bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reverse Fountain and the Nighttime Enhancement in the Ionospheric Electron Density Over the Equatorial Region: A Case Study
Authors: Yadav Sneha , Choudhary R. K. , Kumari Jyoti , Sunda Surendra , Shreedevi P. R. , Pant Tarun. K. 
Published: April 2020

AbstractThis paper focuses on the linkage between reverse fountain effect and anomalous enhancement in the nighttime electron density over the equatorial ionosphere often referred as the ionospheric nighttime enhancement (INE). The Global Positioning System (GPS)‐derived total electron content (TEC) measurements over two Indian equatorial stations and ionosonde measurements are used to investigate the occurrence characteristics and mechanism of the premidnight and postmidnight INE events. The high‐resolution spatiotemporal two‐dimensional (2D) TEC maps generated by using satellite‐based augmentation system are used to visualize the reverse fountain effect. These TEC maps are found to be effective in envisaging the motion of equatorial ionization anomaly (EIA) in nighttime ionosphere and its impact on the distribution of electron density over the equatorial region. Salient features of this case study illustrate that, accompanying enhancements in the nighttime TEC, there exist decrease in the F2 layer height, prevalence of downward vertical plasma drift, and dramatic increase in the F2 region electron density. The 2D‐TEC maps reveal the persistence of well‐developed EIA until late evening hours and its gradual shift toward equator during the events of postmidnight INEs. It is found out that the premidnight INE is not invariably linked to the prereversal enhancement of the zonal electric field and could be associated with the redistribution of electron density caused by the reverse fountain effect. The present observations indicate that although the westward electric field serves as a prime driver, the INEs over the equatorial regions are associated with plasma motions caused by the retreating anomaly.
The Influence of Surface Stress Fluctuation on Saltation Sand Transport Around Threshold
Authors: Zheng Xiaojing , Jin Ting , Wang Ping 
Published: April 2020

AbstractMultiscale wind velocity fluctuation and complex inertial response of sand saltation to wind variations give rise to intermittent and nonuniform sand transport, which greatly challenges the prediction of transport rate under wind conditions around saltation threshold. In this paper, three‐dimensional sand saltation within simulation domain of wind tunnel scale is modeled based on large eddy simulation of turbulent wind. Special attention is paid to the prediction of surface shear stress and consequently aerodynamic entrainment. When the wall stress model considering the influence of large‐scale turbulent structures was employed in case of relatively small resistance level for calculating particle aerodynamic entrainment, the model results predict sand transport below the impact threshold. The sand transport rate in this regime increases exponentially with mean wall stress, in contrast to the standard power law‐like behavior above the impact threshold. Aerodynamic entrainment and strong transport events lag behind high‐speed fluids sweep on a large scale even in wind tunnel, but the spatiotemporal variability of small‐scale sand transport is still unclear and quite complex due to transport inertia.
Laboratory Experiments of Bank Collapse: The Role of Bank Height and Near‐Bank Water Depth
Authors: Zhao Kun , Gong Zheng , Zhang Kaili , Wang Keyu , Jin Chuang , Zhou Zeng , Xu Fan , Coco Giovanni 
Published: April 2020

AbstractWe set up a laboratory experiment to reproduce flow‐induced bank erosion and bank collapse and to study the role of bank height (Hb) and near‐bank water depth (Hw) on bank stability. Five laboratory experiments were conducted in a plexiglass‐walled soil tank, using silt collected from natural tidal channel banks (D50 = 75 μm). During each experiment, the bank was subject to a steady and uniform flow. We measured the variations in total soil stress, pore water pressure (when negative, called matric suction), and water content inside the bank and flow velocity and suspended‐sediment concentration upstream and downstream of the bank. Results show that the experiments can reproduce four failure types commonly observed in nature including toppling, tensile and shear failures, and erosion and failure driven by loss of matric suction. The patterns of bank failure can be related to Hb/Hw. For large Hb/Hw (> = 2), we observe a cantilever‐shape bank profile. For small Hb/Hw (<2), we first observe cracks on the bank top, followed by shear failures along a vertical or inclined surface separating the cantilever block up from the bank top. When accounting for our results in the context of previous experimental studies, we find a transition point characterized by a maximum normalized bank retreat rate. For toppling failures, we also find a positive correlation between the ratio Hb/Hw and the geometrical contribution to bank retreat from bank collapse (Cbc). Our research quantifies the role of Hb/Hw on bank collapse, bank retreat rate, and the overall Cbc.
Enhanced Lateral Exchange of Carbon and Nitrogen in a Coastal Wetland With InvasiveSpartina alterniflora
Authors: Gao Yu , Peng Rong‐Hao , Ouyang Zu‐Tao , Shao Chang‐Liang , Chen Ji‐Quan , Zhang Ting‐Ting , Guo Hai‐Qiang , Tang Jian‐Wu , Zhao Feng , Zhuang Ping , Zhao Bin 
Published: April 2020

