70 research outputs found
No.08: IMPROVING THE PROFITABILITY OF WET MARKET FOOD VENDORS IN CHINA
â 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.
â 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.
â 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
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 peopleâs 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
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 (BMS) is generated by the super-rotation
generators which form a Virasoro sub-algebra with central charge ,
together with mutually-commuting super-translation generators. The
super-rotation and super-translation generators have non-trivial commutation
relations with another central charge . In this paper, we study a free
scalar theory in two dimensions exhibiting BMS symmetry, which can also be
understood as the ultra-relativistic limit of a free scalar CFT. Upon
canonical quantization on the highest weight vacuum, the central charges are
found to be and . Because of the vanishing central charge
, 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
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 m2âąg-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
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 âmarketplaceâ 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 âcrawling pegâ 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
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 âmarketplaceâ 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 âcrawling pegâ 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
Food system planning is important to achieve the goal of âzero hungerâ in the UNâs
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
âvegetable basket projectâ 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
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Can annual land use plan control and regulate construction land growth in China?
Annual land use plan (ALUP) stands for the quota allocation of land converted to non-agricultural use, which has been in place since 1987 in China. Although the ALUP has been implemented for more than 30 years and has played an important role in Chinaâs non-agricultural land growth management, little has been done to assess the effect of its implementation. The purpose of this research is to evaluate the effect of the ALUP on controlling the growth of construction land in China. The province-level data on land use in China during the period of 2006â2013 were collected and then analyzed using panel data model. The results show that (1) the ALUP can effectively curb construction land growth, and the construction land decreased about 1721 ha with a 1% increment of the intensity of growth management. Construction land growth is closely related to the implementation intensity of the ALUP, which decreases 30,892 ha under strict implementation but increases an extra 181,451 ha with relaxed implementation; (2) the implementation effect of the ALUP shows significant differences between provinces, and the provinces of northwestern and eastern China show better performance than provinces from the southwest and central regions. National development strategy and regionâs differentiation land policy may have contributed to this phenomenon; (3) taking both the goal achievement and effectiveness into account, the implementation of the ALUP is described as effective though not completely successful; and (4) for more efficiency and success, the study proposes some suggestions on improving policy implementation in the future
Mapping Plastic Greenhouses Using Spectral Metrics Derived From GaoFen-2 Satellite Data
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
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