Influence of long-term fertilization on soil aggregates stability and organic carbon occurrence characteristics in karst yellow soil of Southwest China

Current research has long focused on soil organic carbon and soil aggregates stability. However, the effects of different long-term fertilization on the composition of yellow soil aggregates and the characteristics of the occurrence of organic carbon in the karst region of Southwest China are still unclear. Based on a 25-year long-term located experiment on yellow soil, soil samples from the 0–20 cm soil layer were collected and treated with different fertilizers (CK: unfertilized control; NPK: chemical fertilizer; 1/4 M + 3/4 NP: 25% chemical fertilizer replaced by 25% organic fertilizer; 1/2 M + 1/2 NP: 50% chemical fertilizer replaced by organic fertilizer; and M: organic fertilizer). In water-stable aggregates, soil aggregates stability, total organic carbon (TOC), easily oxidized organic carbon (EOC), carbon preservation capacity (CPC), and carbon pool management index (CPMI) were analyzed. The findings demonstrated that the order of the average weight diameter (MWD), geometric mean diameter (GWD), and macro-aggregate content (R0.25) of stable water aggregates was M > CK > 1/2M +1/2NP > 1/4M +3/4NP> NPK. The MWD, GWD, and R0.25 of NPK treatment significantly decreased by 32.6%, 43.2%, and 7.0 percentage points, respectively, compared to CK treatment. The order of TOC and EOC content in aggregates of different particle sizes was M > 1/2M +1/2NP > 1/4M +3/4NP> CK > NPK, and it increased as the rate of organic fertilizer increased. In macro-aggregates and bulk soil, the CPC of TOC (TOPC) and EOC (EOPC), as well as CPMI, were arranged as M > 1/2M +1/2NP > 1/4M +3/4NP> CK > NPK, but the opposite was true for micro-aggregates. In bulk soil treated with organic fertilizer, the TOPC, EOPC, and CPMI significantly increased by 27.4%–53.8%, 29.7%–78.1%, 29.7–82.2 percentage points, respectively, compared to NPK treatment. Redundancy analysis and stepwise regression analysis show that TOC was the main physical and chemical factor affecting the aggregates stability, and the TOPC in micro-aggregates has the most direct impact. In conclusion, the primary cause of the decrease in SOC caused by the long-term application of chemical fertilizer was the loss of organic carbon in macro-aggregates. An essential method to increase soil nutrient supply and improve yellow soil productivity was to apply an organic fertilizer to increase aggregates stability, storage and activity of SOC in macro-aggregates

The role of Tyro 3 subfamily receptors in the regulation of hemostasis and megakaryocytopoiesis

Background and Objectives The molecular mechanisms regulating megakaryocytopoiesis and hemostasis remain largely unknown. The Tyro 3 subfamily of receptor tyrosine kinases (RTK), which is composed of three members (Tyro 3, Axl and Mer), plays important roles in various tissues, such as those in the nervous, immune and reproductive systems. Here, we investigate the roles of the Tyro 3 RTK subfamily in regulating megakaryocytopoiesis and hemostasis.Design and Methods Single, double, and triple knock-out mice for the three Tyro 3 RTK were used in the study. Bleeding time, platelet count, megakaryocyte count, megakaryocyte ploidy, rate of proplatelet formation, platelet aggregation and ATP release were used as criteria to evaluate hemostasis, megakaryocytopoiesis and platelet function.Results Mice lacking all three receptors had impaired hemostasis and mild thrombocytopenia, which may be due to platelet dysfunction and defective megakaryocytopoiesis. Mice lacking different combinations of two receptors of the Tyro 3 RTK subfamily had normal platelet counts in peripheral blood, but exhibited impaired hemostasis and platelet function. Although knock-out mice for any single receptor had normal hemostasis and megakaryocytopoiesis, they exhibited a mild platelet dysfunction.Interpretation and Conclusions The Tyro 3 RTK subfamily plays important roles in regulating hemostasis, megakaryocytopoiesis and platelet function

