Magnetorotational Instability in a Couette Flow of Plasma

All experiments, which have been proposed so far to model the magnetorotational instability (MRI) in the laboratory, involve a Couette flow of liquid metals in a rotating annulus. All liquid metals have small magnetic Prandtl numbers, Pm, of about 10^{-6} (the ratio of kinematic viscosity to magnetic diffusivity). With plasmas both large and small Pm are achievable by varying the temperature and the density of plasma. Compressibility and fast rotation of the plasma result in radial stratification of the equilibrium plasma density. Evolution of perturbations in radially stratified viscous and resistive plasma permeated by an axial uniform magnetic field is considered. The differential rotation of the plasma is induced by the ExB drift in applied radial electric field. Global unstable eigenmodes are calculated by our newly developed matrix code. The plasma is shown to be MRI unstable for parameters easily achievable in experimental setup.Comment: 6 pages, 2 figures; to be published in the Proceedings of the 3d Workshop on Non-Neutral Plasmas, July 2003, Santa Fe, US

The Role of Preconceived Ideas in Macroeconomic Policy: Japan's Experiences in the Two Deflationary Periods

This paper examines the role of misleading economic ideas that most likely promoted the economic disasters of the two deflationary periods in Japanese economic history. Misleading ideas deepened the depression during the interwar years, and erroneous thinking prolonged the stagnation of the Japanese economy since the 1990s. While the current framework of political economy is based on the self-interests of political agents as well as of voters, we highlight the role of ideas in policy making, in particular, in the field of macro-economy where the incidence of a particular policy is not clear to the public. Using two significant examples, this paper illustrates the role of preconceived ideas, in contrast to economic interests, that dominantly influenced economic policy making.Preconceived ideas, perception on economic mechanism, vested interests, great depression, deflation in contemporary Japan

The Role of Preconceived Ideas in Macroeconomic Policy: Japan's Experiences in Two Deflationary Periods

This paper examines the role of misleading economic ideas that most likely promoted the economic disasters of the two deflationary periods in Japanese economic history. Misleading ideas deepened the depression during the interwar years, and erroneous thinking has prolonged the stagnation of the Japanese economy since the 1990s. While the current framework of political economy is based on the self-interest of political agents as well as of voters, we highlight the role of ideas in policy making, in particular, in the field of macro-economy where the incidence of a particular policy is not clear to the public. Using two significant examples, this paper illustrates the role of preconceived ideas, in contrast to economic interests, as dominant forces influencing economic policy making.

Compton Spectrum from Poynting Flux Accelerated e+e- Plasma

We report the Compton scattering emission from the Poynting flux acceleration of electron- positron plasma simulated by the 2-1/2 dimensional particle-in-cell(PIC) code. We show these and other remarkable properties of Poynting flux acceleration and Compton spectral output, and discuss the agreement with the observed spectra of GRBs and XRFs.Comment: 4 pages, 4 figures, submitted to Swift GRB Workshop Proceedings 2006 (in press

The role of preconceived ideas in macroeconomic policy: Japan's experiences in the two deflationary periods

This paper examines the role of misleading economic ideas that most likely promoted the economic disasters of the two deflationary periods in Japanese economic history. Misleading ideas deepened the depression during the interwar years, and erroneous thinking prolonged the stagnation of the Japanese economy since the 1990s. While the current framework of political economy is based on the self-interests of political agents as well as of voters, we highlight the role of misleading ideas in policy making, in particular, in the field of macro-economy where the incidence of a particular policy is not clear to the public. Using two significant examples, this paper illustrates the role of preconceived ideas, in contrast to economic interests, that dominantly influenced economic policy making

Yukawa hierarchy from extra dimensions and infrared fixed points

We discuss the existence of hierarchy of Yukawa couplings in the models with extra spatial dimensions. The hierarchical structure is induced by the power behavior of the cutoff dependence of the evolution equations which yield large suppressions of couplings at the compactification scale. The values of coupling constants at this scale can be made stable almost independently of the initial input parameters by utilizing the infrared fixed point. We find that the Yukawa couplings converge to the fixed points very quickly because of the enhanced energy dependence of the suppression factor from extra dimensions as well as in the case of large gauge couplings at high-energy scale.Comment: 13 pages, 3 eps figure

Frequency-dependent ERK phosphorylation in spinal neurons by electric stimulation of the sciatic nerve and the role in electrophysiological activity

The phosphorylation of extracellular signal-regulated kinase (pERK) in DRG and dorsal horn neurons is induced by the C-fiber electrical stimulation to the peripheral nerve. The present study was designed to investigate the expression and modulation of pERK in the rat dorsal horn neurons produced by repetitive electrical stimulation, and its involvement in the electrophysiological activity of dorsal horn neurons. Electrical stimulation of C-fiber intensity at different frequencies was applied to the sciatic nerve; the stimuli-induced pERK expression and the activity in dorsal horn neurons were studied by immunohistochemistry and extracellular recording, respectively. Electrical stimulation of C-fibers (3 mA) induced pERK expression in dorsal horn neurons in a frequency-dependent manner, indicating that the frequency of electrical stimulation is an important factor which activates the intracellular signal pathway in the spinal cord. To demonstrate the underlying mechanism of this frequency-dependent pERK expression, an NMDA receptor antagonist, MK-801, and a voltage sensitive calcium channel antagonist, nifedipine, were administrated intrathecally before the stimulation. We found that high frequency (0.5 Hz and 10 Hz) but not low frequent (0.05 Hz) stimulus-evoked pERK was partially inhibited by MK-801. Both high and low frequency stimulus-evoked pERK were inhibited by the nifedipine treatment. The extracellular single unit activities were recorded from the laminae I-II and V of the L4-5 dorsal horn, and we found that blockage of the intracellular ERK signal suppressed the wind-up responses in a dose-dependent manner. In contrast, any change in the mechanically evoked responses was not observed following the administration of ERK inhibitor. These observations indicate that ERK activation plays an important role in the induction of the wind-up responses in dorsal horn nociceptive neurons