Habitat suitablity modelling in the New Forest National Park.

The New Forest National Park is a unique semi-natural landscape which contains many species and habitats which are rare and/or threatened. In order to effectively aid in the conservation of these species, particularly in the face of climate change, there is a requirement to know their habitat requirements and distributions within the New Forest. However, due to limited resources there are gaps in knowledge about this for many of these species. Habitat suitability modelling was carried out to suggest unsurveyed sites of potentially suitable habitat (and consequently higher likelihood of species occurrence) for selected species of high conservation concern (Chamaemelum nobile, Galium constrictum, Gladiolus illyricus, Hipparchia semele, Nemobius sylvestris, Pilularia globulifera, Plebejus argus and Poronia punctata). The performance of several modelling approaches was compared. Of the models based on the use of GIS spatial data, an approach requiring only species presence data (Ecological Niche Factor Analysis (ENFA)) was compared to approaches additionally requiring absence or pseudo-absence data (Generalised Linear Models (GLMs) and Generalised Additive Models (GAMs)). An additional approach that did not require GIS data, Bayesian Belief Network (BBN) modelling, was also used to incorporate finer-scale variables not available in GIS format. This relatively new approach to habitat suitability modelling was also used to predict the potential impact of climate change on the suitability of the habitats for the selected species. The evaluation results showed that the presence-absence GLM and GAM models out-performed the presence-only ENFA method, and that the use of pseudo-absences and automated stepwise variable selection proved effective for developing these models. Species with specialist habitat requirements tended to be modelled more accurately than more generalist species. The BBN models also achieved high evaluation values, and were particularly valuable in being able to provide a quantitative assessment of the potential impact of climate change on the selected species. Habitat suitability modelling at the scale of an individual predicted area of the size of the New Forest has so far been rare, as have predictions of climate change on specific species at this scale. However, the results of this research show that this can be a valuable approach to aid in management and conservation of species and their habitats in protected areas

Vannotea: A collaborative video indexing, annotation and discussion system for broadband networks

A number of research groups and software companies have developed digital annotation tools for textual documents, web pages, images, audio and video resources. By annotations we mean subjective comments, notes, explanations or external remarks that can be attached to a document or a selected part of a document without actually modifying the document. When a user retrieves a document, they can also download the annotations attached to it from an annotation server to view their peer’s opinions and perspectives on the particular document or to add, edit or update their own annotations. The ability to do this collaboratively and in real time during group discussions is of great interest to the educational, medical, scientific, cultural, defense and media communities. But it is extremely challenging technically and demands significant bandwidth, particularly for video documents. In this paper we describe a unique prototype application developed over the Australian GrangeNet broadband research network, which combines videoconferencing over access grid nodes with collaborative, real-time sharing of an application which enables the indexing, browsing, annotation and discussion of video content between multiple groups at remote locations

Revolutionaries and spies: Spy-good and spy-bad graphs

We study a game on a graph $G$ played by $r$ {\it revolutionaries} and $s$ {\it spies}. Initially, revolutionaries and then spies occupy vertices. In each subsequent round, each revolutionary may move to a neighboring vertex or not move, and then each spy has the same option. The revolutionaries win if $m$ of them meet at some vertex having no spy (at the end of a round); the spies win if they can avoid this forever. Let $\sigma(G,m,r)$ denote the minimum number of spies needed to win. To avoid degenerate cases, assume |V(G)|\ge r-m+1\ge\floor{r/m}\ge 1. The easy bounds are then \floor{r/m}\le \sigma(G,m,r)\le r-m+1. We prove that the lower bound is sharp when $G$ has a rooted spanning tree $T$ such that every edge of $G$ not in $T$ joins two vertices having the same parent in $T$. As a consequence, \sigma(G,m,r)\le\gamma(G)\floor{r/m}, where $\gamma(G)$ is the domination number; this bound is nearly sharp when $\gamma(G)\le m$. For the random graph with constant edge-probability $p$, we obtain constants $c$ and $c'$ (depending on $m$ and $p$) such that $\sigma(G,m,r)$ is near the trivial upper bound when $r<c\ln n$ and at most $c'$ times the trivial lower bound when $r>c'\ln n$. For the hypercube $Q_d$ with $d\ge r$, we have $\sigma(G,m,r)=r-m+1$ when $m=2$, and for $m\ge 3$ at least $r-39m$ spies are needed. For complete $k$-partite graphs with partite sets of size at least $2r$, the leading term in $\sigma(G,m,r)$ is approximately $\frac{k}{k-1}\frac{r}{m}$ when $k\ge m$. For $k=2$, we have \sigma(G,2,r)=\bigl\lceil{\frac{\floor{7r/2}-3}5}\bigr\rceil and \sigma(G,3,r)=\floor{r/2}, and in general $\frac{3r}{2m}-3\le \sigma(G,m,r)\le\frac{(1+1/\sqrt3)r}{m}$.Comment: 34 pages, 2 figures. The most important changes in this revision are improvements of the results on hypercubes and random graphs. The proof of the previous hypercube result has been deleted, but the statement remains because it is stronger for m<52. In the random graph section we added a spy-strategy resul

Mass accommodation coefficient measurements for HNO3, HCl and N2O5 on water, ice and aqueous sulfuric acid droplet surfaces

Preliminary results are reported of the direct measurement of accommodation coefficients for HNO3, N2O5 and HCl on water drops, aqueous sulfuric acid drops and ice particles. The heterogeneous chemistry of these species together with ClONO2 has been implicated in the ozone depletion observed in the Antarctic stratosphere during the spring in the last eight years. The most plausible chemical mechanism involves the removal of nitrogen oxide species via condensation on ice particles in polar stratospheric clouds resulting in a increase in the active chlorine species responsible for the ozone depletion. The observation of low NO2 and high ClO densities in the Antarctic stratosphere last summer appear to be consistent with such a mechanism