格氏栲自然保护区常绿阔叶林群落的数量分类

基于对群落22个样地的调查,以群落样地中乔木层树种的重要值为指标,采用纸条排队法、群落相似系数分类法、最近邻体法和组平均法对格氏栲自然保护区常绿阔叶林群落进行数量分类。结果表明:4种分类结果基本相似,格氏栲自然保护区常绿阔叶林群落样地可分为格氏栲群系、米槠群系、甜槠群系、刨花楠群系、沉水樟群系、观光木群系和闽楠群系等7个群系,并论述了各群系的群落学特征,各群系基本处于稳定的顶极阶段。     

内蒙古根瘤菌的数值分类

对63株新分离的内蒙古根瘤菌与6株来自Rhizobiumleguminosarum及Sinorhizobiummililoti的参比菌株一起进行了数值分类。结果表明：所有测试菌株在67％的相似性水平上分为三个表观群,群Ⅰ包括3株Sinorhizobiummeliloti的参比菌和9株新分离的内蒙古根瘤菌;群Ⅱ包括3株RhizobiumLoguminosarum参比菌和37株新分离的内蒙古根瘤菌;群Ⅲ全部由20株新分离的内蒙古根瘤菌组成。在78％的相似     

新型数值分类软件X-Cluster的开发及应用

针对目前常用数值分类软件的不足,采用多种设计模式开发了新型数值分类软件X-C luster。该软件具有界面友好、操作方便、体积小、速度快、功能强大、应用范围广等特点,能够满足大多数情况下数值分类研究工作的需求,并在芽孢杆菌分类研究中得到了验证。     

Modeling impacts of Yangtze River water transfer on water ages in Lake Taihu, China

To improve water quality and alleviate eutrophication in Lake Taihu, the third largest freshwater lake in China, a Yangtze River water transfer project was initiated in 2002 to bring water from the Yangtze River to Lake Taihu to dilute and divert pollutants out of the lake. We used a three-dimensional numerical model, Environmental Fluid Dynamics Code, to study the impacts of water transfer on the transport of dissolved substances in the lake by using the concept of water age. In particular, the influences of inflow tributaries and wind forcing on water age were investigated. Model results showed that the effect of water transfer on transport processes in the lake is strongly influenced by hydrodynamic conditions induced by wind and inflow/outflow tributaries. During the simulation year (2005), the water ages in Lake Taihu were highly variable both spatially and temporally, with a mean of approximately 130 days in summer and 230 days in the other seasons. Southeasterly winds—dominant in the summer—could improve the quality of water by reducing the water age in the eastern areas of the lake, which are used as a drinking water source, and in Meiliang Bay, the most polluted bay. In terms of dilution, the most efficient flow rate for transferred water was predicted to be approximately 100 m³/s. The spatial distribution of water ages showed that water transfer may preferentially enhance exchanges in some areas of the lake unless nutrient concentrations in the transferred water are reduced to a reasonable level. This study provides useful information for a better understanding of the complex hydrodynamic and mass transport processes in the lake, which is important for developing and implementing effective ecological restoration strategies in the region.     

Trait biogeography of marine copepods – an analysis across scales

Functional traits, rather than taxonomic identity, determine the fitness of individuals in their environment: traits of marine organisms are therefore expected to vary across the global ocean as a function of the environment. Here, we quantify such spatial and seasonal variations based on extensive empirical data and present the first global biogeography of key traits (body size, feeding mode, relative offspring size and myelination) for pelagic copepods, the major group of marine zooplankton. We identify strong patterns with latitude, season and between ocean basins that are partially (c. 50%) explained by key environmental drivers. Body size, for example decreases with temperature, confirming the temperature‐size rule, but surprisingly also with productivity, possibly driven by food‐chain length and size‐selective predation. Patterns unrelated to environmental predictors may originate from phylogenetic clustering. Our maps can be used as a test‐bed for trait‐based mechanistic models and to inspire next‐generation biogeochemical models.     

