bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measuring Fundamental and Higher Mode Surface Wave Dispersion on Mars From Seismic Waveforms
Authors: Xu Haotian , Beghein C. , Panning M. P. , Drilleau M. , Lognonné P. , van Driel M. , Ceylan S. , Böse M. , Brinkman N. , Clinton J. , Euchner F. , Giardini D. , Horleston A. , Kawamura T. , Kenda B. , Murdoch N. , Stähler S. 
Published: December 2020

AbstractOne of the goals of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission is to constrain the interior structure of Mars. We present a hierarchical transdimensional Bayesian approach to extract phase velocity dispersion and interior shear‐wave velocity (VS) models from a single seismogram. This method was adapted to Mars from a technique recently developed for Earth (Xu & Beghein, 2019, https://doi.org/10.1093/gji/ggz133). Monte Carlo Markov Chains seek an ensemble of one dimensional (1‐D) VS models between a source and a receiver that can explain the observed waveform. The models obtained are used to calculate the phase velocities of fundamental and higher modes at selected periods, and a subsequent analysis is performed to assess which modes were reliably measured. An advantage of our approach is that it can also fit unknown data noise, which reduces the risk of overfitting the data. In addition, uncertainties in the source parameters can be propagated, yielding more accurate model parameter uncertainties. In this study, we first present our technique and discuss the challenges stemming from using a single station to characterize both structure and the source and from the absence of a Mars reference model. We then demonstrate the method feasibility using the Mars Structure Service blind test data and our own synthetic data, which included realistic noise levels based on the noise recorded by InSight.
The Cusp as a VLF Saucer Source: First Rocket Observations of Long‐Duration VLF Saucers on the Dayside
Authors: Moser C. , LaBelle J. , Hatch S. , Moen J. I. , Spicher A. , Takahashi T. , Kletzing C. A. , Bounds S. , Oksavik K. , Sigernes F. , Yeoman T. K. 
Published: December 2020

AbstractAuroral whistler‐mode radio emissions called saucers are of fundamental interest because they require an unusually stationary emission process in the dynamic auroral environment, and it is a mystery how that can happen in this or similar conditions elsewhere in geospace. The Cusp Alfvén and Plasma Electrodynamics Rocket (CAPER‐2), launched into the cusp, obtained the first rocket measurements of a large‐scale, multiple‐armed dayside saucer, similar to those observed by the DEMETER satellite, with the addition of particle measurements and ground‐based measurements. Analysis of saucer shapes, directional measurements using waveforms, and ground‐based data show that, accounting for estimated uncertainties, these originate at altitudes ∼4,000 km within the cusp, the eastern side of which is penetrated by the rocket ∼100 s after the saucers are encountered. On‐board particle instruments show dispersed electron bursts in the cusp, Alfvénically accelerated at altitudes at or above the saucer sources.
Fast Quasi‐Geostrophic Magneto‐Coriolis Modes in the Earth's Core
Authors: Gerick F. , Jault D. , Noir J. 
Published: December 2020

AbstractFast changes of Earth's magnetic field could be explained by inviscid and diffusion‐less quasi‐geostrophic (QG) Magneto‐Coriolis modes. We present a hybrid QG model with columnar flows and three‐dimensional magnetic fields and find modes with periods of a few years at parameters relevant to Earth's core. For the simple poloidal magnetic field that we consider here they show a localization of kinetic and magnetic energy in the equatorial region. This concentration of energy near the equator and the high frequency make them a plausible mechanism to explain similar features observed in recent geomagnetic field observations. Our model potentially opens a way to probe the otherwise inaccessible magnetic field structure in the Earth's outer core.
Solar Extreme Ultraviolet Irradiance Uncertainties for Planetary Studies
Authors: Thiemann E. M. B. , Eparvier F. G. , Knoer V. , Al Muharrami Abdulla , Lillis R. J. 
Published: December 2020

