Are naked and common mole-rats eusocial and if so, why?

Eusociality in mammals is defined in the present paper by the following criteria: reproductive altruism (which involves reproductive division of labor and cooperative alloparental brood care), overlap of adult generations, and permanent (lifelong) philopatry. We argue that additional criteria such as the existence of castes, colony size, reproductive skew, and social cohesion are not pertinent to the definition of eusociality in mammals. According to our definition of mammalian eusociality, several rodent species of the African family Bathyergidae can be considered eusocial, including the naked mole-rat (Heterocephalus glaber), Damaraland mole-rat (Cryptomys damarensis), and several additional, if not all, species in the genus Cryptomys. Furthermore, some species of social voles (like Microtus ochrogaster) may also fulfill criteria of mammalian eusociality. Understanding the evolution of eusociality in mole-rats requires answers to two primary questions: (1) What are the preconditions for the development of their eusocial systems? (2) Why do offspring remain in the natal group rather than dispersing and reproducing? Eusociality in mammals is by definition a special case of monogamy (more specifically: monogyny one female breeding), involving prolonged pair bonding for more than one breeding period. We argue that eusociality in mole-rats evolved from a monogamous mating system where cooperative brood care was already established. A tendency for group living is considered to be an ancestral (plesiomorph) trait among African bathyergid mole-rats, linking them to other hystricognath rodents. A solitary lifestyle seen in some genera, such as Bathyergus, Georychus, and Heliophobius, is assumed to be a derived trait that arose independently in different lineages of bathyergids, possibly as a consequence of selective constraints associated with the subterranean environment. In proximate terms, in eusocial mole-rats either puberty is assumed to be developmentally delayed so that under natural conditions most animals die before dispersal is triggered (e.g., in the case of Heterocephalus) or dispersal is induced only by an incidental encounter with an unfamiliar, yet adequate sexual partner (e.g., in the case of Cryptomys). Ultimately, a combination of strategies involving either dispersal and/or philopatry can be beneficial, especially in a highly unpredictable environment. If genetic relatedness among siblings is high (e.g., a coefficient of relatedness of 0.5 or more), then philopatry would not invoke an appreciable loss of fitness, especially if the cost of dispersing is higher than staying within the natal group. High genetic relatedness is more likely in a monogamous mating system or a highly inbred population. In this paper, we argue that the preconditions for eusociality in bathyergid mole-rats were a monogamous mating system and high genetic relatedness among individuals. We argue against the aridity food-distribution hypothesis (AFDH) that suggests a causal relationship between cooperative foraging for patchily distributed resources and the origin of eusociality. The AFDH may explain group size dynamics of social mole-rats as a function of the distribution and availability of resources but it is inadequate to explain the formation of eusocial societies of mole-rats, especially with respect to providing preconditions conducive for the emergence of eusociality.     

Does information of predators influence general wariness?

Antipredator behavior includes several qualitatively distinct activities, but few studies have determined the degree to which these activities are independent. If behaviors are not independent, then the nature of the relationship would illustrate potential performance constraints. We studied crimson rosellas (Platycercus elegans) and first focused on acoustic predator discrimination. We measured time allocation before and after playback of one of three experimental treatments (peregrine falcons—Falco peregrinus, wedge-tailed eagles—Aquila audax, and crimson rosellas) to determine whether or not rosellas discriminated predators from non-predators, and specifically whether or not they discriminated large from small predators. We then focused on the decision to flee. We experimentally approached subjects and measured the distance at which they oriented to us (alert distance) and the distance at which they fled (flight initiation distance; FID). We found that rosellas could distinguish among predators; however, there was no effect on general wariness as measured by FID. These two processes of antipredator behavior may, thus, be independent.     

基于放射源理论的区域生态系统评价方法

研究区域生态系统定量评价方法对区域生态系统的建设与保护具有十分重要的意义。从放射源理论出发,首次将生态影响距离、生态源及生态影响效应的概念引入分析评价中,提出了区域生态系统的定量评价方法,并建立了基于景观空间格局的区域生态系统生态影响的定量计算公式。甘垛镇新庄片和横泾镇沿荡片的应用实例表明,该方法原理简明、结果直观,为区域生态系统的科学评价提供了定量评价方法。     

湿式煤气柜施工安全措施的制订

针对正在运行的湿式煤气柜防火间距不够的位置动火建造大10倍的湿式煤气柜的实际情况,采取现场调查、安全系统分析,制订切实可行的措施,顺利完成施工任务。     

One-step estimation method and nomogram to predict safety distances of pressurized gas pipelines from blast sources

