bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Seasonality of VLF Attenuation Through the Ionosphere Verified by DEMETER Satellite
Authors: Greninger Paul T. , Colman Jonah J. 
Published: May 2021

AbstractWe constructed a program, we call “Iriatten,” to calculate using parameters from the International Reference Ionosphere, attenuation of Very Low Frequency (VLF) radiation transiting the ionosphere. The calculations are performed as function of latitude, longitude, year, month, day, and hour and based upon the quasi‐longitudinal approximation put forth by Helliwell, where the wave vector k, is in the direction of propagation, and follows the Earth's magnetic field lines. The best values of various parameters are taken from the literature. Attenuation occurs through electron neutral collisions. In his seminal 1965 text, Helliwell presented atmospheric attenuation curves for day and night, 2 and 20 kHz, as a function of latitude. Program Iriatten is used to re‐calculate Helliwell's curves and then to fully exercise access to seasonality. High power VLF transmitters are utilized as a reference signal and two physical models are used to represent them. In the Vertically Inclined model, the attenuation is assumed to occur “straight up” from the location of the VLF transmitter. In the Crary model waves are launched from a dipole source and ionospheric attenuation is applied where the wave is turned up in the Earth‐ionospheric waveguide. Both representations reveal a seasonality that is unmistakable. Using the two models the ionospheric attenuation is calculated for four VLF transmitters and compared to observations by the DEMETER. Results from the Crary transmitter model more realistically portray seasonal variations exemplified by DEMETER satellite data. Crary model errors, which are within 11 dB, are lower than or comparable to Vertically Inclined errors.
Cusp Dynamics and Polar Cap Patch Formation Associated With a Small IMF Southward Turning
Authors: Nishimura Y. , Sadler F. B. , Varney R. H. , Gilles R. , Zhang S. R. , Coster A. J. , Nishitani N. , Otto A. 
Published: May 2021

AbstractWe present high‐resolution Resolute Bay Incoherent Scatter Radar (RISR) measurements in the cusp region during an IMF southward turning. The simultaneous RISR‐N and RISR‐C operation provided 3‐D observations of the dayside polar region, and offered an opportunity to identify the cusp dynamics and polar cap patch formation. Associated with the IMF southward turning, the F‐region density and temperature increased in the cusp, and the increase was particularly evident in the topside ionosphere. The high‐density plasma drifted into the polar cap by an enhanced poleward convection, and became a polar cap patch. The patch plasma was initially dominated by density originating in the cusp, and then later the subauroral ionospheric plasma also contributed to the density enhancement. Weak upflows were present but their contribution within the RISR altitude range was minor. We suggest that the patch source region switches due to dynamic variations of the cusp precipitation and convection from lower latitudes. RISR also detected a flow vortex embedded in the large‐scale convection, which is likely a poleward moving auroral form (PMAF) signature. Joule heating peaked in the cusp E and lower F‐regions. The F‐region Pedersen conductivity increased more than the Hall conductivity, and the high conductivity region extended poleward associated with the patch density enhancement. A 1‐D cusp simulation reproduced the density and temperature enhancements by soft electron precipitation, indicating the importance of soft electron precipitation for the cusp dynamics and the initial part of the patch formation.
Thermochemical State of the Upper Mantle Beneath South China From Multi‐Observable Probabilistic Inversion
Authors: Yang Xiaoyu , Li Yonghua , Afonso Juan Carlos , Yang Yingjie , Zhang Anqi 
Published: May 2021

