Einen Analysengang zur Identifizierung von Giften in verd?chtigen Lebensmitteln

Ohne Zusammenfassung     

Steroide

Ohne Zusammenfassung     

Critical dynamics and multifractal exponents at the Anderson transition in 3d disordered systems

We investigate the dynamics of electrons in the vicinity of the Anderson transition in d = 3 dimensions. Using the exact eigenstates from a numerical diagonalization, a number of quantities related to the critical behavior of the diffusion function are obtained. The relation η = d ? D₂ between the correlation dimension D₂ of the multifractal eigenstates and the exponent η which enters into correlation functions is verified. Numerically, we have η ≈? 1.3. Implications of critical dynamics for experiments are predicted. We investigate the long-time behavior of the motion of a wave packet. Furthermore, electron-electron and electron-phonon scattering rates are calculated. For the latter, we predict a change of the temperature dependence for low T due to η. The electron-electron scattering rate is found to be linear in T and depends on the dimensionless conductance at the critical point.     

Generalized Markovian decision processes

Summary A general discrete decision process is formulated which includes both undiscounted and discounted semi-Markovian decision processes as special cases. A policy-iteration algorithm is presented and shown to converge to an optimal policy. Properties of the coupled functional equations are derived. Primal and dual linear programming formulations of the optimization problem are also given. An application is given to Markov ratio decision process.

---

Zusammenfassung Es wird ein allgemeiner diskreter Entscheidungsprozeß betrachtet, welcher sowohl die undiskontierten und diskontierten Semi-Markoffschen Entscheidungsprozesse als Spezialfälle enthält. Ein auf der Politik-Iteration basierendes Verfahren wird vorgestellt und die Konvergenz gegen eine optimale Politik wird bewiesen. Wir zeigen einige Eigenschaften des Paares gekoppelter Funktionalgleichungen, die in diesem Modell auftreten. Zum Schluß werden noch die Formulierungen dieses Entscheidungsmodelles als primales und duales lineares Optimierungsproblem angegeben.

     

Jod

Ohne Zusammenfassung     

Stickstoff

Ohne Zusammenfassung     

Studies on the solvent extraction of some cadmium chelates

Eighteen different chelating agents have been investigated as possible extractants for radiolabelled 10^-5.1M cadmium from aqueous solutions into chloroform. The experimentally-determined extraction data have been analyzed theoretically by measurement of metal chelate and chelating agent association constants and distribution constants.     

Knight shift tensors and π-spin densities in the organic metals αt-(BEDT-TTF)2I3 and (BEDT-TTF)2Cu(NCS)2

¹³C-MASS spectra of pure BEDT-TTF and of the organic metals α_t-(BEDT-TTF)₂I₃ and (BEDT-TTF)₂Cu(NCS)₂ were recorded atν _L = 68 MHz. Isotropic shifts and the principal components of the shift tensors were determined, respectively, from the center and spinning side bands. For pure BEDT-TTF which is a diamagnetic insolator, the measured shifts arechemical shifts while for the organic metals they are the sum of chemical and Knight shifts. In each of the compounds the shifts are assigned ingroups to theinner, middle andouter carbons of the BEDT-TTF molecule. For the organic metals the separation of the experimental shifts into chemical and Knight shifts is discussed. From the anisotropic part of the Knight shift tensors the π-spin densities at the carbon and sulphur positions of the BEDT-TTF molecule are inferred. The result is that the π-spin density of the unpaired hole is concentrated on the center part of the BEDT-TTF molecule, i.e., on the inner and middle carbons, and on the inner sulphurs. It is argued that the current density is concentrated on this part of the BEDT-TTF molecule as well.