Growth Responses of Trees to Micronutrients and Their Feedback Effect in Various Soil-Forest Ecosystems of Taihu Lake Region

Vector analysis technique and ecological sequential comparison methods were adopted to study tree growth response to the micronutrients, B, Mo, Cu, Zn, Fe, and Mn, in soils derived from various parent materials in the forest area of Taihu Lake region in southeast China. The results showed that the dry weight of individual current-year needle of Chinese fir (Cunninghamia lanceolata) grown on the soi1 derived from granite parent rock was increased by 8% and 13% in comparison with that grown on the soils derived from sandstone and ash-tuff parent rock, respectively. And such dry weight of loblolly pine (Pinus taeda) grown on the soil derived from sandstone parent rock was increased by 21% in comparison with that on the soil derived from ash-tuff parent rock. One of the reasons for those results was that micronutrients content in the soil derived from ash-tuff parent rock were not sufficient to meet the requirement of the growth of Chinese fir and loblolly pine, i.e., micronutrients in soil were deficient and/or induced deficient. The amounts of Cu, Zn, Fe, and Mn uptake by Chinese fir and loblolly pine were in agreement with the contents of available micronutrients in soil respectively, except for B and Mo. Meanwhile, there might exist an "antagonism" between the uptake of B versus Mo by trees, although more studies are needed to confirm it. Regression analysis indicated that amount of a soil available micronutrient was correlated to the type of parent material and its total amount in the forest floor, except for B. The F test identified that the correlation of each equation reached the significant level to different extents, respectively. The t test confirmed that amount of available forms was mainly depended on the type of parent material for Mo, Cu, Zn and Mn but on the forest floor for Fe. There was a feedback effect of forest stand on the amount of soil available micronutrients. The ability of accumulating available micronutrients in soil was better by the sawtooth oak (Quercus acutissima) stand than by the Chinese fir stand (except for B). The ability of accumulating available Zn, Fe, Mn and Mo in soil was better by the Chinese fir stand than by the loblolly pine stand, while as for available B and Cu, by the latter was better than by the former. When discussing the effect of forest stand on the amount of soil available micronutrients, not only the amount of micronutrient in the forest floor and the parent materials but also the amount of micronutrient taken up by current-year needles have to be considered.

Component ACD Model and Its Application in Studying the Price-Related Feedback Effect in Investor Trading Behaviors in Chinese Stock Market

This paper explores the investors＇ feedback to the price change by modelling the price- related dynamics of trading intensity. A component decomposition duration modeling approach, called the component autoregressive conditional duration （CACD） model, is proposed to capture the variation of trading intensity across time intervals between price change events. Based on the CACD model, an empirical analysis is carried out on the Chinese stock market that covers different market statuses. The empirical results suggest that the CACD model can capture the price-related dynamics of trading intensity, which supports the existence of the feedback effect and is robust across different market statuses. The authors also study how the investors react to the price change by examining the driven factors of the price-related dynamics of trading intensity. The authors find that the trading can be triggered by the fast rise in the price level and the high trading volume. Besides, investors are more sensitive to the price change direction in the sideways market than in the upward or downward markets.

The Effectiveness of Peer Feedback in EFL Writing

Based on the students' capability of assessing peers' essays, this paper attempts to analyze the effectiveness of peer feed-back in EFL writing. Significant improvements can be made in writing proficiency, especially for the students who review others' essays. The reviewers may not only improve their peer's papers but also improve general writing skills and learn to self-evaluatetheir own writing.

Effect of Teacher Feedback, Peer Review and the Combination on EFL Writing Study Proposal

Since the result of effect comparison is important for teacher's decision making,roles teacher feedback and peer review play respectively and collaboratively in tertiary-level EFL writing context should be addressed via quantitative study as this paper proposed.Quantitative data should be collected from students'first drafts,second drafts and written comments from teachers and peers.Gains for overall scores between the first and second drafts and correlation between suggestions and gains should be examined.

Impulsive effect on exponential synchronization of neural networks with leakage delay under sampled-data feedback control

We consider the impulsive effect on the exponential synchronization of neural networks with leakage delay under the sampled-data feedback control. We use an appropriate Lyapunov-Krasovskii functional combined with the input delay approach and some inequality techniques to derive sufficient conditions that ensure the exponential synchronization of the delayed neural network. The conditions are formulated in terms of the leakage delay, the sampling period, and the exponential convergence rate. Numerical examples are given to demonstrate the usefulness and the effectiveness of the results.

