新型职业农民:成长轨迹、影响因素及培育策略——基于19个省市39位新型职业农民生命历程的分析

通过对全国19个省市39位优秀新型职业农民的生命历程进行分析,发现其成长轨迹呈现出折勾型、倒梯型、V字型、阶梯型以及N字型五种类型,并且不同来源、不同世代的新型职业农民成长轨迹具有一定的差异性。究其原因,新型职业农民终身发展的动力支撑显得不足;新型职业农民的个体主观能动性得到了充分的发挥;政府扶持与引领作用有待继续加强;新型职业农民培育时机并未得到恰当的把握;影响新型职业农民成长的相关利益主体分布比较广泛。针对以上情况,提出新型职业农民的培育策略:强化政府主导力量,增强新型职业农民职业吸引力;吸收年轻优秀群体,壮大新型职业农民的新生力量;重视人地实际需求,把握新型职业农民培育的时机。     

Navigating the migration industry: migrants moving through an African-European web of facilitation/control

ABSTRACT

This paper approaches the African-European migration industry as a complex web of relations in which different actors liaise, objectives oppose each other, and roles overlap. Starting from this notion, the question emerges: How do migrants navigate this fuzzy web of migration facilitation/control? To answer this question, this paper uses a ‘trajectory ethnography’ that follows the im/mobility processes of migrants from West – and Central Africa to, and inside, Europe. In so doing, it particularly focuses on two practices that are related to the concept of social navigation. First, it concerns débrouillardise, a term that points to the power of improvisation, creativity and hustling. Second, it regards social negotiation, a term referring to the process of how migrants ‘massage’ their relations with important actors in the field. The findings stress the relational dimension of the migration industry in the sense that the functioning of one actor depends so much on the intentions and efforts of others. I conclude that we could enhance our knowledge on migration industries with studies that constantly shift between the perspective of the migrant, the social network, the facilitator and controller. Such a dynamic approach unpacks further the multiple efforts that produce migrant im/mobility.     

Stories of Non‐Becoming: Non‐Issues,Non‐Events and Non‐Identities in Asexual Lives

In contrast to conventional models of positively “becoming” an identity through social interaction, this article explores the inverse, negational process of “non‐becoming,” whereby actors start but do not continue along an identity career trajectory. Through cumulative attrition, interactions and encounters at key moments create an overall pattern of non‐progression. Using asexuality as an example, we identify three main trajectory stages of non‐awareness, communicative negation and non‐consolidation, each involving interactional contingencies. With a wider applicability to other repudiated identities, this model shows how even negational symbolic social objects (non‐issues, non‐events, and non‐identities) are constituted through social interaction.     

The reproductive health indices and sex hormone levels in middle-aged and elderly Chinese men

Objective: The aim of this study was to analyze the age-related recession trajectory of reproductive health indices in middle-aged and elderly Chinese men.

Methods: A population-based cross-sectional study was conducted in Jiashan County, Zhejiang in 2012. Healthy men between 40 and 80 years of age were considered eligible for the study. Physical examination and the sex hormones were measured. The subjects were assessed based on the 5-item version of the International Index of Erectile Function (IIEF-5) for Erectile Dysfunction (ED), and Aging Males’ Symptoms (AMS) scale for Symptomatic Late-Onset Hypogonadism (SLOH).

Results: TG showed a decrease at age 60 years. Testis volume and TT did not show significant difference among the four age groups; cFT began to decrease at age 50 years and Bio-T decreased faster at age 50 years. SHBG and LH increased faster at age 50 and 70 years, respectively. IIEF5 score decrease faster at age 60 years. AMS scores increased faster at age 70 years. With the increase in age, the symptoms of ED and SLOH became severer.

Conclusion: Different indices on reproductive health of men showed turning points at different ages. At first, androgenic sex hormones decreased faster, and then erectile dysfunction got severer, and the last overall male syndromes declined.     

