@article{LiuLiuXuetal.2013,
  author    = {Liu, Rui and Liu, Chang and Xu, Yan and Liu, Wei and Kliem, Bernhard and Wang, Haimin},
  title     = {Observation of a moretown wave and wave-filament interactions associated with the renowned X9 flare on 1990 May 24},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {773},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/773/2/166},
  pages     = {13},
  year      = {2013},
  abstract  = {Using Big Bear Solar Observatory film data recently digitized at NJIT, we investigate a Moreton wave associated with an X9 flare on 1990 May 24, as well as its interactions with four filaments F1-F4 located close to the flaring region. The interaction yields interesting insight into physical properties of both the wave and the filaments. The first clear Moreton wavefront appears at the flaring-region periphery at approximately the same time as the peak of a microwave burst and the first of two gamma-ray peaks. The wavefront propagates at different speeds ranging from 1500-2600 km s(-1) in different directions, reaching as far as 600 Mm away from the flaring site. Sequential chromospheric brightenings are observed ahead of the Moreton wavefront. A slower diffuse front at 300-600 km s(-1) is observed to trail the fast Moreton wavefront about one minute after the onset. The Moreton wave decelerates to similar to 550 km s(-1) as it sweeps through F1. The wave passage results in F1's oscillation which is featured by similar to 1 mHz signals with coherent Fourier phases over the filament, the activation of F3 and F4 followed by gradual recovery, but no disturbance in F2. Different height and magnetic environment together may account for the distinct responses of the filaments to the wave passage. The wavefront bulges at F4, whose spine is oriented perpendicular to the upcoming wavefront. The deformation of the wavefront is suggested to be due to both the forward inclination of the wavefront and the enhancement of the local Alfven speed within the filament channel.},
  language  = {en}
}
@article{KliemToeroekTitovetal.2014,
  author    = {Kliem, Bernhard and Toeroek, Tibor and Titov, Viacheslav S. and Lionello, Roberto and Linker, Jon A. and Liu, Rui and Liu, Chang and Wang, Haimin},
  title     = {Slow rise and partial eruption of a double-decker filament. II. A double flux rope model},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {792},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/792/2/107},
  pages     = {10},
  year      = {2014},
  abstract  = {Force-free equilibria containing two vertically arranged magnetic flux ropes of like chirality and current direction are considered as a model for split filaments/prominences and filament-sigmoid systems. Such equilibria are constructed analytically through an extension of the methods developed in Titov \& Demoulin and numerically through an evolutionary sequence including shear flows, flux emergence, and flux cancellation in the photospheric boundary. It is demonstrated that the analytical equilibria are stable if an external toroidal (shear) field component exceeding a threshold value is included. If this component decreases sufficiently, then both flux ropes turn unstable for conditions typical of solar active regions, with the lower rope typically becoming unstable first. Either both flux ropes erupt upward, or only the upper rope erupts while the lower rope reconnects with the ambient flux low in the corona and is destroyed. However, for shear field strengths staying somewhat above the threshold value, the configuration also admits evolutions which lead to partial eruptions with only the upper flux rope becoming unstable and the lower one remaining in place. This can be triggered by a transfer of flux and current from the lower to the upper rope, as suggested by the observations of a split filament in Paper I. It can also result from tether-cutting reconnection with the ambient flux at the X-type structure between the flux ropes, which similarly influences their stability properties in opposite ways. This is demonstrated for the numerically constructed equilibrium.},
  language  = {en}
}
@article{LiuKliemToeroeketal.2012,
  author    = {Liu, Rui and Kliem, Bernhard and Toeroek, Tibor and Liu, Chang and Titov, Viacheslav S. and Lionello, Roberto and Linker, Jon A. and Wang, Haimin},
  title     = {Slow rise and partial eruption of a double-decker filament. I. observations and interpretation},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {756},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.1088/0004-637X/756/1/59},
  pages     = {14},
  year      = {2012},
