东亚地区陆地植被净初级生产力与夏季气候的模拟

利用中国科学院大气物理研究所(IAP)一个海洋-大气-动态植被耦合模式(GOALS-AVIM),进行了100年模拟积分.基于模拟结果,对东亚地区的植被净初级生产力(NPP)、降水、地面气温和短波辐射的季节变化进行了标准化对比,分析了NPP的时空格局与气候因子(气温、短波辐射和降水)的关系;利用奇异值分解(SVD)对东亚夏季降水场和NPP的关系进行分解.结果表明,夏季东亚地区植被NPP及相关气候因子的时空变化规律明显,耦合模式可以很好地模拟出观测存在的降水及NPP、LAI(叶面积指数)大值区随季节北移南退的形态;由于耦合模式中AVIM的双向特点,模式模拟的NPP与其他物理场的季节变化有很强的对应关系,而且在不同时间和地区,NPP与降水、地面气温、短波辐射表现出不同的对应关系,其中植被NPP时间变化与气温和降水的相关性都较高;从NPP场和降水场夏季逐月标准化距平奇异值分解的空间分布模态来看.NPP与降水在时空场上表现出很强的耦合性,NPP的空间格局与降水存在较好的相关性,不同地理位置的相关性强弱不同,分解出的降水场异常相关模态也再现了东亚夏季降水移动的时空特征,同时东亚雨带随季节变化与NPP的气候变率表现出不同的对应模态.     

一个海陆气耦合模式中大气-植被的年际变化及其相互作用

含有动态植被过程的陆面模式Atmosphere-Vegetation Interaction Model(AVIM)与中国科学院大气物理研究所大气科学与地球流体力学数值模拟国家重点实验室(IAP/LASG)的9层大气环流模式AGCM 及20层的海洋环流模式(OGCM)耦合,建立了一个全球模式(GoALS-AVIM)并进行100年的模拟积分.后40年的结果分析表明,该耦合模式能够合理地模拟大气及陆地生态系统显著的年际变化.用奇异值分解(SVD)分析了东亚地区植被生长和气候变化的相互关系,发现在东业区域的植被净初级生产力(NPP)强弱的变化对血着大气环流的变化,特别是NPP分别与850 hPa的风场和500 hPa的高度场表现出很强的时空一致性.在东亚地区,由于植被类型的不同,导致NPP年际变化与降水、表面气温、短波辐射的年际变化的相关性不同,它们的年际变化与相关物理量场的年际变化表现出很强的植物种类的区别.     

医用CT增益可编程的多路高速数据采集系统设计

介绍了一种医用CT增益可编程的多路高速数据采集系统,该系统以FPGA为时序控制器,以ADC4344为模数转换器,通过串行移位寄存器控制多路模拟开关实现多路模拟数据的采集,并采用可编程增益放大器提高了系统的分辨率。该系统电路结构简单,对多路高速、宽动态范围的数据采集系统具有一定的通用性,可根据系统的需要进行扩展。     

珠江口盆地惠州地区A区块碳酸盐岩油气储层预测

珠江口盆地珠江组碳酸盐岩油藏在近年取得了勘探新突破,如LF15-1油藏的成功评价,极大地鼓舞了区域碳酸盐岩勘探。由于碳酸盐岩储层非均质性强、分布复杂,受古地形、沉积环境、成岩作用叠合影响,储层评价困难。笔者在前人研究的碳酸盐岩地层速度和储层孔隙度呈线性关系成果的基础上,充分挖潜地震资料计算碳酸盐岩地层速度对研究区储层发育区进行宏观分析,结合叠前叠后联合相控反演进行碳酸盐岩储层精细刻画,在研究区评价出3个有利储层发育区,识别出有利储层Ⅰ区是一个规模超过12km2的岩性圈闭,为区域后续勘探奠定了良好基础。     

Salinity-related variation in gene expression in wild populations of the black-chinned tilapia from various West African coastal marine,estuarine and freshwater habitats

This study measured the relative expression of the genes coding for Na⁺, K⁺-ATPase 1α(NAKA), voltage-dependent anion channel (VDAC), cytochrome c oxidase-1 (COX), and NADH dehydrogenase (NDH), in gills of six wild populations of a West African tilapia species, acclimatised to a range of seasonal (rainy or dry) salinities in coastal, estuarine and freshwater sites. Previous laboratory experiments have demonstrated that these genes, involved in active ion transport, oxidative phosphorylation, and intra-cellular ATP transport, are relatively over-expressed in gill tissues of this species acclimated to high salinity. Positive correlations between relative expression and ambient salinity were found for all genes in the wild populations (Spearman rank correlation, p < 0.05), although for some genes these were only significant in either the rainy season or dry season. Most significantly, however, relative expression was positively correlated amongst the four genes, indicating that they are functionally interrelated in adaptation of Sarotherodon melanotheron to salinity variations in its natural environment. In the rainy season, when salinity was unstable and ranged between zero and 37 psu across the sites, overall mean expression of the genes was higher than in the dry season, which may have reflected more variable particularly sudden fluctuations in salinity and poorer overall water quality. In the dry season, when the salinity is more stable but ranged between zero and 100 psu across the sites, NAKA, NDH and VDAC expression revealed U-shaped relationships with lowest relative expression at salinities approaching seawater, between 25 and 45 psu. Although it is not simple to establish direct relationship between gene expression levels and energy requirement for osmoregulation, these results may indicate that costs of adaptation to salinity are lowest in seawater, the natural environment of this species. While S. melanotheron can colonise environments with extremely high salinities, up to 100 psu, this was related to high relative expression for all genes studied, indicating that this imposes increased energy demand for osmotic homeostasis in gill tissues. This study is the first to demonstrate, in fish and in wild populations, that expression of NAKA, VDAC, NDH and COX are interrelated in gill tissues, and are involved in long-term acclimatisation to a salinity range between 0 and 100 psu.     

