Joint Effects of Inbreeding and Local Adaptation on the Evolution of Genetic Load after Fragmentation

Abstract: Disruption of gene flow among demes after landscape fragmentation can facilitate local adaptation but increase the effect of genetic drift and inbreeding. The joint effects of these conflicting forces on the mean fitness of individuals in a population are unknown. Through simulations, we explored the effect of increased isolation on the evolution of genetic load over the short and long term when fitness depends in part on local adaptation. We ignored genetic effects on demography. We modeled complex genomes, where a subset of the loci were under divergent selection in different localities. When a fraction of the loci were under heterogeneous selection, isolation increased mean fitness in larger demes made up of hundreds of individuals because of improved local adaptation. In smaller demes of tens of individuals, increased isolation improved local adaptation very little and reduced overall fitness. Short‐term improvement of mean fitness after fragmentation may not be indicative of the long‐term evolution of fitness. Whatever the deme size and potential for local adaptation, migration of one or two individuals per generation minimized the genetic load in general. The slow dynamics of mean fitness following fragmentation suggests that conservation measures should be implemented before the consequences of isolation on the genetic load become of concern.     

危化品道路运输事故应急救援中心选址模型研究

为快速提高危化品道路运输事故应急救援能力,降低事故后果,文章基于目前应急救援中心选址模型的不足,提出了一种新的双目标决策救援中心选址模型。通过综合考虑应急响应时间及应急处理能力对救援能力的影响,建立了救援中心点的最大网络覆盖模型;并采用较优的邻域搜索算法求解救援中心点的合理位置。最后以某地危化品运输路网为例,利用所建模型对事故应急救援中心的合理布局计算求解。结果表明:考虑应急响应时间及应急处理能力限制的应急救援中心选址模型,能够有效提高救援中心的综合应急能力,为有关部门合理规划危化品道路运输事故应急救援中心布局提供理论参考和决策依据。     

Predicting the Probability of Outbreeding Depression

Abstract: Fragmentation of animal and plant populations typically leads to genetic erosion and increased probability of extirpation. Although these effects can usually be reversed by re‐establishing gene flow between population fragments, managers sometimes fail to do so due to fears of outbreeding depression (OD). Rapid development of OD is due primarily to adaptive differentiation from selection or fixation of chromosomal variants. Fixed chromosomal variants can be detected empirically. We used an extended form of the breeders’ equation to predict the probability of OD due to adaptive differentiation between recently isolated population fragments as a function of intensity of selection, genetic diversity, effective population sizes, and generations of isolation. Empirical data indicated that populations in similar environments had not developed OD even after thousands of generations of isolation. To predict the probability of OD, we developed a decision tree that was based on the four variables from the breeders’ equation, taxonomic status, and gene flow within the last 500 years. The predicted probability of OD in crosses between two populations is elevated when the populations have at least one of the following characteristics: are distinct species, have fixed chromosomal differences, exchanged no genes in the last 500 years, or inhabit different environments. Conversely, the predicted probability of OD in crosses between two populations of the same species is low for populations with the same karyotype, isolated for <500 years, and that occupy similar environments. In the former case, we recommend crossing be avoided or tried on a limited, experimental basis. In the latter case, crossing can be carried out with low probability of OD. We used crosses with known results to test the decision tree and found that it correctly identified cases where OD occurred. Current concerns about OD in recently fragmented populations are almost certainly excessive.     

Thermal Strain in Fire Fighters While Wearing Task-Fitted Versus EN 469:2005 Protective Clothing During a Prolonged Rescue Drill

Fire fighters are normally overprotected during their working hours because of the tendency to keep the personal protection level sufficiently high in case of the worst possible scenarios. This study investigated the effects of task-fitted protective clothing on thermal strain in fire fighters as compared to EN 469:2005 protective clothing during a prolonged (2 1/2 hrs) job-related rescue drill under neutral and hot climates. The subjects were 23 healthy, physically fit professional male fire fighters aged 26–44 years. Measurements included cardiovascular and thermal responses and subjective assessments. Wearing task-fitted clothing during rescue tasks in a neutral climate considerably reduced total thermal and cardiovascular strain in prolonged rescue work. The fire fighters also perceived physical work as significantly harder on average, and reported more intense subjective discomfort while wearing EN 469:2005 as compared to task-fitted clothing.     

