bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Resolution Terrain Analysis for Lander Safety Landing and Rover Path Planning Based on Lunar Reconnaissance Orbiter Narrow Angle Camera Images: A Case Study of China's Chang'e‐4 Probe
Authors: Li Bo , Yue Zongyu , Zhang Jiang , Fu Xiaohui , Ling Zongcheng , Chen Shengbo , Chen Jian , Yao Peiwen 
Published: February 2019

AbstractChina's Chang'e‐4 (CE‐4) probe will explore the South Pole‐Aitken basin in late 2018. Its preselected landing area is located on the southeastern floor of the Von Kármán crater. Landing experience of China's Chang'e‐3 probe may not be applied to CE‐4 mission directly because the topography of lunar farside is more rugged. Moreover, due to scale dependence and smooth effects, the previous topographic studies derived from digital elevation model data with lower resolution cannot represent the meter‐scale topographic features. Because of low time and space complexities in lunar images, image segmentation algorithm is especially suitable for recognizing lunar features. We divided the narrow angle camera (NAC) mosaic image into three parts: dark area, bright area, and flat area, based on a double‐threshold Otsu method. The first two parts corresponded to the undulating areas (positive and negative terrains). And then we calculated the flat area percentage (Fap) of the previous successful lunar landing missions (including Chang'e‐3, Apollo, Surveyor, and Luna series) and obtained the Fap threshold (>0.6) for lunar safe landing. According to Fap map (~1.5 m per pixel) of CE‐4 preselected landing area, the divided square grids with a size of 0.01° can be classified into safe grids (Fap > 0.6) and unsafe grids (Fap ≤ 0.6). The CE‐4 preselected landing areas can be greatly reduced to five potential landing areas. In the last, we proposed a route planning method, which took both the distance and security into account, for CE‐4 rover to dynamically generate a safe and short route between current grid and target grid.
Quantifying Flood Vulnerability Reduction via Private Precaution
Authors: Sairam Nivedita , Schröter Kai , Lüdtke Stefan , Merz Bruno , Kreibich Heidi 
Published: February 2019

AbstractPrivate precaution is an important component in contemporary flood risk management and climate adaptation. However, quantitative knowledge about vulnerability reduction via private precautionary measures is scarce and their effects are hardly considered in loss modeling and risk assessments. However, this is a prerequisite to enable temporally dynamic flood damage and risk modeling, and thus the evaluation of risk management and adaptation strategies. To quantify the average reduction in vulnerability of residential buildings via private precaution empirical vulnerability data (n = 948) is used. Households with and without precautionary measures undertaken before the flood event are classified into treatment and nontreatment groups and matched. Postmatching regression is used to quantify the treatment effect. Additionally, we test state‐of‐the‐art flood loss models regarding their capability to capture this difference in vulnerability. The estimated average treatment effect of implementing private precaution is between 11 and 15 thousand EUR per household, confirming the significant effectiveness of private precautionary measures in reducing flood vulnerability. From all tested flood loss models, the expert Bayesian network‐based model BN‐FLEMOps and the rule‐based loss model FLEMOps perform best in capturing the difference in vulnerability due to private precaution. Thus, the use of such loss models is suggested for flood risk assessments to effectively support evaluations and decision making for adaptable flood risk management.
Hydroxylamine as a Potential Indicator of Nitrification in the Open Ocean
Authors: Korth Frederike , Kock Annette , Arévalo‐Martínez Damian L. , Bange Hermann W. 
Published: February 2019

AbstractHydroxylamine (NH2OH), a short‐lived intermediate in the nitrogen cycle, is a potential precursor of nitrous oxide (N2O) in the ocean. However, measurements of NH2OH in the ocean are sparse. Here we present a data set of depth profiles of NH2OH from the equatorial Atlantic Ocean and the eastern tropical South Pacific and compare it to N2O, nitrate, and nitrite profiles under varying oxygen conditions. The presence of NH2OH in surface waters points toward surface nitrification in the upper 100 m. Overall, we found a ratio of 1:3 between NH2OH and N2O in open ocean areas when oxygen concentrations were >50 μmol/L. In the equatorial Atlantic Ocean and the open ocean eastern tropical South Pacific, where nitrification is the dominant N2O production pathway, stepwise multiple regressions demonstrated that N2O, NH2OH, and nitrate concentrations were highly correlated, suggesting that NH2OH is a potential indicator for nitrification.
Pacific Ocean Variability Influences the Time of Emergence of a Seasonally Ice‐Free Arctic Ocean
Authors: Screen J. A. , Deser C. 
Published: February 2019

