bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of the Disturbed Electric Field in the Sporadic E (Es) Layer Development Over Brazilian Region
Authors: Resende L. C. A. , Shi J. , Denardini C. M. , Batista I. S. , Picanço G. A. S. , Moro J. , Chagas R. A. J. , Barros D. , Chen S. S. , Nogueira P. A. B. , Andrioli V. F. , Silva R. P. , Carrasco A. J. , de Araujo R. C. , Wang C. , Liu Z. 
Published: February 2021

AbstractDuring disturbed periods, E region electric fields can cause anomalous Es layer behavior, which is observed in the digital ionosonde data. To investigate the influence of these electric fields in the Es layer development, we analyzed a set of 20 magnetic storms from 2015 to 2018 over Boa Vista (BV, 2.8°N, 60.7°W, dip ∼18°), São Luís (SLZ, 2.3°S, 44.2°W, dip ∼8°), and Cachoeira Paulista (CXP, 22.41°S, 45°W, dip ∼35°). The electric field zonal components during the main and recovery phases of each magnetic storm are computed to study the corresponding characteristics of these Es seen in ionograms. Additionally, a numerical model (MIRE, Portuguese acronym for E Region Ionospheric Model) is used to analyze the Es layer dynamics modification around disturbed times. Using observation data and simulations, we were able to establish a threshold value for the electric field intensity for each region that can affect the Es layer formation. The results sustain that the strong Es layer in BV can be an indicator of the disturbed dynamo event. At SLZ, on the other hand, the Es layers are affected by the competition mechanisms of their formation, as equatorial electrojet irregularities and winds, during the main phase of the magnetic storm. Over CXP, the Es layer dynamics are dominated by the wind shear mechanism. Finally, this study provides new insights into the real impact of the electric field in the Es layer development over the Brazilian sector. Thus, our results lead to a better understanding of the underlying mechanisms related to the Es layer formation and dynamics.
On the Association Between Electron Flux Oscillations and Local Phase Space Density Gradients
Authors: Sarris Theodore E. , Li Xinlin , Zhao Hong , Khoo Leng Ying , Liu Wenlong , Temerin Michael A. 
Published: February 2021

AbstractElectron flux oscillations are often observed in electron energy channels in the range of 10 keV to 100 keV. They are observed in the form of flux fluctuations with periods corresponding to the drift periods of electrons around the Earth and can be produced in the magnetosphere as a result of drift resonant interactions in association with broadband ultra‐low frequency (ULF) waves. They are observed in particular during quiet times and are indicators of ongoing drift‐resonant processes and resulting radial transport caused by ULF waves. In this study we investigate the association of the appearance of such flux oscillations with the local phase space density. In particular, it is shown that flux oscillations appear when nonzero phase space density gradients are present and furthermore that the observed amplitude of flux oscillations is dependent on radial phase space density gradients, with steeper gradients enabling the observation of flux oscillations with higher‐amplitude. Via statistical observations from the Van Allen probes twin‐spacecraft mission while at apogee at L* ∼5 to ∼5.6 it is found that, during quiet times, electron flux oscillations are more likely to diminish for electron energy of ∼400 keV, and associated phase space density is more likely to be zero for the corresponding first adiabatic invariant values of ∼300 MeV/G. It is also concluded that flux oscillations could be used as indicators of phase space density gradients.
Convergence of Daily GRACE Solutions and Models of Submonthly Ocean Bottom Pressure Variability
Authors: Schindelegger Michael , Harker Alexander A. , Ponte Rui M. , Dobslaw Henryk , Salstein David A. 
Published: February 2021

