Evidence of a nonlinear transition from mitigation to suppression of the edge localized mode (ELM) by using resonant magnetic perturbations (RMPs) in the EAST tokamak is presented. This is the first demonstration of ELM suppression with RMPs in slowly rotating plasmas with dominant radio-frequency wave heating. Changes of edge magnetic topology after the transition are indicated by a gradual phase shift in the plasma response field from a linear magneto hydro dynamics modeling result to a vacuum one and a sudden increase of three-dimensional particle flux to the divertor. The transition threshold depends on the spectrum of RMPs and plasma rotation as well as perturbation amplitude. This means that edge topological changes resulting from nonlinear plasma response plays a key role in the suppression of ELM with RMPs. DOI: 10.1103/PhysRevLett.117.115001 Magnetic reconnection and the resultant topological change play an important role in plasma dynamics in both laboratory and space plasma physics research. The formation of an edge stochastic magnetic field caused by resonant magnetic perturbations (RMPs) is believed to be the reason for the suppression of periodic crash events near the plasma edge known as the edge localized mode (ELM) observed in the DIII-D tokamak [1]. The ELM causes transient heat loads to the plasma facing components and may degrade them on the next generation fusion device like ITER [2]. The reduction of free energy in the edge pressure gradient and current because of field stochasticity moves the plasma into a stable regime against the ELM [3]. This successful experiment motivated ELM control using RMPs in many other tokamaks [4][5][6][7]. However, the plasma response effect usually shields the external applied RMPs and may significantly reduce the magnetic field stochasticity [8][9][10][11], which makes this mechanism questionable. Different from topological change, the linear peelinglike magneto hydro dynamics (MHD) response has been found to play an important role in ELM control [12][13][14]. Nonlinear plasma response has been observed in the JET totamak [15]. The possible formation of a magnetic island near the plasma edge [16] with a toroidal Fourier mode number n ¼ 1 during ELM suppression by using n ¼ 2 RMP has been recently observed on DIII-D [17]. However, the key difference between ELM suppression and mitigation and the different roles of linear and nonlinear plasma response on ELM suppression are still not clear.In this Letter, we report the first observation of full ELM suppression using low n RMPs in slowly rotating plasmas with dominant radio-frequency (rf) wave heating, which is potentially important for the application of this method for a future fusion device. This is the first observation of full ELM suppression using RMPs in the medium plasma collisionality regime in EAST, and it expands beyond the previous observations of ELM suppression on DIII-D [1,3] and KSTAR [7]. It is found that not only the formation of a magnetic island near the edge [17] but also a critical leve...

The dopaminergic amacrine cells of the cat retina have been stained by immunocytochemistry using an antibody to tyrosine hydroxylase (Toh). The complete population of Toh+ cells has been studied by light microscopy of retinal wholemounts to evaluate morphological details of dendritic structure and branching patterns. Selected Toh+ amacrine cells have been studied by serial-section electron microscopy to analyse synaptic input and output relationships. The majority of Toh+ amacrine cells occur in the amacrine cell layer of the retina and have their dendrites ramifying and forming the characteristic rings in stratum 1 of the inner plexiform layer. A minority of Toh+ cells have cell bodies displaced to the ganglion cell layer but their dendrites also stratify in stratum 1. All Toh+ cells have some dendritic branches running in stratum 2 as well as in stratum 1, and frequently they have long 'axon-like' processes (500-1000 microns long) dipping down to run in stratum 5 before passing up to rejoin the major dendritic arbors in stratum 1. In addition Toh+ stained processes follow blood vessels in the inner plexiform layer and in the ganglion cell layer. A population of Toh+ cells found in the inferior retina appears to give rise to stained processes that pass to the outer plexiform layer and therein to run for as far as one millimeter. Electron microscopy reveals that Toh+ amacrine cells are postsynaptic to amacrine cells and a few bipolar cell terminals in stratum 1 of the inner plexiform layer and are primarily presynaptic to AII amacrine cell bodies and lobular appendages, and to another type of amacrine cell body and amacrine dendrites hypothesized to be the A17 amacrine cell. The Toh+ dendrites in stratum 2 are presynaptic to AII lobular appendages primarily. Stained 'axon-like' processes running in stratum 5 prove to be presynaptic to AII amacrine dendrites as they approach the rod bipolar axon terminals and they may also be presynaptic to the rod bipolar terminal itself. The Toh+ stained dendrites that have been followed in the outer plexiform layer run along the top of the B-type horizontal cell somata and may have small synapses upon them. The only clear synapses seen in the outer plexiform layer are from the Toh+ profiles upon vesicle filled amacrine-like profiles that are in turn presynaptic to bipolar cell dendrites in the outer plexiform layer. We presume the cells postsynaptic to the Toh+ dendrites in the outer plexiform layer are interplexiform cells.(ABSTRACT TRUNCATED AT 400 WORDS)

NAC domain transcription factors are important regulators that activate the secondary wall biosynthesis in wood formation. In this work, we investigated the possible functions of an NAC family member SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN2 (PtSND2) using chimeric repressor silencing technology. Reverse transcription-polymerase chain reaction, subcellular localization and transcriptional activation analyses indicated that PtSND2 is a wood-associated transcriptional factor with the predicted transcriptional activation activity, which could be inhibited by the repression domain SUPERMAN REPRESSION DOMAIN X (SRDX) in yeast. Wood formation was severely repressed in transgenic poplar plants overexpressing PtSND2-SRDX. Meanwhile, the secondary cell wall thickness of xylem fibers was restrained, and the contents of cellulose and lignin were obviously decreased in the stems of transgenic plants. Further studies indicated that expressions of a number of wood-associated genes were down-regulated in the stems of transgenic plants. Our results suggest that PtSND2 may play important roles during the secondary growth of stems in poplar.