bluuebunny/crossref_metadata_2025 huggingface dataset:
Deriving Tidal Structure From Satellite Image Time Series
Authors: Geyman Emily C. , Maloof Adam C.
Published: January 2020

In shallow coastal regions, tides often control the water flux, which in turn directs sediment transport, nutrient delivery, and geochemical gradients. However, tides in shallow areas are spatially heterogeneous, making it challenging to constrain the geographic structure of tidal phase and amplitude without extensive networks of tide gauges. We present a simple remote sensing method for deriving tidal structure from satellite time series. Our method is based on two observations: (1) Tidally driven variations in water depth can be detected as changes in pixel intensity in optical satellite imagery, and (2) repeating passes by an orbiting satellite capture a region at different phases of the tidal cycle. By stacking multiple satellite acquisitions of a shallow bank, we can compute the relative tidal phase and amplitude for each pixel location, thereby resolving a detailed map of tidal propagation and attenuation. While our method requires a set of local water‐depth measurements to calibrate the color‐to‐depth relationship and compute tidal amplitude (in meters), our method can produce spatial estimates of tidal phase and relative amplitude without any site‐specific calibration data. As an illustration of the method, we use Landsat imagery to derive the spatial structure of tides on the Great Bahama Bank, estimating tidal phase and amplitude with mean absolute errors of 15 min and 0.15 m, respectively.
Energy Flow in the Region 2 Field‐Aligned Current Region Under Quasi‐steady Convection
Authors: Ebihara Yusuke , Lee Lou‐Chuang , Tanaka Takashi
Published: January 2020

We investigated energy flow in the inner magnetosphere on the basis of the results obtained by a global magnetohydrodynamic simulation. When the magnetosphere is exposed to a southward interplanetary magnetic field, the magnetosphere undergoes quasi‐steady convection. Downward (earthward) Poynting flux is found in the polar cap, which is consistent with previous observations. However, Poynting flux appears to be upward (antiearthward) in the equatorward region of the auroral oval. The Region 2 field‐aligned current (FAC) is embedded in the upward Poynting flux region. The upward Poynting flux is closely associated with space charge deposited by the ionospheric Hall current under inhomogeneous ionospheric conductivity. The space charge gives rise to shear flow of plasma, which is transmitted upward to the magnetosphere. The shear flow generates additional Region 2 FAC, at least, in the low‐altitude magnetosphere. Spatial distribution of the Region 2 FAC appears to depend on altitude, suggesting the significant influence of the ionosphere in the Region 2 FAC region. We traced integral curves of Poynting flux (S curves) backward from a magnetic field line in the Region 2 FAC region and found that the S curves originate either in the solar wind and in the earthward‐most boundary of the simulation. These simulation results suggest that the ionosphere participates in the generation of the Region 2 FAC, and the ionosphere is a mediator to feed energy to the inner magnetosphere under the quasi‐steady convection.
Arctic Ocean Surface Energy Flux and the Cold Halocline in Future Climate Projections
Authors: Metzner Enrico P. , Salzmann Marc , Gerdes Rüdiger
Published: January 2020

Ocean heat transport is often thought to play a secondary role for Arctic surface warming in part because warm water which flows northward is prevented from reaching the surface by a cold and stable halocline layer. However, recent observations in various regions indicate that occasionally, warm water is found directly below the surface mixed layer. Here we investigate Arctic Ocean surface energy fluxes and the cold halocline layer in climate model simulations from the Coupled Model Intercomparison Project Phase 5. An ensemble of 15 models shows decreased sea ice formation and increased ocean energy release during fall, winter, and spring for a high‐emission future scenario. Along the main pathways for warm water advection, this increased energy release is not locally balanced by increased Arctic Ocean energy uptake in summer. Because during Arctic winter, the ocean mixed layer is mainly heated from below, we analyze changes of the cold halocline layer in the monthly mean Coupled Model Intercomparison Project Phase 5 data. Fresh water acts to stabilize the upper ocean as expected based on previous studies. We find that in spite of this stabilizing effect, periods in which warm water is found directly or almost directly below the mixed layer and which occur mainly in winter and spring become more frequent in high‐emission future scenario simulations, especially along the main pathways for warm water advection. This could reduce sea ice formation and surface albedo.
Extratropical Prediction Skill of the Subseasonal‐to‐Seasonal (S2S) Prediction Models
Authors: Son Seok‐Woo , Kim Hera , Song Kanghyun , Kim Sang‐Wook , Martineau Patrick , Hyun Yu‐Kyung , Kim Yoonjae
Published: January 2020

The deterministic prediction skill of the 10 operational models participating in the subseasonal‐to‐seasonal (S2S) prediction project is assessed for both the extratropical stratosphere and troposphere. Based on the mean squared skill score of 50‐ and 500‐hPa geopotential height forecasts, the overall prediction skill is on average 16 days in the stratosphere and 9 days in the troposphere. The high‐top models with a fully resolved stratosphere typically have a higher prediction skill than the low‐top models. Among them, the European Centre for Medium‐Range Weather Forecasts model shows the best performance in both hemispheres. The decomposition of model errors reveals that eddy errors are more important than zonal‐mean errors in both the stratosphere and troposphere. While the errors in the stratosphere are dominated by planetary‐scale eddies, those in the troposphere are equally influenced by planetary‐ and synoptic‐scale eddies. This result indicates that subseasonal‐to‐seasonal prediction could be improved by better representing planetary‐scale wave activities in the model.
Constraining the Surface Flux of Sea Spray Particles From the Southern Ocean
Authors: Hartery S. , Toohey D. , Revell L. , Sellegri K. , Kuma P. , Harvey M. , McDonald A. J.
Published: January 2020

