Definition of fine roots on the basis of the root anatomy, diameter,and branch orders of one-year old Fraxinus mandshurica seedlings

Fine roots are important in root absorption of nutrient and water,and in root turnover.Accurate definition of fine roots is a prerequisite to improved estimation of the physiological and ecological functions of forest ecosystems.Root development and physiological functions are reflections of root anatomical structure.In this study,the anatomical structures of different root orders were analyzed by examining paraffin sections of one-year old Fraxinus mandshurica seedlings.One-year-old F.mandshurica seedlings had over five root orders.The root anatomical structures of all orders showed more differences.First and second order roots consisted of four sections： the epidermis,cortex,pericycle,and vascular bundles.Fourth and fifth order roots were mainly composed of the skin and peripheral vascular bundles（including the xylem and phloem）.Third order roots had root epidermal and cortical structures,but the quantity and integrity of the cortical cells were inferior to those of the first and second order roots,and superior to those of the fourth and fifth order roots.All the first and second order roots and some third order roots with discontinuous cork layer（〈0.4 mm in diameter）,but not the fourth and fifth order roots,were the fine roots of one-year old F.mandshurica seedlings.Although they had similar diameters,different portions of root systems had different anatomical structures and therefore,vary in capacity to absorb water and nutrients.Fine roots were accurately defined by root diameter,branch orders,and anatomical structural features of one-year old F.mandshurica seedlings.

Root phosphatase activity is a competitive trait affiliated with the conservation gradient in root economic space

Background:The diversity of resource acquisition strategies of plant roots determines the species coexistence patterns to a certain extent.However,few root physiological traits have been investigated,such as root phosphatase activity(PA)that affects plant phosphorus(P)uptake.Methods:Root PA and classical root functional traits were investigated for 21 coexisting species in a deciduous broad-leaved forest in warm temperate-subtropical transition zone,China.We analyzed the root order variation of absorptive fine root PA,clarified the attribution of root PA in root economic space(RES)and the different P acquisition strategies of co-occurring species based on the multidimensional RES theory,and determined the dominant factors affecting interspecific variation in root PA.Results:There was no distinct pattern of PA variation with root order in the first three root orders of absorptive fine roots,and root PA was constrained by phylogeny.Root PA is a competitive trait affiliated with the conservation gradient in RES.The tight linkages among root PA,mycorrhizal colonization,diameter,specific root length,and nitrogen concentration suggested trade-offs among P acquisition strategies of co-occurring species,i.e.species with long and fine roots acquire inorganic P by actively exploring the soil and secreting phosphatase to mineralize and hydrolyze organic P,while species with short and thick roots obtain P mainly by investing C in mycorrhizal partners.Conclusions:Collectively,our study provides an insight into the forest species coexistence in climatic transition zones,i.e.species coexistence mechanisms based on diverse phosphorus acquisition strategies.

High-Order Iterative Methods Repeating Roots a Constructive Recapitulation

This paper considers practical, high-order methods for the iterative location of the roots of nonlinear equations, one at a time. Special attention is being paid to algorithms also applicable to multiple roots of initially known and unknown multiplicity. Efficient methods are presented in this note for the evaluation of the multiplicity index of the root being sought. Also reviewed here are super-linear and super-cubic methods that converge contrarily or alternatingly, enabling us, not only to approach the root briskly and confidently but also to actually bound and bracket it as we progress.

Computationally efficient direction finding using polynomial rooting with reduced-order and real-valued computations

The root multiple signal classification（root-MUSIC） algorithm is one of the most important techniques for direction of arrival（DOA） estimation. Using a uniform linear array（ULA） composed of M sensors, this method usually estimates L signal DOAs by finding roots that lie closest to the unit circle of a（2M-1）-order polynomial, where L 〈 M. A novel efficient root-MUSIC-based method for direction estimation is presented, in which the order of polynomial is efficiently reduced to 2L. Compared with the unitary root-MUSIC（U-root-MUSIC） approach which involves real-valued computations only in the subspace decomposition stage, both tasks of subspace decomposition and polynomial rooting are implemented with real-valued computations in the new technique,which hence shows a significant efficiency advantage over most state-of-the-art techniques. Numerical simulations are conducted to verify the correctness and efficiency of the new estimator.