  abstract  = {We study an active-region dextral filament that was composed of two branches separated in height by about 13 Mm, as inferred from three-dimensional reconstruction by combining SDO and STEREO-B observations. This "double-decker" configuration sustained for days before the upper branch erupted with a GOES-class M1.0 flare on 2010 August 7. Analyzing this evolution, we obtain the following main results. (1) During the hours before the eruption, filament threads within the lower branch were observed to intermittently brighten up, lift upward, and then merge with the upper branch. The merging process contributed magnetic flux and current to the upper branch, resulting in its quasi-static ascent. (2) This transfer might serve as the key mechanism for the upper branch to lose equilibrium by reaching the limiting flux that can be stably held down by the overlying field or by reaching the threshold of the torus instability. (3) The erupting branch first straightened from a reverse S shape that followed the polarity inversion line and then writhed into a forward S shape. This shows a transfer of left-handed helicity in a sequence of writhe-twist-writhe. The fact that the initial writhe is converted into the twist of the flux rope excludes the helical kink instability as the trigger process of the eruption, but supports the occurrence of the instability in the main phase, which is indeed indicated by the very strong writhing motion. (4) A hard X-ray sigmoid, likely of coronal origin, formed in the gap between the two original filament branches in the impulsive phase of the associated flare. This supports a model of transient sigmoids forming in the vertical flare current sheet. (5) Left-handed magnetic helicity is inferred for both branches of the dextral filament. (6) Two types of force-free magnetic configurations are compatible with the data, a double flux rope equilibrium and a single flux rope situated above a loop arcade.},
  language  = {en}
}
@article{LiuKliemTitovetal.2016,
  author    = {Liu, Rui and Kliem, Bernhard and Titov, Viacheslav S. and Chen, Jun and Wang, Yuming and Wang, Haimin and Liu, Chang and Xu, Yan and Wiegelmann, Thomas},
  title     = {STRUCTURE, STABILITY, AND EVOLUTION OF MAGNETIC FLUX ROPES FROM THE PERSPECTIVE OF MAGNETIC TWIST},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {818},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/0004-637X/818/2/148},
  pages     = {22},
  year      = {2016},
  abstract  = {We investigate the evolution of NOAA Active Region (AR) 11817 during 2013 August 10-12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated with a magnetic flux rope (MFR) located along the major polarity inversion line, where shearing and converging photospheric flows are present. Aided by the nonlinear force-free field modeling, we identify the MFR through mapping magnetic connectivities and computing the twist number \${{ \mathcal T }}_{w}\$ for each individual field line. The MFR is moderately twisted (\$| {{ \mathcal T }}_{w}| \lt 2\$) and has a well-defined boundary of high squashing factor Q. We found that the field line with the extremum \$| {{ \mathcal T }}_{w}| \$ is a reliable proxy of the rope axis, and that the MFR's peak \$| {{ \mathcal T }}_{w}| \$ temporarily increases within half an hour before each flare while it decreases after the flare peak for both confined and eruptive flares. This pre-flare increase in \$| {{ \mathcal T }}_{w}| \$ has little effect on the AR's free magnetic energy or any other parameters derived for the whole region, due to its moderate amount and the MFR's relatively small volume, while its decrease after flares is clearly associated with the stepwise decrease in the whole region's free magnetic energy due to the flare. We suggest that \${{ \mathcal T }}_{w}\$ may serve as a useful parameter in forewarning the onset of eruption, and therefore, the consequent space weather effects. The helical kink instability is identified as the prime candidate onset mechanism for the considered flares.},
  language  = {en}
}
@article{ChenLiuLiuetal.2019,
  author    = {Chen, Jun and Liu, Rui and Liu, Kai and Awasthi, Arun Kumar and Zhang, Peijin and Wang, Yuming and Kliem, Bernhard},
  title     = {Extreme-ultraviolet late phase of solar flares},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {890},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {Institute of Physics Publ.},
  address   = {London},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/ab6def},
  pages     = {10},
  year      = {2019},
  abstract  = {A second peak in the extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as the EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop system. Here we carry out a survey of 55 M-and-above GOES-class flares with ELP during 2010-2014. Based on the flare-ribbon morphology, these flares are categorized as circular-ribbon (19 events), two-ribbon (23 events), and complex-ribbon (13 events) flares. Among them, 22 events (40\%) are associated with coronal mass ejections, while the rest are confined. An extreme ELP, with the late-phase peak exceeding the main-phase peak, is found in 48\% of two-ribbon flares, 37\% of circular-ribbon flares, and 31\% of complex-ribbon flares, suggesting that additional heating is more likely present during ELP in two-ribbon than in circular-ribbon flares. Overall, cooling may be the dominant factor causing the delay of the ELP peak relative to the main-phase peak, because the loop system responsible for the ELP emission is generally larger than, and well separated from, that responsible for the main-phase emission. All but one of the circular-ribbon flares can be well explained by a composite "dome-plate" quasi-separatrix layer (QSL). Only half of these show a magnetic null point, with its fan and spine embedded in the dome and plate, respectively. The dome-plate QSL, therefore, is a general and robust structure characterizing circular-ribbon flares.},
