Estimating seasonal abundance of a central place forager using counts and telemetry data

R.J.S. was supported by a Natural Environment Research Council studentship.Obtaining population estimates of species that are not easily observed directly can be problematic. However, central place foragers can often be observed some of the time, e.g. when seals are hauled out. In these instances, population estimates can be derived from counts, combined with information on the proportion of time that animals can be observed. We present a modelling framework to estimate seasonal absolute abundance using counts and information from satellite telemetry data. The method was tested on a harbour seal population in an area of southeast Scotland. Counts were made monthly, between November 2001 and June 2003, when seals were hauled out on land and were corrected for the proportion of time the seals were at sea using satellite telemetry. Harbour seals (n=25) were tagged with satellite relay data loggers between November 2001 and March 2003. To estimate the proportion of time spent hauled out, time at sea on foraging trips was modelled separately from haul-out behaviour close to haul-out sites because of the different factors affecting these processes. A generalised linear mixed model framework was developed to capture the longitudinal nature of the data and the repeated measures across individuals. Despite seasonal variability in the number of seals counted at haul-out sites, the model generated estimates of abundance, with an overall mean of 846 (95% CI: 767 to 979). The methodology shows the value of using count and telemetry data collected concurrently for estimating absolute abundance, information that is essential to assess interactions between predators, fish stocks and fisheries.Publisher PDFPeer reviewe

A Scalable Middleware Solution for Advanced Wide Area Web Services

To alleviate scalability problems in the Web, many researchers concentrate on how to incorporate advanced caching and replication techniques. Many solutions incorporate object-based techniques. In particular, Web resources are considered as distributed objects offering a well-defined interface. We argue that most proposals ignore two important aspects. First, there is little discussion on what kind of coherence should be provided. Proposing specific caching or replication solutions makes sense only if we know what coherence model they should implement. Second, most proposals treat all Web resources alike. Such a one-size-fits-all approach will never work in a wide-area system. We propose a solution in which Web resources are encapsulated in physically distributed shared objects. Each object should encapsulate not only state and operations, but also the policy by which its state is distributed, cached, replicated, migrated, etc

Deployment of collaborative Web Caching with Active Networks

International audienceDeploying ”distributed intelligence” inside the network through the help of collaborative caches is a difficult task. This paper focus on the design of new collaborative web caches protocols through the help of active networks. These protocols have been implemented within the high performance Tamanoir[6] execution environment. First experiments on local platform are presented

Acculturation and the acceptance of the Genocide Convention

This article contributes to the burgeoning literature on why states ratify human rights treaties. It first analyses why Ireland, the United Kingdom and the United States did not initially ratify or accede to the 1948 Genocide Convention, and then explores why the three countries eventually did accept it, 20–40 years after it was approved by the United Nations General Assembly. The extent to which material costs and benefits, the logic of appropriateness, and acculturation played a role in each of the three cases is assessed. Acculturation is particularly evident in the Irish case, but it also helps to explain the UK and US acceptance of the Convention