“平台”与我国县域基层法治秩序的生成——浙江海宁社会治理实践的观察

基层社会治理“平台”是我国县域范围构建具有中国特色法治秩序的重要实践形式。在提升县域基层社会治理水平的过程中,平台被打造成一个由不同政府机构、不同社会组织与社会成员通过协调、协商、议论等方式博弈以解决与民生密切相关的各种类型问题的工作机制,客观上已经助力生成了法治秩序不可或缺的不同主体之间展开话语交流的公共空间。在浙江海宁,平台被用于促进实现公众与企业合法权利、改造和规范行使公共权力、保障社会稳定与居民安居乐业,以公开促公正公平,有效提升了法律在基层的实施能力。在法治建设正在寻求新的突破之际,有关平台建设的实践具有一定的可借鉴的普遍意义。

基层政府治理水平对农民奋斗价值观的影响研究

赓续艰苦奋斗精神,激发农民奋斗意志,是当前基层治理中农民思想建设的重要内容。基于2018年与2020年中国家庭追踪调查数据,利用有序Probit模型,实证分析基层政府治理水平对农民奋斗价值观的影响及作用机制。研究发现:第一,基层政府治理水平与农民奋斗价值观呈正相关,即基层政府治理水平越高,农民越倾向于认为“努力工作能有回报”,越发增强“对未来的信心”;第二,基层政府治理水平对农民奋斗价值观的影响,主要通过提高该群体的生活满意度和工作满意度来实现;第三,高水平的基层政府治理正向促进了建档立卡农民和非建档立卡农民奋斗价值观的塑造,且这种促进作用在非建档立卡农民中更显著。

扫描根窗法在落叶松人工林细根动态研究中的应用

植物根系深藏于地下,由于缺乏有效的观测方法,制约了对根系的了解。以落叶松人工林为研究对象,根据扫描根窗法对落叶松人工林细根长期观测案例,介绍扫描根窗法在野外原位观测细根动态的过程。结果表明:在深秋季节安装根窗,根窗安装扰动后恢复期为1 a,经过冻融交替和一个生长季后,细根现存量迅速恢复且趋于稳定;通过观察发现吸收根现存量峰值多出现在春季和初夏,而运输根峰值多出现在秋季;野外根窗法与微根管法相比可清晰的观测到细根的完整分枝结构,将高度异质性的细根群体细分为不同根序或功能类型,为区分不同细根功能和分枝等级提供了手段。

基于高阶累计量Root-MUSIC法和Prony法的轧辊偏心谐波参数估计

针对轧辊偏心信号是混杂在各种随机干扰中含有多次谐波的复杂高频周期信号,以及FFT(Fast Fourier Transform)法对轧辊偏心信号分析的局限性,研究了一种基于四阶累积量的Root-MUSIC(Multiple Signal Classification)法和Prony法相结合的轧辊偏心信号估计新方法.利用基于四阶累积量的Root-MUSIC法准确估计出偏心谐波的频率及谐波的个数,同时由Root-MUSIC求得的根直接使用Prony方法估计出偏心信号的各次谐波幅值和相位.仿真结果和实验结果也验证了结合方法的可行性和有效性,在信噪比较低的情况下仍具有较高的频谱分辨率和估计精度,能准确地同时估计出偏心谐波的频率、幅值及相位,尤其在频率分辨率和抗噪声上具有FFT法无法比拟的优越性.

Root stoichiometric dynamics and homeostasis of invasive species Phyllostachys edulis and native species Cunninghamia lanceolata in a subtropical forest in China

The community species abundance and diversity declined with bamboo invasion had been widely reported worldwide.However,the physiological strategies used during root competition between native species and invasive bamboo are poorly understood.To clarify the mechanisms underlying such strategies,the stoichiometric dynamics and homeostasis of nitrogen,phosphorus,organic carbon in root orders of Phyllostachys edulis(I du[=Ⅰ-Pe,years 1 and 2];Ⅱdu[=Ⅱ-Pe,years 3 and 4]),Cunninghamia lanceolata in transition and pure forests were analyzed.With increasing intensity of bamboo invasion,N,P,and C content of C.lanceolata root orders declined,N and P content in P.edulis rhizome orders declined,while C increased,the stoichiometric ratios in mixed forest interface mainly increased,and the stoichiometric differences within native and invasive species root orders narrowed.Meanwhile,the stoichiometric homeostasis index(H)of elements in the same root order and even the same elements in different root orders were not consistent.H of most root orders(except some HP)was greater than 4,the H ranked order wasⅠ-Pe>Cl>Ⅱ-Pe in mixed interfaces,and the N:P ratio of most species root orders was greater than 16,despite being affected by invasion.Our research concluded that the bamboo invasion narrows stoichiometric differences within root orders,and the juvenile bamboo rhizome has a stronger capacity for homeostatic regulation than in adult bamboo and C.lanceolata,which is a key determinant of bamboo invasion success.