Carbonate ramp depositional systems from a late Jurassic epeiric platform (Iberian Basin, Spain): a combined computer modelling and outcrop analysis

No counterparts to epeiric-sea carbonate ramps are known in present-day environments. This hinders the interpretation of the factors controlling the growth and evolution of these depositional settings. In this study we analyse the facies and geometries of two Jurassic examples both from outcrop study and through computer modelling. This analysis is constrained by two important features of these Oxfordian and Kimmeridgian ramps: firstly, they are very well exposed, allowing accurate reconstruction of a 200-km section from proximal to distal ramp environments, and, secondly, a time framework for correlation, section reconstruction and modelling is provided by a well-defined ammonite biostratigraphy. The modelling results in a synthetic stratigraphy which closely matches the reconstructed cross-sections and, when integrated with the field study, constrains and provides additional quantitative data on the following aspects of carbonate ramp systems. Resedimentation by storms is an important process in maintaining the ramp profile through time. Down-ramp transport distances of between 25 and 40 km are indicated from the distribution of storm beds and shallow-water allochems and from model-matching known stratigraphic thicknesses and geometries. Modelling sediment production within the time constraints from the ammonite biozones indicates that shallow-water carbonate production was 1–2 orders of magnitude less than that predicted for present-day open-marine carbonate platforms. Deeper-water production rates were reduced by lesser amounts. These proportionally higher, outer-ramp production rates also help to maintain ramp geometries through time. The enigmatic slope crest of ramps is shown to result from a combination of higher, shallow-water production and erosion rates, together with loss of accommodation during highstands and high-stillstands in the modelled sea-level curves. The most parsimonious modelling of the two ramp sequences comes from a relative sea-level curve composed of a linear subsidence component superposed by 20- and 100-kyr cycles on a third-order cycle. The third-order cycles and their timing do not correspond to those of the Exxon curve.     

A data-synthesis-driven method for detecting and extracting vague cognitive regions

Cognitive regions and places are notoriously difficult to represent in geographic information science and systems. The exact delineation of cognitive regions is challenging insofar as borders are vague, membership within the regions varies non-monotonically, and raters cannot be assumed to assess membership consistently and homogeneously. In a study published in this journal in 2014, researchers devised a novel grid-based task in which participants rated the membership of individual cells in a given region and contrasted this approach to a standard boundary-drawing task. Specifically, the authors assessed the vague cognitive regions of Northern California and Southern California. The boundary between these cognitive regions was found to have variable width, and region membership peaked not at the most northern or southern cells but at substantially less extreme latitudes. The authors thus concluded that region membership is about attitude, not just latitude. In the present work, we reproduce this study by approaching it from a computational fourth-paradigm perspective, i.e., by the synthesis of high volumes of heterogeneous data from various sources. We compare the regions which we identify to those from the human-participants study of 2014, identifying differences and commonalities. Our results show a significant positive correlation to those in the original study. Beyond the extracted regions themselves, we compare and contrast the empirical and analytical approaches of these two methods, one a conventional human-participants study and the other an application of increasingly popular data-synthesis-driven research methods in GIScience.     

A weighted multi-attribute method for matching user-generated Points of Interest

To a large degree, the attraction of Big Data lies in the variety of its heterogeneous multi-thematic and multi-dimensional data sources and not merely its volume. To fully exploit this variety, however, requires conflation. This is a two-step process. First, one has to establish identity relations between information entities across different data sources; and second, attribute values have to be merged according to certain procedures that avoid logical contradictions. The first step, also called matching, can be thought of as a weighted combination of common attributes according to some similarity measures. In this work, we propose such a matching based on multiple attributes of Points of Interest (POI) from the Location-based Social Network Foursquare and the local directory service Yelp. While both contain overlapping attributes that can be used for matching, they have specific strengths and weaknesses that make their conflation desirable. For instance, Foursquare offers information about user check-ins to places, while Yelp specializes in user-contributed reviews. We present a weighted multi-attribute matching strategy, evaluate its performance, and discuss application areas that benefit from a successful matching. Finally, we also outline how the established POI matches can be stored as Linked Data on the Semantic Web. Our strategy can automatically match 97% of randomly selected Yelp POI to their corresponding Foursquare entities.     

Access to supermarkets among poorer neighborhoods: a comparison of time and distance measures

This research assesses neighborhood differences in access to supermarkets for the Portland, Oregon region. Five-year American Community Survey data for the 2006–2010 period are used to compare a travel time and distance measure of supermarket access for neighborhoods of concentrated poverty relative to other neighborhoods, taking into account their distance to the city center. Poor and nonpoor outer neighborhoods have longer average travel times and distances to nearby supermarkets than their more centralized counterparts. Poor outer neighborhoods fare better on travel distance than nonpoor outer neighborhoods do, but endure penalties in longer travel times. This research demonstrates the potential for variation in results across methods measuring access to neighborhood amenities and suggests that more nuanced methodology will be required for us to understand sociospatial disparities in access.