bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mercury in Active‐Layer Tundra Soils of Alaska: Concentrations, Pools, Origins, and Spatial Distribution
Authors: Olson C. , Jiskra M. , Biester H. , Chow J. , Obrist D. 
Published: June 2018

AbstractTundra soils serve as major sources of mercury (Hg) input to the Arctic Ocean via river runoff and coastal erosion; yet little information is available on tundra soil Hg concentrations, pool sizes, origins, and dynamics. We present a detailed investigation of Hg in the active layer (upper ~100 cm subject to seasonal thaw) of tundra soils across 11 sites in Alaska. Soil Hg concentrations in organic horizons (151 ± 7 μg/kg) were in the upper range of temperate soil organic horizons, and concentrations in mineral horizons (98 ± 6 μg/kg) were much higher than in temperate soils. Soil Hg concentrations declined from inland to coastal sites, in contrast to a hypothesized northward increase expected because of proximity to coastal atmospheric mercury depletion events. Principle component analyses and elemental ratios results show that exogenic sources dominated over geogenic sources—in A‐horizons (66 ± 4%) and mineral B‐horizons (51 ± 1%). 14C age‐dating suggested recent origins of Hg in surface soils but showed that mineral soils (more than 7,300 years old) must have accumulated atmospheric inputs across millennia leading to high soil concentrations and pools. We estimated a total Northern Hemisphere active‐layer tundra soil Hg pool of 184 Gg (range of 136 to 274 Gg), suggesting a globally important Hg storage pool. Tundra soils are subject to seasonal thaw and freeze dynamics, thereby providing large inputs to rivers, lakes, and the Arctic Ocean. Understanding processes that mobilize Hg from tundra soils will be critical to understanding future Arctic wildlife and human Hg exposures.
Concomitant Double Ion and Electron Populations in the Earth's Magnetopause Boundary Layers From Double Reconnection With Lobe and Closed Field Lines
Authors: Lavraud Benoit , Jacquey Christian , Achilli Timothée , Fuselier Stephen A. , Grigorenko Elena , Phan Tai D. , Øieroset Marit , McFadden James , Angelopoulos Vassilis 
Published: June 2018

AbstractWhile double ion populations, with a cold population originating from the solar wind and a hotter one from the magnetosphere, are frequently observed in the low‐latitude boundary layers at the Earth's magnetopause, similar double electron populations are observed less often. A preliminary study of magnetopause crossings characteristics was used to determine the typical locations and energy spectra of ion and electron populations near the magnetopause. Then, we set up an automated detection algorithm for identifying regions with concomitant double populations in both ion and electron energy spectra. The statistical study was carried out on 7 years of Time History of Events and Macroscale Interactions during Substorms particle data, to determine the interplanetary magnetic field conditions in the upstream solar wind for these double populations. The results suggest that such concomitant ion and electron double population boundary layers form preferentially in the subsolar region and under northward interplanetary magnetic field but with a significant BY component. We interpret this finding as the result of reconnection of the same magnetosheath field line in both hemispheres with at least one end reconnecting in its hemisphere at lower latitude with a closed magnetospheric field line that already contains a hot electron source.
Boundary Layer Diabatic Processes, the Virtual Effect, and Convective Self‐Aggregation
Authors: Yang Da 
Published: June 2018

AbstractThe atmosphere can self‐organize into long‐lasting large‐scale overturning circulations over an ocean surface with uniform temperature. This phenomenon is referred to as convective self‐aggregation and has been argued to be important for tropical weather and climate systems. Here we present a boundary layer centric framework based on the available potential energy budget of convective self‐aggregation. We show that boundary layer diabatic processes dominate the available potential energy production and are, therefore, essential to convective self‐aggregation. We further show that the enhanced virtual effect of water vapor can lead to convective self‐aggregation.
A TKE‐Based Framework for Studying Disturbed Atmospheric Surface Layer Flows and Application to Vertical Velocity Variance Over Canopies
Authors: Chamecki Marcelo , Dias Nelson L. , Freire Livia S. 
Published: June 2018

