Optimal scaling of Metropolis algorithms: Heading toward general target distributions

The authors provide an overview of optimal scaling results for the Metropolis algorithm with Gaussian proposal distribution. They address in more depth the case of high‐dimensional target distributions formed of independent, but not identically distributed components. They attempt to give an intuitive explanation as to why the well‐known optimal acceptance rate of 0.234 is not always suitable. They show how to find the asymptotically optimal acceptance rate when needed, and they explain why it is sometimes necessary to turn to inhomogeneous proposal distributions. Their results are illustrated with a simple example.     

Applicability of a Neuroprobabilistic Integral Risk Index for the Environmental Management of Polluted Areas: A Case Study

Recently, we developed a GIS-Integrated Integral Risk Index (IRI) to assess human health risks in areas with presence of environmental pollutants. Contaminants were previously ranked by applying a self-organizing map (SOM) to their characteristics of persistence, bioaccumulation, and toxicity in order to obtain the Hazard Index (HI). In the present study, the original IRI was substantially improved by allowing the entrance of probabilistic data. A neuroprobabilistic HI was developed by combining SOM and Monte Carlo analysis. In general terms, the deterministic and probabilistic HIs followed a similar pattern: polychlorinated biphenyls (PCBs) and light polycyclic aromatic hydrocarbons (PAHs) were the pollutants showing the highest and lowest values of HI, respectively. However, the bioaccumulation value of heavy metals notably increased after considering a probability density function to explain the bioaccumulation factor. To check its applicability, a case study was investigated. The probabilistic integral risk was calculated in the chemical/petrochemical industrial area of Tarragona (Catalonia, Spain), where an environmental program has been carried out since 2002. The risk change between 2002 and 2005 was evaluated on the basis of probabilistic data of the levels of various pollutants in soils. The results indicated that the risk of the chemicals under study did not follow a homogeneous tendency. However, the current levels of pollution do not mean a relevant source of health risks for the local population. Moreover, the neuroprobabilistic HI seems to be an adequate tool to be taken into account in risk assessment processes.     

How bad can a voting location be

Two questions concerning the location of a single facility by a voting process are investigated for transportation networks:

- What is the maximum number of customers located on the network preferring some rival point over a voting solution?

- How does the average distance of the customers to the facility increase when a voting location instead of a Weber location is chosen for the facility?

Complete answers are given for general networks and for certain planar networks, viz., the so-called generalized cacti.     

Leveraging middle managers’ brokerage for corporate entrepreneurship: The role of multilevel social capital configurations

Building on recent efforts to bring a socio-political perspective to social capital research, we develop and test a multilevel framework that explains why middle managers who occupy brokerage positions differ in their ability and willingness to engage in entrepreneurial behavior. More specifically, we provide a contextualized understanding of the links among middle managers' brokerage, their political-support ties, and their personal initiative. Results derived from data on 383 middle managers and 72 top managers in 34 business units indicate that political-support ties with top managers strengthen the relationship between middle managers’ brokerage and personal initiative. However, this positive effect depends on the social capital resources available in the focal business unit. It is attenuated in business units with a supportive and trusting social context and amplified in business units with high levels of internal connectedness. By uncovering these incompatibilities and complementarities, our study demonstrates the value of accounting for different social capital configurations and the interplay of their inherent social capital resources when examining the effects of brokerage on corporate entrepreneurship.     

The ecosystem blueprint: How firms shape the design of an ecosystem according to the surrounding conditions

Ecosystems are formed by organisations that jointly create a value proposition that a single firm could not create in isolation. To deliver this value proposition, the partners need a focal firm, the orchestrator, to be align them towards the joint value proposition. Thus, how orchestrators design the alignment structure of an ecosystem is at the very heart of the ecosystem concept – yet it has not been sufficiently addressed by extant research. This is all the more true for the question of how the design of an ecosystem is shaped depending on surrounding conditions. This paper applies a qualitative study with ten cases and, based on the attention-based view of the firm, contributes to research on ecosystems in several ways. First, it explains which ecosystem designs are beneficial under which conditions. Second, it elucidates the structure and activities within ecosystems and shows that start-ups can be just as good ecosystem orchestrators as incumbents. Third, it explains the circumstances under which single vs. multi orchestrator ecosystems occur. Fourth, it presents the conditions when incumbents or start-ups make better orchestrators. Finally, it is among the first studies to apply the attention-based view to business ecosystems, and shows that doing so yields intriguing insights into this emerging field of research.     

The relationship between presenteeism and job satisfaction: A mediated moderation model using work engagement and perceived organizational support

Research on presenteeism has largely focused on its prevalence, determinants and consequences on the health of both employees and organizations. To date, few studies have examined the influence of presenteeism on workers’ attitudinal and motivational responses. Based on the Effort–Recovery Theory, this study evaluates the mediating effect of work engagement in the relationship between presenteeism and job satisfaction. Building on previous work, this study also proposes to consider perceived organizational support as a moderator of the work engagement–job satisfaction relationship. Presented in the form of a mediated moderation model, the results of bootstrapped regression analyses show three main results. First, presenteeism is negatively associated with work engagement and job satisfaction. Secondly, work engagement is one of the factors through which presenteeism influences job satisfaction. Thirdly, perceived organizational support moderates the association between work engagement and job satisfaction so that, at a low level of work engagement, feeling supported by the organization makes a difference on job satisfaction. Overall, this research is part of the limited number of studies that have focused on the interplay existing between presenteeism and its consequences in terms of job attitudes.     

