bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Presence of Africa and Limited Soil Moisture Contribute to Future Drying of South America
Authors: Pietschnig M. , Lambert F. H. , Saint‐Lu M. , Vallis G. K. 
Published: November 2019

AbstractOver oceans, precipitation generally increases with warming in regions where preindustrial precipitation minus evaporation is positive. This simple “wet‐get‐wetter” principle does not hold over land. The Amazon region and Equatorial Africa currently receive ample rainfall, but the former is projected to dry out whereas precipitation is expected to increase over the latter. Our experiments with an idealized Atmospheric General Circulation Model and realistic continents show that land surface evaporation must be limited in order to obtain drying over the Amazon basin. Our simulations with rectangular, flat continents reveal that large parts of South America would receive more rainfall with warming in the absence of Africa. We suggest that this is due to a warming‐induced Matsuno‐Gill‐type circulation anomaly over Africa. We propose a new simple scaling that diagnoses precipitation change from surface relative humidity change and provides further evidence for the importance of circulation changes for future rainfall.
Interdecadal variation of Indian Ocean basin mode and the impact on Asian summer climate
Authors: Sun Bo , Li Huixin , Zhou Botao 
Published: November 2019

AbstractThis study documents an interdecadal variation in the pattern of Indian Ocean basin mode (IOBM) of sea surface temperature (SST) during boreal summer, where the center of action in the IOBM shifted towards the Arabian Sea after the late 1970s. Correspondingly, the influences of an interannual warming in the tropical Indian Ocean on the Asian summer climate became more significant after the late 1970s due to the Arabian Sea center of action, which are characterized by anomalous subsidence and anticyclones over the Bay of Bengal and the South China Sea. These atmospheric anomalies may result in surface temperature and precipitation anomalies in a wide area of Asia. Numerical experiments demonstrate the different influences of different IOBM patterns on the Asian summer climate. Statistical analysis and numerical experiments indicate a minor role of the different tropical Pacific SSTs concurrent with the different IOBMs in causing the different Asian summer climate anomalies.
Quantifying the Potential for Snow‐Ice Formation in the Arctic Ocean
Authors: Merkouriadi Ioanna , Liston Glen E. , Graham Robert M. , Granskog Mats A. 
Published: November 2019

AbstractWe examine the regional variations and long‐term changes of the potential for snow‐ice formation for level Arctic sea ice from 1980 to 2016. We use daily sea ice motion data and implement a 1‐D snow/ice thermodynamic model that follows the ice trajectories while forcing the simulations with Modern‐Era Retrospective analysis for Research and Applications, Version 2 and ERA‐Interim reanalyses. We find there is potential for snow‐ice formation in level ice over most of the Arctic Ocean; this is true since the 1980s. In addition, the regional variations are very strong. The largest potential is typically found in the Atlantic sector of the Arctic Ocean, particularly in the Greenland Sea, where precipitation is highest. We surmise that, in addition to the annual amount of solid precipitation, potential for snow‐ice formation is controlled by two main factors: the initial second‐year/multiyear ice thickness in the autumn and the timing of first‐year ice formation.
Unprecedented DMSP Concentrations in a Massive Dinoflagellate Bloom in Monterey Bay, CA
Authors: Kiene Ronald P. , Nowinski Brent , Esson Kaitlin , Preston Christina , Marin Roman , Birch James , Scholin Christopher , Ryan John , Moran Mary Ann 
Published: November 2019

AbstractThe organic sulfur compound dimethylsulfoniopropionate (DMSP) is synthesized by numerous species of marine phytoplankton, and its volatile degradation products are a major source of biogenic sulfur to the atmosphere. A massive bloom of the dinoflagellate Akashiwo sanguinea occurred in Monterey Bay, CA, USA, in the fall of 2016 and led to exceptionally high seawater DMSP concentrations that peaked at 4,240 nM. Bacterial consumption rates showed that only a small fraction of the DMSP standing stock flowed through the dissolved DMSP pool per day, contributing to the high DMSP concentrations and creating conditions conducive to production of dimethylsulfide (DMS). Conservative calculations of DMS yield from this persistent A. sanguinea bloom suggest substantial regional‐scale inputs of DMS‐sulfur to the atmosphere. Other recently reported major coastal blooms of A. sanguinea, along with indications that this species may benefit from climate change conditions, reveal a mechanism that could alter oceanic contributions to atmospheric sulfur pools.
Orbital Identification of Hydrated Silica in Jezero Crater, Mars
Authors: Tarnas J. D. , Mustard J. F. , Lin Honglei , Goudge T. A. , Amador E. S. , Bramble M. S. , Kremer C. H. , Zhang X. , Itoh Y. , Parente M. 
Published: November 2019

