An elm EST database for identifying leaf beetle egg-induced defense genes

Directory of Open Access Journals (Sweden)

Büchel Kerstin

2012-06-01

Full Text Available Abstract Background Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor, egg laying by the elm leaf beetle ( Xanthogaleruca luteola activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. Results Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i untreated control elms, and elms treated with (ii egg laying and feeding by elm leaf beetles, (iii feeding, (iv artificial transfer of egg clutches, and (v methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs were identified which clustered into 52,823 unique transcripts (Unitrans and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction

An elm EST database for identifying leaf beetle egg-induced defense genes.

Science.gov (United States)

Büchel, Kerstin; McDowell, Eric; Nelson, Will; Descour, Anne; Gershenzon, Jonathan; Hilker, Monika; Soderlund, Carol; Gang, David R; Fenning, Trevor; Meiners, Torsten

2012-06-15

Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor), egg laying by the elm leaf beetle ( Xanthogaleruca luteola) activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i) untreated control elms, and elms treated with (ii) egg laying and feeding by elm leaf beetles, (iii) feeding, (iv) artificial transfer of egg clutches, and (v) methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs) were identified which clustered into 52,823 unique transcripts (Unitrans) and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant) database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction, transport and primary metabolism

PROGRESS IN THE PEELING-BALLOONING MODEL OF ELMS: NUMERICAL STUDIES OF 3D NONLINEAR ELM DYNAMICS

International Nuclear Information System (INIS)

SNYDER, P.B.; WILSON, H.R.; XU, X.Q.

2004-01-01

Nonlinear simulations with the 3D electromagnetic two-fluid BOUT code are employed to study the dynamics of edge localized modes (ELMs) driven by intermediate wavelength peeling-ballooning modes. It is found that the early behavior of the modes is similar to expectations from linear, ideal peeling-ballooning mode theory, with the modes growing linearly at a fraction of the Alfven frequency. In the nonlinear phase, the modes grow explosively, forming a number of extended filaments which propagate rapidly from the outer closed flux region into the open flux region toward the outboard wall. Similarities to non-linear ballooning theory, as well as additional complexities are observed. Comparison to observations reveals a number of similarities. Implications of the simulations and proposals for the dynamics of the full ELM crash are discussed

Observation of Current Structures at Type-III ELM Onset on EAST

DEFF Research Database (Denmark)

Yan, Ning; Naulin, Volker; Xu, G.

structure. To verify the current characteristic of this structure, a mono-polar current filaments model was involved, which can reproduce same pattern commendably. Thus, current transport may dominant in transitional stage and plays an important role in the nonlinear development phase of ELM exhaustive......In far scrape-o layer (SOL), alternating negative and positive burst structures in ion saturation current were detected at the onset of each type-III edge localized mode (ELM) on EAST. Different from the fast streaming phenomenon reported previously, one subsequent positive burst structure appears...... every time in the early phase of ELM. It seems like a quick transitional stage between edge localized mode (MHD) phase and transport phase during the ELM. A pronounced sinusoidal pattern has been observed on the radial magnetic induction signal by Langmuir - magnetic probe, corresponding with almost...

Filament-induced remote surface ablation for long range laser-induced breakdown spectroscopy operation

International Nuclear Information System (INIS)

Rohwetter, Ph.; Stelmaszczyk, K.; Woeste, L.; Ackermann, R.; Mejean, G.; Salmon, E.; Kasparian, J.; Yu, J.; Wolf, J.-P.

2005-01-01

We demonstrate laser induced ablation and plasma line emission from a metallic target at distances up to 180 m from the laser, using filaments (self-guided propagation structures ∼ 100 μm in diameter and ∼ 5 x 10 13 W/cm 2 in intensity) appearing as femtosecond and terawatt laser pulses propagating in air. The remarkable property of filaments to propagate over a long distance independently of the diffraction limit opens the frontier to long range operation of the laser-induced breakdown spectroscopy technique. We call this special configuration of remote laser-induced breakdown spectroscopy 'remote filament-induced breakdown spectroscopy'. Our results show main features of filament-induced ablation on the surface of a metallic sample and associated plasma emission. Our experimental data allow us to estimate requirements for the detection system needed for kilometer-range remote filament-induced breakdown spectroscopy experiment

Modeling of ELM Dynamics in ITER

International Nuclear Information System (INIS)

Pankin, A.Y.; Bateman, G.; Kritz, A.H.; Brennan, D.P.; Snyder, P.B.; Kruger, S.

2007-01-01

Edge localized modes (ELMs) are large scale instabilities that alter the H-mode pedestal, reduce the total plasma stored energy, and can result in heat pulses to the divertor plates. These modes can be triggered by pressure driven ballooning modes or by current driven peeling instabilities. In this study, stability analyses are carried out for a series of ITER equilibria that are generated with the TEQ and TOQ equilibrium codes. The H-mode pedestal pressure and parallel component of plasma current density are varied in a systematic way in order to include the relevant parameter space for a specific ITER discharge. Ideal MHD stability codes, DCON, ELITE, and BALOO code, are employed to determine whether or not each ITER equilibrium profile is unstable to peeling or ballooning modes in the pedestal region. Several equilibria that are close to the marginal stability boundary for peeling and ballooning modes are tested with the NIMROD non-ideal MHD code. The effects of finite resistivity are studied in a series of linear NIMROD computations. It is found that the peeling-ballooning stability threshold is very sensitive to the resistivity and viscosity profiles, which vary dramatically over a wide range near the separatrix. Due to the effects of finite resistivity and viscosity, the peeling-ballooning stability threshold is shifted compared to the ideal threshold. A fundamental question in the integrated modeling of ELMy H-mode discharges concerning how much plasma and current density is removed during each ELM crash can be addressed with nonlinear non-ideal MHD simulations. In this study, the NIMROD computer simulations are continued into the nonlinear stage for several ITER equilibria that are marginally unstable to peeling or ballooning modes. The role of two-fluid and finite Larmor radius effects on the ELM dynamics in ITER geometry is examined. The formation of ELM filament structures, which are observed in many existing tokamak experiments, is demonstrated for ITER

ELM-induced transient tungsten melting in the JET divertor

International Nuclear Information System (INIS)

Coenen, J.W.; Clever, M.; Knaup, M.; Arnoux, G.; Matthews, G.F.; Balboa, I.; Meigs, A.; Bazylev, B.; Autricque, A.; Dejarnac, R.; Horacek, J.; Komm, M.; Coffey, I.; Corre, Y.; Gauthier, E.; Devaux, S.; Krieger, K.; Frassinetti, L.; Jachmich, S.; Marsen, S.

2015-01-01

The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER. Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of I P  = 3.0 MA/B T  = 2.9 T H-mode pulses with an input power of P IN  = 23 MW, a stored energy of ∼6 MJ and regular type I ELMs at ΔW ELM  = 0.3 MJ and f ELM  ∼ 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within ∼1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (δW ∼ 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957–64). Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (∼80 µm) were released. Almost 1 mm (∼6 mm 3 ) of W was moved by ∼150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j

ELM-induced transient tungsten melting in the JET divertor

Science.gov (United States)

Coenen, J. W.; Arnoux, G.; Bazylev, B.; Matthews, G. F.; Autricque, A.; Balboa, I.; Clever, M.; Dejarnac, R.; Coffey, I.; Corre, Y.; Devaux, S.; Frassinetti, L.; Gauthier, E.; Horacek, J.; Jachmich, S.; Komm, M.; Knaup, M.; Krieger, K.; Marsen, S.; Meigs, A.; Mertens, Ph.; Pitts, R. A.; Puetterich, T.; Rack, M.; Stamp, M.; Sergienko, G.; Tamain, P.; Thompson, V.; Contributors, JET-EFDA

2015-02-01

The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER. Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of IP = 3.0 MA/BT = 2.9 T H-mode pulses with an input power of PIN = 23 MW, a stored energy of ˜6 MJ and regular type I ELMs at ΔWELM = 0.3 MJ and fELM ˜ 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within ˜1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (δW ˜ 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957-64). Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (˜80 µm) were released. Almost 1 mm (˜6 mm3) of W was moved by ˜150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j × B forces. The evaporation rate determined

Elm genetic diversity and hybridization in the presence of Dutch elm disease

Science.gov (United States)

Johanne Brunet; Raymond P. Guries

2017-01-01

The impact of Dutch elm disease (DED) on the genetic diversity of slippery elm (Ulmus rubra) is summarized and its potential impact on the genetic diversity of other North American native elms, American elm (U. americana), rock elm (U. thomasii), winged elm (U. alata), cedar elm (

Elm diseases

Science.gov (United States)

John W. Peacock

1989-01-01

Dutch elm disease was found in Cleveland, Ohio, in 1930, and is now in most of the contiguous 48 states. The disease is caused by a fungus that has killed millions of wild and planted elms. Losses have been the greatest in the eastern United States. The fungus attacks all elms, but our native species, American, slippery, and rock elm have little or no resistance to the...

Laser-induced filaments in the mid-infrared

International Nuclear Information System (INIS)

Zheltikov, A M

2017-01-01

Laser-induced filamentation in the mid-infrared gives rise to unique regimes of nonlinear wave dynamics and reveals in many ways unusual nonlinear-optical properties of materials in this frequency range. The λ 2 scaling of the self-focusing threshold P cr , with radiation wavelength λ , allows the laser powers transmitted by single mid-IR filaments to be drastically increased without the loss of beam continuity and spatial coherence. When extended to the mid-infrared, laser filamentation enables new methods of pulse compression. Often working around the universal physical limitations, it helps generate few-cycle and subcycle field waveforms within an extraordinarily broad range of peak powers, from just a few up to hundreds of P cr . As a part of a bigger picture, laser-induced filamentation in the mid-infrared offers important physical insights into the general properties of the nonlinear-optical response of matter as a function of the wavelength. Unlike their near-infrared counterparts, which can be accurately described within the framework of perturbative nonlinear optics, mid-infrared filaments often entangle perturbative and nonperturbative nonlinear-optical effects, showing clear signatures of strong-field optical physics. With the role of nonperturbative nonlinear-optical phenomena growing, as a general tendency, with the field intensity and the driver wavelength, extension of laser filamentation to even longer driver wavelengths, toward the long-wavelength infrared, promises a hic sunt dracones land. (topical review)

Dutch elm disease

Science.gov (United States)

James W. Walters

1992-01-01

Since its discovery in the United States in 1930, Dutch elm disease has killed thousands of native elms. The three native elms, American, slippery, and rock, have little or no resistance to Dutch elm disease, but individual trees within each species vary in susceptibility to the disease. The most important of these, American elm, is scattered in upland stands but is...

Non-linear simulations of ELMs in ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Lessig, Alexander; Hoelzl, Matthias; Orain, Francois; Guenter, Sibylle [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, 85748 Garching (Germany); Becoulet, Marina; Huysmans, Guido [CEA-IRFM, Cadarache, 13108 Saint-Paul-Lez-Durance (France); Collaboration: the ASDEX Upgrade Team

2016-07-01

Large edge localized modes (ELMs) are a severe concern for the operation of future tokamak devices like ITER or DEMO due to the high transient heat loads induced on divertor targets and wall structures. It is therefore important to study ELMs both theoretically and experimentally in order to obtain a comprehensive understanding of the underlying mechanisms which is necessary for the prediction of ELM properties and the design of ELM mitigation systems. Using the non-linear MHD code JOREK, we have performed first simulations of full ELM crashes in ASDEX Upgrade, taking into account a large number of toroidal Fourier harmonics. The evolution of the toroidal mode spectrum has been investigated. In particular, we confirm the previously observed non-linear drive of linearly sub-dominant low-n components in the early non-linear phase of the ELM crash. Preliminary comparisons of the simulations with experimental observations regarding heat and particle losses, pedestal evolution and heat deposition patterns are shown. On the long run we aim at code validation as well as an improved understanding of the ELM dynamics and possibly a better characterization of different ELM types.

Modeling elm growth and Dutch elm disease susceptibility

Science.gov (United States)

Alberto Santini; Luisa Ghelardini

2012-01-01

Elm susceptibility to Dutch elm disease (DED) displays strong seasonal variation. The period during which elms can become infected and express DED symptoms is generally restricted to several weeks after growth resumption in spring, although it can vary among species, provenances, and environmental conditions. The reason for this phenomenon is not understood, but the...

Elm genetic diversity and hybridization in the presence of Dutch elm disease

Science.gov (United States)

Dutch elm disease (DED) has devastated native North American elm species for more than 75 years. The impact of DED on the genetic diversity of one native elm species, U. rubra or slippery elm, is summarized and its potential impact on the genetic diversity of the other four North American native elm...

Dutch elm disease pathogen transmission by the banded elm bark beetle Scolytus schevyrewi

Science.gov (United States)

W. R. Jacobi; R. D. Koski; J. F. Negron

2013-01-01

Dutch Elm Disease (DED) is a vascular wilt disease of Ulmus species (elms) incited in North America primarily by the exotic fungus Ophiostoma novo-ulmi. The pathogen is transmitted via root grafts and elm bark beetle vectors, including the native North American elm bark beetle, Hylurgopinus rufipes and the exotic smaller European elm bark beetle, Scolytus multistriatus...

Hydrodynamic interaction induced spontaneous rotation of coupled active filaments.

Science.gov (United States)

Jiang, Huijun; Hou, Zhonghuai

2014-12-14

We investigate the coupled dynamics of active filaments with long range hydrodynamic interactions (HI). Remarkably, we find that filaments can rotate spontaneously under the same conditions in which a single filament alone can only move in translation. Detailed analysis reveals that the emergence of coupled rotation originates from an asymmetric flow field associated with HI which breaks the symmetry of translational motion when filaments approach. The breaking is then further stabilized by HI to form self-sustained coupled rotation. Intensive simulations show that coupled rotation forms easily when one filament tends to collide with the front-half of the other. For head-to-tail approaching, we observe another interesting HI-induced coupled motion, where filaments move together in the form of one following the other. Moreover, the radius of coupled rotation increases exponentially as the rigidity of the filament increases, which suggests that HI are also important for the alignment of rigid-rod-like filaments which has been assumed to be solely a consequence of direct collisions.

Effect of pedestal fluctuation on ELM frequency in the EAST tokamak

Science.gov (United States)

Zhong, F. B.; Zhang, T.; Liu, Z. X.; Qu, H.; Liu, H. Q.; Li, G. Q.; Liu, Y.; Gao, W.; Duan, Y. M.; Yang, Y.; Zeng, L.; Xiang, H. M.; Geng, K. N.; Wen, F.; Zhang, S. B.; Gao, X.; the EAST Team

2018-05-01

The dependence of ELM frequency on heating power has been studied on the Experimental Advanced Superconducting Tokamak (EAST). It is found that the ELM frequency (f ELM) generally increases with the power through separatrix (P sep), indicating type-I ELM in these plasmas. However, there are two data points, named ‘abnormal ELM’ in the present paper, which have much lower f ELM than the ‘normal ELM’, while both types of ELM have similar ELM energy losses. The ‘abnormal ELM’ occurs at a phase with increased radiation power due to metal impurity influx events. The increased radiation power cannot explain the much lower f ELM for ‘abnormal ELM’, since the reduction of P sep is weaker than proportional to the observed reduction of the ELM frequency. The ‘abnormal ELM’ feature can be attributed to the enhanced amplitude of a coherent mode in the pedestal region. Comparing the pedestal evolutions for the two types of ELM with similar separatrix power P sep, it is actually found that the more pronounced pedestal coherent mode in the plasma with ‘abnormal ELM’ leads to a slower pressure pedestal recovery during the inter-ELM phase. This experimental result implies that the physical mechanism for ‘abnormal ELM’ is that the more pronounced pedestal fluctuation induces larger outward transport, slows down the pedestal evolution and leads to longer inter-ELM phase, i.e. lower ELM frequency.

Slippery Elm

Science.gov (United States)

Slippery elm is a tree that is native to eastern Canada and the eastern and central United States. ... whole bark) is used as medicine. People take slippery elm by mouth for coughs, sore throat, colic, diarrhea, ...

Laser-filamentation-induced condensation and snow formation in a cloud chamber.

Science.gov (United States)

Ju, Jingjing; Liu, Jiansheng; Wang, Cheng; Sun, Haiyi; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

2012-04-01

Using 1 kHz, 9 mJ femtosecond laser pulses, we demonstrate laser-filamentation-induced spectacular snow formation in a cloud chamber. An intense updraft of warm moist air is generated owing to the continuous heating by the high-repetition filamentation. As it encounters the cold air above, water condensation and large-sized particles spread unevenly across the whole cloud chamber via convection and cyclone like action on a macroscopic scale. This indicates that high-repetition filamentation plays a significant role in macroscopic laser-induced water condensation and snow formation.

ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

Energy Technology Data Exchange (ETDEWEB)

Baylor, Larry R. [ORNL; Lang, P. [EURATOM / UKAEA, Abingdon, UK; Allen, S. L. [Lawrence Livermore National Laboratory (LLNL); Lasnier, C. J. [Lawrence Livermore National Laboratory (LLNL); Meitner, Steven J. [ORNL; Combs, Stephen Kirk [ORNL; Commaux, Nicolas JC [ORNL; Loarte, A. [ITER Organization, Cadarache, France; Jernigan, Thomas C. [ORNL

2015-08-01

The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components (PFCs). Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet is injected. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation.A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of these issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.

Influence of the plasma pedestal parameters on ELM mitigation at low collisionality

Energy Technology Data Exchange (ETDEWEB)

Leuthold, Nils [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Universitaet Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth (Germany); Suttrop, Wolfgang [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

2016-07-01

The control of Edge Localized Modes (ELMs) is of great importance for future fusion devices in order to provide longevity of the plasma facing components and a better overall plasma performance. In recent magnetic perturbation ELM mitigation experiments in ASDEX Upgrade at low pedestal collisionality, the dependence of ELM losses on pedestal parameters is investigated. It is found that the reduction of the stored energy loss associated with ELMs occurs in correlation with a reduction of edge density and edge pedestal pressure induced by the applied magnetic perturbation (''pedestal pump-out''). Significant ELM mitigation occurs at lowest densities, in a region of pedestal n-T parameter space that has not been accessible in ASDEX Upgrade without magnetic perturbations, and which is occupied by type-IV ELMs in DIII-D. The role of magnetic perturbations for ELM mitigation will be discussed in this context and attempts to counteract the confinement loss by increasing neutral beam injection power or pellet injection increases the ELM energy losses.

Ulmus crassifolia Nutt. Cedar Elm

Science.gov (United States)

John J. Stransky; Sylvia M. Bierschenk

1990-01-01

Cedar elm (Ulmus cassifolia) grows rapidly to medium or large size in the Southern United States and northeastern Mexico, where it may sometimes be called basket elm, red elm, southern rock elm, or olmo (Spanish) It usually is found on moist, limestone soils along water courses with other bottomland trees, but it also paws on dry limestone hills. The...

Bundling of elastic filaments induced by hydrodynamic interactions

Science.gov (United States)

Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

2017-12-01

Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long

Density profiles in the Scrape-Off Layer interpreted through filament dynamics

Science.gov (United States)

Militello, Fulvio

2017-10-01

We developed a new theoretical framework to clarify the relation between radial Scrape-Off Layer density profiles and the fluctuations that generate them. The framework provides an interpretation of the experimental features of the profiles and of the turbulence statistics on the basis of simple properties of the filaments, such as their radial motion and their draining towards the divertor. L-mode and inter-ELM filaments are described as a Poisson process in which each event is independent and modelled with a wave function of amplitude and width statistically distributed according to experimental observations and evolving according to fluid equations. We will rigorously show that radially accelerating filaments, less efficient parallel exhaust and also a statistical distribution of their radial velocity can contribute to induce flatter profiles in the far SOL and therefore enhance plasma-wall interactions. A quite general result of our analysis is the resiliency of this non-exponential nature of the profiles and the increase of the relative fluctuation amplitude towards the wall, as experimentally observed. According to the framework, profile broadening at high fueling rates can be caused by interactions with neutrals (e.g. charge exchange) in the divertor or by a significant radial acceleration of the filaments. The framework assumptions were tested with 3D numerical simulations of seeded SOL filaments based on a two fluid model. In particular, filaments interact through the electrostatic field they generate only when they are in close proximity (separation comparable to their width in the drift plane), thus justifying our independence hypothesis. In addition, we will discuss how isolated filament motion responds to variations in the plasma conditions, and specifically divertor conditions. Finally, using the theoretical framework we will reproduce and interpret experimental results obtained on JET, MAST and HL-2A.

ELM frequency dependence on toroidal rotation in the grassy ELM regime in JT-60U

International Nuclear Information System (INIS)

Oyama, N; Kamada, Y; Isayama, A; Urano, H; Koide, Y; Sakamoto, Y; Takechi, M; Asakura, N

2007-01-01

A systematic study of the effect of the level of toroidal plasma rotation at the top of the ion temperature pedestal ( T i ped ) on the edge localised mode (ELM) characteristics in JT-60U has been performed. The level of toroidal plasma rotation was varied by using different combinations of tangential and perpendicular neutral beam injection (NBI). In the grassy ELM regime at high triangularity (δ) and high safety factor (q), the ELM frequency clearly increased up to 1400 Hz, when counter (ctr) plasma rotation was increased. The response of the ELM frequency was independent of poloidal beta (β p ) in the range 0.84 p 0.53. Even in non-rotating plasma with balanced-NBIs, a high ELM frequency of ∼400 Hz was observed without a large energy loss. When the frequency of the plasma rotation in the co-direction of the plasma current became higher than ∼1 kHz, type I ELMs with a frequency of ∼20 Hz was observed. The achieved pedestal pressure and plasma confinement were similar both in plasmas with type I ELMs and in plasmas with grassy ELMs. The energy loss due to grassy ELMs was evaluated from the reduction in the electron temperature, and the ratio of the energy loss to the pedestal stored energy was less than 1%

Novel insights into the elm yellows phytoplasma genome and into the metagenome of elm yellows-infected elms

Science.gov (United States)

Christina Rosa; Paolo Margaria; Scott M. Geib; Erin D. Scully

2017-01-01

In North America, American elms were historically present throughout the northeastern United States and southeastern Canada. The longevity of these trees, their resistance to the harsh urban environment, and their aesthetics led to their wide use in landscaping and streetscaping over several decades. American elms were one of most cultivated plants in the United States...

Filament-induced luminescence and supercontinuum generation in undoped, Yb-doped, and Nd-doped YAG crystals

Science.gov (United States)

Kudarauskas, D.; Tamošauskas, G.; Vengris, M.; Dubietis, A.

2018-01-01

We present a comparative spectral study of filament-induced luminescence and supercontinuum generation in undoped, Yb-doped, and Nd-doped YAG crystals. We show that supercontinuum spectra generated by femtosecond filamentation in undoped and doped YAG crystals are essentially identical in terms of spectral extent. On the other hand, undoped and doped YAG crystals exhibit remarkably different filament-induced luminescence spectra whose qualitative features are independent of the excitation wavelength and provide information on the energy deposition to embedded dopants, impurities, and the crystal lattice itself. Our findings suggest that filament-induced luminescence may serve as a simple and non-destructive tool for spectroscopic studies in various transparent dielectric media.

Laser filament-induced aerosol formation

Directory of Open Access Journals (Sweden)

H. Saathoff

2013-05-01

Full Text Available Using the aerosol and cloud simulation chamber AIDA, we investigated the laser filament induced particle formation in ambient air, humid synthetic air, humid nitrogen, argon–oxygen mixture, and pure argon in order to simulate the particle formation under realistic atmospheric conditions as well as to investigate the influence of typical gas-phase atmospheric constituents on the particle formation. Terawatt laser plasma filaments generated new particles in the size range 3 to 130 nm with particle production rates ranging from 1 × 107 to 5 × 109 cm−3 plasma s−1 for the given experimental conditions. In all cases the particle formation rates increased exponentially with the water content of the gas mixture. Furthermore, the presence of a few ppb of trace gases like SO2 and α-pinene clearly enhanced the particle yield by number, the latter also by mass. Our findings suggest that new particle formation is efficiently supported by oxidized species like acids generated by the photoionization of both major and minor components of the air, including N2, NH3, SO2 and organics.

The Italian elm breeding program for Dutch elm disease resistance

Science.gov (United States)

Alberto Santini; Francesco Pecori; Luisa Ghelardini

2012-01-01

In the 20th century, elms across Europe and North America were devastated by two pandemics of Dutch elm disease (DED), caused by the introduction of two fungal pathogens: Ophiostoma ulmi, followed by O. novo-ulmi. At the end of 1920s, research into a resistance to DED began in Europe and then in the United States. No...

The spatial structure of type-I ELMs at the mid-plane in ASDEX Upgrade and a comparison with data from MAST

International Nuclear Information System (INIS)

Kirk, A; Eich, T; Herrmann, A; Muller, H W; Horton, L D; Counsell, G F; Price, M; Rohde, V; Bobkov, V; Kurzan, B; Neuhauser, J; Wilson, H

2005-01-01

The radial extent and spatial structure of type-I edge localized modes (ELMs) in ASDEX Upgrade are investigated using data from a mid-plane manipulator equipped with Langmuir probes and a fast visible imaging camera and are compared to data from MAST. Plasmas with a range of toroidal magnetic fields have been studied. The radial extent of the ELM efflux is found to be largest at the smaller toroidal magnetic field. A study of a series of shots on ASDEX Upgrade with different plasma edge to wall separation suggests that the closeness of the wall does not have a stabilizing effect on the radial extent of the ELM. The data from the mid-plane manipulator and from visible imaging are consistent with non-linear ballooning mode theory, which predicts that the ELM has a filament like structure. On both devices these structures have a poloidal extent of 5-10 cm and a typical toroidal mode number of ∼15 and are found to accelerate away from the plasma edge. The acceleration is ∼3 times larger on MAST than on ASDEX Upgrade

Effect of ELMs on rotation and momentum confinement in H-mode discharges in JET

DEFF Research Database (Denmark)

Versloot, T.W.; de Vries, P.C.; Giroud, C.

2010-01-01

. An increase in profile peaking of ion temperature and angular frequency is observed. At the same time the plasma confinement is reduced while the ratio of confinement times (Rτ = τE/τ) increases noticeably with ELM frequency. This change could be explained by the relatively larger ELM induced losses......The loss of plasma toroidal angular momentum and thermal energy by edge localized modes (ELMs) has been studied in JET. The analysis shows a consistently larger drop in momentum in comparison with the energy loss associated with the ELMs. This difference originates from the large reduction...... in angular frequency at the plasma edge, observed to penetrate into the plasma up to r/a ~ 0.65 during large type-I ELMs. As a result, the time averaged angular frequency is lowered near the top of the pedestal with increasing ELM frequency, resulting in a significant drop in thermal Mach number at the edge...

Latest investigations on fluctuations, ELM filaments and turbulent transport in the SOL of ASDEX Upgrade

Czech Academy of Sciences Publication Activity Database

Müller, H. W.; Adámek, Jiří; Cavazzana, R.; Conway, G.D.; Fuchs, C.; Gunn, J. P.; Herrmann, A.; Horáček, Jan; Ionita, C.; Kallenbach, A.; Kočan, M.; Maraschek, M.; Maszl, C.; Mehlmann, F.; Nold, B.; Peterka, M.; Rohde, V.; Schweinzer, J.; Schrittwieser, R.; Vianello, N.; Wolfrum, E.; Zuin, M.

2011-01-01

Roč. 51, č. 7 (2011), 073023-073023 ISSN 0029-5515 R&D Projects: GA AV ČR KJB100430901 Institutional research plan: CEZ:AV0Z20430508 Keywords : SOL * ASDEX * ELM * tokamak * ball- pen * H-mode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.090, year: 2011 http://iopscience.iop.org/0029-5515/51/7/073023/pdf/0029-5515_51_7_073023.pdf

Radiation-induced grafting of acrylic acid onto polyethylene filaments

International Nuclear Information System (INIS)

Kaji, K.; Sakurada, I.; Okada, T.

1981-01-01

Radiation-induced grafting of acrylic acid onto high density polyethylene (PE) filaments was carried out in order to raise softening temperature and impart flame retardance and hydrophilic properties. Mutual γ-irradiation method was employed for the grafting in a mixture of acrylic acid (AA), ethylene dichloride and water containing a small amount of ferrous ammonium sulfate. The rate of grafting was very low at room temperature. On the other hand, large percent grafts were obtained when the grafting was performed at an elevated temperature. Activation energy for the initial rate of grafting was found to be 17 kcal/mol between 20 and 60 0 C and 10 kcal/ mol between 60 and 80 0 C. Original PE filament begins to shrink at 70 0 C, shows maximum shrinkage of 50% at 130 0 C and then breaks off at 136 0 C. When a 34% AA graft is converted to metallic salt the graft filament retains its filament form even above 300 0 C and gives maximum shrinkage of 15%. Burning tests by a wire-netting basket method indicate that graft filaments and their metallic salts do not form melting drops upon burning and are self-extinguishing. Original PE filament shows no moisture absorption; however, that of AA-grafted PE increases with increasing graft percent. (author)

Do mites phoretic on elm bark beetles contribute to the transmission of Dutch elm disease?

Science.gov (United States)

John Moser; Heino Konrad; Stacy Blomquist; Thomas Kirisits

2010-01-01

Dutch elm disease (DED) is a destructive vascular wilt disease of elm (Ulmus) trees caused by the introduced Ascomycete fungus Ophiostoma novo-ulmi. In Europe, this DED pathogen is transmitted by elm bark beetles in the genus Scolytus. These insects carry phoretic mites to new, suitable habitats. The aim of this...

Beam deflection induced by E×B near a linear filament cathode

Energy Technology Data Exchange (ETDEWEB)

Zhang, Huashun; Jiang, Jiasheng

2017-02-21

Beam deflection induced by E×B near a linear filament cathode in a two grid electron gun is presented theoretically and experimentally. The experimental results are consistent with the calculation based on the theoretical equations. The influences upon performance and design of electron gun with linear filament cathode, which is used broadly in electrocurtain accelerators, are discussed in detail.

Measurements and modeling of intra-ELM tungsten sourcing and transport in DIII-D

Science.gov (United States)

Abrams, T.; Leonard, A. W.; Thomas, D. M.; McLean, A. G.; Makowski, M. A.; Wang, H. Q.; Unterberg, E. A.; Briesemeister, A. R.; Rudakov, D. L.; Bykov, I.; Donovan, D.

2017-10-01

Intra-ELM tungsten erosion profiles in the DIII-D divertor, acquired via W I spectroscopy with high temporal and spatial resolution, are consistent with SDTrim.SP sputtering modeling using measured ion saturation currents and impact energies during ELMs as input and an ad-hoc 2% C2+ impurity flux. The W sputtering profile peaks close to the OSP both during and between ELMs in the favorable BT direction. In reverse BT the W source peaks close to the OSP between ELMs but strongly broadens and shifts outboard during ELMs, heuristically consistent with radially outward ion transport via ExB drifts. Ion impact energies during ELMs (inferred taking the ratio of divertor heat flux to the ion saturation current) are found to be approximately equal to Te,ped, lower than the 4*Te,ped value predicted by the Fundamenski/Moulton free streaming model. These impact energies imply both D main ions and C impurities contribute strongly to W sputtering during ELMs on DIII-D. This work represents progress towards a predictive model to link upstream conditions (i.e., pedestal height) and SOL impurity levels to the ELM-induced W impurity source at both the strike-point and far-target regions in the ITER divertor. Correlations between ELM size/frequency and SOL W fluxes measured via a midplane deposition probe will also be presented. Work supported by US DOE under DE-FC02-04ER54698.

Proceedings of the American elm restoration workshop 2016

Science.gov (United States)

Cornelia C. Pinchot; Kathleen S. Knight; Linda M. Haugen; Charles E. Flower; James M. Slavicek

2017-01-01

Proceedings from the 2016 American Elm Restoration Workshop in Lewis Center, OH. The published proceedings include 16 papers pertaining to elm pathogens, American elm ecology, and American elm reintroduction.

Genotype x environment interaction and growth stability of several elm clones resistant to Dutch elm disease

Science.gov (United States)

Alberto Santini; Francesco Pecori; Alessia L. Pepori; Luisa Ghelardini

2012-01-01

The elm breeding program carried out in Italy at the Institute of Plant Protection - Consiglio Nazionale delle Ricercje (CNR) during the last 40 years aimed to develop Dutch elm disease (DED)-resistant elm selections specific to the Mediterranean environment. The need for genotypes adapted to Mediterranean conditions was evident from the poor performance of the Dutch...

ELM triggering by energetic particle driven mode in wall-stabilized high-β plasmas

International Nuclear Information System (INIS)

Matsunaga, G.; Aiba, N.; Shinohara, K.; Asakura, N.; Isayama, A.; Oyama, N.

2013-01-01

In the JT-60U high-β plasmas above the no-wall β limit, a triggering of an edge localized mode (ELM) by an energetic particle (EP)-driven mode has been observed. This EP-driven mode is thought to be driven by trapped EPs and it has been named EP-driven wall mode (EWM) on JT-60U (Matsunaga et al 2009 Phys. Rev. Lett. 103 045001). When the EWM appears in an ELMy H-mode phase, ELM crashes are reproducibly synchronized with the EWM bursts. The EWM-triggered ELM has a higher repetition frequency and less energy loss than those of the natural ELM. In order to trigger an ELM by the EP-driven mode, some conditions are thought to be needed, thus an EWM with large amplitude and growth rate, and marginal edge stability. In the scrape-off layer region, several measurements indicate an ion loss induced by the EWM. The ion transport is considered as the EP transport through the edge region. From these observations, the EP contributions to edge stability are discussed as one of the ELM triggering mechanisms. (paper)

Structural analysis for the joint of the ITER ELM coil

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shanwen, E-mail: zhangshanwen123@163.com [College of Mechanical Engineering Yangzhou University, Yangzhou 225127 (China); Song, Yuntao; Wang, Zhongwei; Ji, Xiang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 200031 (China); Zhang, Jianfeng [College of Mechanical Engineering Yangzhou University, Yangzhou 225127 (China)

2017-01-15

Highlights: • The FE sub-model method is feasible and rapid for the joint design. • The components meet the static and fatigue criteria. • Nuclear heat is the key factor for the joint design. - Abstract: The joint is an important component of the Edge Localized Modes (ELM) coils in fusion reactor, which is used to connect the ELM coils. Like the ELM coils, the joints work in an environment with high radiation levels, high temperature and high magnetic field. These joints are mainly subject to nuclear heat from the plasma and cyclic electromagnetic (EM) loads induced by the interaction of ELM coil current with magnetic fields. Take the joint of ITER ELM coil for example. In order to assure the structural integrity of joints under these loads, it is necessary to estimate the strength and fatigue of the joints. As a local model, the joint without ELM coil is investigated by the sub-model method. Results show that the finite element sub-model method is feasible and rapid for the joint design. The maximum magnetic flux intensity occurs in the axial direction for the joint local reference, which parallels with the current and corresponds to the toroidal direction of the ITER. The two areas at the top of the Inconel sleeve appear high temperature. For the joint, the conductor, jacket and sleeve can meet the static and fatigue criteria and the joint design is valid and feasible. The thermal load from the nuclear heat is the key factor for the joint design.

Modeling of ELM events and their effect on impurity enrichment

International Nuclear Information System (INIS)

Hogan, J.; Colchin, R.; Coster, D.; Baylor, L.; Fenstermacher, M.; Groth, M.; Wade, M.

2003-01-01

Modeling of transient impurity transport during large ELMs is used to explore basic processes which may determine ELM-averaged enrichment. The b2-Eirene code (solps4), used for DIII-D geometry, suggests that a complex sequence can occur during an ELM cycle in which a transiently detached phase, with relatively low enrichment, can occur even under nominally attached conditions. A slower recovery phase then follows, in which the effect of induced scrape-off layer flows can increase in importance. The model results are compared with available fast time-scale measurements. The observed increased enrichment with higher Z is similar to trends in basic particle reflection properties. Neon recycling processes may thus introduce a significant history effect, as illustrated by analysis of continuous, unforced neon accumulation in a DIII-D discharge with a well-characterized operational history

ELMs and the H-mode pedestal in NSTX

International Nuclear Information System (INIS)

Maingi, R.; Sabbagh, S.A.; Bush, C.E.; Fredrickson, E.D.; Menard, J.E.; Stutman, D.; Tritz, K.; Bell, M.G.; Bell, R.E.; Boedo, J.A.; Gates, D.A.; Johnson, D.W.; Kaita, R.; Kaye, S.M.; Kugel, H.W.; LeBlanc, B.P.; Mueller, D.; Raman, R.; Roquemore, A.L.; Soukhanovskii, V.A.; Stevenson, T.

2005-01-01

We report on the behavior of ELMs in NBI-heated H-mode plasmas in NSTX. It is observed that the size of Type I ELMs, characterized by the change in plasma energy, decreases with increasing line-average density, as observed at conventional aspect ratio. It is also observed that the Type I ELM size decreases as the plasma equilibrium is shifted from a symmetric double-null toward a lower single-null configuration. Type II/III ELMs have also been observed in NSTX, as well as a high-performance regime with small ELMs which we designate Type V. The Type V ELMs are characterized by an intermittent n 1 magnetic pre-cursor oscillation rotating counter to the plasma current; the mode vanishes between Type V ELMs crashes. Without active pumping, the density rises continuously through the Type V phase, albeit at a slower rate than ELM-free discharges

Using Dutch elm disease-tolerant elm to restore floodplains impacted by emerald ash borer

Science.gov (United States)

Kathleen S. Knight; James M. Slavicek; Rachel Kappler; Elizabeth Pisarczyk; Bernadette Wiggin; Karen. Menard

2012-01-01

American elm (Ulmus Americana L.) was a dominant species in floodplains and swamps of the Midwest before Dutch elm disease (DED) (Ophiostoma ulmi and O.novo-ulmi) reduced its populations. In many areas, ash (Fraxinus spp.) became dominant in these ecosystems. Emerald ash borer (EAB) (...

Helical filaments

Energy Technology Data Exchange (ETDEWEB)

Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

2014-06-30

The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

Automated recognition system for ELM classification in JET

International Nuclear Information System (INIS)

Duro, N.; Dormido, R.; Vega, J.; Dormido-Canto, S.; Farias, G.; Sanchez, J.; Vargas, H.; Murari, A.

2009-01-01

Edge localized modes (ELMs) are instabilities occurring in the edge of H-mode plasmas. Considerable efforts are being devoted to understanding the physics behind this non-linear phenomenon. A first characterization of ELMs is usually their identification as type I or type III. An automated pattern recognition system has been developed in JET for off-line ELM recognition and classification. The empirical method presented in this paper analyzes each individual ELM instead of starting from a temporal segment containing many ELM bursts. The ELM recognition and isolation is carried out using three signals: Dα, line integrated electron density and stored diamagnetic energy. A reduced set of characteristics (such as diamagnetic energy drop, ELM period or Dα shape) has been extracted to build supervised and unsupervised learning systems for classification purposes. The former are based on support vector machines (SVM). The latter have been developed with hierarchical and K-means clustering methods. The success rate of the classification systems is about 98% for a database of almost 300 ELMs.

Adaptive Online Sequential ELM for Concept Drift Tackling

Directory of Open Access Journals (Sweden)

Arif Budiman

2016-01-01

Full Text Available A machine learning method needs to adapt to over time changes in the environment. Such changes are known as concept drift. In this paper, we propose concept drift tackling method as an enhancement of Online Sequential Extreme Learning Machine (OS-ELM and Constructive Enhancement OS-ELM (CEOS-ELM by adding adaptive capability for classification and regression problem. The scheme is named as adaptive OS-ELM (AOS-ELM. It is a single classifier scheme that works well to handle real drift, virtual drift, and hybrid drift. The AOS-ELM also works well for sudden drift and recurrent context change type. The scheme is a simple unified method implemented in simple lines of code. We evaluated AOS-ELM on regression and classification problem by using concept drift public data set (SEA and STAGGER and other public data sets such as MNIST, USPS, and IDS. Experiments show that our method gives higher kappa value compared to the multiclassifier ELM ensemble. Even though AOS-ELM in practice does not need hidden nodes increase, we address some issues related to the increasing of the hidden nodes such as error condition and rank values. We propose taking the rank of the pseudoinverse matrix as an indicator parameter to detect “underfitting” condition.

Different ELM regimes at ASDEX upgrade and their linear stability analysis

International Nuclear Information System (INIS)

Burckhart, Andreas O.

2013-01-01

the theory, as the equilibrium becomes more stable against peeling-ballooning modes, the ELM frequency actually increases. Other scenarios in which peeling-ballooning modes are not thought to be the ELM trigger are also examined. In discharges featuring type-II and type-III ELMs the edge pressure gradient and current density are well below the threshold for peeling-ballooning instabilities, consistent with expectations. This indicates that other mechanisms must be present that prevent the kinetic profiles from building up. The behaviour of the analysed type-III ELMs is consistent with the hypothesis that they are driven by resistive interchange modes. The feasibility of triggering ELMs via frozen deuterium pellets is also examined in detail. In discharges performed when the walls of AUG were protected by carbon tiles, pellets triggered ELMs whenever they were injected into an H-mode plasma. In the tungsten-walled AUG, however, it is only possible to trigger ELMs after a specific lag time has elapsed since the previous ELM. This lag time can be significantly reduced, though not eliminated, when injecting nitrogen into the divertor. In the tungsten-walled AUG, with and without nitrogen, it is possible to trigger ELMs via pellets when the pedestal pressure gradient and the edge current density are 20% below the threshold for spontaneous ELMs. Since the ELM-induced collapse of the plasma edge pressure profile is strongest in the unseeded tungsten machine and the profile recovery is slower, the lag time for successful triggering is longer. Recent extrapolations of the ITER pedestal are also tested using the peeling-ballooning model. It is found that the predictions are very optimistic, but that stability could be achieved with temperatures and densities which are 30% lower than in the extrapolations. Some of the results presented in this thesis question the validity of the peeling-ballooning theory. In many of the presented cases, ELMs occur well below the threshold for

Different ELM regimes at ASDEX upgrade and their linear stability analysis

Energy Technology Data Exchange (ETDEWEB)

Burckhart, Andreas O.

2013-12-16

the theory, as the equilibrium becomes more stable against peeling-ballooning modes, the ELM frequency actually increases. Other scenarios in which peeling-ballooning modes are not thought to be the ELM trigger are also examined. In discharges featuring type-II and type-III ELMs the edge pressure gradient and current density are well below the threshold for peeling-ballooning instabilities, consistent with expectations. This indicates that other mechanisms must be present that prevent the kinetic profiles from building up. The behaviour of the analysed type-III ELMs is consistent with the hypothesis that they are driven by resistive interchange modes. The feasibility of triggering ELMs via frozen deuterium pellets is also examined in detail. In discharges performed when the walls of AUG were protected by carbon tiles, pellets triggered ELMs whenever they were injected into an H-mode plasma. In the tungsten-walled AUG, however, it is only possible to trigger ELMs after a specific lag time has elapsed since the previous ELM. This lag time can be significantly reduced, though not eliminated, when injecting nitrogen into the divertor. In the tungsten-walled AUG, with and without nitrogen, it is possible to trigger ELMs via pellets when the pedestal pressure gradient and the edge current density are 20% below the threshold for spontaneous ELMs. Since the ELM-induced collapse of the plasma edge pressure profile is strongest in the unseeded tungsten machine and the profile recovery is slower, the lag time for successful triggering is longer. Recent extrapolations of the ITER pedestal are also tested using the peeling-ballooning model. It is found that the predictions are very optimistic, but that stability could be achieved with temperatures and densities which are 30% lower than in the extrapolations. Some of the results presented in this thesis question the validity of the peeling-ballooning theory. In many of the presented cases, ELMs occur well below the threshold for

Laser induced white lighting of tungsten filament

Science.gov (United States)

Strek, W.; Tomala, R.; Lukaszewicz, M.

2018-04-01

The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

Acoustic Measurement of the Length of Air-plasma Filament Induced by an Intense Femtosecond Laser Pulse

Directory of Open Access Journals (Sweden)

Wu Si-Qing

2017-01-01

Full Text Available The paper studies acoustic emission from air-plasma filament induced by a strong femtosecond laser pulse. Acoustic signal is detected with a sensitive directional microphone. Acoustic measurement provides a new method to determine the length of a filament. Compared with other methods, acoustic measurement is simpler, more sensitive, and with higher spatial resolution. Information of filament length is experimentally acquired through measuring acoustic pressure at different position of filament. On the basis of the relationship between acoustic signal and free-electron density in filament, profile of free-electron density is demonstrated

ELMs IN DIII-D HIGH PERFORMANCE DISCHARGES

International Nuclear Information System (INIS)

TURNBULL, A.D; LAO, L.L; OSBORNE, T.H; SAUTER, O; STRAIT, E.J; TAYLOR, T.S; CHU, M.S; FERRON, J.R; GREENFIELD, C.M; LEONARD, A.W; MILLER, R.L; SNYDER, P.B; WILSON, H.R; ZOHM, H

2003-01-01

A new understanding of edge localized modes (ELMs) in tokamak discharges is emerging [P.B. Snyder, et al., Phys. Plasmas, 9, 2037 (2002)], in which the ELM is an essentially ideal magnetohydrodynamic (MHD) instability and the ELM severity is determined by the radial width of the linearly unstable MHD kink modes. A detailed, comparative study of the penetration into the core of the respective linear instabilities in a standard DIII-D ELMing, high confinement mode (H-mode) discharge, with that for two relatively high performance discharges shows that these are also encompassed within the framework of the new model. These instabilities represent the key, limiting factor in extending the high performance of these discharges. In the standard ELMing H-mode, the MHD instabilities are highly localized in the outer few percent flux surfaces and the ELM is benign, causing only a small temporary drop in the energy confinement. In contrast, for both a very high confinement mode (VH-mode) and an H-mode with a broad internal transport barrier (ITB) extending over the entire core and coalesced with the edge transport barrier, the linearly unstable modes penetrate well into the mid radius and the corresponding consequences for global confinement are significantly more severe. The ELM accordingly results in an irreversible loss of the high performance

The effect of ELMs on energy confinement in JET

International Nuclear Information System (INIS)

Zhang, W.; Tubbing, B.J.D.; Ward, D.J.

1998-01-01

The effect of ELMs on energy confinement in JET has been analysed. ELMs are characterized using D α emission which is decomposed into two components, a baseline level with superimposed pulses due to the ELMs. The analysis of the experimental data shows that the D α baseline, which reflects the neutral pressure at the plasma edge, is an important parameter in determining the energy confinement deterioration. The origin of the D α baseline is either from the neutralization of plasma particles which are expelled by the ELM pulses, or from external gas puffing. An ELM severity parameter, taking into account both the D α baseline and the ELM pulses, is defined. The energy confinement time normalized to the energy confinement time of ELM free phase, τ B /τ H , decreases linearly as the ELM severity increases. The results are independent of divertor configurations. (author)

Transient thermo-structural and static magnetic characteristics of 1:1 prototype JET ELM control coils

Energy Technology Data Exchange (ETDEWEB)

Kundu, Ananya; Pradhan, Subrata, E-mail: pradhan@ipr.res.in; Ghate, Mahesh; Kanabar, Deven; Roy, Swati; Kumar, Nitish

2017-01-15

3D transient thermo-structural analyses and steady state magnetic field analyses of 1:1 prototyped JET Edge Localized Mode (ELM) coils have been carried out. Temperature distribution within the magnet winding as well as the temperature evolution have also been simulated as a function of pulsed transport currents in both large and small ELM coils as per the operational scenarios. The induced thermal stresses along with the shear stress components acting on the winding elements have also been analyzed. The deformations caused by thermal stresses have been calculated for the case, the conductor bundle and the insulation layers within the coils. In addition to thermo-structural analyses, steady state magnetic field analyses have also been carried out in the current carrying ELM coils. These values have been compared with the experimental values. The experimentally obtained values matches well with those obtained in simulations indicating that the prototyped ELM coils can operate successfully in JET operational scenarios. Additionally, the R & D and technologies developed in the context of JET ELM coils have also been validated with the magnet performances experimentally.

Laser-filamentation-induced water condensation and snow formation in a cloud chamber filled with different ambient gases.

Science.gov (United States)

Liu, Yonghong; Sun, Haiyi; Liu, Jiansheng; Liang, Hong; Ju, Jingjing; Wang, Tiejun; Tian, Ye; Wang, Cheng; Liu, Yi; Chin, See Leang; Li, Ruxin

2016-04-04

We investigated femtosecond laser-filamentation-induced airflow, water condensation and snow formation in a cloud chamber filled respectively with air, argon and helium. The mass of snow induced by laser filaments was found being the maximum when the chamber was filled with argon, followed by air and being the minimum with helium. We also discussed the mechanisms of water condensation in different gases. The results show that filaments with higher laser absorption efficiency, which result in higher plasma density, are beneficial for triggering intense airflow and thus more water condensation and precipitation.

Survey of Type I ELM dynamics measurements

International Nuclear Information System (INIS)

Leonard, A W; Asakura, N; Boedo, J A; Becoulet, M; Counsell, G F; Eich, T; Fundamenski, W; Herrmann, A; Horton, L D; Kamada, Y; Kirk, A; Kurzan, B; Loarte, A; Neuhauser, J; Nunes, I; Oyama, N; Pitts, R A; Saibene, G; Silva, C; Snyder, P B; Urano, H; Wade, M R; Wilson, H R

2006-01-01

This report summarizes Type I edge localized mode (ELM) dynamics measurements from a number of tokamaks, including ASDEX-Upgrade, DIII-D, JET, JT-60U and MAST, with the goal of providing guidance and insight for the development of ELM simulation and modelling. Several transport mechanisms are conjectured to be responsible for ELM transport, including convective transport due to filamentary structures ejected from the pedestal, parallel transport due to edge ergodization or magnetic reconnection and turbulent transport driven by the high edge gradients when the radial electric field shear is suppressed. The experimental observations are assessed for their validation, or conflict, with these ELM transport conjectures

Fast dynamics of Type I ELM and transport of ELM pulse in JT-60U

International Nuclear Information System (INIS)

Oyama, N.

2002-01-01

The mitigation of the large ELM heat load on the divertor target is one of the most important issues to be overcome on ITER. Since the ELM heat load strikes the divertor target not as a time-averaged load but as an instantaneous heat pulse, the evaluation of both ELM energy, and the time scale of the collapse and transport is very important. In JT-60U, the detailed dynamic behaviors of the collapse were measured using O-mode reflectometer. The duration of the collapse was within 0.35 ms and the lost pedestal density was recovered quickly within 0.5 ms. The collapse reached 10 cm inside the separatrix, which corresponds to twice the pedestal width of 5 cm. Dedicated edge density measurements on high- and low-field side revealed the poloidal asymmetry of the collapse of density pedestal for the first time. The measurement of SOL flow and heat load to the divertor target by using SOL Mach probe and IRTV showed that convective transport of the SOL plasma gave large contribution to the ELM heat deposition process. (author)

Elms: MHD Instabilities at the transport barrier

Energy Technology Data Exchange (ETDEWEB)

Huysmans, G.T.A

2005-07-01

Significant progress has been made in recent years both on the experimental characterisation of ELMs (edge localized modes) and the theory and modelling of ELMs. The observed maximum pressure gradient is in good agreement with the calculated ideal MHD stability limits due to peeling-ballooning modes. The dependence on plasma current and plasma shape are also reproduced by the ideal MHD model. It will be a challenge to verify experimentally the influence of the extensions to the ideal MHD theory such as the possibly incomplete diamagnetic stabilisation, the influence of shear flow, finite resistivity or the stabilizing influence of the separatrix on peeling modes. The observations of the filamentary structures find their explanation in the theory and simulations of the early non-linear phase of the evolution of ballooning modes. One of the remaining open questions is what determines the size of the ELM and its duration. This is related to the loss mechanism of energy and density. Some heuristic descriptions of possible mechanisms have been proposed in literature but none of the models so far makes quantitative predictions on the ELM size. Also the numerical simulations are not yet advanced to the point where the full ELM crash can be modelled. The theory and simulations of the ELMs are necessary to decide between the possible parameters, such as the collisionality or the parallel transport time, that are proposed for the extrapolation of ELM sizes to ITER.

Elms: MHD Instabilities at the transport barrier

International Nuclear Information System (INIS)

Huysmans, G.T.A.

2005-01-01

Significant progress has been made in recent years both on the experimental characterisation of ELMs (edge localized modes) and the theory and modelling of ELMs. The observed maximum pressure gradient is in good agreement with the calculated ideal MHD stability limits due to peeling-ballooning modes. The dependence on plasma current and plasma shape are also reproduced by the ideal MHD model. It will be a challenge to verify experimentally the influence of the extensions to the ideal MHD theory such as the possibly incomplete diamagnetic stabilisation, the influence of shear flow, finite resistivity or the stabilizing influence of the separatrix on peeling modes. The observations of the filamentary structures find their explanation in the theory and simulations of the early non-linear phase of the evolution of ballooning modes. One of the remaining open questions is what determines the size of the ELM and its duration. This is related to the loss mechanism of energy and density. Some heuristic descriptions of possible mechanisms have been proposed in literature but none of the models so far makes quantitative predictions on the ELM size. Also the numerical simulations are not yet advanced to the point where the full ELM crash can be modelled. The theory and simulations of the ELMs are necessary to decide between the possible parameters, such as the collisionality or the parallel transport time, that are proposed for the extrapolation of ELM sizes to ITER

Toroidally asymmetric ELM precursor oscillations in the TCV tokamak

International Nuclear Information System (INIS)

Reimerdes, H.; Pochelon, A.; Guittienne, P.; Weisen, H.; Suttrop, W.

1997-01-01

In TCV ohmic H-modes have been obtained in diverted single-null (SND), double-null (DND), and elongated limited plasma configurations. In ELM-free H-modes the particle density rises continuously until the discharge usually terminates with a high density disruption. Quasi-stationary H-modes have been obtained in the presence of ELMs. The observed ELM spectrum is continuous and ranges from clearly identifiable type III ELMs to low frequency, large ELMs. The necessity of ELMs for particle control of H-mode plasmas while causing high peak-power loads on strike points makes the control of their level and nature desirable and motivates the study of the underlying MHD-instability. Prior to ELMs in TCV coherent magnetic oscillations, that indicate a rapidly growing MHD instability, have been observed. The structure of these precursor oscillation is investigated with TCV's Mirnov probe arrays. In particular an observed toroidal asymmetry in the growth of the instability has to be explained. (author) 2 figs., 6 refs

Current filaments in turbulent magnetized plasmas

DEFF Research Database (Denmark)

Martines, E.; Vianello, N.; Sundkvist, D.

2009-01-01

gradient region of a fusion plasma confined in reversed field pinch configuration and in a density gradient region in the Earth magnetosphere are measured and compared, showing that in both environments they can be attributed to drift-Alfvén vortices. Current structures associated with reconnection events......Direct measurements of current density perturbations associated with non-linear phenomena in magnetized plasmas can be carried out using in situ magnetic measurements. In this paper we report such measurements for three different kinds of phenomena. Current density fluctuations in the edge density...... measured in a reversed field pinch plasma and in the magnetosheath are detected and compared. Evidence of current filaments occurring during ELMs in an H-mode tokamak plasma is displayed....

Combined Langmuir-magnetic probe measurements of type-I ELMy filaments in the EAST tokamak

Science.gov (United States)

Qingquan, YANG; Fangchuan, ZHONG; Guosheng, XU; Ning, YAN; Liang, CHEN; Xiang, LIU; Yong, LIU; Liang, WANG; Zhendong, YANG; Yifeng, WANG; Yang, YE; Heng, ZHANG; Xiaoliang, Li

2018-06-01

Detailed investigations on the filamentary structures associated with the type-I edge-localized modes (ELMs) should be helpful for protecting the materials of a plasma-facing wall on a future large device. Related experiments have been carefully conducted in the Experimental Advanced Superconducting Tokamak (EAST) using combined Langmuir-magnetic probes. The experimental results indicate that the radially outward velocity of type-I ELMy filaments can be up to 1.7 km s‑1 in the far scrape-off layer (SOL) region. It is remarkable that the electron temperature of these filaments is detected to be ∼50 eV, corresponding to a fraction of 1/6 to the temperature near the pedestal top, while the density (∼ 3× {10}19 {{{m}}}-3) of these filaments could be approximate to the line-averaged density. In addition, associated magnetic fluctuations have been clearly observed at the same time, which show good agreement with the density perturbations. A localized current on the order of ∼100 kA could be estimated within the filaments.

