Detection of fine-scale relationships between species composition and biomass in grassland
In: Community ecology: CE ; interdisciplinary journal reporting progress in community and population studies, Band 2, Heft 2, S. 221-230
ISSN: 1588-2756
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In: Community ecology: CE ; interdisciplinary journal reporting progress in community and population studies, Band 2, Heft 2, S. 221-230
ISSN: 1588-2756
In: Ecotoxicology and environmental safety: EES ; official journal of the International Society of Ecotoxicology and Environmental safety, Band 65, Heft 1, S. 67-73
ISSN: 1090-2414
In: Terrorism and political violence, Band 36, Heft 4, S. 409-424
ISSN: 1556-1836
In: Periodica polytechnica. Social and management sciences, Band 25, Heft 2, S. 108
ISSN: 1587-3803
This paper addresses the background variables influencing the disabled persons' motivation to work. Data collection was carried out in Hungary by experts analyzing the change of capability to work on a nationally representative sample. This allows us to highlight also the regional differences, because the motivational status sharply reflected this geographical impact. Besides the socio-economical status, not only motivational readiness was studied, but also factors responsible for cognitive and emotional immunity. Points of intervention were also identified, where the motivation processes could be catalyzed. The aim of this paper is to provide a concise summary of results, to give tentative interpretations and finally to identify practical intervention possibilities to increase handicapped persons' motivation to work in Hungary.
In: Community ecology: CE ; interdisciplinary journal reporting progress in community and population studies, Band 7, Heft 2, S. 133-141
ISSN: 1588-2756
In: Land use policy: the international journal covering all aspects of land use, Band 80, S. 430-438
ISSN: 0264-8377
In: Community ecology: CE ; interdisciplinary journal reporting progress in community and population studies, Band 2, Heft 2, S. 145-159
ISSN: 1588-2756
In: Europas Osten im 20. Jahrhundert Band/Volume 9
Funding Information: YM, H-HJ, JT, and JK are thankful for the hospitality of Aalto University. This research used computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science. Publisher Copyright: © Copyright © 2021 Murase, Jo, Török, Kertész and Kaski. ; Interactions between humans give rise to complex social networks that are characterized by heterogeneous degree distribution, weight-topology relation, overlapping community structure, and dynamics of links. Understanding these characteristics of social networks is the primary goal of their research as they constitute scaffolds for various emergent social phenomena from disease spreading to political movements. An appropriate tool for studying them is agent-based modeling, in which nodes, representing individuals, make decisions about creating and deleting links, thus yielding various macroscopic behavioral patterns. Here we focus on studying a generalization of the weighted social network model, being one of the most fundamental agent-based models for describing the formation of social ties and social networks. This generalized weighted social network (GWSN) model incorporates triadic closure, homophilic interactions, and various link termination mechanisms, which have been studied separately in the previousworks. Accordingly, the GWSN model has an increased number of input parameters and the model behavior gets excessively complex, making it challenging to clarify the model behavior. We have executed massive simulations with a supercomputer and used the results as the training data for deep neural networks to conduct regression analysis for predicting the properties of the generated networks from the input parameters. The obtained regression model was also used for global sensitivity analysis to identify which parameters are influential or insignificant. We believe that this methodology is applicable for a large class of complex network models, thus opening the way for more realistic quantitative agent-based modeling. ; Peer reviewed
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In: Kommune: Forum für Politik, Ökonomie, Kultur, Band 16, Heft 5, S. 35-51
ISSN: 0723-7669
This is the final version. Available on open access from Nature Research via the DOI in this record ; Data availability: Data tenure was controlled by a non-disclosure agreement between the data owner and the research group. The access for the same can be requested by email to the corresponding author. ; Code availability: ABM simulation and parameter calibration codes have been written in Python and have been reposited at https://github.com/bokae/spatial_difusion. All other codes to produce the results have been written in R. Tese latter codes are available upon request at the corresponding author. ; The urban–rural divide is increasing in modern societies calling for geographical extensions of social influence modelling. Improved understanding of innovation diffusion across locations and through social connections can provide us with new insights into the spread of information, technological progress and economic development. In this work, we analyze the spatial adoption dynamics of iWiW, an Online Social Network (OSN) in Hungary and uncover empirical features about the spatial adoption in social networks. During its entire life cycle from 2002 to 2012, iWiW reached up to 300 million friendship ties of 3 million users. We find that the number of adopters as a function of town population follows a scaling law that reveals a strongly concentrated early adoption in large towns and a less concentrated late adoption. We also discover