AbstractSilica has the highest demonstrated potential of any phase to preserve microfossils on Earth and therefore may host potential biosignatures on Mars. We detected hydrated silica in Jezero crater, the landing site of the National Aeronautics and Space Administration's Mars 2020 rover mission, by applying Dynamic Aperture Factor Analysis/Target Transformation to images from the Compact Reconnaissance Imaging Spectrometer for Mars. Hydrated silica detections with Dynamic Aperture Factor Analysis/Target Transformation were verified using commonly accepted Compact Reconnaissance Imaging Spectrometer for Mars analysis methods. The morphology of geologic units associated with silica was characterized with high‐resolution imaging. Several hypotheses are presented for the formation environment of hydrated silica. All are testable via in situ investigation. We assess the likelihood of silica to preserve biosignatures in these different scenarios based on habitability considerations and biosignature preservation in Earth analog environments and materials. Also reported are possible detections of hydrated silica in the Nili Fossae basement and olivine‐rich units, as well as Al‐phyllosilicate within Jezero crater.
High‐Resolution Optical Observations of Neutral Heating Associated With the Electrodynamics of an Auroral Arc
Authors: Price D. J. , Whiter D. K. , Chadney J. M. , Lanchester B. S. 
Published: November 2019

AbstractWe present results that indicate the existence of two distinct neutral heating processes associated with a discrete auroral arc over Svalbard. Within the order of seconds, the thermospheric temperature profile displays a significant response to the arc on spatial scales smaller than 10 km. It is suggested that both heating signatures are associated with the electrodynamic system responsible for the formation of the arc. Pedersen currents produce a temperature increase of approximately 100 K, observed at altitudes between 80 and 160 kilometres, directly adjacent to the arc structure and on its poleward edge only. In contrast, field‐aligned currents produce a variable temperature increase, of approximately 50 K, which is observed within the arc itself and constrained to a narrow altitude range between 90 and 110 km. By utilizing a range of observations and new analysis methods we are able to measure the atmospheric neutral temperature profile, over auroral altitudes, at unprecedented temporal and spatial scales. The High Throughput Imaging Echelle Spectrograph records high‐resolution emission spectra of the aurora, which are then fitted with synthetic N2 spectra, generated with modeled N2 volume emission rate profiles and a library of trial temperature profiles. The N2 volume emission rate profiles are retrieved from the Southampton ionospheric model using precipitating particle energies and fluxes obtained from Auroral Structure and Kinetics and the EISCAT Svalbard Radar. The application of this technique allows us to produce a time series of neutral temperature profiles and measure the localized heating of the neutral atmosphere resulting from the electrodynamics of the arc.
Unraveling the Mechanics of Thermal Stress Weathering: Rate‐Effects, Size‐Effects, and Scaling Laws
Authors: Ravaji Babak , Alí‐Lagoa Víctor , Delbo Marco , Wilkerson Justin W. 
Published: November 2019

AbstractThermal stress weathering is now recognized to be an active and significant geomorphological process on airless bodies. This study aims to understand the key factors governing thermal stresses in rocks on airless bodies through extensive numerical calculations and analytic analyses. Microscopic (grain‐scale) thermal stresses are driven primarily by the maximum diurnal temperature variation at said depth. Macroscopic (rock‐scale) thermal stresses are more complex. For rock sizes larger than the thermal skin depth, macroscopic thermal stresses are driven primarily by second (and higher) order spatial gradients of temperature. For rock sizes smaller than the thermal skin depth, macroscopic thermal stresses are primarily driven by the ratio of rock size to thermal skin depth. Additionally, scaling relations for diurnal surface temperature variation, time‐rate‐of‐change of surface temperature, as well as peak microscopic (grain‐scale) and macroscopic (rock‐scale) thermal stresses are derived to provide a more accessible modeling tool. These scaling relations are remarkably accurate when compared to both the numerical calculations as well as three‐dimensional finite element calculations. The model formulation, results, and scaling relations provided here allow the estimation of diurnal temperatures and thermal stresses on rocks of various size and materials on airless bodies at any orbital distance with a broad spectrum of spin rates. Lastly, we postulate and confirm that there is a critical spin rate where macroscopic thermal stresses will be greatest.
Dynamic Controls on Field‐Scale Soil Nitrous Oxide Hot Spots and Hot Moments Across a Microtopographic Gradient
Authors: Krichels Alexander H. , Yang Wendy H. 
Published: November 2019