Modeling the shortwave radiation balance over the Southern Ocean region remains a challenge for Earth system models. To investigate whether this is related to the representation of aerosol‐cloud interactions, we compared measurements of the total number concentration of sea spray‐generated particles within the Southern Ocean region to model predictions thereof. Measurements were conducted from a container laboratory aboard the R/V Tangaroa throughout an austral summer voyage to the Ross Sea. We used source‐receptor modeling to calculate the sensitivity of our measurements to upwind surface fluxes. From this approach, we could constrain empirical parameterizations of sea spray surface flux based on surface wind speed and sea surface temperature. A newly tuned parameterization for the flux of sea spray particles based on the near‐surface wind speed is presented. Comparisons to existing model parameterizations revealed that present model parameterizations led to overestimations of sea spray concentrations. In contrast to previous studies, we found that including sea surface temperature as an explanatory variable did not substantially improve model‐measurement agreement. To test whether or not the parameterization may be applicable globally, we conducted a regression analysis using a database of in situ whitecap measurements. We found that the key fitting parameter within this regression agreed well with the parameterization of sea spray flux. Finally, we compared calculations from the best model of surface flux to boundary layer measurements collected onboard an aircraft throughout the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES), finding good agreement overall.
The Influence of Frost Weathering on Debris Flow Sediment Supply in an Alpine Basin
Authors: Rengers F. K. , Kean Jason W. , Reitman Nadine G. , Smith Joel B. , Coe Jeffrey A. , McGuire Luke A.
Published: January 2020

Rocky, alpine mountains are prone to mass wasting from debris flows. The Chalk Cliffs study area (central Colorado, USA) produces debris flows annually. These debris flows are triggered when overland flow driven by intense summer convective storms mobilizes large volumes of sediment within the channel network. Understanding the debris flow hazard in this, and similar alpine settings, requires determining the magnitude of sediment accumulation between debris flow seasons and identifying the control on sediment production. To address these knowledge gaps, we measured changes in sediment production using a sediment retention fence to quantify how sedimentation was influenced by temperature at the plot scale. These measurements were extrapolated to a larger area, where we extended the sediment fence results to explore how rockfall sedimentation contributed to channel refilling between active debris flow periods. This work shows that debris flow channel refilling is correlated with low temperatures and time in the frost‐cracking window, implicating frost‐weathering mechanisms as a key driver of sedimentation. This sediment production process resulted in a large amount of sediment accumulation during a single winter season in our study reach (up to 0.4 m in some locations). Using these observations, we develop a channel refilling model that generally describes the mass balance of debris flow watersheds in alpine areas.
Fabrication of magnetic trimetallic metal–organic frameworks for the rapid removal of tetracycline from water
Authors: Xiao Rui , Abdu Hassan Idris , Wei Liping , Wang Tieying , Huo Shuhui , Chen Jing , Lu Xiaoquan
Published: January 2020

The metal–organic framework (MOF-74) series has the most open metal sites.
Simple one-pot synthesis of Cu4SnS4 nanoplates and temperature-induced phase transformation mechanism
Authors: Zhang Xiaoyan , Tang Yu , Wang Yifeng , Shen Liming , Gupta Arunava , Bao Ningzhong
Published: January 2020

A simple one-pot heat-up method has been developed to synthesize Cu4SnS4 nanoplates with highly exposed (002) surfaces.
Structure and thermal expansion behavior of Ca4La6−xNdx(SiO4)4(PO4)2O2 apatite for nuclear waste immobilization
Authors: Yan Shan , Yang Dongyan , Chen Shuangqiang , Wen Juan , He Wenhao , Ji Shiyin , Xia Yue , Wang Yinlong , Zhou Liangfu , Li Yuhong
Published: January 2020

In this study, Ca4La6−xNdx(SiO4)4(PO4)2O2 (x = 0, 1, 2, 3, 4, 5, and 6) apatites were explored for nuclear waste immobilization, and Nd3+ ions were used as the surrogate of radionuclides (such as Am3+, Cm3+, and Pu3+).
Significant enhancement in the electrochemical determination of 4-aminophenol from nanoporous gold by decorating with a Pd@CeO2 composite film
Authors: Li Gang , Sun Peng , Wu Fanggen , Zhao Jie , Han Dongxue , Cui Guofeng
Published: January 2020

An electrode based on Pd@CeO2 nanocomposite-decorated nanoporous gold on a carbon fiber paper was achieved, which demonstrated excellent performance in 4-aminophenol determination.
Synthesis and characterization of biodegradable linear shape memory polyurethanes with high mechanical performance by incorporating novel long chain diisocyanates
Authors: Yang Wei , Guan Di , Liu Juan , Luo Yanfeng , Wang Yuanliang
Published: January 2020

Novel long chain diisocyanates were developed for synthesis of biodegradable linear shape memory polyurethanes demonstrating high mechanical performance.
Melamine foam and cellulose nanofiber co-mediated assembly of graphene nanoplatelets to construct three-dimensional networks towards advanced phase change materials
Authors: Xue Fei , Jin Xin-zheng , Wang Wen-yan , Qi Xiao-dong , Yang Jing-hui , Wang Yong
Published: January 2020

