Change Point Analysis to Detect the Effect of Pruning Severity on Tree Growth

The effect of pruning severity on tree growth was analyzed by change point detection using segmented regression. The present study applied this analysis to a well-known published data set including diameter growth response, tree age, pruning severity and pretreatment crown size. First, multiple regression analysis was performed to assess the effect of tree age, pruning severity and pretreatment crown size on diameter growth response. Next, segmented regression analysis was performed to assess the effect of pruning severity on diameter growth response. The results of the multiple regression showed that diameter growth response was significantly influenced by pruning severity and pretreatment crown size. The results of the segmented regression showed that in the whole data set, an abrupt change toward a decrease in diameter growth response was detected at 25% of the live crown removed. However, in the group of fully crowned and open-grown, diameter growth response continuously decreased with increasing pruning severity with no significant abrupt change, whereas in the group of 70% - 90% live crown, diameter growth response did not significantly decrease up to the break point (53% crown removed) and then abruptly decreased. This may be the first study to show the numerical evaluation of the effect of pruning severity on tree growth by change point analysis.

Enhanced stability and rate performance of zinc-doped cobalt hexacyanoferrate (CoZnHCF) by the limited crystal growth and reduced distortion

Cobalt hexacyanoferrate (CoHCF) is a potential cathode for aqueous Na-ion batteries due to its high theoretical specific capacity (170 m Ah g^(-1));however,its lower rate capability and cyclability limit its applications.Structural distortion at a weak N-coordinated crystal field during cycling disintegrates Co,yielding an irreversible reaction.Different Zn amounts ranging 0–1 were added to the Co site to suppress the structural irreversibility of CoHCF,yielding Co_(1-x)Zn_(x)HCF powder;this Zn (x≤0.09) addition reduced the powder’s dimension because the lower four coordination of Zn–N,not the six coordination of Co–N,limits the powder growth.Simultaneously,a small lattice parameter and interaxial angle (~90°) are obtained,implying that a narrower Co_(1-x)Zn_(x)HCF inner structure is formed to accommodate Na ions.Moreover,the electronic conductivity of Co_(1-x)Zn_(x)HCF gradually increased within 0–0.09 range.A smaller particle size with a high surface area leads to a near-surface-limited redox process,similar to a capacitive reaction.Both the surface-limited reaction and electronic conductivity enhances the reversibility due to the smaller charge transfer resistance at the electrode/electrolyte interface caused by Zn addition.Replacing redox-active Co with non-active Zn amount of 0.07 (Co_(1-x)Zn_(x)HCF) slightly reduces the specific capacity from 127 to 119 mAh g^(-1)at 0.1 A g^(-1)due to the shrunken Co charging sites.Rate performance is enhanced by compromising the capacity and reduced distortion,resulting in 81%retention at a 20-times-faster charging rate.Notably,the Co_(1-x)Zn_(x)HCF sample exhibited the good stability while preserving 74%of the initial capacity at 0.5 A g^(-1)after 200 cycles.

Phosphate limitation of phytoplankton growth in the Changjiang Estuary

Laboratory experiments of bioassay with Pltaeodaetytum tricornutum, Chatoceros didymus, Chaetoreros calcitraus and Heterogtoea sp. sampled from the Changjiang Estuary in spring and summer, 1986, indicated that both N and P limit phytoplankton growth in the medium with N : P ranged between 8-30, and N limits phytoplankton production in the medium with N: P<8, while P is the limitary nutrient in the N : P>30. Generally, N : P in the Changjiang Estuary waters is 2 times higher than Redfield ratio. The bioassay experiments with high N : P water samples collected from Changjiang Estuary show that phytoplankton production is limited by P. Phytopiankton appears to give priority to the uptake of P at all periods of time. And the optimum N:P for phytoplankton growth is determined to be 18.

Infinitely many solutions of p-Laplacian equations with limit subcritical growth

We discussed a class of p-Laplacian boundary problems on a bounded smooth domain, the nonlinearity is odd symmetric and limit subcritical growing at infinite. A sequence of critical values of the variational functional was constructed after the general- ized Palais-Smale condition was verified. We obtain that the problem possesses infinitely many solutions and corresponding energy levels of the functional pass to positive infinite. The result is a generalization of a similar problem in the case of subcritical.

