bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrative Crop‐Soil‐Management Modeling to Assess Global Phosphorus Losses from Major Crop Cultivations
Authors: Liu Wenfeng , Yang Hong , Ciais Philippe , Stamm Christian , Zhao Xu , Williams Jimmy R. , Abbaspour Karim C. , Schulin Rainer 
Published: June 2018

AbstractFertilization, crop uptake followed by plant harvest, runoff and erosion, and transformations of phosphorus (P) in soil are the major factors influencing the P balance of croplands. It is important to integrate plant‐soil‐management interactions into consistent modeling systems to determine the effect of P fertilization conditions on yields and to quantify P losses. Previous assessment of P losses on large scales did not consider the interactions among these factors. Here we applied a grid‐based crop model to estimate global P losses from three most produced crops: maize, rice, and wheat. The model was forced by detailed P input data sets over the period 1998–2002. According to our simulations, global P losses from the three crops reached 1.2 Tg P/year, and about 44% of it was due to soil erosion. The global total P losses were dominated by contributions from a few hot spot regions. Reducing P fertilizer in regions experiencing excessive P uses and hence losses, especially in China and India, could achieve the same yields as today and save about two thirds of global total P inputs, with the cobenefits of declining global total P losses by 41% and downstream water quality improvement. Reducing soil erosion and retaining more crop residues on croplands could further save P inputs and alleviate P losses. This study is of significance to determine the major factors influencing P balance across regions of the world and help policy makers to propose efficient strategies for tackling P‐driven environmental problems.
Seasonal Patterns of Water Cycling in a Deep, Continental Mountain Valley Inferred From Stable Water Vapor Isotopes
Authors: Fiorella Richard P. , Poulsen Christopher J. , Matheny Ashley M. 
Published: June 2018

AbstractThe origin of atmospheric moisture is difficult to determine from meteorological measurements alone. Stable water vapor isotopes can be used to trace the atmospheric history of water vapor, and therefore are a powerful tool for understanding water cycle processes across a range of spatial and temporal scales. We present subhourly measurements of summer and winter vapor isotope ratios from a deep mountain valley in northwestern Wyoming. Vapor isotopes are paired with local meteorological measurements, and relationships between local vapor isotopic compositions and large‐scale air transport are explored using atmospheric back trajectories and a Lagrangian moisture source diagnostic. Isotopic compositions vary on diurnal to seasonal timescales, and to first order, track changes in local specific humidity. Local vapor isotopic composition varies with air transport pathway in both seasons, but cannot be uniquely mapped to a source region due to continental recycling of vapor. Diurnal variability in d‐excess is substantial in summer, but not in winter. This seasonal contrast is likely driven by local surface and near‐surface processes including evapotranspiration and boundary layer mixing, which partially overprint the source isotope ratios of the regional source during the summer and casts doubt on the use of d‐excess over continental interiors as a tracer of evaporative conditions over the ocean. Continued monitoring of the isotopic composition of near‐surface vapor in continental settings may help detect changes in regional moisture convergence and the local evapotranspiration flux, as well as assess meso‐to‐regional scale responses to hydrologic variability.
The Nature and Origin of Deposits in Uzboi Vallis on Mars
Authors: Wilson S. A. , Grant J. A. , Howard A. D. , Buczkowski D. L. 
Published: June 2018

AbstractUzboi Vallis in northwestern Noachis Terra is the uppermost segment of the Noachian to Hesperian Uzboi‐Ladon‐Morava mesoscale outflow system that dominates regional northward drainage through Noachis and Margaritifer Terrae. Recently acquired High Resolution Imaging Science Experiment (HiRISE) and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data, as well as topography, help to characterize the nature and origin of a previously unrecognized deposit on the floor of Uzboi Vallis at the confluence of Nirgal Vallis. The Uzboi floor deposit consists of a lower unit (~255 km3) and an upper unit (~34 km3). The origin and age of the lower unit are less constrained; it may have formed by a combination of impact (e.g., ejecta from Luki crater), fluvial/alluvial, and (or) mass wasting processes. The superimposed upper unit is symmetrical relative to the mouth of Nirgal, fan‐shaped in planform and layered. The morphology and location of the upper unit are consistent with alluvial (and possibly debris flow) deposition related to discharge from Nirgal Vallis. Crater Luki and the upper unit likely postdate the draining of the short‐lived lake in Uzboi that formed after the mid‐ to Late Hesperian Holden crater blocked the northern end of Uzboi. Late‐stage aqueous activity from Nirgal may have been sustained to some extent by groundwater discharge from aquifers along Nirgal that were recharged when Uzboi hosted a lake and (or) somewhat limited precipitation‐fed surface runoff. The associated climate in the mid‐ to Late Hesperian was favorable for such aqueous processes, and it may have provided habitable surface conditions in this region relatively late in Martian history.
Numerical Modeling of the Concentric Gravity Wave Seeding of Low‐Latitude Nighttime Medium‐Scale Traveling Ionospheric Disturbances
Authors: Chou Min‐Yang , Lin Charles C. H. , Huba Joseph D. , Lien Chuan‐Ping , Chen Chia‐Hung , Yue Jia , Chang Loren C. , Rajesh P. K. 
Published: June 2018

