Calibration of Land Use Change Drivers in Support of Dynamic Urban Growth Modeling

The Land use Evolution and impact Assessment Model (LEAM) is a cellular urban dynamics model designed to simulate changing landscapes over space and time. One of the challenging problems in the LEAM model is calibrating the model results, and this study presents a step to calibration. The probability of land use change in each cell is determined by various factors including a cell’s proximity to development attractors, which are physical features that promote residential and commercial developments. This study presents a way to calculate a cell’s proximity to development attractors and converting the proximity to relative probability to help with LEAM calibration. The ten-county area in Illinois and Missouri, USA, around the City of St. Louis, was chosen as a study area. The results show general patterns of distributions of existing urban cells in terms of travel time to attractors. Furthermore, existing residential and commercial land uses show distinct spatial patterns for development. The adoption of this method has contributed to more realistic simulation of new developments in the study area

The Influences of Key Factors on the Consequences Following the Natural Gas Leakage from Pipeline

AbstractThe effects of the environmental dispersion (i.e. atmospheric stability, wind speed, temperature, humidity and ground roughness) and source release factors (i.e. pipeline diameter, length, pressure and release opening area) on the suffocation distance, flammable vapor cloud distance, overpressure distance and thermal radiation distance after the natural gas released from pipeline were evaluated and analyzed. The results show that all the environmental dispersion factors except humidity have an effect on the flammable vapor cloud distance. The more stable atmospheric condition, lower wind speed and smaller ground roughness lead to the longer flammable vapor cloud distance. The atmosphere temperature has a very limited influence on the flammable vapor cloud distance. The higher ambient temperature and larger humidity result in the longer downwind thermal radiation distance, while the atmospheric stability, wind speed and ground roughness nearly does not. All the four source release factors significantly influence the flammable vapor cloud distance and thermal radiation distance, which is due to the different release amount, release rate and initial momentum

Percutaneous nephrolithotripsy: C-arm CT with 3D virtual navigation in non-dilated renal collecting systems

PURPOSE:We aimed to evaluate the clinical superiority of using C-arm computed tomography (CT) to establish percutaneous nephrolithotripsy (PCNL) access for patients with non-dilated renal collecting systems.METHODS:From May 2014 to May 2015, 33 patients underwent C-arm CT-guided puncture to establish PCNL access after failed attempts of ultrasonography-guided nephrostomy. Technical success, procedure details, radiation exposure, complications, and stone-free rate were recorded.RESULTS:The technical success rate was 97% (32/33) with a mean puncture score of 4.5/5. Mean puncture, dilation, and fragmentation times were 17.9±6.0, 12.6±3.9, and 33.1±8.8 minutes, respectively. Mean radiation exposure was 4.8±2.1 mSv without serious complications. Stone-free rate was 93.8%.CONCLUSION:C-arm CT is a useful tool to establish PCNL access, particularly in cases of upper pole access or complicated anatomy

How to Keep it Adequate: A Validation Protocol for Agent-Based Simulation

Agent-based models are used in a huge diversity of contexts, which complicates the establishment of a shared understanding of model validity and adequate methods for model construction, inference and validation. Starting from the tenet that model validity can only be judged with respect to a well-defined purpose and context, we conceptualise validation as systematically substantiating the premises on which conclusions from simulation analysis for a specific context are built. We revisit the premises of empirical and structural validation and argue that validation should not be understood as an isolated step in the modelling process. Rather, sound conclusions from simulation analysis require context-adequate choices at all steps of simulation analysis. To facilitate communication, we develop a protocol of guiding questions to analyse the modelling context, choose appropriate methods at each step, document the premises involved in a specific simulation analysis, and demonstrate the adequacy of the model for its context