AbstractAccurate estimates of extreme ultraviolet (EUV) irradiance are needed in order to understand the dynamical, chemical, and plasma processes occurring in planetary upper and tenuous atmospheres. Most studies rely on irradiance measurements made at Earth, which are extrapolated to the location of interest. The Mars Atmosphere and Volatile Evolution (MAVEN) orbiter includes the Extreme Ultraviolet Monitor (EUVM) instrument to measure the solar EUV irradiance in situ at Mars, which is used in this study to quantify the error introduced when phase‐shifting EUV measurements from Earth to other locations in the solar system. The MAVEN/EUVM solar soft X‐Ray (SXR) and Lyman‐α measurements are compared with analogous measurements made from Earth to characterize the typical error introduced when phase‐shifting solar EUV irradiance measurements made from Earth to other points in the solar system according to the 27.27 day synodic solar rotation period. The phase‐shifting error, εps, measured at SXR and Lyman‐α wavelengths are extrapolated to the full EUV spectrum by assuming it is proportional to the variability that occurs over the 27‐day timescale of solar rotation. Values for εps as a function of wavelength are reported and used to find the typical error for estimates of photoionization frequencies of some major species found in planetary upper atmospheres. Measuring EUV irradiance in situ reduces the random uncertainty by approximately half of that expected from phase shifting irradiances to the point of interest from Earth. These findings indicate that estimates of EUV induced variability in planetary atmospheres are highly uncertain at timescales of ∼10 days for large phase angles.
On the Altitude Patterns of Photo‐Chemical‐Equilibrium in the Martian Ionosphere: A Special Role for Electron Temperature
Authors: Mendillo Michael , Phillips Sophie R. , Narvaez Clara , Mayyasi Majd , Thiemann Edward , Benna Mehdi , Eparvier Francis , Chamberlin Phillip , Mahaffy Paul , Andersson Laila 
Published: December 2020

AbstractThe ionosphere at Mars is governed by photo‐chemical‐equilibrium (PCE) at and below the height of maximum electron density (∼130 km), while the topside ionosphere blends PCE with other processes (e.g., plasma dynamics). We studied the altitude profile from 135 to 260 km where PCE conditions transition to the non‐PCE domain. Using MAVEN observations of electron density (Ne) and temperature (Te), CO2 densities, and integrated energy flux Fsun(5–93 nm), we tested the PCE relationship (Mendillo et al., 2017, https://doi.org/10.1002/2017ja024366). We found high correlations coefficients (CC = 80–90%) for heights 25–40 km above hmax, and then decreases to CC = 50% (defining partial PCE control). Surprisingly, CCs returned to > 50% in the 160–175 height range. We found the re‐establishment of PCE control occurs where the Te values rise sharply and thereby reduce the plasma recombination rate due to its inverse dependence on electron temperature. Enhancements in the topside ionosphere due to that process were first postulated by Fox and Yeager (2006, https://doi.org/10.1029/2006JA011697) to explain the “shoulder” seen Ne(h) profiles from radio occultation experiments. MAVEN data now provide the first comprehensive set of in situ observations to relate this enigmatic “bulge” to observed PCE parameters. Moreover, MAVEN observations reveal that additional sources are present to account for the Ne enhancements larger than possible from the thermal process alone.
Application of Cold and Hot Plasma Composition Measurements to Investigate Impacts on Dusk‐Side Electromagnetic Ion Cyclotron Waves
Authors: Lee Justin H. , Turner Drew L. , Vines Sarah K. , Allen Robert C. , Toledo‐Redondo Sergio , Bingham Sam T. , Fuselier Stephen A. , Cohen Ian J. , Starkey Michael J. , Graham Daniel B. , Khotyaintsev Yuri V. , Mauk Barry H. , Pollock Craig J. , Ergun Robert E. , Lindqvist Per‐Arne , Torbert Roy B. , Burch James L. 
Published: December 2020

AbstractAn extended interval of perturbed magnetospheric conditions in November 2016 supported increased convection and sunward transport of plasmaspheric material. During this period of time the Magnetospheric Multiscale satellites, with their apogees along Earth's dusk‐side outer magnetosphere, encountered several cold plasma density structures at the same time as plasma bulk flows capable of accelerating hidden cold plasma occurred. Investigating the charged particle and fields data during two subintervals showed that the satellites made direct measurements of cold plasmaspheric ions embedded within multicomponent hot plasmas as well as electromagnetic emissions consistent with electromagnetic ion cyclotron (EMIC) waves. The complex in situ ion composition measurements were applied to linear wave modeling to interpret the impacts of cold and hot ion species on wave growth and band structure. Although the waves for both intervals were predicted to have peak growth rate below ΩHe+, substantial differences were observed among all other dispersive properties. The modeling also showed EMIC waves generated in the presence of heavy ions had growth rates and unstable wave numbers always smaller than predicted for a pure proton‐electron plasma. The results provide implications for future investigation of EMIC wave generation with and without direct measurements of the cold and hot plasma composition as well as of subsequent wave‐particle interactions.
Joint Bayesian Inference for Near‐Surface Explosion Yield and Height‐of‐Burst
Authors: Ford S. R. , Bulaevskaya V. , Ramirez A. , Johannesson G. , Rodgers A. J. 
Published: December 2020