A model for wave growth in fetch-limited conditions

In this paper, it is held that the universal relationships of wave growth in fetch-limited conditions , i. e., (f|~) p=A(x|~)-Band (m|~)0= C(x|~) Dshould satisfy the Toba 3/2 power law and the wave energy balance equation. In the ideal generation situation, theoretically it can be derived that the ideal fetch-limited wave growth relationship should have D=3B and D+B =1, (i.e., B = 0.25, D = 0.75 ) and A3C=2. 1×l(T4C^(1/2)_d , where Cd is the drag coefficient. The 3/2 power law, the wave energy balance equation and the decrease of wave steepness with increasing fetch have became three requirements which should be satisfied by fetch-limited wave growth algorithms. A semi-empirical and semi-theoretical model for fetch-limited wave growth is presented. In the application to the slanting wind situation an un(?)ersal relationship of dimensionless wave energy vs dimensionless peak frequency is presented and the comparisons show that the model is in good agreement with observations.

Economic Growth:Theoretical Arguments about Resources,Environment and the Limit Issue & the Choices Faced by the Human Being

The relationship between man and nature seems highly diverse during the evolving process of human society.Numerous destructive consequences incurring from the early stage of the industrialization led to man’s severe concern aboutecological and environment issues. In 1972, a book entitled "The Limits To Growth " ushered in a worldwide argumentationcampaign, and forced man to realize that the bearing capacity of ecological surroundings is finite, and the quantity of resourcesis numbered as well. Admittedly, the human advance in science and technology, from the long-term viewpoint, is capable ofdiscovering new types of energy and resources. However, each specific period of human history is always endangered due tothe crisis of energy and resources. Therefore the core of the retainable development lies in variation of the outdated pattern ofeconomic growth as well as pursuit to the new substitutes.

Non-Local Analysis of Forming Limits of Ductile Material Considering Void Growth

The current study performed a finite element analysis of the strain localization behavior of a voided ductile material using a non-local plasticity formulation in which the yield strength depends on both an equivalent plastic strain measurement (hardening parameter) and Laplacian equivalent. The introduction of gradient terms to the yield function was found to play an important role in simulating the strain localization behavior of the voided ductile material. The effect of the mesh size and characteristic length on the strain localization were also investigated. An FEM simulation based on the proposed non-local plasticity revealed that the load-strain curves of the voided ductile material subjected to plane strain tension converged to one curve, regardless of the mesh size. In addition, the results using non-local plasticity also exhibited that the dependence of the deformation behavior of the material on the mesh size was much less sensitive than that with classical local plasticity and could be succe

基尼系数测度贫富差距的一种改进方法

基尼系数是测度贫富差距的重要指标,但是洛伦兹曲线的构造使得基尼系数存在结构性局限,即代表着不同的贫富差距情况的两条洛伦兹曲线可能对应着同一个基尼系数,仅凭基尼系数无法反映贫富差距的结构特征。文章提出将洛伦兹曲线上切线斜率为1的点叫做平均增长点,每条洛伦兹曲线有且仅有一个平均增长点,洛伦兹曲线切线斜率具有单调性,可以通过引入平均增长点,与基尼系数共同测度贫富差距,突破单纯依靠基尼系数测度贫富差距的结构性局限。

三江源区高寒草原退化对不同生长期土壤真菌群落的影响

土壤真菌群落在草地生态系统物质循环过程中扮演着重要角色,但草地退化对不同生长期土壤真菌群落的影响尚不清楚。本研究以三江源高寒草原为研究对象,通过野外调查和高通量测序技术,探究草原退化对植物不同生长期土壤真菌群落特征的影响及其驱动因素。结果表明,三江源区高寒草原不同生长期土壤真菌群落优势菌门均为子囊菌门和担子菌门,草原退化显著降低了优势菌门的相对丰度;在不同生长期土壤真菌群落多样性存在显著差异(P<0.05),表现为生长季初期较低,末期则较高;草原退化对土壤真菌群落多样性影响不显著(P>0.05),但显著改变了不同生长期内土壤真菌群落结构(P<0.05);相比于原生草原,退化草原土壤真菌群落结构与植物群落特征表现出更强的相关关系,植物群落生物量和土壤有机质含量是显著影响退化草原土壤真菌群落结构的主要因子(P<0.05)。研究结果表明,草原退化改变了土壤真菌群落结构,增强了土壤真菌群落的资源限制。因此,针对植被群落的修复将有利于退化高寒草原土壤真菌群落的恢复。

