bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive bulk assimilation: A model for crust-mantle mixing in silicic magmas
Authors: Beard James S. , Ragland Paul C. , Crawford Maria Luisa 
Published: July 2019

Abstract
Bulk assimilation of small (millimeters to ∼1 km) fragments of crust—driven and (ultimately) masked by reactions during xenolith melting and magma crystallization—is an important mechanism for crust-mantle mixing. Xenoliths containing mica or amphibole undergo dehydration melting when incorporated into a host magma, yielding mainly plagioclase, pyroxene, Fe-Ti oxides, and hydrous melt. The xenolith is physically compromised by partial melting and begins to disintegrate; xenolithic melt and crystals are mixed into the host magma. Xenocrystic zircon is liberated at this stage. The cryptic character of assimilation is greatly enhanced in any hydrous magma by hydration crystallization reactions (the reverse of dehydration melting). All pyroxenes and oxides (phenocrysts, xenocrysts, or crystals having a hybrid signature) will be subject to these reactions, producing feldspars, amphiboles, and micas that incorporate material from several sources, a particularly effective mixing mechanism. Implicit in the model is a reduced energy penalty for bulk assimilation—much of the assimilant remains in solid form—compared to melt-assimilation models. A large role for bulk assimilation supports stoping as a credible mechanism for the ascent of magmas. While the assimilation of low-density crust and concomitant fractionation provide the isostatic impetus for ascent, the wholesale incorporation and processing of crustal rocks in the magma chamber helps create the room for ascent.
Fluid density control on vapor-liquid partitioning of metals in hydrothermal systems
Authors: Pokrovski Gleb S. , Roux Jacques , Harrichoury Jean-Claude 
Published: July 2019

Abstract
Hot aqueous fluids, both vapor and saline liquid, are primary transporting media for metals in hydrothermal-magmatic systems. Despite the growing geological evidence that the vapor phase, formed through boiling of magmatic ore-bearing fluids, can selectively concentrate and transport metals, the physical-chemical mechanisms that control the metal vapor-liquid fractionation remain poorly understood. We performed systematic experiments to investigate the metal vapor-liquid partitioning in model water-salt-gas systems H2O-NaCl-KCl-HCl at hydrothermal conditions. Measurements show that equilibrium vapor-liquid fractionation patterns of many metals are directly related to the densities of the coexisting vapor and liquid phases. Despite differences in the vapor-phase chemistry of various metals that form hydroxide, chloride, or sulfide gaseous molecules of contrasting volatile properties, water-solute interaction is a key factor that controls the metal transfer by vapor-like fluids in Earth's crust. These findings allow quantitative prediction of the vapor-liquid distribution patterns and vapor-phase metal transport in a wide range of conditions. Our density model accounts well for the vapor-brine distribution patterns of Na, Si, Fe, Zn, As, Sb, and Ag observed in fluid inclusions from magmatic-hydrothermal deposits. For Au and Cu, the partitioning in favor of the liquid phase, predicted in a sulfur-free system, contrasts with the copper and gold enrichment observed in natural vapor-like inclusions. The formation of stable complexes of Cu and Au with reduced sulfur may allow for their enhanced transport by sulfur-enriched magmatic-hydrothermal vapors.
Dining in the Pleistocene—Who's on the menu?
Authors: Kohn Matthew J. , McKay Moriah P. , Knight James L. 
Published: July 2019

