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Keywords: les, tržne razmere, les
Published in DiRROS: 11.12.2024; Views: 84; Downloads: 25
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Keywords: gozdovi, gozdarstvo, epidemija, Covid-19, lastniki gozdov, izpad dohodka, finančno nadomestilo, odkup lesa
Published in DiRROS: 11.12.2024; Views: 87; Downloads: 25
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Keywords: gozdovi, gozdarstvo, epidemija, Covid-19, lastniki gozdov, sanitarna sečnja, finančno nadomestilo, odkup lesa
Published in DiRROS: 11.12.2024; Views: 88; Downloads: 29
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Abstract: Early detection and rapid response are essential to deal effectively with new introductions of invasive alien species (IAS). Citizen science platforms for opportunistic recording of species are increasingly popular, and there is potential to harvest their data for early detection of IAS, but this has not been tested. We evaluated the potential of data from existing citizen science platforms for early detection of IAS by obtaining 687 first records of species from 30 European countries where there was both an official first record (i.e. published in scientific literature or by a government agency) and a record in a citizen science platform. We tested how the difference between the two (time lag) was related to species traits, popularity in citizen science platforms, public and research attention and regulatory status. We found that for 50% of the time lag records, citizen science platforms reported IAS earlier than or in the same year as the official databases. Although we cannot determine causality (the first official record could have been from a citizen science platform, or contemporaneous with it), this demonstrates that citizen science platforms are effective for IAS early detection. Time lags were largely affected by species traits. Compared with official records, vertebrates were more likely to have earlier records on citizen science platforms, than plants or invertebrates. Greater popularity of the IAS in citizen science platforms and its observation in neighbouring countries resulted in earlier citizen science reporting. In contrast, inclusion in the EU priority list resulted in earlier official recording, reflecting the efficacy of targeted surveillance programmes. However, time lags were not affected by the overall activity of citizen platforms per country. Synthesis and applications. Multi-species citizen science platforms for reporting nature sightings are a valuable source of information on early detection of IAS even though they are not specifically designed for this purpose. We recommend that IAS surveillance programmes should be better connected with citizen science platforms, including greater acknowledgement of the role of citizen scientists and better data flow from smaller citizen science initiatives into global databases, to support efficient early detection.
Keywords: invasive species, citizen science, early detection
Published in DiRROS: 11.12.2024; Views: 85; Downloads: 39
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Abstract: Drawing a graph in the plane with as few crossings as possible is one of the central problems in graph drawing and computational geometry. Another option is to remove the smallest number of vertices or edges such that the remaining graph can be drawn without crossings. We study both problems in a book-embedding setting for ordered graphs, that is, graphs with a fixed vertex order. In this setting, the vertices lie on a straight line, called the spine, in the given order, and each edge must be drawn on one of several pages of a book such that every edge has at most a fixed number of crossings. In book embeddings, there is another way to reduce or avoid crossings; namely by using more pages. The minimum number of pages needed to draw an ordered graph without any crossings is its (fixed-vertex-order) page number. We show that the page number of an ordered graph with $n$ vertices and $m$ edges can be computed in $2^m \cdot n^{{\mathcal O}(1)}$ time. An ${\mathcal O}(\log n)$-approximation of this number can be computed efficiently. We can decide in $2^{{\mathcal O}(d \sqrt{k} \log (d+k))} \cdot n^{{\mathcal O}(1)}$ time whether it suffices to delete $k$ edges of an ordered graph to obtain a $d$-planar layout (where every edge crosses at most $d$ other edges) on one page. As an additional parameter, we consider the size $h$ of a hitting set, that is, a set of points on the spine such that every edge, seen as an open interval, contains at least one of the points. For $h = 1$, we can efficiently compute the minimum number of edges whose deletion yields fixed-vertex-order page number $p$. For $h > 1$, we give an XP algorithm with respect to $h+p$. Finally, we consider spine+t-track drawings, where some but not all vertices lie on the spine. The vertex order on the spine is given; we must map every vertex that does not lie on the spine to one of $t$ tracks, each of which is a straight line on a separate page, parallel to the spine. In this setting, we can minimize in $2^n \cdot n^{{\mathcal O}(1)}$ time either the number of crossings or, if we disallow crossings, the number of tracks.
Keywords: ordered graphs, book embedding, edge deletion, d-planar, hitting set
Published in DiRROS: 10.12.2024; Views: 77; Downloads: 38
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