The 1991 Cholera Epidemic in Peru: Not a Case of Precaution Gone Awry

The precautionary principle calls on decisionmakers to take preventive action in light of evidence indicating that there is a potential for harm to public health and the environment, even though the nature and magnitude of harm are not fully understood scientifically. Critics of the precautionary principle frequently argue that unbridled application of the principle leads to unintended damage to health and ecosystems (risk tradeoffs) and that precautious decision making leaves us vulnerable to "false-positive" risks that divert resources away from "real risks." The 1991 cholera epidemic in Peru is often cited as an example of these pitfalls of the precautionary principle. It has been mistakenly argued that application of the precautionary principle caused decisionmakers to stop chlorinating the water supply due to the risks of disinfection byproducts (DBPs), resulting in the epidemic. Through analyses of investigations conducted in the cities of Iquitos and Trujillo, Peru, literature review, and interviews with leading Peruvian infectious disease researchers, we determined that the epidemic was caused by a much more complex set of circumstances, including poor sanitation conditions, poor separation of water and waste streams, and inadequate water treatment and distribution systems. The evidence indicates that no decision was made to stop chlorinating on the basis of DBP concerns and that concerns raised about DBPs masked more important factors limiting expansion of chlorination. In fact, outside of Peru's capital Lima, chlorination of drinking water supplies at the time of the epidemic was limited at best. We conclude that the Peruvian cholera epidemic was not caused by a failure of precaution but rather by an inadequate public health infrastructure unable to control a known risk: that of microbial contamination of water supplies.     

Defining Dangerous Anthropogenic Interference: The Role of Science, the Limits of Science

Defining "dangerous anthropogenic interference with the climate system" in the context of Article 2 of the UN Framework Convention on Climate Change (UNFCCC) presents a complex challenge for those developing long-term climate policy. Natural science has a key role to play in quantifying vulnerabilities of elements of the Earth system and estimating the risks from a changing climate. But attempts to interpret Article 2 will inevitably draw on understanding from social science, psychology, law, and ethics. Here I consider the limits of science in defining climate "danger" by focusing on the potential disintegration of the major ice sheets as an example of an extreme impact. I show that considerations of timescale, uncertainty, and learning preclude a definition of danger drawn purely from natural science. Decision makers will be particularly challenged by one characteristic of global problems: answers to some scientific questions become less accurate over decadal timescales, meandering toward the wrong answer, a feature I call negative learning. I argue for a precautionary approach to Article 2 that would be based initially on current, limited scientific understanding of the future of the ice sheets.     

基于协同救助的海上救助报酬合理分配方法

海上救助报酬是为鼓励人们冒险参与海上救援,由受益人给予救助人的补偿和回报,具有射幸性,奉行“无效果、无报酬”的给付原则。本文以救助方成本性和非成本性投入对救助效果的贡献为依据,首先对各方的成本性投入进行补偿;然后从资源要素的关键性和参与人的重要性两个维度对各救助方的贡献进行综合评价,并按贡献度对“剩余”部分进行二次分配,两次分配之和即为各救助方所获得的分配总额。通过运用“重购成本”和Shapley值法分别对资源要素的关键性和参与人的重要性进行客观度量,该方法可同时解决共同救助报酬的外部分配与内部分配问题,不仅避免了目前各国司法实践中按成本投入比例进行分配的不合理性,也更能体现相关国际公约和国内立法有关救助报酬分配的原则。     

Ho-Lee利率模型下带有零息票债券的投资-消费模型

在随机利率环境下研究一类带有零息票债券的投资-消费问题,其中假设无风险利率是服从Ho-Lee利率模型的随机过程,且金融市场由一种无风险资产、一种风险资产和一种零息票债券所构成。投资人希望选择一种最优投资-消费策略来最大化其有限时间段内终端财富和累积消费的期望效用。文章应用动态规划原理和变量替换方法得到了幂效用和对数效用下最优投资-消费策略的显示解。算例分析演示了最优投资-消费策略随市场参数的变化而变化的动态行为,并给出了一些经济学涵义。     

Societal Response to Hurricane Mitch and Intra‐ versus Intergenerational Equity Issues: Whose Norms Should Apply?