AbstractWe propose an approach to study disturbed surface layer flows based on a simplified form of the turbulent kinetic energy (TKE) budget equation (the reduced TKE budget), which can be represented by a two‐dimensional phase space. The phase space provides a way to quantify relative contributions of shear and buoyancy production/destruction of TKE, as well as the local imbalance between local production and dissipation. In this framework, Monin‐Obukhov Similarity Theory represents one possible approach to reduce the dimensionality of the phase space. We apply this framework to study the vertical velocity variance in the canonical surface layer and in the canopy roughness sublayer above the Amazon forest. Results reveal interesting insight into the behavior of the vertical velocity variance over forests, linking its magnitude to the imbalance between local production and dissipation of TKE.
Enhancing the Predictability of Seasonal Streamflow With a Statistical‐Dynamical Approach
Authors: Slater Louise J. , Villarini Gabriele 
Published: June 2018

AbstractSeasonal streamflow forecasts facilitate water allocation, reservoir operation, flood risk management, and crop forecasting. They are generally computed by forcing hydrological models with outputs from general circulation models (GCMs) or using large‐scale climate indices as predictors in statistical models. In contrast, hybrid statistical‐dynamical forecasts (combining statistical methods with dynamical climate predictions) are still uncommon, and their skill is largely unknown. Here we conduct systematic forecasting of seasonal streamflow using eight GCMs from the North American Multi‐Model Ensemble, 0.5–9.5 months ahead, at 290 stream gauges in the U.S. Midwest. Probabilistic forecasts are developed for low to high streamflow using predictors that reflect climatic and anthropogenic influences. Results indicate that GCM forecasts of climate and antecedent climatic conditions enhance seasonal streamflow predictability; while land cover and population density predictors decrease biases or enhance skill in certain catchments. This paper paves the way for novel forecasting approaches using dynamical GCM predictions within statistical frameworks.
Eddy Tracking in the Northwestern Indian Ocean During Southwest Monsoon Regimes
Authors: Trott Corinne B. , Subrahmanyam Bulusu , Chaigneau Alexis , Delcroix Thierry 
Published: June 2018

AbstractThe northwestern Indian Ocean exhibits a relatively highly energetic eddy field during the southwest monsoon season between June and September. This study analyzes the seasonal and interannual variability of the eddy characteristics and their trajectories in the northwestern Indian Ocean using altimetric sea surface height observations from 1993 to 2014. Although the highest number of eddies is found in the Arabian Peninsula coastal region, the strongest eddies, characterized by large radii, amplitudes, and eddy kinetic energies are found along the Somali Current. Trajectories of anticyclonic and cyclonic eddies are investigated to provide insight on the generation and propagation of eddies of varying amplitudes. The largest annual eddy in the Somali Current system corresponds to the Great Whirl, for which the year‐to‐year variability with respect to shape, size, generation, and propagation was examined, as was the development of these characteristics over the Great Whirl's lifetime.
Security of Deep Groundwater in the Coastal Bengal Basin Revealed by Tracers
Authors: Lapworth D. J. , Zahid A. , Taylor R. G. , Burgess W. G. , Shamsudduha M. , Ahmed K. M. , Mukherjee A. , Gooddy D. C. , Chatterjee D. , MacDonald A. M. 
Published: June 2018

AbstractUncertainty persists regarding the vulnerability of deep groundwater across Asia's megadeltas. In the coastal Bengal Basin aquifer system, shallow groundwater (<100 m) commonly features high salinity or arsenic concentrations, and deep, better‐quality, groundwater supplies drinking water to >80 million people. Here we report new radiocarbon evidence from a network of nine dedicated, multilevel monitoring wells, which indicates residence times of between 103 and 104 years for groundwater at depths >150 m. Modern groundwater detected in some deep abstraction wells using anthropogenic tracers (SF6, CFCs) is attributed to short circuiting of shallow groundwater within wells. Age‐depth profiles and hydrochemical data in monitoring wells confirm the regional resilience of deep groundwater to ingress of shallow contaminated groundwater. Our results are consistent with high regional anisotropy in the aquifer and support continued use of deep groundwater though the potential for leakage of shallow contaminated groundwater in deep abstraction wells requires careful monitoring.
Can Formulas Derived From Pyroxenes and/or HEDs Be Used to Determine the Mineralogies of V‐Type Asteroids?
Authors: Burbine T. H. , Buchanan P. C. , Klima R. L. , Binzel R. P. 
Published: June 2018

