544,721 research outputs found

    From the axial line to the walked line: Evaluating the utility of commercial and user-generated street network datasets in space syntax analysis

    Get PDF
    Data availability, reliability and cost are some of the most constraining factors in space syntax analysis and wider commercial acceptance. In recent years user-created Volunteered Geographic Information (VGI) that is free to all via the Internet has gained wider acceptance and proven reliability (Haklay, 2010). Furthermore it has the property of being created by the people who inhabit the spaces being mapped; therefore it captures local knowledge and detail to a far greater degree than commercial mapping agencies. From a space syntax perspective it also relates more closely to the pedestrian network as it is used on foot and captures details of pedestrian routes through the urban fabric that other road-centric data sources ignore. This paper demonstrates the methodological approaches and analytic outcomes of a space syntax sensitivity analysis of Open Street Map (OSM) VGI road network data, the UK national mapping agency Ordnance Survey Integrated Transport Network (ITN) road data and a hand-drawn Axial map for four areas within the Greater London Region. The space syntax segment analysis was completed within the Depthmap application. The segment analysis was completed on the ITN model, OSM model and hand-drawn model separately and then it was carried out on a combined model of the ITN and OSM that integrated all the network elements from both. The integration and comparison of the network models was carried out through the usage of a new algorithm currently under development at University College London that identifies and extracts the differences between two line network datasets (Koukoletsos, forthcoming) and standard GIS processing techniques. The space syntax measures were evaluated on four areas in outer London that are the focus of the Adaptable Suburbs project at the Bartlett School of Graduate Studies. The analysis was carried out using length-weighted angular segment and choice analysis at radii 800m, 2000m and n (Turner, 2007). Comparative statistics were then generated for the areas to evaluate the analysis outcomes of the different network models. The London-wide network that was created through the combination of the OSM and ITN networks had a total length of 32,000km representing an increase of approximately 20% over the Ordnance Survey ITN network. The dramatic increase in network length alone demonstrates the divergent realities of the two mapping techniques and the representation of the world that they capture. It is anticipated that the sensitivity analysis will find that there was no significant difference in the global syntax values between the ITN and OSM and Axial models but at the local level the additional network segments for pedestrian routes within the OSM data will provide greater network accuracy and syntax values that model the reality on the ground better than the Ordnance Survey ITN model. Furthermore it captures potential pedestrian routes that are not present in the other data sets. The work carried out seeks to understand whether Volunteered Geographic Information is a viable alternative to official mapping sources when creating models for analysis of small urban areas. If this proves to be the case such data would provide not only a cost effective alternative to commercially produced data but indeed a more reliable network model for the analysis to be carried out. Open source geographic data have the capability to improve and enrich space syntax analysis whilst removing high price barriers that commercial data sources impose

    Synthesis and final recommendations on the development of a European Information System for Organic Markets. = Deliverable D6 of the European Project EISfOM QLK5-2002-02400

