bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climatic and Tectonic Control on the Bengal Fan Sedimentation Since the Pliocene
Authors: Peketi A. , Mazumdar A. , Pillutla S. P. K. , Sawant B. , Gupta H. 
Published: February 2021

AbstractStrontium and Neodymium isotopic analysis of the lithogenic fractions of the hole U1445A (International Ocean Discovery Program‐353) collected from the deep‐water end of the Mahanadi basin (western Bay of Bengal) was carried out to evaluate the sediment sources as well as to understand the link between the temporal variations in the Sr‐Nd isotope ratios and climatic and tectonic forcings during the last 6 Ma. The Sr‐Nd isotopic compositions along with Fe/Al ratios and clay mineralogy show tell‐tale signature of Ganga‐Brahmaputra sedimentation (Bengal fan) in the study area. The significant temporal fluctuations observed in the Sr‐Nd isotopic compositions suggest variation in the relative sediment contribution by the Ganga and Brahmaputra river systems, which in turn are controlled by monsoon intensity variations coupled with orographic effect, glaciation, and multiple tectonic activities. The results show the marked influence of glacial‐interglacials on the relative sediment contribution by Ganga and Brahmaputra rivers during 0–1.8 Ma, while the sedimentation during the 1.8–6 Ma time window was likely influenced by both climatic and tectonic forcings such as uplift of the Shillong plateau, eastern syntaxis development of Indo‐Burma wedge, reorganization of Brahmaputra river system. The present study is the first high resolution (122 samples within 6 Ma) Sr‐Nd isotope ratio analysis from the Bengal Fan. The study has brought to light multiple isotope fluctuations linked to climatic and tectonic forcings. The work also establishes dominant control of Ganga‐Brahmaputra sedimentation along the deep waters of the Indian east coast.
Energy‐Resolved Detection of Precipitating Electrons of 30–100 keV by a Sounding Rocket Associated With Dayside Chorus Waves
Authors: Sugo S. , Kawashima O. , Kasahara S. , Asamura K. , Nomura R. , Miyoshi Y. , Ogawa Y. , Hosokawa K. , Mitani T. , Namekawa T. , Sakanoi T. , Fukizawa M. , Yagi N. , Fedorenko Y. , Nikitenko A. , Yokota S. , Keika K. , Hori T. , Koehler C. 
Published: February 2021

AbstractWhistler mode chorus waves scatter magnetospheric electrons and cause precipitation into the Earth's atmosphere. Previous measurements showed that nightside chorus waves are indeed responsible for diffuse/pulsating aurora. Although chorus waves and electron precipitation have also been detected on the dayside, their link has not been illustrated (or demonstrated) in detail compared to the nightside observations. Conventional low‐altitude satellite observations do not well resolve the energy range of 10–100 keV, hampering verification on resonance condition with chorus waves. In this paper we report observations of energetic electrons with energies of 30–100 keV that were made by the electron sensor installed on the NASA's sounding rocket RockSat‐XN. It was launched from the Andøya Space Center on the dayside (MLT ∼ 11 h) at the L‐value of ∼7 on January 13, 2019. Transient electron precipitation was observed at ∼50 keV with the duration of <100 s. The VLF receiver of a ground station at Kola peninsula in Russia near the rocket's footprint observed intermittent emissions of whistler‐mode waves at the VLF frequency range simultaneously with the rocket observations. The energy of precipitating electrons is consistent with those derived from the quasilinear theory of pitch angle scattering by chorus waves through cyclotron resonance, assuming a typical dayside magnetospheric electron density. Precise interaction region is discussed based on the obtained energy spectrum below 100 keV.
Evidence for the Significant Differences in Response Times of Equatorial Ionization Anomaly Crest Corresponding to Plasma Fountains During Daytime and Post‐Sunset Hours
Authors: Kumar A. , Chakrabarty D. , Pandey K. , Fejer B. G. , Sunda S. , Seemala G. K. , Sripathi S. , Yadav A. K. 
Published: February 2021

