bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yield Estimate (230 kt) for a Mueller‐Murphy Model of the 3 September 2017, North Korean Nuclear Test (mbNEIC = 6.3) From Teleseismic Broadband P Waves Assuming Extensive Near‐Source Damage
Authors: Chaves Esteban J. , Lay Thorne , Voytan Dimitri P. 
Published: September 2018

AbstractThe 3 September 2017 underground nuclear test (mbNEIC = 6.3) is the largest of six announced North Korean explosions. The event generated many P wave seismograms at global broadband seismic stations with good signal‐to‐noise ratio for periods less than ~5 s. Instrument deconvolution provides 435 stable broadband P wave ground displacement records in the period range 0.1 to 5.0 s. These are stacked in 26 azimuth/distance windows to average path and receiver effects. Waveform stacks and average amplitude of 4‐Hz ground displacements are modeled assuming a Mueller‐Murphy explosion source model for a granite source medium. Nonelastic pP delays consistent with burial depths in the mountainous source topography are considered, and explosion yield and an average constant‐Q attenuation operator are estimated by fitting the waveforms. For a source depth of 750 m in heavily damaged environment, the estimated yield = 230 ± 50 kt and t* = 0.78 ± 0.03 s.
Density Depletions Associated With Enhancements of Electron Cyclotron Harmonic Emissions: An ERG Observation
Authors: Kazama Y. , Kojima H. , Miyoshi Y. , Kasahara Y. , Usui H. , Wang B.‐J. , Wang S.‐Y. , Tam S. W. Y. , Chang T.‐F. , Ho P. T. P. , Asamura K. , Kumamoto A. , Tsuchiya F. , Kasaba Y. , Matsuda S. , Shoji M. , Matsuoka A. , Teramoto M. , Takashima T. , Shinohara I. 
Published: September 2018

AbstractIn this study, we describe small‐scale density depletions of cold electrons associated with electrostatic electron cyclotron harmonic (ECH) waves observed by the ERG (Exploration of energization and Radiation in Geospace) spacecraft during a plasmapause crossing near the magnetic equator in the postmidnight sector. The total electron density was roughly 2 orders of magnitude larger than that of the hot electrons, indicating existence of a cold and dense electron population below ∼20 eV. The cold electron density profile showed small‐scale density depletion regions, in which the ECH emissions were intensified. Moreover, a flux enhancement of hot electrons in the perpendicular direction was also associated with the ECH emissions intensity. This relation suggests perpendicular energization of electrons by electric field oscillation of the ECH waves.
Longitudinal Characteristics of Martian Electron Density Profiles: MGS Observations
Authors: Upadhayaya A. K. , Gupta Sumedha 
Published: September 2018

AbstractAn analysis of longitudinal characteristics of 5,600 electron density profiles returned from the Mars Global Surveyor's Radio Science experiment is carried out by dividing the entire data set into 33 subsets, keeping solar zenith angle nearly constant. We find that the peak altitude of the photochemical F1 layer (hmF1) exhibits a large degree of longitudinal variability. This variability is not seen in Earth's ionosphere. Since F1 layer is isobaric, this variability in hmF1 represents a large degree of spatial changes in the underlying neutral atmosphere. Though this variability is quite chaotic in most of the subsets, a few subsets provide some evidence for the presence of a well‐defined wave. We therefore perform a spectral fit of wave 1–3, as earlier carried out by Bougher et al. (2004, https://doi.org/10.1029/2003JE002154; 2001, https://doi.org/10.1029/2001GL012884), to all 33 subsets. Results indicate that this wave is seen only in 10 of the subsets and is most dominant between 0 to 200°E longitudes. Similar wave is seen in the longitude plots of the peak electron density of F1 layer but with a phase reversal. Further, these 10 subsets are confined mostly between 02 to 04 local solar time, thereby indicating a local time dependence of the wave. We examined the characteristics of electron density profiles located at the crests and troughs and found abnormal upliftment in F1 layer during consecutive occultations (~2 hr). Rapid spatial changes are observed during intervals as short as 2 hr. The ionosphere is lifted up and the peak density decreases when wave 1–3 is present.
An Intercomparison of VLF and Sounding Rocket Techniques for Measuring the Daytime D Region Ionosphere: Theoretical Implications
Authors: Siskind D. E. , Zawdie K. A. , Sassi F. , Drob D. P. , Friedrich M. 
Published: September 2018