Study of Type III ELMs in JET

Energy Technology Data Exchange (ETDEWEB)

Sartori, R [EFDA Close Support Unit, Garching, 2 Boltzmannstrasse, Garching (Germany); Saibene, G [EFDA Close Support Unit, Garching, 2 Boltzmannstrasse, Garching (Germany); Horton, L D [Association Euratom-IPP, MPI fuer Plasmaphysik, 2 Boltzmannstrasse, Garching (Germany); Becoulet, M [Association Euratom-CEA, CE Cadarache, F-13108 St Paul-lez-Durance, CEDEX (France); Budny, R [PPPL, Princeton University, PO Box 451, Princeton, NJ 08543 (United States); Borba, D [Associacao EURATOM/IST, Centro de Fusao Nuclear, 1096 Lisbon, CODEX (Portugal); Chankin, A [Association Euratom-IPP, MPI fuer Plasmaphysik, 2 Boltzmannstrasse, Garching (Germany); Conway, G D [Association Euratom-IPP, MPI fuer Plasmaphysik, 2 Boltzmannstrasse, Garching (Germany); Cordey, G [EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); McDonald, D [EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Guenther, K [EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Hellermann, M G von [FOM-Rijnhuizen, Ass. Euratom-FOM, TEC, PO Box 1207, 3430 BE Nieuwegein (Netherlands); Igithkanov, Yu [Max-Planck-Institute for Plasma Physics, Teilinstitut Greifswald, EURATOM Ass., D-17491, Greifswald (Germany); Loarte, A [EFDA Close Support Unit, Garching, 2 Boltzmannstrasse, Garching (Germany); Lomas, P J [EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Pogutse, O [EURATOM-UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Rapp, J [EFDA Close Support Unit, Culham, Abingdon OX14 3DB (United Kingdom)

2004-05-01

This paper presents the results of JET experiments aimed at studying the operational space of plasmas with a Type III ELMy edge, in terms of both local and global plasma parameters. In JET, the Type III ELMy regime has a wide operational space in the pedestal n{sub e} - T{sub e} diagram, and Type III ELMs are observed in standard ELMy H-modes as well as in plasmas with an internal transport barrier (ITB). The transition from an H-mode with Type III ELMs to a steady state Type I ELMy H-mode requires a minimum loss power, P{sub TypeI}. P{sub TypeI} decreases with increasing plasma triangularity. In the pedestal n{sub e} - T{sub e} diagram, the critical pedestal temperature for the transition to Type I ELMs is found to be inversely proportional to the pedestal density (T{sub crit} {proportional_to} 1/n) at a low density. In contrast, at a high density, T{sub crit}, does not depend strongly on density. In the density range where T{sub crit} {proportional_to} 1/n, the critical power required for the transition to Type I ELMs decreases with increasing density. Experimental results are presented suggesting a common mechanism for Type III ELMs at low and high collisionality. A single model for the critical temperature for the transition from Type III to Type I ELMs, based on the resistive interchange instability with magnetic flutter, fits well the density and toroidal field dependence of the JET experimental data. On the other hand, this model fails to describe the variation of the Type III n{sub e} - T{sub e} operational space with isotopic mass and q{sub 95}. Other results are instead suggestive of a different physics for Type III ELMs. At low collisionality, plasma current ramp experiments indicate a role of the edge current in determining the transition from Type III to Type I ELMs, while at high collisionality, a model based on resistive ballooning instability well reproduces, in term of a critical density, the experimentally observed q{sub 95} dependence of the

Generation of American elm trees with tolerance to Dutch elm disease through controlled crosses and selection

Science.gov (United States)

James M. Slavicek; Kathleen S. Knight

2012-01-01

The goal of our research and development efforts is to generate new and/or improved selections of the American elm (Ulmus americana L.) with tolerance/resistance to Dutch elm disease (DED). The approaches we are taking for this effort include: 1) controlled breeding using known DED -tolerant selections, 2) controlled breeding using DED-tolerant...

Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

International Nuclear Information System (INIS)

Zhang, Haisu; Tzortzakis, Stelios

2016-01-01

We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

Energy Technology Data Exchange (ETDEWEB)

Zhang, Haisu [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Tzortzakis, Stelios, E-mail: stzortz@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, Heraklion 71110 (Greece); Materials Science and Technology Department, University of Crete, 71003 Heraklion (Greece); Science Program, Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar)

2016-05-23

We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

ELM Dynamics in TCV H-modes

Science.gov (United States)

Degeling, A. W.; Martin, Y. R.; Lister, J. B.; Llobet, X.; Bak, P. E.

2003-06-01

TCV (Tokamak à Configuration Variable, R = 0.88 m, a limited and diverted plasmas, with the primary aim of investigating the effects of plasma shape and current profile on tokamak physics and performance. L-mode to H-mode transitions are regularly obtained in TCV over a wide range of configurations. Under most conditions, the H-mode is ELM-free and terminates in a high density disruption. The conditions required for a transition to an ELMy H-mode were investigated in detail, and a reliable gateway in parameter space for the transition was identified. Once established, the ELMy H-mode is robust to changes in plasma current, elongation, divertor geometry and plasma density over ranges that are much wider than the size of the gateway in these parameters. There exists marked irregularity in the time interval between consecutive ELMs. Transient signatures in the time-series revealing the existence of an underlying chaotic dynamical system are repeatedly observed in a sizable group of discharges [1]. The properties of these signatures (called unstable periodic orbits, or UPOs) are found to vary systematically with parameters such as the plasma current, density and inner plasma — wall gap. A link has also been established between the dynamics of ELMs and sawteeth in TCV: under certain conditions a clear preference is observed in the phase between ELMs and sawtooth crashes, and the ratio of the ELM frequency (felm) to sawtooth frequency (fst) is found to prefer simple rational values (e.g. 1/1, 2/1 or 1/2). An attempt to control the ELM dynamics was made by applying a perturbation signal to the radial field coils used for vertical stabilisation. Phase synchronisation was found with the external perturbation, and felm was found to track limited scans in the driver frequency about the unperturbed value, albeit with intermittent losses in phase lock.

QUANTITATIVE TESTS OF ELMs AS INTERMEDIATE n PEELING-BALOONING MODES

International Nuclear Information System (INIS)

LAO, LL; SNYDER, PB; LEONARD, AW; OIKAWA, T; OSBORNE, TH; PETRIE, TW; FERRON, JR; GROEBNER, RJ; HORTON, LD; KAMADA, Y; MURAKAMI, M; SAARELMA, S; STJOHN, HE; TURNBULL, AD; WILSON, HR

2003-01-01

A271 QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALOONING MODES. Several testable features of the working model of edge localized modes (ELMs) as intermediate toroidal mode number peeling-ballooning modes are evaluated quantitatively using DIII-D and JT-60U experimental data and the ELITE MHD stability code. These include the hypothesis that ELM sizes are related to the radial widths of the unstable MHD modes, the unstable modes have a strong ballooning character localized in the outboard bad curvature region, and ELM size generally becomes smaller at high edge collisionality. ELMs are triggered when the growth rates of the unstable MHD modes become significantly large. These testable features are consistent with many ELM observations in DIII-D and JT-60U discharges

Establishment and characterization of American elm cell suspension cultures

Science.gov (United States)

Steven M. Eshita; Joseph C. Kamalay; Vicki M. Gingas; Daniel A. Yaussy

2000-01-01

Cell suspension cultures of Dutch elm disease (DED)-tolerant and DED-susceptible American elms clones have been established and characterized as prerequisites for contrasts of cellular responses to pathogen-derived elicitors. Characteristics of cultured elm cell growth were monitored by A700 and media conductivity. Combined cell growth data for all experiments within a...

Distinguishing deterministic and noise components in ELM time series

International Nuclear Information System (INIS)

Zvejnieks, G.; Kuzovkov, V.N

2004-01-01

Full text: One of the main problems in the preliminary data analysis is distinguishing the deterministic and noise components in the experimental signals. For example, in plasma physics the question arises analyzing edge localized modes (ELMs): is observed ELM behavior governed by a complicate deterministic chaos or just by random processes. We have developed methodology based on financial engineering principles, which allows us to distinguish deterministic and noise components. We extended the linear auto regression method (AR) by including the non-linearity (NAR method). As a starting point we have chosen the nonlinearity in the polynomial form, however, the NAR method can be extended to any other type of non-linear functions. The best polynomial model describing the experimental ELM time series was selected using Bayesian Information Criterion (BIC). With this method we have analyzed type I ELM behavior in a subset of ASDEX Upgrade shots. Obtained results indicate that a linear AR model can describe the ELM behavior. In turn, it means that type I ELM behavior is of a relaxation or random type

MHD stability analysis of ELMs in MAST

International Nuclear Information System (INIS)

Saarelma, S; Hender, T C; Kirk, A; Meyer, H; Wilson, H R; Team, MAST

2007-01-01

In this paper, edge stability analyses of the MAST tokamak plasmas are presented. The analyses show that the experimental equilibrium prior to an edge localized mode (ELM) is unstable against very narrow peeling modes with low growth rate. When the edge pressure gradient becomes steeper, wider peeling-ballooning modes with larger growth rate become unstable. These modes are the likely triggers of ELMs. In the analyses the required pressure increase for destabilization is sensitive to how the X-point is modelled in the equilibrium reconstruction. A 'sharp' X-point approximation is more stable against the peeling-ballooning modes than a 'round' one. An experimental ELM-free single null plasma is significantly more stable against the peeling-ballooning modes than the double null plasma, but this is unlikely to be directly due to the single null geometry but rather due to the different plasma profiles. Sheared toroidal rotation is able to stabilize the peeling-ballooning modes. This suggests the following model for the ELM triggering: the rotation shear keeps the edge stable until the pressure gradient has sufficiently exceeded the stability boundary for the static plasma. When the mode becomes unstable, it starts to grow, ties the flux surfaces together and flattens the rotation profile. This further destabilizes the edge plasma leading to an ELM crash

Peeling mode relaxation ELM model

International Nuclear Information System (INIS)

Gimblett, C. G.

2006-01-01

This paper discusses an approach to modelling Edge Localised Modes (ELMs) in which toroidal peeling modes are envisaged to initiate a constrained relaxation of the tokamak outer region plasma. Relaxation produces both a flattened edge current profile (which tends to further destabilise a peeling mode), and a plasma-vacuum negative current sheet which has a counteracting stabilising influence; the balance that is struck between these two effects determines the radial extent (rE) of the ELM relaxed region. The model is sensitive to the precise position of the mode rational surfaces to the plasma surface and hence there is a 'deterministic scatter' in the results that has an accord with experimental data. The toroidal peeling stability criterion involves the edge pressure, and using this in conjunction with predictions of rE allows us to evaluate the ELM energy losses and compare with experiment. Predictions of trends with the edge safety factor and collisionality are also made

ELM: an Algorithm to Estimate the Alpha Abundance from Low-resolution Spectra

Science.gov (United States)

Bu, Yude; Zhao, Gang; Pan, Jingchang; Bharat Kumar, Yerra

2016-01-01

We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.

ELM: AN ALGORITHM TO ESTIMATE THE ALPHA ABUNDANCE FROM LOW-RESOLUTION SPECTRA

International Nuclear Information System (INIS)

Bu, Yude; Zhao, Gang; Kumar, Yerra Bharat; Pan, Jingchang

2016-01-01

We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods

ELM: AN ALGORITHM TO ESTIMATE THE ALPHA ABUNDANCE FROM LOW-RESOLUTION SPECTRA

Energy Technology Data Exchange (ETDEWEB)

Bu, Yude [School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong (China); Zhao, Gang; Kumar, Yerra Bharat [Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Pan, Jingchang, E-mail: ydbu@bao.ac.cn, E-mail: gzhao@nao.cas.cn [School of Mechanical, Electrical and Information Engineering, Shandong University, Weihai, 264209, Shandong (China)

2016-01-20

We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.

A two-dimensional statistical framework connecting thermodynamic profiles with filaments in the scrape off layer and application to experiments

Science.gov (United States)

Militello, F.; Farley, T.; Mukhi, K.; Walkden, N.; Omotani, J. T.

2018-05-01

A statistical framework was introduced in Militello and Omotani [Nucl. Fusion 56, 104004 (2016)] to correlate the dynamics and statistics of L-mode and inter-ELM plasma filaments with the radial profiles of thermodynamic quantities they generate in the Scrape Off Layer. This paper extends the framework to cases in which the filaments are emitted from the separatrix at different toroidal positions and with a finite toroidal velocity. It is found that the toroidal velocity does not affect the profiles, while the toroidal distribution of filament emission renormalises the waiting time between two events. Experimental data collected by visual camera imaging are used to evaluate the statistics of the fluctuations, to inform the choice of the probability distribution functions used in the application of the framework. It is found that the toroidal separation of the filaments is exponentially distributed, thus suggesting the lack of a toroidal modal structure. Finally, using these measurements, the framework is applied to an experimental case and good agreement is found.

A review of models for ELMs

International Nuclear Information System (INIS)

Connor, J.W.

1997-04-01

The improved confinement regime known as the H-mode is often perturbed by the onset of a quasi-periodic series of relaxation oscillations involving bursts of MHD activity and D α emission known as edge localised modes (ELMs). The result in rapid losses of particles and energy from the region near the plasma boundary, reducing the average global energy confinement by 10-20%. Furthermore these transient burst of energy and particles into the scrape-off layer produce high peak heat loads on the divertor plates which must be accommodated by the divertor design. However, the ELMs are efficient, and beneficial, in removing density and impurities. Thus they are deemed necessary for the stationary operation of ITER, preventing the build up of density, impurities and helium ash. It is therefore desirable to be able to control the level and nature of the ELM activity in order to meet these various conflicting conditions; this would be aided by understanding their cause. After describing the phenomenology of ELMs, various theoretical models that have been proposed to explain them are discussed. These fall into three broad classes. Since ELMs are accompanied by bursts of magnetic activity, the first class of models involves the excitation of various MHD instabilities: ideal and resistive ballooning modes, external kink modes and so-called 'peeling modes'. Such models envisage the application of auxiliary heating driving the equilibrium to a state which triggers some such instability, resulting in the loss of plasma, followed by a recovery stage until the cycle is repeated; thus this description of the ELM cycle is merely conceptual. The second class of models involves limit cycle solutions of the transport equations governing the plasma edge region, exploiting the bifurcations inherent in theories of the L-H transition, eg those involving sheared rotation stabilisation. In the third class elements of both types of theory have been combined, with MHD or pressure driven

ELM Dynamics in TCV H-modes

International Nuclear Information System (INIS)

Degeling, A.W.; Martin, Y.R.; Lister, J.B.; Llobet, X.; Bak, P.E.

2003-01-01

TCV (Tokamak a Configuration Variable, R = 0.88 m, a < 0.25 m, BT < 1.54 T) is a highly elongated tokamak, capable of producing limited and diverted plasmas, with the primary aim of investigating the effects of plasma shape and current profile on tokamak physics and performance. L-mode to H-mode transitions are regularly obtained in TCV over a wide range of configurations. Under most conditions, the H-mode is ELM-free and terminates in a high density disruption. The conditions required for a transition to an ELMy H-mode were investigated in detail, and a reliable gateway in parameter space for the transition was identified. Once established, the ELMy H-mode is robust to changes in plasma current, elongation, divertor geometry and plasma density over ranges that are much wider than the size of the gateway in these parameters. There exists marked irregularity in the time interval between consecutive ELMs. Transient signatures in the time-series revealing the existence of an underlying chaotic dynamical system are repeatedly observed in a sizable group of discharges [1]. The properties of these signatures (called unstable periodic orbits, or UPOs) are found to vary systematically with parameters such as the plasma current, density and inner plasma -- wall gap. A link has also been established between the dynamics of ELMs and sawteeth in TCV: under certain conditions a clear preference is observed in the phase between ELMs and sawtooth crashes, and the ratio of the ELM frequency (felm) to sawtooth frequency (fst) is found to prefer simple rational values (e.g. 1/1, 2/1 or 1/2). An attempt to control the ELM dynamics was made by applying a perturbation signal to the radial field coils used for vertical stabilisation. Phase synchronisation was found with the external perturbation, and felm was found to track limited scans in the driver frequency about the unperturbed value, albeit with intermittent losses in phase lock

Simulation of tungsten armour cracking due to small ELMs in ITER

International Nuclear Information System (INIS)

Pestchanyi, S.; Garkusha, I.; Landman, I.

2010-01-01

Simulations of tungsten armour cracking under small ELM-like plasma heat load, which does not cause surface melting, have been performed using the PEGASUS-3D code. A dedicated series of experiments have been performed in the QSPA-Kh50 facility for measurements of the unknown tungsten thermophysical properties and for verification of the PEGASUS-3D simulation results. The simulations revealed that a cellular crack network with average mesh size Λ ∼ 0.5 mm formed after first ELMs and the pattern does not change further. With increasing number of repetitive ELMs loads, the average crack width Δ(n) has a maximum value Δ m . The ratio of Δ m /Λ is equal to the tungsten thermal expansion at the maximum surface temperature. Δ(n) tends to this value exponentially. The number of ELMs n m needed for Δ stabilization depends on the ELMs energy density and time duration, n m ∼ 300 for the simulated ELMs of 0.45 MJ/m 2 and 0.25 ms duration. The PEGASUS-3D code is prepared for simulations of tungsten armour damage under action of ELMs of various energy deposition and time duration. These parameters of ELMs depend on ITER regimes of operation and on how successful will be the efforts on ELMs mitigation.

DNA Double-Strand Breaks Induce the Nuclear Actin Filaments Formation in Cumulus-Enclosed Oocytes but Not in Denuded Oocytes.

Directory of Open Access Journals (Sweden)

Ming-Hong Sun

Full Text Available As a gamete, oocyte needs to maintain its genomic integrity and passes this haploid genome to the next generation. However, fully-grown mouse oocyte cannot respond to DNA double-strand breaks (DSBs effectively and it is also unable to repair them before the meiosis resumption. To compensate for this disadvantage and control the DNA repair events, oocyte needs the cooperation with its surrounding cumulus cells. Recently, evidences have shown that nuclear actin filament formation plays roles in cellular DNA DSB repair. To explore whether these nuclear actin filaments are formed in the DNA-damaged oocytes, here, we labeled the filament actins in denuded oocytes (DOs and cumulus-enclosed oocytes (CEOs. We observed that the nuclear actin filaments were formed only in the DNA-damaged CEOs, but not in DOs. Formation of actin filaments in the nucleus was an event downstream to the DNA damage response. Our data also showed that the removal of cumulus cells led to a reduction in the nuclear actin filaments in oocytes. Knocking down of the Adcy1 gene in cumulus cells did not affect the formation of nuclear actin filaments in oocytes. Notably, we also observed that the nuclear actin filaments in CEOs could be induced by inhibition of gap junctions. From our results, it was confirmed that DNA DSBs induce the nuclear actin filament formation in oocyte and which is controlled by the cumulus cells.

Simulation of tungsten armour cracking due to small ELMs in ITER

Energy Technology Data Exchange (ETDEWEB)

Pestchanyi, S., E-mail: sergey.pestchanyi@ihm.fzk.de [Forschungszentrum Karlsruhe, IHM (Germany); Garkusha, I. [Institute of Plasma Physics of the NSC KIPT, Kharkov 61108 (Ukraine); Landman, I. [Forschungszentrum Karlsruhe, IHM (Germany)

2010-12-15

Simulations of tungsten armour cracking under small ELM-like plasma heat load, which does not cause surface melting, have been performed using the PEGASUS-3D code. A dedicated series of experiments have been performed in the QSPA-Kh50 facility for measurements of the unknown tungsten thermophysical properties and for verification of the PEGASUS-3D simulation results. The simulations revealed that a cellular crack network with average mesh size {Lambda} {approx} 0.5 mm formed after first ELMs and the pattern does not change further. With increasing number of repetitive ELMs loads, the average crack width {Delta}(n) has a maximum value {Delta}{sub m}. The ratio of {Delta}{sub m}/{Lambda} is equal to the tungsten thermal expansion at the maximum surface temperature. {Delta}(n) tends to this value exponentially. The number of ELMs n{sub m} needed for {Delta} stabilization depends on the ELMs energy density and time duration, n{sub m} {approx} 300 for the simulated ELMs of 0.45 MJ/m{sup 2} and 0.25 ms duration. The PEGASUS-3D code is prepared for simulations of tungsten armour damage under action of ELMs of various energy deposition and time duration. These parameters of ELMs depend on ITER regimes of operation and on how successful will be the efforts on ELMs mitigation.

ELMs and the role of current-driven instabilities in the edge

International Nuclear Information System (INIS)

Snyder, P.B.; Wilson, H.R.

2001-01-01

Edge localized modes (ELMs) can limit tokamak performance both directly, via large transient heat loads, and indirectly, through constraints placed on the H-mode pedestal height which impact global confinement. Theoretical understanding of the physics of ELMs should allow optimisation of existing experiments, and lead to greater confidence in projections for Next Step devices. However, understanding ELMs has proved challenging, in part because the sharp edge pressure gradients and consequent large bootstrap currents in the pedestal region provide drive for a variety of modes over a wide range of toroidal mode numbers (n). Here we present a brief discussion of ELM phenomenology, focussing primarily on ELMs whose frequency increases with input power. Theories of ELMs will be reviewed, emphasizing those which incorporate current-driven instabilities such as kink or 'peeling' modes. Parallel current plays a dual role in the edge, enhancing second stability access for ballooning modes while providing drive for peeling modes. The strong collisionality dependence of the edge bootstrap current introduces separate density and temperature dependence into pedestal MHD stability. We give a detailed description of recent work on coupled peeling-ballooning modes, including a model for ELM characteristics and temperature pedestal limits. Peeling-ballooning stability analysis of experimental discharges will be discussed, emphasising comparisons of different ELM regimes, such as the comparison between 'giant' and 'grassy' ELM shots on JT-60U. (orig.)

Phospho.ELM: a database of phosphorylation sites--update 2011

DEFF Research Database (Denmark)

Dinkel, Holger; Chica, Claudia; Via, Allegra

2011-01-01

The Phospho.ELM resource (http://phospho.elm.eu.org) is a relational database designed to store in vivo and in vitro phosphorylation data extracted from the scientific literature and phosphoproteomic analyses. The resource has been actively developed for more than 7 years and currently comprises ...... sequence alignment used for the score calculation. Finally, special emphasis has been put on linking to external resources such as interaction networks and other databases.......The Phospho.ELM resource (http://phospho.elm.eu.org) is a relational database designed to store in vivo and in vitro phosphorylation data extracted from the scientific literature and phosphoproteomic analyses. The resource has been actively developed for more than 7 years and currently comprises 42...

Experimental and numerical simulations of ELM-like transient damage behaviors to different grade tungsten and tungsten alloys

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiang, E-mail: xliu@swip.ac.cn [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Lian, Youyun; Chen, Lei; Chen, Zhenkui; Chen, Jiming; Duan, Xuru [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Fan, Jinlian [Central South University, Changsha 410083 (China); Song, Jiupeng [Xiamen Honglu Tungsten & Molybdenum Industry Co., Ltd, Xiamen (China)

2015-08-15

Transient heat loads, such as plasma disruptions and ELMs, could induce plastic deformations, cracking, melting, even fatigue cracks and creep of tungsten (W) surface. A high purity W, CVD-W coating, TiC dispersion strengthened and K doped tungsten alloys were tested in a 60 kW electron-beam facility by simulating the transient load events under different base temperatures. It was found that CVD-W, W-TiC and W-K alloys have higher crack thresholds than high purity W, meanwhile CVD-W is more sensitive to the crack disappearing at elevated base temperatures. On the other hand, repetitive pulse loading like ELMs can induce serious network cracks even the power density was quite lower than the crack threshold determined by a single shot. The ABAQUS code was used to simulate the crack behaviors of ITER grade pure W by a single shot and a FE-SAFE code was adopted to estimate the fatigue life under ELMs-like loads. A good agreement with experiment results was found.

Gamma irradiating elm billets reduces their attractancy to the smaller elm bark beetle, Scolytus multistriatus (Marsham)

International Nuclear Information System (INIS)

French, J.R.J.; Robinson, P.J.

1982-01-01

Irradiating elm billets with gamma rays had a significant effect in reducing the attractancy of these billets to inflight adults of the smaller elm bark beetle Scolytus multistriatus (Marsham). The temperature at which the fresh billets were stored prior to the beetle exposure had little effect. Irradiated billets, irrespective of storage temperature, had significantly fewer holes than the freshly cut billets. There were significant differences associated with the location of the billets in the field, but these differences were smaller than those associated with irradiation. (orig.) [de

Inter-ELM pedestal structure development in ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Laggner, Florian Martin

2017-06-15

The performance of a magnetically confined, fusion plasma is strongly impacted by the plasma edge, which is the boundary between the hot, confined plasma and the reactor walls. In a tokamak, which uses a toroidally axis-symmetric magnetic field configuration, a regime of improved plasma confinement, the high confinement mode (H-mode), has been observed. The confinement improvement originates from an edge transport barrier (ETB), which is accompanied by steep gradients of the plasma pressure, named pedestal. The maximum sustainable pedestal, i.e. the maximum pressure gradient, is usually set by an ideal magnetohydrodynamic limit, which if exceeded is leading to edge localised modes (ELMs). ELMs are instabilities that relax the pedestal and lead to a loss of the order of 10% from the plasma stored energy. The mechanisms, which set the pedestal structure before an ELM crash, keeping the pedestal stable up to this point, are not fully understood. Here, microturbulent instabilities, e.g. kinetic ballooning modes (KBMs), are expected to play an important role. The presented PhD thesis investigates the temporal development of the pedestal density and temperature profiles in between ELM crashes at the ASDEX Upgrade tokamak. The aims were comparisons of different plasma conditions, i.e. plasma collisionality (ν{sup *}), main isotope species and plasma shapes. Further, the impact of the conditions outside the confined plasma on the pedestal development was investigated. The extensive study of these parameters resulted in one key observation: The pedestal recovers in distinct phases in between ELM crashes with always the same sequence. Immediately after the ELM crash, the electron density (n{sub e}) pedestal is established, followed by the electron temperature (T{sub e}) pedestal. Finally, a period with constant pressure gradient appears, which can vary in duration. For a large range of ν{sup *} it has been found that the onset of radial magnetic fluctuations with

Simultaneous induction of jasmonic acid and disease-responsive genes signifies tolerance of American elm to Dutch elm disease

Science.gov (United States)

Sherif , S. M.; Shukla, M. R.; Murch, S. J.; Bernier, L.; Saxena, P. K.

2016-01-01

Dutch elm disease (DED), caused by three fungal species in the genus Ophiostoma, is the most devastating disease of both native European and North American elm trees. Although many tolerant cultivars have been identified and released, the tolerance mechanisms are not well understood and true resistance has not yet been achieved. Here we show that the expression of disease-responsive genes in reactions leading to tolerance or susceptibility is significantly differentiated within the first 144 hours post-inoculation (hpi). Analysis of the levels of endogenous plant defense molecules such as jasmonic acid (JA) and salicylic acid (SA) in tolerant and susceptible American elm saplings suggested SA and methyl-jasmonate as potential defense response elicitors, which was further confirmed by field observations. However, the tolerant phenotype can be best characterized by a concurrent induction of JA and disease-responsive genes at 96 hpi. Molecular investigations indicated that the expression of fungal genes (i.e. cerato ulmin) was also modulated by endogenous SA and JA and this response was unique among aggressive and non-aggressive fungal strains. The present study not only provides better understanding of tolerance mechanisms to DED, but also represents a first, verified template for examining simultaneous transcriptomic changes during American elm-fungus interactions. PMID:26902398

ELM pace making and amelioration at ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Lang, P.T.; Gruber, O.; Haas, G.; Horton, L.D.; Kaufmann, M.; Mertens, V.; Neu, R.; Neuhauser, J.; Puetterich, T.; Schneider, W.; Sihler, C.; Sips, A.C.C.; Suttrop, W.; Treutterer, W. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Garching (Germany); Bucalossi, J. [Association Euratom-Confederation Suisse, CRPP-EPFL, Lausanne (Switzerland); Kalvin, S.; Kocsis, G. [Association Euratom, KFKI-RMKI, Budapest (Hungary); Mc Carthy, P.J. [University College Cork, Physics Dept., Association Euratom-DCu, Cork (Ireland)

2004-07-01

Different techniques were tried to trigger ELMs (edge localized mode): injection of cryogenic solid pellets or a super-sonic molecular gas jet composed of deuterium or magnetic triggering, relying on a fast motion of the plasma column in a spatially asymmetric flux configuration. Our investigations prove externally imposed control techniques can change the ELM frequency. Frequency enhancement can result in amelioration of the single ELMs. Moreover, the approach can maintain plasma operation at a high performance level. Both pellet injection and magnetic triggering have been shown their potential to act as useful control tools. This yields the option to choose eventually the most appropriate technique for a given scenario.

Femtosecond Laser Filamentation

CERN Document Server

Chin, See Leang

2010-01-01

Femtosecond Laser Filamentation gives a comprehensive review of the physics of propagation of intense femtosecond laser pulses in optical media (principally air) and the applications and challenges of this new technique. This book presents the modern understanding of the physics of femtosecond laser pulse propagation, including unusual new effects such as the self-transformation of the pulse into a white light laser pulse, intensity clamping, the physics of multiple filamentation and competition, and how filaments’ ability to melt glass leads to wave guide writing. The potential applications of laser filamentation in atmospheric sensing and the generation of other electromagnetic pulses from the UV to the radio frequency are treated, together with possible future challenges in the excitation of super-excited states of molecules. Exciting new phenomena such as filament induced ultrafast birefringence and the excitation of molecular rotational wave packets and their multiple revivals in air (gases) will also ...

The MHD stability analysis of type I ELMS in ASDEX Upgrade Tokamak

International Nuclear Information System (INIS)

Saarelma, S.

2000-01-01

The ELMs or edge localized modes are plasma instabilities localized in the edge region of a tokamak plasma. They cause periodic expulsions of particles and energy. The ELMs play a significant role in the confinement of the plasma, helium exhaust and diverter erosion. These are crucial issues in tokamak operation and, thus, understanding the underlying physical mechanism behind the ELM phenomenon is very important. The ELMs are classified into three different types based on the plasma conditions, where they are observed, and, on the ELM frequency response to the heating power. In this thesis, type I ELMs which are the most intense and the most damaging to the diverters, are studied. A model for the ELMs presented by Connor et al. is tested in experimental ASDEX Upgrade plasmas. In the Connor model, the ELMs are explained as a result of two instabilities, ballooning and peeling modes. Also a phenomenon called the bootstrap current plays a significant role by being the destabilising trigger to the peeling modes. The method used to study the model is MHD or magnetohydrodynamics. The theory of the ideal MHD equilibrium and the linear stability analysis is described. Inclusion of the bootstrap current to the equilibrium construction is introduced. The equilibria are created using experimental data from plasma shots that display type I ELMs. The stability analysis indicates that the investigated ELM model is a feasible explanation for type I ELMs. The pressure gradient near the plasma edge was found to be close to the ballooning stability boundary as predicted by the model. The peeling mode stability analysis confirms the prediction of the model that as the bootstrap current increases, the plasma becomes unstable for peeling modes with low to intermediate toroidal mode numbers. The mode numbers agree with the experimental results. In the experiments with high triangularity, low ELM frequency and ELM-free periods were observed. This indicates better stability of the plasma

Probability distribution functions for ELM bursts in a series of JET tokamak discharges

International Nuclear Information System (INIS)

Greenhough, J; Chapman, S C; Dendy, R O; Ward, D J

2003-01-01

A novel statistical treatment of the full raw edge localized mode (ELM) signal from a series of previously studied JET plasmas is tested. The approach involves constructing probability distribution functions (PDFs) for ELM amplitudes and time separations, and quantifying the fit between the measured PDFs and model distributions (Gaussian, inverse exponential) and Poisson processes. Uncertainties inherent in the discreteness of the raw signal require the application of statistically rigorous techniques to distinguish ELM data points from background, and to extrapolate peak amplitudes. The accuracy of PDF construction is further constrained by the relatively small number of ELM bursts (several hundred) in each sample. In consequence the statistical technique is found to be difficult to apply to low frequency (typically Type I) ELMs, so the focus is narrowed to four JET plasmas with high frequency (typically Type III) ELMs. The results suggest that there may be several fundamentally different kinds of Type III ELMing process at work. It is concluded that this novel statistical treatment can be made to work, may have wider applications to ELM data, and has immediate practical value as an additional quantitative discriminant between classes of ELMing behaviour

Myosin binding protein-C activates thin filaments and inhibits thick filaments in heart muscle cells.

Science.gov (United States)

Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm

2014-12-30

Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) filaments in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin filaments and on myosin regulatory light chain in the thick filaments to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin filaments than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin filaments. In contrast, structural changes in thick filaments induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick filaments. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin filaments and the OFF state of thick filaments and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility.

Structure, stability and ELM dynamics of the H-mode pedestal in DIII-D

International Nuclear Information System (INIS)

Fenstermacher, M.E.; Leonard, A.W.; Osborne, T.H.

2005-01-01

Experiments are described that have increased understanding of the transport and stability physics that set the H-mode edge pedestal width and height, determine the onset of Type-I edge localized modes (ELMs), and produce the nonlinear dynamics of the ELM perturbation in the pedestal and scrape-off layer (SOL). Predictive models now exist for the n e pedestal profile and the p e height at the onset of Type-I ELMs, and progress has been made toward predictive models of the T e pedestal width and nonlinear ELM evolution. Similarity experiments between DIII-D and JET suggested that neutral penetration physics dominates in the relationship between the width and height of the n e pedestal while plasma physics dominates in setting the T e pedestal width. Measured pedestal conditions including edge current at ELM onset agree with intermediate-n peeling-ballooning (P-B) stability predictions. Midplane ELM dynamics data show the predicted (P-B) structure at ELM onset, large rapid variations of the SOL parameters, and fast radial propagation in later phases, similar to features in nonlinear ELM simulations. (author)

Analytical Core Mass Function (CMF) from Filaments: Under Which Circumstances Can Filament Fragmentation Reproduce the CMF?

Energy Technology Data Exchange (ETDEWEB)

Lee, Yueh-Ning; Hennebelle, Patrick [IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette (France); Chabrier, Gilles, E-mail: yueh-ning.lee@cea.fr [École normale supérieure de Lyon, CRAL, UMR CNRS 5574, Université de Lyon, F-69364 Lyon Cedex 07 (France)

2017-10-01

Observations suggest that star formation in filamentary molecular clouds occurs in a two-step process, with the formation of filaments preceding that of prestellar cores and stars. Here, we apply the gravoturbulent fragmentation theory of Hennebelle and Chabrier to a filamentary environment, taking into account magnetic support. We discuss the induced geometrical effect on the cores, with a transition from 3D geometry at small scales to 1D at large ones. The model predicts the fragmentation behavior of a filament for a given mass per unit length (MpL) and level of magnetization. This core mass function (CMF) for individual filaments is then convolved with the distribution of filaments to obtain the final system CMF. The model yields two major results. (i) The filamentary geometry naturally induces a hierarchical fragmentation process, first into groups of cores, separated by a length equal to a few filament Jeans lengths, i.e., a few times the filament width. These groups then fragment into individual cores. (ii) Non-magnetized filaments with high MpL are found to fragment excessively, at odds with observations. This is resolved by taking into account the magnetic field (treated simply as additional pressure support). The present theory suggests two complementary modes of star formation: although small (spherical or filamentary) structures will collapse directly into prestellar cores, according to the standard Hennebelle–Chabrier theory, the large (filamentary) ones, the dominant population according to observations, will follow the aforedescribed two-step process.

American Elm clones of importance in DED tolerance studies

Science.gov (United States)

We present the background and characteristics of American elm clones that are commercially available or of interest in research on Dutch elm disease (DED) tolerance in the United States. The characteristics of interest include origin, ploidy level, whether available in nursery trade, evidence of DED...

THE ELM SURVEY. III. A SUCCESSFUL TARGETED SURVEY FOR EXTREMELY LOW MASS WHITE DWARFS

International Nuclear Information System (INIS)

Brown, Warren R.; Kenyon, Scott J.; Kilic, Mukremin; Allende Prieto, Carlos

2012-01-01

Extremely low mass (ELM) white dwarfs (WDs) with masses ☉ are rare objects that result from compact binary evolution. Here, we present a targeted spectroscopic survey of ELM WD candidates selected by color. The survey is 71% complete and has uncovered 18 new ELM WDs. Of the seven ELM WDs with follow-up observations, six are short-period binaries and four have merger times less than 5 Gyr. The most intriguing object, J1741+6526, likely has either a pulsar companion or a massive WD companion making the system a possible supernova Type Ia or an Ia progenitor. The overall ELM survey has now identified 19 double degenerate binaries with <10 Gyr merger times. The significant absence of short orbital period ELM WDs at cool temperatures suggests that common envelope evolution creates ELM WDs directly in short period systems. At least one-third of the merging systems are halo objects, thus ELM WD binaries continue to form and merge in both the disk and the halo.

PDGF-AA-induced filamentous mitochondria benefit dermal papilla cells in cellular migration.

Science.gov (United States)

Mifude, C; Kaseda, K

2015-06-01

Human dermal papilla cells (HDPCs) play essential roles in hair follicular morphogenesis and postnatal hair growth cycles. Previous reports demonstrated that platelet-derived growth factor-AA (PDGF-AA) enhanced the formation of dermal condensates in hair follicular development. Additionally, PDGF-AA induces/maintains the anagen phase of the hair cycle. It is likely that mitochondrial morphology and functions are tightly coupled with maintenance of these energy-demanding activities. However, little is known about the mitochondrial regulation in HDPCs. Thus, we investigated the PDGF-involved mitochondrial regulation in HDPCs. The mitochondrial morphologies of HDPCs were examined in the presence or absence of PDGF-AA under a fluorescent microscope. ATP production and cellular motility were investigated. The relationship between mitochondrial morphology and the cellular functions was discussed. We observed that primary HDPCs contained mitochondria with filamentous and/or rounded morphologies. Both types of mitochondria showed similar membrane potentials. Interestingly, in the presence of PDGF-AA, but not PDGF-BB, the balance between the two morphologies shifted towards the filamentous form. Concomitantly, both mitochondrial enzymatic activity and total cellular ATP level were augmented by PDGF-AA. These two parameters were closely correlated, suggesting the mitochondrial involvement in the PDGF-augmented ATP production. Moreover, PDGF-AA accelerated the migration of HDPCs in a gap-filling assay, but did not change the rate of cellular proliferation. Notably, filamentous mitochondria dominated migrating HDPCs. PDGF-AA benefits HDPCs in the process of migration, by increasing the number of filamentous mitochondria. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Menyoal Elaboration Likelihood Model (ELM dan Teori Retorika

Directory of Open Access Journals (Sweden)

Yudi Perbawaningsih

2012-06-01

Full Text Available Abstract: Persuasion is a communication process to establish or change attitudes, which can be understood through theory of Rhetoric and theory of Elaboration Likelihood Model (ELM. This study elaborates these theories in a Public Lecture series which to persuade the students in choosing their concentration of study. The result shows that in term of persuasion effectiveness it is not quite relevant to separate the message and its source. The quality of source is determined by the quality of the message, and vice versa. Separating the two routes of the persuasion process as described in the ELM theory would not be relevant. Abstrak: Persuasi adalah proses komunikasi untuk membentuk atau mengubah sikap, yang dapat dipahami dengan teori Retorika dan teori Elaboration Likelihood Model (ELM. Penelitian ini mengelaborasi teori tersebut dalam Kuliah Umum sebagai sarana mempersuasi mahasiswa untuk memilih konsentrasi studi studi yang didasarkan pada proses pengolahan informasi. Menggunakan metode survey, didapatkan hasil yaitu tidaklah cukup relevan memisahkan pesan dan narasumber dalam melihat efektivitas persuasi. Keduanya menyatu yang berarti bahwa kualitas narasumber ditentukan oleh kualitas pesan yang disampaikannya, dan sebaliknya. Memisahkan proses persuasi dalam dua lajur seperti yang dijelaskan dalam ELM teori menjadi tidak relevan.

Interplay between Solo and keratin filaments is crucial for mechanical force–induced stress fiber reinforcement

Science.gov (United States)

Fujiwara, Sachiko; Ohashi, Kazumasa; Mashiko, Toshiya; Kondo, Hiroshi; Mizuno, Kensaku

2016-01-01

Mechanical force–induced cytoskeletal reorganization is essential for cell and tissue remodeling and homeostasis; however, the underlying cellular mechanisms remain elusive. Solo (ARHGEF40) is a RhoA-targeting guanine nucleotide exchange factor (GEF) involved in cyclical stretch–induced human endothelial cell reorientation and convergent extension cell movement in zebrafish gastrula. In this study, we show that Solo binds to keratin-8/keratin-18 (K8/K18) intermediate filaments through multiple sites. Solo overexpression promotes the formation of thick actin stress fibers and keratin bundles, whereas knockdown of Solo, expression of a GEF-inactive mutant of Solo, or inhibition of ROCK suppresses stress fiber formation and leads to disorganized keratin networks, indicating that the Solo-RhoA-ROCK pathway serves to precisely organize keratin networks, as well as to promote stress fibers. Of importance, knockdown of Solo or K18 or overexpression of GEF-inactive or deletion mutants of Solo suppresses tensile force–induced stress fiber reinforcement. Furthermore, knockdown of Solo or K18 suppresses tensile force-induced RhoA activation. These results strongly suggest that the interplay between Solo and K8/K18 filaments plays a crucial role in tensile force–induced RhoA activation and consequent actin cytoskeletal reinforcement. PMID:26823019

THE ELM SURVEY. III. A SUCCESSFUL TARGETED SURVEY FOR EXTREMELY LOW MASS WHITE DWARFS

Energy Technology Data Exchange (ETDEWEB)

Brown, Warren R.; Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States); Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States); Allende Prieto, Carlos, E-mail: wbrown@cfa.harvard.edu, E-mail: skenyon@cfa.harvard.edu, E-mail: kilic@ou.edu, E-mail: callende@iac.es [Instituto de Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)

2012-01-10

Extremely low mass (ELM) white dwarfs (WDs) with masses < 0.25 M{sub Sun} are rare objects that result from compact binary evolution. Here, we present a targeted spectroscopic survey of ELM WD candidates selected by color. The survey is 71% complete and has uncovered 18 new ELM WDs. Of the seven ELM WDs with follow-up observations, six are short-period binaries and four have merger times less than 5 Gyr. The most intriguing object, J1741+6526, likely has either a pulsar companion or a massive WD companion making the system a possible supernova Type Ia or an Ia progenitor. The overall ELM survey has now identified 19 double degenerate binaries with <10 Gyr merger times. The significant absence of short orbital period ELM WDs at cool temperatures suggests that common envelope evolution creates ELM WDs directly in short period systems. At least one-third of the merging systems are halo objects, thus ELM WD binaries continue to form and merge in both the disk and the halo.

An Improved Iris Recognition Algorithm Based on Hybrid Feature and ELM

Science.gov (United States)

Wang, Juan

2018-03-01

The iris image is easily polluted by noise and uneven light. This paper proposed an improved extreme learning machine (ELM) based iris recognition algorithm with hybrid feature. 2D-Gabor filters and GLCM is employed to generate a multi-granularity hybrid feature vector. 2D-Gabor filter and GLCM feature work for capturing low-intermediate frequency and high frequency texture information, respectively. Finally, we utilize extreme learning machine for iris recognition. Experimental results reveal our proposed ELM based multi-granularity iris recognition algorithm (ELM-MGIR) has higher accuracy of 99.86%, and lower EER of 0.12% under the premise of real-time performance. The proposed ELM-MGIR algorithm outperforms other mainstream iris recognition algorithms.

Discriminant analysis to predict the occurrence of ELMs in H-mode discharges

International Nuclear Information System (INIS)

Kardaun, O.J.W.F.; Itoh, S.; Itoh, K.; Kardaun, J.W.P.F.

1993-08-01

After an exposition of its theoretical background, discriminant analysis is applied to the H-mode confinement database to find the region in plasma parameter space in which H-mode with small ELMs (Edge Localized Modes) is likely to occur. The boundary of this region is determined by the condition that the probability of appearance of such a type of H-mode, as a function of the plasma parameters, should be (1) larger than some threshold value and (2) larger than the corresponding probability for other types of H-mode (i.e., H-mode without ELMs or with giant ELMs). In practice, the discrimination has been performed for the ASDEX, JET and JFT-2M tokamaks (a) using four instantaneous plasma parameters (injected power P inj , magnetic field B t , plasma current I p and line averaged electron density (n-bar e ) and (b) taking also memory effects of the plasma and the distance between the plasma and the wall into account, while using variables that are normalised with respect to machine size. Generally speaking, it is found that there is a substantial overlap between the region of H-mode with small ELMs and the region of the two other types of H-mode. However, the ELM-free and the giant ELM H-modes relatively rarely appear in the region, that, according to the analysis, is allocated to small ELMs. A reliable production of H-mode with only small ELMs seems well possible by choosing this regime in parameter space. In the present study, it was not attempted to arrive at a unified discrimination across the machines. So, projection from one machine to another remains difficult, and a reliable determination of the region where small ELMs occur still requires a training sample from the device under consideration. (author) 53 refs

Dynamics and mechanics of motor-filament systems

Science.gov (United States)

Kruse, K.; Jülicher, F.

2006-08-01

Motivated by the cytoskeleton of eukaryotic cells, we develop a general framework for describing the large-scale dynamics of an active filament network. In the cytoskeleton, active cross-links are formed by motor proteins that are able to induce relative motion between filaments. Starting from pair-wise interactions of filaments via such active processes, our framework is based on momentum conservation and an analysis of the momentum flux. This allows us to calculate the stresses in the filament network generated by the action of motor proteins. We derive effective theories for the filament dynamics which can be related to continuum theories of active polar gels. As an example, we discuss the stability of homogenous isotropic filament distributions in two spatial dimensions.

Far-reaching Impact of Intermittent Transport across the Scrape-off Layer: Latest Results from ASDEX Upgrade

Energy Technology Data Exchange (ETDEWEB)

Kocan, M.; Muller, W.; Conway, G.; De Marne, P.; Eich, T.; Fischer, R.; Fuchs, C.; Herrmann, A.; Ionita, C.; Kallenbach, A.; Lunt, T.; Maraschek, M.; Muller, S.; Nold, B.; Ribeiro, T.; Rohde, V.; Scott, B.; Stroth, U.; Suttrop, W.; Wolfrum, E., E-mail: martin.kocan@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Adamek, J.; Horacek, J.; Komm, M. [Association EURATOM-IPP CR, Prague (Czech Republic); Gennrich, F.; Maszl, C.; Mehlmann, F.; Schrittwieser, R. [Institute for Ion Physics and Applied Physics, Association Euratom-OAW (Austria); Huang, Z. [Institut fuer Plasmaforschung, Universitat Stuttgart, Stuttgart (Germany)

2012-09-15

Full text: Latest research of intermittent transport in the scrape-off layer (SOL) of the ASDEX Upgrade tokamak is presented. Near the separatrix the fluctuations of the plasma and the floating potentials, measured by various Langmuir probes (LPs), are found to be anti-correlated due to fluctuations of the electron temperature. This indicates that, in contrast to a widely used experimental practice, a free exchange of both potentials is unjustified and can lead to significant error. Measurements of ion energies in turbulent L-mode and ELM filaments were carried out using a retarding field analyzer. In L-mode plasma, the filament ion temperature measured at 2 cm outside the separatrix is 80 - 110 eV, i.e., 3 - 4x the background ion temperature. Turbulent filaments also convect plasma to the wall with larger density than the background plasma density. Qualitatively similar observations were obtained during inter-ELM periods. Such enhanced particle and energy fluxes can potentially raise the erosion of the first wall in ITER. The ion temperature averaged over an ELM measured 35 - 60 mm outside the separatrix is in the range of 20 - 200 eV (5 - 50% of the pedestal top ion temperature). This demonstrates that ELM filaments carry hot ions over large radial distances in the SOL, which, in turn, can lead to enhanced sputtering from the first wall in future tokamaks. Lowest ion energies are observed during ELMs mitigated by in-vessel magnetic perturbations (MPs). The ELM ion temperature in the far SOL is found to increase with the ELM energy, indicating that on average the filaments in large ELMs propagate faster radially. The filamentary structure of the ion current density measured by LPs at the outboard mid-plane during mitigated ELMs is qualitatively similar to that observed during type I ELMs. The amplitude of the ion current density decreases only slightly when ELMs are mitigated, but, in contrast to type I ELMs, bursts of the ion current are observed throughout the

Divertor load footprint of ELMs in pellet triggering and pacing experiments at JET

Energy Technology Data Exchange (ETDEWEB)

Frigione, D., E-mail: domenico.frigione@frascati.enea.it [Unità Tecnica Fusione, ENEA C.R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Garzotti, L. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom); Lennholm, M. [EFDA CSU, Culham Science Centre, OX14 3DB (United Kingdom); Alper, B. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom); Artaserse, G. [Unità Tecnica Fusione, ENEA C.R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Bennett, P. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom); Giovannozzi, E. [Unità Tecnica Fusione, ENEA C.R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Eich, T. [Max Planck Institute for Plasma Physics, Garching (Germany); Kocsis, G. [WIGNER RCP RMI, POB 49, 1525 Budapest (Hungary); Lang, P.T. [Max Planck Institute for Plasma Physics, Garching (Germany); Maddaluno, G. [Unità Tecnica Fusione, ENEA C.R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Mooney, R. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom); Rack, M. [Institut für Energieforschung – Plasmaphysik, Forschungszentrum Jülich, 52425 Jülich (Germany); Sips, G. [EFDA CSU, Culham Science Centre, OX14 3DB (United Kingdom); Tvalashvili, G. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom); Viola, B. [Unità Tecnica Fusione, ENEA C.R. Frascati, via E. Fermi 45, 00044 Frascati (Roma) (Italy); Wilkes, D. [CCFE, Culham Science Centre, OX14 3DB (United Kingdom)

2015-08-15

An investigation of pellet pacing and triggering of Edge Localized Modes (ELMs) was carried out in the frame of ELM mitigation studies aimed at reducing their damaging effects on the plasma-facing components (PFCs). The divertor power load footprint of triggered ELMs was compared with gas puffing controlled ELMs. Small pellets, corresponding to a few per cent of the target plasma particle inventory, were used to minimize the fueling effect and the total particle throughput. There is no evidence that pellets can reduce the divertor power load with respect to gas fueling when operating at the same ELM frequency. The line average density and the energy confinement time remained constant when the gas was progressively substituted by pellets. The launch from the Vertical High Field Side (VHFS) confirmed to be more efficient in ELM triggering than from the Low Field Side (LFS) while the power load footprint remained the same both in time evolution and in spatial distribution when changing the injection geometry.

Surface EMG signals based motion intent recognition using multi-layer ELM

Science.gov (United States)

Wang, Jianhui; Qi, Lin; Wang, Xiao

2017-11-01

The upper-limb rehabilitation robot is regard as a useful tool to help patients with hemiplegic to do repetitive exercise. The surface electromyography (sEMG) contains motion information as the electric signals are generated and related to nerve-muscle motion. These sEMG signals, representing human's intentions of active motions, are introduced into the rehabilitation robot system to recognize upper-limb movements. Traditionally, the feature extraction is an indispensable part of drawing significant information from original signals, which is a tedious task requiring rich and related experience. This paper employs a deep learning scheme to extract the internal features of the sEMG signals using an advanced Extreme Learning Machine based auto-encoder (ELMAE). The mathematical information contained in the multi-layer structure of the ELM-AE is used as the high-level representation of the internal features of the sEMG signals, and thus a simple ELM can post-process the extracted features, formulating the entire multi-layer ELM (ML-ELM) algorithm. The method is employed for the sEMG based neural intentions recognition afterwards. The case studies show the adopted deep learning algorithm (ELM-AE) is capable of yielding higher classification accuracy compared to the Principle Component Analysis (PCA) scheme in 5 different types of upper-limb motions. This indicates the effectiveness and the learning capability of the ML-ELM in such motion intent recognition applications.

ELM triggering conditions for the integrated modeling of H-mode plasmas

International Nuclear Information System (INIS)

Pankin, A.Y.; Schnack, D.D.; Bateman, G.; Kritz, A.H.; Brennan, D.P.; Snyder, P.B.; Voitsekhovitch, I.; Kruger, S.; Janeschitz, G.; Onjun, T.; Pacher, G.W.; Pacher, H.D.

2005-01-01

Recent advances in the integrated modeling of ELMy H-mode plasmas are presented. A new model for the H-mode pedestal and for the triggering of ELMs predicts the height, width, and shape of the H-mode pedestal and the frequency and width of ELMs. The model for the pedestal and ELMs is used in the ASTRA integrated transport code to follow the time evolution of tokamak discharges from L-mode through the transition from L-mode to H-mode, with the formation of the H-mode pedestal, and, subsequently, to the triggering of ELMs. Turbulence driven by the ion temperature gradient mode, resistive ballooning mode, trapped electron mode, and electron temperature gradient mode contributes to the anomalous thermal transport at the plasma edge in this model. Formation of the pedestal and the L-H transition is the direct result of E(vector) r x B(vector) flow shear suppression of anomalous transport. The periodic ELM crashes are triggered by MHD instabilities. Two mechanisms for triggering ELMs are considered: ELMs are triggered by ballooning modes if the pressure gradient exceeds the ballooning threshold or by peeling modes if the edge current density exceeds the peeling mode threshold. The BALOO, DCON, and ELITE ideal MHD stability codes are used to derive a new parametric expression for the peeling-ballooning threshold. The new dependence for the peeling-ballooning threshold is implemented in the ASTRA transport code. Results of integrated modeling of DIII-D like discharges are presented and compared with experimental observations. The results from the ideal MHD stability codes are compared with results from the resistive MHD stability code NIMROD. (author)

Establishment patterns of water-elm at Catahoula Lake, Louisiana

Science.gov (United States)

Karen S. Doerr; Sanjeev Joshi; Richard F. Keim

2015-01-01

At Catahoula Lake in central Louisiana, an internationally important lake for water fowl, hydrologic alterations to the surrounding rivers and the lake itself have led to an expansion of water-elm (Planera aquatic J.F. Gmel.) into the lake bed. In this study, we used dendrochronology and aerial photography to quantify the expansion of water-elm in the lake and identify...

Integrated simulation of ELM energy loss determined by pedestal MHD and SOL transport

International Nuclear Information System (INIS)

Hayashi, N.; Takizuka, T.; Ozeki, T.; Aiba, N.; Oyama, N.

2007-01-01

An integrated simulation code TOPICS-IB based on a transport code with a stability code for the peeling-ballooning modes and a scrape-off-layer (SOL) model has been developed to clarify self-consistent effects of edge localized modes (ELMs) and the SOL on the plasma performance. Experimentally observed collisionality dependence of the ELM energy loss is found to be caused by both the edge bootstrap current and the SOL transport. The bootstrap current decreases with an increase in collisionality and intensifies the magnetic shear at the pedestal region. The increase in the magnetic shear reduces the width of eigenfunctions of unstable modes, which results in the reduction of both the area of the ELM enhanced transport and the ELM enhanced transport near the separatrix. On the other hand, when an ELM crash occurs, the energy flows into the SOL and the SOL temperature rapidly increases. The increase in the SOL temperature lowers the ELM energy loss due to the flattening of the radial edge gradient. The parallel electron heat conduction determines how the SOL temperature increases. For higher collisionality, the conduction becomes lower and the SOL electron temperature increases more. By the above two mechanisms, the ELM energy loss decreases with increasing collisionality

Multiclass AdaBoost ELM and Its Application in LBP Based Face Recognition

Directory of Open Access Journals (Sweden)

Yunliang Jiang

2015-01-01

Full Text Available Extreme learning machine (ELM is a competitive machine learning technique, which is simple in theory and fast in implementation; it can identify faults quickly and precisely as compared with traditional identification techniques such as support vector machines (SVM. As verified by the simulation results, ELM tends to have better scalability and can achieve much better generalization performance and much faster learning speed compared with traditional SVM. In this paper, we introduce a multiclass AdaBoost based ELM ensemble method. In our approach, the ELM algorithm is selected as the basic ensemble predictor due to its rapid speed and good performance. Compared with the existing boosting ELM algorithm, our algorithm can be directly used in multiclass classification problem. We also carried out comparable experiments with face recognition datasets. The experimental results show that the proposed algorithm can not only make the predicting result more stable, but also achieve better generalization performance.

