An age‐structured model of population dynamics with dominant ages,delayed behavior,and oscillations

An age‐structured model of population dynamics with age‐dominance is proposed and analyzed. Existence and uniqueness of solutions are established as well as the uniqueness and local asymptotic stability of steady‐states. Conditions for convergence to or oscillation about the steady‐state are specified in some cases.     

Contextual Variability in Young Children's Gender Ingroup Stereotype

Self-categorization theorists (Oakes, Haslam & Turner, 1994) have shown that stereotypes are not rigid and fixed, and that they vary to reflect variations in the comparative context within which they are formed. In this paper we investigate stereotype variability in a sample of 6/7-year-old children. Participants describe a specific outgroup, and then describe the ingroup (that is 'boys' or 'girls', depending on the sex of the participant). There are two conditions: in condition one the outgroup is represented by adult 'men', if participants are boys, or by adult 'women', if participants are girls. In condition two the outgroup is represented by 'girls', if participants are boys, or by 'boys', if participants are girls. Results show that stereotypical traits attributed to the ingroup change significantly with changes in the frame of reference.     

Swinger economics

Swinging is a sexual behaviour of increasing relevance but substantially ignored in theoretical economic investigation. This paper has two major goals. The first is to describe what swinging is, discuss its economic relevance and single out the main characteristics of swinger behaviour. To this end, the Italian situation has been considered as a type of case study. The second goal is to use standard and less-standard tools from economic theory to propose some preliminary assessments of the causes and consequences of swinger couples’ behaviour. In this respect, some contributions on two-sided markets, hedonic adaptation approaches and equilibrium matching models have proved particularly useful.     

Art dealers as competitors and community builders: Understanding the overlapping social logics of the contemporary art world

Art dealers are often described as gatekeepers who are focused on their own position as well as the status of their artists and collectors. We argue that this is an incomplete account of art dealing. The goal of this article is to explain how art dealing is a “toolkit” that does not exclusively focus on status building and social capital, but also includes behavior associated with accessing the visual arts field and community development. First, art dealers often have a background that has strong social ties to art, which provides them with intimate knowledge of the art world and social connections with artists, collectors, and other art world actors. For that reason, entry into art dealing reflects intimate knowledge of art practices, what we call “proximate connoisseurship.” Second, art dealerships reflect both competitive and communal factors. Art dealers may choose to work with artists based on their ability to generate income, social capital, and prestige (“competitive logic”), but art dealers may also employ a “communal logic” focused on friendships and creating community. This theory of art dealers is illustrated with excerpts from interviews with 34 dealers randomly selected from the rosters of international art fairs such as Art Basel Miami, EXPO Chicago, Aqua, and the New Art Dealers Alliance show.     

On multivariate smoothed bootstrap consistency

This paper deals with the convergence in Mallows metric for classical multivariate kernel distribution function estimators. We prove the convergence in Mallows metric of a locally orientated kernel smooth estimator belonging to the class of sample smoothing estimators. The consistency follows for the smoothed bootstrap for regular functions of the marginal means. Two simple simulation studies show how the smoothed versions of the bootstrap give better results than the classical technique.     

An exact semidefinite programming approach for the max-mean dispersion problem

This paper proposes an exact algorithm for the Max-Mean dispersion problem (\(Max-Mean DP\)), an NP-Hard combinatorial optimization problem whose aim is to select the subset of a set such that the average distance between elements is maximized. The problem admits a natural non-convex quadratic fractional formulation from which a semidefinite programming (SDP) relaxation can be derived. This relaxation can be tightened by means of a cutting plane algorithm which iteratively adds the most violated triangular inequalities. The proposed approach embeds the SDP relaxation and the cutting plane algorithm into a branch and bound framework to solve \(Max-Mean DP\) instances to optimality. Computational experiments show that the proposed method is able to solve to optimality in reasonable time instances with up to 100 elements, outperforming other alternative approaches.     

Agency Problems and Airport Security: Quantitative and Qualitative Evidence on the Impact of Security Training

We analyze the issue of agency costs in aviation security by combining results from a quantitative economic model with a qualitative study based on semi‐structured interviews. Our model extends previous principal‐agent models by combining the traditional fixed and varying monetary responses to physical and cognitive effort with nonmonetary welfare and potentially transferable value of employees' own human capital. To provide empirical evidence for the tradeoffs identified in the quantitative model, we have undertaken an extensive interview process with regulators, airport managers, security personnel, and those tasked with training security personnel from an airport operating in a relatively high‐risk state, Turkey. Our results indicate that the effectiveness of additional training depends on the mix of “transferable skills” and “emotional” buy‐in of the security agents. Principals need to identify on which side of a critical tipping point their agents are to ensure that additional training, with attached expectations of the burden of work, aligns the incentives of employees with the principals' own objectives.     

How to cut a pizza fairly: Fair division with decreasing marginal evaluations

Existential and constructive solutions to the classic problems of fair division are known for individuals with constant marginal evaluations. By considering nonatomic concave capacities instead of nonatomic probability measures, we extend some of these results to the case of individuals with decreasing marginal evaluations. Received: 12 June 2001/Accepted: 23 May 2002 An earlier version of this paper, Caltech Social Science Working Paper # 1126, was titled “How to cut a cake healthily”. We wish to thank Maristella Botticini, Erio Castagnoli, Marco Dall'Aglio, Paolo Ghirardato, Luigi Montrucchio, Marco Scarsini, Marciano Siniscalchi, as well as Maurice Salles (the Editor), an Associate Editor, and four anonymous Referees for helpful suggestions. The financial support of MIUR, CNR, and Università Bocconi is gratefully acknowledged. Part of this research was done while the first author was visiting Boston University and the California Institute of Technology, which he thanks for their hospitality.