Safety First: Recognizing and Managing the Risks to Child Participants in Magnetic Resonance Imaging Research

Specialized and up-to-date knowledge is required to identify and manage the risks associated with advanced biomedical research. Additional complexities need to be considered when the research involves infants or young children. In this article, we focus on recent information about the physical risks of pediatric magnetic resonance imaging research and highlight information gaps. With an eye to assisting institutional review boards and researchers, we consider strategies for the management of these risks and formulate key questions aimed at exposing hidden hazards. Institutional review boards should ask these questions, and researchers should bear them in mind as they develop research protocols.     

ANDREAS HEINRICH VOIGT AND THE HICKS‐ALLEN REVOLUTION IN CONSUMER THEORY

In 1893, Andreas Heinrich Voigt argued that utility admits only an ordinal characterization. We discuss the apparent impact of Voigt's now forgotten early argument for an ordinal approach to utility on later economists. Edgeworth cited Voigt's ordinal‐cardinal distinction several times in the Economic Journal, bringing both the concept and the terminology into Anglophone economics. In 1927, Rosenstein‐Rodan, too, cited Voigt's argument for ordinal utility. Since Hicks apparently learned the cardinal‐ordinal terminology from Edgeworth, and discussed utility theory and complementarity with Rosenstein‐Rodan, it appears that Voigt's 1893 article is the original source of ordinal utility in economics. (JEL B13, B21)     

An Age-Structured Model for Childhood Obesity

An age-structured model for childhood obesity at population level is fitted to empirical data in order to predict the proportion of overweighted and obese children in the 6–8 and 9–12 year old classes in the region of Valencia, Spain.     

Non-parametric Estimation of Tail Dependence

Abstract.  Dependencies between extreme events (extremal dependencies) are attracting an increasing attention in modern risk management. In practice, the concept of tail dependence represents the current standard to describe the amount of extremal dependence. In theory, multi-variate extreme-value theory turns out to be the natural choice to model the latter dependencies. The present paper embeds tail dependence into the concept of tail copulae which describes the dependence structure in the tail of multivariate distributions but works more generally. Various non-parametric estimators for tail copulae and tail dependence are discussed, and weak convergence, asymptotic normality, and strong consistency of these estimators are shown by means of a functional delta method. Further, weak convergence of a general upper-order rank-statistics for extreme events is investigated and the relationship to tail dependence is provided. A simulation study compares the introduced estimators and two financial data sets were analysed by our methods.     

Siting Praxeology. The Methodological Significance of “Public” in Theories of Social Practices

The concept of “site” is at the center of current debates in theories of social practices as well as in cultural anthropology. It is unclear, however, how to assess the associated methodological assumption that overriding social structures or cultural formations can manifest themselves in sites. The article draws on the conception of social practices and introduces the notion of “publicness” in order to explicate how and why sociality and social structures can be accessed through “siting”. Sites as well as social practices, it is claimed, have to be conceptualized as essentially public and thus principally observable phenomena. This assumption of publicness implicit to both site ontology and theories of social practices is unfolded on the basis of a praxeological reformulation of the paradigm of joint attention elaborated in developmental psychology. To avoid presentist misinterpretations, we then conceptualize sociality as chains of practices across time and space, drawing on the works of Theodore Schatzki, Ludwig Wittgenstein, Anthony Giddens and Bruno Latour. The public carriers of practices (artifacts, symbols, media, bodies) and the translocal structures they establish acquire particular significance in these approaches. In a further step, we present some methodological consequences of the “publicness assumption” and support our arguments by referring to Pierre Bourdieu's study on Distinction.     

On the Estimation of Integrated Covariance Functions of Stationary Random Fields

Abstract.  For stationary vector-valued random fields on     the asymptotic covariance matrix for estimators of the mean vector can be given by integrated covariance functions. To construct asymptotic confidence intervals and significance tests for the mean vector, non-parametric estimators of these integrated covariance functions are required. Integrability conditions are derived under which the estimators of the covariance matrix are mean-square consistent. For random fields induced by stationary Boolean models with convex grains, these conditions are expressed by sufficient assumptions on the grain distribution. Performance issues are discussed by means of numerical examples for Gaussian random fields and the intrinsic volume densities of planar Boolean models with uniformly bounded grains.