AbstractWe compare the two approaches that have been used to measure the lowermost ionosphere, the measurement of the propagation of very low frequency (VLF) radio waves and the in situ sampling by sounding rockets. We focus on the altitude, latitude, and zenith angle variation of the electron density profiles inferred from these two observational techniques as compared with a theoretical photochemical model. Our results show that below 68–70 km, the VLF data and the model agree better with each other than with the sounding rocket profile. At the lowest altitudes, near 60 km, both the VLF data and the model show a greater electron density at higher latitudes, consistent with a cosmic ray flux that increases with latitude, whereas the limited rocket data show a maximum at the tropics. Above 68–70 km, the VLF data and the sounding rockets agree better and at tropical latitudes, the model fails to reproduce the observations. Specifically, the calculated electron density is lower than the data by up to a factor of 2. Possible reasons for the model deficit include underestimates of the solar Lyman alpha flux, the solar X‐ray flux and the mesospheric nitric oxide density. Once these three factors are mitigated, the model is in agreement with the observations between 60 and 80 km.
A Modeling Study on the Sensitivities of Atmospheric Charge Separation According to the Relative Diffusional Growth Rate Theory to Nonspherical Hydrometeors and Cloud Microphysics
Authors: Glassmeier F. , Arnold L. , Dietlicher R. , Paukert M. , Lohmann U. 
Published: September 2018

AbstractCollisional charge transfer between graupel and ice crystals in the presence of cloud droplets is considered the dominant mechanism for charge separation in thunderclouds. According to the relative diffusional growth rate (RDGR) theory, the hydrometeor with the faster diffusional radius growth is charged positively in such collisions. We explore sensitivities of the RDGR theory to nonspherical hydrometeors and six parameters (pressure, temperature, liquid water content, sizes of ice crystals, graupel, and cloud droplets). Idealized simulations of a thundercloud with two‐moment cloud microphysics provide a realistic sampling of the parameter space. Nonsphericity and anisotropic diffusional growth strongly control the extent of positive graupel charging. We suggest a tuning parameter to account for anisotropic effects not represented in bulk microphysics schemes. In a susceptibility analysis that uses automated differentiation, we identify ice crystal size as most important RDGR parameter, followed by graupel size. Simulated average ice crystal size varies with temperature due to ice multiplication and heterogeneous freezing of droplets. Cloud microphysics and ice crystal size thus indirectly determine the structure of charge reversal lines in the traditional temperature‐water‐content representation. Accounting for the variability of ice crystal size and potentially habit with temperature may help to explain laboratory results and seems crucial for RDGR parameterizations in numerical models. We find that the contribution of local water vapor from evaporating rime droplets to diffusional graupel growth is only important for high effective water content. In this regime, droplet size and pressure are the dominant RDGR parameters. Otherwise, the effect of local graupel growth is masked by small ice crystal sizes that result from ice multiplication.
Land‐Atmosphere Coupling in CORDEX‐Africa: Hindcast Regional Climate Simulations
Authors: Careto J. A. M. , Cardoso R. M. , Soares P. M. M. , Trigo R. M. 
Published: September 2018

