bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of liver receptor homologue-1 by DDB2 E3 ligase activity is critical for hepatic glucose metabolism
Authors: Lai Tsai-Chun , Hu Meng-Chun 
Published: March 2019

AbstractLiver receptor homologue-1 (LRH-1) plays a critical role in hepatic metabolism and disease. Here we show that LRH-1 protein stability is regulated by the cullin 4 (CUL4) E3 ubiquitin ligase complex. We found that DNA damage-binding protein 2 (DDB2) directly interacts with LRH-1 and functions as a substrate recognition component of CUL4-DDB1 to promote LRH-1 ubiquitination and proteasomal degradation. In human hepatoma (HepG2) cells, we observed that protein levels of endogenous LRH-1 are increased by insulin without a change in mRNA levels of LRH-1. However, overexpression of DDB2 impaired the insulin-stimulated increase in LRH-1 levels. In addition, DDB2 overexpression decreased LRH-1 transcriptional activation and expression of target genes, such as glucokinase, whereas knockdown of DDB2 increased the expression of glucokinase. Finally, we demonstrated that DDB2 knockdown increases glucose uptake and intracellular levels of glucose-6-phosphate in HepG2 cells. Our study reveals a novel regulatory mechanism of LRH-1 activity and suggests a role for DDB2 in hepatic glucose metabolism.
RNA interference-mediated knockdown of voltage-gated sodium channel (MpNav) gene causes mortality in peach-potato aphid, Myzus persicae
Authors: Tariq Kaleem , Ali Asad , Davies T. G. Emyr , Naz Erum , Naz Laila , Sohail Summar , Hou Maolin , Ullah Farman 
Published: March 2019

AbstractVoltage-gated sodium channels (VGSC) are transmembrane proteins that generate an action potential in excitable cells and play an essential role in neuronal signaling. Since VGSCs play a crucial role in nerve transmission they have become primary targets for a broad range of commercial insecticides. RNA interference (RNAi) is a valuable reverse genetics tool used in functional genomics, but recently, it has also shown promise as a novel agent that could be used to control agricultural insect pests. In this study, we targeted the VGSC (MpNav) gene in the peach-potato aphid Myzus persicae, by oral feeding of artificial diets mixed with dsRNAs. Knock-down of MpNav gene expression caused up to 65% mortality in 3rd instar nymphs. Moreover, significantly lower fecundity and longevity was observed in adult aphids that had been fed with dsMpNav solution at the nymphal stage. Analysis of gene expression by qRT-PCR indicated that the aphid mortality rates and the lowered fecundity and longevity were attributable to the down-regulation of MpNav by RNAi. Taken together, our results show that MpNav is a viable candidate target gene for the development of an RNAi-based bio-aphicide.
Propagation of Subseasonal Equatorially-Forced Coastal Trapped Waves down to the Benguela Upwelling System
Authors: Illig Serena , Bachèlery Marie-Lou 
Published: March 2019

AbstractThe oceanic connection between the coastal variability along the southwestern African coasts and the linear equatorial dynamics at subseasonal time-scales (<120 days) is examined using a variety of model outputs, ranging from linear to general circulation models. We focus on the equatorially-forced fast and weakly dissipative first-mode coastal trapped waves which are shown to propagate down to the southern tip of Africa. In the eastern equatorial Atlantic, the first-mode equatorial forcing is tangled with the higher-order Kelvin wave modes and is overshadowed by the dominant second baroclinic mode. The latter is slower and peaks 10 days after the concealed first-mode contribution. Within this time frame, the remotely-forced first-mode coastal trapped waves impinge on the variability of the Benguela upwelling ecosystem, almost in phase with the subseasonal sea level fluctuations in the Gulf of Guinea. Over 1993–2008, the equatorial forcing undergoes a substantial interannual modulation. Periods of energetic first-mode equatorial Kelvin waves coincide with a strong subseasonal coastal wind activity that breaks the stronger equatorial connection. This suggests the existence of a large-scale atmospheric connection between the equatorial wave forcing and the along-shore winds in the Benguela, modulating the maximum latitude at which the equatorial dynamics impacts the local marine resources.
Effects of microRNA-208a on inflammation and oxidative stress in ketamine-induced cardiotoxicity through Notch/NF-κB signal pathways by CHD9
Authors: Yuan Hongjie , Du Shibin , Deng Youliang , Xu Xiaoqing , Zhang Qian , Wang Miao , Wang Ping , Su Yi , Liang Xiao , Sun Yanyan , An Zhengzhuang 
Published: March 2019

