A neuro-fuzzy approach as medical diagnostic interface

In contrast to the symbolic approach, neural networks seldom are designed to explain what they have learned. This is a major obstacle for its use in everyday life. With the appearance of neuro-fuzzy systems which use vague, human-like categories the situation has changed. Based on the well-known mechanisms of learning for RBF networks, a special neuro-fuzzy interface is proposed in this paper. It is especially useful in medical applications, using the notation and habits of physicians and other medically trained people. As an example, a liver disease diagnosis system is presented

Bistability and hysteresis of dipolar dynamos generated by turbulent convection in rotating spherical shells

Bistability and hysteresis of magnetohydrodynamic dipolar dynamos generated by turbulent convection in rotating spherical fluid shells is demonstrated. Hysteresis appears as a transition between two distinct regimes of dipolar dynamos with rather different properties including a pronounced difference in the amplitude of the axisymmetric poloidal field component and in the form of the differential rotation. The bistability occurs from the onset of dynamo action up to about 9 times the critical value of the Rayleigh number for onset of convection and over a wide range of values of the ordinary and the magnetic Prandtl numbers including the value unity

STUDIES ON PLANT BILE PIGMENTS.

The (4 Z, 10 2, 15Ej-2,3-dihydrobilindione 4, along with the fully unsaturated (E, 2, Z)-analogue 8, has been prepared from the corresponding (Z, Z, Z)-isomer by a variation of Falk's method (Falk et ul., 1980). The photochemical and acid-catalyzed back-reactions have been studied by UV-vis and 'H-NMR spectroscopy

Dynamo quenching due to shear flow

We provide a theory of dynamo (α effect) and momentum transport in three-dimensional magnetohydrodynamics. For the first time, we show that the α effect is reduced by the shear even in the absence of magnetic field. The α effect is further suppressed by magnetic fields well below equipartition (with the large-scale flow) with different scalings depending on the relative strength of shear and magnetic field. The turbulent viscosity is also found to be significantly reduced by shear and magnetic fields, with positive value. These results suggest a crucial effect of shear and magnetic field on dynamo quenching and momentum transport reduction, with important implications for laboratory and astrophysical plasmas, in particular, for the dynamics of the Sun

The alpha-effect in a turbulent liquid-metal plane Couette flow

We calculate the mean electromotive force in plane Couette flows of a nonrotating conducting fluid under the influence of a large-scale magnetic field for driven turbulence. A vertical stratification of the turbulence intensity results in an alpha effect owing to the presence of horizontal shear. Here we discuss the possibility of an experimental determination of the components of the alpha tensor using both quasilinear theory and nonlinear numerical simulations. For magnetic Prandtl numbers of the order of unity, we find that in the high-conductivity limit the alpha effect in the direction of the flow clearly exceeds the component in spanwise direction. In this limit, alpha runs linearly with the magnetic Reynolds number Rm while in the low-conductivity limit it runs with the product Rm*Re, where Re is the kinetic Reynolds number so that for given Rm the alpha effect grows with decreasing magnetic Prandtl number. For the small magnetic Prandtl numbers of liquid metals, a common value for the horizontal elements of the alpha tensor appears, which makes it unimportant whether the alpha effect is measured in the spanwise or streamwise directions. The resulting effect should lead to an observable voltage in both directions of about 0.5 mV for magnetic fields of 1 kgauss and velocity fluctuations of about 1 m/s in a channel of 50 cm height (independent of its width).Comment: 9 pages, 6 figures, PRE, in pres

A de Finetti Representation Theorem for Quantum Process Tomography

In quantum process tomography, it is possible to express the experimenter's prior information as a sequence of quantum operations, i.e., trace-preserving completely positive maps. In analogy to de Finetti's concept of exchangeability for probability distributions, we give a definition of exchangeability for sequences of quantum operations. We then state and prove a representation theorem for such exchangeable sequences. The theorem leads to a simple characterization of admissible priors for quantum process tomography and solves to a Bayesian's satisfaction the problem of an unknown quantum operation.Comment: 10 page

Angular momentum conservation and torsional oscillations in the Sun and solar-like stars

The solar torsional oscillations, i.e., the perturbations of the angular velocity of rotation associated with the eleven-year activity cycle, are a manifestation of the interaction among the interior magnetic fields, amplified and modulated by the solar dynamo, and rotation, meridional flow and turbulent thermal transport. Therefore, they can be used, at least in principle, to put constraints on that interaction. Similar phenomena are expected to be observed in solar-like stars and can be modelled to shed light on analogous interactions in different environments. The source of the torsional oscillations is investigated by means of a model for the angular momentum transport within the convection zone. A description of the torsional oscillations is introduced, based on an analytical solution of the angular momentum equation in the mean-field approach. It provides information on the intensity and location of the torques producing the redistribution of the angular momentum within the convection zone of the Sun along the activity cycle. The method can be extended to solar-like stars for which some information on the time-dependence of the differential rotation is becoming available. Illustrative applications to the Sun and solar-like stars are presented. Under the hypothesis that the solar torsional oscillations are due to the mean-field Lorentz force, the mean amplitude of the Maxwell stresses and the phase relationship between poloidal and toroidal field components are obtained. Our preliminary results show the capability of the proposed approach to constrain the amplitude, phase and location of the perturbations leading to the observed torsional oscillations.Comment: 13 pages, 12 figures, accepted by Astronomy & Astrophysic