Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.     

Theory and practice of monetary policy

Summary. We consider an optimally managed renewable resource with stochastic non-concave growth function. We characterize the conditions under which the optimal policy leads to global extinction, global conservation and the existence of a safe standard of conservation. Our conditions are specified in terms of the economic and ecological primitives of the model: the biological growth function, the welfare function, the distribution of shocks and the discount rate. Our results indicate that, unlike deterministic models, extinction and conservation in stochastic models are not determined by a simple comparison of the growth rate and the discount rate; the welfare function plays an important role.Received: 20 October 2004, Revised: 28 February 2005, JEL Classification Numbers: D90, O11, O41, Q32.Santanu Roy: Correspondence toResearch on this paper was completed when the second author visited Cornell University in July, 2003. We thank the Center for Analytic Economics and the Department of Economics at Cornell University for making this research visit possible. The current version has gained considerably from the comments made by an anonymous referee.     

The value of nonindigenous species risk assessment in international trade

Managing the introduction of nonindigenous species is becoming a major goal of policy-makers at regional, national and international scales. Here we investigate, at the national level, the ideal design and expected net benefits of a risk assessment program for evaluating the desirability of nonindigenous species imports. We show how to enhance the statistical rigor of such a system by correcting a common non-random sampling problem encountered in the data. This correction enables model output to be interpreted in an economically relevant way and facilitates a theoretically rigorous characterization of the balance between trade and nonindigenous species establishment risk. Using reptiles and amphibians imported to the U.S. as a case study, we characterize economic outcomes over a range of cases and demonstrate substantial expected returns to such a screening program, relative to the current effectively open-door policy. Our results are informative for the current debate in the U.S. about whether to require federal agencies to apply risk assessment before allowing a species for import. The framework presented decomposes a complex argument about risk management into component economic and statistical parts, allowing for debate and improved understanding over each element to inform the overall program in a transparent fashion.     

Being Good Parents or Being Good Citizens: Dilemmas and Contradictions of Urban Families in Middle‐Class Enclaves and Mixed Neighbourhoods in Germany

In recent years, cities have become ever more attractive to middle‐class families. On the one hand, middle‐class families tend to withdraw into (often newly built) socially homogeneous middle‐class neighbourhoods. On the other hand, they are also known to move into inner‐city and socially mixed areas, thus triggering processes of gentrification. Academic literature has often denounced these housing choices as being either ‘separatist’ or ‘revanchist’, more broadly categorized as strategies of ‘middle‐class disaffiliation’. Although there is a grain of truth in these interpretations, the reality is certainly more complicated. In our research on middle‐class parents’ housing and neighbourhood choices as well as their patterns of neighbourhood use, carried out in each of the two types of residential area mentioned above, we have only very rarely found an explicit desire to draw boundaries that exclude those ‘beneath’ them. We rather argue that the housing choices and neighbourhood‐related activities of middle‐class family households are heavily influenced by the specific dilemmas the interviewees face as (working) urban parents. While a significant number of respondents worry about the social sustainability, justice and cohesion of urban society, they are also concerned about the future prospects of their children. Many find it difficult to reconcile these conflicting normative demands under the prevailing circumstances.     

自然保护区生态旅游设计发展潜力分析——以吉林省长白山自然保护区为例

生态旅游是一种将可持续发展理念贯穿于整个旅游系统的发展方式,它是可持续旅游宏观指导思想的一种操作上的落实。自然保护区生态旅游,是在自然保护区内开展的、以自然保护为核心的、高度责任化的高层次旅游活动。长白山自然保护区是我国重要的旅游地区,自然环境独特,旅游资源丰富多样,长白山自然保护区生态旅游具有很大的发展潜力。因此应制定生态旅游规划,建立“吉林省长白山管理区”,建立健全的旅游环境容量调控系统。     

Parental perception of lunch schemes in Danish kindergartens: A cross-sectional survey

Children’s daily consumption of food in childcare institutions has an impact on their public health nutritional status. The collaboration of parents and employees of kindergartens is important to ensure healthy eating habits among the next generation. Consequently, evaluations of lunch schemes are important to provide a good foundation for enhancing communication between home and institutional settings. The aim of this article is to assess parental satisfaction and identify themes related to parental perceptions of lunch schemes in Danish kindergartens. A survey was developed and distributed in four kindergartens with lunch schemes. A combination of closed and open questions were used to evaluate satisfaction and identify positive and negative aspects of the lunch schemes. Parents of 93 children participated in the study and the response rate was 55%. Eighty-nine percent expressed satisfaction with their children’s lunch scheme. According to parents, the most positive aspects were that lunch schemes serve a variety of food, their ability to prevent neophobia, that children learn that eating is a social occasion, and that the arrangements offer convenience to parents. The negative aspects identified were the lack of communication between the kindergarten childcare institutions and the parents regarding the food. Overall, parents are very satisfied with their children’s lunch schemes; however, the information between institutions and parents could be improved.     

The Essential Role of Sense of Community in a Youth Sport Program

This multiphased study identifies the salient benefits that parents seek for their families from a youth sport program. Phase 1, a preseason focus group study of parents of swimmers in three clubs (N = 15), indicated parents seek a sense of community for their children and themselves, and sense of community is linked to their desire for children to learn sport and life skills. Phase 2, a postseason survey of parents in the same three clubs (N = 129), tested the relationships among coaching quality, friendships, organizational communication, sport and life skills, sense of community, parents' satisfaction, and their repeat purchase intention. Using path analysis, sense of community was identified as the key driver of satisfaction and repeat purchase intention, with swimming improvement also having a significant effect on satisfaction. These findings highlight the central role sense of community plays for participants and their families in youth sport contexts.     

Competitive selection, self-organisation and Joseph A. Schumpeter

Post-Schumpeterians have tended to use biological analogies to understand economic evolution, in contrast to Schumpeter himself. In this paper it is argued that the biological analogies used tend to be outdated and that Schumpeter espoused an intuitive understanding of the evolutionary economic process that is closely related to modern conceptions of self-organisation, suitably adapted for application in socioeconomic systems. Using a self-organisation approach, competition can be understood without recourse to biological analogy, in terms of general systemic principles that operate in the presence of variety. Viewing economic evolution in terms of complex adaptation in self-organising systems yields nonequilibrium and nonlinear perspectives that parallel Schumpeter's own intuitions, reinvigorating them as the basis of evolutionary economic thinking in the new Millennium.     

美国生物医学研究概况

美国国立卫生研究院（NIH）专司是美国唯一一家国家级公立生物医学研究机构，负责生物医学领域的研究和管理。在关联邦机构中，NIH掌管的研发经费仅次于国防部。本文对NIH的科研投入情况、资助计划和发展方向进行介绍和分析，旨在从宏观上把握美国生物医学的总体发展水平和重点方向。     

《医学生物实验学》教学改革的探索与实践

通过优化重组实验教材,增加综合性和探索性实验内容,改革教学手段,开展师生座谈会及时反馈教学效果等一系列教学改革措施,最终建立由医学细胞生物学、医学遗传学、医学生物实验学组成的相互支撑、紧密联系的课程体系,提高学生跨学科知识综合运用的能力和实验操作的能力。