作为媒介的社会组织对乡村生活共同体建构的影响——基于苏州市M村的个案研究

改革开放后,随着乡村经济由传统农业向现代产业转型,乡村的社会关系和生活方式产生深刻变革,传统的乡土团结逐渐瓦解。同时,城市化进程加速引发的人口外流,导致乡村社区空心化和人际关系淡化,进而加剧了乡村的原子化趋势。在此背景下,重建乡土团结成为乡村治理中亟须解决的问题。研究以苏州市的一个乡村为案例,以媒介交转性为理论视角,采用线上与线下相结合的参与式观察和深度访谈法,探讨作为外源型力量的社工组织进入乡村后如何成为媒介,并建构人与人、人与村庄的新型关系,从而促进乡村社会再团结。之所以选择社工组织为研究对象,是因为社工组织作为一种公益、半公益性质的社会组织,在社区营造、便民服务供给、社会关系调解等方面能够发挥重要作用,对于乡村社会的团结建构意义非凡。与此同时,对于一些发达地区的村庄而言,其公共基础设施已相当完备,通过集体修路、铺桥、造公厕等“事件团结”的方式凝聚人心、培养互助友爱精神,已变得收效甚微。而社工组织这种通过社会支持来培养群众公共性和主体性的外源型力量,恰好能弥补此类村庄团结机制缺失的问题。研究发现:作为媒介的社工组织首先通过便民服务供给的方式,将村民、村干部等多元主体连接起来,以此密切村庄内部人与人之间的联系;其次,在连接的基础上,村民与村民、村民与村干部之间经由交往实践,建构了一种彼此交融的整体化生活方式,展现出社工组织的媒介“交互”作用;再者,借由交互实践,社工组织与村庄之间共同编织出一张新的社交网络,使得村民与村民、村民与村干部之间的关系发生改变,一定程度上重塑了村庄的社会关系格局;最终,在社工组织促成的关系再生产后,村民的公共性和主体性得到强化,在村庄公共事务参与中体现出强烈的互助友爱精神,建构出乡村生活共同体的美好图景。总体来看,作为媒介的社工组织对乡村生活共同体的塑造,经历了一个“建立连接—展开互动—再生关系—建构意义”的递进式动态过程,其所构建的社会关系,重塑了乡村居民日常生活中的公共性,为乡村治理的媒介化转向提供了可能。

Corrosion resistance of in-situ Mg-Al hydrotalcite conversion film on AZ31 magnesium alloy by one-step formation

In situ growth of nano-sized layered double hydroxides （LDH） conversion film on AZ31 alloy was synthesized by a urea hydrolysis method. The formation mechanism of the film was proposed. Firstly, the dissolved Mg2＋ ions deposited into a precursor film consisted of MgCO3 and Mgs（CO3）4（OH）2·4H2O; secondly, the precursor translated into the crystalline Mg（OH）2 in alkaline conditions; finally, the Mg2＋ ions in Mg（OH）z were replaced by A13＋ ions, Mg（OH）2 translated into the more stable LDH structure, simultaneously, the OH- ions in the interlayer were exchanged by CO32-, thus led to the formation of the LDH （Mg6Alz（OHh6CO3·4H2O） film. The results indicated that the LDH film characterized by interlocking plate-like nanostructures and ion-exchange ability significantly improved the corrosion resistance of the AZ31 Mg alloy.

Mechanisms of cancer metastasis to the bone

Some of the most common human cancers, including breast cancer, prostate cancer, and lung cancer, metastasize with avidity to bone. What is the basis for their preferential growth within the bone microenvironment? Bidirectional interactions between tumor cells and cells that make up bone result in a selective advantage for tumor growth and can lead to bone destruction or new bone matrix deposition. This review discusses our current understanding of the molecu- lar components and mechanisms that are responsible for those interactions.

Variable-order rotated staggered-grid method for elastic-wave forward modeling

Numerical simulations of a seismic wavefield are important to analyze seismic wave propagation. Elastic-wave equations are used in data simulation for modeling migration and imaging. In elastic wavefield numerical modeling, the rotated staggered-grid method （RSM） is a modification of the standard staggered-grid method （SSM）. The variable-order method is based on the method of variable-length spatial operators and wavefield propagation, and it calculates the real dispersion error by adapting different finite-difference orders to different velocities. In this study, the variable-order rotated staggered-grid method （VRSM） is developed after applying the variable-order method to RSM to solve the numerical dispersion problem of RSM in low-velocity regions and reduce the computation cost. Moreover, based on theoretical dispersion and the real dispersion error of wave propagation calculated with the wave separation method, the application of the original method is extended from acoustic to shear waves, and the calculation is modified from theoretical to time-varying values. A layered model and an overthrust model are used to demonstrate the applicability of VRSM. We also evaluate the order distribution, wave propagation, and computation time. The results suggest that the VRSM order distribution is reasonable and VRSM produces high-precision results with a minimal computation cost.