AbstractWe present an upper mantle model of seismic velocities, temperature, density, and bulk composition for the South China Block (SCB) and adjacent areas by jointly inverting Rayleigh wave phase and group dispersion data, absolute elevation, geoid height, and surface heat flow using a probabilistic inversion method. The lithospheric structure of this region is dominated by a thick root (200–240 km) under the western Yangtze and thinner lithosphere (70–120 km) under the eastern SCB, in agreement with independent xenolith data. We reveal for the first time the extent of metasomatism/refertilization in the lithospheric mantle beneath the Yangtze Craton (YC). Our results show pervasive refertilization of the lithospheric mantle associated with the basaltic lavas of the Emeishan large igneous province. We also show that the refertilized mantle identified in the northern boundaries of the YC extends into the interior of the craton further than previously recognized, reaching at least parts of the Sichuan basin. The only region that preserve a depleted mantle signature is the central segment of the Yangtze craton. In contrast, the eastern SCB lithosphere is characterized by an alternating pattern of fast/slow seismic and depleted/fertile anomalies, supporting the hypothesis that the lithospheric mantle has been partly replaced/modified by deep mantle processes during the Phanerozoic. Also, we found no evidence for a linear plume track associated with the Hainan plume that can be used to independently constrain the plate motion history of the SCB.
Bayesian Inversion for a Stress‐Driven Model of Afterslip and Viscoelastic Relaxation: Method and Application to Postseismic Deformation Following the 2011 MW 9.0 Tohoku‐Oki Earthquake
Authors: Fukuda Junichi , Johnson Kaj M. 
Published: May 2021

AbstractPostseismic deformation following great subduction earthquakes is commonly modeled as the sum of the contributions from afterslip on the megathrust and viscoelastic relaxation of the coseismic stress changes in the mantle. However, it is generally difficult to separate the contributions of these mechanisms to geodetically observed postseismic deformation. Here we develop an inversion method for estimating the parameters of a stress‐driven postseismic deformation model that incorporates velocity‐strengthening afterslip and viscoelastic mantle relaxation governed by a biviscous Burgers rheology using coseismic and postseismic geodetic data. We assume that afterslip and viscoelastic relaxation are driven by coseismic stress changes and interact mechanically with each other. The unknown parameters to be estimated include the coseismic slip distribution that drives the postseismic processes, and the fault frictional and mantle viscosity parameters. We present a Bayesian formulation of the inverse problem and an algorithm for estimating the posterior probability density function. This approach allows us to quantify the uncertainties of the model parameters. We apply the method to the coseismic displacements and postseismic displacement time series of the 2011 Tohoku‐Oki earthquake. Our results show that the observations place tight constraints on the model parameters, with the estimated model effectively reproducing the first‐order spatial and temporal patterns of horizontal and vertical postseismic deformation. We find that the relative contributions of afterslip and viscoelastic relaxation to horizontal and vertical postseismic deformation vary in space. We suggest that our method may potentially provide a way to objectively separate the contributions of these two mechanisms to postseismic deformation.
Variability of Deep Water in Jordan Basin of the Gulf of Maine: Influence of Gulf Stream Warm Core Rings and the Nova Scotia Current
Authors: Du Jiabi , Zhang Weifeng G. , Li Yizhen 
Published: May 2021

AbstractAs the nutrient‐rich subsurface slope water intruding into the deep basin of the Gulf of Maine (GoM) supports the high biological productivity in the semi‐enclosed gulf, it is important to understand the process and time scale of such slope water intrusion. This study focuses on variations of the GoM deep water on seasonal to interannual time scales and the influences of open ocean processes on the temporal variation of the deep water properties. Based on long‐term monitoring data, it is found that the deep water at Jordan Basin (one of three major basins in the GoM) is persistently warmer in winter than in summer, which is distinctly different from the seasonality of surface water in the basin and the deep water on neighboring shelf seas. The unique seasonality in the deep GoM reflects a time‐lagged response to shoreward intrusion of the subsurface slope water off the GoM. Both observation‐based lag‐correlation analyses and numerical simulations confirm a timescale of approximately 3 months for the intruding subsurface slope water to flow from Northeast Channel to Jordan Basin. Properties of the intruding slope water at the Northeast Channel were significantly correlated with the Gulf Stream position and dramatically impacted by episodic warm‐core rings shed from Gulf Stream. Inside the deep GoM, the intruding slope water was also indirectly affected by the fresher water input from Nova Scotia Current. Spreading of the fresher water inside the gulf strengthens near‐surface stratification, suppresses deep convection, and preserves heat and salt in the deep GoM during the wintertime.
Multisensor and Multimodel Monitoring and Investigation of a Wintertime Air Pollution Event Ahead of a Cold Front Over Eastern China
Authors: Hu Xiao‐Ming , Hu Jun , Gao Lan , Cai Changjie , Jiang Yujun , Xue Ming , Zhao Tianliang , Crowell Sean M. R. 
Published: May 2021

