Numerical analysis of non-constant pure rate of time preference: A model of climate policy

When current decisions affect welfare in the far-distant future, as with climate change, the use of a declining pure rate of time preference (PRTP) provides potentially important modeling flexibility. The difficulty of analyzing models with non-constant PRTP limits their application. We describe and provide software (available online) to implement an algorithm to numerically obtain a Markov perfect equilibrium for an optimal control problem with non-constant PRTP. We apply this software to a simplified version of the numerical climate change model used in the Stern Review. For our calibration, the policy recommendations are less sensitive to the PRTP than widely believed.     

When is a male not a male? Sex recognition and choice in two sex-changing species

For dioecious species, choosing a mate of the same sex can have reproductive costs. For sex-changing animals, however, a lack of sex recognition may not carry a reproductive cost, as pairs that were initially same-sex can become opposite-sex pairs as one partner changes sex. The strength of sex discrimination in sex changers, then, should depend on the duration of mating associations and whether the time of sex change is influenced by social situation (“flexible” sex change). We studied two species of marine snails that change sex from male to female, one with flexible sex change and long-term or permanent mating associations (Crepidula fornicata) and one with short-term pairings and relatively fixed time of sex change (Crepidula convexa), to determine whether either species exhibits sex recognition and whether members of C. convexa show stronger sex discrimination. In laboratory experiments, small males, the choosing animals, were placed with either a male or a female conspecific (no-choice experiments) or given a choice of a male or female (choice experiments). We controlled for shell length in all experiments, as relative size may influence sex change or choice. Males of both species paired more often with females than males, but, as predicted, males of C. convexa showed stronger discrimination: When given a choice, no C. convexa male paired with another male. In contrast, some C. fornicata males always chose other males even when given the choice of a female. These results suggest that sex recognition can be adaptive even for sex changers but demonstrate that the level of sex recognition will depend on other aspects of reproductive behavior.     

微重力波动与燃烧温度变化的研究

本文通过试验飞机抛物线飞行进行了微重力燃烧实验,采集得到微重力条件下一个采样点微重力波动和燃烧温度变化的数据,在此基础上将时间序列预测和神经网络相结合进行了微重力波动与燃烧温度变化的研究,揭示了试验飞机抛物线飞行中微策略波动和采样点燃烧温度变化的规律。     

Estimating the total exposure to air pollutants for different population age groups in Hong Kong

Given that Hong Kong is one of the most densely populated cities in the world, the exposure of the Hong Kong people is one of the interesting research areas. In this study, an indirect approach was used to estimate the exposure to nitrogen dioxide (NO2), respiratory dust (PM10) and carbon monoxide (CO) pollutants experienced by different age groups of people in Hong Kong. The average concentrations of the 20 major microenvironments obtained from our measurement survey data, together with the people activity pattern data obtained from 7-day recall questionnaires, were used to predict frequency distributions to exposure assessment. Our results showed that Hong Kong people spent more than 86% of their time indoors. Homes were shown to be the one of the major exposure sites to NO2, CO and PM10 for all age groups. Our results also indicate that the 24-h NO2 exposure for individuals, irrespective of age, spending more than 2 h in commuting daily, was observed to be exceeding the 24-h NO2 exposure standards. This study was one of the pioneering studies with valuable contribution for modeling the estimates of exposures to NO2, PM10 and CO of different age groups in Hong Kong.     

我国潜在顾客对城市美食的偏好与影响因素研究--基于网络关注度视角

通过收集网络关注度等数据,利用赫芬达尔—赫希曼指数、皮尔逊相关系数、多元回归分析等方法分析了我国31个省份潜在顾客对10个典型城市美食的偏好与影响因素。结果发现:①同一性别、年龄和地区的潜在顾客对不同城市美食偏好程度均不同,男性潜在顾客对美食的偏好程度略高于女性潜在顾客,美食的潜在顾客以中青年为主。②不同性别、年龄和地区的潜在顾客对同一城市美食的偏好也存在明显差异。③人们对美食的偏好程度与可支配收入之间存在正相关关系,与空间距离之间存在负相关关系。④地域文化、宗教信仰、气候等因素也会对潜在顾客的美食偏好产生影响。     