AbstractThe first‐principles three‐dimensional ionosphere model Naval Research Laboratory SAMI3/ESF is used to study the low‐latitude nighttime medium‐scale traveling ionospheric disturbances (MSTIDs) triggered by the typhoon‐induced concentric gravity waves (CGWs) for the first time. Simulation results demonstrate that the electrodynamic coupling between CGWs and Perkins instability can initiate the rarely observed low‐latitude nighttime MSTIDs by accelerating their growth rates. Both the simulations and observations show that the westward and westward/equatorward propagating CGWs with similar wavefront alignments to the Perkins instability could enhance the generation of MSTIDs rather than the northward propagating CGWs. The CGWs penetrating to the ionospheric F layer without severe dissipation can induce greater polarization electric fields to accelerate the Perkins instability via E × B drifts.
Centroid Moment Tensor Inversion of Shallow Very Low Frequency Earthquakes Off the Kii Peninsula, Japan, Using a Three‐Dimensional Velocity Structure Model
Authors: Takemura Shunsuke , Matsuzawa Takanori , Kimura Takeshi , Tonegawa Takashi , Shiomi Katsuhiko 
Published: June 2018

AbstractWe conducted centroid moment tensor inversions of shallow very low frequency earthquakes (SVLFEs) that occurred around off the southeast Kii Peninsula, Japan. A set of Green's functions was evaluated using numerical simulations of seismic wave propagation in a three‐dimensional velocity structure model, including the subducting Philippine Sea slab and the accretionary prism. We used observed seismograms for periods of 20–50 s at an onshore broadband network, which enable us to investigate the long‐term activity of SVLFEs. Estimated centroid locations and focal mechanisms of SVLFEs, including SVLFEs that occurred prior to the deployment of seafloor observations, were very similar to those estimated using seafloor records. Low‐angle thrust faulting mechanisms were concentrated around the accretionary prism toe. SVLFE activity in April 2016 was concentrated further west in an area of previous activity. Our results imply seismic slip around the very shallow part of the Philippine Sea plate boundary.
Increase in Subdaily Precipitation Extremes in India Under 1.5 and 2.0 °C Warming Worlds
Authors: Ali Haider , Mishra Vimal 
Published: June 2018

AbstractAn increase in short duration precipitation extremes poses challenges for storm water design in rapidly urbanizing India. The recent Paris Agreement aims to limit the global mean temperature (GMT) below 1.5 °C (and possibly below 2.0 °C) from the preindustrial level. However, the changes in subdaily precipitation extremes in India remain unrecognized under the 1.5‐ and 2.0‐°C temperature targets. Here using observations and projections of the subdaily precipitation, we show that a majority (11 out of 15) of General Circulation Models underestimate 3‐hourly precipitation extremes and overestimate the relationship between 3‐hourly precipitation extremes and GMT (scaling) in India. A rise of 1.5 (2.0 °C) in GMT from the preindustrial level is projected to cause 20% (25%) increase in 3‐hourly precipitation maxima at 100‐year return period under the stationary condition, which can further rise by 10% under the nonstationary condition. Projected warming results in a much faster (almost twice) increase in 3‐hourly precipitation maxima than 24‐hourly 100‐year precipitation maxima. Moreover, 3‐hourly 100‐year precipitation maxima are projected to increase significantly at 78 locations (out of 89) if GMT increases from 1.5 to 2.0 °C from the preindustrial level. Our findings have implications for urban storm water designs in India.
ARTEMIS Observations of Solar Wind Proton Scattering off the Lunar Surface
Authors: Lue C. , Halekas J. S. , Poppe A. R. , McFadden J. P. 
Published: June 2018

