Queens and major workers of Acanthomyrmex ferox redistribute nutrients with trophic eggs

 In Acanthomyrmex ferox, two distinct egg-types are produced: reproductive eggs that give rise to offspring and trophic eggs that serve to distribute nutrients. Queens lay both reproductive and trophic eggs, while major and minor workers lay only trophic eggs in the presence of the queen. The queen lays on average 17% of the trophic eggs in a colony, while majors and minors produce 42% and 41%, respectively. The large proportion of trophic egg production by the queen and soldiers is quite remarkable, since ant queens are expected to focus entirely on reproduction and majors, which have a defensive function in many species, to be sterile. Received: 25 April 2000 / Accepted in revised form: 16 June 2000     

Systematic analysis and overall toxicity evaluation of dioxins and hexachlorobenzene in human milk

A systematic method for analyzing dioxins (PCDDs, PCDFs and dioxin-like PCBs), hexachlorobenzene (HCB), heptachlor epoxide and beta-hexachlorocyclohexane (HCH) in human milk was developed to determine the residual amount of HCB in human milk and to evaluate the overall toxicity of both dioxins and HCB in human milk. The fractionation behavior of HCB on chromatography with silica gel, alumina, and activated carbon/silica gel, and the concentrated sulfuric acid decomposition method, which is widely used as a dioxin cleanup method, were studied in order to make the preprocessing operation for HCB measurement compatible with that for conventional dioxin measurement. HCB was found to be eluted in the 2% dichloromethane (DCM)/hexane 60 ml fraction from an alumina column. Heptachlor epoxide and a part of beta-HCH were eluted in the 10% DCM/hexane 50 ml fraction from a silica gel column, while the remaining beta-HCH was eluted in the 25% DCM/hexane 60 ml fraction from an activated carbon/silica gel column. Moreover, HCB showed significant correlation with dioxin congeners having high toxicity equivalence factors (TEFs). The results suggest that the exposure route to HCB and its accumulation behavior in the human body are similar to those of the dioxins.     

考虑人员感知和行为交互的应急资源调度

目前应急资源调度的研究多数是以提高资源利用效率为目标处理某种物资调度问题,缺乏对相关人员行为感知和多资源协调调度问题的考虑。本文试图在资源调度问题研究成果的基础之上,增加行为假设,分析相关行为主体的关注点、个性偏好和情绪波动,借鉴行为运作的研究思路,综合运用前景理论、双边匹配理论、行为博弈理论和约束理论,从救助物资调度、救助人员调度和多种救助资源协调调度3个方面开展研究,改进应急资源调度方案。     

Jig separation of crushed automobile shredded residue and its evaluation by float and sink analysis

Automobile shredded residue is a potential solid fuel when its metal and chloride-containing components have been removed. The authors have investigated physical separation of automobile shredded residue to isolate components that may be used as solid fuel and reported that agglomerates of entangling fiber-like material are formed during crushing. These agglomerates make removal of metals and chloride-containing components difficult, and the paper proposes a treatment flowchart consisting of separate treatments of the coarse size fraction containing entangling fiber-like components and the smaller size fraction containing particulate matter. This paper reports the treatment of the smaller size fraction treated with jigging to obtain a low-ash and low-chloride-content product. A new washability curve was developed based on float and sink analysis test results, and it was applied to estimate the gravity separation performance of treatments such as jigging and dense medium separation. The estimated results show good agreement with the experimental results of jig separation.     

基于虚拟现实技术的起重作业人员培训仿真系统研究

特种作业人员之一的起重作业人员的安全培训工作由于受实际条件的限制,一般实际操作培训并不到位,这给生产实践中的安全问题带来了隐患,因此需要开发出能替代用于生产的起重设备来进行实际操作培训的仿真虚拟培训系统.本文介绍了系统的开发环境及用户操作界面,并且以货物偏摆为例建立了仿真模型,用Simulink验证了建立该仿真培训系统对于作业人员操作培训效果的有效性,对于我国的安全培训工作有着十分重要的意义.     