波束域Root-MUSIC算法的进一步降阶处理

研究了波束域降阶Root-MUSIC算法,在子阵分解降阶的基础上,进一步将多项式的求根阶次降到与源数目相同,提出了求解降阶多项式的方法。该方法最大程度地减少了求根多项式的阶次和求解多项式的次数,并保持了Root-MUSIC算法的优良性能。显著降低运算量是其最大优点,仿真结果验证了降阶算法的有效性,并比较了不同阶次波束域Root-MUSIC算法的估计性能。

超声处理时间对莲藕淀粉理化和结构特性的影响

以莲藕淀粉(lotus root starch,LS)为对象,探究不同超声时间(0、10、20、30、40、50 min)对LS糊化特性、流变特性以及片层结构、结晶结构、短程有序结构、微观结构等的影响。结果表明,不同超声时间处理后LS分子链溶胀和缠结增加,糊化黏度最大增至(6059±31)mPa·s;淀粉颗粒表面出现裂缝、塌陷及坑洞,利于水分子进入,黏弹性增加。在超声作用下LS的α-1,6-糖苷键被破坏,部分支链断裂,形成淀粉短链,重新排列成有序的结构,短程有序结构增多,R_(1047/1022)值升高了3.20%;较短时间的超声处理(30 min)增强了淀粉分子间的相互作用,双螺旋结构变得有序和紧密,使T_p和ΔH值分别增大了11.09%和89.21%。长时间超声处理(40~50 min)不利于这种有序结构的形成。本研究结果可为超声技术在淀粉理化特性及多尺度结构调控中的应用提供理论参考。

基于扎根理论的农村订单定向医学生职业认同的影响因素分析:一项质性研究

背景随着我国农村订单定向医学生(以下简称公费医学生)培养项目的持续开展,基层全科医学人才队伍不断充实,公费医学生职业认同现状及影响因素备受关注。目的分析公费医学生职业认同的影响因素。方法采用目的性抽样方法,以山东中医药大学2018-2022级中医学(五年制)惠民班的30名公费医学生为访谈对象,采用半结构化访谈方式于2022年12月—2023年3月进行访谈。遵循AnselmStrauss、JulietCorbin程序化扎根理论方法,采用开放性编码、主轴编码、选择性编码对访谈资料进行编码和分析。结果经开放性编码提取到初始概念482个,基本范畴47个;经主轴编码获得9个主范畴;经选择性编码形成典型关系结构,显示公费医学生职业认同的影响因素由职业认知、职业行为、职业选择、职业意志、职业情感、职业信念6大维度构成。结论公费医学生职业认同的影响因素由职业认知、职业行为、职业选择、职业意志、职业情感、职业信念6大维度构成,其中职业认知、职业行为、职业选择属于外显因素,职业意志、职业信念、职业情感属于内隐因素。

Morphological Characteristics and Nutrient Content of Fine Roots of 2-Year-Old and 3-Year-Old Eucalyptus grandis Plantation

