“关系就医”与城市居民就医认可——基于关系资本“负功能”的讨论

基于关系资本的“负功能”讨论,在尝试克服自选择性偏误的前提下,重新审视了关系资本对就医认可负面效应的呈现,并进一步考察了这一负面效应的发生机制。研究发现:在排除诸多因素干扰后,关系资本仍对就医者就医总体认可产生稳健的负面效应;关系资本会显著提升就医资源性认可而降低就医制度性认可;关系资本对就医总体认可产生的负面效应在关系资本使用可能性更低的就医者中更为明显。就医认可中的关系资本“负功能”发生机制并非非理性的关系无用论,而是制度损害换取资源便利的关系侵蚀论以及关系异质性回报的关系分化论,未来的关系资本研究需要更加重视“正负功能”的转换。

新发展阶段下高校资助育人功能面临的挑战及解决路径

新发展阶段是我国在全面建成小康社会后向着第二个百年奋斗目标迈进的关键时期,尽管高校资助育人工作在各方的努力下取得了明显的正面效果,但也出现了“假经济困难”“坐等靠要”等负面现象,受助学生感恩、诚信、自强等意识日渐缺乏。出于善的动机的资助育人工作,为何起到了负面作用?本文基于育人功能的视角,探索新发展阶段下高校资助工作如何扭转育人的负功能并巩固脱贫攻坚的育人成效,对进一步优化资助方式、打造“三全育人”新格局和培养德智体美劳全面发展的社会主义建设者和接班人具有十分重大的意义。

Alzheimer’s disease classification based on sparse functional connectivity and non-negative matrix factorization

A novel framework is proposed to obtain physiologically meaningful features for Alzheimer's disease(AD)classification based on sparse functional connectivity and non-negative matrix factorization.Specifically,the non-negative adaptive sparse representation(NASR)method is applied to compute the sparse functional connectivity among brain regions based on functional magnetic resonance imaging(fMRI)data for feature extraction.Afterwards,the sparse non-negative matrix factorization(sNMF)method is adopted for dimensionality reduction to obtain low-dimensional features with straightforward physical meaning.The experimental results show that the proposed framework outperforms the competing frameworks in terms of classification accuracy,sensitivity and specificity.Furthermore,three sub-networks,including the default mode network,the basal ganglia-thalamus-limbic network and the temporal-insular network,are found to have notable differences between the AD patients and the healthy subjects.The proposed framework can effectively identify AD patients and has potentials for extending the understanding of the pathological changes of AD.

Effect of captopril on myocardial energy metabolism in chronic pressure overload rats

Objective To investigate the effects of captopril on cardiac function and levels of energy-rich phosphates in pressure overload induced left ventricular hypertrophy rats. Methods One hundred and twenty SD rats were randomly divided into three groups： sham operation group （SH group, n=40）,coarctation of abdominal aorta group （CAA group, n=40） and captopril treatment lmg~ 100g1 ~ d-1） group （CAP group, n=40）. Left ventricular end-diastolic pressure （LVEDP）, left venh-icular mass index （LVMI）, levels of energy-rich phosphates and morphological changes of the myocardial mitochondria were compared at the 62 and 82 week after operation. Results At 62 week, in CAA group, LVMI and LVEDP were increased and _ dp/dtmax was decreased, while ATP and ADP were decreased and AMP was increased （P〈0.01）. These changes were much obvious at 8th week （P〈0.01）. Compared with those of CAA group, the parameters of heart function and energy-rich phosphates （ATP, ADP, AMP, TAN） in CAP group were improved significantly（P〈0.01） at the 6th and 8th week. In CAP group, the parameters of heart function and energy-rich phosphates （ADP, AMP, TAN） were much better at 8~ week than those at 6th week. The morphological change of mitochondria was less in CAP group than that in CAA group. Conclusion Captopril significantly improves myocardial energy metabolism in pressure overload rats and protects the function of myocardial mitochondria

The Bi-directional Three-Phase PWM Rectifier Inverter for Electric Vehicle Charging Station