AbstractLateral movements of materials and energy in coastal wetlands, due mainly to tidal activities, have been recognized as key processes in understanding the biogeochemical cycles of ecosystems. However, our understanding of the roles of lateral movement in shaping ecosystem functions remains limited. Here we quantified the effects of lateral sediment transport on total carbon (C, inorganic + organic) and nitrogen (N) pools in plants and soils in two dominant wetland types: invasiveSpartina alterniflora(Spartina) marshes and nativePhragmites australis(Phragmites) marshes in coastal Shanghai of the Yangtze Estuary. We found that the accreted sediments across the water‐marsh gradients caused by lateral movement resulted in contrasting C and N contents between the two communities. The sediment load and C and N pools in the plants and soils of theSpartinamarshes were significantly higher than those in the adjacentPhragmitesmarshes. The shifts in species composition and community structure not only altered the C and N balance but also enhanced the ecosystem net primary productivity. Our findings highlight the importance of lateral transport in altering ecosystem structure afterSpartinainvasion. The ecosystem C and N pools were significantly higher in the invaded ecosystems than in the native community. Our study also reveals that the plant density and structures can alter tidal hydrodynamics and the lateral transportations of sediments, which in turn influence ecosystem C and N cycle. The C accumulation processes of the native and invaded marshes were further complicated by the contrasting productivities of the ecosystems.
The Distribution of Aerosols and Their Impacts on Chlorophyll‐a Distribution in the South China Sea
Authors: Shen Chunyan , Zhao Hui , Chen Fajin , Xiao Hongwei 
Published: April 2020

AbstractThe distribution of aerosols and their impacts on chlorophyll‐a (Chl‐a) distribution were studied in the South China Sea (SCS). Seventeen years of aerosol optical depth (AOD) data, Chl‐a concentration data, wind speed (WS), and sea surface temperature (SST) from satellite observations were employed along with 2 years of in situ aerosol total suspended particulates (TSP), total nitrogen, NO3−, and NH4+ data in this study. The results showed that under the influence of the Asian monsoon, the AOD values were higher during the winter (>0.12) and lower during the summer (<0.09). Higher aerosol levels were strongly associated with stronger wind conditions (r = 0.70 [AOD vs. WS]; r = 0.67 [TSP vs. WS]). This study also revealed that Chl‐a concentrations were strongly modulated by aerosol deposition in SCS. Multiple correlation analyses between monthly Chl‐a and environmental conditions (i.e., AOD, SST, and WS) in the SCS showed that the Chl‐a were highly correlated with AOD (r = 0.31) and WS (r = 0.47). The higher partial correlation coefficients of Chl‐a with AOD and WS suggested that WS played the most important role, followed by AOD. Aerosol deposition was therefore a main factor besides wind that determined the availability of nutrients at the surface ocean in the SCS, modulating the distribution of Chl‐a. The contribution of nutrients (i.e., NO3− and NH4+) from aerosol dry and wet deposition to new production in the SCS accounted for approximately 10.32% to 28.87%.
Miocene Evolution of North Atlantic Sea Surface Temperature
Authors: Super James R. , Thomas Ellen , Pagani Mark , Huber Matthew , O'Brien Charlotte L. , Hull Pincelli M. 
Published: April 2020