AbstractThe Arctic Ocean is projected to become seasonally ice‐free before midcentury unless greenhouse gas emissions are rapidly reduced, but exactly when this could occur depends considerably on internal climate variability. Here we show that trajectories to an ice‐free Arctic are modulated by concomitant shifts in the Interdecadal Pacific Oscillation (IPO). Trajectories starting in the negative IPO phase become ice‐free 7 years sooner than those starting in the positive IPO phase. Trajectories starting in the negative IPO phase subsequently transition toward the positive IPO phase, on average, with an associated strengthening of the Aleutian Low, increased poleward energy transport, and faster sea‐ice loss. The observed IPO began to transition away from its negative phase in the past few years. If this shift continues, our results suggest increased likelihood of accelerated sea‐ice loss over the coming decades, and an increased risk of an ice‐free Arctic within the next 20–30 years.
Wave Activity in Jupiter's North Equatorial Belt From Near‐Infrared Reflectivity Observations
Authors: Giles Rohini S. , Orton Glenn S. , Stephens Andrew W. , Wong Michael H. , Irwin Patrick G. J. , Sinclair James A. , Tabataba‐Vakili Fachreddin 
Published: February 2019

AbstractHigh spatial resolution images of Jupiter at 1.58–2.28 μm are used to track and characterize a wave pattern observed in 2017 at a planetocentric latitude of 14°N. The wave pattern has a wave number of 18 and spans ∼5° in latitude. One bright crest remains stationary in System III longitude, while the remaining crests move slowly westward. The bright and dark regions of the near‐infrared wave pattern are caused by variations in the vertical location of the upper tropospheric haze layer. A comparison with thermal infrared observations shows a correlation with temperature anomalies in the upper troposphere. The results are consistent with a Rossby wave, generated by flow around a stationary vortex.
Inferring Source Properties of Monoenergetic Electron Precipitation From Kappa and Maxwellian Moment‐Voltage Relationships
Authors: Hatch Spencer M. , LaBelle James , Chaston Christopher C. 
Published: February 2019

AbstractWe present two case studies of FAST electrostatic analyzer measurements of both highly nonthermal (
2.5) and weakly nonthermal/thermal monoenergetic electron precipitation at ∼4,000 km, from which we infer the properties of the magnetospheric source distributions via comparison of experimentally determined number density‐, current density‐, and energy flux‐voltage relationships with corresponding theoretical relationships. We also discuss the properties of the two new theoretical number density‐voltage relationships that we employ. Moment uncertainties, which are calculated analytically via application of the Gershman et al. (2015, https://doi.org/10.1002/2014JA020775) moment uncertainty framework, are used in Monte Carlo simulations to infer ranges of magnetospheric source population densities, temperatures, κ values, and altitudes. We identify the most likely ranges of source parameters by requiring that the range of κ values inferred from fitting experimental moment‐voltage relationships correspond to the range of κ values inferred from directly fitting observed electron distributions with two‐dimensional kappa distribution functions. Observations in the first case study, which are made over ∼78–79° invariant latitude in the Northern Hemisphere and 4.5–5.5 magnetic local time, are consistent with a magnetospheric source population density nm= 0.7–0.8 cm−3, source temperature Tm≈ 70 eV, source altitude h= 6.4–7.7 RE, and κ= 2.2–2.8. Observations in the second case study, which are made over 76–79° invariant latitude in the Southern Hemisphere and ∼21 magnetic local time, are consistent with a magnetospheric source population density nm= 0.07–0.09 cm−3, source temperature Tm≈ 95 eV, source altitude
6 RE, and κ= 2–6.
Rupture of the Indian Slab in the 2011 Mw 6.9 Sikkim Himalaya Earthquake and Its Tectonic Implications
Authors: Sunilkumar T. C. , Earnest Anil , Silpa K. , Andrews Ronia 
Published: February 2019

