Analysis and synthesis of resistive n-port networks

Various aspects of analysis and synthesis of resistive n-port networks are considered in this paper. Two different characterizations of the network are examined, the Y matrix characterization and the K matrix characterization. Based on these characterizations, a set of equations is derived which relate the edge admittances with the elements of these matrices. When the K matrix is given, these equations are linear and can be solved analytically. When the Y matrix is given, the equations are bilinear and cannot be solved analytically. In this case, the problem is formulated as an optimization problem and techniques of nonlinear programming are used to obtain a realization. Synthesis from the Y matrix is finally extended to include sensitivity considerations.     

Should students design or interact with models? Using the Bifocal Modelling Framework to investigate model construction in high school science

The Bifocal Modelling Framework (BMF) is an approach for science learning which links students’ physical experimentation with computer modelling in real time, focusing on the comparison of the two media. In this paper, we explore how a Bifocal Modelling implementation supported learning outcomes related to both content and metamodeling knowledge, focusing on the role of designing models. Our study consisted of three conditions implemented with a total of 69 9th grade high-school students. The first and second classes were assigned two implementation modes of BMF: with and without a model design module. The third condition, employed as a control, consisted of a class that received instruction in the school’s traditional approach. Our results indicate that students participating in both BMF implementations demonstrated improved content knowledge and a better understanding of metamodeling. However, only the ‘BMF-with-design’ group improved significantly in both content and metamodeling knowledge. Our qualitative analyses indicate that both BMF groups designed detailed models that included scientific explanations. However only students who engaged in the model design component: (1) completed a detailed model displaying molecular interaction; and (2) developed a critical perspective about models. We discuss the implications of those results for teaching scientific science concepts and metamodeling knowledge.     

Analysis of a varnish applied by Nicéphore Niépce to make a print used for photographic purpose transparent

Nicéphore Niépce carried out a lot of meticulous experiments that led him to the invention of photography. In particular, in the 1820s, he obtained heliographs by coating a substrate with a light-sensitive substance, which was then exposed to light under a paper print made translucent with the help of varnish. The objective of the work described here is to determine how Niépce made these paper prints transparent. Did he use his experimental knowledge on photosensitive resins, or did he apply commonly used recipes of his time to make paper transparent? To date, no studies have been carried out on the varnish used by Nicéphore Niépce and no previous research has undertaken analytical investigations on Nicéphore's prints, using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Gas Chromatography/Mass Spectrometry (GC/MS). In this paper, we identify the varnishes used by Nicéphore Niépce on four transparent prints, now belonging to the Nicéphore Niépce museum in Chalon-sur-Saône, France. The varnish he used was based on a diterpenic Pinaceae sp. resin (most probably colophony). The finding is supported by historical knowledge about varnishes.     

LEDs as a tool to enhance faded colours of museums artefacts

A procedure to enhance the faded colours of museums artefacts is presented. The method is based on adjusting the spectral profile of the light while maintaining a given white colour of the illumination. The procedure is tested using colour LED clusters and a series of damaged samples and their good condition counterparts. The intensity of the three components of four feasible LED clusters is computed in order to produce white illumination metameric to a white LED light source taken as a reference. Colorimetric calculations are performed to model the colour changes undergone by target colour samples using illumination based on colour LED association with respect to the white LED reference. The model is based on CIELAB specification and allows to optimize the choice of three-colour LED associations that modify the hue and the saturation of a few target colour areas of illuminated samples while other areas are left moderately desaturated. Modelling and experimental visual validation were practically obtained by adjusting the intensity of five calibrated colour LEDs, blue, cyan, green, amber and red, accommodated in a light booth. A visual validation was conducted asking 20 observers to rate the colourfulness appearance of aged inkjet prints under every LED cluster with respect to the colourfulness of their original counterparts under the reference white LED source. The visual assessments agreed with the colorimetric predictions. Finally, a demonstration is shown of the feasibility of the method by simulating the rejuvenated appearance of a natural history specimen of which the museum possesses two differently aged items.     

