红豆草空间诱变突变体叶片同工酶及细胞超微结构分析

经神州4号飞船搭载的红豆草种子,当代出现匍匐型突变体,其叶片同工酶谱及细胞超微结构的分析结果表明:匍匐型突变体、空间诱变直立型植株及对照之间过氧化物酶同工酶酶带数没有明显差异,其中匍匐型突变体脂酶同工酶酶带数与对照相同,空间诱变直立型植株酶带数多于对照;空间诱变的红豆草,叶片细胞壁不规则增厚,细胞质稀薄,液泡大,叶绿体变小,形状多不规则,叶绿体内淀粉粒细小、数量多,基粒片层直径小,但数量明显多于对照,匍匐型突变体表现尤为明显.     

高粱航天新不育系与恢复系的配合力分析

为了尽快鉴定高粱航天新恢复系和不育系的配合力和遗传力,采用双列不完全杂交法分析了高粱新选航天新不育系与恢复系的配合力。结果表明,不育系中产量、穗粒重的一般配合力较高的有52A和55A,恢复系中一般配合力较高的有sp42和sp46。在穗粒重性状上特殊配合力最高的组合是52A×sp46。加性方差与基因型方差的比值依次之顺序是穗粒重>株高>穗粒数>产量>千粒重>穗长。杂交种产量的髙低取决于双亲一般配合力和特殊配合力效应较高的组合,试验中52A×sp46,52A×sp42是两个较优的杂交组合。     

基于空间句法的清华大学校园历史与人文景观空间形态演变研究

基于空间句法中整合率与穿行率2个指标,对清华大学校园景观空间形态及其演变展开建模、分析与论述。通过对景观形态特征与历史社会经济特点的讨论,将清华大学校园景观形态的演变分为4个时期作为理解景观形态发展的框架,包括熙春园时期、美式校园时期、单位制时期和书院回归时期。结果表明,熙春园时期的3个重要历史景观均为现代校园师生出行的重要空间节点。不同时期关键景观节点具备通过空间形态特征,反映校园发展过程中典型文化意识形态的潜力。历史与人文景观空间节点在师生出行中逐渐向穿行地的角色靠拢。同时基于聚类分析,发现清华大学1954年前后建成的景观空间差异性较大。     

Using social media data to understand the impact of the COVID-19 pandemic on urban green space use

Having access to and visiting urban green space (UGS) improves liveability and provides considerable benefits to residents. However, traditional methods of investigating UGS visitation, such as questionnaires and social surveys, are usually time- and resource-intensive, and frequently provide less transferable, site-specific outcomes. This study uses social media data (Twitter) to examine spatio-temporal changes in UGS use in London associated with COVID-19 related lockdowns. It compares georeferenced Tweets posted in a 3 month period from 23 March to 23 June for 3 years covering the first lockdown in the UK in 2020, with Tweets for the same period in 2019 and 2021. The results show that (1) the land-use type of Public Park and Garden was the most frequently visited type of UGS, which may be correlated with these UGS areas remaining opening during the lockdown period; (2) the usage of UGS decreased in central London and increased in other areas during lockdown, which may correlated with working from home restrictions; (3) activities were positively associated with Physical activities maybe as a result of allowing people to take a single daily exercise, and (4) people spent more time in UGS areas on weekdays than weekends compared to pre-lockdown. This is the first study to examine social media data over consistent time period before, during and after the lockdown in relation to UGS. The results show that the findings and method can inform policy makers in their management and planning of UGS, especially in a period of social crisis like the COVID-19 pandemic.     

Transport infrastructure modifications and accessibility to public parks in Greater Cairo

It is widely accepted that transport infrastructure policies have significant consequences on the environment, housing, business, and people’s everyday movement. With the use of space syntax geometric (sum of angular deviations) and topological (number of directional changes) measures and conventional network metric distance, this article analyses the change in transport infrastructure in Greater Cairo between 2011 and 2021 and quantifies its likely impact on access to 57 public parks. The study advocates for a better understanding of the streetscape changes produced by transport infrastructure policies and how they may impact access to urban green spaces (UGS), particularly parks. The results suggest that the accessibility of 40 parks was reduced at both neighborhood and city-wide scales. Moreover, more than one-quarter of the total study area, including both densely populated marginalized areas and upscale neighborhoods, was significantly negatively affected by streetscape changes. Furthermore, the average distance traveled to parks increased from 3566 (m) in 2011–3612 (m) in 2021. These distances are high compared to the few hundred meters recommended in pedestrian accessibility strategies. These findings are not only important for policy makers in Egypt but will also be helpful to other similar contexts around the world by understanding and forecasting the likely implications of design changes and suggesting targeted strategies for improving access to UGS and, in turn, maximizing UGS use rates. In particular, our findings contribute to the debate on the problems caused by inner-city elevated highways. Lastly, this study provides a general analytical framework that can be applied to other cities across the globe to assess the effects of transport infrastructure changes on access to UGS.     

