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  • 1
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  ISPRS International Journal of Geo-Information Vol. 11, No. 4 ( 2022-03-26), p. 224-
    In: ISPRS International Journal of Geo-Information, MDPI AG, Vol. 11, No. 4 ( 2022-03-26), p. 224-
    Abstract: Geometrically induced topology plays a major role in applications such as simulations, navigation, spatial or spatio-temporal analysis and many more. This article computes geometrically induced topology useful for such applications and extends previous results by presenting the unpublished used algorithms to find inner disjoint (d+1)-dimensional simplicial complexes from a set of intersecting d-dimensional simplicial complexes which partly shape their B-Reps (Boundary Representations). CityGML has been chosen as the input data format for evaluation purposes. In this case, the input data consist of planar segment complexes whose triangulated polygons serve as the set of input triangle complexes for the computation of the tetrahedral model. The creation of the volumetric model and the computation of its geometrically induced topology is partly parallelized by decomposing the input data into smaller pices. A robustness analysis of the implementations is given by varying the angular precision and the positional precision of the epsilon heuristic inaccuracy model. The results are analysed spatially and topologically, summarised and presented. It turns out that one can extract most, but not all, volumes and that the numerical issues of computational geometry produce failures as well as a variety of outcomes.
    Type of Medium: Online Resource
    ISSN: 2220-9964
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2655790-3
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  • 2
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2022
    In:  The Computer Journal Vol. 65, No. 2 ( 2022-02-14), p. 310-330
    In: The Computer Journal, Oxford University Press (OUP), Vol. 65, No. 2 ( 2022-02-14), p. 310-330
    Abstract: Space filling curves are widely used in computer science. In particular, Hilbert curves and their generalizations to higher dimension are used as an indexing method because of their nice locality properties. This article generalizes this concept to the systematic construction of $p$-adic versions of Hilbert curves based on special affine transformations of the $p$-adic Gray code and develops a scaled indexing method for data taken from high-dimensional spaces based on these new curves, which with increasing dimension is shown to be less space consuming than the optimal standard static Hilbert curve index. A measure is derived, which allows to assess the local sparsity of a dataset, and is tested on some real-world data.
    Type of Medium: Online Resource
    ISSN: 0010-4620 , 1460-2067
    RVK:
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1477172-X
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  • 3
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  ISPRS International Journal of Geo-Information Vol. 11, No. 10 ( 2022-10-20), p. 533-
    In: ISPRS International Journal of Geo-Information, MDPI AG, Vol. 11, No. 10 ( 2022-10-20), p. 533-
    Abstract: In order to perform topological queries on geographic data, it is necessary to first develop a topological access method (TOAM). Using the fact that any (incidence or other binary) relation produces a topology which includes the common usage of topology for spatial or spatiotemporal data, here, such a TOAM is developed on the basis of the previously applied concept of Property Graph used in order to manage topological information in data of any dimension, whether time dependent or not. As a matter of fact, it is necessary to have a TOAM in order to query such a graph, and also to have data which are topologically consistent in a certain sense. While the rendering of topological consistency was the concern of previous work, here, the aim is to develop a methodology which builds on this concept. In the end, an experimental test of this approach on a small city model is performed. It turned out that the Euler characteristic, a well-known topological invariant, can be helpful for the initial data validation. Practically, this present theoretical work is seen to be necessary in view of future innovative applications, e.g., in the context of city model simulations, including distributed geo-processing.
