Evolution of social learning when high expected payoffs are associated with high risk of failure

In an environment where the availability of resources sought by a forager varies greatly, individual foraging is likely to be associated with a high risk of failure. Foragers that learn where the best sources of food are located are likely to develop risk aversion, causing them to avoid the patches that are in fact the best; the result is sub-optimal behaviour. Yet, foragers living in a group may not only learn by themselves, but also by observing others. Using evolutionary agent-based computer simulations of a social foraging game, we show that in an environment where the most productive resources occur with the lowest probability, socially acquired information is strongly favoured over individual experience. While social learning is usually regarded as beneficial because it filters out maladaptive behaviours, the advantage of social learning in a risky environment stems from the fact that it allows risk aversion to be circumvented and the best food source to be revisited despite repeated failures. Our results demonstrate that the consequences of individual risk aversion may be better understood within a social context and suggest one possible explanation for the strong preference for social information over individual experience often observed in both humans and animals.     

天然气管道安全运行危害因素及防范措施

分析了天然气管道安全运行的危害因素，从设计和施工方面提出了防范措施。     

后京都时代到来之前CDM项目开发运营的应对策略

后京都时代CDM市场的形势不明朗,我国CDM项目的主要参与方如何应对,关系到其切身利益.以实务操作为视角,各参与方迫切需要从把握碳市场的国际形势、加强项目开发运营管理能力建设、注重减排量购买协议中法律风险防范、关注国内碳交易市场建设等多方面入手,有效应对新形势下CDM项目的开发运营工作.     

Winning and positive affect can lead to reckless gambling.

Experiments 1 and 2 examined whether winning versus losing led to reckless betting for real prize money. Experiment 2 also assessed whether positive or negative emotions were linked to such reckless betting. College students were randomly assigned to experience primarily either wins or losses during the rigged first round of a computerized card tournament that had 2 independent rounds. For the second round, participants’ chip totals were reset and cards were dealt randomly. In Experiment 1 (N = 107), participants in the Initial-Winning, as compared with the Initial-Losing, condition bet more recklessly (i.e., bet too many chips when a loss was likely). Experiment 2 (N = 72) again showed that Initial-Winning participants bet significantly more recklessly than did Initial-Losing participants. It also revealed that positive affect was significantly positively correlated with such reckless betting. These findings have implications for understanding how college students, those at an age when they are especially vulnerable to problem gambling, can come to lose more money than they can afford. Initially winning and positive affect when gambling could be risk factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

保单驱动索赔离散风险模型的精算量分布

研究了一类索赔是由保单驱动的带随机利率的离散时间非寿险风险保险模型,证明了该模型的盈余首次超过给定水平的时间、破产前最大盈余、破产持续时间以及盈余首次回复为正后的瞬间值等精算量的分布都可以由一类积分方程的唯一解给出。     

马池煤矿11041回采工作面首采段消突技术实践

马池煤矿11041回采工作面为突出危险工作面,在掘进期间采取综合防突措施,保证了掘进安全;为保证回采安全,首先对首采段进行了顺层钻孔预抽,以消除突出危险性,该方法行之有效。     

Predictors of high-risk alcohol consumption in young offenders on community orders: Policy and treatment implications.

The present study examined the relationship between a set of individual and contextual variables and high-risk alcohol use among young offenders placed on community orders in New South Wales, Australia. Participants (n = 777) were compared on a set of factors known to be strong predictors of high-risk alcohol use among adolescents. The authors assessed the strength of the relationship between gender, age, ethnicity, geographical region of residence, school attendance, father absence, history of childhood trauma, and the presence of severe conduct disorder on weekly levels of alcohol use. Living in rural locations, not currently attending school, being female, and not having been raised with a biological father present were associated with significantly increased odds of alcohol abuse. Father absence was a more important risk factor for rural young offenders, but school dropout was associated with more hazardous drinking among young offenders in urban areas. Accordingly, the authors suggest family-focused intervention programs for young offenders living in rural areas and school-based programs for vulnerable young people living in urban areas, although programs should consider including both factors for both groups if feasible and warranted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

分包商在国际工程承包中的风险及应对措施

从分包商这一角色出发，结合从事海外工程的经验对国际工程承包市场中的风险进行了论述和分析，有针对性地提出了一些应对措施，为企业在国际市场上如何进行风险管理提供了宝贵的经验。     

A Genetic‐Based Iterative Quantile Regression Algorithm for Analyzing Fatigue Curves

Accurate prediction of fatigue failure times of materials such as fracture and plastic deformation at various stress ranges has a strong bearing on practical fatigue design of materials. In this study, we propose a novel genetic‐based iterative quantile regression (GA‐IQR) algorithm for analyzing fatigue curves that represent a nonlinear relationship between a given stress amplitude and fatigue life. We reduce the problem to a linear framework and develop the iterative algorithm for determining the model coefficients including unknown fatigue limits. The procedure keeps updating the estimates in a direction to reduce its resulting error. Also, our approach benefits from the population‐based stochastic search of the genetic algorithms so that the algorithm becomes less sensitive to its initialization. Compared with conventional approaches, the proposed GA‐IQR requires fewer assumptions to develop fatigue model, capable of exploring the data structure in a relatively flexible manner. All procedures and calculations are quite straightforward, such that the proposed quantile regression model has a high potential value in a wide range of applications for exploring nonlinear relationships with lifetime data. Computational results for real data sets found in the literature present good evidences to support the argument. Copyright © 2012 John Wiley & Sons, Ltd.