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991.
Improvement in collective performance with experience in ants 总被引:3,自引:4,他引:3
Elizabeth?A.?Langridge Nigel?R.?FranksEmail author Ana?B.?Sendova-Franks 《Behavioral ecology and sociobiology》2004,56(6):523-529
We show that entire ant colonies can improve their collective performance progressively when they repeat the same process. Colonies of Leptothorax albipennis can reduce their total emigration times over successive emigrations. We show that this improvement is based on experience and some memory-like process, rather than a coincidental developmental change or an increased general level of arousal. We demonstrate that the benefits of experience can be lost (i.e. forgotten) if the interval between successive emigrations is too long. We also show that the benefits of experience are more likely to be retained over a longer period if the collective performance has been repeated several times. This is a new demonstration of a process akin to learning in ants and we briefly discuss how it may involve not only improvements in individual performance but also improvements in the ways in which the ants interact with one another.Communicated by L. Sundström 相似文献
992.
The importance of spatial autocorrelation,extent and resolution in predicting forest bird occurrence 总被引:3,自引:0,他引:3
Concerns about declines in forest biodiversity underscore the need for accurate estimates of the distribution and abundance of organisms at large scales and at resolutions that are fine enough to be appropriate for management. This paper addresses three major objectives: (i) to determine whether the resolution of typical air photo-derived forest inventory is sufficient for the accurate prediction of site occupancy by forest birds. We compared prediction success of habitat models using air photo variables to models with variables derived from finer resolution, ground-sampled vegetation plots. (ii) To test whether incorporating spatial autocorrelation into habitat models via autologistic regression increases prediction success. (iii) To determine whether landscape structure is an important factor in predicting bird distribution in forest-dominated landscapes. Models were tested locally (Greater Fundy Ecosystem [GFE]) using cross-validation, and regionally using an independent data set from an area located ca. 250 km to the northwest (Riley Brook [RB]). We found significant positive spatial autocorrelation in the residuals of at least one habitat model for 76% (16/21) of species examined. In these cases, the logistic regression assumption of spatially independent errors was violated. Logistic models that ignored spatial autocorrelation tended to overestimate habitat effects. Though overall prediction success was higher for autologistic models than logistic models in the GFE, the difference was only significantly improved for one species. Further, the inclusion of spatial covariates did little to improve model performance in the geographically discrete study area. For 62% (13/21) of species examined, landscape variables were significant predictors of forest bird occurrence even after statistically controlling for stand-level variability. However, broad spatial extents explained less variation than local factors. In the GFE, 76% (16/21) of air photo and 81% (17/21) of ground plot models were accurate enough to be of practical utility (AUC > 0.7). When applied to RB, both model types performed effectively for 55% (11/20) of the species examined. We did not detect an overall difference in prediction success between air photo and ground plot models in either study area. We conclude that air photo data are as effective as fine resolution vegetation data for predicting site occupancy for the majority of species in this study. These models will be of use to forest managers who are interested in mapping species distributions under various timber harvest scenarios, and to protected areas planners attempting to optimize reserve function. 相似文献
993.
高效液相色谱法分析水中痕量多环芳烃 总被引:14,自引:3,他引:14
本文利用高效液相色谱法测定水中痕量多环芳烃(PAHs)。以二氯甲烷作溶剂,超声提取水中痕量PAHs;甲醇、水作流动相,梯度淋洗,用程序可变波长荧光检测器测定。PHAs浓度为0.007=0.6μg·ml^-1范围时,线性相关系数均在0.9999以上;峰高、峰面积的相对标准偏差(n=10)分别为1.01-1.85%,2.00-3.94%;检测限(S/N=2)为3.1-23.0pg;实际水样的加标回收率 相似文献
994.
广州地铁二号线列车控制系统的设计 总被引:1,自引:0,他引:1
张彤 《湖南环境生物职业技术学院学报》2005,11(3):251-254,261
从用户的角度,介绍了广州地铁二号线列车控制系统的技术参数,特点及其性能,并对其在一号线列车控制基础上所做的改进进行了说明. 相似文献
995.
996.
对火焰原子吸收分光光度法测定土壤中的锌消解方法进行了改进,通过器皿的精心清洗、加盖防止尘埃污染以及选择优级纯的消解试剂等措施,降低了空白试验的测定值,从而提高了样品测定的精密度和准确度. 相似文献
997.
针对石油石化企业HSSE管理体系运行中存在的问题,基于企业实际情况,采用系统方法设计提出了石油石化企业HSSE管理体系运行模式。从企业整体角度,运用战略思维提出HSSE管理体系运行的推进模型和方法,从战略、组织、能力、信息、流程、绩效6个方面,提出HSSE管理体系运行要求。通过创新HSSE管理体系运行模式和推进方法,企业能够从更加宏观的角度,整合有限资源实现HSSE管理体系有效运行,从而提升企业HSSE绩效。 相似文献
998.
999.
低贵金属含稀土复合型汽车排气净化催化剂研究 总被引:2,自引:2,他引:2
研究了3种低钯含稀土复合型汽车排气净化催化剂的制备工艺条件、活性和热稳定性。结果表明:所研制的催化剂对CO、HC的起燃温度分别在182℃~210℃之间;完全氧化温度在230℃~250℃之间。具有起燃温度低、活性高的特性。高温处理后,T50%和T100%仅上升了8℃~24℃,说明热稳定性良好。少量贵金属Pd分浸法以及在活性氧化铝涂层上使用无机胶粘剂的制备工艺能提高催化剂的热稳定性 相似文献
1000.
抚西河综合整治是抚顺市区内七条支流河整治项目之一。经调查,沿河无统一的治理规划,河两岸的基础设施残缺不全,普遍无排水设施,致使附近工业废水和城市居民生活污水直接排入河中,造成河水污染。为确保浑河水体不再受污染,文中在论述抚西河污染现状及其危害的基础上,提出了点源治理、污水截流等方面的具体方案和对策。 相似文献