zircons of the Green Sandstone Bed, South Africa.

The nature of Earth's earliest crust and the processes by which it formed remain major issues in Precambrian geology. Due to the absence of a rock record older than ∼4.02 Ga, the only direct record of the Hadean is from rare detrital zircon and that largely from a single area: the Jack Hills and Mount Narryer region of Western Australia. Here, we report on the geochemistry of Hadean detrital zircons as old as 4.15 Ga from the newly discovered Green Sandstone Bed in the Barberton greenstone belt, South Africa. We demonstrate that the U-Nb-Sc-Yb systematics of the majority of these Hadean zircons show a mantle affinity as seen in zircon from modern plume-type mantle environments and do not resemble zircon from modern continental or oceanic arcs. The zircon trace element compositions furthermore suggest magma compositions ranging from higher temperature, primitive to lower temperature, and more evolved tonalite-trondhjemite-granodiorite (TTG)-like magmas that experienced some reworking of hydrated crust. We propose that the Hadean parental magmas of the Green Sandstone Bed zircons formed from remelting of mafic, mantle-derived crust that experienced some hydrous input during melting but not from the processes seen in modern arc magmatism.

InSPECtor: an end-to-end design framework for compressive pixelated hyperspectral instruments.

Classic designs of hyperspectral instrumentation densely sample the spatial and spectral information of the scene of interest. Data may be compressed after the acquisition. In this paper, we introduce a framework for the design of an optimized, micropatterned snapshot hyperspectral imager that acquires an optimized subset of the spatial and spectral information in the scene. The data is thereby already compressed at the sensor level but can be restored to the full hyperspectral data cube by the jointly optimized reconstructor. This framework is implemented with TensorFlow and makes use of its automatic differentiation for the joint optimization of the layout of the micropatterned filter array as well as the reconstructor. We explore the achievable compression ratio for different numbers of filter passbands, number of scanning frames, and filter layouts using data collected by the Hyperscout instrument. We show resulting instrument designs that take snapshot measurements without losing significant information while reducing the data volume, acquisition time, or detector space by a factor of 40 as compared to classic, dense sampling. The joint optimization of a compressive hyperspectral imager design and the accompanying reconstructor provides an avenue to substantially reduce the data volume from hyperspectral imagers.

Constraining crustal silica on ancient Earth.

Accurately quantifying the composition of continental crust on Hadean and Archean Earth is critical to our understanding of the physiography, tectonics, and climate of our planet at the dawn of life. One longstanding paradigm involves the growth of a relatively mafic planetary crust over the first 1 to 2 billion years of Earth history, implying a lack of modern plate tectonics and a paucity of subaerial crust, and consequently lacking an efficient mechanism to regulate climate. Others have proposed a more uniformitarian view in which Archean and Hadean continents were only slightly more mafic than at present. Apart from complications in assessing early crustal composition introduced by crustal preservation and sampling biases, effects such as the secular cooling of Earth's mantle and the biologically driven oxidation of Earth's atmosphere have not been fully investigated. We find that the former complicates efforts to infer crustal silica from compatible or incompatible element abundances, while the latter undermines estimates of crustal silica content inferred from terrigenous sediments. Accounting for these complications, we find that the data are most parsimoniously explained by a model with nearly constant crustal silica since at least the early Archean.

Neoproterozoic glacial origin of the Great Unconformity.

The Great Unconformity, a profound gap in Earth's stratigraphic record often evident below the base of the Cambrian system, has remained among the most enigmatic field observations in Earth science for over a century. While long associated directly or indirectly with the occurrence of the earliest complex animal fossils, a conclusive explanation for the formation and global extent of the Great Unconformity has remained elusive. Here we show that the Great Unconformity is associated with a set of large global oxygen and hafnium isotope excursions in magmatic zircon that suggest a late Neoproterozoic crustal erosion and sediment subduction event of unprecedented scale. These excursions, the Great Unconformity, preservational irregularities in the terrestrial bolide impact record, and the first-order pattern of Phanerozoic sedimentation can together be explained by spatially heterogeneous Neoproterozoic glacial erosion totaling a global average of 3-5 vertical kilometers, along with the subsequent thermal and isostatic consequences of this erosion for global continental freeboard.

LOUPE: observing Earth from the Moon to prepare for detecting life on Earth-like exoplanets.