    Type of Medium: Online Resource
    ISSN: 2220-9964
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2655790-3
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  • 4
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2015
    In:  Proceedings of the National Academy of Sciences Vol. 112, No. 49 ( 2015-12-08), p. 15125-15129
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 49 ( 2015-12-08), p. 15125-15129
    Abstract: The search for simple principles underlying the complex architecture of ecological communities such as forests still challenges ecological theorists. We use tree diameter distributions—fundamental for deriving other forest attributes—to describe the structure of tropical forests. Here we argue that tree diameter distributions of natural tropical forests can be explained by stochastic packing of tree crowns representing a forest crown packing system: a method usually used in physics or chemistry. We demonstrate that tree diameter distributions emerge accurately from a surprisingly simple set of principles that include site-specific tree allometries, random placement of trees, competition for space, and mortality. The simple static model also successfully predicted the canopy structure, revealing that most trees in our two studied forests grow up to 30–50 m in height and that the highest packing density of about 60% is reached between the 25- and 40-m height layer. Our approach is an important step toward identifying a minimal set of processes responsible for generating the spatial structure of tropical forests.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2022
    In:  AStA Advances in Statistical Analysis Vol. 106, No. 3 ( 2022-09), p. 403-405
    In: AStA Advances in Statistical Analysis, Springer Science and Business Media LLC, Vol. 106, No. 3 ( 2022-09), p. 403-405
    Type of Medium: Online Resource
    ISSN: 1863-8171 , 1863-818X
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2277258-3
    detail.hit.zdb_id: 2276384-3
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  • 6
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2022
    In:  AStA Advances in Statistical Analysis Vol. 106, No. 3 ( 2022-09), p. 349-382
    In: AStA Advances in Statistical Analysis, Springer Science and Business Media LLC, Vol. 106, No. 3 ( 2022-09), p. 349-382
    Abstract: A pandemic poses particular challenges to decision-making because of the need to continuously adapt decisions to rapidly changing evidence and available data. For example, which countermeasures are appropriate at a particular stage of the pandemic? How can the severity of the pandemic be measured? What is the effect of vaccination in the population and which groups should be vaccinated first? The process of decision-making starts with data collection and modeling and continues to the dissemination of results and the subsequent decisions taken. The goal of this paper is to give an overview of this process and to provide recommendations for the different steps from a statistical perspective. In particular, we discuss a range of modeling techniques including mathematical, statistical and decision-analytic models along with their applications in the COVID-19 context. With this overview, we aim to foster the understanding of the goals of these modeling approaches and the specific data requirements that are essential for the interpretation of results and for successful interdisciplinary collaborations. A special focus is on the role played by data in these different models, and we incorporate into the discussion the importance of statistical literacy and of effective dissemination and communication of findings.
    Type of Medium: Online Resource
    ISSN: 1863-8171 , 1863-818X
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2277258-3
    detail.hit.zdb_id: 2276384-3
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  • 7
    In: Digestion, S. Karger AG, Vol. 89, No. 4 ( 2014), p. 310-318
    Abstract: 〈 b 〉 〈 i 〉 Background and Aims: 〈 /i 〉 〈 /b 〉 Despite increasingly sensitive and accurate blood tests to detect liver disease, liver biopsy remains very useful in patients with atypical clinical features and abnormal liver tests of unknown etiology. The aim was to determine those elevated laboratory liver parameters that cause the clinician to order a biopsy, and whether laboratory tests are associated with pathological findings on histology. 〈 b 〉 〈 i 〉 Methods: 〈 /i 〉 〈 /b 〉 504 patients with unclear hepatopathy, admitted to the outpatient clinic of a university hospital between 2007 and 2010, were analyzed with respect to laboratory results, clinical data, and the results of liver biopsies. 〈 b 〉 〈 i 〉 Results: 〈 /i 〉 〈 /b 〉 Aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) levels above the normal range significantly increased the likelihood of recommending a liver biopsy by 81% [OR with 95% CI 1.81 (1.21-2.71), p = 0.004] and 159% [OR with 95% CI 2.59 (1.70-3.93), p 〈 0.001], respectively. AST values above normal were associated with fibrosis (63 vs. 40% for normal AST, p = 0.010). Elevated ferritin levels pointed to a higher incidence of steatosis (48 vs. 10% for normal ferritin, p 〈 0.001) and inflammation (87 vs. 62% for normal ferritin, p = 0.004). 〈 b 〉 〈 i 〉 Conclusions: 〈 /i 〉 〈 /b 〉 Our results indicate that elevated AST and GLDH were associated with a greater likelihood of recommending liver biopsy. Elevated AST and ferritin levels were associated with steatosis, inflammation and fibrosis on liver biopsies. Thus, AST and ferritin may be useful non-invasive predictors of liver pathology in patients with unclear hepatopathy.
    Type of Medium: Online Resource
    ISSN: 0012-2823 , 1421-9867
    RVK:
    RVK:
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2014
    detail.hit.zdb_id: 1482218-0
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