Exhaust, ELM and Halo physics using the MAST tokamak

International Nuclear Information System (INIS)

Counsell, G.F.; Ahn, J-W.; Kirk, A.; Helander, P.; Martin, R.; Tabasso, A.; Wilson, H.R.; Cohen, R.H.; Ryutov, D.D.; Yang, Y.

2003-01-01

The scrape-off layer (Sol) and divertor target plasma of a large spherical tokamak (ST) is characterised in detail for the first time. Scalings for the SOL heat flux width in MAST are developed and compared to conventional tokamaks. Modelling reveals the significance of the mirror force to the ST SOL. Core energy losses, including during ELMs, in MAST arrive predominantly (>80%) to the outboard targets in all geometries. Convective transport dominates energy losses during ELMs and MHD analysis suggests ELMs in MAST are Type III even at auxiliary heating powers well above the L-H threshold. ELMs are associated with a poloidally and/or toroidally localised radial efflux at ∼1 km/s well into the far SOL but not with any broadening of the target heat flux width. Toroidally asymmetric divertor biasing experiments have been conducted in an attempt to broaden the target heat flux width, with promising results. During vertical displacement events, the maximum product of the toroidal peaking factor and halo current fraction remains below 0.3, around half the ITER design limit. Evidence is presented that the resistance of the halo current path may have an impact on the distribution of halo current. (author)

Development of methods for the restoration of the American elm in forested landscapes

Science.gov (United States)

James M. Slavicek

2013-01-01

A project was initiated in 2003 to establish test sites to develop methods to reintroduce the American elm (Ulmus americana L.) in forested landscapes. American elm tree strains with high levels of tolerance to Dutch elm disease (DED) were established in areas where the trees can naturally regenerate and spread. The process of regeneration will...

Adaptive Control of Nonlinear Discrete-Time Systems by Using OS-ELM Neural Networks

Directory of Open Access Journals (Sweden)

Xiao-Li Li

2014-01-01

Full Text Available As a kind of novel feedforward neural network with single hidden layer, ELM (extreme learning machine neural networks are studied for the identification and control of nonlinear dynamic systems. The property of simple structure and fast convergence of ELM can be shown clearly. In this paper, we are interested in adaptive control of nonlinear dynamic plants by using OS-ELM (online sequential extreme learning machine neural networks. Based on data scope division, the problem that training process of ELM neural network is sensitive to the initial training data is also solved. According to the output range of the controlled plant, the data corresponding to this range will be used to initialize ELM. Furthermore, due to the drawback of conventional adaptive control, when the OS-ELM neural network is used for adaptive control of the system with jumping parameters, the topological structure of the neural network can be adjusted dynamically by using multiple model switching strategy, and an MMAC (multiple model adaptive control will be used to improve the control performance. Simulation results are included to complement the theoretical results.

Electrical testing and performance evaluation of 1:1 prototype JET ELM control coils

Energy Technology Data Exchange (ETDEWEB)

Kanabar, Deven, E-mail: deven@ipr.res.in; Roy, Swati; Ghate, Mahesh; Raj, Piyush; Kundu, Ananya; Kumar, Nitish; Bhavsar, Dhaval; Panchal, Arun; Pradhan, Subrata, E-mail: pradhan@ipr.res.in

2016-12-15

Highlights: • An appropriate 1:1 prototype Small and Large ELM coils for JET have been successfully manufactured using indigenous technologies. • ELM coils have been tested extensively to verify and validated their performance with respect to operational requirement of JET. • The test results confirm and validate the electrical performance of ELM coils. - Abstract: Magnet Technology Development Division at Institute for Plasma research is engaged in extensive R & D for appropriate technologies towards manufacturing of Edge Localized Mode (ELM) magnets for Large Tokamak such as Joint European Torus (JET) as well as for Steady State Superconducting Tokamak (SST-1). Under this project, manufacturing of 1:1 prototype of Large and Small JET ELM control coils (CC) is completed incorporating indigenously developed manufacturing and insulation technologies. Performance evaluation of both the types of coil has been completed for its current carrying capability and insulation resistance as required by various operational scenarios of JET. Experimental setups, test procedures and measurements for electrical characterization of both type of ELM control coil has been discussed in this paper.

Electrical testing and performance evaluation of 1:1 prototype JET ELM control coils

International Nuclear Information System (INIS)

Kanabar, Deven; Roy, Swati; Ghate, Mahesh; Raj, Piyush; Kundu, Ananya; Kumar, Nitish; Bhavsar, Dhaval; Panchal, Arun; Pradhan, Subrata

2016-01-01

Highlights: • An appropriate 1:1 prototype Small and Large ELM coils for JET have been successfully manufactured using indigenous technologies. • ELM coils have been tested extensively to verify and validated their performance with respect to operational requirement of JET. • The test results confirm and validate the electrical performance of ELM coils. - Abstract: Magnet Technology Development Division at Institute for Plasma research is engaged in extensive R & D for appropriate technologies towards manufacturing of Edge Localized Mode (ELM) magnets for Large Tokamak such as Joint European Torus (JET) as well as for Steady State Superconducting Tokamak (SST-1). Under this project, manufacturing of 1:1 prototype of Large and Small JET ELM control coils (CC) is completed incorporating indigenously developed manufacturing and insulation technologies. Performance evaluation of both the types of coil has been completed for its current carrying capability and insulation resistance as required by various operational scenarios of JET. Experimental setups, test procedures and measurements for electrical characterization of both type of ELM control coil has been discussed in this paper.

H-Mode Turbulence, Power Threshold, ELM, and Pedestal Studies in NSTX

International Nuclear Information System (INIS)

Maingi, R.; Bush, C.E.; Fredrickson, E.D.; Gates, D.A.; Kaye, S.M.; LeBlanc, B.P.; Menard, J.E.; Meyer, H.; Mueller, D.; Nishino, N.; Roquemore, A.L.; Sabbagh, S.A.; Tritz, K.; Zweben, S.J.; Bell, M.G.; Bell, R.E.; Biewer, T.; Boedo, J.A.; Johnson, D.W.; Kaita, R.; Kugel, H.W.; Maqueda, R.J.; Munsat, T.; Raman, R.; Soukhanovskii, V.A.; Stevenson, T.; Stutman, D.

2004-01-01

High-confinement mode (H-mode) operation plays a crucial role in NSTX [National Spherical Torus Experiment] research, allowing higher beta limits due to reduced plasma pressure peaking, and long-pulse operation due to high bootstrap current fraction. Here, new results are presented in the areas of edge localized modes (ELMs), H-mode pedestal physics, L-H turbulence, and power threshold studies. ELMs of several other types (as observed in conventional aspect ratio tokamaks) are often observed: (1) large, Type I ELMs, (2) ''medium'' Type II/III ELMs, and (3) giant ELMs which can reduce stored energy by up to 30% in certain conditions. In addition, many high-performance discharges in NSTX have tiny ELMs (newly termed Type V), which have some differences as compared with ELM types in the published literature. The H-mode pedestal typically contains between 25-33% of the total stored energy, and the NSTX pedestal energy agrees reasonably well with a recent international multi-machine scaling. We find that the L-H transition occurs on a ∼100 (micro)sec timescale as viewed by a gas puff imaging diagnostic, and that intermittent quiescent periods precede the final transition. A power threshold identity experiment between NSTX and MAST shows comparable loss power at the L-H transition in balanced double-null discharges. Both machines require more power for the L-H transition as the balance is shifted toward lower single null. High field side gas fueling enables more reliable H-mode access, but does not always lead to a lower power threshold e.g., with a reduction of the duration of early heating. Finally the edge plasma parameters just before the L-H transition were compared with theories of the transition. It was found that while some theories can separate well-developed L- and H-mode data, they have little predictive value

Transition to ELM-free Improved H-mode by Lithium Deposition on NSTX Graphite Divertor Surfaces

International Nuclear Information System (INIS)

Mansfield, D.K.; Kugel, H.W.; Maingi, R.; Bell, M.G.; Bell, R.; Kaita, R.; Kallman, J.; Kaye, S.; LeBlanc, B.; Mueller, D.; Paul, S.; Raman, R.; Roquemore, L.; Sabbagh, S.; Schneider, H.; Skinner, C.H.; Soukhanovskii, V.; Timberlake, J.; Wilgen, J.; Zakharov, L.

2009-01-01

Lithium evaporated onto plasma facing components in the NSTX lower divertor has made dramatic improvements in discharge performance. As lithium accumulated, plasmas previously exhibiting robust Type 1 ELMs gradually transformed into discharges with intermittent ELMs and finally into continuously evolving ELM-free discharges. During this sequence, other discharge parameters changed in a complicated manner. As the ELMs disappeared, energy confinement improved and remarkable changes in edge and scrape-off layer plasma properties were observed. These results demonstrate that active modification of plasma surface interactions can preempt large ELMs.

Observations of ELM stabilization during neutral beam injection in DIII-D

Science.gov (United States)

Bortolon, Alessandro; Kramer, Gerrit; Diallo, Ahmed; Knolker, Matthias; Maingi, Rajesh; Nazikian, Raffi; Degrassie, John; Osborne, Thomas

2017-10-01

Edge localized modes (ELMs) are generally interpreted as peeling-ballooning instabilities, driven by the pedestal current and pressure gradient, with other subdominant effects possibly relevant close to marginal stability. We report observations of transient stabilization of type-I ELMs during neutral beam injection (NBI), emerging from a combined dataset of DIII-D ELMy H-mode plasmas with moderate heating obtained through pulsed NBI waveforms. Statistical analysis of ELM onset times indicates that, in the selected dataset, the likelihood of onset of an ELM lowers significantly during NBI modulation pulses, with the stronger correlation found with counter-current NBI. The effect is also found in rf-heated H-modes, where ELMs appear inhibited when isolated diagnostic beam pulses are applied. Coherent average analysis is used to determine how plasma density, temperature, rotation as well as beam ion quantities evolve during a NB modulation cycle, finding relatively small changes ( 3%) of pedestal Te and ne and toroidal and poloidal rotation variations up to 5 km/s. The effect of these changes on pedestal stability will be discussed. Work supported by US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466.

e-Learning Management System (eLMS) -

Data.gov (United States)

Department of Transportation — DOT's electronic Learning Management System (eLMS) is a state-of-the-art web-based system that meets the needs of training administrators, learners, and managers and...

Integrated simulations of H-mode operation in ITER including core fuelling, divertor detachment and ELM control

Science.gov (United States)

Polevoi, A. R.; Loarte, A.; Dux, R.; Eich, T.; Fable, E.; Coster, D.; Maruyama, S.; Medvedev, S. Yu.; Köchl, F.; Zhogolev, V. E.

2018-05-01

ELM mitigation to avoid melting of the tungsten (W) divertor is one of the main factors affecting plasma fuelling and detachment control at full current for high Q operation in ITER. Here we derive the ITER operational space, where ELM mitigation to avoid melting of the W divertor monoblocks top surface is not required and appropriate control of W sources and radiation in the main plasma can be ensured through ELM control by pellet pacing. We apply the experimental scaling that relates the maximum ELM energy density deposited at the divertor with the pedestal parameters and this eliminates the uncertainty related with the ELM wetted area for energy deposition at the divertor and enables the definition of the ITER operating space through global plasma parameters. Our evaluation is thus based on this empirical scaling for ELM power loads together with the scaling for the pedestal pressure limit based on predictions from stability codes. In particular, our analysis has revealed that for the pedestal pressure predicted by the EPED1  +  SOLPS scaling, ELM mitigation to avoid melting of the W divertor monoblocks top surface may not be required for 2.65 T H-modes with normalized pedestal densities (to the Greenwald limit) larger than 0.5 to a level of current of 6.5–7.5 MA, which depends on assumptions on the divertor power flux during ELMs and between ELMs that expand the range of experimental uncertainties. The pellet and gas fuelling requirements compatible with control of plasma detachment, core plasma tungsten accumulation and H-mode operation (including post-ELM W transient radiation) have been assessed by 1.5D transport simulations for a range of assumptions regarding W re-deposition at the divertor including the most conservative assumption of zero prompt re-deposition. With such conservative assumptions, the post-ELM W transient radiation imposes a very stringent limit on ELM energy losses and the associated minimum required ELM frequency. Depending on

QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALLOONING MODES

International Nuclear Information System (INIS)

LAO, LL; SNYDER, PB; LEONARD, AW; OSBORNE, TH; PETRIE, TW; FERRON, JR; GROEBNER, RJ; HORTON, LD; KAMADA, Y; MURAKAMI, M; OIKAWA, T; PEARLSTEIN, LD; SAARELMA, S; STJOHN, HE; THOMAS, DM; TURNBULL, AD; WILSON, HR

2002-01-01

OAK A271 QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALLOONING MODES. Two of the major issues crucial for the design of the next generation tokamak burning plasma devices are the predictability of the edge pedestal height and control of the divertor heat load in H-mode configurations. Both of these are strongly impacted by edge localized modes (ELMs) and their size. A working model for ELMs is that they are intermediate toroidal mode number, n ∼ 5-30, peeling-ballooning modes driven by the large edge pedestal pressure gradient P(prime) and the associated large edge bootstrap current density J BS . the interplay between P(prime) and J BS as a discharge evolves can excite peeling-ballooning modes over a wide spectrum of n. The pedestal current density plays a dual role by stabilizing the high n ballooning modes via opening access to second stability but providing free energy to drive the intermediate n peeling modes. This makes a systematic evaluation of this model particularly challenging. This paper describes recent quantitative tests of this model using experimental data from the DIII-D and the JT-60U tokamaks. These tests are made possible by recent improvements to the ELITE MHD stability code, which allow an efficient evaluation of the unstable peeling-ballooning modes, as well as by improvements to other diagnostic and analysis techniques. Some of the key testable features of this model are: (1) ELMs are triggered when the growth rates of intermediate n MHD modes become significantly large; (2) ELM sizes are related to the radial widths of the unstable modes; (3) the unstable modes have a strong ballooning character localized in the outboard bad curvature region; (4) at high collisionality, ELM size generally becomes smaller because J BS is reduced

ELM elimination with Li powder injection in EAST discharges using the tungsten upper divertor

Science.gov (United States)

Maingi, R.; Hu, J. S.; Sun, Z.; Tritz, K.; Zuo, G. Z.; Xu, W.; Huang, M.; Meng, X. C.; Canik, J. M.; Diallo, A.; Lunsford, R.; Mansfield, D. K.; Osborne, T. H.; Gong, X. Z.; Wang, Y. F.; Li, Y. Y.; EAST Team

2018-02-01

We report the first successful use of lithium (Li) to eliminate edge-localized modes (ELMs) with tungsten divertor plasma-facing components in the EAST device. Li powder injected into the scrape-off layer of the tungsten upper divertor successfully eliminated ELMs for 3-5 s in EAST. The ELM elimination became progressively more effective in consecutive discharges at constant lithium delivery rates, and the divertor D α baseline emission was reduced, both signatures of improved wall conditioning. A modest decrease in stored energy and normalized energy confinement was also observed, but the confinement relative to H98 remained well above 1, extending the previous ELM elimination results via Li injection into the lower carbon divertor in EAST (Hu et al 2015 Phys. Rev. Lett. 114 055001). These results can be compared with recent observations with lithium pellets in ASDEX-Upgrade that failed to mitigate ELMs (Lang et al 2017 Nucl. Fusion 57 016030), highlighting one comparative advantage of continuous powder injection for real-time ELM elimination.

THE ELM SURVEY. IV. 24 WHITE DWARF MERGER SYSTEMS

International Nuclear Information System (INIS)

Kilic, Mukremin; Brown, Warren R.; Kenyon, S. J.; Allende Prieto, Carlos; Heinke, Craig O.; Agüeros, M. A.; Kleinman, S. J.

2012-01-01

We present new radial velocity and X-ray observations of extremely low mass (ELM, ∼0.2 M ☉ ) white dwarf (WD) candidates in the Sloan Digital Sky Survey Data Release 7 area. We identify seven new binary systems with 1-18 hr orbital periods. Five of the systems will merge due to gravitational wave radiation within 10 Gyr, bringing the total number of merger systems found in the ELM Survey to 24. The ELM Survey has now quintupled the known merger WD population. It has also discovered the eight shortest period detached binary WD systems currently known. We discuss the characteristics of the merger and non-merger systems observed in the ELM Survey, including their future evolution. About half of the systems have extreme mass ratios. These are the progenitors of the AM Canum Venaticorum systems and Type Ia supernovae. The remaining targets will lead to the formation of extreme helium stars, subdwarfs, or massive WDs. We identify three targets that are excellent gravitational wave sources. These should be detected by the Laser Interferometer Space Antenna like missions within the first year of operation. The remaining targets are important indicators of what the Galactic foreground may look like for gravitational wave observatories.

THE ELM SURVEY. IV. 24 WHITE DWARF MERGER SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, OK 73019 (United States); Brown, Warren R.; Kenyon, S. J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Allende Prieto, Carlos [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Heinke, Craig O. [Department of Physics, CCIS 4-183, University of Alberta, Edmonton, AB, T6G 2E1 (Canada); Agueeros, M. A. [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Kleinman, S. J., E-mail: kilic@ou.edu [Gemini Observatory, 670 North A' ohoku Place, Hilo, HI 96720 (United States)

2012-06-01

We present new radial velocity and X-ray observations of extremely low mass (ELM, {approx}0.2 M{sub Sun }) white dwarf (WD) candidates in the Sloan Digital Sky Survey Data Release 7 area. We identify seven new binary systems with 1-18 hr orbital periods. Five of the systems will merge due to gravitational wave radiation within 10 Gyr, bringing the total number of merger systems found in the ELM Survey to 24. The ELM Survey has now quintupled the known merger WD population. It has also discovered the eight shortest period detached binary WD systems currently known. We discuss the characteristics of the merger and non-merger systems observed in the ELM Survey, including their future evolution. About half of the systems have extreme mass ratios. These are the progenitors of the AM Canum Venaticorum systems and Type Ia supernovae. The remaining targets will lead to the formation of extreme helium stars, subdwarfs, or massive WDs. We identify three targets that are excellent gravitational wave sources. These should be detected by the Laser Interferometer Space Antenna like missions within the first year of operation. The remaining targets are important indicators of what the Galactic foreground may look like for gravitational wave observatories.

Exhaust, ELM and halo physics using the MAST tokamak

International Nuclear Information System (INIS)

Counsell, G. F.

2002-01-01

Scalings for the SOL width on MAST extend the parameter range of conventional devices but confirm a negative dependence on power flow across the separatrix. In L-mode and at ELM peaks, >95% of power to the targets arrives to the outboard side. Peak heat flux densities rise by a factor 2∼6 during ELMs and are accompanied by a shift in the strike-point location but by little change in the target heat flux width. Energy loss per ELM as a percentage of pedestal energy and pedestal collisionality appear uncorrelated, possibly because ELMs on MAST are dominated by convective transport. Modelling shows that parallel gradients in the magnitude of the magnetic field in MAST may drive strong upstream flows. Broadening of the target heat flux width by divertor biasing is being explored as a means of reducing target power loading in next-step devices and has facilitated halo current measurements using series resistors. Halo currents are always less than 30% of plasma current and the product of toroidal peaking factor and halo current fraction is ∼50% of the ITER design limit. Varying the series resistance demonstrates that the VDE behaves more as a voltage source than a current source. (author)

Integrated ELM simulation with edge MHD stability and transport of SOL-divertor plasmas

International Nuclear Information System (INIS)

Hayashi, Nobuhiko; Takizuka, Tomonori; Aiba, Nobuyuki; Ozeki, Takahisa; Oyama, Naoyuki

2007-07-01

The effect of the pressure profile on the energy loss caused by edge localized modes (ELMs) has been investigated by using an integrated simulation code TOPICS-IB based on a core transport code with a stability code for the peeling-ballooning modes and a transport model for scrape-off-layer and divertor plasmas. The steep pressure gradient inside the pedestal top is found to broaden the region of the ELM enhanced transport through the broadening of eigenfunctions and enhance the ELM energy loss. The ELM energy loss in the simulation becomes larger than 15% of the pedestal energy, as is shown in the database of multi-machine experiments. (author)

Helical beating of an actuated elastic filament

International Nuclear Information System (INIS)

Coq, Nais; Roure, Olivia du; Fermigier, Marc; Bartolo, Denis

2009-01-01

We investigate the propulsive force resulting from the rotation of a flexible filament in the low Reynolds number regime. Using a simple linear model, we establish the nonlinear torque-force relations for two torque-driven actuation modes. When the rotation of the filament is induced by two perpendicular transverse oscillating torques, the propulsive force increases monotonically with the torque amplitude. Conversely, when a constant axial torque is applied, the torque-force characteristics displays an unstable branch, related to a discontinuous transition in the shape of the filament. We characterize this shape transition using two geometrical parameters, quantifying the wrapping around and the collapse on the axis of the filament. The proposed theoretical description correctly accounts for our experimental observations and reveals a strong dependence of the filament dynamics on the anchoring conditions.

Assessment of erosion of the ITER divertor targets during type I ELMs

Science.gov (United States)

Federici, G.; Loarte, A.; Strohmayer, G.

2003-09-01

This paper presents the results of a preliminary assessment conducted to estimate the thermal response and erosion lifetime of the ITER divertor targets clad either with carbon-fibre composite or tungsten during type I ELMs. The one-dimensional thermal/erosion model, used for the analyses, is briefly described. It includes all the key surface heat transfer processes such as evaporation, melting, and radiation, and their interaction with the bulk thermal response, and it is based on an implicit finite-difference scheme, which allows for temperature-dependent material properties. The cases analysed clarify the influence of several ELM parameters on the heat transfer and erosion processes at the target (i.e. characteristic plasma ELM energy loss from the pedestal, fraction of the energy reaching the divertor, broadening of the strike-points during ELMs, duration and waveform of the ELM heat load) and design/material parameters (i.e. inclination of the target, type and thickness of the armour material, and for tungsten only, fraction of the melt layer loss). Comparison is made between cases where all ELMs are characterized by the same fixed averaged parameters, and cases where instead the characteristic parameters of each ELM are evaluated in a random fashion by using a standard Monte Carlo technique, based on distributions of some of the variables of interest derived from experiments in today's machines. Although uncertainties rule out providing firm quantitative predictions, the results of this study are useful to illustrate trends. Based on the results, the implications on the design and operation are discussed and priorities are determined for the R&D needed to reduce the remaining uncertainties.

Assessment of erosion of the ITER divertor targets during type I ELMs

International Nuclear Information System (INIS)

Federici, G; Loarte, A; Strohmayer, G

2003-01-01

This paper presents the results of a preliminary assessment conducted to estimate the thermal response and erosion lifetime of the ITER divertor targets clad either with carbon-fibre composite or tungsten during type I ELMs. The one-dimensional thermal/erosion model, used for the analyses, is briefly described. It includes all the key surface heat transfer processes such as evaporation, melting, and radiation, and their interaction with the bulk thermal response, and it is based on an implicit finite-difference scheme, which allows for temperature-dependent material properties. The cases analysed clarify the influence of several ELM parameters on the heat transfer and erosion processes at the target (i.e. characteristic plasma ELM energy loss from the pedestal, fraction of the energy reaching the divertor, broadening of the strike-points during ELMs, duration and waveform of the ELM heat load) and design/material parameters (i.e. inclination of the target, type and thickness of the armour material, and for tungsten only, fraction of the melt layer loss). Comparison is made between cases where all ELMs are characterized by the same fixed averaged parameters, and cases where instead the characteristic parameters of each ELM are evaluated in a random fashion by using a standard Monte Carlo technique, based on distributions of some of the variables of interest derived from experiments in today's machines. Although uncertainties rule out providing firm quantitative predictions, the results of this study are useful to illustrate trends. Based on the results, the implications on the design and operation are discussed and priorities are determined for the R and D needed to reduce the remaining uncertainties

Theory-based model for the pedestal, edge stability and ELMs in tokamaks

International Nuclear Information System (INIS)

Pankin, A.Y.; Bateman, G.; Brennan, D.P.; Schnack, D.D.; Snyder, P.B.; Voitsekhovitch, I.; Kritz, A.H.; Janeschitz, G.; Kruger, S.; Onjun, T.; Pacher, G.W.; Pacher, H.D.

2006-01-01

An improved model for triggering edge localized mode (ELM) crashes is developed for use within integrated modelling simulations of the pedestal and ELM cycles at the edge of H-mode tokamak plasmas. The new model is developed by using the BALOO, DCON and ELITE ideal MHD stability codes to derive parametric expressions for the ELM triggering threshold. The whole toroidal mode number spectrum is studied with these codes. The DCON code applies to low mode numbers, while the BALOO code applies to only high mode numbers and the ELITE code applies to intermediate and high mode numbers. The variables used in the parametric stability expressions are the normalized pressure gradient and the parallel current density, which drive ballooning and peeling modes. Two equilibria motivated by DIII-D geometry with different plasma triangularities are studied. It is found that the stable region in the high triangularity discharge covers a much larger region of parameter space than the corresponding stability region in the low triangularity discharge. The new ELM trigger model is used together with a previously developed model for pedestal formation and ELM crashes in the ASTRA integrated modelling code to follow the time evolution of the temperature profiles during ELM cycles. The ELM frequencies obtained in the simulations of low and high triangularity discharges are observed to increase with increasing heating power. There is a transition from second stability to first ballooning mode stability as the heating power is increased in the high triangularity simulations. The results from the ideal MHD stability codes are compared with results from the resistive MHD stability code NIMROD

The Prediction of Yarn Elongation of Kenyan Ring-Spun Yarn using Extreme Learning Machines (ELM

Directory of Open Access Journals (Sweden)

Josphat Igadwa Mwasiagi

2017-03-01

Full Text Available The optimization of the manufacture of cotton yarns involves several processes, while the prediction of yarn quality parameters forms an important area of investigation. This research work concentrated on the prediction of cotton yarn elongation. Cotton lint and yarn samples were collected in textile factories in Kenya.The collected samples were tested under standard testing conditions. Cotton lint parameters, machine parameters and yarn elongation were used to design yarn elongation prediction models. The elongation prediction models used three network training algorithms, including backpropagation (BP, an extreme learning machine (ELM, and a hybrid of differential evolution (DE and an ELM referred to as DE-ELM. The prediction models recorded a mean squared error (mse value of 0.001 using 11, 43 and 2 neurons in the hidden layer for the BP, ELM and DE-ELM models respectively. The ELM models exhibited faster training speeds than the BP algorithms, but required more neurons in the hidden layer than other models. The DEELM hybrid algorithm was faster than the BP algorithm, but slower than the ELM algorithm.

Investigation of dynamics of ELM crashes and their mitigation techniques

Energy Technology Data Exchange (ETDEWEB)

Pankin, Alexei Y. [Tech-X Corporation, Boulder, CO (United States)

2015-08-14

The accurate prediction of H-mode pedestal dynamics is critical for planning experiments in existing tokamaks and in the design of future tokamaks such as ITER and DEMO. The main objective of the proposed research is to advance the understanding of the physics of H-mode pedestal. Through advances in coupled kinetic-MHD simulations, a new model for H-mode pedestal and ELM crashes as well as an improved model for the bootstrap current will be developed. ELMmitigation techniques will also be investigated. The proposed research will help design efficient confinement scenarios and reduce transient heat loads on the divertor and plasma facing components. During the last two years, the principal investigator (PI) of this proposal actively participated in physics studies related to the DOE Joint Research Targets. These studies include the modeling of divertor heat load in the DIII-D, Alcator C-Mod, and NSTX tokamaks in 2010, and the modeling of H-mode pedestal structure in the DIII-D tokamak in 2011. It is proposed that this close collaboration with experimentalists from major US tokamaks continue during the next funding period. Verification and validation will be a strong component of the proposed research. During the course of the project, advances will be made in the following areas; Dynamics of the H-mode pedestal buildup and recovery after ELM crashes – The effects of neutral fueling, particle and thermal pinches will be explored; Dynamics of ELM crashes in realistic tokamak geometries – Heat loads associated with ELM crashes will be validated against experimental measurements. An improved model for ELM crashes will be developed; ELM mitigation – The effect of resonant magnetic perturbations on ELMs stability and their evolution will be investigated; Development of a new bootstrap current model – A reduced model for will be developed through careful verification of existing models for bootstrap current against first-principle kinetic neoclassical simulations

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

Science.gov (United States)

Preil, Simone Andrea Rørdam; Thorsen, Anne-Sofie Faarvang; Christiansen, Anne Lindegaard; Poulsen, Mikael Kjær; Karsdal, Morten Asser; Leeming, Diana Julie; Rasmussen, Lars Melholt

2017-11-01

Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM. Blood samples from 302 type 2 diabetic patients were analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index. T2DM patients with peripheral arterial disease (low ankle-brachial index) (PAD) display higher levels of MMP-2 and ELM compared to patients without PAD. However, none of the proteins or degradation products correlated with myocardial ischemia or a combined measure of CVD-signs, including myocardial ischemia, increased carotid thickness and decreased ankle-brachial blood pressure. Our results suggest that the diabetic environment affects the circulating amounts of MMP-2 and ELM in patients with PAD. However, the same connection could not be seen in diabetic patients with CVD broadly identified in three vascular territories. LOX and ELM-2 did not correlate to any type of CVD. Overall, serum levels of elastin-related molecules are only remotely related to CVD in type 2 diabetes.

ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

NARCIS (Netherlands)

Baylor, L.R.; Lang, P.T.; Allen, S.L.; Combs, S.K.; Commaux, N.; Evans, T.E.; Fenstermacher, M.E.; Huijsmans, G.T.A.; Jernigan, T.C.; Lasnier, C.J.; Leonard, A.W.; Loarte, A.; Maingi, R.; Maruyama, S.; Meitner, S.J.; Moyer, R.A.; Osborne, T.H.

2015-01-01

PLASMA-SURFACE INTERACTIONS 21 — Proceedings of the 21st International Conference on Plasma-Surface Interactions in Controlled Fusion Devices Kanazawa, Japan May 26-30, 2014 The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to

Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

Science.gov (United States)

Suslova, A.; El-Atwani, O.; Sagapuram, D.; Harilal, S. S.; Hassanein, A.

2014-11-01

Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten.

ELM as a trigger mechanism for the transition between two Edge regimes

International Nuclear Information System (INIS)

Pshenov, A.A.; Morozov, D.Kh.

2012-01-01

The possibility of edge regime transitions under the influence of edge-localized modes (ELMs) is investigated. A theoretical model of the process is presented and examined numerically. ELMs appear able to trigger irreversible transitions from one equilibrium to another with different edge temperatures. The results correspond to the recent experimental studies on both DIII-D and JET tokamaks showing type-I and type-II ELMs causing a prolonged collapse of the edge plasma temperature (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Plant signals during beetle (Scolytus multistriatus) feeding in American elm (Ulmus americana Planch).

Science.gov (United States)

Saremba, Brett M; Tymm, Fiona J M; Baethke, Kathy; Rheault, Mark R; Sherif, Sherif M; Saxena, Praveen K; Murch, Susan J

2017-05-04

American Elms were devastated by an outbreak of Dutch Elm Disease is caused by the fungus Ophiostoma novo-ulmi Brasier that originated in Asia and arrived in the early 1900s. In spite of decades of study, the specific mechanisms and disease resistance in some trees is not well understood. the fungus is spread by several species of bark beetles in the genus Scolytus, during their dispersal and feeding. Our objective was to understand elm responses to beetle feeding in the absence of the fungus to identify potential resistance mechanisms. A colony of Scolytus multistriatus was established from wild-caught beetles and beetles were co-incubated with susceptible or resistant American elm varieties in a controlled environment chamber. Beetles burrowed into the auxillary meristems of the young elm shoots. The trees responded to the beetle damage by a series of spikes in the concentration of plant growth regulating compounds, melatonin, serotonin, and jasmonic acid. Spikes in melatonin and serotonin represented a 7,000-fold increase over resting levels. Spikes in jasmonic acid were about 10-fold higher than resting levels with one very large spike observed. Differences were noted between susceptible and resistant elms that provide new understanding of plant defenses.

Magnetohydrodynamic behaviour during core transport barrier experiments with ion Bernstein wave heating in PBX-M: I ELMs fluctuations and crash events

International Nuclear Information System (INIS)

Sesnic, S.; Kaita, R.; Batha, S.H.

1998-01-01

If the ion Bernstein wave (IBW) heating power in an H mode discharge of the PBX-M experiment exceeds a threshold power of about 200 kW, a core transport barrier is created in the central region of the plasma. At lower neutral beam injection (NBI) powers, the core barrier is accompanied by an edge L mode. The high edge localized mode (ELM) repetition frequency (1 kHz) prevents the creation of a strong barrier, so the edge first has to make an H-to-L transition before a strong core transport barrier can be created. At higher NBI powers, the ELM repetition frequency is lowered to less than 200 Hz, which allows the immediate creation of a strong core barrier. Edge localized mode loss, which propagates radially first on a fast (non-diffusive) and then on a slow (diffusive) time-scale all the way to the plasma core, is strongly reduced in the core barrier region. Correlated with the reduced ELM loss, the fluctuations in the core barrier region are also strongly reduced, both during the ELM and during the quite periods between the ELMs. There is strong evidence that the IBW induced poloidal flow shear is responsible for the stabilization of core turbulence and the creation of the core transport barrier. The large perpendicular E x B flow shear component of the measured toroidal velocity in co-injection neutral beam heated discharges seems to be largely cancelled by the ion diamagnetic drift shear produced by large ion pressure gradients in the core barrier region. The value of IBW induced poloidal flow has not been experimentally determined, but its numerical value is found to be a factor of 4 larger than either the toroidal velocity or the ion diamagnetic drift shear components, leaving only IBW induced flow shear as the most probable cause for the turbulence stabilization. The core turbulence suppression and the creation of the core transport barrier is also consistent with expectations from a comparison between the E x B flow shear rate and a rough estimate of the

Terahertz waves radiated from two noncollinear femtosecond plasma filaments

Energy Technology Data Exchange (ETDEWEB)

Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko, E-mail: otani@riken.jp [Terahertz Sensing and Imaging Research Team, RIKEN Center for Advanced Photonics, RIKEN, Sendai, Miyagi 980-0845 (Japan); Midorikawa, Katsumi [Attosecond Science Research Team, RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan)

2015-11-23

Terahertz (THz) waves radiated from two noncollinear femtosecond plasma filaments with a crossing angle of 25° are investigated. The irradiated THz waves from the crossing filaments show a small THz pulse after the main THz pulse, which was not observed in those from single-filament scheme. Since the position of the small THz pulse changes with the time-delay of two filaments, this phenomenon can be explained by a model in which the small THz pulse is from the second filament. The denser plasma in the overlap region of the filaments changes the movement of space charges in the plasma, thereby changing the angular distribution of THz radiation. As a result, this schematic induces some THz wave from the second filament to propagate along the path of the THz wave from the first filament. Thus, this schematic alters the direction of the THz radiation from the filamentation, which can be used in THz wave remote sensing.

Observation of pre- and postcursor modes of type-I ELMs on JET

International Nuclear Information System (INIS)

Koslowski, H.R.; Perez, C.; Alper, B.; Hender, T.C.; Sharapov, S.E.; Eich, T.; Huysmans, G.T.A.; Smeulders, P.; Westerhof, E.

2003-01-01

Recent observations of MHD activity in type-I ELMy H-mode discharges on JET have revealed two phenomena: (i) the so-called palm tree mode, a new, snake-like MHD mode at the q = 3 surface which is excited by type-I ELMs, and (ii) coherent MHD mode activity as a precursor to the ELM collapse. Both modes are detected by magnetic pick up coils and can also be seen on the edge ECE and SXR measurements. They are located a few cm inside the separatrix. Palm tree modes have been identified in a wide range of plasma conditions, which comprise standard ELMy H-modes, ITER-like plasma shapes, pellet fuelling, and even pure helium plasmas. The mode frequency increases in time and starts to saturate until the mode finally decays. A possible explanation of the palm tree mode is, that it is the remnant of a (3,1)-island created due to edge ergodisation by the ELM perturbation. The type-I ELM precursor modes have toroidal mode numbers n in the range 1 to 14, a kink-like structure, and appear commonly 0.5 - 1 ms before the ELM, but can appear much earlier in some cases. (author)

Interplay between Solo and keratin filaments is crucial for mechanical force-induced stress fiber reinforcement.

Science.gov (United States)

Fujiwara, Sachiko; Ohashi, Kazumasa; Mashiko, Toshiya; Kondo, Hiroshi; Mizuno, Kensaku

2016-03-15

Mechanical force-induced cytoskeletal reorganization is essential for cell and tissue remodeling and homeostasis; however, the underlying cellular mechanisms remain elusive. Solo (ARHGEF40) is a RhoA-targeting guanine nucleotide exchange factor (GEF) involved in cyclical stretch-induced human endothelial cell reorientation and convergent extension cell movement in zebrafish gastrula. In this study, we show that Solo binds to keratin-8/keratin-18 (K8/K18) intermediate filaments through multiple sites. Solo overexpression promotes the formation of thick actin stress fibers and keratin bundles, whereas knockdown of Solo, expression of a GEF-inactive mutant of Solo, or inhibition of ROCK suppresses stress fiber formation and leads to disorganized keratin networks, indicating that the Solo-RhoA-ROCK pathway serves to precisely organize keratin networks, as well as to promote stress fibers. Of importance, knockdown of Solo or K18 or overexpression of GEF-inactive or deletion mutants of Solo suppresses tensile force-induced stress fiber reinforcement. Furthermore, knockdown of Solo or K18 suppresses tensile force-induced RhoA activation. These results strongly suggest that the interplay between Solo and K8/K18 filaments plays a crucial role in tensile force-induced RhoA activation and consequent actin cytoskeletal reinforcement. © 2016 Fujiwara et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Plasma shaping and its impact on the pedestal of ASDEX Upgrade: edge stability and inter-ELM dynamics at varied triangularity

Science.gov (United States)

Laggner, F. M.; Wolfrum, E.; Cavedon, M.; Dunne, M. G.; Birkenmeier, G.; Fischer, R.; Willensdorfer, M.; Aumayr, F.; The EUROfusion MST1 Team; The ASDEX Upgrade Team

2018-04-01

The plasma shape, in particular the triangularity (δ), impacts on the pedestal stability. A scan of δ including a variation of heating power (P heat) and gas puff was performed to study the behaviour of edge localised modes (ELMs) and the pre-ELM pedestal stability for different plasma shapes. Generally, at higher δ the pedestal top electron density (n e) is enhanced and the ELM repetition frequency (f ELM) is reduced. For all δ, the pedestal top n e is already fully established to its pre-ELM value during the initial recovery phase of the n e pedestal, which takes place immediately after the ELM crash. The lowering of the f ELM with increasing δ is related to longer pedestal recovery phases, especially the last pre-ELM phase with clamped pedestal gradients (after the recovery phases of the n e and electron temperature (T e) pedestal) is extended. In all investigated discharge intervals, the pre-ELM pedestal profiles are in agreement with peeling-ballooning (PB) theory. Over the investigated range of δ, two well-separated f ELM bands are observed in several discharge intervals. Their occurrence is linked to the inter-ELM pedestal stability. In both kinds of ELM cycles the pedestal evolves similarly, however, the ‘fast’ ELM cycle occurs before the global plasma stored energy (W MHD) increases, which then provides a stabilising effect on the pedestal, extending the inter-ELM period in the case of the ‘slow’ ELM cycle. At the end of a ‘fast’ ELM cycle the n e profile is radially shifted inwards relative to the n e profile at the end of a ‘slow’ ELM cycle, leading to a reduced pressure gradient. The appearance of two f ELM bands suggests that the pedestal becomes more likely PB unstable in certain phases of the inter-ELM evolution. Such a behaviour is possible because the evolution of the global plasma is not rigidly coupled to the evolution of the pedestal structure on the timescales of an ELM cycle.

Contamination of ITER core by high-Z impurities after ELMs

International Nuclear Information System (INIS)

Landman, I.; Janeschitz, G.

2007-01-01

The H-mode confinement in the future tokamak ITER is anticipated to be repetitively worsened by edge localized instabilities (ELMs). At each ELM the deuterium-tritium (DT) plasma lost from the pedestal into the scrape-off layer (SOL) and further onto a divertor armour produces surface erosion. The following contamination of SOL by the eroded and then ionized material species provides the impurities in the pedestal and the core. The fraction of carbon-based material (CBM) must be minimized, because of not acceptable accumulation rate of radioactive tritium inside its bulk. Therefore tungsten-based material (WBM) should be preferable even near the separatrix strike point (SSP) where DT-plasma maximum flux impacts on CBM tiles. However, the presence of highly but not fully ionized W-ions in the confinement region may get dangerous for the device operation, which is due to enhanced heat loss by the line radiation of W-ions. In this work the DT-plasma contamination after the Type I ELMs is simulated with the tokamak integrated modelling code TOKES. The simulations imply some ELM-caused heat flux distribution over the wall as a function of time and poloidal coordinate along the divertor surface. The processes of emission of eroded C- and W-atoms and their ionization in the SOL as well as the multi-fluid transport in the confinement region among D-, T-, He-, C- and W-ions are calculated for the whole ITER discharge with multiple ELMs, different fuelling and auxiliary heating schemes (neutral beams and pellets) and the burning at fusion gain Q<10. The aim is obtaining tolerable ELM energy based on the radiation losses and deterioration of fusion gain caused by the W-impurity that was produced after the ELM. The TOKES calculates self-consistently also both the poloidal field external coil currents and the confined plasma currents and thus the separatrix dynamics, and thus a significant broadening of power footprint compared to the usual assumption of the SOL effective width

Contamination of ITER core by high-Z impurities after ELMs

Energy Technology Data Exchange (ETDEWEB)

Landman, I.; Janeschitz, G. [Forschungszentrum Karlsruhe (Germany). IHM Fusion

2007-07-01

The H-mode confinement in the future tokamak ITER is anticipated to be repetitively worsened by edge localized instabilities (ELMs). At each ELM the deuterium-tritium (DT) plasma lost from the pedestal into the scrape-off layer (SOL) and further onto a divertor armour produces surface erosion. The following contamination of SOL by the eroded and then ionized material species provides the impurities in the pedestal and the core. The fraction of carbon-based material (CBM) must be minimized, because of not acceptable accumulation rate of radioactive tritium inside its bulk. Therefore tungsten-based material (WBM) should be preferable even near the separatrix strike point (SSP) where DT-plasma maximum flux impacts on CBM tiles. However, the presence of highly but not fully ionized W-ions in the confinement region may get dangerous for the device operation, which is due to enhanced heat loss by the line radiation of W-ions. In this work the DT-plasma contamination after the Type I ELMs is simulated with the tokamak integrated modelling code TOKES. The simulations imply some ELM-caused heat flux distribution over the wall as a function of time and poloidal coordinate along the divertor surface. The processes of emission of eroded C- and W-atoms and their ionization in the SOL as well as the multi-fluid transport in the confinement region among D-, T-, He-, C- and W-ions are calculated for the whole ITER discharge with multiple ELMs, different fuelling and auxiliary heating schemes (neutral beams and pellets) and the burning at fusion gain Q<10. The aim is obtaining tolerable ELM energy based on the radiation losses and deterioration of fusion gain caused by the W-impurity that was produced after the ELM. The TOKES calculates self-consistently also both the poloidal field external coil currents and the confined plasma currents and thus the separatrix dynamics, and thus a significant broadening of power footprint compared to the usual assumption of the SOL effective width

Theory and Simulations of ELM Control with a Snowflake Divertor

Energy Technology Data Exchange (ETDEWEB)

Ryutov, D.; Cohen, B.; Cohen, R.; Makowski, M. A.; Menard, J.; Rognlien, T.; Soukhanovskii, V.; Umansky, M.; Xu, X., E-mail: ryutov1@llnl.gov [Lawrence Livermore National Laboratory, Livermore (United States); Kolemen, E. [Princeton Plasma Physics Laboratory, Princeton (United States)

2012-09-15

Full text: This paper is concerned with the use of a snowflake (SF) divertor for the control and mitigation of edge localized modes (ELMs). Our research is focused on the following three issues: 1. Effect of the SF geometry on neoclassical ion orbits near the separatrix, including prompt ion losses and the related control mechanism for the electric field and plasma flow in the pedestal; 2. Influence of the thereby modified flow and of high poloidal plasma beta in the divertor region on plasma turbulence and transport in the snowflake-plus geometry; 3. Reaction of the SF divertor to type-1 ELM events. Neoclassical ion orbits in the vicinity of the SF separatrix are changed due to a much weaker poloidal field near the null and much longer particle dwell-time in this area. This leads to an increase of the prompt ion loss, which then affects the radial electric field profile near the separatrix. The resulting E x B flow shear in the pedestal region affects the onset of ELMs. The electric field and velocity shear are then used as a background for two-fluid simulations of the edge plasma turbulence in a realistic geometry with the 3D BOUT code. A SF-plus geometry is chosen, so that the separatrix topology remains the same as for the standard X-point divertor, whereas the magnetic shear both inside and outside the separatrix increases dramatically. It is found that mesoscale instabilities are suppressed when the geometry is close to a perfect SF. In situations where complete suppression of ELMs is impossible, the SF divertor offers a path to reducing heat loads during ELM events to an acceptable level. Two effects, both related to the weakness of the poloidal field near the SF null, act synergistically in the same favorable direction. The first is the onset of strong, curvature-driven convection in the divertor, triggered by the increase of the poloidal pressure during the ELM and leading to the splitting of the heat flux between all four (as is the case in a SF geometry

Stabilizing effect of resistivity towards ELM-free H-mode discharge in lithium-conditioned NSTX

Science.gov (United States)

Banerjee, Debabrata; Zhu, Ping; Maingi, Rajesh

2017-07-01

Linear stability analysis of the national spherical torus experiment (NSTX) Li-conditioned ELM-free H-mode equilibria is carried out in the context of the extended magneto-hydrodynamic (MHD) model in NIMROD. The purpose is to investigate the physical cause behind edge localized mode (ELM) suppression in experiment after the Li-coating of the divertor and the first wall of the NSTX tokamak. Besides ideal MHD modeling, including finite-Larmor radius effect and two-fluid Hall and electron diamagnetic drift contributions, a non-ideal resistivity model is employed, taking into account the increase of Z eff after Li-conditioning in ELM-free H-mode. Unlike an earlier conclusion from an eigenvalue code analysis of these equilibria, NIMROD results find that after reduced recycling from divertor plates, profile modification is necessary but insufficient to explain the mechanism behind complete ELMs suppression in ideal two-fluid MHD. After considering the higher plasma resistivity due to higher Z eff, the complete stabilization could be explained. A thorough analysis of both pre-lithium ELMy and with-lithium ELM-free cases using ideal and non-ideal MHD models is presented, after accurately including a vacuum-like cold halo region in NIMROD to investigate ELMs.

Physics of increased edge electron temperature and density turbulence during ELM-free QH-mode operation on DIII-D

Science.gov (United States)

Sung, C.; Rhodes, T. L.; Staebler, G. M.; Yan, Z.; McKee, G. R.; Smith, S. P.; Osborne, T. H.; Peebles, W. A.

2018-05-01

For the first time, we report increased edge electron temperature and density turbulence levels ( T˜ e and n˜ e) in Edge Localized Mode free Quiescent H-mode (ELM-free QH-mode) plasmas as compared to the ELMing time period. ELMs can severely damage plasma facing components in fusion plasma devices due to their large transient energy transport, making ELM-free operation a highly sought after goal. The QH-mode is a candidate for this goal as it is ELM-free for times limited only by hardware constraints. It is found that the driving gradients decrease during the QH-mode compared to the ELMing phase, however, a significant decrease in the ExB shearing rate is also observed that taken together is consistent with the increased turbulence. These results are significant as the prediction and control of ELM-free H-mode regimes are crucial for the operation of future fusion devices such as ITER. The changes in the linear growth rates calculated by CGYRO [Candy et al., J. Comput. Phys. 324, 73 (2016)] and the measured ExB shearing rate between ELMing and QH-mode phases are qualitatively consistent with these turbulence changes. Comparison with ELMing and 3D fields ELM suppressed H-mode finds a similar increase in T˜ e and n˜ e, however, with distinctly different origins, the increased driving gradients rather than the changes in the ExB shearing rate in 3D fields ELM suppressed the H-mode. However, linear gyrokinetic calculation results are generally consistent with the increased turbulence in both ELM-controlled discharges.

Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

Energy Technology Data Exchange (ETDEWEB)

Bell, Keaton J.; Winget, D. E.; Montgomery, M. H.; Castanheira, B. G.; Vanderbosch, Z.; Winget, K. I. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Gianninas, A.; Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Hermes, J. J. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Brown, Warren R., E-mail: keatonb@astro.as.utexas.edu [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States)

2017-02-01

We assess the photometric variability of nine stars with spectroscopic T {sub eff} and log g values from the ELM Survey that locates them near the empirical extremely low-mass (ELM) white dwarf instability strip. We discover three new pulsating stars: SDSS J135512.34+195645.4, SDSS J173521.69+213440.6, and SDSS J213907.42+222708.9. However, these are among the few ELM Survey objects that do not show radial velocity (RV) variations that confirm the binary nature expected of helium-core white dwarfs. The dominant 4.31 hr pulsation in SDSS J135512.34+195645.4 far exceeds the theoretical cut-off for surface reflection in a white dwarf, and this target is likely a high-amplitude δ Scuti pulsator with an overestimated surface gravity. We estimate the probability to be less than 0.0008 that the lack of measured RV variations in four of eight other pulsating candidate ELM white dwarfs could be due to low orbital inclination. Two other targets exhibit variability as photometric binaries. Partial coverage of the 19.342 hr orbit of WD J030818.19+514011.5 reveals deep eclipses that imply a primary radius >0.4 R {sub ⊙}—too large to be consistent with an ELM white dwarf. The only object for which our time series photometry adds support to ELM white dwarf classification is SDSS J105435.78−212155.9, which has consistent signatures of Doppler beaming and ellipsoidal variations. We conclude that the ELM Survey contains multiple false positives from another stellar population at T {sub eff}≲9000 K, possibly related to the sdA stars recently reported from SDSS spectra.

Pruning cycles and storm damage: are young American elms failing prematurely?

Science.gov (United States)

Chad P. Giblin

2017-01-01

The use of Dutch elm disease-resistant elms as a common replacement tree in municipal planting schedules has amassed a large population of these trees in many cities throughout the eastern half of the United States. Reports from practitioners have suggested that this population is vulnerable to catastrophic losses due to severe canopy failures during wind-loading...

Observation of different phases during an ELM crash with the help of nitrogen seeding

International Nuclear Information System (INIS)

Schneider, P A; Wolfrum, E; Dunne, M G.; Dux, R; Gude, A; Kurzan, B; Pütterich, T; Rathgeber, S K.; Weller, A; Wenninger, R; Vicente, J

2014-01-01

A new method was applied to indirectly obtain information about the features of the crash of the H-mode edge transport barrier in consequence of an edge localized mode (ELM). The method is based on a combination of fast measurements, without spatial resolution, and relatively slow measurements, with high spatial resolution. The comparison of two different ELM scenarios in the full metal tokamak ASDEX Upgrade—a standard scenario and one with additional nitrogen seeding—revealed a two-fold nature of the ELM crash. In the case with additional nitrogen only a part of the standard crash is observed. This suggests the standard ELM crash consists of two or more consecutive events instead of a single distinct one. Some of these events are observed to be suppressed with changes in plasma parameters. The effect of the impurity seeding on different plasma parameters is documented in detail and compared to measurements conducted in machines with a carbon wall. The radial extent of the phases observed during the ELM crash differs in the kinetic profiles, with one instability extending inside the pedestal top and the other being confined to the pedestal region. This picture can explain the differences in the loss of stored energy and the change in ELM frequency which are observed for the analysed pair of discharges. It also suggests that the ELM crash starts at the pedestal top and only then affects the steep gradient region. (paper)

The role of edge current-driven modes in ELM activity

Energy Technology Data Exchange (ETDEWEB)

Gimblett, C G; Hastie, R J; Helander, P [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom)

2006-10-15

We propose a model for edge localized mode (ELM) evolution which goes beyond linear stability arguments by hypothesizing that peeling modes initiate a Taylor relaxation (a constrained minimization of the magnetic energy) of an outer annular plasma region. The relaxation has two effects on peeling mode stability: (a) As the relaxation process proceeds radially inwards it leaves in its wake a Taylor state, which for conventional tokamak ordering is simply a flattened equilibrium toroidal current density. This effect acting in isolation would provide a destabilizing effect (for conventional current profiles the edge current density would increase); (b) The formation of a (negative for conventional current profiles) skin current at the plasma-vacuum interface which has a counteracting stabilizing effect on peeling modes. For a finite relaxed annulus, these two opposing effects can balance and give a configuration that is stable to all possible peeling instabilities. The radial extent of the relaxed region required for stability can be calculated using this balance. This then leads to model predictions for ELM characteristics such as the widths and mode numbers, the magnitude of the attendant energy losses and the natural (deterministic) scatter in these quantities. We compare these model predictions with a number of experimentally observed ELM properties. Further, expanding the governing equations gives analytic expressions for ELM widths in terms of localized edge parameters. Peeling modes can occur even when the critical pressure gradient for the onset of ballooning modes has not been reached. For this reason 'type III' ELMs, which typically occur just above the threshold for L-H transitions, may be best described by this model.

The role of edge current-driven modes in ELM activity

International Nuclear Information System (INIS)

Gimblett, C G; Hastie, R J; Helander, P

2006-01-01

We propose a model for edge localized mode (ELM) evolution which goes beyond linear stability arguments by hypothesizing that peeling modes initiate a Taylor relaxation (a constrained minimization of the magnetic energy) of an outer annular plasma region. The relaxation has two effects on peeling mode stability: (a) As the relaxation process proceeds radially inwards it leaves in its wake a Taylor state, which for conventional tokamak ordering is simply a flattened equilibrium toroidal current density. This effect acting in isolation would provide a destabilizing effect (for conventional current profiles the edge current density would increase); (b) The formation of a (negative for conventional current profiles) skin current at the plasma-vacuum interface which has a counteracting stabilizing effect on peeling modes. For a finite relaxed annulus, these two opposing effects can balance and give a configuration that is stable to all possible peeling instabilities. The radial extent of the relaxed region required for stability can be calculated using this balance. This then leads to model predictions for ELM characteristics such as the widths and mode numbers, the magnitude of the attendant energy losses and the natural (deterministic) scatter in these quantities. We compare these model predictions with a number of experimentally observed ELM properties. Further, expanding the governing equations gives analytic expressions for ELM widths in terms of localized edge parameters. Peeling modes can occur even when the critical pressure gradient for the onset of ballooning modes has not been reached. For this reason 'type III' ELMs, which typically occur just above the threshold for L-H transitions, may be best described by this model

Filament heater current modulation for increased filament lifetime

International Nuclear Information System (INIS)

Paul, J.D.; Williams, H.E. III.

1996-01-01

The surface conversion H-minus ion source employs two 60 mil tungsten filaments which are approximately 17 centimeters in length. These filaments are heated to approximately 2,800 degrees centigrade by 95--100 amperes of DC heater current. The arc is struck at a 120 hertz rate, for 800 microseconds and is generally run at 30 amperes peak current. Although sputtering is considered a contributing factor in the demise of the filament, evaporation is of greater concern. If the peak arc current can be maintained with less average heater current, the filament evaporation rate for this arc current will diminish. In the vacuum of an ion source, the authors expect the filaments to retain much of their heat throughout a 1 millisecond (12% duty) loss of heater current. A circuit to eliminate 100 ampere heater currents from filaments during the arc pulse was developed. The magnetic field due to the 100 ampere current tends to hold electrons to the filament, decreasing the arc current. By eliminating this magnetic field, the arc should be more efficient, allowing the filaments to run at a lower average heater current. This should extend the filament lifetime. The circuit development and preliminary filament results are discussed

ELMs and constraints on the H-mode pedestal: A model based on peeling-ballooning modes

International Nuclear Information System (INIS)

Snyder, P.B.

