Modeling and Simulation of Large Microstructured Particles in Magnetic‐Shape‐Memory Composites

We study composite materials in which single‐crystalline magnetic shape‐memory particles are embedded in a polymer matrix, in the limit of particles much larger than the typical domain size. We first derive an effective macroscopic model, using the mathematical theory of relaxation, and then solve it numerically for practically relevant parameters, and compare with experimental results.     

How do biologists respond to low-intensity armed conflicts? The case of Bangladesh (1961–2011)

Armed conflict affects the biological diversity and biological research regime of a country. This paper takes a low-intensity armed conflict in the biologically and ethnically diverse Chittagong Hill Tracts (CHT) of Bangladesh, as an example, and assesses the response of biologists to this conflict. The study spans the last 50 years dividing it into three periods: pre-conflict (1961?1974), conflict (1975–1997) and post-conflict (1998–2011). Interactions with selected researchers and a literature survey showed that sporadic, intermittent biological research was conducted in this region even during the conflict. The number of research initiatives substantially increased and became more diverse over the last decade. Research opportunity has increased mainly because of improved security and accessibility. Nevertheless, despite the research capacity and a positive attitude among the researchers, some fundamental issues still limit long-term research in this area. The continuing volatile situation due to slow implementation of the 1997 Peace Accord and the tension between rebel factions and indigenous and settler communities in some areas continue to be serious concerns for studying and conserving the biodiversity of this region. Innovative research approaches and the full implementation of the peace agreement are vital to improving the situation for biological research in the CHT. The paper underlines the importance of a biologist’s self-motivation to respond to low-intensity armed conflicts.     

Aging and inhibition processes: The case of metaphor treatment.

The inhibitory deficit hypothesis has often been cited as a possible explanation for cognitive changes related to age. The aim of this study was to develop a new procedure for evaluating effortful inhibition on the basis of the comprehension of metaphors. Our experiment was carried out on younger and older adults, in whom we also measured inhibitory capacity, working memory, and processing speed. The results show that older participants required a longer time and made more frequent errors in rejecting metaphors versus literally false statements. The interference effect was predicted by the psychometric tests designed to evaluate inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design and performance evaluation of ContentPlace,a social-aware data dissemination system for opportunistic networks

In this paper we present and evaluate ContentPlace, a data dissemination system for opportunistic networks, i.e., mobile networks in which stable simultaneous multi-hop paths between communication endpoints cannot be provided. We consider a scenario in which users both produce and consume data objects. ContentPlace takes care of moving and replicating data objects in the network such that interested users receive them despite possible long disconnections, partitions, etc. Thanks to ContentPlace, data producers and consumers are completely decoupled, and might be never connected to the network at the same point in time. The key feature of ContentPlace is learning and exploiting information about the social behaviour of the users to drive the data dissemination process. This allows ContentPlace to be more efficient both in terms of data delivery and in terms of resource usage with respect to reference alternative solutions. The performance of ContentPlace is thoroughly investigated both through simulation and analytical models.     

Session based access control in geographically replicated Internet services

Performance critical services over Internet often rely on geographically distributed architectures of replicated servers. Content Delivery Networks (CDN) are a typical example where service is based on a distributed architecture of replica servers to guarantee resource availability and proximity to final users. In such distributed systems, network links are not dedicated, and may be subject to external traffic. This brings up the need to develop access control policies that adapt to network load changing conditions. Further, Internet services are mainly session based, thus an access control support must take into account a proper differentiation of requests and perform session based decisions while considering the dynamic availability of resources due to external traffic.In this paper we introduce a distributed architecture with access control capabilities at session aware access points. We consider two types of services characterized by different patterns of resource consumption and priorities. We formulate a Markov Modulated Poisson Decision Process for access control that captures the heterogeneity of multimedia services and the variable availability of resources due to external traffic. The proposed model is optimized by means of stochastic analysis, showing the impact of external traffic on service quality. The structural properties of the optimal solutions are studied and considered as the basis for the formulation of heuristics. The performance of the proposed heuristics is studied by means of simulations, showing that in some typical scenario they perform close to the optimum.