AbstractSoil nitrous oxide (N2O) emissions are highly variable in space and time, making it difficult to estimate ecosystem level fluxes of this potent greenhouse gas. While topographic depressions are often evoked as permanent N2O hot spots and rain events are well‐known triggers of N2O hot moments, soil N2O emissions are still poorly predicted. Thus, the objective of this study was to determine how to best use topography and rain events as variables to predict soil N2O emissions at the field scale. We measured soil N2O emissions 11 times over the course of one growing season from 65 locations within an agricultural field exhibiting microtopography. We found that the topographic indices best predicting soil N2O emissions varied by date, with soil properties as consistently poor predictors. Large rain events (>30 mm) led to an N2O hot moment only in the early summer and not in the cool spring or later in the summer when crops were at peak growth and likely had high evapotranspiration rates. In a laboratory experiment, we demonstrated that low heterotrophic respiration rates at cold temperatures slowly depleted soil dissolved O2, thus suppressing denitrification over the 2–3 day timescale typical of field ponding. Our findings show that topographic depressions do not consistently act as N2O hot spots and that rainfall does not consistently trigger N2O hot moments. We assert that the spatiotemporal variation in soil N2O emissions is not always characterized by predictable hot spots or hot moments and that controls on this variation change depending on environmental conditions.
Seasonal Variations in N2O Emissions in a Subtropical Forest With Exogenous Nitrogen Enrichment are Predominately Influenced by the Abundances of Soil Nitrifiers and Denitrifiers
Authors: Han Xiaoge , Xu Changchao , Nie Yanxia , He Jinhong , Wang Wenjuan , Deng Qi , Shen Weijun 
Published: November 2019

AbstractElevated nitrogen (N) deposition has induced substantial impacts on the emissions of nitrous oxide (N2O) from forest ecosystems, but how soil microbes regulate the production/consumption of N2O under elevated N deposition remains poorly understood, particularly in high N deposition subtropical forests that are characterized by distinct wet‐dry seasonality. We established a field N addition experiment in a subtropical forest in southern China to explore the influences of low, medium and high (35, 70, and 105 kg N ha‐1 yr‐1, respectively) N addition on N2O efflux and its associated microbial functional genes [amoA for nitrifiers (ammonia‐oxidizing bacteria (AOB) and ammonia‐oxidizing archaea (AOA)) and nirK and nosZ for denitrifiers]. The results showed the following: (1) The N2O emissions were stimulated by N addition in the dry season but were depressed in the wet season. (2) The nirK and nosZ abundances were generally stimulated by N addition, whereas the AOB‐amoA and AOA‐amoA abundances showed divergent responses to N addition. (3) Based on the results of principal component and Pearson correlation analyses, N2O effluxes were associated with microbial biomass in the wet season but with nirK and nosZ abundances in the dry season. Structural equation modeling analyses further indicated that both nitrifiers and denitrifiers under N addition contributed to the generation of N2O in the dry season, whereas the decreased production of N2O in the wet season was primarily caused by denitrifiers. Therefore, seasonally specific strategies should be developed to mitigate the emissions of N2O from subtropical forests with distinct seasonal precipitation patterns.
Analysis of Bent Wire Antenna Resonant Frequency for Different Bent Angles
Authors: Suganya J. , Sciacca Umberto , Baskaradas James A. , Zirizzotti Achille 
Published: November 2019