AbstractBackground: MicroRNA can regulate gene expression, and participate in multiple vital activities, such as inflammation, oxidative stress epigenetic modification, cell proliferation, and apoptosis. It plays an important role in the genesis and development of cardiovascular disease.Objective: To assess the role of microRNA-208a in ketamine-induced cardiotoxicity.Methods: All rats were randomly selected into two groups: sham and model groups. After fixed, all rats in the model group was intraperitoneally (IP) injected with 100 mg/kg of ketamine. Heart samples were stained with HE assay. Total RNAs from serum were used to hybridize with the SurePrint G3 Rat Whole Genome GE 8×60 K Microarray G4858A platform.Results: In the rat model with ketamine-induced cardiotoxicity, microRNA-208a expression was increased. Then, over-expression of microRNA-208a increased inflammation and oxidative stress in vitro model. However, down-regulation of microRNA-208a decreased inflammation and oxidative stress in vitro model. Over-expression of microRNA-208a suppressed CHD9 and Notch1, and induced p65 protein expression in vitro model. Overexpression of CHD9 reduced the effects of microRNA-208a on inflammation and oxidative stress in heart cell through Notch/p65 signal pathways. Notch1 activation reduced the effects of microRNA-208a on inflammation and oxidative stress in heart cell through p65 signal pathways.Conclusion: MicroRNA-208a may be a potential biomarker for ketamine-induced cardiotoxicity through inflammation and oxidative stress by Notch/NF-κB signal pathways by CHD9.
Synthesis of monodisperse ZrO2 microspheres via urea homogeneous precipitation and its effect on the sintering properties
Authors: Tong Fan , Zhao Ye , Wang Mao‐Hua 
Published: March 2019

Monodisperse zirconia microspheres were prepared by homogeneous urea precipitation method. The effect of reaction time, reaction temperature and other synthetic parameters on the dispersion of the product was investigated in this experiment. The as‐prepared zirconium oxide (ZrO2) powders were characterised by X‐ray diffraction, Brunauer–Emmett–Teller analysis, field emission‐scanning electron microscopy and Fourier‐transform infrared spectroscopy. The experimental results show that the size and dispersion of ZrO2 microspheres can be controlled by changing the concentration of polyvinylpyrrolidone (PVP). The size of ZrO2 microspheres is changed from 120 nm to 1 μm with the increase of PVP concentration. When the reaction temperature is raised to 90°C and the reaction time is reached to 2 h, the monodisperse ZrO2 microspheres with a diameter of 120 nm are finally prepared. ZrO2 ceramics possessed an ultrafine, uniform microstructure and a narrow pore size distribution, and the grain size increased from 72 to 190 nm with the increase of sintering temperature. Moreover, when ZrO2 ceramics were sintered at 950°C for 2 h, the theoretical density was up to about 98% (a density of 5.65 g/cm3), which is higher than that of conventional ZrO2 ceramics.
Single-mode interferometric field of view in partial turbulence correction
Authors: Perrin G. , Woillez J. 
Published: March 2019

