bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Observing System Simulation Experiment for Ocean State Estimation to Assess the Performance of the SWOT Mission: Part 1—A Twin Experiment
Authors: Li Zhijin , Wang Jinbo , Fu Lee‐Lueng 
Published: July 2019

AbstractThe Surface Water Ocean Topography (SWOT) satellite mission is planned for launch in 2021. It will use the technique of radar interferometry to measure sea surface height over a 120‐km‐wide swath with a 20‐km gap around the satellite's nadir track. The oceanographic objectives of the mission are to study ocean circulation at scales down to 15 km. To prepare for the evaluation of the mission's performance, we are undertaking a series of studies to explore the efficacy of an assimilative high‐resolution modeling system for estimating the state of the ocean based on independent observations from both spaceborne and in situ measurements. The system is based on the heritage of a multiscale approach to data assimilation by the Regional Ocean Modeling System. Observing System Simulation Experiments were first conducted in the setup of an identical twin experiment to assess the system's performance near the calibration/validation site of SWOT off the coast of California. The system was applied to a nested model domain with 1‐km resolution. Simulated satellite observations of SSH, sea surface temperature, salinity, in situ observations of upper ocean temperature, and salinity by profiling floats and a dedicated notional array of station‐keeping gliders were assimilated by the system. The results indicate that such an observing system can accurately estimate the state of the ocean, and in particular SSH for the evaluation of SWOT performance.
The Unusual Thermophysical and Surface Properties of the Daedalia Planum Lava Flows
Authors: Simurda C. M. , Ramsey M. S. , Crown D. A. 
Published: July 2019

AbstractDaedalia Planum contains numerous young lava flows with diverse flow morphology. Previous thermal infrared studies avoided this region because of the moderately high visible albedo, assumed to be caused by optically thick dust, and overall low thermal inertia. The Daedalia Planum flows, however, have some of the roughest surfaces on Mars and display an unusual thermophysical behavior that most likely indicates different areal percentages of dust, sand, and lava outcrops. Recent studies suggest that these surfaces contain significant proportions of lava outcrops rising above low‐lying regions of sand with a spatially discontinuous dust layer. A multi‐instrument, multispectral approach combined with prior morphological mapping is applied here to discriminate between individual flows and determine the variation of thermophysical units on the surface. High‐resolution ConTeXt Camera and High‐Resolution Imaging Science Experiment data are used to investigate the flow surfaces and degree of mantling. Thermal Emission Imaging System and Thermal Emission Spectrometer thermal infrared data are analyzed to quantify the thermophysical variations between flows, identify surfaces with minimally mantled lava outcrops, and apply a thermophysical classification to differentiate the surface units. The results demonstrate that the observed thermal variations are due to different distributions of blocky lavas and sand infill. A majority of lava flows with rough surfaces display a diurnal and thermal inertia response indicative of a larger areal percentage of those outcrops versus that of sand and dust. This approach identifies surfaces with more exposed lava outcrops, promising targets for future composition analysis, in regions previously thought to be too dusty for such studies using thermal infrared data.
Quantifying Soil Phosphorus Dynamics: A Data Assimilation Approach
Authors: Hou Enqing , Lu Xingjie , Jiang Lifen , Wen Dazhi , Luo Yiqi 
Published: July 2019

AbstractThe dynamics of soil phosphorus (P) control its bioavailability. Yet it remains a challenge to quantify soil P dynamics. Here we developed a soil P dynamics (SPD) model. We then assimilated eight data sets of 426‐day changes in Hedley P fractions into the SPD model, to quantify the dynamics of six major P pools in eight soil samples that are representative of a wide type of soils. The performance of our SPD model was better for labile P, secondary mineral P, and occluded P than for nonoccluded organic P (Po) and primary mineral P. All parameters describing soil P dynamics were approximately constrained by the data sets. The average turnover rates were labile P 0.040 g g−1 day−1, nonoccluded Po 0.051 g g−1 day−1, secondary mineral P 0.023 g g−1 day−1, primary mineral P 0.00088 g g−1 day−1, occluded Po 0.0066 g g−1 day−1, and occluded inorganic P 0.0065 g g−1 day−1, in the greenhouse environment studied. Labile P was transferred on average more to nonoccluded Po (transfer coefficient of 0.42) and secondary mineral P (0.38) than to plants (0.20). Soil pH and organic C concentration were the key soil properties regulating the competition for P between plants and soil secondary minerals. The turnover rate of labile P was positively correlated with that of nonoccluded Po and secondary mineral P. The pool size of labile P was most sensitive to its turnover rate. Overall, we suggest data assimilation can contribute significantly to an improved understanding of soil P dynamics.
Next‐Generation Sequencing to Identify Lacustrine Haptophytes in the Canadian Prairies: Significance for Temperature Proxy Applications
Authors: Plancq Julien , Couto Jillian M. , Ijaz Umer Z. , Leavitt Peter R. , Toney Jaime L. 
Published: July 2019