AbstractWe study the scattering of solar wind protons off the lunar surface, using ion observations collected over 6 years by the ARTEMIS satellites at the Moon. We show the average scattered proton energy spectra, directional scattering distributions, and scattering efficiency, for different solar wind incidence angles and impact speeds. We find that the protons have a scattering distribution that is similar to existing empirical models for scattered hydrogen energetic neutral atoms, with a peak in the backward direction (toward the Sun). We provide a revised model for the scattered proton energy spectrum. We evaluate the positive to neutral charge state ratio by comparing the proton spectrum with existing models for scattered hydrogen. The positive to neutral ratio increases with increasing exit speed from the surface but decreases with increasing impact speed. Combined, these counteracting effects result in a scattering efficiency that decreases from ~0.5% at 300 km/s solar wind speed to ~0.3% at 600 km/s solar wind speed.
Comparative Effects of Climate Change and Tidal Stream Energy Extraction in a Shelf Sea
Authors: De Dominicis Michela , Wolf Judith , O'Hara Murray Rory 
Published: June 2018

AbstractThe environmental implications of tidal stream energy extraction need to be evaluated against the potential climate change impacts on the marine environment. Here we study how hypothetical very large tidal stream arrays and a business as usual future climate scenario can change the hydrodynamics of a seasonally stratified shelf sea. The Scottish Shelf Model, an unstructured grid three‐dimensional ocean model, has been used to reproduce the present and the future state of the NW European continental shelf. Four scenarios have been modeled: present conditions and projected future climate in 2050, each with and without very large scale tidal stream arrays in Scottish Waters (UK). It is found that where tidal range is reduced a few centimeters by tidal stream energy extraction, it can help to counter extreme water levels associated with future sea level rise. Tidal velocities, and consequently tidal mixing, are also reduced overall by the action of the tidal turbine arrays. A key finding is that climate change and tidal energy extraction both act in the same direction, in terms of increasing stratification due to warming and reduced mixing; however, the effect of climate change is an order of magnitude larger.
Ocean Surface Layer Response to Convectively Coupled Kelvin Waves in the Eastern Equatorial Indian Ocean
Authors: Pujiana Kandaga , McPhaden Michael J. 
Published: June 2018

AbstractMoored measurements between June 2011 and April 2012 at 0°, 90°E in the Indian Ocean are analyzed to assess the surface layer response to the passage of 15 convectively coupled Kelvin waves. During the suppressed phase of the Kelvin waves, intense downward net surface heat flux, weak winds, and a strong diurnal cycle were evident. The net surface heat flux was 3 times larger than turbulent cooling at the base of the surface layer, accounting for an increase of surface layer temperature by +0.2 °C on average. In contrast, strong winds, heavy rainfall, diminished diurnal variations, and air‐sea heat loss marked the active phase, during which surface layer cooling from above by air‐sea fluxes and from below by subsurface turbulent mixing led to a decrease in surface layer temperature by −0.3 °C. Strong salinity stratification formed a thick barrier layer during the active phase, inhibiting the downward diffusion of heat below the surface layer.
Limited Acute Influence of Aerobic Methane Oxidation on Ocean Carbon Dioxide and pH in Hudson Canyon, Northern U.S. Atlantic Margin
Authors: Garcia‐Tigreros Fenix , Kessler John D. 
Published: June 2018

AbstractThe ocean continental shelves host the largest global reservoir of methane (CH4). Despite the great extent of these CH4 reservoirs, much of the CH4 released into deep ocean environments appear to dissolve in seawater prior to atmospheric emission. Once dissolved in ocean water, the CH4 emitted can be aerobically oxidized and converted into either carbon dioxide (CO2) or biomass. While hypotheses have been levied suggesting that the CO2 produced from aerobic methane oxidation could enhance ocean acidification, no empirical research has been performed to confirm or refute this hypothesis. The work presented here investigates local changes in seawater‐dissolved CO2 and pH in a region that is experiencing active CH4 seepage near the upper stability boundary of methane clathrate hydrates. We show that in an area of elevated CH4 concentrations and aerobic oxidation rates, Hudson Canyon, aerobic CH4 oxidation is only responsible for 0.3 ± 0.2% of the observed change in dissolved inorganic carbon. Measurements further show that the remineralization of both old marine and young terrestrial organic carbon is contributing more substantially to the observed changes. While this investigation did not investigate chronic, multiyear changes in ocean acidification due to CH4 oxidation, these results suggest that over short timescales, CH4 oxidation in seep fields does not have an acute influence on seawater pH.
Alternative Particle Formation Pathways in the Eastern Tropical North Pacific's Biological Carbon Pump
Authors: Cavan E. L. , Giering S. L. C. , Wolff G. A. , Trimmer M. , Sanders R. 
Published: June 2018

