Urban cultivation in Accra: an examination of the nature, practices, problems, potentials and urban planning implications

The literature on urban farming in Sub-Saharan African cities reveals that most studies have been conducted in Eastern, Southern and Central African cities. A few have focused on West Africa, including Sierra Leone, Guinea Bissau, and Cameroon. In Ghana there is a paucity of information on urban farming. The purpose of this paper is to examine the status of urban cultivation in Accra, Ghana's capital, reviewing existing research, and to present new empirical findings on urban cultivation emphasizing on its history, nature, practices, problems, potentials and urban planning implications.     

三代领导人城市布局思想与政策绩效分析

城市作为社会、经济、文化活动空间集聚面形成了社会景观, 其产生和发展是各种社会经济要素的空间流动和地理集中的结果。城市不但是人口集聚地, 而且成为各种产业的集聚中心。本文所及的城市布局、规范的范围始于新中国建立。20世纪50年来, 三代领导人在城市布局理论、方法和实践上的特色有许多值得总结的东西     

美国城市化经验对江苏城市化战略的启示

美国城市化经历了发生、发展、成熟的完整过程 ,具体表现为集中和分散两个显著特征 ;我国江苏城市化进程中的独特现象与美国城市化形成鲜明对比 ,通过比较、借鉴 ,江苏必须走出一条符合省情的城市化道路。     

Urban Housing as an Issue of Redistribution through Planning? The Case of Dhaka City

The rapid growth of population, the mushrooming of poor settlements and unplanned urbanization have crucial implications for the efficiency and equity of urban services. The resultant infringements of critical human rights throw into focus the importance of housing as a social policy issue. Urban services are strained in Dhaka city. Urban management has been disrupted as a result of spatial encroachment and environmental degradation. In addition to land scarcity, land speculation and endemic corruption, the high price of land is also a product of the system of land registration. The dearth of valuable urban land, together with delays in urban planning and its implementation, have made the acquisition of land for housing prohibitively expensive for middle and low‐income households. Consequently, the quality of the housing environment is deteriorating. The problem of housing finance is intrinsically linked to its affordability, being currently the prerogative only of the affluent. This article delineates the inherent lack of integrated urban planning, the lacunae within institutions responsible for urban management – and, contextually, the nature of housing as a social policy issue, where reinforced, coordinated planning and administration could ensure distributive benefits even to the poor.     

论高等教育发展的适切性--兼论高等教育对农村的适切性

适切性是高等教育发展的永恒追求。高等教育发展是对社会和个人教育需求的适应、满足以及适切性增强的过程,高等教育发展应更加切合农村社会和农村个人高等教育需求,引入农村“需求导向”,以多样化、多层次、多形式的多元高等教育结构,通过以高校为主体的“自适应”,增加高等教育在农村的有效供给。     

西部大开发中新疆城镇发展的对策研究

实施西部大开发是国家提出的一项重大战略决策。城市是社会经济发展的一个重要组成部分 ,如何对待城市的发展问题 ,关系到西部地区开发成败的关键。本文首先分析了新疆城镇发展的主导因素 ,指出以政府为主导的发展模式是新疆城镇发展缺乏内在动力的原因。然后从城镇空间分布及城镇体系等方面分析了目前新疆城镇发展的主要特征及存在的问题。最后在以上分析的基础上 ,提出了今后城镇发展的对策与建议     

Tree health mapping with multispectral remote sensing data at UC Davis, California

Tree health is a critical parameter for evaluating urban ecosystem health and sustainability. Traditionally, this parameter has been derived from field surveys. We used multispectral remote sensing data and GIS techniques to determine tree health at the University of California, Davis. The study area (363 ha) contained 8,962 trees of 215 species. Tree health conditions were mapped for each physiognomic type at two scales: pixel and whole tree. At the pixel scale, each tree pixel within the tree crown was classified as either healthy or unhealthy based on vegetation index values. At the whole tree scale, raster based statistical analysis was used to calculate tree health index which is the ratio of healthy pixels to entire tree pixels within the tree crown. The tree was classified as healthy if the index was greater than 70%. Accuracy was checked against a random sample of 1,186 trees. At the whole tree level, 86% of campus trees were classified as healthy with 88% mapping accuracy. At the pixel level, 86% of the campus tree cover was classified as healthy. This tree health evaluation approach allows managers to identify the location of unhealthy trees for further diagnosis and treatment. It can be used to track the spread of disease and monitor seasonal or annual changes in tree health. Also, it provides tree health information that is fundamental to modeling and analysis of the environmental, social, and economic services produced by urban forests.     

试析利他行为的不同类型及其原因

利他行为可区分为软利他行为和硬利他行为.软利他行为可以用人的利己心解释,而硬利他行为则否.硬利他行为又可以分为有限硬利他行为和无限硬利他行为,有限硬利他行为服从边际效用递减率,而无限硬利他行为则否.无限硬利他行为的形成与进化无法单纯用个体之间的竞争来解释,它是人类在个体之间和群体之间多个层次的竞争当中的适应性行为,是在多层竞争中形成与进化的,是多层竞争选择的结果.     

獭兔养殖综合技术研究

对獭兔的适应性、饲养管理、疾病防治、产品加工等养殖综合技术进行了研究,提出了獭兔的“三改、两杯、两早一分和两选两适”规范化饲养管理制度和疾病综合防治技术措施,探索出了优质獭兔毛皮和“富钙兔肉脯”的加工工艺以及獭兔良种推广的有效途径。     

价值哲学的认识论转换--乌尔班价值理论研究

从乌尔班的《评价 :其性质及其法则》开始 ,价值哲学的研究主题发生了一种根本性的转变 :由新世界图景的价值哲学建构 ,转向对价值哲学理论的研究。换言之 ,在此之后价值哲学研究结束了形而上学阶段 ,而进入了认识论阶段。在认识论阶段 ,评价问题成为最为重要的研究课题。在对评价问题的研究中 ,乌尔班开创了一种以心理学为基础的经验论研究理路。我国近 2 0年的价值哲学的研究范式与乌尔班开始的美国价值哲学的研究范式十分相似。