中国城市尺度科学知识网络与技术知识网络结构的时空复杂性

知识在产业集聚、区域创新中的地位越来越突出,城市知识储量及其在区域知识网络中的地位对城市的综合竞争力有重要影响。学术论文合作与专利合作是知识溢出的体现形式,是科学和技术发展的重要成果,也是度量区域创新能力的主要指标。以2000-2009年中国生物技术领域合著论文和共同申请专利的信息为原始数据,分别构建中国城市间科学知识网络(scientific knowledge network,SKN)与技术知识网络(technological knowledge network,TKN)。运用复杂网络与地学空间分析方法,从整体网络结构特征、择优链接性、中心城市及其自我网络的空间特征等方面进行分析,探究知识溢出的时空复杂性。研究表明:1 SKN和TKN具有无标度网络特征;SKN节点度数的异质性高于TKN。2两种网络均呈异配性,即城市选择合作对象存在明显择优链接性,知识溢出具有粘着性和空间依赖性。3 SKN中心城市具有明显的等级结构,空间分布总体呈"大分散小集聚"特点;TKN中心城市层级结构不明显,尚未形成明显极化中心。4 SKN中心城市自我网络的合作空间,由最初的沿海省会城市间的合作转向长三角、珠三角、京津冀等区域间和沿海城市与内陆城市间的合作,区域间知识溢出明显;TKN中心城市自我网络仍多分布于沿海城市和少数中西部省会城市,区域间知识溢出不明显。5 SKN中心城市及其自我网络的时空演变存在等级扩散和传染扩散的现象,符合时空梯度推移规律,且空间等级梯度逐渐向扁平化转变;TKN中心城市及其自我网络的时空演变以等级扩散为主,时空梯度推移现象不明显。研究结论为量化知识溢出及知识溢出网络结构的时空演化过程提供新的研究视角,对城市创新政策的制定有一定借鉴意义。     

Do people “personally experience” global warming,and if so how,and does it matter?

For most people, the direct and personally observable signals of climate change should be difficult to detect amid the variability of everyday weather. Yet, previous research has shown that some people believe they have personally experienced global warming. Through four related studies, our paper sheds light on what signals of global warming some people believe they are detecting, why, and whether or not it matters. These studies were conducted using population survey and climatic data from a single county in Michigan. Study 1 found that 27% of the county's adult residents felt that they had personally experienced global warming. Study 2 – based on content analysis of people's open-ended responses – found that the most frequently described personal experiences of global warming were changes in seasons (36%), weather (25%), lake levels (24%), animals and plants (20%), and snowfall (19%). Study 3 – based on NOAA climatic data – found that most, but not all, of these detected signals are borne out in the climatic record. Study 4 – using the survey data – found that personal experience of global warming matters in that it predicts perceptions of local risk of global warming, controlling for demographics, political affiliation, and cultural beliefs about national policy outcomes. We conclude that perceived personal experience of global warming appears to heighten people's perception of the risks, likely through some combination of direct experience, vicarious experience (e.g., news media stories), and social construction.     

Chemical studies of copper-organic complexes isolated from estuarine waters using C18 reverse-phase liquid chromatography

Dissolved organic matter (DOM) and dissolved copper-organic complexes were isolated from the estuarine waters of Narragansett Bay, RI, using reverse-phase liquid chromatography employing C₁₈ Sep-Pak cartridges (Waters Associates). The cartridges were found to have a constant retention efficiency for processing ? 1-l volumes of seawater. Fractionation of the isolated material, by sequential elution of the Sep-Pak with water: methanol mixtures of increasing organic solvent concentration, yielded a fraction of the organic matter with a specific copper activity six times greater than the overall activity for the isolated DOM. Analysis of this fraction by high performance liquid chromatography suggested that the organic components are of intermediate polarity and have appreciable aromatic character.An investigation of the protonation characteristics of the isolated complexes indicated that most of the copper is associated with a broad range of acidic sites on the DOM. Analysis by electron paramagnetic resonance spectroscopy confirmed the organic association of the isolated copper and also suggested the presence of several types of binding sites which probably involve oxygen donor ligands.Studies of the exchange of ⁶⁴Cu with these binding sites on the isolated DOM indicated that 70% of the sites undergo rapid exchange with copper in seawater while 20% of these sites did not exchange in a 24-h time period.     

Exact formulas for approximating variogram function integrals

The application of regionalized variables requires the estimation of the variogram function and the evaluation of its integral. By representing the variogram by a polygonal function the integral may be easily approximated by closed form representations of polygonal integrals. This approach provides a basis for more extensive statistical evaluation not evident in existing approximation methods. This paper provides the closed form representations for two-dimensional variogram functions whose domain is represented by a finite collection of rectangles.     

