bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Turbulence Reveals Riverbed Drag Coefficient
Authors: Branch R. A. , Horner‐Devine A. R. , Chickadel C. C. , Talke S. A. , Clark D. , Jessup A. T. 
Published: April 2021

AbstractFlow in rivers and the coastal ocean is controlled by the frictional force exerted on the water by riverbed or seabed roughness. The frictional force is typically characterized by a drag coefficient Cd, which is estimated from bulk measurements and often assumed constant. Here, we demonstrate a relationship between bed roughness and water surface turbulence that can be used to make remote estimates of Cd. We observe that regions with larger bed roughness result in greater turbulent kinetic energy (TKE), which is transported upward by river boils to the water surface. We present a relationship between surface TKE and Cd, and validate this relationship by comparing remotely sensed estimates of Cd to those from in situ measurements. Thus, our results provide an approach for estimating bottom roughness and Cd based entirely on remotely sensed data, including their spatial variability, which can improve modeling of river discharge and morphodynamics in data‐poor regions.
Simultaneous Observation of Two Isolated Proton Auroras at Subauroral Latitudes by a Highly Sensitive All‐Sky Camera and Van Allen Probes
Authors: Nakamura Kohki , Shiokawa Kazuo , Otsuka Yuichi , Shinbori Atsuki , Miyoshi Yoshizumi , Connors Martin , Spence Harlan , Reeves Geoff , Funsten Herbert O. , MacDowall Robert , Smith Charles , Wygant John , Bonnell John 
Published: April 2021

AbstractIsolated proton auroras (IPAs) appearing at subauroral latitudes are generated by energetic protons precipitating from the magnetosphere through interaction with electromagnetic ion cyclotron (EMIC) waves. An IPA thus indicates the spatial scale and temporal variation of wave‐particle interactions in the magnetosphere. In this study, a unique event of simultaneous ground and magnetospheric satellite observations of two IPAs were conducted on March 16, 2015, using an all‐sky imager at Athabasca, Canada and Van Allen Probes. The Van Allen Probes observed two isolated EMIC waves with frequencies of ∼1 and 0.4 Hz at L ≈ 5.0 when the satellite footprint crossed over the two IPAs. This suggests that the IPAs were caused by localized EMIC waves. Proton flux at 5–20 keV increased locally when the EMIC waves appeared. Electron flux at energies below ∼500 eV also increased. Temperature anisotropy of the energetic protons was estimated at 1.5–2.5 over a wide L‐value range of 3.0–5.2. Electron density gradually decreased from L = 3.5 to 5.4, suggesting that the EMIC wave at L ≈ 5.0 was located in the gradual plasmapause. From these observations, we conclude that the localized IPAs and associated EMIC waves took place because of localized enhancement of energetic proton flux and plasma density structure near the plasmapause. The magnetic field observed by the satellite showed small variation during the wave observation, indicating that the IPAs were accompanied by the weak field‐aligned current.
Impacts of Horizontal Resolution on Global Data Assimilation of Satellite Measurements for Tropospheric Chemistry Analysis
Authors: Sekiya Takashi , Miyazaki Kazuyuki , Ogochi Koji , Sudo Kengo , Takigawa Masayuki , Eskes Henk , Boersma K. Folkert 
Published: April 2021