2002-01-01

Maximizing the pedestal height while maintaining acceptable ELMs is a key issue for optimizing tokamak performance. We present a model for ELMs and pedestal constraints based upon theoretical analysis of edge instabilities which can limit the pedestal height and drive ELMs. Sharp pedestal pressure gradients drive large bootstrap currents which play a complex dual role in the stability physics. Consequently, the dominant modes are often intermediate-n coupled 'peeling-ballooning' modes, driven both by current and the pressure gradient. A highly efficient new MHD code, ELITE, is used to study these modes, and calculate quantitative stability constraints on the pedestal, including direct constraints on the pedestal height. A model of various ELM types is developed, and quantitatively compared to data from several tokamaks. A number of observations agree with predictions, including ELM onset times, ELM depth, and variation in pedestal height with discharge shape. Projections of pedestal stability constraints for Next Step designs, and nonlinear simulations of peeling-ballooning modes using the BOUT code are also presented. (author)

Inter-ELM evolution of the edge current density profile on the ASDEX Upgrade tokamak

International Nuclear Information System (INIS)

Dunne, Michael G.

2014-01-01

The sudden decrease of plasma stored energy and subsequent power deposition on the first wall of a tokamak device due to edge localised modes (ELMs) is potentially detrimental to the success of a future fusion reactor. Understanding and control of ELMs is critical for the longevity of these devices and also to maximise their performance. The commonly accepted picture of ELMs posits a critical pressure gradient and current density in the plasma edge, above which coupled magnetohydrodynamic (MHD) peeling-ballooning modes are driven unstable. Much analysis has been presented in recent years on the spatial and temporal evolution of the edge pressure gradient. However, the edge current density has typically been overlooked due to the difficulties in measuring this quantity. In this thesis, a novel method of current density recovery is presented, using the equilibrium solver CLISTE to reconstruct a high resolution equilibrium utilising both external magnetic and internal edge kinetic data measured on the ASDEX Upgrade (AUG) tokamak. The evolution of the edge current density relative to an ELM crash is presented, showing that a resistive delay in the buildup of the current density is unlikely. An uncertainty analysis shows that the edge current density can be determined with an accuracy consistent with that of the kinetic data used. A comparison with neoclassical theory demonstrates excellent agreement between the current density determined by CLISTE and the calculated profiles. Three ELM mitigation regimes are investigated: Type-II ELMs, ELMs suppressed by external magnetic perturbations (MPs), and Nitrogen seeded ELMs. In the first two cases, the current density is found to decrease as mitigation onsets, indicating a more ballooning-like plasma behaviour. In the latter case, the flux surface averaged current density can decrease while the local current density increases, thus providing a mechanism to suppress both the peeling and ballooning modes.

Inter-ELM evolution of the edge current density profile on the ASDEX Upgrade tokamak

Energy Technology Data Exchange (ETDEWEB)

Dunne, Michael G.

2014-02-15

The sudden decrease of plasma stored energy and subsequent power deposition on the first wall of a tokamak device due to edge localised modes (ELMs) is potentially detrimental to the success of a future fusion reactor. Understanding and control of ELMs is critical for the longevity of these devices and also to maximise their performance. The commonly accepted picture of ELMs posits a critical pressure gradient and current density in the plasma edge, above which coupled magnetohydrodynamic (MHD) peeling-ballooning modes are driven unstable. Much analysis has been presented in recent years on the spatial and temporal evolution of the edge pressure gradient. However, the edge current density has typically been overlooked due to the difficulties in measuring this quantity. In this thesis, a novel method of current density recovery is presented, using the equilibrium solver CLISTE to reconstruct a high resolution equilibrium utilising both external magnetic and internal edge kinetic data measured on the ASDEX Upgrade (AUG) tokamak. The evolution of the edge current density relative to an ELM crash is presented, showing that a resistive delay in the buildup of the current density is unlikely. An uncertainty analysis shows that the edge current density can be determined with an accuracy consistent with that of the kinetic data used. A comparison with neoclassical theory demonstrates excellent agreement between the current density determined by CLISTE and the calculated profiles. Three ELM mitigation regimes are investigated: Type-II ELMs, ELMs suppressed by external magnetic perturbations (MPs), and Nitrogen seeded ELMs. In the first two cases, the current density is found to decrease as mitigation onsets, indicating a more ballooning-like plasma behaviour. In the latter case, the flux surface averaged current density can decrease while the local current density increases, thus providing a mechanism to suppress both the peeling and ballooning modes.

Laser-filament-induced snow formation in a subsaturated zone in a cloud chamber: experimental and theoretical study.

Science.gov (United States)

Ju, Jingjing; Sun, Haiyi; Sridharan, Aravindan; Wang, Tie-Jun; Wang, Cheng; Liu, Jiansheng; Li, Ruxin; Xu, Zhizhan; Chin, See Leang

2013-12-01

1 kHz, 2 mJ, 45 fs, 800 nm laser pulses were fired into a laboratory diffusion cloud chamber through a subsaturated zone (relative humidity ∼73%, T ∼ 4.3 °C). After 60 min of laser irradiation, an oval-shaped snow pile was observed right below the filament center and weighed ∼12.0 mg. The air current velocity at the edge of the vortices was estimated to be ∼16.5 cm/s. Scattering scenes recorded from the side show that filament-induced turbulence were formed inside the cloud chamber with two vortices below the filament. Two-dimensional simulations of the air flow motion in two cross sections of the cloud chamber confirm that the turbulent vortices exist below the filament. Based upon this simulation, we deduce that the vortices indeed have a three-dimensional elliptical shape. Hence, we propose that inside vortices where the humidity was supersaturated or saturated the condensation nuclei, namely, HNO(3), N(2)(+), O(2)(+) and other aerosols and impurities, were activated and grew in size. Large-sized particles would eventually be spun out along the fast moving direction towards the cold plate and formed an oval-shaped snow pile at the end.

H/He irradiation on tungsten exposed to ELM-like thermal shocks

International Nuclear Information System (INIS)

Lemahieu, Nathan; Balden, Martin; Elgeti, Stefan; Greuner, Henri; Linke, Jochen; Maier, Hans; Pintsuk, Gerald; Wirtz, Marius; Van Oost, Guido; Noterdaeme, Jean-Marie

2016-01-01

Highlights: • After ELM-like thermal shocks, tungsten was exposed to H/He particle fluxes. • The influence of combined loading conditions on the damage behaviour was studied. • Roughened surfaces do not alter H/He induced surface modifications. • Cracks interact with the particle flux, resulting in phenomena such as crack bridging. - Abstract: ELM-like thermal shocks and H/He particle exposure were subsequently applied on tungsten samples. Polished test specimens underwent in the JUDITH 1 electron beam facility 100 transient thermal events with a duration of 1 ms. The absorbed heat flux was 0.4 GW m"−"2 and 1.5 GW m"−"2, which is above the material's damage threshold. These experiments were done at room temperature and with the samples heated to 400 °C base temperature. Depending on the loading conditions the test specimens have either a crack network or showed surface roughening. The samples were then loaded in the GLADIS facility at different surface temperatures with a mixed H/He beam with a flux of 3.7 × 10"2"1 m"−"2 s"−"1. Post-mortem analysis showed that the roughened surface did not alter the H/He induced surface modifications. In contrast to that on the test specimens that exhibited crack formation, phenomena such as bubble creation along the crack edge, formation of a shallow layer of nano-structures covering the crack opening, and the emerging of a porous structure which partially fills the crack are observed.

H/He irradiation on tungsten exposed to ELM-like thermal shocks

Energy Technology Data Exchange (ETDEWEB)

Lemahieu, Nathan, E-mail: Nathan.Lemahieu@UGent.be [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Institute of Interfacial Process Engineering and Plasma Technology IGVP, Universität Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Balden, Martin; Elgeti, Stefan; Greuner, Henri [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Linke, Jochen [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Maier, Hans [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Pintsuk, Gerald; Wirtz, Marius [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Van Oost, Guido [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Noterdaeme, Jean-Marie [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium)

2016-11-01

Highlights: • After ELM-like thermal shocks, tungsten was exposed to H/He particle fluxes. • The influence of combined loading conditions on the damage behaviour was studied. • Roughened surfaces do not alter H/He induced surface modifications. • Cracks interact with the particle flux, resulting in phenomena such as crack bridging. - Abstract: ELM-like thermal shocks and H/He particle exposure were subsequently applied on tungsten samples. Polished test specimens underwent in the JUDITH 1 electron beam facility 100 transient thermal events with a duration of 1 ms. The absorbed heat flux was 0.4 GW m{sup −2} and 1.5 GW m{sup −2}, which is above the material's damage threshold. These experiments were done at room temperature and with the samples heated to 400 °C base temperature. Depending on the loading conditions the test specimens have either a crack network or showed surface roughening. The samples were then loaded in the GLADIS facility at different surface temperatures with a mixed H/He beam with a flux of 3.7 × 10{sup 21} m{sup −2} s{sup −1}. Post-mortem analysis showed that the roughened surface did not alter the H/He induced surface modifications. In contrast to that on the test specimens that exhibited crack formation, phenomena such as bubble creation along the crack edge, formation of a shallow layer of nano-structures covering the crack opening, and the emerging of a porous structure which partially fills the crack are observed.

Optical spectroscopy using gas-phase femtosecond laser filamentation.

Science.gov (United States)

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

Energy saving and prediction modeling of petrochemical industries: A novel ELM based on FAHP

International Nuclear Information System (INIS)

Geng, ZhiQiang; Qin, Lin; Han, YongMing; Zhu, QunXiong

2017-01-01

Extreme learning machine (ELM), which is a simple single-hidden-layer feed-forward neural network with fast implementation, has been widely applied in many engineering fields. However, it is difficult to enhance the modeling ability of extreme learning in disposing the high-dimensional noisy data. And the predictive modeling method based on the ELM integrated fuzzy C-Means integrating analytic hierarchy process (FAHP) (FAHP-ELM) is proposed. The fuzzy C-Means algorithm is used to cluster the input attributes of the high-dimensional data. The Analytic Hierarchy Process (AHP) based on the entropy weights is proposed to filter the redundant information and extracts characteristic components. Then, the fusion data is used as the input of the ELM. Compared with the back-propagation (BP) neural network and the ELM, the proposed model has better performance in terms of the speed of convergence, generalization and modeling accuracy based on University of California Irvine (UCI) benchmark datasets. Finally, the proposed method was applied to build the energy saving and predictive model of the purified terephthalic acid (PTA) solvent system and the ethylene production system. The experimental results demonstrated the validity of the proposed method. Meanwhile, it could enhance the efficiency of energy utilization and achieve energy conservation and emission reduction. - Highlights: • The ELM integrated FAHP approach is proposed. • The FAHP-ELM prediction model is effectively verified through UCI datasets. • The energy saving and prediction model of petrochemical industries is obtained. • The method is efficient in improvement of energy efficiency and emission reduction.

Were the chaotic ELMs in TCV the result of an ARMA process?

International Nuclear Information System (INIS)

Degeling, A W; Lister, J B; Martin, Y R; Zvejnieks, G

2004-01-01

The results of a previous paper claiming the demonstration that edge localized mode (ELM) dynamics on TCV are chaotic in a number of cases has recently been called into question, because the statistical test employed was found to also identify linear auto regressive-moving average (ARMA) models as chaotic. The TCV ELM data has therefore been re-examined with an improved method that is able to make this distinction, and the ARMA model is found to be an inappropriate description of the dynamics on TCV. The hypothesis that ELM dynamics are chaotic on TCV in a number of cases is therefore still favoured. (letter to the editor)

Pressure injection of methyl 2-benzimidazole carbamate hydrochloride solution as a control for Dutch elm disease

Science.gov (United States)

Garold F. Gregory; Thomas W. Jones

1973-01-01

A preliminary evaluation of the effectiveness of injecting methyl 2-benzimidazole carbamate hydrochloride solution into elms for prevention or cure of Dutch elm disease is reported. Symptom development was diminished or prevented in elms injected with fungicide before inoculation. Symptom development was arrested in all crown-inoculated diseased trees injected with the...

Unambiguous Evidence of Filament Splitting-induced Partial Eruptions

Science.gov (United States)

Cheng, X.; Kliem, B.; Ding, M. D.

2018-03-01

Coronal mass ejections are often considered to result from the full eruption of a magnetic flux rope (MFR). However, it is recognized that, in some events, the MFR may release only part of its flux, with the details of the implied splitting not completely established due to limitations in observations. Here, we investigate two partial eruption events including a confined and a successful one. Both partial eruptions are a consequence of the vertical splitting of a filament-hosting MFR involving internal reconnection. A loss of equilibrium in the rising part of the magnetic flux is suggested by the impulsive onset of both events and by the delayed onset of reconnection in the confined event. The remaining part of the flux might be line-tied to the photosphere in a bald patch (BP) separatrix surface, and we confirm the existence of extended BP sections for the successful eruption. The internal reconnection is signified by brightenings in the body of one filament and between the rising and remaining parts of both filaments. It evolves quickly into the standard current sheet reconnection in the wake of the eruption. As a result, regardless of being confined or successful, both eruptions produce hard X-ray sources and flare loops below the erupting but above the surviving flux, as well as a pair of flare ribbons enclosing the latter.

ELM suppression in low edge collisionality H-mode discharges using n = 3 magnetic perturbations

Energy Technology Data Exchange (ETDEWEB)

Burrell, K H [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Evans, T E [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Doyle, E J [University of California, Los Angeles, California (United States); Fenstermacher, M E [Lawrence Livermore National Laboratory, Livermore, California (United States); Groebner, R J [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Leonard, A W [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Moyer, R A [University of California, San Diego, California (United States); Osborne, T H; Schaffer, M J; Snyder, P B [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Thomas, P R [CEA Cadarache EURATOM Association, Cadarache (France); West, W P [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Boedo, J A [University of California, San Diego, California (United States); Garofalo, A M [Columbia University, New York, New York (United States); Gohil, P; Jackson, G L; La Haye, R J [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Lasnier, C J [Lawrence Livermore National Laboratory, Livermore, California (United States); Reimerdes, H [Columbia University, New York, New York (United States); Rhodes, T L [University of California, Los Angeles, California (United States); Scoville, J T [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Solomon, W M [Princeton Plasma Physics Laboratory, Princeton, New Jersey (United States); Thomas, D M [General Atomics, PO Box 85608, San Diego, CA 92186-9784 (United States); Wang, G [University of California, Los Angeles, California (United States); Watkins, J G [Sandia National Laboratories, Albuquerque, New Mexico (United States); Zeng, L [University of California, Los Angeles, California (United States)

2005-12-15

Using resonant magnetic perturbations with toroidal mode number n = 3, we have produced H-mode discharges without edge localized modes (ELMs) which run with constant density and radiated power for periods up to about 2550 ms (17 energy confinement times). These ELM suppression results are achieved at pedestal collisionalities close to those desired for next step burning plasma experiments such as ITER and provide a means of eliminating the rapid erosion of divertor components in such machines which could be caused by giant ELMs. The ELM suppression is due to an enhancement in the edge particle transport which reduces pedestal current density and maximum edge pressure gradient below the threshold for peeling-ballooning modes. These n = 3 magnetic perturbations provide a means of active control of edge plasma transport.

ELM suppression in low edge collisionality H-mode discharges using n = 3 magnetic perturbations

International Nuclear Information System (INIS)

Burrell, K H; Evans, T E; Doyle, E J; Fenstermacher, M E; Groebner, R J; Leonard, A W; Moyer, R A; Osborne, T H; Schaffer, M J; Snyder, P B; Thomas, P R; West, W P; Boedo, J A; Garofalo, A M; Gohil, P; Jackson, G L; La Haye, R J; Lasnier, C J; Reimerdes, H; Rhodes, T L; Scoville, J T; Solomon, W M; Thomas, D M; Wang, G; Watkins, J G; Zeng, L

2005-01-01

Using resonant magnetic perturbations with toroidal mode number n = 3, we have produced H-mode discharges without edge localized modes (ELMs) which run with constant density and radiated power for periods up to about 2550 ms (17 energy confinement times). These ELM suppression results are achieved at pedestal collisionalities close to those desired for next step burning plasma experiments such as ITER and provide a means of eliminating the rapid erosion of divertor components in such machines which could be caused by giant ELMs. The ELM suppression is due to an enhancement in the edge particle transport which reduces pedestal current density and maximum edge pressure gradient below the threshold for peeling-ballooning modes. These n = 3 magnetic perturbations provide a means of active control of edge plasma transport

Nonlinear evolution of the mode structure of ELMs in realistic ASDEX Upgrade geometry

Energy Technology Data Exchange (ETDEWEB)

Krebs, Isabel; Hoelzl, Matthias; Lackner, Karl; Guenter, Sibylle [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, Garching (Germany); Collaboration: The ASDEX Upgrade Team

2013-07-01

Edge-localized modes (ELMs) are edge instabilities in H-mode plasmas, which eject particles and energy. The suitability of the H-mode for future fusion reactors depends crucially on the exact ELM dynamics as they can damage plasma facing components if too large. We have simulated ELMs in ASDEX Upgrade geometry using the nonlinear MHD code JOREK. Emphasis was put on the mode structure evolution in the early ELM phase which is characterized by the exponential growth of the unstable toroidal Fourier harmonics followed by a phase of saturation. In the linear phase, toroidal harmonics grow independently, whereas at larger amplitudes, the nonlinear interaction between the toroidal harmonics influences their growth and structure. Prior to mode saturation, the evolution of the mode structure can be reproduced well by a simple quadratic mode-interaction model, which yields a possible explanation for the strong n=1 component of type-I ELMs observed in ASDEX Upgrade. In the linear phase of the simulations, intermediate toroidal mode numbers (n 6-14) are most unstable as predicted by the peeling-ballooning model. But non-linearly, the n=1 component becomes important due to an energy transfer from pairs of linearly dominant toroidal harmonics with neighboring mode numbers to the n=1. The latter thereby changes its spatial structure.

ELM - A SIMPLE TOOL FOR THERMAL-HYDRAULIC ANALYSIS OF SOLID-CORE NUCLEAR ROCKET FUEL ELEMENTS

Science.gov (United States)

Walton, J. T.

1994-01-01

ELM is a simple computational tool for modeling the steady-state thermal-hydraulics of propellant flow through fuel element coolant channels in nuclear thermal rockets. Written for the nuclear propulsion project of the Space Exploration Initiative, ELM evaluates the various heat transfer coefficient and friction factor correlations available for turbulent pipe flow with heat addition. In the past, these correlations were found in different reactor analysis codes, but now comparisons are possible within one program. The logic of ELM is based on the one-dimensional conservation of energy in combination with Newton's Law of Cooling to determine the bulk flow temperature and the wall temperature across a control volume. Since the control volume is an incremental length of tube, the corresponding pressure drop is determined by application of the Law of Conservation of Momentum. The size, speed, and accuracy of ELM make it a simple tool for use in fuel element parametric studies. ELM is a machine independent program written in FORTRAN 77. It has been successfully compiled on an IBM PC compatible running MS-DOS using Lahey FORTRAN 77, a DEC VAX series computer running VMS, and a Sun4 series computer running SunOS UNIX. ELM requires 565K of RAM under SunOS 4.1, 360K of RAM under VMS 5.4, and 406K of RAM under MS-DOS. Because this program is machine independent, no executable is provided on the distribution media. The standard distribution medium for ELM is one 5.25 inch 360K MS-DOS format diskette. ELM was developed in 1991. DEC, VAX, and VMS are trademarks of Digital Equipment Corporation. Sun4 and SunOS are trademarks of Sun Microsystems, Inc. IBM PC is a registered trademark of International Business Machines. MS-DOS is a registered trademark of Microsoft Corporation.

Post-filament self-trapping of ultrashort laser pulses.

Science.gov (United States)

Mitrofanov, A V; Voronin, A A; Sidorov-Biryukov, D A; Andriukaitis, G; Flöry, T; Pugžlys, A; Fedotov, A B; Mikhailova, J M; Panchenko, V Ya; Baltuška, A; Zheltikov, A M

2014-08-15

Laser filamentation is understood to be self-channeling of intense ultrashort laser pulses achieved when the self-focusing because of the Kerr nonlinearity is balanced by ionization-induced defocusing. Here, we show that, right behind the ionized region of a laser filament, ultrashort laser pulses can couple into a much longer light channel, where a stable self-guiding spatial mode is sustained by the saturable self-focusing nonlinearity. In the limiting regime of negligibly low ionization, this post-filamentation beam dynamics converges to a large-scale beam self-trapping scenario known since the pioneering work on saturable self-focusing nonlinearities.

Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade

International Nuclear Information System (INIS)

Krieger, K; Sieglin, B; Balden, M; De Marne, P; Nille, D; Rohde, V; Faitsch, M; Giannone, L; Herrmann, A; Coenen, J W; Göths, B; Laggner, F; Matthews, G F; Dejarnac, R; Horacek, J; Komm, M; Pitts, R A; Ratynskaia, S; Thoren, E; Tolias, P

2017-01-01

Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in the tokamak experiment ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the Divertor Manipulator II system. The exposed sample was designed with an elevated sloped surface inclined against the incident magnetic field to increase the projected parallel power flux to a level were transient melting by ELMs would occur. Sample exposure was controlled by moving the outer strike point to the sample location. As extension to previous melt studies in the new experiment both the current flow from the sample to vessel potential and the local surface temperature were measured with sufficient time resolution to resolve individual ELMs. The experiment provided for the first time a direct link of current flow and surface temperature during transient ELM events. This allows to further constrain the MEMOS melt motion code predictions and to improve the validation of its underlying model assumptions. Post exposure ex situ analysis of the retrieved samples confirms the decreased melt motion observed at shallower magnetic field line to surface angles compared to that at leading edges exposed to the parallel power flux. (paper)

Divertor power and particle fluxes between and during type-I ELMs in the ASDEX Upgrade

Science.gov (United States)

Kallenbach, A.; Dux, R.; Eich, T.; Fischer, R.; Giannone, L.; Harhausen, J.; Herrmann, A.; Müller, H. W.; Pautasso, G.; Wischmeier, M.; ASDEX Upgrade Team

2008-08-01

Particle, electric charge and power fluxes for type-I ELMy H-modes are measured in the divertor of the ASDEX Upgrade tokamak by triple Langmuir probes, shunts, infrared (IR) thermography and spectroscopy. The discharges are in the medium to high density range, resulting in predominantly convective edge localized modes (ELMs) with moderate fractional stored energy losses of 2% or below. Time resolved data over ELM cycles are obtained by coherent averaging of typically one hundred similar ELMs, spatial profiles from the flush-mounted Langmuir probes are obtained by strike point sweeps. The application of simple physics models is used to compare different diagnostics and to make consistency checks, e.g. the standard sheath model applied to the Langmuir probes yields power fluxes which are compared with the thermographic measurements. In between ELMs, Langmuir probe and thermography power loads appear consistent in the outer divertor, taking into account additional load due to radiation and charge exchange neutrals measured by thermography. The inner divertor is completely detached and no significant power flow by charged particles is measured. During ELMs, quite similar power flux profiles are found in the outer divertor by thermography and probes, albeit larger uncertainties in Langmuir probe evaluation during ELMs have to be taken into account. In the inner divertor, ELM power fluxes from thermography are a factor 10 larger than those derived from probes using the standard sheath model. This deviation is too large to be caused by deficiencies of probe analysis. The total ELM energy deposition from IR is about a factor 2 higher in the inner divertor compared with the outer divertor. Spectroscopic measurements suggest a quite moderate contribution of radiation to the target power load. Shunt measurements reveal a significant positive charge flow into the inner target during ELMs. The net number of elementary charges correlates well with the total core particle loss

Characterizations of power loads on divertor targets for type-I, compound and small ELMs in the EAST superconducting tokamak

DEFF Research Database (Denmark)

Wang, L.; Xu, G.S.; Guo, H.Y.

2013-01-01

-III ELMy H-modes. The energy loss and divertor power load are systematically characterized for these different ELMy H-modes to provide a physics basis for the next-step high-power long-pulse operations in EAST. Both type-I and compound ELMs exhibit good confinement (H98(y,2) ∼ 1). A significant loss......The Experimental Advanced Superconducting Tokamak (EAST) has recently achieved a variety of H-mode regimes with different edge-localized mode (ELM) dynamics, including type-I ELMs, compound ELMs, which are manifested by the onset of a large spike followed by a sequence of small spikes on Dα......-III ELMs. It is remarkable that the new very small ELMy H-modes exhibit even lower target power deposition than type-III ELMs, with the peak heat flux generally below 1 MW m−2. These very small ELMs are usually accompanied by broadband fluctuations with frequencies ranging from 20 to 50 kHz, which may...

Investigations on the edge kinetic data in regimes with type-I and mitigated ELMs at ASDEX Upgrade

International Nuclear Information System (INIS)

Rathgeber, S.K.; Barrera, L.; Birkenmeier, G.; Fischer, R.; Suttrop, W.

2014-01-01

The behaviour of profiles and gradients of electron density, temperature and pressure at the edge of ASDEX Upgrade was studied in regimes with type-I and small edge localized modes (ELMs) of discharges with and without applied magnetic perturbations (MPs). Estimation of the edge kinetic parameters was performed by means of integrated data analysis for joint reconstruction of electron density and temperature profiles via combination of data from different diagnostics. The MP fields for ELM mitigation were produced by 16 in-vessel coils allowing to execute this survey with large variations in poloidal spectrum and resonant component of the error field. With several dedicated discharges the effect of MPs on the edge kinetic data and ELMs was determined in dependence of heating power, gas puff and MP-coil configuration. Small ELMs are dominant—with and without MPs—in regimes with reduced pedestal top electron temperatures and flattened edge electron pressure gradients compared to type-I ELM phases. Furthermore, application of MPs opens an additional small ELM regime in the high temperature range at reduced electron pressure gradient. (paper)

Quasineutral plasma expansion into infinite vacuum as a model for parallel ELM transport

Science.gov (United States)

Moulton, D.; Ghendrih, Ph; Fundamenski, W.; Manfredi, G.; Tskhakaya, D.

2013-08-01

An analytic solution for the expansion of a plasma into vacuum is assessed for its relevance to the parallel transport of edge localized mode (ELM) filaments along field lines. This solution solves the 1D1V Vlasov-Poisson equations for the adiabatic (instantaneous source), collisionless expansion of a Gaussian plasma bunch into an infinite space in the quasineutral limit. The quasineutral assumption is found to hold as long as λD0/σ0 ≲ 0.01 (where λD0 is the initial Debye length at peak density and σ0 is the parallel length of the Gaussian filament), a condition that is physically realistic. The inclusion of a boundary at x = L and consequent formation of a target sheath is found to have a negligible effect when L/σ0 ≳ 5, a condition that is physically plausible. Under the same condition, the target flux densities predicted by the analytic solution are well approximated by the ‘free-streaming’ equations used in previous experimental studies, strengthening the notion that these simple equations are physically reasonable. Importantly, the analytic solution predicts a zero heat flux density so that a fluid approach to the problem can be used equally well, at least when the source is instantaneous. It is found that, even for JET-like pedestal parameters, collisions can affect the expansion dynamics via electron temperature isotropization, although this is probably a secondary effect. Finally, the effect of a finite duration, τsrc, for the plasma source is investigated. As is found for an instantaneous source, when L/σ0 ≳ 5 the presence of a target sheath has a negligible effect, at least up to the explored range of τsrc = L/cs (where cs is the sound speed at the initial temperature).

Effects of ELMs and disruptions on ITER divertor armour materials

Science.gov (United States)

Federici, G.; Zhitlukhin, A.; Arkhipov, N.; Giniyatulin, R.; Klimov, N.; Landman, I.; Podkovyrov, V.; Safronov, V.; Loarte, A.; Merola, M.

2005-03-01

This paper describes the response of plasma facing components manufactured with tungsten (macro-brush) and CFC to energy loads characteristic of Type I ELMs and disruptions in ITER, in experiments conducted (under an EU/RF collaboration) in two plasma guns (QSPA and MK-200UG) at the TRINITI institute. Targets were exposed to a series of repetitive pulses in QSPA with heat loads in a range of 1-2 MJ/m 2 lasting 0.5 ms. Moderate tungsten erosion, of less than 0.2 μm per pulse, was found for loads of ˜1.5 MJ/m 2, consistent with ELM erosion being determined by tungsten evaporation and not by melt layer displacement. At energy densities of ˜1.8 MJ/m 2 a sharp growth of tungsten erosion was measured together with intense droplet ejection. MK-200UG experiments were focused on studying mainly vapor plasma production and impurity transport during ELMs. The conditions for removal of thin metal deposits from a carbon substrate were characterized.

Effects of ELMs and disruptions on ITER divertor armour materials

International Nuclear Information System (INIS)

Federici, G.; Zhitlukhin, A.; Arkhipov, N.; Giniyatulin, R.; Klimov, N.; Landman, I.; Podkovyrov, V.; Safronov, V.; Loarte, A.; Merola, M.

2005-01-01

This paper describes the response of plasma facing components manufactured with tungsten (macro-brush) and CFC to energy loads characteristic of Type I ELMs and disruptions in ITER, in experiments conducted (under an EU/RF collaboration) in two plasma guns (QSPA and MK-200UG) at the TRINITI institute. Targets were exposed to a series of repetitive pulses in QSPA with heat loads in a range of 1-2 MJ/m 2 lasting 0.5 ms. Moderate tungsten erosion, of less than 0.2 μm per pulse, was found for loads of ∼1.5 MJ/m 2 , consistent with ELM erosion being determined by tungsten evaporation and not by melt layer displacement. At energy densities of ∼1.8 MJ/m 2 a sharp growth of tungsten erosion was measured together with intense droplet ejection. MK-200UG experiments were focused on studying mainly vapor plasma production and impurity transport during ELMs. The conditions for removal of thin metal deposits from a carbon substrate were characterized

Mechanical response of melt-spun amorphous filaments

International Nuclear Information System (INIS)

Leal, A A; Reifler, F A; Hufenus, R; Mohanty, G; Michler, J

2014-01-01

High-speed melt spinning of a cyclo-olefin polymer (COP) and a copolyamide (CoPA) have been performed. Differential scanning calorimetry curves of the resulting monofilaments show that they remain in an amorphous state even after hot drawing. Wide angle x-ray diffraction patterns of undrawn and drawn COP filaments show that although the material remains in an amorphous state, a degree of orientation is induced in the polymer after drawing. The amorphous filaments show an enhanced bending recovery with respect to different semi-crystalline monofilaments commercially available. However, single fiber axial compressive testing indicates that the amorphous filaments exhibit a compressive modulus value which is 50% lower than what is observed for a reference semi-crystalline PET filament. Analysis of the compressive strains applied by the bending recovery test indicates that while the maximum applied strains remain well within the region of elastic deformation of the amorphous materials, the threshold between elastic and plastic deformation is reached for the semi-crystalline materials. (paper)

Using ELM-based weighted probabilistic model in the classification of synchronous EEG BCI.

Science.gov (United States)

Tan, Ping; Tan, Guan-Zheng; Cai, Zi-Xing; Sa, Wei-Ping; Zou, Yi-Qun

2017-01-01

Extreme learning machine (ELM) is an effective machine learning technique with simple theory and fast implementation, which has gained increasing interest from various research fields recently. A new method that combines ELM with probabilistic model method is proposed in this paper to classify the electroencephalography (EEG) signals in synchronous brain-computer interface (BCI) system. In the proposed method, the softmax function is used to convert the ELM output to classification probability. The Chernoff error bound, deduced from the Bayesian probabilistic model in the training process, is adopted as the weight to take the discriminant process. Since the proposed method makes use of the knowledge from all preceding training datasets, its discriminating performance improves accumulatively. In the test experiments based on the datasets from BCI competitions, the proposed method is compared with other classification methods, including the linear discriminant analysis, support vector machine, ELM and weighted probabilistic model methods. For comparison, the mutual information, classification accuracy and information transfer rate are considered as the evaluation indicators for these classifiers. The results demonstrate that our method shows competitive performance against other methods.

Effect of ELMs on rotation and momentum confinement in H-mode discharges in JET

NARCIS (Netherlands)

Versloot, T.W.; de Vries, P.C.; Giroud, C.; Hua, M.D.; Beurskens, M.N.A.; Brix, M.; Eich, T.; Luna, de la E.; Tala, T.; Naulin, V.; Zastrov, K.D.

2010-01-01

The loss of plasma toroidal angular momentum and thermal energy by edge localized modes (ELMs) has been studied in JET. The analysis shows a consistently larger drop in momentum in comparison with the energy loss associated with the ELMs. This difference originates from the large reduction in

ELM triggering conditions for the integrated modeling of H-mode plasmas

International Nuclear Information System (INIS)

Pankin, A.Y.; Schnack, D.D.; Bateman, G.; Kritz, A.H.; Brennan, D.P.; Snyder, P.B.; Voitsekhovitch, I.; Kruger, S.; Janeschitz, G.; Onjun, T.; Pacher, G.W.; Pacher, H.D.

2004-01-01

Recent advances in the integrated modeling of ELMy (edge localized mode) H-mode plasmas are presented. A model for the H-mode pedestal and for the triggering of ELMs predicts the height, width, and shape of the H-mode pedestal and the frequency and width of ELMs. Formation of the pedestal and the L-H transition is the direct result of E r x B flow shear suppression of anomalous transport. The periodic ELM crashes are triggered by either the ballooning or peeling MHD instabilities. The BALOO, DCON, and ELITE ideal MHD stability codes are used to derive a new parametric expression for the peeling-ballooning threshold. The new dependence for the peeling-ballooning threshold is implemented in the ASTRA transport code. Results of integrated modeling of DIII-D like discharges are presented and compared with experimental observations. The results from the ideal MHD stability codes are compared with results from the resistive MHD stability code NIMROD. (authors)

ELMs and constraints on the H-mode pedestal: A model based on peeling-ballooning modes

International Nuclear Information System (INIS)

Snyder, P.B.; Ferron, J.R.; Wilson, H.R.

2003-01-01

We propose a model for Edge Localized Modes (ELMs) and pedestal constraint based upon theoretical analysis of instabilities which can limit the pedestal height and drive ELMs. The sharp pressure gradients, and resulting bootstrap current, in the pedestal region provide free energy to drive peeling and ballooning modes. The interaction of peeling-ballooning coupling, ballooning mode second stability, and finite-Larmor-radius effects results in coupled peeling-ballooning modes of intermediate wavelength generally being the limiting instability. A highly efficient new MHD code, ELITE, is used to calculate quantitative stability constraints on the pedestal, including con straits on the pedestal height. Because of the impact of collisionality on the bootstrap current, these pedestal constraints are dependant on the density and temperature separately, rather than simply on the pressure. A model of various ELM types is developed, and quantitatively compared to data. A number of observations agree with predictions, including ELM onset times, ELM depth and variation in pedestal height with collisionality and discharge shape. Stability analysis of series of model equilibria are used both o predict and interpret pedestal trends in existing experiments and to project pedestal constraints for future burning plasma tokamak designs. (author)

Synergistic effects of ELMs and steady state H and H/He irradiation on tungsten

International Nuclear Information System (INIS)

Lemahieu, Nathan; Greuner, Henri; Linke, Jochen; Maier, Hans; Pintsuk, Gerald; Van Oost, Guido; Wirtz, Marius

2015-01-01

Highlights: • Tungsten was first exposed to H or H/He fluxes and then to ELM-like transients. • The influence of particle exposure on the thermal shock behaviour was studied. • There was no deterioration of thermal shock behaviour compared to reference material. • Some combinations of loading conditions resulted in an improved material behaviour. - Abstract: To investigate synergistic effects of high heat flux loading on H and H/He loaded tungsten surfaces, specimens were exposed to a 30 keV steady-state H or H/He beam and subsequently loaded with an electron beam to simulate ELMs. The heat flux during the H and H/He loading was 10.5 MW m"−"2, while a 2 × 10"2"5 m"−"2 fluence was reached. After exposure, all specimens exhibited an altered surface morphology. The H/He samples with a surface temperature of 1000 °C and 1500 °C had a multitude of surface extrusions. Afterwards the particle loaded samples were exposed to 100 ELM-like pulses around the material's damage threshold. Transient heat fluxes of 190 MW m"−"2 and 380 MW m"−"2 were applied at room temperature and 400 °C for a duration of 1 ms. Post-mortem analysis showed no deterioration of thermal shock resistance in comparison with polished material. For some tests the reference specimens roughened or cracked while the H or H/He exposed material had no damage. The H-content and the H/He-induced cavities and/or extrusions are suggested as two potential causes for this change in material behaviour.

Synergistic effects of ELMs and steady state H and H/He irradiation on tungsten

Energy Technology Data Exchange (ETDEWEB)

Lemahieu, Nathan, E-mail: n.lemahieu@fz-juelich.de [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Institute of Interfacial Process Engineering and Plasma Technology IGVP, Universität Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Greuner, Henri [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Linke, Jochen [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Maier, Hans [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Pintsuk, Gerald [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany); Van Oost, Guido [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Wirtz, Marius [Institute for Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich (Germany)

2015-10-15

Highlights: • Tungsten was first exposed to H or H/He fluxes and then to ELM-like transients. • The influence of particle exposure on the thermal shock behaviour was studied. • There was no deterioration of thermal shock behaviour compared to reference material. • Some combinations of loading conditions resulted in an improved material behaviour. - Abstract: To investigate synergistic effects of high heat flux loading on H and H/He loaded tungsten surfaces, specimens were exposed to a 30 keV steady-state H or H/He beam and subsequently loaded with an electron beam to simulate ELMs. The heat flux during the H and H/He loading was 10.5 MW m{sup −2}, while a 2 × 10{sup 25} m{sup −2} fluence was reached. After exposure, all specimens exhibited an altered surface morphology. The H/He samples with a surface temperature of 1000 °C and 1500 °C had a multitude of surface extrusions. Afterwards the particle loaded samples were exposed to 100 ELM-like pulses around the material's damage threshold. Transient heat fluxes of 190 MW m{sup −2} and 380 MW m{sup −2} were applied at room temperature and 400 °C for a duration of 1 ms. Post-mortem analysis showed no deterioration of thermal shock resistance in comparison with polished material. For some tests the reference specimens roughened or cracked while the H or H/He exposed material had no damage. The H-content and the H/He-induced cavities and/or extrusions are suggested as two potential causes for this change in material behaviour.

Particle and power deposition on divertor targets in EAST H-mode plasmas

International Nuclear Information System (INIS)

Wang, L.; Xu, G.S.; Guo, H.Y.; Chen, R.; Ding, S.; Gan, K.F.; Gao, X.; Gong, X.Z.; Jiang, M.; Liu, P.; Liu, S.C.; Luo, G.N.; Ming, T.F.; Wan, B.N.; Wang, D.S.; Wang, F.M.; Wang, H.Q.; Wu, Z.W.; Yan, N.; Zhang, L.

2012-01-01

The effects of edge-localized modes (ELMs) on divertor particle and heat fluxes were investigated for the first time in the Experimental Advanced Superconducting Tokamak (EAST). The experiments were carried out with both double null and lower single null divertor configurations, and comparisons were made between the H-mode plasmas with lower hybrid current drive (LHCD) and those with combined ion cyclotron resonance heating (ICRH). The particle and heat flux profiles between and during ELMs were obtained from Langmuir triple-probe arrays embedded in the divertor target plates. And isolated ELMs were chosen for analysis in order to reduce the uncertainty resulting from the influence of fast electrons on Langmuir triple-probe evaluation during ELMs. The power deposition obtained from Langmuir triple probes was consistent with that from the divertor infra-red camera during an ELM-free period. It was demonstrated that ELM-induced radial transport predominantly originated from the low-field side region, in good agreement with the ballooning-like transport model and experimental results of other tokamaks. ELMs significantly enhanced the divertor particle and heat fluxes, without significantly broadening the SOL width and plasma-wetted area on the divertor target in both LHCD and LHCD + ICRH H-modes, thus posing a great challenge for the next-step high-power, long-pulse operation in EAST. Increasing the divertor-wetted area was also observed to reduce the peak heat flux and particle recycling at the divertor target, hence facilitating long-pulse H-mode operation. The particle and heat flux profiles during ELMs appeared to exhibit multiple peak structures, and were analysed in terms of the behaviour of ELM filaments and the flux tubes induced by modified magnetic topology during ELMs. (paper)

Dependence of helium transport on plasma current and ELM frequency in H-mode discharges in DIII-D

International Nuclear Information System (INIS)

Wade, M.R.; Hillis, D.L.; Hogan, J.T.; Finkenthal, D.F.; West, W.P.; Burrell, K.H.; Seraydarian, R.P.

1993-05-01

The removal of helium (He) ash from the plasma core with high efficiency to prevent dilution of the D-T fuel mixture is of utmost importance for future fusion devices, such as the International Thermonuclear Experimental Reactor (ITER). A variety of measurements in L-mode conditions have shown that the intrinsic level of helium transport from the core to the edge may be sufficient to prevent sufficient dilution (i.e., τ He /τ E < 5). Preliminary measurements in biased-induced, limited H-mode discharges in TEXTOR suggest that the intrinsic helium transport properties may not be as favorable. If this trend is shown also in diverted H-mode plasmas, then scenarios based on ELMing H-modes would be less desirable. To further establish the database on helium transport in H-mode conditions, recent studies on the DIII-D tokamak have focused on determining helium transport properties in H-mode conditions and the dependence of these properties on plasma current and ELM frequency

Nonlinear Binormal Flow of Vortex Filaments

Science.gov (United States)

Strong, Scott; Carr, Lincoln

2015-11-01

With the current advances in vortex imaging of Bose-Einstein condensates occurring at the Universities of Arizona, São Paulo and Cambridge, interest in vortex filament dynamics is experiencing a resurgence. Recent simulations, Salman (2013), depict dissipative mechanisms resulting from vortex ring emissions and Kelvin wave generation associated with vortex self-intersections. As the local induction approximation fails to capture reconnection events, it lacks a similar dissipative mechanism. On the other hand, Strong&Carr (2012) showed that the exact representation of the velocity field induced by a curved segment of vortex contains higher-order corrections expressed in powers of curvature. This nonlinear binormal flow can be transformed, Hasimoto (1972), into a fully nonlinear equation of Schrödinger type. Continued transformation, Madelung (1926), reveals that the filament's square curvature obeys a quasilinear scalar conservation law with source term. This implies a broader range of filament dynamics than is possible with the integrable linear binormal flow. In this talk we show the affect higher-order corrections have on filament dynamics and discuss physical scales for which they may be witnessed in future experiments. Partially supported by NSF.

Impact of Te and ne on edge current density profiles in ELM mitigated regimes on ASDEX Upgrade

Science.gov (United States)

Dunne, M. G.; Rathgeber, S.; Burckhart, A.; Fischer, R.; Giannone, L.; McCarthy, P. J.; Schneider, P. A.; Wolfrum, E.; the ASDEX Upgrade Team

2015-01-01

ELM resolved edge current density profiles are reconstructed using the CLISTE equilibrium code. As input, highly spatially and temporally resolved edge electron temperature and density profiles are used in addition to data from the extensive set of external poloidal field measurements available at ASDEX Upgrade, flux loop difference measurements, and current measurements in the scrape-off layer. Both the local and flux surface averaged current density profiles are analysed for several ELM mitigation regimes. The focus throughout is on the impact of altered temperature and density profiles on the current density. In particular, many ELM mitigation regimes rely on operation at high density. Two reference plasmas with type-I ELMs are analysed, one with a deuterium gas puff and one without, in order to provide a reference for the behaviour in type-II ELMy regimes and high density ELM mitigation with external magnetic perturbations at ASDEX Upgrade. For type-II ELMs it is found that while a similar pedestal top pressure is sustained at the higher density, the temperature gradient decreases in the pedestal. This results in lower local and flux surface averaged current densities in these phases, which reduces the drive for the peeling mode. No significant differences between the current density measured in the type-I phase and ELM mitigated phase is seen when external perturbations are applied, though the pedestal top density was increased. Finally, ELMs during the nitrogen seeded phase of a high performance discharge are analysed and compared to ELMs in the reference phase. An increased pedestal pressure gradient, which is the source of confinement improvement in impurity seeded discharges, causes a local current density increase. However, the increased Zeff in the pedestal acts to reduce the flux surface averaged current density. This dichotomy, which is not observed in other mitigation regimes, could act to stabilize both the ballooning mode and the peeling mode at the

A quantitative analysis of the effect of ELMs on H-mode thermal energy confinement in DIII-D

International Nuclear Information System (INIS)

Schissel, D.P.; Osborne, T.H.; Carlstrom, T.N.; Zohm, H.

1992-06-01

The desire to reach ignition in future tokamaks the energy confinement time critical parameter. The most promising enhanced (over L-mode) confinement regime is the H-mode, discovered on ASDEX with neutral beam heating, and then confirmed with various auxiliary heating sources on numerous machines. The knowledge of how H-mode τ E depends on different parameters is of chemical importance to the performance predictions for next generation devices. Inter-machine H-mode total and thermal energy confinement (τ th ) scalings, which are being utilized to predict ITER thermal energy confinement, have been created for discharges where the Edge Localized Mode (ELM) instability has not been present. Confinement scaling research hm concentrated on this ELM-free H-mode phase mostly owing to the difficulty of characterizing ELM behavior. To date, long pulse H-mode operation has only been achieved by utilizing ELMs to flush out unpurities and prevent radiative collapse of the discharge. Unfortunately, accompanying the ELMS is a decrease of the plasma stored energy due to the expulsion of particles near the edge of the discharge resulting in a reduction of the steep edge electron density gradient. In order to predict ITER's H-mode τ th in the presence of ELMS, an estimated 25% confinement degradation factor has been applied to the ELM-free predictions. Our work, summarized in this paper, indicates that this 25% reduction factor is too large and instead a value of approximately 15% would be more appropriate

Mutation-specific effects on thin filament length in thin filament myopathy.

Science.gov (United States)

Winter, Josine M de; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A; Pappas, Christopher T; Gregorio, Carol C; Stienen, Ger J M; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B; Engelen, Baziel G van; Voermans, Nicol C; Donkervoort, Sandra; Bönnemann, C G; Clarke, Nigel F; Beggs, Alan H; Granzier, Henk; Ottenheijm, Coen A C

2016-06-01

Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation. We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force-sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin-thick filament overlap. These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. Ann Neurol 2016;79:959-969. © 2016 American Neurological Association.

Comparative investigation of ELM control based on toroidal modelling of plasma response to RMP fields

Science.gov (United States)

Liu, Yueqiang

2016-10-01

The type-I edge localized mode (ELM), bursting at low frequency and with large amplitude, can channel a substantial amount of the plasma thermal energy into the surrounding plasma-facing components in tokamak devices operating at the high-confinement mode, potentially causing severe material damages. Learning effective ways of controlling this instability is thus an urgent issue in fusion research, in particular in view of the next generation large devices such as ITER and DEMO. Among other means, externally applied, three-dimensional resonant magnetic perturbation (RMP) fields have been experimentally demonstrated to be successful in mitigating or suppressing the type-I ELM, in multiple existing devices. In this work, we shall report results of a comparative study of ELM control using RMPs. Comparison is made between the modelled plasma response to the 3D external fields and the observed change of the ELM behaviour on multiple devices, including MAST, ASDEX Upgrade, EAST, DIII-D, JET, and KSTAR. We show that toroidal modelling of the plasma response, based on linear and quasi-linear magnetohydrodynamic (MHD) models, provides essential insights that are useful in interpreting and guiding the ELM control experiments. In particular, linear toroidal modelling results, using the MARS-F code, reveal the crucial role of the edge localized peeling-tearing mode response during ELM mitigation/suppression on all these devices. Such response often leads to strong peaking of the plasma surface displacement near the region of weak equilibrium poloidal field (e.g. the X-point), and this provides an alternative practical criterion for ELM control, as opposed to the vacuum field based Chirikov criteria. Quasi-linear modelling using MARS-Q provides quantitative interpretation of the side effects due to the ELM control coils, on the plasma toroidal momentum and particle confinements. The particular role of the momentum and particle fluxes, associated with the neoclassical toroidal

UV-induced filamentation in bacteria of the generum Erwinia

Energy Technology Data Exchange (ETDEWEB)

Prokulevich, V A; Tomichev, Yu K

1988-09-01

It is experimentally shown that cells of 56 pectolytic Erwinia strains isolated at different tomus in different states from various natural sources are converted into filaments under UV-light effect in relatively low doses which allows one to refer them to natural Fil/sup +/ - organisms. Ability to filamentation in Erwinia bacterium correlates with secretion process to the environment of pectolytic enzymes. Bacteria of 9 E.herbicola strains investigated (without pectatlyase secretion) after irradiation do not form stretched cells. Based on the results obtained a conclusion is drawn that increased ENA49 E.chrysanthemic cell sensitivity to UV light results from its natural defect in the system, providing for cell division processes like the one revealed in E.CoLiB and Lon/sup -/ - mutants of E.Coli K-12.

Heterologous gene expression in filamentous fungi.

Science.gov (United States)

Su, Xiaoyun; Schmitz, George; Zhang, Meiling; Mackie, Roderick I; Cann, Isaac K O

2012-01-01

Filamentous fungi are critical to production of many commercial enzymes and organic compounds. Fungal-based systems have several advantages over bacterial-based systems for protein production because high-level secretion of enzymes is a common trait of their decomposer lifestyle. Furthermore, in the large-scale production of recombinant proteins of eukaryotic origin, the filamentous fungi become the vehicle of choice due to critical processes shared in gene expression with other eukaryotic organisms. The complexity and relative dearth of understanding of the physiology of filamentous fungi, compared to bacteria, have hindered rapid development of these organisms as highly efficient factories for the production of heterologous proteins. In this review, we highlight several of the known benefits and challenges in using filamentous fungi (particularly Aspergillus spp., Trichoderma reesei, and Neurospora crassa) for the production of proteins, especially heterologous, nonfungal enzymes. We review various techniques commonly employed in recombinant protein production in the filamentous fungi, including transformation methods, selection of gene regulatory elements such as promoters, protein secretion factors such as the signal peptide, and optimization of coding sequence. We provide insights into current models of host genomic defenses such as repeat-induced point mutation and quelling. Furthermore, we examine the regulatory effects of transcript sequences, including introns and untranslated regions, pre-mRNA (messenger RNA) processing, transcript transport, and mRNA stability. We anticipate that this review will become a resource for researchers who aim at advancing the use of these fascinating organisms as protein production factories, for both academic and industrial purposes, and also for scientists with general interest in the biology of the filamentous fungi. Copyright © 2012 Elsevier Inc. All rights reserved.

Magnetic islands in tokamaks induced by thermal filamentation

International Nuclear Information System (INIS)

Dubois, M.A.; Mohamed-Benkadda, M.S.

1991-11-01

The thermal instability of filamentation is revisited in the fully nonlinear regime of a system of cool magnetic island chains, taking into account: the different transport processes inside and outside island cores, and a realistic temperature dependence of radiative losses. This mechanism is found to be a plausible candidate to explain the anomalous electron energy transport

Analytical Redundancy Design for Aeroengine Sensor Fault Diagnostics Based on SROS-ELM

Directory of Open Access Journals (Sweden)

Jun Zhou

2016-01-01

Full Text Available Analytical redundancy technique is of great importance to guarantee the reliability and safety of aircraft engine system. In this paper, a machine learning based aeroengine sensor analytical redundancy technique is developed and verified through hardware-in-the-loop (HIL simulation. The modified online sequential extreme learning machine, selective updating regularized online sequential extreme learning machine (SROS-ELM, is employed to train the model online and estimate sensor measurements. It selectively updates the output weights of neural networks according to the prediction accuracy and the norm of output weight vector, tackles the problems of singularity and ill-posedness by regularization, and adopts a dual activation function in the hidden nodes combing neural and wavelet theory to enhance prediction capability. The experimental results verify the good generalization performance of SROS-ELM and show that the developed analytical redundancy technique for aeroengine sensor fault diagnosis based on SROS-ELM is effective and feasible.

Dutch elm disease control: performance and costs

Science.gov (United States)

William N., Jr. Cannon; David P. Worley

1980-01-01

Municipal programs to suppress Dutch elm disease have had highly variable results. Performance as measured by tree mortality was unrelated to control strategies. Costs for control programs were 37 to 76 percent less than costs without control programs in the 15-year time-span of the study. Only those municipalities that conducted a high-performance program could be...

Study of type III ELMs in JET

NARCIS (Netherlands)

Sartori, R.; Saibene, G.; Horton, L. D.; Becoulet, M.; Budny, R.; Borba, D.; Chankin, A.; Conway, G. D.; Cordey, G.; McDonald, D.; Guenther, K.; von Hellermann, M. G.; Igithkanov, Y.; Loarte, A.; Lomas, P. J.; Pogutse, O.; Rapp, J.

2004-01-01

This paper presents the results of JET experiments aimed at studying the operational space of plasmas with a Type III ELMy edge, in terms of both local and global plasma parameters. In JET, the Type III ELMy regime has a wide operational space in the pedestal n(e)-T-e diagram, and Type III ELMs are

Small ELM regimes with good confinement on JET and comparison to those on ASDEX Upgrade, Alcator C-mod, and JT-60U

International Nuclear Information System (INIS)

Stober, J.; Lomas, P.; Saibene, G.

2005-01-01

Since it is uncertain if ITER operation is compatible with type-I ELMs, the study of alternative H-mode pedestals is an urgent issue. This paper reports on experiments on JET aiming to find scenarios with small ELMs and good confinement, such as the type-II ELMs in ASDEX Upgrade, the enhanced D-alpha H-mode in Alcator C-mod or the grassy ELMs in JT-60U. The study includes shape variations, especially the closeness to a double-null configuration, variations of q 95 , density and beta poloidal. H-mode pedestals without type-I ELMs have been observed only at the lowest currents (≤ 1.2 MA), showing similarities to the observations in the devices mentioned above. These are discussed in detail on the basis of edge fluctuation analysis. For higher currents, only the mixed type-I/II scenario is observed. Although the increased inter-ELM transport reduces the type-I ELM frequency, a single type-I ELM is not significantly reduced in size. Obviously, these results do question the accessibility of such small ELM scenarios on ITER, except perhaps the high beta-poloidal scenario at higher q 95 , which could not be tested at higher currents at JET due to limitations in heating power. (author)

Spatial Distribution and Site-Specific Spraying of Main Sucking Pests of Elm Trees.

Science.gov (United States)

Karimzadeh, R; Iranipour, S

2017-06-01

Elm trees are important landscape trees and sucking insects weaken the elm trees and produce large amounts of honeydew. The main objectives of this study were to identify main honeydew-producing pests of elm trees and do site-specific spraying against these pests. To map the spatial distribution of the sucking pests in the large scale, the study area was divided into 40 × 40 m grids and one tree was chosen randomly from each grid (a total of 55 trees). These trees were sampled twice a year in 2011 and 2012. Each sample was a 30-cm branch terminal. Eight samples were taken from each tree in four cardinal directions and two canopy levels. The number of sucking insects and leaves of each sample were counted and recorded. Spatial analysis of the data was carried out using geostatistics. Kriging was used for producing prediction maps. Insecticide application was restricted to the regions with populations higher than threshold. To identify within-tree distribution of the honeydew-producing pests, six and four elm trees were chosen in 2011 and 2012 respectively, and sampled weekly. These trees were sampled as described previously. European elm scale (EES), Gossyparia spuria (Modeer) and two species of aphids were the dominant honeydew-producing pests. The results revealed that the effects of direction, canopy level and their interactions on insect populations were not statistically significant (P < 0.05). Site-specific spraying decreased the amount of insecticides used by ca. 20%, while satisfactory control of the sucking pests and honeydew excretion was obtained. Considering the environmental and economic benefits of site-specific spraying, it is worth doing more complementary works in this area.

Plasma-edge gradients in L-mode and ELM-free H-mode JET plasmas

International Nuclear Information System (INIS)

Breger, P.; Zastrow, K.-D.; Davies, S.J.; K ig, R.W.T.; Summers, D.D.R.; Hellermann, M.G. von; Flewin, C.; Hawkes, N.C.; Pietrzyk, Z.A.; Porte, L.

1998-01-01

Experimental plasma-edge gradients in JET during the edge-localized-mode (ELM) free H-mode are examined for evidence of the presence and location of the transport barrier region inside the magnetic separatrix. High spatial resolution data in electron density is available in- and outside the separatrix from an Li-beam diagnostic, and in electron temperature inside the separatrix from an ECE diagnostic, while outside the separatrix, a reciprocating probe provides electron density and temperature data in the scrape-off layer. Ion temperatures and densities are measured using an edge charge-exchange diagnostic. A comparison of observed widths and gradients of this edge region with each other and with theoretical expectations is made. Measurements show that ions and electrons form different barrier regions. Furthermore, the electron temperature barrier width (3-4 cm) is about twice that of electron density, in conflict with existing scaling laws. Suitable parametrization of the edge data enables an electron pressure gradient to be deduced for the first time at JET. It rises during the ELM-free phase to reach only about half the marginal pressure gradient expected from ballooning stability before the first ELM. Subsequent type I ELMs occur on a pressure gradient contour roughly consistent with both a constant barrier width model and a ballooning mode envelope model. (author)

An interpretation of the structure of ELMs and the H to L transition on JET

International Nuclear Information System (INIS)

Cripwell, P.; Edwards, A.; Galvao, R.

