bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiocarbon in the Land and Ocean Components of the Community Earth System Model
Authors: Frischknecht Tobias , Ekici Altug , Joos Fortunat 
Published: December 2021

AbstractLarge amounts of the carbon‐isotope 14C, entering Earth's carbon cycle, were produced in the atmosphere by atomic bomb tests in the 1950s and 1960s. Here, we forced the ocean and land components of the Community Earth System Model with atmospheric 14CO2 over the historical period to constrain overturning time scales and fluxes. The uptake of bomb 14C by the land model is lower than observation‐based estimates. This mismatch is likely linked to too‐low 14C uptake by vegetation as the model overestimates 14C/C ratios of modern soils. This suggests model biases in forest productivity or wood carbon allocation and turnover, and, in turn, a bias in the forest sink of anthropogenic carbon. The ocean model matches the observation‐based global bomb 14C inventories when applying the quadratic relationship between gas transfer piston velocity and wind speed of Wanninkhof (2014), https://doi.org/10.4319/lom.2014.12.351 and the wind products from Large and Yeager or the Japanese Reanalysis Project. Simulated natural radiocarbon ages in the deep ocean are many centuries older than data‐based estimates, indicating too slow deep ocean ventilation. The sluggish circulation causes large biases in biogeochemical tracers and implies a delayed deep ocean uptake of heat and carbon in global warming projections. Our study suggests that 14C observations are key to constrain carbon fluxes and transport timescales for improved representations of land and ocean biogeochemical cycles and Earth system model projections.
A Marginal Stability Paradigm for Shear‐Induced Diapycnal Turbulent Mixing in the Ocean
Authors: Mashayek A. , Baker L. E. , Cael B. B. , Caulfield C. P. 
Published: December 2021

AbstractTurbulent mixing induced by breaking internal waves is key to the ocean circulation and global tracer budgets. While the classic marginal shear instability of Richardson number ∼1/4 has been considered as potentially relevant to turbulent wave breaking, its relevance to flows that are not steady parallel shear flows has been suspect. We show that shear instability is indeed relevant in the ocean interior and propose a new marginal stability paradigm that relates the stability criterion based on Richardson number to one based on the ratio of Ozmidov and Thorpe turbulence scales. The new paradigm applies to both ocean interior and boundary layer flows. This allows for accurate quantification of the transition from downwelling to upwelling zones in a recently emerged paradigm of ocean circulation. Our results help climate models more accurately calculate the mixing‐driven deep ocean circulation and fluxes of tracers in the ocean interior.
San Andreas Fault Stress Change Due To Groundwater Withdrawal in California's Central Valley, 1860‐2010
Authors: Lundgren Paul , Liu Zhen , Ali S. Tabrez 
Published: December 2021

AbstractChanges in groundwater storage in California's Central Valley (CV) are considered partly responsible for vertical uplift surrounding the southern CV and for stress changes on nearby faults. Questions remain regarding the distribution of stress on the central San Andreas fault (CSAF) from recent and historical drawdown of the CV aquifer over the past 150 years (1860–2010). We combine groundwater storage change estimates for the 2006–2010 drought with a three‐dimensional finite element model to estimate Coulomb failure stress change (ΔCFS) on the CSAF. We combine a simple parameterization of historical hydraulic head change for 1860–1960 with a CV hydrological model (1961–2003) to estimate visco‐elastic effects on ΔCFS total and 2010 rate. We find that ΔCFS on the CSAF correlates positively with shallow seismicity and low frequency earthquakes for both short‐term and long term stressing. Unloading uplift rates surrounding the southern CV only partially account for the observed vertical GPS rates.
Multiple Leaking Mode Dispersion Observations and Applications From Ambient Noise Cross‐Correlation in Oklahoma
Authors: Li Zhengbo , Shi Caiwang , Ren Hengxin , Chen Xiaofei 
Published: December 2021

