Approximate Treatment of Lepton Distortion in Charged-Current Neutrino Scattering from Nuclei

The partial-wave expansion used to treat the distortion of scattered electrons by the nuclear Coulomb field is simpler and considerably less time-consuming when applied to the production of muons and electrons by low and intermediate-energy neutrinos. For angle-integrated cross sections, however, a modification of the "effective-momentum-transfer" approximation seems to work so well that for muons the full distorted-wave treatment is usually unnecessary, even at kinetic energies as low as an MeV and in nuclei as heavy as lead. The method does not work as well for electron production at low energies, but there a Fermi function usually proves adequate. Scattering of electron-neutrinos from muon decay on iodine and of atmospheric neutrinos on iron are discussed in light of these results.Comment: 11 pages, LaTeX, submitted to Phys. Rev.

RAW Quantum transition state theory

Contents 1 -- Introduction 409 2 -- Feynman path integrals 410 3 -- How should a quantum transition state be defined? 410 4 -- The action surface and the minimum action path 411 5 -- The conical dividing surface of RAW-QTST 416 6 -- The prefactor for RAW-QTST 418 7 -- Application of RAW-QTST to a test problem RAW QUANTUM TRANSITION STATE THEORY 409 1. -- Introduction Many important problems in chemistry and condensed matter physics involve the characterization of the rate of a transition of atoms and/or electrons. Most transitions observable in the laboratory are `rare events' in the sense that the transition rate is many orders of magnitude smaller than the rate associated with molecular vibrations. A direct simulation of the atomic scale dynamics is not useful for studying such transitions because the simulated time interval is far too short to include even a single transition. Transition state theory (TST) is well established and widely used for c

Structure and Dynamics of the hydration shells of the Zn²+ ion from ab initio molecular dynamics and combined ab initio and classical molecular dynamics simulations

info:eu-repo/semantics/publishe

Ribozymes: Analytical Solution of the One-substrate, Two-intermediate Reversible Scheme for Enzyme Reactions

The paper presents a kinetic analysis of a reversible enzymatic reaction S⇄P involving two intermediate compounds under the condition [E]0 ≫ [S]0 + [P]0. For the case of mono-exponential behavior, we derive an equation for kobs as a function of [E]0, which emphasizes the pitfalls of oversimplifying kinetic schemes (such as the Michaelis-Menten model) for ribozyme studies. This novel apparent rate constant, which has been arrived at through mechanistic considerations, is analyzed, and the characteristic parameters obtained. The equation, which seems to fit experimental data better than conventional approximations, is used to analyze a single turnover study on an ADC1 ribozyme drawn from hepatitis delta virus RNA. The microscopic kinetic constants for such enzyme are evaluated and its mono-exponential behavior verified