The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Ivan Cunha Nascimento - One of the best experts on this subject based on the ideXlab platform.
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Transport Threshold Model of subsonic neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, Ivan Cunha NascimentoAbstract:A transport Threshold Model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation and to complement this equation with the single-fluid parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport, which is the precondition for developing the above Model. It is shown that the subsonic NTMs transport Threshold Model can be more realistic than the standard transport Model of NTMs suggested by Fitzpatrick [Phys. Plasmas 2, 825 (1995)].
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Fluid treatment of convective-transport Threshold Model of neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, S. V. Konovalov, Ivan Cunha NascimentoAbstract:A fluid treatment of convective-transport Threshold Model of neoclassical tearing modes (NTMs) in tokamaks is developed. A Grad-type system of moment equations of the drift kinetic equation with a Model perpendicular transport is derived. The essence of this moment equation system is to allow for the parallel heat flux on an equal footing with pressure and temperature, what goes beyond the scope of the Braginskii approach. The suggested moment equation system is applied for analyzing the bootstrap current drive of NTMs. As a result, a Threshold Model of these modes is derived, which coincides qualitatively with the convective-transport Threshold Model initially formulated by means of intuitive considerations.
V. S. Tsypin - One of the best experts on this subject based on the ideXlab platform.
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Fluid treatment of convective-transport Threshold Model of neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, S. V. Konovalov, Ivan Cunha NascimentoAbstract:A fluid treatment of convective-transport Threshold Model of neoclassical tearing modes (NTMs) in tokamaks is developed. A Grad-type system of moment equations of the drift kinetic equation with a Model perpendicular transport is derived. The essence of this moment equation system is to allow for the parallel heat flux on an equal footing with pressure and temperature, what goes beyond the scope of the Braginskii approach. The suggested moment equation system is applied for analyzing the bootstrap current drive of NTMs. As a result, a Threshold Model of these modes is derived, which coincides qualitatively with the convective-transport Threshold Model initially formulated by means of intuitive considerations.
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Transport Threshold Model of subsonic neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, Ivan Cunha NascimentoAbstract:A transport Threshold Model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation and to complement this equation with the single-fluid parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport, which is the precondition for developing the above Model. It is shown that the subsonic NTMs transport Threshold Model can be more realistic than the standard transport Model of NTMs suggested by Fitzpatrick [Phys. Plasmas 2, 825 (1995)].
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Rotation-transport Threshold Model of neoclassical tearing modes
Plasma Physics and Controlled Fusion, 2002Co-Authors: Sergey Konovalov, A. B. Mikhailovskii, M. S. Shirokov, V. S. TsypinAbstract:A rotation-transport Threshold Model of neoclassical tearing modes (NTMs) is suggested. It is assumed that weakening of the bootstrap current effect is determined by competition of perpendicular transport and island rotation, which is in contrast to the known transport Threshold Models dealing with the parallel transport or parallel convection instead of island rotation. It is shown that for sufficiently strong island rotation the perpendicular transport does not lead to decreasing the bootstrap current contribution into the island width evolution equation. It is explained that the island rotation can prevail over the parallel transport/convection mainly for the case of ion contribution into the bootstrap current effect. Interrelation between the rotation-transport Threshold Model and the known ones is discussed. A generalized transport Threshold Model of NTMs describing the competition of the perpendicular transport with the island rotation, parallel transport and parallel convection is formulated. It is shown that the perpendicular transport can lead to weakening the bootstrap drive contribution only if it overpowers all the competitive effects.
A. B. Mikhailovskii - One of the best experts on this subject based on the ideXlab platform.
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Fluid treatment of convective-transport Threshold Model of neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, S. V. Konovalov, Ivan Cunha NascimentoAbstract:A fluid treatment of convective-transport Threshold Model of neoclassical tearing modes (NTMs) in tokamaks is developed. A Grad-type system of moment equations of the drift kinetic equation with a Model perpendicular transport is derived. The essence of this moment equation system is to allow for the parallel heat flux on an equal footing with pressure and temperature, what goes beyond the scope of the Braginskii approach. The suggested moment equation system is applied for analyzing the bootstrap current drive of NTMs. As a result, a Threshold Model of these modes is derived, which coincides qualitatively with the convective-transport Threshold Model initially formulated by means of intuitive considerations.
