Microbiological activities in moonmilk monitored using isothermal microcalorimetry (cave of Vers Chez le Brandt, Neuchatel, Switzerland)

Studies of the influence of microbial communities on calcium carbonate deposits mostly rely on classical or molecular microbiology, isotopic analyses, and microscopy. Using these techniques, it is difficult to infer microbial activities in such deposits. In this context, we used isothermal microcalorimetry, a sensitive and nondestructive tool, to measure microbial activities associated with moonmilk ex-situ. Upon the addition of diluted LB medium and other carbon sources to fresh moonmilk samples, we estimated the number of colony forming units per gram of moonmilk to be 4.8 3 105 6 0.2 3 105. This number was close to the classical plate counts, but one cannot assume that all active cells producing metabolic heat were culturable. Using a similar approach, we estimated the overall growth rate and generation time of the microbial community associated with the moonmilk upon addition of various carbon sources. The range of apparent growth rates of the chemoheterotrophic microbial community observed was between 0.025 and 0.067 h21 and generation times were between 10 and 27 hours. The highest growth rates were observed for citrate and diluted LB medium, while the highest carbon-source consumption rates were observed for low molecular weight organic acids (oxalate and acetate) and glycerol. Considering the rapid degradation of organic acids, glucose, and other carbon sources observed in the moonmilk, it is obvious that upon addition of nutrients during snow melting or rainfall these communities can have high overall activities comparable to those observed in some soils. Such communities can influence the physico-chemical conditions and participate directly or indirectly to the formation of moonmilk.

Vers une sociolinguistique médicale : une approche des objets de langage dans le contexte de la médecine

L'interaction soignant-soigné, dans ses aspects relationnel et communicationnel, a fait l'objet depuis les années 1970 de nombreuses études, inscrites dans une pluralité d'approches théoriques et méthodologiques. L'approche de la sociolinguistique de type médical, dans laquelle s'insère le présent travail de thèse, s'est développée dans le contexte même de ces études. Ce travail s'articule autour de trois sujets de recherche permettant d'illustrer, d'éclairer ainsi que de définir l'approche spécifique de la sociolinguistique médicale et traduisant, par ailleurs, certaines des questions relatives au développement de cette sociolinguistique, qui relève des sciences de la communication et des sciences humaines en médecine. Les deux premiers sujets de recherche se focalisent sur le processus d'échange d'information, central dans l'interaction médicale. Ils portent, pour l'un, sur un format de question spécifique utilisé par des étudiants en médecine dans le cadre d'entretiens avec patients simulés centrés sur l'annonce de mauvaises nouvelles et, pour l'autre, sur la(es) définition(s) d'une unité lexicale attestée dans le contexte communicationnel du VIH/sida. Le troisième sujet de recherche, en corrélation avec les deux autres, traite des défis qui se posent aux chercheurs-sociolinguistes relativement à l'étude et à la production de savoirs sur des questions liées à la santé et à la maladie. - Since the 1970's, many studies, following various theoretical and methodological approaches, have investigated - from a relational and communication point of view - the interaction between health care professionals and patients. The approach of the medical sociolinguistics, on which this PhD thesis is based, has been developed in the context of these studies. This PhD thesis is centred on three research topics illustrating and revealing the specific approach of the medical sociolinguistics and reflecting, as regards the third research topic, on particular issues related to the development of this discipline belonging to both communication sciences and medical humanities. The first two research topics focus on the information sharing process, a main phase and purpose of the medical interaction. They address (i) a particular question design used by medical students with simulated patients in breaking bad news interviews, and (ii) the meaning of a lexical unit used in the HIV/AIDS communication context. The third topic, related with the two other, focuses on the challenges faced by medical sociolinguists while producing knowledge and investigating health- and disease-related issues.