AbstractKnowledge of submonthly variability in ocean bottom pressure (pb) is an essential element in space‐geodetic analyses and global gravity field research. Estimates of these mass changes are typically drawn from numerical ocean models and, more recently, GRACE (Gravity Recovery and Climate Experiment) series at daily sampling. However, the quality of pb fields from either source has been difficult to assess and reservations persist as to the dependence of regularized GRACE solutions on their oceanographic priors. Here, we make headway on the subject by comparing two daily satellite gravimetry products (years 2007–2009) both with each other and with pb output from a diverse mix of ocean models, complemented by insights from bottom pressure gauges. Emphasis is given to large spatial scales and periods <60 days. Satellite‐based mass changes are in good agreement over basin interiors and point to excess pb signals (∼2 cm root‐mean‐square error) over Southern Ocean abyssal plains in the present GRACE de‐aliasing model. These and other imperfections in baroclinic models are especially apparent at periods <10 days, although none of the GRACE series presents a realistic ground truth on time scales of a few days. A barotropic model simulation with parameterized topographic wave drag is most commensurate with the GRACE fields over the entire submonthly band, allowing for first‐order inferences about error and noise in the gravimetric mass changes. Estimated pb errors vary with signal magnitude and location but are generally low enough (0.5–1.5 cm) to judge model skill in dynamically active regions.
Climatology of Interhemispheric Mesopause Temperatures Using the High‐Latitude and Middle‐Latitude Meteor Radars
Authors: Yi Wen , Xue Xianghui , Reid Iain M. , Murphy Damian J. , Hall Chris M. , Tsutsumi Masaki , Ning Baiqi , Li Guozhu , Yang Guotao , Li Na , Chen Tingdi , Dou Xiankang 
Published: February 2021

AbstractWe present the climatology of mesopause temperatures using high‐latitude and middle‐latitude meteor radars. The daily mesopause temperatures are estimated using ambipolar diffusion coefficient data from the meteor radars at Davis Station (68.6°S, 77.9°E), in Antarctica, Svalbard (78.3°N, 16°E), Tromsø (69.6°N, 19.2°E) in the Arctic, and Mohe (53.5°N, 122.3°E) and Beijing (40.3°N, 116.2°E) in the northern middle latitudes. The seasonal variations in the meteor radar‐derived temperatures are in good agreement with the temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the TIMED satellite. Interhemispheric observations indicate that the mesopause temperatures over the southern and northern polar regions show a clear seasonal asymmetry. The seasonal variations in the Davis Station meteor radar temperatures in the southern polar mesopause are dominated by an annual oscillation (AO) with a relatively weak semiannual oscillation (SAO), which show a clear minimum during summer and a maximum during winter. The mesopause temperatures in the northern high and middle latitudes observed by the Svalbard, Tromsø, Mohe, and Beijing meteor radars mainly show an AO, with a maximum during winter and a minimum during summer. The AO in the northern polar regions is stronger than that in the southern polar regions, while the SAO in the southern polar regions is relatively strong compared to that in the northern polar regions.
Winter Oxygen Regimes in Clear and Turbid Shallow Lakes
Authors: Rabaey Joseph S. , Domine Leah M. , Zimmer Kyle D. , Cotner James B. 
Published: February 2021

AbstractDissolved oxygen controls important processes in lakes, from chemical reactions to organism community structure and metabolism. In shallow lakes, small volumes allow for large fluctuations in dissolved oxygen concentrations, and the oxygen regime can greatly affect ecosystem‐scale processes. We used high frequency dissolved oxygen measurements to examine differences in oxygen regimes between two alternative stable states that occur in shallow lakes. We compared annual oxygen regimes in four macrophyte‐dominated, clear state lakes to four phytoplankton‐dominated, turbid state lakes by quantifying oxygen concentrations, anoxia frequency, and measures of whole‐lake metabolism. Oxygen regimes were not significantly different between lake states throughout the year except for during the winter under‐ice period. During winter, clear lakes had less oxygen, higher frequency of anoxic periods, and higher oxygen depletion rates. Winter oxygen depletion rates correlated positively with peak summer macrophyte biomass. Due to lower levels of oxygen, clear shallow lakes may experience anoxia more often and for longer duration during the winter, increasing the likelihood of fish winterkills. These observations have important implications for shallow lake management, which typically focuses efforts on maintaining the clearwater state.
Plio‐Pleistocene Continental Hydroclimate and Indian Ocean Sea Surface Temperatures at the Southeast African Margin
Authors: Taylor Audrey K. , Berke Melissa A. , Castañeda Isla S. , Koutsodendris Andreas , Campos Hernan , Hall Ian R. , Hemming Sidney R. , LeVay Leah J. , Sierra Alejandra Cartagena , O'Connor Keith ,   Expedition 361 Scientists
Published: February 2021

