Sampling from spatial databases

This paper deals with techniques for obtaining random point samples from spatial databases. We seek random points from a continuous domain (usually ²) which satisfy a spatial predicate that is represented in the database as a collection of polygons. Several applications of spatial sampling (e.g. environmental monitoring, agronomy, forestry, etc) are described. Sampling problems are characterized in terms of two key parameters: coverage (selectivity), and expected stabbing number (overlap). We discuss two fundamental approaches to sampling with spatial predicates, depending on whether we sample first or evaluate the predicate first. The approaches are described in the context of both quadtrees and R-trees, detailing the sample first, acceptance/rejection tree, and partial area tree algorithms. A sequential algorithm, the one-pass spatial reservoir algorithm is also described. The relative performance of the various sampling algorithms is compared and choice of preferred algorithms is suggested. We conclude with a short discussion of possible extensions.     

Cybernetic Risk Analysis

The Pearl Harbor case study reveals that risk analysis failure may be caused by any of a number of factors. However, the most important variables are system load, gain, lead time, and lag time. The dynamics of such cybernetic systems analysis constitute an important aspect in this regard. Four different risk management strategies, or organization designs, have been proposed in this paper. Each has a unique combination of the imputed variables and each has a unique cause of surprise, risk analysis failure, and crisis.     

On the effectiveness of cognitive feedback from an interface agent

The objective of this study was to determine the impact of task information (TI) provided by an interface agent during the idea evaluation and integration step of the problem formulation stage of the problem solving process. The effectiveness assessment was based on solving diagnostic decision problems in the domain of complex industrial machinery. Ten domain experts participated in this study. Decision support was provided by a case-based reasoning system. Findings suggest that TI provided by the interface agent had no effect on the decision maker's performance, nor on the associated cognitive effort. However, a verbal protocol analysis revealed that the ten subjects used the interface agent to verify their decision processes. The results and their implications are discussed with respect to current findings in the area of decision support systems.     

Adaptive Build-up and Breakdown of Trust: An Agent Based Computational Approach

This article employs Agent-Based Computational Economics (ACE) to investigate whether, and under what conditions, trust is viable in markets. The emergence and breakdown of trust is modeled in a context of multiple buyers and suppliers. Agents develop trust in a partner as a function of observed loyalty. They select partners on the basis of their trust in the partner and potential profit, with adaptive weights. On the basis of realized profits, they adapt the weight they attach to trust relative to profitability, and their own trustworthiness, modeled as a threshold of defection. Trust and loyalty turn out to be viable under fairly general conditions.     

自组织建模方法和GDP增长模型研究

经济系统的复杂性决定了经济变动及影响因素解释的困难性。本文阐述了一种经济系统复杂性研究的有效方法-自组织建模方法,同时应用此方法建立一个解释我国GDP增长的自组织模型,分析影响我国经济增长的主要因素,并在此基础上提出相应的对策思路。     

生存理性如何影响农户的差别化生产

在食品安全威胁下,农户重新定义了“为自家生产”和“为市场生产”的差别化生产行为。基于经济理性行为假设认为农户存在以确保自家食品安全为动机的生存理性。根据在5省区收集的827份农村入户调研数据,对农户差别化生产行为进行具体分析,描述了差别化生产行为总体特征,并测量农户食品安全自我保护意识、威胁感知程度和信息渠道等因素。运用Probit模型验证了命题：以食品安全自我保护意识为特征的生存理性,支配了农户为确保自家消费安全而进行的差别化生产。     

中国电力消费周期的路径演化识别——基于Markov区制转移模型

基于1980-2016年中国第一产业、第二产业（工业、建筑业）和第三产业的年度电力消费数据,采用H-P滤波技术对中国电力消费的趋势成分和波动成分轨迹进行刻画,运用马尔科夫区制转移[MS（n）-AR（p）]模型分析中国电力消费周期在各区制间的动态转移过程,识别改革开放以来中国电力消费周期的路径演化特征,在此基础上预测未来5年中国电力消费周期的区制分布情况。研究发现:（1）中国电力消费增长率的波动程度自2003年明显缩窄,且从2007年开始进入下行周期。（2）中国电力消费周期具有较强的稳定性,不易向着其收缩期和扩张期跨越。且中国电力消费处于"低速增长区制"的年份往往对应着中国经济发展相对趋缓的大环境。（3）2014-2015年中国电力消费向其收缩期转移的迹象明显,但预测结果表明,未来5年中国电力消费整体上将继续保持稳定增长的趋势。     

新贫困视域下乡村转型的困厄与重构路径

中国社会转型的重要背景之一是全球消费社会的到来。 这使得新穷人现象日渐凸显,并成为影响甚至主导整个社会转型的核心线索。 作为新穷人的典型表现,乡村新贫困既包括在城乡二元结构下,村民难以获得以城市生活方式为参照的社会公认生活水准而引发的结构性贫困,也包括由消费欲望激发的社会心理性贫困。 由此,乡村消费转型表现为如下困境:私人消费中,个体消费认同在地和脱嵌的困境以及家庭消费规范物质化和人伦的两难;集体消费中,消费品“上移冶和“下乡冶的悖论。 为应对这些困境,必须从消费角度,破解“新穷困冶的结构性和文化困境,实行新型城镇化和新农村建设并举。     

Early Pregnancy Assessment Services in Australia: What psychosocial support is available? A qualitative study

ProblemWomen commonly experience emotional distress following miscarriage but do not receive the support they need from healthcare providers.BackgroundMiscarriage can result in psychological morbidity; however, appropriate support at the time of a miscarriage can lead to better psychological outcomes. Early Pregnancy Assessment Services (EPASs) are dedicated outpatient services considered the “gold standard” for miscarriage care. Little is known about the psychosocial support EPASs provide in Australia.AimsThe aim of this study was to explore the provision of psychosocial support in Australian EPASs.MethodsSemi-structured interviews were conducted with 29 purposively sampled key-informants from 13 EPASs. Interviews were audio-recorded, transcribed, and thematically analysed.FindingsConsiderable variation was found in how EPASs functioned and their provision of psychosocial support. Many services were co-located with antenatal services, run by doctors with limited experience and most did not offer any psychosocial training to staff specific to EPAS. Referrals for additional support were generally not offered for first trimester miscarriages, and follow-up typically focused on physical management rather than emotional wellbeing. All EPAS staff demonstrated a strong commitment to providing best possible care to women within their own clinical setting and acknowledged the need for improved psychosocial support.ConclusionThis study provides the first exploration of Australian EPASs’ provision of psychosocial support. It has shown that while health care professionals working in EPASs are dedicated to providing the best possible care to women within their clinical setting, psychosocial support is very limited and could be improved.     

R&D cooperation in collaborative consumption of research equipment: An ERGM approach

High-tech research infrastructure is essential for state-of-the-art research, but requires many resources. Relatively weak actors, such as SMEs, cannot secure enough of those. Applying the concept of collaborative consumption via digital platforms, we examine the cooperative behavior of Korean SMEs that share research equipment to overcome their lack of resources. Also, we analyze configurations of a collaborative consumption network using the Exponential Random Graph Model. Network structural factor analysis shows sufficient effects of network positive feedback through cooperative consumption with a variety of popular providers and attributes analysis shows that SMEs frequently engage in collaborative consumption with their counterparts in the same region. This new cooperative model can achieve a virtuous cycle of policies, as it increases the efficiency of research infrastructure, preventing the unnecessary building of new research equipment and enabling relocation of underutilized infrastructure and online reservation of equipment.