The catchment and climate regulation of pCO2 in boreal lakes

The regulation of surface water pCO₂ was studied in a set of 33 unproductive boreal lakes of different humic content, situated along a latitudinal gradient (57°N to 64°N) in Sweden. The lakes were sampled four times during one year, and analyzed on a wide variety of water chemistry parameters. With only one exception, all lakes were supersaturated with CO₂ with respect to the atmosphere at all sampling occasions. pCO₂ was closely related to the DOC concentration in lakes, which in turn was mainly regulated by catchment characteristics. This pattern was similar along the latitudinal gradient and at different seasons of the year, indicating that it is valid for a variety of climatic conditions within the boreal forest zone. We suggest that landscape characteristics determine the accumulation and subsequent supply of allochthonous organic matter from boreal catchments to lakes, which in turn results in boreal lakes becoming net sources of atmospheric CO₂.     

STABILITY IN THE PROPORTION OF HARBOR SEALS HAULED OUT UNDER LOCALLY IDEAL CONDITIONS

We monitored the haul-out behavior of 68 radio-tagged harbor seals ( Phoca vitulina ) during the molt season at two Alaskan haul-out sites (Grand Island, August-September 1994; Nanvak Bay, August-September 2000). For each site, we created a statistical model of the proportion of seals hauled out as a function of date, time of day, tide, and weather covariates. Using these models, we identified the conditions that would result in the greatest proportion of seals hauled out. Although those "ideal conditions" differed between sites, the proportion of seals predicted to be hauled out under those conditions was very similar (81.3% for Grand Island and 85.7% for Nanvak Bay). The similar estimates for both sites suggest that haul-out proportions under locally ideal conditions may be constant between years and geographic regions, at least during the molt season.     

DNA水平上的植物系统学研究方法

本文简要总结了近年来在ＤＮＡ水平上的植物系统学研究方法,着重介绍了限制性长度多态性分析,ＰＣＲ技术在植物系统学上的应用等这一领域最新的进展,并对分子数据的分析方法及系统树的构建进行了详细讨论。     

饱和试验设计资料的逐步回归分析

对饱和试验设计资料,一次最小二乘分析是不合理的,采用逐步回归分析法,在选择适当的理论F值前提下,不仅可以检验每个回归系数的显著性,而且能够获得最优回归方程．     

适用于获取最优化配方的一种算法

本文应用印楝种仁提取物（F3）与敌敌畏混配为例,以斜纹夜蛾（Spodopteralitura）为目标害虫,介绍一种适用于获取最优化配方的算法,在二次通用回归旋转组合设计的基础上,经参数辨识,获取二次回归方程,经失拟性、回归显著性检验,本方程基本能够反映杀虫剂用量与斜纹夜蛾幼虫死亡机率值之间的关系．在害虫防治实践中,要求在防治费用最小的基础上,目标害虫有最大的死亡率.因此,以防治目标害虫的费用作为优化算法的目标函数,以害虫死亡机率值最大作为约束条件,有如下的一组优化算式为目标函数约束条件式中a1,a2分别为参试杀虫剂1,2最低用量,b1,b2则为相应的最高用量．C1,C2分别为杀虫剂1,2的单价,N1,N2为杀虫剂l,2的用量．Y为目标害虫死亡机率值回归方程．本文所依据的试验设计中,以对数函数关系变换编码值与使用浓度之间的关系,所以应用拉格朗日求极值原理求取最优化配方．由计算所得的混配比例与其他方法所获结果一致．     

Statistical analysis of algal and water quality data

Data on cyanobacteria (blue-green algae) are generallycollected on a reactive basis, frequently in responseto bloom events. Such data presents a biased andincomplete snapshot of water quality. This paper looksat two typical data sets for UK waters showing thatwhile statistics may be used to describe the data theyare of limited use in forecasting. Suggestions ofappropriate tests for small and sparse data sets aremade.     

Sarsicopia polaris gen. et sp.n., the first platycopioida (Copepoda: Crustacea) from the Arctic Ocean,and its phylogenetic significance

A new genus of Platycopioida is described from a boxcore sample taken at a depth of 534 m in the ArcticBarents Sea. This is the deepest record ofPlatycopioida so far. Sarsicopia gen. n. is thesistergroup of a taxon comprising Platycopia and Nanocopia; the sistergroup ofthese is Antrisocopia. Sarsicopia gen. n.is the only platycopioid to retain 2 inner setae onthe second endopod segment P2–P4, and 8 setae in thethird endopod segment of P2. The male antennnule isremarkable in having a geniculation located betweenancestral segments XX and XXI. It is suggested thatthis flexure zone was already present in thegroundpattern of Copepoda. Platycopia and Nanocopia have secondarily lost thisgeniculation.     

Myocardial uptake kinetics of tocainide enantiomers in the isolated perfused rabbit heart

The extent of myocardial accumulation of tocainide, administered as single enantiomers and as well as racemate, was determined in the isolated, spontaneous beating rabbit heart. The heart was retrogradely perfused at a constant rate and fractions of the perfusate were collected during and after infusion. Kinetic parameters for myocardial accumulation and disposition of tocainide were indirectly determined from drug concentration/time course in the outflow perfusate. No stereoselectivity in myocardial accumulation was observed. A two compartment model with mean half-lives for distribution and elimination of 0.60 and 3.78 min, respectively, was fitted to the accumulation and disposition data. At steady-state, tocainide enantiomers were accumulated about three times in the myocardium relative to the perfusion liquid. © 1995 Wiley-Liss, Inc.     

A phylogenetic study of the free-living amoeba

Immunological distances were determined for four strains of the free-living amoeba classified as Amoeba proteus, two strains classified as Polychaos dubia and a single strain classified as Chaos carolinensis. The data show that the _ShP strain does not belong to the proteus group; that A. proteus is more closely related to C. carolinensis and is derived from Chaos as is the _ShP strain; that P. dubia and C. carolinensis are the more distantly related species and appear to be the first of the above to have diverged from a common ancestor; and that the amoebae have a long evolutionary history. The accuracy of the phylogenetic tree and the distance Wagner network was discussed. Since the amoebae may be polyphyletic in origin, the latter was assumed to be a more accurate representation of the immunological distance data.