Classification of Bacteria and Archaea: Past,present and future

The late 19th century was the beginning of bacterial taxonomy and bacteria were classified on the basis of phenotypic markers. The distinction of prokaryotes and eukaryotes was introduced in the 1960s. Numerical taxonomy improved phenotypic identification but provided little information on the phylogenetic relationships of prokaryotes. Later on, chemotaxonomic and genotypic methods were widely used for a more satisfactory classification. Archaea were first classified as a separate group of prokaryotes in 1977. The current classification of Bacteria and Archaea is based on an operational-based model, the so-called polyphasic approach, comprised of phenotypic, chemotaxonomic and genotypic data, as well as phylogenetic information. The provisional status Candidatus has been established for describing uncultured prokaryotic cells for which their phylogenetic relationship has been determined and their authenticity revealed by in situ probing.     

Numerical simulation of a stroke: computational problems and methodology

We discuss the difficulties of the numerical simulation of a stroke, and we describe the numerical methods which we have developed and used to obtain some realistic results. Nowadays, the computations are performed in two-dimensional slices of a brain, but the strategies to obtain full three-dimensional simulations are explored. This paper is written so as to be understandable by non-mathematicians.     

A Technique to Analyse Succession Data from Permanent Plots

IIntroductionSuccessionstudyIsaspeclalfleldInvegetationecology（Greig—Smith1983）．ItreferstocummulatlvechangeInvegetationovertime．Florl幻IcgradientsIndicativeofsuccessionaltrendsmayemergefromconventionalordinationIfextrinsic！nformatlonallowsthemtobel－dentlfledassuch．Inthespedalcaseofforestvegetation,forInstance,Informationonthesize—classesoftreespedespresentmaypermitsuccessionalgradientslobeldentlfleddirectly（Goff1968,Carleton＆Maycock1978）．Fewauthors,however,haveattempted…     

中国薹草属黑穗薹草组的数量分类研究

对中国薹草属黑穗薹草组Sect.Racemosae及外类群冻原薹草组Sect.Frigidae共20种3变种采用38个形态特征进行了数量分类研究。聚类分析结果表明,黑穗薹草组应是一个自然分类群;支持了《中国植物志》将两对相似种：乌拉草（Carer meyeriana）与红原薹草（Carer hongyuanensis）、膨囊薹草（Carex lehmanii）与五台山薹草（Carex montis-wutaii）分别处理为种的观点。主成分分析结果表明,本组的分类特征较为稳定与集中,本组主成分分析散点图与聚类分析的分类结果大致吻合,并表明有关小坚果、果囊、鳞片、主茎叶和苞片的性状在本组的分类中起到了主要作用。     

Simulation of scalp cooling by external devices for prevention of chemotherapy-induced alopecia

Hypothermia of the scalp tissue during chemotherapy treatment (scalp cooling) has been shown to reduce or prevent chemotherapy-induced hair loss. In this study, numerical models are developed to investigate the interaction between different types of external scalp cooling devices and the human scalp tissue. This work focuses on improving methods of modeling scalp cooling devices as it relates specifically to the prevention of chemotherapy-induced alopecia. First, the cooling power needed for any type of device to achieve therapeutic levels of scalp hypothermia is investigated. Subsequently, two types of scalp cooling devices are simulated: a pre-cooled/frozen cap design and a liquid-cooled cap design. For an average patient, simulations show that 38.5 W of heat must be extracted from the scalp tissue for this therapy in order to cool the hair follicle to 22 °C. In practice, the cooling power must be greater than this amount to account for thermal losses of the device. Simulations show that pre-cooled and liquid-cooled cap designs result in different tissue temperatures over the course of the procedure. However, it is the temperature of the coolant that largely determines the resulting tissue temperature. Simulations confirm that the thermal resistance of the hair/air layer has a large impact on the resulting tissue temperatures. The results should be correlated with experimental data as an effort to determine the optimal parameter choices for this model.