Potential Competition in Preemption Games

We consider a preemption game with two potential competitors who come into play at some random secret times. The presence of a competitor is revealed to a player only when the former moves, which terminates the game. We show that all perfect Bayesian equilibria give rise to the same distribution of players' moving times. Moreover, there exists a unique perfect Bayesian equilibrium in which each player's behavior from any time on is independent of the date at which she came into play. We find that competitive pressure is nonmonotonic over time, and that private information tends to alleviate rent dissipation. Our results have a natural interpretation in terms of eroding reputations.

Influence of boundary conditions on yielding in a soft glassy material

The yielding behavior of a sheared Laponite suspension is investigated within a 1 mm gap under two different boundary conditions. No-slip conditions, ensured by using rough walls, lead to shear localization as already reported in various soft glassy materials. When apparent wall slip is allowed using a smooth geometry, the sample is shown to break up into macroscopic solid pieces that get slowly eroded by the surrounding fluidized material up to the point where the whole sample is fluid. Such a drastic effect of boundary conditions on yielding suggests the existence of some macroscopic characteristic length that could be connected to cooperativity effects in jammed materials under shear.Comment: 4 pages, 5 figure

Depletion and social reproduction

Much work has been done on the unaccounted contribution of social reproductive work to national economies. What has been less studied is the consequence of this neglect for individuals, households and communities engaged in social reproduction. Where these consequences have been recognised, it has largely been in the context of economic crises. So, for example, Elson has pointed out in her analysis of gendered impact of crises, "If too much pressure is put upon the domestic sector to provide unpaid care work to make up for deficiencies elsewhere, the result may be a depletion of human capabilities, ...To maintain and enhance human capabilities, the domestic sector needs adequate inputs from all other sectors. It cannot be treated as a bottomless well, able to provide the care needed regardless of the resources it gets from the other sectors" (2000:28). In this paper we take this insight and develop it in the context of the everyday political economy. We argue that the inputs into social reproduction are less than the outputs generated by it. We term this difference depletion

The role of boundary objects in the co-evolution of design and use: the KMP project experimentation

Nowadays, it is widely recognized that an ICT tool cannot be built without knowing who will use it and what they will do with. In this perspective, Human-Computer Interaction community (Carroll, 1990; Jarke, Tung Bui and Carroll, 1998; Young and Barnard, 1987; Young and al., 1989) developed a scenario-based approach contrasting with the traditional information system design. The scenario describes an existing or envisioned system from the perspective of one or more users and includes a narration of their goals, plans and reactions (Rosson and Carroll, 2002). As a result, design is founded on the use of scenarios as a central representation for the analysis and design of use. The scenario-based design appears to be a first step in the integration of users in the design of ICT tool. However, we would like to underline in this paper a more active role of users in the design process. According to Orlikowski (2000) while a technology can be seen to have been constructed with particular materials and inscribed with developers' assumptions and knowledge about the world at a point in time, it is only when this technology is used in recurrent social practices that it can be said to structure user's action. The use of technology in recurrent social practices must be considered because how technological properties will for the moment be used or appropriate is not inherent or predetermined. Finally, this approach leads us to dissociate the designers' world from the users' world. In this perspective, the design project is the result of the co-evolution and the convergence of both worlds: on the one hand, the world of design and a first integration of users by scenarios; on the other hand, the world of users where innovation is the art of interesting an increasing number of allies who will make the world of design stronger and stronger. The objective of this paper is to understand the mechanisms of interaction between the world of design and that of users i.e. between loops of co-design and loops of uses. Indeed, according to Akrich, Callon and Latour (1988) we adopt a whirlwind model of innovation. In this perspective, “innovation continuously transforms itself according to the trials to which it is submitted i.e. of the “interessements” tried out » (Akrich and al., 2002: 7). We will demonstrate that the key success of an innovation depends on the co-evolution and convergence of design and use around boundary objects developed during this process (see Figure 1). More specifically, we will show the role of boundary objects on the integration and on the involvement of users in the design process. In order to do so, we carried out an empirical research – the Knowledge Management Platform project - located in the scientific park of Sophia Antipolis (Alpes-Maritimes, France), focusing on the Telecom Valley® (TV) association which gathers the main actors of the Sophia Antipolis Telecom cluster. Indeed, the KMP project aims to build a semantic web service of competencies in order to enhance exchange and combination dynamics of knowledge within the Telecom cluster thanks to an interactive mapping of competencies. This paper will comprise three parts: Based on the researches of Akrich, Callon and Latour (1988), Hatchuel and Mollet (1986), Orlikowski (2000), Romme and Endenburg (2006) we will identify and analyse in a first part the process of design. The combination of these approaches leads us to distinguish the design' world from the users' world. In this perspective, the success of an innovation may be explained by the co-evolution and the convergence of these two worlds. In this process, we suggest that boundary objects play a key role in the convergence of these two worlds. We will present in a second part the empirical study of the KMP project within the TV network. The KMP project involved researchers from socio-economic sciences (GREDEG Laboratory, UNSA-CNRS, Rodige and Latapses teams), cognitive sciences and artificial intelligence (INRIA, Acacia team), telecommunications (GET) and users (TV) for a total force of 187 men per month for a two-year period (2003-2005). At this present time this project is being set up in a pre-industrialization phase, supported by TV and the PACA region. Here, we will analyse the specific process of design experimented by KMP. Finally, the third part discusses the role of boundary objects in the KMP experimentation. In this part, we will show the evolution of boundary objects during the loops of design. More specifically, the focus will be on the emergence of compromises between designers and users, their materialisation in boundary objects and finally their evolution during the design' process.boundary objects, IS development, actor network theory