AbstractEfforts to understand long‐term Indian Ocean dynamics and land‐sea linkages in southeast Africa during periods of significant global and regional climate change have been inhibited by a lack of high‐resolution climate records, particularly during the Plio‐Pleistocene. Here we present new biomarker and pollen records from International Ocean Discovery Program (IODP) Site U1478, located at the Upper Agulhas Confluence near the Limpopo River mouth, to establish environmental conditions at the southeast African margin between 4 and 1.8 Ma and address this spatiotemporal gap. Compound‐specific hydrogen isotopes of terrestrial leaf waxes (δDwax) and TEX86, using marine archaeal lipids, document hydroclimate variability and sea surface temperature (SST), respectively, permitting an onshore‐offshore climate comparison. The U1478 records establish the Limpopo catchment response to the switch in Indonesian Throughflow source waters, the mid‐Pliocene Warm Period, and intensification of Northern Hemisphere glaciations at ∼2.7 Ma. Broad coherence between the δDwax and SST records supports a linkage between Indian Ocean temperatures and southeast African hydroclimate. We hypothesize that additional mechanisms including Indian Ocean cross‐basin SST gradients (ΔSST) and high latitude glaciation acted as hydroclimate controls during the Plio‐Pleistocene. We use ΔSST to evaluate ocean‐atmosphere patterns similar to the Indian Ocean Dipole (IOD) and establish generally wetter conditions in the region associated with positive IOD‐like phases. Additionally, an obliquity signal evident in the δDwax record indicates that glacial‐interglacial variability likely influenced the tropical rain belt position and also controlled rainfall. Hydroclimate and environmental conditions across the Plio‐Pleistocene in southeast Africa may have important implications for regional hominin evolution.
Strain and Velocity Across the Great Basin Derived From 15‐ka Fault Slip Rates: Implications for Continuous Deformation and Seismic Hazard in the Walker Lane, California‐Nevada, USA
Authors: Reitman Nadine G. , Molnar Peter 
Published: February 2021

AbstractAverage strain across the Great Basin over the past 15 Kyr derived from slip rates on individual faults shows a concentration of both right‐lateral shear and extension in the western Great Basin (Walker Lane). Straining is modest across the central Great Basin, with a zone of higher strain in the eastern Great Basin including the Wasatch Front. The horizontal velocity field derived from 15‐ka fault slip rates is similar to the pattern of GPS velocities, suggesting that regional strain release patterns have been constant over the past 15 Kyr. The magnitudes of velocities inferred from fault slip rates, relative to North America, are lower than those from GPS in the Walker Lane, suggesting that the geologic record is missing evidence of strike slip on faults, and seismic hazard may be higher than suggested by fault slip rates alone. The observed strain concentration in the western Great Basin is consistent with a Sierra Nevada block that is more rigid than the surrounding lithosphere of nonlinear rheology, which concentrates strain east of and adjacent to the rigid block. Treating the western U.S. as a thin viscous sheet with the Sierra Nevada block as a rigid boundary provides a consistent history of continuous deformation in the Walker Lane over decadal, millennial, and Neogene timescales.
Macronutrient intake during pregnancy in women with a history of obesity or gestational diabetes and offspring adiposity at 5 years of age
Authors: Meinilä Jelena , Klemetti Miira M. , Huvinen Emilia , Engberg Elina , Andersson Sture , Stach-Lempinen Beata , Koivusalo Saila 
Published: February 2021

