Rural labor migration and farmers’arrangements of rice production systems in Central China:Insight from the intergenerational division of labor

Rice production is crucial for food security in China,and its relationship with rural labor migration has been studied extensively.Labor migration in rural China has taken new forms in recent years.There has been a discernible trend wherein adult children have started migrating to cities while their elderly parents return to villages to re-engage in on-farm work.The phenomenon has notably shaped the intergenerational division of labor(IDL)within households.However,it remains to be seen how farmers adjust their rice production systems in response to the IDL.The age of 60 years for employment injury insurance is the eligibility threshold for off-farm employment and is used to obtain a source of exogenous variation in the IDL.Based on a representative household survey of 1,752 rice farmers in the Hubei Province of Central China,our fuzzy regression discontinuity analysis reveals that farmers in IDL households are more likely to adopt ratoon rice(RR)than single cropping rice(SR)or double cropping rice(DR).The effect of the IDL varies under different levels of operational scales and specialized agricultural service availability.Further analysis suggests that farmers’arrangements are associated with two potential mechanisms of downward intergenerational transfer.Monetary transfer for urban housing purchases increases RR in IDL households,and time transfer for intergenerational childcare significantly promotes SR in IDL households.This study enhances the understanding of the relationship between rural labor migration and rice production in China,providing a reference for adjusting rice production systems to ensure food security.

A blockchain bee colony double inhibition labor division algorithm for spatio-temporal coupling task with application to UAV swarm task allocation

It is difficult for the double suppression division algorithm of bee colony to solve the spatio-temporal coupling or have higher dimensional attributes and undertake sudden tasks.Using the idea of clustering,after clustering tasks according to spatio-temporal attributes,the clustered groups are linked into task sub-chains according to similarity.Then,based on the correlation between clusters,the child chains are connected to form a task chain.Therefore,the limitation is solved that the task chain in the bee colony algorithm can only be connected according to one dimension.When a sudden task occurs,a method of inserting a small number of tasks into the original task chain and a task chain reconstruction method are designed according to the relative relationship between the number of sudden tasks and the number of remaining tasks.Through the above improvements,the algorithm can be used to process tasks with spatio-temporal coupling and burst tasks.In order to reflect the efficiency and applicability of the algorithm,a task allocation model for the unmanned aerial vehicle(UAV)group is constructed,and a one-to-one correspondence between the improved bee colony double suppression division algorithm and each attribute in the UAV group is proposed.Task assignment has been constructed.The study uses the self-adjusting characteristics of the bee colony to achieve task allocation.Simulation verification and algorithm comparison show that the algorithm has stronger planning advantages and algorithm performance.

Re-measuring Status of China＇s High-Tech Industries in International Division of Labor： Applying a Non-Competitive Input-Output Model

Based on a refined ＂non-competitive input-output model,＂ this paper proposes a new framework for analyzing the status of a country＇s high-tech industries in the international division of labor, i.e. calculates the index of＂ weighted value-added productivity ＂ by compiling non-competitive input-output tables which distinguish high-tech industries from traditional industries. The new method effectively avoids ＂statistical illusion＂ which stems from a biased focus on gross exports under intra-product specialization. The empirical study shows that since 1995, the status of China＇s high-tech industries has grown quickly as a result of enhanced labor productivity, but still lags behind those of major developed countries. In addition, the study also suggests that the status of China＇s high-tech industries has been over-estimated using the traditional gross export statistical method.

Differing Effects of Intra-Product International Division of Labor on Technological Progress:Comparing Proactive Participation with Passive Inclusion

This paper has identified two models of intra-product international division of labor:the model of passive inclusion and the model of proactive participation.Their difference is essentially whether participation in international division of labor is dominated by multinational firms or by local firms.At the level of representative sectors,some characteristic variables of participation in international division of labor demonstrate significant industry differences.Models of division of labor affect technology progress.According to the empirical analysis result at the micro-level of four sectors,no matter for export or the contribution of learning by doing to corporate technology progress,the model of proactive participation is superior to the model of passive inclusion;under the model of passive inclusion,the technology spillover effect of import is smaller than "learning by doing " effect;under the model of proactive participation,technology spillover effect is over two times the "learning by doing" effect.

Division of labor, perceived labor-related stress and well-being among European couples

Background: The objective of this study was to analyze how involvement in paid and unpaid work and perceived labor-related stress are related to the well-being of married or cohabiting men and women in Europe. Methods: Data from the European Social Survey round two has been used. The sample consists of 5800 women and 6952 men, aged between 18-65 years. Exposure variables were divided into labor involvement, time spent on paid and unpaid work, and labor-related stress. Multiple logistic regressions with 95 % confidence interval were used. Results: Women spent more hours on housework than men did, but fewer hours on paid work. Women tended to perceive higher degrees of housework-related stress than men did. Furthermore, women who experienced houseworkrelated stress tended to have higher odds of reporting a low level of perceived well-being than men, while men had higher odds of reporting a low level of perceived well-being when they experienced work/family conflicts. Conclusion: For both men and women, the perceptions of labor involvement are of more importance for the well-being than the actual time spent on paid and unpaid work. This implies that, when studying the relationship between labor involvement and well-being, perceived stress should be considered.