Origins and destinies: Immigration to the United States since World War II

Contemporary immigration to the United States and the formation of new ethnic groups are the complex and unintended social consequences of the expansion of the nation to its post-World War II position of global hegemony. Immigrant communities in the United States today are related to a history of American military, political, economic, and cultural involvement and intervention in the sending countries, especially in Asia and the Caribbean Basin, and to the linkages that are formed in the process that open a variety of legal and illegal migration pathways. The 19.8 million foreign-born persons counted in the 1990 U.S. census formed the largest immigrant population in the world, though in relative terms, only 7.9% of the U.S. population was foreign-born, a lower proportion than earlier in this century. Today's immigrants are extraordinarily diverse, a reflection of polar-opposite types of migrations embedded in very different historical and structural contexts. Also, unlike the expanding economy that absorbed earlier flows from Europe, since the 1970s new immigrants have entered an hourglass economy with reduced opportunities for social mobility, particularly among the less educated, and new waves of refugees have entered a welfare state with expanded opportunities for public assistance. This paper seeks to make sense of the new diversity. A typology of contemporary immigrants is presented, and their patterns of settlement, their distinctive social and economic characteristics compared to major native-born racial-ethnic groups, and their different modes of incorporation in—and consequences for—American society are considered.     

Composition-consistent tournament solutions and social choice functions

This paper introduces a new axiom for choice in preference profiles and tournaments, called composition-consistency. A social choice function is composition-consistent if it is non-sensitive to the cloning of one or several outcomes. The key feature of the composition consistency property is an operation concept called multiple composition product of profiles. The paper provides a brief overview of some social choice functions studied in the literature. Concerning the tournament solutions, it is proved that the Top Cycle, the Slater and the Copeland solutions are not composition-consistent, whereas the Banks, Uncovered Set, TEQ, Minimal Covering Set are composition-consistent. Moreover, we define the composition-consistent hull of a solution as the smallest composition-consistent solution containing . The composition-consistent hulls of the Top cycle and Copeland solutions are specified, and we give some hints about the location of the hull of the Slater set. Concerning social choice functions, it is shown that Kemeny, Borda and Minimax social choice functions are not composition-consistent, whereas the Paretian one is composition-consistent. Moreover, we prove that the latter is the composition-consistent hull of the Borda and Minimax functions.     

Changes in the social definition of early childhood and the new forms of symbolic violence

Conclusion The nursery school may be considered an institution and a market where the habits produced by the family are moulded, developed and standardized; thus, it is confronted with an objective definition of early childhood embedded in pedagogical practices. The proper objective of a sociology of nursery-school practice is the analysis of the lag between the functions delegated to the school by the different social classes and the functions which it objectively tends to fulfill. Here we have the best test of the lag between the pedagogic demands of the different classes and what the schools supply-which is very abstract, with results that are only visible at a later stage in the school career. It is not so much a question of learning to read or of preparing to do so (the acquisition of certain logical operations or a developed sensitivity, of acquiring a few I.Q. points). This learning takes place through many varied activities which apppear to be far from the learning function.All told, the conditions for understanding nursery-school exercises flow from the conditions for inventing these exercises. For instance, in games of manipulation, construction, classifying various objects, is not some knowledge of Piaget (at least in the sense of some psychologikal knowledge) needed to understand that practical manipulation is also logical manipulation, to see in cube games the learning of logic? Similarly, the language naïveté cultivated in language games is a clever naïveté, which supposes for example a cultured re-discovery of popular archaic language or of child talk. p ]Is it not likely to appear as pure childishness to those who, without the ncessary cultural knowledge, do not have the keys to decipher these ostensibly naïve exercises? Similarly, the conditions for understanding children's drawings as artistic learning (and the nursery school as an educational institution) are the very conditions for understanding modern art as art.It is not just a matter of perception and understanding; as the objective definition of early childhood proper to the different social classes becomes pervasive both in the relationship with school and in the socialization practices of the family, it patterns the children's habitus (as long-lasting internalized dispositions), which in turn influence the child's behavior and attitude towards school.The perception categories and the different forms of treatment of young children appropriate to each social class are not simply the result of the diffusion of definitions of early childhood produced by the autonomous evolution of scientific and artistic disciplines. They are the products of all the social and cultural conditions which define the class situation. We may also wonder whether at least some pedagogy and certain types of exercises do not presume that the child has socially marked attitudes, produced in some classes by family inculcation. For instance, a general attitude of disinterested interest is required by a pedagogy offering multiple activities and open to an attitude of active research and exploration. Does not this attitude suppose as an existential possibility the condition of social classes protected from economic pressure and from the urgency of immediate life, a general attitude towards life nearer to leisure than to the constraints of work?Thus, in confronting supply with demand—here even less than elsewhere-there is no question of comparing the expectations arising from users' opinions with the program offered in the official definition of the institution. The expectations are those which arise from objective determinations inherent in each social group, the forms of treatment and perception of early childhood. To analyze the program-and therefore to ascertain the social conditions governing the use of the nursery school—the dominant definition of early childhood on which the institution is founded must be brought to light. Moreover, the way in which this definition is written into the curriculum (and, subsequently, into pedagogical practice) must also be studied. This implies that the preliminary condition for a sociological analysis of the functions performed by the nursery school for the different social classes would be an analysis of a) the components of this dominant definition of early childhood and b) of the social conditions in those groups which make it possible to identify these components.We wish to thank P. Bourdieu for his advice during our research. R. Collins provided useful suggestions after reading the first version of this paper.