AbstractBased on 10 years' (2010–2019) of vertical total electron content (VTEC) data from Ahmedabad (23.0°N, 72.6°E, dip angle 35.2°) and campaign based OI 630.0 nm airglow intensity measurements from Mt. Abu (24.6°N, 72.7°E, dip angle 38.0°), it is shown that plasma density over the equatorial ionization anomaly (EIA) crest region increases in varying degrees during post‐sunset hours (2000–2100 LT) in magnetically quiet periods. The post‐sunset peak in VTEC precedes the corresponding peak in airglow intensity. By comparing post‐sunset VTEC enhancements with ionosonde observations from Tirunelveli (8.7°N, 77.7°E, dip angle 1.7°), it is shown that pre‐reversal enhancement (PRE) of the zonal electric field causes these enhancements over the EIA crest region. These observations are supported by TEC measurements by GAGAN (GPS Aided Geo Augmented navigation), the Indian Satellite‐based Augmentation System (SBAS). Comparison of average VTEC variations with global empirical model drifts reveals that the post‐sunset enhancements in VTEC occurs ∼1.7 h after the PRE and are significant only during December solstice and equinoctial months in high solar activity years similar to seasonal variations in PRE amplitudes. This time delay (response time of EIA crest) is almost half compared to the average response time (3–4 h) associated with the daytime fountain. Based on the latitudinal gradient in SBAS‐TEC, it is proposed that the PRE drives plasma from 5°N to 10°N magnetic latitudes to the EIA crest region leading to shorter response time. These results show the important role of the PRE in conditioning the EIA crest region.
Latitudinal Variations of Daytime Periodic Ionospheric Disturbances From Beidou GEO TEC Observations Over China
Authors: Hu Lianhuan , Lei Jiuhou , Sun Wenjie , Zhao Xiukuan , Wu Baoyuan , Xie Haiyong , Yang Sipeng , Wu Zhi , Zheng Jianchang , Ning Baiqi , Ding Feng , Li Guozhu 
Published: February 2021

AbstractUsing total electron content (TEC) data from a chain of Beidou geostationary satellite TEC receivers along ∼110°E during 2016–2019, the local time, seasonal, and latitudinal occurrence characteristics of periodic TEC perturbation associated with medium scale traveling ionospheric disturbances (MSTIDs) are investigated. The results show that the daytime periodic ionospheric disturbances appear prominently in winter with dominant periods ∼30–40 min. An interesting feature is that the latitudinal variations of periodic ionospheric disturbances show two occurrence peaks at higher and lower latitudes, with a minimum centering around 30°N‐33°N, where almost no periodic ionospheric disturbance was detected under the threshold of absolute TEC perturbation greater than 0.3 TECU. Further, using two short‐baseline GNSS receiver arrays at middle and low latitudes, the propagation characteristics of the periodic ionospheric disturbances were derived. The median values of propagation azimuth, phase velocity, and period of the ionospheric disturbances at middle (low) latitude are 153.1° (157.4°), 36.7 min (33 min), and 97.2 m/s (62.5 m/s), respectively, showing typical characteristics of MSTIDs. We surmise that the perturbation source and background electron density could play important roles in causing the latitudinal variation of daytime periodic ionospheric disturbances along 110°E.
Evaluating the Formation Pressure of Diamond‐Hosted Majoritic Garnets: A Machine Learning Majorite Barometer
Authors: Thomson A. R. , Kohn S. C. , Prabhu A. , Walter M. J. 
Published: February 2021

AbstractDiamond‐hosted majoritic garnet inclusions provide unique insights into the Earth's deep, and otherwise inaccessible, mantle. Compared with other types of mineral inclusions found in sub‐lithospheric diamonds, majoritic garnets can provide the most accurate estimates of diamond formation pressures because laboratory experiments have shown that garnet chemistry varies strongly as a function of pressure. However, evaluation using a compilation of experimental data demonstrates that none of the available empirical barometers are reliable for predicting the formation pressure of many experimental majoritic garnets and cannot be applied with confidence to diamond‐hosted garnet inclusions. On the basis of the full experimental data set, we develop a novel type of majorite barometer using machine learning algorithms. Cross validation demonstrates that Random Forest Regression allows accurate prediction of the formation pressure across the full range of experimental majoritic garnet compositions found in the literature. Applying this new barometer to the global database of diamond‐hosted inclusions reveals that their formation occurs in specific pressure modes. However, exsolved clinopyroxene components that are often observed within garnet inclusions are not included in this analysis. Reconstruction of inclusions, in the 8 cases where this is currently possible, reveals that ignoring small exsolved components can lead to underestimating inclusion pressures by up to 7 GPa (∼210 km). The predicted formation pressures of majoritic garnet inclusions are consistent with crystallization of carbon‐rich slab‐derived melts in Earth's deep upper mantle and transition zone.
Authigenic Iron Sulfides Indicate Sea‐Level Change on the Continental Shelf: An Illustration From the East China Sea
Authors: Liu Jianxing , Shi Xuefa , Liu Qingsong , Liu Shengfa , Liu Yan , Zhang Qiang , Yu Xiaoxiao , Fang Xisheng , Wu Yonghua , Xu Taoyu , Li Jinhua 
Published: February 2021

