bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Life on Climate Stabilization Over Different Timescales
Authors: Höning Dennis 
Published: September 2020

AbstractSurface life has been argued to be crucial in keeping a planet habitable in the long term. Biologically enhanced weathering compensates for increasing solar luminosity, and temperature‐dependent plant productivity weakens climate perturbations. Furthermore, a reduced calcification rate of marine organisms provides a negative feedback to rising atmospheric CO2. Here, I present a model of the long‐term carbon cycle including biological enhancement of weathering and marine calcification. Climate oscillations of periods from thousands to millions of years arise from a simple model of mountain uplift and erosion. I systematically study the influence of the biologically driven feedbacks on damping these oscillations. For oscillations of periods <2 Myr, the marine calcification feedback yields surface temperature amplitudes that are approximately 1/3 lower compared to a model that ignores this feedback. Abiotic oceans, however, would not necessarily imply a less stable climate on short timescales, due to a higher pH and thereby a higher buffer capacity. On longer timescales, the higher ocean pH would reduce climate stability, since the seafloor weathering feedback would work less efficiently. Biological enhancement of weathering helps stabilizing the climate against oscillations of periods >0.5 Myr. These findings are sensitive to the ratio of land to oceans, however. Furthermore, the mantle carbon degassing rate plays a role, since the temperature dependence of biological primary productivity may be smaller at higher temperatures. Altogether, life can be argued to stabilize the climate on timescales longer than some 100 kyr, while details depend on the geological state of the planet.
Proton Properties in Mercury's Magnetotail: A Statistical Study
Authors: Zhao J.‐T. , Zong Q.‐G. , Slavin J. A. , Sun W.‐J. , Zhou X.‐Z. , Yue C. , Raines J. M. , Ip W.‐H. 
Published: September 2020

AbstractThis study investigates the properties of protons in the magnetotail plasma sheet of Mercury. By superposing 5‐year measurements from the MESSENGER spacecraft, we obtain the average energy spectrum of protons in the plasma sheet, which can be fitted nicely by the Gaussian‐Kappa model. The proton density, pressure, and energy spectral index κ are found to be higher on the dawnside than on the duskside. The proton temperature shows a clearly outward radial gradient. The field‐aligned density profile indicates that the protons in the outer plasma sheet move adiabatically. The pitch angle distribution reveals the reflected fluxes to be always less than the incident fluxes and indicates the loss of protons due to their impact on the planetary surface.
Glacier Loss Impacts Riverine Organic Carbon Transport to the Ocean
Authors: Hood Eran , Fellman Jason B. , Spencer Robert G. M. 
Published: September 2020

AbstractLateral transport of organic carbon (OC) to the coastal ocean is an important component of the global carbon cycle because rivers transport, mineralize, and bury significant amounts of OC. Glaciers drive water and sediment export from many high‐elevation and high‐latitude ecosystems, yet their role in watershed OC balances is poorly understood, particularly with regard to particulate OC. Here, we evaluate seasonal water, sediment, and comprehensive OC budgets, including both dissolved and particulate forms, for three watersheds in southeast Alaska that vary in glacier coverage. We show that glacier loss will shift the dominant size fraction of riverine OC from particulate toward dissolved and potentially alter the provenance of particulate OC. Glacier coverage also controls whether OC export is source (C stock) or transport (runoff) limited at the watershed scale. These findings provide insight into the future trajectory of riverine OC export in glacierized regions.
Is Coulomb Stress the Best Choice for Aftershock Forecasting?
Authors: Sharma Shubham , Hainzl Sebastian , Zöeller Gert , Holschneider Matthias 
Published: September 2020