Sex-specific facilitation and reproduction of the gynodioecious cushion plant Arenaria polytrichoides on the Himalaya-Hengduan mountains,SW China

When benefiting other beneficiaries,cushion plants may reciprocally receive feedback effects.The feedback effects on different sex morphs,however,remains unclear.In this study,taking the gynodioecious Arenaria polytrichiodes as a model species,we aimed to assess the sex-specific facilitation intensity of cushion plant by measuring the beneficiary cover ratio,and to assess the potential costs in cushion reproductive functions by measuring the flower and fruit cover ratios.The total beneficiary cover ratio was similar between females and hermaphrodites.Females produced much less flowers but more fruits than hermaphrodites.These results suggested that females and hermaphrodites possess similar facilitation intensity,and female cushion A.polytrichoides may allocate more resources saved from pollen production to seed production,while hermaphrodites possibly allocate more resources to pollen production hence reducing seed production.The surface areas covered by beneficiaries produced less flowers and fruits than areas without beneficiaries.In addition,strong negative correlations between beneficiary cover and flower cover were detected for both females and hermaphrodites,but the correlation strength were similar for these two sex morphs.However,the correlation between beneficiary cover and fruit cover was only significantly negative for females,suggesting that beneficiary plants negatively affect fruit reproduction of females while have neutral effects on hermaphrodites.All the results suggest that to facilitate other beneficiaries can induce reproductive costs on cushion A.polytrichoides,with females possibly suffering greater cost than hermaphrodites.Such differentiation in reproductive costs between sex morphs,in long-term perspective,may imply sex imbalance in population dynamics.

基于双回路反馈的光纤干涉式GIS局部放电超声传感系统研究

光纤干涉式GIS局部放电超声传感系统受到环境干扰,会导致超声检测灵敏度降低。基于单回路反馈的传感系统能够抑制振动干扰,但长时间工作仍会出现工作点漂移。文中首先分析了单回路反馈传感系统工作点漂移的原因,指出了压电陶瓷迟滞效应的影响;其次,搭建了基于双回路反馈的光纤干涉式GIS局部放电超声传感系统,引入了二次反馈回路以补偿一次反馈回路累积的低频相位调制误差;再次,通过振动干扰下的超声检测试验和GIS局部放电检测试验,证明了双回路反馈传感系统能够长时间保持稳定的超声检测灵敏度;最后,搭建了真型126 kV GIS局部放电检测试验平台,利用双回路反馈传感系统成功检测到了金属颗粒引发的局部放电和跳动声信号,检测到的最小视在放电量为5.2 pC。

县域帮扶的价值互馈效应——基于上市公司参与原国家级贫困县帮扶的研究

企业参与欠发达地区县域帮扶是推进乡村全面振兴和区域协调发展的重要举措。本文将企业参与欠发达地区县域帮扶视为一种具有跨区域投资特征的企业对地区的帮扶协作行为,并提出价值互馈效应这一概念,将之阐释为企业在助力欠发达县脱贫振兴的同时也从中获得补贴、业务拓展等价值回报且基于这种回报在该县进行扩大再帮扶。本文利用手工搜集的沪深上市公司参与原国家级贫困县帮扶的数据,进行县域帮扶价值互馈效应的实证检验,并发现:上市公司参与欠发达地区县域帮扶产生了价值互馈效应,即上市公司参与原国家级贫困县帮扶,能够获得与帮扶相关的补贴或业务拓展等价值回报且基于回报在该县扩大再帮扶,该结论在一系列稳健性检验之后依然成立;上述价值互馈效应一定程度上是通过产业帮扶实现的;来自市场化程度较低地区的公司,处于成长期和成熟期的公司,以及劳动密集型、技术密集型行业的公司参与县域帮扶的价值互馈效应更显著。据此,上市公司应重视参与县域帮扶的经济价值及其可持续性;国家乡村振兴重点帮扶县应由被动受帮扶转向帮扶协作,改善营商环境,确保产业帮扶协作项目有效落地和持续运营。

再生水投入与长江和黄河流域经济发展的互馈效应研究

基于面板向量自回归模型,收集了2011—2020年长江和黄河流域18个省(自治区、直辖市)的面板数据,在验证了面板数据的有效性基础上,分析了模型的结果、脉冲响应函数及方差分解结果,考察了再生水投入与长江和黄河流域经济发展之间的相互作用及动态双向影响。结果表明:再生水投入与长江和黄河流域经济发展之间具有相互促进、共同发展的关系,并具有区域差异性特征;在流域经济发展对再生水投入的影响上,黄河流域的依赖性明显大于长江流域;在再生水投入对流域经济发展的影响上,黄河流域和长江流域整体上均呈现正向影响,但长江流域正向影响滞后性更强。

