Dynamical patterns of cattle trade movements

Despite their importance for the spread of zoonotic diseases, our understanding of the dynamical aspects characterizing the movements of farmed animal populations remains limited as these systems are traditionally studied as static objects and through simplified approximations. By leveraging on the network science approach, here we are able for the first time to fully analyze the longitudinal dataset of Italian cattle movements that reports the mobility of individual animals among farms on a daily basis. The complexity and inter-relations between topology, function and dynamical nature of the system are characterized at different spatial and time resolutions, in order to uncover patterns and vulnerabilities fundamental for the definition of targeted prevention and control measures for zoonotic diseases. Results show how the stationarity of statistical distributions coexists with a strong and non-trivial evolutionary dynamics at the node and link levels, on all timescales. Traditional static views of the displacement network hide important patterns of structural changes affecting nodes' centrality and farms' spreading potential, thus limiting the efficiency of interventions based on partial longitudinal information. By fully taking into account the longitudinal dimension, we propose a novel definition of dynamical motifs that is able to uncover the presence of a temporal arrow describing the evolution of the system and the causality patterns of its displacements, shedding light on mechanisms that may play a crucial role in the definition of preventive actions.     

Socioeconomic dimensions,migration, and deforestation: An integrated model of territorial organization for the Brazilian Amazon

The territory organization of the Brazilian Amazon, understood as a socioeconomic network of municipalities, reflects the diversity of human settlements and their potentials for environmental changes, especially deforestation. This paper characterizes the urban network in the Brazilian Amazon through a model that integrates the levels of socioeconomic organization of municipalities and their interrelationships, as determined through migratory movements. The model of territorial organization combines five components: (i) the hierarchy of central places (poles) established by the concentration of urban specialized services, (ii) the geographical distance between central poles and other centers, (iii) the poles’ populations, (iv) the migratory movements among them, and (v) a socioeconomic dimension index. These components are combined into a gravitational model to produce measures and maps of the socioeconomic municipality network of the Brazilian Amazon. As a result, out of 792 municipalities in the Brazilian Amazon, 9 were classified as macro-poles, 29 were classified as meso-poles and 48 as micro-poles. The areas of influence of these poles were determined according to the three hierarchy levels. The Amazon region network comprises a nested spatial pattern of municipalities not constrained by the state boundaries. Socioeconomic space and population movements influence the mobility of the deforestation frontier. This analysis provides insights to predict deforestation as well as to guide formulation of sustainable development policies suitable for each region's specificity.     

基于复杂网络的长三角城市对外服务群落结构研究

城市群已成为国家参与全球竞争与国际分工的重要空间载体,其空间组织形式正从个体城市集聚、等级性的中心地结构向多中心、嵌套式的群落结构演变。为刻画长三角地区城市在不同要素层面下形成的多层次群落结构及其状态,借助复杂网络分析工具,从城市群落的节点特征、垂直和水平结构、不同群落结构间的相互关联三方面实证分析长三角地区3类(生产性、生活性、公共性)对外服务流的网络结构特征。研究显示:1)长三角城市节点服务功能分化,节点层级性分异显著,生产和生活性服务网络的节点规模呈"长尾"分布,公共性服务网络的节点规模相对均衡;2)垂直结构上,3类对外服务网络的网络密度、网络效率、流量占比和空间分布各不相同;水平结构上,初步形成对外服务网络的专业化分工格局,部分城市突破区域界线,呈跨地域集聚组团的态势。3)较强的结构关联性存在于生产性和生活性对外服务网络之间,两者在中低度值的城市节点上具有一致性,呈联动发展格局;公共性对外服务网络与前两者的节点度值分异较大,促进了整体群落服务功能结构的丰富和完善。基于复杂网络的群落研究可以从多维结构的分析中寻求城市群落的分工协作和共生,为当前多核心、网络化的城市空间组织与规划提供科学参考。     

Patterns and Limitations of Urban Human Mobility Resilience under the Influence of Multiple Types of Natural Disaster

Natural disasters pose serious threats to large urban areas, therefore understanding and predicting human movements is critical for evaluating a population’s vulnerability and resilience and developing plans for disaster evacuation, response and relief. However, only limited research has been conducted into the effect of natural disasters on human mobility. This study examines how natural disasters influence human mobility patterns in urban populations using individuals’ movement data collected from Twitter. We selected fifteen destructive cases across five types of natural disaster and analyzed the human movement data before, during, and after each event, comparing the perturbed and steady state movement data. The results suggest that the power-law can describe human mobility in most cases and that human mobility patterns observed in steady states are often correlated with those in perturbed states, highlighting their inherent resilience. However, the quantitative analysis shows that this resilience has its limits and can fail in more powerful natural disasters. The findings from this study will deepen our understanding of the interaction between urban dwellers and civil infrastructure, improve our ability to predict human movement patterns during natural disasters, and facilitate contingency planning by policymakers.     