Pressurized gas pipelines may be endangered by accidental or intentional activities causing excess ground vibrations leading to failure. Thus, many papers have been published on this issue, yet most of these efforts suffer from complexity and inability to ascertain that all engaged factors are taken into account. These factors are attributed, namely, to explosion source, explosion-ground interaction, energy transfer through the ground, ground-pipeline interaction, and response of the pipeline. The deterministic method developed previously by the author has derived useful prediction mathematical formulas that can be used to calculate, either the stand-off distance of purposefully used explosives, or the maximum quantity of explosives to be used at a given distance, or the equivalent stress of a pipeline induced by an explosive charge at a given standoff distance. The method can also be applied to accidental blast events in factories or other activities. Yet, the complex formulas developed are hard to be used in the field and a simpler approach is needed to facilitate and accelerate in-field estimations. Thus, a nomogram was prepared to make the safety estimations easy and fast and taking into account all engaged critical factors starting from the explosion source through the integrity of the structure.     

Insight into the safety distance of ground and underground installations in typical petrochemical plants

Petrochemical plants are continuously turning into large-size corporations, the installations of facilities show a developing trend from ground to underground because of the difference in land using rate. In this regard, the safety distance of petrochemical equipment buried in both ground and underground cases were investigated based on risk assessment. As a case study, gasoline tank and LPG tank set on the ground and underground are singled out to compare the risks involved. The research showed that the setting case of installation had a great influence on safety distance. Two cases have 80% reduction of equivalent safety distance compared with the rest of the cases. It was found that when the gasoline storage tank was placed underground alone, the PLL value decreased by 36.7%. Only LPG tank was placed underground, and the PLL decreased by 6.33%, and the gasoline and LPG storage tanks were placed underground simultaneously, the PLL value declined by 42.3%. Thus, the layout of plants could be further optimized, which can greatly improve the performances of land use efficiency and safety. In addition, this paper, the selection of embedding methods and the sensitivity of underground case to overpressure was resumed from two aspects: soil properties and burial depth. For the soil properties, it was found that the water saturated sandy soil with high air content and the low density unsaturated sandy soil had better effects on weakening overpressure. Such properties are particularly beneficial to reducing the occurrence rate of accidents. In terms of burial depth, it can be observed that as the burial depth was changed from 0.5m to 1.1m, the value of overpressure has dropped dramatically. When the burial depth was 2m, the damage to personnel and buildings has been greatly reduced beyond 2m from the explosion center.     

考虑驾驶员反应时间的车辆碰撞预警模型

为了保证车辆在行驶过程中的安全性,提出了一种考虑驾驶员反应时间的车辆碰撞预警模型,改进了传统模型中驾驶员反应时间定值化的缺点。首先,依据车辆的制动过程分析了驾驶员反应时间对制动距离的影响。其次,设计驾驶员反应时间的模糊推理算法,选取驾龄、疲劳强度和应变能力3个主要因素作为评价指标来计算反应时间。最后,采用分等级的预警策略建立考虑驾驶员反应时间的碰撞预警模型,并通过Carsim-Matlab/Simulink联合仿真与传统模型进行对比分析。结果表明,设计的预警模型可以对不同类型的驾驶员进行差异化碰撞预警,在30 km/h和80 km/h两种车速下实际停车距离与理论值的最大误差为8%。     

碳排放交易制度下城市减排的机会成本研究——基于中国碳排放试点城市的实证检验

作为全球气候治理的重要手段,碳排放交易制度受到了广泛的关注与讨论。基于此,本文采用我国2010-2016年城市面板数据,运用非参数方法构建方向性环境距离函数测算了2009-2015年城市减排的机会成本,计算结果显示,试点地区与非试点地区的碳排放的机会成本整体表现为上升的趋势,且试点地区的碳排放的机会成本总体低于非试点地区。在测算城市减排机会成本的基础上,运用双重差分法来检验碳排放交易制度的有效性。经检验发现：碳排放交易制度有利于降低城市减排的机会成本,然而由于碳排放交易制度还存在碳排放权初始分配制度缺失、碳排放交易制度的定价机制扭曲等问题,因此其对降低城市减排的机会成本作用较小,并且进一步通过对政策时间趋势的分析得出政策效应随时间推移而逐渐减弱。