The New Rural Cooperative Medical Scheme and Its Implications on Rural Labor Migration in China：Evidence from Longitudinal Surveys

In 2003, China initiated the New Rural Cooperative Medical Scheme （NRCMS） in order to provide basic health care coverage for the rural population. However, the NRCMS has had a marked impact on rural-urban labor migration as its current regulations present a barrier for cross-region participation in the NRCMS, and its reimbursement system is biased when the enrollees seek medical services outside their location of hukou, a household registration system in China. This paper performs a variety of empirical tests on a panel data set from the China Health and Nutrition Survey （CHNS） to study how the NRCMS affects rural residents＇ work location choices. We observed a ＂locking effect＂ on potential rural migrant workers and a ＂pulling effect＂ on existing ones. According to the results, the NRCMS has discouraged rural residents from working outside their location of hukou, lowering the probability of relocation by 3.52 percent. Meanwhile, the NRCMS system actually encourages existing migrant workers to return home. This paper concludes that the NRCMS has to some extent restrained the free flow of the labor force and exacerbated the migrant worker shortage.

Joint subcarrier and power allocation with threshold in cooperative multiuser networks

In this paper, we investigate a resource allocation issue in OFDMA-based decode-and-forward cooperative multiuser networks and propose joint subcarrier and power allocation schemes. The optimal solution of this combinable allocation shows high computational complexity, so we allocate subcarriers and power separately. At firstly, we distribute subcarriers to relays and users under the assumption of equal power distribution. Here, we propose an equal capacity increment （ECI） allocation strategy to achieve tradeoff between total throughput and fairness. To further improve the system performance, we introduce threshold into ECI strategy, named ECI strategy with threshold （ECI-T）, where subcarriers with bad performance are prevented from transmitting. Subsequently, a water-filling method is adopted to distribute the power to cooperative links in order to fully utilize the limited power. Simulation results show that system performance of the proposed schemes is significantly enhanced compared with an existing resource allocation scheme. Besides, the resource allocation schemes with the water- filling method notably outperform schemes with equal power allocation.

Cooperative communications with hierarchical modulation in downlink OFDMA based cellular networks

Cooperative transmission is a promising way to improve system performance in orthogonal frequency division multiple access (OFDMA) based cellular networks.This paper proposes two heuristic cooperation schemes including relay selection and resource allocation using hierarchical modulation (HM) to fully exploit the radio resources in cellular networks where user equipments (UEs) relay for each other.The relay selection procedure considers both the channel conditions and the energies left in relays to make the cooperative communications behave better.To mitigate the spectrum efficiency loss due to the half-duplex mode,the bits of relayaided UE and its relay (which is also a UE) are transmitted simultaneously in one sub-channel using HM to improve the utilization efficiency of sub-channels.Besides,time resources are used effectively with the adaptively changed proportion of the two sub-frames divided for relay transmission.Simulation results show that the proposed schemes can improve the spectrum efficiency compared with the traditional schemes.

INTERFERENCE MITIGATION FOR ASYNCHRONOUS COOPERATIVE STBC-OFDM SYSTEMS

This paper addresses the problem of interference mitigation in cooperative Space Time Block Coded Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems in the presence of asyn-chronism. This scheme first preprocesses the received ST codewords to convert the equivalent fading matrix into a suboptimal ordering upper triangular form based on low complexity permutation QR decomposition, and then suppresses the InterCarrier Interference (ICI) and InterSymbol Interference (ISI) by exploiting Successive Interference Cancellation (SIC) technique. Simulation results show that the performance of the proposed algorithm slightly outmatches or asymptotically approaches to that of the existing Minimum Mean Square Error (MMSE) detector depending on the magnitude of the Carrier Frequency Offsets (CFOs) but with less complexity.

Two-Codebook-Based Cooperative Precoding for TDD-CoMP in 5G Ultra-Dense Networks

In ultra-dense networks （UDN）, the local precoding scheme for time-division duplex coordinated multiple point transmission （TDD-CoMP） can have a good performance with no feedback by using reciprocity between uplink and dovallink. However, if channel is time-varying, the channel difference would cause codeword mismatch between transmitter and receiver, which leads to performance degradation. In this paper, a linear interpolation method is proposed for TDD-CoMP system to estimate the uplink channel at the receiver, which would reduce the channel difference caused by time delay and decrease the probability of codeword mismatch between both sides. Moreover, to mitigate severe inter-cell interference and increase the coverage and throughput of celledge users in UDN, a two-codebook scheme is used to strengthen cooperation between base stations （BSs）, which can outperform the global precoding scheme with less overhead. Simulations show that the proposed scheme can significantly improve the link performance compared to the global precoding scheme.