AbstractThe Coulomb failure stress (CFS) criterion is the most commonly used method for predicting spatial distributions of aftershocks following large earthquakes. However, large uncertainties are always associated with the calculation of Coulomb stress change. The uncertainties mainly arise due to nonunique slip inversions and unknown receiver faults; especially for the latter, results are highly dependent on the choice of the assumed receiver mechanism. Based on binary tests (aftershocks yes/no), recent studies suggest that alternative stress quantities, a distance‐slip probabilistic model as well as deep neural network (DNN) approaches, all are superior to CFS with predefined receiver mechanism. To challenge this conclusion, which might have large implications, we use 289 slip inversions from SRCMOD database to calculate more realistic CFS values for a layered half‐space and variable receiver mechanisms. We also analyze the effect of the magnitude cutoff, grid size variation, and aftershock duration to verify the use of receiver operating characteristic (ROC) analysis for the ranking of stress metrics. The observations suggest that introducing a layered half‐space does not improve the stress maps and ROC curves. However, results significantly improve for larger aftershocks and shorter time periods but without changing the ranking. We also go beyond binary testing and apply alternative statistics to test the ability to estimate aftershock numbers, which confirm that simple stress metrics perform better than the classic Coulomb failure stress calculations and are also better than the distance‐slip probabilistic model.
Simulation of Topography Effects on Rockfall‐Generated Seismic Signals: Application to Piton de la Fournaise Volcano
Authors: Kuehnert J. , Mangeney A. , Capdeville Y. , Métaxian J. P. , Bonilla L. F. , Stutzmann E. , Chaljub E. , Boissier P. , Brunet C. , Kowalski P. , Lauret F. , Hibert C. 
Published: September 2020

AbstractSeismic waves generated by rockfalls contain valuable information on the properties of these events. However, as rockfalls mainly occur in mountainous regions, the generated seismic waves can be affected by strong surface topography variations. We present a methodology for investigating the influence of topography using a Spectral‐Element‐based simulation of 3‐D wave propagation in various geological media. This methodology is applied here to Dolomieu crater on the Piton de la Fournaise volcano, Reunion Island, but it can be used for other sites, taking into account local topography and medium properties. The complexity of wave fields generated by single‐point forces is analyzed for different velocity models and topographies. Ground‐motion amplification is studied relative to flat reference models, showing that Peak Ground Velocity (PGV) and total kinetic energy can be amplified by factors of up to 10 and 20, respectively. Simulations with Dolomieu‐like crater shapes suggest that curvature variations are more influential than depth variations. Topographic effects on seismic signals from rockfalls at Dolomieu crater are revealed by interstation spectral ratios. Results suggest that propagation along the topography rather than source direction dominates the spectral ratios and that resulting radiation patterns can be neglected. The seismic signature of single rockfall impacts is studied. Using Hertz contact theory, impact force and duration are estimated and then used to scale simulations, achieving order‐of‐magnitude agreement with observed signal amplitudes and frequency thresholds. Our study shows that combining Hertz theory with high‐frequency seismic wave simulations on real topography improves the quantitative analysis of rockfall seismic signals.
Thermoelastic Dispersion and Attenuation of P and SV Wave Scattering by Aligned Fluid‐Saturated Cracks of Finite Thickness in an Isothermal Elastic Medium
Authors: Wei Jia , Fu Li‐Yun , Han Tongcheng , Carcione José M. 
Published: September 2020

AbstractP and SV wave scattering by thermally constrained saturated cracks couples elastic deformation with temperature. We estimate the scattering attenuation and velocity dispersion by aligned fluid‐saturated cracks with finite thickness, which are sparsely and randomly embedded in an isothermal and isotropic elastic medium. By incorporating thermoelastic effects into the representation theorem with the non‐interaction Foldy approximation, we formulate the dispersion and attenuation of P and SV waves induced by displacement discontinuities across aligned cracks constrained by a thermoelastic boundary condition. The frequency‐dependent response as a function of temperature is calculated for various P and SV wave incidence angles. The resulting scattering attenuation and dispersion are compared with those of the conventional aligned‐crack model. The examples show that the dissipation increases with increasing temperature, but the scattering is inhibited at a given temperature. The P wave shows a strong sensitivity to temperature along the direction normal to the cracks, whereas the SV wave has an opposite behavior. This theory has the potential to assess the distribution of temperature from seismic attributes.
Structure and Density of H2O‐Rich Mg2SiO4 Melts at High Pressure From Ab Initio Simulations
Authors: Yuan Liang , Steinle‐Neumann Gerd , Suzuki Akio 
Published: September 2020