AbstractWe present the results from a global 0.56°‐resolution chemical data assimilation that integrates satellite observations of ozone, NO2, CO, HNO3, and SO2 from OMI, GOME‐2, SCIAMACHY, TES, MOPITT, and MLS. The assimilation is based on an ensemble Kalman filter technique and simultaneously optimizes ozone precursor emissions and concentrations of various species. The data assimilation at 0.56° resolution reduced model errors against independent surface, aircraft, and ozonesonde observations, which was larger than at coarser resolutions for many cases. By the data assimilation, surface model errors over major polluted regions were reduced by 33%–75% for NO2 and by 15%–18% for ozone. Agreements against assimilated observations for NO2 were improved using the data assimilation at 0.56° resolution by a factor of 1.5–3 compared to 2.8° resolution over major polluted regions. The estimated global total NOx emission over medium and strong source areas were smaller by 15% at 0.56° resolution than at 2.8° resolution associated with resolving small‐scale transport and chemistry processes, while 2%–26% smaller emissions were found for regional total emissions over Europe, the United States, China, India, and South Africa, with larger differences over megacities such as Los Angeles (−41%). The estimated ship emissions were 5%–7% smaller at 0.56° resolution over the Pacific and Atlantic. The 0.56°‐resolution data assimilation provides globally consistent analyses of the emissions and concentrations on a megacity scale, which benefit studies on air quality and its impact on human health at various spatial scales over different regions of the world.
Modeling the Geomagnetic Response to the September 2017 Space Weather Event Over Fennoscandia Using the Space Weather Modeling Framework: Studying the Impacts of Spatial Resolution
Authors: Dimmock A. P. , Welling D. T. , Rosenqvist L. , Forsyth C. , Freeman M. P. , Rae I. J. , Viljanen A. , Vandegriff E. , Boynton R. J. , Balikhin M. A. , Yordanova E. 
Published: April 2021

AbstractWe must be able to predict and mitigate against geomagnetically induced current (GIC) effects to minimize socio‐economic impacts. This study employs the space weather modeling framework (SWMF) to model the geomagnetic response over Fennoscandia to the September 7–8, 2017 event. Of key importance to this study is the effects of spatial resolution in terms of regional forecasts and improved GIC modeling results. Therefore, we ran the model at comparatively low, medium, and high spatial resolutions. The virtual magnetometers from each model run are compared with observations from the IMAGE magnetometer network across various latitudes and over regional‐scales. The virtual magnetometer data from the SWMF are coupled with a local ground conductivity model which is used to calculate the geoelectric field and estimate GICs in a Finnish natural gas pipeline. This investigation has lead to several important results in which higher resolution yielded: (1) more realistic amplitudes and timings of GICs, (2) higher amplitude geomagnetic disturbances across latitudes, and (3) increased regional variations in terms of differences between stations. Despite this, substorms remain a significant challenge to surface magnetic field prediction from global magnetohydrodynamic modeling. For example, in the presence of multiple large substorms, the associated large‐amplitude depressions were not captured, which caused the largest model‐data deviations. The results from this work are of key importance to both modelers and space weather operators. Particularly when the goal is to obtain improved regional forecasts of geomagnetic disturbances and/or more realistic estimates of the geoelectric field.
Linking Flood Frequency With Mesoscale Convective Systems in the US
Authors: Hu Huancui , Feng Zhe , Leung Lai‐Yung Ruby 
Published: April 2021

AbstractMesoscale convective systems (MCSs) with larger rain areas and higher rainfall intensity than non‐MCS events can produce severe flooding. Flooding occurrences associated with MCS and non‐MCS rainfall in the US east of 110°W are examined by linking a high‐resolution MCS data set and reported floods in the warm season (April‐August) between 2007 and 2017. MCSs account for the majority of slow‐rising and hybrid floods, while non‐MCS rainfall explains about half of flash floods in July and August as individual thunderstorms occur frequently in the Rocky Mountains and Appalachian Mountains. The event‐total rainfall area of MCSs is the dominant factor of flood occurrences: MCSs with greater rainfall areas tend to produce more floods. While not related to flood frequency, propagating MCSs tend to produce flash floods with longer durations. These established links can improve our confidence in interpreting flood risks and their future changes due to changes in MCS characteristics with warming.
Marginal Instability Within Internal Solitary Waves
Authors: Chang Ming‐Huei 
Published: April 2021