Grassland greening on the Mongolian Plateau despite higher grazing intensity

Changes in land management and climate alter vegetation dynamics, but the determinants of vegetation changes often remain elusive, especially in global drylands. Here we assess the determinants of grassland greenness on the Mongolian Plateau, one of the world's largest grassland biomes, which covers Mongolia and the province of Inner Mongolia in China. We use spatial panel regressions to quantify the impact of precipitation, temperature, radiation, and the intensity of livestock grazing on the normalized difference vegetation indices (NDVI) during the growing seasons from 1982 to 2015 at the county level. The results suggest that the Mongolian Plateau experienced vegetation greening from 1982 to 2015. Precipitation and animal density were the most influential factors contributing to higher NDVI on the grasslands of Inner Mongolia and Mongolia. Our results highlight the dominant effect of climate variability, and especially of the precipitation variability, on the grassland greenness in Mongolian drylands. The findings challenge the common belief that higher grazing pressure is the key driver for land degradation. The analysis exemplifies how representative wall‐to‐wall results for large areas can be attained from exploring space–time data and adds empirical insights to the puzzling relationship between grazing intensity and vegetation growth in dryland areas.European Union's Framework Programme for Research and Innovation ‐ Horizon 2020 (2014‐2020)Alexander von Humboldt Foundation of GermanyPeer Reviewe

Potential of Using ICT Tools for Crop Diseases Management among Heterogenous Farmers in Rwanda

Social interactions among farmers, extension agents, and government officials play a critical role in knowledge development and exchange, uptake of new practices, collective decision-making in agricultural practices. Smartphones and new communication tools are likely to transform the way information exchange and social interactions take place. However, how these ICT developments will influence the communication and social interactions among farmers, and the decision-making of farmers are intriguing questions, yet to be studied. Thus, this study aims to evaluate the use and experience of ICT of banana growers in Rwanda within the context of establishing an effective method for prevention and control of Banana Xanthomas Wilt (BXW), an infectious plant disease. Specifically, we want to assess whether farm clusters associate with the different behaviors and perceptions of the use of ICT. A structured questionnaire was used to collect household information from banana growers (n=690) in 8 representative districts. A combination of principal component analysis and cluster analysis was used to develop a farmer typology of banana growers. Three types of banana growers were identified, namely, i) Beer banana farmers, ii) Livestock-based farmers, and iii) Cooking banana farmers. We then conducted a statistical analysis to regress the use of ICT on the farmer typology and other socioeconomic control variables. Results showed that cooking banana-based farmers are more likely to own a smartphone and perceive ICT as very useful in effective control of BXW whereas beer banana farmers are less likely to own a smartphone, and they tend to perceive ICT as irrelevant in controlling BXW. Beer banana farmers are mainly limited by not knowing how to use these services which are associated with their low level of literacy while Livestock farmers prefer to get information from other sources. The studied farmers provide the potential for using ICT (Mobile based) extension services however beer banana farmers, less likely to own smartphones, are limited to few options

Indirect Effects of Grazing on Wind-Dispersed Elm Seeds in Sparse Woodlands of Northern China

Grazing leads to the reduction of biomass and plays a critical role in land degradation in arid and semiarid lands. However, the indirect effects of grazing on the ecosystem, e.g., the effect on seed dispersal, have not been well understood. In this study, we built an agent-based model (ABM) to simulate how grazing intensity affects the seed dispersal of elm trees, one of the native vegetation species of temperate woodlands in semiarid lands. The simulated results from the ABM and observed data from the real world were compared to assess the accuracy and validity of the ABM. The results show that elm seed densities in non-grazing, light, moderate, and heavy grazing lands were 74.97 ± 1.44, 57.63 ± 0.89, 37.73 ± 0.95, and 0.97 ± 0.05 seeds m−2, respectively—an apparently decreasing trend. Moreover, as grazing intensity increased, the values of nugget, sill, and partial sill decreased and the value of the ratio of nugget to sill increased. This study indicates that the grazing indirectly leads to the reduction of elm seed density and the increase of spatial heterogeneity of elm seed on the ground in sparse elm woodlands. Moreover, values of geostatistical indices from the ABM were not significantly different from field observation data except for the ratio of nugget to sill. It shows that ABMs can reasonably replicate the spatial pattern of elm seed densities in the field and thus are useful for simulating long-distance seed dispersal in sandy lands. This finding suggests that the indirect effects of grazing should be considered to effectively protect sparse elm woodlands