AbstractWater has a strong effect on silicate melt properties, yet its dissolution mechanism in depolymerized melts, typical for mantle composition, remains poorly understood. Here we report results of first‐principles molecular dynamics simulations for hydrous Mg2SiO4 melts with 6, 16, and 27 wt% H2O at pressure and temperature conditions relevant to the upper mantle and mantle transition zone. The results show that hydrogen bonds not only to the network‐forming cation Si but also to Mg which—nevertheless—remains the most important network modifier. There is no evidence to support the hypothesis based on experimental data that water may cause an increase in melt polymerization for ultramafic magmas; the ratio of non‐bridging oxygen per Si increases with the addition of the oxygen from H2O. The partial molar volume of water is independent on concentration in our simulations which allows us to examine the density of hydrous melt systematically. The critical water content—at which melts are neutrally buoyant compared to the surrounding mantle—is ~4 wt% H2O for a pyrolite composition, much lower than the high water content (>10 wt%) observed in petrological experiments and estimated thermodynamically for low‐degree partial melts formed in the vicinity of the mantle transition zone.
Seasonal Physical Fronts and Associated Biogeochemical‐Ecological Effects off the Jiangsu Shoal in the Western Yellow Sea, China
Authors: Wei Qinsheng , Fu Mingzhu , Sun Junchuan , Yao Qingzhen , Wang Baodong , Liu Xuehai , Yu Zhigang 
Published: September 2020

AbstractThe Jiangsu Shoal and its adjacent area in the western Yellow Sea (YS) have become hotspots of ecological disasters in China and have attracted considerable attention. Based on remote sensing and field observations in this region, we investigated the physical fronts and their seasonal variations and clarified the spatiotemporal patterns of physical‐biogeochemical factors as well as their interactions and synergies. The results show that pronounced physical fronts were present in the study area. Specifically, arc‐ and “S”‐shaped thermal fronts existed off the shoal in summer and winter, respectively. The saline front largely expanded southeastward in spring, autumn, and winter, while it expanded northeastward in summer. The turbidity over the shoal was high year‐round, and a marked turbidity front was formed between the nearshore water and the offshore seawater. The seasonal patterns and variations of the physical fronts significantly influenced material transport. During cold seasons, the frontal system was responsible for the significant turbid water plume expanding in a southeastern direction from the Jiangsu Coast. In summer, the arc‐shaped thermal front confined the turbid water within the shoal. The expansion of excess dissolved inorganic nitrogen was consistent with the saline front, and the vertical transport of nutrients by upwelling occurred off the shoal in summer. Due to favorable conditions, the frontal region off the shoal is prone to high chlorophyll a (Chl‐a) and may act as oases in either summer or winter. A conceptual diagram is assembled to provide an overview of physical‐biogeochemical‐ecological interactions off the Jiangsu Shoal in the western YS.
Investigation of the Variability of Near‐Surface Temperature Anomaly and Its Causes Over the Tibetan Plateau
Authors: Liu Ye , Xue Yongkang , Li Qian , Lettenmaier Dennis , Zhao Ping 
Published: September 2020

