THE NEED FOR PHYSICAL GEOGRAPHY

As a viable intellectual and professional pursuit with well defined goals, physical geography is alive and kicking but demands greater commitment from the geography profession generally. In particular, physical geographers are exhorted to be thoroughly trained in the subject matter and methodology of their own and related disciplines, to be integrative in the acquisition, analysis and interpretation of data, to be predictive in their work, and to be proud of the role that they can play in serving society's environmental needs.     

基于混合像元分解的海坛岛植被覆盖度因子研究

在USLE／RUSLE中,降雨侵蚀力与地表植被覆盖度因子具有季节变化特征．本研究考虑到两者的时空耦合性,采用基于混合像元分解的计算-y法,得到了海坛岛不同月份的地表植被覆盖度因子C。值（第i月的地表植被覆盖度因子值）和不同地类的年植被覆盖度因子C值,为岛内土壤侵蚀预报和水保工作提供参考．对第i月的地表ND啊值与年C／Ci值进行分析,发现它们呈现较好的线性关系,用SPSS软件进行回归分析得到两组线性回归参数．年C值与11月份的地表NDVI拟合程度最好,NDVIi与C1值的拟合程度好于年C值与NDVLi最后得到海坛岛通用的Ci值估算模型G=1．007—1．119-ND％,该模型的决定系数达到0．8,可用于计算岛内各月份的Ci值．     

On the well‐posedness of some mechanical variational problems

The paper aims to establish the existence and uniqueness of the solution of some variational problems constituting the basis of finite element modellings encountered in mechanics and civil engineering. And indeed, by expanding to the approximate problems coming from the space discretization, such theoretical results contribute to strengthen the robustness of the modelling softwares and the quality of their numerical results. More particularly, three kinds of mixed variational problems involving rheological non‐linearities are considered here: the evolution problems of incompressible continua (solids or fluids) subjected to quasistatic small transformations, the problems of hydromechanical coupling and those coming from quasistatic large transformations of continua. Copyright © 2005 John Wiley & Sons, Ltd.     

一致拟Lipschitzian映象的具有混合误差的Ishikawa迭代序列的收敛性

在完备凸度量空间中，对一致拟Lipschitzian映象T证明了带混合误差的渐进Ishikawa型迭代序列收敛．到不动点的一些充分必要条件。其中T不必是连续的。     

Characteristics of intraseasonal variations in the mixed layer of “warm pool” areas

Observational data obtained during the TOGA-COARE IOP in the “warm pool” area of the Western Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixed layer. The influence of westerly burst and rainfall on SST, salinity and mixed layer depth are discussed. There are two pairs of counteracting processes in the “warm pool” mixed layer: (1) The increase of mixed layer depth caused by local westerly bursts and the decrease of mixed layer depth caused by larger scale easterly relaxation; (2) the vertical mixing by local wind and the strong stratification due to rainfall in the mixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale variations of the oceanic mixed layer and atmospheric low frequency oscillations are revealed. Supported by National Natural Science Foundation of China (49276250) and LASG of Beijing.     

嗜酸小球菌对日本鳗鲡生长和免疫的影响

在饲料中分别添加3.0×108kg-1(A组)、1.5×108kg-1(B组)、1.0×108kg-1(C组)的嗜酸小球菌,制成3种实验饲料,以不添加嗜酸小球菌(D组)作为对照,饲养日本鳗鲡60d,以研究嗜酸小球菌对日本鳗鲡生长和免疫的影响。测定了增重率、饵料系数、成活率、血清中一氧化氮含量以及人工感染后的死亡率,并通过电镜观察了小肠壁细胞的微绒毛结构。结果表明A、B、C组和对照组的相对增重率分别为42.31%、75.42%、89.65%和40.32%,饲料系数分别为1.93、1.12、0.98和1.58,C组的相对增重率显著高于其他组,饵料系数则显著低于其他组,成活率也显著提高。电镜观察发现C组和B组的鳗鲡小肠细胞微绒毛排列整齐、细而长,吸收面积增大,从而提高了对饲料利用率,D组鳗鲡小肠细胞的微绒毛稀疏、短,排列不均匀。血清中NO的含量A、B、C组分别比对照组提高了23%、42%和73%。C组人工感染后的死亡率显著低于其他组。实验结果表明,在鳗鲡饲料中添加嗜酸小球菌可以显著促进鳗鲡的生长,降低饵料系数,增强其免疫力。     