AbstractSurface wave imaging based on the normal modes extracted via ambient noise cross‐correlation has become a popular seismological technique during the last two decades. In addition to normal modes, which occupy most seismic wave energy, leaking modes with much weaker energy can also be obtained from ambient noise cross‐correlation. We report the observation of multimodal leaking mode dispersion curves retrieved from the cross‐correlation of ambient noise recorded by the LArge‐n Seismic Survey in Oklahoma array. The extracted leaking modes are closely related to the guided wave dispersion resulting from the layered P‐wave velocity (Vp) structure; hence, these modes can be used to invert the Vp structure. Moreover, the joint inversion of leaking modes and normal modes can not only accurately acquire the Vp structure but also effectively improve the fitness of normal modes from the inversion of only normal modes.
A New Parameterization of Turbulent Mixing Enhanced Over Rough Seafloor Topography
Authors: Hibiya Toshiyuki 
Published: December 2021

AbstractExisting parameterizations of turbulent mixing enhanced over high‐wavenumber seafloor topography miss the fact that internal tidal waves emanating from the seafloor transform to internal lee waves as the tide‐topography interaction strengthens. This motivates us to replace the vertical decay scale of bottom‐enhanced turbulent mixing with the “vertical mean free path” of internal lee waves, namely, the average vertical distance over which internal lee waves propagate until they discharge their energy through interactions with the background internal waves. The resulting formula shows that the vertical extent of turbulent mixing becomes proportional to the abyssal barotropic tidal or steady flow amplitude squared and the inverse abyssal buoyancy frequency squared, but independent of the wavenumber of the seafloor, consistent with recent eikonal calculations and field observations. We propose a new parameterization of turbulent mixing enhanced over high‐wavenumber seafloor topography through incorporating the formulated vertical decay scale.
Post‐Perovskite Phase Transition in the Pyrolitic Lowermost Mantle: Implications for Ubiquitous Occurrence of Post‐Perovskite Above CMB
Authors: Kuwayama Yasuhiro , Hirose Kei , Cobden Laura , Kusakabe Mayu , Tateno Shigehiko , Ohishi Yasuo 
Published: December 2021

AbstractWe conducted in situ high‐pressure and ‐temperature X‐ray diffraction measurements of a pyrolitic mantle material up to 4480 K at 122–166 GPa in a laser‐heated diamond anvil cell. Results demonstrate that the phase transition between bridgmanite and post‐perovskite occurs in pyrolite within the lowermost mantle pressure range even at >4000 K. It suggests the ubiquitous occurrence of post‐perovskite above the core‐mantle boundary, which may be consistent with recent high‐quality seismology data that non‐observations of D” reflections are exceptions. Combining with earlier experiments performed at and below the normal lower‐mantle geotherm, our data show that the bridgmanite + post‐perovskite two‐phase region is ∼5 GPa thick and the dP/dT slope of the boundary is +6.5 ± 2.2 MPa/K, slightly smaller than previous theoretical calculations in MgSiO3. The global presence of rheologically weak post‐perovskite at the bottom of the mantle has profound implications in seismology, geodynamics, and heat transfer from the core.
Unsteady Magnetopause Reconnection Under Quasi‐Steady Solar Wind Driving
Authors: Zou Ying , Walsh Brian M. , Chen Li‐Jen , Ng Jonathan , Shi Xueling , Wang Chih‐Ping , Lyons Larry R. , Liu Jiang , Angelopoulos Vassilis , McWilliams Kathryn A. , Michael Ruohoniemi J. 
Published: December 2021

AbstractThe intrinsic temporal nature of magnetic reconnection at the magnetopause has been an active area of research. Both temporally steady and intermittent reconnection have been reported. We examine the steadiness of reconnection using space‐ground conjunctions under quasi‐steady solar wind driving. The spacecraft suggests that reconnection is first inactive, and then activates. The radar further suggests that after activation, reconnection proceeds continuously but unsteadily. The reconnection electric field shows variations at frequencies below 10 mHz with peaks at 3 and 5 mHz. The variation amplitudes are ∼10–30 mV/m in the ionosphere, and 0.3–0.8 mV/m at the equatorial magnetopause. Such amplitudes represent 30%–60% of the peak reconnection electric field. The unsteadiness of reconnection can be plausibly explained by the fluctuating magnetic field in the turbulent magnetosheath. A comparison with a previous global hybrid simulation suggests that it is the foreshock waves that drive the magnetosheath fluctuations, and hence modulate the reconnection.
Discovering spatiotemporal patterns of COVID-19 pandemic in South Korea
Authors: Kim Sungchan , Kim Minseok , Lee Sunmi , Lee Young Ju 
Published: December 2021