不同产地甜瓜植物生长调节剂残留分析和膳食风险评估

为明确不同产地甜瓜植物生长调节剂残留状况,探明其残留风险。该研究以2020年广西,海南、河北、辽宁、江苏、吉林132份甜瓜样品为研究对象,参照DB65/T 3970-2017《蔬菜和水果中17种植物生长调节剂残留量的测定液相色谱-串联质谱法》开展了样品中6种植物生长调节剂残留水平的定量分析,比较了不同产地甜瓜植物生长调节剂残留差异,进而开展了各产区残留植物生长调节剂的急、慢性膳食摄入风险评估和风险排序。甜瓜样品中残留5种植物生长调节剂,其中脱落酸残留样品占比最高为72.13%,其次是多效唑、矮壮素、氯吡脲、烯效唑,残留样品占比分别为11.48%、9.29%、4.37%、2.73%。残留的5种植物生长调节剂,其慢性膳食摄入风险在0%~0.1197%,平均值为0.0152%;急性膳食摄入风险在0%~9.7141%,平均值为0.6692%,均远低于100%,处于安全水平。风险排序得分,无高风险植物生长调节剂,且不同产地残留样品风险得分不同。综合残留样品占比、急、慢性膳食风险评估及风险得分来看,eMRL建议制定修订多效唑、矮壮素、烯效唑的最大残留限量值分别为9、4、1 mg/kg,且脱落酸和多效唑的残留风险相对较高,建议加强关注。

蔬菜水果中植物生长调节剂分析方法研究

植物生长调节剂在现代农业生产中对植物生长有着极其重要的作用,可影响和调控植物的生长和发育,为有效调节作物产量、改善品质,达到稳产增产,植物生长调节剂在农业生产中必不可少。近年来,蔬菜水果生产中滥用植物生长调节剂的现象比较严重,相关食品安全问题广受关注,相关检测方法层出不穷。本文对蔬菜水果中多种常见植物生长调节剂的前处理技术、分析检测技术以及相应的限量要求进行了综述。

EFFECT OF NITROGEN AND PHOSPHORUS ON THE GROWTH OF A RED TIDE DINOFLAGELLATE SCRIPPSIELLA TROCHOIDEA (STEIN) LOEBLICH III

Scrippsiella trochoidea (Stein) Loeblich III was grown in a nitrogen or phosphorus limited batch culture system in laboratory. Growth rates and cellular Chl a were measured as functions of nitrate and phosphate concentrations. Growth rates were hyperbolic with both nitrate and phosphate concentration and fit the Monod equation. The minimum cell quota of nitrogen and phosphorus and then the optimum N:P ratio of S. trochoidea were estimated in this study. Measurement of phosphate concentration in Jiaozhou Bay suggest that phosphorus is the limiting factor of S. trochoidea growth.

Effects of soil nitrate:ammonium ratio on plant carbon:nitrogen ratio and growth rate of Artemisia sphaerocephala seedlings

Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.

Evaluation of nutrient limitation in aquatic ecosystems with nitrogen fixing bacteria

There has always been a great need for simple and accurate bioassays for evaluating nutrient limitation in aquatic ecosystems. Whereas organic carbon is usually considered to be the limiting nutrient for microbial growth in many aquatic ecosystems, there are, however, many water sources that are limited by phosphorus or nitrogen. A method named ＂nitrogen fixing bacterial growth potential＂ （NFBGP） test, which is based on pre-culturing of autochthonous （target） microorganisms was described. The method was applied to evaluate phosphorus or nitrogen nutrient limitation in lake and sewage water samples using an isolate of the nitrogen fixing bacterium, Azorhizobium sp. WS6. The results corresponded well to those from the traditional algal growth potential （AGP） test and the bacterial regrowth potential （BRP） test, suggesting that the NFBGP test is a useful supplementary method for evaluating the limiting nutrient, especially phosphorus, in an aquatic environment.

Crack growth time dependence analysis of granite under compressive-shear stresses state

The curves of crack relative length lib and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-torsion constant displacement load relaxa- tion method.The relations between crack relative length and the crack growth time were discussed under different stresses and different crack lengths.The results show that there is a turning point on curve of crack relative length//b and crack growth time of granite.The slope of curve is small when crack relative length is less than the vertical coordinate of the point,and crack grows stably in this case.Cracks grow,encounter and integrate catastro- phically when crack relative length is more than the vertical coordinate of the point,and there is not a gradual stage from crack stability growth to crack instability growth,i.e.rock mass instability is sudden.The curves of crack relative length lib and crack growth time t of granite move to right with decrease of stress σ_1 or crack length a,which implies that limit time increases consequently.The results correspond to practicality.