Effects of foreign acquisitions on R&D activity: Evidence from firm-level data for France

This paper investigates the causal effect of foreign acquisitions on the research and development (R&D) activities of domestic target firms over the period 1994–2004. Using accounting data on French innovative manufacturing firms, we implement appropriate difference-in-difference estimation techniques associated with a matching propensity score procedure. We find that the acquisitions of French firms by foreign companies boost R&D spending. There is a simultaneous rise in the external and in-house R&D expenditures of French acquired firms. R&D is more contracted out to local research providers, in particular to local public laboratories and universities. The increase in internal R&D spending benefits to development, but also basic and applied research. Finally, the growth of the R&D budget is not only financed by internal resources but also receives financing from external partners, especially parent companies. Thus, our results call into question the idea that foreign takeovers hamper the R&D development of target firms and are detrimental to the national innovation system of the host country. First, acquisitions appear to bring efficiency gains enough to counterbalance the various costs of integration and market power effects, pushing firms to invest more in R&D. Acquisitions do not seem to incite managers to take shorter term and more financial driven decisions at the expense of R&D. Second, when motivated by technology sourcing and overseas R&D development, acquisitions might be used to access the specific know-how of target firms and to tap into the knowledge of the national innovation system. Then, purchaser firms could be more likely to develop the innovative capability of target firms and to strengthen their linkages with local partners than to reduce them and relocate R&D abroad.     

Pédagogie and didactique: An incestuous relationship

This article deals with the evolution of pedagogical theory in the Francophone world. At present, two major currents of reflection on education exist in the Francophone world. The first, called didactique – didactics – relates to teacher planning, working chiefly from considerations about the pupil's cognitive characteristics. The second, called pédagogie – pedagogy – relates to the features of pedagogical reflection-in-action. This article analyzes the distinctions between the two currents with a view to determining whether they constitute genuine differences.     

Developing University Teachers: an account of a scheme designed for postgraduate researchers on a lecturing career path

Abstract

There is a growing recognition within higher education institutions of the importance of teaching as a core activity for trainee academics. This paper outlines and reports on a scheme which has been established to address the needs of postgraduate researchers who wish to build a career as university teachers. The scheme, now under review at the close of its first year of operation, is one which provides a potential model for other institutions. The paper includes extracts from a frank discussion involving participants in the scheme and highlights some of the practical difficulties which have occurred, in addition to the many benefits which are both expected in the future as well as some which are currently accruing     

Certifying effect and consumer effect: Some remarks on strategies employed by higher education institutions

The term certification, as used in discussions concerning higher education, is clarified and a distinction made between terminal awards which do have a genuine certifying effect in the sense of procuring admission to a profession and those which do not. Institutions wishing to increase the value of the certifying effect of their awards, seek to do this by stimulating applications for entry to their institution. The longer the queue at the gate the greater the prestige of the terminal award. The ability to influence the certifying effect of an award does not, however, lie with the teaching institutions alone; business, the employers and the professions can, and increasingly do, determine the relative value of awards and of different ways of preparing for the exercise of a particular profession. The case of the business schools in France is described to illustrate how teaching institutions once they are established seek to increase the certifying effect of the diplomas they award by actually reducing the number of graduates. The numerus clausus, as applied to medical schools, provides another example of the same phenomenon. Such strategies lead to what the author describes as consumer effect. Once admittance to a prestige institution has been gained, entry to a position of influence and possibly affluence, is more or less assured. Students in such institutions, in both capitalist and communist countries, have exploited this by persuading teaching staff to acquiesce in a reduction of the demands made by the course, though some directors of institutions have begun to respond by failing more students, seeking to re-establish positions surrendered in the days of student unrest and by these and other means seeking to reduce consumer effect. Teacher training colleges provide an interesting example of institutions having a low but certain certifying effect, producing a high consumer effect. The possibility of deriving a general theory from the proposition put forward in the article is discussed.This is an improved version of an article published earlier in French: Effet certifiant et effet clientèle. Quelques remarques sur les stratégies des institutions d'enseignement supérieur dans les pays développés, ESPRIT, nov./dec. 1978. Translation: Sylvia Collot.