AbstractGiven the limitations in pollutant measurements (e.g., coverage, observation errors) and air quality model uncertainties (e.g., with parameterizations and emissions), a multisensor and multimodel approach offers additional benefits compared to a single‐instrument and deterministic approach for monitoring, investigating, and predicting air pollution events. In this study, we use multisensors (including the spaceborne MODIS, OCO‐2, AIRS, and OMPS instruments as well as surface instruments) and multimodels (including WRF‐Chem and WRF‐CO2) to investigate a severe air pollution event on December 9, 2016 over eastern China. During this episode, a strong cold front moved southward. At the leading edge of the front, WRF‐CO2 simulates an enhanced XCO2 belt while WRF‐Chem simulates a belt of high PM2.5 concentration. The XCO2 and PM2.5 belts are generally colocated, due to coemission of CO2 and pollutants (or their precursors). Satellite observations including MODIS AOD, OCO‐2 XCO2, OMPS NO2, AIRS CO, and surface data confirm the simulated pollution and XCO2 belts. Later on, the front became distorted due to terrain blocking and mountain channel flows. Both observations and simulations show that the channel winds between Mountains Dabie and Huang transport the haze plume into Jiangxi province, enhancing pollution in the region. It is concluded that the multisensor (including space‐based and ground‐based instruments) and multimodel (e.g., WRF‐CO2, WRF‐Chem) approach can be used to collectively monitor and investigate air pollution events, given that emissions of the involved species have generally similar spatial distributions.
The Impact of Abyssal Hill Roughness on the Benthic Tide
Authors: Shakespeare Callum J. , Arbic Brian K. , McC. Hogg Andrew 
Published: May 2021

AbstractThe flow of tides over rough bathymetry in the deep ocean generates baroclinic motion including internal waves and bottom‐trapped tides. The stresses generated by this motion feedback on the amplitude and phase of the large‐scale tide. Quantifying the stresses associated with tidal flow over abyssal hills is especially important, as this scale of bathymetry is often unresolved in global baroclinic tide models, and the stresses must therefore be parameterized. Here, we extend the previous theoretical work of the authors to determine the amplitude, phasing, and vertical location of the stresses exerted on a flow driven by a time‐periodic body force when it encounters rough bathymetry. The theory compares favorably with a suite of fully nonlinear numerical simulations. It is shown that all topographic stresses are applied directly above the bathymetry, leading to a two‐layer baroclinic flow, with the near‐bottom spatial‐mean flow (the benthic tide) strongly modified by topographic stresses, and the flow at height unperturbed by the presence of topography. Our results provide a framework to improve baroclinic tide models by (i) providing a simple parameterization for the subinertial stress which is currently not included in any models, (ii) establishing that parameterized stresses should be applied in the diffusive boundary layer directly above the topography, independent of where internal tides may dissipate, and (iii) identifying a minimum resolution of ∼10 km for baroclinic tidal models to adequately capture wave resonance effects that can significantly impact the magnitude of the benthic tide.
Shaping the Future of Science: COVID‐19 Highlighting the Importance of GeoHealth
Authors: Gorris Morgan E. , Anenberg Susan C. , Goldberg Daniel L. , Kerr Gaige Hunter , Stowell Jennifer D. , Tong Daniel , Zaitchik Benjamin F. 
Published: May 2021

AbstractFrom the heated debates over the airborne transmission of the novel coronavirus to the abrupt Earth system changes caused by the sudden lockdowns, the dire circumstances resulting from the coronavirus disease 2019 (COVID‐19) pandemic have brought the field of GeoHealth to the forefront of visibility in science and policy. The pandemic has inadvertently provided an opportunity to study how human response has impacted the Earth system, how the Earth system may impact the pandemic, and the capacity of GeoHealth to inform real‐time policy. The lessons learned throughout our responses to the COVID‐19 pandemic are shaping the future of GeoHealth.
Evaluation of Flow‐Log Data From Crystalline Rocks With Steady‐State Pumping and Ambient Flow
Authors: Zou Liangchao , Cvetkovic Vladimir 
Published: May 2021

