Volume 38, Issue 11

We study a new parameter - the "Non-Uniformity Factor" (NUF) -, which we have introduced in [1]. by way of estimating and comparing the deviation from average behavior (expressed by such factors as the Lyapunov characteristic exponent(s) and the information dimension) in various strange attractors (discrete and chaotic flows). Our results show for certain values of the control parameters the inadequacy of the above averaging properties in representing what is actually going on - especially when the strange attractors are employed as dynamical models for information processing and pattern recognition. In such applications (like for example visual pattern perception or communication via a burst-error channel) the high degree of adherence of the processor to a rather small subset of crucial features of the pattern under investigation or the flow, has been documented experimentally: Hence the weakness of concepts such as the entropy in giving in such cases a quantitative measure of the information transaction between the pattern and the processor. We finally investigate the influence of external noise in modifying the NUF

Two more classes of monotonic double layers complementing the class of beam-type double layers are investigated analytically, and their range of existence is explored in the small amplitude limit. One class preferentially exists for hot ions and electron drifts of the order of electron thermal velocity. The second one, instead, assumes hot electrons and needs almost current-free conditions. The first class, called SEADL, is based on the slow electron acoustic branch and exhibits a tuning-fork configuration in the electron phase space. Its density decreases with increasing potential. The second one (SIADL) rests on the slow ion acoustic branch and. consequently, has a tuning-fork pattern in the ion phase space. Its density increases with the potential. Both classes are found to be linearly stable with respect to one-dimensional, but unstable with respect to two-dimensional electrostatic perturbations. A comparison with experiments suggests an identification of the second type with the double layers obtained by Hollenstein

In unified field models all observable (elementary and nonelementary) particles are assumed to be bound states of elementary unobservable fermion fields. Such models are formulated by selfregularizing higher order nonlinear spinor field equations with indefinite metric. The latter needs a careful investigation of the corresponding state space, in particular with respect to bound states. Based on preceding papers the general analysis of the state space is further developed in the framework of a relativistic energy representation in Part I. In Part II this formalism is applied to bound states of the two-fermion sector for a simple model. By direct calculation it turns out that for very heavy masses of the constituent fields bound states with positive norm and small masses are possible, i.e., that the two-fermion sector allows a meaningful physical interpretation

A recent theory by Molvig et al. on particle transport in turbulent fields with overlapping island structure is critically reviewed. An inconsistency in the derivation of the diffusion coefficient D from the assumption of a Wiener process is pointed out and corrected. In the region ΔΩ • τ K ≪ 1 the results if properly interpreted are unchanged. For ΔΩ • τ K ≪ 1 the results differ (ΔΩ = particle velocity/mode correlation length, τ K = "randomization" time). Computer experiments are performed to support the critical arguments

Absorption and fluorescence spectra, fluorescence quantum yield and decay time have been measured for eight new 10-phenyl-9-acetoxyanthracene derivatives. It is found that the strength of the absorption transition is independent of the phenyl and anthracene substitution, whereas the strength of the fluorescence transition depends more on the functional groups substituted in the anthracene ring then in the phenyl ring. The loss of mirror symmetry between the absorption and emission spectra and the large values of the Stokes shift suggest that, due to perturbation of the functional groups, the molecular geometries of the S 0 and S * 1 states are different. The investigated compounds show laser action. The relative value of the absorption threshold power, the gain spectra and the lasing region have been determined. It is found that the amplified spontaneous emission and gain spectra depend on the interaction of the substituted phenyl ring with the π-electrons of the anthracene ring

The total structure factors as well as the total pair correlation functions of amorphous Mg 84 Ni 16 and Mg 30 Ca 70 were determined by X-ray diffraction. The Mg-Ni glass shows rather strong chemical short range ordering. By Gaussian fit of the total pair correlation function partial coordination numbers and atomic distances were obtained. Similar surrounding of the Ni atoms in the amorphous phase and in crystalline Mg 2 Ni was found. The structural features of the Mg-Ca glass differ from those of the Mg-Ni glass