低蛋白日粮添加限制性氨基酸对肉鸡生产性能的影响

文章旨在研究低蛋白低豆粕日粮添加限制性氨基酸对肉鸡生产性能的影响。试验一,将160只22日龄AA肉鸡随机分为4组,每组4个重复,每个重复10只鸡,对照组、试验Ⅰ、Ⅱ、Ⅲ组日粮粗蛋白质水平分别为20%、19%、18%和17%,各试验组添加不同比例赖氨酸、蛋氨酸、苏氨酸、缬氨酸等限制性氨基酸;试验二,将144只22日龄AA肉鸡随机分为9组,每组2个重复,每个重复8只鸡,将粗蛋白质为17%的日粮中赖氨酸、蛋氨酸、苏氨酸、缬氨酸添加量在原有基础上分别提高10%、20%和30%,做正交试验,试验为期21 d。结果表明:试验I、Ⅱ组42日龄终重、平均日采食量及平均日增重与对照组差异不显著(P>0.05);试验Ⅲ组的终重、平均日采食量与对照组差异显著(P<0.05);试验Ⅲ组的平均日增重与对照组、试验Ⅰ、Ⅱ组差异显著(P<0.05)。把粗蛋白质为17%的肉鸡日粮中赖氨酸、DL-蛋氨酸、苏氨酸和缬氨酸的添加量分别提高30%、30%、10%和20%,肉鸡生长性能能达到粗蛋白质为20%的日粮水平。由此可见,在肉鸡低蛋白低豆粕减量替代日粮中添加限制性氨基酸能降低日粮粗蛋白质水平;22~42日龄肉鸡日粮中赖氨酸、蛋氨酸、苏氨酸和缬氨酸4种限制性氨基酸添加量分别为1.25%、0.44%、0.34%和0.30%时,肉鸡日粮粗蛋白质水平可以降低3%而不影响其生长性能。

劳动分工与经济增长极限模型分析

根据学习曲线与遗忘曲线原理,分别构建出生产的渐佳函数和遗忘函数并推导出分工与产能关系的数学模型。提出三个假设命题并利用模型辨析真伪,结论证明:劳动分工能有效提升整个社会的生产能力,且不同的分工方式提升效果也不同;分工亦会增加生产成本,当分工成本等于分工收益即产能增量时,经济增长达到极限,整个社会的分工程度达到最佳状态。据此结论进行相关案例分析,并对社会生产提出建议。

涨跌幅限制对我国股市波动性的影响研究

基于2020年8月24日创业板的涨跌幅限制由10%提高到20%这一政策变化,文章采用GARCH模型对上证板块、创业板和港股板块分行业进行波动性研究,以此来探索不同涨跌幅制度下我国各股票市场波动性的变化情况。研究结果表明:对于原材料、工业等支柱型行业,创业板的波动性均小于上证板块,对于日常消费品、医疗保健、通讯服务和信息技术等行业,创业板的波动性大于上证板块。对港股板块的波动性分析可以看出,信息技术和工业等在港股板块占比较大的行业在港股板块的波动性在三个板块中最大,而原材料、日常消费品等行业的波动性在三个板块中最小。对于整个市场来说,放宽涨跌幅限制后创业板的波动性小于上证板块的波动性,上证板块的波动性小于港股板块的波动性,这表明适当的涨跌幅限制可以有效降低股市的波动性,本文对这一结论进行分析并给出相关政策建议。

植物生长调节剂在果蔬中的应用与安全性分析研究进展

植物生长调节剂可有效提高果蔬产量、品质,其在果蔬生产中的应用越来越多;对植物生长调节剂残留危害风险的评估也成为了研究热点。本文综述了植物生长调节剂的主要类别、作用和在果蔬中的应用现状;并归纳分析了果蔬中多效唑、氯吡脲、赤霉酸、乙烯利、2,4-二氯苯氧乙酸(2,4-D)等几种主要生长调节剂的危害和残留现状;发现果蔬中乙烯利的平均残留量最高,葡萄、豆芽、草莓等果蔬中植物生长调节剂残留情况最为严重,其潜在的安全隐患应引起重视;而国家现行植物生长调节剂标准中并未覆盖一些果蔬,亟需完善植物生长调节剂残留相关标准及风险评估。