AbstractA fraction of organic carbon produced in the oceans by phytoplankton sinks storing 5–15 gigatonnes of carbon annually in the ocean interior. The accepted paradigm is that rapid aggregation of phytoplankton cells occurs, forming large, fresh particles which sink quickly; this concept is incorporated into ecosystem models used to predict the future climate. Here we demonstrate a slower, less efficient export pathway in the Eastern Tropical North Pacific. Lipid biomarkers suggest that the large, fast‐sinking particles found beneath the mixed layer are compositionally distinct from those found in the mixed layer and thus not directly and efficiently formed from phytoplankton cells. We postulate that they are formed from the in situ aggregation of smaller, slow‐sinking particles over time in the mixed layer itself. This export pathway is likely widespread where smaller phytoplankton species dominate. Its lack of representation in biogeochemical models suggests that they may be currently overestimating the ability of the oceans to store carbon if large, fast‐sinking, labile particles dominate simulated particle export.
A Linear Response Framework for Radiative‐Convective Instability
Authors: Beucler Tom , Cronin Timothy , Emanuel Kerry 
Published: June 2018

AbstractRadiative‐convective equilibrium is a simple paradigm for the tropical climate, in which radiative cooling balances convective heating in the absence of lateral energy transport. Recent studies have shown that a large‐scale circulation may spontaneously develop from radiative‐convective equilibrium through the interactions among water vapor, radiation, and convection. This potential instability, referred to as radiative‐convective instability, may be posed as a linear stability problem for the water vapor profile by combining a linear response framework with the weak temperature gradient approximation. We design two analytic models of convective linear response to moisture perturbations, which are similar to Betts‐Miller and bulk‐plume convection schemes. We combine these convective responses with either clear‐sky gray or real‐gas radiative responses. In all cases, despite consistent radiative feedbacks, the characteristics of convection dominate the vertical structure of the most unstable linear mode of water vapor perturbations. For Betts‐Miller convection, the stability critically depend on a key parameter: the heating to advection of moisture conversion rate (HAM); warmer atmospheres with higher HAM exhibit more linear instability. In contrast, bulk‐plume convection is stable across temperatures but becomes linearly unstable with a moisture mode peaking in the midtroposphere once combined to radiation, with approximate growth rates of 10 days.
Impact of Precipitating Electrons and Magnetosphere‐Ionosphere Coupling Processes on Ionospheric Conductance
Authors: Khazanov G. V. , Robinson R. M. , Zesta E. , Sibeck D. G. , Chu M. , Grubbs G. A. 
Published: June 2018

AbstractModeling of electrodynamic coupling between the magnetosphere and ionosphere depends on accurate specification of ionospheric conductances produced by auroral electron precipitation. Magnetospheric models determine the plasma properties on magnetic field lines connected to the auroral ionosphere, but the precipitation of energetic particles into the ionosphere is the result of a two‐step process. The first step is the initiation of electron precipitation into both magnetic conjugate points from Earth's plasma sheet via wave‐particle interactions. The second step consists of the multiple atmospheric reflections of electrons at the two magnetic conjugate points, which produces secondary superthermal electron fluxes. The steady state solution for the precipitating particle fluxes into the ionosphere differs significantly from that calculated based on the originating magnetospheric population predicted by magnetohydrodynamic and ring current kinetic models. Thus, standard techniques for calculating conductances from the mean energy and energy flux of precipitating electrons in model simulations must be modified to account for these additional processes. Here we offer simple parametric relations for calculating Pedersen and Hall height‐integrated conductances that include the contributions from superthermal electrons produced by magnetosphere‐ionosphere‐atmosphere coupling in the auroral regions.
Antithrombotic therapy for venous thromboembolism in myeloproliferative neoplasms
Authors: De Stefano Valerio , Finazzi Guido , Barbui Tiziano 
Published: June 2018