城市再生视野下高密度城区生态空间规划方法——以厦门本岛立体绿化专项规划为例

面对快速城市化进程中城市高密度地区生态空间缺乏、布局支离破碎的问题,从规划层面分析了其问题的症结所在;提出屋顶绿化与城市绿地系统联动互补,是针对城市高密度地区生态环境受损严重以及土地资源紧缺的约束条件下,建构生态空间网络的有效途径;并以厦门本岛为研究区,基于GIS、遥感技术,利用高清遥感数据结合实地调研、问卷调查、部门资料、规划文本建立现状及规划空间数据库;从既有研究梳理、综合效益影响、城市发展诉求分析3个层面总结屋顶绿化实施潜力影响因子,结合规划分区与建筑分类建立实施潜力评估方法;对研究区进行屋顶绿化实施潜力评估,结合城市绿地系统,以"全域空间、重点片区、多维网络"为方法进行研究区生态空间网络规划。结果表明:1)生态结构完善、城市功能优化、公共服务需求、环境改善需求、建筑属性特征、建筑产权归属是屋顶绿化实施潜力评估要素,其包含的城市生态框架、城市功能结构、景观提升需求、建筑改造需求、内涝程度、热岛强度、微气候环境、建筑高度、建筑年代、建筑类型、建筑产权属性是关键性评估因子;2)厦门本岛2016年屋顶绿化率仅有2%,且附属于居住建筑和城中村的屋顶绿化量超过总量的一半,商业、公共、产业建筑作为空间载体进行屋顶绿化有较大发展空间,未绿化的屋顶资源中有81.3%适宜进行屋顶绿化;3)探索高密度城区生态空间网络布局的规划方法是本研究的第一步,下一步通过借助AI、GIS等技术,尝试防控高强度开发与高危集聚引发的城市生态和灾害问题,构建满足复合功能的生态空间网络优化的研究方法。     

基于景感生态学理念的乡村社会-生态系统供给服务研究

乡村社会-生态系统的稳定和可持续发展为农业农村现代化的实现奠定着基础,在稳定社会经济发展、提高城乡居民福祉方面发挥着重要作用。服务性公共设施作为乡村社会-生态系统供给服务的重要组成部分,代表了乡村的发展水平与该地区居民生活质量水平。研究公共服务设施的空间分布特征和综合评价其供给服务可改善乡村社会-生态系统结构,为城乡居民提供高质量的社会生态系统服务。以厦门市岛外城市化乡村为研究对象,通过厦门市岛外POI数据和乡村社会经济统计数据,以公共服务设施为景感载体,分析其空间分布和测度其供给服务水平,采用核密度分析方法与熵值分析法,分析厦门市乡村社会-生态系统供给服务空间分布特征,结合人口、经济、距岛内核心区距离等指标对各村庄社会-生态系统供给服务能力进行皮尔逊相关性分析。研究发现厦门乡村公共设施供给服务能力表现为集美区 > 海沧区 > 同安区 > 翔安区;各村庄公共设施供给服务能力水平影响因素是多元且具有多样性的;提出从城乡居民的认知心理与物质需求出发对公共设施进行景感生态营造以提高村庄社会-生态系统供给服务能力,更好满足人们的需求。本文对公共服务设施的空间优化提出对策建议,研究结果可为乡村社会-生态系统供给服务提升和乡村可持续发展提供理论研究依据。     

Complexity in Urban Development and Management

Systems dynamics, cellular automata, agent-based modeling, and network analyses have been used in population, land use, and transport planning models. An overview of complex systems science as applied to urban development is presented, and examples are given of where the problems of housing people and anticipating their movements have been addressed with complex approaches, sometimes in concert with deterministic, large-scale urban models. Planning for cities today has additional environmental and social priorities in common with many topics that concern industrial ecology. The research agenda suggested here is that this, too, can be enriched with complex systems thinking and models to complement the often static assessment of environmental performance and better inform decision processes.     