Sediment Movement in Periodic Alternating Current

The present paper summarizes the results of previous studies, including the structure and principle of the rotary ring flume for researching the fine sediment movement, the mechanism of the flume, method of eliminating the influence of the centrifugal force and sediment movement experiments with periodic alternating current. Also included are the experiment-based relationship among sediment concentration, bed shear stress and silt carrying capacity, a proposed erosion-deposition function and bed erosion-deposition calculation together with the results of verification.

Performance optimization of electric power steering based on multi-objective genetic algorithm

The vehicle model of the recirculating ball-type electric power steering (EPS) system for the pure electric bus was built. According to the features of constrained optimization for multi-variable function, a multi-objective genetic algorithm (GA) was designed. Based on the model of system, the quantitative formula of the road feel, sensitivity, and operation stability of the steering were induced. Considering the road feel and sensitivity of steering as optimization objectives, and the operation stability of steering as constraint, the multi-objective GA was proposed and the system parameters were optimized. The simulation results show that the system optimized by multi-objective genetic algorithm has better road feel, steering sensibility and steering stability. The energy of steering road feel after optimization is 1.44 times larger than the one before optimization, and the energy of portability after optimization is 0.4 times larger than the one before optimization. The ground test was conducted in order to verify the feasibility of simulation results, and it is shown that the pure electric bus equipped with the recirculating ball-type EPS system can provide better road feel and better steering portability for the drivers, thus the optimization methods can provide a theoretical basis for the design and optimization of the recirculating ball-type EPS system.

Performance analysis of optical burst switching node with limited wavelength conversion capabilities

The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.

Variation in soil properties in a transformed ecosystem in Southwestern Nigeria

Variation in soil properties as a result of the conversion of the tropical rainforest to a monospecific plantation of teak, tectona grandis, was examined in Akure forest reserve in Southwestern Nigeria. Comparison was made in the active rooting zone of 50 cm soil depth. It was discovered that there were no significant differences in the physical properties except in the value of organic matter content at the top 10 cm layer but chemical properties such as the pH and organic carbon changed significantly at the top 10 cm layer. Differences in other chemical properties, such as the available P, exchangeable cations K, Ca and Mg, the exchangeable acidity and the cation exchange capacity were minor. This showed that no nutrient was limiting or was likely to be limiting in the soil for subsequent short rotation of plantation development.

Super-exchange and Exchange-Enhanced Reactivity in Fe_(4)S_(4)-Mediated Activation of SAM by Radical SAM Enzymes

[4Fe-4S]-dependent radical S-adenosylmethionine(SAM)proteins are a superfamily of oxidoreductases that can catalyze a series of challenging transformations using the common 5-d Ado radical intermediate.Although the structures and functions of radical SAM enzymes have been extensively studied,the electronic state-dependent reactions of the[4Fe-4S]clusters in these enzymes are still elusive.Herein we performed QM/MM calculations to elucidate the electronic state-dependent reactivity of the[4Fe-4S]cluster in pyruvate-formate lyase activating enzyme.Our calculations show that the electronic statedependent SAM activation by the[4Fe-4S]clusters in radical SAM enzyme is determined by both the super-exchange and exchange-enhanced reactivities.The super-exchange coupling in the[4Fe-4S]cluster favors the antiferromagnetic coupling between two neighbouring pairs,which results in theα-electron rather than theβ-electron donation from the[4Fe-4S]^(1+)cluster toward the SAM activation.Meanwhile,in the most favorable electronic state for the reductive cleavage of S-C5′,Fe4 would donate itsα-electron to gain the maximum exchange interactions in the Fe4-block.Such super-exchange and exchange-enhanced reactivity could be the general principles for reactivities of[4Fe-4S]cluster in RS enzymes.