1989-01-01

Initial studies on JET have described the characteristics of edge fluctuations in X-point plasmas and their effects on energy and particle confinement. In this paper we perform a detailed magnetic analysis of ELMs and their precursors, and make a comparison with the H to L transition. These magnetic results correlate with those of other diagnostics such as the microwave reflectometer and X-point langmuir probes. Localization of ELMs and H to L transition spike is determined with the soft X-ray camera, and particle transport estimated by an H-alpha detector. Finally possible theoretical explanations for ELMs are discussed. (author) 5 refs., 3 figs

Enhancement of ELM by Clustering Discrimination Manifold Regularization and Multiobjective FOA for Semisupervised Classification

OpenAIRE

Qing Ye; Hao Pan; Changhua Liu

2015-01-01

A novel semisupervised extreme learning machine (ELM) with clustering discrimination manifold regularization (CDMR) framework named CDMR-ELM is proposed for semisupervised classification. By using unsupervised fuzzy clustering method, CDMR framework integrates clustering discrimination of both labeled and unlabeled data with twinning constraints regularization. Aiming at further improving the classification accuracy and efficiency, a new multiobjective fruit fly optimization algorithm (MOFOA)...

Enhancement of ELM by Clustering Discrimination Manifold Regularization and Multiobjective FOA for Semisupervised Classification.

Science.gov (United States)

Ye, Qing; Pan, Hao; Liu, Changhua

2015-01-01

A novel semisupervised extreme learning machine (ELM) with clustering discrimination manifold regularization (CDMR) framework named CDMR-ELM is proposed for semisupervised classification. By using unsupervised fuzzy clustering method, CDMR framework integrates clustering discrimination of both labeled and unlabeled data with twinning constraints regularization. Aiming at further improving the classification accuracy and efficiency, a new multiobjective fruit fly optimization algorithm (MOFOA) is developed to optimize crucial parameters of CDME-ELM. The proposed MOFOA is implemented with two objectives: simultaneously minimizing the number of hidden nodes and mean square error (MSE). The results of experiments on actual datasets show that the proposed semisupervised classifier can obtain better accuracy and efficiency with relatively few hidden nodes compared with other state-of-the-art classifiers.

Enhancement of ELM by Clustering Discrimination Manifold Regularization and Multiobjective FOA for Semisupervised Classification

Directory of Open Access Journals (Sweden)

Qing Ye

2015-01-01

Full Text Available A novel semisupervised extreme learning machine (ELM with clustering discrimination manifold regularization (CDMR framework named CDMR-ELM is proposed for semisupervised classification. By using unsupervised fuzzy clustering method, CDMR framework integrates clustering discrimination of both labeled and unlabeled data with twinning constraints regularization. Aiming at further improving the classification accuracy and efficiency, a new multiobjective fruit fly optimization algorithm (MOFOA is developed to optimize crucial parameters of CDME-ELM. The proposed MOFOA is implemented with two objectives: simultaneously minimizing the number of hidden nodes and mean square error (MSE. The results of experiments on actual datasets show that the proposed semisupervised classifier can obtain better accuracy and efficiency with relatively few hidden nodes compared with other state-of-the-art classifiers.

Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

Directory of Open Access Journals (Sweden)

A. Bortolon

2017-08-01

Full Text Available Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux (Bortolon et al., Nucl. Fus., 56, 056008, 2016. However, in scenarios with high pedestal density (∼6 ×1019m−3, the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation. Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. Field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.

The non-linear evolution of edge localized modes

International Nuclear Information System (INIS)

Wenninger, Ronald

2013-01-01

mode number is 1. Consistent with linear and non-linear MHD calculations this leads to the conclusion that the dominant toroidal mode number from the linear to the non-linear phase has a transition from intermediate (n∼10) to low values (n∼1). Thi structural transition emphasizes the need to approach the question of ELM-sizes non-linearly. Furthermore the question is raised, whether the interaction of this modified non-linear perturbation and the conducting wall leads to a temporary saturation of the perturbation. Dominant magnetic perturbations are compared with ELM signatures typically observed earlier (coherent ELM precursors) or later (ELM filaments) in order to obtain information and understanding of the ELM evolution. The transport during ELMs is characterized by a competition between parallel transport to the divertor and transport in radially ejected ELM filaments. The analysis method diagnostic mapping, which has been developed in the course of this thesis, allows to carry out an improved correlation of dominant magnetic perturbations and ELM filaments. The resulting observation of propagation of both features in different perpendicular directions is understood as a consequence of the strong perpendicular rotation shear in this radial region. Furthermore dominant magnetic perturbations have characteristics of a trigger for the radial propagation of ELM filaments. The results gathered in the framework of this thesis enable the development of a picture of the processes during ELMs, which is more complete than any before. It is expected that this will contribute to a further extended understanding of ELMs and methods to mitigate them and to an ELM model, which is capable of reliably predicting ELM sizes and evolution.

The non-linear evolution of edge localized modes

Energy Technology Data Exchange (ETDEWEB)

Wenninger, Ronald

2013-01-09

mode number is 1. Consistent with linear and non-linear MHD calculations this leads to the conclusion that the dominant toroidal mode number from the linear to the non-linear phase has a transition from intermediate (n{approx}10) to low values (n{approx}1). Thi structural transition emphasizes the need to approach the question of ELM-sizes non-linearly. Furthermore the question is raised, whether the interaction of this modified non-linear perturbation and the conducting wall leads to a temporary saturation of the perturbation. Dominant magnetic perturbations are compared with ELM signatures typically observed earlier (coherent ELM precursors) or later (ELM filaments) in order to obtain information and understanding of the ELM evolution. The transport during ELMs is characterized by a competition between parallel transport to the divertor and transport in radially ejected ELM filaments. The analysis method diagnostic mapping, which has been developed in the course of this thesis, allows to carry out an improved correlation of dominant magnetic perturbations and ELM filaments. The resulting observation of propagation of both features in different perpendicular directions is understood as a consequence of the strong perpendicular rotation shear in this radial region. Furthermore dominant magnetic perturbations have characteristics of a trigger for the radial propagation of ELM filaments. The results gathered in the framework of this thesis enable the development of a picture of the processes during ELMs, which is more complete than any before. It is expected that this will contribute to a further extended understanding of ELMs and methods to mitigate them and to an ELM model, which is capable of reliably predicting ELM sizes and evolution.

Dynamic ELM and divertor control using resonant toroidal multi-mode magnetic fields in DIII-D and EAST

Science.gov (United States)

Sun, Youwen

2017-10-01

A rotating n = 2 Resonant Magnetic Perturbation (RMP) field combined with a stationary n = 3 RMP field has validated predictions that access to ELM suppression can be improved, while divertor heat and particle flux can also be dynamically controlled in DIII-D. Recent observations in the EAST tokamak indicate that edge magnetic topology changes, due to nonlinear plasma response to magnetic perturbations, play a critical role in accessing ELM suppression. MARS-F code MHD simulations, which include the plasma response to the RMP, indicate the nonlinear transition to ELM suppression is optimized by configuring the RMP coils to drive maximal edge stochasticity. Consequently, mixed toroidal multi-mode RMP fields, which produce more densely packed islands over a range of additional rational surfaces, improve access to ELM suppression, and further spread heat loading on the divertor. Beneficial effects of this multi-harmonic spectrum on ELM suppression have been validated in DIII-D. Here, the threshold current required for ELM suppression with a mixed n spectrum, where part of the n = 3 RMP field is replaced by an n = 2 field, is smaller than the case with pure n = 3 field. An important further benefit of this multi-mode approach is that significant changes of 3D particle flux footprint profiles on the divertor are found in the experiment during the application of a rotating n = 2 RMP field superimposed on a static n = 3 RMP field. This result was predicted by modeling studies of the edge magnetic field structure using the TOP2D code which takes into account plasma response from MARS-F code. These results expand physics understanding and potential effectiveness of the technique for reliably controlling ELMs and divertor power/particle loading distributions in future burning plasma devices such as ITER. Work supported by USDOE under DE-FC02-04ER54698 and NNSF of China under 11475224.

COMPARISON OF ELM PULSE PROPAGATION IN THE DIII-D SOL AND DIVERTORS WITH AN ION CONVECTION MODEL

International Nuclear Information System (INIS)

FENSTERMACHER, ME; PORTER, GD; LEONARD, AW; BROOKS, NH; BOEDO, JA; COLCHIN, RJ; GRAY, DS; GROEBNER, RJ; GROTH, M; HOGAN, JT; HOLLMANN, EM; LASNIER, CJ; OSBORNE, TH; PETRIE, TW; RUDAKOV, DL; SNYDER, PB; TAKAHASHI, H; WATKINS, JG; ZENG, L; DIII-D TEAM

2003-01-01

OAK-B135 Results from dedicated ELM experiments, performed in DIII-D with fast diagnostics to measure the evolution of Type-I ELM effects in the SOL and divertor, are compared with a simple ion convection model and with initial time-dependent UEDGE simulations. Delays between ELM effects observed in the inner versus the outer divertor regions in the experiments scale, as a function of density, with the difference in ion convection time along field lines from the outer midplane to the divertor targets. The ELM perturbation was modeled as an instantaneous radially uniform increase of diffusion coefficients from the top of the pedestal to the outer SOL. The perturbation was confined to a low field side poloidal zone ± 40 o from the outer midplane. The delays in the simulations are similar to those observed in the experiments

Scaling of ELM and H-mode pedestal characteristics in ITER shape discharges in the DIII-D tokamak

International Nuclear Information System (INIS)

Osborne, T.H.; Groebner, R.J.; Lao, L.L.; Leonard, A.W.; Miller, R.L.; Thomas, D.M.; Waltz, R.E.; Maingi, R.; Porter, G.D.

1997-07-01

The authors have shown a correlation between the H-mode pressure pedestal height and the energy confinement enhancement in ITER shape discharges on DIII-D which is consistent with the behavior of H in different ELM classes. The width of the steep gradient region was found to equally well fit the scalings δ/R ∝ (ρ POL /R) 2/3 and δ/R ∝ (β POL PED /R) 1/2 . The normalized pressure gradient α MHD was found to be relatively constant just before a type I ELM. An estimate of T PED for ITER gave 1 to 5 keV. They also estimate ΔE ELM ≅ 26 MJ for ITER. They identified a distinct class of type III ELM at low density which may play a role in setting H at powers near the H-mode threshold power

Scrape-off layer ion temperature measurements at the divertor target during type III ELMs in MAST measured by RFEA

Energy Technology Data Exchange (ETDEWEB)

Elmore, S., E-mail: Sarah.Elmore@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Allan, S.Y.; Fishpool, G.; Kirk, A. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kočan, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Tamain, P. [Association Euratom-CEA, CEA/DSM/IRFM, CEA-Cadarache, F-13108 St Paul-lez-Durance Cedex (France); Thornton, A.J. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2015-08-15

Edge-localised modes (ELMs) can carry significant fractions of their energy as far as main chamber plasma-facing components in divertor tokamaks. Since in future devices (e.g. ITER, DEMO) these energies could cause issues for material lifetime and impurity production, the energy and temperature of ions in ELMs needs to be investigated. In MAST, novel divertor measurements of T{sub i} during ELMs have been made using the divertor retarding field energy analyser (RFEA) probe. These measurements have shown instantaneous ion energy distributions corresponding to an effective T{sub i} at 5 cm from the strike point at the target that can be as high as 60 eV and that this decreases with time after the ELM start. This is consistent with the hottest, fastest ions arriving at the target first by parallel transport, followed by the lower end of the ion energy distribution. This analysis will form a basis for future data analysis of fast swept measurements of ion distributions in ELMs.

Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

Energy Technology Data Exchange (ETDEWEB)

Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 220, Santiago (Chile); Castillo, Fermin [Universidad Nacional Autónoma de México, Cuernavaca, México (Mexico); Veloso, Felipe [Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago (Chile); Auluck, S. K. H. [Bhabha Atomic Research Center, Mumbai 400 085 (India)

2014-07-15

Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

Stability analysis of ELMs in long-pulse discharges with ELITE code on EAST tokamak

Science.gov (United States)

Wang, Y. F.; Xu, G. S.; Wan, B. N.; Li, G. Q.; Yan, N.; Li, Y. L.; Wang, H. Q.; Peng, Y.-K. Martin; Xia, T. Y.; Ding, S. Y.; Chen, R.; Yang, Q. Q.; Liu, H. Q.; Zang, Q.; Zhang, T.; Lyu, B.; Xu, J. C.; Feng, W.; Wang, L.; Chen, Y. J.; Luo, Z. P.; Hu, G. H.; Zhang, W.; Shao, L. M.; Ye, Y.; Lan, H.; Chen, L.; Li, J.; Zhao, N.; Wang, Q.; Snyder, P. B.; Liang, Y.; Qian, J. P.; Gong, X. Z.; EAST team

2018-05-01

One challenge in long-pulse and high performance tokamak operation is to control the edge localized modes (ELMs) to reduce the transient heat load on plasma facing components. Minute-scale discharges in H-mode have been achieved repeatedly on Experimental Advanced Superconducting Tokamak (EAST) since the 2016 campaign and understanding the characteristics of the ELMs in these discharges can be helpful for effective ELM control in long-pulse discharges. The kinetic profile diagnostics recently developed on EAST make it possible to perform the pedestal stability analysis quantitatively. Pedestal stability calculation of a typical long-pulse discharge with ELITE code is presented. The ideal linear stability results show that the ELM is dominated by toroidal mode number n around 10–15 and the most unstable mode structure is mainly localized in the steep pressure gradient region, which is consistent with experimental results. Compared with a typical type-I ELM discharge with larger total plasma current (I p = 600 kA), pedestal in the long-pulse H-mode discharge (I p = 450 kA) is more stable in peeling-ballooning instability and its critical peak pressure gradient is evaluated to be 65% of the former. Two important features of EAST tokamak in the long-pulse discharge are presented by comparison with other tokamaks, including a wider pedestal correlated with the poloidal pedestal beta and a smaller inverse aspect ratio and their effects on the pedestal stability are discussed. The effects of uncertainties in measurements on the linear stability results are also analyzed, including the edge electron density profile position, the separatrix position and the line-averaged effective ion charge {Z}{{e}{{f}}{{f}}} value.

Hyperparameterization of soil moisture statistical models for North America with Ensemble Learning Models (Elm)

Science.gov (United States)

Steinberg, P. D.; Brener, G.; Duffy, D.; Nearing, G. S.; Pelissier, C.

2017-12-01

Hyperparameterization, of statistical models, i.e. automated model scoring and selection, such as evolutionary algorithms, grid searches, and randomized searches, can improve forecast model skill by reducing errors associated with model parameterization, model structure, and statistical properties of training data. Ensemble Learning Models (Elm), and the related Earthio package, provide a flexible interface for automating the selection of parameters and model structure for machine learning models common in climate science and land cover classification, offering convenient tools for loading NetCDF, HDF, Grib, or GeoTiff files, decomposition methods like PCA and manifold learning, and parallel training and prediction with unsupervised and supervised classification, clustering, and regression estimators. Continuum Analytics is using Elm to experiment with statistical soil moisture forecasting based on meteorological forcing data from NASA's North American Land Data Assimilation System (NLDAS). There Elm is using the NSGA-2 multiobjective optimization algorithm for optimizing statistical preprocessing of forcing data to improve goodness-of-fit for statistical models (i.e. feature engineering). This presentation will discuss Elm and its components, including dask (distributed task scheduling), xarray (data structures for n-dimensional arrays), and scikit-learn (statistical preprocessing, clustering, classification, regression), and it will show how NSGA-2 is being used for automate selection of soil moisture forecast statistical models for North America.

Filament Activation in Response to Magnetic Flux Emergence and Cancellation in Filament Channels

Science.gov (United States)

Li, Ting; Zhang, Jun; Ji, Haisheng

2015-06-01

We conducted a comparative analysis of two filaments that showed a quite different activation in response to the flux emergence within the filament channels. The observations from the Solar Dynamics Observatory (SDO) and Global Oscillation Network Group (GONG) were made to analyze the two filaments on 2013 August 17 - 20 (SOL2013-08-17) and September 29 (SOL2013-09-29). The first event showed that the main body of the filament was separated into two parts when an active region (AR) emerged with a maximum magnetic flux of about 6.4×1021 Mx underlying the filament. The close neighborhood and common direction of the bright threads in the filament and the open AR fan loops suggest a similar magnetic connectivity of these two flux systems. The equilibrium of the filament was not destroyed three days after the start of the emergence of the AR. To our knowledge, similar observations have never been reported before. In the second event, the emerging flux occurred nearby a barb of the filament with a maximum magnetic flux of 4.2×1020 Mx, about one order of magnitude lower than that of the first event. Two patches of parasitic polarity in the vicinity of the barb merged, then cancelled with nearby network fields. About 20 hours after the onset of the emergence, the filament erupted. Our findings imply that the location of emerging flux within the filament channel is probably crucial to filament evolution. If the flux emergence appears nearby the barbs, it is highly likely that the emerging flux and the filament magnetic fields will cancel, which may lead to the eruption of the filament. The comparison of the two events shows that the emergence of a small AR may still not be enough to disrupt the stability of a filament system, and the actual eruption only occurs after the flux cancellation sets in.

H-mode pedestal characteristics, ELMs, and energy confinement in ITER shape discharges on DIII-D

International Nuclear Information System (INIS)

Osborne, T.H.; Groebner, R.J.; Lao, L.L.; Leonard, A.W.; Miller, R.L.; Thomas, D.M.; Waltz, R.E.; Maingi, R.; Porter, G.D.

1997-12-01

The H-mode confinement enhancement factor, H, is found to be strongly correlated with the height of the edge pressure pedestal in ITER shape discharges. In discharges with Type I ELMs the pedestal pressure is set by the maximum pressure gradient before the ELM and the width of the H-mode transport barrier. The pressure gradient before Type I ELMs is found to scale as would be expected for a stability limit set by ideal ballooning modes, but with values significantly in excess of that predicted by stability code calculations. The width of the H-mode transport barrier is found to scale equally well with pedestal P(POL)(2/3) or B(POL)(1/2). The improved H value in high B(POL) discharges may be due to a larger edge pressure gradient and wider H-mode transport barrier consistent with their higher edge ballooning mode limit. Deuterium puffing is found to reduce H consistent with the smaller pedestal pressure which results from the reduced barrier width and critical pressure gradient. Type I ELM energy loss is found to be proportional to the change in the pedestal energy

Dynamic divertor control using resonant mixed toroidal harmonic magnetic fields during ELM suppression in DIII-D

Science.gov (United States)

Jia, M.; Sun, Y.; Paz-Soldan, C.; Nazikian, R.; Gu, S.; Liu, Y. Q.; Abrams, T.; Bykov, I.; Cui, L.; Evans, T.; Garofalo, A.; Guo, W.; Gong, X.; Lasnier, C.; Logan, N. C.; Makowski, M.; Orlov, D.; Wang, H. H.

2018-05-01

Experiments using Resonant Magnetic Perturbations (RMPs), with a rotating n = 2 toroidal harmonic combined with a stationary n = 3 toroidal harmonic, have validated predictions that divertor heat and particle flux can be dynamically controlled while maintaining Edge Localized Mode (ELM) suppression in the DIII-D tokamak. Here, n is the toroidal mode number. ELM suppression over one full cycle of a rotating n = 2 RMP that was mixed with a static n = 3 RMP field has been achieved. Prominent heat flux splitting on the outer divertor has been observed during ELM suppression by RMPs in low collisionality regime in DIII-D. Strong changes in the three dimensional heat and particle flux footprint in the divertor were observed during the application of the mixed toroidal harmonic magnetic perturbations. These results agree well with modeling of the edge magnetic field structure using the TOP2D code, which takes into account the plasma response from the MARS-F code. These results expand the potential effectiveness of the RMP ELM suppression technique for the simultaneous control of divertor heat and particle load required in ITER.

Quantification of filamentation by uropathogenic Escherichia coli during experimental bladder cell infection by using semi-automated image analysis

DEFF Research Database (Denmark)

Klein, Kasper; Palarasah, Yaseelan; Kolmos, Hans Jørn

2015-01-01

in focus-stacked microscopy images. Used in combination with a flow-chamber based in vitro cystitis model, we study the factors involved in filament formation by uropathogenic E. coli (UPEC) during infection. The influence of substratum surface, intracellular proliferation and flow media on UPEC...... rod-shaped cells. Evidence has emerged over the past decade suggesting that this morphological transformation is controlled and reversible and provides selective advantages under certain growth conditions, such as during infection in humans. In order to identify the factors which induce filamentation...... filamentation is evaluated. We show that reversible UPEC filamentation during cystitis is not dependent on intracellular infection, which previous studies have suggested. Instead, we find that filamentation can be induced by contact with surfaces, both biological and artificial. Lastly our data indicate...

The influence of protruding filamentous bacteria on floc stability and solid-liquid separation in the activated sludge process.

Science.gov (United States)

Burger, Wilhelm; Krysiak-Baltyn, Konrad; Scales, Peter J; Martin, Gregory J O; Stickland, Anthony D; Gras, Sally L

2017-10-15

Filamentous bacteria can impact on the physical properties of flocs in the activated sludge process assisting solid-liquid separation or inducing problems when bacteria are overabundant. While filamentous bacteria within the flocs are understood to increase floc tensile strength, the relationship between protruding external filaments, dewatering characteristics and floc stability is unclear. Here, a quantitative methodology was applied to determine the abundance of filamentous bacteria in activated sludge samples from four wastewater treatment plants. An automated image analysis procedure was applied to identify filaments and flocs and calculate the length of the protruding filamentous bacteria (PFB) relative to the floc size. The correlation between PFB and floc behavior was then assessed. Increased filament abundance was found to increase interphase drag on the settling flocs, as quantified by the hindered settling function. Additionally, increased filament abundance was correlated with a lower gel point concentration leading to poorer sludge compactability. The floc strength factor, defined as the relative change in floc size upon shearing, correlated positively with filament abundance. This influence of external protruding filamentous bacteria on floc stability is consistent with the filamentous backbone theory, where filamentous bacteria within flocs increase floc resistance to shear-induced breakup. A qualitative correlation was also observed between protruding and internal filamentous structure. This study confirms that filamentous bacteria are necessary to enhance floc stability but if excessively abundant will adversely affect solid-liquid separation. The tools developed here will allow quantitative analysis of filament abundance, which is an improvement on current qualitative methods and the improved method could be used to assist and optimize the operation of waste water treatment plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pacing control of sawtooth and ELM oscillations in tokamaks

NARCIS (Netherlands)

Lauret, M.; Lennholm, M.; de Baar, M.R.; Heemels, W.P.M.H.

2016-01-01

In tokamak plasmas, the sawtooth oscillation (ST) and the edge-localized-mode (ELM) are characterized by a phase of a slow evolution of the plasma conditions, followed by a crash-like instability that resets the plasma conditions when certain criteria of the plasma conditions are satisfied.

Erosion dynamics of tungsten fuzz during ELM-like heat loading

Science.gov (United States)

Sinclair, G.; Tripathi, J. K.; Hassanein, A.

2018-04-01

Transient heat loading and high-flux particle loading on plasma facing components in fusion reactors can lead to surface melting and possible erosion. Helium-induced fuzz formation is expected to exacerbate thermal excursions, due to a significant drop in thermal conductivity. The effect of heating in edge-localized modes (ELMs) on the degradation and erosion of a tungsten (W) fuzz surface was examined experimentally in the Ultra High Flux Irradiation-II facility at the Center for Materials Under Extreme Environment. W foils were first exposed to low-energy He+ ion irradiation at a fluence of 2.6 × 1024 ions m-2 and a steady-state temperature of 1223 K. Then, samples were exposed to 1000 pulses of ELM-like heat loading, at power densities between 0.38 and 1.51 GW m-2 and at a steady-state temperature of 1223 K. Comprehensive erosion analysis measured clear material loss of the fuzz nanostructure above 0.76 GW m-2 due to melting and splashing of the exposed surface. Imaging of the surface via scanning electron microscopy revealed that sufficient heating at 0.76 GW m-2 and above caused fibers to form tendrils to conglomerate and form droplets. Repetitive thermal loading on molten surfaces then led to eventual splashing. In situ erosion measurements taken using a witness plate and a quartz crystal microbalance showed an exponential increase in mass loss with energy density. Compositional analysis of the witness plates revealed an increase in the W 4f signal with increasing energy density above 0.76 GW m-2. The reduced thermal stability of the fuzz nanostructure puts current erosion predictions into question and strengthens the importance of mitigation techniques.

Solo and keratin filaments regulate epithelial tubule morphology.

Science.gov (United States)

Nishimura, Ryosuke; Kato, Kagayaki; Fujiwara, Sachiko; Ohashi, Kazumasa; Mizuno, Kensaku

2018-04-28

Epithelial tubules, consisting of the epithelial cell sheet with a central lumen, are the basic structure of many organs. Mechanical forces play an important role in epithelial tubulogenesis; however, little is known about the mechanisms controlling the mechanical forces during epithelial tubule morphogenesis. Solo (also known as ARHGEF40) is a RhoA-targeting guanine-nucleotide exchange factor that is involved in mechanical force-induced RhoA activation and stress fiber formation. Solo binds to keratin-8/keratin-18 (K8/K18) filaments, and this interaction plays a crucial role in mechanotransduction. In this study, we examined the roles of Solo and K8/K18 filaments in epithelial tubulogenesis using MDCK cells cultured in 3D collagen gels. Knockdown of either Solo or K18 resulted in rounder tubules with increased lumen size, indicating that Solo and K8/K18 filaments play critical roles in forming the elongated morphology of epithelial tubules. Moreover, knockdown of Solo or K18 decreased the level of diphosphorylated myosin light chain (a marker of contractile force) at the luminal and outer surfaces of tubules, suggesting that Solo and K8/K18 filaments are involved in the generation of the myosin II-mediated contractile force during epithelial tubule morphogenesis. In addition, K18 filaments were normally oriented along the long axis of the tubule, but knockdown of Solo perturbed their orientation. These results suggest that Solo plays crucial roles in forming the elongated morphology of epithelial tubules and in regulating myosin II activity and K18 filament organization during epithelial tubule formation.

Tungsten erosion under plasma heat loads typical for ITER type I Elms and disruptions

Energy Technology Data Exchange (ETDEWEB)

Garkusha, I.E. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine)]. E-mail: garkusha@ipp.kharkov.ua; Bandura, A.N. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Byrka, O.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Chebotarev, V.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Landman, I.S. [Forschungszentrum Karlsruhe, IHM, 76021 Karlsruhe (Germany); Makhlaj, V.A. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Marchenko, A.K. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Solyakov, D.G. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Tereshin, V.I. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Trubchaninov, S.A. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine); Tsarenko, A.V. [Institute of Plasma Physics of the NSC KIPT, 61108 Kharkov (Ukraine)

2005-03-01

The behavior of pure sintered tungsten under repetitive plasma heat loads of {approx}1 MJ/m{sup 2} (which is relevant to ITER ELMs) and 25 MJ/m{sup 2} (ITER disruptions) is studied with the quasi-steady-state plasma accelerator QSPA Kh-50. The ELM relevant heat loads have resulted in formation of two kinds of crack networks, with typical sizes of 10-20 {mu}m and {approx}1 mm, at the surface. Tungsten preheating to 600 deg. C indicates that fine intergranular cracks are probably caused by thermal stresses during fast resolidification of the melt, whereas large cracks are the result of ductile-to-brittle transition. For several hundreds of ELM-like exposures, causing surface melting, the melt motion does not dominate the profile of the melt spot. The disruption relevant experiments demonstrated that melt motion became the main factor of tungsten damage.

Coexisting Flux Rope and Dipped Arcade Sections Along One Solar Filament

Science.gov (United States)

Guo, Y.; Schmieder, B.; Démoulin, P.; Wiegelmann, T.; Aulanier, G.; Török, T.; Bommier, V.

2010-05-01

We compute the three-dimensional magnetic field of an active region in order to study the magnetic configuration of active region filaments. The nonlinear force-free field model is adopted to compute the magnetic field above the photosphere, where the vector magnetic field was observed by THEMIS/MTR on 2005 May 27. We propose a new method to remove the 180° ambiguity of the transverse field. Next, we analyze the implications of the preprocessing of the data by minimizing the total force and torque in the observed vector fields. This step provides a consistent bottom boundary condition for the nonlinear force-free field model. Then, using the optimization method to compute the coronal field, we find a magnetic flux rope along the polarity inversion line. The magnetic flux rope aligns well with part of an Hα filament, while the total distribution of the magnetic dips coincides with the whole Hα filament. This implies that the magnetic field structure in one section of the filament is a flux rope, while the other is a sheared arcade. The arcade induced a left-bearing filament in the magnetic field of negative helicity, which is opposite to the chirality of barbs that a flux rope would induce in a magnetic field of the same helicity sign. The field strength in the center of the flux rope is about 700 G, and the twist of the field lines is ~1.4 turns.

Impact of impurity seeding and divertor conditions on transitions, pedestal structure and ELMs

Science.gov (United States)

Dunne, M. G.

2017-02-01

Future devices will require a high scrape-off later (SOL) density and impurity seeding to avoid high-Z sputtering. However, these operational parameters are not included in present-day scaling laws, making extrapolations to larger devices difficult. As such, understanding the physics of such effects is vital in order to design the operational scenarios most favorable to high fusion gain. This review presents the favorable lowering of L-H transition power by changing to metal walled devices and sumarises the effects currently thought to be responsible for how SOL geometry can play a role in determining this threshold. Experimental observations on changes to the pedestal structure with main ion fuelling and low-, medium-, and high-Z impurity seeding are presented. These results, from several devices, show that main ion fuelling or high density operation can result in a lower pedestal top pressure, and hence reduced stored energy, while impurity seeding can recover this lost pressure. Particular focus is given to nitrogen seeded discharges and the recovery of pedestal parameters (notably high {{T}\\text{e,\\text{ped}}} ) in JET and AUG since the changeover to metal walls in these devices. Lithium seeding is also emerging as a strong actuator in pedestal dynamics, with results ranging from a prolonged inter-ELM period to completely ELM-free scenarios on different devices. ELM dynamics are also presented in each section, with nitrogen seeding offering a probe into the structure of the ELM and demonstrating the difference between the initial ELM crash, likely due to a sharp MHD event, and a prolonged second phase, the origin of which remains unkown. Finally, modelling of the pedestal in impurity seeded scenarios reveals a common effect in the position of the density profile. Either through mode excitation near to the separatrix or an altered fuelling profile, seeding of impurities results in an inward shift of the density profile. This inward shift improves MHD stability

Challenge inoculations to test for Dutch elm disease tolerance: a summary of Methods used by various researchers

Science.gov (United States)

A variety of methods have been used by different research groups to “challenge” inoculate American elms (Ulmus americana) with the purpose of determining whether some clones may be resistant to the Dutch elm disease fungus. The methods used by seven research groups are described, along with observat...

Two-dimensional numerical study of ELMs-induced erosion of tungsten divertor target tiles with different edge shapes

International Nuclear Information System (INIS)

Huang, Yan; Sun, Jizhong; Hu, Wanpeng; Sang, Chaofeng; Wang, Dezhen

2016-01-01

Highlights: • Thermal performance of three edge-shaped divertor tiles was assessed numerically. • All the divertor tiles exposed to type-I ELMs like ITER's will melt. • The rounded edge tile thermally performs the best in all tiles of interest. • The incident energy flux density was evaluated with structural effects considered. - Abstract: Thermal performance of the divertor tile with different edge shapes was assessed numerically along the poloidal direction by a two-dimensional heat conduction model with considering the geometrical effects of castellated divertor tiles on the properties of its adjacent plasma. The energy flux density distribution arriving at the castellated divertor tile surface was evaluated by a two-dimension-in-space and three-dimension-in-velocity particle-in-cell plus Monte Carlo Collisions code and then the obtained energy flux distribution was used as input for the heat conduction model. The simulation results showed that the divertor tiles with any edge shape of interest (rectangular edge, slanted edge, and rounded edge) would melt, especially, in the edge surface region of facing plasma poloidally under typical heat flux density of a transient event of type-I ELMs for ITER, deposition energy of 1 MJ/m"2 in a duration of 600 μs. In comparison with uniform energy deposition, the vaporizing erosion was reduced greatly but the melting erosion was aggravated noticeably in the edge area of plasma facing diveror tile. Of three studied edge shapes, the simulation results indicated that the divertor plate with rounded edge was the most resistant to the thermal erosion.

Manufacture of mineral-insulated conductor for ITER prototype ELM and VS coil

International Nuclear Information System (INIS)

Long, Feng; Wu, Yu; Jin, Huan; Yu, Min; Han, Qiyang; Ling, Feng; Kalish, Michael

2015-01-01

Highlights: • Compaction method is successfully developed for MIC manufacture. • Manufactured MICs show well controlled outer diameter and good electrical properties. • Insulation resistance of all the MICs is higher than 100 GΩ@DC 2500 V. - Abstract: An ITER Organization (IO) Task Agreement (TA) “Final Design and Prototyping of the ITER In-Vessel Coils (IVC) and Feeders” is almost finished by Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). ITER IVCs consist of edge-localized mode (ELM) and vertical stabilization (VS) coils. One prototype Mid-ELM coil complete with 19 brackets brazed with the conductors and one prototype 120° section of upper VS coil with structural components brazed to the conductors have been fabricated. Compaction method is developed successfully for the mineral-insulated conductor (MIC) manufacture. Approximate 110 m Inconel 625 jacket MICs for Mid-ELM prototype coil and 80 m stainless steel 316L jacket MICs for VS prototype coil were manufactured. Most of the copper tubes used for the MICs fabrication failed the ultrasonic testing (UT), but the jacket tubes have good passing rate. Manufacture processes and inspection for the MICs are presented in this paper

Manufacture of mineral-insulated conductor for ITER prototype ELM and VS coil

Energy Technology Data Exchange (ETDEWEB)

Long, Feng, E-mail: longf@ipp.ac.cn [Institute of Plasma Physics of Chinese Academy of Sciences, Hefei 230031 (China); Wu, Yu; Jin, Huan; Yu, Min; Han, Qiyang; Ling, Feng [Institute of Plasma Physics of Chinese Academy of Sciences, Hefei 230031 (China); Kalish, Michael [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, NJ 08543 (United States)

2015-06-15

Highlights: • Compaction method is successfully developed for MIC manufacture. • Manufactured MICs show well controlled outer diameter and good electrical properties. • Insulation resistance of all the MICs is higher than 100 GΩ@DC 2500 V. - Abstract: An ITER Organization (IO) Task Agreement (TA) “Final Design and Prototyping of the ITER In-Vessel Coils (IVC) and Feeders” is almost finished by Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). ITER IVCs consist of edge-localized mode (ELM) and vertical stabilization (VS) coils. One prototype Mid-ELM coil complete with 19 brackets brazed with the conductors and one prototype 120° section of upper VS coil with structural components brazed to the conductors have been fabricated. Compaction method is developed successfully for the mineral-insulated conductor (MIC) manufacture. Approximate 110 m Inconel 625 jacket MICs for Mid-ELM prototype coil and 80 m stainless steel 316L jacket MICs for VS prototype coil were manufactured. Most of the copper tubes used for the MICs fabrication failed the ultrasonic testing (UT), but the jacket tubes have good passing rate. Manufacture processes and inspection for the MICs are presented in this paper.

Edge localized mode control by resonant magnetic perturbations in tokamak plasmas

International Nuclear Information System (INIS)

Orain, Francois

2014-01-01

geometry. An ELM is characterized by the growth of precursors, rotating in the electron diamagnetic direction at half the diamagnetic frequency, followed by the non-linear expulsion of plasma filaments through the edge transport barrier. This behaviour found in modeling accurately matches several experimental observations. After an ELM crash, the diamagnetic rotation is found to be instrumental to stabilize the plasma and to model the cyclic reconstruction and collapse of the plasma pressure profile. ELM relaxations are cyclically initiated each time the pedestal gradient crosses a triggering threshold. After a few transient ELMs, a quasiperiodic ELMy regime is obtained, characterized by a similar coupling between modes, similar maximum pressure gradient reached when the crash occurs and similar power deposition on the divertor plates, cyclically recovered for all the ELMs. Diamagnetic drifts are also found to yield a near-symmetric ELM power deposition on the inner and outer divertor target plates, in closer agreement with experimental measurements as compared to previous simulations where the diamagnetic rotation was neglected. Last the ELM mitigation and suppression by RMPs is observed for the first time in modeling. The non-linear coupling of the RMPs with unstable modes is found to modify the edge magnetic topology and to induce a continuous MHD activity in place of a large ELM crash, resulting in the mitigation of the ELMs. The ELM footprints follow the RMP footprint, although modulated by other modes. At larger diamagnetic rotation, a bifurcation from unmitigated ELMs (at low RMP current) towards fully suppressed ELMs (at large RMP current) is obtained: the large permanent transport induced by the RMP-driven MHD activity stabilizes the plasma under the stability threshold thus ELMs are fully suppressed. (author) [fr

Filament Substructures and their Interrelation

Science.gov (United States)

Lin, Y.; Martin, S. F.; Engvold, O.

The main structural components of solar filaments, their spines, barbs, and legs at the extreme ends of the spine, are illustrated from recent high-resolution observations. The thread-like structures appear to be present in filaments everywhere and at all times. They are the fundamental elements of solar filaments. The interrelation of the spines, barbs and legs are discussed. From observations, we present a conceptual model of the magnetic field of a filament. We suggest that only a single physical model is needed to explain filaments in a continuous spectrum represented by active region filaments at one end and quiescent filaments at the other end.

Challenge inoculations to test for Dutch elm disease tolerance: a summary of methods used by various researchers

Science.gov (United States)

Linda M. Haugen; Garrett L. Beier; Susan E. Bentz; Raymond P. Guries; James M. Slavicek

2017-01-01

A variety of methods have been used by different research groups to "challenge" inoculate American elms (Ulmus americana) with the purpose of determining whether some clones may be resistant to the Dutch elm disease fungus. The methods used by seven research groups are described, along with observations on complications and benefits...

Unconventional actin conformations localize on intermediate filaments in mitosis

International Nuclear Information System (INIS)

Hubert, Thomas; Vandekerckhove, Joel; Gettemans, Jan

2011-01-01

Research highlights: → Unconventional actin conformations colocalize with vimentin on a cage-like structure in metaphase HEK 293T cells. → These conformations are detected with the anti-actin antibodies 1C7 ('lower dimer') and 2G2 ('nuclear actin'), but not C4 (monomeric actin). → Mitotic unconventional actin cables are independent of filamentous actin or microtubules. → Unconventional actin colocalizes with vimentin on a nocodazole-induced perinuclear dense mass of cables. -- Abstract: Different structural conformations of actin have been identified in cells and shown to reside in distinct subcellular locations of cells. In this report, we describe the localization of actin on a cage-like structure in metaphase HEK 293T cells. Actin was detected with the anti-actin antibodies 1C7 and 2G2, but not with the anti-actin antibody C4. Actin contained in this structure is independent of microtubules and actin filaments, and colocalizes with vimentin. Taking advantage of intermediate filament collapse into a perinuclear dense mass of cables when microtubules are depolymerized, we were able to relocalize actin to such structures. We hypothesize that phosphorylation of intermediate filaments at mitosis entry triggers the recruitment of different actin conformations to mitotic intermediate filaments. Storage and partition of the nuclear actin and antiparallel 'lower dimer' actin conformations between daughter cells possibly contribute to gene transcription and transient actin filament dynamics at G1 entry.

Role of phytohormones in organogenic ability of elm multiplicated shoots

Czech Academy of Sciences Publication Activity Database

Malá, J.; Gaudinová, Alena; Dobrev, Petre; Eder, Josef; Cvikrová, Milena

2006-01-01

Roč. 50, č. 1 (2006), s. 8-14 ISSN 0006-3134 Institutional research plan: CEZ:AV0Z5038910; CEZ:AV0Z50380511 Keywords : auxin * cytokinins * multiplication of elm Subject RIV: GK - Forestry Impact factor: 1.198, year: 2006

Intermediate Filaments at the Junction of Mechanotransduction, Migration, and Development

Directory of Open Access Journals (Sweden)

Rucha Sanghvi-Shah

2017-09-01

Full Text Available Mechanically induced signal transduction has an essential role in development. Cells actively transduce and respond to mechanical signals and their internal architecture must manage the associated forces while also being dynamically responsive. With unique assembly-disassembly dynamics and physical properties, cytoplasmic intermediate filaments play an important role in regulating cell shape and mechanical integrity. While this function has been recognized and appreciated for more than 30 years, continually emerging data also demonstrate important roles of intermediate filaments in cell signal transduction. In this review, with a particular focus on keratins and vimentin, the relationship between the physical state of intermediate filaments and their role in mechanotransduction signaling is illustrated through a survey of current literature. Association with adhesion receptors such as cadherins and integrins provides a critical interface through which intermediate filaments are exposed to forces from a cell's environment. As a consequence, these cytoskeletal networks are posttranslationally modified, remodeled and reorganized with direct impacts on local signal transduction events and cell migratory behaviors important to development. We propose that intermediate filaments provide an opportune platform for cells to both cope with mechanical forces and modulate signal transduction.

Intermittent transport across the scrape-off layer: latest results from ASDEX Upgrade

International Nuclear Information System (INIS)

Kočan, M.; Müller, H.W.; Lunt, T.; Bernert, M.; Conway, G.D.; De Marné, P.; Eich, T.; Herrmann, A.; Kallenbach, A.; Maraschek, M.; Müller, S.; Nold, B.; Huang, Z.; Adámek, J.; Horacek, J.; Komm, M.; Allan, S.Y.; Elmore, S.; Gennrich, F.P; Mehlmann, F.

2013-01-01

We report the latest results of turbulence and transport studies in the ASDEX Upgrade scrape-off layer (SOL). Dissimilarity between the plasma and the floating potential fluctuations is studied experimentally and by gyrofluid simulations. Measurements by a retarding field analyser reveal that both, edge-localized mode (ELM) and turbulent filaments, convey hot ions over large radial distances in the SOL. The measured far SOL ELM ion temperature increases with the ELM energy, consistent with earlier observations that large ELMs deposit a large fraction of their energy outside the divertor. In the SOL, the ELM suppression by magnetic perturbations (MPs) results in lower ELM ion energy in the far SOL. At the same time, large filaments of ion saturation current are replaced by more continuous bursts. Splitting of the divertor strike zones observed by the infrared imaging in H-mode with MPs agree with predictions from the EMC3-Eirene simulations. This suggests that the ‘lobe’ structures due to perturbation fields observed near the X-point are not significantly affected by plasma screening, and can be described by a vacuum approach, as in the EMC3-Eirene. Finally, some effects of the MPs on the L-mode SOL are addressed. (paper)

Elm Farm Organic Research Centre December 2006

OpenAIRE

Sanders, Richard; Whiltley, Andrew; Haigh, Zoe; Clarke, Sarah; Hitchings, Roger; O'Brien, Josie

2006-01-01

The Organic Research Centre. Elm Farm Research Centre Bulletin with Technical Updates from The Organic Advisory Service is a regular publication from The Organic Research Centre. The current issue covers: Report from 2006 Cirencester Conference; Quest for more home produced organic food; in a world where bread matters; Improving wheat with plenty of parents; Unlocking the secrets of the ancient (cereal varieties); Brain food- a good read; Not to late to protect the future: The organic...

SYMPATHETIC SOLAR FILAMENT ERUPTIONS

Energy Technology Data Exchange (ETDEWEB)

Wang, Rui; Liu, Ying D.; Zimovets, Ivan; Hu, Huidong; Yang, Zhongwei [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); Dai, Xinghua, E-mail: liuxying@spaceweather.ac.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2016-08-10

The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.

Modern filaments for composite materials

International Nuclear Information System (INIS)

Krivelli-Viskonti, I.

1982-01-01

Analysis of modern state and ways to improve properties of different filaments for the forecast of the filament application in composite materials has been conducted. In the near future as before the greatest attention will be paid to fibre glass, as this material is widely used in the reinforcing of organic matrices. Carbon and kevlar filaments are the most prospective ones. For the service at medium, high or superhigh temperatures selection of matrix material is more significant than selection of filament. Organic matrices can not be used at temperatures > 250 deg C: this is already the range of metal matrix application. Though at temperatures above room one many filaments can be used, boron filaments and metal wire are the only reinforcing materials, inspite of the fact that carbon filaments are successfully used for metal matrix reinforcing. At very high temperatures only carbon filaments or silicon carbide ones can be used, but their cost is very high and besides economical problems there are many difficulties of technical character

Real-time identification of the resistive-wall-mode in DIII-D with Kalman filter ELM discrimination

International Nuclear Information System (INIS)

Edgell, D.H.; Fransson, C.M.; Humphreys, D.A.; Ferron, J.R.; Garofalo, A.M.; Kim, J.S.; La Haye, R.J.; Okabayashi, M.; Reimerdes, H.; Strait, E.J.; Turnbull, A.D.

2004-01-01

The resistive-wall-mode (RWM) is a major performance-limiting instability in present-day tokamaks. Active control and stabilization of the mode will almost certainly be essential for the success of advanced tokamaks and for the economic viability of tokamak fusion reactors. High performance tokamak plasmas often experience edge-localized-modes (ELMs) which can interfere with RWM identification and control. If the RWM control scheme reacts to an ELM the RWM may be driven unstable instead of controlled. An algorithm for real-time identification of the RWM with discrimination of ELMs in the DIII-D tokamak has been developed using a combination of matched filter and Kalman filter methods. The algorithm has been implemented in DIII-D's real-time plasma control system (PCS) and is available to drive active mode control schemes

Flapping modes of three filaments placed side by side in a free stream

Science.gov (United States)

Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Lu, Xi-Yun

2010-11-01

Flexible filaments flapping in a surrounding flow are useful models for understanding the flow-induced vibration and mimicking the schooling behavior of fish. In the present work, the coupled modes of three identical filaments in a side-by- side arrangement are studied using the linear stability analysis and also an immersed boundary--lattice Boltzmann method for low Reynolds numbers (Re on order of 100). The numerical simulations show that the system dynamics exhibits several patterns that depend on the spacing between the filaments. Among these patterns, three can be predicted by the linear analysis and have been reported before. These modes are: (1) the three filaments all flap in phase; (2) the two outer filaments are out of phase while the middle one is stable; (3) the two outer filaments are in phase while the middle one is out of phase. The simulations also identified two additional modes: (1) the outer two filaments are out of phase while the middle one flaps at a frequency reduced by half; (2) the outer two filaments are out of phase while the middle one flaps at a slightly different frequency. In addition to the vibratory modes, the drag force and the flapping amplitude are also computed, and the implication of the result will be discussed.

Genome-wide analyses of the Dutch elm disease fungi

Science.gov (United States)

Louis. Bernier

2017-01-01

The Ascomycete fungi Ophiostoma ulmi and O. novo-ulmi are the pathogens respectively responsible for the two successive pandemics of Dutch elm disease (DED) since the early 1900s. The advent of the highly fit and virulent O. novo-ulmi was a landmark event in the evolution of DED during the last 100 years....

Methane penetration in DIII-D ELMing H-mode plasmas

International Nuclear Information System (INIS)

West, W.P.; Lasnier, C.J.; Whyte, D.G.; Isler, R.C.; Evans, T.E.; Jackson, G.L.; Rudakov, D.; Wade, M.R.; Strachan, J.

2003-01-01

Carbon penetration into the core plasma during midplane and divertor methane puffing has been measured for DIII-D ELMing H-mode plasmas. The methane puffs are adjusted to a measurable signal, but global plasma parameters are only weakly affected (line average density, e > increases by E , drops by 6+ density profiles in the core measured as a function of time using charge exchange recombination spectroscopy. The methane penetration factor is defined as the difference in the core content with the puff on and puff off, divided by the carbon confinement time and the methane puffing rate. In ELMing H-mode discharges with ion ∇B drift direction into the X-point, increasing the line averaged density from 5 to 8x10 19 m -3 dropped the penetration factor from 6.6% to 4.6% for main chamber puffing. The penetration factor for divertor puffing was below the detection limit (<1%). Changing the ion ∇B drift to away from the X-point decreased the penetration factor by more than a factor of five for main chamber puffing

Analysis of different responses of ion and electron in six-field two-fluid ELM simulations

Science.gov (United States)

Ma, Chenhao; Xu, Xueqiao

2013-10-01

We report simulation results of a Landau-Fluid (GLF) extension of the BOUT++ six-field two-fluid Braginskii model which contributes to increasing the physics understanding of ELMs. Landau-Fluid closure can fill the gap for parallel dynamics between hot, collisionless pedestal region and cold, collisional SOL region in H-mode plasmas. Our goal is extending the classical parallel heat flux with Landau-Fluid closures and making comparisons with other closure models. Our simulations show that for weakly collisional pedestal plasmas, the calculated growth rate with Landau-Fluid closure introduces more effective damping on the peeling-ballooning modes than that with the classical thermal diffusivity. Further nonlinear simulation shows that ELM size with Landau-Fluid Closure is smaller than that with classical thermal diffusivity. We find an ELM crash has two phases: fast initial crash of ion temperature perturbation on the Alfven time scale and slow turbulence spreading. Turbulence transport phase is a slow encroachment of electron temperature perturbation due to the ELM event into pedestal region which is due to a positive phase shift around π / 2 between electron temperature and potential on pedestal region while ion temperature is in-phase with potential. This work was performed under the auspices of the U.S. DoE by LLNL under Contract DE-AC52-07NA27344 and also supported by the China Scholarship Committee under contract N0.2011601099.

ELM-induced melting: assessment of shallow melt layer damage and the power handling capability of tungsten in a linear plasma device

Czech Academy of Sciences Publication Activity Database

Morgan, T.W.; van Eden, G.G.; de Kruif, T.M.; van den Berg, A.; Matějíček, Jiří; Chráska, Tomáš; De Temmerman, G.

-, T159 (2014), 014022-014022 ISSN 0031-8949. [International Conference on Plasma-Facing Materials and Components for Fusion Applications/14./. Jülich, 13.05.2013-17.05.2013] Institutional support: RVO:61389021 Keywords : melting * tungsten * ELMs * divertor * ITER * DEMO Subject RIV: JG - Metallurgy Impact factor: 1.126, year: 2014 http://iopscience.iop.org/1402-4896/2014/T159/014022/pdf/1402-4896_2014_T159_014022.pdf

Experiments on transient melting of tungsten by ELMs in ASDEX Upgrade

Science.gov (United States)

Krieger, K.; Balden, M.; Coenen, J. W.; Laggner, F.; Matthews, G. F.; Nille, D.; Rohde, V.; Sieglin, B.; Giannone, L.; Göths, B.; Herrmann, A.; de Marne, P.; Pitts, R. A.; Potzel, S.; Vondracek, P.; ASDEX-Upgrade Team; EUROfusion MST1 Team

2018-02-01

Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the divertor manipulator II (DIM-II) system (Herrmann et al 2015 Fusion Eng. Des. 98-9 1496-9). Designed as near replicas of the geometries used also in separate experiments on the JET tokamak (Coenen et al 2015 J. Nucl. Mater. 463 78-84 Coenen et al 2015 Nucl. Fusion 55 023010; Matthews et al 2016 Phys. Scr. T167 7), the samples featured a misaligned leading edge and a sloped ridge respectively. Both structures protrude above the default target plate surface thus receiving an increased fraction of the parallel power flux. Transient melting by ELMs was induced by moving the outer strike point to the sample location. The temporal evolution of the measured current flow from the samples to vessel potential confirmed transient melting. Current magnitude and dependency from surface temperature provided strong evidence for thermionic electron emission as main origin of the replacement current driving the melt motion. The different melt patterns observed after exposures at the two sample geometries support the thermionic electron emission model used in the MEMOS melt motion code, which assumes a strong decrease of the thermionic net current at shallow magnetic field to surface angles (Pitts et al 2017 Nucl. Mater. Energy 12 60-74). Post exposure ex situ analysis of the retrieved samples show recrystallization of tungsten at the exposed surface areas to a depth of up to several mm. The melt layer transport to less exposed surface areas leads to ratcheting pile up of re-solidified debris with zonal growth extending from the already enlarged grains at the surface.

The effects of pulse cycloheximide treatments on the light-induced recovery of mitotic divisions in antheridial filaments of Chara vulgaris

Directory of Open Access Journals (Sweden)

Maria Kwiatkowska

2014-01-01

Full Text Available Within the proliferative period of spermatogenesis in Chara vulgaris, the progression throughout successive cell divisions in antheridial filaments is greatly influenced by changes in photoperiodic conditions. The extended (4-day period of total darkness brings about cell cycle arrest in the early G2 phase. The recovery of mitosis requires about 20 hours of exposition to light. In the present study, a series of 8 pulse incubations of plants in cycloheximide (Cx; 2.5 mg/I, 2.5 h each pulse were performed within the period elapsing till the resumption of mitotic divisions. Depending on the time of treatment, the effects induced by Cx vary considerably. Within the first 10 hs of exposition to light, incubations with Cx result in the delays of mitoses; within the period between the 10th and the 17th h, mitotic divisions become blocked, and, following the 17.5 h of light-induced recovery, no influence of Cx is noticed on mitotic activity, as compared with the untreaed control plants. The obtained results provide a starting point for the characteristic of proteins synthesized during the G2 phase and a preliminary study on those mechanisms, which become engaged in the regulation of the G1-deficient cell cycle evidenced in antheridial filaments of Chara.

Collapsing vortex filaments and the spectrum of quantum turbulence

Science.gov (United States)

Andryushchenko, V. A.; Nemirovskii, S. K.

2017-01-01

The method of correlation functions and the method of quantum vortex configurations are used to calculate the energy spectrum of a three-dimensional velocity field that is induced by collapsing (immediately before reconnection) vortex filaments. The formulation of this problem is motivated by the idea of modeling classical turbulence by a set of chaotic quantized vortex filaments. Among the various arguments that support the idea of quasi-classical behavior for quantum turbulence, the most persuasive is probably the resulting Kolmogorov energy spectrum resembling E ( k ) ∝ k - 5 / 3 that was obtained in a number of numerical studies. Another goal is associated with an important and intensely studied theme that relates to the role of hydrodynamic collapse in the formation of turbulence spectra. Calculations have demonstrated that vortex filaments create a velocity field at the moment of contact, which has a singularity. This configuration of vortex filaments generates the spectrum E(k), which bears the resemblance to the Kolmogorov law. A possible cause for this observation is discussed, as well as the likely reasons behind any deviations. The obtained results are discussed from the perspective of both classical and quantum turbulence.

The Glenwood Estate: our 32-year experience using Arbotect® 20-S to control Dutch elm disease

Science.gov (United States)

William L. MacDonald; Mark L. Double; Cameron M. Stauder; Kemp. Winfree

2017-01-01

We report a case study that demonstrates the successful use of the fungicide Arbotect® 20-S to protect American elms (Ulmus americana) from Dutch elm disease at a historic site in Charleston, WV. Standard injection protocols were used every 3 to 4 years to deliver the chemical into the root flares. Twelve of the original 16 trees remain 34 years...

Lateral deflection of the SOL plasma during a giant ELM

International Nuclear Information System (INIS)

Landman, I.S.; Wuerz, H.

2001-01-01

In recent H-mode experiments at JET with giant ELMs a lateral deflection of hot tokamak plasma striking the divertor plate has been observed. This deflection can effect the divertor erosion caused by the hot plasma irradiation. Based on the MHD model for the vapor shield plasma and the hot plasma, the Seebeck effect is analyzed for explanation of the deflection. At t=-∞ both plasmas are at rest and separated by a boundary parallel to the target. The interaction between plasmas develops gradually ('adiabatically') as exp(t/t 0 ) with t 0 ∼10 2 μs the ELM duration time. At inclined impact of the magnetized hot plasma a toroidal current develops in the interaction zone of the plasmas. The JxB force accelerates the interacting plasmas in the lateral direction. The cold plasma motion essentially compensates the current. The magnitude of the hot plasma deflection is comparable to the observed one

Program ELM: A tool for rapid thermal-hydraulic analysis of solid-core nuclear rocket fuel elements

International Nuclear Information System (INIS)

Walton, J.T.