AbstractAlthough sea‐level is the primary control over sedimentary architectures on continental shelves, deciphering such changes is still challenging, except for the easily recognized transgression‐regression cycles. This problem becomes more prominent in sedimentary units with relatively homogenous and fine‐grained lithologies that have been deposited over short periods. Here, we focus on a dominantly clayey silt section of a sediment core from the outer shelf of the East China Sea. Detailed rock magnetic and electron microscopy analyses indicate that authigenic greigite (Fe3S4) is the major magnetic component in an almost 4‐m‐thick interval that was deposited during the late Marine Isotope Stage (MIS) 3, while pyrite (FeS2) is enriched in the underlying middle MIS 3 sediments. According to microfossil analyses, the identified greigite formed in a prodelta setting that was affected by cold coastal currents after the middle MIS 3, when the Taiwan Warm Current and its associated upwelling were prevailing within a middle‐outer shelf setting favorable for pyrite formation. Large‐amplitude regression occurred subsequently during the MIS 2, limiting sulfate supply and favoring the greigite preservation. Our results, along with the previous studies, demonstrate that both the material and environmental conditions that are crucial to iron sulfide survival have been largely controlled by sea‐level change. Moreover, we make a preliminary proposition that a water depth range of 30–60 m is more likely to lead to the enrichment of greigite on continental shelves. We, therefore, provide a promising avenue for the assessment of sea‐level change on continental shelves over orbital and even suborbital timescales.
First Focal Mechanisms of Marsquakes
Authors: Brinkman Nienke , Stähler Simon C. , Giardini Domenico , Schmelzbach Cédric , Khan Amir , Jacob Alice , Fuji Nobuaki , Perrin Clement , Lognonné Philippe , Beucler Eric , Böse Maren , Ceylan Savas , Charalambous Constantinos , Clinton John F. , van Driel Martin , Euchner Fabian , Horleston Anna , Kawamura Taichi , Knapmeyer‐Endrun Brigitte , Mainsant Guenole , Panning Mark P. , Pike William T. , Scholz John‐Robert , Robertsson Johan O. A. , Banerdt William B. 
Published: February 2021

AbstractSince February 2019, NASA's InSight lander is recording seismic signals on the planet Mars, which, for the first time, allows to observe ongoing tectonic processes with geophysical methods. A number of Marsquakes have been located in the Cerberus Fossae graben system in Elysium Planitia and further west, in the Orcus Patera depression. We present a first study of the focal mechanisms of three well‐recorded events (S0173a, S0183a, S0235b) to determine the processes dominating in the source region. We infer for all three events a predominantly extensional setting. Our method is adapted to the case of a single, multicomponent receiver and based on fitting waveforms of P and S waves against synthetic seismograms computed for the initial crustal velocity model derived by the InSight team. We explore the uncertainty due to the single‐station limitation and find that even data recorded by one station constrains the mechanisms (reasonably) well. For the events in the Cerberus Fossae region (S0173a, S0235b) normal faulting with a relatively steep dipping fault plane is inferred, suggesting an extensional regime mainly oriented E‐W to NE‐SW. The fault regime in the Orcus Patera region is not determined uniquely because only the P wave can be used for the source inversion. However, we find that the P and weak S waves of the S0183a event show similar polarities to the event S0173, which indicates similar fault regimes.
Enhancements of Himalayan and Tibetan Erosion and the Produced Organic Carbon Burial in Distal Tropical Marginal Seas During the Quaternary Glacial Periods: An Integration of Sedimentary Records
Authors: Xu Zhaokai , Wan Shiming , Colin Christophe , Clift Peter D. , Chang Fengming , Li Tiegang , Chen Hongjin , Cai Mingjiang , Yu Zhaojie , Lim Dhongil 
Published: February 2021

