bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of CaSO4micrograins in the context of organic matter delivery: thermochemistry and atmospheric entry
Authors: Micca Longo G. , Piccinni V. , Longo S. 
Published: July 2018

AbstractIn this paper, anhydrous calcium sulphate CaSO4(anhydrite) is considered as a carrier material for organic matter delivery from Space to Earth. Its capability of incorporating important fractions of water, leading to different species like bassanite and gypsum, as well as organic molecules; its discovery on Mars surface and in meteorites; the capability to dissipate much energy by its chemical decomposition into solid (CaO) and gaseous (SO3) oxide, make anhydrite a very promising material in an astrobiological perspective. Since chemical cooling has been recently considered by some of the present authors for the case of Ca/Mg carbonates, CaSO4can be placed into a class of ‘white soft minerals’ (WSM) of astrobiological interest. In this context, CaSO4is evaluated here by using the atmospheric entry model previously developed for carbonates. The model includes grain dynamics, thermochemistry, stoichiometry, radiation and evaporation heat losses. Results are discussed in comparison with MgCO3and CaCO3and show that sub-mm anhydrite grains are potentially effective organic matter carriers. A Monte Carlo simulation is used to provide distributions of the sulphate fraction as a function of altitude. Two-zone model results are presented to support the isothermal grain hypothesis.
Response of Glyphosate-resistant and Conventional Soybean Grafted Plants to Glyphosate
Authors: Chen Yin , Jiang Linjian , Doohan Douglas 
Published: July 2018

AbstractGrafting is a common technique used to impart desirable traits to a plant’s scion. Herbicide resistant rootstocks have the potential to confer non–genetically modified (non-GM) scions with herbicide tolerance while mitigating some societal concerns regarding GM crops and food. We examined the impacts of soybean cultivar and growth stage and environmental temperature on transference of glyphosate tolerance to conventional (CN) soybean scions when grafted to glyphosate-resistant (RR) rootstocks. Small CN/RR (scion/rootstock) plants (3-leaf stage) and medium-sized plants (6-leaf stage) were injured more than large plants (10-leaf stage) 34 d after treatment (DAT) with 0.84 and 1.68 kg ae ha−1 glyphosate. All CN/CN combinations died, and RR/RR were uninjured. The cultivar of the scion had a greater effect on glyphosate tolerance than the cultivar of the rootstock. CN scions 352 and 5418 were more tolerant than CN scion 5388 across all RR rootstocks 35 DAT when treated with 0.84 kg ha−1 glyphosate. CN/RR construct 5388/9392 was more sensitive to temperature compared with 352/9392. Less leaf regrowth of 5388/9392 was observed under the warmer temperature. Our experiments demonstrated that grafting imparted robust glyphosate tolerance across different plant sizes, environmental temperatures, and scion/rootstock cultivars.
Negative Affect-Related Autonomic Arousal Mediates the Association Between Baroreflex Dysfunction and Insulin Resistance in Non-Diabetic Young Adults
Authors: Dennis Paul A. , Neal Julia M. , Travis Emili , Watkins Lana L. , Calhoun Patrick S. , Dennis Michelle F. , Beckham Jean C. 
Published: July 2018

Abstract. Autonomic dysfunction, in particular under-regulation of heart rate (HR) by the baroreflex, is implicated in development of insulin resistance (IR). According to reactivity hypothesis, sympathetic response to stressors may be more sensitive at predicting IR than baroreceptor sensitivity (BRS), a baseline measure of baroreflex functioning. Using ecological momentary assessment (EMA) of negative affect coupled with minute-to-minute HR and heart-rate variability (HRV) monitoring, we examined whether negative affect (NA)-related autonomic arousal mediates the association of BRS with IR. At baseline, BRS was measured, and fasting serum glucose and insulin levels were collected from 178 young adults (18–39 years old), from which homeostasis model assessment of IR (HOMA-IR) and beta-cell functioning (HOMA %B) were derived. Participants subsequently underwent one day of Holter HR and HRV monitoring while reporting NA levels via EMA. Multilevel modeling was used to assess the associations of momentary NA with HR and low- (LF) and high-frequency (HF) HRV during the 5-minute intervals following each EMA reading. Structural equation modeling was then used to determine whether individual differences in these associations mediated the association of BRS with IR, measured by HOMA-IR, HOMA %B, and insulin levels. As predicted, BRS was negatively associated with the IR (β = −.17, p = .024). However, NA-related autonomic arousal mediated their association, accounting for 56% of the covariance between BRS and IR. Not only do these results provide support for reactivity hypothesis, they reveal a potential point of intervention in the treatment of affective dysregulation.
Time‐Dependent Consolidation in Porous Geomaterials at In Situ Conditions of Temperature and Pressure
Authors: Choens R. C. , Chester F. M. 
Published: July 2018

