Multilocus linkage analysis by blocked Gibbs sampling

The problem of multilocus linkage analysis is expressed as a graphical model, making explicit a previously implicit connection, and recent developments in the field are described in this context. A novel application of blocked Gibbs sampling for Bayesian networks is developed to generate inheritance matrices from an irreducible Markov chain. This is used as the basis for reconstruction of historical meiotic states and approximate calculation of the likelihood function for the location of an unmapped genetic trait. We believe this to be the only approach that currently makes fully informative multilocus linkage analysis possible on large extended pedigrees.     

La carrière des artistes et les transformations de la production musicale. Relations de travail et relation au travail dans le monde des musiques rap et électroniques

The interaction between the artistic and managerial poles of the world formed by the persons specialized in rap and electronic music in France is described as well as musicians' occupational culture. The aesthetic and organizational characteristics of these musical genres are shown to influence the division of labour in recording and production. Owing to the combination of artistic and managerial activities typical of these musicians, occupational networks are fluid. This blurring of roles is especially visible in the recording labels used from home studios. Technical changes in the “tools” for this work have led these artists to become professionally involved in management and advertising. Cultural motivations also explain this involvement: the critical stance adopted by the “cultures” of rap, electro, techno, etc., tends to make obsolete the image of the artist as a creator who avoids the engineering aspects of the commercial distribution of his recordings. In contrast, rap and electronic musicians' careers develop through participation in many and various projects, which nurtures their artistic production, improves the quality of their groups and enhances their reputations. Accepting more short-term professional engagements supposedly increases their control over their career profiles. However these musicians voice concerns, in particular, about bonds between the individual and the groups whom they cross (and who cross them) — concerns that can be extended to other types de workers caught up in an occupational world organized “by project”.     

Optimization of a catalyst system through the sequential application of experimental design techniques

The selective oligomerisation of ethylene to higher alpha olefins is an area of much recent interest. In this regard, Sasol Technology R{&}D has developed a homogeneous catalyst system based on bis-sulfanylamine (SNS) complexes of chromium for the selective trimerisation of ethylene to 1-hexene. It is activated by methylaluminoxane (MAO), which is an extremely expensive activator. This paper discusses how, through the sequential application of experimental design and response surface techniques, the activator requirements of the catalyst system were reduced 12 times, whilst improving the catalyst activity on a g/g Cr/h basis ca. three times and the activity on a g/g MAO basis ca. nine times. This reduction in the amount of MAO required led to economically attractive catalyst activities for the production of 1-hexene, and would not have been possible without the use of experimental design techniques. This paper will demonstrate the process of investigation through the use of sequential experimental design in practice.     

Optimal saturated block designs when observations are correlated

A- and MV-optimal block designs are identified in the class of minimally connected designs when the observations within blocks are spatially correlated. All connected designs are shown to be D-equal regardless of the correlation structure, and a sufficient condition for E-optimality is presented. Earlier results for the uncorrelated case are strengthened.     

Obstacles to export initiation and expansion

The increasing globalization of markets witnessed in recent years has been paralleled by growing research attention upon the internationalization of small and medium sized firms. In industrialized nations, a significant degree of dormant export potential has been identified in this firm size sector. The proliferation of extant literature can explain structural, behavioural and process-based aspects of export expansion. However, it remains that limited conceptual and empirical insights exist that explain the phenomena underlying pre-export decision making and behaviour. The present inquiry addresses this issue and investigates those obstacles that act upon domestic firms' intentions to enter overseas markets via the export channel. Specifically, the empirical study documented here establishes significant differences in the extent to which exporting obstacles discourage export engagement amongst varied groups of domestic firms considered in terms of their export intention. It also draws a similar comparison between such groups of non-exporting firms and those already engaged in export operations. The findings are interpreted and discussed in the light of current knowledge and attention is paid towards pertinent implications for export management and future research.