AbstractWe compare methods for determining the pyroxene mineralogies of V‐type near‐Earth asteroids from their reflectance spectra. We evaluate whether band centers derived from the spectra of synthetic pyroxenes can be used to achieve greater analytical accuracy than is achieved through the use of band centers derived from the spectra of basaltic achondrites (howardites, eucrites, diogenites or HEDs). We conclude that band centers derived from the reflectance spectra of synthetic pyroxenes with known mineralogies do not provide useful diagnostic information to derive equations for determining accurate pyroxene compositions of V‐type asteroids. Band centers from the reflectance spectra of HEDs with known pyroxene mineralogies can be used to derive equations for determining accurate pyroxene compositions of V‐type asteroids. HEDs are physical mixtures of a number of different types of pyroxenes and best simulate the surfaces of V‐type asteroids. Formulas using the Band I center appear best for determining asteroid pyroxene mineralogies for V‐type asteroids due to the current difficulty in doing accurate temperature corrections to the Band II center. Most of the observed V‐type near‐Earth asteroids have interpreted mineralogies similar to eucrites or howardites. One of the observed near‐Earth asteroids could possibly have a surface mineralogy similar to diogenites.
Image Reconstruction Techniques in Neutron and Gamma Ray Spectroscopy: Improving Lunar Prospector Data
Authors: Wilson J. T. , Lawrence D. J. , Peplowski P. N. , Cahill J. T. S. , Eke V. R. , Massey R. J. , Teodoro L F. A. 
Published: June 2018

AbstractWe present improved resolution maps of the Lunar Prospector Neutron Spectrometer thermal, epithermal, and fast neutron data and gamma ray spectrometer Th‐line fluxes via global application of pixon image reconstruction techniques. With the use of mock data sets, we show that the pixon image reconstruction method compares favorably with other methods that have been used in planetary neutron and gamma ray spectroscopy. The improved thermal neutron maps are able to clearly distinguish variations in composition across the lunar surface, including within the lunar basins of Hertzsprung and Schrödinger. The improvement in resolution reveals a correlation between albedo and thermal neutron flux within the basins. The consequent increase in dynamic range confirms that Hertzsprung basin contains one of the most anorthositic parts of the lunar crust, including nearly pure anorthite over a region tens of kilometers in diameter. At Orientale, the reconstructed epithermal neutron data show broad overlap with circular polarization ratio but there remains a mismatch between measures of regolith maturity that sample the surface and those that probe the near subsurface, which is consistent with a complex layering scenario.
Towards a More Earth‐Like Circulation in Idealized Models
Authors: Wu Zheng , Reichler Thomas 
Published: June 2018

AbstractIdealized models are useful for the investigation of dynamical phenomena in which physical processes play a secondary role. Typically, such models employ highly idealized topography and zonally symmetric equilibrium temperatures as forcings. However, these simplifications are somewhat unrealistic and make these models unfit for investigations in which similarity with the real atmosphere is crucial. In this study, we present a new idealized model of the stratosphere‐troposphere system which has a more Earth‐like circulation than previous models. We accomplish this by introducing into the dry dynamical core of the Geophysical Fluid Dynamics Laboratory realistic topography and equilibrium temperatures with zonal asymmetries. We then explore the model's sensitivity to the prescribed strength of the surface momentum drag. We find improvements in the model's circulation when validating against reanalysis. Most notably, the strength and structure of the winds, the spectrum of planetary waves, and the frequency of stratospheric sudden warming events are more realistic than in traditional idealized models. In the extratropics, the diagnosed diabatic forcing of the model also compares favorably against the observations. We further find that variations in the surface momentum damping exert an important control on the model's circulation, including the frequency of stratospheric sudden warming events. We believe that the new model reduces the gap between traditional idealized models and full models and that it is useful for the investigation of phenomena in which greater similarity with the real system is needed. The code for the new model and its equilibrium temperature data set is published on GitHub.
A strong link between marine microbial community composition and function challenges the idea of functional redundancy
Authors: Galand Pierre E , Pereira Olivier , Hochart Corentin , Auguet Jean Christophe , Debroas Didier 
Published: June 2018