AbstractWe reconstruct sea surface temperatures (SSTs) at Deep Sea Drilling Project Site 608 (42.836°N, 23.087°), north of the Azores Front, and Ocean Drilling Program Site 982 (57.516°N, 15.866°), under the North Atlantic Current, in order to track Miocene (23.1–5.3 Ma) development of North Atlantic surface waters. Mean annual SSTs from TEX86and UK′37proxy estimates at both sites were 10–15 °C higher than modern through the Miocene Climatic Optimum (17–14.5 Ma). During the global cooling of the Middle Miocene Climate Transition (~14.5–12.5 Ma), SSTs at midlatitude Site 608 cooled by ~6 °C, whereas high‐latitude Site 982 cooled by only ~2 °C, resulting in an ~4 Myr collapse of the SST gradient between the two sites. This regional pattern is inconsistent with an increased latitudinal surface temperature gradient, as generally associated with global cooling episodes linked to decreasingpCO2levels. Instead, the pattern is best explained by enhanced ocean heat transport into the high‐latitude North Atlantic superimposed on the global cooling trend, probably due to enhanced Atlantic meridional overturning circulation and/or a stronger North Atlantic Current. During global late Miocene cooling (~8–7 Ma), surface waters cooled by ~6 °C at Site 982 while minimal change occurred at Site 608, reestablishing the North Atlantic SST gradient. The collapse and reemergence of the SST gradient between the middle‐ and high‐latitude North Atlantic suggests that interaction between changes in regional ocean circulation and the global response to changes in greenhouse gas concentration was important in Miocene climate evolution.
The Impact of Astronomical Forcing on Surface and Thermocline Variability Within the Western Pacific Warm Pool Over the Past 160 kyr
Authors: Hollstein M. , Mohtadi M. , Kienast M. , Rosenthal Y. , Groeneveld J. , Oppo D. W. , Southon J. R. , Lückge A. 
Published: April 2020

AbstractThe Western Pacific Warm Pool (WPWP) constitutes an important component within the global climate system by providing an enormous amount of heat and moisture to the global atmosphere. Nevertheless, past variability of oceanography and climate across the WPWP is still debated. Here, we compile newly generated and published surface and thermocline temperature and seawater stable oxygen isotope (δ18OSW) records from the WPWP north and south of the equator to monitor its variability, particularly in response to astronomical forcing, over the last glacial‐interglacial cycle. We find a coherent first‐order variability in all records from the northern and southern WPWP sites over the past 160 kyr indicating a relatively stable WPWP spatial structure. The second‐order variability is modulated by regionally varying influences. Precipitation varied uniformly across the WPWP marine realm. Thermocline records illustrate the influence of both northern and southern Pacific waters on the WPWP. Differences between the thermocline temperature records are attributed to the differing effect of obliquity on the thermocline water masses influencing the individual sites. Precession exerts an influence on the thermocline at both northern and southern WPWP sites. Variations in thermocline conditions in the precession band are attributed to a combination of modifications in the thermocline source waters, changes in the regional atmospheric circulation and the El Niño‐Southern Oscillation regime.
Improvement of IRI Global TEC Maps by Deep Learning Based on Conditional Generative Adversarial Networks
Authors: Ji Eun‐Young , Moon Yong‐Jae , Park Eunsu 
Published: April 2020

AbstractIn this study, we make a model, which is called DeepIRI, to generate improved International Reference Ionosphere (IRI) total electron content (TEC) maps by deep learning based on conditional Generative Adversarial Networks. For this we consider 48,901 pairs of IRI TEC maps and International Global Navigation Satellite Systems (GNSS) Service (IGS) TEC maps from 2001 to 2011 for training the model. We evaluate the model by comparing IGS TEC maps and DeepIRI TEC ones from 2013 to 2017. The DeepIRI TEC maps that our model generated are much more consistent with the corresponding IGS TEC maps than the IRI TEC ones. Especially, ionospheric peak structures are successfully generated in DeepIRI TEC maps while they are not in IRI‐2016 ones. From the average differences between IRI and IGS TEC maps, our model greatly improved the IRI TEC at low‐latitude region around the equatorial anomaly. These results show that our model can improve the global TEC prediction ability of the IRI‐2016. Our study suggests a sufficient possibility to generate DeepIRI global TEC maps in near real time if IRI is generated in time. Our approach can be applied to make improved versions of empirical models if more realistic observations are available with a time delay.
The Fifth Stage in Water Management: Policy Lessons for Water Governance
Authors: Loch A. , Adamson D. , Dumbrell N. P. 
Published: April 2020