Sensitivities of species compositions of the mixed forest in eastern Eurasian continent to climate change

Sensitivities of species compositions of the broadleaf–conifer mixed forest in eastern Eurasian continent to climate change were evaluated with three forest gap models, namely KOPIDE, NEWCOP, and ForClim. Testing sites are located on Changbai Mountain, the middle of the distribution range for the mixed forest. Six climate change scenarios characterizing increase in temperature and increase/decrease in precipitation were used to test the sensitivities of species composition to climate change. Simulations suggest that the mixed forest in temperate Monsoon Asia will face changes in species composition should climate change be almost certain. At the minimum level, the order of dominant species is going to change due to species competition, resulting in the increase in the proportion of broadleaved tree species in the forest. If air temperature increases and precipitation decreases, Pinus koraiensis is going to disappear from the forest and the mixed forest will become hardwood forest. This experiment supports some earlier predictions under other climate change scenarios.     

High Performance Corrugated Feed Horns for Space Applications at Millimetre Wavelengths

We report on the design fabrication and testing of a set of high performance corrugated feed horns at 30, 70, and 100 GHz, built as advanced prototypes for the Low Frequency Instrument (LFI) of the ESA Planck mission. The electromagnetic designs include linear (100 GHz) and dual shaped (30 and 70 GHz) profiles. Fabrication has been achieved by direct machining at 30 GHz and by electro-formation at higher frequencies. The measured performances on side lobe and return loss meet the stringent Planck requirements over the large (20%) instrument bandwidth. Moreover, the advantage in terms of main lobe shape and side lobe levels of the dual profiled designs has been demonstrated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Implications of heterogeneous flood‐frequency distributions on traditional stream‐discharge prediction techniques

Traditional flood‐frequency analysis involves the assumption of homogeneity of the flood distribution. However, floods are often generated by heterogeneous distributions composed of a mixture of two or more populations. Differences between the populations may be the result of a number of factors, including seasonal variations in the flood‐producing mechanisms, changes in weather patterns resulting from low‐frequency climate shifts and/or El Niño/La Nina oscillations, changes in channel routing owing to the dominance of within‐channel or floodplain flow, and basin variability resulting from changes in antecedent soil moisture. Not recognizing these physical processes in conventional flood‐frequency analysis probably is the main reason that many frequency distributions do not provide an acceptable fit to flood data. In this paper, we use long‐term hydroclimatic records from the Gila River basin of south‐east and central Arizona in the USA to explore the extent and significance of mixed populations. First, we discuss the probable causes of heterogeneity in the frequency distribution of annual flood and present evidence of its occurrence. Second, we investigate the implications of using various popular homogeneous distributions for predicting peak flows for basins that exhibit mixed population characteristics. Third, we demonstrate how alternative frequency models that explicitly account for floods generated by a mixture of two or more populations are both hydrologically and statistically more appropriate. We illustrate how the selection of the most plausible distribution for flood‐frequency analysis also should be based on hydrological reasoning as opposed to the sole application of the traditional statistical goodness‐of‐fit tests. Copyright © 2002 John Wiley & Sons, Ltd.     

The upper ocean response to tropical cyclones in the northwestern Pacific analyzed with Argo data

A large number of autonomous profiling floats deployed in global oceans have provided abundant temperature and salinity profiles of the upper ocean. Many floats occasionally profile observations during the passage of tropical cyclones. These in-situ observations are valuable and useful in studying the ocean’s response to tropical cyclones, which are rarely observed due to harsh weather conditions. In this paper, the upper ocean response to the tropical cyclones in the northwestern Pacific during 2000–2005 is analyzed and discussed based on the data from Argo profiling floats. Results suggest that the passage of tropical cyclones caused the deepening of mixed layer depth (MLD), cooling of mixed layer temperature (MLT), and freshening of mixed layer salinity (MLS). The change in MLT is negatively correlated to wind speed. The cooling of the MLT extended for 50–150 km on the right side of the cyclone track. The change of MLS is almost symmetrical in distribution on both sides of the track, and the change of MLD is negatively correlated to pre-cyclone initial MLD.