AbstractSoil moisture is one of the most important variables of the climate system as it constrains evapotranspiration, affecting the surface energy and water balance. It is of particular importance over transition regions between humid and dry climates as lower evapotranspiration rates lead to higher surface air temperatures thought strong soil moisture‐temperature coupling. A new and more extensive evaluation of the surface energy balance, for the Africa Coordinated Regional Downscaling Experiment, is performed for hindcast simulations, where different Regional Climate Models are driven by ERA‐Interim reanalysis (1990–2008). A new validation is carried out, with Regional Climate Models displaying a good agreement with observations. However, large biases are found over the Sahel and southern Africa for precipitation. All models tend to underestimate maximum temperature, whereas minimum temperature is overestimated for large regions. A multimodel mean ensemble is found to outperform individual models in almost all situations, representing the best estimate of present climate. The seasonal coupling strength as determined by a correlation between latent and sensible heat fluxes indicates Sahel and western Africa as strong coupling for boreal and austral summer, respectively. Also, the strong coupling areas match the transition regions identified by the intermediate values of the evaporative fraction, varying in the spatial extent. Additionally, a new soil moisture‐temperature coupling metric is introduced, which highlights the regions where higher temperatures are influenced by evaporative stress. Therefore, this metric relates extreme daily maximum temperature with latent heat flux and is computed for monthly time scales, incorporating information from the recent past.
Uncertainties in MODIS‐Based Cloud Liquid Water Path Retrievals at High Latitudes Due to Mixed‐Phase Clouds and Cloud Top Height Inhomogeneity
Authors: Khanal Sujan , Wang Zhien 
Published: September 2018

AbstractCombined A‐train remote sensing measurements from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR‐E), CloudSat, and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to study MODIS liquid water path (LWP) uncertainties at high latitudes. The focus is on quantifying uncertainties due to mixed‐phase clouds and solar zenith angle‐dependent bias, both of which disproportionately affect the MODIS data set in the polar regions. Multisensor LWP retrievals in stratiform mixed‐phase clouds show that treating mixed‐phase clouds as liquid clouds result in LWP bias that is related to the ice water path (IWP) on average and reaches close to 15% at IWP of 150 g/m2 and can reach 40% or higher when IWP is greater than 400 g/m2. Moreover, A‐train measurements and radiative transfer modeling are used to further understand the well‐known yet unresolved solar zenith angle‐dependent high bias in MODIS LWP. It is shown that the cloud top height variation is one of the main factors that contribute to this bias due to three‐dimensional radiative interactions with cloud top inhomogeneity. Excluding only 0.5% of data points that show significant three‐dimensional errors reduces the bias by 25 g/m2 at solar zenith angle of 80° and improves agreement with the AMSR‐E LWP trends. Three‐dimensional radiative transfer simulations confirm that cloud top inhomogeneity is primarily responsible for the solar zenith angle‐dependent LWP bias as observed by the MODIS measurements. This study provides a framework to guide future improvements of MODIS LWP data set, which is a key data source to constrain climate models.
Biological Cycling of Mineral Nutrients in a Temperate Forested Shale Catchment
Authors: Soper Fiona M. , Chamberlain Samuel D. , Crumsey Jasmine M. , Gregor Sonia , Derry Louis A. , Sparks Jed P. 
Published: September 2018

AbstractBiological pumping of mineral elements (root uptake from the soil and concentration at the surface via litterfall) may be an important mechanism influencing their loss from terrestrial ecosystems by accelerating transport in runoff, though few estimates exist to assess this. In the Susquehanna Shale Hills Critical Zone Observatory (a temperate forested watershed in central Pennsylvania), we compared two independent methods (litterfall‐based and transpiration flow‐based) for estimating the total uptake of elements (Ca, K, Mg, Mn, Si, Sr, and Al) by canopy trees. Elemental concentrations were measured monthly in leaf tissue and xylem sap of dominant species Quercus rubra (chestnut oak), Q. prinus (red oak), and Acer saccharum (sugar maple) for two growing seasons. Species‐specific litterfall and transpiration (estimated by eddy covariance) were used to scale concentrations to annual fluxes. For most elements, both methods generated comparable gross fluxes in the range of 53–85 (Ca), 9–19 (Mg), 14–28 (Mn), 0.2–0.6 (Al), and 0.1–0.3 (Sr) kg·ha−1·year−1. For K, litterfall‐based methods generated substantially lower estimates than transpiration, though neither accounted comprehensively for leaching from live foliage, resorption, or potential recycling within the growing season. For most elements, uptake rates were similar in magnitude to stream losses, implying a low degree of recycling. For K and Mn however, biological uptake exceeded losses by 1–2 orders of magnitude, suggesting a biological role in ecosystem retention. We conclude that litter‐ and transpiration‐based methods can be combined to broadly estimate the magnitude of biological pumping, with additional measures of wood‐/root‐based turnover necessary for more accurate budgets.
Solar Sources of Interplanetary Magnetic Clouds Leading to Helicity Prediction
Authors: Ulrich Roger K. , Riley Pete , Tran T. 
Published: September 2018

