607 research outputs found

    Research in emerging fields: Who takes the lead?.

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    In the present piece we study research performance and collaboration of the European Union and the most active countries in emerging topics that have been identified in a dynamic cluster analysis of selected Web of Science Subject Categories in the period 1999-2008.

    Using noun phrases extraction for the improvement of hybrid clustering with text- and citation-based components. The example of “Information Systems Research”

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    The hybrid clustering approach combining lexical and link-based similarities suffered for a long time from the different properties of the underlying networks. We propose a method based on noun phrase extraction using natural language processing to improve the measurement of the lexical component. Term shingles of different length are created form each of the extracted noun phrases. Hybrid networks are built based on weighted combination of the two types of similarities with seven different weights. We conclude that removing all single term shingles provides the best results at the level of computational feasibility, comparability with bibliographic coupling and also in a community detection application

    Traces of prior art. An analysis of non-patent references found in patent documents.

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    Research in the area of innovation has pointed out the relevance of conceiving innovation as processes in which a multitude of actors and a variety of interactions play a role. Integrative notions like (national) innovations systems, (techno-scientific) networks, or the triple helix metaphor, have been widely accepted as relevant to grasp the complexities entailed. This development highlights the need for indicators that mirror the dynamics involved. This contribution presents an in-depth examination of the role of 'Non-Patent references', found in patents. After examining the occurrence of these references in the USPTO and EPO patent systems, the precise nature of these references is delineated by means of a systematic content analysis of two samples of non-patent references (n=10.000). Our observations reveal the relevance of 'non-patent references' for developing indicators to depict the proximity of technological and scientific developments. Application areas, limitations and directions for future research are discussed.Academic investors; Field; Industry; Knowledge; Knowlegde interactions; Research; University-industry relations; Working; Area; Innovation; Processes; Innovations; Systems; Networks; Triple-helix; Complexity; Indicators; Dynamics; Patents;

    Improved lexical similarities for hybrid clustering through the use of noun phrases extraction

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    Clustering of hybrid document networks combining citation based links with lexical similarities suffered for a long time from the different properties of these underlying networks. In this paper we evaluate different processing options of noun phrases extracted from abstracts using natural language processing to improve the measurement of the lexical component. Term shingles of different length are created from each of the extracted noun phrases. We discuss twenty different extraction-shingling scenarios and compare their results. Some scenarios show no improvement compared with the previously used single term lexical approach used so far. But when all single term shingles are removed from the dataset the lexical network has properties which are comparable with those from a bibliographic coupling based network. Next, hybrid networks are built based on weighted combination of the two types of similarities with seven different weights. We demonstrate that removing all single term shingles provides the best results at the level of computational feasibility, comparability with bibliographic coupling and also in a community detection application

    Decentralized linked open data in constrained wireless sensor networks

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    Data generated by sensors in Internet of Things ecosystems contains lots of valuable information, which is often not used to its full potential. This is mainly due to the fact that data is stored in proprietary storages and formats. Manufacturers of sensor devices often offer closed platforms to view and manage the data, which limits their reusability. Moreover, questions start to raise about true data ownership over data generated from monitoring our everyday lives. In order to overcome these issues several initiatives have emerged in the past to hand over data to the rightful owner. One of these initiatives is Solid, currently focusing on socially linked data. However, never before did one apply the Solid principles to Internet of Things data. Therefore, in this paper, a novel approach is presented where sensor data is handled from sensor to storage using open data formats and standards to ensure interoperability and reusability. It is shown that combining existing concepts can be helpful in designing decentralized Internet of Things data storages, on top of which data can be incorporated into the Linked Open Data cloud. This has been done by comparing the overhead of a regular approach, using Linked Open Data concepts on top of a sensor device, to an approach that was optimized for device management in constrained Internet of Things networks

    Woody plant communities of isolated Afromontane cloud forests in Taita Hills, Kenya

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    In the Taita Hills in southern Kenya, remnants of the original Afromontane forest vegetation are restricted to isolated mountain peaks. To assess the level of degradation and the need for forest restoration, we examined how forest plant communities and their indicator species vary between and within remnant patches of cloud forest. We used ordinal abundance data to compare plant communities in eight forest fragments. We also analyzed data on the diversity and abundance of trees in 57 0.1 ha plots to compare tree communities within and between the largest two of these fragments, Ngangao (120 ha) and Mbololo (220 ha). The extant vegetation of the Taita Hills at landscape scale consists of secondary moist montane to intermediate montane forest. There was a high species dissimilarity between fragments (69%). Variation in species composition coincided with an abiotic gradient related to elevation. At plot level, secondary successional species and species of forest edges were most abundant and most frequent. Inferred clusters of plots almost entirely coincided with the two forest fragments. Indicator species associated with forest margins and gaps were more frequent in the smaller of the two forest fragments, while indicators for the larger fragment were more typical for less disturbed moist forest. Abiotic site variability but also different levels of disturbance determine site-specific variants of the montane forest. Conservation efforts should not only focus on maintaining forest quantity (size), but also on forest quality (species composition). Late-successional rainforest species are underrepresented in the woody plant communities of the Taita Hills and assisting restoration of viable populations of cloud forest climax tree species is urgently needed

    Potential tree species extinction, colonization and recruitment in Afromontane forest relicts

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    Tree species regeneration determines future forest structure and composition, but is often severely hampered in small forest relicts. To study succession, long-term field observations or simulation models are used but data, knowledge or resources to run such models are often scarce in tropical areas. We propose and implement a species accounting equation, which includes the co-occurring events extinction, colonization and recruitment and which can be solved by using data from a single inventory. We solved this species accounting equation for the 12 remaining Afromontane cloud forest relicts in Taita Hills, Kenya by comparing the tree species present among the seedling, sapling and mature tree layer in 82 plots. A simultaneous ordination of the seedling, sapling and mature tree layer data revealed that potential species extinctions, colonizations and recruitments may induce future species shifts. On landscape level, the potential extinction debt amounted to 9% (7 species) of the regional species pool. On forest relict level, the smallest relicts harbored an important proportion of the tree species diversity in the regeneration layer. The average potential recruitment credit, defined as species only present as seedling or sapling, was 3 and 6 species for large and small forest relicts, while the average potential extinction debt was 12 and 4 species, respectively. In total, both large and small relicts are expected to lose approximately 20% of their current local tree species pool. The species accounting equations provide a time and resource effective tool and give an improved understanding of the conservation status and possible future succession dynamics of forest relicts, which can be particularly useful in a context of participatory monitoring

    Cross-scale modelling of transpiration from stomata via the leaf boundary layer

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    Background and Aims Leaf transpiration is a key parameter for understanding land surface-climate interactions, plant stress and plant structure-function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2-5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5-10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be significantly erroneous because they do not account for microscopic stomata, but instead assume a uniform distribution of evaporation such as found for a fully-wet leaf. The model output can be used to correct or upgrade existing BLCs or to feed into higher-scale models, for example within a multiscale framewor
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