AbstractRecent research has reported the great influence of springtime land surface temperature (LST) and subsurface temperature (SUBT) over the Tibetan Plateau (TP) on downstream region summer precipitation, indicating the potential application of LST/SUBT on subseasonal to seasonal (S2S) prediction. In this study, we employed both observational data and offline model simulation to explore the memory of surface and subsurface variables and assess the driving effects of snow/albedo and SUBT on the LST anomaly. Our composite analysis based on observation shows that the anomalous LST in the TP can sustain for seasons and is accompanied by persistent SUBT as well as snow and associated surface albedo anomalies. A multilayer frozen soil model reproduces the observed LST anomaly and shows surface albedo and middle‐layer SUBT have 1–3 months memory, indicating the degree of persistence or dissipation of anomaly through time with more extended memory during spring. With simulated middle‐layer SUBT as a predictor, the linear regression model produces
of 0.44 and 0.26 for 1‐ and 2‐month LST prediction, respectively. The predictability is higher during the spring. Our results also show February snowfall, May snowmelt, and aero in snow exert substantial impacts on springtime LST through snow albedo feedback. The long memory of SUBT allows it to preserve the surface thermal anomaly and release it gradually in the following months to seasons. Meanwhile, the sensitivity study indicates that the soil properties and soil column depth predominate SUBT memory, which suggests the key processes to improve LST/SUBT then downstream S2S prediction.
Diurnal Climatology of Planetary Boundary Layer Height Over the Contiguous United States Derived From AMDAR and Reanalysis Data
Authors: Zhang Yuanjie , Sun Kang , Gao Zhiqiu , Pan Zaitao , Shook Michael A. , Li Dan 
Published: September 2020

AbstractThe diurnal variation of the planetary boundary layer height (PBLH) over the contiguous United States (CONUS) is examined using Aircraft Meteorological Data Reports (AMDAR) at 54 major airports and the ERA5 reanalysis product. The bulk Richardson number method is used to derive the PBLH at hourly scales from the AMDAR profiles. It is found that the estimated PBLH is sensitive to the value of the critical bulk Richardson number and to the consideration of the surface friction effect, especially under stable and near‐neutral conditions. Parameters constrained by field campaign observations are finally selected to estimate the PBLH. The results reveal that the diurnal climatology of PBLH exhibits seasonal and spatial variations, with greater diurnal variations in spring and summer and in the western regions. It is demonstrated that the traditional twice‐daily radiosonde data may roughly capture the diurnal amplitude of PBLH in the western but not the eastern CONUS. Compared to the AMDAR data, the ERA5 reanalysis product overestimates the daytime PBLH throughout the CONUS by 18–41% and shows an earlier peak time by 1–2 hr in the western regions and a later peak time by 1 hr in the eastern regions.
COnstraining ORographic Drag Effects (COORDE): A Model Comparison of Resolved and Parametrized Orographic Drag
Authors: van Niekerk Annelize , Sandu Irina , Zadra Ayrton , Bazile Eric , Kanehama Takafumi , Köhler Martin , Koo Myung‐Seo , Choi Hyun‐Joo , Kuroki Yukihiro , Toy Michael D. , Vosper Simon B. , Yudin Valery 
Published: September 2020

AbstractThe parametrization of orographic drag processes is a major source of circulation uncertainty in models. The COnstraining ORographic Drag Effects (COORDE) project makes a coordinated effort to narrow this uncertainty by bringing together the modeling community to: explore the variety of orographic drag parametrizations employed in current operational models; assess the resolution sensitivity of resolved and parametrized orographic drag across models; and to validate the parametrized orographic drag in low‐resolution simulations using explicitly resolved orographic drag from high‐resolution simulations. Eleven models from eight major modeling centers are used to estimate resolved orographic drag from high‐resolution (km‐scale) simulations and parametrized orographic drag from low‐resolution simulations, typically used for seasonal forecasting (∼40 km) and climate projections (∼100 km). In most models, at both seasonal and climate resolutions, the total (resolved plus parametrized) orographic gravity wave drag over land is shown to be underestimated by a considerable amount (up to 50%) over the Northern and Southern Hemisphere and by more than 60% over the Middle East region, with respect to the resolved gravity wave drag estimated from km‐scale simulations. The km‐scale simulations also provide evidence that the parametrized surface stress and the parametrized low‐level orographic drag throughout the troposphere are overestimated in most models over the Middle East region, particularly at climate resolutions. Through this process‐based evaluation, COORDE provides model developers new valuable information on the current representation of orographic drag at seasonal and climate resolutions and the vertical partitioning of orographic low‐level and gravity wave drag.
Sarcoma stratification by combined pH2AX and MAP17 (PDZK1IP1) levels for a better outcome on doxorubicin plus olaparib treatment
Authors: Perez Marco , García-Heredia José Manuel , Felipe-Abrio Blanca , Muñoz-Galván Sandra , Martín-Broto Javier , Carnero Amancio 
Published: September 2020