AbstractAlternative evaluation methods are assessed by numerical modeling of pumping tests in three‐dimensional fracture networks. Network scale heterogeneity, fracture‐to‐fracture scale heterogeneity, and individual fracture scale heterogeneity (fracture roughness) are considered as representative of multi‐scale hydraulic and structural heterogeneity of crystalline rocks. The results show that ambient hydraulic gradient has a negligible effect on transmissivity inference of sparsely fractured rocks using flow logs. Consequently, the common dual pumping method used to account for the ambient flow can be simplified to a single pumping. This could potentially reduce the site characterization effort in typical applications such as nuclear waste disposal. The transmissivity inference method based on the Thiem solution provides representative median transmissivity. It, however, underestimates relatively high transmissivities due to its inability to account for the impact of fracture roughness. These findings have important implications regarding pumping test schemes and data interpretation methods in the hydrogeological characterization of sparsely fractured rocks using flow‐log data.
Explaining the Shortcomings of Log‐Transforming the Dependent Variable in Regression Models and Recommending a Better Alternative: Evidence From Soil CO2 Emission Studies
Authors: Liaw Kao‐Lee , Khomik Myroslava , Arain M. Altaf 
Published: May 2021

AbstractLog‐transforming the dependent variable of a regression model, though convenient and frequently used, is accompanied by an under‐prediction problem. We found that this underprediction can reach up to 20%, which is significant in studies that aim to estimate annual budgets. The fundamental reason for this problem is simply that the log‐function is concave, and it has nothing to do with whether the dependent variable has a log‐normal distribution or not. Using field‐observed data of soil CO2 emission, soil temperature and soil moisture in a saturated‐specification of a regression model for predicting emissions, we revealed that the under‐predictions of the log‐transformed approach were pervasive and systematically biased. The key determinant of the problem's severity was the coefficient of variation in the dependent variable that differed among different combinations of the values of the explanatory factors. By applying a parsimonious (Gaussian‐Gamma) specification of the regression model to data from four different ecosystems, we found that this under‐prediction problem was serious to various extents, and that for a relatively weak explanatory factor, the log‐transformed approach is prone to yield a physically nonsensical estimated coefficient. Finally, we showed and concluded that the problem can be avoided by switching to the nonlinear approach, which does not require the assumption of homoscedasticity for the error term in computing the standard errors of the estimated coefficients.
CXCR4 intracellular protein promotes drug resistance and tumorigenic potential by inversely regulating the expression of Death Receptor 5
Authors: Nengroo Mushtaq A. , Maheshwari Shrankhla , Singh Akhilesh , Verma Ayushi , Arya Rakesh K. , Chaturvedi Priyank , Saini Krishan K. , Singh Anup K. , Sinha Abhipsa , Meena Sanjeev , Gupta Annapurna , Mishra Anjali , Sarkar Jayanta , Datta Dipak 
Published: May 2021