AbstractForensic capabilities to understand chemical and nuclear explosions are greatly aided by an accurate estimate of explosive yield with uncertainty. The relationship between explosive size and geophysical observations of seismic, acoustic, and optical waves can be exploited to provide an estimate of yield. Any near‐surface yield estimate is complicated by the surface interaction, so an estimate for the explosion height‐of‐burst is necessarily included in the relationship. The relationship dictates a trade‐off between estimates of yield and height‐of‐burst. Fortunately, the surface interaction for each type of observation is different, which breaks the trade‐off, and the inclusion of height‐of‐burst with multiple data types improves yield estimation. We define simple parametric forward models to relate seismoäcoustoöptic observations from a data set of known explosive yields and height‐of‐bursts. The parameters of the models and a prediction for the yield and height‐of‐burst of a new event can then be estimated given new observations via Bayesian inference. We report posterior distribution estimates of the parametric models using a Markov chain Monte Carlo sampling technique. These models are then used to predict the yield and height‐of‐burst of SUGAR, a historical near‐surface nuclear explosion, using its reported historical observations. The reported yield of 1.2 ktonne Trinitrotoluene (TNT)‐equivalent (Department of Energy, 2015) is within the estimated posterior. Yield uncertainty can be estimated from the spread of the posterior, which is between 0.9 and 2.1 ktonne TNT‐equivalent. The posterior for height‐of‐burst has a wider range between 10 m below and 8 m above ground that includes the true height‐of‐burst of 1 m.
Deposition and Dispersion of Radio‐Cesium Released due to the Fukushima Nuclear Accident: 2. Sensitivity to Aerosol Microphysical Properties of Cs‐Bearing Microparticles (CsMPs)
Authors: Kajino Mizuo , Adachi Kouji , Igarashi Yasuhito , Satou Yukihiko , Sawada Morihiro , Thomas Sekiyama Tsuyoshi , Zaizen Yuji , Saya Akane , Tsuruta Haruo , Moriguchi Yuichi 
Published: December 2020

AbstractThe dispersion and deposition of radio‐cesium (137Cs) carried by two types (type A and type B) of water‐insoluble Cs‐bearing solid microparticles (CsMPs) released due to the Fukushima nuclear accident were simulated for the first time. The presence of type B CsMPs (70–400 μm found in soil and 1–5 μm found in air), associated with the hydrogen explosion of Unit 1 in the afternoon of March 12, could partly explain the simulated underestimation of total deposition over land by assuming that 100% of the Cs carriers were water‐soluble submicron particles (WSPs). Type A CsMPs (0.1–10 μm), released from Units 2 or 3 in the midnight between March 14 and 15, traveled over the Kanto Plain, the most populated plain in Japan. Differences in the size distribution of type A CsMPs altered the surface air concentration over Kanto substantially, by up to more than one order of magnitude. The major deposition mechanisms varied among dry, wet, and fog (and/or cloud) depositions depending on the size distribution and locations. The simulated activity fractions due to the CsMPs in the total deposition were compared to those observed in surface soil for the first time. The observations could be explained by the simulations for the locations under the influence of type B CsMPs. However, the simulations were substantially underestimated for the locations influenced by type A CsMPs. There could be more fractions of type A CsMPs emission in the source term and/or the simulated deposition rates of type A CsMPs were underestimated.
Coupling of the CAS‐LSM Land‐Surface Model With the CAS‐FGOALS‐g3 Climate System Model
Authors: Xie Jinbo , Xie Zhenghui , Jia Binghao , Qin Peihua , Liu Bin , Wang Longhuan , Wang Yan , Li Ruichao , Chen Si , Liu Shuang , Zeng Yujing , Gao Junqiang , Li Lijuan , Yu Yongqiang , Dong Li , Wang Bin , Xie Zhipeng 
Published: December 2020

