A method for the determination of the dissociation constants of acids with an uncalibrated glass electrode

A method is presented for the determination of absolute pKa values of acids in solvents with a high dielectric constant by potentiometry with an uncalibrated glass electrode; in the determination, the glass electrode becomes calibrated. The method has the advantage that it is rapid and simple. Moreover, the range of pKa values that can be determined by this method is about 3 pK units greater than for the direct conductivity method

On the unsteady behavior of turbulence models

Periodically forced turbulence is used as a test case to evaluate the predictions of two-equation and multiple-scale turbulence models in unsteady flows. The limitations of the two-equation model are shown to originate in the basic assumption of spectral equilibrium. A multiple-scale model based on a picture of stepwise energy cascade overcomes some of these limitations, but the absence of nonlocal interactions proves to lead to poor predictions of the time variation of the dissipation rate. A new multiple-scale model that includes nonlocal interactions is proposed and shown to reproduce the main features of the frequency response correctly

The effects of disruptive and stabilizing selection on body size in Drosophila melanogaster. III. Genetic analysis of two lines with different reactions to disruptive selection with mating of opposite extremes

A genetic analysis was made of two lines which when subjected to disruptive selection with compulsary mating of opposite extremes (D−) showed a different response viz. one, D−-1, showing predominantly an increase of environmental variance and possibly interaction variance, the other, D−-2, showing an increase of genetic variance. Crosses between extreme flies within lines revealed that D−-1 genomes from large flies are dominant to genomes from small individuals. In D−-2 the genetic variation is predominantly additive variance. Tests for dominant chromosome effect in crosses with an inbred stock with recessive markers showed clear third chromosome differences in D−-2 and not in D−-1. Chromosome exchange between extreme flies corroborated the importance of genetic differences in D−-2. A factor or complex of factors with large effect decreasing body size is located on third chromosomes from small flies in D−-2. Interaction between chromosomes has a similar magnitude in the two lines. Crowding and temperature experiments did not reveal an increased general sensitivity to environmental factors in D−-1, which was suggested by the enlarged environmental variance of this line

The behaviour of a single catalyst pellet for the selective hydrogenation of ethyne in ethene

The steady-state and dynamic behaviour of a single Pd---Al2O3 catalyst particle is studied for the selective hydrogenation of ethyne in the presence of ethene, without addition of carbon monoxide. The particle-to-gas heat transfer in the reactor is characterized. During selective hydrogenation, not only the ignition and the extinction phenomena but also oscillatory behaviour is observed. The nature of the single and multipeak oscillations is discussed. With a dynamic model, based on relatively simple kinetic equations and an additional slow mechanism, e.g. the formation of ethylidyne on the catalyst surface, the qualitative features of this system can be described

Off-Shell Electromagnetic Form Fators of the Nucleon in Chiral Perturbation Theory

We study the electromagnetic form factors of a nucleon in next-to-leading order chiral perturbation theory (CPT) in the case where one of the nucleons is off its mass shell. We calculate the leading nonanalytic contributions to relevant measures for the off-shell dependence in the limited kinematical range allowed.Comment: 3 pages LaTeX with worldsci.sty (available by mailing [email protected] and typing "get worldsci.sty" in the subject line), invited talk given at the International Symposium on Medium Energy Physics, Beijing, August 199

Is there a single frontier in a single European banking market?

This paper attempts to estimate comparable efficiency scores for European banks operating in the Single Market in the EU. Using a data set of more than 5000 large commercial banks from all major European banking markets over the period 1993-2004, the application of meta-frontiers enables us to assess the existence of a single and integrated European banking market. We find evidence in favor of a single European banking market characterized by cost and profit meta-frontiers. However, compared to the meta-frontier estimations, pooled frontier estimations tend to underestimate efficiency levels and correlate poorly with country-specific frontier efficiency ranks. JEL Classification: G21, L11, L22, L23banking, meta-frontiers, stochastic frontiers, technology gap ratios, X-efficiency

Comparing energy use and greenhouse gas emissions in organic and conventional farming systems in the Netherlands

Results are presented of a model study comparing energy use and greenhouse gas emissions in organic and conventional farming systems in the Netherlands. Calculations have been performed for model farms, designed on the basis of current organic and conventional farming practices. Energy use and greenhouse gas emissions per hectare on organic farms are lower than on conventional farms, particularly in dairy farming. Energy use and greenhouse gas emissions per Mg of milk in organic dairy farming is about 80 and 90%, respectively of that in conventional dairy farming. Energy use and greenhouse gas emission per Mg product in organic crop production is 5-40 and 7-17%, respectively higher than in conventional systems. The wide ranges found in crop production reflect large differences among individual crops

Persistence of the valence bond glass state in the double perovskites Ba2-xSrxYMoO6

Peer reviewedPublisher PD

Origin of Lagrangian Intermittency in Drift-Wave Turbulence

The Lagrangian velocity statistics of dissipative drift-wave turbulence are investigated. For large values of the adiabaticity (or small collisionality), the probability density function of the Lagrangian acceleration shows exponential tails, as opposed to the stretched exponential or algebraic tails, generally observed for the highly intermittent acceleration of Navier-Stokes turbulence. This exponential distribution is shown to be a robust feature independent of the Reynolds number. For small adiabaticity, algebraic tails are observed, suggesting the strong influence of point-vortex-like dynamics on the acceleration. A causal connection is found between the shape of the probability density function and the autocorrelation of the norm of the acceleration