bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Helium Elemental and Isotopic Compositions of the Earth's Core Based on Ab Initio Simulations
Authors: Yuan Liang , Steinle‐Neumann Gerd 
Published: October 2021

AbstractWe use density functional theory‐based molecular dynamics simulations to predict the partitioning behavior of helium (He) between coexisting metal and silicate melts at conditions of the magma ocean and the current core–mantle boundary. Helium strongly favors silicate over metal at low pressures and temperatures (10 GPa and 3,000 K) but it becomes approximately two orders of magnitude more compatible with metal at greater pressures and temperatures (50 GPa and 4,000 K) expected in a deep magma ocean. We further examine He partitioning behavior for varying metal compositions (pure Fe, Fe‐S, and Fe‐O alloys) and find that oxygen enhances He incorporation into the core by one to two orders of magnitude. The He elemental and isotopic compositions of the Earth's core are estimated to be ∼4.2 ng/g and ∼140 atmospheric 3He/4He ratio assuming the core containing some amounts of oxygen as required to explain the core density deficit. Our results suggest that the core may play a key role as a reservoir for the He signature recorded in ocean island basalts with distinctively high 3He/4He ratios.
The Morphology of Simulated Trade‐Wind Convection and Cold Pools Under Wind Shear
Authors: Helfer K. C. , Nuijens L. 
Published: October 2021

AbstractA growing body of literature investigates convective organization, but few studies to date have sought to investigate how wind shear plays a role in the spatial organization of shallow (trade‐wind) convection. The present study hence investigates the morphology of precipitating marine cumulus convection using large‐eddy‐simulation experiments with zonal forward and backward shear and without shear. One set of simulations includes evaporation of precipitation, promoting cold‐pool development, and another set inhibits the evaporation of precipitation and thus cold‐pool formation. Without (or with only weak) subcloud‐layer shear, conditions are unfavorable for convective deepening, as clouds remain stationary relative to their subcloud‐layer roots so that precipitative downdrafts interfere with emerging updrafts. Under subcloud‐layer forward shear (FS), where the wind strengthens with height (a condition that is commonly found in the trades), clouds move at greater speed than their roots and precipitation falls downwind away from emerging updrafts. FS in the subcloud layer appears to promote the development of stronger subcloud circulations, with greater divergence in the cold‐pool area downwind of the original cell and larger convergence and stronger uplift at the gust front boundary. As clouds shear forward, a larger fraction of precipitation falls outside of clouds, leading to more moistening within the cold pool (gust front).
Divergent Patterns and Spatial Heterogeneity of Soil Nutrients in a Complex and Dynamic Savanna Landscape
Authors: Zhou Yong , Taylor Robert J. , Boutton Thomas W. 
Published: October 2021

AbstractMany grassy ecosystems around the world are experiencing woody encroachment. These woody encroachers often cause nutrient enrichment in the plant‐soil environment, potentially facilitating their growth and reproduction. However, studies of encroachment effects on nutrient distributions have been confined to a few major elements (e.g.,N, and P) and limited in spatial extent. We analyzed 19 elements in dominant plants and in georeferenced soils across a subtropical savanna landscape experiencing woody encroachment to quantify their spatial patterns and elucidate drivers responsible for these patterns. We found divergent patterns of spatial heterogeneity of these elements in surface soils across this complex landscape. Nutrient accumulation and redistribution underneath woody canopies occurred in a subset of elements (i.e., N, P, S, Ca, Cu, and Sr). Though some of these elements are not necessarily growth‐limiting, they do occur in higher concentrations in woody compared to herbaceous plants. Distributions of the other elements were closely related to spatial variation in soil pH, clay content, and slope rather than to woody encroachment. Our nuanced spatial sampling approach and analysis reveal significant variation in nutrient distributions in response to woody encroachment, and illustrate the role of landscape patterns in mediating ecosystem processes. These changes in the concentrations and distributions of key essential nutrients broaden our understanding of the biogeochemical consequences of woody encroachment, and provide new insights regarding the significance of long‐term vegetation dynamics in dryland ecosystems.
Root Exudates Alters Nutrient Transport in Soil
Authors: Paporisch Amit , Bavli Harel , Strickman Rachel J. , Neumann Rebecca B. , Schwartz Nimrod 
Published: October 2021