AbstractIn myeloproliferative neoplasms (MPNs) the incidence of venous thromboembolism (VTE) is 0.6–1.0 per 100 pt-years, and the rate of recurrence after VTE is 6.0–6.5 per 100 pt-yrs. Vitamin K-antagonists (VKA) reduces the risk of recurrence after VTE at usual sites (i.e., deep venous thrombosis (DVT) of the legs and pulmonary embolism (PE)) by 48–69%, with a rate of recurrent thrombosis per 100 pt-yrs of 3.4–4.7 on VKA and 8.9–9.6 off VKA; VKA discontinuation produces a 2.2-fold increased risk of novel thrombotic events with respect to continuation. However, the rate of both recurrent thrombosis and major bleeding on VKA is higher in MPN patients than in non-MPN patients, and the risk-benefit balance of long-term VKA treatment is challenging. In the absence of strong evidence, the tailored management of MPN-related VTE should operatively consider the risk categories for recurrence and bleed well established in the non-MPN setting. In summary, MPN patients with VTE are candidates for life-long VKA treatment, especially after unprovoked proximal DVT and PE. Aspirin can offer a moderate benefit in those patients who stop anticoagulation. The use of direct oral anticoagulants should be explored aiming to ameliorate the rate of bleeding.
CEACAM1 promotes CD8+ T cell responses and improves control of a chronic viral infection
Authors: Khairnar Vishal , Duhan Vikas , Patil Ashwini M. , Zhou Fan , Bhat Hilal , Thoens Christine , Sharma Piyush , Adomati Tom , Friendrich Sarah-Kim , Bezgovsek Judith , Dreesen Janine D. , Wennemuth Gunther , Westendorf Astrid M. , Zelinskyy Gennadiy , Dittmer Ulf , Hardt Cornelia , Timm Jörg , Göthert Joachim R. , Lang Philipp A. , Singer Bernhard B. , Lang Karl S. 
Published: June 2018

AbstractDysfunction of CD8+ T cells can lead to the development of chronic viral infection. Identifying mechanisms responsible for such T cell dysfunction is therefore of great importance to understand how to prevent persistent viral infection. Here we show using lymphocytic choriomeningitis virus (LCMV) infection that carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is fundamental for recruiting lymphocyte-specific protein kinase (Lck) into the T cell receptor complex to form an efficient immunological synapse. CEACAM1 is essential for activation of CD8+ T cells, and the absence of CEACAM1 on virus-specific CD8+ T cells limits the antiviral CD8+ T cell response. Treatment with anti-CEACAM1 antibody stabilizes Lck in the immunological synapse, prevents CD8+ T cell exhaustion, and improves control of virus infection in vivo. Treatment of human virus-specific CD8+ T cells with anti-CEACAM1 antibody similarly enhances their proliferation. We conclude that CEACAM1 is an important regulator of virus-specific CD8+ T cell functions in mice and humans and represents a promising therapeutic target for modulating CD8+ T cells.
Synthetic molecular evolution of hybrid cell penetrating peptides
Authors: Kauffman W. Berkeley , Guha Shantanu , Wimley William C. 
Published: June 2018

AbstractPeptides and analogs such as peptide nucleic acids (PNA) are promising tools and therapeutics, but the cell membrane remains a barrier to intracellular targets. Conjugation to classical cell penetrating peptides (CPPs) such as pTat48–60 (tat) and pAntp43–68 (penetratin) facilitates delivery; however, efficiencies are low. Lack of explicit design principles hinders rational improvement. Here, we use synthetic molecular evolution (SME) to identify gain-of-function CPPs with dramatically improved ability to deliver cargoes to cells at low concentration. A CPP library containing 8192 tat/penetratin hybrid peptides coupled to an 18-residue PNA is screened using the HeLa pTRE-LucIVS2 splice correction reporter system. The daughter CPPs identified are one to two orders of magnitude more efficient than the parent sequences at delivery of PNA, and also deliver a dye cargo and an anionic peptide cargo. The significant increase in performance following a single iteration of SME demonstrates the power of this approach to peptide sequence optimization.