基于井下避难硐室系统的煤矿应急救援体系探讨

本文在分析我国煤矿应急救援现状和简单介绍煤矿避难硐室的定义和功能的基础上,分析了建立我国基于井下避难硐室系统的煤矿应急救援体系的必要性和重要意义,并强调指出建设基于避难硐室系统的煤矿应急救援体系模型不仅可以指导开展受灾矿工自救互救工作,而且也使地面救援工作更具针对性和方向性,可以直达要害,从而实现井上井下协调统一的"立体"救援,对于坚持"以人为本"的煤矿生产理念具有重要的意义。     

公路隧道火灾逃生疏散研究

以苍岭隧道为背景,首先采用经验计算理论和计算软件building EXODUS相结合的方式,从被困人员的安全疏散时间、高温烟气的影响、隧道横通道的利用率以及人员的疏散行为特性进行了研究。结果表明:中小规模火灾情况下的安全疏散时间控制在8 min之内,高温烟气影响不大,但横通道的利用率不平均,且人员疏散路线相对集中。然后对存在的逃生疏散问题提出针对性建议以及其他相关建议,旨在为更大程度降低事故的严重性和经济财产损失。     

煤矿紧急避险体系构建与应急救援模型研究

为构建煤矿井下紧急避险体系结构,打造基于紧急避险设施的应急救援体系,分析国外矿业发达国家紧急避险理论和应急救援案例,研究煤矿紧急避险建设及相关参数,探讨紧急避险体系构建中的国家层面概念定义、立法保障、救援体系、避险安全文化及评价等关键问题,设计出以危险源感知为基础的"感知-避险设施-运行"3层紧急避险体系结构。采用应急管理阶段理论与方法,构建基于紧急避险"感知-避险-救援"应急救援模型,并对救援模型的可行性进行模拟。煤矿井下紧急避险体系构建要有国家标准和立法保障,紧急避险3层体系结构为避险系统建设提供指导,救援模型为应急救援体系打造提供一种方法。     

矿山钻孔救援技术的研究与务实思考

钻孔救援技术是煤矿应急救援的一项有效实用的救生、救援技术。目前尚处于探索起步阶段,许多机构和企业的研究更多集中在精确钻孔方面,缺乏对钻孔救援的深入思考,尤其是以救生为核心的研究。该文主要总结了智利圣何塞铜矿事故救援的经过和主要成功要素。在此基础上,提出了钻孔救援的基本概念,总结了钻孔救援的前提是要求钻孔精准的达到指定位置,钻孔救援技术的限制条件和措施。提出发展钻孔救援要以救生为目标,加强引进和研发提高钻孔救援装备的水平,依靠科技进步,大力发展钻孔救援技术装备;组织开展生命救治技术措施研究;制订和完善钻孔救援技术战术规程、标准等。     

应急救援中紧急冲淋设备的研讨

随着国家经济的飞速发展,减少作业人员在事故发生时所受到的职业危害尤为重要。本文对紧急冲淋设备的技术性能、作用进行了一定探讨与描述,希望对企业正确的配备紧急冲淋设备有所帮助。     

基于WiFi的煤矿井下应急救援无线通信系统的研究

随着现代化煤矿的要求及无线通信技术的发展,地面无线通信技术开始应用于煤矿井下通信。本文从煤矿井下灾害环境的特殊性及救援工作的安全性、紧迫性出发,通过分析W iF i短距离无线通信技术,提出了基于W iF i技术建立一种新的煤矿井下应急救援无线通信系统,重点介绍了其原理、硬件设计和软件仿真。该系统在灾后煤矿井下电力供应完全切断的情况下,仍能迅速建立应急救援无线通信链路。该系统基于S3C2410X ARM9硬件平台,硬件设计主要包括采集终端设备和链路路由设备两部分,可实现井下事故现场的环境参数监测、数据实时传输、语音通信等功能。通过NS2离线事件仿真器对系统仿真结果可以看,出该系统的时延小、抖动率低,传输速率随着时间的增加呈现稳定增长趋势,理论上基本满足井下应急救援通信需要,且性能比较稳定。