AbstractThe land‐surface model of the Chinese Academy of Sciences (CAS‐LSM), which includes lateral flow, water use, nitrogen discharge and river transport, soil freeze‐thaw front dynamics, and urban planning, was implemented in the Flexible Global Ocean‐Atmosphere‐Land System model, grid‐point version 3 (CAS‐FGOALS‐g3) to investigate the climatic effects of eco‐hydrological processes and human activities. Simulations were conducted using the land‐atmospheric component setup of CAS‐FGOALS‐g3 with given sea‐surface temperatures and sea‐ice distributions to assess its new capabilities. It was shown that anthropogenic groundwater use led to increased latent heat flux of about 20 W∙m−2 in three groundwater overexploitation areas: North India, northern China, and central United States. The groundwater lateral flow accompanied by this exploitation has led to deepening water table depth in these regions. The derived permafrost extent from the soil freeze‐thaw front (FTF) was comparable to observations, and the inclusion of FTF dynamics enabled simulations of seasonal variations in freeze‐thaw processes and related eco‐hydrological effects. Inclusion of riverine nitrogen transport and its joint implementation with the human activity scheme showed large dissolved inorganic nitrogen concentrations in major rivers around the globe, including western Europe, eastern China, and the U.S. Midwest, which were affected by nitrogen retention and surface water use during transport. The results suggest that the model is a useful tool for studying the effects of land‐surface processes on global climate, especially those influenced by human interventions.
Detecting Shallow Groundwater From Spaceborne Soil Moisture Observations
Authors: Soylu Mehmet E. , Bras Rafael L. 
Published: December 2020

AbstractIn order to accurately estimate surface fluxes, groundwater levels need to be specified accurately. However, monitoring Groundwater (GW) is challenging. The main goal of this study is to develop an innovative, yet simple, approach to detect shallow GW based solely on spaceborne soil moisture observations and apply this approach to improve the lower boundary conditions of soil moisture models. We simulated the influence of shallow GW on surface soil moisture under various environmental conditions and the results showed that the mean soil moisture and its Coefficient of Variation (CV) are both sensitive to shallow GW. Using those observations, we developed an algorithm that uses empirical functions calculating thresholds of mean soil moisture and CV to detect occurrence of shallow GW. We tested this algorithm in five different locations representing various climatic regions across the US, Argentina, and Australia. The algorithm performed well by correctly identifying periods of GW influence 92.4% of the time. We confirmed the algorithm by applying it over two regions: The Pampas, Argentina, and Southwestern Australia. The results indicate that our SMAP‐based algorithm successfully detects the shallow groundwater influenced time periods and significantly improves one particular soil moisture model output when the lower boundary conditions are adjusted according to the detection of shallow groundwater. The SMAP‐based method presented here addresses the growing need for observation‐based approaches to detect shallow groundwater at regional to global scales that may be beneficial to improving land surface and Earth system models.
Blockade of EIF5A hypusination limits colorectal cancer growth by inhibiting MYC elongation
Authors: Coni Sonia , Serrao Silvia Maria , Yurtsever Zuleyha Nihan , Di Magno Laura , Bordone Rosa , Bertani Camilla , Licursi Valerio , Ianniello Zaira , Infante Paola , Moretti Marta , Petroni Marialaura , Guerrieri Francesca , Fatica Alessandro , Macone Alberto , De Smaele Enrico , Di Marcotullio Lucia , Giannini Giuseppe , Maroder Marella , Agostinelli Enzo , Canettieri Gianluca 
Published: December 2020

ABSTRACTEukaryotic Translation Initiation Factor 5A (EIF5A) is a translation factor regulated by hypusination, a unique posttranslational modification catalyzed by deoxyhypusine synthetase (DHPS) and deoxyhypusine hydroxylase (DOHH) starting from the polyamine spermidine. Emerging data are showing that hypusinated EIF5A regulates key cellular processes such as autophagy, senescence, polyamine homeostasis, energy metabolism, and plays a role in cancer. However, the effects of EIF5A inhibition in preclinical cancer models, the mechanism of action, and specific translational targets are still poorly understood. We show here that hypusinated EIF5A promotes growth of colorectal cancer (CRC) cells by directly regulating MYC biosynthesis at specific pausing motifs. Inhibition of EIF5A hypusination with the DHPS inhibitor GC7 or through lentiviral-mediated knockdown of DHPS or EIF5A reduces the growth of various CRC cells. Multiplex gene expression analysis reveals that inhibition of hypusination impairs the expression of transcripts regulated by MYC, suggesting the involvement of this oncogene in the observed effect. Indeed, we demonstrate that EIF5A regulates MYC elongation without affecting its mRNA content or protein stability, by alleviating ribosome stalling at five distinct pausing motifs in MYC CDS. Of note, we show that blockade of the hypusination axis elicits a remarkable growth inhibitory effect in preclinical models of CRC and significantly reduces the size of polyps in APCMin/+ mice, a model of human familial adenomatous polyposis (FAP). Together, these data illustrate an unprecedented mechanism, whereby the tumor-promoting properties of hypusinated EIF5A are linked to its ability to regulate MYC elongation and provide a rationale for the use of DHPS/EIF5A inhibitors in CRC therapy.
Varicella-zoster virus VLT-ORF63 fusion transcript induces broad viral gene expression during reactivation from neuronal latency
Authors: Ouwendijk Werner J. D. , Depledge Daniel P. , Rajbhandari Labchan , Lenac Rovis Tihana , Jonjic Stipan , Breuer Judith , Venkatesan Arun , Verjans Georges M. G. M. , Sadaoka Tomohiko 
Published: December 2020