AbstractRoot exudates alter the rhizosphere's physical properties, but the impact that these changes have on solute transport is unknown. In this study, we tested the effects of chia mucilage and wheat root exudates (WREs) on the transport of iodide and potassium in saturated or unsaturated soil. Saturated solute breakthrough experiments, conducted in loamy sand soil or coarser textured quartz sand, revealed that increasing the exudate concentration in soil resulted in non‐equilibrium solute transport. This behavior was demonstrated by an initial solute breakthrough after fewer pore volumes (PVs) and the arrival of the peak solute concentration after greater PVs in soil mixed with exudates compared to soil without exudates. These patterns were more pronounced for the coarser textured quartz sand than for the loamy sand soil, and in soil mixed with mucilage than in soil mixed WREs. Parameter fits to these breakthrough curves with a mobile‐immobile transport model indicated the fraction of immobile water increased as the concentration of exudates increased. For example, in quartz sand the estimated immobile fraction increased from 0 without exudates to 0.75 at a mucilage concentration of 0.2%. The solutes' breakthrough under unsaturated conditions was also altered by the exudates, demonstrated by a smaller volume of water extracted from soil mixed with exudates, compared to soil without exudates, before the arrival of the peak solute concentration. The results indicate that exudates alter the rhizosphere's transport properties; we hypothesize that this is due to exudates creating low‐conducting flow paths that result in a physical non‐equilibrium solute transport.
Dynamic Adaptation of Water Resources Systems Under Uncertainty by Learning Policy Structure and Indicators
Authors: Cohen Jonathan S. , Herman Jonathan D. 
Published: October 2021

AbstractThe challenge of adapting water resources systems to uncertain hydroclimatic and socioeconomic conditions warrants a dynamic planning approach. Recent studies have designed policies with structures linking infrastructure and management actions to threshold values of indicator variables observed over time. Typically, one or more of these components are held fixed while the others are optimized, constraining the flexibility of policy generation. Here we develop a framework to address this challenge by designing and testing dynamic adaptation policies that combine indicators, actions, and thresholds in a flexible structure. The approach is demonstrated for a case study of northern California, where a mix of infrastructure, management, and operational adaptations are considered over time in response to an ensemble of nonstationary hydrology and water demands. We first identify a subset of non‐dominated policies that are robust to held‐out scenarios, and then analyze their most common actions and indicators compared to non‐robust policies. Results show that the robust policies are not differentiated by the actions they select, but show substantial differences in their indicator variables, which can be interpreted in the context of physical hydrologic trends. In particular, the most frequent statistical transformations of indicator variables highlight the balance between adapting quickly versus correctly. Additionally, we determine the indicators most frequently associated with each action, as well as the distribution of action timing across scenarios. This study presents a new and transferable problem framing for adaptation under uncertainty in which indicator variables, actions, and policy structure are identified simultaneously during the optimization.
Embodied intelligence via learning and evolution
Authors: Gupta Agrim , Savarese Silvio , Ganguli Surya , Fei-Fei Li 
Published: October 2021

AbstractThe intertwined processes of learning and evolution in complex environmental niches have resulted in a remarkable diversity of morphological forms. Moreover, many aspects of animal intelligence are deeply embodied in these evolved morphologies. However, the principles governing relations between environmental complexity, evolved morphology, and the learnability of intelligent control, remain elusive, because performing large-scale in silico experiments on evolution and learning is challenging. Here, we introduce Deep Evolutionary Reinforcement Learning (DERL): a computational framework which can evolve diverse agent morphologies to learn challenging locomotion and manipulation tasks in complex environments. Leveraging DERL we demonstrate several relations between environmental complexity, morphological intelligence and the learnability of control. First, environmental complexity fosters the evolution of morphological intelligence as quantified by the ability of a morphology to facilitate the learning of novel tasks. Second, we demonstrate a morphological Baldwin effect i.e., in our simulations evolution rapidly selects morphologies that learn faster, thereby enabling behaviors learned late in the lifetime of early ancestors to be expressed early in the descendants lifetime. Third, we suggest a mechanistic basis for the above relationships through the evolution of morphologies that are more physically stable and energy efficient, and can therefore facilitate learning and control.
Realization of nearly dispersionless bands with strong orbital anisotropy from destructive interference in twisted bilayer MoS2
Authors: Xian Lede , Claassen Martin , Kiese Dominik , Scherer Michael M. , Trebst Simon , Kennes Dante M. , Rubio Angel 
Published: October 2021