The relationship between lifetime health trajectories and socioeconomic attainment in middle age

A large literature demonstrates the direct and indirect influence of health on socioeconomic attainment, and reveals the ways in which health and socioeconomic background simultaneously and dynamically affect opportunities for attainment and mobility. Despite an increasing understanding of the effects of health on social processes, research to date remains limited in its conceptualization and measurement of the temporal dimensions of health, especially in the presence of socioeconomic circumstances that covary with health over time. Guided by life course theory, we use data from the British National Child Development Study, an ongoing panel study of a cohort born in 1958, to examine the association between lifetime health trajectories and socioeconomic attainment in middle age. We apply finite mixture modeling to identify distinct trajectories of health that simultaneously account for timing, duration and stability. Moreover, we employ propensity score weighting models to account for the presence of time-varying socioeconomic factors in estimating the impact of health trajectories. We find that, when poor health is limited to the childhood years, the disadvantage in socioeconomic attainment relative to being continuously healthy is either insignificant or largely explained by time-varying socioeconomic confounders. The socioeconomic impact of continuously deteriorating health over the life course is more persistent, however. Our results suggest that accounting for the timing, duration and stability of poor health throughout both childhood and adulthood is important for understanding how health works to produce social stratification. In addition, the findings highlight the importance of distinguishing between confounding and mediating effects of time-varying socioeconomic circumstances.     

Random effects regression mixtures for analyzing infant habituation

Random effects regression mixture models are a way to classify longitudinal data (or trajectories) having possibly varying lengths. The mixture structure of the traditional random effects regression mixture model arises through the distribution of the random regression coefficients, which is assumed to be a mixture of multivariate normals. An extension of this standard model is presented that accounts for various levels of heterogeneity among the trajectories, depending on their assumed error structure. A standard likelihood ratio test is presented for testing this error structure assumption. Full details of an expectation-conditional maximization algorithm for maximum likelihood estimation are also presented. This model is used to analyze data from an infant habituation experiment, where it is desirable to assess whether infants comprise different populations in terms of their habituation time.     

Trajectory of problem behaviours of Korean adopted children: using piecewise hierarchical linear growth modelling

This study examined the trajectory of problem behaviours in domestically adopted children in South Korea as they aged. This study used the Panel Study on Korean Adopted Children's longitudinal, three‐wave data (2006, 2008 and 2010). Although data were collected at three time points, our data consisted of six time points, which covered the 5–10 years age range of the adopted children at the time of survey. One hundred sixty‐four children were included in the analysis, 75 of whom contributed to one time point, 74 to two time points and 15 to three time points. The trajectory of the problem behaviours of adopted children was examined using a piecewise hierarchical linear growth model. Because the initial exploration of the data suggested non‐linear changes in behaviour problems over time, we split the growth trajectory into two time periods: Time 1 (5–7 years) and Time 2 (7–10 years). A two‐rate model was used to estimate separate slopes for the two time periods. Results showed that the externalizing and internalizing problems of adopted children have different trajectories. Internalizing problems did not show significant changes after 5 years of age, while externalizing problems increased until 7 years of age and decreased significantly thereafter.     

可拆装式湿法剪切粉碎设备结构设计与转子系统动态分析

为解决工业化生产中大量韧性湿物料粉碎难度大、粉碎部件磨损严重的难题,对大功率湿法剪切粉碎设备的关键部件进行结构设计与优化,将定转子优化为可装拆式结构。通过工程软件ANSYS对转子进行变形分析与模态分析,分析其高速转子系统的振动特征,为关键部件的结构设计与优化提供理论依据,为整机的动态稳定性分析奠定基础。     

基于正交试验的间歇传动链动力学仿真研究

以间歇传动链为研究对象,建立了该系统的虚拟样机。运用正交法设计试验,选择输入轴转速、导轨材料阻尼系数、链条和导轨之间的库仑动摩擦系数、预紧弹簧刚度和集中质量共5个因素作为试验参数,以链条附件加速度值作为振动指标,进行了间歇传动链的动力学仿真研究。     

基于扭转振动的多步态移动装置的运动学建模

为了实现移动机器人多步态稳定运动,提出一种新型的利用自身的结构特性来设计移动装置的方法。通过对其 倒立的U型结构的设计,再分别对该移动装置滑、走、跑和跳4个步态进行运动学建模,最后利用ADAMS仿真实现了该 移动装置稳定的多步态的运动。然后根据仿真结果给出了各运动相在每个步态周期中的足地接触距离以及横梁质心位 移的变化情况,最后讨论了影响该移动装置多步态运动的因素,如机体与两腿的长度之比r、共振频率和电机转速等。 结果表明该移动装置实现了多步态的运动,对未来研究多步态移动机器人提供了理论基础。