Le geste de metier : problèmes de la transmission

La transmission des gestes professionnels est au principe du développement de l'expérience dans beaucoup de métiers. Apprendre un geste c'est le retoucher en fonction des contextes hétérogènes qu'il traverse. Selon Bernstein, les automatismes qui réalisent ce geste sont composés en fonction de la tâche à accomplir, tout comme le contrôle du geste est organisé par l'action. C'est pourquoi nous ne concevons pas la transmission comme une intériorisation simple des gestes de l'imité par l'imitateur. Elle exige la réduction réciproque en cours d'activité de plusieurs mobilisations subjectives de direction opposée et, par suite, une action qui les dépasse toutes à la fois. Dans l'activité professionnelle, un geste se libère du geste des autres non pas en le niant mais par la voie de son perfectionnement lorsqu'il est re-conçu

Are impatient farmers more risk-averse? Evidence from a lab-in-the-field experiment in rural Uganda

Based on data from a field-experiment in rural Uganda, we show that impatient farmers are more risk-averse than patient farmers. We relied on a simplified version of the Convex Time Budget (CTB) method to elicit farmers’ time preferences and on an independent method for eliciting their risk-preferences. We report two important findings. First, we show that our simplified CTB method applied to farmers from Uganda replicates the key findings of Andreoni and Sprenger’s lab experiments that involved student subjects. Second, we establish the existence of a negative correlation between risk tolerance and impatience, based on two independent measures

Articulating practice through the interview to the double

The paper aims to realise the critical potential of the practice lens by contributing to the development of a coherent set of methodologies for investigating work and organisational activity. It does so by introducing and critically assessing the "interview to the double" as a method to articulate and represent practice. After briefly illustrating its history and usage, the paper analyses in depth the setting generated by this unusual interview method. It argues that the nature of the encounter produces narratives that are often morally connoted and idealised in character. As a consequence the method is especially useful to capture the going concerns which orient the conduct of the members and the normative and moral dimension of practice. The paper also shows that because it mimics familiar instruction-giving discursive practices, the method constitutes an effective textual device to convey this moral and normative dimension in a way which remains faithful to its situated and contingent nature of practice

The Spin-Dependent Structure Functions of Nuclei in the Meson-Nucleon Theory

A theoretical approach to the investigation of spin-dependent structure functions in deep inelastic scattering of polarized leptons off polarized nuclei, based on the effective meson-nucleon theory and operator product expansion method, is proposed and applied to deuteron and $^3He$. The explicit forms of the moments of the deuteron and $^3He$ spin-dependent structure functions are found and numerical estimates of the influence of nuclear structure effects are presented.Comment: 42 pages revtex, 7 postscript figures available from above e-mail upon request. Perugia preprint DFUPG 92/9

Real-time pollen identification using holographic imaging and fluorescence measurements

Over the past few years, a diverse range of automatic real-time instruments has been developed to respond to the needs of end users in terms of information about atmospheric bioaerosols. One of them, the SwisensPoleno Jupiter, is an airflow cytometer used for operational automatic bioaerosol monitoring. The instrument records holographic images and fluorescence information for single aerosol particles, which can be used for identification of several aerosol types, in particular different pollen taxa. To improve the pollen identification algorithm applied to the SwisensPoleno Jupiter and currently based only on the holography data, we explore the impact of merging fluorescence spectra measurements with holographic images. We demonstrate, using measurements of aerosolised pollen, that combining information from these two sources results in a considerable improvement in the classification performance compared to using only a single source (balanced accuracy of 0.992 vs. 0.968 and 0.878). This increase in performance can be ascribed to the fact that often classes which are difficult to resolve using holography alone can be well identified using fluorescence and vice versa. We also present a detailed statistical analysis of the features of the pollen grains that are measured and provide a robust, physically based insight into the algorithm's identification process. The results are expected to have a direct impact on operational pollen identification models, particularly improving the recognition of taxa responsible for respiratory allergies.</p