AbstractEffective management of water resources is a critical policy issue globally. Using a framework developed by Turton, and a common set of characteristics describing key stages of water demand, we examine the effectiveness of isolated technical (e.g., irrigation upgrades) and allocative (e.g., buyback) efficiency for reducing water demand to sustainable levels. We base our analysis on Australia's water reform context which offers an advanced example of applying these levers to achieve allocative and technical efficiency. The study is motivated by appreciation of the benefits from increased policy flexibility and adaptability in response to the following: potential transformations toward inflexible production systems; uncertainty associated with impacts of climate change on future water reliability; and the need for increased possible future equity between uses/users (productive/consumptive, environmental, cultural). Our results highlight that a balance between technical and allocative efficiency mechanisms is necessary, as neither is sufficient in isolation, when seeking to reduce total water use. This approach also enables a clearer representation of uncertainty in future policy choices in many global settings with respect to water demand reduction.
Spatiotemporal Variations of Satellite Microwave Emissivity Difference Vegetation Index in China Under Clear and Cloudy Skies
Authors: Li Rui , Wang Yipu , Hu Jiheng , Wang Yu , Min Qilong , Bergeron Yves , Valeria Osvaldo , Gao Zongting , Liu Jinjun , Fu Yuyun 
Published: April 2020

AbstractIn this study, we used data from multiple sensors onboard NASA Aqua satellite to conduct a 10‐year (2002–2011) remote sensing of microwave emissivity difference vegetation index (EDVI) over China. We investigated the spatial and temporal variations of EDVI in tropical and subtropical evergreen forest, deciduous forest, rice and wheat farmlands, grassland, and montane vegetation regions. The average of China's EDVI is positive in dense vegetation regions and negative in sparse vegetation regions, depending on the proportion of bare soil and open water. In all selected studying regions, the seasonal variation of EDVI follows the trend of vegetation phenology, even in regions with large proportion of open water. EDVI is positively correlated to the greenness of vegetation (normalized difference vegetation index [NDVI]) with certain phase difference in their seasonal cycle. In autumn, EDVI begins to decline earlier and faster than NDVI. In tropical rainforest, EDVI also starts to increase earlier than NDVI in spring. The large‐scale spatial distribution of EDVI under clear sky and cloudy sky is similar. In montane vegetation regions, EDVI under heavy clouds (90% fraction) conditions is significantly greater than that under clear sky (10% fraction), indicating a possible cloud induced enhancement of vegetation water content. In forests and croplands in the plains, such effect is not remarkable.
High-temperature infrared camouflage with efficient thermal management
Authors: Zhu Huanzheng , Li Qiang , Zheng Chunqi , Hong Yu , Xu Ziquan , Wang Han , Shen Weidong , Kaur Sandeep , Ghosh Pintu , Qiu Min 
Published: April 2020

AbstractHigh-temperature infrared (IR) camouflage is crucial to the effective concealment of high-temperature objects but remains a challenging issue, as the thermal radiation of an object is proportional to the fourth power of temperature (T4). Here, we experimentally demonstrate high-temperature IR camouflage with efficient thermal management. By combining a silica aerogel for thermal insulation and a Ge/ZnS multilayer wavelength-selective emitter for simultaneous radiative cooling (high emittance in the 5–8 μm non-atmospheric window) and IR camouflage (low emittance in the 8–14 μm atmospheric window), the surface temperature of an object is reduced from 873 to 410 K. The IR camouflage is demonstrated by indoor/outdoor (with/without earthshine) radiation temperatures of 310/248 K for an object at 873/623 K and a 78% reduction in with-earthshine lock-on range. This scheme may introduce opportunities for high-temperature thermal management and infrared signal processing.
Reducing endogenous insulin is linked with protection against hepatic steatosis in mice
Authors: Akheruzzaman Md , Hegde Vijay , Shin Andrew C. , Dhurandhar Nikhil V. 
Published: April 2020