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Transport Threshold Model of subsonic neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, Ivan Cunha NascimentoAbstract:A transport Threshold Model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation and to complement this equation with the single-fluid parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport, which is the precondition for developing the above Model. It is shown that the subsonic NTMs transport Threshold Model can be more realistic than the standard transport Model of NTMs suggested by Fitzpatrick [Phys. Plasmas 2, 825 (1995)].
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Rotation-transport Threshold Model of neoclassical tearing modes
Plasma Physics and Controlled Fusion, 2002Co-Authors: Sergey Konovalov, A. B. Mikhailovskii, M. S. Shirokov, V. S. TsypinAbstract:A rotation-transport Threshold Model of neoclassical tearing modes (NTMs) is suggested. It is assumed that weakening of the bootstrap current effect is determined by competition of perpendicular transport and island rotation, which is in contrast to the known transport Threshold Models dealing with the parallel transport or parallel convection instead of island rotation. It is shown that for sufficiently strong island rotation the perpendicular transport does not lead to decreasing the bootstrap current contribution into the island width evolution equation. It is explained that the island rotation can prevail over the parallel transport/convection mainly for the case of ion contribution into the bootstrap current effect. Interrelation between the rotation-transport Threshold Model and the known ones is discussed. A generalized transport Threshold Model of NTMs describing the competition of the perpendicular transport with the island rotation, parallel transport and parallel convection is formulated. It is shown that the perpendicular transport can lead to weakening the bootstrap drive contribution only if it overpowers all the competitive effects.
M. S. Shirokov - One of the best experts on this subject based on the ideXlab platform.
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Fluid treatment of convective-transport Threshold Model of neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, S. V. Konovalov, Ivan Cunha NascimentoAbstract:A fluid treatment of convective-transport Threshold Model of neoclassical tearing modes (NTMs) in tokamaks is developed. A Grad-type system of moment equations of the drift kinetic equation with a Model perpendicular transport is derived. The essence of this moment equation system is to allow for the parallel heat flux on an equal footing with pressure and temperature, what goes beyond the scope of the Braginskii approach. The suggested moment equation system is applied for analyzing the bootstrap current drive of NTMs. As a result, a Threshold Model of these modes is derived, which coincides qualitatively with the convective-transport Threshold Model initially formulated by means of intuitive considerations.
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Transport Threshold Model of subsonic neoclassical tearing modes in tokamaks
Physics of Plasmas, 2003Co-Authors: A. B. Mikhailovskii, Sergey Konovalov, M. S. Shirokov, V. S. Tsypin, Takahisa Ozeki, Tomonori Takizuka, Ricardo Magnus Osorio Galvao, Ivan Cunha NascimentoAbstract:A transport Threshold Model of subsonic neoclassical tearing modes (NTMs) in tokamaks is developed. The basic procedure is to include the velocity-dependent term into the single-fluid heat-conductivity equation and to complement this equation with the single-fluid parallel plasma motion equation. These equations permit the determination of the perturbed plasma temperature and the bootstrap current drive of NTMs, for both strong and weak perpendicular heat transport, which is the precondition for developing the above Model. It is shown that the subsonic NTMs transport Threshold Model can be more realistic than the standard transport Model of NTMs suggested by Fitzpatrick [Phys. Plasmas 2, 825 (1995)].
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Rotation-transport Threshold Model of neoclassical tearing modes
Plasma Physics and Controlled Fusion, 2002Co-Authors: Sergey Konovalov, A. B. Mikhailovskii, M. S. Shirokov, V. S. TsypinAbstract:A rotation-transport Threshold Model of neoclassical tearing modes (NTMs) is suggested. It is assumed that weakening of the bootstrap current effect is determined by competition of perpendicular transport and island rotation, which is in contrast to the known transport Threshold Models dealing with the parallel transport or parallel convection instead of island rotation. It is shown that for sufficiently strong island rotation the perpendicular transport does not lead to decreasing the bootstrap current contribution into the island width evolution equation. It is explained that the island rotation can prevail over the parallel transport/convection mainly for the case of ion contribution into the bootstrap current effect. Interrelation between the rotation-transport Threshold Model and the known ones is discussed. A generalized transport Threshold Model of NTMs describing the competition of the perpendicular transport with the island rotation, parallel transport and parallel convection is formulated. It is shown that the perpendicular transport can lead to weakening the bootstrap drive contribution only if it overpowers all the competitive effects.