AbstractChemokine receptor CXCR4 overexpression in solid tumors has been strongly associated with poor prognosis and adverse clinical outcome. However, blockade of CXCL12-CXCR4 signaling axis by inhibitors like Nox-A12, FDA approved CXCR4 inhibitor drug AMD3100 have shown limited clinical success in cancer treatment. Therefore, exclusive contribution of CXCR4-CXCL12 signaling in pro-tumorigenic function is questionable. In our pursuit to understand the impact of chemokine signaling in carcinogenesis, we reveal that instead of CXCR4-CXCL12 signaling, presence of CXCR4 intracellular protein augments paclitaxel resistance and pro-tumorigenic functions. In search of pro-apoptotic mechanisms for CXCR4 mediated drug resistance; we discover that DR5 is a new selective target of CXCR4 in breast and colon cancer. Further, we detect that CXCR4 directs the differential recruitment of transcription factors p53 and YY1 to the promoter of DR5 in course of its transcriptional repression. Remarkably, inhibiting CXCR4-ligand-mediated signals completely fails to block the above phenotype. Overexpression of different mutant versions of CXCR4 lacking signal transduction capabilities also result in marked downregulation of DR5 expression in colon cancer indeed confirms the reverse relationship between DR5 and intracellular CXCR4 protein expression. Irrespective of CXCR4 surface expression, by utilizing stable gain and loss of function approaches, we observe that intracellular CXCR4 protein selectively resists and sensitizes colon cancer cells against paclitaxel therapy in vitro and in vivo. Finally, performing TCGA data mining and using human breast cancer patient samples, we demonstrate that expression of CXCR4 and DR5 are inversely regulated. Together, our data suggest that targeting CXCR4 intracellular protein may be critical to dampen the pro-tumorigenic functions of CXCR4.
TRIM25 regulates oxaliplatin resistance in colorectal cancer by promoting EZH2 stability
Authors: Zhou Sha , Peng Jianhong , Xiao Liuniu , Zhou Caixia , Fang Yujing , Ou Qingjian , Qin Jiayi , Liu Mengzhong , Pan Zhizhong , Hou Zhenlin 
Published: May 2021

AbstractResistance to chemotherapy remains the major cause of treatment failure in patients with colorectal cancer (CRC). Here, we identified TRIM25 as an epigenetic regulator of oxaliplatin (OXA) resistance in CRC. The level of TRIM25 in OXA-resistant patients who experienced recurrence during the follow-up period was significantly higher than in those who had no recurrence. Patients with high expression of TRIM25 had a significantly higher recurrence rate and worse disease-free survival than those with low TRIM25 expression. Downregulation of TRIM25 dramatically inhibited, while overexpression of TRIM25 increased, CRC cell survival after OXA treatment. In addition, TRIM25 promoted the stem cell properties of CRC cells both in vitro and in vivo. Importantly, we demonstrated that TRIM25 inhibited the binding of E3 ubiquitin ligase TRAF6 to EZH2, thus stabilizing and upregulating EZH2, and promoting OXA resistance. Our study contributes to a better understanding of OXA resistance and indicates that inhibitors against TRIM25 might be an excellent strategy for CRC management in clinical practice.
TP53INP1 exerts neuroprotection under ageing and Parkinson’s disease-related stress condition
Authors: Dinh Emilie , Rival Thomas , Carrier Alice , Asfogo Noemi , Corti Olga , Melon Christophe , Salin Pascal , Lortet Sylviane , Kerkerian-Le Goff Lydia 
Published: May 2021

AbstractTP53INP1 is a stress-induced protein, which acts as a dual positive regulator of transcription and of autophagy and whose deficiency has been linked with cancer and metabolic syndrome. Here, we addressed the unexplored role of TP53INP1 and of itsDrosophilahomolog dDOR in the maintenance of neuronal homeostasis under chronic stress, focusing on dopamine (DA) neurons under normal ageing- and Parkinson’s disease (PD)-related context.Trp53inp1−/−mice displayed additional loss of DA neurons in the substantia nigra compared to wild-type (WT) mice, both with ageing and in a PD model based on targeted overexpression of α-synuclein. NigralTrp53inp1expression of WT mice was not significantly modified with ageing but was markedly increased in the PD model.Trp53inp2expression showed similar evolution and did not differ between WT andTrp53inp1−/−mice. InDrosophila, pan-neuronaldDORoverexpression improved survival under paraquat exposure and mitigated the progressive locomotor decline and the loss of DA neurons caused by the human α-synuclein A30P variant.dDORoverexpression in DA neurons also rescued the locomotor deficit in flies with RNAi-induced downregulation ofdPINK1ordParkin. Live imaging, confocal and electron microscopy in fat bodies, neurons, and indirect flight muscles showed thatdDORacts as a positive regulator of basal autophagy and mitophagy independently of the PINK1-mediated pathway. Analyses in a mammalian cell model confirmed that modulatingTP53INP1levels does not impact mitochondrial stress-induced PINK1/Parkin-dependent mitophagy. These data provide the first evidence for a neuroprotective role of TP53INP1/dDOR and highlight its involvement in the regulation of autophagy and mitophagy in neurons.