Aux limites du paradigme de la distribution : l’écoute des appels de détresse et le traitement de la souffrance des suicidaires,du téléphone à l’e-mail

How can a telephone hotline for helping the suicidal be seen as a distributed practice and collective skill? Based on fieldwork, this research reviews the paradigm of distributed action by broadening it to activities that imply not only cognition but also moral and emotional dimensions. Two limits of this paradigm are discussed. The first, illustrated with the shift from telephone calls to electronic mail, bears on the capacity for analyzing the development of activities; it leads to a discussion of the differences and similarities between distributed cognition and activity theory. The second has to do with covering up the political dimension of distributed cognition: how do the persons involved in an activity perceive what they do and act on their perceptions — how are they “concerned”? This case study of a counseling hotline by telephone and E-mail raises questions about the performative nature of the words used to express suffering.     

Copules archimédiennes et families de lois bidimensionnelles dont les marges sont données

Every bivariate distribution function with continuous marginals can be represented in terms of a unique copula, that is, in terms of a distribution function on the unit square with uniform marginals. This paper is concerned with a special class of copulas called Archimedean, which includes the uniform representation of many standard bivariate distributions. Conditions are given under which these copulas are stochastically ordered and pointwise limits of sequences of Archimedean copulas are examined. We also provide two new one-parameter families of bivariate distributions which include as limiting cases the Frechet bounds and the independence distribution.     

‘Minimum level of activity’—A quick method of assessing growth potential in the smaller business

The purpose of this article is to provide a method for making a quick assessment of the growth potential of small and medium-sized companies. It provides in particular a calculation of the maximum level of activity to cover costs and achieve a given rate of profitability. This method makes use of graphic material and of simple relations, and does not involve complex calculations. It enables the user to make a simplified forecast of his accounts.     

OR/MS methodology—A conceptual framework

Many authors deal, explicitly or implicitly, with OR/MS methodology and the term ‘methodology’ has gained such an inclusive connotation that it comes to denote nothing in particular. This has diluted the analytical precision of OR/MS ‘methodology’ as well as its practicability. Therefore an attempt to form a conceptual framework for OR/MS methodology will be presented. This framework consists of seven components addressing specific methodological aspects: each component has specific properties which distinguish it from the others; all of them together form a consistent hierarchy suitable to aid the successful development and implementation of OR/MS methods.     

Mitochondrial Dynamics in Cell Life and Death

Mitochondria are dynamic organelles that are able to change their morphology during cellular development and to meet the energetic needs of the cell, for example. During the past several years, knowledge about the molecular machinery involved in the control of mitochondrial shape has improved considerably. In August 2005, leading researchers in the field of mitochondrial dynamics met at the Venetian Institute of Molecular Medicine in Padova, Italy, to discuss novel and intriguing findings presented at the first workshop on "Mitochondrial Dynamics in Cell Life and Death." Some of the findings related to apoptosis and aging are described in this Perspective.     

Pooling operators with the marginalization property

In this paper, we consider the problem of combining a number of opinions which have been expressed as probability measures P₁, …, P_n, over some space. It is shown that a pooling formula which has the marginalization property of McConway (1981) must be of the form T = Σⁿ_i=₁W_i P_i + (1 - Σⁿ_i =₁W_i)Q, where Q is an arbitrary measure and W₁, …, W_n ϵ [—1,1] are weights such that| Σ_J Σ _j w_j | ≤ 1 for every subset J of {1, …, n}. If, in addition, T is required to preserve the independence of arbitrary events A and B whenever these events are independent under each P_i, then either T = P_i for some 1 ≤ i ≤ n or T = Q, in which case Q takes values in {0, l}.     

The two-sample t test versus satterthwaite's approximate f test

A comparison between the two-sample t test and Satterthwaite's approximate F test is made, assuming the choice between these two tests is based on a preliminary test on the variances. Exact formulas for the sizes and powers of the tests are derived. Sizes and powers are then calculated and compared for several situations.