Abstract
The Camelot local fauna, a new fossil locality in southeastern South Carolina, has yielded a spectacularly abundant and well-preserved late Irvingtonian (ca. 400 ka) megafauna, including saber-toothed cat (Smilodon fatalis), wolf (Canis armbrusteri), cheetah (Miracinonyx inexpectatus), “camels” (Hemiauchenia macrocephala and Paleolama mirifica), tapir (Tapirus veroensis), deer (Odocoileus virginianus), sloth (Megalonyx jeffersoni), and horse (Equus sp.). Of particular interest is the number of well-preserved fossil teeth and the ability to decipher paleoecologies and paleodiets, especially for carnivores, by using carbon isotope compositions (δ13C) of these teeth. P. mirifica, M. jeffersoni, O. virginianus, and T. veroensis have the lowest δ13C values (−16‰ to −13‰, Vienna Peedee belemnite standard); C. armbrusteri, S. fatalis, and H. macrocephala have intermediate values (−13‰ to −8‰); and Equus sp. has the highest values (−7‰ to −1‰). High (>−5‰) vs. low (≤−9‰) δ13C values for herbivores indicate local habitats dominated by warm-climate grasses vs. trees and shrubs. The high δ13C values for Equus sp. indicate the presence of grasslands, whereas the low δ13C values for the other herbivores generally indicate the presence of forests. Although few data are available for carnivores, moderate δ13C values for C. armbrusteri indicate that it preyed mainly upon forest herbivores. S. fatalis appears to have preferred marginal woodland-grassland areas.
A general method for morphologic dating of hillslopes
Authors: Nash David B. 
Published: July 2019

Abstract
Morphologic dating of hillslopes is the determination of the age of a hillslope by its morphology. Current methods match the observed morphology with the morphology predicted by the diffusion-equation model for hillslope evolution. The morphologic dating method presented here requires no specific model for evolution, but is only applicable to transport-limited hillslopes on which the downslope debris flux is some scale- and time-independent function of slope angle. If these conditions are met, changes in morphology with scale (e.g., height) for a set of hillslopes of a fixed age are identical to changes in morphology with time for a hillslope of a fixed scale. This fact provides the basis for a simple, generally applicable method for morphologically dating such hillslopes with any initial morphology. This new dating method may be applied to a wide variety of vegetated hillslopes in temperate humid regions and is an improvement over previous morphologic dating methods that relied on the diffusion-equation model.
Termination of a fossil continent-ocean fracture zone imaged with three-dimensional seismic data: The Chain Fracture Zone, eastern equatorial Atlantic
Authors: Davies Richard J. , MacLeod Christopher J. , Morgan Richard , Briggs Sepribo E. 
Published: July 2019

Abstract
We describe the first three-dimensional imaging of the termination of a continent-ocean fracture zone (COFZ), the Chain Fracture Zone, located offshore of the Niger Delta. The COFZ marks the abrupt transition between extended continental crust, comprising multiple half-graben, and oceanic crust that has a pervasive seafloor-spreading fabric. It preserves a history of continent-continent shearing followed by oceanic crust accretion and continent-ocean shearing during the inception of Atlantic rifting. The termination is marked by steeply dipping faults with sigmoidal planform and thrusts that probably formed as a result of continent-continent or continent-ocean shearing. These are crosscut by the seafloor-spreading fabric that formed during the subsequent phase of oceanic crust accretion. The accreted oceanic crust is cut by listric and planar faults that curve in the direction of the COFZ, where they terminate. The transition from continental to oceanic crust across the COFZ is sharp and resolvable to ∼100–200 m. Complexes of lava flows emanate from volcanoes along the COFZ, bifurcating and trifurcating down the volcano flanks. The volcanoes are 2–5.5 km wide and 1.4 km in height relative to adjacent oceanic crust and were injected at the COFZ, probably as the spreading center migrated along it.
Resolving the Richat enigma: Doming and hydrothermal karstification above an alkaline complex
Authors: Matton Guillaume , Jébrak Michel , Lee James K.W. 
Published: July 2019