AbstractVaricella-zoster virus (VZV) establishes lifelong neuronal latency in most humans world-wide, reactivating in one-third to cause herpes zoster and occasionally chronic pain. How VZV establishes, maintains and reactivates from latency is largely unknown. VZV transcription during latency is restricted to the latency-associated transcript (VLT) and RNA 63 (encoding ORF63) in naturally VZV-infected human trigeminal ganglia (TG). While significantly more abundant, VLT levels positively correlated with RNA 63 suggesting co-regulated transcription during latency. Here, we identify VLT-ORF63 fusion transcripts and confirm VLT-ORF63, but not RNA 63, expression in human TG neurons. During in vitro latency, VLT is transcribed, whereas VLT-ORF63 expression is induced by reactivation stimuli. One isoform of VLT-ORF63, encoding a fusion protein combining VLT and ORF63 proteins, induces broad viral gene transcription. Collectively, our findings show that VZV expresses a unique set of VLT-ORF63 transcripts, potentially involved in the transition from latency to lytic VZV infection.
An excitatory ventromedial hypothalamus to paraventricular thalamus circuit that suppresses food intake
Authors: Zhang Jia , Chen Dan , Sweeney Patrick , Yang Yunlei 
Published: December 2020

AbstractIt is well recognized that ventromedial hypothalamus (VMH) serves as a satiety center in the brain. However, the feeding circuit for the VMH regulation of food intake remains to be defined. Here, we combine fiber photometry, chemo/optogenetics, virus-assisted retrograde tracing, ChR2-assisted circuit mapping and behavioral assays to show that selective activation of VMH neurons expressing steroidogenic factor 1 (SF1) rapidly inhibits food intake, VMH SF1 neurons project dense fibers to the paraventricular thalamus (PVT), selective chemo/optogenetic stimulation of the PVT-projecting SF1 neurons or their projections to the PVT inhibits food intake, and chemical genetic inactivation of PVT neurons diminishes SF1 neural inhibition of feeding. We also find that activation of SF1 neurons or their projections to the PVT elicits a flavor aversive effect, and selective optogenetic stimulation of ChR2-expressing SF1 projections to the PVT elicits direct excitatory postsynaptic currents. Together, our data reveal a neural circuit from VMH to PVT that inhibits food intake.
Inhibition of protein glycosylation is a novel pro-angiogenic strategy that acts via activation of stress pathways
Authors: Zhong Cuiling , Li Pin , Argade Sulabha , Liu Lixian , Chilla’ Anastasia , Liang Wei , Xin Hong , Eliceiri Brian , Choudhury Biswa , Ferrara Napoleone 
Published: December 2020

AbstractEndothelial cell (EC) metabolism is thought to be one of the driving forces for angiogenesis. Here we report the identification of the hexosamine D-mannosamine (ManN) as an EC mitogen and survival factor for bovine and human microvascular EC, with an additivity with VEGF. ManN inhibits glycosylation in ECs and induces significant changes in N-glycan and O-glycan profiles. We further demonstrate that ManN and two N-glycosylation inhibitors stimulate EC proliferation via both JNK activation and the unfolded protein response caused by ER stress. ManN results in enhanced angiogenesis in a mouse skin injury model. ManN also promotes angiogenesis in a mouse hindlimb ischemia model, with accelerated limb blood flow recovery compared to controls. In addition, intraocular injection of ManN induces retinal neovascularization. Therefore, activation of stress pathways following inhibition of protein glycosylation can promote EC proliferation and angiogenesis and may represent a therapeutic strategy for treatment of ischemic disorders.