AbstractFor the bedrock survey in the temperate glacier regions, low frequency antenna system of the airborne ground penetrating RADAR plays a very important role. A small size antenna, working at 10 MHz, would make its use easier in various radar applications. Reducing the resonant frequency of the wire dipole antenna structure, without increasing the physical size, can be attained by introducing bents in the existing structure. This paper introduces a new bent wire dipole antenna and presents the effects of bent angle of 80°, 70°, 60°, 50°, 45° and 40°of the wire antenna on the antenna parameters such as resonant frequency, S11, VSWR, gain and radiation pattern. A broadband four element equivalent circuit model of a straight dipole is used with some modifications in the R, L, C equations for the new bent wire dipole antenna by utilizing the bent angle. The frequency response of the equivalent circuit model, calculated resonant frequency values using the equations and the simulated results of the bent wire dipole antenna is compared and analyzed. As the antenna placement area inside the anechoic chamber is limited, the size of the 10MHz antenna has been scaled down by a factor of 0.01. This modifies the resonant frequency of the new structure to 1GHz. The scaled down antenna system are simulated, analyzed and tested in a GTEM cell. For bandwidth improvement of the 10 MHz antenna, a lumped element matching circuit has been designed and simulated.
Fault Creep and Strain Partitioning in Trinidad‐Tobago: Geodetic Measurements, Models, and Origin of Creep
Authors: Weber John , Geirsson Halldor , La Femina Peter , Robertson Richard , Churches Chris , Shaw Kenton , Latchman Joan , Higgins Machel , Miller Keith 
Published: November 2019

AbstractThe expansion of geodetic networks and Earth observing systems has allowed for new understandings of continental transform faults, including the partitioning of relative plate motions between multiple active strands and fault behavior during the earthquake cycle. One important global observation is that some continental transform faults creep (i.e., slip aseismically) at a percentage of or even at the full relative plate motion rate. The Caribbean‐South American plate boundary is a right‐stepping, segmented, dextral continental transform system. We studied active faults in the Trinidad‐Tobago segment of the Caribbean‐South American plate boundary zone using a new GPS‐derived horizontal velocity field, then modeled these data using a series of simple screw dislocation models. Our best‐fit model for interseismic strain accumulation requires 13.4 ± 0.3 mm/yr of right‐lateral movement and very shallow locking (0.2 ± 0.2 km), essentially creep, across the Central Range Fault (CRF), 3.4 ± 0.3 mm/yr across the South Coast Fault south of Trinidad, and 3.5 ± 0.3 mm/yr of dextral shear on fault(s) between Trinidad and Tobago. The CRF creeps along a physical boundary between rocks associated with thermogenically generated petroleum in south and central Trinidad and rocks containing only biogenic gas to the north. Fluid (oil and gas) overpressure, in addition to weak material in the fault core, likely causes CRF creep.
Molecular basis for chirality-regulated Aβ self-assembly and receptor recognition revealed by ion mobility-mass spectrometry
Authors: Li Gongyu , DeLaney Kellen , Li Lingjun 
Published: November 2019

AbstractDespite extensive efforts on probing the mechanism of Alzheimer’s disease (AD) and enormous investments into AD drug development, the lack of effective disease-modifying therapeutics and the complexity of the AD pathogenesis process suggest a great need for further insights into alternative AD drug targets. Herein, we focus on the chiral effects of truncated amyloid beta (Aβ) and offer further structural and molecular evidence for epitope region-specific, chirality-regulated Aβ fragment self-assembly and its potential impact on receptor-recognition. A multidimensional ion mobility-mass spectrometry (IM-MS) analytical platform and in-solution kinetics analysis reveal the comprehensive structural and molecular basis for differential Aβ fragment chiral chemistry, including the differential and cooperative roles of chiral Aβ N-terminal and C-terminal fragments in receptor recognition. Our method is applicable to many other systems and the results may shed light on the potential development of novel AD therapeutic strategies based on targeting the D-isomerized Aβ, rather than natural L-Aβ.
Transcriptional dysregulation by a nucleus-localized aminoacyl-tRNA synthetase associated with Charcot-Marie-Tooth neuropathy
Authors: Bervoets Sven , Wei Na , Erfurth Maria-Luise , Yusein-Myashkova Shazie , Ermanoska Biljana , Mateiu Ligia , Asselbergh Bob , Blocquel David , Kakad Priyanka , Penserga Tyrone , Thomas Florian P , Guergueltcheva Velina , Tournev Ivailo , Godenschwege Tanja , Jordanova Albena , Yang Xiang-Lei 
Published: November 2019

