城市公园的环境–活动游憩机会谱模型研究——以广州珠江公园为例

城市公园游憩体验的研究对于解决多样化的游憩需求与有限的游憩资源之间的矛盾具有重要意义。将游憩机会谱理论应用于城市公园游憩体验质量改善,提出环境–活动游憩机会谱模型（E-A ROS）。以广州珠江公园为例,采用问卷调查法和SPSS统计分析法,从物质、社会、管理3个方面构建珠江公园环境质量评价的指标体系和指标量化方法,从人口统计学特征、行为特征和行为偏好3个方面进行活动因子研究,探讨珠江公园使用者活动规律,构建珠江公园游憩机会谱。从而为城市公园环境–活动游憩机会谱模型的应用提供了详细的操作指引。     

Steller sea lion spatial‐use patterns derived from a Bayesian model of opportunistic observations

Despite acquisition of a substantial catalog of telemetry data from Steller sea lions (Eumetopias jubatus) over the past two decades, scientists still lack comprehensive regionally explicit knowledge about Steller sea lion habitat use. The Platforms of Opportunity data contain records of Steller sea lion sightings throughout the species’ entire range and have potential to fill gaps in knowledge about their spatial use; however, the data have not previously been used because effort (e.g., time spent surveying or area sampled) was not recorded when sightings were obtained. For this study a novel approach was used to overcome the lack of effort data through development of an effort index and a Bayesian negative binomial model. The model quantified Steller sea lion encounter rates and associated uncertainty within 15 × 15 km² grid cells across the species’ entire range. Year‐round, as well as breeding and nonbreeding season encounter rates were estimated. The results of this analysis identify several previously undocumented areas of high use by Steller sea lions, indicate that only 37% of Steller sea lion high‐use areas fall within designated critical habitat, and demonstrate that use of depth and distance from shore as indicators of Steller sea lion habitat is contraindicated.     

Patterns of vegetative growth and reproduction in relation to branch orders: the plant as a spatially structured population

The patterns of vegetative growth and reproduction in relation to orders of terminal branches were examined in the evergreen woody plant, Eurya japonica. The branch order number was determined centrifugally. The trunk was given order number 1; branches issuing directly from the trunk were order 2; branches growing on order 2 branches were order 3, and so on. The results of this study show the differential patterns of vegetative growth and reproduction in relation to the branch orders. Lower-order shoots of terminal branches grew more, but produced few flowers. On the other hand, for the higher-order terminal branches, shoot growth was very limited but flowering was more intense. The results show that a tree can be interpreted not as a mere population of equivalent modules but as a spatially structured population. Thus, it is essential to consider the position of modules within the branch system when patterns of vegetative growth and reproduction are examined. It is hypothesized that the difference in the opportunity cost in relation to the branch orders is the main cause of the spatial structure for patterns of vegetative growth and reproduction. Furthermore, for same-order terminal branches, current-year shoot elongation was independent of flowering intensity. These results suggest that this species only invests resources in reproduction that are surplus to its requirements for the functions associated with survival, such as growth and/or storage. Received: 22 July 1999 / Accepted: 12 January 2000     

连续肾脏替代疗法治疗重症急性胰腺炎时机的探讨

目的:探讨连续肾脏替代疗法(CRRT)治疗重症急性胰腺炎的最佳时机。方法:选取我院收治的30例重症急性胰腺炎(SAP)患者为研究对象,按发病后行CRRT的时间分将患者随机为A、B两组,A组发病后72小时内治疗,B组发病后72小时后治疗,分析和比较两组治疗后的临床转归及生命体征变化、APACHEⅡ评分变化急性生理与慢性健康状况、住院费用、平均住院时间。结果:经CRRT治疗后,A组死亡率(14.3%)低于B组(43.7%),差异有统计学意义(P0.05);A、B两组治疗后体温、心率、呼吸、平均动脉压平稳,A组优于B组,差异有统计学意义(P0.05);A组的平均住院时间(15.7±8.9)d、住院费用(107000±65000)万元均明显优于B组,差异有统计学意义(P0.05);两组患者治疗后APACHEⅡ评分均明显优于治疗前,治疗后A组APACHEⅡ评分明显优于B组,差异显著有统计学意义(P0.05)。结论:早期行CRRT能明显改善重症急性胰腺炎患者的疗效和预后,最佳治疗时机可能为发病后72小时内。     

微生物学复兴的机遇、挑战和趋势

历史上,微生物学的发展曾经历了两个辉煌的黄金时代,也经历了其发展的低谷时期。近20年来,随着基因组学、结构生物学、生物信息学、PCR技术、高分率荧光显微镜及其它物理化学理论和技术等的应用,使微生物学的研究取得了一系列突破性进展,微生物学己走出其低谷,开始进入它的第三个黄金时代。本文就下列几个方面谈谈自已对当今微生学发展的机遇、挑战和趋势的一些认识,供读者参考:(1)历史上微生物学发展的两个黄金时代;(2)微生物学复兴的机遇和挑战;(3)当前微生物学发展的特点和趋势;(4)整合微生物学——第三个黄金时代的重要特征。     

