Survivability of Deterministic Dynamical Systems

The notion of a part of phase space containing desired (or allowed) states of a dynamical system is important in a wide range of complex systems research. It has been called the safe operating space, the viability kernel or the sunny region. In this paper we define the notion of survivability: Given a random initial condition, what is the likelihood that the transient behaviour of a deterministic system does not leave a region of desirable states. We demonstrate the utility of this novel stability measure by considering models from climate science, neuronal networks and power grids. We also show that a semi-analytic lower bound for the survivability of linear systems allows a numerically very efficient survivability analysis in realistic models of power grids. Our numerical and semi-analytic work underlines that the type of stability measured by survivability is not captured by common asymptotic stability measures.Comment: 21 pages, 6 figure

Using court reports to enhance knowledge of sexual abuse in sport: A Norwegian case study

Copyright @ 2013 The authorsSport scientists face difficulties in gaining access to data on sexual abuse in sport through conventional research sources and also in verifying media reports of such cases. One potential alternative source of data is court reports. The study reported here used a small number of court reports to examine issues confronting those researching sexual abuse in sport. Two questions were investigated: What do the court reports tell us about the perpetrators and their abuse strategies? How useful is content analysis of court reports for acquiring more knowledge about sexual abuse cases in sport? Data were drawn from electronic searches of the Norwegian Lovdata (Lawdata) website. 15 sport-based cases were revealed by the searches and then subjected to content analysis, both within- and cross-case. The findings confirm previous studies in relation to the perpetrator strategies and the absence of any perpetrator stereotype. The article concludes that court reports provide one valuable, yet still incomplete, source of information against which to test our understanding of sexual abuse in sport and develop abuse prevention measure

Aspects of precommercial thinning in heterogeneous forests in southern Sweden

The overall objective of the work underlying this thesis was to suggest and evaluate possible strategies for the tending of young heterogeneous stands of Norway spruce, Scots pine and birch in southern Sweden. Heterogeneity was defined as variation in species composition, height distribution and spatial arrangement of the trees. The influence of stand density after precommercial thinning and timing of thinning on the diameter of the thickest branch was studied for naturally regenerated Scots pine. The branch diameter was found to decrease with increasing number of remaining stems after precommercial thinning. However, leaving very dense stands (> 3000 stems ha-1) resulted only in a minor reduction of the branch diameter. Late precommercial thinning, compared to early, reduced the branch diameter. The influence of the precommercial thinning regime on the crown ratio (living crown length/tree height) was also analysed. To be able to simulate the influence of different management options on the development of the young forest, single-tree growth models was developed for Scots pine, Norway spruce and birch. Height growth and diameter was estimated as a function of tree height, stand and site variables. Growth reduction due to competition was estimated using individual, distance independent indices as well as expressions of the overall stand density. In the third study the influence of stand structure after precommercial thinning on the development of mixtures between Norway spruce and silver birch was simulated. The aim was to identify mixtures that allowed both species to develop well until the first commercial thinning. By leaving birches with an average height slightly greater than spruce at precommercial thinning, a large proportion of competitive birches were available at first commercial thinning, at the same time as the relative diameter distribution of spruce in the mixture was equal to that of a pure spruce stand of the same density. The height difference between the species as well as the species proportion had a decisive impact on volume production. In the fourth study different precommercial thinning strategies were identified and applied to a heterogeneous stand including Scots pine, Norway spruce and birch. Stand development and economical returns over a rotation was estimated using a set of empirical models. The aim of the long-term strategies was: (i) a conifer dominated stand with focus on high production, (ii) a conifer dominated stand with focus on high timber quality, (iii) to preserve the heterogeneous stand structure, (iv) a mosaic pattern by tree species, (v) to reduce the precommercial thinning cost, without jeopardizing the future stand development. The difference in total volume production was found to be relatively small between the strategies. The lowest production was found for the strategies promoting species mixture at tree level (iii) and group level (iv). The net present value was highest for the strategy aiming at high production (ii) and lowest for the strategy aiming at preserved heterogeneity (iii). The minimal precommercial thinning (v) was a less profitable alternative, mainly because of an expensive first commercial thinning. Differences in timber quality were not considered in the simulations. The case study illustrates the possibilities for influencing the structure of a heterogeneous stand through precommercial thinning, as well as the limitations imposed by the initial stand structure

Participatory design and participatory development: a comparative review

This paper examines literature in the twin domains of participatory interactive systems design and participatory approaches to international development. As interactive systems are increasingly promoted as a possible means of achieving international development goals, designers generally agree that participatory design approaches should be applied. However, review of the literature reveals that these two different traditions have more complex relationships, and questions must be asked about: the aims of participation, the forms of participation that are being advocated, and the skills and strategies required of practitioners. The findings suggest that successful integration of participatory interactive systems design into development will require careful reflection on the nature of development and the approaches adopted.</p

Survivability : A Unifiying Concept for the Transient Resilience of Deterministic Dynamical Systems

16 pagesNon peer reviewedPreprin

The Issue of Tourist Accommodation in the Scandinavian Journal of Hospitality and Tourism

The aim of the study is to analyze the contents of the articles published in the Scandinavian Journal of Hospitality and Tourism with special attention paid to texts describing tourist accommodation in its broadest sense. The list of references was collected in a survey of Taylor & Francis Online1 which includes online editions of the journal