LOUPE, the Lunar Observatory for Unresolved Polarimetry of the Earth, is a small, robust spectro-polarimeter for observing the Earth as an exoplanet. Detecting Earth-like planets in stellar habitable zones is one of the key challenges of modern exoplanetary science. Characterizing such planets and searching for traces of life requires the direct detection of their signals. LOUPE provides unique spectral flux and polarization data of sunlight reflected by Earth, the only planet known to harbour life. These data will be used to test numerical codes to predict signals of Earth-like exoplanets, to test algorithms that retrieve planet properties, and to fine-tune the design and observational strategies of future space observatories. From the Moon, LOUPE will continuously see the entire Earth, enabling it to monitor the signal changes due to the planet's daily rotation, weather patterns and seasons, across all phase angles. Here, we present both the science case and the technology behind LOUPE's instrumental and mission design. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades'.

Volcanic-plutonic parity and the differentiation of the continental crust.

The continental crust is central to the biological and geological history of Earth. However, crustal heterogeneity has prevented a thorough geochemical comparison of its primary igneous building blocks-volcanic and plutonic rocks-and the processes by which they differentiate to felsic compositions. Our analysis of a comprehensive global data set of volcanic and plutonic whole-rock geochemistry shows that differentiation trends from primitive basaltic to felsic compositions for volcanic versus plutonic samples are generally indistinguishable in subduction-zone settings, but are divergent in continental rifts. Offsets in major- and trace-element differentiation patterns in rift settings suggest higher water content in plutonic magmas and reduced eruptibility of hydrous silicate magmas relative to dry rift volcanics. In both tectonic settings, our results indicate that fractional crystallization, rather than crustal melting, is predominantly responsible for the production of intermediate and felsic magmas, emphasizing the role of mafic cumulates as a residue of crustal differentiation.

Vector-apodizing phase plate coronagraph: design, current performance, and future development [Invited].

Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8 m class telescopes. The vAPP is a geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagraphic point spread functions (PSFs) that cancel starlight on opposite sides of the PSF and have opposite circular polarization states. The efficiency, that is, the amount of light in these PSFs, depends on the retardance offset from a half-wave of the liquid-crystal retarder. Using different liquid-crystal recipes to tune the retardance, different vAPPs operate with high efficiencies (${\gt}96\%$) in the visible and thermal infrared (0.55 µm to 5 µm). Since 2015, seven vAPPs have been installed in a total of six different instruments, including Magellan/MagAO, Magellan/MagAO-X, Subaru/SCExAO, and LBT/LMIRcam. Using two integral field spectrographs installed on the latter two instruments, these vAPPs can provide low-resolution spectra (${\rm{R}} \sim 30$) between 1 µm and 5 µm. We review the design process, development, commissioning, on-sky performance, and first scientific results of all commissioned vAPPs. We report on the lessons learned and conclude with perspectives for future developments and applications.

Potassic, high-silica Hadean crust.

Understanding Hadean (>4 Ga) Earth requires knowledge of its crust. The composition of the crust and volatiles migrating through it directly influence the makeup of the atmosphere, the composition of seawater, and nutrient availability. Despite its importance, there is little known and less agreed upon regarding the nature of the Hadean crust. By analyzing the 87Sr/86Sr ratio of apatite inclusions in Archean zircons from Nuvvuagittuq, Canada, we show that its protolith had formed a high (>1) Rb/Sr ratio reservoir by at least 4.2 Ga. This result implies that the early crust had a broad range of igneous rocks, extending from mafic to highly silicic compositions.

Highly multiplexed Bragg gratings for large field of view gas sensing in planetary atmospheres.

Detecting and monitoring gas species is an important part of remote sensing because the state of the environment can be retrieved from the state of the gas species. This can be used to track temperature and pressure structures in the atmosphere for weather predictions, or monitor the air quality. Discriminating different species is easier at higher spectral resolution when the spectral lines are clearly resolved. The need to do this at high spatial resolution and over large fields of view leads to a trade-off between spectral and spatial resolution and spectral bandwidth. We propose to use a highly multiplexed Bragg grating that can optically combine the relevant information from the spectrum without the need to disperse the whole spectrum. This allows us to circumvent the spatial and spectral trade-off and therefore substantially increase the field of view compared to conventional hyperspectral imagers. A dynamic implementation based on acousto-optical filters that can be adapted on the fly is discussed as an easy and flexible way to create the multiplexed gratings. We describe the details of multiplexed Bragg gratings and show that we can retrieve the spatial distribution of individual species abundances in gas mixtures, and we show that we can even do this for the atmospheres of exoplanets orbiting far-away stars.