A new kind of PCMs have been fabricated through the MF and CNF co-mediated assembly of GNPs, and the PCMs exhibit excellent performances, with great potential applications in many fields relating to energy conversion, storage, release and utilization.
Thermally healable and reprocessable polymethacrylate networks based on diol-mediated metathesis of 6-membered boronic esters
Authors: Yang Yue , Du Fu-Sheng , Li Zi-Chen
Published: January 2020

We demonstrate the thermally repairable and reprocessable poly(methacrylate) networks crosslinked by boronic ester linkage, the dynamic behaviors and mechanical properties of which could be finely tuned by the pendent diols.
Efficient CsSnI3-based inorganic perovskite solar cells based on a mesoscopic metal oxide framework via incorporating a donor element
Authors: Zhang Tao , Li Hao , Ban Huaxia , Sun Qiang , Shen Yan , Wang Mingkui
Published: January 2020

A significantly improved oxidation stability of CsSnI3 perovskites was achieved by introducing cobaltocene as an electron donor additive.
Investigating two-step MAPbI3thin film formation during spin coating by simultaneousin situabsorption and photoluminescence spectroscopy
Authors: Chauhan Mihirsinh , Zhong Yu , Schötz Konstantin , Tripathi Brijesh , Köhler Anna , Huettner Sven , Panzer Fabian
Published: January 2020

Here we investigate the two-step MAPbI3thin film formation during spin coating by simultaneousin situabsorption and photoluminescence spectroscopy.
Carbazole-perylenebisimide electron donor/acceptor dyads showing efficient spin orbit charge transfer intersystem crossing (SOCT-ISC) and photo-driven intermolecular electron transfer
Authors: Rehmat Noreen , Toffoletti Antonio , Mahmood Zafar , Zhang Xue , Zhao Jianzhang , Barbon Antonio
Published: January 2020

An efficient spin orbit charge transfer intersystem crossing (SOCT-ISC) was demonstrated in non-orthogonal compact carbazole-perylenebisimide electron donor/acceptor dyads.
Attenuation‐factor error shaping technique for split CDAC in SAR ADCs
Authors: Sun Jie , Li Xin , Yan Chenggang , Liu Weiqiang
Published: January 2020

A shaping technique is proposed to remedy the attenuation‐factor error in the split capacitor‐digital‐to‐analogue converter (CDAC) of a successive‐approximation‐register (SAR) ADC. By feeding back the previous quantised value of the least significant bit part to the most significant bit part, the inaccurate attenuation‐factor error caused by mismatches and parasitic components is shaped to high frequency. The in‐band dynamic performance is significantly improved without any calibration. Simulation results show that the proposed attenuation‐factor shaping technique improves the spurious‐free‐dynamic‐range by 10 dB, whereas the number of capacitors increases only 1.2%.
Review on development of carbon nanotube field emission cathode for space propulsion systems
Authors: Huo Chao , Liang Feng , Sun An‐bang
Published: January 2020

In recent years, small‐size, low‐weight aerospace propulsion systems have developed rapidly for space exploration, on‐orbit scientific instruments and extra space missions, while additional electron emission devices are commonly required in those propulsion systems. Carbon nanotube (CNT) based field emission cathodes exhibit extraordinary field emission properties and are regarded to be an ideal alternative of conventional thermionic or hollow cathodes. In this study, the authors give an overview of present status of researches on CNT‐based electron emission cathodes for utilising as neutralisers or electron sources particularly in space electric propulsion systems, the theory and characteristics of CNT are also illustrated. Furthermore, challenges, problems and possible solutions before actual applications of CNT in a space mission are discussed accordingly.
Comparative analysis of two different interphase reactors applied in 36‐pulse diode rectifier
Authors: Lian Yuxin , Yang Shiyan , Zeng Xiaoshan , Ben Hongqi , Yang Wei
Published: January 2020

This study presents a comparative analysis of two different interphase reactors (IPRs) applied in a 36‐pulse diode rectifier. One is traditional triple‐tapped IPR; the other is unconventional IPR (UIPR) composed of the primary winding and secondary winding. The primary winding is double‐tapped conventionally and the secondary winding is connected with a single‐phase full‐wave rectifier. The operation modes and optimal parameters of both IPRs are analysed. The effect of different operation modes on output currents of the two three‐phase diode‐bridge rectifiers, input currents and load voltages is also analysed. Under the optimal parameters, both rectifiers operate as 36‐pulse diode rectifiers and reduce the total harmonic distortion of input line currents to be 5%. Especially, the proposed rectifier using UIPR is easy and simple to implement. Some experiments are provided to validate the theoretical analysis.
Improved double‐surface sliding mode observer for flux and speed estimation of induction motors
Authors: Mansouri Seyed Amir , Ahmarinejad Amir , Javadi Mohammad Sadegh , Heidari Reza , Catalão João P. S.
Published: January 2020