Spatial inequality of housing value changes since the financial crisis

The financial crisis has dramatically reshaped the map of inequality; in particular, wealth has been redistributed because of fluctuations in the prices of equities and housing. However, since the explanation of this issue has by default been seen as economists' responsibility, the spatial dimension of the financial crisis still remains unexplored, especially at the intra-urban level. This study examines the local geographies of the housing value bust (2008-2012) and boom (2012-2016) since the financial crisis, with an explicit emphasis on their impacts on urban inequality in Salt Lake County, Utah. We find that housing value changes differ across space and appear strongly associated with the spatial distribution of neighborhood conditions and urban amenities. Additional regressions confirm that a city's housing market volatility is amplified by uneven distribution of physical and service amenities and residential segregation. Moreover, the significance level of local attributes changes over the bust-boom cycle of the housing market. The comparison between bust and boom models suggests that the value of houses enjoying shade from trees and proximity to jobs, places of worship, and good public schools are more resilient, experiencing less value drop in an economic bust, but also less increase in a boom. Other amenities such as public transport, hospitals, parks, and restaurants could be interpreted as types of discretionary consumption, which positively contribute to housing value volatility. Neighborhood conditions, especially white-Hispanic segregation, significantly contribute to housing value fluctuation. Hispanic communities in Salt Lake County tend to experience more loss of property value in a bust and gain more in a boom. Thus, our study suggests that a more balanced urban distribution of employment, races, and amenities would significantly enhance local economic stability by smoothing fluctuations of business cycles at the local level

Spatial inequality of job accessibility in Shanghai: A geographical skills mismatch perspective

This study explores the spatial inequality of job accessibility in urban China, focusing on geographical skills mismatch in Shanghai. Our results suggest that geographical skills mismatch should be a critical concern in measuring job accessibility because the urban villages create residential sites for low-skill workers in central Shanghai. Based on the job accessibility index considering geographical skills mismatch, the floating population has high job accessibility in the periphery of the central urban area because there are affordable housing prices. The spatial distribution of the registered population's job accessibility still follows the core-periphery pattern. The spatial mismatch between the job centers for floating and registered populations might enlarge the segregation between them. The path analysis reveals that the housing/rent market, urban structure, and education attainment collectively shape job accessibility through residential segregation. Furthermore, path analysis manifests that high-skill people, mainly living in the central urban area, have significantly higher job accessibility. The polycentric development fails to create self-contained job centers for low-skill people. Future policies should pay attention to connecting the low-skill workers and their job markets through public rental housing or improving the public transit system

Modelling urban expansion in the transitional Greater Mekong Region

Urban expansion in emerging urban areas has drawn plenty of attention. The Greater Mekong Region (GMR) has experienced dramatic urbanisation and urban land expansion in recent decades. Based on built-up area data from the World Bank compiled over the 2000–2010 period, this paper integrates geographical, socioeconomic and physical factors to explore the underlying patterns and dynamics of urban land expansion in the GMR. An explicit and critical emphasis is placed on institutional conditions. The growth of built-up areas in the GMR has concentrated heavily in the capital cities and coastal areas. Additionally, the transitional countries have shown more dramatic expansion. The results of multi-level models suggest that urban developments in the GMR are not only sensitive to local contexts, such as distance to coastlines, accessibility factors and population growth rates, but are also closely associated with country-level factors, such as country political systems, and patterns of economic growth and foreign investment. We also find that the demographic measures of urbanisation have more influence in Thailand, while measures of economic growth have more marked impacts in the transitional countries

Firm Suburbanization in the Context of Urban Sprawl: Neighborhood Effect and Sectoral Difference