AbstractThis study identifies the solar origins of magnetic clouds that are observed at 1 AU and predicts the helical handedness of these clouds from the solar surface magnetic fields. We started with the magnetic clouds listed by the Magnetic Field Investigation (MFI) team supporting NASA's Wind spacecraft in what is known as the MFI table and worked backward in time to identify solar events that produced these clouds. Our methods utilize magnetograms from the Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory spacecraft so that we could only analyze MFI entries after the beginning of 2011. This start date and the end date of the MFI table gave us 37 cases to study. Of these we were able to associate only eight surface events with clouds detected by Wind at 1 AU. We developed a simple algorithm for predicting the cloud helicity that gave the correct handedness in all eight cases. The algorithm is based on the conceptual model that an ejected flux tube has two magnetic origination points at the positions of the strongest radial magnetic field regions of opposite polarity near the places where the ejected arches end at the solar surface. We were unable to find events for the remaining 29 cases: lack of a halo or partial halo coronal mass ejection in an appropriate time window, lack of magnetic and/or filament activity in the proper part of the solar disk, or the event was too far from disk center. The occurrence of a flare was not a requirement for making the identification but in fact flares, often weak, did occur for seven of the eight cases.
Interpretation of Low‐Temperature Thermochronometer Ages From Tilted Normal Fault Blocks
Authors: Johnstone S. A. , Colgan J. P. 
Published: September 2018

AbstractLow‐temperature thermochronometry is widely used to measure the timing and rate of slip on normal faults. Rates are often derived from suites of footwall thermochronometer samples, but regression of age versus structural depth fails to account for the trajectories of samples during fault slip. We demonstrate that in rotating fault blocks, regression of age‐depth data is susceptible to significant errors (>10%) in the identification of the initiation and rate of faulting. Advection of heat and topographic growth influence the thermal histories of exhumed particles, but for a range of geologically reasonable fault geometries and rates these effects produce Apatite (U‐Th)/He ages comparable to those derived from rotation through fixed isotherms. We apply the fixed‐isotherm model to published data from the Pine Forest Range and the East Range, Nevada, by incorporating field and thermochronologic constraints into a Markov chain Monte Carlo model. Modeled parameters for the Pine Forest Range are described by narrow ranges of geologically reasonable values. Compared to slip rates of 0.3–0.8 km/Myr and an initiation of faulting ca. 11–12 Ma derived from visual inspection, the model predicts an average slip rate of ~1.1 km/Myr and an onset of faulting ca. 9–10 Ma. For the East Range fault block the model suggests that faulting began ~17 Ma with an extension rate of ~3 km/Myr and slowed to an extension rate of ~0.5 km/Myr at ~14 Ma. The absence of a preserved partial retention zone in the East Range sample set limits how well the model can predict fault block geometry.
Nested Scales of Spatial and Temporal Variability of Soil Water Content Across a Semiarid Montane Catchment
Authors: Kaiser Kendra E. , McGlynn Brian L. 
Published: September 2018