This study studies a double‐surface sliding‐mode observer (DS‐SMO) for estimating the flux and speed of induction motors (IMs). The SMO equations are based on an IM model in the stationary reference frame. The DS‐SMO is developed based on the equations of a single‐surface SMO (SS‐SMO) of IM. In DS‐SMO method, the observer is designed through combining sliding variables produced by combining estimated fluxes of currents error. The speed is easily determined based on the pass of switching signal through a low‐pass filter. Also, an optimal DS‐SMO (ODS‐SMO) is proposed to improve the transient condition by optimally tuning the observer parameters. To optimise these parameters, the particle swarm optimisation method is adopted. Moreover, an improved DS‐SMO (IDS‐SMO) is proposed to improve both transient and steady‐state conditions, torque ripple and total harmonic distortion. Moreover, the proposed IDS‐SMO has a stable performance under sudden load change and the low‐speed region. Finally, the accuracy of the proposed ODS‐SMO and IDS‐SMO methods is substantiated through simulation and experimental results.
Multi‐objective‐based feature selection for DDoS attack detection in IoT networks
Authors: Roopak Monika , Tian Gui Yun , Chambers Jonathon
Published: January 2020

In this study, the authors propose a multi‐objective optimisation‐based feature selection (FS) method for the detection of distributed denial of service (DDoS) attacks in an internet of things (IoT) network. An intrusion detection system (IDS) is one approach for the detection of cyber‐attacks. FS is required to reduce the dimensionality of data and improve the performance of the IDS. One of the reasons for the failure of an IDS is incorrect selection of features because most of the FS methods are based on a limited number of objectives such as accuracy or relevance of data, but these are not enough as they can be misleading for attack detection the contribution of this work is to develop appropriate FS method. They have implemented the nondominated sorting algorithm with its adapted jumping gene operator to solve the optimisation problem and exploited an extreme learning machine as the classifier for FS based on six important objectives for an IoT network. Experimental results verify that the proposed method performs well for FS and have achieved 99.9% and has reduced the total number of features by nearly 90%. The proposed method outperforms other proposed FS methods for the detection of DDoS attacks by an IDS.
Asymmetric expansion of coronal mass ejections in the low corona
Authors: Cremades H. , Iglesias F. A. , Merenda L. A.
Published: January 2020

Aims. Understanding how magnetic fields are structured within coronal mass ejections (CMEs), and how they evolve from the low corona into the heliosphere, is a major challenge for space weather forecasting and for solar physics. The study of CME morphology is a particularly auspicious approach to this problem, given that it holds a close relationship with the CME magnetic field configuration. Although earlier studies have suggested an asymmetry in the width of CMEs in orthogonal directions, this has not been inspected using multi-viewpoint observations.

Methods. The improved spatial, temporal, and spectral resolution, added to the multiple vantage points offered by missions of the Heliophysics System Observatory, constitute a unique opportunity to gain insight into this regard. We inspect the early evolution (below ten solar radii) of the morphology of a dozen CMEs occurring under specific conditions of observing spacecraft location and CME trajectory, favorable to reduce uncertainties typically involved in the 3D reconstruction used here. These events are carefully reconstructed by means of a forward modeling tool using simultaneous observations of the Solar-Terrestrial Relations Observatory (STEREO) Extreme Ultraviolet Imager and the Solar Dynamics Observatory Atmospheric Imaging Assembly as input when originating low in the corona, and followed up in the outer fields of view of the STEREO and the Solar and Heliospheric Observatory coronagraphs. We then examine the height evolution of the morphological parameters arising from the reconstructions.

Results. The multi-viewpoint analysis of this set of CMEs revealed that their initial expansion – below three solar radii – is considerably asymmetric and non-self-similar. Both angular widths, namely along the main axes of CMEs (AWL) and in the orthogonal direction (AWD, representative of the flux rope diameter), exhibit much steeper change rates below this height, with the growth rate of AWL found to be larger than that of AWD, also below that height. Angular widths along the main axes of CMEs are on average ≈1.8 times larger than widths in the orthogonal direction AWD. The ratios of the two expansion speeds, namely in the directions of CMEs main axes and in their orthogonal, are nearly constant in time after ∼4 solar radii, with an average ratio ≈1.6. Heights at which the width change rate is defined to stabilize are greater for AWL than for AWD.
Close galaxy pairs with accurate photometric redshifts
Authors: Rodriguez Facundo , Gonzalez Elizabeth Johana , O’Mill Ana Laura , Gaztañaga Enrique , Fosalba Pablo , Lambas Diego García , Mezcua Mar , Siudek Małgorzata
Published: January 2020

Context.Studies of galaxy pairs can provide valuable information to jointly understand the formation and evolution of galaxies and galaxy groups. Consequently, taking the new high-precision photo-zsurveys into account, it is important to have reliable and tested methods that allow us to properly identify these systems and estimate their total masses and other properties.

Aims.In view of the forthcoming Physics of the Accelerating Universe Survey (PAUS), we propose and evaluate the performance of an identification algorithm of projected close isolated galaxy pairs. We expect that the photometrically selected systems can adequately reproduce the observational properties and the inferred lensing mass–luminosity relation of a pair of truly bound galaxies that are hosted by the same dark matter halo.

Methods.We developed an identification algorithm that considers the projected distance between the galaxies, the projected velocity difference, and an isolation criterion in order to restrict the sample to isolated systems. We applied our identification algorithm using a mock galaxy catalog that mimics the features of PAUS. To evaluate the feasibility of our pair finder, we compared the identified photometric samples with a test sample that considers that both members are included in the same halo. Taking advantage of the lensing properties provided by the mock catalog, we also applied a weak-lensing analysis to determine the mass of the selected systems.

