Stop or Continue Data Collection: A Nonignorable Missing Data Approach for Continuous Variables

We present an approach to inform decisions about nonresponse follow-up sampling. The basic idea is (i) to create completed samples by imputing nonrespondents' data under various assumptions about the nonresponse mechanisms, (ii) take hypothetical samples of varying sizes from the completed samples, and (iii) compute and compare measures of accuracy and cost for different proposed sample sizes. As part of the methodology, we present a new approach for generating imputations for multivariate continuous data with nonignorable unit nonresponse. We fit mixtures of multivariate normal distributions to the respondents' data, and adjust the probabilities of the mixture components to generate nonrespondents' distributions with desired features. We illustrate the approaches using data from the 2007 U. S. Census of Manufactures

ACME vs PDDL: support for dynamic reconfiguration of software architectures

On the one hand, ACME is a language designed in the late 90s as an interchange format for software architectures. The need for recon guration at runtime has led to extend the language with speci c support in Plastik. On the other hand, PDDL is a predicative language for the description of planning problems. It has been designed in the AI community for the International Planning Competition of the ICAPS conferences. Several related works have already proposed to encode software architectures into PDDL. Existing planning algorithms can then be used in order to generate automatically a plan that updates an architecture to another one, i.e., the program of a recon guration. In this paper, we improve the encoding in PDDL. Noticeably we propose how to encode ADL types and constraints in the PDDL representation. That way, we can statically check our design and express PDDL constraints in order to ensure that the generated plan never goes through any bad or inconsistent architecture, not even temporarily.Comment: 6\`eme \'edition de la Conf\'erence Francophone sur les Architectures Logicielles (CAL 2012), Montpellier : France (2012

Issues of Architectural Description Languages for Handling Dynamic Reconfiguration

Dynamic reconfiguration is the action of modifying a software system at runtime. Several works have been using architectural specification as the basis for dynamic reconfiguration. Indeed ADLs (architecture description languages) let architects describe the elements that could be reconfigured as well as the set of constraints to which the system must conform during reconfiguration. In this work, we investigate the ADL literature in order to illustrate how reconfiguration is supported in four well-known ADLs: pi-ADL, ACME, C2SADL and Dynamic Wright. From this review, we conclude that none of these ADLs: (i) addresses the issue of consistently reconfiguring both instances and types; (ii) takes into account the behaviour of architectural elements during reconfiguration; and (iii) provides support for assessing reconfiguration, e.g., verifying the transition against properties.Comment: 6\`eme Conf\'erence francophone sur les architectures logicielles (CAL'2012), Montpellier : France (2012

Managing Mobility for Human Development: The Growing Salience of Mixed Migration

In the analysis of migration a basic distinction is often made between those who chose to move and those who are forced to – that is, between ‘voluntary’ and ‘forced’ migrants. This distinction is maintained in the policy world, where the governance of international migration is shaped by the conceptual distinction between ‘voluntary’ and ‘forced’ migration as mutually exclusive categories. In reality of course the distinction is far from clear-cut. Migration can be ‘mixed’ in several senses: motivations may be mixed at the point of making the decision to move, when there are often combinations of choice and compulsion in play; people may travel with others in mixed migratory flows; motivations may change en route; and people may find themselves in mixed communities during their journeys or at their destination. This paper explores the connections between mixed migration and human development, understood as the expansion of capabilities and choice (Sen 1999). It first clarifies some of the key concepts in the migration discourse, particularly the role of choice and compulsion in migration, before exploring the emergence of the notions of ‘mixed migration’ and the ‘migration-asylum nexus’ in the policy arena. The paper then turns to some of the manifestations of ‘mixed migration’ and the conditions migrants encounter in such migration streams. It next considers how mixed migration and migration policies – or ‘migration governance’ -- encounter one another. Finally, some policy conclusions are drawn from the evidence presented, pointing to the idea that the transnational practices that arise from mixed migration may constitute a ‘durable solution’ in settings of conflict and displacement.mixed migration, force and choice, refugees, migration policy, development

Managing mobility for human development: the growing salience of mixed migration

In the analysis of migration a basic distinction is often made between those who chose to move and those who are forced to – that is, between ‘voluntary’ and ‘forced’ migrants. This distinction is maintained in the policy world, where the governance of international migration is shaped by the conceptual distinction between ‘voluntary’ and ‘forced’ migration as mutually exclusive categories. In reality of course the distinction is far from clear-cut. Migration can be ‘mixed’ in several senses: motivations may be mixed at the point of making the decision to move, when there are often combinations of choice and compulsion in play; people may travel with others in mixed migratory flows; motivations may change en route; and people may find themselves in mixed communities during their journeys or at their destination. This paper explores the connections between mixed migration and human development, understood as the expansion of capabilities and choice (Sen 1999). It first clarifies some of the key concepts in the migration discourse, particularly the role of choice and compulsion in migration, before exploring the emergence of the notions of ‘mixed migration’ and the ‘migration-asylum nexus’ in the policy arena. The paper then turns to some of the manifestations of ‘mixed migration’ and the conditions migrants encounter in such migration streams. It next considers how mixed migration and migration policies – or ‘migration governance’ -- encounter one another. Finally, some policy conclusions are drawn from the evidence presented, pointing to the idea that the transnational practices that arise from mixed migration may constitute a ‘durable solution’ in settings of conflict and displacement.mixed migration, force and choice, refugees, migration policy, development