AbstractHigh‐resolution observations of the currents, hydrography, and turbulence within internal solitary waves (ISWs) reveal Kelvin‐Helmholtz (KH) billows and breaking waveforms occurring in the lower periphery and in the trailing edges, respectively, of the wave cores. Marginal instability (MI) is evident in wave cores, where the probability distribution of the Richardson number Ri, fluctuates around 0.25. The critical value for the occurrence of KH instability in ISWs is evidently 0.25, the canonical criterion of a parallel stratified shear flow. When Ri > 0.25, the turbulent diffusivity Κρ remains O (10−3) m2 s−1 with a standard deviation of one order. When Ri crosses the critical value, the logarithmic turbulent diffusivity linearly increases with a logarithmic reduction in Ri to smooth the velocity and density differences so that Ri is ultimately restored to >0.25. Therefore, the processes of MI cycling preserve ISWs against breakdowns resulting from the uninterrupted growth of KH instability.
Investigating the Moon's Interaction With the Terrestrial Magnetotail Lobe Plasma
Authors: Liuzzo Lucas , Poppe Andrew R. , Halekas Jasper S. , Simon Sven , Cao Xin 
Published: April 2021

AbstractWe present observations of the Moon's plasma interaction in Earth's magnetotail lobes by the ARTEMIS mission, and compare these to hybrid model results to constrain the global properties of the lunar electromagnetic environment. We identify, for the first time in the magnetotail lobes, a low‐energy wake extending multiple lunar radii downstream of the Moon along the ambient flow direction. This wake is tilted out of the lunar optical shadow, allowing for detection of the otherwise unobservable cold ambient magnetospheric plasma. Similar eclipse encounters may provide additional opportunities to measure this low‐energy plasma potentially originating from the terrestrial ionosphere. We find lunar ionospheric outflow extending multiple Moon radii downstream that generates asymmetries in the Moon's plasma environment and shares characteristics with the plasma interactions of Rhea, Tethys, and Dione. The extensive ARTEMIS data set may therefore provide additional insights into the plasma environments near moons of the outer solar system.
Ionospheric Plasma Fluctuations Induced by the NWC Very Low Frequency Signal Transmitter
Authors: Ivarsen Magnus F. , Park Jaeheung , Jin Yaqi , Clausen Lasse B. N. 
Published: April 2021

AbstractThe Australian NWC (North West Cape) signal transmitter is known to strongly interfere with the topside ionosphere. We analyze 456 conjunctions between Swarm A, B and NWC, in addition to 58 conjunctions between NorSat‐1 and NWC. The in‐situ measurements provided by these satellites include the 16 Hz Swarm Advanced Plasma Density data set, and the novel 1,000 Hz plasma density measurements from the m‐NLP system aboard NorSat‐1. We subject the data to a detailed PSD analysis and subsequent superposed epoch analysis. This allows us to present comprehensive statistics of the NWC‐induced plasma fluctuations, both their scale‐dependency, and their climatology. The result should be seen in the context of VLF signal transmitter‐induced plasma density fluctuations, where we find counter‐evidence for the existence of turbulent structuring induced by the NWC transmitter.
Anti-tumor activity of a novel proteasome inhibitor D395 against multiple myeloma and its lower cardiotoxicity compared with carfilzomib
Authors: Shen Xuxing , Wu Chao , Lei Meng , Yan Qing , Zhang Haoyang , Zhang Lina , Wang Xueyuan , Yang Ye , Li Jianyong , Zhu Yongqiang , Chen Lijuan 
Published: April 2021