AbstractThe Great Plains of North America often experience prolonged droughts that have major economic and environmental impacts. Temperature reconstructions are thus crucial to help decipher the mechanisms responsible for drought occurrences. Long‐chain alkenones (LCAs), lipids produced by three major phylogenetic groups (Groups I, II, and III) of haptophyte algae within the order Isochrysidales, are increasingly used for temperature reconstructions in lacustrine settings. However, to select the most appropriate calibration of the LCA‐based temperature proxy, it is first essential to identify the LCA‐producing haptophyte species present. Here we used next‐generation sequencing to target the 18S rRNA haptophyte gene from sediments with distinct LCA profiles to identify the LCA‐producer(s) from five Canadian prairie lakes. In total, 374 operational taxonomic units (OTUs) were identified across the studied samples, of which 234 fell within the Phylum Haptophyta. Among the most abundant OTUs, three were characterized as LCA‐producers, one falling within the Group I haptophytes and two within the Group II haptophytes. The OTU from Group I haptophytes was associated with a single, highly specific LCA profile, whereas Group II OTUs showed higher variability in LCA distributions. Our study revealed that most of the LCA‐producing OTUs thriving in the Canadian lakes are included within the genus Isochrysis, which helps guide selection of the most appropriate calibration for down‐core temperature reconstructions. Our findings also suggest that the temperature dependency is likely consistent within different taxa from Group I and Group II haptophytes, but that other environmental parameters may influence the accuracy of the calibration.
Improving Representation of Deforestation Effects on Evapotranspiration in the E3SM Land Model
Authors: Cai Xitian , Riley William J. , Zhu Qing , Tang Jinyun , Zeng Zhenzhong , Bisht Gautam , Randerson James T. 
Published: July 2019

AbstractEvapotranspiration (ET) plays an important role in land‐atmosphere coupling of energy, water, and carbon cycles. Following deforestation, ET is typically observed to decrease substantially as a consequence of decreases in leaf area and roots and increases in runoff. Changes in ET (latent heat flux) revise the surface energy and water budgets, which further affects large‐scale atmospheric dynamics and feeds back positively or negatively to long‐term forest sustainability. In this study, we used observations from a recent synthesis of 29 pairs of adjacent intact and deforested FLUXNET sites to improve model parameterization of stomatal characteristics, photosynthesis, and soil water dynamics in version 1 of the Energy Exascale Earth System Model (E3SM) Land Model (ELMv1). We found that default ELMv1 predicts an increase in ET after deforestation, likely leading to incorrect estimates of the effects of deforestation on land‐atmosphere coupling. The calibrated model accurately represented the FLUXNET observed deforestation effects on ET. Importantly, the search for global optimal parameters converged at values consistent with recent observational syntheses, confirming the reliability of the calibrated physical parameters. Applying this improved model parameterization to the globe scale reduced the bias of annual ET simulation by up to ~600 mm/year. Analysis on the roles of parameters suggested that future model development to improve ET simulation should focus on stomatal resistance and soil water‐related parameterizations. Finally, our predicted differences in seasonal ET changes from deforestation are large enough to substantially affect land‐atmosphere coupling and should be considered in such studies.
Are U‐Th Dates Correlated With Historical Records of Earthquakes? Constraints From Coseismic Carbonate Veins Within the North Anatolian Fault Zone
Authors: Karabacak Volkan , Uysal I. Tonguç , Mutlu Halim , Ünal‐İmer Ezgi , Dirik R. Kadir , Feng Yue‐xing , Akıska Sinan , Aydoğdu İsmail , Zhao Jian‐xin 
Published: July 2019