Pneumatic Performance of Staggered Impulse Turbine for OWC Wave Energy Convertor

A staggered impulse turbine is proposed for asymmetric air flows in Oscillating Water Column wave energy plants, which is expected to enhance the pneumatic power output in a wave cycle. The setting angle of rotor blades is set as 5°. The 3D numerical simulations were conducted under steady conditions using MRF and Mixing Plane model based on CFD software Fluent 12.0. Its mean efficiencies under different velocity amplitude ratios are studied using quasi-steady analysis, which derive corresponding data from the numerical simulation. It is found that the staggered turbine shows better performance than the conventional one under the asymmetrical air flows. Furthermore, its mean efficiency and output-work in a wave period are compared with another unsymmetrical twin impulse turbine system. The results show that the staggered turbine shows better output-work performance than the twin turbine system over the high flow coefficient domain(φ>0.7), which provides more choices to future research on turbine's optimization.

Electronic physics and possible superconductivity in layered orthorhombic cobalt oxychalcogenides

We suggest that cobalt-oxychalcogenide layers constructed by vertex sharing CoA_2O_2(A = S, Se, Te) tetrahedra, such as BaCoAO, are strongly correlated multi-orbitals electron systems that can provide important clues on the cause of unconventional superconductivity. Differing from cuprates and iron-based superconductors, these systems lack of the D_(4h) symmetry classification. However, their parental compounds possess antiferromagnetic(AFM) Mott insulating states through pure superexchange interactions and the low energy physics near Fermi surfaces upon doping is mainly attributed to the three t_(2g) orbitals that dominate the AFM interactions. We derive a low energy effective model for these systems and predict that a d-wave-like superconducting state with reasonable high transition temperature can emerge by suppressing the AFM ordering even if the pairing symmetry can not be classified by the rotational symmetry any more.

Effects of a Weakly Interacting Light U Boson on Protoneutron Stars Including the Hyperon-Hyperon Interactions

In the framework of the relativistic mean field theory including the hyperon-hyperon(YY) interactions,protoneutron stars with a weakly interacting light U boson are studied. The U-boson leads to the increase of the star maximum mass. The modification to the maximum mass by the U-boson with the strong YY interaction is larger than that with the weak YY interaction. The maximum mass of the protoneutron star is less sensitive to the U-boson than that of the neutron star. The inclusion of the U-boson narrows down the mass window for the hyperonized protoneutron stars. As g^2/μ~2 increases, the species of hyperons, which can appear in a stable protoneutron star decrease. The rotation frequency, the red shift, the momentum of inertia and the total neutrino fraction of PSR J1903-0327 are sensitive to the U-boson and change with g^2/μ~2 in an approximate linear trend. The possible way to constrain the coupling constants of the U-boson is discussed.

Establishment of a transgenic mouse model with liver-specific expression of secretory immunoglobulin D

Mutation of mevalonate kinase （MVK） is thought to account for most cases of hyperimmunoglobulinemia D syndrome （HIDS） with recurrent fever. However, its mechanism and the relationship between elevated serum immunoglobulin D （IgD） and the clinical features of HIDS are unclear. In this study, we generated by fusion PCR a vector to express high levels of chimeric secretory IgD （cslgD） specifically in the liver. We then generated seven founder lines of transgenic mice by co-microinjection, and verified them using genomic PCR and Southern blotting. We detected the expression of csIgD by reverse transcription PCR, quantitative PCR, western blotting, and enzyme-linked immunosorbent assays. We demonstrated that csIgD could be specifically and stably expressed in the liver. We used flow cytometry to show that overexpression of csIgD in the bone marrow and spleen cells had no effect on B cell development. Morphologic and anatomical observation of the transgenic mice revealed skin damage, hepatosplenomegaly, and nephromegaly in some transgenic mice; in these mice, pathological sections showed high levels of cell necrosis and protein-like sediments in the liver, spleen, and kidney. We demonstrated that the genomic insertion sites of the transgeues did not disrupt the MVK gene on mouse chromosome 5. This transgenic mouse will be useful to explore the pathogenesis of HIDS.

The effect of secondary structures on the generation of characteristic events during the translocation of DNA hybrid through ?-hemolysin

Nanopore has been developed to be a powerful,single-molecule analytical tool for sensing ions,small organic molecules and biomacromolecules such as proteins and DNAs.Generally,the identity of the analyte can be revealed by current amplitude changes and mean dwell time of the analyte binding events.In some cases,generation of highly characteristic current events affords an alternative way of analyte determination with high confidence level.However,we found that secondary structures in DNA/RNA hybrids might severely hinder the generation of signature events during their translocation through?-hemolysin nanopore.In this report,we propose a strategy to add a certain concentration of urea in the buffer solution for single channel recordings and validate that low concentration of urea can effectively denature the secondary structures in DNA hybrids and recover the generation of signature events.This finding might be useful in other secondary structure-related nanopore sensing activities.