Accessibility as the objective of public transportation planning: an integrated transportation and land use model

The subject of this paper is planning of public transportation in sparsely populated areas.The paper consists of four main parts. In part I an analysis of the system to be planned is carried out. A comparison with a survey on the traffic and transportation models available in the literature, though very voluminous, reveals a lack of a general model-framework for planning public transportation in sparsely populated areas. It is the aim of the present paper to fill this gap.Part II discusses how to evaluate optional plans for the physical and socio-economic structure of a region and concludes that this must be done by means of accessibility. Acessibility is defined in this paragraph.In part III a model is presented which describes the interdependance between on one hand the demand of accessibility of the population and on the other hand the transportation system, both public and private, and the location of facilities and residential areas. The applicability of some standard transportation and traffic models is discussed briefly in this section.Finally part IV describes a case study, in which the models set out in part III are applied. Some results are presented with conclusions.     

Measurements of angular distributions of sputtered material as a new tool for surface-segregation studies: Segregation in CuPt alloys

The angular distribution of copper and platinum sputtered by argon ions from polycrystalline CuPt targets at 77 K has been measured by a collection technique. The argon-ion energy has been varied from 1.25 to 320 keV. For bombardment energies above 20 keV, differences in the angular distributions for the two elements indicate a strong copper segregation to the surface during bombardment.     

3J(PCNH) in phosphorus substituted thioformamides as a configurational probe

Coupling between P and (N)? H has been observed in the ¹H{¹⁴N}NMR spectra of a series of phosphorus substituted thioformamides, R¹₂/P(X)C(S)NHR². For R² = H one of the two couplings constants ³J(PCNH) is much larger than the other. The larger constant is assumed to be ³J(PCNH) (trans) and the magnitude of ³J(PCNH) for several compounds with R² = Me or Ph is used to assign the configuration about the C(S)? N bond.     

The mathematical technique in Fermat's deduction of the law of refraction

This article attempts to explain Fermat's not quite obvious calculations connected with his deduction of the law of refraction in Analysis ad refractiones (1662), and to describe the development which led to these calculations. In 1657 Fermat tried to deduce a law of refraction based on the principle that light follows the quickest path between two given points. He did not succeed because he found that the calculations were too long and tedious. The calculations are indeed complicated, but if Fermat, in 1657, had been willing to accept Descartes' law of refraction he would probably also have seen that it solved his problem. However, Fermat was of the opinion that Descartes' law was wrong and, therefore, he did not expect that solution. Only in 1662, when he succeeded in reducing the calculations substantially, did he realize that they led to the sine law of Descartes.     

The differential equations of the Voigt function

The three second-order partial differential equations of the Voigt function are presented, leading to a powerful and accurate method of determining the Voigt function in the calculation of a line profile in a stellar atmosphere.     

Dopant-modulated pair interaction in cuprate superconductors

A comparison of recent experimental STM data with single-impurity and many-impurity Bogoliubov-de Gennes calculations strongly suggests that random out-of-plane dopant atoms in cuprates modulate the pair interaction locally. This type of disorder is crucial to understanding the nanoscale electronic inhomogeneity observed in BSCCO-2212, and can reproduce observed correlations between the positions of impurity atoms and various aspects of the local density of states such as the gap magnitude and the height of the coherence peaks. Our results imply that each dopant atom modulates the pair interaction on a length scale of order one lattice constant.     

Stopping power in insulators and metals without charge exchange

The slowing-down process of pointlike charged particles in matter has been investigated by measuring the stopping power for antiprotons in materials of qualitatively very different nature. Whereas the velocity-proportional stopping power observed for metal-like targets such as aluminum over a wide energy range of 1-50 keV is in agreement with expectations, it is surprising that the same velocity dependence is seen for a large band-gap insulator such as LiF. The validity of these observations is supported by several measurements with protons and several checks of the target properties. The observations call for both a qualitative explanation and a quantitative theoretical model.