AbstractU‐Th dating of carbonate veins in connection with active tectonics has recently been used as an attractive tool for constraining the absolute timing of late Quaternary crustal deformations. In this study, for the first time we correlate U‐Th ages of travertine deposits in coseismic fissures along the North Anatolian Fault Zone with records of paleoseismological studies supported by historical earthquake catalogued data. U‐Th ages are assessed in relation to the recurrence interval and the size and epicenter distance of major Holocene earthquakes. Our statistical evaluations on age correlations indicate that the carbonate vein precipitation is concentrated in eight different periods along the North Anatolian Fault Zone. The periods are well correlated with historical earthquake records and with previous dating results of the nearby trench studies. At least six of the periods correspond to the earthquakes reported in the historical catalogues. The age correlations of carbonate precipitation intervals for the last millennium show a recurrence along the eastern North Anatolian Fault Zone with a mode at 130–330 years that is consistent with a previously proposed paleoseismic recurrence interval of the fault. Recorded events in carbonate veins indicate a close‐epicenter (d< 200 km) and high‐intensity (I > VI) paleoearthquakes. Our results suggest that coseismic carbonate veins could be used to determine paleoseismic records as a supplementary tool to augment paleoseismological techniques. This tool has advantages over traditional paleoseismological methods for the understanding of long‐term earthquake behavior, particularly for prehistoric late Pleistocene events which cannot be dated easily by traditional paleoseismological methods.
Contrasting Response of Precipitation to Aerosol Perturbation in the Tropics and Extratropics Explained by Energy Budget Considerations
Authors: Dagan Guy , Stier Philip , Watson‐Parris Duncan 
Published: July 2019

AbstractPrecipitation plays a crucial role in the Earth's energy balance, the water cycle, and the global atmospheric circulation. Aerosols, by direct interaction with radiation and by serving as cloud condensation nuclei, may affect clouds and rain formation. This effect can be examined in terms of energetic constraints, that is, any aerosol‐driven diabatic heating/cooling of the atmosphere will have to be balanced by changes in precipitation, radiative fluxes, or divergence of dry static energy. Using an aqua‐planet general circulation model (GCM), we show that tropical and extratropical precipitation have contrasting responses to aerosol perturbations. This behavior can be explained by contrasting ability of the atmosphere to diverge excess dry static energy in the two different regions. It is shown that atmospheric heating in the tropics leads to large‐scale thermally driven circulation and a large increase in precipitation, while the excess energy from heating in the extratropics is constrained due to the effect of the Coriolis force, causing the precipitation to decrease.
Investigation on the Variability of the Geomagnetic Daily Current During Sudden Stratospheric Warmings
Authors: Owolabi Charles , Lei Jiuhou , Bolaji O. S. , Jimoh Oluwaseyi , Ruan Haibing , Li Na , Niu Xiaojuan , Yoshikawa Akimasa 
Published: July 2019

AbstractThe magnetic field records of the magnetometer networks in the American, East Asian‐Australian, and European‐African sectors were employed in this present work. We used them to investigate equatorial electrojet (EEJ), counter electrojet (CEJ), tidal variability in EEJ strength and ionospheric current during the 2005/2006 and 2008/2009 sudden stratospheric warming (SSW) events. In addition to the well‐investigated tidal variability in EEJ strength over the American and East Asian sectors, we investigated that of the African sector for the first time. Interestingly, the tidal components in EEJ strength during both SSW events clearly exhibit marked longitudinal differences with high, moderate, and low amplitudes in the American, East Asian, and African sectors, respectively. An exception found around day 71 in the African sector after the 2008/2009 SSW event had higher solar diurnal tidal component as compared to that of the Asian sector. Over the American sector, solar and lunar semidiurnal tides were strongly associated with CEJ current during both SSW events, whereas at the African and East Asian sectors such variabilities are not evident. A solar diurnal tidal component was strongly related to a reduction in the EEJ strength over the East Asian sector. In addition, a prolonged period of CEJ occurrence that begins during the SSW precondition and ends when the SSW was evolving characterized the African sector during both SSW events. There is a steady shift in phase at later hours when both SSW events are evolving.
The Connected Isotopic Water Cycle in the Community Earth System Model Version 1
Authors: Brady E. , Stevenson S. , Bailey D. , Liu Z. , Noone D. , Nusbaumer J. , Otto‐Bliesner B. L. , Tabor C. , Tomas R. , Wong T. , Zhang J. , Zhu J. 
Published: July 2019