Context. The GRAVITY instrument on the ESO VLTI is setting a new mark in the landscape of optical interferometers. Long exposures are possible for the first time in this wavelength domain, delivering a dramatic improvement for astrophysics. In particular, faint objects can be observed at the angular resolution of the VLTI, with exposures exceeding by many orders of magnitude the coherence time of atmospheric turbulence.
Aims. Modern interferometers, especially those that combine light collected by large telescopes such as the Unit Telescopes of the VLT, benefit from partial correction of atmospheric turbulence. We investigate in this paper the influence of atmospheric turbulence on the maximum field of view of interferometers such as GRAVITY, where wavefronts are filtered with single-mode fibres. The basic question is whether the maximum field of view is restricted to the diffraction limit of single apertures or if it is wider in practice. We discuss in particular the case of the field around Sgr A* , with an emphasis on the detectability of the massive main-sequence star S2.
Methods. We theoretically investigated the interferometric and photometric lobes of the interferometer and took atmospheric turbulence into account. We computed the lobe functions with and without partial correction for atmospheric turbulence.
Results. The main result of the paper is that the field of view of the interferometer is widened by tip-tilt residues if higher orders of atmospheric turbulence are corrected for. As a particular case, the S2 star can be detected in interferometric frames centred on Sgr A* even when the distance between the two objects is up to about twice the diffraction limit of a single aperture. We also show that the visibilities are not biased in this case if the pointing accuracies of the fibres are of the order of 10 mas.
Two’s a crowd? Characterising the effect of photometric contamination on the extraction of the global asteroseismic parameter νmax in red-giant binaries
Authors: Sekaran S. , Johnston C. , Tkachenko A. , Beck P. G. , Prša A. , Hambleton K. M. 
Published: March 2019

Context. Theoretical scaling relations for solar-like oscillators and red giants are widely used to estimate fundamental stellar parameters. The accuracy and precision of these relations have often been questioned in the literature, with studies often utilising binarity for model-independent validation. However, it has not been tested if the photometric effects of binarity introduce a systematic effect on the extraction of the seismic properties of the pulsating component(s).
Aims. In this paper, we present an estimation of the impact of a contaminating photometric signal with a distinct background profile on the global asteroseismic parameter νmax through the analysis of synthetic red-giant binary light curves.
Methods. We generated the pulsational and granulation parameters for single red giants with different masses, radii and effective temperatures from theoretical scaling relations and use them to simulate single red-giant light curves with the characteristics of Kepler long-cadence photometric data. These are subsequently blended together according to their light ratio to generate binary red-giant light curves of various configurations. We then performed a differential analysis to characterise the systematic effects of binarity on the extraction of νmax.
Results. We quantify our methodological uncertainties through the analysis of single red-giant light curves, both in the presence and absence of granulation. This is used as a reference for our subsequent differential binary analysis, where we find that the νmax extraction for red-giant power spectra featuring overlapping power excesses is unreliable if unconstrained priors are used. Outside of this scenario, we obtain results that are nearly identical to single-star case.
Conclusions. We conclude that (i) the photometric effects of binarity on the extraction of νmax are largely negligible as long as the power excesses of the individual components do not overlap, and that (ii) there is minimal advantage to using more than two super-Lorentzian components to model the granulation signal of a binary red-giant.
High energy spatially radiative properties of Vela X pulsar wind nebula
Authors: Lu Fang-Wu , Gao Quan-Gui , Zhu Bo-Tao , Zhang Li 
Published: March 2019

Context. Vela X is a middle-aged pulsar wind nebula (PWN) that has been detected in radio, X-ray, and γ-ray bands. The observations indicate that that photon index and flux density of the inner regions of the nebula have obvious changes as the radial distance increases in the X-ray band, and the surface brightness has been discovered to decrease with the increase of radial distance in γ-ray band.
Aims. The multi-band photon emission and high energy spatially radiative properties of Vela X are investigated in the framework of a spatially dependent particle transport model.
Methods. Electron distribution inside the PWN was described by a spatially dependent particle transport equation and the evolution of the non-thermal photon was described as a photon conservation equation under the assumption of a spherically symmetric system with dynamical evolution. In this model, the dynamical and particle evolution equations were simultaneously solved, and the γ-ray attenuation by the supernova remnant (SNR) photon fields in the PWN were taken into account.
Results. The observed spectral energy distributions of Vela X, including X-ray spectra of the inner regions and γ-ray spectra observed at GeV and TeV bands, are well reproduced. The radial variations of the photon index in X-ray band and the surface brightness in the TeV energy range as well as the γ-ray spectra of the inner region and ring extension can also be well reproduced in the framework of our model. The spatial variations of photon indices at GeV and TeV bands are predicted and show that the photon index in GeV band increases with the increase of radial distance while there is only a slight change in the TeV band. Moreover, the modelling results reveal that the γ-ray attenuation by the SNR photon fields is important for modifying very high energy γ-ray spectrum of Vela X.
Starspot activity of HD 199178
Authors: Hackman T. , Ilyin I. , Lehtinen J. J. , Kochukhov O. , Käpylä M. J. , Piskunov N. , Willamo T. 
Published: March 2019

Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved.Aims. High-resolution spectral observations during 1994–2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD 199178.Methods. Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines.Results. We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near the visible rotation pole. Some lower latitude cool features are also recovered, although the reliability of these is questionable. There is an expected anti-correlation between the mean surface temperature and the spot coverage. Using the Doppler images, we construct the equivalent of a solar butterfly diagram for HD 199178.Conclusions. HD 199178 clearly has a long-term large and cool spot structure at the rotational pole. This spot structure dominated the spot activity during the years 1994–2017. The size and position of the structure has evolved with time, with a gradual increase during the last years. The lack of lower latitude features prevents the determination of a possible differential rotation.
Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud
Authors: Licandro J. , de la Fuente Marcos C. , de la Fuente Marcos R. , de León J. , Serra-Ricart M. , Cabrera-Lavers A. 
Published: March 2019

Context. The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area have focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual chemical compositions. This may have produced a biased sample of Oort cloud comets in which the most common objects may be rare, particularly those with perihelia well beyond the orbit of the Earth. Within this context, the known Oort cloud comets may not be representative of the full sample meaning that our current knowledge of the appearance of the average Oort cloud comet may not be accurate. Comet C/2018 F4 (PANSTARRS) is an object of interest in this regard.
Aims. Here, we study the spectral properties in the visible region and the cometary activity of C/2018 F4, and we also explore its orbital evolution with the aim of understanding its origin within the context of known minor bodies moving along nearly parabolic or hyperbolic paths.
Methods. We present observations obtained with the 10.4 m Gran Telescopio Canarias (GTC) that we use to derive the spectral class and visible slope of C/2018 F4 as well as to characterise its level of cometary activity. Direct N-body simulations are carried out to explore its orbital evolution.
Results. The absolute magnitude of C/2018 F4 is Hr > 13.62 ± 0.04 which puts a strong limit on its diameter, D < 10.4 km, assuming a pV = 0.04 cometary-like value of the albedo. The object presents a conspicuous coma, with a level of activity comparable to those of other comets observed at similar heliocentric distances. Comet C/2018 F4 has a visible spectrum consistent with that of an X-type asteroid, and has a spectral slope S′ = 4.0 ± 1.0%/1000 Å and no evidence of hydration. The spectrum matches those of well-studied primitive asteroids and comets. The analysis of its dynamical evolution prior to discovery suggests that C/2018 F4 is not of extrasolar origin.
Conclusions. Although the present-day heliocentric orbit of C/2018 F4 is slightly hyperbolic, both its observational properties and past orbital evolution are consistent with those of a typical dynamically old comet with an origin in the Oort cloud.
Varied origins of up-bending breaks in galaxy disks
Authors: Watkins Aaron E. , Laine Jarkko , Comerón Sébastien , Janz Joachim , Salo Heikki 
Published: March 2019

