70 research outputs found

    No.08: IMPROVING THE PROFITABILITY OF WET MARKET FOOD VENDORS IN CHINA

    Get PDF
    ■ The characteristics of individual vendors and their business operations have a more significant impact on business profits than more general socioeconomic factors. Policy interventions need to prioritize the former. ■ The profits of wet market vendors vary spatially in Nanjing, China. The average profit level in central urban districts is higher than in peri-urban districts. ■ Almost all determinants have more significant impacts on vendor profitability in peri-urban than urban areas. Measures should therefore be taken to improve the profitability of wet market vendors in peri-urban areas

    No. 14: The Impact of Proximity to Wet Markets and Supermarkets on Household Dietary Diversity in Nanjing City, China

    Get PDF
    Existing studies suggest that despite the proliferation of supermarkets, traditional wet markets have persisted in many countries and have been playing an important role in people’s daily food access. Yet, studies investigating the issue of food access and its influences on food security have mainly focused on food deserts and the proximity to supermarkets, with limited focus on wet markets and other food outlets. This study investigates the influence of the proximity to wet markets and supermarkets on urban household dietary diversity in Nanjing. Based on the data collected through a citywide survey in 2015 and the map data of wet markets and supermarkets, the Poisson regression model was deployed to examine the correlations between geographical proximity to supermarkets and wet markets and household dietary diversity. The results show that the coefficients for the distance to the nearest wet market are not statistically significant. Although the coefficients for the distance to nearest supermarket are statistically significant, they were too minor to be of practical importance. We argue, however, that the insignificant correlations reflect exactly the high physical accessibility to food outlets and the extensive spatially dense food supply network constituted by wet markets, supermarkets and small food stores in Nanjing. This is verified by the survey data that more than 90% of households purchased fresh food items within their neighbourhoods or in walking distance. In addition to the densely distributed food outlets, various other factors contributed to the non-significant influence of the distance to the nearest wet market and supermarket, including the many small food stores within or close to residential communities, the prevalence of three-generation extended households and high household income. This study highlights the importance of allowing mixed land use for food outlets with residential land and integrating wet markets into urban infrastructure planning

    A BMS-invariant free scalar model

    Full text link
    The BMS (Bondi-van der Burg-Metzner-Sachs) symmetry arises as the asymptotic symmetry of flat spacetime at null infinity. In particular, the BMS algebra for three dimensional flat spacetime (BMS3_3) is generated by the super-rotation generators which form a Virasoro sub-algebra with central charge cLc_L, together with mutually-commuting super-translation generators. The super-rotation and super-translation generators have non-trivial commutation relations with another central charge cMc_M. In this paper, we study a free scalar theory in two dimensions exhibiting BMS3_3 symmetry, which can also be understood as the ultra-relativistic limit of a free scalar CFT2_2. Upon canonical quantization on the highest weight vacuum, the central charges are found to be cL=2c_L=2 and cM=0c_M=0. Because of the vanishing central charge cM=0c_M=0, the theory features novel properties: there exist primary states which form a multiplet, and the Hilbert space can be organized by an enlarged version of BMS modules dubbed the staggered modules. We further calculate correlation functions and the torus partition function, the later of which is also shown explicitly to be modular invariant.Comment: 59 pages, 5 figures. v2, minor revision: typos correted and some statement rephrase

    Monodisperse SiO2 Microspheres with Large Specific Surface Area: Preparation and Particle Size Control

    Get PDF
    Monodisperse SiO2 microspheres have found applications in catalysis, drug delivery, coatings, cosmetics, optical sensing and plastics. The particle size of monodisperse SiO2 microspheres is closely related to its application. In this paper, monodisperse SiO2 microspheres with tunable diameter were successfully synthesized using cetyltrimethylammonium bromide (CTAB) as template. The monodisperse SiO2 microspheres with diameters ranging from 200 nm to 3 ÎŒm were obtained by controlling the concentration of CTAB, tetraethyl orthosilicate (TEOS), diethanolamine (DEA) and reaction temperature. The BET surface area could reach 835 m2‱g-1 and mean pore diameter was 2.3 nm. The formation mechanism of monodisperse SiO2 microspheres was investigated

    No. 24: Achieving Urban Food Security through a Public-Private Hybrid Food Provisioning System: A Case Study of Nanjing, China

