Search Results (5)

Based on the practical requirements of China’s urban–rural integrated development, it is of great theoretical and practical significance to analyze the impact of agricultural labor migration on the urban–rural dual economic structure. This paper empirically examined the impact of agricultural labor migration on the urban–rural dual economic structure by using the spatial Durbin model and the geographically and temporally weighted regression model on the basis of the panel data of 14 regions in Liaoning Province from 2005 to 2020. The results show that agricultural labor migration has an obvious optimization effect and spatial spillover effect on the urban–rural dual economic structure; in terms of space, agricultural labor migration has a stronger impact on the central and western regions and a weaker impact on the southeastern regions; in terms of time, agricultural labor migration can stably promote the integration of urban and rural economies before the second Lewis turning point. Therefore, this paper provides references with regard to increasing investment in rural education and training; improving the structure of government spending; and protecting the rights and interests of rural migrants. Full article

The health shocks caused by air pollution seriously interfere with people’s economic life. Based on the air pollution index and health shock index calculated by the principal component entropy weight method, this article analyzes the impact of air pollution on labor mobility, and adopts the mediation effect model to test the mediation effect of health shocks, using the threshold model to analyze the time and the health shocks threshold effect of air pollution on labor mobility. Its conclusions are as follows: (1) Air pollution has a negative impact on the net inflow of labor mobility, and the net inflow of labor mobility decreases between 24.9% and 44.7% on average for each unit increase in the health shocks of air pollution. (2) The impact of air pollution on labor mobility is all caused by health shocks; the health shocks are also an important factor influencing the decrease in the labor mobility supply across provinces, and the different health levels of the migrating individuals due to air pollution. (3) The health shocks of air pollution have a single-time threshold effect on labor mobility, and the health shocks of air pollution in China have intensified after 2010, confirming that China’s Lewis turning point was 2010. (4) The attraction effect of stable and higher regional real income will partially offset the repulsion effect of health shocks of air pollution on labor mobility, when the health-shocks index of air pollution exceeds the threshold value of 1.9873. Finally, the policy implications of the health shocks of air pollution on labor mobility are also formulated. Full article

Recently, a derivative-free optimization algorithm was proposed that utilizes a minimum Frobenius norm (MFN) Hessian update for estimating the second derivative information, which in turn is used for accelerating the search. The proposed update formula relies only on computed function values and is a closed-form expression for a special case of a more general approach first published by Powell. This paper analyzes the convergence of the proposed update formula under the assumption that the points from ${\mathbb{R}}^n$ where the function value is known are random. The analysis assumes that the $N+2$ points used by the update formula are obtained by adding $N+1$ vectors to a central point. The vectors are obtained by transforming a prototype set of $N+1$ vectors with a random orthogonal matrix from the Haar measure. The prototype set must positively span a $N\le n$ dimensional subspace. Because the update is random by nature we can estimate a lower bound on the expected improvement of the approximate Hessian. This lower bound was derived for a special case of the proposed update by Leventhal and Lewis. We generalize their result and show that the amount of improvement greatly depends on N as well as the choice of the vectors in the prototype set. The obtained result is then used for analyzing the performance of the update based on various commonly used prototype sets. One of the results obtained by this analysis states that a regular n-simplex is a bad choice for a prototype set because it does not guarantee any improvement of the approximate Hessian. Full article

My essay considers the history of collecting the art of Haudenosaunee (Iroquois) artists in the twentieth century. For decades Native visual and material culture was viewed under the guise of ‘crafts.’ I look back to the work of Lewis Henry Morgan on Haudenosaunee material culture. His writings helped establish a specific notion of Haudenosaunee material culture within the scholarly field of anthropology in the nineteenth century. At that point two-dimensional arts did not play a substantial role in Haudenosaunee visual culture, even though both Tuscarora and Seneca artists had produced drawings and paintings then. I investigate the turn toward collecting two-dimensional Haudenosaunee representational art, where before there was only craft. I locate this turn at the beginning of Franklin Delano Roosevelt’s administration in the 1930s. It was at this point that Seneca anthropologist Arthur C. Parker recruited Native crafts people and painters working in two-dimensional art forms to participate in a Works Progress Administration-sponsored project known as the Seneca Arts Program. Thereafter, museum collectors began purchasing and displaying paintings by the artists: Jesse Cornplanter, Sanford Plummer, and Ernest Smith. I argue that their representation in museum collections opened the door for the contemporary Haudenosaunee to follow. Full article

We report novel insights into the cascade rearrangement of destabilized vinyl cations deriving from the BF₃·Et₂O-induced decomposition of cyclic α-diazo-β-hydroxy ketones in turn prepared by aldol-type condensation of cycloalkanones with diazoacetone. Complexation of the hydroxy group of the α-diazo-β-hydroxy compound with the Lewis acid is the first event, followed by the generation of the cycloalkanylidenediazonium salt that, after nitrogen loss, produces the highly reactive vinyl cation. The subsequent ring expansion results in the formation of a cycloalkenyl vinyl cation that affords the allylic cation by 1,2-methylene shift and ring contraction. The cation can then trap the solvent, the fluoride or the hydroxide released from the [BF₃OH]⁻ to afford different reaction products. The effect of both solvent and substrate ring size on products types and ratios were analyzed and discussed from a mechanistic point of view. Full article