Edward J. Calabrese - One of the best experts on this subject based on the ideXlab platform.
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Getting the dose–response wrong: why hormesis became marginalized and the Threshold Model accepted
Archives of Toxicology, 2009Co-Authors: Edward J. CalabreseAbstract:The dose–response relationship is central to the biological and biomedical sciences. During the early decades of the twentieth century consensus emerged that the most fundamental dose–response relationship was the Threshold Model, upon which scientific, health and medical research/clinical practices have been based. This paper documents that the scientific community made a fundamental error on the nature of the dose response in accepting the Threshold Model and in rejecting the hormetic-biphasic Model, principally due to conflicts with homeopathy. Not only does this paper detail the underlying factors leading to this dose response decision, but it reveals that the scientific community never validated the Threshold Model throughout the twentieth century. Recent findings indicate that the Threshold Model poorly predicts responses in the low dose zone whereas its dose response “rival”, the hormesis Model, has performed very well. This analysis challenges a key foundation upon which biological, biomedical and clinical science rest.
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getting the dose response wrong why hormesis became marginalized and the Threshold Model accepted
Archives of Toxicology, 2009Co-Authors: Edward J. CalabreseAbstract:The dose–response relationship is central to the biological and biomedical sciences. During the early decades of the twentieth century consensus emerged that the most fundamental dose–response relationship was the Threshold Model, upon which scientific, health and medical research/clinical practices have been based. This paper documents that the scientific community made a fundamental error on the nature of the dose response in accepting the Threshold Model and in rejecting the hormetic-biphasic Model, principally due to conflicts with homeopathy. Not only does this paper detail the underlying factors leading to this dose response decision, but it reveals that the scientific community never validated the Threshold Model throughout the twentieth century. Recent findings indicate that the Threshold Model poorly predicts responses in the low dose zone whereas its dose response “rival”, the hormesis Model, has performed very well. This analysis challenges a key foundation upon which biological, biomedical and clinical science rest.
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hormesis outperforms Threshold Model in national cancer institute antitumor drug screening database
Toxicological Sciences, 2006Co-Authors: Edward J. Calabrese, John Staudenmayer, Edward J Stanek, George R. HoffmannAbstract:Which dose-response Model best explains low-dose responses is a critical issue in toxicology, pharmacology, and risk assessment. The present paper utilized the U.S. National Cancer Institute yeast screening database that contains 56,914 dose-response studies representing the replicated effects of 2189 chemically diverse possible antitumor drugs on cell proliferation in 13 different yeast strains. Multiple evaluation methods indicated that the observed data are inconsistent with the Threshold Model while supporting the hormetic Model. Hormetic response patterns were observed approximately four times more often than would be expected by chance alone. The data call for the rejection of the Threshold Model for low-dose prediction, and they support the hormetic Model as the default Model for scientific interpretation of low-dose toxicological responses.
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the hormetic dose response Model is more common than the Threshold Model in toxicology
Toxicological Sciences, 2003Co-Authors: Edward J. Calabrese, Linda A BaldwinAbstract:The Threshold dose-response Model is widely viewed as the most dominant Model in toxicology. The present study was designed to test the validity of the Threshold Model by assessing the responses of doses below the toxicological NOAEL (no observed adverse effect level) in relationship to the control response (i.e., unexposed group). Nearly 1800 doses below the NOAEL, from 664 doseresponse relationships derived from a previously published database that satisfied a priori entry criteria, were evaluated. While the Threshold Model predicts a 1:1 ratio of responses “greater than” to “less than” the control response (i.e., a random distribution), a 2.5:1 ratio (i.e., 1171:464) was observed, reflecting 31% more responses above the control value than expected (p < 0.0001). The mean response (calculated as % control response) of doses below the NOAEL was 115.0% 1.5 standard error of the mean (SEM). These findings challenge the long-standing belief in the primacy of the Threshold Model in toxicology (and other areas of biology involving dose-response relationships) and provide strong support for the hormetic-like biphasic dose-response Model characterized by a low-dose stimulation and a high-dose inhibition. These findings may affect numerous aspects of toxicological and biological/ biomedical research related to dose-response relationships, including study design, risk assessment, as well as chemotherapeutic strategies.