Capacity Investment under Demand Uncertainty. An Empirical Study of the US Cement Industry, 1994‐2006

Uncertainty about the level of demand is thought to influence irreversible capacity decisions. This paper examines some implications of the theory literature on this topic in an empirical study of the US cement industry between 1994 and 2006. Firms in this sector have the ability to deliver cement either from domestic plants or from imports. Since cement is costly to transport via land, the difference in marginal cost between local production and imports varies across local markets. The marginal cost of imports is lower in areas with access to a sea port, decreasing the relative value of investing in local capacity sufficient to supply positive local demand shocks. In the presence of uncertain demand, firms may choose to serve these markets via both domestic production and imports. Consistent with the theory, we find a negative relationship between the average level of excess capacity and demand volatility only for coastal areas. An increase in demand volatility is associated with an increase in excess capacity only in landlocked areas. More generally, the paper shows that the cost of imports relative to the cost of domestic production affects the relationship between uncertainty and domestic capacity decisions. The results suggest that a unilateral climate policy in the US may induce a partial international relocation of capacity in carbon intensive industries, such as cement, by increasing the relative cost of domestic production.Capacity Investment, Demand Uncertainty, Imports, Cement

Capacity Investment under Demand Uncertainty. An Empirical Study of the US Cement Industry, 1994-2006

Uncertainty about the level of demand is thought to influence irreversible capacity decisions. This paper examines some implications of the theory literature on this topic in an empirical study of the US cement industry between 1994 and 2006. Firms in this sector have the ability to deliver cement either from domestic plants or from imports. Since cement is costly to transport via land, the difference in marginal cost between local production and imports varies across local markets. The marginal cost of imports is lower in areas with access to a sea port, decreasing the relative value of investing in local capacity sufficient to supply positive local demand shocks. In the presence of uncertain demand, firms may choose to serve these markets via both domestic production and imports. Consistent with the theory, we find a negative relationship between the average level of excess capacity and demand volatility only for coastal areas. An increase in demand volatility is associated with an increase in excess capacity only in landlocked areas. More generally, the paper shows that the cost of imports relative to the cost of domestic production affects the relationship between uncertainty and domestic capacity decisions. The results suggest that a unilateral climate policy in the US may induce a partial international relocation of capacity in carbon intensive industries, such as cement, by increasing the relative cost of domestic production.capacity investment, demand uncertainty, imports, cement

Melting, vaporization, and energy partitioning for impacts on asteroidal and planetary objects

A three-dimensional smoothed particle hydrodynamics code was used to model normal and oblique impacts of silicate projectiles on asteroidal and planetary bodies. The energy of the system, initially in the kinetic energy of the impactor, is partitioned after impact into internal and kinetic energy of the impactor and the target body. These simulations show that, unlike the case of impacts onto a half-space, a significant amount of energy remains in the kinetic energy of the impacting body, as parts of it travel past the main planet and escape the system. This effect is greater for more oblique impacts, and for impacts onto the small planets. Melting and vaporization of both bodies were also examined. The amount of the target body melted was much greater in the case of smaller targets than for an impact of a similar scale on a larger body

Leniency Programs in a Multimarket Setting: Amnesty Plus and Penalty Plus

We examine the effect of Amnesty Plus and Penalty Plus on firms' initial selfreporting decision, in one market, by altering their whistle-blowing incentives in another market. Amnesty Plus and Penalty Plus are proactive US strategies which aim at triggering multiple confessions by increasing the incentives of already convicted firms to report in a second market where they collude. Predictably, conditional on the conviction of one cartel, Amnesty Plus and Penalty Plus strengthen firms' incentives to report the remaining cartel. However, Amnesty Plus and Penalty Plus have an ambiguous impact on firms' incentives to apply for amnesty in the first place: On the one hand, Amnesty Plus and Penalty Plus may help to sustain a cartel, otherwise reported under the EC Leniency Program. On the other hand, Amnesty Plus and Penalty Plus may induce immediate reporting of both cartels whereas only one of them would have been reported under the EC Leniency Program.Amnesty Plus; Leniency Program; Multimarket Contact; Self-reporting