AbstractCarfilzomib, a second-generation proteasome inhibitor, has significantly improved the survival rate of multiple myeloma (MM) patients, but its clinical application is still restricted by drug resistance and cardiotoxicity. Here, we identified a novel proteasome inhibitor, D395, and assessed its efficacy in treating MM as well as its cardiotoxicity at the preclinical level. The activities of purified and intracellular proteasomes were measured to determine the effect of D395 on the proteasome. CCK-8 and flow cytometry experiments were designed to evaluate the effects of D395 on cell growth and apoptosis. The effects of D395 and carfilzomib on serum enzyme activity, echocardiography features, cardiomyocyte morphology, and hERG channels were also compared. In our study, D395 was highly cytotoxic to MM cell lines and primary MM cells but not normal cells, and it was well tolerated in vivo. Similar to carfilzomib, D395 inhibited osteoclast differentiation in a dose-dependent manner. In particular, D395 exhibited lower cardiotoxicity than carfilzomib in all experiments. In conclusion, D395 is a novel irreversible proteasome inhibitor that has remarkable anti-MM activity and mild cardiotoxicity in vitro and in vivo.
Bruton’s tyrosine kinase regulates gut immune homeostasis through attenuating Th1 response
Authors: Guan Di , Wang Zixi , Huo Jianxin , Xu Shengli , Lam Kong-Peng 
Published: April 2021

AbstractInflammatory bowel disease (IBD) is driven by multiple genetic and environmental risk factors. Patients with mutations in Bruton’s tyrosine kinase (BTK) is known to manifest high prevalence of intestinal disorders including IBD. Although BTK mediates the signaling of various immune receptors, little is known how BTK maintains the homeostasis of the gut immune system. Here, we show that BTK-deficiency promotes IBD progression in a mouse model of colitis. Interestingly, the increased colitis susceptibility of BTK-deficient mice is not caused by gut microbiota changes but rather arises from enhanced pro-inflammatory Th1 response. More importantly, we find the heightened Th1 response in BTK-deficient mice to result from both T cell-extrinsic and -intrinsic mechanisms. BTK-deficient dendritic cells secret elevated levels of the Th1-polarizing cytokine IL-12 and BTK-deficient T cells are inherently more prone to Th1 differentiation. Thus, BTK plays critical roles in maintaining gut immune homeostasis and preventing inflammation via regulating T-cell polarization.
Permissive effect of GSK3β on profibrogenic plasticity of renal tubular cells in progressive chronic kidney disease
Authors: Chen Bohan , Wang Pei , Liang Xianhui , Jiang Chunming , Ge Yan , Dworkin Lance D. , Gong Rujun 
Published: April 2021

AbstractRenal tubular epithelial cells (TECs) play a key role in renal fibrogenesis. After persistent injuries that are beyond self-healing capacity, TECs will dedifferentiate, undergo growth arrest, convert to profibrogenic phenotypes, and resort to maladaptive plasticity that ultimately results in renal fibrosis. Evidence suggests that glycogen synthase kinase (GSK) 3β is centrally implicated in kidney injury. However, its role in renal fibrogenesis is obscure. Analysis of publicly available kidney transcriptome database demonstrated that patients with progressive chronic kidney disease (CKD) exhibited GSK3β overexpression in renal tubulointerstitium, in which the predefined hallmark gene sets implicated in fibrogenesis were remarkably enriched. In vitro, TGF-β1 treatment augmented GSK3β expression in TECs, concomitant with dedifferentiation, cell cycle arrest at G2/M phase, excessive accumulation of extracellular matrix, and overproduction of profibrotic cytokines like PAI-1 and CTGF. All these profibrogenic phenotypes were largely abrogated by GSK3β inhibitors or by ectopic expression of a dominant-negative mutant of GSK3β but reinforced in cells expressing the constitutively active mutant of GSK3β. Mechanistically, GSK3β suppressed, whereas inhibiting GSK3β facilitated, the activity of cAMP response element-binding protein (CREB), which competes for CREB-binding protein, a transcriptional coactivator essential for TGF-β1/Smad signaling pathway to drive TECs profibrogenic plasticity. In vivo, in mice with folic acid-induced progressive CKD, targeting of GSK3β in renal tubules via genetic ablation or by microdose lithium mitigated the profibrogenic plasticity of TEC, concomitant with attenuated interstitial fibrosis and tubular atrophy. Collectively, GSK3β is likely a pragmatic therapeutic target for averting profibrogenic plasticity of TECs and improving renal fibrosis.
MIR99AHG is a noncoding tumor suppressor gene in lung adenocarcinoma
Authors: Han Chencheng , Li Hong , Ma Zhifei , Dong Guozhang , Wang Qianyun , Wang Siwei , Fang Panqi , Li Xiang , Chen Hao , Liu Tongyan , Xu Lin , Wang Jie , Wang Jun , Yin Rong 
Published: April 2021

