1,728,204 research outputs found
Species-habitat associations in a northern temperate forest in China
No full textZhang, C., Zhao, Y., Zhao, X. & Gadow, K. v. 2012. Species-habitat associations in a northern temperate forest in China. Silva Fennica 46(4): 501-519. This contribution identifies species-habitat associations in a temperate forest in north-eastern China, based on the assumption that habitats are spatially autocorrelated and species are spatially aggregated due to limited seed dispersal. The empirical observations were obtained in a large permanent experimental area covering 660 x 320 m. The experimental area was subdivided into four habitat types using multivariate regression tree (MRT) analysis. According to an indicator species analysis, 38 of the 47 studied species were found to be significant indicators of the MRT habitat types. The relationships between species richness and topographic variables were found to be scale-dependent, while the great majority of the species shows distinct habitat-dependence. There are 188 potential species-habitat associations, and 114 of these were significantly positive or negative based on habitat randomization. We identified 139 significant associations using a species randomization. A habitat is not a closed system it may be both, either a sink or a source. Therefore, additional to the randomization, the Poisson Cluster Model (PCM) was applied. PCM considers the spatial autocorrelation of species and habitats, and thus appears to be more realistic than the traditional randomization processes. It identified only 37 associations that were significant. In conclusion, the deviation from the random process, i.e. the high degree of species spatial mingling may be explained by persistent immigration across habitats
Reproductive allocation of two dioecious Rhamnus species in temperate forests of northeast China
Full text linkCITATION: Wang, J., Zhang, C., Zhao, X., Von Gadow, K. 2014. Reproductive allocation of two dioecious Rhamnus species in temperate forests of northeast China. iForest, 7:25-32, doi:10.3832/ifor1020-007.The original publication is available at http://www.sisef.it/iforestWhen a plant increases resource allocation to reproduction from its limited reserves, the allocation to the other functions is reduced. Because of these trade-offs, differences in reproductive allocation are believed to result in relative differences in life history traits. Dioecious plants provide an excellent opportunity for detecting such possible trade-offs in resource allocation. This study aims to present a finding about the gender-based cost of reproductive allocation. The trade-off between reproduction and foliage biomass allocation was examined in Rhamnus davurica and Rhamnus schneideri at different modular levels (shoot/sub-branch, branch, and shrub/tree level). There were no intra-annual trade-offs between reproduction and foliage biomass in either sex of either species at shoot/sub-branch level, branch level and shrub level. Interannual trade-offs were detected in females for both species. Inter-annual trade-offs existed at all three different modular levels in R. schneideri females, while the evidence of inter-annual trade-offs was only detected at branch level in R. davurica females. At the population level, the sex ratio was female-biased in 2010, and it did not significantly deviate from 1:1 in 2011 in R. davurica. However, the sex ratios were significantly female-biased in both 2010 and 2011 in R. schneideri. This study show that the degree of autonomy of the different plant organs influences the trade-offs between reproduction and growth, which suggests a species- and sex-dependent modular autonomy.http://www.sisef.it/iforest/contents/?id=ifor1020-007Publisher's versio
Gated relational stacked denoising autoencoder with localized author embedding for global citation recommendation
No full textCitation recommendation is an effective and efficient way to facilitate authors finding desired references. This paper presents a novel neural network based model, called gated relational probabilistic stacked denoising autoencoder with localized author (GRSLA) embedding, for global citation recommendation task. Our model is comprised of two modules with different neural network architecture. For each citing and cited papers, we use a gated paper embedding module, which is extended from probabilistic stacked denoising autoencoder (PSDAE) by adding gated units, to obtain their paper vectors. The added gated units are able to utilize text information of cited paper to refine the vector representation of citing paper in multiple semantic levels. For an author in papers, we first apply topic model to obtain his/her semantic neighbors, and then use a localized author embedding (LAE) module to excavate author vector representation from semantic and explicit neighbors. Unlike most graph convolutional network (GCN) based methods, the LAE module is able to avoid computing global Laplacian in whole graph by taking limited neighbors. Moreover, the LAE module can also be stacked to absorb more neighbors, which makes our model have high extendibility. Based on the generation process of GRSLA, we also derive a learning algorithm of our model by maximum a posteriori (MAP) estimation. We conduct experiments on the AAN, DBLP and CORD-19 datasets, and the results show that GRSLA model works well than previous global citation recommendation methods
Diagnosis of active systems by semantic patterns
No full textA gap still exists between complex discrete-event systems (DESs) and the effectiveness of state-of-the-art diagnosis techniques, where faults are defined at component levels and diagnoses incorporate the occurrences of component faults. All these approaches to diagnosis are context-free, inasmuch diagnosis is anchored to components, irrespective of the context in which they are embedded. By contrast, since complex DESs are naturally organized in hierarchies of contexts, different diagnosis rules are to be defined for different contexts. Diagnosis rules are specified based on associations between context-sensitive faults and regular expressions, called semantic patterns. Since the alphabets of such regular expressions are stratified, so that the semantic patterns of a context is defined based on the interface symbols of its sub-contexts only, separation of concerns is achieved, and the expressive power of diagnosis is enhanced. This new approach to diagnosis is bound to seemingly contradictory but nonetheless possible scenarios: a DES can be normal despite the faulty behavior of a number of its components; also, it can be faulty despite the normal behavior of all its components
Temporalities and changing understandings of children's use of media
No full textThis chapter examines shifts in parents’ understanding of digital media, with a particular focus on their new insights on children’s use of media that came as a result of pandemic family life. With increases in children’s use of media and the new contexts introduced by the pandemic, parents reassessed previous rules and routines, observed more of what their children were doing with digital technologies, and subsequently reevaluated their understanding of the role of screen media in children’s lives. The chapter analyses findings from Australia, China, and the United States. It identifies three main changes in parents’ understanding of their children’s media use: greater distinctions between children’s purposes for using media, increased understanding of media content, and exacerbated worries about screen media. The chapter explains these changes by applying the lens of time and temporality. It argues that it was the parents’ understanding, experiences, and imaginaries of multiple forms of time during lockdowns that shaped parental attitudes towards screen media across the three countries
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