AbstractA novel severe acute respiratory syndrome coronavirus 2 emerged in December 2019, and it took only a few months for WHO to declare COVID-19 as a pandemic in March 2020. It is very challenging to discover complex spatial–temporal transmission mechanisms. However, it is crucial to capture essential features of regional-temporal patterns of COVID-19 to implement prompt and effective prevention or mitigation interventions. In this work, we develop a novel framework of compatible window-wise dynamic mode decomposition (CwDMD) for nonlinear infectious disease dynamics. The compatible window is a selected representative subdomain of time series data, in which compatibility between spatial and temporal resolutions is established so that DMD can provide meaningful data analysis. A total of four compatible windows have been selected from COVID-19 time-series data from January 20, 2020, to May 10, 2021, in South Korea. The spatiotemporal patterns of these four windows are then analyzed. Several hot and cold spots were identified, their spatial–temporal relationships, and some hidden regional patterns were discovered. Our analysis reveals that the first wave was contained in the Daegu and Gyeongbuk areas, but it spread rapidly to the whole of South Korea after the second wave. Later on, the spatial distribution is seen to become more homogeneous after the third wave. Our analysis also identifies that some patterns are not related to regional relevance. These findings have then been analyzed and associated with the inter-regional and local characteristics of South Korea. Thus, the present study is expected to provide public health officials helpful insights for future regional-temporal specific mitigation plans.
Analysis of bone transport for ankle arthrodesis as a limb salvage procedure for the treatment of septic pilon fracture nonunion
Authors: Rosteius Thomas , Lotzien Sebastian , Königshausen Matthias , Rausch Valentin , Cibura Charlotte , Behr Björn , Lehnhardt Markus , Schildhauer Thomas Armin , Geßmann Jan 
Published: December 2021

AbstractSeptic nonunion of the pilon region with ankle joint infection is challenging for orthopedic surgeons to treat and is associated with a high risk of limb loss. Therefore, the aim of this study was to evaluate the effectiveness of bone transport for ankle arthrodesis in salvaging the limp after septic ankle destruction of the pilon region. We conducted a single-center, retrospective study including 21 patients treated for septic pilon nonunion with accompanying septic ankle destruction via Ilizarov bone transport between 2004 and 2018. In all cases, the complete excision of the nonunion and the resection of the ankle joint were carried out, followed by treating the bone and joint defect with a bone transport into the ankle arthrodesis. In 12/21 patients an additional flap transfer was required due to an accompanying soft tissue lesion. The overall healing and failure rate, final alignment and complications were recorded by the patients’ medical files. The bone-related and functional results were evaluated according to the Association for the Study and Application of Methods of Ilizarov (ASAMI) scoring system and a modified American Orthopedic Foot and Ankle Society (AOFAS) scale. After a mean follow-up of 30.9 ± 15.7 months (range 12–63 months), complete bone and soft tissue healing occurred in 18/21 patients (85.7%). The patients had excellent (5), good (7), fair (4), and poor (3) results based on the ASAMI functional score. Regarding bone stock, 6 patients had excellent, 7 good, and 6 fair results. The modified AOFAS score reached 60.6 ± 18 points (range, 29–86). In total, 33 minor complications and 28 major complications occurred during the study period. In 2 cases, a proximal lower leg amputation was performed due to a persistent infection and free flap necrosis with a large soft tissue defect, whereas in one case, persistent nonunion on the docking side was treated with a carbon orthosis because the patient refused to undergo an additional surgery. Bone transport for ankle arthrodesis offers the possibility of limb salvage after septic ankle destruction of the pilon region, with acceptable bony and functional results. However, a high number of complications and surgical revisions are associated with the treatment of this severe complication after pilon fracture.
Hybrid flux predictor‐based predictive flux control of permanent magnet synchronous motor drives
Authors: Fu Rong , Cao Yang 
Published: December 2021

AbstractIn the field of a model predictive control of a permanent magnet synchronous motor (PMSM), the predictive flux control (PFC) has received great attention, which only takes the stator flux vector as the control variable instead of the electromagnetic torque and the stator flux amplitude. Because PFC does not involve the cumbersome setting of weight factors, it is a promising control algorithm. However, the prediction of the stator flux vector depends on motor parameters, which inevitably reduces the robustness of the control system. In order to solve this problem, this paper proposes a hybrid flux predictor‐based predictive flux control of PMSM drives. The proposed stator flux predictor combines the voltage prediction model and the current prediction model, and the proportional–integral regulator is utilised to control the switching between the two prediction models. Experimental results show that the proposed algorithm has better dynamic, steady‐state and robust performances than the traditional predictive flux control.
Characteristics of pantograph‐catenary arc under low air pressure and strong airflow
Authors: Xu Zhilei , Gao Guoqiang , Wei Wenfu , Yang Zefeng , Xie Wenhan , Dong Keliang , Ma Yaguang , Yang Yan , Wu Guangning 
Published: December 2021