AbstractLittle is known about noncoding tumor suppressor genes. An effective way to identify these genes is by analyzing somatic copy number variation (CNV)-related noncoding genes. By integrated bioinformatics analyses of differentially expressed long noncoding RNAs (lncRNAs) and arm-level CNVs in lung adenocarcinoma (LUAD), we identified a potential antitumor gene, MIR99AHG, encoding lncRNA MIR99AHG as well as a miR-99a/let-7c/miR-125b2 cluster on chromosome 21q. All four of these transcripts were downregulated in LUAD tissues partly due to the copy number deletion of the MIR99AHG gene. Both MIR99AHG and miR-99a expression was positively correlated with the survival of LUAD patients. MIR99AHG suppressed proliferation and metastasis and promoted autophagy both in vitro and in vivo. Mechanistically, the interaction between MIR99AHG and ANXA2 could accelerate the ANXA2-induced ATG16L+ vesicle biogenesis, thus promoting phagophore assembly. Additionally, miR-99a targeted a well-known autophagy suppressor, mammalian target of rapamycin (mTOR), thereby synergistically promoting autophagy and postponing LUAD progression with MIR99AHG. In summary, MIR99AHG emerges as a noncoding tumor suppressor gene in LUAD, providing a new strategy for antitumor therapy.
Tumor suppressive role of mitochondrial sirtuin 4 in induction of G2/M cell cycle arrest and apoptosis in hepatitis B virus-related hepatocellular carcinoma
Authors: Huang Fung-Yu , Wong Danny Ka-Ho , Seto Wai-Kay , Mak Lung-Yi , Cheung Tan-To , Yuen Man-Fung 
Published: April 2021

AbstractHepatocellular carcinoma (HCC) is developed from uncontrolled cell growth after the malignant transformation of hepatocytes. The hepatitis B virus (HBV) X protein (HBx) has shown to induce cell cycle progression and hepatocarcinogenesis. A sub-fraction of HBx is localized in the mitochondria. Sirtuin 4 (SIRT4), a mitochondrial protein, has been demonstrated to play a tumor-suppressive role in many cancers, including HCC. However, little is known about the association between mitochondrial HBx and SIRT4 during hepatocarcinogenesis. We aimed to investigate the clinical significance and functional role of SIRT4 in HBV-related HCC. SIRT4 expression was significantly lower in the HCC tissues collected from 30 patients with HBV-related HCC than in normal liver tissues from control patients (p < 0.0001). TCGA data analysis indicated that SIRT4 expression was also lower in patients with HBV infection than in those without, and SIRT4 levels were positively associated with better patient survival. Similarly, HCC cell lines had lower SIRT4 expression than normal liver cell lines (all p < 0.01). Among the HCC cell lines, those harbored HBV had a lower SIRT4 expression than those without HBV (p < 0.0001). In vitro experiments revealed that stable HBx transfection suppressed SIRT4 expression in both HepG2 and Huh7 cells (both p < 0.001). Ectopic SIRT4 overexpression alone could induce cellular senescence through arresting cell-cycle progression at G2/M, and inducing cell apoptosis in HCC cells. Mechanistically, SIRT4 upregulated cell-cycle governing genes p16 and p21 protein expression, suppressed CyclinB1/Cdc2 and Cdc25c which normally induce cell-cycle progression, and suppressed survivin to induce apoptosis. Our findings demonstrate the interaction between HBV and SIRT4 in the context of HCC. SIRT4 involves in G2/M DNA damage checkpoint control and genomic stability in hepatocarcinogenesis, which could be targeted for future anticancer strategies.
Strategies to improve photodynamic therapy efficacy by relieving the tumor hypoxia environment
Authors: Shen Zijun , Ma Qingming , Zhou Xinyu , Zhang Guimin , Hao Guizhou , Sun Yong , Cao Jie 
Published: April 2021

