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P Rietveld

Publications and source records attributed to P Rietveld.

5 recordsLinked to original sources
PubMed2000

Economic evaluation of traffic safety measures for transport companies.

This paper addresses the economic feasibility of measures to reduce the material damage of transport companies. Results are presented of a series of interviews among transport companies as well as from a postal questionnaire survey. Next, calculations are presented for three types of companies: a small family company, a large family company and a large formalised company. From the viewpoint of costs and benefits, damage prevention measures appear to be particularly interesting to larger companies. Small companies, being the largest group, tend to have an informal culture in which measures are less effective. Especially those measures for which no large investments are needed, which influence the behaviour of drivers and need not to be contracted out, are perceived as attractive by the transport companies.

Accidents, Occupational↗
PubMed1994

Reductive and oxidative half-reactions of glutathione reductase from Escherichia coli.

Glutathione reductase catalyzes the reduction of glutathione disulfide by NADPH and has a redox active disulfide and an FAD cofactor in each monomer. In the reductive half-reaction, FAD is reduced by NADPH and electrons pass from the reduced flavin to the redox active disulfide. The oxidative half-reaction is dithiol-disulfide interchange between the enzyme dithiol and glutathione disulfide. We have investigated the reductive and oxidative half-reactions using wild-type glutathione reductase from Escherichia coli and in an altered form of the enzyme in which the active site acid-base catalyst, His439, has been changed to an alanine residue (H439A). H439A has 0.3% activity in the NADPH/GSSG assay. The replacement affects both the oxidative half-reaction, as expected, and the reductive half-reaction--specifically, the passage of electrons from reduced flavin to the disulfide. Reduction of H439A by NADPH allows direct observation of flavin reduction. The NADPH-FAD charge transfer complex is formed in the dead time. Reduction of FAD, at a limiting rate of 250 s-1, is observed as a decrease at 460 nm and an increase at 670 nm (FADH(-)-NADP+ charge transfer). Subsequent passage of electrons from FADH- to the disulfide (increase at 460 nm and a decrease at 670 nm) is very slow (6-7 s-1) and concentration independent in H439A. The monophasic oxidative half-reaction is very slow, as expected for reduced H439A.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1989

Intraregional income distribution and poverty: some investigations for the Netherlands, 1960-81.

"This paper is addressed to intraregional income inequalities in the Netherlands. Various concepts are used to measure the degree of regional poverty. In addition, dissimilarity between intraregional income distributions is studied. At the provincial level, relatively small and decreasing dissimilarities are observed. However, at lower spatial levels (especially within metropolitan areas) much larger dissimilarities in mean income and income distribution occur. In the Netherlands, urban poverty has become a more intense and widespread phenomenon than rural poverty."

Demography↗
PubMed1988

Urban development patterns in Indonesia.

The author examines recent urban development in Indonesia. "Analysis of urban developments in Indonesia has been hampered in the past by weak data. Recently, the National Urban Development Strategy (NUDS) project has generated a set of improved data. This paper aims at elaborating and supplementing the NUDS study. After a discussion of definitional problems, an analysis is carried out of urban growth rates at the provincial level. Private investment is shown to be a principal determinant of urban growth rates. Other significant determinants are rural immigration and the present level of urbanisation. Private investment is shown to be strongly biased towards provinces with large urban areas. In addition, polarisation is studied at the level of individual cities. It is found that a period of rapidly increasing polarisation has come to an end during the last decade."

Asia↗