AbstractAnalysis of quartz sandstones shows that grain‐scale crushing (fracture and rearrangement) and associated sealing of fractures contribute significantly to consolidation. The crushing strength (P*) for granular material is defined by laboratory experiments conducted at strain rates of 10−4 to 10−5 s−1 and room temperature. Based on experiments, many sandstones would require burial depths in excess of the actual maximum burial depth to create observed microstructure and density. We use experiments and soil mechanics principles to determine rate laws for brittle consolidation of fine‐grained quartz sand to better estimate in situ failure conditions of porous geomaterials. Experiments were conducted on St. Peter sand utilizing different isostatic consolidation and creep load paths at temperatures to 200 °C and at strain rates of 10−4 to 10−10 s−1. Experiment results are consistent with observed rate dependence of consolidation in soils, and P* for sand can be identified by the change in the dependence of consolidation rate with stress, allowing the extrapolation of P* determined in the laboratory to geologic rates and temperatures. Additionally, normalized P* values can be described by a polynomial function to quantify temperature, stress, and strain‐rate relationships for the consolidation of porous geomaterials by subcritical cracking. At geologic loading rates, P* for fine‐grained quartz sand is achieved within ~3‐km burial depth, and thus, shear‐enhanced compaction under nonisostatic stress can occur at even shallower depths. These results demonstrate that time and temperature effects must be considered for predicting the brittle consolidation of sediments in depositional basins, petroleum reservoirs, and engineering applications.
Evolution of Conduit Geometry and Eruptive Parameters During Effusive Events
Authors: Aravena A. , Cioni R. , de’ Michieli Vitturi M. , Pistolesi M. , Ripepe M. , Neri A. 
Published: July 2018

AbstractThe dynamics of effusive events is controlled by the interplay between conduit geometry and source conditions. Dyke‐like geometries have been traditionally assumed for describing conduits during effusive eruptions, but their depth‐dependent and temporal modifications are largely unknown. We present a novel model which describes the evolution of conduit geometry during effusive eruptions by using a quasi steady state approach based on a 1‐D conduit model and appropriate criteria for describing fluid shear stress and elastic deformation. This approach provides time‐dependent trends for effusion rate, conduit geometry, exit velocity, and gas flow. Fluid shear stress leads to upward widening conduits, whereas elastic deformation becomes relevant only during final phases of effusive eruptions. Simulations can reproduce different trends of effusion rate, showing the effect of magma source conditions and country rock properties on the eruptive dynamics. This model can be potentially applied for data inversion in order to study specific case studies.
Fluid‐Induced Fracturing of Initially Damaged Granite Triggered by Pore Pressure Buildup
Authors: Katayama Ikuo , Nicolas Aurélien , Schubnel Alexandre 
Published: July 2018

AbstractFluid flow‐induced seismic activity has been observed in various environments; however, the relations among fluid migration, pore pressure buildup, and fracturing remain poorly understood. In the present study, we conducted fluid‐induced fracture experiments on initially damaged granite. Acoustic events and macroscopic failure of the samples were triggered exclusively by a buildup of pore pressure, and fracturing occurred when the average effective stress reached a critical stress state (following the Mohr‐Coulomb criterion). The spatiotemporal distribution of acoustic events is mainly controlled by the pore pressure diffusion front through the sample. Fluid migration velocity was dependent primarily on the initial stress state and permeability. Although the propagation of acoustic events was slower in our laboratory experiments than in natural seismic swarms, a similar parabolic relationship in space and time suggests that these microearthquakes are likely triggered by the passage of a critical pore fluid pressure through the damaged zones.
Hysteresis and Resilience of the AMOC in an Eddy‐Permitting GCM
Authors: Jackson L. C. , Wood R. A. 
Published: July 2018