AbstractThe Himalayan and Tibetan highlands (mountains), with high rates of physical erosion, are extreme settings for earth surface processes, generating one of the largest recent terrigenous detritus and organic carbon discharges to the ocean. However, their significance with respect to the global carbon and climate cycles during the Quaternary is still unclear, especially in quantitative terms. Here, we present comprehensive records of continental erosion and weathering, terrestrial supply, marine productivity, and organic carbon burial in the distal Arabian Sea, Bay of Bengal, and southern South China Sea since ∼700 ka over orbital timescales. These records exhibit periodicities corresponding to sea level and Indian summer monsoon intensity changes. During glacial periods, the enhanced highland surface erosion and activation of deep‐sea channels significantly increased inputs of terrigenous detritus, nutrients, and organic carbon into the Arabian Sea and Bay of Bengal, whereas strengthened continental shelf surface weathering and organic matter preservation occurred in the South China Sea. Conclusively, our integrative proxies in the study area demonstrate, for the first time, pronounced glacial burial pulses of organic carbon (∼1.12 × 1012 mol/yr), dominantly originating from the highland surface erosion and marine productivity. Together with the increased silicate weathering on the exposed tropical continental shelves and in the tropical volcanic arcs, the enhanced burial flux of organic carbon in the tropical marginal seas, therefore, highlights the large contributions that tropical regions can make within the glacial‐interglacial carbon inventory of the ocean and atmosphere and thus cause significant negative feedback on the global climate.
A Binomial Stochastic Framework for Efficiently Modeling Discrete Statistics of Convective Populations
Authors: Neggers Roel A. J. , Griewank Philipp J. 
Published: February 2021

AbstractUnderstanding the coupling between convective clouds and the general circulation, as well as addressing the gray zone problem in convective parameterization, requires insight into the genesis and maintenance of spatial patterns in cumulus cloud populations. In this study, a simple toy model for recreating populations of interacting convective objects as distributed over a two‐dimensional Eulerian grid is formulated to this purpose. Key elements at the foundation of the model include i) a fully discrete formulation for capturing discrete behavior in convective properties at small population sample sizes, ii) object age‐dependence for representing life‐cycle effects, and iii) a prognostic number budget allowing for object interactions and co‐existence of multiple species. A primary goal is to optimize the computational efficiency of this system. To this purpose the object birth rate is represented stochastically through a spatially aware Bernoulli process. The same binomial stochastic operator is applied to horizontal advection of objects, conserving discreteness in object number. The applicability to atmospheric convection as well as behavior implied by the formulation is assessed. Various simple applications of the BiOMi model (Binomial Objects on Microgrids) are explored, suggesting that important convective behavior can be captured at low computational cost. This includes i) subsampling effects and associated powerlaw scaling in the convective gray zone, ii) stochastic predator‐prey behavior, iii) the downscale turbulent energy cascade, and iv) simple forms of spatial organization and convective memory. Consequences and opportunities for convective parameterization in next‐generation weather and climate models are discussed.
Implementation of a 1‐D Thermodynamic Model for Simulating the Winter‐Time Evolvement of Physical Properties of Snow and Ice Over the Arctic Ocean
Authors: Kang Eui‐Jong , Sohn Byung‐Ju , Tonboe Rasmus Tage , Dybkjær Gorm , Holmlund Kenneth , Kim Jong‐Min , Liu Chao 
Published: February 2021

AbstractThis paper presents a sea ice prognostic model involving a one‐dimensional thermodynamic diffusion model, nudging satellite‐derived snow/ice temperatures, and two‐dimensional Lagrangian ice tracking. The aim of the model is to produce the evolvement of the physical properties of the snow and ice over the Arctic Ocean during the winter season. While the one‐dimensional column process solves the solution at a specific time and location, the evolvement of physical properties of the same ice target can be continuously simulated along the trajectory of ice movement determined by the Lagrangian tracking method. The main inputs were reanalysis‐based atmospheric forcings, thermal conditions constrained through nudging of snow skin temperature and snow‐ice interface temperature, and satellite‐derived ice motion vectors. The simulation results showed that the model can successfully reproduce well‐known regional features and geographical distributions of snow depth and ice thickness. The model‐simulated variables (i.e., snow depth, total freeboard, ice freeboard, ice thickness, and temperature) showed high correlations with the in situ or satellite measurements. In particular, the simulated temperatures were in excellent agreement with drifting buoy measurements. Since the nudging of the satellite‐derived temperature data into the model improved the thermal structure considerably, these data appear to be a key element for the successful simulation of other variables as well.
Consensus of semi‐Markov multi‐agent systems with stochastically unmatched topologies
Authors: Wang Guoliang , Huang Yifan , Wang Xiaoqiang 
Published: February 2021