Mobilis in mobile: a probabilistic and chronotopic model of mobility in urban spaces.

In this communication we propose an urban mobility model based on individual random walk driven by a chronotopic action with a deterministic public transportation network. In the absence of chronotopoi the mean field analytic results are found in good agreement with simulations on a computer. When the chronotopoi are switched on, they attract people according to a given law and we obtain a sort of diffusive motion. The model can describe many different kinds of dynamical systems, including biological ones. The work is in progress and the next step will be an empirical test in a concrete case.     

基于GIS、景观格局和网络分析法的厦门本岛生态网络规划

 以厦门本岛2000年Landsat-TM卫星影像解译的土地利用现状图、绿地系统现状图与规划图为基础资料,在地理信息系统（GIS）支持下,运用景观格局分析方法,选用多种景观指数,评价了厦门本岛绿地系统的现状与已有规划。在此基础上,应用网络分析法构建了旨在优化生态网络的不同新方案。通过α指数、β指数、γ指数等网络结构指数,进行不同方案的比较,从中选出最优的规划方案。将选出的生态网络E的廊道宽度设为50 m,叠加到厦门市绿地系统规划图上,并应用景观指数,定量评价了该优化方案对厦门本岛绿地系统的改善情况。其结果表明：该优化方案能使景观的破碎化程度得到改善,绿地斑块形状的复杂性程度进一步增加,景观连接度得到提高,说明优化方案生态网络E可进一步明显改善厦门本岛现有绿地系统的数量和质量。我们的研究结果也表明：应用景观指数和网络分析法相结合的方法,不仅可以定量评价城市绿地系统现状以及规划的合理性,而且可以优化城市生态网络的方案,使其更符合城市生态网络建设的整合性、和谐性、流通性、安全性、多样性和持续性原则。     

Antarctic killer whales make rapid,round-trip movements to subtropical waters: evidence for physiological maintenance migrations?

Killer whales (Orcinus orca) are important predators in high latitudes, where their ecological impact is mediated through their movements. We used satellite telemetry to provide the first evidence of migration for killer whales, characterized by fast (more than 12 km h(-1), 6.5 knots) and direct movements away from Antarctic waters by six of 12 type B killer whales tagged when foraging near the Antarctic Peninsula, including all tags transmitting for more than three weeks. Tags on five of these whales revealed consistent movements to subtropical waters (30-37° S) off Uruguay and Brazil, in surface water temperatures ranging from -1.9°C to 24.2°C; one 109 day track documented a non-stop round trip of almost 9400 km (5075 nmi) in just 42 days. Although whales travelled slower in the warmest waters, there was no obvious interruption in swim speed or direction to indicate calving or prolonged feeding. Furthermore, these movements were aseasonal, initiating over 80 days between February and April; one whale returned to within 40 km of the tagging site at the onset of the austral winter in June. We suggest that these movements may represent periodic maintenance migrations, with warmer waters allowing skin regeneration without the high cost of heat loss: a physiological constraint that may also affect other whales.     

Do physicians locate as spatial competition models predict? Evidence from Alberta.

This article analyses how physicians choose locations of practice in response to spatial competition forces and considers the implications of such choices for public policy to alleviate shortages of practitioners in rural areas. The predicted geographic distribution of physicians, as determined through spatial competition modelling, was compared with the actual distribution of physicians in 1990 among Alberta''s 19 census divisions. Physicians were found to respond to spatial competition forces in choosing where to practise, with the qualification that 1 urban patient had a demand weight equal to 2.32 rural patients. A policy to attract more physicians to rural areas by means of income subsidies is technically feasible but expensive. The high cost means that alternative policies such as a bigger and more effective ambulance network to transport patients to medical centres should become the focus of public policies to improve health care in rural areas.     