Why do lower order branches show greater shoot growth than higher order branches? Considering space availability as a factor affecting shoot growth

Many woody plants show hierarchical shoot growth: annual shoot length decreased with increasing branching order. We hypothesize that plants showing hierarchical shoot growth improve the efficiency in terms of space acquisition and use per invested shoot length. This hypothesis was tested by using a simple geometric simulation model of branch development. In this study, the effective shoot length (EL), the shoot length produced within a growth season without any overlap from other shoots, was used as the index of space availability. We compared EL among shoots on different branching orders of a “simulated” branch system. The EL decreased with an increasing branching order. The results suggested that space availability decreased with increasing branching orders. The results also showed that simulated plants with the hierarchical shoot growth showed higher efficiency in terms of space acquisition per investment than those with the non-hierarchical shoot growth. We concluded that the difference in space availability between the branching orders could be an important ultimate factor causing hierarchical shoot growth.     

Quantifying episodes of sexual selection: Insights from a transparent worm with fluorescent sperm

Sexual selection operates through consecutive episodes of selection that ultimately contribute to the observed variance in reproductive success between individuals. Understanding the relative importance of these episodes is challenging, particularly because the relevant postcopulatory fitness components are often difficult to assess. Here, we investigate different episodes of sexual selection on the male sex function, by assessing how (precopulatory) mating success, and (postcopulatory) sperm‐transfer efficiency and sperm‐fertilizing efficiency contribute to male reproductive success. Specifically, we used a transgenic line of the transparent flatworm, Macrostomum lignano, which expresses green fluorescent protein (GFP) in all cell types, including sperm cells, enabling in vivo sperm tracking and paternity analysis. We found that a large proportion of variance in male reproductive success arose from the postcopulatory episodes. Moreover, we also quantified selection differentials on 10 morphological traits. Testis size and seminal vesicle size showed significant positive selection differentials, which were mainly due to selection on sperm‐transfer efficiency. Overall, our results demonstrate that male reproductive success in M. lignano is not primarily limited by the number of matings achieved, but rather by the ability to convert matings into successful fertilizations, which is facilitated by producing many sperm.     

The orangutan–oil palm conflict: economic constraints and opportunities for conservation

The future of the orangutan (Pongo spp.) is far from secure despite the species’ high profile and media attention. The traditional threat to the orangutan has been widespread logging, but the continuing conversion of remaining habitat for oil palm (Elaeis guineensis) cultivation is hastening its extinction in the wild. This situation is driven by a robust global market for palm oil as a vegetable oil and biofuel. In tackling this conservation problem, therefore, economic factors cannot be overlooked. This article analyses these factors and how they curtail effective orangutan conservation. Of significance are the high opportunity costs of orangutan conservation and market failures associated with the public-goods nature of the orangutan’s forest habitat. Conservationists should consider these constraints when formulating remedial action. This article assesses strategies that reduce the opportunity cost of conserving habitat (via supply-side approaches that divert oil palm cultivation away from forests) and enhance the realisable value of orangutan habitat (by capitalising on the demand for non-market values such as carbon storage). It is concluded that the former group of strategies are likely to have limited effect on curtailing deforestation, but with the right institutional policies in place they can act as stopgaps while strategies involving carbon financing and payments for biodiversity develop sufficiently to render habitat retention financially competitive.

Tolerance and recovery responses of playa halophytes to light,salinity and temperature stresses during seed germination

Halogeton glomeratus (M. Bieb.) C.A. Mey., Lepidium latifolium Linn. and Peganum harmala Linn. are distributed in temperate salt playa habitats of Upper Hunza, Pakistan. Seeds were germinated under various salinity (0–500 mM NaCl), light (12 h-light:12 h-dark and 24 h-dark) and temperature (5/15, 10/20, 15/25, 20/30, and 25/35 °C, dark/light) regimes for 20 days to determine the optimal conditions for germination and recovery of seeds from these factors when exposed to less than optimal conditions. Seeds that failed to germinate in dark were transferred successively to 12 h-photoperiod, salinity to distilled water and from various temperature regimes to 20/30 °C, to determine the effect of these stresses and the ability of these seeds to recover respectively. Highest seed germination (H. glomeratus and L. latifolium: 100%; P. harmala: 80%) was obtained in non-saline control at 20/30 °C in 12 h-photoperiod, however, increase in salinity progressively inhibited seed germination. Seed germination of H. glomeratus and P. harmala was substantially inhibited and that of L. latifolium was prevented in dark. Salinity and dark treatments have a synergistic effect in inhibiting seed germination of all species. No seed of any species germinated at 5/15 °C; germination was substantially inhibited at 25/35 °C both for H. glomeratus and P. harmala while L. latifolium failed to germinate at 25/35 °C. Rate of germination also decreased with an increase in salinity at all temperature regimes but this effect was minimal at optimal temperature regime of 20/30 °C. After successive elimination of light, salinity and temperature stresses, final seed germination was identical to respective controls. The results indicate that seeds of these temperate halophytes could endure environmental stresses without losing viability and germinate readily when these stresses are removed. Under the extremely variable conditions of the playa habitat these species are highly opportunistic exploiting the windows of opportunity available during spring or early summer.