AbstractRecently, the twist angle between adjacent sheets of stacked van der Waals materials emerged as a new knob to engineer correlated states of matter in two-dimensional heterostructures in a controlled manner, giving rise to emergent phenomena such as superconductivity or correlated insulating states. Here, we use an ab initio based approach to characterize the electronic properties of twisted bilayer MoS2. We report that, in marked contrast to twisted bilayer graphene, slightly hole-doped MoS2 realizes a strongly asymmetric px-py Hubbard model on the honeycomb lattice, with two almost entirely dispersionless bands emerging due to destructive interference. The origin of these dispersionless bands, is similar to that of the flat bands in the prototypical Lieb or Kagome lattices and co-exists with the general band flattening at small twist angle due to the moiré interference. We study the collective behavior of twisted bilayer MoS2 in the presence of interactions, and characterize an array of different magnetic and orbitally-ordered correlated phases, which may be susceptible to quantum fluctuations giving rise to exotic, purely quantum, states of matter.
Magnetopause ripples going against the flow form azimuthally stationary surface waves
Authors: Archer M. O. , Hartinger M. D. , Plaschke F. , Southwood D. J. , Rastaetter L. 
Published: October 2021

AbstractSurface waves process the turbulent disturbances which drive dynamics in many space, astrophysical and laboratory plasma systems, with the outer boundary of Earth’s magnetosphere, the magnetopause, providing an accessible environment to study them. Like waves on water, magnetopause surface waves are thought to travel in the direction of the driving solar wind, hence a paradigm in global magnetospheric dynamics of tailward propagation has been well-established. Here we show through multi-spacecraft observations, global simulations, and analytic theory that the lowest-frequency impulsively-excited magnetopause surface waves, with standing structure along the terrestrial magnetic field, propagate against the flow outside the boundary. Across a wide local time range (09–15h) the waves’ Poynting flux exactly balances the flow’s advective effect, leading to no net energy flux and thus stationary structure across the field also. Further down the equatorial flanks, however, advection dominates hence the waves travel downtail, seeding fluctuations at the resonant frequency which subsequently grow in amplitude via the Kelvin-Helmholtz instability and couple to magnetospheric body waves. This global response, contrary to the accepted paradigm, has implications on radiation belt, ionospheric, and auroral dynamics and potential applications to other dynamical systems.
SARS-CoV-2 antibody seroprevalence and associated risk factors in an urban district in Cameroon
Authors: Nwosu Kene , Fokam Joseph , Wanda Franck , Mama Lucien , Orel Erol , Ray Nicolas , Meke Jeanine , Tassegning Armel , Takou Desire , Mimbe Eric , Stoll Beat , Guillebert Josselin , Comte Eric , Keiser Olivia , Ciaffi Laura 
Published: October 2021

AbstractThe extent of SARS-CoV-2 circulation in many African countries remains unclear, underlining the need for antibody sero-surveys to assess the cumulative attack rate. Here, we present the results of a cross-sectional sero-survey of a random sample of residents of a health district in Yaounde, Cameroon, conducted from October 14 to November 26, 2020. Among the 971 participants, the test-adjusted seroprevalence of anti-SARS-CoV-2 IgG antibodies was 29·2% (95% CI 24·3–34·1). This is about 322 times greater than the 0.09% nationwide attack rate implied by COVID-19 case counts at the time. Men, obese individuals and those living in large households were significantly more likely to be seropositive, and the majority (64·2% [58·7–69·4]) of seropositive individuals reported no symptoms. Despite the high seroprevalence, most of the population had not been infected with SARS-CoV-2, highlighting the importance of continued measures to control viral spread and quick vaccine deployment to protect the vulnerable.
Noninvasive spinal stimulation safely enables upright posture in children with spinal cord injury
Authors: Keller Anastasia , Singh Goutam , Sommerfeld Joel H. , King Molly , Parikh Parth , Ugiliweneza Beatrice , D’Amico Jessica , Gerasimenko Yury , Behrman Andrea L. 
Published: October 2021