AbstractThis paper addresses the consensus problem of semi‐Markov multi‐agent systems, where the topology switching is stochastically unmatched to the original switching. The unmatched property is described by a stochastically conditional probability and quantized by a given transition probability density function (PDF). Then a consensus protocol based on the aforementioned topology is proposed and includes mode‐dependent and ‐independent control inputs as special cases. Based on the Lyapunov function approach and some enlarging techniques, sufficient LMI conditions are presented to solve the controller directly. All the features such as conditional probability, dwell time and transition probability are involved. An improved method but needing nonsingular expectation of the truncated PDF matrix is also proposed. A practical example is offered so as to verify the effectiveness and superiority of the methods proposed in this study.
Video super‐resolution with non‐local alignment network
Authors: Zhou Chao , Chen Can , Ding Fei , Zhang Dengyin 
Published: February 2021

AbstractVideo super‐resolution (VSR) aims at recovering high‐resolution frames from their low‐resolution counterparts. Over the past few years, deep neural networks have dominated the video super‐resolution task because of its strong non‐linear representational ability. To exploit temporal correlations, most deep neural networks have to face two challenges: (1) how to align consecutive frames containing motions, occlusions and blurring, and establish accurate temporal correspondences, (2) how to effectively fuse aligned frames and balance their contributions. In this work, a novel video super‐resolution network, named NLVSR, is proposed to solve above problems in an efficient and effective manner. For alignment, a temporal‐spatial non‐local operation is employed to align each frame to the reference frame. Compared with existing alignment approaches, the proposed temporal‐spatial non‐local operation is able to integrate the global information of each frame by a weighted sum, leading to a better performance in alignment. For fusion, an attention‐based progressive fusion framework was designed to integrate aligned frames gradually. To penalize the points with low‐quality in aligned features, an attention mechanism was employed for a robust reconstruction. Experimental results demonstrate the superiority of the proposed network in terms of quantitative and qualitative evaluation, and surpasses other state‐of‐the‐art methods by 0.33 dB at least.
Optimization of Coumarins Extraction from Pterocaulon balansae by Box-Behnken Design and Anti-Trichomonas vaginalis Activity
Authors: Brazil Nathalya Tesch , Medeiros-Neves Bruna , Fachel Flávia Nathiely Silveira , Pittol Vanessa , Schuh Roselena Silvestri , Rigo Graziela Vargas , Tasca Tiana , von Poser Gilsane Lino , Teixeira Helder Ferreira 
Published: February 2021

Abstract
Trichomonas vaginalis causes trichomoniasis, a nonviral sexually transmitted infection with a high prevalence worldwide. Oral metronidazole is the drug of choice for the treatment of this disease, although high levels of T. vaginalis resistance to this agent are well documented in the literature. This study describes the anti-T. vaginalis activity of an optimized coumarin-rich extract from Pterocaulon balansae. Optimization was performed to maximize extraction of total coumarins by means of a 3-level Box-Behnken design, evaluating the effect of three factors: extraction time, plant : solvent ratio, and ethanol concentration. Optimum conditions were found to be 5 h extraction time and a plant : solvent ratio of 1% (w/v) and 60% (v/v) ethanol, which resulted in approximately 30 mg of total coumarins/g of dry plant. The coumarin-enriched extract exhibited a minimum inhibitory concentration of 30 µg/mL and an IC50 of 3.2 µg/mL against
T. vaginalis, a low cytotoxicity, and a high selectivity index (18 for vaginal epithelial cells and 16 for erythrocytes). The coumarins permeation/retention profile through porcine vaginal mucosa was evaluated in Franz-type diffusion cells. After 8 h of kinetics, coumarins were detected in the tissue (4.93 µg/g) without detecting them in the receptor compartment. A significant increase of coumarins in the mucosa layers (8.18 µg/g) and receptor compartment (0.26 µg/g) was detected when a T. vaginalis suspension (2 × 105 trophozoites/mL) was previously added onto the mucosa. No alterations were visualized in the stratified squamous non-keratinized epithelium of the porcine vaginal mucosa after contact with the extract. Overall, these results suggest that the P. balansae coumarin-rich extract may have potential as a treatment for trichomoniasis.