AbstractWe show a quasi‐irreversible shutdown (hysteresis) of the Atlantic meridional overturning circulation (AMOC) in an unfluxadjusted global climate model with an eddy‐permitting ocean. This global climate model is a prototype of one submitted to the sixth Coupled Model Intercomparison Project and is the most comprehensive model to show this behavior. The AMOC has a resilience timescale for a given hosing: If the hosing exceeds the critical hosing for collapse for only a limited time, the AMOC recovers when the hosing is stopped. Beyond the critical time, when the hosing stops the AMOC stays in a weak state with no recovery within 200 years. We show that simple, observable metrics such as AMOC strength and mixed layer depth can indicate whether this critical resilience time has passed and that the mechanism controlling the presence of recovery is a positive advective feedback.
Bagnold Dunes Campaign Phase 2: Visible/Near‐Infrared Reflectance Spectroscopy of Longitudinal Ripple Sands
Authors: Johnson Jeffrey R. , Bell James F. , Bender Steve , Cloutis Edward , Ehlmann Bethany , Fraeman Abigail , Gasnault Olivier , Maurice Sylvestre , Pinet Patrick , Thompson Lucy , Wellington Danika , Wiens Roger C. 
Published: July 2018

AbstractAs part of the Phase 2 Bagnold Dune campaign at Gale Crater, Mars, constraints on the geochemistry, mineralogy, and oxidation state of pristine and disturbed linear sand ripples were made using visible/near‐infrared spectral observations for comparison to Phase 1 spectra of the barchan dunes to the north. Spectra acquired by the ChemCam and Mastcam instruments (400–1,000 nm) at four Phase 2 locations revealed similar overall spectral trends between the two regions, but most Phase 2 sands were redder in the visible wavelengths. The majority of targets exhibited lower red/infrared ratios, higher ~530‐nm band depths, and higher red/blue ratios than Phase 1 samples, suggesting a greater proportion of redder, fine‐grained, ferric sands in Phase 2 samples. This is consistent with the slightly greater proportion of hematite in Phase 2 samples as determined from CheMin analyses of the Ogunquit sands, which may reflect contamination from the surrounding hematite‐bearing Murray formation bedrock.
Ionospheric Density Irregularities, Turbulence, and Wave Disturbances During the Total Solar Eclipse Over North America on 21 August 2017
Authors: Pradipta Rezy , Yizengaw Endawoke , Doherty Patricia 
Published: July 2018

AbstractData from ionosonde and global positioning system (GPS) total electron content (TEC) observations reveal a number of ionospheric phenomena during the total solar eclipse on 21 August 2017 over North America. The eclipse started over the West Coast at ∼16:00 UTC (∼07:53 LT) and ended over the East Coast at ∼20:00 UTC (∼14:46 LT). We identify a growth of plasma density irregularities and turbulence on the bottomside ionosphere during the eclipse totality (at ∼10:03 LT over Idaho Falls), signified by the distinct appearance of spread‐F echoes in the ionosonde data. In addition, data from the ionosonde observations also show some characteristic signatures of traveling ionospheric disturbances at ∼300‐km altitude during the eclipse. Finally, large reductions in TEC and ionospheric plasma densities (by 33–45%) due to the eclipse were observed in both the GPS TEC and ionosonde data.
Comparison of Dust Impact and Solitary Wave Signatures Detected by Multiple Electric Field Antennas Onboard the MMS Spacecraft
Authors: Vaverka Jakub , Nakamura Takuji , Kero Johan , Mann Ingrid , De Spiegeleer Alexandre , Hamrin Maria , Norberg Carol , Lindqvist Per‐Arne , Pellinen‐Wannberg Asta 
Published: July 2018