The structure of amorphous Cu 57 Zr 43 has been investigated by neutron diffraction using the isotopic substitution method with the isotopes 63 Cu and 65 Cu besides natural Cu. From the scattering contribution of concentration fluctuations to the measured structure factors and from the atomic distances chemical ordering is concluded to exist in amorphous Cu 57 Zr 43 . The structural results are compared with previous experimental and theoretical investigations of Cu- Zr- and other binary metallic glasses formed by transition metals. Evidence is given that the topological as well as the chemical short range order is asymmetric in respect to both components in this type of metallic glasses

The cluster model, developed for the ESR-absorption of a pure antiferromagnetic compound, has been modified to take into account the magnetic dilution. As bonding in a cluster is sensitive to its local geometry, the consideration is confined to the specific structure of α-Cr 2 O 3 . In this case, the incorporation of diamagnetic Ga 3+ ions sets up eight local configurations with different coupling energies and distinct probabilities. It is assumed that the ESR-absorption of a doped crystal can be explained by the absorption within these configurations. The theory is able to predict the dependence on temperature and concentration for the ESR-intensity of gallium-doped Cr 2 O 3 with an accuracy of about 3%. Numeral results of this fit are the magnetic coupling energies K 1 = 183 cm -1 between nearest Cr 3+ neighbours and K 2 = 82.3 cm -1 between next-nearest Cr 3+ neighbours

The microwave spectrum of 2-chloropropene was reinvestigated using microwave Fourier transform spectroscopy. For the two isotopic species CH 3 C 35 Cl=CH 2 and CH 3 C 37 Cl=CH 2 the chlorine quadrupole coupling was determined with higher accuracy. The barrier to internal rotation was determined from the ground state. For comparison the first excited torsional state of CH 3 C 35 Cl=CH 2 was remeasured and reanalysed

The rotational spectrum of 3-bromothiophene was investigated in the frequency range between 8 and 18 GHz by use of a microwave Fourier transform spectrometer. Both a- and b-type spectra were assigned for the vibronic ground state. Rotational constants, quartic centrifugal distortion constants and quadrupole coupling constants were obtained for the 79 Br- and 81 Br-isotopic species. For the analysis, the effective rotational Hamiltonian including centrifugal distortion in the form of Van Eijck's symmetric top reduction and bromine quadrupole coupling was set up in the coupled basis of the limiting symmetric top, J, K, I, F, M F >, and was diagonalized numerically. Spin rotation interaction was neglected

A harmonic field for cubane is developed by means of the following experimental data from literature: vibrational frequencies for C 8 H 8 , sym-C 8 H 6 D 2 , sym-C 8 H 2 D 6 and C 8 D 8 , in addition to three Coriolis constants of C 8 H 8 . As a part of this analysis a new iteration method was developed for simultaneous fitting of vibrational frequencies and first-order Coriolis constants of a threedimensional symmetry block. The force constants were used to calculate the vibrational frequencies of all the twenty existing partially deuterated cubanes, in addition to the unsubstituted (C 8 H 8 ) and perdeuterated (C 8 D 8 ) molecules. Also the first-order Coriolis constants, mean amplitudes of vibration and perpendicular amplitude correction coefficients for selected cubane molecules are reported

Magnetic circular dichroism (MCD) spectra of some thiadiazoles have revealed the characteristic π → π* transitions in cata-condensed thiadiazoles. Within the framework of the PPP method quantum mechanical calculations have been carried out in order to give a reasonable explanation for the MCD spectra, resulting in a fairly good agreement between the experimental and theoretical Faraday parameters

Two new molecular emissions have been observed at 400 nm and 250 nm in bismuth vapour after visible and infrared multiphoton absorption. A new state of even parity, labelled W and lying at more than 37600 cm -1 from the ground state, has been evidenced. Known atomic lines are also excited via dissociation of repulsive states