AbstractUnlike the other Himalayan plate boundary segments, the eastern Nepal to Bhutan Himalayan region is not known to have generated prominent shallow thrust faulting earthquakes, typical of the ongoing convergence. This region features strike‐slip earthquakes over the depth ranges of 40–120 km, indicating intraslab deformation. Here we present for the first time a slip distribution model for the largest recorded intraslab strike‐slip earthquake in this region, the Mw 6.9 Sikkim event that occurred on 18 September 2011. Relying on kinematic source process modeling, our results indicate a NE‐SW trending, steeply dipping sinistral source zone within the underthrusting Indian slab. The rupture propagated radially, with a low rupture velocity of 1.7 km/s, breaking a large asperity of 20 × 20 km2 with a maximum slip of 1.6 m. The rupture nucleated at a depth of 45 km and reached upper mantle depths. The computed coseismic stress drop value is 13.6 MPa. We suggest that most of the aftershocks occurred on the conjugate plane, possibly due to stress triggering. Stress inversion of focal mechanisms indicates a transpressive stress regime throughout the crust and pure strike‐slip regime in the upper mantle. We observed a unimodal distribution of earthquakes beneath the Higher Himalaya. This indicates a strong, brittle Indian slab and unravels a scenario of an eventual breakup of the lithosphere; the key trigger might be variation in the convergence rates along the Himalayan arc.
Bio‐optical Properties of Surface Waters in the Atlantic Water Inflow Region off Spitsbergen (Arctic Ocean)
Authors: Kowalczuk Piotr , Sagan Sławomir , Makarewicz Anna , Meler Justyna , Borzycka Karolina , Zabłocka Monika , Zdun Agnieszka , Konik Marta , Darecki Mirosław , Granskog Mats A. , Pavlov Alexey K. 
Published: February 2019

AbstractBio‐optical properties of surface waters were characterized off western and northern Spitsbergen in the summers of 2013, 2014, and 2015. We observed statistically significant year‐to‐year differences in spatial distribution of spectral absorption (a(λ)) and beam attenuation (c(λ)). Highest a(λ) and c(λ) were located in the frontal zone between water masses and co‐varied strongly with chlorophyll a fluorescence. Phytoplankton pigments dominated the absorption budget at 443 nm (50%). The contribution of chromophoric dissolved organic matter to total nonwater absorption was highest at 412 nm (42%), and detrital absorption contributed most at 550 nm (37%). Almost all inherent optical properties, except chromophoric dissolved organic matter, were highly correlated with the chlorophyll a concentration (Chla, R2 > 0.81). Relationships between Chla and the particulate and phytoplankton pigments absorption coefficients at 443 and 676 nm were characterized by significant determination coefficients (R2 > 0.73). The phytoplankton pigments line height absorption aLH(676) was found to be the most reliable optical proxy for determination of Chla, compared to total nonwater absorption, apg(676), and stimulated in situ chlorophyll a fluorescence intensity, IChla. In the presence of sea ice melt the water column was stratified and the vertical distribution of inherent optical properties was characterized by a surface minimum followed by a distinct subsurface maximum, aligned with a subsurface chlorophyll a maximum. We surmise that prevailing regional wind patterns affect sea ice and surface drift in central Fram Strait, and thus the location of sea ice meltwater, which affects the vertical stratification and occurrence of subsurface chlorophyll a maximum.
Downstream‐Propagating Channel Responses to Decadal‐Scale Climate Variability in a Glaciated River Basin
Authors: Anderson Scott W. , Konrad Chris P. 
Published: February 2019

AbstractRegional climate is an important control on the rate of coarse sediment mobilization and transport in alpine river systems. Changes in climate are then expected to cause a cascade of geomorphic responses, including adjustments in downstream channel morphology. However, the mechanics and sensitivity of channel response to short‐term climate variability remain poorly documented. In the Nooksack River, which drains a glaciated stratovolcano in Washington State, bed elevation changes were inferred from shifting stage‐discharge relations at seven U.S Geological Survey stream gages. Decadal‐scale elevation trends can be explained as a downstream‐propagating channel response to regional climate variability, where periods of persistent warm, dry (cool and wet) conditions corresponded to periods of aggradation (incision). The channel elevation response propagated downstream at a rate of 1 to 4 km per year; propagation rate scaled closely with channel slope. Historical trends in glacier extent and flood intensity both show some potential to explain climate‐sediment linkages, though assessing causation is complicated by the shared climate signal in both records. Results show the influence of the Pacific Decadal Oscillation, with relatively high coarse sediment yields prior to 1950 and since 1980, and notably lower sediment yields from 1950 to 1980. Measured sediment yields from nearby glaciated basins corroborate this history, suggesting a regional consistency to these climate‐sediment linkages. These results document consistent relations between climate, sediment supply, and downstream channel response at the basin scale, with channel responses propagating downstream over periods of decades with little apparent attenuation.
Experimenting With Frequency‐And‐Angular Sounding to Characterize Traveling Ionospheric Disturbances Using the LWA‐SV Radio Telescope and A DPS4D
Authors: Obenberger K. S. , Dao E. , Dowell J.D. 
Published: February 2019