AbstractBecause of the pervasive role of water in the Earth system, the relative abundances of stable isotopologues of water are valuable for understanding atmospheric, oceanic, and biospheric processes, and for interpreting paleoclimate proxy reconstructions. Isotopologues are transported by both large‐scale and turbulent flows, and the ratio of heavy to light isotopologues changes due to fractionation that can accompany condensation and evaporation processes. Correctly predicting the isotopic distributions requires resolving the relationships between large‐scale ocean and atmospheric circulation and smaller‐scale hydrological processes, which can be accomplished within a coupled climate modeling framework. Here we present the water isotope‐enabled version of the Community Earth System Model version 1 (iCESM1), which simulates global variations in water isotopic ratios in the atmosphere, land, ocean, and sea ice. In a transient Last Millennium simulation covering the 850–2005 period, iCESM1 correctly captures the late‐twentieth‐century structure of δ18O and δD over the global oceans, with more limited accuracy over land. The relationship between salinity and seawater δ18O is also well represented over the observational period, including interbasin variations. We illustrate the utility of coupled, isotope‐enabled simulations using both Last Millennium simulations and freshwater hosing experiments with iCESM1. Closing the isotopic mass balance between all components of the coupled model provides new confidence in the underlying depiction of the water cycle in CESM, while also highlighting areas where the underlying hydrologic balance can be improved. The iCESM1 is poised to be a vital community resource for ongoing model development with both modern and paleoclimate applications.
Universal perpendicular orientation of block copolymer microdomains using a filtered plasma
Authors: Oh Jinwoo , Suh Hyo Seon , Ko Youngpyo , Nah Yoonseo , Lee Jong-Chan , Yeom Bongjun , Char Kookheon , Ross Caroline A. , Son Jeong Gon 
Published: July 2019

AbstractSub-10 nm patterns prepared by directed self-assembly (DSA) of block copolymer (BCP) thin films offer a breakthrough method to overcome the limitations of photolithography. Perpendicular orientation of the BCP nanostructures is essential for lithographic applications, but dissimilar surface/interfacial energies of two blocks generally favour parallel orientations, so that the perpendicular orientation could only be obtained under very limited conditions. Here, we introduce a generalized method for creating perpendicular orientations by filtered plasma treatment of the BCP films. By cross-linking the surface of disordered BCP films using only physical collisions of neutral species without ion bombardment or UV irradiation, neutral layers consistent with the BCP volume fraction are produced that promote the perpendicular orientations. This method works with BCPs of various types, volume fractions, and molecular weights individually at the top and bottom interfaces, so it was applied to orientation-controlled 3D multilayer structures and DSA processes for sub-10 nm line-spacing patterns.
Untwisted restacking of two-dimensional metal-organic framework nanosheets for highly selective isomer separations
Authors: Tao Ze-Rong , Wu Jian-Xiang , Zhao Ying-Jie , Xu Ming , Tang Wen-Qi , Zhang Qing-Hua , Gu Lin , Liu Da-Huan , Gu Zhi-Yuan 
Published: July 2019

AbstractThe stacking between nanosheets is an intriguing and inevitable phenomenon in the chemistry of nano-interfaces. Two-dimensional metal-organic framework nanosheets are an emerging type of nanosheets with ultrathin and porous features, which have high potential in separation applications. Here, the stacking between single-layer metal-organic framework nanosheets is revealed to show three representative conformations with tilted angles of 8°, 14°, and 30° for Zr-1, 3, 5-(4-carboxylphenyl)-benzene framework as an example. Efficient untwisted stacking strategy by simple heating is proposed. A detailed structural analysis of stacking modes reveals the creation of highly ordered sub-nanometer micropores in the interspacing of untwisted nano-layers, yielding a high-resolution separator for the pair of para-/meta-isomers over the twisted counterparts and commercial HP-5MS and VF-WAXMS columns. This general method is proven by additional nanosheet examples and supported by Grand Canonical Monte Carlo simulation. This finding will provide a synthetic route in the rational design of functionalities in two-dimensional metal-organic framework nanosheet.
Fokker-Planck analysis of optical near-field traps
Authors: Zaman Mohammad Asif , Padhy Punnag , Hesselink Lambertus 
Published: July 2019