Species-specific forest variable estimation using non-parametric modeling of multi-spectral photogrammetric point cloud data

The recent development in software for automatic photogrammetric processing of multispectral aerial imagery, and the growing nation-wide availability of Digital Elevation Model (DEM) data, are about to revolutionize data capture for forest management planning in Scandinavia. Using only already available aerial imagery and ALS-assessed DEM data, raster estimates of the forest variables mean tree height, basal area, total stem volume, and species-specific stem volumes were produced and evaluated. The study was conducted at a coniferous hemi-boreal test site in southern Sweden (lat. 58° N, long. 13° E). Digital aerial images from the Zeiss/Intergraph Digital Mapping Camera system were used to produce 3D point-cloud data with spectral information. Metrics were calculated for 696 field plots (10 m radius) from point-cloud data and used in k-MSN to estimate forest variables. For these stands, the tree height ranged from 1.4 to 33.0 m (18.1 m mean), stem volume from 0 to 829 m3 ha-1 (249 m3 ha-1 mean) and basal area from 0 to 62.2 m2 ha-1 (26.1 m2 ha-1 mean), with mean stand size of 2.8 ha. Estimates made using digital aerial images corresponding to the standard acquisition of the Swedish National Land Survey (Lantmäteriet) showed RMSEs (in percent of the surveyed stand mean) of 7.5% for tree height, 11.4% for basal area, 13.2% for total stem volume, 90.6% for pine stem volume, 26.4 for spruce stem volume, and 72.6% for deciduous stem volume. The results imply that photogrammetric matching of digital aerial images has significant potential for operational use in forestry

UCL DAF (Data Audit Framework) Pilot: final report

The UCL DAF (Data Audit Framework) pilot implementation project was funded by JISC for a period of seven months (August 2008-March 2009) to trial the implementation of the DAF methodology at UCL

Growth allocation and stand structure in Norway spruce stands

This thesis is based on analyses of permanent sample plot data gathered over periods of 10-34 years from an experiment in which a wide range of thinning regimes, and thinnings combined with N-fertilisation, were applied to 25 even-aged Norway spruce (Picea abies (L.) Karst.) stands in southern Sweden (56-63 No). At the start of the experiment, before the first thinning, the dominant height was 12-18 m. The overall objective was to evaluate the extent to which growth allocation along the bole and the stand structure of Picea abies stands can be controlled by different silvicultural regimes. To do this the data were used in four studies to evaluate the impact of: thinning and N-fertilisation on stem form and taper (Study I); different thinning regimes on the removal and growth in the diameter at breast height (DBH) of individual stems (Studies II and III); and the thinning regimes on the growth in mean DBH of four classes of the largest stems by DBH ha 1 (Study IV). The studies (ii) and (iii) form a growth model. In stands subjected to different thinning regimes, one model predicts which individual trees will remain at future points in time and an associated model predicts the future DBH of the remaining stems. Separate models were developed for stands thinned from below, stands thinned from above and unthinned stands. In Study IV the actual and genuine increases in the arithmetic mean DBH of the 100, 200, 300 and 400 largest stems by DBH ha 1 associated with six different thinning regimes in periods up to 35 years were compared to the corresponding stems in unthinned stands. The goals of achieving rapid diameter growth and low stem tapering cannot be attained simultaneously as heavy thinnings cause increased tapering, and thus silvicultural regimes must reflect a compromise between these and other production objectives. Trees in thinned and N-fertilised stands had the same taper as trees in equally thinned, unfertilised stands. Heavy thinnings from below promote high frequencies of thick stems and extra heavy thinnings promote high frequencies of extra thick stems. Thinning from above (or no thinnngs) may be an alternative to thinning from below in situations where a main crop consisting of moderately thick stems would be regarded as a satisfactory outcome. The actual mean DBH of larger stems can be increased, compared to the corresponding stems in unthinned stands, by up to 2.6 mm per year if extra heavy thinnings are carried out. The biological response to thinning of thick stems is influenced by the thinning intensity but not by the thinning method. The variation in DBH increases over time but increases more in stands thinned from above and unthinned stands than in stands thinned from below

Male-biased operational sex ratios and the Viking phenomenon : an evolutionary anthropological perspective on Late Iron Age Scandinavian raiding

Acknowledgements We would like to thank Laura Whitehouse, John Carman, Oliver Grimm, Julie Lund, Bjørnar Olsen, two anonymous reviewers, and the editor for their comments and suggestions on earlier versions of this paper. We also thank Alex Woolf for providing us with a copy of his forthcoming article on the Vikings in Ireland. Lastly, we are grateful to Luke Glowacki, Shane McFarlane, and Ryan Schacht for their insights about raiding and OSRs. Needless to say, all remaining errors are our own. Funding BR and MC are supported by the Social Sciences and Humanities Research Council of Canada through a Partnership Grant (895-2011-1009) awarded to the Cultural Evolution of Religion Research Consortium (www.ubc/hecc/cerc). MC is also supported by the Canada Research Chairs Program, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, and Simon Fraser University. NP is supported by a Swedish Research Council grant for "The Viking Phenomenon" project (2015-00466).Peer reviewedPublisher PD