Results.Photometrically selected samples tend to show high purity values, but tend to misidentify truly bounded pairs as the photometric redshift errors increase. Nevertheless, overall properties such as the luminosity and mass distributions are successfully reproduced. We also accurately reproduce the lensing mass–luminosity relation as expected for galaxy pairs located in the same halo.
Herds on green meadows: the decarbonization of institutional portfolios
Authors: Benz Lukas , Jacob Andrea , Paulus Stefan , Wilkens Marco
Published: January 2020

We analyze an emerging sustainable trend in asset management: the decarbonization of institutional portfolios. By using broad institutional ownership data, we show that investors exhibit herding behavior in the sense of decarbonization. They are inclined to follow their own or other investors’ buys in green stocks and sales in brown stocks over adjacent quarters. Beyond that, we find that Hedge Funds as well as Investment Advisors lead the herd by executing trades in the sense of decarbonization. This is in line with expectations that sophisticated investors, who integrate environmental aspects into their investment decision process, are able to attract imitators. For the aspired achievement of market-wide decarbonization, investors leading the herd should be encouraged to further decarbonize their portfolios in order to trigger follow-up trades.
Rheometric measurements of molten sulfur might lead to safer transport
Authors: Mandel Savannah
Published: January 2020

To optimize the transport of liquid sulfur, scientists gather rheometric properties of the material using a modified Anton-Paar Modular Compact Rheometer.
Uncertainty in learning, choice, and visual fixation
Authors: Stojić Hrvoje , Orquin Jacob L. , Dayan Peter , Dolan Raymond J. , Speekenbrink Maarten
Published: January 2020

Uncertainty plays a critical role in reinforcement learning and decision making. However, exactly how it influences behavior remains unclear. Multiarmed-bandit tasks offer an ideal test bed, since computational tools such as approximate Kalman filters can closely characterize the interplay between trial-by-trial values, uncertainty, learning, and choice. To gain additional insight into learning and choice processes, we obtained data from subjects’ overt allocation of gaze. The estimated value and estimation uncertainty of options influenced what subjects looked at before choosing; these same quantities also influenced choice, as additionally did fixation itself. A momentary measure of uncertainty in the form of absolute prediction errors determined how long participants looked at the obtained outcomes. These findings affirm the importance of uncertainty in multiple facets of behavior and help delineate its effects on decision making.
Dysregulation of TLR9 in neonates leads to fatal inflammatory disease driven by IFN-γ
Authors: Stanbery Alison G. , Newman Zachary R. , Barton Gregory M.
Published: January 2020

Significance

Toll-like receptors (TLRs) sense and respond to foreign nucleic acids, but this specificity raises the risk of inappropriate responses to self-nucleic acids, leading to autoimmune diseases. Limiting TLR9 activation to endosomes is thought to reduce recognition of self-DNA. To test the importance of this compartmentalized activation for immune tolerance, we developed mice with inducible expression of a mutated TLR9 that bypasses the requirement for endosomal activation. While induction of expression in adults resulted in rather mild disease, expression during development resulted in neonatal fatality dependent on type II interferon (IFN) signaling and driven by macrophages and IFN-γ–producing natural killer cells. This study uses a new model to reveal unique aspects of TLR9-driven inflammatory disease, especially early in life.
Fast-freezing kinetics inside a droplet impacting on a cold surface
Authors: Kant Pallav , Koldeweij Robin B. J. , Harth Kirsten , van Limbeek Michiel A. J. , Lohse Detlef
Published: January 2020

Significance

From critically affecting the performance of an aircraft to droplet-based additive manufacturing, the solidification of impacting droplets influences a wide range of industrial applications; thus, a deeper fundamental understanding of the solidification of an impacting droplet is necessary. In this work, we reveal and rationalize a peculiar freezing morphology originating from the complex interplay between the droplet-scale hydrodynamics and phase-transition effects at sufficiently high substrate undercooling. The direct visualization of different freezing morphologies only became possible as we adopt an optical technique (TIR) in the context of freezing. This technique can be employed in more complex situations, such as solidification of an impacting droplet on liquid-infused or patterned surfaces, which potentially can influence many industrial processes.
Combinatorial protein–protein interactions on a polymerizing scaffold
Authors: Ortiz-Muñoz Andrés , Medina-Abarca Héctor F. , Fontana Walter
Published: January 2020

Significance

Scaffold proteins play an important role in the control and evolution of cellular signaling processes by brokering interactions among docking proteins. In recent years it has become apparent that many scaffolds can form oligomers. We explore theoretically the combinatorial impact of scaffold polymerization on promoting interactions. It is well known that increasing scaffold abundance first expands opportunities for ligand interaction but then collapses them as ligands become separated on different scaffold instances. The polymerizing system stands out by significantly heightening interaction possibilities in the promoting phase and considerably mitigating their collapse. While the qualitative behavior of the system is robust, parameter changes—achievable through the very processes the system mediates—can considerably sculpt its quantitative behavior.
ECM1 is an essential factor for the determination of M1 macrophage polarization in IBD in response to LPS stimulation
Authors: Zhang Yaguang , Li Xuezhen , Luo Zhongguang , Ma Liyan , Zhu Songling , Wang Zhishuo , Wen Jing , Cheng Shipeng , Gu Wangpeng , Lian Qiaoshi , Zhao Xinhao , Fan Weiguo , Ling Zhiyang , Ye Jing , Zheng Songguo , Li Dangsheng , Wang Hongyan , Liu Jie , Sun Bing
Published: January 2020