Applications of electric vehicles need to build a large number of charging stations. The electric vehicle charging stations communicate with the grid. In V2G （vehicle to grid） mode, electric vehicles can be used as energy storage units and transfer power to the grid. The electric vehicles charge at night to reduce the cost and the grid load, simultaneously to fill the valley. When grid load increases, electric vehicles＇ batteries discharge to the grid to improve the stability of the grid. As distributed storage units, electric vehicles are important components of the smart grid. In this paper, the three-phase PWM （pulse width modulation） rectifier used for smart charging and discharging system of electric vehicles are analyzed and designed. This paper includes the principle of PWM rectifier-inverter and direct current control strategy. Also, the SVPWM （space vector pulse width modulation） and system design of three-phase PWM rectifiers are analyzed. A 10 kW prototype is developed. Simulation and experiment results show that the three-phase PWM rectifiers reach the unit power factor. From the experimental results, PWM rectifier implements the sinusoidal grid current and achieves the unit power factor.

Species abundance is jointly determined by functional traits and negative density dependence in a subtropical forest in southern China

Aims The factors affecting species abundance are a subject of ongoing debates in community ecology.Empirical studies have demonstrated that tree abundance is affected by plant functional traits and negative density dependence(NDD).However,few studies have focused on the combined effects of NDD and plant functional traits on species abundance.Methods In this study,we used tree functional traits and two census data from a 50-ha forest dynamic plot in the Heishiding(HSD)Nature Reserve to explore the combined effects of functional traits and NDD on species abundance.Using hierarchical Bayesian models,we analyzed how neighbor densities affected the survival of saplings from 130 species and extracted posterior means of the coefficients to represent NDD.The structural equation modeling(SEM)analysis was then applied to investigate the causal relationships among species functional traits,NDD and species abundance.Important Findings SEM showed that tree functional traits,including specific leaf area(SLA),leaf area(LA),leaf dry matter content(LDMC),leaf N content(LNC),maximum electron transport rate(ETRmax)and conspecific adult negative density dependence(CNDDadult),together explained 20%of the total variation in tree abundance.Specifically,SLA affected tree abundance both directly and indirectly via CNDDadult,with a totally negative influence on abundance.LDMC and LNC had only indirect effects mediated by CNDDadult on tree abundance.ETRmax and LA had directly negative effects on abundance,but their direct connections with CNDDaduIt were not observed.In addition,CNDDadult was negatively correlated with species abundance,indicating that abundant species are under stronger NDD.Among these investigated traits,SLA contributed the most to the variation in CNDDaduIt and abundance.We argued that our findings of trait-CNDDadult-abundance relationships can improve our understanding of the determinants of species commonness and rarity in forests.

Sequences of Lower Bounds for the Perron Root of a Nonnegative Irreducible Matrix

Estimate bounds for the Perron root of a nonnegative matrix are important in theory of nonnegative matrices.It is more practical when the bounds are expressed as an easily calcu-lated function in elements of matrices.For the Perron root of nonnegative irreducible matrices,three sequences of lower bounds are presented by means of constructing shifted matrices,whose convergence is studied.The comparisons of the sequences with known ones are supplemented with a numerical example.

Filling and unfilling carbon capsules with transition metal oxide nanoparticles for Li-ion hybrid supercapacitors:towards hundred grade energy density

Li-ion hybrid supercapacitors （Li-HECs） facilitate effective combination of the advantages of supercapacitors and Li-ion batteries （LIBs）. However, challenges remain in designing and preparing suitable anode and cathode materials, which often require tedious and expensive procedures. Herein, we demonstrated that hollow N-doped carbon capsules （HNC） with and without a Fe304 nanoparticle core can respectively function as the anode and the cathode in very-high-performance Li-HECs. The Fe3Oa@NC anode exhibited a high reversible specific capacity exceeding 1530 mA h g^-1 at 100 mA g^-1 and excellent rate capability （45% capacity retention from 0.1 to 5 A g^-1） and cycle stability （〉97% retention after 100 cycles）. Moreover, high rate performance was achieved in a full-cell using the HNC cathode. By combining the respective structural advantages of the components, the hybrid device with Fe3Oa@NC//HN C exhibited a remark- able energy density of 185 W h kg^-1 at a power density of 39 W kg^-1. The hybrid device furnished a battery-inaccessible power density of 28 kW kg^-1 with rapid charging/discharging within 9 s at an energy density of 95 W h kg^-1.