AbstractBackground/objectivesThe impact of maternal macronutrient intake during pregnancy on offspring childhood adiposity is unclear. We assessed the associations between maternal macronutrient intake during and after pregnancy with offspring adiposity at 5 years of age. Additionally, we investigated whether gestational diabetes (GDM), BMI, or breastfeeding modified these associations.Subjects/methodsAltogether, 301 mother–child dyads with maternal prepregnancy BMI ≥ 30 and/or previous GDM participated in the Finnish Gestational Diabetes Prevention Study (RADIEL) and its 5 years follow-up. Macronutrient intakes (E%) were calculated from 3-day food records collected at 5–18 weeks’ gestation, in the third trimester, and at 12 months and 5 years after pregnancy. Offspring body fat mass (BFM) and fat percentage (BF%) at 5 years were measured by bioimpedance. Statistical analyses were multivariate linear regression.ResultsMean (SD) prepregnancy BMI was 33(4) kg/m2. GDM was diagnosed in 47%. In normoglycemic women, higher first half of pregnancy n-3 PUFA intake was associated with lower offspring BFM (g) (ß−0.90; 95% CI −1.62, −0.18) and BF% (ß−3.45; 95% CI −6.17, −0.72). In women with GDM, higher first half of pregnancy n-3 PUFA intake was associated with higher offspring BFM (ß0.94; 95% CI 0.14, 1.75) and BF% (ß3.21; 95% CI 0.43, 5.99). Higher SFA intake in the third trimester and cumulative intake across pregnancy (mean of the first half and late pregnancy) was associated with higher BFM and BF% (across pregnancy:ß0.12; 95% CI 0.03, 0.20 andß0.44; 95% CI 0.15, 0.73, respectively). Higher carbohydrate intake across pregnancy was associated with lower BFM (ß−0.044; 95% CI −0.086, −0.003), and borderline associated with BF% (ß−0.15; 95% CI −0.31, 0.00).ConclusionsThe macronutrient composition of maternal diet during pregnancy is associated with offspring BFM and BF% at 5 years. GDM modifies the association between prenatal n-3 PUFA intake and offspring anthropometrics.
ECT2 overexpression promotes the polarization of tumor-associated macrophages in hepatocellular carcinoma via the ECT2/PLK1/PTEN pathway
Authors: Xu Dafeng , Wang Yu , Wu Jincai , Zhang Zhensheng , Chen Jiacheng , Xie Mingwei , Tang Rong , Chen Cheng , Chen Liang , Lin Shixun , Luo Xiangxiang , Zheng Jinfang 
Published: February 2021

AbstractHepatocellular carcinoma (HCC) is a common high-mortality cancer, mainly due to diagnostic difficulties during its early clinical stages. In this study, we aimed to identify genes that are important for HCC diagnosis and treatment, and we investigated the underlying mechanism of prognostic differences. Differentially expressed genes (DEGs) were identified by using the limma package, and receiver operating characteristic curve analysis was performed to identify diagnostic markers for HCC. Bioinformatics and clinical specimens were used to assess epithelial cell transforming 2 (ECT2) in terms of expression, prognostic value, pathways, and immune correlations. In vitro experiments were used to investigate the underlying mechanism and function of ECT2, and the results were confirmed through in vivo experiments. The integrated analysis revealed 53 upregulated DEGs, and one candidate biomarker for diagnosis (ECT2) was detected. High expression of ECT2 was found to be an independent prognostic risk factor for HCC. ECT2 expression showed a strong correlation with tumor-associated macrophages. We found that ECT2 overexpression increased the migration and proliferation of HCC cells. It also promoted the expression of PLK1, which subsequently interacted with PTEN and interfered with its nuclear translocation, ultimately enhancing aerobic glycolysis and promoting M2 macrophage polarization. M2 macrophages suppress the functions of NK cells and T cells, and this was confirmed in the in vivo experiments. Overall, ECT2 may promote the polarization of M2 macrophages by enhancing aerobic glycolysis and suppressing the functions of immune cells. ECT2 could serve as a candidate diagnostic and prognostic biomarker for HCC.
Ubiquitous quantum scarring does not prevent ergodicity
Authors: Pilatowsky-Cameo Saúl , Villaseñor David , Bastarrachea-Magnani Miguel A. , Lerma-Hernández Sergio , Santos Lea F. , Hirsch Jorge G. 
Published: February 2021