AbstractPhotodynamic therapy (PDT) is an emerging technology for tumor treatment in which photosensitizer (PS)-mediated light irradiation reduces oxygen, producing high levels of reactive oxygen species (ROS) that can cause vascular injury and effectively kill tumor cells. However, the naturally hypoxic tumor microenvironment is the main obstacle that hinders the photodynamic response in vivo and prevents its extensive application to tumor treatment. Moreover, PDT-mediated oxygen consumption further increases tumor hypoxia, potentially causing a variety of adverse consequences, such as angiogenesis, tumor invasion, and metastasis. To overcome these limitations caused by hypoxia, multiple strategies have been investigated, including the use of oxygen carriers and reactive oxygen supply materials, the regulation of tumor microenvironments, and multimodal therapy including PDT. In this review, we summarize the latest progress in the development of strategies to relieve tumor hypoxia for improved PDT efficacy and better therapeutic effects.
Multifunctional molybdenum disulfide flash memory using a PEDOT:PSS floating gate
Authors: Hong Seongin , Park Junwoo , Lee Jung Joon , Lee Sunjong , Yun Kyungho , Yoo Hocheon , Kim Sunkook 
Published: April 2021

AbstractTwo-dimensional transition metal dichalcogenide materials (TMDs), such as molybdenum disulfide (MoS2), have been considered promising candidates for future electronic applications owing to their electrical, mechanical, and optical properties. Here, we present a new concept for multifunctional MoS2 flash memory by combining a MoS2 channel with a PEDOT:PSS floating layer. The proposed MoS2 memory devices exhibit a switching ratio as high as 2.3 × 107, a large memory window (54.6 ± 7.80 V), and high endurance (>1,000 cycles). As the PEDOT:PSS film enables a low-temperature solution-coating process and mechanical flexibility, the proposed P-memory can be embedded on a polyimide substrate over a rigid silicon substrate, offering high mechanical endurance (over 1,000 cycle bending test). Furthermore, both MoS2 and PEDOT:PSS have a bandgap that is desirable in optoelectronic memory operation, where charge carriers are stored differently in the floating gate depending on light illumination. As a new application that combines photodiodes and memory functions, we demonstrate multilevel memory programming based on light intensity and color.
Dynamic regulation of DNA nanostructures by noncanonical nucleic acids
Authors: He Shiliang , Ge Zhilei , Zuo Xiaolei , Fan Chunhai , Mao Xiuhai 
Published: April 2021

AbstractDNA nanostructures are among the most fascinating self-assembled nanostructures in diverse areas of science and technology, because of their nanoscale precision in biomolecule and nanoparticle organization. The implementation of dynamic and spatial regulation in structural morphology and hierarchical assembly upon specific external stimuli will greatly expand their applications in biocomputation, clinical diagnosis, and cancer therapy. Recently, noncanonical nucleic acids, particularly DNA triplexes, i-motifs, and G-quadruplexes, have become powerful tools for biosensing and mechanical switching. Developments in incorporating stimuli-responsive noncanonical nucleic acids into DNA nanostructures provide a promising approach to regulating the spatial organization and hierarchical assembly of DNA nanostructures. In this review, we briefly introduce recent progress in constructing DNA nanostructures with dynamic regulation of the structural transformation and programmable assembly pathways at the nanometer scale by noncanonical nucleic acids and discuss their potential applications and challenges.