[ Objective] This study aimed to explore the morphological characteristics and nutrient content of f＇me roots of 2-year-old and 3-year-old Euca/yptus grand/s plantation and investigate the correlation. [ Method] Fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation were collected as experimental materials, to determine the root diameter （D）, root length （L）, specific root length （SRL） and contents of major nutrient elements N, P, K, Ca, Mg and C of fine roots （level 1 -5）, study the morphological characteristics and major nutrient element content and investigate the correlation. [ Result] The results showed that morphological differences of fine roots （ level 1 - 5 ） of Eucalyptus grandis plantation were great with the increase of root order, to be specific, D and L increased and SRL decreased with the increasing root order; SRL, L and D of 3-year-old Eucalyptus grauclis plantation were greater than those of 2-year-old Euca/yptus grand/s plantation. Contents of N, Ca, Mg and C of fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation showed consistent orders with the increase of root order： N and Mg contents were reduced, while Ca and C contents were enhanced; P and K contents varied with different forest ages; both 2-year-old and 3-year- old Eucalyptus grandis showed an order of C 〉 K 〉 Ca （Mg） 〉 N. Major nutrient element content and morphological characteristics of Eucalyptus grand/s fine roots （level 1 -5 ） were extremely significantly correlated （P 〈0.01 ）, SRL, L and D could be adopted as reference indices to evaluate nutrient status of Eucalyptus grand/s. Required nutrients and fine root morphology of Eucalyptus grandis plantation changed with the increase of forest age, and the nutrient cycling and energy flow patterns also changed; major nutrient dements in fine roots of 2-year-old and 3-year-old Eucalyptus grandis plantation transferred in a different order from the growth order, therefore N fertilizer could be applied to improve the growth of fine roots. [ Condusion] This study laid the foundation for understanding the fine root morphology and nutrient variation pattern of Eucalyptus grandis plantation and enriching the response and adaptation mechanism theory of roots to environment, pos- sessing important reference significance for the sustainable development of Eucalyptus grand/s plantation.

分级治理:乡村旅游开发中的基层治理秩序再造——基于豫北Y村的田野调查

产业兴旺、生活富裕与治理有序共同构成了乡村振兴的基础。基于豫北的田野调查发现,乡村旅游开发提高了农民的非农就业机会与家庭收入,但也造成了村庄开发的混乱局面,建立在土地之上单一利益主体间的互动转变为多方利益主体的博弈。在新的关系互动模式下,村庄内形成了土地利益分化的差序格局,集体土地分配规则的公共性与权威弱化,基于土地调整、分配的层级治理秩序受到冲击,导致了村级治理的困境。要实现不同利益主体博弈的平衡,必须重新构建发展型村庄的治理体系,即由村一级负责对接村庄发展性任务,承担村庄的土地经营与产业发展,同时落实相应基础设施建设和资源分配,保证村庄内部发展的整体性公平;而组一级负责对接村庄常规性事务,负责对农民的组织和动员,同时参与村庄经济发展的监督与收益分配,保证村庄事务推进的公开透明性,以此通过权力、责任和利益的协调,重构村组之间的利益连带关系,形成村组之间相互嵌入的新层级治理体系与基层治理效力。

界限估计方法在高压配电系统地震易损性分析中的应用研究

配电系统中某一单体设备的抗震性能评估结果难以表征配电系统整体的抗震能力,高压配电系统的抗震安全性评估研究亟需开展。目前,用于结构系统可靠性评估的界限估计方法在土木工程结构领域得到应用和推广,此方法在电力系统抗震性能概率性评估中的应用较少。基于此,文中以某实际工程高压配电系统为例,采用一阶界限估计方法和二阶界限估计方法对配电系统的易损性进行研究。研究结果表明:该配电系统的超限概率大于系统中任一单体设备的超限概率;基于一阶界限估计方法求解的配电系统易损性曲线界限区间较宽,不利于工程的实际应用;基于二阶界限估计方法求解的易损性曲线界限区间窄,但下界对系统中单体设备的超限排列顺序较为敏感,在应用此方法时应特别注意。

A Fourth-order Covergence Newton-type Method

为非线性的方程解决根的一个第四顺序的集中方法，它是牛顿的方法 given.Its 集中性质的变体是 proved.It 是简单的根和一顺序集中附近的至少第四顺序的集中，在多重 roots.In 附近结束，数字测试被给，与另外的已知的牛顿和牛顿类型 methods.The 相比，结果比 others.It 充实方法发现非线性的方程的根。

Do root modules still exist after they die?

Background:The terminal branch orders of plant root systems are increasingly known as an ephemeral module.This concept is crucial to recognize belowground processes.However,it is unknown if root modules still exist after they die?Methods:The decomposition patterns of the first five root orders were observed for 3 years using a branch-order classification,a litter-bag method and sequential sampling in a common subalpine tree species(Picea asperata)of southwestern China.Results:Two root modules were observed during the 3-year incubation.Among the first five branch orders,the first three order roots exhibited temporal patterns of mass loss,nutrients and stoichiometry distinct from their woody mother roots throughout the experimental period.This study,for the first time,reported the decomposition pattern of each individual root order and found a similar decomposition dynamic among ephemeral root branches in a forest tree species.Conclusions:Results from this study suggest that root modules may also exist after death,while more data are needed for confirmation.The findings may further advance our understanding of architecture-associated functional heterogeneity in the fine-root system and also improve our ability to predict belowground processes.