Aims. Using a sample of 175 low-inclination galaxies from the S4G, we investigate the origins of up-bending (Type III) breaks in the 3.6 μm surface brightness profiles of disk galaxies.
Methods. We reanalyzed a sample of previously identified Type III disk break-hosting galaxies using a new, unbiased break-finding algorithm, which uncovered many new, sometimes subtle disk breaks across the whole sample. We classified each break by its likely origin through close examination of the galaxy images across wavelengths, and compare samples of galaxies separated by their outermost identified break types in terms of their stellar populations and local environments.
Results. We find that more than half of the confirmed Type III breaks in our sample can be attributed to morphological asymmetry in the host galaxies. As these breaks are mostly an artifact of the azimuthal averaging process, their status as physical breaks is questionable. Such galaxies occupy some of the highest density environments in our sample, implying that much of this asymmetry is the result of tidal disturbance. We also find that Type III breaks related to extended spiral arms or star formation often host down-bending (Type II) breaks at larger radius which were previously unidentified. Such galaxies reside in the lowest density environments in our sample, in line with previous studies that found a lack of Type II breaks in clusters. Galaxies occupying the highest density environments most often show Type III breaks associated with outer spheroidal components.
Conclusions. We find that Type III breaks in the outer disks of galaxies arise most often through environmental influence: either tidal disturbance (resulting in disk asymmetry) or heating through, for example, galaxy harrassment (leading to spheroidal components). Galaxies hosting the latter break types also show bimodal distributions in central g − r color and morphological type, with more than half of such galaxies classified as Sa or earlier; this suggests these galaxies may be evolving into early-type galaxies. By contrast, we find that Type III breaks related to apparently secular features (e.g., spiral arms) may not truly define their hosts’ outer disks, as often in such galaxies additional significant breaks can be found at larger radius. Given this variety in Type III break origins, we recommend in future break studies making a more detailed distinction between break subtypes when seeking out, for example, correlations between disk breaks and environment, to avoid mixing unlike physical phenomena.
Pulse-beam heating of deep atmospheric layers, their oscillations and shocks modulating the flare reconnection
Authors: Jelínek P. , Karlický M. 
Published: March 2019

Aims.We study the processes occurring after a sudden heating of deep atmospheric layers at the flare arcade footpoints, which is assumed to be caused by particle beams.Methods.For the numerical simulations we adopt a 2D magnetohydrodynamic (MHD) model, in which we solve a full set of the time-dependent MHD equations by means of the FLASH code, using the adaptive mesh refinement (AMR) method.Results.In the initial state we consider a model of the solar atmosphere with densities according to the VAL-C model and the magnetic field arcade having the X-point structure above, where the magnetic reconnection is assumed. We found that the sudden pulse-beam heating of deep atmospheric layers at the flare arcade footpoints generates two magnetohydrodynamic shocks, one propagating upwards and the second propagating downwards in the solar atmosphere. The downward-moving shock is reflected at deep and dense atmospheric layers and triggers oscillations of these layers. The period of these oscillations in our case is about 174 s. These oscillations generate the upward-moving magnetohydrodynamic waves that can influence the flare magnetic reconnection in a quasi-periodic way. These processes require a sudden heating in very localized regions in dense atmospheric layers; therefore, they can be also associated with seismic waves.
Nucleophilic Trifluoromethylation Reactions Involving Copper(I) Species: From Organometallic Insights to Scope
Authors: Mudarra Ángel L. , Martínez de Salinas Sara , Pérez-Temprano Mónica H. 
Published: March 2019

Over the last decades, trifluoromethyl copper(I) complexes have played a key role as reactive species in C–CF3 bond-forming reactions. This Short Review not only covers selected examples of relevant copper-mediated or catalyzed nucleophilic trifluoromethylation reactions, which is one of the most active fields in organic synthesis, but also provides a comprehensive picture of the real behavior of these copper species, including ubiquitous cuprates, in the reaction media.1	Introduction2	Historical Perspective of the Identification of Relevant Trifluoro-	methyl Copper(I) Species3	In Situ Generation of Active Trifluoromethyl Copper(I) Species 4	Well-Defined Active Trifluoromethyl Copper(I) Complexes5	Recent Advances on the Performance of Trifluoromethylation	Protocols6	Conclusions