AbstractHere we present near vertical angle of arrival and Doppler observations using a Digisonde Portable Sounder 4D (DPS4D) as a transmitter and the Long Wavelength Array at Sevilleta (LWA‐SV) radio telescope as a receiver, over an 80‐km baseline. With 256 dual‐polarization dipole antennas, LWA‐SV provides unparalleled sensitivity and angular resolution to high frequency sounding measurements of traveling ionospheric disturbances (TIDs). We conducted a study over 3 days in March 2018 and detected several TIDs ranging from 10‐ to 45‐min periods. These medium scale TIDs were detected using an implementation of frequency‐and‐angular sounding (FAS), which was first described in Beley et al. (1995, https://doi.org/10.1029/95RS01992). FAS assumes an ionospheric mirror model and provides estimates of the wavelength, direction, and speed of TIDs using the measured angle of arrival and Doppler of a high frequency ionospheric reflection. We experiment with this method and show that LWA‐SV is capable of achieving observations that are unmatched in sensitivity and resolution, allowing for measurements limited primarily by the errors accumulated by the assumptions within different manifestations of the FAS algorithm.
Using Color Coherence Vectors to Evaluate the Performance of Hydrologic Data Assimilation
Authors: Moslehi Mahsa , de Barros Felipe P. J. 
Published: February 2019

AbstractAn inadequate characterization of hydrogeological properties can significantly decrease the trustworthiness of subsurface flow and transport model predictions. A variety of data assimilation methods have been proposed in order to estimate hydrogeological parameters from spatially scarce data by incorporating them into the governing physical models. In order to quantify the accuracy of the estimations, several metrics have been used such as Rank Histograms, root‐mean‐square error (RMSE), and Ensemble Spread. However, these commonly used metrics do not regard the spatial correlation of the aquifer's properties. This can cause permeability fields with very different spatial structures to have similar histograms or RMSE. In this paper, we propose an approach based on color coherence vectors (CCV) for evaluating the performance of these estimation methods. CCV is a histogram‐based technique for comparing images that incorporate spatial information. We represent estimated fields as digital three‐channel images and use CCV to compare and quantify the accuracy of estimations. The appealing feature of this technique is that it considers the spatial structure embedded in the estimated fields. The sensitivity of CCV to spatial information makes it a suitable metric for assessing the performance of data assimilation techniques. Under various factors, such as numbers of measurements and structural parameters of the log conductivity field, we compare the performance of CCV with the RMSE.
Comparison of Contemporary In Situ, Model, and Satellite Remote Sensing Soil Moisture With a Focus on Drought Monitoring
Authors: Ford Trent W. , Quiring Steven M. 
Published: February 2019