[Perioperative infusion therapy in children : Are infusion sets with precision flow regulators suitable for pediatric anesthesia?] / Perioperative Infusionstherapie im Kindesalter : Eignen sich Infusionssysteme mit Laufratenbeschränkung für die Kinderanästhesie?

BACKGROUND: Infusion sets with precision flow regulators are frequently used in children undergoing surgery in order to control the perioperative administration of fluids. There are no data about the safety and accuracy of these infusion sets. A study was therefore conducted to compare adjusted and actual flow rates of three different infusion sets with precision flow regulators under standardized conditions. METHODS: The study evaluated three different infusion sets with precision flow regulators each at two different static levels. The actual flow rates of 5 infusions were recorded each time for adjusted flow rates of 50 ml/h, 100 ml/h, 150 ml/h, 200 ml/h and 250 ml/h over 1 h. Statistical analysis was performed with Excel (Excel, Microsoft Corporation, Redmond, WA, USA) and SOFA (Paton-Simpson and Associates Ltd., USA). The results are presented as means (standard deviation). RESULTS: For the adjusted flow rates of 50, 100, 150, 200 and 250 ml/h, actual flow rates were 107 (5.3), 174.8 (6.5), 255.8 (10.2), 312.4 (15.7) and 362.6 (20.2) ml/h for the Frekadrop® infusion set at a static level of 128 cm and 83.8 (4.4), 147.8 (5.5), 197 (12.4), 257.2 (4.97) and 311.6 (17.9) ml/h at a static level of 100 cm, respectively. For the Exadrop® infusion set actual flow rates were 88.6 (6.9), 131.2 (14.1), 224.4 (14.1), 296.6 (27.6) and 330.4 (22.4) ml/h at a static level of 128 cm and 54 (4), 82.4 (10.2), 138.8 (15.7), 209.4 (36.8) and 249 (12) ml/h at a static level of 76 cm, respectively. For the D-Flo infusion set actual flow rates were 95.6 (2.8), 167.6 (29), 217.8 (9.9), 281.6 (10.6) and 396.8 (37.5) ml/h at a static level of 128 cm and 69.2 (4.4), 110.2 (12.6), 169.2 (6), 205.2 (14) and 243 (15.9) ml/h at a static level of 80 cm, respectively. CONCLUSION: The actual flow rates differed considerably from the adjusted flow rates in the evaluated infusion sets. The flow rates substantially depended on the static level of the infusion. First and foremost, regulation of the administered infusion volume does not seem to be reliable when using an infusion set with a precision flow regulator.

Statistical geochemistry reveals disruption in secular lithospheric evolution about 2.5 Gyr ago.

The Earth has cooled over the past 4.5 billion years (Gyr) as a result of surface heat loss and declining radiogenic heat production. Igneous geochemistry has been used to understand how changing heat flux influenced Archaean geodynamics, but records of systematic geochemical evolution are complicated by heterogeneity of the rock record and uncertainties regarding selection and preservation bias. Here we apply statistical sampling techniques to a geochemical database of about 70,000 samples from the continental igneous rock record to produce a comprehensive record of secular geochemical evolution throughout Earth history. Consistent with secular mantle cooling, compatible and incompatible elements in basalts record gradually decreasing mantle melt fraction through time. Superimposed on this gradual evolution is a pervasive geochemical discontinuity occurring about 2.5 Gyr ago, involving substantial decreases in mantle melt fraction in basalts, and in indicators of deep crustal melting and fractionation, such as Na/K, Eu/Eu* (europium anomaly) and La/Yb ratios in felsic rocks. Along with an increase in preserved crustal thickness across the Archaean/Proterozoic boundary, these data are consistent with a model in which high-degree Archaean mantle melting produced a thick, mafic lower crust and consequent deep crustal delamination and melting--leading to abundant tonalite-trondhjemite-granodiorite magmatism and a thin preserved Archaean crust. The coincidence of the observed changes in geochemistry and crustal thickness with stepwise atmospheric oxidation at the end of the Archaean eon provides a significant temporal link between deep Earth geochemical processes and the rise of atmospheric oxygen on the Earth.