AbstractIn a classically chaotic system that is ergodic, any trajectory will be arbitrarily close to any point of the available phase space after a long time, filling it uniformly. Using Born’s rules to connect quantum states with probabilities, one might then expect that all quantum states in the chaotic regime should be uniformly distributed in phase space. This simplified picture was shaken by the discovery of quantum scarring, where some eigenstates are concentrated along unstable periodic orbits. Despite that, it is widely accepted that most eigenstates of chaotic models are indeed ergodic. Our results show instead that all eigenstates of the chaotic Dicke model are actually scarred. They also show that even the most random states of this interacting atom-photon system never occupy more than half of the available phase space. Quantum ergodicity is achievable only as an ensemble property, after temporal averages are performed.
Winner-takes-all resource competition redirects cascading cell fate transitions
Authors: Zhang Rong , Goetz Hanah , Melendez-Alvarez Juan , Li Jiao , Ding Tian , Wang Xiao , Tian Xiao-Jun 
Published: February 2021

AbstractFailure of modularity remains a significant challenge for assembling synthetic gene circuits with tested modules as they often do not function as expected. Competition over shared limited gene expression resources is a crucial underlying reason. It was reported that resource competition makes two seemingly separate genes connect in a graded linear manner. Here we unveil nonlinear resource competition within synthetic gene circuits. We first build a synthetic cascading bistable switches (Syn-CBS) circuit in a single strain with two coupled self-activation modules to achieve two successive cell fate transitions. Interestingly, we find that the in vivo transition path was redirected as the activation of one switch always prevails against the other, contrary to the theoretically expected coactivation. This qualitatively different type of resource competition between the two modules follows a ‘winner-takes-all’ rule, where the winner is determined by the relative connection strength between the modules. To decouple the resource competition, we construct a two-strain circuit, which achieves successive activation and stable coactivation of the two switches. These results illustrate that a highly nonlinear hidden interaction between the circuit modules due to resource competition may cause counterintuitive consequences on circuit functions, which can be controlled with a division of labor strategy.
Cryo-EM reveals structural breaks in a patient-derived amyloid fibril from systemic AL amyloidosis
Authors: Radamaker Lynn , Baur Julian , Huhn Stefanie , Haupt Christian , Hegenbart Ute , Schönland Stefan , Bansal Akanksha , Schmidt Matthias , Fändrich Marcus 
Published: February 2021

AbstractSystemic AL amyloidosis is a debilitating and potentially fatal disease that arises from the misfolding and fibrillation of immunoglobulin light chains (LCs). The disease is patient-specific with essentially each patient possessing a unique LC sequence. In this study, we present two ex vivo fibril structures of a λ3 LC. The fibrils were extracted from the explanted heart of a patient (FOR005) and consist of 115-residue fibril proteins, mainly from the LC variable domain. The fibril structures imply that a 180° rotation around the disulfide bond and a major unfolding step are necessary for fibrils to form. The two fibril structures show highly similar fibril protein folds, differing in only a 12-residue segment. Remarkably, the two structures do not represent separate fibril morphologies, as they can co-exist at different z-axial positions within the same fibril. Our data imply the presence of structural breaks at the interface of the two structural forms.
Single-cell profiling identifies pre-existing CD19-negative subclones in a B-ALL patient with CD19-negative relapse after CAR-T therapy
Authors: Rabilloud Tracy , Potier Delphine , Pankaew Saran , Nozais Mathis , Loosveld Marie , Payet-Bornet Dominique 
Published: February 2021

AbstractChimeric antigen receptor T cell (CAR-T) targeting the CD19 antigen represents an innovative therapeutic approach to improve the outcome of relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). Yet, despite a high initial remission rate, CAR-T therapy ultimately fails for some patients. Notably, around half of relapsing patients develop CD19 negative (CD19neg) B-ALL allowing leukemic cells to evade CD19-targeted therapy. Herein, we investigate leukemic cells of a relapsing B-ALL patient, at two-time points: before (T1) and after (T2) anti-CD19 CAR-T treatment. We show that at T2, the B-ALL relapse is CD19 negative due to the expression of a non-functional CD19 transcript retaining intron 2. Then, using single-cell RNA sequencing (scRNAseq) approach, we demonstrate that CD19neg leukemic cells were present before CAR-T cell therapy and thus that the relapse results from the selection of these rare CD19neg B-ALL clones. In conclusion, our study shows that scRNAseq profiling can reveal pre-existing CD19neg subclones, raising the possibility to assess the risk of targeted therapy failure.