Abstract
Marine microbes have tremendous diversity, but a fundamental question remains unanswered: why are there so many microbial species in the sea? The idea of functional redundancy for microbial communities has long been assumed, so that the high level of richness is often explained by the presence of different taxa that are able to conduct the exact same set of metabolic processes and that can readily replace each other. Here, we refute the hypothesis of functional redundancy for marine microbial communities by showing that a shift in the community composition altered the overall functional attributes of communities across different temporal and spatial scales. Our metagenomic monitoring of a coastal northwestern Mediterranean site also revealed that diverse microbial communities harbor a high diversity of potential proteins. Working with all information given by the metagenomes (all reads) rather than relying only on known genes (annotated orthologous genes) was essential for revealing the similarity between taxonomic and functional community compositions. Our finding does not exclude the possibility for a partial redundancy where organisms that share some specific function can coexist when they differ in other ecological requirements. It demonstrates, however, that marine microbial diversity reflects a tremendous diversity of microbial metabolism and highlights the genetic potential yet to be discovered in an ocean of microbes.
Selection for increased quorum-sensing cooperation in Pseudomonas aeruginosa through the shut-down of a drug resistance pump
Authors: Oshri Ron D , Zrihen Keren S , Shner Itzhak , Omer Bendori Shira , Eldar Avigdor 
Published: June 2018

Abstract
The opportunistic pathogen Pseudomonas aeruginosa employs a hierarchical quorum-sensing network to regulate virulence factor production that cooperatively benefit the population at a cost to the individual. It has been argued that the evolution of a cooperative mutant in a quorum sensing-suppressed population would be hampered through its exploitation by neighboring non-mutant cells. It remains unclear whether mechanisms which overcome this exploitation exist. Here we investigate the regain of quorum-sensing cooperation by evolving a mutant of the lasR master quorum-sensing regulator. The mutant regained partial cooperative growth through null mutations in mexT, which codes for an activator of the MexEF-OprN multidrug-resistant pump. We find that these mutations enhance cooperative growth in both the lasR mutant and wild-type backgrounds through the activation of the RhlIR system. We show that the regain of cooperation in mexT mutants is mediated by the reduction in MexEF-OprN activity, whereas an additional source of private benefit is mostly mexEF-oprN-independent. Finally, we show that addition of antibiotics for which resistance is mediated by MexEF-OprN prevents the selection of increased cooperation at sub-MIC concentrations. MexT, therefore, not only links private and public goods, but also exposes conflicts between selection for antibiotic resistance and enhanced cooperation.
SERPINB2 is a novel indicator of stem cell toxicity
Authors: Lee Na-Hee , Cho Ara , Park Se-Ra , Lee Jin Woo , Sung Taek Park , Park Chan Hum , Choi Yoon-Hyeong , Lim Soyi , Baek Min-Kwan , Kim Dong Young , Jin Mirim , Lee Hwa-Yong , Hong In-Sun 
Published: June 2018

AbstractThe toxicological evaluation of potential drug candidates is very important in the preclinical phase of drug development. Toxic materials may cause serious decline in stem cell function and loss of stemness. Indeed, we found that toxic exposure more profoundly suppressed the growth of stem cells than terminally differentiated fibroblasts. Importantly, toxic exposure suppressed stem cell migration and multi-lineage differentiation potential in vitro and in vivo. Moreover, early-response genes involved in stem cell properties such as self-renewal and differentiation capabilities can be used as specific markers to predict toxicity. In the present study, we also identified a labile toxic response gene, SERPINB2, which is significantly increased in response to various toxic agents in human stem cells in vitro and in vivo. Consistently, self-renewal, migration, and multi-lineage differentiation potential were markedly decreased following SERPINB2 overexpression. To the best of our knowledge, this is the first study to focus on the functions of SERPINB2 on the regenerative potential of stem cells in response to various existing chemicals, and the findings will facilitate the development of promising toxicity test platforms for newly developed chemicals.
Estimating spatiotemporally varying malaria reproduction numbers in a near elimination setting
Authors: Routledge Isobel , Chevéz José Eduardo Romero , Cucunubá Zulma M. , Rodriguez Manuel Gomez , Guinovart Caterina , Gustafson Kyle B. , Schneider Kammerle , Walker Patrick G.T. , Ghani Azra C. , Bhatt Samir 
Published: June 2018