A diagnosis of eosinophilic esophagitis is associated with increased life insurance premiums.

Eosinophilic esophagitis (EoE) is a chronic disease that can be diagnosed at any age, but is not associated with malignancy and does not shorten lifespan. It remains unknown whether an EoE diagnosis affects insurability or insurance premium costs. We therefore aimed to determine whether a diagnosis of EoE affects the costs of life insurance. Our investigation was a secret shopper audit study whereby we contacted national insurance companies in the United States to evaluate the effect of a diagnosis of EoE on life insurance premiums. We constructed standardized case scenarios for males and females, including a 25-year-old and a 48-year-old without other comorbid conditions, who either had or did not have a diagnosis of EoE. Companies were asked for their best estimate for a $100,000 whole life insurance policy. Comparisons between median premiums were made using the Mann-Whitney U test. There were 20 national life insurance companies contacted and a total of 73 quotes were obtained. The median premium rate was similar for EoE and non-EoE cases at the younger age ($828 [IQR $576-1,020] vs. $756 [IQR $504-$804]; P = 0.10). However, the premium for the older case without EoE was 19% less expensive compared to a case with EoE ($1990 [IQR $1,248-2,350] vs. $2,375 [IQR $2,100-2568; P = 0.02]. This finding was not explained by sex or state of residence. Based on these findings, we conclude that life insurance premiums are significantly more expensive in the older patient case with EoE when compared to the same case without EoE. Patients with EoE and their providers should be aware of the additional cost associated with this diagnosis.

Collaborative and partnership research for improvement of health and social services: researcher's experiences from 20 projects.

BACKGROUND: Getting research into policy and practice in healthcare is a recognised, world-wide concern. As an attempt to bridge the gap between research and practice, research funders are requesting more interdisciplinary and collaborative research, while actual experiences of such processes have been less studied. Accordingly, the purpose of this study was to gain more knowledge on the interdisciplinary, collaborative and partnership research process by investigating researchers' experiences of and approaches to the process, based on their participation in an inventive national research programme. The programme aimed to boost collaborative and partnership research and build learning structures, while improving ways to lead, manage and develop practices in Swedish health and social services. METHODS: Interviews conducted with project leaders and/or lead researchers and documentation from 20 projects were analysed using directed and conventional content analysis. RESULTS: Collaborative approaches were achieved by design, e.g. action research, or by involving practitioners from several levels of the healthcare system in various parts of the research process. The use of dual roles as researcher/clinician or practitioner/PhD student or the use of education designed especially for practitioners or 'student researchers' were other approaches. The collaborative process constituted the area for the main lessons learned as well as the main problems. Difficulties concerned handling complexity and conflicts between different expectations and demands in the practitioner's and researcher's contexts, and dealing with human resource issues and group interactions when forming collaborative and interdisciplinary research teams. The handling of such challenges required time, resources, knowledge, interactive learning and skilled project management. CONCLUSIONS: Collaborative approaches are important in the study of complex phenomena. Results from this study show that allocated time, arenas for interactions and skills in project management and communication are needed during research collaboration to ensure support and build trust and understanding with involved practitioners at several levels in the healthcare system. For researchers, dealing with this complexity takes time and energy from the scientific process. For practitioners, this puts demands on understanding a research process and how it fits with on-going organisational agendas and activities and allocating time. Some of the identified factors may be overlooked by funders and involved stakeholders when designing, performing and evaluating interdisciplinary, collaborative and partnership research.

[Endoscopic triple neurectomy for tumor-induced inguinal pain syndrome]. / Endoskopische Triple-Neurektomie bei tumorbedingtem, inguinalem Schmerzsyndrom.

We report on an endoscopic triple neurectomy in a female patient with vulvar carcinoma metastasized to the left groin with refractory neuropathic inguinodynia. Using a retroperitoneoscopic approach we resected the ilioinguinal, iliohypogastric, and genitofemoral nerves. The inguinodynia improved significantly; especially the reduced ability to walk was enhanced considerably. Endoscopic triple neurectomy could be a useful therapeutic option in refractory inguinal pain caused by local tumor manifestation.