  language  = {en}
}
@article{WangKoehlerCaoetal.2012,
  author    = {Wang, Wei-Hong and K{\"o}hler, Barbara and Cao, Feng-Qiu and Liu, Guo-Wei and Gong, Yuan-Yong and Sheng, Song and Song, Qi-Chao and Cheng, Xiao-Yuan and Garnett, Trevor and Okamoto, Mamoru and Qin, Rui and M{\"u}ller-R{\"o}ber, Bernd and Tester, Mark and Liu, Lai-Hua},
  title     = {Rice DUR3 mediates high-affinity urea transport and plays an effective role in improvement of urea acquisition and utilization when expressed in Arabidopsis},
  series = {New phytologist : international journal of plant science},
  volume    = {193},
  journal   = {New phytologist : international journal of plant science},
  number    = {2},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {0028-646X},
  doi       = {10.1111/j.1469-8137.2011.03929.x},
  pages     = {432 -- 444},
  year      = {2012},
  abstract  = {Despite the great agricultural and ecological importance of efficient use of urea-containing nitrogen fertilizers by crops, molecular and physiological identities of urea transport in higher plants have been investigated only in Arabidopsis. We performed short-time urea-influx assays which have identified a low-affinity and high-affinity (Km of 7.55 mu M) transport system for urea-uptake by rice roots (Oryza sativa). A high-affinity urea transporter OsDUR3 from rice was functionally characterized here for the first time among crops. OsDUR3 encodes an integral membrane-protein with 721 amino acid residues and 15 predicted transmembrane domains. Heterologous expression demonstrated that OsDUR3 restored yeast dur3-mutant growth on urea and facilitated urea import with a Km of c. 10 mu M in Xenopus oocytes. Quantitative reverse-transcription polymerase chain reaction (qPCR) analysis revealed upregulation of OsDUR3 in rice roots under nitrogen-deficiency and urea-resupply after nitrogen-starvation. Importantly, overexpression of OsDUR3 complemented the Arabidopsis atdur3-1 mutant, improving growth on low urea and increasing root urea-uptake markedly. Together with its plasma membrane localization detected by green fluorescent protein (GFP)-tagging and with findings that disruption of OsDUR3 by T-DNA reduces rice growth on urea and urea uptake, we suggest that OsDUR3 is an active urea transporter that plays a significant role in effective urea acquisition and utilisation in rice.},
  language  = {en}
}
@article{XueLiuWangetal.2019,
  author    = {Xue, Rui and Liu, Ruo-Yu and Wang, Xiang-Yu and Yan, Huirong and B{\"o}ttcher, Markus},
  title     = {On the minimum jet power of TeV BL Lac objects in the p-gamma model},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {871},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {1},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/aaf720},
  pages     = {10},
  year      = {2019},
  abstract  = {We study the requirement of the jet power in the conventional p-gamma models (photopion production and Bethe-Heitler pair production) for TeV BL Lac objects. We select a sample of TeV BL Lac objects whose spectral energy distributions are difficult to explain by the one-zone leptonic model. Based on the relation between the p-gamma interaction efficiency and the opacity of gamma gamma absorption, we find that the detection of TeV emission poses upper limits on the p-gamma interaction efficiencies in these sources and hence minimum jet powers can be derived accordingly. We find that the obtained minimum jet powers exceed the Eddington luminosity of the supermassive black holes (SMBHs). Implications for the accretion mode of the SMBHs in these BL Lac objects and the origin of their TeV emissions are discussed.},
  language  = {en}
}
@book{ChenLiuNiuetal.2003,
  author    = {Chen, Rui and Liu, Jiaqi and Niu, Wenyuan and Deng, Xiangzheng and Mu, Guijin and Wagner, Mayke and Geldmacher, Karl},
  title     = {Critical controlling of PRED system of oasis ecology in the arid region of central Asia : a case study of Keriya River Valley oases, Xinjiang},
  series = {Ecosystems dynamics, ecosystem-society interactions, and remote sensing applications for semi-arid and arid land},
  volume    = {4890},
  journal   = {Ecosystems dynamics, ecosystem-society interactions, and remote sensing applications for semi-arid and arid land},
  publisher = {SPIE},
  address   = {Bellingham, Wash.},
  isbn      = {0-8194-4676-9},
  year      = {2003},