AbstractDust impact detection by electric field instruments is a relatively new method. However, the influence of dust impacts on electric field measurements is not completely understood and explained. A better understanding is very important for reliable dust impact identification, especially in environments with low dust impact rate. Using data from Earth‐orbiting Magnetospheric Multiscale mission (MMS) spacecraft, we present a study of various pulses detected simultaneously by multiple electric field antennas in the monopole (probe‐to‐spacecraft potential measurement) and dipole (probe‐to‐probe potential measurement) configurations. The study includes data obtained during an impact of a millimeter‐sized object. We show that the identification of dust impacts by a single antenna is a very challenging issue in environments where solitary waves are commonly present and that some pulses can be easily misinterpreted as dust impacts. We used data from multiple antennas to distinguish between changes in the spacecraft potential (dust impact) and structures in the ambient plasma or electric field. Our results indicate that an impact cloud is in some cases able to influence the potential of the electric field antenna during its expansion.
ULF Electromagnetic Field in the Upper Ionosphere Excited by Lightning
Authors: Mazur N. G. , Fedorov E. N. , Pilipenko V. A. , Vakhnina V. V. 
Published: July 2018

AbstractWe examine excitation of ultralow frequency (ULF) electromagnetic waves by an atmospheric lightning stroke in the upper ionosphere and the role of the ionospheric Alfvén resonator (IAR) in this process. We have theoretically calculated with the developed numerical model the spatial and spectral structures of electromagnetic disturbance in the ULF frequency range 0.1–6.0 Hz excited by an atmospheric lightning stroke on the ground and at ionospheric altitudes. The frequency band under consideration comprises typical frequencies of the IAR and the ionospheric waveguide. The spectra of horizontal magnetic and electric components reveal a spectral multiband structure in the upper ionosphere. The form of spectra depends significantly on the horizontal distance ρ from the source: spectral peaks associated with the IAR are evident at ρ≤400 km, whereas at ρ≥1,000 km the spectral peaks (>4 Hz) corresponding to the ionospheric waveguide modes can be seen. The model predicts that a vertical electric discharge with the charge moment MQ=106 C·m produces at altitude 500 km and ρ = 40 km a pulse with electric and magnetic amplitudes of about 4 mV/m and 4 nT, correspondingly, and duration ∼0.2 s. The pulse amplitude decays rather slowly with distance
. Detection of ULF response in the upper ionosphere to isolated intense lightning stroke by low‐orbiting satellites with magnetic or electric sensors onboard is quite feasible.
The Biogeochemistry of Electroactive Humic Substances and Its Connection to Iron Chemistry in the North East Atlantic and the Western Mediterranean Sea
Authors: Dulaquais Gabriel , Waeles Matthieu , Gerringa Loes J. A. , Middag Rob , Rijkenberg Micha J. A. , Riso Ricardo 
Published: July 2018

AbstractWe present the zonal distribution of electroactive humic‐like substances (eHS) along a section from Offshore Portugal in the North East Atlantic to the Sicily Channel in the Mediterranean Sea. The concentrations were normalized to Suwannee River Fulvic Acid and ranged from 11 μg/L to 81 μg/L. The vertical distributions were typical of those previously reported for dissolved organic carbon in the Mediterranean Sea. High eHS concentrations were measured in surface water and concentrations decreased with depth before increasing again toward benthic maxima measured at some stations. We estimate that eHS represented a relatively small fraction of the natural organic matter in the Mediterranean Sea (2–5%) but considering their important role in the complexation and the solubility of key trace elements (e.g., iron and copper), the eHS cycle could influence the entire biogeochemistry of these marine systems. We identified key processes controlling the concentration of eHS. While biologically mediated production was the major source of eHS, riverine and rain inputs as well as sediment release were also likely external sources. Low eHS concentrations at subsurface depths pointed to photodegradation as a possible sink of eHS, but degradation by heterotrophic bacteria seemed to be the main sink in the deep sea. Finally, we found a positive correlation between dissolved iron and eHS concentrations. Estimation of eHS contribution to iron binding ligand concentrations indicates the complexation of iron by eHS in the Mediterranean Sea. These observations suggest links between the cycles of eHS and iron in the Mediterranean Sea.
A Study of Cloud Microphysical Processes Associated With Torrential Rainfall Event Over Beijing
Authors: Mao Jiahua , Ping Fan , Yin Lei , Qiu Xinfa 
Published: July 2018