a strengthening distance decay of spread over the life-cycle indicating high fraction of distant diffusion in early stages but the dominance of local diffusion in late stages. The spreading process is modelled within the Bass diffusion framework that enables us to compare the differential equation version with an agent-based version of the model run on the empirical network. Although both model versions can capture the macro trend of adoption, they have limited capacity to describe the observed trends of urban scaling and distance decay. We find, however that incorporating adoption thresholds, defined by the fraction of social connections that adopt a technology before the individual adopts, improves the network model fit to the urban scaling of early adopters. Controlling for the threshold distribution enables us to eliminate the bias induced by local network structure on predicting local adoption peaks. Finally, we show that geographical features such as distance from the innovation origin and town size influence prediction of adoption peak at local scales in all model specifications. ; Rosztoczy Foundation ; Eötvös Fellowship of the Hungarian State ; National Research, Development and Innovation Office ; Royal Society ; British Academy ; Academy of Medical Sciences ; European Union Horizon 2020 ; Hungarian Scientific Research Fund
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Interactions between humans give rise to complex social networks that are characterized by heterogeneous degree distribution, weight-topology relation, overlapping community structure, and dynamics of links. Understanding these characteristics of social networks is the primary goal of their research as they constitute scaffolds for various emergent social phenomena from disease spreading to political movements. An appropriate tool for studying them is agent-based modeling, in which nodes, representing individuals, make decisions about creating and deleting links, thus yielding various macroscopic behavioral patterns. Here we focus on studying a generalization of the weighted social network model, being one of the most fundamental agent-based models for describing the formation of social ties and social networks. This generalized weighted social network (GWSN) model incorporates triadic closure, homophilic interactions, and various link termination mechanisms, which have been studied separately in the previous works. Accordingly, the GWSN model has an increased number of input parameters and the model behavior gets excessively complex, making it challenging to clarify the model behavior. We have executed massive simulations with a supercomputer and used the results as the training data for deep neural networks to conduct regression analysis for predicting the properties of the generated networks from the input parameters. The obtained regression model was also used for global sensitivity analysis to identify which parameters are influential or insignificant. We believe that this methodology is applicable for a large class of complex network models, thus opening the way for more realistic quantitative agent-based modeling.
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In: Annales mathematicae et informaticae: international journal for mathematics and computer science, Band 51, S. 41-52
ISSN: 1787-6117
Although many climate research experiments are providing valuable data, long-term measurements are not always affordable. In the last decades, several facilities have secured long-term experiments, but few studies have incorporated spatial and scale effects. Most of them have been implemented in experimental agricultural fields but none for ecological studies. Scale effects can be assessed using remote sensing images from space or airborne platforms. Unmanned aerial vehicles (UAVs) are contributing to an increased spatial resolution, as well as becoming the intermediate scale between ground measurements and satellite/airborne image data. In this paper we assess the applicability of UAV-borne multispectral images to provide complementary experimental data collected at point scale (field sampling) in a long-term rain manipulation experiment located at the Kiskun Long-Term Socio-Ecological Research (LTSER) site named ExDRain to assess the effects on grassland vegetation. Two multispectral sensors were compared at different scales, the Parrot Sequoia camera on board a UAV and the portable Cropscan spectroradiometer. The NDVI values were used to assess the effect of plastic roofs and a proportional reduction effect was found for Sequoia-derived NDVI values. Acceptable and significant positive relationships were found between both sensors at different scales, being stronger at Cropscan measurement scale. Differences found at plot scale might be due to heterogeneous responses to treatments. Spatial variability analysis pointed out a more homogeneous response for plots submitted to severe and moderate drought. More investigation is needed to address the possible effect of species abundance on NDVI at plot scale contributing to a more consistent representation of ground measurements. The feasibility of carrying out systematic UAV flights coincident or close to ground campaigns will certainly reveal the consistency of the observed spatial patterns in the long run. ; This research was funded by the European Union's Horizon 2020 Research and Innovation Program under grant agreement No. 654359 (eLTER Horizon 2020 project). Gy. K-D. was supported by the National Research, Development and Innovation Fund (NRDI Fund) of Hungary (Nos. K112576, K129068) ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI) ; Peer reviewed
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