The usage,constraints and preferences of green space at disadvantage neighborhood: A review of empirical evidence

Neighborhood green space is closely related to the lives of every city dweller. However, some evidence showed that residents in disadvantaged neighborhoods do not fully use the green space due to quality, safety, and distance issues. Therefore, it is essential to understand how disadvantaged groups interact and use green space in these communities. However, there is still a lack of comprehensive evaluation. This research systematically sorts out the relevant literature and collects various attributes of the use, constraints, and preferences of the residents of disadvantaged neighborhoods on the green space through a systematic review method from the perspective of social ecology. Through a literature review of 4 databases (Science Direct, Scopus, web of science, and CNKI), 42 articles (N = 42) were finally included. This article concerns peer-reviewed papers published between 2008 and 2021. The research results showed that residents of disadvantaged communities' use of nearby green space are affected by personal, social, physical, and other attributes. Finally, a conceptual framework for the use, constraints, and preferences of disadvantaged neighborhood green space is proposed to help planners and designers design and improve community green space more effectively and ultimately achieve a harmonious living environment that meets various needs.     

A framework to evaluate the accessibility,visibility, and intelligibility of green-blue spaces (GBSs) related to pedestrian movement

The planning of green-blue spaces (GBSs) requires considering the pedestrian needs in their walking routes for improving the walking experience. Incorporating the quantitative spatial characteristics of pedestrian movement is essential for pedestrian-friendly urban planning, which however received insufficient attention. Based on the space syntax theory, this study provided three indicators – accessibility, visibility, and intelligibility – to demonstrate the needs of physical access, visual access, and spatial cognition, respectively, in pedestrian movement. Measuring these three indicators, this study exemplified the planning of pedestrian-friendly GBSs using Guangzhou, China as a case study. Spatial design network analysis was used to quantify heterogeneous values of accessibility, visibility, and intelligibility of each GBS throughout the city. Moreover, we used principal component analysis to identify the leading indicators based on their weightings and then to calculate the scores to compare these three aspects of GBSs. The measurements of accessibility, visibility, and intelligibility of each GBS were then averaged across urban administrative districts for evaluating city-scale GBSs. The findings showed that GBSs in central districts were most accessible and visible but least intelligible. In contrast, the overall intelligibility of GBSs throughout the city was the greatest but the visibility was the least. Furthermore, intelligibility, as a more important factor than accessibility and visibility, should be particularly emphasized in future planning of pedestrian-friendly GBSs. Pedestrians from the central districts of Guangzhou city were most satisfied with the walking experience, in terms of accessing to, viewing, and cognizing the GBSs. ‘Yuexiu’, ‘Huadu’, and ‘Nansha’ districts were found as the key places where improved accessibility, visibility, and intelligibility were particularly needed to improve the GBS pedestrian-friendliness throughout the city. In summary, this study not only demonstrated a human-scale GBS evaluation framework for improving the human walking experience but also provided empirical evidence for building pedestrian-friendly green-blue spaces at the city scale.     

基于空间句法的中山市三角镇滨水道连通性调查研究

岭南水乡的滨水道良好的连通性能提升滨水空间的活力及其休闲观光和文化体验等。随着城镇化发展，滨水道出现通畅度不佳、空间渗透能力较弱、集聚效益较低的问题。以广东省中山市三角镇为研究对象，运用空间句法研究分析，选取连接度、深度值、整体集成度、全局穿行度与步行穿行度 5 项指标数据对滨水道连通性进行分析，并运用熵权法建立评价指标体系，对三角镇滨水道连通性进行综合评价。结合实地踏勘与空间句法指标数据分析三角镇滨水道的空间形态与现状，进而提出三角镇滨水道优化建议。     

基于空间句法的广州珠江前航道滨水景观空间探讨

珠江是广州城市发展的母亲河,珠江滨水区对广州城市景观、生态、文化、社会经济等方面的建设有着重要作用。正确认识珠江滨水空间并优化珠江两岸景观,才能推进城市的可持续发展。文章基于空间句法的理论和方法,以量化的手段揭示前航道滨水景观空间与城市的结构关系和景观空间的建构问题,主要考察前航道滨水景观空间的分布特征和景观空间的渗透性,并在此基础上提出相应的优化建议。     

论城镇景观的环境意象与犯罪恐惧感

根据心理学理论，城镇景观的环境意象涵盖空间形态和空间氛围两大内容。空间形态的不良设计和缺陷会为犯罪主体提供犯罪机会和条件，从而使犯罪目标产生犯罪恐惧感；空间形态的设计主要关注景观学和社会学的关系，对犯罪恐惧感的产生构成间接影响。对于犯罪目标而言，空间氛围设计的失误和不足将直接对其造成心理影响；空间氛围设计主要关注景观学和心理学的关系，对犯罪恐惧感的产生构成直接影响。