Abstract
The Richat structure (Sahara, Mauritania) appears as a large dome at least 40 km in diameter within a Late Proterozoic to Ordovician sequence. Erosion has created circular cuestas represented by three nested rings dipping outward from the structure. The center of the structure consists of a limestone-dolomite shelf that encloses a kilometer-scale siliceous breccia and is intruded by basaltic ring dikes, kimberlitic intrusions, and alkaline volcanic rocks. Several hypotheses have been presented to explain the spectacular Richat structure and breccia, but their origin remains enigmatic. The breccia body is lenticular in shape and irregularly thins at its extremities to only a few meters. The breccia was created during karst dissolution and collapse. Internal sediments fill the centimeter- to meter-scale cavities. Alkaline enrichment and the presence of Cretaceous automorphous neoformed K-feldspar demonstrate the hydrothermal origin of these internal sediments and their contemporaneity with magmatism. A model is proposed in which doming and the production of hydrothermal fluids were instrumental in creating a favorable setting for dissolution. The circular Richat structure and its breccia core thus represent the superficial expression of a Cretaceous alkaline complex with an exceptionally well preserved hydrothermal karst infilling at its summit.
What drives orogeny in the Andes?
Authors: Sobolev S.V. , Babeyko A.Y. 
Published: July 2019

Abstract
The Andes, the world's second highest orogenic belt, were generated by the Cenozoic tectonic shortening of the South American plate margin overriding the subducting Nazca plate. We use a coupled thermomechanical numerical modeling technique to identify factors controlling the intensity of the tectonic shortening. From the modeling, we infer that the most important factor was accelerated westward drift of the South American plate; changes in the subduction rate were less important. Other important factors are crustal structure of the overriding plate and shear coupling at the plates' interface. The model with a thick (40–45 km at 30 Ma) South American crust and relatively high friction coefficient (0.05) at the Nazca–South American interface generates >300 km of tectonic shortening during 30–35 m.y. and replicates the crustal structure and evolution of the high central Andes. The model with an initially thinner (<40 km) continental crust and lower friction coefficient (<0.015) results in <40 km of South American plate shortening, replicating the situation in the southern Andes. Our modeling also demonstrates the important role of the processes leading to mechanical weakening of the overriding plate during tectonic shortening, such as lithospheric delamination, triggered by the gabbro-eclogite transformation in the thickened continental lower crust, and mechanical failure of the sediment cover at the shield margin.
Selective calcareous nannoplankton survivorship at the Cretaceous-Tertiary boundary
Authors: Bown Paul 
Published: July 2019

AbstractCalcareous nannoplankton underwent devastating diversity loss at the Cretaceous- Tertiary boundary (65.5 Ma), but recovered rapidly in the early Paleocene from a small number of survivor species. An understanding of this survivorship has been hampered by uncertainties introduced by reworking and mixing, but new high-resolution assemblage data from the northwest Pacific (Shatsky Rise, Ocean Drilling Program Site 1210) allow the unequivocal identification of 10 survivors. Evidence of shared adaptive strategies among these species provides the first indication that the extinctions were selective, with survival limited to a few neritic and/or opportunistic species, probably facilitated by hardiness and/or life-cycle escape strategies.
Time scale of magma differentiation in arcs from protactinium-radium isotopic data
Authors: Asmerom Yemane , DuFrane S. Andrew , Mukasa Samuel B. , Cheng Hai , Edwards R. Lawrence 
Published: July 2019

Abstract
Absolute chronology of magma differentiation processes has been a long-desired goal, given its importance in understanding magma chamber dynamics and its connection to a fundamental understanding of the style and frequency of volcanic eruptions. Broad estimates of the duration of magma differentiation and overall crustal residence times have been made based on a variety of indirect approaches, such as physical models of magma chamber cooling, rates of crystal growth and settling, and long-lived radiogenic isotopes. In contrast, combined 231Pa-235U data may provide a robust measure of the time scale of magma differentiation. Based on 231Pa-235U, 230Th-238U and 226Ra-230Th data from Taal volcano, Luzon Arc, Philippine Archipelago, we show that 231Pa-235U data may provide a robust direct measure of the time scale of magma differentiation. A closed-system magma fractionation model gives a 231Pa-235U differentiation time scale in the range of 30 k.y., while the 226Ra-230Th time scale is considerably younger. The time scales are reconciled if we consider either fluid-mixing or magma-mixing models. The fluid-mixing model gives a time scale of differentiation similar to the 231Pa-235U closed-system time scale and is supported by the 230Th-238U data. The magma-mixing model gives a considerably longer time, in the range of 55 k.y. The combined observations support the robustness of the 231Pa-235U chronology, indicating a differentiation time scale in the range of 30 k.y., although this time scale for other volcanoes may vary depending on size and thermal state of the magma chamber. The 226Ra-230Th closed-system model ages, which yield much younger estimates for magma differentiation, are not likely to reflect time scales of magma differentiation.
Oxford Video Informed Consent Tool (OxVIC): a pilot study of informed video consent in spinal surgery and preoperative patient satisfaction
Authors: Mawhinney Gerard , Thakar Chrishan , Williamson Victoria , Rothenfluh Dominique A , Reynolds Jeremy 
Published: July 2019