AbstractPantograph‐catenary arc fault is the primary factor threatening the stability of the power transmission for high‐speed railway. The motion characteristics of the pantograph‐catenary arc under low air pressure and strong airflow is significantly different from the case under atmospheric pressure. In this paper, an experimental platform of pantograph‐catenary arc was built to investigate arc root position‐time and arc column longitudinal drift height‐time characteristic curves under different air pressures and airflow velocites. Via analysing the corresponding results, it can be found that there are different arc root–arc column traction mechanisms at different stages of arc development. The arcing time and arc root stagnation time under low air pressure are significantly longer than the case under atmospheric pressure, resulting in more serious electrode ablation. The arc column longitudinal drift velocity and height are greater with the increase of airflow velocity. Two typical irregular arc motion phenomena—arc root jumping and arc reignition are observed. To clarify the internal mechanism of the above phenomenon, a magnetohydrodynamics (MHD) model of the pantograph‐catenary arc was lauched, the influence mechanism of the pantograph‐catenary arc temperature and voltage are studied, and the physical process of arc temperature oscillation is analysed. The research results provide theoretical support for arc protection in high‐altitude areas.
Evaluation of the ICRF stability from a position time series analysis
Authors: Liu N. , Lambert S. B. , Arias E. F. , Liu J.-C. , Zhu Z. 
Published: December 2021

Context. The celestial reference frame is established on the basis of the absolute positions of extragalactic sources that are assumed to be fixed in space. The fixing of the axes is one of the crucial points for the concept behind the International Celestial Reference System (ICRS). However, due to various effects such as its intrinsic activity, the apparent position of the extragalactic sources may vary with time, resulting in a time-dependent deviation of the frame axes that are defined by the positions of these sources.
Aims. We aim to evaluate the axis stability of the third realization of the International Celestial Reference Frame (ICRF3).
Methods. We first derived the extragalactic source position time series from observations of very long baseline interferometry (VLBI) at the dual S∕X-band (2.3/8.4 GHz) between August 1979 and December 2020. We measured the stability of the ICRF3 axes in terms of the drift and scatter around the mean: (i) we estimated the global spin of the ICRF3 axes based on the apparent proper motion (slope of the position time series) of the defining sources of the ICRF3; (ii) we also constructed the yearly representations of the ICRF3 through annually averaged positions of the defining sources of the ICRF3 and estimated the dispersion in the axes orientation of these yearly frames.
Results. The global spin is no higher than 0.8 μas yr-1 for each ICRF3 axis with an uncertainty of 0.3 μas yr-1, corresponding to an accumulated deformation smaller than 30 μas for the celestial frame axes during 1979.6–2021.0. The axes orientation of the yearly celestial frame becomes more stable as time elapses, with a standard deviation of 10 μas–20 μas for each axis.
Conclusions. The axes of the ICRF3 are stable at approximately 10 μas–20 μas from 1979.6–2021.0 and the axes stability does not degrade after the adoption of the ICRF3.
UV-enhanced NO2 gas sensors based on In2O3/ZnO composite material modified by polypeptides
Authors: Ying Zhihua , Zhang Teng , Feng Chao , Wen Fei , Li Lili , Zheng Xiaolong , Zheng Peng , Wang Gaofeng 
Published: December 2021

