Discontinuities in the Electromagnetic Fields of Vortex Beams in the Complex Source/Sink Model

An analytical discontinuity is reported in what was thought to be the discontinuity-free exact nonparaxial vortex beam phasor obtained within the complex source/sink model. This discontinuity appears for all odd values of the orbital angular momentum mode. Such discontinuities in the phasor lead to nonphysical discontinuities in the real electromagnetic field components. We identify the source of the discontinuities, and provide graphical evidence of the discontinuous real electric fields for the first and third orbital angular momentum modes. A simple means of avoiding these discontinuities is presented.Comment: 10 pages, 4 figure

Photoionization of Atoms

This chapter outlines the theory of atomic photoionization, and the dynamics of the photon-atom collision process. Those kinds of electron correlation that are most important in photoionization are emphasized, although many qualitative features can be understood within a central field model. The particle-hole type of electron correlations are discussed, as they are by far the most important for describing the single photoionization of atoms near ionization thresholds. Detailed reviews of atomic photoionization are presented in Refs. [I] and 121. Current activities and interests are well-described in two recent books [3,4

Book Review: \u3ci\u3eThe Theory of Atomic Structure and Spectra\u3c/i\u3e by Robert D. Cowan

The field of atomic spectroscopy is currently experiencing a resurgence of interest owing on the one hand to its applications in astrophysics, plasma physics, and other fields and on the other hand to the development of new experimental tools to probe atomic structures. One example of the latter is the use of tunable lasers to study highly excited atoms in the presence of strong external electric and magnetic fields. Another is the use of synchrotron radiation to probe with increasing detail the inner shell structure of rare earth, actinide, and other heavy atoms

Length and Velocity Formulas in Approximate Oscillator-Strength Calculations

The matrix element for electric dipole transitions is correctly given by the length formula in the Hartree-Fock, configuration-interaction, and related approximations, which involve the diagonalization of an approximate, but nonlocal, Hamiltonian

Book Review: \u3ci\u3eThe Theory of Atomic Structure and Spectra\u3c/i\u3e by Robert D. Cowan

The field of atomic spectroscopy is currently experiencing a resurgence of interest owing on the one hand to its applications in astrophysics, plasma physics, and other fields and on the other hand to the development of new experimental tools to probe atomic structures. One example of the latter is the use of tunable lasers to study highly excited atoms in the presence of strong external electric and magnetic fields. Another is the use of synchrotron radiation to probe with increasing detail the inner shell structure of rare earth, actinide, and other heavy atoms

Card Test as a Simple Method to Diagnose Short Anagen Syndrome

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Photoionization of Atoms

This chapter outlines the theory of atomic photoionization, and the dynamics of the photon-atom collision process. Those kinds of electron correlation that are most important in photoionization are emphasized, although many qualitative features can be understood within a central field model. The particle-hole type of electron correlations are discussed, as they are by far the most important for describing the single photoionization of atoms near ionization thresholds. Detailed reviews of atomic photoionization are presented in Refs. [I] and 121. Current activities and interests are well-described in two recent books [3,4

Parametrizations and dynamical analysis of angle-integrated cross sections for double photoionization including nondipole effects

Similarly to differential cross sections for one-electron photoionization, the doubly differential cross section for double photoionization (DPI) may be conveniently described by four parameters: the singly differential (with respect to energy sharing) cross section (σ0), the dipole asymmetry parameter (β), and two nondipole asymmetry parameters (Y and δ). Here we derive two model-independent representations for these parameters for DPI from a S01 atomic bound state: (i) in terms of one-dimensional integrals of the polarization-invariant DPI amplitudes and (ii) in terms of the exact two-electron reduced matrix elements. For DPI of He at excess energies, Eexc, of 100 eV, 450 eV, and 1 keV, we present numerical results for the asymmetry parameters within the framework of the convergent close-coupling theory and compare them with results of lowest-order (in the interelectron interaction) perturbation theory (LOPT). The results for Eexc=1keV exhibit a nondipole asymmetry that is large enough to be easily measured experimentally. We find excellent agreement between our LOPT results and other theoretical predictions and experimental data for total cross sections and ratios of double to single ionization cross sections for K-shell DPI from several multielectron atoms

Activation of Jun N-terminal Kinase/Stress-activated Protein Kinase Pathway by Tumor Necrosis Factor α Leads to Intercellular Adhesion Molecule-1 Expression

Tumor necrosis factor alpha (TNF-alpha) is a cytokine implicated in the pathogenesis of numerous chronic and acute inflammatory conditions. We have previously shown that mouse Sertoli cells respond to TNF-alpha by increasing interleukin-6 production and intercellular adhesion molecule-1 (ICAM-1) expression (1). In this cell type TNF-alpha activates the mitogen-activated protein kinase (MAPK) pathways p42/p44 MAPK, JNK/SAPK, and p38, the last of which is responsible for interleukin-6 production (1). To determine which MAPK signaling pathway is required for TNF-alpha induction of ICAM-1 expression, we have utilized the protein kinase inhibitor dimethylaminopurine, demonstrating that treatment of Sertoli cells with such compound significantly reduced ICAM-1 expression and JNK/SAPK activation. Moreover, dimethylaminopurine treatment increased the expression of MAPK phosphatase-2, providing a possible mechanism of action of this compound. By using agonist antibodies to p55 and to p75 TNF-alpha receptors and both human and mouse TNF-alpha, we demonstrate that both TNF receptors are expressed and that only the p55 receptor is involved in ICAM-1 expression. The p55 receptor activates all of the three pathways, whereas p75 failed to activate any of the MAPKs. Altogether our results demonstrate that TNF-alpha up-regulates ICAM-1 expression through the activation of the JNK/SAPK transduction pathway mediated by the p55 receptor