Late in the 1998 hurricane season, Central America was slammed by a devastating hurricane. Honduras, Nicaragua, El Salvador, Guatemala, and Belize were greatly impacted by Hurricane Mitch, one of the deadliest storms to affect the region in the past 200 years. The economies of each of these countries were badly affected. In the case of Honduras — at the time the fourth‐poorest country in Latin America — its president suggested that 50 years of progress had been wiped out by the floods and mudslides associated with this relatively short‐lived storm system. Humanitarian assistance poured into the region in the first months following the disaster. As of mid‐2000, various national, bilateral, international, and nongovernmental programs were in progress or on the drawing board for recovery, reconstruction, and renewed development of the worst affected countries. Using Honduras as a case study, some of the ethical issues that abound in the decisions of whom to help, when, and how to help them in the wake of such an extreme climate‐related human tragedy are examined. Should development assistance be focused on those who have been directly and adversely affected by this storm, or should the emphasis be on reducing the risk of exposure by future generations to such disasters? Is there yet another approach that seeks to protect future generations from similar harm while at the same time assisting present‐day victims to get through their hardships?     

关于新型期权及其定价模型的研究

本文剖析了新型期权的生成机理和主要特征,由此归纳出新型斯权的主要类型.在标准期权定价模型的基础上,深入讨论了各类新型期权的定价模型,并重点研究了路径依赖型期权的定价问题,创建了包含路径因子在内的定价模型,最后对多因素新型期权的定价进行了展望.     

面向复杂性:和谐管理理论的概念、原则及框架

从传统管理面临的困境入手,分析了和谐管理理论提出的必要性,对和谐管理理论的概 念、原则和基础框架进行了阐释. 从和谐主题出发,选择优化和不确定性消减的问题解决方式, 构成和谐管理理论认识论和方法论的基本特征. 在上述分析的基础上,提出了一个系统的和谐 管理分析框架.     

An optimal selection of two-level regular single arrays for robust parameter experiments

Efforts have been made in the literature to find optimal single arrays which work best for the robust parameter experiments. However, examples show that in many cases the optimal designs obtained by the existing criteria cloud not attain the maximum number of clear interested effects for robust parameter experiments. In this paper, through a similar way of Zhang et al. (2008) (ZLZA, in short), an aliasing pattern to measure the confounding between the interested effects and other effects for the case of robust parameter designs is introduced. A new criterion for selecting optimal two-level regular single arrays is proposed. In the consideration of the criterion, two rank-orders of effects are suggested: one is based on the interest of experimenters and the other is under the usual effect hierarchy principle. The optimal designs are tabulated in the appendix.     

Kumulation von Mikrodaten – Konzeptionelle Grundlagen und ein Vorschlag zur Realisierung

Zusammenfassung: In dieser Studie wird ein Konzept zur Kumulation von laufenden Haushaltsbudgetbefragungen im Rahmen des Projektes Amtliche Statistik und sozioökonomische Fragestellungen entwickelt und zur Diskussion gestellt. Dafür werden die theoretischen Grundlagen und Bausteine gelegt und die zentrale Aufgabe einer strukturellen demographischen Gewichtung mit einem Hochrechnungs–/Kalibrierungsansatz auf informationstheoretischer Basis gelöst.Vor dem Hintergrund der Wirtschaftsrechnungen des Statistischen Bundesamtes (Lfd. Wirtschaftsrechnungen und EVS) wird darauf aufbauend ein konkretes Konzept für die Kumulation von jährlichen Haushaltsbudgetbefragungen vorgeschlagen. Damit kann das Ziel einer Kumulation von Querschnitten mit einer umfassenderen Kumulationsstichprobe für tief gegliederte Analysen erreicht werden. Folgen sollen die Simulationsrechnungen zur Evaluation des Konzepts.

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Summary: In this study a concept for cumulating periodic household surveys within the frame of the project Official Statistics and Socio–Economic Questions is developed and asks for discussion. We develop the theoretical background and solve the central task of a structural demographic weighting/calibration based on an information theoretical approach.Based on the household budget surveys of the Federal Statistical Office (Periodic Household Budget Surveys and Income and Consumption Sample (EVS)) a practical concept is proposed to cumulate yearly household surveys. This allows a cumulation of cross–sections by a comprehensive cumulated sample for deeply structured analyses. In a following study this concept shall be evaluated.

     

On three and four vicious walkers

We establish a reflection principle for three lattice walkers and use this principle to reduce the enumeration of configurations of three vicious walkers to the enumeration of configurations of two vicious walkers. More precisely, the reflection principle leads to a bijection between three walks (L₁, L₂, L₃) such that L₂ intersects both L₁ and L₃ and three walks (L₁, L₂, L₃) such that L₁ intersects L₃. Hence we find a combinatorial interpretation of the formula for the generating function for the number of configurations of three vicious walkers, originally derived by Bousquet-Mélou by using the kernel method, and independently by Gessel by using tableaux and symmetric functions. This answers a question posed by Gessel and Bousquet-Mélou. We also find a reflection principle for four vicious walks that leads to a combinatorial interpretation of a formula derived from Gessel's theorem.