Divorce in common murres (Uria aalge): relationship to parental quality

Behavioral precursors of 12 divorces were examined in 30 color-banded pairs of common murres (Uria aalge) over six breeding seasons. Common murres are long-lived seabirds that typically return each year to the same mate and nest site in dense colonies. At least one parent is present continuously from egg lay to chick fledging. Murres, therefore, have considerable opportunities to compare their mates parental behavior with that of several familiar neighbors. Previous reproductive success was lower for divorcing birds than for reuniting pairs. As predicted by the better option hypothesis, there were clear choosers (seven females and five males) that initiated divorce by moving to a new birds site or by courting a new partner at their current site. Choosers improved their reproductive success after the divorce, whereas their previous partners, the victims did not. Yearly divorce rates (average 8.2% per year) were significantly correlated with yearly mortality rates. Divorces appear to be opportunistic: pairs divorced after varying numbers of reproductive failures with the immediate precursor usually being the disappearance (death) of a murre from a successful neighboring site. In contrast to the delays experienced by victims, choosers formed new pairs quickly and laid their eggs no later than reuniting pairs. Prior to the divorce, victims fed their chicks less often than choosers, and some engaged in other behaviors that compromised egg or chick survival. These observations suggest that deficiencies in parental behavior were precursors to the divorce. This report is one of the first cases where reproductive failure of divorcing pairs has been linked to deficits in the parental behavior of the subsequent divorce victim.Communicated by C. Brown     

期权理论在排污权初始分配中的应用

排污权交易是当前总量控制目标下最具潜力的环境政策,它兼有环境质量保障和成本效率优化的特点.在对国内外排污权交易和初始分配充分考察的基础上,提出了在排污权初次分配中引入期权机制的尝试,并对这种方法的理论基础作了分析和讨论.     

基于价格随机Faustmann模型的最优轮伐期决策方法及演进

可持续森林经营是应对气候变化的重要途径,最优轮伐期决策是可持续森林经营的重要条件。由于经典Faustmann模型关于林木生长和市场价格的静态假设在现实中无法得到满足,有必要使用动态模型根据市场状况灵活决策,从而在价格波动的市场中实现利润最大化的目标。作者以Faustmann模型经典框架为基础,归纳Faustmann模型的起源及演进,梳理随机价格问题在最优轮伐期决策上的研究动态。结果表明：①在现代资本市场理论中,随机过程是描述价格波动的重要模型,主要包括符合有效市场假说的几何布朗运动或符合完全竞争市场假设的均值回复过程,此外也可以基于经验价格数据的检验使用更为复杂的随机过程模型。②贴现现金流多用于静态Faustmann模型分析,但忽略了新信息对于决策的影响,而实物期权分析允许林地所有者进行动态分析,在每个决策点比较立即采伐与延迟采伐的预期收益、并根据市场状况随时调整经营策略以在风险中获利。③以即期收益价值与连续收益价值最大化为目标的贝尔曼方程是求解价格随机Faustmann模型的有效方法,而构建偏微分方程、蒙特卡洛模拟和马尔可夫决策过程则分别可以在价格服从正态分布、具有多个随机价格和价格具有马尔可夫性时有效求解贝尔曼方程。随机价格问题未来在最优轮伐期决策中的研究趋势还涉及以下几个方面：将Faustmann模型在气候变化背景下扩展至完整林业碳汇效益、使用包含机器学习在内的多种方法对木材及碳汇价格波动进行更加精确和合理的建模、在Faustmann模型中考虑包含资源风险和决策者偏好风险在内的多个风险来源。     

基于资源最优化回收的再制造工程

从对寿命末端产品的处理选择分析出发，建立了末端产品回收梯级模型，提出基于最优化产品末端回收选择的再制造工程回收的附加值最大，环境污染最小，综合效益最高，并分析了再制造在产品全寿命周期各阶段所发挥的重要作用。     

对应RoHS指令的体制提案

本文提出了对应RoHS的体制提案,供参考.     

A Proactive Approach Can Make Site Remediation Less Expensive

Without any incentive to clean up a contaminated site, remediation is often delayed until the site owner is compelled to act by regulatory agencies. In such a context, the selected technology is typically the one that will reach the remediation goals as quickly as possible. Unfortunately, this criterion is often met by overly expensive technologies, resulting in high and sometimes unaffordable total remediation costs, leading to a remediation with a negative net benefit. This study examines the effects of time constraint and benefit value on the optimal remediation strategy for a diesel-contaminated site. This strategy is developed using the technico-economic model METEORS, which takes into account the technology’s effectiveness, the uncertainty of the level of contamination, and the possibility of reducing this uncertainty through either an additional characterization (before selecting and applying a technology) or the monitoring of the remediation technology (during its use). Results of simulations with both economic and temporal constraints support a proactive approach to site remediation.     

洞庭湖湿地生态系统管理面临的威胁及应对策略初探

生态系统管理可以实现自然资源的多目标管理。洞庭湖湿地生态系统优越,区域内社会经济发达,但面临保护与发展的双重压力。其中,开展洞庭湖区湿地生态系统管理面临众多威胁,包括自然灾害频发、资源利用不当、工农业污染突出、自然保护能力不足以及季节性缺水等新老问题交织在一起,共同导致了洞庭湖湿地生态系统功能降低,包括生物多样性降低、调蓄能力减弱、洪渍涝灾害加剧、地下水位升高、垸老田低等现象日益突出,而且这种人类不合理活动的后效放大驱动将长期存在,危及到了湖区水产养殖的自然增殖以及自然资源基础的安全性,成为湖区社会经济发展的严重制约因素。为此,建议在遵循生态系统方法的前提下,洞庭湖地区应该加强管理体制机制创新实践,加快湿地保护的立法与执法进程,通过编制洞庭湖区中长期发展总体规划,促进各种利益相关方参与和共管洞庭湖湿地退田还湖等生态恢复工程的巩固、湿地资源合理利用、湿地产业的开发以及湖区湿地生态与环境建设,最终实现湖区生态美好、民生改善的“人地和谐