Inflammatory bowel disease (IBD) comprises chronic relapsing disorders of the gastrointestinal tract characterized pathologically by intestinal inflammation and epithelial injury. Here, we uncover a function of extracellular matrix protein 1 (ECM1) in promoting the pathogenesis of human and mouse IBD. ECM1 was highly expressed in macrophages, particularly tissue-infiltrated macrophages under inflammatory conditions, and ECM1 expression was significantly induced during IBD progression. The macrophage-specific knockout of ECM1 resulted in increased arginase 1 (ARG1) expression and impaired polarization into the M1 macrophage phenotype after lipopolysaccharide (LPS) treatment. A mechanistic study showed that ECM1 can regulate M1 macrophage polarization through the granulocyte-macrophage colony-stimulating factor/STAT5 signaling pathway. Pathological changes in mice with dextran sodium sulfate-induced IBD were alleviated by the specific knockout of theECM1gene in macrophages. Taken together, our findings show that ECM1 has an important function in promoting M1 macrophage polarization, which is critical for controlling inflammation and tissue repair in the intestine.
Reciprocity and behavioral heterogeneity govern the stability of social networks
Authors: Dakin Roslyn , Ryder T. Brandt
Published: January 2020

The dynamics of social networks can determine the transmission of information, the spread of diseases, and the evolution of behavior. Despite this broad importance, a general framework for predicting social network stability has not been proposed. Here we present longitudinal data on the social dynamics of a cooperative bird species, the wire-tailed manakin, to evaluate the potential causes of temporal network stability. We find that when partners interact less frequently and when social connectedness increases, the network is subsequently less stable. Social connectivity was also negatively associated with the temporal persistence of coalition partnerships on an annual timescale. This negative association between connectivity and stability was surprising, especially given that individual manakins who were more connected also had more stable partnerships. This apparent paradox arises from a within-individual behavioral trade-off between partnership quantity and quality. Crucially, this trade-off is easily masked by behavioral variation among individuals. Using a simulation, we show that these results are explained by a simple model that combines among-individual behavioral heterogeneity and reciprocity within the network. As social networks become more connected, individuals face a trade-off between partnership quantity and maintenance. This model also demonstrates how among-individual behavioral heterogeneity, a ubiquitous feature of natural societies, can improve social stability. Together, these findings provide unifying principles that are expected to govern diverse social systems.
IL-4 controls activated neutrophil FcγR2b expression and migration into inflamed joints
Authors: Panda Sudeepta Kumar , Wigerblad Gustaf , Jiang Long , Jiménez-Andrade Yanek , Iyer Vaishnavi Srinivasan , Shen Yunbing , Boddul Sanjaykumar V. , Guerreiro-Cacais André Ortlieb , Raposo Bruno , Kasza Zsolt , Wermeling Fredrik
Published: January 2020

Neutrophils are the most abundant immune cells found in actively inflamed joints of patients with rheumatoid arthritis (RA), and most animal models for RA depend on neutrophils for the induction of joint inflammation. Exogenous IL-4 and IL-13 protect mice from antibody-mediated joint inflammation, although the mechanism is not understood. Neutrophils display a very strong basal expression of STAT6, which is responsible for signaling following exposure to IL-4 and IL-13. Still, the role of IL-4 and IL-13 in neutrophil biology has not been well studied. This can be explained by the low neutrophil surface expression of the IL-4 receptor α-chain (IL-4Rα), essential for IL-4– and IL-13–induced STAT6 signaling. Here we identify that colony stimulating factor 3 (CSF3), released during acute inflammation, mediates potent STAT3-dependent neutrophil IL-4Rα up-regulation during sterile inflammatory conditions. We further demonstrate that IL-4 limits neutrophil migration to inflamed joints, and that CSF3 combined with IL-4 or IL-13 results in a prominent neutrophil up-regulation of the inhibitory Fcγ receptor (FcγR2b). Taking these data together, we demonstrate that the IL-4 and CSF3 pathways are linked and play important roles in regulating proinflammatory neutrophil behavior.
Conformational changes upon gating of KirBac1.1 into an open-activated state revealed by solid-state NMR and functional assays
Authors: Amani Reza , Borcik Collin G. , Khan Nazmul H. , Versteeg Derek B. , Yekefallah Maryam , Do Hoa Q. , Coats Heather R. , Wylie Benjamin J.
Published: January 2020

The conformational changes required for activation and K
+
conduction in inward-rectifier K
+
(Kir) channels are still debated. These structural changes are brought about by lipid binding. It is unclear how this process relates to fast gating or if the intracellular and extracellular regions of the protein are coupled. Here, we examine the structural details of KirBac1.1 reconstituted into both POPC and an activating lipid mixture of 3:2 POPC:POPG (wt/wt). KirBac1.1 is a prokaryotic Kir channel that shares homology with human Kir channels. We establish that KirBac1.1 is in a constitutively active state in POPC:POPG bilayers through the use of real-time fluorescence quenching assays and Förster resonance energy transfer (FRET) distance measurements. Multidimensional solid-state NMR (SSNMR) spectroscopy experiments reveal two different conformers within the transmembrane regions of the protein in this activating lipid environment, which are distinct from the conformation of the channel in POPC bilayers. The differences between these three distinct channel states highlight conformational changes associated with an open activation gate and suggest a unique allosteric pathway that ties the selectivity filter to the activation gate through interactions between both transmembrane helices, the turret, selectivity filter loop, and the pore helix. We also identify specific residues involved in this conformational exchange that are highly conserved among human Kir channels.
Theory of the strange metal Sr
3
Ru
2
O
7
Authors: Mousatov Connie H. , Berg Erez , Hartnoll Sean A.
Published: January 2020

