Computer science in Dutch secondary education: independent or integrated?

Nowadays, in Dutch secondary education, computer science is integrated within school subjects. About ten years ago computer science was considered an independent subject, but in the mid-1980s this idea changed. In our study we investigated whether the objectives of teaching computer science as an independent subject are met when computer science is integrated within school subjects. The main problem was that there was no formal curriculum of computer science as an independent subject. Therefore we interviewed 13 experts in the field of computer science and then compared this formal curriculum with the operational (integrated) curriculum, which is still in the development stage. It appears that most of the components of the formal curriculum are being covered by the operational curriculum, and we therefore concluded that these curricula are equivalent, although there may be differences in the level of teaching. In our opinion the best approach to computer science is to combine the independent and the integrated approaches

Experimental evidence for the complete saturation phase in the argon neutral system

An experimental study of the population densities of excited states confirms the existence of the complete excitation saturation phase in the argon neutral system. Collisional radiative coefficients r/sub m//sup (1)/ are independent of n/sub e/ and decrease with decreasing ionization energy. At higher n/sub e/-values the levels are observed to come consecutively into Saha equilibrium (PLTE

An analytical excitation for an ionizing plasma

From an analytical model for the population of high-lying excited levels in ionizing plasmas it appears that the distribution is a superposition of the equilibrium (Saha) value and an overpopulation. This overpopulation takes the form of a Maxwell distribution for free electrons. Experiments for He II, Na I and Ar I confirm the general validity of the mode

A collisional radiative model of the argon ion system tested for a large range of electron densities

The authors previously reported on a comparison between a Collisional Radiative Model (CRM) for the argon ion system and density measurements of the 4s and 4p group of that system from the plasma column of a hollow cathode arc (HCA) (see Physica vol.94C, p.369, 1978). It appeared that there was a factor 3 discrepancy between the model and the experimental data for the 4p group. Measurements with a new type of HCA showed an increasing discrepancy with the existent model with increasing density, so that it was evident that this model was not adequate to give a good explanation of the experimental behaviour of excited groups over the whole density range. The authors have modified induced processes to and from the doubly ionized ground level

A numerical collisional radiative model for the argon neutral system

The authors describe a numerical model developed for the argon neutral system. The major question for non-hydrogenlike systems is which electron-collision cross-section between excited states have to be used, since theoretical or measured values are in general not available. Another severe problem, specific to the numerical approach, is how many states or groups have to be taken into account to get a reliable model. Up till now, the specific results of several CR models for the argon neutral system were unsatisfactory and disagree with each other. The authors present the r/sup 1/(4p) coefficient as a function of the electron density n/sub e

Passive and active spectroscopy on flowing plasmas

The equil. departures of two types of flowing plasmas were studied exptl. The combination of abs. emission spectroscopy with the non-intrusive active tool of Thomson/Rayleigh scattering made it possible to compare the at. state distribution function (ASDF) with its equil. form. The electron excitation kinetics (EEK) of a highly recombinative Cascaded Arc Created Magnetized Expanding Plasma was studied using time resolved laser induced fluorescence. The recombination process was found to be largely affected by heavy particle excitation kinetics (HEK). A comparable study of an inductively coupled plasma revealed that the deviations from partial local Saha equil. (pLSE) were much less pronounced. To get insight in this plasma, global active spectroscopy was performed by following the response to the power interruption