AbstractThe motion of a nanoparticle in the vicinity of a near-field optical trap is modeled using the Fokker-Planck equation. A plasmonic C-shaped engraving on a gold film is considered as the optical trap. The time evolution of the position probability density of the nanoparticle is calculated to analyze the trapping dynamics. A spatially varying diffusion tensor is used in the formulation to take into account the hydrodynamic interactions. The steady-state position distribution obtained from the Fokker-Planck equation is compared with experimental results and found to be in good agreement. Computational cost of the proposed method is compared with the conventionally used Langevin equation based approach. The proposed method is found to be computationally efficient (requiring 35 times less computation time) and scalable to more complex lab-on-a-chip systems.
Stargazin and γ4 slow the channel opening and closing rates of GluA4 AMPA receptors
Authors: Pierce Vincen D. , Niu Li 
Published: July 2019

AbstractAs auxiliary subunits, transmembrane AMPA receptor regulatory proteins (TARPs) are known to enhance macroscopic current amplitude and alter kinetic properties of AMPA receptors on slow time scale, such as desensitization rate. Whether TARPs affect the rate of AMPA channel opening and closing, however, remains elusive. Using a laser-pulse photolysis technique, we investigated the effect of γ-2 (stargazin, a type 1a TARP) and γ-4 (a type 1b TARP) on the channel-opening and channel-closing rate constants (i.e., kop and kcl) of GluA4 homomeric channels. We found both TARPs slow the kop and kcl by 4-fold and 3-fold, respectively, without appreciable change of channel-opening probability, as compared with GluA4 channel alone. On the other hand, γ-4 has a stronger effect on slowing the channel desensitization rate than γ-2; yet, γ-2 causes a much more pronounced left shift of the dose-response relationship by increasing its affinity towards glutamate than γ-4. Our study shows that on the faster time scale, the major impact of TARP association with GluA4 is to lengthen the lifetime of the open channel, which is slow to form, to allow a larger charge transfer through the open channel that closes more slowly, without appreciable change of channel opening probability.
Nicotinamide riboside promotes autolysosome clearance in preventing doxorubicin-induced cardiotoxicity
Authors: Zheng Dong , Zhang Yi , Zheng Ming , Cao Ting , Wang Grace , Zhang Lulu , Ni Rui , Brockman Joseph , Zhong Huiting , Fan Guo-Chang , Peng Tianqing 
Published: July 2019

Abstract
Doxorubicin (DOX) is widely used as a first-line chemotherapeutic drug for various malignancies. However, DOX causes severe cardiotoxicity, which limits its clinical uses. Oxidative stress is one of major contributors to DOX-induced cardiotoxicity. While autophagic flux serves as an important defense mechanism against oxidative stress in cardiomyocytes, recent studies have demonstrated that DOX induces the blockage of autophagic flux, which contributes to DOX cardiotoxicity. The present study investigated whether nicotinamide riboside (NR), a precursor of nicotinamide adenine dinucleotide (NAD)+, prevents DOX cardiotoxicity by improving autophagic flux. We report that administration of NR elevated NAD+ levels, and reduced cardiac injury and myocardial dysfunction in DOX-injected mice. These protective effects of NR were recapitulated in cultured cardiomyocytes upon DOX treatment. Mechanistically, NR prevented the blockage of autophagic flux, accumulation of autolysosomes, and oxidative stress in DOX-treated cardiomyocytes, the effects of which were associated with restoration of lysosomal acidification. Furthermore, inhibition of lysosomal acidification or SIRT1 abrogated these protective effects of NR during DOX-induced cardiotoxicity. Collectively, our study shows that NR enhances autolysosome clearance via the NAD+/SIRT1 signaling, thereby preventing DOX-triggered cardiotoxicity.