Significance

The behavior of “strange metals” has eluded theoretical understanding for some time. It has remained unclear whether strange metals are fundamentally novel forms of matter or whether some unidentified variant of well-understood physics is at work. We show how the behavior of strontium ruthenate, a widely studied strange metal, follows in detail from well-established electronic properties. Specifically, strontium ruthenate contains “hot” electrons that are less quantum mechanical than the other “cold” electrons. A scattering process in which a cold electron becomes hot after colliding with a second cold electron is unusually strong, because the hot electrons are not subject to the Pauli exclusion principle. This fact is seen to underpin the strange metallicity of strontium ruthenate.
Evolutionary dynamics of recent selection on cognitive abilities
Authors: Miller Sara E. , Legan Andrew W. , Henshaw Michael T. , Ostevik Katherine L. , Samuk Kieran , Uy Floria M. K. , Sheehan Michael J.
Published: January 2020

Cognitive abilities can vary dramatically among species. The relative importance of social and ecological challenges in shaping cognitive evolution has been the subject of a long-running and recently renewed debate, but little work has sought to understand the selective dynamics underlying the evolution of cognitive abilities. Here, we investigate recent selection related to cognition in the paper wasp
Polistes fuscatus
—a wasp that has uniquely evolved visual individual recognition abilities. We generate high quality de novo genome assemblies and population genomic resources for multiple species of paper wasps and use a population genomic framework to interrogate the probable mode and tempo of cognitive evolution. Recent, strong, hard selective sweeps in
P. fuscatus
contain loci annotated with functions in long-term memory formation, mushroom body development, and visual processing, traits which have recently evolved in association with individual recognition. The homologous pathways are not under selection in closely related wasps that lack individual recognition. Indeed, the prevalence of candidate cognition loci within the strongest selective sweeps suggests that the evolution of cognitive abilities has been among the strongest selection pressures in
P. fuscatus
’ recent evolutionary history. Detailed analyses of selective sweeps containing candidate cognition loci reveal multiple cases of hard selective sweeps within the last few thousand years on de novo mutations, mainly in noncoding regions. These data provide unprecedented insight into some of the processes by which cognition evolves.
FOXO1 and FOXO3 transcription factors have unique functions in meniscus development and homeostasis during aging and osteoarthritis
Authors: Lee Kwang Il , Choi Sungwook , Matsuzaki Tokio , Alvarez-Garcia Oscar , Olmer Merissa , Grogan Shawn P. , D’Lima Darryl D. , Lotz Martin K.
Published: January 2020

Significance

Meniscus damage is a common musculoskeletal injury and a major risk factor for knee osteoarthritis (OA). An important knowledge gap exists about meniscus cell homeostasis mechanisms and how their impairment contributes to meniscus pathology following trauma and in aging. Forkhead Box O (FoxO) transcription factors are essential regulators of cellular homeostasis. We performed analysis of expression patterns and function of FoxO in human and mouse menisci. Our results show that FoxOs are suppressed in degenerated meniscus and that FoxO1 regulates meniscus growth and maturation, while both FoxO1 and 3 have protective functions in meniscus during aging and OA. These discoveries provide insight into mechanisms of meniscus degeneration and targets for therapeutic intervention.
Regulation of adipose tissue inflammation by interleukin 6
Authors: Han Myoung Sook , White Alexis , Perry Rachel J. , Camporez Joao-Paulo , Hidalgo Juan , Shulman Gerald I. , Davis Roger J.
Published: January 2020

Significance

Chronic low-grade inflammation is a key driver of metabolic syndrome. This inflammatory response is mediated by immune-cell infiltration and the expression of inflammatory cytokines. IL6 is implicated in this response, but the physiological role of IL6 signaling is unclear. Here, we demonstrate that the source of IL6 influences the nature of the inflammatory response. We report that IL6 secreted by myeloid cells inhibits adipose tissue macrophage (ATM) accumulation by a canonical signaling mechanism, but IL6 secreted by adipocytes or muscle promotes ATM accumulation by a noncanonical mechanism. These observations provide physiological insight into the complexity of IL6-mediated regulation of inflammation.
Global smoothness for a 1D supercritical transport model with nonlocal velocity
Authors: Ferreira Lucas , Moitinho Valter
Published: January 2020

We are concerned with a nonlocal transport 1D-model with supercritical dissipation

γ
∈
(
0
,
1
)

\gamma \in (0,1)

in which the velocity is coupled via the Hilbert transform, namely the so-called CCF model. This model arises as a lower dimensional model for the well-known 2D dissipative quasi-geostrophic equation and in connection with vortex-sheet problems. It is known that its solutions can blow up in finite time when

γ
∈
(
0
,
1

/

2
)

\gamma \in (0,1/2)

. On the other hand, as stated by Kiselev (2010), in the supercritical subrange

γ
∈
[
1

/

2
,
1
)