    Get PDF
    Executive summary European markets for organic products are growing rapidly, but the market information available in most European countries is woefully inadequate. Often only very basic data such as certified organic holdings and land area are reported, and sometimes not even individual crop areas or livestock numbers. Important market data, such as the amount of production, consumption, international trade or producer and consumer prices, do not exist in most European countries. In some European countries there are only rough estimates of the levels of production and consumption. There is no standardisation and data are seldom comparable. Furthermore, detailed information on specific commodities is missing. Hence, investment decisions are taken under conditions of great uncertainty. Policy evaluation, including periodic monitoring of the European Action Plan for Organic Food and Farming and RDP 2007-2013, will require many other data in addition to those regarding production structures and financial data that are already available, but obtaining this information would require a new EU-wide data collection and processing system (DCPS) to be put in place. The European Information System for Organic Markets (EISfOM) project is an EUfunded Concerted Action which has analysed and documented the current situation and proposed ways in which organic data collection and processing systems (DCPS) can be improved by means of: • improvement in the current situation of data collecting and processing systems for the organic sector • innovation in data collection and processing systems for the organic sector • integration of conventional and organic data collection and processing systems This report summarises the most relevant findings of the EISfOM project, which are analysed in the main project reports: Wolfert, S., Kramer, K. J., Richter, T., Hempfling, G., Lux. S. and Recke, G. (eds.) (2004). Review of data collection and processing systems for organic and conventional markets. EISfOM (QLK5-2002-02400) project deliverable submitted to European Commission. www.eisfom.org/publications. Recke, G., Hamm, U., Lampkin, N., Zanoli, R., Vitulano, S. and Olmos, S. (eds.) (2004a) Report on proposals for the development, harmonisation and quality assurance of organic data collection and processing systems (DCPS). EISfOM (QLK5-2002-02400) project deliverable submitted to European Commission. www.eisfom.org/publications. Recke, G., Willer, H., Lampkin, N. and Vaughan, A. (eds.) (2004b). Development of a European Information System for Organic Markets – Improving the Scope and Quality of Statistical Data. Proceedings of the 1st EISfOM European Seminar, Berlin, Germany, 26-27 April, 2004. Research Institute of Organic Agriculture (FiBL), Frick, Switzerland. www.eisfom.org/publications. Gleirscher, N., Schermer, M., Wroblewska, M. and Zakowska-Biemans, S. (2005) Report on the evaluation of the pilot case studies. EISfOM (QLK5-2002-02400) project deliverable submitted to European Commission. www.eisfom.org/publications. QLK5-2002-02400 European Information System for Organic Markets (EISfOM) D6 final report Rippin, M. and Lampkin, N. (eds.) (2005) Framework for a European Information System for Organic Markets. Unpublished report of the project European Information System for Organic Markets (EISfOM) (QLK5-2002-02400). Rippin, M., Willer, H., Lampkin, N., and Vaughan A. (2006). Towards a European Framework for Organic Market information, Proceedings of the 2nd EISfOM European Seminar, Brussels, November 10 and 11, 2005. Research Institute of Organic Agriculture (FiBL), Frick, Switzerland. www.eisfom.org/publications

    Centralized and distributed cognitive task processing in the human connectome

    Get PDF
    A key question in modern neuroscience is how cognitive changes in a human brain can be quantified and captured by functional connectomes (FC) . A systematic approach to measure pairwise functional distance at different brain states is lacking. This would provide a straight-forward way to quantify differences in cognitive processing across tasks; also, it would help in relating these differences in task-based FCs to the underlying structural network. Here we propose a framework, based on the concept of Jensen-Shannon divergence, to map the task-rest connectivity distance between tasks and resting-state FC. We show how this information theoretical measure allows for quantifying connectivity changes in distributed and centralized processing in functional networks. We study resting-state and seven tasks from the Human Connectome Project dataset to obtain the most distant links across tasks. We investigate how these changes are associated to different functional brain networks, and use the proposed measure to infer changes in the information processing regimes. Furthermore, we show how the FC distance from resting state is shaped by structural connectivity, and to what extent this relationship depends on the task. This framework provides a well grounded mathematical quantification of connectivity changes associated to cognitive processing in large-scale brain networks.Comment: 22 pages main, 6 pages supplementary, 6 figures, 5 supplementary figures, 1 table, 1 supplementary table. arXiv admin note: text overlap with arXiv:1710.0219

    A Review of the Enviro-Net Project

    Get PDF
    Ecosystems monitoring is essential to properly understand their development and the effects of events, both climatological and anthropological in nature. The amount of data used in these assessments is increasing at very high rates. This is due to increasing availability of sensing systems and the development of new techniques to analyze sensor data. The Enviro-Net Project encompasses several of such sensor system deployments across five countries in the Americas. These deployments use a few different ground-based sensor systems, installed at different heights monitoring the conditions in tropical dry forests over long periods of time. This paper presents our experience in deploying and maintaining these systems, retrieving and pre-processing the data, and describes the Web portal developed to help with data management, visualization and analysis.Comment: v2: 29 pages, 5 figures, reflects changes addressing reviewers' comments v1: 38 pages, 8 figure
    • …
    corecore