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The three-dimensional angular distribution of electrons in two-photon ionization of atoms by an elliptically polarized laser beam, from an initial state with arbitrary angular momentum J i , is expressed in terms of six frequency-dependent invariant atomic parameters. The specific effect of the field polarization on the angular distribution (the elliptic dichroism, ED) is discussed for the general case of elliptic polarization. The necessary conditions for a non-zero ED are established and its physical origin is explained. The general theory is illustrated by a simple analytical calculation for the δ-potential model. Numerical calculations of the angular distribution parameters for H and Cs atoms are also performed and the dependence of ED magnitude on the atomic quantum numbers and the photon frequency is discussed for different frequencies.

The paper deals with methods of identification of the parameters of an induction motor model using genetic algorithms. It is supposed that the inverter supplying the motor is directly accessible for control of the conduction sequences of its power switches. This makes it possible to carry out a test consisting of a transient from standstill to steady-state operation at a given frequency and successive free motion to standstill. During this test, data are acquired referring to stator voltages, and currents and speed. Then, a genetic algorithm is employed with the aim of determining the mechanical and electrical parameters of the model, so as to reproduce the input-output behaviour of a real open-loop system. © IEE, 1998

BackgroundIn cardiac resynchronization therapy (CRT), quadripolar (QUAD) left ventricular (LV) leads are less prone to postoperative complications than non‐QUAD leads. Some studies have suggested better clinical outcomes.Methods and ResultsClinical events were assessed in 847 patients after CRT‐pacing or CRT‐defibrillation using either QUAD (n=287) or non‐QUAD (n=560), programmed to single‐site site LV pacing. Over a follow‐up period of 3.2 years (median [interquartile range, 1.90–5.0]), QUAD was associated with a lower total mortality (adjusted hazard ratio [aHR]: 0.32, 95% confidence interval [CI], 0.20–0.52), cardiac mortality (aHR: 0.36, 95% CI, 0.20–0.65), and heart failure (HF) hospitalization (aHR: 0.62, 95% CI, 0.39–0.99), after adjustment for age, sex, New York Heart Association class, HF etiology, device type (CRT‐pacing or CRT‐defibrillation), comorbidities, atrial rhythm, medication, left ventricular ejection fraction, and creatinine. Death from pump failure was lower with QUAD (aHR: 0.33; 95% CI, 0.18–0.62), but no group differences emerged with respect to sudden cardiac death. There were no differences in implant‐related complications. Re‐interventions for LV displacement or phrenic nerve stimulation, which were lower with QUAD, predicted total mortality (aHR: 1.68, 95% CI, 1.11–2.54), cardiac mortality (aHR: 2.61, 95% CI, 1.66–4.11) and HF hospitalization (aHR: 2.09, 95% CI, 1.22–3.58).Conclusions CRT using QUAD, programmed to biventricular pacing with single‐site LV pacing, is associated with a lower total mortality, cardiac mortality, and HF hospitalization. These trends were observed for both CRT‐defibrillation and CRT‐pacing, after adjustment for HF cause and other confounders. Re‐intervention for LV lead displacement or phrenic nerve stimulation was associated with worse outcomes.

A new generation of switching regulators inbedding an LC3 modulator (limit cycle conductance controller) is analysed and optimized from the point of view of dynamic performances. This is done by application of the current injected technique to the power stage model which is shown to behave like a first order system for low frequency perturbations. The optimization is carried out by specification of the desired closed loop modes of the system and calculation of the appropriate state variable feedback gains. The correctness of both the analytical model and optimisation procedure is verified by breadboard dynamic measurements.

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Success of quantum mechanical approximations for molecular geometries and electron-nuclear attraction expectation values: Gift of the Coulomb potential? J. Chem. Phys. 84, 4519 (1986); 10.1063/1.450024 Interpolated values of spectroscopic constants of asymmetric alkali molecules and molecular ions J. Chem. Phys. 62, 4753 (1975); 10.1063/1.430424Expectation values of the kinetic and potential energy of a diatomic molecule By using Hellman-type model potentials for alkali atoms, the many-electron problem of the alkali molecular ions is reduced to a three-body problem, and the ground state energy of the these ions calculated in the familiar Rayleigh-Ritz variational treatment. All the ions result as being stable. Other physical quantities (equilibrium and mean distances, etc.) are. also calculated. The reported data may be useful in a· variety of scattering problems, such as, for instance, alkali atom-ion collisions. They support the James' suggestion that the dissociation energies of the alkali molecular ions must be greater than those of the corresponding molecules, due to the greater diffuseness of the bonding wavefunctions. Application of the present approach to alkali hydride ions seems to indicate that these ions are not stable. The limitations of the pseudopotential approach for molecular calculations are discussed, and it is concluded that the approach is of simpler use for alkali molecular ions than for the corresponding molecules. Cs 3.88 1.6721. 0.3331. aReference 27. bReference 28.