AbstractIn children with spinal cord injury (SCI), scoliosis due to trunk muscle paralysis frequently requires surgical treatment. Transcutaneous spinal stimulation enables trunk stability in adults with SCI and may pose a non-invasive preventative therapeutic alternative. This non-randomized, non-blinded pilot clinical trial (NCT03975634) determined the safety and efficacy of transcutaneous spinal stimulation to enable upright sitting posture in 8 children with trunk control impairment due to acquired SCI using within-subject repeated measures study design. Primary safety and efficacy outcomes (pain, hemodynamics stability, skin irritation, trunk kinematics) and secondary outcomes (center of pressure displacement, compliance rate) were assessed within the pre-specified endpoints. One participant did not complete the study due to pain with stimulation on the first day. One episode of autonomic dysreflexia during stimulation was recorded. Following hemodynamic normalization, the participant completed the study. Overall, spinal stimulation was well-tolerated and enabled upright sitting posture in 7 out of the 8 participants.
DUBStepR is a scalable correlation-based feature selection method for accurately clustering single-cell data
Authors: Ranjan Bobby , Sun Wenjie , Park Jinyu , Mishra Kunal , Schmidt Florian , Xie Ronald , Alipour Fatemeh , Singhal Vipul , Joanito Ignasius , Honardoost Mohammad Amin , Yong Jacy Mei Yun , Koh Ee Tzun , Leong Khai Pang , Rayan Nirmala Arul , Lim Michelle Gek Liang , Prabhakar Shyam 
Published: October 2021

AbstractFeature selection (marker gene selection) is widely believed to improve clustering accuracy, and is thus a key component of single cell clustering pipelines. Existing feature selection methods perform inconsistently across datasets, occasionally even resulting in poorer clustering accuracy than without feature selection. Moreover, existing methods ignore information contained in gene-gene correlations. Here, we introduce DUBStepR (Determining theUnderlyingBasis usingStepwiseRegression), a feature selection algorithm that leverages gene-gene correlations with a novel measure of inhomogeneity in feature space, termed the Density Index (DI). Despite selecting a relatively small number of genes, DUBStepR substantially outperformed existing single-cell feature selection methods across diverse clustering benchmarks. Additionally, DUBStepR was the only method to robustly deconvolve T and NK heterogeneity by identifying disease-associated common and rare cell types and subtypes in PBMCs from rheumatoid arthritis patients. DUBStepR is scalable to over a million cells, and can be straightforwardly applied to other data types such as single-cell ATAC-seq. We propose DUBStepR as a general-purpose feature selection solution for accurately clustering single-cell data.
Whole chromosome loss and genomic instability in mouse embryos after CRISPR-Cas9 genome editing
Authors: Papathanasiou Stamatis , Markoulaki Styliani , Blaine Logan J. , Leibowitz Mitchell L. , Zhang Cheng-Zhong , Jaenisch Rudolf , Pellman David 
Published: October 2021

AbstractKaryotype alterations have emerged as on-target complications from CRISPR-Cas9 genome editing. However, the events that lead to these karyotypic changes in embryos after Cas9-treatment remain unknown. Here, using imaging and single-cell genome sequencing of 8-cell stage embryos, we track both spontaneous and Cas9-induced karyotype aberrations through the first three divisions of embryonic development. We observe the generation of abnormal structures of the nucleus that arise as a consequence of errors in mitosis, including micronuclei and chromosome bridges, and determine their contribution to common karyotype aberrations including whole chromosome loss that has been recently reported after editing in embryos. Together, these data demonstrate that Cas9-mediated germline genome editing can lead to unwanted on-target side effects, including major chromosome structural alterations that can be propagated over several divisions of embryonic development.
A bioinspired scaffold for rapid oxygenation of cell encapsulation systems
Authors: Wang Long-Hai , Ernst Alexander Ulrich , An Duo , Datta Ashim Kumar , Epel Boris , Kotecha Mrignayani , Ma Minglin 
Published: October 2021