Abstract
This present study reported a high-performance gas sensor, based on In2O3/ZnO composite material modified by polypeptides, with a high sensibility to NO2, where the In2O3/ZnO composite was prepared by a one-step hydrothermal method. A series of results through material characterization technologies showed the addition of polypeptides can effectively change the morphology and size of In2O3/ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In2O3/ZnO composite modified by polypeptides increased the active sites on the surface. At the same time, the gas sensing properties of four different ratios of polypeptide-modified In2O3/ZnO gas sensors were tested. It was found that the In2O3/ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In2O3/ZnO-10 gas sensor showed a strong linear relationship with the NO2 gas concentration. When the NO2 gas concentration was 20 ppm, the response time was as quick as 19 s, and the recovery time was 57 s. Finally, based on the obtained experimental characterization results and energy band structure analysis, a possible gas sensing mechanism is proposed.
Flexible silicon nanowires sensor for acetone detection on plastic substrates
Authors: Lan Kuibo , Wang Zhi , Yang Xiaodong , Wei Junqing , Qin Yuxiang , Qin Guoxuan 
Published: December 2021

Abstract
Acetone commonly exists in daily life and is harmful to human health, therefore the convenient and sensitive monitoring of acetone is highly desired. In addition, flexible sensors have the advantages of light-weight, conformal attachable to irregular shapes, etc. In this study, we fabricated high performance flexible silicon nanowires (SiNWs) sensor for acetone detection by transferring the monocrystalline Si film and metal-assisted chemical etching method on polyethylene terephthalate (PET). The SiNWs sensor enabled detection of gaseous acetone with a concentration as low as 0.1 parts per million (ppm) at flat and bending states. The flexible SiNWs sensor was compatible with the CMOS process and exhibited good sensitivity, selectivity and repeatability for acetone detection at room temperature. The flexible sensor showed performance improvement under mechanical bending condition and the underlying mechanism was discussed. The results demonstrated the good potential of the flexible SiNWs sensor for the applications of wearable devices in environmental safety, food quality, and healthcare.
Collapse arrest in a two-dimensional Airy Gaussian beam and Airy Gaussian vortex beam in nonlocal nonlinear media
Authors: Chen Ye , Ge Lijuan , Wang Xinglin , Shen Ming 
Published: December 2021

Abstract
Propagation dynamics of a two-dimensional Airy Gaussian beam and Airy Gaussian vortex beam are investigated numerically in local and nonlocal nonlinear media. The self-healing and collapse of the beam crucially depend on the distribution factor b and the topological charge m. With the aid of nonlocality, a stable Airy Gaussian beam and an Airy Gaussian vortex beam with larger amplitude can be obtained, which always collapse in local nonlinear media. When the distribution factor b is large enough, the Airy Gaussian vortex beam will transfer into quasi-vortex solitons in nonlocal nonlinear media.
Few-photon routing via chiral light-matter couplings
Authors: Yang Ya , Lu Jing , Zhou Lan 
Published: December 2021

Abstract
A quantum router is one of the essential elements in the quantum network. Conventional routers only direct a single photon from one quantum channel into another. Here, we propose a few-photon router. The active element of the router is a single qubit chirally coupled to two independent waveguides simultaneously, where each waveguide mode provides a quantum channel. By introducing the operators of the scatter-free space and the controllable space, the output state of the one-photon and two-photon scattering are derived analytically. It is found that the qubit can direct one and two photons from one port of the incident waveguide to an arbitrarily selected port of the other waveguide with unity, respectively. However, two photons cannot be simultaneously routed to the same port due to the anti-bunch effect.
Spatial Distribution of HOCN Around Sagittarius B2
Authors: Zheng Si-Qi , Li Juan , Wang Jun-Zhi , Gao Feng , Wu Ya-Jun , Liu Shu , Li Shang-Huo 
Published: December 2021

Abstract
HOCN and HNCO abundance ratio in molecular gas can tell us the information of their formation mechanism. We performed high-sensitivity mapping observations of HOCN, HNCO, and HNC18O lines around Sagittarius B2 (Sgr B2) with the IRAM 30 m telescope at the 3 mm wavelength. HNCO 404–303 and HOCN 404–303 are used to obtain the abundance ratio of HNCO to HOCN. The ratio of HNCO 404–303 to HNC18O 404–303 is used to calculate the optical depth of HNCO 404–303. The abundance ratio of HOCN and HNCO is observed to range from 0.4% to 0.7% toward most positions, which agrees well with the gas-grain model. However, the relative abundance of HOCN is observed to be enhanced toward the direction of Sgr B2 (S), with HOCN to HNCO abundance ratio of ∼0.9%. The reason for that still needs further investigation. Based on the intensity ratio of HNCO and HNC18O lines, we updated the isotopic ratio of 16O/18O to be 296 ± 54 in Sgr B2.