社会建构、反馈效应与延迟退休年龄政策停滞

党的十八届三中全会以来,我国屡次提出研究和制定“渐进式延迟退休年龄政策”的方针策略,然时至今日,全国性的延迟退休政策尚未出台。以社会建构与政策设计理论为理论基础与分析框架,以1951—2021年54份中央政府文件为样本,考察目标群体的社会建构如何通过反馈效应影响延迟退休年龄政策进程,研究发现:干部和高级专业技术人员被正面建构且因政策受益,产生正反馈,政策长期仅适用于该群体,普通劳动者被正面建构但因政策受损,产生负反馈,以致全国性政策无法出台,政策陷入停滞;而正反馈效应长期积累促使社会建构转向,社会环境因素改变政策认知,进而推动政策进程。因此,政策制定者坚定决心,不断优化政策设计,回应目标群体的社会建构转向;党和中央政府以积极应对人口老龄化战略吸纳延迟退休年龄政策,塑造公众政策认知;地方政府积极开展政策试验,总结经验教训,这些措施都有助于加快政策进程。

目标群体异质性影响政策遵从的双重机制研究——以企业养老保险缴费所有制差异为例

相同政策下目标群体为何存在遵从差异?基于政策反馈理论,本文提出目标群体异质性影响政策遵从的双重机制:解释效应,政策认知在异质性目标群体之间存在差异,影响遵从意愿;资源效应,政策导致的资源变化在异质性目标群体中分配不均衡,影响遵从能力;二者的大小和方向共同决定遵从程度。以2008—2015年A股上市公司为样本,实证检验所有制影响两类企业养老保险政策遵从的机制。结果发现:(1)目标群体异质性通过解释效应和资源效应显著影响政策遵从;(2)解释效应可以与资源效应作用相反,且超过资源效应;(3)政策性质影响解释效应和资源效应。

自我效能、绩效反馈与创造性思维认知负荷的关系

该文以386名大学生作为被试,通过实证研究探讨自我效能、绩效反馈与创造性思维任务中认知负荷的关系。结果表明,积极性反馈和较强的自我效能感与创造性思维任务中较低的认知负荷有关,而较高的认知负荷会对创造性思维产生消极影响;自我效能感越高,创造性思维过程中的认知负荷就越低;与负反馈相比,正反馈与较低的认知负荷有关;较高的认知负荷对创造性思维绩效有负向影响;认知负荷在绩效反馈与创造性思维,以及自我效能与创造性思维间的关系中起部分中介作用。该研究对鼓励学生参与创造性思维活动的教育者的教学决策具有重要的启示意义。

股票市场正反馈交易的空间溢出效应——基于新冠疫情冲击的计量检验

利用空间自相关正反馈交易模型,对新冠疫情爆发前后国际股票市场的正反馈交易进行了检验.结果表明,新冠疫情爆发后国际股票市场正反馈交易显著增强并呈现空间相关特征.相关国家反危机的调控措施,虽然一度抑制了股票市场下行,但同时强化了投资者非理性的外推性预期,加剧了股票市场正反馈交易的空间溢出效应.因此,在新冠疫情不断持续的情况下,监管当局应充分考虑反危机调控措施对投资者心理账户和市场预期的影响,防范疫情冲击下股票市场正反馈交易空间溢出的风险联动效应.

小数字大作用——经济和环境反馈干预对群体节能行为作用效果的现场对照实验

私人消费领域中的个体或家庭节能行为已日益受到重视,然而对于群体消费情境下的用能者而言,如何促进其主动节能还缺乏关注。为了评估信息反馈策略激励群体用户节电行为的有效性,本研究开展了一项为期18周的现场对照实验。根据节能动机的差异,实验分为3个实验组(经济型反馈组、抽象环境型反馈组、具体环境型反馈组),并设置一个无干预对照组,以评估三种干预策略促进节电行为的有效性。实验以电力系统记录的居住者的真实用电量数据为依据,运用倾向得分匹配-双重差分法,分析三种干预策略的节电效果。结果显示:经济型反馈组和具体环境型反馈组可以显著促进群体用能者主动节电。其中,经济型反馈组的节电效果最好(14.4%),其次是具体环境型反馈组(6.2%),而抽象环境型反馈组与对照组无显著差异。干预策略的长期效应检验进一步发现,随着干预停止,经济型反馈组和具体环境型反馈组的节能效果仍然存在。干预停止后,具体环境型反馈组的节电效果更好,证明了具体环境型反馈策略的长期有效性。此外,本研究还发现:群体特征异质性也会影响不同干预策略的节电效果。这些结论为如何在群体消费情境下利用反馈干预措施节约能源提供了依据和可行的建议。