AbstractSarcomas constitute a rare heterogeneous group of tumors, including a wide variety of histological subtypes. Despite advances in our understanding of the pathophysiology of the disease, first-line sarcoma treatment options are still limited and new treatment approaches are needed. Histone H2AX phosphorylation is a sensitive marker for double strand breaks and has recently emerged as biomarker of DNA damage for new drug development. In this study, we explored the role of H2AX phosphorylation at Ser139 alone or in combination with MAP17 protein, an inducer of DNA damage through ROS increase, as prognostic biomarkers in sarcoma tumors. Next, we proposed doxorubicin and olaparib combination as potential therapeutic strategies against sarcomas displaying high level of both markers. We evaluate retrospectively the levels of pH2AX (Ser139) and MAP17 in a cohort of 69 patients with different sarcoma types and its relationship with clinical and pathological features. We found that the levels of pH2AX and MAP17 were related to clinical features and poor survival. Next, we pursued PARP1 inhibition with olaparib to potentiate the antitumor effect of DNA damaging effect of the DNA damaging agent doxorubicin to achieve an optimal synergy in sarcoma. We demonstrated that the combination of olaparib and doxorubicin was synergistic in vitro, inhibiting cell proliferation and enhancing pH2AX intranuclear accumulation, as a result of DNA damage. The synergism was corroborated in patient-derived xenografts (PDX) where the combination was effective in tumors with high levels of pH2AX and MAP17, suggesting that both biomarkers might potentially identify patients who better benefit from this combined therapy.
Recent advances in the development of protein–protein interactions modulators: mechanisms and clinical trials
Authors: Lu Haiying , Zhou Qiaodan , He Jun , Jiang Zhongliang , Peng Cheng , Tong Rongsheng , Shi Jianyou 
Published: September 2020

AbstractProtein–protein interactions (PPIs) have pivotal roles in life processes. The studies showed that aberrant PPIs are associated with various diseases, including cancer, infectious diseases, and neurodegenerative diseases. Therefore, targeting PPIs is a direction in treating diseases and an essential strategy for the development of new drugs. In the past few decades, the modulation of PPIs has been recognized as one of the most challenging drug discovery tasks. In recent years, some PPIs modulators have entered clinical studies, some of which been approved for marketing, indicating that the modulators targeting PPIs have broad prospects. Here, we summarize the recent advances in PPIs modulators, including small molecules, peptides, and antibodies, hoping to provide some guidance to the design of novel drugs targeting PPIs in the future.
Evaluation of a novel fixed-space maintainer made of light-cured acrylic resin: an in vitro study
Authors: Souror Yasser R. , Maaly Tayseer , Khawandanah Mohammed Sameer 
Published: September 2020

AbstractTo evaluate a fixed-space maintainer made of light-cure acrylic resin (LCAR) for its flexural and shear bond strength using different bonding systems to the enamel. 45 extracted primary teeth were selected. They were randomly divided into three equal groups (n = 15) along with the type of adhesive system (Tetric Flow, Transbond XT, and Fuji Ortho LC) used for bonding (LCAR) to the tooth surface. Surfaces were treated; LCAR was attached to the treated surfaces using a split Teflon mold. For flexural strength testing, ten bars of LCAR were made using another Teflon-split mold. Shear bond strength and mean flexural strength values were evaluated by a universal testing machine. The highest values of bond strength were recorded for Transbond XT, followed by Tetric Flow, while the lowest values were for Fuji Ortho LC. Various groups had a significant difference as investigated by ANOVA. ARI scores showed no significant difference in debond sites. Mean value and standard deviation of flexural strength for LCAR were 82.83  ± 5.2. LCAR has superior mechanical properties and could be an alternative to currently-in-use space maintainer though in vivo and in vitro trials are needed to progress the ultimate design of LCAR.