The future representativeness of Madagascar's protected area network in the face of climate change

With many species predicted to respond to a changing climate by shifting their distribution to climatically suitable areas, the effectiveness of static protected areas (PAs) is in question. The Madagascan PA network area has quadrupled over the past 15 years, and, although conservation planning techniques were employed to prioritise suitable areas for protection during this process, climate change impacts were not considered. We make use of species distribution models for 750 Madagascan vertebrate species to assess the potential impacts of climate change on (1) species richness across Madagascar, (2) species gain, loss and turnover in Madagascar's PAs and (3) PA network representativeness. Results indicate that Madagascar is predicted to experience substantial shifts in species richness, with most PAs predicted to experience high rates of species turnover. Provided there are no barriers to species movements, the representativeness of the current PA network will remain high for the species that are predicted to survive changes in climate by 2070, suggesting that little benefit will be gained from establishing new PAs. However, this rests on the assumption of mobility through areas currently characterised by fragmentation and anthropogenic activity, something that will require considerable expansion in conservation efforts in order to achieve.     

Bicycle accidents in childhood.

The results of a 10 year study of bicycle fatalities and an eight year study of serious non-fatalities are reported for urban Brisbane (population 1,000,000). There were 845 serious non-fatal bicycle accidents and 46 fatalities during the study. Boys were involved in 86% of accidents. Boys have an accident rate of 134.21 per 100,000 population at risk and a fatality rate of 5.06 per 100,000 at risk. Serious bicycle accidents have increased by 50% in this decade; but considering fatal cases alone, no secular trend was evident over the 10 year period of the study. This suggests that an increase in the overall rate of bicycle accidents has been in part compensated by less serious injuries. In 70% of fatalities children had head injuries, and 87% of fatalities followed a collision between a cyclist and a motor vehicle or a train. Bicycle accidents on the roads most commonly occur to boys aged between 12 and 14 years on a straight road at "mid-block" between 3 and 5 pm in clear weather conditions and in daylight. It is concluded that injuries and fatalities after bicycle accidents can be reduced by protecting children''s heads, separating child cyclists from other road traffic, or educating and training both cyclists and other road users in safe behaviour. The compulsory use of helmets and the restriction of access to the roads by child cyclists to reduce injuries are, however, still controversial in many areas.     

Trade-off between Multiple Constraints Enables Simultaneous Formation of Modules and Hubs in Neural Systems

The formation of the complex network architecture of neural systems is subject to multiple structural and functional constraints. Two obvious but apparently contradictory constraints are low wiring cost and high processing efficiency, characterized by short overall wiring length and a small average number of processing steps, respectively. Growing evidence shows that neural networks are results from a trade-off between physical cost and functional value of the topology. However, the relationship between these competing constraints and complex topology is not well understood quantitatively. We explored this relationship systematically by reconstructing two known neural networks, Macaque cortical connectivity and C. elegans neuronal connections, from combinatory optimization of wiring cost and processing efficiency constraints, using a control parameter , and comparing the reconstructed networks to the real networks. We found that in both neural systems, the reconstructed networks derived from the two constraints can reveal some important relations between the spatial layout of nodes and the topological connectivity, and match several properties of the real networks. The reconstructed and real networks had a similar modular organization in a broad range of , resulting from spatial clustering of network nodes. Hubs emerged due to the competition of the two constraints, and their positions were close to, and partly coincided, with the real hubs in a range of values. The degree of nodes was correlated with the density of nodes in their spatial neighborhood in both reconstructed and real networks. Generally, the rebuilt network matched a significant portion of real links, especially short-distant ones. These findings provide clear evidence to support the hypothesis of trade-off between multiple constraints on brain networks. The two constraints of wiring cost and processing efficiency, however, cannot explain all salient features in the real networks. The discrepancy suggests that there are further relevant factors that are not yet captured here.     

Network centrality of metro systems

Whilst being hailed as the remedy to the world's ills, cities will need to adapt in the 21(st) century. In particular, the role of public transport is likely to increase significantly, and new methods and technics to better plan transit systems are in dire need. This paper examines one fundamental aspect of transit: network centrality. By applying the notion of betweenness centrality to 28 worldwide metro systems, the main goal of this paper is to study the emergence of global trends in the evolution of centrality with network size and examine several individual systems in more detail. Betweenness was notably found to consistently become more evenly distributed with size (i.e. no "winner takes all") unlike other complex network properties. Two distinct regimes were also observed that are representative of their structure. Moreover, the share of betweenness was found to decrease in a power law with size (with exponent 1 for the average node), but the share of most central nodes decreases much slower than least central nodes (0.87 vs. 2.48). Finally the betweenness of individual stations in several systems were examined, which can be useful to locate stations where passengers can be redistributed to relieve pressure from overcrowded stations. Overall, this study offers significant insights that can help planners in their task to design the systems of tomorrow, and similar undertakings can easily be imagined to other urban infrastructure systems (e.g., electricity grid, water/wastewater system, etc.) to develop more sustainable cities.     