AbstractInadequate oxygenation is a major challenge in cell encapsulation, a therapy which holds potential to treat many diseases including type I diabetes. In such systems, cellular oxygen (O2) delivery is limited to slow passive diffusion from transplantation sites through the poorly O2-soluble encapsulating matrix, usually a hydrogel. This constrains the maximum permitted distance between the encapsulated cells and host site to within a few hundred micrometers to ensure cellular function. Inspired by the natural gas-phase tracheal O2 delivery system of insects, we present herein the design of a biomimetic scaffold featuring internal continuous air channels endowed with 10,000-fold higher O2 diffusivity than hydrogels. We incorporate the scaffold into a bulk hydrogel containing cells, which facilitates rapid O2 transport through the whole system to cells several millimeters away from the device-host boundary. A computational model, validated by in vitro analysis, predicts that cells and islets maintain high viability even in a thick (6.6 mm) device. Finally, the therapeutic potential of the device is demonstrated through the correction of diabetes in immunocompetent mice using rat islets for over 6 months.
Multi-targeted 1H/19F MRI unmasks specific danger patterns for emerging cardiovascular disorders
Authors: Flögel Ulrich , Temme Sebastian , Jacoby Christoph , Oerther Thomas , Keul Petra , Flocke Vera , Wang Xiaowei , Bönner Florian , Nienhaus Fabian , Peter Karlheinz , Schrader Jürgen , Grandoch Maria , Kelm Malte , Levkau Bodo 
Published: October 2021

AbstractPrediction of the transition from stable to acute coronary syndromes driven by vascular inflammation, thrombosis with subsequent microembolization, and vessel occlusion leading to irreversible myocardial damage is still an unsolved problem. Here, we introduce a multi-targeted and multi-color nanotracer platform technology that simultaneously visualizes evolving danger patterns in the development of progressive coronary inflammation and atherothrombosis prior to spontaneous myocardial infarction in mice. Individual ligand-equipped perfluorocarbon nanoemulsions are used as targeting agents and are differentiated by their specific spectral signatures via implementation of multi chemical shift selective19F MRI. Thereby, we are able to identify areas at high risk of and predictive for consecutive development of myocardial infarction, at a time when no conventional parameter indicates any imminent danger. The principle of this multi-targeted approach can easily be adapted to monitor also a variety of other disease entities and constitutes a technology with disease-predictive potential.
CD127+ CD94+ innate lymphoid cells expressing granulysin and perforin are expanded in patients with Crohn’s disease
Authors: Krabbendam L. , Heesters B. A. , Kradolfer C. M. A. , Haverkate N. J. E. , Becker M. A. J. , Buskens C. J. , Bemelman W. A. , Bernink J. H. , Spits H. 
Published: October 2021

AbstractPhenotypic definition of helper ILC1 and NK cells is problematic due to overlapping markers. Recently we showed the identification of cytotoxic ILC3s characterized by expression of CD94. Here we analyse CD127+ ILCs and NK cells in intestinal lamina propria from healthy donors and Crohn’s disease patients and identify two populations of CD127+CD94+ ILCs, designated population A and B, that can be distinguished on the expression of CD117, CD18 and cytotoxic molecules. Population B expresses granulysin, a cytotoxic molecule linked to bacterial lysis and/or chemotaxis of monocytes. Granulysin protein is secreted by population B cells upon stimulation with IL-15. Activation of population B in the presence of TGF-β strongly reduces the expression of cytotoxic effector molecules of population B. Strikingly, samples from individuals that suffer from active Crohn’s disease display enhanced frequencies of granulysin-expressing effector CD127+CD94+ ILCs in comparison to controls. Thus this study identifies group 1 ILC populations which accumulate in inflamed intestinal tissue of Crohn’s disease patients and may play a role in the pathology of the disease.