AbstractThe evolution of mesoscale convective systems (MCSs) leading to a heavy rainstorm event that occurred in Beijing on 21 July 2012 was simulated using the Weather Research and Forecasting model. Observational analyses indicated that this event can be divided into an earlier‐occurring warm‐sector precipitation (WSP) and a later‐occurring cold‐frontal precipitation (CFP). Owing to the considerable differences in their ambient weather conditions, the features and evolution of the cloud microphysics were different. Diagnoses of the mass‐ and heat‐hydrometeor budgets showed that the major differences in rainwater source were that the graupel melting (PGMLT) and the collection of snow by rain (PRACS_s2r) had similar magnitudes in the WSP, and PGMLT was larger than PRACS_s2r in the CFP, while the accretion growth of cloud droplets (PRA) was always the largest in both phases. The main cooling effect in the WSP was due to the evaporation of rainwater (PRE) and cloud water, while it was PRE and PGMLT for the CFP. The mechanisms of how microphysical processes influenced the precipitation were explored. It was found that the strong PRA in the WSP was conducive to the formation of a supercooled water level and evoked a seeding effect. However, graupel processes were crucial for the CFP. The strong sublimation processes of graupel and snow associated with the collection of droplets by graupel caused more latent heat release and drove airflow to reach a higher convection height. Moreover, the stronger PGMLT cooled the air in the MCS and reduced the effect of cloud droplet accretion growth.
Crustal Deformation of South Korea After the Tohoku‐Oki Earthquake: Deformation Heterogeneity and Seismic Activity
Authors: Kim Sungshil , Ree Jin‐Han , Yoon Ha Su , Choi Byung‐Kyu , Park Pil‐Ho 
Published: July 2018

AbstractAlthough the 2011 Tohoku‐Oki earthquake (Mw 9.0, 11 March 2011) occurred more than 1,000 km from South Korea, it significantly changed the magnitudes and orientations of Global Positioning System (GPS) velocity vectors in the country, which took two years to return to preearthquake values. Then, areas with relatively thick crust show contractional surface deformation, whereas areas with thinner crust show dilatation, suggesting that the deformation pattern is long‐term. Although there is no one‐to‐one correlation between earthquakes and surface deformation, earthquakes tend to be concentrated in areas with higher shear strain rates. In South Korea, the stress field inferred from earthquake data is inconsistent with surface deformation calculated from GPS data. This may arise because stress orientations at earthquake focal depths are different from those at the surface, or surface deformation measured by GPS may represent interseismic elastic deformation leading to future large earthquakes, while recent earthquakes without surface ruptures might not contribute to the surface deformation. Some effects of crustal thickness on surface deformation and inconsistency between surface deformation from GPS data and kinematics from earthquake data may be a common feature of intraplate regions.
Multidecadal Trajectory of Riverine Nitrogen and Phosphorus Dynamics in Rural Catchments
Authors: Dupas Rémi , Minaudo Camille , Gruau Gérard , Ruiz Laurent , Gascuel‐Odoux Chantal 
Published: July 2018

AbstractThe long‐term evolution of nutrient dynamics in rivers under changing external forcings, termed hereafter trajectory, is influenced by local human activities and regional climatic variations. Here we investigate nitrogen (N) and phosphorus (P) dynamics in seven mesoscale agricultural catchments (median size 800 km2) of western France from seasonal to multidecadal time scales (1970–2016). Results show that, in these catchments dominated by shallow groundwater, long‐term nitrate exports responded to variations of the agricultural N surplus with time lags of approximately 10 years. Presence of legacy N storage, related to the catchments' denitrification capacity, was found to increase response times. In contrast, P trends were predominantly controlled by decreasing point source emissions during the study period, and P dynamics were influenced by in‐stream retention/remobilization processes that hampered precise quantification of land‐to‐river diffuse transport processes. Occurrence of interannual climate variations during three 5‐ to 10‐year dry‐wet cycles, influenced by the North Atlantic Oscillation, affected N and P dynamics with persistent interannual hysteresis patterns among catchment and years. Thus, water quality assessment programs should cover at least five years to decipher the effect of mitigation measures from climate variations.