AbstractTopographic redistribution of water has been represented by various terrain metrics (e.g., topographic wetness index, slope, and upslope accumulated area). This type of landscape characterization has promoted the use of terrain metrics to inform how spatial patterns of soil volumetric water content (VWC) influence streamflow, ecological processes, and associated nutrient fluxes. However, evaluation of what these static terrain metrics reflect has only been accomplished in a few catchments. Additionally, previous research suggests that relationships between topographic metrics and VWC could be different across catchments through time. Here we measured VWC from snowmelt through summer drydown across a semiarid montane catchment. Using a spatially nested sampling design, we assessed the spatiotemporal variability of VWC from plot (tens of meters) to landscape scales (hundreds of meters). Variance of riparian area VWC increased as the catchment dried, while upland variance decreased, highlighting the utility of delineating distinct landscape units when considering spatial variability of moisture, rather than calculating statistics across the landscape as a whole. In contrast to previous research, we found that the relationship between VWC and topographic metrics persisted through the dry catchment state, suggesting that patterns of topographic redistribution of water during snowmelt continued to influence dry season VWC despite variability in plot scale vertical processes (e.g., evapotranspiration). Future research should focus on resolving the relationship between catchment moisture state and VWC variability as a function of wetness state, seasonality, and magnitude of precipitation, topography, and soil depth.
Autism, Early Psychosis, and Social Anxiety Disorder: a transdiagnostic examination of executive function cognitive circuitry and contribution to disability
Authors: Demetriou Eleni A. , Song Christine Y. , Park Shin H. , Pepper Karen L. , Naismith Sharon L. , Hermens Daniel F. , Hickie Ian B. , Thomas Emma E. , Norton Alice , White Django , Guastella Adam J. 
Published: September 2018

AbstractThe disability burden in clinical cohorts with social impairment is significant, leading to poor functional outcomes. Some of this impairment has been linked to executive dysfunction. In this study, a transdiagnostic approach was taken to identify executive function (EF) processes in young adults that may underpin social impairment and to evaluate their contribution to disability. Comparisons were made between three prominent disorders that are characterized by social impairments, Autism Spectrum Disorder (ASD), Early Psychosis (EP) and Social Anxiety Disorder (SAD), as well as a neurotypically developing group (TYP). We examined whether overall disability could be predicted by neuropsychological and self-report assessments of EF. Our study showed that ASD participants demonstrated impaired performance on most domains of EF compared to the TYP group (mental flexibility, sustained attention and fluency) while the EP group showed impairment on sustained attention and attentional shifting. The SAD participants showed EF impairment on self-report ratings, even though their objective performance was intact. Self-reports of EF explained a significant percentage (17%) of disability in addition to the variance explained by other predictors, and this was particularly important for ASD. This is the first study to compare EF measures across clinical groups of social impairment and suggests unique cognitive-circuitry that underpins disability within groups. Impairments in EF were broad in ASD and predicted disability, EP impairments were specific to attentional processes and SAD impairments likely relate to negative self-monitoring. Self-report, as opposed to performance-based EF, provided best capacity to predict disability. These findings contribute to transdiagnostic circuitry models and intervention strategies.
The proline–arginine repeat protein linked to C9-ALS/FTD causes neuronal toxicity by inhibiting the DEAD-box RNA helicase-mediated ribosome biogenesis
Authors: Suzuki Hiroaki , Shibagaki Yoshio , Hattori Seisuke , Matsuoka Masaaki 
Published: September 2018

AbstractA GGGGCC repeat expansion in the C9ORF72 gene has been identified as the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The repeat expansion undergoes unconventional translation to produce dipeptide repeat (DPR) proteins. Although it has been reported that DPR proteins cause neurotoxicity, the underlying mechanism has not been fully elucidated. In this study, we have first confirmed that proline–arginine repeat protein (poly-PR) reduces levels of ribosomal RNA and causes neurotoxicity and found that the poly-PR-induced neurotoxicity is repressed by the acceleration of ribosomal RNA synthesis. These results suggest that the poly-PR-induced inhibition of ribosome biogenesis contributes to the poly-PR-induced neurotoxicity. We have further identified DEAD-box RNA helicases as poly-PR-binding proteins, the functions of which are inhibited by poly-PR. The enforced reduction in the expression of DEAD-box RNA helicases causes impairment of ribosome biogenesis and neuronal cell death. These results together suggest that poly-PR causes neurotoxicity by inhibiting the DEAD-box RNA helicase-mediated ribosome biogenesis.