一种单反馈通道振荡射流激励器设计

为了设计一种有利于分离控制的振荡射流激励器,选取单反馈通道的形式,重点研究第二喉道与扩张段参数对射流振荡特性与偏转襟翼分离控制效果的影响,并总结几何参数设计依据,完成激励器设计并对比了其与典型激励器的分离控制效果。结果表明:反馈段参数应使射流在混合段扩张部分的偏角最大;混合段参数应使射流附着于混合段壁面;第二喉道应使射流向流场中均匀传递动量,其过小或过大均会减小射流偏角并导致射流向流场中传递动量不均匀;扩张段扩张角应增大至刚好不阻挡射流偏转,过大会使扩张段内射流发生不对称附着现象;增大出口高度可以增大射流偏移量,但其过大会延长射流在扩张段两侧的停滞时间。不同激励器的分离控制效果对比表明,采用自主设计激励器时的偏转襟翼减阻量是采用典型激励器时的3.8倍。

问题导学法在初中数学教学中的应用探究

问题导学法是指教师根据教学需要提出问题,然后引导学生对问题进行思考、探究和解决,以此激发学生的学习兴趣和学习动力,培养学生的问题解决能力、探究能力和创新意识,使其对数学知识形成深度理解并积极应用。在教学实践中,教师可以通过创设课堂教学情境、实施课堂提问教学、开展小组合作、有目的地设计问题、及时反馈和总结归纳等策略,充分发挥问题导学法的价值,实现课堂教学效率的提升。

基于未知多智能体系统的新型增益控制策略

针对一类具有未知状态与磁滞输入的多智能体系统稳定性问题,提出了一种基于新型时变增益的自适应控制方案。该方案包括构建新型高增益观测器、整合所有未知项并在微分控制环节中进行统一处理,以及调整时变增益信号中的补偿参数实现输入信号的波形降噪与上、下限约束。通过应用这一控制方案,可以实现系统的一致稳定性,还可有效降低微分控制环节中的计算量。除此之外,在系统频率响应的允许范围内调整补偿参数,可以实现输入降噪与上、下限约束。仿真实验结果表明,该方案成功实现了系统输入波形的上、下限约束和降噪优化,同时能够降低微分控制环节的计算量,提高系统的鲁棒性和适应性。

政策如何塑造大众?基于最近三十年国际政策反馈研究的元分析

自20世纪90年代以来,关注政策如何塑造政治的政策反馈研究逐步成为政策过程研究的重要子领域。尽管公共政策对大众政治态度和行为的影响受到广泛关注,但是现有研究发现大众反馈效应的程度及其方向存在显著差异。论文提出一项新的分析框架,指出大众反馈效应会随着政策类型、分析角度、福利状态、关注议题和国家等因素的变化而变化。对近30年来国际上110项实证研究中549个效应量进行元分析发现:在政策类型方面,分配型和建构型政策的平均效应量大于再分配型政策和管制型政策的平均效应量。在分析角度方面,相比“政策投入”,基于“政策参与”和“政策变迁”发现的反馈效应更突出。在福利状态方面,论文引入“负向偏误”理论揭示出福利削减会产生比福利增加更显著的非对称效应。在关注议题方面,分析结果未表明政策对个体政策态度、政治态度与政治参与的影响存在显著差异。而且,分析结果也未支持国家情境的影响。另外,论文重点总结了亟待推进的两个研究方向:以福利削减为主题和基于中国情境的研究。论文有助于增进学界对大众反馈效应及其影响因素的系统认知,深化对政策的政治效应的理解。

微纳光栅MOEMS加速度计优化设计与测试

提出了一种基于微纳光栅泰伯效应的微光机电系统(MOEMS)加速度计,通过Comsol软件对加速度计结构和光栅结构参数进行优化,使其在20g量程范围内获得较大的结构灵敏度和衍射效应灵敏度,同时通过仿真分析了该结构的交叉轴串扰情况。由于受外界温度起伏影响,双层光栅结构间距受热膨胀系数的影响产生相对位移。为了减小由于温度起伏对光栅加速度计零偏的影响,采用温度闭环反馈控制技术将加速度计温度变化控制在±10 mK范围内。经实验测试,加速度计零偏稳定性达3.7μg,相较于无温控情况提升了近7倍。最终实现光栅MOEMS加速度计的灵敏度达5.23 V/g,线性相关系数为99.9%,分辨率达286.8μg。

西安市地方标准实施信息反馈研究初探

标准实施效果评价是标准化工作的重要组成部分,是促进标准化生态圈良性发展的重要一环。为了促进标准实施的进一步落实,做好标准制修订、完善标准体系建设等工作,标准实施信息反馈的研究尤为重要。本文主要从反馈内容、反馈方法、信息采集、信息输出四个方面进行了标准实施信息反馈研究,提出了西安市地方标准实施信息反馈的方法。