ObjectivesThe British Association of Spinal Surgeons recently called for updates in consenting practice. This study investigates the utility and acceptability of a personalised video consent tool to enhance patient satisfaction in the preoperative consent giving process.DesignA single-centre, prospective pilot study using questionnaires to assess acceptability of video consent and its impacts on preoperative patient satisfaction.SettingA single National Health Service centre with individuals undergoing surgery at a regional spinal centre in the UK.Outcome measureAs part of preoperative planning, study participants completed a self-administered questionnaire (CSQ-8), which measured their satisfaction with the use of a video consent tool as an adjunct to traditional consenting methods.Participants20 participants with a mean age of 56 years (SD=16.26) undergoing spinal surgery.ResultsMean patient satisfaction (CSQ-8) score was 30.2/32. Median number of video views were 2–3 times. Eighty-five per cent of patients watched the video with family and friends. Eighty per cent of participants reported that the video consent tool helped to their address preoperative concerns. All participants stated they would use the video consent service again. All would recommend the service to others requiring surgery. Implementing the video consent tool did not endure any significant time or costs.ConclusionsIntroduction of a video consent tool was found to be a positive adjunct to traditional consenting methods. Patient–clinician consent dialogue can now be documented. A randomised controlled study to further evaluate the effects of video consent on patients’ retention of information, preoperative and postoperative anxiety, patient reported outcome measures as well as length of stay may be beneficial.
Associations of school tobacco policies and legislation with youth smoking: a cross-sectional study of Danish vocational high schools
Authors: Andersen Susan , Pisinger Veronica , Rod Morten Hulvej , Tolstrup Janne 
Published: July 2019

BackgroundIn vocational high schools, the prevalence of smoking is high (nearly 40% daily smoking in Danish vocational high schools). Schools are increasingly adopting school tobacco policies (STPs) and a national law on smoke-free school grounds has been implemented. Our objective was to explore the extent of STPs in vocational schools and examine the association of STPs and smoke-free school grounds legislation with student smoking.MethodsWe used data from the cross-sectional Danish National Youth Study 2014, including 5013 vocational high school students (76% male) at 40 campuses. Implementation of STPs was measured by questionnaires to principals and field observations of smoking practices were conducted. Logistic regression models assessed whether STP characteristics were associated with students’ current smoking (ie, daily and occasional) compared with non-current smoking. Negative binominal regression models assessed cigarettes per day among daily smokers.ResultsSchools covered by the national law on smoke-free school ground had more comprehensive STPs than schools not covered by the law. Student smoking was observed on 78% of campuses, with less visibility of smoking in schools covered by the national law (69% vs 83%). Current smoking was lower for students attending a school covered by the national law (OR=0.86, 95% CI 0.75 to 0.97). Students who attended schools that allowed teacher–student smoking were more likely to smoke (OR=1.13, 95% CI 1.01 to 1.27).ConclusionsA law on smoke-free school grounds was associated with less current smoking in vocational high schools, while school norms that are supportive of teacher-student smoking were associated with greater odds of current smoking. Visibility of student smoking was less prevalent at schools covered by the law on smoke-free school grounds; nevertheless, the visibility of smoking was high. Better enforcement or an extension of the current law on smoke-free school grounds is recommended.
Prevalence and determinants of hyperglycaemia among adults in Bangladesh: results from a population-based national survey
Authors: Islam Jessica Yasmine , Zaman Mohammad Mostafa , Bhuiyan Mahfuz Rahman , Haq Syed Atiqul , Ahmed Shamim , Al-Qadir Ahmad Zahid 
Published: July 2019