1992-11-01

This report reviews the state of the art of thermal-hydraulic analysis codes and presents a new code, Program ELM, for analysis of fuel elements. ELM is a concise computational tool for modeling the steady-state thermal-hydraulics of propellant flow through fuel element coolant channels in a nuclear thermal rocket reactor with axial coolant passages. The program was developed as a tool to swiftly evaluate various heat transfer coefficient and friction factor correlations generated for turbulent pipe flow with heat addition which have been used in previous programs. Thus, a consistent comparison of these correlations was performed, as well as a comparison with data from the NRX reactor experiments from the Nuclear Engine for Rocket Vehicle Applications (NERVA) project. This report describes the ELM Program algorithm, input/output, and validation efforts and provides a listing of the code

Structure determination of helical filaments by solid-state NMR spectroscopy

Science.gov (United States)

Ahmed, Mumdooh; Spehr, Johannes; König, Renate; Lünsdorf, Heinrich; Rand, Ulfert; Lührs, Thorsten; Ritter, Christiane

2016-01-01

The controlled formation of filamentous protein complexes plays a crucial role in many biological systems and represents an emerging paradigm in signal transduction. The mitochondrial antiviral signaling protein (MAVS) is a central signal transduction hub in innate immunity that is activated by a receptor-induced conversion into helical superstructures (filaments) assembled from its globular caspase activation and recruitment domain. Solid-state NMR (ssNMR) spectroscopy has become one of the most powerful techniques for atomic resolution structures of protein fibrils. However, for helical filaments, the determination of the correct symmetry parameters has remained a significant hurdle for any structural technique and could thus far not be precisely derived from ssNMR data. Here, we solved the atomic resolution structure of helical MAVSCARD filaments exclusively from ssNMR data. We present a generally applicable approach that systematically explores the helical symmetry space by efficient modeling of the helical structure restrained by interprotomer ssNMR distance restraints. Together with classical automated NMR structure calculation, this allowed us to faithfully determine the symmetry that defines the entire assembly. To validate our structure, we probed the protomer arrangement by solvent paramagnetic resonance enhancement, analysis of chemical shift differences relative to the solution NMR structure of the monomer, and mutagenesis. We provide detailed information on the atomic contacts that determine filament stability and describe mechanistic details on the formation of signaling-competent MAVS filaments from inactive monomers. PMID:26733681

Cellular Development Associated with Induced Mycotoxin Synthesis in the Filamentous Fungus Fusarium graminearum

Science.gov (United States)

Menke, Jon; Weber, Jakob; Broz, Karen; Kistler, H. Corby

2013-01-01

Several species of the filamentous fungus Fusarium colonize plants and produce toxic small molecules that contaminate agricultural products, rendering them unsuitable for consumption. Among the most destructive of these species is F. graminearum, which causes disease in wheat and barley and often infests the grain with harmful trichothecene mycotoxins. Synthesis of these secondary metabolites is induced during plant infection or in culture in response to chemical signals. Our results show that trichothecene biosynthesis involves a complex developmental process that includes dynamic changes in cell morphology and the biogenesis of novel subcellular structures. Two cytochrome P-450 oxygenases (Tri4p and Tri1p) involved in early and late steps in trichothecene biosynthesis were tagged with fluorescent proteins and shown to co-localize to vesicles we provisionally call “toxisomes.” Toxisomes, the inferred site of trichothecene biosynthesis, dynamically interact with motile vesicles containing a predicted major facilitator superfamily protein (Tri12p) previously implicated in trichothecene export and tolerance. The immediate isoprenoid precursor of trichothecenes is the primary metabolite farnesyl pyrophosphate. Changes occur in the cellular localization of the isoprenoid biosynthetic enzyme HMG CoA reductase when cultures non-induced for trichothecene biosynthesis are transferred to trichothecene biosynthesis inducing medium. Initially localized in the cellular endomembrane system, HMG CoA reductase, upon induction of trichothecene biosynthesis, increasingly is targeted to toxisomes. Metabolic pathways of primary and secondary metabolism thus may be coordinated and co-localized under conditions when trichothecene biosynthesis occurs. PMID:23667578

Solar Filament Extraction and Characterizing

Science.gov (United States)

Yuan, Yuan; Shih, F. Y.; Jing, J.; Wang, H.

2010-05-01

This paper presents a new method to extract and characterize solar filaments from H-alpha full-disk images produced by Big Bear Solar Observatory. A cascading Hough Transform method is designed to identify solar disk center location and radius. Solar disks are segmented from the background, and unbalanced illumination on the surface of solar disks is removed using polynomial surface fitting. And then a localized adaptive thresholding is employed to extract solar filament candidates. After the removal of small solar filament candidates, the remaining larger candidates are used as the seeds of region growing. The procedure of region growing not only connects broken filaments but also generate complete shape for each filament. Mathematical morphology thinning is adopted to produce the skeleton of each filament, and graph theory is used to prune branches and barbs to get the main skeleton. The length and the location of the main skeleton is characterized. The proposed method can help scientists and researches study the evolution of solar filament, for instance, to detect solar filament eruption. The presented method has already been used by Space Weather Research Lab of New Jersey Institute of Technology (http://swrl.njit.edu) to generate the solar filament online catalog using H-alpha full-disk images of Global H-alpha Network (http://swrl.njit.edu/ghn_web/).

Nonlinear simulation of edge-localized mode in spherical tokamak

International Nuclear Information System (INIS)

Mizuguchi, N.; Hayashi, T.; Nakajima, N.; Khan, R.

2006-10-01

A numerical modeling for the dynamics of an edge-localized mode (ELM) crash in the spherical tokamak is proposed with a consecutive scenario which is initiated by the spontaneous growth of the ballooning mode instability by means of a three-dimensional nonlinear magnetohydrodynamic simulation. The simulation result shows a two-step relaxation process which is induced by the intermediate-n ballooning instability followed by the m/n=1/1 internal kink mode, where m and n represent the poloidal and toroidal mode numbers, respectively. By comparing with the experimental observations, we have found that the simulation result can reproduce several characteristic features of the so-called type-I ELM in an appropriate time scale: (1) relation to the ballooning instability, (2) intermediate-n precursors, (3) low-n structure on the crash, (4) formation and separation of the filament, and (5) considerable amount of loss of plasma. Furthermore, the model is verified by examining the effect of diamagnetic stabilization and comparing the nonlinear behavior with that of the peeling modes. The ion diamagnetic drift terms are found to stabilize some specific components linearly; nevertheless they are not so effective in the nonlinear dynamics such as the filament formation and the amount of loss. For the peeling mode case, no prominent filament structure is formed in contrast to the ballooning case. (author)

Temporal symmetry of individual filaments in different spatial symmetry filaments pattern in a dielectric barrier discharge

International Nuclear Information System (INIS)

Dong, L. F.; Xiao, H.; Fan, W. L.; Yin, Z. Q.; Zhao, H. T.

2010-01-01

The temporal behavior of individual filament in different spatial symmetry filaments patterns in dielectric barrier discharge is investigated by using an optical method. A series of return maps of the discharge moments of individual filaments is given. It is found that the temporal symmetry of individual filament changes with the change of the spatial symmetry of filaments pattern as the applied voltage increases. The role of wall charges for this phenomenon is analyzed.

Magnetic helicity and active filament configuration

Science.gov (United States)

Romano, P.; Zuccarello, F.; Poedts, S.; Soenen, A.; Zuccarello, F. P.

2009-11-01

Context: The role of magnetic helicity in active filament formation and destabilization is still under debate. Aims: Although active filaments usually show a sigmoid shape and a twisted configuration before and during their eruption, it is unclear which mechanism leads to these topologies. In order to provide an observational contribution to clarify these issues, we describe a filament evolution whose characteristics seem to be directly linked to the magnetic helicity transport in corona. Methods: We applied different methods to determine the helicity sign and the chirality of the filament magnetic field. We also computed the magnetic helicity transport rate at the filament footpoints. Results: All the observational signatures provided information on the positive helicity and sinistral chirality of the flux rope containing the filament material: its forward S shape, the orientation of its barbs, the bright and dark threads at 195 Å. Moreover, the magnetic helicity transport rate at the filament footpoints showed a clear accumulation of positive helicity. Conclusions: The study of this event showed a correspondence between several signatures of the sinistral chirality of the filament and several evidences of the positive magnetic helicity of the filament magnetic field. We also found that the magnetic helicity transported along the filament footpoints showed an increase just before the change of the filament shape observed in Hα images. We argued that the photospheric regions where the filament was rooted might be the preferential ways where the magnetic helicity was injected along the filament itself and where the conditions to trigger the eruption were yielded.

Can we determine the filament chirality by the filament footpoint location or the barb-bearing?

Science.gov (United States)

Hao, Qi; Guo, Yang; Fang, Cheng; Chen, Peng-Fei; Cao, Wen-Da

2016-01-01

We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the concept of an unweighted undirected graph and adopt the Dijkstra shortest path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with Hα filtergrams from the Big Bear Solar Observatory (BBSO) Hα archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations.

Can we determine the filament chirality by the filament footpoint location or the barb-bearing?

International Nuclear Information System (INIS)

Hao, Qi; Guo, Yang; Fang, Cheng; Chen, Peng-Fei; Cao, Wen-Da

2016-01-01

We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the concept of an unweighted undirected graph and adopt the Dijkstra shortest path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with Hα filtergrams from the Big Bear Solar Observatory (BBSO) Hα archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations. (paper)

Comparisons of actin filament disruptors and Rho kinase inhibitors as potential antiglaucoma medications

OpenAIRE

Tian, Baohe; Kaufman, Paul L

2012-01-01

Dynamics of the actin cytoskeleton in the trabecular meshwork play a crucial role in the regulation of trabecular outflow resistance. The actin filament disruptors and Rho kinase inhibitors affect the dynamics of the actomyosin system by either disrupting the actin filaments or inhibiting the Rho kinase-activated cellular contractility. Both approaches induce similar morphological changes and resistance decreases in the trabecular outflow pathway, and thus both have potential as antiglaucoma ...

A Nanodiamond-peptide Bioconjugate for Fluorescence and ODMR Microscopy of a Single Actin Filament.

Science.gov (United States)

Genjo, Takuya; Sotoma, Shingo; Tanabe, Ryotaro; Igarashi, Ryuji; Shirakawa, Masahiro

2016-01-01

Recently, the importance of conformational changes in actin filaments induced by mechanical stimulation of a cell has been increasingly recognized, especially in terms of mechanobiology. Despite its fundamental importance, however, long-term observation of a single actin filament by fluorescent microscopy has been difficult because of the low photostability of traditional fluorescent molecules. This paper reports a novel molecular labeling system for actin filaments using fluorescent nanodiamond (ND) particles harboring nitrogen-vacancy centers; ND has flexible chemical modifiability, extremely high photostability and biocompatibility, and provides a variety of physical information quantitatively via optically detected magnetic resonance (ODMR) measurements. We performed the chemical surface modification of an ND with the actin filament-specific binding peptide Lifeact and observed colocalization of pure Lifeact-modified ND and actin filaments by the ODMR selective imaging protocol, suggesting the capability of long-term observation and quantitative analysis of a single molecule by using an ND particle.

Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

CSIR Research Space (South Africa)

Oliphant, CJ

2009-05-01

Full Text Available extensively used for the deposition of various materials, including diamond [1], polymers [2], silicon thin films [3], boron-carbon-nitride layers [4] and carbon nanotubes (CNTs) [5]. The process relies on the catalytic decomposition of precursor gases... (Ho) twice as efficient as a W filament during the deposition of microcrystalline silicon thin films [6]. Reactions between the precursor gases and the heated filament result in changes of the structural properties of the filaments; a process...

Filament wound structure and method

International Nuclear Information System (INIS)

Dritt, W.S.; Gerth, H.L.; Knight, C.E. Jr.; Pardue, R.M.

1977-01-01

A filament wound spherical structure is described comprising a plurality of filament band sets disposed about the surface of a mandrel with each band of each set formed of a continuous filament circumferentially wound about the mandrel a selected number of circuits and with each circuit of filament being wound parallel to and contiguous with an immediate previously wound circuit. Each filament band in each band set is wound at the same helix angle from the axis of revolution of the mandrel and all of the bands of each set are uniformly distributed about the mandrel circumference. The pole-to-equator wall thickness taper associated with each band set, as several contiguous band sets are wound about the mandrel starting at the poles, is accumulative as the band sets are nested to provide a complete filament wound sphere of essentially uniform thickness

High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

International Nuclear Information System (INIS)

Voronin, A. A.; Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A.; Zheltikov, A. M.

2011-01-01

Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-μm laser pulses in high-pressure argon.

Third-harmonic generation and scattering in combustion flames using a femtosecond laser filament.

Science.gov (United States)

Zang, Hong-Wei; Li, He-Long; Su, Yue; Fu, Yao; Hou, Meng-Yao; Baltuška, Andrius; Yamanouchi, Kaoru; Xu, Huailiang

2018-02-01

Coherent radiation in the ultraviolent (UV) range has high potential applicability to the diagnosis of the formation processes of soot in combustion because of the high scattering efficiency in the UV wavelength region, even though the UV light is lost largely by the absorption within the combustion flames. We show that the third harmonic (TH) of a Ti:sapphire 800 nm femtosecond laser is generated in a laser-induced filament in a combustion flame and that the conversion efficiency of the TH varies sensitively by the ellipticity of the driver laser pulse but does not vary so much by the choice of alkanol species introduced as fuel for the combustion flames. We also find that the TH recorded from the side direction of the filament is the Rayleigh scattering of the TH by soot nanoparticles within the flame and that the intensity of the TH varies depending on the fuel species as well as on the position of the laser filament within the flame. Our results show that a remote and in situ measurement of distributions of soot nanoparticles in a combustion flame can be achieved by Rayleigh scattering spectroscopy of the TH generated by a femtosecond-laser-induced filament in the combustion flame.

Repetitive plasma loads typical for ITER Type-I ELMS; simulation in QSPA Kh-50

International Nuclear Information System (INIS)

Tereshin, V.I.; Bandura, A.N.; Byrka, O.V.; Chebotarev, V.V.; Garkusha, I.E.; Makhlaj, V.A.; Solyakov, D.G.; Tsarenko, A.V.; Landman, I.

2005-01-01

The power loads on current tokamaks associated with the Type I ELMs generally do not affect the lifetime of divertor elements. However, the ITER ELMs may lead to unacceptable lifetime; their loads are estimated as QELM(1-3) MJ/m 2 at t = 0.1-1 ms and the repetition frequency of an order of 1 Hz (∼ 400 ELMs during each ITER pulse). Such plasma energy loads expected for ITER ELMs are not achieved in existing tokamaks. Therefore powerful plasma accelerators are used at present for study of plasma-target interaction and for numerical models validation. Quasi-steady-state plasma accelerators (QSPA), which characterized by essentially longer duration of plasma stream generation in comparison with pulsed plasma guns, became especially attractive facilities for investigations of plasma-surface interaction in conditions of high heat loads simulating the ITER disruptions and ELMs. The paper presents experimental study of energy characteristics of the plasma streams generated with quasi-steady-state plasma accelerator QSPA Kh-50 and the main features of plasma interaction with material surfaces in dependence on plasma heat loads. The samples of pure sintered tungsten of EU trademark have been exposed to hydrogen plasma streams produced by the accelerator. To estimate the range of tolerable loads the effects of ELMs on the lifetime of plasma facing components have been experimentally simulated for large numbers of impacts with varying energy density. The experiments were performed with up to 450 pulses of the duration of 0.25 ms and the heat loads in the range of 0.5 - 1.2 MJ/m 2 . At this calorimetry (both at plasma stream and at the target surface), piezo-detectors as well as spectroscopy and interferometry measurements were applied to determine the impacting plasma parameters in different regimes of operation. A threshold character of morphological changes on the tungsten surface under the melting in respect to the pulses number is demonstrated. The number of initial

Menyoal Elaboration Likelihood Model (ELM) dan Teori Retorika

OpenAIRE

Yudi Perbawaningsih

2012-01-01

Abstract: Persuasion is a communication process to establish or change attitudes, which can be understood through theory of Rhetoric and theory of Elaboration Likelihood Model (ELM). This study elaborates these theories in a Public Lecture series which to persuade the students in choosing their concentration of study. The result shows that in term of persuasion effectiveness it is not quite relevant to separate the message and its source. The quality of source is determined by the quality of ...

Menyoal Elaboration Likelihood Model (ELM) Dan Teori Retorika

OpenAIRE

Perbawaningsih, Yudi

2012-01-01

: Persuasion is a communication process to establish or change attitudes, which can be understood through theory of Rhetoric and theory of Elaboration Likelihood Model (ELM). This study elaborates these theories in a Public Lecture series which to persuade the students in choosing their concentration of study. The result shows that in term of persuasion effectiveness it is not quite relevant to separate the message and its source. The quality of source is determined by the quality of the mess...

Improving germination of red elm (Ulmus rubra), gray alder (Alnus incana), and buffaloberry (Shepherdia canadensis) seeds with gibberellic acid

Science.gov (United States)

Brenda Morales; Charles Barden; Cheryl Boyer; Jason Griffin; Lillian Fisher; Joni Thompson

2012-01-01

Red elm (Ulmus rubra), gray alder (Alnus incana), and buffaloberry (Shepherdia canadensis) are considered important plants for many Native American tribes in the United States. Native Americans use these 3 species for a variety of traditional and medicinal purposes. For example, red elm is still the preferred firewood for the cultural ceremonies of several tribes....

Microwave processing of ceramic oxide filaments

Energy Technology Data Exchange (ETDEWEB)

Vogt, G.J.; Katz, J.D. [Los Alamos National Laboratory, NM (United States)

1995-05-01

The objective of the microwave filament processing project is to develop microwave techniques at 2.45 GHZ to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company.

Preliminary investigations of equilibrium reconstruction quality during ELMy and ELM-free phases on JET

International Nuclear Information System (INIS)

Gelfusa, M.; Murari, A.; Peluso, E.; Gaudio, P.; Orsitto, F.P.; Gerasimov, S.

2013-01-01

On JET, the magnetic topology is normally derived from the code EFIT, which solves the Grad–Shafranov equation with constraints imposed by the available measurements, typically the pick-up coils. Both the code and the measurements are expected to perform worse during ELMs. To assess this hypothesis, various statistical indicators, based on the values of the residuals and their probability distribution, have been calculated. They all show that the quality of EFIT reconstructions is clearly better in absence of ELMs. How the responsibility, for the lower quality of the reconstructions, is shared between the measurements and EFIT is a subject under investigation. © 2001 Elsevier Science. All rights reserved

Feature Optimize and Classification of EEG Signals: Application to Lie Detection Using KPCA and ELM

Directory of Open Access Journals (Sweden)

GAO Junfeng

2014-04-01

Full Text Available EEG signals had been widely used to detect liars recent years. To overcome the shortcomings of current signals processing, kernel principal component analysis (KPCA and extreme learning machine (ELM was combined to detect liars. We recorded the EEG signals at Pz from 30 randomly divided guilty and innocent subjects. Each five Probe responses were averaged within subject and then extracted wavelet features. KPCA was employed to select feature subset with deduced dimensions based on initial wavelet features, which was fed into ELM. To date, there is no perfect solution for the number of its hidden nodes (NHN. We used grid searching algorithm to select simultaneously the optimal values of the dimension of feature subset and NHN based on cross- validation method. The best classification mode was decided with the optimal searching values. Experimental results show that for EEG signals from the experiment of lie detection, KPCA_ELM has higher classification accuracy with faster training speed than other widely-used classification modes, which is especially suitable for online EEG signals processing system.

Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D

Science.gov (United States)

Moyer, R. A.; Paz-Soldan, C.; Nazikian, R.; Orlov, D. M.; Ferraro, N. M.; Grierson, B. A.; Knölker, M.; Lyons, B. C.; McKee, G. R.; Osborne, T. H.; Rhodes, T. L.; Meneghini, O.; Smith, S.; Evans, T. E.; Fenstermacher, M. E.; Groebner, R. J.; Hanson, J. M.; La Haye, R. J.; Luce, T. C.; Mordijck, S.; Solomon, W. M.; Turco, F.; Yan, Z.; Zeng, L.; DIII-D Team

2017-10-01

Experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) to ITER-relevant levels of beam torque. The results support the hypothesis for RMP ELM suppression based on transition from an ideal screened response to a tearing response at a resonant surface that prevents expansion of the pedestal to an unstable width [Snyder et al., Nucl. Fusion 51, 103016 (2011) and Wade et al., Nucl. Fusion 55, 023002 (2015)]. In ITER baseline plasmas with I/aB = 1.4 and pedestal ν * ˜ 0.15, ELMs are readily suppressed with co- I p neutral beam injection. However, reducing the beam torque from 5 Nm to ≤ 3.5 Nm results in loss of ELM suppression and a shift in the zero-crossing of the electron perpendicular rotation ω ⊥ e ˜ 0 deeper into the plasma. The change in radius of ω ⊥ e ˜ 0 is due primarily to changes to the electron diamagnetic rotation frequency ωe * . Linear plasma response modeling with the resistive MHD code m3d-c1 indicates that the tearing response location tracks the inward shift in ω ⊥ e ˜ 0. At pedestal ν * ˜ 1, ELM suppression is also lost when the beam torque is reduced, but the ω ⊥ e change is dominated by collapse of the toroidal rotation v T . The hypothesis predicts that it should be possible to obtain ELM suppression at reduced beam torque by also reducing the height and width of the ωe * profile. This prediction has been confirmed experimentally with RMP ELM suppression at 0 Nm of beam torque and plasma normalized pressure β N ˜ 0.7. This opens the possibility of accessing ELM suppression in low torque ITER baseline plasmas by establishing suppression at low beta and then increasing beta while relying on the strong RMP-island coupling to maintain suppression.

Solar Features - Prominences and Filaments - Filaments

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Filaments are formed in magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun (David Hathaway/NASA)

On lateral deflection of the SOL plasma in tokamaks during giant ELMs

International Nuclear Information System (INIS)

Landman, I.S.; Wuerz, H.

2000-06-01

In recent H-mode experiments at JET with giant ELMs a lateral deflection of hot tokamak plasma leaving the scrape-off layer and striking the divertor plate has been observed. This deflection can effect the divertor erosion caused by the hot plasma irradiation, because of enlarging the irradiated area. A simplified MHD model of the vapor shield plasma and of the hot plasma initially formed at time t → -∞ is analyzed. At t = -∞ both plasmas are assumed to stay on rest and to be separated by a boundary, which is parallel to the plate surface. The interaction between plasmas is assumed to develop gradually ('adiabatically') as exp(t/t 0 ) with t 0 ∝ 10 2 μs the ELM duration time. Electrical insulation of the core tokamak plasma is assumed everywhere except for the contact with the divertor. Electric currents are flowing only in the toroidal direction. These currents developing in the interaction zone of the hot plasma and the rather cold target plasma are calculated for inclined impact of the magnetized hot plasma. At such conditions the J x B force in the lateral direction accelerates the interacting plasmas. The motion of the cold plasma and the gradual increase of the plasma interaction intensity are shown to be important for the appropriate deflection magnitude. Adiabatically responding against the increase of the interaction intensity the cold plasma motion compensates significantly the currents thus decreasing the deflection compared to motionless approach. The calculated magnitude of the hot plasma deflection is comparable to the observed one. The results of the modeling are discussed in relation to the experiments. It is shown that sudden switching on of the interaction produces Alfven oscillations of large amplitudes causing much larger amplitudes of the magnetic field induced by the currents than in the adiabatic case. (orig.)

THE ELM SURVEY. II. TWELVE BINARY WHITE DWARF MERGER SYSTEMS

International Nuclear Information System (INIS)

Kilic, Mukremin; Brown, Warren R.; Kenyon, S. J.; Prieto, Carlos Allende; Agueeros, M. A.; Heinke, Craig

2011-01-01

We describe new radial velocity and X-ray observations of extremely low-mass white dwarfs (ELM WDs, ∼0.2 M sun ) in the Sloan Digital Sky Survey Data Release 4 and the MMT Hypervelocity Star survey. We identify four new short period binaries, including two merger systems. These observations bring the total number of short period binary systems identified in our survey to 20. No main-sequence or neutron star companions are visible in the available optical photometry, radio, and X-ray data. Thus, the companions are most likely WDs. Twelve of these systems will merge within a Hubble time due to gravitational wave radiation. We have now tripled the number of known merging WD systems. We discuss the characteristics of this merger sample and potential links to underluminous supernovae, extreme helium stars, AM CVn systems, and other merger products. We provide new observational tests of the WD mass-period distribution and cooling models for ELM WDs. We also find evidence for a new formation channel for single low-mass WDs through binary mergers of two lower mass objects.

Tungsten Filament Fire

Science.gov (United States)

Ruiz, Michael J.; Perkins, James

2016-01-01

We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent…

Fine filament NbTi superconductive composite

International Nuclear Information System (INIS)

Hong, S.; Grabinsky, G.; Marancik, W.; Pattanayak, D.

1986-01-01

The large superconducting magnet for the high energy physics accelerator requires fine filament composite to minimize the field error due to the persistent current in the filaments. New concepts toward the fine filament composite and its cable fabrication are discussed. Two-stage cables of fine wire with intermediate number of filaments were introduced. The first stage was six wires cables around one and in the second stage this was used to produce a Rutherford cable. The advantage of this process is in the ease of billet fabrication since the number of filaments in a single wire is within the range of easy billet fabrication. The disadvantage is in the cable fabrication. One of the major concerns in the fabrication of fine NbTi filaments composite in a copper matrix is the intermetallic compound formation during the extrusion and heat treatment steps. The hard intermetallic particles degrade the uniformity of the filaments and reduce the critical current density. The process of using Nb barrier between the filaments and copper matrix in order to prevent this CuTi intermetallic particle formation is described

Numerical Modeling of Edge-Localized-Mode Filaments on Divertor Plates Based on Thermoelectric Currents

International Nuclear Information System (INIS)

Wingen, A.; Spatschek, K. H.; Evans, T. E.; Lasnier, C. J.

2010-01-01

Edge localized modes (ELMs) are qualitatively and quantitatively modeled in tokamaks using current bursts which have been observed in the scrape-off-layer (SOL) during an ELM crash. During the initial phase of an ELM, a heat pulse causes thermoelectric currents. They first flow in short connection length flux tubes which are initially established by error fields or other nonaxisymmetric magnetic perturbations. The currents change the magnetic field topology in such a way that larger areas of short connection length flux tubes emerge. Then currents predominantly flow in short SOL-like flux tubes and scale with the area of the flux tube assuming a constant current density. Quantitative predictions of flux tube patterns for a given current are in excellent agreement with measurements of the heat load and current flow at the DIII-D target plates during an ELM cycle.

Stability of two-dimensional vorticity filaments

International Nuclear Information System (INIS)

Elhmaidi, D.; Provenzale, A.; Lili, T.; Babiano, A.

2004-01-01

We discuss the results of a numerical study on the stability of two-dimensional vorticity filaments around a circular vortex. We illustrate how the stability of the filaments depends on the balance between the strain associated with the far field of the vortex and the local vorticity of the filament, and we discuss an empirical criterion for filament stability

Edge stability and performance of the ELM-free quiescent H-mode and the quiescent double barrier mode on DIII-D

International Nuclear Information System (INIS)

West, W.P.; Burrell, K.H.; Snyder, P.B.; Gohil, P.; Lao, L.L.; Leonard, A.W.; Osborne, T.H.; Thomas, D.M.; Casper, T.A.; Lasnier, C.J.; Doyle, E.J.; Wang, G.; Zeng, L.; Nave, M.F.F.

2005-01-01

The quiescent H (QH) mode, an edge localized mode (ELM)-free, high-confinement mode, combines well with an internal transport barrier to form quiescent double barrier (QDB) stationary state, high performance plasmas. The QH-mode edge pedestal pressure is similar to that seen in ELMing phases of the same discharge, with similar global energy confinement. The pedestal density in early ELMing phases of strongly pumped counter injection discharges drops and a transition to QH-mode occurs, leading to lower calculated edge bootstrap current. Plasmas current ramp experiment and ELITE code modeling of edge stability suggest that QHmodes lie near an edge current stabilty boundary. At high triangularity, QH-mode discharges operate at higher pedestal density and pressure, and have achieved ITER level values of β PED and ν*. The QDB achieves performance of β N H 89 ∼ 7 in quasi-stationary conditions for a duration of 10 τ E , limited by hardware. Recently we demonstrated stationary state QDB discharges with little change in kinetic and q profiles (q 0 > 1) for 2 s, comparable to ELMing 'hybrid scenarios', yet without the debilitating effects of ELMs. Plasma profile control tools, including electron cyclotron heating and current drive and neutral beam heating, have been demonstrated to control simultaneously the q profile development, the density peaking, impurity accumulation and plasma beta. (author)

Wettability dynamics of liquid filaments on horizontal substrates

Science.gov (United States)

Diez, Javier; Ravazzoli, Pablo; Cuellar, Ingrith; Gonzalez, Alejandro

2017-11-01

We study the hydrodynamic mechanisms involved in the motion of the contact line formed at the end region of a liquid filament laying on a planar and horizontal substrate. Since the flow develops under partially wetting conditions, the tip of the filament recedes and forms a bulged region (head) that subsequently develops a neck region behind it. Later the neck breaks up leading to a separated drop, while the rest of the filament restarts the sequence. One main feature of this flow is that the whole dynamics and final drop shapes are strongly influenced by the hysteresis of the contact angle typical in most of the liquid-substrate systems. The time evolution till breakup is studied experimentally and pictured in terms of a hybrid wettability theory which involves the Cox-Voinov hydrodynamic approach combined with the molecular kinetic theory developed by Blake. The parameters of this theory are determined for our liquid-substrate system (silicone oil ``coated glass). The experimental results of the retracting filament are described in terms of a simple heuristic model and compared with numerical simulations of the full Navier-Stokes equations. This study is of special interest in the context of pulsed laser-induced dewetting. The authors acknowledge support from Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET, Argentina) with Grant PIP 844/2012 and Agencia Nacional de Promocin Cientfica y Tecnolgica (ANPCyT, Argentina) with Grant PICT 931/2012.

Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator

International Nuclear Information System (INIS)

Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

2013-01-01

The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA

Unwinding motion of a twisted active region filament

Energy Technology Data Exchange (ETDEWEB)

Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)

2014-12-10

To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

Filaments and clusters of galaxies

International Nuclear Information System (INIS)

Soltan, A.

1987-01-01

A statistical test to investigate filaments of galaxies is performed. Only particular form of filaments is considered, viz. filaments connecting Abell clusters of galaxies. Relative position of triplets ''cluster - field object - cluster'' is analysed. Though neither cluster sample nor field object sample are homogeneous and complete only peculiar form of selection effects could affect the present statistics. Comparison of observational data with simulations shows that less than 15 per cent of all field galaxies is concentrated in filaments connecting rich clusters. Most of the field objects used in the analysis are not normal galaxies and it is possible that this conclusion is not in conflict with apparent filaments seen in the Lick counts and in some nearby 3D maps of the galaxy distribution. 26 refs., 2 figs. (author)

Neonicotinoid Insecticide Imidacloprid Causes Outbreaks of Spider Mites on Elm Trees in Urban Landscapes

Science.gov (United States)

Szczepaniec, Adrianna; Creary, Scott F.; Laskowski, Kate L.; Nyrop, Jan P.; Raupp, Michael J.

2011-01-01

Background Attempts to eradicate alien arthropods often require pesticide applications. An effort to remove an alien beetle from Central Park in New York City, USA, resulted in widespread treatments of trees with the neonicotinoid insecticide imidacloprid. Imidacloprid's systemic activity and mode of entry via roots or trunk injections reduce risk of environmental contamination and limit exposure of non-target organisms to pesticide residues. However, unexpected outbreaks of a formerly innocuous herbivore, Tetranychus schoenei (Acari: Tetranychidae), followed imidacloprid applications to elms in Central Park. This undesirable outcome necessitated an assessment of imidacloprid's impact on communities of arthropods, its effects on predators, and enhancement of the performance of T. schoenei. Methodology/Principal Findings By sampling arthropods in elm canopies over three years in two locations, we document changes in the structure of communities following applications of imidacloprid. Differences in community structure were mostly attributable to increases in the abundance of T. schoenei on elms treated with imidacloprid. In laboratory experiments, predators of T. schoenei were poisoned through ingestion of prey exposed to imidacloprid. Imidacloprid's proclivity to elevate fecundity of T. schoenei also contributed to their elevated densities on treated elms. Conclusions/Significance This is the first study to report the effects of pesticide applications on the arthropod communities in urban landscapes and demonstrate that imidacloprid increases spider mite fecundity through a plant-mediated mechanism. Laboratory experiments provide evidence that imidacloprid debilitates insect predators of spider mites suggesting that relaxation of top-down regulation combined with enhanced reproduction promoted a non-target herbivore to pest status. With global commerce accelerating the incidence of arthropod invasions, prophylactic applications of pesticides play a major role in

The H-mode pedestal, ELMs and TF ripple effects in JT-60U/JET dimensionless identity experiments

International Nuclear Information System (INIS)

Saibene, G.; Oyama, N.; Loennroth, J.; Andrew, Y.; Luna, E. de la; Giroud, C.; Huysmans, G.T.A.; Kamada, Y.; Kempenaars, M.A.H.; Loarte, A.; Donald, D. Mc; Nave, M.M.F.; Meiggs, A.; Parail, V.; Sartori, R.; Sharapov, S.; Stober, J.; Suzuki, T.; Takechi, M.; Toi, K.; Urano, H.

2007-01-01

This paper summarizes results of dimensionless identity experiments in JT-60U and JET, aimed at the comparison of the H-mode pedestal and ELM behaviour in the two devices. Given their similar size, dimensionless matched plasmas are also similar in their dimensional parameters (in particular, the plasma minor radius a is the same in JET and JT-60U). Power and density scans were carried out at two values of I p , providing a q scan (q 95 = 3.1 and 5.1) with fixed (and matched) toroidal field. Contrary to initial expectations, a dimensionless match between the two devices was quite difficult to achieve. In general, p ped in JT-60U is lower than in JET and, at low q, the pedestal pressure of JT-60U with a Type I ELMy edge is matched in JET only in the Type III ELM regime. At q 95 = 5.1, a dimensionless match in ρ*, ν* and β p,ped is obtained with Type I ELMs, but only with low power JET H-modes. These results motivated a closer investigation of experimental conditions in the two devices, to identify possible 'hidden' physics that prevents obtaining a good match of pedestal values over a large range of plasmas parameters. Ripple-induced ion losses of the medium bore plasma used in JT-60U for the similarity experiments are identified as the main difference with JET. The magnitude of the JT-60U ripple losses is sufficient to induce counter-toroidal rotation in co-injected plasma. The influence of ripple losses was demonstrated at q 95 = 5.1: reducing ripple losses by ∼2 (from 4.3 to 1.9 MW) by replacing positive with negative neutral beam injection at approximately constant P in resulted in an increased p ped in JT-60U, providing a good match to full power JET H-modes. At the same time, the counter-toroidal rotation decreased. Physics mechanisms relating ripple losses to pedestal performance are not yet identified, and the possible role of velocity shear in the pedestal stability, as well as the possible influence of ripple on thermal ion transport are briefly

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

DEFF Research Database (Denmark)

Rørdam Preil, Simone; Faarvang Thorsen, Anne-Sofie; Christiansen, Anne Lindegaard

2017-01-01

BACKGROUND: Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression i......BACKGROUND: Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered m......RNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM. METHODS: Blood samples from 302 type 2 diabetic patients were...... analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index. RESULTS: T2DM...

Evolution of Filament Barbs

OpenAIRE

Liu, Rui; Xu, Yan; Wang, Haimin

2010-01-01

We present a selected few cases in which the sense of chirality of filament barbs changed within as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes only one overlay a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward and then departed ...

Variability of morphometric caracteristics of one-year seedlings of different half-sib European White Elm (Ulmus effusa Wild. from the Great War Island

Directory of Open Access Journals (Sweden)

Devetaković, J.

2013-12-01

Full Text Available European White Elm is recognized as a rare and endangered species in the forest fund of the Republic of Serbia. During the past century massive drying of elms occurred and the indications of their extinction appeared, which consequently led to a reduction in genetic diversity and the danger of genetic drift. In the area of the Great War Island near Belgrade we found 56 trees of European White Elm that are spatially divided into three subpopulations. In order to assess the genetic potential of European White Elm in the Great War Island and to define adequate conservation measures variability of 14 selected test trees progeny was rated. Results shows that the satisfactory variability within the popoulation exists, which is a good basis for the conservation of genepool available.

New Techniques For The Improvement Of The ICRH System ELM Tolerance On JET

Science.gov (United States)

Monakhov, I.; Blackman, T.; Walden, A.; Nightingale, M.; Whitehurst, A.; Durodie, F.; Jet Efda Contributors

2003-12-01

Two complementary improvements to the ELM tolerance of the existing A2 antennas on JET are being assessed. The use of external conjugate-T matching of straps of adjacent antenna arrays could reduce the VSWR levels at RF amplifier output during fast load perturbations. The scheme under consideration uses coaxial line-stretchers (trombones) for tuning the conjugate-T to low resistive impedance (3-6 Ohm) with subsequent stub/trombone circuit impedance transformation to 30 Ohms. Another technique is to modify the RF plant protection system logic to reduce the high VSWR trip duration to an absolute minimum corresponding to a typical ELM response (˜1-2ms) without compromising the plant safety. Both projects are presently being tested and could increase the average power delivered by RF plant into ELMy plasmas at JET.

An ELM-Based Approach for Estimating Train Dwell Time in Urban Rail Traffic

Directory of Open Access Journals (Sweden)

Wen-jun Chu

2015-01-01

Full Text Available Dwell time estimation plays an important role in the operation of urban rail system. On this specific problem, a range of models based on either polynomial regression or microsimulation have been proposed. However, the generalization performance of polynomial regression models is limited and the accuracy of existing microsimulation models is unstable. In this paper, a new dwell time estimation model based on extreme learning machine (ELM is proposed. The underlying factors that may affect urban rail dwell time are analyzed first. Then, the relationships among different factors are extracted and modeled by ELM neural networks, on basis of which an overall estimation model is proposed. At last, a set of observed data from Beijing subway is used to illustrate the proposed method and verify its overall performance.

PROGRESS IN THE PEELING-BALLOONING MODEL OF ELMS: TOROIDAL ROTATION AND 3D NONLINEAR DYNAMICS

International Nuclear Information System (INIS)

SNYDER, P.B.; WILSON, H.R.; XU, X.Q.; WEBSTER, A.J.

2004-01-01

Understanding the physics of the H-Mode pedestal and edge localized modes (ELMs) is very important to next-step fusion devices for two primary reasons: (1) The pressure at the top of the edge barrier (''pedestal height'') strongly impacts global confinement and fusion performance, and (2) large ELMs lead to localized transient heat loads on material surfaces that may constrain component lifetimes. The development of the peeling-ballooning model has shed light on these issues by positing a mechanism for ELM onset and constraints on the pedestal height. The mechanism involves instability of ideal coupled ''peeling-ballooning'' modes driven by the sharp pressure gradient and consequent large bootstrap current in the H-mode edge. It was first investigated in the local, high-n limit [1], and later quantified for non-local, finite-n modes in general toroidal geometry [2,3]. Important aspects are that a range of wavelengths may potentially be unstable, with intermediate n's (n ∼ 3-30) generally limiting in high performance regimes, and that stability bounds are strongly sensitive to shape [Fig l(a)], and to collisionality (i.e. temperature and density) [4] through the bootstrap current. The development of efficient MHD stability codes such as ELITE [3,2] and MISHKA [5] has allowed detailed quantification of peeling-ballooning stability bounds (e.g. [6]) and extensive and largely successful comparisons with observation (e.g. [2,6-9]). These previous calculations are ideal, static, and linear. Here we extend this work to incorporate the impact of sheared toroidal rotation, and the non-ideal, nonlinear dynamics which must be studied to quantify ELM size and heat deposition on material surfaces

SOLPS5 modelling of the type III ELMing H-mode on TCV

International Nuclear Information System (INIS)

Gulejova, B.; Pitts, R.A.; Wischmeier, M.; Behn, R.; Coster, D.; Horacek, J.; Marki, J.

2007-01-01

Although ohmic H-modes have long been produced on TCV and the effects of ELMs at the divertor target studied in some detail, no attempt has yet been made to model the scrape-off layer (SOL) in these plasmas. This paper describes details of the first such efforts in which simulations of the inter-ELM phases using the coupled fluid-Monte Carlo SOLPS5 code (without drifts) are constrained by careful upstream Thomson scattering and Langmuir probe profiles. Simulated divertor profiles are compared with Langmuir probes and fast IR camera measurements at the targets. To account for the very differing transport rates in the edge pedestal and main SOL regions, radial variation of edge transport coefficients has been introduced in the simulations. Similarly, it is found that transport in the main chamber and divertor regions must be separately adjusted to provide an acceptable code-experiment match

Electron emitting filaments for electron discharge devices

International Nuclear Information System (INIS)

Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

1988-01-01

This patent describes an electron emitting device for use in an electron discharge system. It comprises: a filament having a pair of terminal ends, electrical supply means for supplying electrical power to the terminal ends of the filament for directly heating the filament by the passage of an electrical current along the filament between the terminal ends, the filament being substantially tapered in cross section continuously in one direction from one of its pair of terminal ends to another of its pair of terminal ends to achieve uniform heating of the filament along the length thereof by compensating for the nonuniform current along the filament due to the emission of electrons therefrom

Analysis of a filament stretching rheometer

DEFF Research Database (Denmark)

Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

1996-01-01

A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown.......A finite element analysis of the stretching filament rheometer of Tirtaadmadja and Sridhar (1993) is presenetd. Simulations of the stretching of a filament of the polymet test solution, fluid A, between two plates are shown....

Mathematical modeling of alignment dynamics in active motor-filament systems

Science.gov (United States)

Swaminathan, Sumanth

The formation of the cytoskeleton, via motor-mediated microtubule self-organization, is an important subject of study in the biological sciences as well as in nonequilibrium, soft matter physics. Accurate modeling of the dynamics is a formidable task as it involves intrinsic nonlinearities, structural anisotropies, nonequilibrium processes, and a broad window of time scales, length scales, and densities. In this thesis, we study the ordering dynamics and pattern formations arising from motor-mediated microtubule self-organization in dilute and semi-dilute filament solutions. In the dilute case, we use a probabilistic model in which microtubules interact through motor induced, inelastic binary collisions. This model shows that initially disordered filament solutions exhibit an ordering transition resulting in the emergence of well aligned rod bundles. We study the existence and dynamic interaction of microtubule bundles analytically and numerically. Our results show a long term attraction and coalescing of bundles indicating a clear coarsening in the system; microtubule bundles concentrate into fewer orientations on a slow logarithmic time scale. In the semi-dilute case, multiple motors can bind a filament to several others and, for a critical motor density, induce a transition to an ordered state with a nonzero mean orientation. We develop a spatially homogeneous, mean-field theory that explicitly accounts for motor forcing and thermal fluctuations which enter into the model as multiplicative and additive noises respectively. Our model further incorporates a force-dependent detachment rate of motors, which in turn affects the mean and the fluctuations of the net force acting on a filament. We demonstrate that the transition to the oriented state changes from second order to first order when the force-dependent detachment becomes important. In our final analysis, we add complex spatial inhomogeneities to our mean field theory. The revised model consists of a system

Density profile analysis during an ELM event in ASDEX Upgrade H-modes

International Nuclear Information System (INIS)

Nunes, I.; Manso, M.; Serra, F.; Horton, L.D.; Conway, G.D.; Loarte, A.

2005-01-01

This paper reports results on measurements of the density profiles. Here we analyse the behaviour of the electron density for a set of experiments in type I ELMy H-mode discharges in ASDEX Upgrade where the plasma current, plasma density, triangularity and input power were varied. Detailed measurements of the radial extent of the perturbation on the density profiles caused by the edge localized mode (ELM) crash (ELM affected depth), the velocity of the radial propagation of the perturbation as well as the width and gradient of the density pedestal are determined. The effect of a type I ELM event on the density profiles affects the outermost 20-40% of the plasma minor radius. At the scrape-off layer (SOL) the density profile broadens while in the pedestal region the density decreases resulting in a smaller density gradient. This change in the density profile defines a pivot point around which the density profile changes. The average radial velocity at the SOL is in the range 125-150 ms -1 and approximately constant for all the density layers far from the pivot point. The width of the density pedestal is approximately constant for all the ELMy H-mode discharges analysed, with values between 2 and 3.5 cm. These results are then compared with an analytical model where the width of the density is predominantly set by ionization (neutral penetration model). The width of the density profiles for L-mode discharges is included, since L- and H-mode have different particle transport. No agreement between the experimental results and the model is found

Modelling ELM heat flux deposition on the ITER main chamber wall

Czech Academy of Sciences Publication Activity Database

Kočan, M.; Pitts, R.A.; Lisgo, S.W.; Loarte, A.; Gunn, J. P.; Fuchs, Vladimír

2015-01-01

Roč. 463, July (2015), s. 709-713 ISSN 0022-3115. [International Conference on Plasma-Surface Interactions in Controlled Fusion Devices (PSI)/21./. Kanazawa, 26.05.2014-30.05.2014] Institutional support: RVO:61389021 Keywords : ELM * ITER Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 2.199, year: 2015

The importance of subfragment 2 and C-terminus of myosin heavy chain for thick filament assembly in skeletal muscle cells.

Science.gov (United States)

Ojima, Koichi; Oe, Mika; Nakajima, Ikuyo; Shibata, Masahiro; Muroya, Susumu; Chikuni, Koichi; Hattori, Akihito; Nishimura, Takanori

2015-04-01

In skeletal muscle cells, myofibrillar proteins are highly organized into sarcomeres in which thick filaments interdigitate with thin filaments to generate contractile force. The size of thick filaments, which consist mainly of myosin molecules, is strictly controlled. However, little is known about the mechanisms by which myosin molecules assemble into thick filaments. Here, we assessed the ability of each domain of myosin heavy chain (Myh) to form thick filaments. We showed that exogenously expressed subfragment 2 (S2) + light meromyosin (LMM) of Myh was efficiently incorporated into thick filaments in muscle cells, although neither solely expressed S2 nor LMM targeted to thick filaments properly. In nonmuscle COS7 cells, S2+LMM formed more enlarged filaments/speckles than LMM. These results suggest that Myh filament formation is induced by S2 accompanying LMM. We further examined the effects of Myh C-terminus on thick filament assembly. C-terminal deletion mutants were incorporated not into entire thick filaments but rather into restricted regions of thick filaments. Our findings suggest that the elongation of myosin filaments to form thick filaments is regulated by S2 as well as C-terminus of LMM. © 2014 Japanese Society of Animal Science.

Proteomics of Filamentous Fungi

NARCIS (Netherlands)

Passel, van M.W.J.; Schaap, P.J.; Graaff, de L.H.

2013-01-01

Filamentous fungi, such as Aspergillus niger and Aspergillus oryzae traditionally have had an important role in providing enzymes and enzyme cocktails that are used in food industry. In recent years the genome sequences of many filamentous fungi have become available. This combined with

The Mysterious Case of the Missing Filaments

Science.gov (United States)

Alden, C. R.

2016-12-01

Coronal Mass Ejections, or CMEs, are large solar eruptions that can have major debilitating impacts on society. Typically, these eruptions have the three following key structures: the leading edge, the empty chamber known as the cavity, and the filament which often is the brightest part of the CME. When we can see all three structures clearly with a coronagraph, it is called a classic three-part CME, also referred to as a 'lightbulb' CME. According to current knowledge, when a CME erupts, a filament should also erupt or lift off the Sun in order to have the bright center within the CME. However, we do not always see a filament erupt at the surface, and yet we still get a 'filament' within the coronagraph CME. To better understand what might be occurring with these missing filaments, we looked at three-part CMEs using the SOHO LASCO CME Catalog and filaments from the SDO AIA Filament Catalog in order to create a list of 50 CMEs without a listed filament erupting at the surface. For those CMEs without filaments in the list we closely inspected the AIA images for evidence of filament eruption. To ensure that there were no filaments past the limb of the Sun, we used data from the STEREO-A and STEREO-B spacecraft's to look at the Sun from other angles. We have found numerous events where no filament erupts from the surface, but we still see the classic three-part CME. We believe this may be due to an optical illusion occurring from the twisting of the flux rope.

Role of Intermediate Filaments in Vesicular Traffic

Directory of Open Access Journals (Sweden)

Azzurra Margiotta

2016-04-01

Full Text Available Intermediate filaments are an important component of the cellular cytoskeleton. The first established role attributed to intermediate filaments was the mechanical support to cells. However, it is now clear that intermediate filaments have many different roles affecting a variety of other biological functions, such as the organization of microtubules and microfilaments, the regulation of nuclear structure and activity, the control of cell cycle and the regulation of signal transduction pathways. Furthermore, a number of intermediate filament proteins have been involved in the acquisition of tumorigenic properties. Over the last years, a strong involvement of intermediate filament proteins in the regulation of several aspects of intracellular trafficking has strongly emerged. Here, we review the functions of intermediate filaments proteins focusing mainly on the recent knowledge gained from the discovery that intermediate filaments associate with key proteins of the vesicular membrane transport machinery. In particular, we analyze the current understanding of the contribution of intermediate filaments to the endocytic pathway.

Correlated waves of actin filaments and PIP3 in Dictyostelium cells.

Science.gov (United States)

Asano, Yukako; Nagasaki, Akira; Uyeda, Taro Q P

2008-12-01

Chemotaxis-deficient amiB-null mutant Dictyostelium cells show two distinct movements: (1) they extend protrusions randomly without net displacements; (2) they migrate persistently and unidirectionally in a keratocyte-like manner. Here, we monitored the intracellular distribution of phosphatidylinositol (3,4,5)-trisphosphate (PIP(3)) to gain insight into roles PIP(3) plays in those spontaneous motilities. In keratocyte-like cells, PIP(3) showed convex distribution over the basal membrane, with no anterior enrichment. In stalled cells, as well as in wild type cells, PIP(3) repeated wave-like changes, including emergence, expansion and disappearance, on the basal membrane. The waves induced lamellipodia when they approached the cell edge, and the advancing speed of the waves was comparable to the migration speed of the keratocyte-like cells. LY294002, an inhibitor of PI3 kinase, abolished PIP(3) waves in stalled cells and stopped keratocyte-like cells. These results together suggested that keratocyte-like cells are "surfing" on the PIP(3) waves by coupling steady lamellipodial protrusions to the PIP(3) waves. Simultaneous live observation of actin filaments and PIP(3) in wild type or stalled amiB(-) cells indicated that the PIP(3) waves were correlated with wave-like distributions of actin filaments. Most notably, PIP(3) waves often followed actin waves, suggesting that PIP(3) induces local depolymerization of actin filaments. Consistent with this idea, cortical accumulation of PIP(3) was often correlated with local retraction of the periphery. We propose that the waves of PIP(3) and actin filaments are loosely coupled with each other and play important roles in generating spontaneous cell polarity. Copyright 2008 Wiley-Liss, Inc.

THE ELM SURVEY. I. A COMPLETE SAMPLE OF EXTREMELY LOW-MASS WHITE DWARFS

International Nuclear Information System (INIS)

Brown, Warren R.; Kilic, Mukremin; Kenyon, Scott J.; Prieto, Carlos Allende

2010-01-01

We analyze radial velocity observations of the 12 extremely low-mass (ELM), with ≤0.25 M sun , white dwarfs (WDs) in the MMT Hypervelocity Star Survey. Eleven of the twelve WDs are binaries with orbital periods shorter than 14 hr; the one non-variable WD is possibly a pole-on system among our non-kinematically selected targets. Our sample is unique: it is complete in a well-defined range of apparent magnitude and color. The orbital mass functions imply that the unseen companions are most likely other WDs, although neutron star companions cannot be excluded. Six of the eleven systems with orbital solutions will merge within a Hubble time due to the loss of angular momentum through gravitational wave radiation. The quickest merger is J0923+3028, a g = 15.7 ELM WD binary with a 1.08 hr orbital period and a ≤130 Myr merger time. The chance of a supernova Ia event among our ELM WDs is only 1%-7%, however. Three binary systems (J0755+4906, J1233+1602, and J2119-0018) have extreme mass ratios and will most likely form stable mass-transfer AM CVn systems. Two of these objects, SDSS J1233+1602 and J2119-0018, are the lowest surface gravity WDs ever found; both show Ca II absorption likely from accretion of circumbinary material. We predict that at least one of our WDs is an eclipsing detached double WD system, important for constraining helium core WD models.

Soliton on thin vortex filament

International Nuclear Information System (INIS)

Konno, Kimiaki; Mituhashi, Masahiko; Ichikawa, Y.H.

1990-12-01

Showing that one of the equations found by Wadati, Konno and Ichikawa is equivalent to the equation of motion of a thin vortex filament, we investigate solitons on the vortex filament. N vortex soliton solution is given in terms of the inverse scattering method. We examine two soliton collision processes on the filament. Our analysis provides the theoretical foundation of two soliton collision processes observed numerically by Aref and Flinchem. (author)

Aquifer test to determine hydraulic properties of the Elm aquifer near Aberdeen, South Dakota

Science.gov (United States)

Schaap, Bryan D.

2000-01-01

The Elm aquifer, which consists of sandy and gravelly glacial-outwash deposits, is present in several counties in northeastern South Dakota. An aquifer test was conducted northeast of Aberdeen during the fall of 1999 to determine the hydraulic properties of the Elm aquifer in that area. An improved understanding of the properties of the aquifer will be useful in the possible development of the aquifer as a water resource. Historical water-level data indicate that the saturated thickness of the Elm aquifer can change considerably over time. From September 1977 through November 1985, water levels at three wells completed in the Elm aquifer near the aquifer test site varied by 5.1 ft, 9.50 ft, and 11.1 ft. From June 1982 through October 1999, water levels at five wells completed in the Elm aquifer near the aquifer test site varied by 8.7 ft, 11.4 ft, 13.2 ft, 13.8 ft, and 19.7 ft. The water levels during the fall of 1999 were among the highest on record, so the aquifer test was affected by portions of the aquifer being saturated that might not be saturated during drier times. The aquifer test was conducted using five existing wells that had been installed prior to this study. Well A, the pumped well, has an operating irrigation pump and is centrally located among the wells. Wells B, C, D, and E are about 70 ft, 1,390 ft, 2,200 ft, and 3,100 ft, respectively, in different directions from Well A. Using vented pressure transducers and programmable data loggers, water-level data were collected at the five wells prior to, during, and after the pumping, which started on November 19, 1999, and continued a little over 72 hours. Based on available drilling logs, the Elm aquifer near the test area was assumed to be unconfined. The Neuman (1974) method theoretical response curves that most closely match the observed water-level changes at Wells A and B were calculated using software (AQTESOLV for Windows Version 2.13-Professional) developed by Glenn M. Duffield of Hydro

Striation and convection in penumbral filaments

NARCIS (Netherlands)

Spruit, H.C.; Scharmer, G.B.; Löfdahl, M.G.

2010-01-01

Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward

The effects of a low-intensity red laser on bacterial growth, filamentation and plasmid DNA

International Nuclear Information System (INIS)

Roos, C; Santos, J N; Guimarães, O R; Geller, M; Fonseca, A S; Paoli, F

2013-01-01

Exposure of nonphotosynthesizing microorganisms to light could increase cell division in cultures, a phenomenon denominated as biostimulation. However, data concerning the importance of the genetic characteristics of cells on this effect are as yet scarce. The aim of this work was to evaluate the effects of a low-intensity red laser on the growth, filamentation and plasmids in Escherichia coli cells proficient and deficient in DNA repair. E. coli cultures were exposed to a laser (658 nm, 10 mW, 1 and 8 J cm −2 ) to study bacterial growth and filamentation. Also, bacterial cultures hosting pBSK plasmids were exposed to the laser to study DNA topological forms from the electrophoretic profile in agarose gels. Data indicate the low-intensity red laser: (i) had no effect on the growth of E. coli wild type and exonuclease III deficient cells; (ii) induced bacterial filamentation, (iii) led to no alteration in the electrophoretic profile of plasmids from exonuclease III deficient cells, but plasmids from wild type cells were altered. A low-intensity red laser at the low fluences used in phototherapy has no effect on growth, but induces filamentation and alters the topological forms of plasmid DNA in E. coli cultures depending on the DNA repair mechanisms. (paper)

Boolean gates on actin filaments

International Nuclear Information System (INIS)

Siccardi, Stefano; Tuszynski, Jack A.; Adamatzky, Andrew

2016-01-01

Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications. - Highlights: • We simulate interaction between voltage pulses using on actin filaments. • We use a coupled nonlinear transmission line model. • We design Boolean logical gates via interactions between the voltage pulses. • We construct one-bit half-adder with interacting voltage pulses.