  abstract  = {Oases is a special ecosystem formed in arid climate and hungriness environment, in which resident, water and soil are the principal factor and exchanges of materials, energy and information are the main functional characteristics. The oases regions in central Asia are not only the basilic cradle of civilization of human beings, but also the important strategic places in world growing awareness of the potential benefits. We choose Keriya River Basin oases in south of Xinjiang as a case to study critical controlling of Oases Evolution, Based on the theories and methods used for environmental geology, physical geography, land resource research, and oases ecology. This study try to indicate the essential factors driving the oases ecosystem and the interactional dynamic mechanism in different scales and levels, confirm the optimal equilibrium aggregate of harmonious development between Population, Resources, Environment and Development, and establish the critical controlling pattern of sustainable development. We advance the indicator system to research the evolution of the PRED System of oases in Keriya River valley oases, in basis of the information derived from the field investigation and local materials. According to inquisitional result based on technical support of Geographic Information System (GIS) and Remote Sense (RS), the comparisons and analyses are carried out in land use at the upper reaches, vegetation change in the middle reaches, and desertification at the lower reaches, which narrates the regulations of Keriya River Valley oases land cover dynamic change. The main land cover types represent distinct characteristics of the local place. On the basis of field survey and statistical data, we use ARCINFO software to preprocess these data and the 2 TM satellite images. Through analyzing these images resulting from post- classification compare, we sums up the concrete quantificational dynamic distributed data of 13 land types covering a span of 15 years and regulation of the local ecological environment system. It finally points out that the trend of Keriya River Valley oases desertification expansion is mainly related to two important reasons: impact of natural environment and impact of human activities.},
  language  = {en}
}
@article{GouLiuKliemetal.2019,
  author    = {Gou, Tingyu and Liu, Rui and Kliem, Bernhard and Wang, Yuming and Veronig, Astrid M.},
  title     = {The birth of a coronal mass ejection},
  series = {Science Advances},
  volume    = {5},
  journal   = {Science Advances},
  number    = {3},
  publisher = {American Assoc. for the Advancement of Science},
  address   = {Washington},
  issn      = {2375-2548},
  doi       = {10.1126/sciadv.aau7004},
  pages     = {9},
  year      = {2019},
  abstract  = {The Sun's atmosphere is frequently disrupted by coronal mass ejections (CMEs), coupled with flares and energetic particles. The coupling is usually attributed to magnetic reconnection at a vertical current sheet connecting the flare and CME, with the latter embedding a helical magnetic structure known as flux rope. However, both the origin of flux ropes and their nascent paths toward eruption remain elusive. Here, we present an observation of how a stellar-sized CME bubble evolves continuously from plasmoids, mini flux ropes that are barely resolved, within half an hour. The eruption initiates when plasmoids springing from a vertical current sheet merge into a leading plasmoid, which rises at increasing speeds and expands impulsively into the CME bubble, producing hard x-ray bursts simultaneously. This observation illuminates a complete CME evolutionary path capable of accommodating a wide variety of plasma phenomena by bridging the gap between microscale and macroscale dynamics.},
  language  = {en}
}
@article{LiuWangXueetal.2019,
  author    = {Liu, Ruo-Yu and Wang, Kai and Xue, Rui and Taylor, Andrew M. and Wang, Xiang-Yu and Li, Zhuo and Yan, Huirong},
  title     = {Hadronuclear interpretation of a high-energy neutrino event coincident with a blazar flare},
  series = {Physical review : D, Particles, fields, gravitation, and cosmology},
  volume    = {99},
  journal   = {Physical review : D, Particles, fields, gravitation, and cosmology},
  number    = {6},
  publisher = {American Physical Society},
  address   = {Melville},
  issn      = {2470-0010},
  doi       = {10.1103/PhysRevD.99.063008},
  pages     = {11},
  year      = {2019},
  abstract  = {Although many high-energy neutrinos detected by the IceCube telescope are believed to have an extraterrestrial origin, their astrophysical sources remain a mystery. Recently, an unprecedented discovery of a high-energy muon neutrino event coincident with a multiwavelength flare from a blazar, TXS 0506 + 056, shed some light on the origin of the neutrinos. It is usually believed that a blazar is produced by a relativistic jet launched from an accreting supermassive black hole (SMBH). Here, we show that the high-energy neutrino event can be interpreted by the inelastic hadronuclear interactions between the accelerated cosmic-ray protons in the relativistic jet and the dense gas clouds in the vicinity of the SMBH. Such a scenario only requires a moderate proton power in the jet, which could be much smaller than that required in the conventional hadronic model which instead calls upon the photomeson process. Meanwhile, the flux of the multiwavelength flare from the optical to gamma-ray band can be well explained by invoking a second radiation zone in the jet at a larger distance to the SMBH. In our model, the neutrino emission lasts a shorter time than the multiwavelength flare, so the neutrino event is not necessarily correlated with the flare, but it is probably accompanied by a spectrum hardening above a few giga-electron-volt (GeV).},
  language  = {en}
}