ObjectivesWith the increasing burden of non-communicable diseases in low-income and middle-income countries, biological risk factors, such as hyperglycaemia, are a major public health concern in Bangladesh. Hyperglycaemia is an excess of glucose in the bloodstream and is often associated with type 2 diabetes mellitus. Nationally representative data of hyperglycaemia prevalence starting from age ≥18 years are currently unavailable for Bangladeshi adults. The objective of this study was to assess the prevalence and determinants of hyperglycaemia among adults in Bangladesh aged ≥18 years.Study designCross-sectional, population-based study.Setting and participantsData for this analysis were collected in November to December 2015, from a population-based nationally representative sample of 1843 adults, aged ≥18 years, from both urban and rural areas of Bangladesh. Demographic information, capillary blood glucose, blood pressure, height, weight, waist circumference and treatment history were recorded.Primary outcome measuresHyperglycaemia was defined as a random capillary blood glucose level of ≥11.1 mmol/L (ie, in the diabetic range) or currently taking medication to control type 2 diabetes, based on self-report.ResultsOverall, the prevalence of hyperglycaemia was 5.5% (95% CI 4.5% to 6.6%) and was significantly higher among urban (9.8%, 95% CI 7.7% to 12.2%) than rural residents (2.8%, 95% CI 1.9% to 3.9%). The age-standardised prevalence of hyperglycaemia was 5.6% (95% CI 4.6% to 6.8%). Among both urban and rural residents, the associated determinants of hyperglycaemia included hypertension and abdominal obesity. About 5% of the total population self-reported have been previously diagnosed with type 2 diabetes; among these adults, over 25% were not taking medications to control their diabetes.ConclusionsOur study found that about 1 in 20 Bangladeshi adults aged ≥18 years have hyperglycaemia. To control and prevent the development of type 2 diabetes, data from this study can be used to inform public health programming and provide descriptive information on surveillance of progress towards controlling diabetes in Bangladesh.
Experiences of how services supporting women with perinatal mental health difficulties work with their families: a qualitative study in England
Authors: Lever Taylor Billie , Billings Jo , Morant Nicola , Bick Debra , Johnson Sonia 
Published: July 2019

ObjectivesPartners and wider family members play a vital role in relation to women’s perinatal mental health. Clinical guidelines in the UK and internationally recommend that services supporting women with perinatal mental health difficulties involve and support their families too. However, little is known about family members’ needs and experiences, or whether they feel included by mental health services. This study set out to explore this.MethodsThis research formed part of a wider study exploring experiences of perinatal mental health care in England. The broader study included semi-structured interviews with 52 women across England who received treatment for a perinatal mental health difficulty, and 32 family members identified by the women as offering them some support. Data from these 84 interviews relating to how services work with partners and families were extracted and analysed thematically.ResultsAnalysis identified three overarching themes: (1) the centrality of women’s families to their perinatal mental health/access to support, (2) experiences of partners and families being excluded by services and (3) ambivalence among women and their families about increasing family involvement/support. We found that partners and families appear to have an important influence on women’s perinatal mental health, access to care and interactions with services, but that services tend to focus on individual women (and babies) with little regard for their wider family context. The complexity of involving and supporting partners and families, coupled with anxiety about this among women and their families, reinforces the tendency to marginalise them.ConclusionInvolving women’s families and providing the support they need is challenging, but important. Experiences of women and their families of services treating perinatal mental health difficulties suggests greater focus is needed on overcoming barriers to family inclusion and on challenging underlying gender roles and expectations, rather than allowing these to shape and guide practice.