Influence of the state of the electron gas on dispersion curves of ionization waves in neon

On the example of neon the onset of a transition is described from a non-hydrodynamic state of the electron gas, which exists at low pressures and currents, to a state where a local hydrodynamics is applicable. In the non-hydrodynamic state the ionization waves are influenced by resonant properties of the electron gas which means that several varieties can be selected on each of the two dispersion curves. With growing current the two parts of dispersion curve of the fast varieties (r and s) merge and this is interpreted as disappearance of the spatial resonance of the electron gas due to an enhancement of the electron Coulomb collisions.The author expresses his gratitude to K.Rohlena and L.Pekárek for helpful discussions.     

Photocounting statistics of radiation propagating through passive and active random media

The photocounting statistics of radiation propagating through active, quadratic random media and through passive media are considered on the basis of a recently developed quantum dynamic theory. We show that the counting statistics for lossless random active media and those for passive weakly-inhomogeneous random media are similar, although there are some differences. The peak of the photocounting distribution shifts to lower count numbern and is found to broaden with increasing turbulence level, as in the case of passive media. In lossy active media, the shift of the peak to lowern is more pronounced, in pumped active media below threshold it is less so, and in pumped active media above threshold, there is a shift of the peak to highern as a consequence of self-radiation. Severe broadening occurs in this latter case. Photocounting statistics for special states of the incident field are also discussed.     

Elektrophorese der halogenokomplexe von hg(ii), bi(iii), cd(ii), pb(ii) und cu(ii) : Chloro-, bromo- und jodokomplexe in kcl,hcl,kbr,hbr und kj

The electrophoretic mobilities of chloro-, bromo- and iodo-complexes of Hg, Bi, Cd, Pb, and Cu, obtained by heavy current electrophoresis on filter paper, are presented in diagrams as a function of the logarithm of the concentrations of the halogen ions KC1, HCl, KUr, HBr and KJ, mainly in concentrations between 0.1N and 4N, were selected as complexing agents Straight lines were obtuned with characteristic slopes, breaks and parallelisms. Furthermore it can be seen from the diagiarns, that the tendency to form complexes increases on the one hand in the sequence chloro - bromo -iodo, and on the other for the chloro- and bromo-complexes in the sequence Cu - Pb - Cd - Bi -Hg In the case of the lodo-complexes the sequence is (Pb + Cd) - Hg - Cu.Figures that show the electrophoretie scpartion of a mixture of Hg - Bi - Cd - Pb - Cu in Voirious concentrations of KC1, KBr and HBr, are given. The separation of these metals in the form of halogeno-complexes can be most satisfactorily accomplished in 0.5_N KBr or 0.5NHBr.     

Status of uncertainty assessment in k 0-NAA measurement: anything still missing?

Several approaches to quantifying measurement uncertainty in k ₀-based neutron activation analysis (k ₀-NAA) are reviewed, comprising the original approach, the spreadsheet approach, the dedicated computer program involving analytical calculations and the two k ₀-NAA programs available on the market. Two imperfectness in the dedicated programs are identified, their impact assessed and possible improvements presented for a concrete experimental situation. The status of uncertainty assessment in k ₀-NAA is discussed and steps for improvement are recommended. It is concluded that the present magnitude of measurement uncertainty should further be improved by making additional efforts in reducing uncertainties of the relevant nuclear constants used.     

Crystal structure and computational studies of (E)-1-(benzo[b]thiophen-3-yl)-N-(4-ethoxyphenyl)methanimine

Crystallography Reports - The title compound, C17H15NOS, crystallizes in the orthorhombic sp. gr. Pca21. Two molecules in the asymmetric unit have similar structure. Crystal structure contains weak...     

Enhancing energy harvesting by coupling monostable oscillators

The performance of a ring of linearly coupled, monostable nonlinear oscillators is optimized towards its goal of acting as energy harvester – through piezoelectric transduction – of mesoscopic fluctuations, which are modeled as Ornstein-Uhlenbeck noises. For a single oscillator, the maximum output voltage and overall efficiency are attained for a soft piecewise-linear potential (providing a weak attractive constant force) but they are still fairly large for a harmonic potential. When several harmonic springs are linearly and bidirectionally coupled to form a ring, it is found that counter-phase coupling can largely improve the performance while in-phase coupling worsens it. Moreover, it turns out that few (two or three) coupled units perform better than more.     

Decoupling of supersymmetric particles

The possibility of a heavy supersymmetric spectrum at the Minimal Supersymmetric Standard Model is considered and the decoupling from the low energy electroweak scale is analyzed in detail. The formal proof of decoupling of supersymmetric particles from low energy physics is stated in terms of the effective action for the particles of the Standard Model that results by integrating out all the sparticles in the limit where their masses are larger than the electroweak scale. The computation of the effective action for the standard electroweak gauge bosons , Z and is performed by integrating out all the squarks, sleptons, charginos and neutralinos to one-loop. The Higgs sector is not considered in this paper. The large sparticle masses limit is also analyzed in detail. Explicit analytical formulae for the two-point functions of the electroweak gauge bosons to be valid in that limit are presented. Finally, the decoupling of sparticles in the S, T and U parameters is studied analitically. A discussion on how the decoupling takes place in terms of both the physical sparticle masses and the non-physical mass parameters as the -parameter and the soft-breaking parameters is included. Received: 27 March 1998 / Published online: 5 October 1998     

Diffraction of three-dimensional beams in uniaxial media

Within here we make an analysis of two and three-dimensional beams synthesized by extraordinary waves that propagate in uniaxial media. A relation between the geometric place of the first interference maxima and the energy flow direction is established. In addition, we determine that three-dimensional extraordinary symmetrical beams can be obtained from two two-dimensional ones that are not to be necessarily orthogonal.