THE THEORETICAL BER PERFORMANCE ANALYSIS OF A COOPERATIVE DIVERSITY SCHEME IN FREQUENCY SELECTIVE FADING CHANNEL

A novel cooperative diversity scheme based on Distributed Space-Time Block Coding and Multi-Carrier Code Division Multiple Access (DSTBC-MC-CDMA) is proposed which works well in frequency selective fading channels with multiple single-antenna users. And an analytical error model is established to describe the symbol decoding errors between interusers, based on which a close form expression for theoretical Bit Error Rate (BER) performance of the scheme is derived to analyze the influence of the interuser decoding errors on the BER performance of the scheme. Then simulation is complimented to verify the analytic result above, which also shows that the BER performance of DSTBC-MC-CDMA outgoes that of non-cooperative MC-CDMA with considerable gains. Further- more, the simulations coincide with the theoretical results well.

全球价值链数字化对中国制造业企业国际分工地位的影响

数字技术发展使全球价值链分工体系向数字化重构并深刻影响中国制造业高质量发展。本文基于K-T数理模型分析开放经济条件下数字中间品投入、出口国内增加值与国际分工地位的相互关系,构建全球价值链数字化与企业国际分工地位的理论分析机制。研究发现:全球价值链数字化通过全要素生产率、贸易成本、产品质量和创新能力这4个渠道提升中国制造业企业国际分工地位;全球价值链数字化对资本密集型企业、一般贸易企业及非国有企业的国际分工地位提升效应较强;全球价值链数字化对知识产权保护较好且研发投入较多地区的企业国际分工地位提升效应较显著。因此,建议从加大国内数字技术研发力度、采用差异化战略引导及加强数字技术知识产权保护等方面激发企业参与全球价值链数字化分工活力,提升企业国际竞争力,促进中国制造业高质量发展。

Changes of Labor Education in the Past 70 Years Since the Founding of the People’s Republic of China

Throughout the development of labor education in the past 70 years since the founding of the People’s Republic of China,its development characteristics are different along with the varying stages of economic development.The development of labor education has an important relationship with the political system,economic policy,and cultural foundation.This article reviews the development process of labor education in the past 70 years since the founding of the People’s Republic of China,analyzes the characteristics of labor education in each period,and proposes suggestions to promote the development of labor education in China,whereby the development of labor education should follow the basic rules of education development,grasp the characteristics of the times of labor education,and build a new system of labor education;adhere to people-oriented education and establish proper educational orientation;innovate the labor education system and build a labor education model with Chinese characteristics;improve the support and guarantee system of labor education and earnestly promote the implementation of labor education;enhance the internationalization of labor education and the international competitiveness of labor education.

数字技术与内需主导型全球价值链分工:理论逻辑与经验证据

数字技术正在加速重塑全球价值链(GVC),以此为契机推动GVC分工向内需主导型转变,是畅通双循环、促进经济行稳致远的重要保障。本文通过辨析增加值来源识别数字技术渗透水平,研究了数字技术对内需主导型GVC分工的影响。研究发现:第一,数字技术可有效深化内需主导型GVC分工,其作用机制在于激发国内需求、强化核心环节优势与降低贸易成本。第二,相对而言,数字技术对内需主导型GVC分工的深化作用在国际分工参与水平高的行业、技术密集型行业、资本密集型行业以及发达国家和地区中更大。第三,与外需主导型GVC分工相比,数字技术对内需主导型GVC分工的深化作用更大。以上结论对中国凭借数字技术优化国际分工模式、加快构建双循环新发展格局有重要启示。

非编码RNA调控真社会性昆虫品级分化和个体分工的研究进展

真社会性昆虫是最具代表性的表型可塑性的研究对象之一,其个体之间分工协作的社会性生活方式增强了整个群体的环境适应性和繁殖力。真社会性昆虫虽然具有相同的遗传背景,个体之间却表现出明显的品级分化和个体分工,这是由环境和遗传共同影响的。表观遗传被认为是应对环境条件下重塑基因表达的主要机制,非编码RNA作为一类广泛参与机体生命活动的不编码蛋白的功能性RNA,在真社会性昆虫的品级分化、个体分工等方面起着重要的调控作用。本文从微小RNA、长链非编码RNA、环状RNA、与PIWI蛋白相作用的RNA等非编码RNA,对蜜蜂、蚂蚁及白蚁等真社会性昆虫的非编码RNA调控机制研究进展进行了综述,以加深对真社会性昆虫内在遗传分子基础的理解和认识,也为害虫防治领域提供新的研发视角。

