Comments on the potentiometric titration of halides including fluoride with a mixed titrant

An attempt was made to verify work reported by others on the potentiometric titration of halides including fluoride with a mixed titrant of silver nitrate and thorium nitrate. The platinum indicator electrode can indeed be used to monitor the titration of bromide and chloride. However, we could not verify the results reported for fluoride. There seems to be no theoretical basis on which to expect the platinum electrode to respond to changes in fluoride ion concentration.     

Numerically stable methods for quadratic programming

Numerically stable algorithms for quadratic programming are discussed. A new algorithm is described for indefinite quadratic programming which utilizes methods for updating positivedefinite factorizations only. Consequently all the updating procedures required are common to algorithms for linearly-constrained optimization. The new algorithm can be used for the positive-definite case without loss of efficiency.     

Gas chromatographic and mass spectrometric investigation of the trimethylsilylethers of vitamin A and some of its isomers

Vitamin A and some of its isomers are separated and quantitatively determined as trimethylsilylethers by gas liquid chromatography. The identity of the different fractions is proved by mass spectrometry.     

“Phonon ineffectiveness” and the influence of Coulomb interactions on the phonon controlled conductivity in high resistivity metals

The theory of electronic transport for high resistivity metals developed recently by Belitz and Schirmacher which provides an explanation for the Mooij resistivity anomalies observed in such materials is extended to include the electron-electron Coulomb interaction explicitly. This makes it possible to quantify previous speculations about “phonon ineffectiveness” in disordered metals. It is shown that the weakening of the electron phonon coupling applies only to current relaxation (scattering) but not to density relaxation (phonon-induced tunnelling) processes. It is argued that the presence of density relaxation and not that of the Coulomb induced “phonon ineffectiveness” is the main reason for the occurrence of the Mooij anomalies in high resistivity metals.     

Die Annäherung guter Strategien bei einer gewissen Klasse von Spielen

Ohne Zusammenfassung     

Über die Normaltorsion von Flächen im vierdimensionalen euklidischen Raum

Ohne Zusammenfassung     

Über Jackson- und Bernstein-Type Ungleichungen für lineare Approximationsverfahren in Lp(En)

Ohne Zusammenfassung     

The computation of Lagrange-multiplier estimates for constrained minimization

Almost all efficient algorithms for constrained optimization require the repeated computation of Lagrange-multiplier estimates. In this paper we consider the difficulties in providing accurate estimates and what tests can be made in order to check the validity of the estimates obtained. A variety of formulae for the estimation of Lagrange multipliers are derived and their respective merits discussed. Finally the role of Lagrange multipliers within optimization algorithms is discussed and in addition to other results, it is shown that some algorithms are particularly sensitive to errors in the estimates.