Boolean gates on actin filaments

Energy Technology Data Exchange (ETDEWEB)

Siccardi, Stefano, E-mail: ssiccardi@2ssas.it [The Unconventional Computing Centre, University of the West of England, Bristol (United Kingdom); Tuszynski, Jack A., E-mail: jackt@ualberta.ca [Department of Oncology, University of Alberta, Edmonton, Alberta (Canada); Adamatzky, Andrew, E-mail: andrew.adamatzky@uwe.ac.uk [The Unconventional Computing Centre, University of the West of England, Bristol (United Kingdom)

2016-01-08

Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications. - Highlights: • We simulate interaction between voltage pulses using on actin filaments. • We use a coupled nonlinear transmission line model. • We design Boolean logical gates via interactions between the voltage pulses. • We construct one-bit half-adder with interacting voltage pulses.

Segmentation and abnormality detection of cervical cancer cells using fast elm with particle swarm optimization

Directory of Open Access Journals (Sweden)

Sukumar P.

2015-01-01

Full Text Available Cervical cancer arises when the anomalous cells on the cervix mature unmanageable obviously in the renovation sector. The most probably used methods to detect abnormal cervical cells are the routine and there is no difference between the abnormal and normal nuclei. So that the abnormal nuclei found are brown in color while normal nuclei are blue in color. The spread or cells are examined and the image denoising is performed based on the Iterative Decision Based Algorithm. Image Segmentation is the method of paneling a digital image into compound sections. The major utilize of segmentation is to abridge or modify the demonstration of an image. The images are segmented by applying anisotropic diffusion on the Denoised image. Image can be enhanced using dark stretching to increase the quality of the image. It separates the cells into all nuclei region and abnormal nuclei region. The abnormal nuclei regions are further classified into touching and non-touching regions and touching regions undergoes feature selection process. The existing Support Vector Machines (SVM is classified few nuclei regions but the time to taken for execution is high. The abnormality detected from the image is calculated as 45% from the total abnormal nuclei. Thus the proposed method of Fast Particle Swarm Optimization with Extreme Learning Machines (Fast PSO-ELM to classify all nuclei regions further into touching region and separated region. The iterative method for to training the ELM and make it more efficient than the SVM method. In experimental result, the proposed method of Fast PSO-ELM may shows the accuracy as above 90% and execution time is calculated based on the abnormality (ratio of abnormal nuclei regions to all nuclei regions image. Therefore, Fast PSO-ELM helps to detect the cervical cancer cells with maximum accuracy.

Filament networks attached to membranes: cytoskeletal pressure and local bilayer deformation

International Nuclear Information System (INIS)

Auth, Thorsten; Safran, S A; Gov, Nir S

2007-01-01

Several cell types, among them red blood cells, have a cortical, two-dimensional (2D) network of filaments sparsely attached to their lipid bilayer. In many mammalian cells, this 2D polymer network is connected to an underlying 3D, more rigid cytoskeleton. In this paper, we consider the pressure exerted by the thermally fluctuating, cortical network of filaments on the bilayer and predict the bilayer deformations that are induced by this pressure. We treat the filaments as flexible polymers and calculate the pressure that a network of such linear chains exerts on the bilayer; we then minimize the bilayer shape in order to predict the resulting local deformations. We compare our predictions with membrane deformations observed in electron micrographs of red blood cells. The polymer pressure along with the resulting membrane deformation can lead to compartmentalization, regulate in-plane diffusion and may influence protein sorting as well as transmit signals to the polymerization of the underlying 3D cytoskeleton

Solar filament material oscillations and drainage before eruption

International Nuclear Information System (INIS)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Dan; Yang, Bo

2014-01-01

Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar filament are associated with the flow of material along the filament axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a filament eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the Hα images from the Global Oscillation Network Group. Hours before the eruption, the filament was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the filament relative to the solar surface. After the active phase, LAL oscillations were observed in the inclined filament. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the filament evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of filament material was drained toward one filament endpoint, followed immediately by the violent eruption of the filament. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the filament material drainage could play a role in the transition from a slow to a fast rise of the erupting filament.

Theory and theory-based models for the pedestal, edge stability and ELMs in tokamaks

International Nuclear Information System (INIS)

Guzdar, P.N.; Mahajan, S.M.; Yoshida, Z.; Dorland, W.; Rogers, B.N.; Bateman, G.; Kritz, A.H.; Pankin, A.; Voitsekhovitch, I.; Onjun, T.; Snyder, S.

2005-01-01

Theories for equilibrium and stability of H-modes, and models for use within integrated modeling codes with the objective of predicting the height, width and shape of the pedestal at the edge of H-mode plasmas in tokamaks, as well as the onset and frequency of Edge Localized Modes (ELMs), are developed. A theory model for relaxed plasma states with flow, which uses two-fluid Hall-MHD equations, predicts that the natural scale length of the pedestal is the ion skin depth and the pedestal width is larger than the ion poloidal gyro-radius, in agreement with experimental observations. Computations with the GS2 code are used to identify micro-instabilities, such as electron drift waves, that survive the strong flow shear, diamagnetic flows, and magnetic shear that are characteristic of the pedestal. Other instabilities on the pedestal and gyro-radius scale, such as the Kelvin-Helmholtz instability, are also investigated. Time-dependent integrated modeling simulations are used to follow the transition from L-mode to H-mode and the subsequent evolution of ELMs as the heating power is increased. The flow shear stabilization that produces the transport barrier at the edge of the plasma reduces different modes of anomalous transport and, consequently, different channels of transport at different rates. ELM crashes are triggered in the model by pressure-driven ballooning modes or by current-driven peeling modes. (author)

Coherent structures in the boundary plasma of EAST Tokamak

DEFF Research Database (Denmark)

Yan, Ning

In recent years, with the application of fast camera in fusion plasma, as well as other diagnostic of spatial-temporal resolution such as Langmuir probe, it has become generally clear that the turbulence transport is mostly dominant by cross-field propagation of coherent structures, namely blobs...... or filaments in low-confinement mode (L-mode). Analogously, the fine structures associated with the edge-localized modes (ELMs), i.e., ELM filaments, have been shown to be the main carriers of the transport in the high-confinement mode (H-mode). The filaments carry particles and heat, impinging upon the plasma......-facing material, leading to intensive transient heat load and particle load on the local areas of both the divertor target plates and the first wall, which damages the material and causes enhanced recycling and impurity generation, then further pollutes the core plasma. In this project, we carried out experiment...

Prediction of Solar Eruptions Using Filament Metadata

Science.gov (United States)

Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal

2018-05-01

We perform a statistical analysis of erupting and non-erupting solar filaments to determine the properties related to the eruption potential. In order to perform this study, we correlate filament eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK filaments that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each filament instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting filament tracks to discover which properties present signs of an eruption. We find that a change in filament length over time is the most important factor in discriminating between erupting and non-erupting filament tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive filament metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the current metadata is only slightly better than chance.

Comparison of edge plasma perturbation during ELM control using one vs. two toroidal rows of RMP coils in ITER similar shaped plasmas on DIII-D

Energy Technology Data Exchange (ETDEWEB)

Fenstermacher, M.E., E-mail: fenstermacher@fusion.gat.co [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Evans, T.E.; Osborne, T.H.; Schaffer, M.J.; DeGrassie, J.S.; Gohil, P.; Groebner, R.J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Moyer, R.A. [University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093 (United States)

2009-06-15

Large Type-I edge localized modes (ELMs) were suppressed by n = 3 resonant magnetic perturbations (RMPs) from a set of internal coils in plasmas with an ITER similar shape at the ITER pedestal collisionality, nu{sub e}*approx0.1 and low edge safety factor (q{sub 95} approx 3.6), with either a single toroidal row of the internal RMP coils or two poloidally separated rows of coils. ELM suppression with a single row of internal coils was achieved at approximately the same q{sub 95} surface-averaged perturbation field as with two rows of coils, but required higher current per coil. Maintaining complete suppression of ELMs using n = 3 RMPs from a single toroidal row of internal coils was less robust to variations in input neutral beam injection torque than previous ELM suppression cases using both rows of internal coils. With either configuration of RMP coils, maximum ELM size is correlated with the width of the edge region having good overlap of the magnetic islands from vacuum field calculations.

Translation elongation factor EF-Tu modulates filament formation of actin-like MreB protein in vitro.

Science.gov (United States)

Defeu Soufo, Hervé Joël; Reimold, Christian; Breddermann, Hannes; Mannherz, Hans G; Graumann, Peter L

2015-04-24

EF-Tu has been shown to interact with actin-like protein MreB and to affect its localization in Escherichia coli and in Bacillus subtilis cells. We have purified YFP-MreB in an active form, which forms filaments on glass slides in vitro and was active in dynamic light-scattering assays, polymerizing in milliseconds after addition of magnesium. Purified EF-Tu enhanced the amount of MreB filaments, as seen by sedimentation assays, the speed of filament formation and the length of MreB filaments in vitro. EF-Tu had the strongest impact on MreB filaments in a 1:1 ratio, and EF-Tu co-sedimented with MreB filaments, revealing a stoichiometric interaction between both proteins. This was supported by cross-linking assays where 1:1 species were well detectable. When expressed in E. coli cells, B. subtilis MreB formed filaments and induced the formation of co-localizing B. subtilis EF-Tu structures, indicating that MreB can direct the positioning of EF-Tu structures in a heterologous cell system. Fluorescence recovery after photobleaching analysis showed that MreB filaments have a higher turnover in B. subtilis cells than in E. coli cells, indicating different filament kinetics in homologous or heterologous cell systems. The data show that MreB can direct the localization of EF-Tu in vivo, which in turn positively affects the formation and dynamics of MreB filaments. Thus, EF-Tu is a modulator of the activity of a bacterial actin-like protein. Copyright © 2015. Published by Elsevier Ltd.

Temperature distributions of a conductively heated filament

International Nuclear Information System (INIS)

Tamura, Koji; Ohba, Hironori; Shibata, Takemasa

1999-07-01

Temperature distributions of a heated filament were measured. A W-Re(5%) filament (0.25 mm in diameter, 24.7 mm in length) was conductively heated by currents between 5A and 7A with a DC power supply, and the surface of the filament was imaged with a charge coupled device (CCD) camera through a monochromatic filter. The spectral radiation intensity at the filament center region was almost uniform. Since the temperature distribution was also uniform and the energy loss by thermal conduction was negligible, temperature in this region was determined from the energy balance between applied power and radiation loss. Temperature distribution of the filament was determined based on the Planck's law of radiation from the spectral radiation intensity ratio of the filament surface using obtained temperature as a reference. It was found that temperature distribution of a filament was easily measured by this method. (author)

Measuring Filament Orientation: A New Quantitative, Local Approach

Energy Technology Data Exchange (ETDEWEB)

Green, C.-E.; Cunningham, M. R.; Jones, P. A. [School of Physics, University of New South Wales, Sydney, NSW, 2052 (Australia); Dawson, J. R. [CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia); Novak, G. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Fissel, L. M. [National Radio Astronomy Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA, 22903 (United States)

2017-09-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”.

Measuring Filament Orientation: A New Quantitative, Local Approach

Science.gov (United States)

Green, C.-E.; Dawson, J. R.; Cunningham, M. R.; Jones, P. A.; Novak, G.; Fissel, L. M.

2017-09-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

Measuring Filament Orientation: A New Quantitative, Local Approach

International Nuclear Information System (INIS)

Green, C.-E.; Cunningham, M. R.; Jones, P. A.; Dawson, J. R.; Novak, G.; Fissel, L. M.

2017-01-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

ELMs and constraints on the H-mode pedestal: peeling-ballooning stability calculation and comparison with experiment

International Nuclear Information System (INIS)

Snyder, P.B.; Ferron, J.R.; Wilson, H.R.

2004-01-01

We review and test the peeling-ballooning model for edge localized modes (ELMs) and pedestal constraints, a model based upon theoretical analysis of magnetohydrodynamic (MHD) instabilities that can limit the pedestal height and drive ELMs. A highly efficient MHD stability code, ELITE, is used to calculate quantitative stability constraints on the pedestal, including constraints on the pedestal height. Because of the impact of collisionality on the bootstrap current, these pedestal constraints are dependent on the density and temperature separately, rather than simply on the pressure. ELITE stability calculations are directly compared with experimental data for a series of plasmas in which the density is varied and ELM characteristics change. In addition, a technique is developed whereby peeling-ballooning pedestal constraints are calculated as a function of key equilibrium parameters via ELITE calculations using series of model equilibria. This technique is used to successfully compare the expected pedestal height as a function of density, triangularity and plasma current with experimental data. Furthermore, the technique can be applied for parameter ranges beyond the purview of present experiments, and we present a brief projection of peeling-ballooning pedestal constraints for burning plasma tokamak designs. (author)

Solar Features - Prominences and Filaments

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Prominences and filaments are two manifestations of the same phenomenon. Both prominences and filaments are features formed above the chromosphere by cool dense...

ELM phenomenon as an interaction between bootstrap-current driven peeling modes and pressure-driven ballooning modes

International Nuclear Information System (INIS)

Saarelma, S.; Kurki-Suonio, T.; Guenter, S.; Zehrfeld, H.-P.

2000-01-01

An ELMy ASDEX Upgrade plasma equilibrium is reconstructed taking into account the bootstrap current. The peeling mode stability of the equilibrium is numerically analysed using the GATO [1] code, and it is found that the bootstrap current can drive the plasma peeling mode unstable. A high-n ballooning mode stability analysis of the equilibria revealed that, while destabilizing the peeling modes, the bootstrap current has a stabilizing effect on the ballooning modes. A combination of these two instabilities is a possible explanation for the type I ELM phenomenon. A triangularity scan showed that increasing triangularity stabilizes the peeling modes and can produce ELM-free periods observed in the experiments. (author)

Edge transport barrier formation and ELM phenomenology in the W7-AS stellarator

International Nuclear Information System (INIS)

Grigull, P.; Hirsch, M.; Baldzuhn, J.; Ehmler, H.; Gadelmeier, F.; Giannone, L.; Hartfuss, H.-J.; Hildebrandt, D.; Jaenicke, R.; Kisslinger, J.; Koenig, R.; McCormick, K.; Wagner, F.; Weller, A.; Wendland, Ch.

2001-01-01

In NBI discharges with density ramps in W7-AS, the quiescent H-mode is restricted to the same ranges of the edge rotational transform as in ECRH discharges and occurs above threshold densities ≥10 20 m -3 which increase with heating power. Higher power needs higher density for stabilization. The approach to the quiescent H-mode often occurs, with increasing density and decreasing power flow through the edge, from grassy through dithering states to bursts of ELMs and, in a few cases, quasi-periodic ELMs. This goes parallel with increasing radial gradients of the plasma pressure and E-field at the edge. Higher heating power reduces in particular the T i gradients and hence the E-field gradients, which effect can be compensated by higher density. The correlations found are fairly consistent when an ExB flow shear decorrelation of the turbulent transport is assumed

Automatic Detect and Trace of Solar Filaments

Science.gov (United States)

Fang, Cheng; Chen, P. F.; Tang, Yu-hua; Hao, Qi; Guo, Yang

We developed a series of methods to automatically detect and trace solar filaments in solar Hα images. The programs are able to not only recognize filaments and determine their properties, such as the position, the area and other relevant parameters, but also to trace the daily evolution of the filaments. For solar full disk Hα images, the method consists of three parts: first, preprocessing is applied to correct the original images; second, the Canny edge-detection method is used to detect the filaments; third, filament properties are recognized through the morphological operators. For each Hα filament and its barb features, we introduced the unweighted undirected graph concept and adopted Dijkstra shortest-path algorithm to recognize the filament spine; then, using polarity inversion line shift method for measuring the polarities in both sides of the filament to determine the filament axis chirality; finally, employing connected components labeling method to identify the barbs and calculating the angle between each barb and spine to indicate the barb chirality. Our algorithms are applied to the observations from varied observatories, including the Optical & Near Infrared Solar Eruption Tracer (ONSET) in Nanjing University, Mauna Loa Solar Observatory (MLSO) and Big Bear Solar Observatory (BBSO). The programs are demonstrated to be effective and efficient. We used our method to automatically process and analyze 3470 images obtained by MLSO from January 1998 to December 2009, and a butterfly diagram of filaments is obtained. It shows that the latitudinal migration of solar filaments has three trends in the Solar Cycle 23: The drift velocity was fast from 1998 to the solar maximum; after the solar maximum, it became relatively slow and after 2006, the migration became divergent, signifying the solar minimum. About 60% filaments with the latitudes larger than 50 degree migrate towards the Polar Regions with relatively high velocities, and the latitudinal migrating

High-resolution Observations of Sympathetic Filament Eruptions by NVST

Energy Technology Data Exchange (ETDEWEB)

Li, Shangwei; Su, Yingna; Zhou, Tuanhui; Ji, Haisheng [Key Laboratory for Dark Matter and Space Science, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Van Ballegooijen, Adriaan [5001 Riverwood Avenue, Sarasota, FL 34231 (United States); Sun, Xudong, E-mail: ynsu@pmo.ac.cn [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2017-07-20

We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts first, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions failed, since the filaments first rise up, then flow toward the south and merge into the southern large quiescent filament. We also observe repeated activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.

Surface damage of W exposed to combined stationary D plasma and ELMs-like pulsed plasma

Energy Technology Data Exchange (ETDEWEB)

Jia, Y.Z., E-mail: jaja880816@aliyun.com [Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu, Sichuan 610213 (China); Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, W., E-mail: liuw@mail.tsinghua.edu.cn [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Xu, B.; Qu, S.L. [Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Morgan, T.W. [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, 5612AJ Eindhoven (Netherlands)

2017-04-15

The surface damage of W under D plasma and ELMs-like transient heat loads was studied by combined stationary and pulsed D plasma. Low-flux transient heat loads will promote blister formation due to the gas expansion inside the blisters. On the contrary, high-flux transient heat loads will mitigate blistering due to the high surface temperature. Therefore, blistering on W surface first increased and then decreased with the increasing transient heat loads. The promotion effect of pulsed plasma on blistering is more obvious on [001] and [110] surfaces than on [111] surface, and the orientation dependence of blisters was mitigated by the transient heat loads. Surface modification induced by transient heat loads only formed on [001] and [110] surfaces, but did not form on [111] surface. The orientation dependence of surface modification was mainly due to the slipping system of dislocations.

Striation and convection in penumbral filaments

Science.gov (United States)

Spruit, H. C.; Scharmer, G. B.; Löfdahl, M. G.

2010-10-01

Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward propagating striations with inclination angles suggesting that they are aligned with the local magnetic field. We interpret it as the equivalent of the striations seen in the walls of small isolated magnetic structures. Their origin is then a corrugation of the boundary between an overturning convective flow inside the filament and the magnetic field wrapping around it. The outward propagation is a combination of a pattern motion due to the downflow observed along the sides of bright filaments, and the Evershed flow. The observed short wavelength of the striation argues against the existence of a dynamically significant horizontal field inside the bright filaments. Its intensity contrast is explained by the same physical effect that causes the dark cores of filaments, light bridges and “canals”. In this way striation represents an important clue to the physics of penumbral structure and its relation with other magnetic structures on the solar surface. We put this in perspective with results from the recent 3-D radiative hydrodynamic simulations. 4 movies are only available in electronic form at http://www.aanda.org

Direct observation of current in type-I edge-localized-mode filaments on the ASDEX upgrade tokamak

DEFF Research Database (Denmark)

Vianello, N.; Zuin, M.; Cavazzana, R.

2011-01-01

Magnetically confined plasmas in the high confinement regime are regularly subjected to relaxation oscillations, termed edge localized modes (ELMs), leading to large transport events. Present ELM theories rely on a combined effect of edge current and the edge pressure gradients which result...

Massive sequencing of Ulmus minor's transcriptome provides new molecular tools for a genus under the constant threat of Dutch elm disease

Directory of Open Access Journals (Sweden)

Pedro ePerdiguero

2015-07-01

Full Text Available Elms, especially Ulmus minor and Ulmus americana, are carrying out a hard battle against Dutch elm disease (DED. This vascular wilt disease, caused by Ophiostoma ulmi and O. novo-ulmi, appeared in the twentieth century and killed millions of elms across North America and Europe. Elm breeding and conservation programmes have identified a reduced number of DED tolerant genotypes. In this study, three U. minor genotypes with contrasted levels of tolerance to DED were exposed to several biotic and abiotic stresses in order to (i obtain a de novo assembled transcriptome of U. minor using 454 pyrosequencing, (ii perform a functional annotation of the assembled transcriptome, (iii identify genes potentially involved in the molecular response to environmental stress, and (iv develop gene-based markers to support breeding programmes. A total of 58,429 putative unigenes were identified after assembly and filtering of the transcriptome. 32,152 of these unigenes showed homology with proteins identified in the genome from the most common plant model species. Well-known family proteins and transcription factors involved in abiotic, biotic or both stresses were identified after functional annotation. A total of 30,693 polymorphisms were identified in 7,125 isotigs, a large number of them corresponding to SNPs (27,359. In a subset randomly selected for validation, 87 % of the SNPs were confirmed. The material generated may be valuable for future Ulmus gene expression, population genomics and association genetics studies, especially taking into account the scarce molecular information available for this genus and the great impact that DED has on elm populations.

A new intelligent classifier for breast cancer diagnosis based on a rough set and extreme learning machine: RS + ELM

OpenAIRE

KAYA, Yılmaz

2014-01-01

Breast cancer is one of the leading causes of death among women all around the world. Therefore, true and early diagnosis of breast cancer is an important problem. The rough set (RS) and extreme learning machine (ELM) methods were used collectively in this study for the diagnosis of breast cancer. The unnecessary attributes were discarded from the dataset by means of the RS approach. The classification process by means of ELM was performed using the remaining attributes. The Wisconsin B...

Simulation of tungsten erosion and transport near the divertor plate during ELMs by a kinetic method

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhenyue; Sang, Chaofeng; Hu, Wanpeng; Du, Hailong; Wang, Dezhen, E-mail: wangdez@dlut.edu.cn

2016-11-01

Highlights: • A kinetic method is used to simulate tungsten erosion and transport during ELMs. • The erosion of tungsten plate by different species (deuterium and carbon ions) is shown. • The charge states of sputtered tungsten particles are given statistically. - Abstract: Tungsten (W) is fore seen as one of the most important candidates of the plasma-facing materials (PFM) for future fusion devices, due to its beneficial properties. However, the high-Z characteristic makes it a potential contamination to the core plasma. Divertor is the main component that directly contacts the plasma, therefore, it is very important to understand the erosion of W divertor plate and the corresponding transport of the eroded wall impurity, especially during edge localized modes (ELMs). In this work, a one-dimension-in-space and three-dimensions-in-velocity particle-in-cell code (EPPIC1D) is used to simulate the erosion of W divertor plate, and the transport of eroded W impurity near the divertor plate is studied by a Monte Carlo code. Benefiting from the kinetic simulation, energy/particle flux to the target could be calculated accurately, and the erosion of W plate by different species is simulated during ELMs. The trajectories and distributions of eroded W impurity particles are demonstrated, which shows us a basic idea of how these impurity particles are generated and transported. It is found that C{sup 3+} plays a dominated role on the erosion of W divertor plate during ELMs even when its concentration is low. Both W atoms and ions distribute mainly near the divertor plate, indicating only a very small fraction of W impurity particles could escape from divertor region and penetrate into the core plasma.

Evolution of filament barbs.

Science.gov (United States)

Liu, R.; Xu, Y.; Wang, H.

We present a selected few cases in which the sense of chirality of filament barbs changed within periods as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes, only one overlays a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward, and then departed from, each other in Halpha , with the barb endpoints migrating as far as ˜ 10 arcsec. We conclude that the evolution of the barbs was driven by flux emergence and cancellation of small bipolar units at the EFC border.

WICH, a member of WASP-interacting protein family, cross-links actin filaments

International Nuclear Information System (INIS)

Kato, Masayoshi; Takenawa, Tadaomi

2005-01-01

In yeast, Verprolin plays an important role in rearrangement of the actin cytoskeleton. There are three mammalian homologues of Verprolin, WIP, CR16, and WICH, and all of them bind actin and Wiskott-Aldrich syndrome protein (WASP) and/or neural-WASP. Here, we describe a novel function of WICH. In vitro co-sedimentation analysis revealed that WICH not only binds to actin filaments but also cross-links them. Fluorescence and electron microscopy detected that this cross-linking results in straight bundled actin filaments. Overexpression of WICH alone in cultured fibroblast caused the formation of thick actin fibers. This ability of WICH depended on its own actin cross-linking activity. Importantly, the actin cross-linking activity of WICH was modified through a direct association with N-WASP. Taken together, these data suggest that WICH induces a bundled form of actin filament with actin cross-linking activity and the association with N-WASP suppresses that activity. WICH thus appears to be a novel actin bundling protein

Simulation of residual thermostress in tungsten after repetitive ELM-like heat loads

Energy Technology Data Exchange (ETDEWEB)

Pestchanyi, S., E-mail: serguei.pestchanyi@kit.edu [Karlsruhe Institute of Technology, IHM (Germany); Garkusha, I. [Institute of Plasma Physics of the NSC KIPT, Kharkov (Ukraine); Landman, I. [Karlsruhe Institute of Technology, IHM (Germany)

2011-10-15

Brittle destruction of tungsten armour under action of edge localised modes of plasma instabilities (ELMs) in ITER is an important issue determining the lifetime of the divertor. Besides, cracking of the armour produces tungsten dust with characteristic size of 1-10 {mu}m flying from the armour surface with velocities up to 10 m/s. Influx of the tungsten dust into the ITER confinement decreases the temperature of the plasma, reduces the thermonuclear gain and even may run the confinement into disruption. This paper describes experiments in QSPA-Kh50 plasma gun and modeling, which has been performed for providing more insight into the physics of tungsten cracking under action of ELMs and for confirmation of the important result on stabilization of the crack development at the tungsten armour surface, predicted in our previous paper - the same authors, 2010. The threshold value of energy density deposition for start of tungsten cracking has been measured as 0.3 MJ/m{sup 2} after 5-10 shots. From analytical considerations three times smaller threshold value has been predicted with increasing number of shots.

Simulation of residual thermostress in tungsten after repetitive ELM-like heat loads

International Nuclear Information System (INIS)

Pestchanyi, S.; Garkusha, I.; Landman, I.

2011-01-01

Brittle destruction of tungsten armour under action of edge localised modes of plasma instabilities (ELMs) in ITER is an important issue determining the lifetime of the divertor. Besides, cracking of the armour produces tungsten dust with characteristic size of 1-10 μm flying from the armour surface with velocities up to 10 m/s. Influx of the tungsten dust into the ITER confinement decreases the temperature of the plasma, reduces the thermonuclear gain and even may run the confinement into disruption. This paper describes experiments in QSPA-Kh50 plasma gun and modeling, which has been performed for providing more insight into the physics of tungsten cracking under action of ELMs and for confirmation of the important result on stabilization of the crack development at the tungsten armour surface, predicted in our previous paper - the same authors, 2010. The threshold value of energy density deposition for start of tungsten cracking has been measured as 0.3 MJ/m 2 after 5-10 shots. From analytical considerations three times smaller threshold value has been predicted with increasing number of shots.

Rift Valley fever phlebovirus NSs protein core domain structure suggests molecular basis for nuclear filaments.

Science.gov (United States)

Barski, Michal; Brennan, Benjamin; Miller, Ona K; Potter, Jane A; Vijayakrishnan, Swetha; Bhella, David; Naismith, James H; Elliott, Richard M; Schwarz-Linek, Ulrich

2017-09-15

Rift Valley fever phlebovirus (RVFV) is a clinically and economically important pathogen increasingly likely to cause widespread epidemics. RVFV virulence depends on the interferon antagonist non-structural protein (NSs), which remains poorly characterized. We identified a stable core domain of RVFV NSs (residues 83-248), and solved its crystal structure, a novel all-helical fold organized into highly ordered fibrils. A hallmark of RVFV pathology is NSs filament formation in infected cell nuclei. Recombinant virus encoding the NSs core domain induced intranuclear filaments, suggesting it contains all essential determinants for nuclear translocation and filament formation. Mutations of key crystal fibril interface residues in viruses encoding full-length NSs completely abrogated intranuclear filament formation in infected cells. We propose the fibrillar arrangement of the NSs core domain in crystals reveals the molecular basis of assembly of this key virulence factor in cell nuclei. Our findings have important implications for fundamental understanding of RVFV virulence.

Dutch elm disease: an overview of the biology and management regimens

Science.gov (United States)

R. Jay. Stipes

2017-01-01

Much of the information on the Dutch elm disease (DED) topic was generated by a large group of dedicated scientists, in several different agencies, primarily in the United States and Europe, over the last century. My work on the fungicidal management is but a modest contribution to the whole. It goes without saying that much more work needs to be done to open up new...

Effect of stationary high heat flux and transient ELMs-like heat loads on the divertor PFCs

Energy Technology Data Exchange (ETDEWEB)

Riccardi, B., E-mail: bruno.riccardi@f4e.europa.eu [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Gavila, P. [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Giniatulin, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Kuznetsov, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Rulev, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Klimov, N.; Kovalenko, D.; Barsuk, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Koidan, V.; Korshunov, S. [NRC “Kurchatov Institute”, Moscow (Russian Federation)

2013-10-15

The experimental evaluation of the divertor plasma facing components (PFCs) lifetime under transient events, such as edge localized modes (ELMs) and high heat flux (HHF) thermal fatigue expected during ITER normal operations and slow transient events is here presented. The experiments have been performed in the frame of an EU/RF collaboration. For carbon fiber composite material the erosion is caused by PAN fiber damage whilst the erosion of tungsten is determined by the melt layer movement and crack formation. The conclusion of this study is that, in addition to the structural change produced in the armor materials by ELMs-like loads, some mock ups showed also a degradation of the thermal fatigue performances.

Power exhaust on JET: An overview of dedicated experiments

International Nuclear Information System (INIS)

Fundamenski, W.; Andrew, P.; Matthews, G.F.; Riccardo, V.; Eich, T.; Pitts, R.A.; Sailer, W.; Sipilae, S.

2005-01-01

Energy transport in the SOL was studied for a variety of JET plasmas with an emphasis on Type-I ELMy H-mode. Under ITER relevant, low collisionality conditions, inter-ELM radial energy transport was found to be dominated by (neo-)classical ion conduction, i.e. by diffusion of heat due to ion-ion collisions. The radial convection of the ELM filaments with perpendicular > ∼ 0.6±0.3 km/s, perpendicular /c s > ∼ 0.2 % and perpendicular >/ s > ∼ 0.3±0.1 % agrees well with a sheath-limited model of plasmoid propagation. Within the filament, the electrons are cooled more rapidly than the ions, which retain much of their initial energy when striking the outboard limiter. (author)

Direct Kernel Perceptron (DKP): ultra-fast kernel ELM-based classification with non-iterative closed-form weight calculation.

Science.gov (United States)

Fernández-Delgado, Manuel; Cernadas, Eva; Barro, Senén; Ribeiro, Jorge; Neves, José

2014-02-01

The Direct Kernel Perceptron (DKP) (Fernández-Delgado et al., 2010) is a very simple and fast kernel-based classifier, related to the Support Vector Machine (SVM) and to the Extreme Learning Machine (ELM) (Huang, Wang, & Lan, 2011), whose α-coefficients are calculated directly, without any iterative training, using an analytical closed-form expression which involves only the training patterns. The DKP, which is inspired by the Direct Parallel Perceptron, (Auer et al., 2008), uses a Gaussian kernel and a linear classifier (perceptron). The weight vector of this classifier in the feature space minimizes an error measure which combines the training error and the hyperplane margin, without any tunable regularization parameter. This weight vector can be translated, using a variable change, to the α-coefficients, and both are determined without iterative calculations. We calculate solutions using several error functions, achieving the best trade-off between accuracy and efficiency with the linear function. These solutions for the α coefficients can be considered alternatives to the ELM with a new physical meaning in terms of error and margin: in fact, the linear and quadratic DKP are special cases of the two-class ELM when the regularization parameter C takes the values C=0 and C=∞. The linear DKP is extremely efficient and much faster (over a vast collection of 42 benchmark and real-life data sets) than 12 very popular and accurate classifiers including SVM, Multi-Layer Perceptron, Adaboost, Random Forest and Bagging of RPART decision trees, Linear Discriminant Analysis, K-Nearest Neighbors, ELM, Probabilistic Neural Networks, Radial Basis Function neural networks and Generalized ART. Besides, despite its simplicity and extreme efficiency, DKP achieves higher accuracies than 7 out of 12 classifiers, exhibiting small differences with respect to the best ones (SVM, ELM, Adaboost and Random Forest), which are much slower. Thus, the DKP provides an easy and fast way

The effect of pyrene labelling on the thermal stability of actin filaments

International Nuclear Information System (INIS)

Halasi, Szulamit; Papp, Gabor; Bugyi, Beata; Barko, Szilvia; Orban, Jozsef; Ujfalusi, Zoltan; Visegrady, Balazs

2006-01-01

The ability of actin to form filaments is fundamental to its biological function and often characterised by various methods in vitro. One of the most frequently used methods capitalises on the observation that the fluorescence emission of a pyrene label on the Cys-374 residue of actin is enhanced by a factor of ∼20 during polymerisation. This method inherently involves the chemical modification of actin monomers with pyrene. It was reported earlier that the pyrene labelling of actin monomers has only small effect on the polymerisation and depolymerisation rates of actin, indicating that the method is suitable to characterise the effect of actin-binding proteins or peptides on the polymerisation kinetics. In our present work we tested the effect of the pyrene labelling on the thermal denaturation of actin filaments by using the method of differential scanning calorimetry (DSC). By recording the heat denaturation profiles of unlabelled and pyrene labelled actin filaments we observed that pyrene labelling shifted the melting point (T m ) of actin filaments from 66 to 68 deg. C. A similar effect was detected in the presence of equimolar concentration of phalloidin where the T m shifted from 79 to 82 deg. C. We concluded that the observed pyrene labelling induced differences of the thermal denaturation of actin filaments were small. The DSC results, therefore, confirmed that the methods based on the measurements of pyrene intensity during actin polymerisation are suitable to characterise the polymerisation kinetics of actin under in vitro conditions

Filamentation of Campylobacter in broth cultures

Directory of Open Access Journals (Sweden)

Nacheervan M Ghaffar

2015-06-01

Full Text Available The transition from rod to filamentous cell morphology has been identified as a response to stressful conditions in many bacterial species and has been ascribed to confer certain survival advantages. Filamentation of Campylobacter jejuni was demonstrated to occur spontaneously on entry in to stationary phase distinguishing it from many other bacteria where a reduction in size is more common. The aim of this study was to investigate the cues that give rise to filamentation of C. jejuni and C. coli and gain insights into the process. Using minimal medium, augmentation of filamentation occurred and it was observed that this morphological change was wide spread amongst C. jejuni strains tested but was not universal in C. coli strains. Filamentation did not appear to be due to release of diffusible molecules, toxic metabolites, or be in response to oxidative stress in the medium. Separated filaments exhibited greater intracellular ATP contents (2.66 to 17.4 fg than spiral forms (0.99 to 1.7 fg and showed enhanced survival in water at 4oC and 37oC compared to spiral cells. These observations support the conclusion that the filaments are adapted to survive extra-intestinal environments. Differences in cell morphology and physiology need to be considered in the context of the design of experimental studies and the methods adopted for the isolation of campylobacters from food, clinical and environmental sources.

Balance of the stored energies sustained by the internal and edge transport barriers and effects of ELMs and L-H transitions in JT-60U

International Nuclear Information System (INIS)

Kamada, Y.; Yoshida, M.; Sakamoto, Y.; Koide, Y.; Oyama, N.; Urano, H.; Kamiya, K.; Suzuki, T.; Isayama, A.

2009-01-01

To understand key physics processes determining radial profiles of the kinetic plasma parameters in the advanced tokamak operation scenarios, correlations between the edge transport barrier (ETB) and the internal transport barrier (ITB) have been studied in the JT-60U tokamak device. It has been found that the edge pedestal poloidal beta, β p -ped, increases almost linearly with the total poloidal beta, β p -tot, over a wide range of the plasma current for type I ELMing H-mode plasmas, and this dependence becomes stronger with increasing triangularity. This dependence is not due to the profile stiffness, since the dependence is the same regardless of the existence of ITB. As the stored energy inside the ITB-foot radius (W ITB ) increases, the total thermal stored energy (W th ) increases and then the pedestal stored energy (W ped ) increases. On the other hand, as W ped increases, the ELM penetration expands more inwards and finally reaches the ITB-foot radius. At this situation, the ITB-foot radius cannot move outwards because of the erosion by ELMs. Then the fractions of W ITB /W th and W ped /W th become almost constant. It has also been found that the type I ELM expels/decreases the edge toroidal momentum larger than the edge ion thermal energy. The ELM penetration for the toroidal rotation tends to be deeper than that for the ion temperature and can exceed the ITB-foot radius. The ELM penetration is deeper for CO-rotating plasmas than CTR rotating plasmas. In both cases, the ELM penetration is deeper in the order of the toroidal rotation (V t ), the ion temperature (T i ) and then the electron temperature (T e ). The L-H transition also changes the V t profile more significantly than the T i profile. At the L-H transition, the pedestal V t shifts into the CTR-direction deeply and suddenly without a change in T i , and then the pedestal V t grows further together with a growth of the pedestal T i in a slower timescale. Such changes in V t by ELMs and L

Plasma Brightenings in a Failed Solar Filament Eruption

Energy Technology Data Exchange (ETDEWEB)

Li, Y.; Ding, M. D., E-mail: yingli@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China)

2017-03-20

Failed filament eruptions are solar eruptions that are not associated with coronal mass ejections. In a failed filament eruption, the filament materials usually show some ascending and falling motions as well as generating bright EUV emissions. Here we report a failed filament eruption (SOL2016-07-22) that occurred in a quiet-Sun region observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . In this event, the filament spreads out but gets confined by the surrounding magnetic field. When interacting with the ambient magnetic field, the filament material brightens up and flows along the magnetic field lines through the corona to the chromosphere. We find that some materials slide down along the lifting magnetic structure containing the filament and impact the chromosphere, and through kinetic energy dissipation, cause two ribbon-like brightenings in a wide temperature range. There is evidence suggesting that magnetic reconnection occurs between the filament magnetic structure and the surrounding magnetic fields where filament plasma is heated to coronal temperatures. In addition, thread-like brightenings show up on top of the erupting magnetic fields at low temperatures, which might be produced by an energy imbalance from a fast drop of radiative cooling due to plasma rarefaction. Thus, this single event of a failed filament eruption shows the existence of a variety of plasma brightenings that may be caused by completely different heating mechanisms.

Some Guides to Discovery About Elm Trees, Owls, Cockroaches, Earthworms, Cement and Concrete.

Science.gov (United States)

Busch, Phyllis S.

The introduction emphasizes the need for environmental and conservation education, and advocates an inquiry approach. Outdoor resources available to every school are listed. Detailed suggestions are made for investigating cement and concrete, cockroaches, earthworms, elm trees, and owls. In each case general background information and a list of…

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

International Nuclear Information System (INIS)

Pankin, Alexei Y.; Kritz, Arnold H.

2011-01-01

Topics covered are: anomalous transport and E f- B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

Energy Technology Data Exchange (ETDEWEB)

Pankin, Alexei Y.; Kritz, Arnold H.

2011-07-19

Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

Models of Tidally Induced Gas Filaments in the Magellanic Stream

Science.gov (United States)

Pardy, Stephen A.; D’Onghia, Elena; Fox, Andrew J.

2018-04-01

The Magellanic Stream and Leading Arm of H I that stretches from the Large and Small Magellanic Clouds (LMC and SMC) and over 200° of the Southern sky is thought to be formed from multiple encounters between the LMC and SMC. In this scenario, most of the gas in the Stream and Leading Arm is stripped from the SMC, yet recent observations have shown a bifurcation of the Trailing Arm that reveals LMC origins for some of the gas. Absorption measurements in the Stream also reveal an order of magnitude more gas than in current tidal models. We present hydrodynamical simulations of the multiple encounters between the LMC and SMC at their first pass around the Milky Way, assuming that the Clouds were more extended and gas-rich in the past. Our models create filamentary structures of gas in the Trailing Stream from both the LMC and SMC. While the SMC trailing filament matches the observed Stream location, the LMC filament is offset. In addition, the total observed mass of the Stream in these models is underestimated by a factor of four when the ionized component is accounted for. Our results suggest that there should also be gas stripped from both the LMC and SMC in the Leading Arm, mirroring the bifurcation in the Trailing Stream. This prediction is consistent with recent measurements of spatial variation in chemical abundances in the Leading Arm, which show that gas from multiple sources is present, although its nature is still uncertain.

Analysis of ELM stability with extended MHD models in JET, JT-60U and future JT-60SA tokamak plasmas

Science.gov (United States)

Aiba, N.; Pamela, S.; Honda, M.; Urano, H.; Giroud, C.; Delabie, E.; Frassinetti, L.; Lupelli, I.; Hayashi, N.; Huijsmans, G.; JET Contributors, the; Research Unit, JT-60SA

2018-01-01

The stability with respect to a peeling-ballooning mode (PBM) was investigated numerically with extended MHD simulation codes in JET, JT-60U and future JT-60SA plasmas. The MINERVA-DI code was used to analyze the linear stability, including the effects of rotation and ion diamagnetic drift ({ω }* {{i}}), in JET-ILW and JT-60SA plasmas, and the JOREK code was used to simulate nonlinear dynamics with rotation, viscosity and resistivity in JT-60U plasmas. It was validated quantitatively that the ELM trigger condition in JET-ILW plasmas can be reasonably explained by taking into account both the rotation and {ω }* {{i}} effects in the numerical analysis. When deuterium poloidal rotation is evaluated based on neoclassical theory, an increase in the effective charge of plasma destabilizes the PBM because of an acceleration of rotation and a decrease in {ω }* {{i}}. The difference in the amount of ELM energy loss in JT-60U plasmas rotating in opposite directions was reproduced qualitatively with JOREK. By comparing the ELM affected areas with linear eigenfunctions, it was confirmed that the difference in the linear stability property, due not to the rotation direction but to the plasma density profile, is thought to be responsible for changing the ELM energy loss just after the ELM crash. A predictive study to determine the pedestal profiles in JT-60SA was performed by updating the EPED1 model to include the rotation and {ω }* {{i}} effects in the PBM stability analysis. It was shown that the plasma rotation predicted with the neoclassical toroidal viscosity degrades the pedestal performance by about 10% by destabilizing the PBM, but the pressure pedestal height will be high enough to achieve the target parameters required for the ITER-like shape inductive scenario in JT-60SA.

Graphene-based filament material for thermal ionization

Energy Technology Data Exchange (ETDEWEB)

Hewitt, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Shick, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Siegfried, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-19

The use of graphene oxide materials for thermal ionization mass spectrometry analysis of plutonium and uranium has been investigated. Filament made from graphene oxide slurries have been 3-D printed. A method for attaching these filaments to commercial thermal ionization post assemblies has been devised. Resistive heating of the graphene based filaments under high vacuum showed stable operation in excess of 4 hours. Plutonium ion production has been observed in an initial set of filaments spiked with the Pu 128 Certified Reference Material.

Footpoint detection and mass-motion in chromospheric filaments

Science.gov (United States)

V, Aparna; Hardersen, P. S.; Martin, S. F.

2013-07-01

A quiescent region on the Sun containing three filaments is used to study the properties of mass motion. This study determines if the footpoints or end-points of the filaments are the locations from where mass gets injected into the filaments. Several hypotheses have been put forth in the past to determine how a filament acquires mass. Trapping of coronal mass in the filament channel due to condensation (Martin, 1996) and injection of mass into the filaments during magnetic reconnection (Priest, et al., 1995) are some of the speculations. This study looks for indications for injection of mass via chromospheric footpoints. The data consists of blue (Hα-0.5 Å) and red (Hα+0.5 Å) wing high resolution Hα images of the W29N37 region of the Sun taken on Oct 30, 2010, from 1200 - 1600 UT. The Dutch Open Telescope was used to obtain the data. The images are aligned and animated to see Doppler motion in the fibrils. Smaller fibrils merge to form longer ones; barbs appear and disappear in one of the long filaments and is seen moving along the length of the filament. A region with no typical filament-like absorption feature is observed to be continuously receiving mass. Fibrils appear to be converging from opposite sides along what appears to be a neutral line; mass motion is seen in these fibrils as well. An eruption occurs in a region of fibrils lumped together at the end of the first hour (1300 UT) followed by plage brightening at 1430 UT near one of the filament regions. Helioviewer (Panasenco, et al., 2011) is used for aligning the images; GIMP is used for precision alignment and animation. Each frame in the sequence is studied carefully to note changes in the filament regions. The footpoints of the filaments are determined by the changes observed in the position of the filament ‘legs’ in each frame. Variations in the magnetic polarity corresponding to changes observed in the chromosphere are analyzed using HMI magnetograms. Bright and dark points on the

Real time monitoring of filament-assisted chemically vapor deposited diamond by spectroscopic ellipsometry

International Nuclear Information System (INIS)

Yue Cong; An, I.; Vedam, K.; Collins, R.W.; Nguyen, H.V.; Messier, R.

1991-01-01

Spectroscopic ellipsometry over the range 1.5-4.5 eV was applied as a real time probe of the processes occurring in the initial nucleation of thin film diamond by heated-filament assisted chemical vapor deposition. Using both untreated and diamond-polished c-Si substrates, as well as both carburized and uncarburized tungsten filaments, it was possible to separate and characterize competing phenomena, including the increase in surface temperature induced by filament ignition, the formation of carbide layers, contamination of the substrate by tungsten from the filament, annealing of diamond polishing damage, and, finally, diamond nucleation. An accurate measurement of the true temperature of the substrate surface averaged over the top 500 A can be obtained from the energy position of critical points in the c-Si band structure. For diamond deposition, we operated with an initial excess flow of CH 4 to stimulate nucleation. We applied real time feedback and manual control to reduce the CH 4 flow in the first monolayers of deposition. The thickness of diamond and an estimate of its nucleation density can be obtained from real time spectra, and the latter was in good agreement with that obtained from scanning electron microscopy. (orig.)

Forchlorfenuron disrupts SEPT9_i1 filaments and inhibits HIF-1.

Directory of Open Access Journals (Sweden)

Dikla Vardi-Oknin

Full Text Available Forchlorfenuron (FCF is a synthetic plant cytokinin that has been shown to alter yeast and mammalian septin organization. Septins are a highly conserved family of GTP-binding cytoskeletal proteins. Mammalian septins are involved in diverse cellular processes including tumorigenesis. We have been studying the interaction between septin 9 isoform 1 (SEPT9_i1 and hypoxia inducible factor-1α (HIF-1α, the oxygen regulated subunit of HIF-1. HIF-1 is a key transcription factor in the hypoxic responses pathway, and its activation has been observed in carcinogenesis and numerous cancers. SEPT9_i1/HIF-1α interaction plays an important role in upregulation of HIF-1 transcriptional activity by preventing HIF-1α's ubiquitination and degradation leading to increased tumor growth and angiogenesis. We tested the hypothesis whether FCF affects SEPT9_i1 filamentous structures and consequently HIF-1 pathway in cancer cells. We showed that FCF suppresses tumorigenic properties, including proliferation, migration and transformation, in prostate cancer cells. FCF did not alter SEPT9_i1 steady state protein expression levels but it affected its filamentous structures and subcellular localization. FCF induced degradation of HIF-1α protein in a dose- and time-dependent manner. This inhibition was also shown in other common cancer types tested. Rapid degradation of HIF-1α protein levels was accompanied by respective inhibition in HIF-1α transcriptional activity. Moreover, HIF-1α protein half-life was markedly decreased in the presence of FCF compared with that in the absence of FCF. The FCF-induced degradation of HIF-1α was mediated in a significant part via the proteasome. To the best of our knowledge, this is the first demonstration of specific manipulation of septin filaments by pharmacological means having downstream inhibitory effects on the HIF-1 pathway.

Thick Filament Protein Network, Functions, and Disease Association.

Science.gov (United States)

Wang, Li; Geist, Janelle; Grogan, Alyssa; Hu, Li-Yen R; Kontrogianni-Konstantopoulos, Aikaterini

2018-03-13

Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

The Antibacterial Cell Division Inhibitor PC190723 Is an FtsZ Polymer-stabilizing Agent That Induces Filament Assembly and Condensation*

Science.gov (United States)

Andreu, José M.; Schaffner-Barbero, Claudia; Huecas, Sonia; Alonso, Dulce; Lopez-Rodriguez, María L.; Ruiz-Avila, Laura B.; Núñez-Ramírez, Rafael; Llorca, Oscar; Martín-Galiano, Antonio J.

2010-01-01

Cell division protein FtsZ can form single-stranded filaments with a cooperative behavior by self-switching assembly. Subsequent condensation and bending of FtsZ filaments are important for the formation and constriction of the cytokinetic ring. PC190723 is an effective bactericidal cell division inhibitor that targets FtsZ in the pathogen Staphylococcus aureus and Bacillus subtilis and does not affect Escherichia coli cells, which apparently binds to a zone equivalent to the binding site of the antitumor drug taxol in tubulin (Haydon, D. J., Stokes, N. R., Ure, R., Galbraith, G., Bennett, J. M., Brown, D. R., Baker, P. J., Barynin, V. V., Rice, D. W., Sedelnikova, S. E., Heal, J. R., Sheridan, J. M., Aiwale, S. T., Chauhan, P. K., Srivastava, A., Taneja, A., Collins, I., Errington, J., and Czaplewski, L. G. (2008) Science 312, 1673–1675). We have found that the benzamide derivative PC190723 is an FtsZ polymer-stabilizing agent. PC190723 induced nucleated assembly of Bs-FtsZ into single-stranded coiled protofilaments and polymorphic condensates, including bundles, coils, and toroids, whose formation could be modulated with different solution conditions. Under conditions for reversible assembly of Bs-FtsZ, PC190723 binding reduced the GTPase activity and induced the formation of straight bundles and ribbons, which was also observed with Sa-FtsZ but not with nonsusceptible Ec-FtsZ. The fragment 2,6-difluoro-3-methoxybenzamide also induced Bs-FtsZ bundling. We propose that polymer stabilization by PC190723 suppresses in vivo FtsZ polymer dynamics and bacterial division. The biochemical action of PC190723 on FtsZ parallels that of the microtubule-stabilizing agent taxol on the eukaryotic structural homologue tubulin. Both taxol and PC190723 stabilize polymers against disassembly by preferential binding to each assembled protein. It is yet to be investigated whether both ligands target structurally related assembly switches. PMID:20212044

Variability of morphometric characteristics of the leaves of European white elm from the area of Great War Island

Directory of Open Access Journals (Sweden)

Devetaković Jovana

2013-01-01

Full Text Available The European White Elm (Ulmus effusa Willd. is indicated as a rare and endangered species in the growing stock of the Republic of Serbia. In the area of Great War Island, its natural populations were reduced to 56 registered trees, which occur in three spatially isolated subpopulations. On the basis of the research conducted on the level of variability of adaptible morphometric characteristics of leaves from 14 selected test trees of European White Elm, it can be concluded that the degree of interpopulation variability is satisfactory, which is a good basis for the conservation of the available gene pool.

Filament shape versus coronal potential magnetic field structure

Science.gov (United States)

Filippov, B.

2016-01-01

Solar filament shape in projection on disc depends on the structure of the coronal magnetic field. We calculate the position of polarity inversion lines (PILs) of coronal potential magnetic field at different heights above the photosphere, which compose the magnetic neutral surface, and compare with them the distribution of the filament material in Hα chromospheric images. We found that the most of the filament material is enclosed between two PILs, one at a lower height close to the chromosphere and one at a higher level, which can be considered as a height of the filament spine. Observations of the same filament on the limb by the Solar Terrestrial Relations Observatory spacecraft confirm that the height of the spine is really very close to the value obtained from the PIL and filament border matching. Such matching can be used for filament height estimations in on-disc observations. Filament barbs are housed within protruding sections of the low-level PIL. On the base of simple model, we show that the similarity of the neutral surfaces in potential and non-potential fields with the same sub-photospheric sources is the reason for the found tendency for the filament material to gather near the potential-field neutral surface.

Fabrication of PLA Filaments and its Printable Performance

Science.gov (United States)

Liu, Wenjie; Zhou, Jianping; Ma, Yuming; Wang, Jie; Xu, Jie

2017-12-01

Fused deposition modeling (FDM) is a typical 3D printing technology and preparation of qualified filaments is the basis. In order to prepare polylactic acid (PLA) filaments suitable for personalized FDM 3D printing, this article investigated the effect of factors such as extrusion temperature and screw speed on the diameter, surface roughness and ultimate tensile stress of the obtained PLA filaments. The optimal process parameters for fabrication of qualified filaments were determined. Further, the printable performance of the obtained PLA filaments for 3D objects was preliminarily explored.

Intermediate filament mechanics in vitro and in the cell: From coiled coils to filaments, fibers and networks

OpenAIRE

Köster, Sarah; Weitz, David; Goldman, Robert D.; Aebi, Ueli; Herrmann, Harald

2015-01-01

Intermediate filament proteins form filaments, fibers and networks both in the cytoplasm and the nucleus of metazoan cells. Their general structural building plan accommodates highly varying amino acid sequences to yield extended dimeric α-helical coiled coils of highly conserved design. These “rod” particles are the basic building blocks of intrinsically flexible, filamentous structures that are able to resist high mechanical stresses, i.e. bending and stretching to a considerable degree, bo...

Self-assembly of designed supramolecular magnetic filaments of different shapes

Energy Technology Data Exchange (ETDEWEB)

Novak, E.V. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Rozhkov, D.A., E-mail: d.a.rozhkov@gmail.com [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Sanchez, P.A. [University of Vienna, Sensengasse 8, Vienna (Austria); Kantorovich, S.S. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

2017-06-01

In the present work we study via molecular dynamics simulations filaments of ring and linear shape. Filaments are made of magnetic nanoparticles, possessing a point dipole in their centres. Particles in filaments are crosslinked in a particular way, so that the deviation of the neighbouring dipoles from the head-to-tail orientation is penalised by the bond. We show how the conformation of a single chain and ring filament changes on cooling for different lengths. We also study filament pairs, by fixing filaments at a certain distance and analysing the impact of inter-filament interaction on the equilibrium configurations. Our study opens a perspective to investigate the dispersions of filaments, both theoretically and numerically, by using effective potentials. - Highlights: • Single filament study. • Magnetic particles crosslinked in chains and rings. • Magnetic filament interactions.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

Science.gov (United States)

Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

International Nuclear Information System (INIS)

Jiang, Chao-Wei; Feng, Xue-Shang; Wu, Shi-Tsan; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE–MHD–NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption. (paper)

Online sequential condition prediction method of natural circulation systems based on EOS-ELM and phase space reconstruction

International Nuclear Information System (INIS)

Chen, Hanying; Gao, Puzhen; Tan, Sichao; Tang, Jiguo; Yuan, Hongsheng

2017-01-01

Highlights: •An online condition prediction method for natural circulation systems in NPP was proposed based on EOS-ELM. •The proposed online prediction method was validated using experimental data. •The training speed of the proposed method is significantly fast. •The proposed method can achieve good accuracy in wide parameter range. -- Abstract: Natural circulation design is widely used in the passive safety systems of advanced nuclear power reactors. The irregular and chaotic flow oscillations are often observed in boiling natural circulation systems so it is difficult for operators to monitor and predict the condition of these systems. An online condition forecasting method for natural circulation system is proposed in this study as an assisting technique for plant operators. The proposed prediction approach was developed based on Ensemble of Online Sequential Extreme Learning Machine (EOS-ELM) and phase space reconstruction. Online Sequential Extreme Learning Machine (OS-ELM) is an online sequential learning neural network algorithm and EOS-ELM is the ensemble method of it. The proposed condition prediction method can be initiated by a small chunk of monitoring data and it can be updated by newly arrived data at very fast speed during the online prediction. Simulation experiments were conducted on the data of two natural circulation loops to validate the performance of the proposed method. The simulation results show that the proposed predication model can successfully recognize different types of flow oscillations and accurately forecast the trend of monitored plant variables. The influence of the number of hidden nodes and neural network inputs on prediction performance was studied and the proposed model can achieve good accuracy in a wide parameter range. Moreover, the comparison results show that the proposed condition prediction method has much faster online learning speed and better prediction accuracy than conventional neural network model.

