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It is foreseeable that the 100 Gb/s/λ and beyond passive optical network (PON) will be required in future optical access networks to meet the explosive growth of data traffic. The coherent optical systems could be a promising solution for the future beyond 100G PON. Coherent PON using digital subcarrier multiplexing (DSCM) can provide flexible bandwidth allocation to a large number of access subscribers by dividing subcarriers of the DSCM signal into time slots for time-and-frequency division multiple access. When the optical network unit is allocated a new subcarrier, digital signal processing (DSP) should converge fast in the allocated time slot to ensure a low handoff latency for real-time bandwidth allocation. However, the traditional coherent DSP is hard to realize fast convergence due to blind and complex algorithms. In this paper, we design a specific training sequence (TS) structure and propose data-aided DSP to achieve fast convergence for coherent PON. The feasibility of the proposed scheme is experimentally verified in an 8 Gbaud/SC×8 SCs 400 Gb/s-net-rate coherent PON using DSCM with 16 quadrature amplitude modulation. The experimental results show that fast convergence is jointly realized by the proposed TS structure and data-aided DSP using a 416-symbol TS with a 52 ns duration. The receiver sensitivity at the 20% soft-decision forward error correction limit is approximately −27 dBm and an optical power budget of about 35.5 dB is achieved with a booster amplifier.

Recently, flexible stretchable sensors have been gaining attention for their excellent adaptability for electronic skin applications. However, the preparation of stretchable strain sensors that achieve dual-mode sensing while still retaining ultra-low detection limit of strain, high sensitivity, and low cost is a pressing task. Herein, a high-performance dual-mode stretchable strain sensor (DMSSS) based on biomimetic scorpion foot slit microstructures and multi-walled carbon nanotubes (MWCNTs)/graphene (GR)/silicone rubber (SR)/Fe

Optical access networks have been evolving to meet the explosive growth of data traffic. It is foreseeable that the 100Gb/s/λ and beyond passive optical network (PON) will be required in future optical access networks. Coherent optical communication is a promising solution for the future beyond 100G PON. However, the traditional digital signal processing (DSP) for coherent optical communication is difficult to realize fast convergence due to blind and complex algorithms. In this paper, we design a specific preamble structure and propose a burst-mode DSP to achieve fast convergence for the coherent PON. For verifying the feasibility of the proposed scheme, point-to-multi-point (P2MP) coherent PON is experimentally built up based on digital subcarrier multiplexing (DSCM), which is a kind of frequency division multiple access. When the allocated frequency of the optical network unit is suddenly changed, the DSP should converge fast to ensure a low handoff latency. In P2MP coherent PON, the proposed specific preamble structure and burst-mode DSP jointly implement the fast convergence using a short preamble with only 416 symbols. The experimental results show that the 8-Gbaud/SC×8-SCs 400Gb/s-net-rate coherent PON in burst-mode detection achieves the receiver sensitivity of approximately −27dBm at the 20% soft-decision forward error correction limit and approximately 35.5dB optical power budget with an optical pre-amplifier.

Contactless palmprint recognition has recently made significant progress in palm-scanning payment and social security. However, most existing methods are based on handcrafted kernels and are sensitive to illumination and scale variations. To address this problem, a competitive convolutional neural network (CompNet) with constrained learnable Gabor filters is proposed for contactless palmprint recognition. The proposed CompNet is built on multisize competitive blocks, which are applied to effectively exploit the rich direction ordering information of the palmprint patterns by means of the ad-hoc softmax and channel-wise convolution operations. Compared to the current deep neural networks, the backbone of the proposed network contains only very few parameters, making it quite easy to train, especially on small-scale datasets. Experimental results obtained on four popular contactless palmprint datasets demonstrate that the proposed CompNet achieves the lowest equal error rate compared to the most commonly used methods.

We examine the multigenerational impacts of a nationwide social pension program in China, the New Rural Pension Scheme (NRPS). NRPS was rolled out in full scale since 2012, and rural enrollees over age 60 are eligible to receive a minimum of 70 CNY non-contributory monthly pension. We leverage age eligibility and variations in pension receipt to identify the inter-generational effect of NRPS on health among grandchildren. We find NRPS substantially increases child weight without impacting height. Overall, child BMI z score increases by 1.09, which is largely driven by grandfathers’ pension receipt raising rates of overweight and obesity among grandsons. Among the potential mechanisms, our findings are more plausibly explained by a mixture of income effect, son preference, and rising inter-generational co-residence and childcare.

