The discretely observed immigration-death process: Likelihood inference and spatiotemporal applications

ABSTRACT

We consider a stochastic process, the homogeneous spatial immigration-death (HSID) process, which is a spatial birth-death process with as building blocks (i) an immigration-death (ID) process (a continuous-time Markov chain) and (ii) a probability distribution assigning iid spatial locations to all events. For the ID process, we derive the likelihood function, reduce the likelihood estimation problem to one dimension, and prove consistency and asymptotic normality for the maximum likelihood estimators (MLEs) under a discrete sampling scheme. We additionally prove consistency for the MLEs of HSID processes. In connection to the growth-interaction process, which has a HSID process as basis, we also fit HSID processes to Scots pine data.     

中国省际经济差距来源分析

在利用索洛模型对中国省区1985—2009年经济增长进行分解的基础上,结合空间标准差指标并采用基于VAR模型的脉冲响应函数分析了中国省际经济差距状况及来源。研究发现:总的来看,中国省区劳均产出与要素投入均呈现空间σ趋异倾向,而全要素生产率则在呈现空间σ收敛后趋于稳定。进一步利用VAR模型及脉冲响应函数分析发现,在较长时期内,要素投入总体上扩大了中国省际经济差距,而全要素生产率则有助于缩小省际经济差距,这主要是由要素投入的经济拉动滞后效应和技术的扩散效应所致。     

LCCM理论框架下空间介词in的非空间关系语义派生研究

英语空间介词的语义研究是认知语言学的热点之一。本文运用LCCM理论对英语空间介词in的词汇概念进行系统全面的认知识解,重点分析了in的词汇概念从空间关系转向非空间关系的认知过程,以期对该领域的研究提供一个新的视角。     

农地承包权置换城镇社保的空间计量分析

通过对江西、安徽、江苏三省42个乡镇样本农户的实地调查数据,分析了农户在农地承包权置换城镇社保意愿选择方面的影响因素,得出乡镇家庭人均纯收入、乡镇所有农户医疗和养老支出占总收入比重的平均值、乡镇所有家庭务工比率的平均值、城镇人均社保缴纳的费用对农户选择农地承包权置换城镇社保的意愿存在显著影响。同时采用空间自相关的莫兰指数来反映不同地区之间农户选择农地承包权置换城镇社保意愿的空间分布模式,验证农户在选择农地承包权置换城镇社保的意愿上存在相互影响的特征。     

城市空间和大学校园——以日本国立大学校园空间变迁为例

大学校园在城市发展中有其特殊的物质、文化机能。本文从El本国立大学校园在历史上的变迁,即从空间形态、空间位置、空间聚集方式等三方面的视点,阐述了大学和城市的相互关系。指出了大学校园在空间形态上的变迁,体现了大学和城市之间的延续性和渗透性;大学在空间位置上的变迁上体现了大学对城市的依赖性;以及大学在空间聚集方式上的变迁体现了大学相对于城市的独立性等相互关系。     

So near and yet so far - socio-spatial factors affecting service accessibility

ABSTRACT

Conventionally, social service planners conduct statistical analyses on service data for future planning. However, the limitations are their neglect of the spatial characteristics of these social data and their effects. All human activities have social and spatial dimensions. Social service provision is no exception. In this study, the authors suggest a socio-spatial framework in term of understanding service accessibility. A questionnaire survey was conducted and 491 participants, users and non-users, were interviewed. The results show that both spatial and social capital factors affect service accessibility. The study can help better service planning in densely-populated Asian metropolis like Hong Kong.     

Spatially Representing Vulnerability to Extreme Rain Events Using Midwestern Farmers’ Objective and Perceived Attributes of Adaptive Capacity

Potential climate‐change‐related impacts to agriculture in the upper Midwest pose serious economic and ecological risks to the U.S. and the global economy. On a local level, farmers are at the forefront of responding to the impacts of climate change. Hence, it is important to understand how farmers and their farm operations may be more or less vulnerable to changes in the climate. A vulnerability index is a tool commonly used by researchers and practitioners to represent the geographical distribution of vulnerability in response to global change. Most vulnerability assessments measure objective adaptive capacity using secondary data collected by governmental agencies. However, other scholarship on human behavior has noted that sociocultural and cognitive factors, such as risk perceptions and perceived capacity, are consequential for modulating people's actual vulnerability. Thus, traditional assessments can potentially overlook people's subjective perceptions of changes in climate and extreme weather events and the extent to which people feel prepared to take necessary steps to cope with and respond to the negative effects of climate change. This article addresses this knowledge gap by: (1) incorporating perceived adaptive capacity into a vulnerability assessment; (2) using spatial smoothing to aggregate individual‐level vulnerabilities to the county level; and (3) evaluating the relationships among different dimensions of adaptive capacity to examine whether perceived capacity should be integrated into vulnerability assessments. The result suggests that vulnerability assessments that rely only on objective measures might miss important sociocognitive dimensions of capacity. Vulnerability indices and maps presented in this article can inform engagement strategies for improving environmental sustainability in the region.     

Spatial Transmission Models: A Taxonomy and Framework

Within risk analysis and, more broadly, the decision behind the choice of which modeling technique to use to study the spread of disease, epidemics, fires, technology, rumors, or, more generally, spatial dynamics, is not well documented. While individual models are well defined and the modeling techniques are well understood by practitioners, there is little deliberate choice made as to the type of model to be used, with modelers using techniques that are well accepted in the field, sometimes with little thought as to whether alternative modeling techniques could or should be used. In this article, we divide modeling techniques for spatial transmission into four main categories: population‐level models, where a macro‐level estimate of the infected population is required; cellular models, where the transmission takes place between connected domains, but is restricted to a fixed topology of neighboring cells; network models, where host‐to‐host transmission routes are modeled, either as planar spatial graphs or where shortcuts can take place as in social networks; and, finally, agent‐based models that model the local transmission between agents, either as host‐to‐host geographical contacts, or by modeling the movement of the disease vector, with dynamic movement of hosts and vectors possible, on a Euclidian space or a more complex space deformed by the existence of information about the topology of the landscape. We summarize these techniques by introducing a taxonomy classifying these modeling approaches. Finally, we present a framework for choosing the most appropriate spatial modeling method, highlighting the links between seemingly disparate methodologies, bearing in mind that the choice of technique rests with the subject expert.     

Use and Misuse of Indicators in Spatial Planning: The Example of Land Take

The use of indicators to assess the impacts of spatial planning policies has experienced a strong increase in the last decades, despite the difficulties to identify clear causality links in this discipline. The aim of this article is to critically reflect on the impacts of such a phenomenon on spatial planning policies and practices. In order to do so, it explores the issue of land take and how the European Community has set up a policy objective, based on an indicator, to try to tackle the phenomenon.     

实现资源空间均衡发展的“双轮外溢驱动”理论及承载力系数值

目前全球经济发展的非均衡性问题日益突出，已成为制约各国经济发展的几大难题之一。如何破解这一难题，已成为理论界关注的焦点。目前看，必须进行理论创新，创建具有可操作且针对性强的新方法。“双轮外溢驱动模式”的研究及“承载力系数”的设定，为解决这一难题提供全新的思想路径。