Flame front propagation IV: Random Noise and Pole-Dynamics in Unstable Front Propagation II

The current paper is a corrected version of our previous paper arXiv:adap-org/9608001. Similarly to previous version we investigate the problem of flame propagation. This problem is studied as an example of unstable fronts that wrinkle on many scales. The analytic tool of pole expansion in the complex plane is employed to address the interaction of the unstable growth process with random initial conditions and perturbations. We argue that the effect of random noise is immense and that it can never be neglected in sufficiently large systems. We present simulations that lead to scaling laws for the velocity and acceleration of the front as a function of the system size and the level of noise, and analytic arguments that explain these results in terms of the noisy pole dynamics.This version corrects some very critical errors made in arXiv:adap-org/9608001 and makes more detailed description of excess number of poles in system, number of poles that appear in the system in unit of time, life time of pole. It allows us to understand more correctly dependence of the system parameters on noise than in arXiv:adap-org/9608001Comment: 23 pages, 4 figures,revised, version accepted for publication in journal "Combustion, Explosion and Shock Waves". arXiv admin note: substantial text overlap with arXiv:nlin/0302021, arXiv:adap-org/9608001, arXiv:nlin/030201

Submillimeter ESR spectra of Fe²⁺ ions in synthetic and natural beryl crystals

© 2017, Pleiades Publishing, Ltd. Electron spin resonance spectra of non-Kramers bivalent iron (Fe 2+ ) ions have been detected in synthetic and natural beryl crystals with an iron impurity. The observed ESR spectra have been attributed to resonance transitions of Fe 2+ ions from the ground (singlet) state to excited (doublet) levels with the splitting Δ = 12.7 cm –1 between the levels. The experimental angular and frequency dependences of the resonance field of the ESR signal have been described by the spin Hamiltonian with the effective spin S = 1. The analysis of the ESR data and optical absorption spectra indicates that the Fe 2+ ions are situated in tetrahedral positions and substitute Be 2+ cations in the beryl structure

The United States Congress and nuclear war powers: explaining legislative nonfeasance

Scholarly debate over the role of the United States Congress in approving military action has focused on the respective war powers granted the executive and legislature by the United States Constitution. Although a voluminous literature has examined the institutional and partisan politics shaping their exercise, a conspicuous lacuna concerns nuclear war powers. Despite periodic but mostly ineffective reassertions of congressional prerogatives over war, the decision to employ nuclear weapons has been left entirely to presidential discretion since 1945. Explaining this consistent refusal by Congress to rein in the ultimate presidential power and exercise co-responsibility for the most devastating form of war relies less on disputatious constitutional grounds than on three arguments about congressional dysfunctionality, legislative irresponsibility, and the relative costs of collective action by federal lawmakers on perilous national security questions

Submillimeter ESR spectra of Fe²⁺ ions in synthetic and natural beryl crystals

© 2017, Pleiades Publishing, Ltd. Electron spin resonance spectra of non-Kramers bivalent iron (Fe 2+ ) ions have been detected in synthetic and natural beryl crystals with an iron impurity. The observed ESR spectra have been attributed to resonance transitions of Fe 2+ ions from the ground (singlet) state to excited (doublet) levels with the splitting Δ = 12.7 cm –1 between the levels. The experimental angular and frequency dependences of the resonance field of the ESR signal have been described by the spin Hamiltonian with the effective spin S = 1. The analysis of the ESR data and optical absorption spectra indicates that the Fe 2+ ions are situated in tetrahedral positions and substitute Be 2+ cations in the beryl structure

Submillimeter ESR spectra of Fe²⁺ ions in synthetic and natural beryl crystals

© 2017, Pleiades Publishing, Ltd. Electron spin resonance spectra of non-Kramers bivalent iron (Fe 2+ ) ions have been detected in synthetic and natural beryl crystals with an iron impurity. The observed ESR spectra have been attributed to resonance transitions of Fe 2+ ions from the ground (singlet) state to excited (doublet) levels with the splitting Δ = 12.7 cm –1 between the levels. The experimental angular and frequency dependences of the resonance field of the ESR signal have been described by the spin Hamiltonian with the effective spin S = 1. The analysis of the ESR data and optical absorption spectra indicates that the Fe 2+ ions are situated in tetrahedral positions and substitute Be 2+ cations in the beryl structure

Submillimeter ESR spectra of Fe²⁺ ions in synthetic and natural beryl crystals

© 2017, Pleiades Publishing, Ltd. Electron spin resonance spectra of non-Kramers bivalent iron (Fe 2+ ) ions have been detected in synthetic and natural beryl crystals with an iron impurity. The observed ESR spectra have been attributed to resonance transitions of Fe 2+ ions from the ground (singlet) state to excited (doublet) levels with the splitting Δ = 12.7 cm –1 between the levels. The experimental angular and frequency dependences of the resonance field of the ESR signal have been described by the spin Hamiltonian with the effective spin S = 1. The analysis of the ESR data and optical absorption spectra indicates that the Fe 2+ ions are situated in tetrahedral positions and substitute Be 2+ cations in the beryl structure