AbstractBackgroundObesity and type 2 diabetes (T2D) are closely associated with hepatic steatosis (HS), which if untreated can advance to serious liver conditions. Since insulin promotes hepatic lipogenesis, reducing hyperinsulinemia may help in treating HS. E4orf1 is an adenovirus-derived protein that improves glucose clearance independent of insulin, lowers insulin amount required for glucose disposal, and reduces HS. As a next step, we evaluated the mechanism for E4orf1-induced reduction in HS and tested that E4orf1 does not induce hypoglycemia, an important attribute for its application as a potential anti-diabetic agent.MethodsC57Bl/6J mice that transgenically express E4orf1 in adipose tissue (E4orf-Tg) and wild-type (WT) mice received a chow diet for 6 weeks, followed by a high-fat (HF) diet for additional 10 weeks. Body composition, blood glucose, and serum insulin levels upon glucose load were measured at 0, 6, 7, and 16 weeks. Serum free fatty acid (FFA), triglyceride (TG), and hepatic TG were measured at study termination. We compared histology and the mRNA/protein markers of hepatic and adipose tissue lipid metabolism between the two groups of mice.ResultsOn chow diet, both groups remained normoglycemic, but E4orf1 expression reduced insulin response. On HF diet, glycemic control in WT deteriorated, whereas E4orf1 significantly enhanced glycemic control, lowered insulin response, reduced hepatic triglycerides, and serum FFA. Overall, a comparison of hepatic mRNA and/or protein expression suggested that E4orf1 expression significantly decreased de novo lipogenesis (DNL) and intracellular lipid transport and increased fat oxidation and TG export. Adipose tissue mRNA and protein markers suggested that E4orf1 expression lowered DNL and increased lipolysis.ConclusionConsidering that E4orf1 is not secreted in circulation, we postulate that reduced endogenous insulin in E4orf1 mice indirectly contributes to reduce HS by altering hepatic lipid metabolism, including lipogenesis. This study underscores the possibility of indirectly impacting HS by manipulating adipose tissue metabolism.
Nuclear factor IX promotes glioblastoma development through transcriptional activation of Ezrin
Authors: Liu Zhuohao , Ge Ruixiang , Zhou Jiayi , Yang Xinzhi , Cheng Kenneth King-yip , Tao Jingli , Wu Dinglan , Mao Jie 
Published: April 2020

AbstractEnhanced migration is pivotal for the malignant development of glioblastoma (GBM), but the underlying molecular mechanism that modulates the migration of the GBM cells remains obscure. Here we show that nuclear factor IX (NFIX) is significantly upregulated in human GBM lesions compared with normal or low-grade gliomas. NFIX deficiency impairs the migration of GBM cells and inhibits the tumor growth in the hippocampus of immunodeficient nude mice. Mechanistically, NFIX silencing suppresses the expression of Ezrin, a protein that crosslinks actin cytoskeleton and plasma membrane, which is also positively correlated with GBM malignancy. NFIX depletion induced migration inhibition of GBM cells can be rescued by the replenishment of Ezrin. Furthermore, we identify a NFIX response element (RE) between −840 and −825 bp in the promoter region of the Ezrin gene. Altogether, our findings show, for the first time that NFIX can transcriptionally upregulate the expression of Ezrin and contribute to the enhanced migration of GBM cells, suggesting that NFIX is a potential target for GBM therapy.
WIP1 promotes cancer stem cell properties by inhibiting p38 MAPK in NSCLC
Authors: Deng Kaiyuan , Liu Liang , Tan Xiaoming , Zhang Zhen , Li Jianjun , Ou Yang , Wang Xin , Yang Shuang , Xiang Rong , Sun Peiqing 
Published: April 2020

AbstractCancer stem cells (CSCs) are a small population of stem cell-like cancer cells that can initiate tumors in vivo, and are the major source of cancer initiation, relapse, and drug resistance. We previously reported that the p38 MAPK, through its downstream effectors MK2 and HSP27, suppressed CSC properties by downregulating the expression of transcription factors that mediate stemness in non-small-cell lung cancer (NSCLC) cells, and that despite unaltered total expression of total p38 proteins, the levels of activated p38 were reduced in NSCLC tissues. However, the mechanism underlying the reduced levels of activated p38 in NSCLC is unknown. In this study, we identified WIP1, a p38 phosphatase frequently overexpressed in cancer, as a suppressor of p38 in a pathway that regulates CSC properties in NSCLC. Increased WIP1 expression correlated with reduced levels of activated p38, and with increased levels of a CSC marker in NSCLC tissues. Further investigation revealed that WIP1 promoted stemness-related protein expression and CSC properties by inhibiting p38 activity in NSCLC cells. WIP1 inhibitors are currently under development as anticancer drugs based on their ability to reactivate p53. We found that a WIP1 inhibitor suppressed stemness-related protein expression and CSC properties by activating p38 in NSCLC cells in vitro and in vivo. These studies have identified the WIP1–p38–MK2–HSP27 cascade as a novel signaling pathway that, when altered, promotes CSC properties in NSCLC development, and have defined novel mechanisms underlying the oncogenic activity of WIP1 and the anticancer efficacy of WIP1 inhibitors.