Fundamentals of Filament Interaction

Science.gov (United States)

2017-05-19

AFRL-AFOSR-VA-TR-2017-0110 FUNDAMENTALS OF FILAMENT INTERACTION Martin Richardson UNIVERSITY OF CENTRAL FLORIDA Final Report 06/02/2017 DISTRIBUTION...of Filament Interaction 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA95501110001 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Martin Richardson 5d. PROJECT...NAME OF RESPONSIBLE PERSON Martin Richardson a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPHONE NUMBER (Include area code) 407-823-6819 Standard Form

Filaments in simulations of molecular cloud formation

Energy Technology Data Exchange (ETDEWEB)

Gómez, Gilberto C.; Vázquez-Semadeni, Enrique [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia Apartado Postal 3-72, 58090 Morelia, Michoacán (Mexico)

2014-08-20

We report on the filaments that develop self-consistently in a new numerical simulation of cloud formation by colliding flows. As in previous studies, the forming cloud begins to undergo gravitational collapse because it rapidly acquires a mass much larger than the average Jeans mass. Thus, the collapse soon becomes nearly pressureless, proceeding along its shortest dimension first. This naturally produces filaments in the cloud and clumps within the filaments. The filaments are not in equilibrium at any time, but instead are long-lived flow features through which the gas flows from the cloud to the clumps. The filaments are long-lived because they accrete from their environment while simultaneously accreting onto the clumps within them; they are essentially the locus where the flow changes from accreting in two dimensions to accreting in one dimension. Moreover, the clumps also exhibit a hierarchical nature: the gas in a filament flows onto a main, central clump but other, smaller-scale clumps form along the infalling gas. Correspondingly, the velocity along the filament exhibits a hierarchy of jumps at the locations of the clumps. Two prominent filaments in the simulation have lengths ∼15 pc and masses ∼600 M {sub ☉} above density n ∼ 10{sup 3} cm{sup –3} (∼2 × 10{sup 3} M {sub ☉} at n > 50 cm{sup –3}). The density profile exhibits a central flattened core of size ∼0.3 pc and an envelope that decays as r {sup –2.5} in reasonable agreement with observations. Accretion onto the filament reaches a maximum linear density rate of ∼30 M {sub ☉} Myr{sup –1} pc{sup –1}.

Thermal and Chemical Evolution of Collapsing Filaments

Energy Technology Data Exchange (ETDEWEB)

Gray, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Scannapieco, Evan [Arizona State Univ., Mesa, AZ (United States). School of Earth and Space Exploration

2013-01-15

Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z_⊙ filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10^-3Z_⊙ filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253, but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

Numerical studies of third-harmonic generation in laser filament in air perturbed by plasma spot

International Nuclear Information System (INIS)

Feng Liubin; Lu Xin; Liu Xiaolong; Li Yutong; Chen Liming; Ma Jinglong; Dong Quanli; Wang Weimin; Xi Tingting; Sheng Zhengming; Zhang Jie; He Duanwei

2012-01-01

Third-harmonic emission from laser filament intercepted by plasma spot is studied by numerical simulations. Significant enhancement of the third-harmonic generation is obtained due to the disturbance of the additional plasma. The contribution of the pure plasma effect and the possible plasma-enhanced third-order susceptibility on the third-harmonic generation enhancement are compared. It is shown that the plasma induced cancellation of destructive interference [Y. Liu et al., Opt. Commun. 284, 4706 (2011)] of two-colored filament is the dominant mechanism of the enhancement of third-harmonic generation.

The antagonistic effect of Saccharomyces boulardii on Candida albicans filamentation, adhesion and biofilm formation.

Science.gov (United States)

Krasowska, Anna; Murzyn, Anna; Dyjankiewicz, Agnieszka; Łukaszewicz, Marcin; Dziadkowiec, Dorota

2009-12-01

The dimorphic fungus Candida albicans is a member of the normal flora residing in the intestinal tract of humans. In spite of this, under certain conditions it can induce both superficial and serious systemic diseases, as well as be the cause of gastrointestinal infections. Saccharomyces boulardii is a yeast strain that has been shown to have applications in the prevention and treatment of intestinal infections caused by bacterial pathogens. The purpose of this study was to determine whether S. boulardii affects the virulence factors of C. albicans. We demonstrate the inhibitory effect of live S. boulardii cells on the filamentation (hyphae and pseudohyphae formation) of C. albicans SC5314 strain proportional to the amount of S. boulardii added. An extract from S. boulardii culture has a similar effect. Live S. boulardii and the extract from S. boulardii culture filtrate diminish C. albicans adhesion to and subsequent biofilm formation on polystyrene surfaces under both aerobic and microaerophilic conditions. This effect is very strong and requires lower doses of S. boulardii cells or concentrations of the extract than serum-induced filamentation tests. Saccharomyces boulardii has a strong negative effect on very important virulence factors of C. albicans, i.e. the ability to form filaments and to adhere and form biofilms on plastic surfaces.

Dynamic behavior of detached recombining plasmas during ELM-like plasma heat pulses in the divertor plasma simulator NAGDIS-II

International Nuclear Information System (INIS)

Uesugi, Y.; Hattori, N.; Nishijima, D.; Ohno, N.; Takamura, S.

2001-01-01

It has been recognized that the ELMs associated with a good confinement at the edge, such as H-mode, must bring an enormous energy to the divertor target plate through SOL and detached plasmas. The understanding of the ELM energy transport through SOL to the divertor target is rather poor at the moment, which leads to an ambiguous estimation of the deposited heat load on the divertor target in ITER. In the present work the ELM-like plasma heat pulse is generated by rf heating in a linear divertor plasma simulator. Energetic electrons with an energy range 10-40 eV are effectively generated by rf heating in low temperature plasmas with (T e )< ∼1 eV. It is observed experimentally that the energetic electrons ionize the highly excited Rydberg atoms quickly, bringing a rapid increase of the ion particle flux to the target, and make the detached plasmas attached to the target. Detailed physical processes about the interaction between the heat pulse with conduction and convection, and detached recombining plasmas are discussed

Ultraviolet treatment on high performance filaments

International Nuclear Information System (INIS)

Gu Huang

2005-01-01

Quartz, Kevlar, carbon, and glass filaments were irradiated by ultraviolet ray with various periods. Tensile strength of the treated fibres was tested and analyzed, and the outward appearance of the treated filaments was shown

Assessing the suitability of extreme learning machines (ELM for groundwater level prediction

Directory of Open Access Journals (Sweden)

Yadav Basant

2017-03-01

Full Text Available Fluctuation of groundwater levels around the world is an important theme in hydrological research. Rising water demand, faulty irrigation practices, mismanagement of soil and uncontrolled exploitation of aquifers are some of the reasons why groundwater levels are fluctuating. In order to effectively manage groundwater resources, it is important to have accurate readings and forecasts of groundwater levels. Due to the uncertain and complex nature of groundwater systems, the development of soft computing techniques (data-driven models in the field of hydrology has significant potential. This study employs two soft computing techniques, namely, extreme learning machine (ELM and support vector machine (SVM to forecast groundwater levels at two observation wells located in Canada. A monthly data set of eight years from 2006 to 2014 consisting of both hydrological and meteorological parameters (rainfall, temperature, evapotranspiration and groundwater level was used for the comparative study of the models. These variables were used in various combinations for univariate and multivariate analysis of the models. The study demonstrates that the proposed ELM model has better forecasting ability compared to the SVM model for monthly groundwater level forecasting.

Localised Microwave Bursts During ELMs on MAST

Directory of Open Access Journals (Sweden)

Freethy Simon

2015-01-01

Full Text Available Bursts of microwave emission are observed during ELM events on the Mega Ampère Spherical Tokamak. In agreement with observations on other machines, these bursts are up to 3 orders of magnitude more intense than the thermal background, but are electron cyclotron in nature. The peak in microwave emission is ~20μ before the peak in midplane Dα emission. Using the Synthetic Aperture Microwave Imaging radiometer, we are able to demonstrate that these bursts are often highly spatially localised and preferentially occur at the tokamak midplane. It is hypothesised that the localisation is a result of Doppler resonance broadening for electron Bernstein waves and the high perpendicular electron energies could be the result of pitch angle scattering in high collisionality regions of the plasma.

Observations of the Growth of an Active Region Filament

Science.gov (United States)

Yang, Bo

2017-04-01

We present observations of the growth of an active region filament caused by magnetic interactions among the filament and its adjacent superpenumbral filament (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the filament is the first step reconnection, which resulted in the filament bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to the disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the filament and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed filament threads, appeared. Hαobservations show that this twisted structure is a longer sinistral filament. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the filament consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among filaments and their adjacent SFs and T could lead to the growth of the filaments, and the filament is probably supported in a flux rope.

Langmuir-magnetic probe measurements of ELMs and dithering cycles in the EAST tokamak

DEFF Research Database (Denmark)

Yan, Ning; Naulin, Volker; Xu, G. S.

2014-01-01

and dithering cycles have been investigated near the threshold power for the transition from the low confinement mode (L-mode) to the high confinement mode (H-mode). A precursor is observed prior to type-III ELM events with chirping frequency (130–70 kHz). It is located inside the separatrix and does not lead...

Colored fused filament fabrication

OpenAIRE

Song, Haichuan; Lefebvre, Sylvain

2017-01-01

Filament fused fabrication is the method of choice for printing 3D models at low cost, and is the de-facto standard for hobbyists, makers and schools. Unfortunately, filament printers cannot truly reproduce colored objects. The best current techniques rely on a form of dithering exploiting occlusion, that was only demonstrated for shades of two base colors and that behaves differently depending on surface slope. We explore a novel approach for 3D printing colored objects, capable of creating ...

The role of radial particle pinches in ELM suppression by resonant magnetic perturbations

International Nuclear Information System (INIS)

Stacey, W.M.; Evans, T.E.

2011-01-01

The force balance in the plasma edge in a matched pair of DIII-D (Luxon 2002 Nucl. Fusion 42 6149) tokamak discharges with and without resonant magnetic perturbations (RMPs) is evaluated in order to investigate the effects on particle transport of RMP applied for the purpose of suppressing edge-localized modes (ELMs). Experimental data are used to evaluate the radial and toroidal force balances, which may be written as a pinch-diffusion relation for the radial ion flux to facilitate investigation of transport effects. The radial electric field in the H-mode plasma had a sharp negative dip in the steep gradient region of the edge pedestal, associated with which was a large inward pinch velocity. The main effect of RMP was to make the edge electric field less negative or more positive, reducing this strong negative dip in the radial electric field (even reversing it from negative to positive over some regions), thereby reducing the strong inward particle pinch in the edge of an H-mode discharge, thus causing a reduction in edge density below the ELM threshold.

Intrusion detection system using Online Sequence Extreme Learning Machine (OS-ELM) in advanced metering infrastructure of smart grid.

Science.gov (United States)

Li, Yuancheng; Qiu, Rixuan; Jing, Sitong

2018-01-01

Advanced Metering Infrastructure (AMI) realizes a two-way communication of electricity data through by interconnecting with a computer network as the core component of the smart grid. Meanwhile, it brings many new security threats and the traditional intrusion detection method can't satisfy the security requirements of AMI. In this paper, an intrusion detection system based on Online Sequence Extreme Learning Machine (OS-ELM) is established, which is used to detecting the attack in AMI and carrying out the comparative analysis with other algorithms. Simulation results show that, compared with other intrusion detection methods, intrusion detection method based on OS-ELM is more superior in detection speed and accuracy.

Positrusion Filament Recycling System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — TUI proposes a novel process to produce 3d printer feedstock filament out of scrap ABS on the ISS. Currently the plastic filament materials that most 3d printers use...

Actin filaments growing against an elastic membrane: Effect of membrane tension

Science.gov (United States)

Sadhu, Raj Kumar; Chatterjee, Sakuntala

2018-03-01

We study the force generation by a set of parallel actin filaments growing against an elastic membrane. The elastic membrane tries to stay flat and any deformation from this flat state, either caused by thermal fluctuations or due to protrusive polymerization force exerted by the filaments, costs energy. We study two lattice models to describe the membrane dynamics. In one case, the energy cost is assumed to be proportional to the absolute magnitude of the height gradient (gradient model) and in the other case it is proportional to the square of the height gradient (Gaussian model). For the gradient model we find that the membrane velocity is a nonmonotonic function of the elastic constant μ and reaches a peak at μ =μ* . For μ membrane energy keeps increasing with time. For the Gaussian model, the system always reaches a steady state and the membrane velocity decreases monotonically with the elastic constant ν for all nonzero values of ν . Multiple filaments give rise to protrusions at different regions of the membrane and the elasticity of the membrane induces an effective attraction between the two protrusions in the Gaussian model which causes the protrusions to merge and a single wide protrusion is present in the system. In both the models, the relative time scale between the membrane and filament dynamics plays an important role in deciding whether the shape of elasticity-velocity curve is concave or convex. Our numerical simulations agree reasonably well with our analytical calculations.

Ion orbit modelling of ELM heat loads on ITER divertor vertical targets.

Czech Academy of Sciences Publication Activity Database

Gunn, J. P.; Carpentier-Chouchana, S.; Dejarnac, Renaud; Escourbiac, F.; Hirai, T.; Komm, Michael; Kukushkin, A.; Panayotis, S.; Pitts, R.A.

2017-01-01

Roč. 12, August (2017), s. 75-83 ISSN 2352-1791. [International Conference on Plasma Surface Interactions 2016, PSI2016 /22./. Roma, 30.05.2016-03.06.2016] Institutional support: RVO:61389021 Keywords : ITER * Divertor * ELM heat loads Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) http://www.sciencedirect.com/science/article/pii/S2352179116302745

Filaments in curved streamlines: rapid formation of Staphylococcus aureus biofilm streamers

International Nuclear Information System (INIS)

Kevin Kim, Minyoung; Drescher, Knut; Shun Pak, On; Stone, Howard A; Bassler, Bonnie L

2014-01-01

Biofilms are surface-associated conglomerates of bacteria that are highly resistant to antibiotics. These bacterial communities can cause chronic infections in humans by colonizing, for example, medical implants, heart valves, or lungs. Staphylococcus aureus, a notorious human pathogen, causes some of the most common biofilm-related infections. Despite the clinical importance of S. aureus biofilms, it remains mostly unknown how physical effects, in particular flow, and surface structure influence biofilm dynamics. Here we use model microfluidic systems to investigate how environmental factors, such as surface geometry, surface chemistry, and fluid flow affect biofilm development of S. aureus. We discovered that S. aureus rapidly forms flow-induced, filamentous biofilm streamers, and furthermore if surfaces are coated with human blood plasma, streamers appear within minutes and clog the channels more rapidly than if the channels are uncoated. To understand how biofilm streamer filaments reorient in flows with curved streamlines to bridge the distances between corners, we developed a mathematical model based on resistive force theory of slender filaments. Understanding physical aspects of biofilm formation of S. aureus may lead to new approaches for interrupting biofilm formation of this pathogen. (paper)

Star-forming Filament Models

International Nuclear Information System (INIS)

Myers, Philip C.

2017-01-01

New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe filaments that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-filament system by identifying the zone of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central filament may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet filament is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.

Star-forming Filament Models

Energy Technology Data Exchange (ETDEWEB)

Myers, Philip C., E-mail: pmyers@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-03-20

New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe filaments that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-filament system by identifying the zone of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central filament may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet filament is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.

Evidence for Mixed Helicity in Erupting Filaments

Science.gov (United States)

Muglach, K.; Wang, Y.-M.; Kliem, B.

2009-09-01

Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non-active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is, in general, determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament "barbs" is opposite in sign to and dominates that of the overlying arcade.

A method for 3D-reconstruction of a muscle thick filament using the tilt series images of a single filament electron tomogram.

Science.gov (United States)

Márquez, G; Pinto, A; Alamo, L; Baumann, B; Ye, F; Winkler, H; Taylor, K; Padrón, R

2014-05-01

Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament - calculated without any image averaging and/or imposition of helical symmetry - only reveals MIH motifs infrequently. This is - to our knowledge - the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. Copyright © 2014 Elsevier Inc. All rights reserved.

Self-induced dipole force and filamentation instability of a matter wave

DEFF Research Database (Denmark)

Saffman, M.

1998-01-01

The interaction of copropagating electromagnetic and matter waves is described with a set of coupled higher-order nonlinear Schrodinger equations. Optical self-focusing modulates an initially planar wave leading to the generation of dipole forces on the atoms. Atomic channeling due to the dipole...... forces leads, in the nonlinear regime, to filamentation of the atomic beam. Instability growth rates are calculated for atomic beams with both low and high phase space densities. In one transverse dimension an exact solution is found that describes a coupled optical and atomic soliton....

The experiment progress of bracket brazing to SSMIC for the ITER ELM prototype coil

International Nuclear Information System (INIS)

Shi, Yi; Wu, Yu; Jin, Huan; Ren, Zhibin; Han, Houxiang; Qian, Jing; Qian, Li; Liu, Bo

2014-01-01

Highlights: • In this study, the experimental research of brackets brazing to stainless steel jacketed, Mineral Insulated Conductor (SSMIC) of the first Edge Localized Modes (ELMs) prototype coil for ITER has been made. • The technology for controlling the fluidity of silver-based brazing alloy is developed to meet the bracket brazing. • Brazing experiments to find the reason for cracks are carried out and the improved brazing technologies to restrain the cracks in the Inconel 625 jacket with silver-based alloy are developed. - Abstract: The first Edge Localized Modes (ELMs) prototype coil for International Thermonuclear Experimental Reactor (ITER) has been manufactured in the Institute of Plasma Physics, CAS (ASIPP) at 2014. The all 19 brackets need to braze to the stainless steel jacketed, Mineral Insulated Conductor (SSMIC) for transporting the nuclear heating in the brackets to the water-cooled SSMIC. Silver-based alloy is the only candidate brazing filler for the bracket brazing due to the limitation from melting point temperature and strength. In this paper, firstly, the experimental study for controlling the fluidity of silver-based brazing alloy is developed. And then, the brazing experiment of prototype bracket is introduced to develop the brazing process and some cracks in the Inconel 625 jackets surface appeared unexpectedly. The microstructures and tensile performance study of the cracked Inconel 625 jacket were made to explore the reason for cracks and the improved brazing technologies to suppress the cracks are developed. Finally, the bracket brazing experiment for the first ELM prototype coil is carried out, In spite of this, some cracks also appear in the Inconel 625 jackets

The experiment progress of bracket brazing to SSMIC for the ITER ELM prototype coil

Energy Technology Data Exchange (ETDEWEB)

Shi, Yi, E-mail: shiyi@ipp.ac.cn; Wu, Yu; Jin, Huan; Ren, Zhibin; Han, Houxiang; Qian, Jing; Qian, Li; Liu, Bo

2014-11-15

Highlights: • In this study, the experimental research of brackets brazing to stainless steel jacketed, Mineral Insulated Conductor (SSMIC) of the first Edge Localized Modes (ELMs) prototype coil for ITER has been made. • The technology for controlling the fluidity of silver-based brazing alloy is developed to meet the bracket brazing. • Brazing experiments to find the reason for cracks are carried out and the improved brazing technologies to restrain the cracks in the Inconel 625 jacket with silver-based alloy are developed. - Abstract: The first Edge Localized Modes (ELMs) prototype coil for International Thermonuclear Experimental Reactor (ITER) has been manufactured in the Institute of Plasma Physics, CAS (ASIPP) at 2014. The all 19 brackets need to braze to the stainless steel jacketed, Mineral Insulated Conductor (SSMIC) for transporting the nuclear heating in the brackets to the water-cooled SSMIC. Silver-based alloy is the only candidate brazing filler for the bracket brazing due to the limitation from melting point temperature and strength. In this paper, firstly, the experimental study for controlling the fluidity of silver-based brazing alloy is developed. And then, the brazing experiment of prototype bracket is introduced to develop the brazing process and some cracks in the Inconel 625 jackets surface appeared unexpectedly. The microstructures and tensile performance study of the cracked Inconel 625 jacket were made to explore the reason for cracks and the improved brazing technologies to suppress the cracks are developed. Finally, the bracket brazing experiment for the first ELM prototype coil is carried out, In spite of this, some cracks also appear in the Inconel 625 jackets.

A filament supported by different magnetic field configurations

Science.gov (United States)

Guo, Y.; Schmieder, B.; Démoulin, P.; Wiegelmann, T.; Aulanier, G.; Török, T.; Bommier, V.

2011-08-01

A nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.

First Report of ‘Candidatus Phytoplasma trifolii’-Related Strain of 16SrVI-A Phytoplasma Subgroup, Associated with Elm Yellows Disease in American Elm ( Ulmus americana L.) in Ohio, U.S.A

Science.gov (United States)

C.E. Flower; N. Hayes-Plazolles; J.M. Slavicek; C. Rosa

2018-01-01

During the investigation of the sudden and early onset of yellowing and mortality of American elm (Ulmus americana L.) trees at the USDA Forest Service Northern Research Station in Delaware, OH, a phytoplasma of the clover proliferation group (16SrVI) was detected as the putative causal agent of the disease outbreak.

Topology of interaction between titin and myosin thick filaments.

Science.gov (United States)

Kellermayer, Miklós; Sziklai, Dominik; Papp, Zsombor; Decker, Brennan; Lakatos, Eszter; Mártonfalvi, Zsolt

2018-05-05

Titin is a giant protein spanning between the Z- and M-lines of the sarcomere. In the A-band titin is associated with the myosin thick filament. It has been speculated that titin may serve as a blueprint for thick-filament formation due to the super-repeat structure of its A-band domains. Accordingly, titin might provide a template that determines the length and structural periodicity of the thick filament. Here we tested the titin ruler hypothesis by mixing titin and myosin at in situ stoichiometric ratios (300 myosins per 12 titins) in buffers of different ionic strength (KCl concentration range 100-300 mM). The topology of the filamentous complexes was investigated with atomic force microscopy. We found that the samples contained distinct, segregated populations of titin molecules and myosin thick filaments. We were unable to identify complexes in which myosin molecules were regularly associated to either mono- or oligomeric titin in either relaxed or stretched states of the titin filaments. Thus, the electrostatically driven self-association is stronger in both myosin and titin than their binding to each other, and it is unlikely that titin functions as a geometrical template for thick-filament formation. However, when allowed to equilibrate configurationally, long myosin thick filaments appeared with titin oligomers attached to their surface. The titin meshwork formed on the thick-filament surface may play a role in controlling thick-filament length by regulating the structural dynamics of myosin molecules and placing a mechanical limit on the filament length. Copyright © 2018 Elsevier Inc. All rights reserved.

Status of the COMPASS tokamak and characterization of the first H-mode

Science.gov (United States)

Pánek, R.; Adámek, J.; Aftanas, M.; Bílková, P.; Böhm, P.; Brochard, F.; Cahyna, P.; Cavalier, J.; Dejarnac, R.; Dimitrova, M.; Grover, O.; Harrison, J.; Háček, P.; Havlíček, J.; Havránek, A.; Horáček, J.; Hron, M.; Imríšek, M.; Janky, F.; Kirk, A.; Komm, M.; Kovařík, K.; Krbec, J.; Kripner, L.; Markovič, T.; Mitošinková, K.; Mlynář, J.; Naydenkova, D.; Peterka, M.; Seidl, J.; Stöckel, J.; Štefániková, E.; Tomeš, M.; Urban, J.; Vondráček, P.; Varavin, M.; Varju, J.; Weinzettl, V.; Zajac, J.; the COMPASS Team

2016-01-01

This paper summarizes the status of the COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for the future studies. The former COMPASS-D tokamak was in operation at UKAEA Culham, UK in 1992-2002. Later, the device was transferred to the Institute of Plasma Physics of the Academy of Sciences of the Czech Republic (IPP AS CR), where it was installed during 2006-2011. Since 2012 the device has been in a full operation with Type-I and Type-III ELMy H-modes as a base scenario. This enables together with the ITER-like plasma shape and flexible NBI heating system (two injectors enabling co- or balanced injection) to perform ITER relevant studies in different parameter range to the other tokamaks (ASDEX-Upgrade, DIII-D, JET) and to contribute to the ITER scallings. In addition to the description of the device, current status and the main diagnostic equipment, the paper focuses on the characterization of the Ohmic as well as NBI-assisted H-modes. Moreover, Edge Localized Modes (ELMs) are categorized based on their frequency dependence on power density flowing across separatrix. The filamentary structure of ELMs is studied and the parallel heat flux in individual filaments is measured by probes on the outer mid-plane and in the divertor. The measurements are supported by observation of ELM and inter-ELM filaments by an ultra-fast camera.

Characterisation of the ELM synchronized H-mode edge pedestal in ASDEX upgrade and DIII-D

Energy Technology Data Exchange (ETDEWEB)

Schneider, Philip A.; Wolfrum, Elisabeth; Guenter, Sibylle; Kurzan, Bernd; Zohm, Hartmut [Max Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Groebner, Rich; Osborne, Tom H.; Ferron, John; Snyder, Philip B. [General Atomics, San Diego, CA (United States); Dunne, Mike G. [Department of Physics, University College Cork, Association Euratom-DCU, Cork (Ireland); Collaboration: ASDEX Upgrade Team; DIII-D Team

2011-07-01

The results of a large database of edge pedestal data from type-I ELMy H-mode discharges from ASDEX Upgrade and DIII-D are presented. The data from high resolution edge diagnostics of both devices is analysed with the same analysis code in order to avoid systematic differences. Furthermore, sophisticated equilibrium reconstructions are used to asses uncertainties which arise during mapping from 2D real space coordinates to 1D flux coordinates. ELM synchronization allows the study of the pedestal structure at the ELM stability boundary. The pedestal is characterized by its top value, the gradient and the width. A large parameter range is covered by the two devices. Over this parameter range the profile shape of edge electron density differs from that of the temperature, irrespective of the device. However, the resulting electron pressure profile shape remains similar for all analysed H-Mode discharges.

Lifetime of titanium filament at constant current

International Nuclear Information System (INIS)

Chou, T.S.; Lanni, C.

1981-01-01

Titanium Sublimation Pump (TSP) represents the most efficient and the least expensive method to produce Ultra High Vacuum (UHV) in storage rings. In ISABELLE, a proton storage accelerator under construction at Brookhaven National Laboratory, for example, TSP provides a pumping speed for hydrogen of > 2 x 10 6 l/s. Due to the finite life of titanium filaments, new filaments have to be switched in before the end of filament burn out, to ensure smooth operation of the accelerator. Therefore, several operational modes that can be used to activate the TSP were studied. The constant current mode is a convenient way of maintaining constant evaporating rate by increasing the power input while the filament diameter decreases as titanium evaporates. The filaments used in this experiment were standard Varian 916-0024 filaments made of Ti 85%, Mo 15% alloy. During their lifetime at a constant current of 48 amperes, the evaporation rate rose to a maximum at about 10% of their life and then flattened out to a constant value, 0.25 g/hr. The maximum evaporation rate occurs coincidently with the recrystallization of 74% Ti 26% Mo 2 from microstructure crystalline at higher titanium concentration to macrostructure crystalline at lower titanium concentration. As the macrocrystal grows, the slip plane develops at the grain boundary resulting in high resistance at the slip plane which will eventually cause the filament burn out due to local heating

Biophysics of filament length regulation by molecular motors

International Nuclear Information System (INIS)

Kuan, Hui-Shun; Betterton, M D

2013-01-01

Regulating physical size is an essential problem that biological organisms must solve from the subcellular to the organismal scales, but it is not well understood what physical principles and mechanisms organisms use to sense and regulate their size. Any biophysical size-regulation scheme operates in a noisy environment and must be robust to other cellular dynamics and fluctuations. This work develops theory of filament length regulation inspired by recent experiments on kinesin-8 motor proteins, which move with directional bias on microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors can depolymerize chemically-stabilized microtubules. In the length-dependent depolymerization model, the rate of depolymerization tends to increase with filament length, because long filaments accumulate more motors at their tips and therefore shorten more quickly. When balanced with a constant filament growth rate, this mechanism can lead to a fixed polymer length. However, the mechanism by which kinesin-8 motors affect the length of dynamic microtubules in cells is less clear. We study the more biologically realistic problem of microtubule dynamic instability modulated by a motor-dependent increase in the filament catastrophe frequency. This leads to a significant decrease in the mean filament length and a narrowing of the filament length distribution. The results improve our understanding of the biophysics of length regulation in cells. (paper)

Physical principles of filamentous protein self-assembly kinetics

Science.gov (United States)

Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.

2017-04-01

The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.

Cadmium induces cadmium-tolerant gene expression in the filamentous fungus Trichoderma harzianum.

Science.gov (United States)

Cacciola, Santa O; Puglisi, Ivana; Faedda, Roberto; Sanzaro, Vincenzo; Pane, Antonella; Lo Piero, Angela R; Evoli, Maria; Petrone, Goffredo

2015-11-01

The filamentous fungus Trichoderma harzianum, strain IMI 393899, was able to grow in the presence of the heavy metals cadmium and mercury. The main objective of this research was to study the molecular mechanisms underlying the tolerance of the fungus T. harzianum to cadmium. The suppression subtractive hybridization (SSH) method was used for the characterization of the genes of T. harzianum implicated in cadmium tolerance compared with those expressed in the response to the stress induced by mercury. Finally, the effects of cadmium exposure were also validated by measuring the expression levels of the putative genes coding for a glucose transporter, a plasma membrane ATPase, a Cd(2+)/Zn(2+) transporter protein and a two-component system sensor histidine kinase YcbA, by real-time-PCR. By using the aforementioned SSH strategy, it was possible to identify 108 differentially expressed genes of the strain IMI 393899 of T. harzianum grown in a mineral substrate with the addition of cadmium. The expressed sequence tags identified by SSH technique were encoding different genes that may be involved in different biological processes, including those associated to primary and secondary metabolism, intracellular transport, transcription factors, cell defence, signal transduction, DNA metabolism, cell growth and protein synthesis. Finally, the results show that in the mechanism of tolerance to cadmium a possible signal transduction pathway could activate a Cd(2+)/Zn(2+) transporter protein and/or a plasma membrane ATPase that could be involved in the compartmentalization of cadmium inside the cell.

On the fragmentation of filaments in a molecular cloud simulation

Science.gov (United States)

Chira, R.-A.; Kainulainen, J.; Ibáñez-Mejía, J. C.; Henning, Th.; Mac Low, M.-M.

2018-03-01

Context. The fragmentation of filaments in molecular clouds has attracted a lot of attention recently as there seems to be a close relation between the evolution of filaments and star formation. The study of the fragmentation process has been motivated by simple analytical models. However, only a few comprehensive studies have analysed the evolution of filaments using numerical simulations where the filaments form self-consistently as part of large-scale molecular cloud evolution. Aim. We address the early evolution of parsec-scale filaments that form within individual clouds. In particular, we focus on three questions: How do the line masses of filaments evolve? How and when do the filaments fragment? How does the fragmentation relate to the line masses of the filaments? Methods: We examine three simulated molecular clouds formed in kiloparsec-scale numerical simulations performed with the FLASH adaptive mesh refinement magnetohydrodynamic code. The simulations model a self-gravitating, magnetised, stratified, supernova-driven interstellar medium, including photoelectric heating and radiative cooling. We follow the evolution of the clouds for 6 Myr from the time self-gravity starts to act. We identify filaments using the DisPerSe algorithm, and compare the results to other filament-finding algorithms. We determine the properties of the identified filaments and compare them with the predictions of analytic filament stability models. Results: The average line masses of the identified filaments, as well as the fraction of mass in filamentary structures, increases fairly continuously after the onset of self-gravity. The filaments show fragmentation starting relatively early: the first fragments appear when the line masses lie well below the critical line mass of Ostriker's isolated hydrostatic equilibrium solution ( 16 M⊙ pc-1), commonly used as a fragmentation criterion. The average line masses of filaments identified in three-dimensional volume density cubes

QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

Energy Technology Data Exchange (ETDEWEB)

WEST,WP; BURRELL,KH; deGRASSIE,JS; DOYLE,EJ; GREENFIELD,CM; LASNIER,CJ; SNYDER,PB; ZENG,L

2003-08-01

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.

QUIESCENT H-MODE, AN ELM-FREE HIGH-CONFINEMENT MODE ON DIII-D WITH POTENTIAL FOR STATIONARY STATE OPERATION

International Nuclear Information System (INIS)

WEST, WP; BURRELL, KH; DeGRASSIE, JS; DOYLE, EJ; GREENFIELD, CM; LASNIER, CJ; SNYDER, PB; ZENG, L.

2003-01-01

OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D α time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with β N *H 89L product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved

Flux Cancellation Leading to CME Filament Eruptions

Science.gov (United States)

Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

Various Barbs in Solar Filaments

Science.gov (United States)

Filippov, Boris

2017-07-01

Interest to lateral details of the solar filament shape named barbs, motivated by their relationship to filament chirality and helicity, showed their different orientation relative to the expected direction of the magnetic field. While the majority of barbs are stretched along the field, some barbs seem to be transversal to it and are referred to as anomalous barbs. We analyse the deformation of helical field lines by a small parasitic polarity using a simple flux rope model with a force-free field. A rather small and distant source of parasitic polarity stretches the bottom parts of the helical lines in its direction creating a lateral extension of dips below the flux-rope axis. They can be considered as normal barbs of the filament. A stronger and closer source of parasitic polarity makes the flux-rope field lines to be convex below its axis and creates narrow and deep dips near its position. As a result, the narrow structure, with thin threads across it, is formed whose axis is nearly perpendicular to the field. The structure resembles an anomalous barb. Hence, the presence of anomalous barbs does not contradict the flux-rope structure of a filament.

Evolution of Edge Pedestal Profiles Between ELMs

Science.gov (United States)

Floyd, J. P.; Stacey, W. M.; Groebner, R. J.

2012-10-01

The measured edge profile evolution in DIII-D discharges is analyzed in terms of the implied thermal diffusivities, ion diffusion coefficients and pinch velocities, using the momentum-balance methodology of Ref. [1], extended to take into account ion orbit loss and X-point loss. The evolution of the density, temperature, rotation and radial electric field profiles in the edge pedestal between edge localized modes (ELMs) provides information of these diffusive and non-diffusive transport processes in the pedestal of H-mode plasmas. This methodology is incorporated in the GTEDGE code developed for DIII-D data interpretation. Using a smaller integration time for the charge exchange recombination measurements than in Ref. [1] allows a more detailed examination of the time evolution of the ion temperature and rotation profiles. 6pt [1] W.M. Stacey and R.J. Groebner, Nucl. Fusion 51, 063024 (2011).

Numerical simulation of laser filamentation in underdense plasma

International Nuclear Information System (INIS)

Yu Lichun; Chen Zhihua; Tu Qinfen

2000-01-01

Developing process of filamentation and effect of characteristic parameters in underdense plasma have been studied using numerical simulation method. Production and development of two-dimensional cylinder filamentation instability were presented clearly. The results indicate incidence laser intensity and plasma background density are important factors affecting convergent intensity. At the same time, it was showed that different laser wavelength or different electron background density could affect filamentation process. The results are consistent with theory and experiments of alien reports. It can provide reference for restraining filamentation

Intrusion detection system using Online Sequence Extreme Learning Machine (OS-ELM in advanced metering infrastructure of smart grid.

Directory of Open Access Journals (Sweden)

Yuancheng Li

Full Text Available Advanced Metering Infrastructure (AMI realizes a two-way communication of electricity data through by interconnecting with a computer network as the core component of the smart grid. Meanwhile, it brings many new security threats and the traditional intrusion detection method can't satisfy the security requirements of AMI. In this paper, an intrusion detection system based on Online Sequence Extreme Learning Machine (OS-ELM is established, which is used to detecting the attack in AMI and carrying out the comparative analysis with other algorithms. Simulation results show that, compared with other intrusion detection methods, intrusion detection method based on OS-ELM is more superior in detection speed and accuracy.

Beam wandering of femtosecond laser filament in air.

Science.gov (United States)

Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

2015-10-05

The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.

Investigating the use of curcumin-loaded electrospun filaments for soft tissue repair applications

Directory of Open Access Journals (Sweden)

Mouthuy PA

2017-05-01

Full Text Available Pierre-Alexis Mouthuy,1,2 Maja Somogyi Škoc,3 Ana Čipak Gašparović,1 Lidija Milković,1 Andrew J Carr,2 Neven Žarković1 1Laboratory for Oxidative Stress, Rudjer Boskovic Institute, Zagreb, Croatia; 2Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Medical Science Division, University of Oxford, Oxford, UK; 3Department of Materials, Fibres and Textile Testing, University of Zagreb, Zagreb, Croatia Abstract: Electrospun filaments represent a new generation of medical textiles with promising applications in soft tissue repair. A potential strategy to improve their design is to combine them with bioactive molecules. Curcumin, a natural compound found in turmeric, is particularly attractive for its antioxidant, anti-inflammatory, and antimicrobial properties. However, investigating the range of relevant doses of curcumin in materials designed for tissue regeneration has remained limited. In this paper, a wide range of curcumin concentrations was explored and the potential of the resulting materials for soft tissue repair applications was assessed. Polydioxanone (PDO filaments were prepared with various amounts of curcumin: 0%, 0.001%, 0.01%, 0.1%, 1%, and 10% (weight to weight ratio. The results from the present study showed that, at low doses (≤0.1%, the addition of curcumin has no influence on the spinning process or on the physicochemical properties of the filaments, whereas higher doses lead to smaller fiber diameters and improved mechanical properties. Moreover, filaments with 0.001% and 0.01% curcumin stimulate the metabolic activity and proliferation of normal human dermal fibroblasts (NHDFs compared with the no-filament control. However, this stimulation is not significant when compared to the control filaments (0%. Highly dosed filaments induce either the inhibition of proliferation (with 1% or cell apoptosis (with 10% as a result of the concentrations of curcumin found in the

Dimensional quantization effects in the thermodynamics of conductive filaments

Science.gov (United States)

Niraula, D.; Grice, C. R.; Karpov, V. G.

2018-06-01

We consider the physical effects of dimensional quantization in conductive filaments that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin filament acquires a positive charge. Several applications of this finding include the host material polarization, the stability of filament constrictions, the equilibrium filament radius, polarity in device switching, and quantization of conductance.

The THMIS-MTR observation of a active region filament

Science.gov (United States)

Zong, W. G.; Tang, Y. H.; Fang, C.

We present some THMIS-MTR observations of a active region filament on September 4, 2002. The full stokes parameters of the filament were obtained in Hα, CaII 8542 and FeI 6302. By use of the data with high spatial resolution(0.44" per pixel), we probed the fine structure of the filament and gave out the parameters at the barbs' endpoints, including intensity, velocity and longitudinal magnetic field. Comparing the quiescent filament which we have discussed before, we find that: 1)The velocities of the barbs' endpoints are much bigger in the active region filament, the values are more than one thousand meters per second. 2)The barbs' endpoints terminate at the low logitudinal magnetic field in the active region filament, too.

Estimation of the dust production rate from the tungsten armour after repetitive ELM-like heat loads

Science.gov (United States)

Pestchanyi, S.; Garkusha, I.; Makhlaj, V.; Landman, I.

2011-12-01

Experimental simulations for the erosion rate of tungsten targets under ITER edge-localized mode (ELM)-like surface heat loads of 0.75 MJ m-2 causing surface melting and of 0.45 MJ m-2 without melting have been performed in the QSPA-Kh50 plasma accelerator. Analytical considerations allow us to conclude that for both energy deposition values the erosion mechanism is solid dust ejection during surface cracking under the action of thermo-stress. Tungsten influx into the ITER containment of NW~5×1018 W per medium size ELM of 0.75 MJ m-2 and 0.25 ms time duration has been estimated. The radiation cooling power of Prad=150-300 MW due to such influx of tungsten is intolerable: it should cool the ITER core to 1 keV within a few seconds.

Estimation of the dust production rate from the tungsten armour after repetitive ELM-like heat loads

International Nuclear Information System (INIS)

Pestchanyi, S; Landman, I; Garkusha, I; Makhlaj, V

2011-01-01

Experimental simulations for the erosion rate of tungsten targets under ITER edge-localized mode (ELM)-like surface heat loads of 0.75 MJ m - 2 causing surface melting and of 0.45 MJ m - 2 without melting have been performed in the QSPA-Kh50 plasma accelerator. Analytical considerations allow us to conclude that for both energy deposition values the erosion mechanism is solid dust ejection during surface cracking under the action of thermo-stress. Tungsten influx into the ITER containment of N W ∼5×10 18 W per medium size ELM of 0.75 MJ m - 2 and 0.25 ms time duration has been estimated. The radiation cooling power of P rad =150-300 MW due to such influx of tungsten is intolerable: it should cool the ITER core to 1 keV within a few seconds.

Physical principles of filamentous protein self-assembly kinetics

International Nuclear Information System (INIS)

Michaels, Thomas C T; Liu, Lucie X; Meisl, Georg; Knowles, Tuomas P J

2017-01-01

The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes. (topical review)

Comparison of SVM, RF and ELM on an Electronic Nose for the Intelligent Evaluation of Paraffin Samples

Directory of Open Access Journals (Sweden)

Hong Men

2018-01-01

Full Text Available Paraffin odor intensity is an important quality indicator when a paraffin inspection is performed. Currently, paraffin odor level assessment is mainly dependent on an artificial sensory evaluation. In this paper, we developed a paraffin odor analysis system to classify and grade four kinds of paraffin samples. The original feature set was optimized using Principal Component Analysis (PCA and Partial Least Squares (PLS. Support Vector Machine (SVM, Random Forest (RF, and Extreme Learning Machine (ELM were applied to three different feature data sets for classification and level assessment of paraffin. For classification, the model based on SVM, with an accuracy rate of 100%, was superior to that based on RF, with an accuracy rate of 98.33–100%, and ELM, with an accuracy rate of 98.01–100%. For level assessment, the R2 related to the training set was above 0.97 and the R2 related to the test set was above 0.87. Through comprehensive comparison, the generalization of the model based on ELM was superior to those based on SVM and RF. The scoring errors for the three models were 0.0016–0.3494, lower than the error of 0.5–1.0 measured by industry standard experts, meaning these methods have a higher prediction accuracy for scoring paraffin level.

Calpain-mediated proteolysis of tropomodulin isoforms leads to thin filament elongation in dystrophic skeletal muscle.

Science.gov (United States)

Gokhin, David S; Tierney, Matthew T; Sui, Zhenhua; Sacco, Alessandra; Fowler, Velia M

2014-03-01

Duchenne muscular dystrophy (DMD) induces sarcolemmal mechanical instability and rupture, hyperactivity of intracellular calpains, and proteolytic breakdown of muscle structural proteins. Here we identify the two sarcomeric tropomodulin (Tmod) isoforms, Tmod1 and Tmod4, as novel proteolytic targets of m-calpain, with Tmod1 exhibiting ∼10-fold greater sensitivity to calpain-mediated cleavage than Tmod4 in situ. In mdx mice, increased m-calpain levels in dystrophic soleus muscle are associated with loss of Tmod1 from the thin filament pointed ends, resulting in ∼11% increase in thin filament lengths. In mdx/mTR mice, a more severe model of DMD, Tmod1 disappears from the thin filament pointed ends in both tibialis anterior (TA) and soleus muscles, whereas Tmod4 additionally disappears from soleus muscle, resulting in thin filament length increases of ∼10 and ∼12% in TA and soleus muscles, respectively. In both mdx and mdx/mTR mice, both TA and soleus muscles exhibit normal localization of α-actinin, the nebulin M1M2M3 domain, Tmod3, and cytoplasmic γ-actin, indicating that m-calpain does not cause wholesale proteolysis of other sarcomeric and actin cytoskeletal proteins in dystrophic skeletal muscle. These results implicate Tmod proteolysis and resultant thin filament length misspecification as novel mechanisms that may contribute to DMD pathology, affecting muscles in a use- and disease severity-dependent manner.

Transition from linear- to nonlinear-focusing regime in filamentation

Science.gov (United States)

Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin

2014-01-01

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature. PMID:25434678

Use of protoplast, cell, and shoot tip culture in an elm germ plasm improvement program

Science.gov (United States)

R. Daniel Lineberger; M.B. Sticklen; P.M. Pijut; Mark A. Kroggel; C.V.M. Fink; S.C. Domir

1990-01-01

An elm germplasm improvement program was established using three distinct approaches: (1) development of protoplast regeneration protocols with the goal of attempting somatic hybridization between Ulmus americana and disease resistant hybrids; (2) evaluation of the extent of somaclonal variation in plants regenerated from protoplasts; and (3)...

Large scale filaments associated with Milky Way spiral arms

Science.gov (United States)

Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, Malcolm; Molinari, Sergio; Schisano, Eugenio

2015-08-01

The ubiquity of filamentary structure at various scales through out the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e., as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel Hi-GAL data complemented by spectral line cubes. We present a sample of the 9 most prominent Herschel filaments from a pilot search field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)×104 Msun, and beam-averaged (28", or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)x1022 cm-2. The bulk of the filaments are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K due to local star formation activities. All the filaments are located within spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These filaments are comparable in length to the Galactic scale height and therefore are not simply part of a grander turbulent cascade. These giant filaments, which often contain regularly spaced pc-scale clumps, are much larger than the filaments found in the Herschel Gould's Belt Survey, and they form the upper ends in the filamentary hierarchy. Full operational ALMA and NOEMA will be able to resolve and characterize similar filaments in nearby spiral galaxies, allowing us to compare the star formation in a uniform context of spiral arms.

Intense EM filamentation in relativistic hot plasmas

Energy Technology Data Exchange (ETDEWEB)

Hu, Qiang-Lin [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Chen, Zhong-Ping [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Mahajan, Swadesh M., E-mail: mahajan@mail.utexas.edu [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Physics, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314 (India)

2017-03-03

Highlights: • Breaking up of an intense EM pulse into filaments is a spectacular demonstration of the nonlinear wave-plasma interaction. • Filaments are spectacularly sharper, highly extended and longer lived at relativistic temperatures. • EM energy concentration can trigger new nonlinear phenomena with absolute consequences for high energy density matter. - Abstract: Through 2D particle-in-cell (PIC) simulations, we demonstrate that the nature of filamentation of a high intensity electromagnetic (EM) pulse propagating in an underdense plasma, is profoundly affected at relativistically high temperatures. The “relativistic” filaments are sharper, are dramatically extended (along the direction of propagation), and live much longer than their lower temperature counterparts. The thermally boosted electron inertia is invoked to understand this very interesting and powerful phenomenon.

High-resolution electron microscopic evidence for the filamentous structure of the cyst wall in Giardia muris and Giardia duodenalis.

Science.gov (United States)

Erlandsen, S L; Bemrick, W J; Pawley, J

1989-10-01

High-resolution morphological studies of the cyst wall of Giardia spp. were performed using low-voltage scanning electron microscopy (LVSEM) and transmission electron microscopy (TEM). The cyst wall was composed of membranous and filamentous layers. The membranous layer consisted of an inner and an outer cyst membrane separated by a thin layer of cytoplasm. The filamentous layer contained individual filaments that ranged from 7 to 20 nm in diameter when measured by LVSEM, formed a dense meshwork with branches or interconnections, and were occasionally arranged on the surface in whorled patterns. Cysts of Giardia muris from mice, Giardia duodenalis from dogs, pigs, voles, beavers, muskrats, and humans, and Giardia psittaci from a bird (parakeet), possessed an essentially identical wall composed of filaments. Inducement of excystation in viable Giardia cysts produced a dramatic increase in the interfilament spacing over an entire cyst, but none was observed in heat-killed or chemically fixed control cysts. These results demonstrated that the cyst wall of Giardia spp. was composed of a complex arrangement of filaments, presumably formed during the process of encystment.

Ca2+ improves organization of single-stranded DNA bases in human Rad51 filament, explaining stimulatory effect on gene recombination.

KAUST Repository

Fornander, Louise H

2012-02-22

Human RAD51 protein (HsRad51) catalyses the DNA strand exchange reaction for homologous recombination. To clarify the molecular mechanism of the reaction in vitro being more effective in the presence of Ca(2+) than of Mg(2+), we have investigated the effect of these ions on the structure of HsRad51 filament complexes with single- and double-stranded DNA, the reaction intermediates. Flow linear dichroism spectroscopy shows that the two ionic conditions induce significantly different structures in the HsRad51/single-stranded DNA complex, while the HsRad51/double-stranded DNA complex does not demonstrate this ionic dependence. In the HsRad51/single-stranded DNA filament, the primary intermediate of the strand exchange reaction, ATP/Ca(2+) induces an ordered conformation of DNA, with preferentially perpendicular orientation of nucleobases relative to the filament axis, while the presence of ATP/Mg(2+), ADP/Mg(2+) or ADP/Ca(2+) does not. A high strand exchange activity is observed for the filament formed with ATP/Ca(2+), whereas the other filaments exhibit lower activity. Molecular modelling suggests that the structural variation is caused by the divalent cation interfering with the L2 loop close to the DNA-binding site. It is proposed that the larger Ca(2+) stabilizes the loop conformation and thereby the protein-DNA interaction. A tight binding of DNA, with bases perpendicularly oriented, could facilitate strand exchange.

Morphological changes of the filamentous fungus Mucor mucedo and inhibition of chitin synthase activity induced by anethole.

Science.gov (United States)

Yutani, Masahiro; Hashimoto, Yukie; Ogita, Akira; Kubo, Isao; Tanaka, Toshio; Fujita, Ken-ichi

2011-11-01

trans-Anethole (anethole), a major component of anise oil, has a broad antimicrobial spectrum with antimicrobial activity relatively weaker than those of well-known antibiotics, and significantly enhances the antifungal activity of polygodial and dodecanol against the baker's yeast Saccharomyces cerevisiae and human pathogenic yeast Candida albicans. However, the antifungal mechanism of anethole is unresolved. Anethole demonstrated antifungal activity against the filamentous fungus, Mucor mucedo IFO 7684, accompanied by hyphal morphological changes such as swollen hyphae at the tips. Its minimum growth inhibitory concentration was 0.625 mM. A hyperosmotic condition (1.2 M sorbitol) restricted the induction of morphological changes, while hypoosmotic treatment (distilled water) induced bursting of hyphal tips and leakage of cytoplasmic constituents. Furthermore, anethole dose-dependently inhibited chitin synthase (CHS) activity in permeabilized hyphae in an uncompetitive manner. These results suggest that the morphological changes of M. mucedo could be explained by the fragility of cell walls caused by CHS inhibition. Copyright © 2011 John Wiley & Sons, Ltd.

Actin filaments regulate the adhesion between the plasma membrane and the cell wall of tobacco guard cells.

Science.gov (United States)

Yu, Qin; Ren, Jing-Jing; Kong, Lan-Jing; Wang, Xiu-Ling

2018-01-01

During the opening and closing of stomata, guard cells undergo rapid and reversible changes in their volume and shape, which affects the adhesion of the plasma membrane (PM) to the cell wall (CW). The dynamics of actin filaments in guard cells are involved in stomatal movement by regulating structural changes and intracellular signaling. However, it is unclear whether actin dynamics regulate the adhesion of the PM to the CW. In this study, we investigated the relationship between actin dynamics and PM-CW adhesion by the hyperosmotic-induced plasmolysis of tobacco guard cells. We found that actin filaments in guard cells were depolymerized during mannitol-induced plasmolysis. The inhibition of actin dynamics by treatment with latrunculin B or jasplakinolide and the disruption of the adhesion between the PM and the CW by treatment with RGDS peptide (Arg-Gly-Asp-Ser) enhanced guard cell plasmolysis. However, treatment with latrunculin B alleviated the RGDS peptide-induced plasmolysis and endocytosis. Our results reveal that the actin depolymerization is involved in the regulation of the PW-CW adhesion during hyperosmotic-induced plasmolysis in tobacco guard cells.

Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin Filament Bundles in the Cytoskeleton Is Independent of Actin Filament Kinetics.

Science.gov (United States)

Appaduray, Mark A; Masedunskas, Andrius; Bryce, Nicole S; Lucas, Christine A; Warren, Sean C; Timpson, Paul; Stear, Jeffrey H; Gunning, Peter W; Hardeman, Edna C

2016-01-01

The actin cytoskeleton is a dynamic network of filaments that is involved in virtually every cellular process. Most actin filaments in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin filament is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during filament assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin filament bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin filament bundles largely independent of the assembly and turnover of actin.

Nonlinear simulations of particle source effects on edge localized mode

Energy Technology Data Exchange (ETDEWEB)

Huang, J.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, S. Y., E-mail: sychen531@163.com [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)

2015-12-15

The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadening of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.

Filamentous Fungi Fermentation

DEFF Research Database (Denmark)

Nørregaard, Anders; Stocks, Stuart; Woodley, John

2014-01-01

Filamentous fungi (including microorganisms such as Aspergillus niger and Rhizopus oryzae) represent an enormously important platform for industrial fermentation. Two particularly valuable features are the high yield coefficients and the ability to secrete products. However, the filamentous...... morphology, together with non-Newtonian rheological properties (shear thinning), result in poor oxygen transfer unless sufficient energy is provided to the fermentation. While genomic research may improve the organisms, there is no doubt that to enable further application in future it will be necessary...... to match such research with studies of oxygen transfer and energy supply to high viscosity fluids. Hence, the implementation of innovative solutions (some of which in principle are already possible) will be essential to ensure the further development of such fermentations....

Mechanical model for filament buckling and growth by phase ordering.

Science.gov (United States)

Rey, Alejandro D; Abukhdeir, Nasser M

2008-02-05

A mechanical model of open filament shape and growth driven by phase ordering is formulated. For a given phase-ordering driving force, the model output is the filament shape evolution and the filament end-point kinematics. The linearized model for the slope of the filament is the Cahn-Hilliard model of spinodal decomposition, where the buckling corresponds to concentration fluctuations. Two modes are predicted: (i) sequential growth and buckling and (ii) simultaneous buckling and growth. The relation among the maximum buckling rate, filament tension, and matrix viscosity is given. These results contribute to ongoing work in smectic A filament buckling.

Chirality of Intermediate Filaments and Magnetic Helicity of Active Regions

Science.gov (United States)

Lim, Eun-Kyung; Chae, J.

2009-05-01

Filaments that form either between or around active regions (ARs) are called intermediate filaments. Even though there have been many theoretical studies, the origin of the chirality of filaments is still unknown. We investigated how intermediate filaments are related to their associated ARs, especially from the point of view of magnetic helicity and the orientation of polarity inversion lines (PILs). The chirality of filaments has been determined based on the orientations of barbs observed in the full-disk Hα images taken at Big Bear Solar Observatory during the rising phase of solar cycle 23. The sign of magnetic helicity of ARs has been determined using S/inverse-S shaped sigmoids from Yohkoh SXT images. As a result, we have found a good correlation between the chirality of filaments and the magnetic helicity sign of ARs. Among 45 filaments, 42 filaments have shown the same sign as helicity sign of nearby ARs. It has been also confirmed that the role of both the orientation and the relative direction of PILs to ARs in determining the chirality of filaments is not significant, against a theoretical prediction. These results suggest that the chirality of intermediate filaments may originate from magnetic helicity of their associated ARs.

Disintegration of an eruptive filament via interactions with quasi-separatrix layers

Science.gov (United States)

Liu, Rui; Chen, Jun; Wang, YuMing

2018-06-01

The disintegration of solar filaments via mass drainage is a frequently observed phenomenon during a variety of filament activities. It is generally considered that the draining of dense filament material is directed by both gravity and magnetic field, yet the detailed process remains elusive. Here we report on a partial filament eruption during which filament material drains downward to the surface not only along the filament's legs, but to a remote flare ribbon through a fan-out curtain-like structure. It is found that the magnetic configuration is characterized by two conjoining dome-like quasi-sepratrix layers (QSLs). The filament is located underneath one QSL dome, whose footprint apparently bounds the major flare ribbons resulting from the filament eruption, whereas the remote flare ribbon matches well with the other QSL dome's far-side footprint. We suggest that the interaction of the filament with the overlying QSLs results in the splitting and disintegration of the filament.

Microwave structure of quiescent solar filaments at high resolution