城市可持续发展的问题与对策

城市的发展基于对环境资源的利用,但这一利用的同时又造成了对环境资源不可避免的破坏,如何维持保护人类的生存环境,实现城市的可持续发展,就成为当今城市研究的主题。本文就当今城市发展中所出现的一系列问题做了较深入的探讨,并相应提出了促进城市可持续发展的种种对策。     

基于手机位置数据的四川九寨沟7.0级地震人流分析

2017年8月8日四川九寨沟7.0级震后,浙江省地震局利用大数据采集了1031.99万条手机位置记录和4.46万个空间格网位置。本文结合24hr连续定位的手机数据,使用手机位置数据分别对九寨沟灾区人口从时间和地理维度上进行了量化分析,估计了多维人口分布的偏差,同时,探讨了剔除微观误差数据用户来估算灾区通讯基站退服分布的方法。该项工作为震后快速获取灾区人口实时动态分布提供了有效途径,同时也为地震灾害评估提供了较准确的依据。     

Comparison of life-history parameters and effectiveness in competition with Moina macrocopa between two Keratella tropica morphs

Competition and predation are the two major biotic interactions in zooplankton community. Various rotifer species exhibit polymorphism in lorica and spine morphology in the presence of predators and competitors, which effectively increases their defence competition capacity. This study compared life-history parameters between long-spined morph (LSM) and short-spined morph (SSM) of Keratella tropica at three temperatures. The results showed that both morphs showed significantly higher intrinsic rate of population increase at 25 °C than those at 20 °C and 30 °C. The intrinsic rate of population increase was significantly lower in LSM than SSM at 25 °C and 30 °C, and the net reproductive rate was significantly lower in LSM than SSM at 30 °C. These results suggested that K. tropica had cost on development of long spines, which, however, was dependent on temperature. Moreover, the competition outcome of LSM and SSM with Moina macrocopa were investigated at three densities of Scenedesmus obliquus (0.5 × 10⁶, 1.0 × 10⁶ and 2.0 × 10⁶ cells/mL) and three initial densities of M. macrocopa (0.1, 0.3 and 0.9 ind./mL), revealing that both LSM and SSM populations decreased significantly at all tested algal densities and Moina levels. LSM showed higher population growth rate than SSM at lower algal density (0.5 × 10⁶ cells/mL) and higher Moina densities (0.3 and 0.9 ind./mL), which suggested that LSM could be more effective to defend M. macrocopa. Three-way analysis of variance showed no significant effects of algal density on population growth rate of K. tropica, but interaction between algal density and M. macrocopa density significantly affected its population growth rate.     

和田地区人口与经济发展时空演变与分布差异研究

以和田地区七县一市作为研究基本单元,根据1995-2014 年人口、GDP和人均GDP面板数据分析了其人口与经济发展演变特征,通过人口经济一致性指数、偏离度指数和Pearson 相关系数探讨了和田地区人口经济分布的差异性,研究发现：近20 a 来和田地区人口和经济快速增长,各县市人口数量和经济发展差异很大;人口集聚与经济集聚水平差异较大并呈现扩大趋势,总体上东部地区人口集聚低于经济集聚,中部地区人口经济集聚基本一致,西部地区人口集聚高于经济集聚;人口分布与经济发展空间一致性总体呈变弱的趋势,人口经济分布差异的变大与地区经济差距的变大有非常高的相关性;地区的自然环境条件和社会经济发展条件是造成和田人口和经济分布差异性的主要原因。     

http://dx.doi.org/10.1016/j.gsf.2016.04.002

Population synthesis studies into planet formation have suggested that distributions consistent with observations can only be reproduced if the actual Type Ⅰ migration timescale is at least an order of magnitude longer than that deduced from linear theories.Although past studies considered the effect of the Type I migration of protoplanetary embryos,in most cases they used a conventional formula based on static torques in isothermal disks,and employed a reduction factor to account for uncertainty in the mechanism details.However,in addition to static torques,a migrating planet experiences dynamic torques that are proportional to the migration rate.These dynamic torques can impact on planet migration and predicted planetary populations.In this study,we derived a new torque formula for Type Ⅰ migration by taking into account dynamic corrections.This formula was used to perform population synthesis simulations with and without the effect of dynamic torques.In many cases,inward migration was slowed significantly by the dynamic effects.For the static torque case,gas giant formation was effectively suppressed by Type I migration;however,when dynamic effects were considered,a substantial fraction of cores survived and grew into gas giants.     

Disturbance of recruitment success of mantis shrimp in Tokyo Bay associated with effects of hypoxia on the early life history

We investigated effects of severe hypoxia (dissolved oxygen <1 ml l⁻¹) on recruitment of mantis shrimp Oratosquilla oratoria in Tokyo Bay. Ten-year field surveys were conducted to examine quantitative relationships in annual mean densities of larvae and juveniles, and spatial distribution of juveniles and severe hypoxia. There was no significant correlation between annual mean densities of larvae and juveniles, suggesting that mortality during larval or juvenile stages varies among years, which might have regulated abundance of young-of-the-year juveniles. Juvenile density was low in the severely hypoxic area, implying that hypoxia could affect survivals and spatial distribution of juveniles. Meanwhile, there are yearly fluctuations in juvenile density in normoxic areas of both northern and southern part of the bay. This evidence suggests that abundance of post-settled juveniles might have been determined by not only effects of hypoxia, but also other factors influencing mortality during the early life stages.     