This study explores spatial patterns and mechanisms of industrial growth in Salt Lake County, Utah, which vary with sectoral divisions and scales in the context of urban sprawl. We find that besides the center growth, producer services prefer newly developed areas, and manufacturing has a suburbanizing growth pattern. The spatial regressions indicate neighborhood effects among mechanisms: At the block group level, producer services are more sensitive to community characteristics than manufacturing. At the neighborhood level, whereas producer services are still profoundly affected by community characteristics such as population density and higher education rates, manufacturing only responds to agglomeration effects. The model sets further uncover the variety of mechanisms among industry sectors. These results illustrate different location preferences of industry sectors and challenge the traditional view regarding producer services as an entire group. Highlighting the preference of firms to newly developed areas, our research discloses the growth pattern in Salt Lake County and illuminates the effects of sprawl development, such as low population density and car-based development, in the firm suburbanization process. It also reveals that growth patterns and mechanisms might vary with industry sectors and due to neighborhood effects. Thus, these effects should be carefully considered in research and policies

Urban land expansion and regional inequality in transitional China

Rising inequality and spatial concentration in China have drawn considerable scholarly interest and social concern. However, sources of spatial inequality in China remain under-studied. This article analyzes spatial patterns and dynamics of urban land expansion in China to better understand the role of institutions and urbanization in spatial inequality. We find that urban land expansion in China is highly uneven at both intra-provincial and intra-prefectural levels, and inequalities are much higher in the Western region than the Eastern region. We also find that provincial-level development policies tend to increase urban land expansion and economic development gaps across prefectures, while urban land expansion tends to converge within prefectures. Such core-periphery growth patterns have intensified economic gaps across prefectures and provinces in China. (C) 2017 Elsevier B.V. All rights reserved

Institutions, Extreme Weather, and Urbanization in the Greater Mekong Region

Climate change threatens many developing countries with more frequent and intense extreme weather events. Researchers, however, have not comprehensively examined how extreme weather influences urbanization and sustainable development. Based on the spatial estimates of precipitation, tropical cyclones, and temperature for the period of 2000 to 2010, we establish an eleven-year climatological record and calculate anomalies at the county and district level in the Greater Mekong Region (GMR). Combining this with urbanization data from the World Bank, we relate weather patterns to growth rates in urban population and urban land use and find that the above-average rainfall in the wet season along with more frequent cold waves and tropical cyclones tend to retard urban development. In contrast, crop failures caused by increasingly severe droughts during the dry season and heat waves accelerate rural-urban migration and the agglomeration of urban poverty. By identifying institutionally varying effects, we further find that nonsocialist countries have additional sensitivity to most weather extremes than more centralized socialist countries, which have stronger ability to mobilize resources for disaster management and relief. Our study contributes to the understanding of effects of weather shocks on socioeconomic outcomes in societies rapidly integrating with the global economy

Urban amenity, human capital and employment distribution in Shanghai

Human capital theory argues that by attracting skilled workers urban amenities are increasingly important to the location decisions of firms and to employment agglomeration. However, this hypothesis has been questioned with respect to the direction of causality at the interurban level, the existence of endogeneity, and confusion between revealed and actual preferences of consumers. In this research, to contribute the existing debate over the relationship between amenities and jobs, we develop a new measurement of private service amenities based on the comments about facilities from Dianping.com, and further relate it to labor markets in Shanghai at the intra-urban level. We find that human capital theory and the distribution of amenities can partially explain the employment agglomeration in Shanghai, and their applicability is also influenced by types of amenities and sectors. Private service amenities, such as entertainment, shopping, for-profit healthcare facilities, and restaurants, are largely associated with the employment agglomeration of producer services at the subdistrict-level, which supports human capital theory, while the agglomeration of manufacturing employment is more likely associated with the development of public facilities such as transportation systems. Our study provides an innovative way to examine urban theories in the context of the social data revolution. It also suggests that the Chinese government has to encourage the decentralization of service amenities to overcome the increasing centrality of producer services and the accelerating marginality of manufacturing employment