鄱阳湖流域天然径流变化特征与水旱灾害

为探讨鄱阳湖流域河川径流的变化过程和规律,深入了解径流特征及其与鄱阳湖水旱灾害的关系,利用时间序列分析方法,对鄱阳湖流域五河水系干流河段主要控制水文测站的天然径流系列进行了研究。研究显示,鄱阳湖五河径流年内分配集中程度在0.43到0.56之间,集中期为每年的5月底6月初,比鄱阳湖汛期提前1-2个月。径流多年变化变差系数变化在0.28～0.33之间,径流年际变率较大,在年代际变化上20世纪90年代径流增加尤其突出;径流序列呈长期的增加趋势,1998年后增加趋势变缓;鄱阳湖流域五河水系出现特大枯水年和丰水年的概率较大,出现平水年的概率略小。以上结果表明,五河汛期来水是影响鄱阳湖洪水的重要因素,而其形成、发展过程还受到长江中上游洪水的控制;径流的长期变化中,气候因素是引起鄱阳湖流域径流变化主导因素,水土流失和水利工程的建设等人为因素起着一定的辅助作用;径流序列枯、丰循环周期的交替变化过程,与过去几十年间流域内出现的干旱、洪水现象具有较好的一致性。     

The use of proactive risk management to reduce emergency service vehicle crashes among firefighters

IntroductionEmergency service vehicle crashes (ESVCs), including rollovers and collisions with other vehicles and fixed objects, are a leading cause of death among U.S. firefighters. Risk management (RM) is a proactive intervention to identifying and mitigating occupational risks and hazards. The goal of this study was to assess the effect of RM in reducing ESVCs. Methods: Three fire departments (A, B and C), representing urban and suburban geographies, and serving medium to large populations, participated in facilitated RM programs to reduce their ESVCs. Interventions were chosen by each department to address their department-specific circumstances and highest risks. Monthly crash rates per 10,000 calls were calculated for each department an average of 28 months before and 23 months after the start of the RM programs. Interrupted time series analysis was used to assess the effect of the RM programs on monthly crash rates. Poisson regression was used to estimate the number of crashes avoided. Economic data from Department A were analyzed to estimate cost savings. Results: Department A had a 15.4% (P = 0.30) reduction in the overall monthly crash rate immediately post-RM and a 1% (P = 0.18) decline per month thereafter. The estimated two-year average cost savings due to 167 crashes avoided was $253,100 (95%CI= $192,355 – $313,885). Department B had a 9.7% (P = 0.70) increase in the overall monthly crash rate immediately post-RM and showed no significant changes in their monthly crash rate. Department C had a 28.4% (P = 0.001) reduction in overall monthly crash rate immediately post-RM and a 1.2% (P = 0.09) increase per month thereafter, with an estimated 122 crashes avoided. Conclusions: RM programs have the potential to reduce ESVCs in the fire service and their associated costs; results may vary based on the interventions chosen and how they are implemented. Practical applications: Risk management may be an effective and broadly implemented intervention to reduce ESVCs in the US fire service.     

EFFECTS OF SALINITY ON PREFERRED AND LETHAL TEMPERATURES OF THE BLACKCHIN TILAPIA,SARATHERODON MELANOTHERON1

Acclimation to varying salinities did not affect the preferred temperature of Saratherodon melanotheron, which had a final preferred temperature of 33.5 C. However, fish acclimated to 25 C and 0, 15, and 30 o/oo salinities had lower lethal temperatures of 15, 13, and 15 C, respectively, and an upper lethal temperature of 37 C. The thermal zone of tolerance for fish acclimated in freshwater was 17-35 C, and was not dependent upon acclimation temperatures. Data suggest this species could expand its range in North America.     

TEMPERATURE BEHAVIOR OF THE BLUESPOTTED SUNFISH ENNEACANTHUS GLORIOSUS (HOLBROOK), WITH AN EVALUATION OF THE INTERPRETATION OF THERMAL BEHAVIOR DATA1

The bluespotted sunfish, Enneacanthus gloriosus (Holbrook), had a final temperature preferendum of 31.5 C. Fish acclimated to 30 C avoided 36 C. The analysis of acute temperature preference data and the relationship between final temperature preferendum and upper avoidance temperatures are discussed.