Effects of chronic ozone exposure on growth, root respiration and nutrient uptake of rice plants

To clarify the response of growth and root functions to low concentrations of ozone (O(3)), rice plants (Oryza sativa L.) were exposed to O(3) at 0.0 (control), 0.05 and 0.10 ppm for 8 weeks from vegetative to early heading stages. Exposure to 0.05 ppm O(3) tended to slightly stimulate the dry weight of whole plants up to 5 weeks and then slightly decrease the dry weight of whole plants. However, these effects were statistically significant only at 6 weeks. Exposure to 0.10 ppm O(3) reduced the dry weight of whole plants by 50% at 5 and 6 weeks, and thereafter the reduction of the dry weight of whole plants was gradually alleviated. Those changes in dry weight can be accounted for by a decrease or increase in the relative growth rate (RGR). The changes in the RGR caused by 0.05 and 0.10 ppm O(3) could be mainly attributed to the effect of O(3) on the net assimilation rate. Root/shoot ratio was lowered by both 0.05 and 0.10 ppm O(3) throughout the exposure period. The root/shoot ratio which had severely decreased at 0.10 ppm O(3) in the first half period of exposure (1-4 weeks) became close to the control in the latter part of exposure (5-8 weeks). Time-course changes in NH(4)-N root uptake rate were similar to those in the root/shoot ratio especially for 0.10 ppm O(3). On the other hand, root respiration increased from the middle to later periods. Since it is to be supposed that plants grown under stressed conditions change the ratio of plant organ weight to achieve balance between the proportion of shoots to roots in the plant and their activity for maintaining plant growth, these changes in root/shoot ratio and nitrogen uptake rate under long-term exposure can be considered to be an adaptive response to maintain rice growth under O(3) stress.     

Fine-scale flower-visiting behavior revealed by using a high-speed camera

Most estimations of the pollination efficiency of insects have been based on observation by the naked human eye. However, insect behaviors are often too rapid to analyze sufficiently this way. Here we demonstrate the use of high-speed cameras to analyze the fine-scale behaviors of Macroglossum pyrrhosticta, Xylocopa appendiculata, and Papilio dehaanii when visiting Clerodendrum trichotomum. The fine-scale nectar drinking time, number of contacts with anthers and/or stigmas, and frequencies of body part contact with anthers and/or stigmas differed significantly among pollinator species. Pollination efficiency was not equal among pollinators. In addition, M. pyrrhosticta made the least number of contacts with anthers and/or stigmas even though it showed the highest visitation frequency. These results demonstrate that when examined from the viewpoint of rapid visitation behaviors, pollination dynamics differ among pollinator species, and flower visits and pollination rates are not equal.     

A simulation model for Japanese sardine (Sardinops melanostictus) migrations in the western North Pacific

A two-dimensional individual-based model coupled with fish bioenergetics was developed to simulate migration and growth of Japanese sardine (Sardinops melanostictus) in the western North Pacific. In the model, fish movement is controlled by feeding and spawning migrations with passive transport by simulated ocean current. Feeding migration was assumed to be governed by search for local optimal habitats, which is estimated by the spatial distribution of net growth rate of a sardine bioenergetics model. The forage density is one of the most important factors which determines the geographical distributions of Japanese sardine during their feeding migrations. Spawning migration was modeled by an artificial neural network (ANN) with an input layer composed of five neurons that receive environmental information (surface temperature, temperature change experienced, current speed, day length and distance from land). Once the weight of the ANN was determined, the fish movement was solved by combining with the feeding migration model. To obtain the weights of the ANN, three experiments were conducted in which (1) the ANN was trained with back propagation (BP) method with optimum training data, (2) genetic algorithm (GA) was used to adjust the weights and (3) the weights of the ANN were decided by the GA with BP, respectively. BP is a supervised learning technique for training ANNs. GA is a search technique used in computing to find approximate solutions, such as optimization of parameters. Condition factor of sardine in the model is used as a factor of optimization in the GA works. The methods using only BP or GA did not work to search the appropriate weights in the ANN for spawning migration. In the third method, which is a combined approach of GA with BP, the model reproduced the most realistic spawning migration of Japanese sardine. The changes in temperature and day length are important factors for the orientation cues of Japanese sardine according to the sensitivity analysis of the weights of the ANN.     

山蒟(Piper hancei)的生态生物学特征

山蒟(Piper hancei)是一种有较高园林绿化价值的常绿藤本植物,通过样地调查及相关数据分析,对山蒟的形态解剖学、生理生态学、营养元素含量等生态生物学特征进行研究,结果表明:山蒟喜阴湿环境,耐贫瘠,适合在酸性赤红壤上生长,主要分布于热带亚热带地区光照适中或较弱的溪涧边、林下、树干或岩石上.其平均光合速率为4.07 μmol·m-2·s-1,气孔导度为0.23 mol·m-2·s-1,蒸腾速率为3.87 mmol·m-2·s-1.山蒟对营养元素的利用率较高,植株体内加权平均养分含量为N2.00%、P0.20%、K2.11%、Ca0.94%、Na0.05%、Mg0.15%,其中叶片的N、K和Ca含量最高,枝的P和Mg含量最高.山药的生态生物学特征有利于其快速生长、覆盖、吸附攀援和适应环境.研究结果将为山蒟的引种、栽培及开发利用提供重要理论依据.