数字经济与全国统一大市场建设:基于城市层面的研究

双循环发展格局下,全国统一大市场建设有助于促进新质生产力形成及经济高质量转型发展。而数字经济的蓬勃发展为全国统一大市场建设提供了新路径。本文使用2005—2021年中国城市层面数据测算了全国统一大市场指数,实证检验了数字经济如何助推全国统一大市场建设。结果表明,数字经济通过提高流通效率、深化专业化分工以及强化城市网络效应助推全国统一大市场形成;同时“宽带中国”战略实施促进了统一大市场整合;数字经济的市场整合效应在不同地理区位、经济发展水平、城市规模、数字化水平以及市场一体化程度的城市间存在显著差异;进一步分析发现,数字经济对全国统一大市场形成存在长期效应和边际效应递增趋势以及空间溢出效应。

家校合作:新时代破解农村学校劳动教育困境的着力点

随着乡村社会的变迁和生产方式的变革,农村学校劳动教育在现实发展中面临着目标外化、地位弱化、模式僵化、空间窄化的困境。家庭是劳动教育的基础,对于学校劳动教育发挥着重要的支持、配合作用。家庭劳动教育的缺位是农村学校劳动教育困境形成的基础性因素。破解新时代农村学校劳动教育的困境,需要从家校达成理念共识、充分挖掘家庭资源、创新家校合作模式以及构建多元考评机制等多方面着手,积极构建劳动教育的家校合作机制,切实发挥家庭在劳动教育中的基础作用。

制造业数字化与劳动收入份额变动

制造业数字化转型能够改变劳动力市场格局,对收入分配产生重要影响。以1995—2018年45个国家17个制造业部门为样本,考察制造业数字化对劳动收入份额的影响。研究发现:制造业数字化对劳动收入份额的影响呈现“倒U型”特征,这种特征在发达国家中比较突出,在发展中国家中不明显;相比于国外投入,国内投入数字化对劳动收入份额的“倒U型”影响较早达到拐点;制造业数字化与直接出口、间接出口以及再进口活动的劳动收入份额分别呈抑制、促进和“倒U型”关系。机制检验显示,制造业数字化主要通过工资率效应和价值链分工效应对劳动收入份额产生“倒U型”影响。进一步分析发现,制造业数字化能够缩小高-低技能和中-高技能劳动者的工资差距。拓展性分析表明,资本-劳动比和行业竞争程度的提高均使劳动收入份额由升转降的拐点提前。研究可为推动制造业数字化转型与完善收入分配制度提供重要启示。

农村社会养老保险对农户多维相对贫困的影响研究

农村社会养老保险对于提升家庭内生发展能力,缓解农户多维相对贫困具有重要意义。基于可行能力理论构建多维相对贫困指数,利用2014—2018年三期中国家庭追踪调查数据库,探究农村社会养老保险对农户多维相对贫困的政策效果及作用机制。结果表明,农村社会养老保险能够通过促进老年人操持家务、隔代照顾和促进青年劳动力外出就业缓解家庭多维相对贫困状况。按照农村社会养老保险的边际效果特征,农户群体可被划分为有效型、抑制型与无效型三种,且在样本期间内抑制型农户减少,无效型农户增多。另外,农村社会养老保险仅对于多维相对贫困程度较高的农户有显著的作用效果,且农村社会养老保险能够阻断返贫以及抑制长期性贫困。因此,为有效缓解农户多维贫困,应推动农村产业发展并加强对农村劳动力的技能培训,完善农村社会养老保险制度的运作模式和提升养老金待遇水平,以及构建多元化农村社会保障制度。

嵌入与重构:全球价值链分工的演进逻辑

全球价值链(GVC)是国际分工合作进一步深化的结果,其源于发达国家产业结构调整和发展中国家经济发展战略转变的相互契合。随着内在动力和外部约束条件的变化,参与GVC分工合作的各经济主体随即开始调整经济行为,其结果表现为GVC的解构和重构。本文从多个视角对GVC重构进行分析,有助于更全面地认识GVC分工演进的内在逻辑。研究发现:(1)GVC分工成为国际分工的标志性特征之一,已成为世界经济发展的支柱和中枢神经系统,三大区域价值链逐渐形成并稳固;(2)超大规模市场提升了中国对GVC的影响,且技术进步推动中国逐渐向GVC中高端环节攀升;(3)GVC重构源于技术进步、经济特征以及政治环境三方面的动因;(4)GVC重构本土化、区域化和多元化三大趋势会对中国各方面产生现实挑战。