鼎湖血桐种群生物学及遗传多样性初步研究

采用点格局分析、径级结构分析以及微卫星筛选等方法,对鼎湖山保护区20hm2永久样地中的鼎湖血桐进行了种群生物学及遗传多样性研究。结果表明:鼎湖血桐是一种r-对策型阳生植物,种群年龄结构呈金字塔型;植株受光照不足的胁迫,种群大部分个体聚集分布于光照充足的林窗中;通过磁珠富集法筛选出鼎湖血桐特异性微卫星引物13对,其中2对具备多态性,多态百分率为15.4%,多态信息含量在0～0.3734之间,平均期望杂合度为0.0756,远低于同属其它植物。研究表明鼎湖血桐对环境变化的适应范围较窄,遗传多样性较低,应对其种质资源进行多样性评估与保护。     

The stabilizability of a controlled system describing the dynamics of a fishery

This work presents two stock-effort dynamical models describing the evolution of a fish population growing and moving between two fishing zones, on which it is harvested by a fishing fleet, distributed on the two zones. The first model corresponds to the case of constant displacement rates of the fishing effort, and the second one to fish stock-dependent displacement rates. In equations of the fishing efforts, a control function is introduced as the proportion of the revenue to be invested, for each fleet. The stabilizability analysis of the aggregated model, in the neighborhood of the equilibrium point, enables the determination of a Lyapunov function, which ensures the existence of a stabilizing discontinuous feedback for this model. This enables us to control the system and to lead, in an uniform way, any solution of this system towards this desired equilibrium point.     

Salmonella spp. are affected by different levels of water activity in closed microcosms

Controlling water activity (a _w) can significantly impact the growth of Salmonella in poultry litter and manure — a phenomenon that was studied quantitatively using two common serotypes of Salmonella. The quantitative effect of changes in levels of a _w on Salmonella populations was determined using inoculated, frosted glass rectangles placed in closed chambers (microcosms). Glass rectangles with known concentrations of Salmonella enteritidis and S. brandenburg were placed in microcosms maintained at an a _w level of 0.893 for 24 h at room temperature (RT) and then transferred to other microcosms maintained at the same temperature but with higher a _w levels (0.932 and 0.987). Salmonella populations on the slides were quantified at 4, 18, 24, and 48 h. Slightly elevated levels of a _w (<0.1, i.e., 10% equilibrium relative humidity) for 24 h resulted in a 100-fold increase in counts of Salmonella. The data also suggested that in vitro adaptation to dry environments may occur when the organisms are exposed to alternating levels of relatively high and low (0.987 and 0.893) levels of a _w. Any increased tolerance of Salmonella to reduced levels of a _w could be the result of physico-chemical changes in the organism due to selective environmental pressure, formation of a protective biofilm, and/or entry into a dormant state. Results from this study are compatible with those from previously reported on-farm surveys, reinforcing the contention that maintaining a _w below 0.85 in and around litter/manure surfaces in poultry or livestock bedding areas may be a critical factor in safe production of food. Journal of Industrial Microbiology & Biotechnology (2001) 26, 222–225. Received 18 May 2000/ Accepted in revised form 24 January 2001     

GIS在描述某城区大气二氧化硫分布中的应用初探

应用地理信息系统（GIS）技术对1996年重庆市主城区大气二氧化硫分布进行了描述和分析。采用GIS的空间分析方法泰森多边形分析和区域插值对大气环境监测数据进行分析处理,避免了以点代面的缺陷,使大气污染物分布描述更为合理。     

Rad50 Zinc Hook Is Important for the Mre11 Complex to Bind Chromosomal DNA Double-stranded Breaks and Initiate Various DNA Damage Responses

The Mre11-Rad50-Nbs1 (MRN) complex plays critical roles in checkpoint activation and double-stranded break (DSB) repair. The Rad50 zinc hook domain mediates zinc-dependent intercomplex associations of MRN, which is important for DNA tethering. Studies in yeast suggest that the Rad50 zinc hook domain is essential for MRN functions, but its role in mammalian cells is not clear. We demonstrated that the human Rad50 hook mutants are severely defective in various DNA damage responses including ATM (Ataxia telangiectasia mutated) activation, homologous recombination, sensitivity to IR, and activation of the ATR pathway. By using live cell imaging, we observed that the Rad50 hook mutants fail to be recruited to chromosomal DSBs, suggesting a novel mechanism underlying the severe defects observed for the Rad50 hook mutants. In vitro analysis showed that Zn(2+) promotes wild type but not the hook mutant of MR to bind double-stranded DNA. In vivo, the Rad50 hook mutants are defective in being recruited to chromosomal DSBs in both H2AX-proficient and -deficient cells, suggesting that the Rad50 hook mutants are impaired in direct binding to chromosomal DSB ends. We propose that the Rad50 zinc hook domain is important for the initial binding of MRN to DSBs, leading to ATM activation to phosphorylate H2AX, which recruits more MRN to the DSB-flanking chromosomal regions. Our studies reveal a critical role for the Rad50 zinc hook domain in establishing and maintaining MRN recruitment to chromosomal DSBs and suggest an important mechanism of how the Rad50 zinc hook domain contributes to DNA repair and checkpoint activation.     

乡村生态系统文化服务供需关系研究——以浙江省湖州市为例

充分利用乡村文化资源,发挥生态系统的文化服务价值,是满足新需求发展新经济、推动乡村文化振兴的重要路径。以浙江省湖州市的乡村区域为研究对象,结合地理信息数据、社会调查数据和兴趣点数据(POI),优化Maxent模型的要素评价体系,对生态系统文化服务量化制图,同时对文化服务供需水平进行空间自相关分析,确定湖州市文化服务价值的分布特征。研究结果表明：(1)湖州市乡村地区3种文化服务类型中科教人文价值最高,自然风光价值和休闲娱乐价值次之;休闲娱乐价值所占面积最大,自然风光价值和科教人文价值次之。在空间分布上,德清县北部、安吉县南部和长兴县的西北部为文化价值突出区域。(2)POI、土地利用/覆被和距道路距离是贡献度最高的3个要素,POI的应用对提高结果可靠性、提升文化服务价值制图精度有较明显的积极作用;(3)结合常住人口和旅游人口,吴兴区的大部分区域具有最高的文化服务需求,其余依次为安吉县的北部和中部、长兴县、德清县的东部、南浔区;(4)根据文化服务供需匹配关系,将湖州市乡村地区划分为发达区、需求区、潜力区、发展区,四种类别面积相对平均但分布具有较强异质性。基于供需关系视角,探索了乡村地区生态系统文化服务发展路径的研究方法,为乡村文化服务综合开发奠定理论基础。     

Multiple Testing for Identifying Effective and Safe Treatments

In the literature various multiple test procedures to compare k treatments with a control have been investigated. They can be applied to establish either treatment efficacy or treatment safety. In this paper we propose procedures which control the multiple level α with respect to efficacy and safety simultaneously. On the one hand we consider a method with stagewise rejective adjustments of local levels applied to appropriately defined subfamilies of null hypotheses. When order restrictions are assumed to hold among the parameters of interest we can alternatively split the multiple level between the families of efficacy and safety null hypotheses. If either all treatments are declared to be safe or all are declared to be effective then the other family can be tested at the full multiple level α, respectively. The methods are compared in a simulation study.     

The Early Middle Palaeolithic lithic industry of Dederiyeh Cave,Northwest Syria

The Lower-to-Middle Paleolithic transition of the Levant has attracted much attention, particularly because the early Middle Paleolithic is the period when the earliest anatomically modern humans fossils known to date in Eurasia have been attested in that part of Asia . The associated lithic assemblages are a significant source of information for investigating the cultural landscape of this important transition. This paper presents a new dataset from the 2003–2009 excavations at Dederiyeh Cave, northwest of Syria. A techno-typological analysis of the lithic industry reveals a common practice of blade blank production, which corroborates the other known early Middle Paleolithic assemblages of the Levant. However, its strong emphasis on Levallois core reduction and sidescraper manufacturing is noteworthy. The significance of this finding deserves further research from multiple viewpoints, including the functional and spatio-temporal variability of hominin activities in this period. It will be also important to interpret the techno-typological diagnostics of the early Middle Paleolithic assemblage of Dederiyeh considering its geographic location at the northern end of the Levant, distant from the previously known sites in the central and southern Levant.