Uncovering Patterns of Inter-Urban Trip and Spatial Interaction from Social Media Check-In Data

The article revisits spatial interaction and distance decay from the perspective of human mobility patterns and spatially-embedded networks based on an empirical data set. We extract nationwide inter-urban movements in China from a check-in data set that covers half a million individuals within 370 cities to analyze the underlying patterns of trips and spatial interactions. By fitting the gravity model, we find that the observed spatial interactions are governed by a power law distance decay effect. The obtained gravity model also closely reproduces the exponential trip displacement distribution. The movement of an individual, however, may not obey the same distance decay effect, leading to an ecological fallacy. We also construct a spatial network where the edge weights denote the interaction strengths. The communities detected from the network are spatially cohesive and roughly consistent with province boundaries. We attribute this pattern to different distance decay parameters between intra-province and inter-province trips.     

基于空间优先级的快速城市化地区绿色基础设施网络构建——以南京市浦口区为例

绿色基础设施是一个由自然区域和其他开放空间相互联系的网络。在城市空间极为有限的情况下,如何有效构建城市绿色基础设施网络并识别那些具关键性景观生态功能的网络要素显得极为重要。为了给城市绿色基础设施网络的建设和管理提供新的建模与分析理念,以快速城市化的南京市浦口区为例,采用MSPA方法并结合景观连通性指数,遴选出了对维持景观连通性贡献最大的生境斑块作为绿色基础设施网络的网络中心,进而采用最小路径方法构建了研究区潜在的绿色基础设施网络,并尝试利用空间句法分析,基于结构优化视角对绿色基础设施网络进行优先级的识别,从而使绿色基础设施网络的构建更科学。研究结果可为快速城市化地区绿色基础设施网络的构建提供一种研究思路与方法,对绿色基础设施网络要素的优先级评价也具有一定的借鉴意义。     

A Generalized Radiation Model for Human Mobility: Spatial Scale,Searching Direction and Trip Constraint

We generalized the recently introduced “radiation model”, as an analog to the generalization of the classic “gravity model”, to consolidate its nature of universality for modeling diverse mobility systems. By imposing the appropriate scaling exponent λ, normalization factor κ and system constraints including searching direction and trip OD constraint, the generalized radiation model accurately captures real human movements in various scenarios and spatial scales, including two different countries and four different cities. Our analytical results also indicated that the generalized radiation model outperformed alternative mobility models in various empirical analyses.     

城市居民行为与生态社区建设研究

简评了城市居民行为与社区生态环境的关系及其对生态社区建设的启示,归纳了相关研究的进展及存在的问题,并提出下一步研究方向。研究发现,当前城市居民行为对生态环境的胁迫及社区环境对居民行为的影响研究方法多样、内容分散,研究设计及其逻辑尚无系统完备的研究体系做支撑。此外,目前生态社区建设研究大多集中于新型生态社区的设计与开发,少有针对已有社区的生态化改造的分析,也没有充分针对不同城市社区类型及资源、能源、环境禀赋提出因地适宜的建设生态社区的建议。研究还发现,即使是针对新型生态化社区,在构建过程中也是重视生态社区的规划和生态基础设施的建设、忽视生态社区的后续管理,更是缺乏针对管理机制创新方面的探讨。另外,现有城市生态社区建设多重视单个具体指标的提升,轻视全面建设生态社区中的系统性思考,缺少具有普适性的生态社区评价指标体系及对指标间关联关系的考量与分析。现有社区物业管理信息化平台,大多包含了社区环境卫生管理,并没有从社区生态系统建设和保护的角度出发将社区物质能量代谢、碳氮循环、生态系统性管理理念纳入进来,更缺少实时、动态的面向社区居民的生态环境资产核算方面的计算、查询、规划等互动式交流。当前生态社区集成示范的可推广性与普适性有待进一步深入考察,即要保证示范具有可参考、可借鉴、可推广等实际应用价值,避免由于技术过于超前或成本太高而导致示范难有操作性。