AGRICULTURAL DROUGHT ON SOUTH-CENTRAL PACIFIC ISLANDS *

A pilot study of spatial patterns of agricultural drought hazard in the south-central Pacific is presented. The durations of crop stress periods are estimated using a water balance approach. A rainfall approach is used to identify dry periods corresponding to different durations. Strong correlation between the results of the two methods indicates that monthly rainfall data are sufficient for estimating the patterns of agricultural drought hazard in the region. The simpler rainfall method is particularly useful for high islands where data required for the water balance approach are not sufficient to characterize the complex climatic patterns. Drought hazard is greatest in the eastern and southwestern parts of the study area. Great spatial variation in drought hazard is observed in a small area on the high islands of Western Samoa, where the range of values found within a few tens of kilometers is about the same as the range found across thousands of kilometers for low islands.     

Scaling Properties of Biologically Active Scalar Concentration Fluctuations in the Atmospheric Surface Layer over a Managed Peatland

The higher-order scalar concentration fluctuation properties are examined in the context of Monin–Obukhov similarity theory for a variety of greenhouse gases that have distinct and separate source/sink locations along an otherwise ideal micrometeorological field site. Air temperature and concentrations of water vapour, carbon dioxide and methane were measured at high frequency (10 Hz) above a flat and extensive peat-land soil in the San Joaquin–Sacramento Delta (California, USA) area, subjected to year-round grazing by beef cattle. Because of the heterogeneous distribution of the sources and sinks of CO₂ and especially CH₄ emitted by cattle, the scaling behaviour of the higher-order statistical properties diverged from predictions based on a balance between their production and dissipation rate terms, which can obtained for temperature and H₂O during stationary conditions. We identify and label these departures as ‘exogenous’ because they depend on heterogeneities and non-stationarities induced by boundary conditions on the flow. Spectral analysis revealed that the exogenous effects show their signatures in regions with frequencies lower than those associated with scalar vertical transport by turbulence, though the two regions may partially overlap in some cases. Cospectra of vertical fluxes appear less influenced by these exogenous effects because of the modulating role of the vertical velocity at low frequencies. Finally, under certain conditions, the presence of such exogenous factors in higher-order scalar fluctuation statistics may be ‘fingerprinted’ by a large storage term in the mean scalar budget.     

The meteorological framework and the cultural memory of three severe winter-storms in early eighteenth-century Europe

Three violent eighteenth-century storms that ravaged the North Sea area (1703), western central Europe (1739) and Portugal (1739) are investigated from the point of view of their meteorological setting, their socio-economic impact, and whether and by what means they secured an enduring place in the cultural memory. The evidence draws on individual narrative sources such as chronicles and poems, and institutional sources such as ship’s logbooks and state-organised ‘windthrow’ inventories of tree loss. Each of the three storms had socio-economic impacts that could be described as ‘war-like’ in the damage caused to buildings and the destruction of forests. The “Great Storm” of December 1703 jeopardized English naval supremacy in the War of the Spanish Succession by sinking a number of Royal Navy ships and taking the life of more than 8000 seamen. In January 1739 two similarly destructive storms swept over mainland Europe. The cultural memory of the three events here considered was however strikingly different. The sequence of storms in January 1739 though being the most protracted of the last centuries, and well-chroniceled, did not persist in the collective memories of those in France, Switzerland and elsewhere who experienced them. Likewise, the “Great Storm” was quickly forgotten on the continent, whereas its memory remained deeply rooted in England through the writings of Defoe (1704). In Portugal the 1739 storm won a lasting place in the country’s cultural memory owing to two poems that it inspired. Furthermore, it was recorded in the Kingdom’s official newspaper, in the astronomical prognoses and in written records of the Old Regime’s cultural elite.     

Venus express: Highlights of the nominal mission

Venus Express is the first European (ESA) mission to the planet Venus. Its main science goal is to carry out a global survey of the atmosphere, the plasma environment, and the surface of Venus from orbit. The payload consists of seven experiments. It includes a powerful suite of remote sensing imagers and spectrometers, instruments for in-situ investigation of the circumplanetary plasma and magnetic field, and a radio science experiment. The spacecraft, based on the Mars Express bus modified for the conditions at Venus, provides a versatile platform for nadir and limb observations as well as solar, stellar, and radio occultations. In April 2006 Venus Express was inserted in an elliptical polar orbit around Venus, with a pericentre height of ～250 km and apocentre distance of ～66000 km and an orbital period of 24 hours. The nominal mission lasted from June 4, 2006 till October 2, 2007, which corresponds to about two Venus sidereal days. Here we present an overview of the main results of the nominal mission, based on a set of papers recently published in Nature, Icarus, Planetary and Space Science, and Geophysical Research Letters.