2011 年夏季胶州湾三种大型水母的种群动态研究

2011年8月1日-9月30日,对胶州湾三种大型水母沙海蛰(Nemopilema nomurai)、白色霞水母(Cyanea nozakii)、海月水母(Aurelia aurita)的种群数量变动及空间分布情况开展了目测调查,同步获得了气象、水温、盐度、叶绿素a、浮游动物丰度、种类组成等数据,调查频率为每周2次。调查期间,海月水母表现出逐渐降低的趋势,沙海蛰与白色霞水母种群均于8月11日达到数量高峰,8月底及9月中旬之后依次衰落,至9月底,三种水母基本消失。三种水母的种群平均丰度变化范围分别为:沙海蛰0-230.8ind/km2;霞水母0-150.2ind/km2;海月水母0-123.4ind/km2。从分布区域来看,海月水母主要位于近岸区,沙海蜇主要分布于湾口和中部深水区,而白色霞水母则在高峰期和次高峰期分别集中于深水区和近岸区。结合往年资料,作者认为,海月水母种群能够在胶州湾内进行自我补充并完成其生活史,而胶州湾沙海蛰与霞水母的种群补充则可能主要依赖于湾外种群。另外,目测方法的准确性可能受到气象条件的影响。     

Species diversity and regeneration of native species in Pennisetum ciliare (buffelgrass) pastures from the thornscrub of Sonora,México

To examine the influence of buffelgrass land conversion and pasture management on native species diversity and regeneration patterns, we describe community attributes and population structure in four different active pastures in thornscrub vegetation from eastern Sonora, Mexico. We compare a relatively undisturbed thornscrub community with a contiguous five years old active pasture, to identify species able to regenerate under current management practices. Buffelgrass conversion has a significant influence on species diversity and other community attributes. Active pastures have lower species diversity, crown cover and basal area of native species than the studied native thornscrub. An active pasture subjected to heavy grazing and without management of the thorny legume, Acacia cochliacantha, showed the lower species diversity and an almost monospecific stand of this legume. It is likely that the reduction in species diversity is caused by the conversion process, inadequate management and regeneration barriers that limit seedling establishment in active pastures. Our data recorded eight native species (13%) that were able to regenerate in active pastures. However, the great majority of native species were unable to regenerate under pastures. This study shows that under current management, active buffelgrass pastures maintain only a small fraction of native species with regenerating populations in the thornscrub.     

Predicting socioeconomic conditions from satellite sensor data in rural developing countries: A case study using female literacy in Assam,India

Social data from census and household surveys provide key information for monitoring the status of populations, but the data utility can be limited by temporal gaps between surveys. Recent studies have pointed to the potential for remotely sensed satellite sensor data to be used as proxies for social data. Such an approach could provide valuable information for the monitoring of populations between enumeration periods. Field observations in Assam, north-east India suggested that socioeconomic conditions could be related to patterns in the type and abundance of local land cover dynamics prompting the development of a more formal approach. This research tested if environmental data derived from remotely sensed satellite sensor data could be used to predict a socioeconomic outcome using a generalised autoregressive error (GAR_err) model. The proportion of female literacy from the 2001 Indian National Census was used as an indicator of socioeconomic conditions. A significant positive correlation was found with woodland and a significant negative correlation with winter cropland (i.e., additional cropping beyond the normal cropping season). The dependence of female literacy on distance to nearest road was very small. The GAR_err model reduced residual spatial autocorrelation and revealed that the logistic regression model over-estimated the significance of the explanatory covariates. The results are promising, while also revealing the complexities of population–environment interactions in rural, developing world contexts. Further research should explore the prediction of socioeconomic conditions using fine spatial resolution satellite sensor data and methods that can account for such complexities.     

Use of an expert system to map forest soils from a geographical information system

Abstract

Mapping forest soils using conventional methods is time consuming and expensive. An expert system is described and applied to the mapping of five forest soil-landscape units formed on a single granitoid parent material. Three thematic maps were considered important in influencing the distribution of soils. The first showed the distribution of nine classes of native eucalypt forests, and the second and third were derived from a digital elevation model and represented slope gradient and a soil wetness index combined with topographical position. These layers were input to a raster based geographical information system (GIS) and then geometrically co-registered to a regular 30 m grid. From a knowledge of soil distributions, the relationships between the soil-landscape units and the three data layers were quantified by an experienced soil scientist and used as rules in a rule based expert system. The thematic layers accessed from the GIS provided data for the expert system to infer the forest soil-landscape unit most likely to occur at any given pixel. The soil-landscape map output by the expert system compared favourably with a conventional soil-landscape map generated using interpretation of aerial photographs.