Currently, many palmprint acquisition devices have been proposed, but how to design the systems are seldom studied, such as how to choose the imaging sensor, the lens, and the working distance. This chapter aims to find the relationship between image sharpness and recognition performance and then utilize this information to direct the system design. In this chapter, firstly, we introduce the development of recent palmprint acquisition systems and abstract their basic frameworks to propose the key problems needed to be solved when designing new systems. Secondly, the relationship between the palm distance in the field of view (FOV) and image pixels per inch (PPI) is studied based on the imaging model. Suggestions about how to select the imaging sensor and camera lens are provided. Thirdly, image blur and depth of focus (DOF) are taken into consideration; the recognition performances of the image layers in the Gaussian scale space are analyzed. Based on this, an image sharpness range is determined for optimal imaging. The experiment results are obtained using different algorithms on various touchless palmprint databases collected using different kinds of devices. They could be references for new system design.

This paper provides new evidence of how political regimes and social connections determine participation in pilot experiments. Using data from China’s national pilot experiments of New Rural Pension Scheme (NRPS), we show that county-level charac- teristics and political regime have explanation power in the early stage of county pilot decision. Local party secretaries connected to Central Committee (CC) members, a po- litical body that comprises the top leaders of the Communist Party, are discouraged to enroll. In contrast, counties that are send-down movement destinations of CC members during Cultural Revolution (1966-1976) are more likely to enroll. We also find counties with lower cost, higher benefits, and more government revenue are more likely to enroll. Local government leaders may face trade-off between economic performance and social welfare, and connected officials have more incentives to allocate resources in economic growth rather than social welfare. These findings are characterized by a theoretical model that describes how connections change local leaders’ allocation of government resources under a multitask problem

The Supplemental Nutrition Assistance Program (SNAP) is one of the largest welfare safety nets in the United States. The purpose of SNAP is to provide low-income eligible families with sufficient funds to reach the cost of a nutritious diet. To mitigate the effects of COVID-19, the maximum SNAP benefits were temporarily increased through September 2021 by a total of 20.3%. On October 1, 2021 the maximum SNAP benefits were permanently increased by 21% from the pre-pandemic levels. A sizeable literature had shown that the pre-pandemic maximum benefit levels were insufficient to reach the full cost of a nutritious diet because individuals spent an insufficient amount of time in food production. This viewpoint considers the question: Are those increases in the maximum SNAP benefits enough to reach the full cost of a nutritious diet when we account for possible changes in home food production labor? In light of the recent pandemic-induced labor market disruptions, this research assesses the needs for additional time inputs to the pre-pandemic food production time amounts given different levels of maximum SNAP benefit adjustments in order to reach the ‘full’ cost of a nutritious diet. We evaluate the feasibility of meeting those additional time needs in the context of reallocating portions of the ‘windfall’ of time normally devoted to working and commuting before the pandemic. Focusing on single headed households we find the temporary 20.3% and the permanent 21% increase both would have to be matched by an increase of about 9 hrs per week in food production in order to reach the full cost of a nutritious diet. This increase seems very unlikely based on historical time allocation patterns. More is needed to be done to increase SNAP benefit adequacy either through further increases to benefit levels and/or through education and outreach efforts designed to improve skills of home meal preparation and time management.

This paper provides new evidence of how political regimes and social connections determine participation in pilot experiments. Using data from China’s national pilot experiments of New Rural Pension Scheme (NRPS), we show that county-level characteristics and political regime have explanation power in the early stage of county pilot decision. Local party secretaries connected to Central Committee (CC) members, a political body that comprises the top leaders of the Communist Party, are discouraged to enroll. In contrast, counties that are send-down movement destinations of CC members during Cultural Revolution (1966–1976) are more likely to enroll. We also find that counties with lower cost, higher benefits, and more government revenue are more likely to enroll. Local government leaders may face trade-off between economic performance and social welfare, and connected officials have more incentives to allocate resources in economic growth rather than social welfare. These findings are characterized by a theoretical model that describes how connections change local leaders’ allocation of government resources under a multitask problem.

International audience; Supply shortages and competitive disadvantages are the main problems faced by China's hog sector. The non-essential import of pork products, triggered by competitive disadvantages, poses great challenges to hog farms. Structural changes are an important policy concern in China and elsewhere. Previous literature has ignored whether the ongoing structural changes from backyard to large farms can contribute to sustainable development. This study adopts the micro-level data of hog farms collected from Jiangsu Province, and uses a two-step metafrontier model and a primal system approach. The empirical results reveal that the ongoing structural changes are capable of boosting the growth in output in China's hog sector, since the stronger increase in comparable technical efficiency compensates for the inappropriate technology. Furthermore, the ongoing structural changes are also beneficial in the reduction of production costs and in improving competitiveness in China's hog sector. The decline in technical and allocative inefficiency costs, particularly for technical inefficiency costs, contributes to the cost advantage with the increasing farm size.

A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with