\gamma \in \lbrack 1/2,1)

it is an open problem to know whether its solutions are globally regular. We show global existence of nonnegative

H

3

/

2

H^{3/2}

-strong solutions in a supercritical subrange (close to 1) that depends on the initial data norm. Then, for each arbitrary smooth nonnegative initial data, the model has a unique global smooth solution provided that

γ
∈
[

γ

1

,
1
)

\gamma \in \lbrack \gamma _{1},1)

where

γ

1

\gamma _{1}

depends on the

H

3

/

2

H^{3/2}

-initial data norm. Our approach is inspired by that of Coti Zelati and Vicol (IUMJ, 2016).
Morphisms between two constructions of Witt vectors of non-commutative rings
Authors: Pisolkar Supriya
Published: January 2020

Let

A
A

be any unital associative, possibly non-commutative ring and let

p
p

be a prime number. Let

E
(
A
)

E(A)

be the ring of

p
p

-typical Witt vectors as constructed by Cuntz and Deninger in [J. Algebra 440 (2015), pp. 545–593] and let

W
(
A
)

W(A)

be the abelian group constructed by Hesselholt in [Acta Math. 178 (1997), pp. 109–141] and [Acta Math. 195 (2005), pp. 55–60]. In [J. Algebra 506 (2018), pp. 379–396] it was proved that if

p
=
2

p=2

and

A
A

is a non-commutative unital torsion free ring, then there is no surjective continuous group homomorphism from
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper W left-parenthesis upper A right-parenthesis right-arrow upper H upper H 0 left-parenthesis upper E left-parenthesis upper A right-parenthesis right-parenthesis colon equals upper E left-parenthesis upper A right-parenthesis slash ModifyingAbove left-bracket upper E left-parenthesis upper A right-parenthesis comma upper E left-parenthesis upper A right-parenthesis right-bracket With bar">

W
(
A
)
→
H

H
0

(
E
(
A
)
)
:=
E
(
A
)

/

[
E
(
A
)
,
E
(
A
)
]

¯

W(A) \to HH_0(E(A)): = E(A)/\overline {[E(A),E(A)]}

which commutes with the Verschiebung operator and the Teichmüller map. In this paper we generalise this result to all primes

p
p

and simplify the arguments used for

p
=
2

p=2

. We also prove that if

A
A

a is a non-commutative unital ring, then there is no continuous map of sets

H

H
0

(
E
(
A
)
)
→
W
(
A
)

HH_0(E(A)) \to W(A)

which commutes with the ghost maps.
Coefficient estimates for 𝐻^{𝑝} spaces with 0<𝑝<1
Authors: Brevig Ole Fredrik , Saksman Eero
Published: January 2020

Let

C
(
k
,
p
)

C(k,p)

denote the smallest real number such that the estimate

|

a
k

|

≤
C
(
k
,
p
)
‖
f

‖

H
p

|a_k|\leq C(k,p)\|f\|_{H^p}

holds for every

f
(
z
)
=

∑

n
≥
0

a
n

z
n

f(z)=\sum _{n\geq 0}a_n z^n

in the

H
p

H^p

space of the unit disc. We compute

C
(
2
,
p
)

C(2,p)

for

0
>
p
>
1

0>p>1

and

C
(
3
,
2

/

3
)

C(3,2/3)

, and identify the functions attaining equality in the estimate.
A Variant in the NEDD4L Gene Associates With Hypertension in Chronic Kidney Disease in the Southeastern Han Chinese Population
Authors: Zhang Jun , Gong Wen-yu , Liu Man , Zhou Wenying , Rao Jialing , Li Yuan-qing , Wu Jian-hao , Luo Dan , Wang Cheng , Peng Hui
Published: January 2020

BACKGROUND

“Neuronal precursor cell expressed developmentally down-regulated 4-like” (NEDD4L) is considered a candidate gene for hypertension—both functionally and genetically—through the regulation of the ubiquitination of the epithelial sodium channel (ENaC). This study explores the relationship between genetic variation in NEDD4L and hypertension with chronic kidney disease (CKD) in the southeastern Han Chinese population.

METHODS

We recruited 623 CKD patients and measured ambulatory blood pressure monitoring (ABPM), and the rs4149601 and rs2288774 polymorphisms in NEDD4L were genotyped using quantitative polymerase chain reaction.

RESULTS

For rs4149601, significant differences in genotype frequencies in an additive model (GG vs. GA vs. AA) were observed between normotensive patients and hypertensive patients when hypertension was classified into ambulatory hypertension, clinical hypertension, and ambulatory systolic hypertension (P = 0.038, 0.005, and 0.006, respectively). In a recessive model (GG + GA vs. AA), the frequency of the AA genotype of rs4149601 in the hypertension groups was all higher than that in the normotensive groups. The genotype distribution of rs2288774 did not differ significantly between the normotensive and hypertensive patients. In both the full cohort and the propensity score matching (PSM) cohort, the AA genotype of rs4149601 (compared with the GG + GA genotype group) was independently correlated with ambulatory hypertension, clinical hypertension, and ambulatory systolic hypertension by multivariate logistic regression analysis.

CONCLUSIONS

The present study indicates that the AA genotype of rs4149601 associates with hypertension in CKD. Consequently, the rs4149601 A allele might be a risk factor for hypertension with CKD.