AbstractSoil moisture is a key drought indicator; however, current in situ soil moisture infrastructure is inadequate for large‐scale drought monitoring. One initiative of the ongoing National Soil Moisture Network program is the development of a near real‐time drought monitoring product that integrates in situ, model, and satellite remote sensing data. Data integration from diverse sources requires large‐scale validation prior to integration. This study develops a framework for assessing the fidelity of in situ, model, and satellite soil moisture data sets. Here we evaluate data from over 100 in situ monitoring stations that are part of nine monitoring networks; North American Land Data Assimilation System Phase 2 and Climate Prediction Center land surface models; and Soil Moisture Active‐Passive, Soil Moisture and Ocean Salinity, and European Space Agency‐Climate Change Initiative (ESA‐CCI) satellite products. The results indicate the majority of in situ stations exhibit low error variance and are spatially representative; however, some networks and individual stations exhibit anomalously high error variance or are sited in a way that make them not spatially representative of a larger area. Overall, North American Land Data Assimilation System Phase 2 is the modeled product that consistently performed best, and Soil Moisture Active‐Passive L3 is the remotely sensed product that consistently performed the best. They were able to both capture in situ soil moisture variability and provide an accurate depiction of drought conditions. The methods and verification framework applied in this study can be used to evaluate any soil moisture data set in any region of the world.
A chemical approach for global protein knockdown from mice to non-human primates
Authors: Sun Xiuyun , Wang Jun , Yao Xia , Zheng Wen , Mao Yang , Lan Tianlong , Wang Liguo , Sun Yonghui , Zhang Xinyi , Zhao Qiuye , Zhao Jianguo , Xiao Rui-Ping , Zhang Xiuqin , Ji Guangju , Rao Yu 
Published: February 2019

AbstractAlthough conventional genetic modification approaches for protein knockdown work very successfully due to the increasing use of CRISPR/Cas9, effective techniques for achieving protein depletion in adult animals, especially in large animals such as non-human primates, are lacking. Here, we report a chemical approach based on PROTACs technology that efficiently and quickly knocks down FKBP12 (12-kDa FK506-binding) protein globally in vivo. Both intraperitoneal and oral administration led to rapid, robust, and reversible FKBP12 degradation in mice. The efficiency and practicality of this method were successfully demonstrated in both large and small animals (mice, rats, Bama pigs, and rhesus monkeys). Furthermore, we showed this approach can also be applied to effectively knockdown other target proteins such as Bruton's tyrosine kinase (BTK). This chemical protein knockdown strategy provides a powerful research tool for gene function studies in animals, particularly in large animals, for which gene-targeted knockout strategies may remain unfeasible.
Dynamics of the Bloch point in an asymmetric permalloy disk
Authors: Im Mi-Young , Han Hee-Sung , Jung Min-Seung , Yu Young-Sang , Lee Sooseok , Yoon Seongsoo , Chao Weilun , Fischer Peter , Hong Jung-Il , Lee Ki-Suk 
Published: February 2019

AbstractA Bloch point (BP) is a topological defect in a ferromagnet at which the local magnetization vanishes. With the difficulty of generating a stable BP in magnetic nanostructures, the intrinsic nature of a BP and its dynamic behaviour has not been verified experimentally. We report a realization of steady-state BPs embedded in deformed magnetic vortex cores in asymmetrically shaped Ni80Fe20 nanodisks. Time-resolved nanoscale magnetic X-ray imaging combined with micromagnetic simulation shows detailed dynamic character of BPs, revealing rigid and limited lateral movements under magnetic field pulses as well as its crucial role in vortex-core dynamics. Direct visualizations of magnetic structures disclose the unique dynamical feature of a BP as an atomic scale discrete spin texture and allude its influence on the neighbouring spin structures such as magnetic vortices.
Generation of pluripotent stem cell-derived mouse kidneys in Sall1-targeted anephric rats
Authors: Goto Teppei , Hara Hiromasa , Sanbo Makoto , Masaki Hideki , Sato Hideyuki , Yamaguchi Tomoyuki , Hochi Shinichi , Kobayashi Toshihiro , Nakauchi Hiromitsu , Hirabayashi Masumi 
Published: February 2019

AbstractRegeneration of human kidneys in animal models would help combat the severe shortage of donors in transplantation therapy. Previously, we demonstrated by interspecific blastocyst complementation between mouse and rats, generation of pluripotent stem cell (PSC)-derived functional pancreas, in apancreatic Pdx1 mutant mice. We, however, were unable to obtain rat PSC-derived kidneys in anephric Sall1 mutant mice, likely due to the poor contribution of rat PSCs to the mouse metanephric mesenchyme, a nephron progenitor. Here, conversely, we show that mouse PSCs can efficiently differentiate into the metanephric mesenchyme in rat, allowing the generation of mouse PSC-derived kidney in anephric Sall1 mutant rat. Glomerular epithelium and renal tubules in the kidneys are entirely composed of mouse PSC-derived cells expressing key functional markers. Importantly, the ureter-bladder junction is normally formed. These data provide proof-of-principle for interspecific blastocyst complementation as a viable approach for kidney generation.