AbstractCharcot-Marie-Tooth disease (CMT) is a length-dependent peripheral neuropathy. The aminoacyl-tRNA synthetases constitute the largest protein family implicated in CMT. Aminoacyl-tRNA synthetases are predominantly cytoplasmic, but are also present in the nucleus. Here we show that a nuclear function of tyrosyl-tRNA synthetase (TyrRS) is implicated in a Drosophila model of CMT. CMT-causing mutations in TyrRS induce unique conformational changes, which confer capacity for aberrant interactions with transcriptional regulators in the nucleus, leading to transcription factor E2F1 hyperactivation. Using neuronal tissues, we reveal a broad transcriptional regulation network associated with wild-type TyrRS expression, which is disturbed when a CMT-mutant is expressed. Pharmacological inhibition of TyrRS nuclear entry with embelin reduces, whereas genetic nuclear exclusion of mutant TyrRS prevents hallmark phenotypes of CMT in the Drosophila model. These data highlight that this translation factor may contribute to transcriptional regulation in neurons, and suggest a therapeutic strategy for CMT.
Structure and regulation of ZCCHC4 in m6A-methylation of 28S rRNA
Authors: Ren Wendan , Lu Jiuwei , Huang Mengjiang , Gao Linfeng , Li Dongxu , Wang Gang Greg , Song Jikui 
Published: November 2019

AbstractN6-methyladenosine (m6A) modification provides an important epitranscriptomic mechanism that critically regulates RNA metabolism and function. However, how m6A writers attain substrate specificities remains unclear. We report the 3.1 Å-resolution crystal structure of human CCHC zinc finger-containing protein ZCCHC4, a 28S rRNA-specific m6A methyltransferase, bound to S-adenosyl-L-homocysteine. The methyltransferase (MTase) domain of ZCCHC4 is packed against N-terminal GRF-type and C2H2 zinc finger domains and a C-terminal CCHC domain, creating an integrated RNA-binding surface. Strikingly, the MTase domain adopts an autoinhibitory conformation, with a self-occluded catalytic site and a fully-closed cofactor pocket. Mutational and enzymatic analyses further substantiate the molecular basis for ZCCHC4-RNA recognition and a role of the stem-loop structure within substrate in governing the substrate specificity. Overall, this study unveils unique structural and enzymatic characteristics of ZCCHC4, distinctive from what was seen with the METTL family of m6A writers, providing the mechanistic basis for ZCCHC4 modulation of m6A RNA methylation.
Nestin regulates cellular redox homeostasis in lung cancer through the Keap1–Nrf2 feedback loop
Authors: Wang Jiancheng , Lu Qiying , Cai Jianye , Wang Yi , Lai Xiaofan , Qiu Yuan , Huang Yinong , Ke Qiong , Zhang Yanan , Guan Yuanjun , Wu Haoxiang , Wang Yuanyuan , Liu Xin , Shi Yue , Zhang Kang , Wang Maosheng , Peng Xiang Andy 
Published: November 2019

AbstractAbnormal cancer antioxidant capacity is considered as a potential mechanism of tumor malignancy. Modulation of oxidative stress status is emerging as an anti-cancer treatment. Our previous studies have found that Nestin-knockdown cells were more sensitive to oxidative stress in non-small cell lung cancer (NSCLC). However, the molecular mechanism by which Nestin protects cells from oxidative damage remains unclear. Here, we identify a feedback loop between Nestin and Nrf2 maintaining the redox homeostasis. Mechanistically, the ESGE motif of Nestin interacts with the Kelch domain of Keap1 and competes with Nrf2 for Keap1 binding, leading to Nrf2 escaping from Keap1-mediated degradation, subsequently promoting antioxidant enzyme generation. Interestingly, we also map that the antioxidant response elements (AREs) in the Nestin promoter are responsible for its induction via Nrf2. Taken together, our results indicate that the Nestin–Keap1–Nrf2 axis regulates cellular redox homeostasis and confers oxidative stress resistance in NSCLC.
A combination of chitooligosaccharide and lipochitooligosaccharide recognition promotes arbuscular mycorrhizal associations in Medicago truncatula
Authors: Feng Feng , Sun Jongho , Radhakrishnan Guru V. , Lee Tak , Bozsóki Zoltán , Fort Sébastien , Gavrin Aleksander , Gysel Kira , Thygesen Mikkel B. , Andersen Kasper Røjkjær , Radutoiu Simona , Stougaard Jens , Oldroyd Giles E. D. 
Published: November 2019

AbstractPlants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce chitooligosaccharides (COs) and lipo-chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment.