捕食者食饵均染病的入侵反应扩散捕食系统中扩散的作用

研究了捕食者食饵均染病的入侵反应扩散捕食系统.利用特征值方法和构造Lyapunov函数,获得了入侵扩散对正常数平衡解的影响,当入侵扩散系数充分大时,导致平衡态失稳.进一步,利用拓扑度方法,证明了在一定条件下入侵扩散系数很大,自扩散充分小时,有非常数正平衡解存在.

连续入侵性信号扩大反映(SISAR)原理及应用简介

连续侵入性信号扩大反应(the serial invasive signal amplification reac-tion,SISAR)不同于以前的 Third Wave Technologies 公司推出的侵入信号扩大反应,它应用两个连续的侵入反应在恒温系统中将靶位点的信号放大,并通过激发荧光来显示信号。具有较高的灵敏性和严紧度,是不需要热循环 PCR 反应和限制性酶切反应的一种另类序列检测手段。

在网络流量中搜索恶意输入并自动修复验证

为了真正实施自我修复技术,提高它们在系统中信任级别,在它自动发展后,"修复"的功效必须进行测试和验证。但在实际部署之前,由于攻击的特性,这种验证必须是自动进行,该问题称为自动修复验证(automatic repair validation,ARV)。为了说明ARV所面临的困难,提出了一种系统的设计,该系统跟踪和存储恶意的网络流量,为自我修复软件在验证阶段后重放提供条件。实例验证了该方法的可行性。

IDS及其安全性测试

上海市信息安全测评认证中心是专门从事信息安全产品、信息系统及信息安全技术服务资质测评的专业机构，其主要职能是在信息安全领域内开展各类测试、评估工作。

Frog community responses to recent American bullfrog invasions

Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in the community （residence time）, and the interaction between these two variables. We tested these effects using data on the effects of American bullfrog Lithobates catesbeianus invasion on native frog communities in 65 permanent lentic waters on islands in the Zhoushan Archipel- ago, China. We examined variation in native frog abundance and species richness in relation to features of the American bullfrog invasion, habitat disturbance, characteristics of the water body and fish communities and the presence of red swamp crayfish. Bullfrog invaded sites had lower native frog density and species richness, higher submerged vegetation cover and greater fre- quency of repairs to the water body than did non-invaded sites. The minimum adequate general linear mixed models showed that both native frog density and species richness were negatively related to post-metamorphosis bullfrog density, and that native frog species richness was also positively related to the vegetation cover. There was no effect on either native frog density or species richness of residence time or its interaction with bullfrog density, or of the abundance of bullfrog tadpoles. The results suggested that post-metamorphosis bullfrogs had impacts on native frog communities in the islands, and that the extents of these impacts are proportional to post-metamorphosis bullfrog density

Antioxidative Responses and Metal Accumulation in Invasive Plant Species Growing on Mine Tailings in Zanjan, Iran

Tailings of a Pb and Zn mine as a metal-contaminated area （Zone 1） with two pioneer plant species, Peganum harmala and Zygophyllum fabago, were investigated and compared with a non-contaminated area （Zone 2） in the vicinity. Total concentrations of Pb, Zn, and Cu in the soil of Zone 1 were 1 416, 2 217, and 426 mg kg-1, respectively, and all exceeded their ranges in the normal soils. The soil pH was in the neutral range and most of the physical and chemical characteristics of the soils from both zones were almost similar. The species Z. fabago accumulated higher Cu and Zn in its aerial part and roots than the normal plants. On the other hand, their concentrations did not reach the criteria that the species could be considered as a metal hyperaccumulator. The species P. harmala did not absorb metals in its roots; accordingly, the accumulation factor values of these metals were lower than 1. The contents of chlorophyll, biomass, malondialdehyde, and dityrosine in these two species did not vary significantly between the two zones studied. In Zone 1, leaf vacuoles of Z. fabago stored 35.6% and 43.2% of the total leaf Cu and Zn, respectively. However, in this species, the levels of phytochelatins （PCs） and glutathione （GSH） and antioxidant enzyme activities were significantly higher in Zone 1 than in Zone 2. In conclusion, metal exclusion in P. harmala and metal accumulation in Z. fabago were the basic strategies in the two studied pioneer species growing on the metal-contaminated zone. In response to metal stress, elevation in antioxidant enzyme activities, increases in the PCs and GSH levels in the aerial parts, and metal storage within vacuoles counteracted each other in the invasion mechanism of Z. ]abago.

Current plant diversity but not its soil legacy influences exotic plant invasion

Current plant diversity can influence exotic plant invasion,but it is unclear whether there is a legacy effect of plant diversity on exotic plant invasion.As plant diversity can affect soil microbial communities and physio-chemical properties,which may cascade to impact subsequent exotic plant growth,we hypothesize that the soil legacy effect of plant diversity can influence exotic plant invasion.We conducted a plant–soil feedback experiment.In the conditioning phase,we trained soils by monocultures of 12 plant species from three functional groups(4 grasses,3 legumes and 5 forbs)and mixtures of 8 randomly selected species with all three functional groups from this 12-species pool.In the test phase,we grew the invasive plant Bidens pilosa with a co-occurring native grass(Arthraxon hispidus),with a co-occurring native forb(Pterocypsela indica)or with both in each type of the conditioned soils.The performance of B.pilosa relative to its native competitors varied depending on the functional type of both conditioning plant species in the conditioning phase and competing plant species in the test phase.Diversity of the conditioning plants did not influence the growth difference between B.pilosa and its native competitors.However,increasing diversity of the competing plant species reduced the performance of B.pilosa relative to its native competitors.Our results suggest that current plant diversity can reduce exotic plant invasion through increasing growth inequality between invasive and native plants,but the soil legacy effect of plant diversity may have little impact on exotic plant invasion.