Design and Analysis of Some Third Order Explicit Almost Runge-Kutta Methods

In this paper, we propose two new explicit Almost Runge-Kutta (ARK) methods, ARK3 (a three stage third order method, i.e., s = p = 3) and ARK34 (a four-stage third-order method, i.e., s = 4, p = 3), for the numerical solution of initial value problems (IVPs). The methods are derived through the application of order and stability conditions normally associated with Runge-Kutta methods;the derived methods are further tested for consistency and stability, a necessary requirement for convergence of any numerical scheme;they are shown to satisfy the criteria for both consistency and stability;hence their convergence is guaranteed. Numerical experiments carried out further justified the efficiency of the methods.

计及时变扰动下永磁牵引电机无传感器滑模控制

针对永磁同步牵引电机因参数摄动不确定因素造成控制性能下降以及速度传感器存在成本高、环境要求严格、估计精度不足等问题,提出了一种基于自适应广义高阶平方根容积卡尔曼滤波算法(ASRGHCKF)无速度传感器的永磁同步电机(PMSM)自适应非奇异快速终端滑模控制算法。首先,建立参数摄动下PMSM数学模型;其次,基于扩展滑模扰动观测器(ESMDO)设计自适应非奇异快速终端滑模转速控制算法(ANFTSMC),选择新型指数趋近律可随系统距离滑模面的远近自适应调整趋近速度,同时ESMDO实时精准观测系统的未知扰动部分;最后,结合ASRGHCKF实时精准估计电机的转速和转子位置。通过与PI和传统SMC算法进行仿真和半实物试验对比,验证了该算法在电机参数摄动下暂稳态性能更佳,有利于改善PMSM的无速度传感器控制效果。

增温和氮添加对杉木不同序级细根形态和化学性状的影响

全球气候变暖与氮(N)沉降是两个同时存在的全球变化主要因素,但目前关于二者的研究多以单因子为主。细根形态和化学性状等功能性状在促进植物养分获取和森林生物地球化学循环方面起着关键作用,但目前气候变暖、N沉降以及两者交互对细根形态和化学性状的影响尚不清楚。在福建三明森林生态系统国家野外科学观测研究站陈大观测点开展土壤增温与N添加双因子试验,包括对照(无增温,无氮添加)、低氮(+4gN m^(-2)a^(-1))、高氮(+8gN m^(-2)a^(-1))、增温(+5℃)、增温+低氮(+5℃,+4gN m^(-2)a^(-1))、增温+高氮(+5℃,+8gN m^(-2)a^(-1))六个处理,探讨增温与N添加对杉木(Cunninghamia Lanceolata)细根形态和化学性状的影响。结果表明:(1)增温显著增加了细根直径(D)。增温和N添加的交互作用对细根比根长(SRL)、比表面积(SRA)及组织密度(RTD)均存在显著影响,与对照相比,增温处理及增温+高氮处理均降低了细根SRL和SRA;不同处理间细根RTD无显著差异。N添加与序级交互作用对细根SRA存在显著影响,仅低氮添加显著增加了1级根SRA。(2)增温和N添加交互作用对细根碳(C)含量存在显著影响,与对照相比,仅增温+高氮处理显著增加了细根C含量。N添加与序级交互作用对细根C含量存在显著影响,仅在1级细根中,高氮添加的细根C含量要显著高于低氮添加。增温、N添加以及序级三者交互作用对细根N含量及碳氮比(C∶N)存在显著影响,与对照相比,低氮和高氮处理对细根N含量及C∶N影响因序级而异;增温处理、增温+低氮处理以及增温+高氮处理均显著提高了细根N含量,降低了细根C∶N;与高阶根相比,低阶根N含量和C∶N对单独增温处理及增温+低氮处理响应要更为敏感。以上结果表明,不同细根功能性状对增温、N添加及两者交互的响应存在差异,这种差异主要与细根序级和N添加水平有关;增温和N添加抑制了细根SRL和SRA,但促进了细根N含量并降低了细根C∶N,这将有助于理解亚热带地区森林地下养分循环以及C固存对全球环境变化的响应。