    Get PDF
    Private and public markets are two models of urban food retailing governance. This paper examines the public-private hybrid model of urban food provisioning system and its governance in Nanjing, China. Based on data from surveys, non-structured interviews, and bibliographical material analysis, we examine the public-private hybrid model and its linkages with urban food security. Our analysis shows that the public-private hybrid model of food markets and its governance ensures a relatively high-level urban food security in Nanjing. We argue that the hybrid food market governance system effectively integrates public and private capital into a government-supported and regulated, small-business-based system in both food wholesale and retailing sectors. In the public-private hybrid system, wholesale markets and wet markets provide a physical “marketplace” for small-scale private food vendors to operate their business, while the private capital-based supermarkets is also integrated into the system of urban food provisioning. The paper reveals how the “crawling peg” policy and the regulation on the usage of marketplaces have ensured that the development of wet markets keeps pace with population growth. While the public-private hybrid system helps avoid market failure and government failure in food provisioning, it faces challenges such as reliance on fiscal inputs

    No. 24: Achieving Urban Food Security Through a Public-Private Hybrid Food Provisioning System: A Case Study of Nanjing, China

    Get PDF
    Private and public markets are two models of urban food retailing governance. This paper examines the public-private hybrid model of urban food provisioning system and its governance in Nanjing, China. Based on data from surveys, non-structured interviews, and bibliographical material analysis, we examine the public-private hybrid model and its linkages with urban food security. Our analysis shows that the public-private hybrid model of food markets and its governance ensures a relatively high-level urban food security in Nanjing. We argue that the hybrid food market governance system effectively integrates public and private capital into a government-supported and regulated, small-business-based system in both food wholesale and retailing sectors. In the public-private hybrid system, wholesale markets and wet markets provide a physical “marketplace” for small-scale private food vendors to operate their business, while the private capital-based supermarkets is also integrated into the system of urban food provisioning. The paper reveals how the “crawling peg” policy and the regulation on the usage of marketplaces have ensured that the development of wet markets keeps pace with population growth. While the public-private hybrid system helps avoid market failure and government failure in food provisioning, it faces challenges such as reliance on fiscal inputs

    Comprehensive food system planning for urban food security in Nanjing, China

    Get PDF
    Food system planning is important to achieve the goal of “zero hunger” in the UN’s 2030 Agenda for Sustainable Development (UN, 2016). However, discussion about comprehensive planning for food security is scarce and little is known about the situation in Chinese cities. To narrow this gap, this study collected and analyzed four medium-term plans and two annual plans for the “vegetable basket project” in Nanjing, China. This study examines the strategies for urban food security in Nanjing to shed light on how the city developed a comprehensive approach to food system planning over the past three decades. The evolution of incremental food system planning in Nanjing provides valuable lessons for other cities facing food security challenges and shortages of financial resources. Reducing food insecurity is an ongoing challenge for the city governments in the Global South and comprehensive planning is a useful tool for addressing the challenge of urban food insecurity

    Mapping Plastic Greenhouses Using Spectral Metrics Derived From GaoFen-2 Satellite Data

    Get PDF
    Plastic greenhouses are an important hallmark of agricultural progress. To meet the growing demand for vegetable and food, the amount of plastic greenhouses has increased significantly over the past few decades. Remote sensing is considered as a promising data source for taking inventory and Monitoring plastic greenhouses for managing modern agriculture. However, a systematic catalog of number and spatial distribution of plastic greenhouses is mostly inexistent. This is primarily due to the complex land surface characteristics and seasonal changes, which make automated classification based on EO data challenging. Current approaches generally suffer from the susceptibility of approaches toward thresholds and changes in the phenological stage. Besides, they often require an extensive training of models, however, often the necessary amount of training data is inexistent. To address These issues, we suggest an adaptable and universal plastic greenhouse mapping method based on very high spatial resolution optical satellite data (GaoFen-2 image) with a three-step procedure. A plastic greenhouse gathering area (100 km2) is selected for the development of the initial method. We receive a very competitive mapping accuracy 97.34% and the likelihood of plastic greenhouses being mapped correctly reaches to 95.20%. Subsequently, we transfer it to a much larger area (2025 km2) featuring a different phenological stage and different surrounding patterns. The stable mapping accuracy proves the validity of our approach
    • 

    corecore