AbstractIn 2016 the World Health Organization identified 21 countries that could eliminate malaria by 2020. Monitoring progress towards this goal requires tracking ongoing transmission. Here we develop methods that estimate individual reproduction numbers and their variation through time and space. Individual reproduction numbers, Rc, describe the state of transmission at a point in time and differ from mean reproduction numbers, which are averages of the number of people infected by a typical case. We assess elimination progress in El Salvador using data for confirmed cases of malaria from 2010 to 2016. Our results demonstrate that whilst the average number of secondary malaria cases was below one (0.61, 95% CI 0.55–0.65), individual reproduction numbers often exceeded one. We estimate a decline in Rc between 2010 and 2016. However we also show that if importation is maintained at the same rate, the country may not achieve malaria elimination by 2020.
miR-23b and miR-218 silencing increase Muscleblind-like expression and alleviate myotonic dystrophy phenotypes in mammalian models
Authors: Cerro-Herreros Estefania , Sabater-Arcis Maria , Fernandez-Costa Juan M. , Moreno Nerea , Perez-Alonso Manuel , Llamusi Beatriz , Artero Ruben 
Published: June 2018

AbstractFunctional depletion of the alternative splicing factors Muscleblind-like (MBNL 1 and 2) is at the basis of the neuromuscular disease myotonic dystrophy type 1 (DM1). We previously showed the efficacy of miRNA downregulation in Drosophila DM1 model. Here, we screen for miRNAs that regulate MBNL1 and MBNL2 in HeLa cells. We thus identify miR-23b and miR-218, and confirm that they downregulate MBNL proteins in this cell line. Antagonists of miR-23b and miR-218 miRNAs enhance MBNL protein levels and rescue pathogenic missplicing events in DM1 myoblasts. Systemic delivery of these “antagomiRs” similarly boost MBNL expression and improve DM1-like phenotypes, including splicing alterations, histopathology, and myotonia in the HSALR DM1 model mice. These mammalian data provide evidence for therapeutic blocking of the miRNAs that control Muscleblind-like protein expression in myotonic dystrophy.
In utero nanoparticle delivery for site-specific genome editing
Authors: Ricciardi Adele S. , Bahal Raman , Farrelly James S. , Quijano Elias , Bianchi Anthony H. , Luks Valerie L. , Putman Rachael , López-Giráldez Francesc , Coşkun Süleyman , Song Eric , Liu Yanfeng , Hsieh Wei-Che , Ly Danith H. , Stitelman David H. , Glazer Peter M. , Saltzman W. Mark 
Published: June 2018

AbstractGenetic diseases can be diagnosed early during pregnancy, but many monogenic disorders continue to cause considerable neonatal and pediatric morbidity and mortality. Early intervention through intrauterine gene editing, however, could correct the genetic defect, potentially allowing for normal organ development, functional disease improvement, or cure. Here we demonstrate safe intravenous and intra-amniotic administration of polymeric nanoparticles to fetal mouse tissues at selected gestational ages with no effect on survival or postnatal growth. In utero introduction of nanoparticles containing peptide nucleic acids (PNAs) and donor DNAs corrects a disease-causing mutation in the β-globin gene in a mouse model of human β-thalassemia, yielding sustained postnatal elevation of blood hemoglobin levels into the normal range, reduced reticulocyte counts, reversal of splenomegaly, and improved survival, with no detected off-target mutations in partially homologous loci. This work may provide the basis for a safe and versatile method of fetal gene editing for human monogenic disorders.