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1. chinaXiv:202006.00241 [pdf]

Responses of leaf water potential and gas exchange to the precipitation manipulation in two shrubs on the Chinese Loess Plateau

LI Yangyang; CHEN Jiacun; AI Shaoshui; SHI Hui
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Regulation of leaf gas exchange plays an important role in the survival of trees and shrubs under future climate change. However, the responses of leaf water potential and gas exchange of shrubs in semi-arid areas to the precipitation alteration are not clear. Here, we conducted a manipulated experiment with three levels of precipitation, i.e., a control with ambient precipitation, 50% above ambient precipitation (irrigation treatment), and 50% below ambient precipitation (drought treatment), with two common shrubs, Salix psammophila C. Wang & C. Y. Yang (isohydric plant, maintaining a constant leaf water potential by stomatal regulation) and Caragana korshinskii Kom. (anisohydric plant, having more variable leaf water potential), on the Chinese Loess Plateau in 2014 and 2015. We measured the seasonal variations of predawn and midday leaf water potential (?pd and ?md), two parameters of gas exchange, i.e., light-saturated assimilation (An) and stomatal conductance (gs), and other foliar and canopy traits. The isohydric S. psammophila had a similar An and a higher gs than the anisohydric C. korshinskii under drought treatment in 2015, inconsistent with the view that photosynthetic capacity of anisohydric plants is higher than isohydric plants under severe drought. The two shrubs differently responded to precipitation manipulation. ?pd, An and gs were higher under irrigation treatment than control for S. psammophila, and these three variables and ?md were significantly higher under irrigation treatment and lower under drought treatment than control for C. korshinskii. Leaf water potential and gas exchange responded to manipulated precipitation more strongly for C. korshinskii than for S. psammophila. However, precipitation manipulation did not alter the sensitivity of leaf gas exchange to vapor-pressure deficit and soil moisture in these two shrubs. Acclimation to long-term changes in soil moisture in these two shrubs was primarily attributed to the changes in leaf or canopy structure rather than leaf gas exchange. These findings will be useful for modeling canopy water-carbon exchange and elucidating the adaptive strategies of these two shrubs to future changes in precipitation.

submitted time 2020-06-22 From cooperative journals:《Journal of Arid Land》 Hits102Downloads48 Comment 0

2. chinaXiv:202006.00200 [pdf]

关于手性问题的讨论.pdf

史志强
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

本文是对《中国科学》一个编者按的商榷和讨论。文章指出手性是手性对称性的破缺,并举例说明了手性对称性和手性的本质区别。手性化合物的一对对映体有不同的生物活性和药物活性,这决不是个别极端的例子,而是非常普遍存在的。生物体内参与蛋白质组成的氨基酸是手性的,但它们既不全都是左旋的,也不全都是右旋的,只能说它们全部都是L构型的。蛋白质的结构是复杂的,我们不能笼统地说蛋白质是右旋的,只能说蛋白质二级结构中的α-螺旋结构是右旋的。最后,我们分析了对手性定义的几种错误表述,并指出产生这些错误的原因。

submitted time 2020-06-17 Hits184Downloads106 Comment 0

3. chinaXiv:201607.00046 [pdf]

Exact Solution for Three-Dimensional Ising Model

Zhang, Degang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Three-dimensional Ising model in zero external field is exactly solved by operator algebras, similar to the Onsager's approach in two dimensions. The partition function of the simple cubic crystal imposed by the periodic boundary condition along both $(0 1 0)$ and $(0 0 1)$ directions and the screw boundary condition along the $(1 0 0)$ direction is calculated rigorously. In the thermodynamic limit an integral replaces a sum in the formula of the partition function. A order-disorder transition in the infinite crystal occurs at a temperature $T=T_c$ determined by the condition: $\sinh\frac{2J}{k_BT_c}\sinh\frac{2(J_1+J_2)}{k_BT_c}=1$, where $(J_1 J_2 J)$ are the interaction energies in three directions, respectively. The analytical expressions for the internal energy and the specific heat are also given. It is also shown that the thermodynamic properties of 3D Ising model with $J_1=J_2$ are connected to those in 2D Ising model with the interaction energies $(J_1 J_{2D})$ by the relation $(\frac{J_{2D}}{k_BT})^*=(\frac{J}{k_BT})^*-\frac{J_1}{k_BT}$, where $x^*=\frac{1}{2}{\rm ln coth} x={\rm tanh}^{-1}(e^{-2x})$.

submitted time 2020-05-12 Hits16230Downloads1881 Comment 0

4. chinaXiv:202001.00062 [pdf]

基于环境示踪剂氯的北山地区浅部地下水补给研究

李杰彪; 苏锐; 周志超; 郭永海; 季瑞利; 张明; 王洪斌
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

地下水补给研究是高放废物深地质处置库选址和场址评价的重要研究内容之一。甘肃北山地区是我国高放废物地质处置库场址首选预选区,为查明该区地下水补给特征,基于环境示踪剂氯查明了北山地区浅部地下水补给量。结果表明:(1) 总体而言,氯质量平衡方法在北山地区应用效果较好。(2) 基于包气带的氯质量平衡方法计算得出的浅部地下水垂向补给量在渗透性较大的沟谷盆地中为0.07~2.03 mm·a-1,平均值约1.0 mm·a-1。(3) 基于饱和带的氯质量平衡方法计算得出北山地区浅部地下水多年平均入渗补给量为0.25 mm·a-1,不足多年平均降水量的0.5%。相关结果可为我国高放废物地质处置库选址和场址评价提供依据。

submitted time 2020-01-06 From cooperative journals:《干旱区地理》 Hits6964Downloads446 Comment 0

5. chinaXiv:201910.00053 [pdf]

Effects of biochar on water movement characteristics in sandy soil under drip irrigation

PU Shenghai; LI Guangyong1; TANG Guangmu; ZHANG Yunshu ; XU Wanli; LI Pan; FENG Guangping; DING Feng
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Biochar addition can improve the physical and hydraulic characteristics of sandy soil. This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation. By indoor simulation experiments, the effects of biochar application at five levels (0%, 1%, 2%, 4% and 6%) on the soil water retention curve, infiltration characteristics of drip irrigation and water distribution were tested and analyzed. The results showed that biochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water. Within the same infiltration time, with an increasing amount of added biochar, the diffusion distance of the horizontal wetting front (HWF) tended to decrease, while the infiltration distance of vertical wetting front (VWF) initially declined and then rose. The features of wetted bodies changed from "broad-shallow" to "narrow-deep" type. The relationship between the transport distances of HWF and VWF and the infiltration time was described by a power function. At the same distance from the point source, the larger the amount of added biochar, the higher the soil water content. Biochar had a great influence on the water content of the layer with biochar (0–200 mm) and had some effects at 200–250 mm without biochar; but it had less influence on the soil water content deeper than 250 mm. For the application rate of biochar of 4%, most water was retained within 0–250 mm soil layer. However, when biochar application amount was high (6%), it would be helpful for water infiltration. During the improvement of sandy soil, biochar application rate of 4% in the plow layer had the best effect.

submitted time 2019-10-26 From cooperative journals:《Journal of Arid Land》 Hits9254Downloads626 Comment 0

6. chinaXiv:201910.00072 [pdf]

不确定性(原理)关系的证伪

段德龙
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

为解决量子力学物理诠释的根本分歧,证明爱因斯坦对于量子力学的预测本文对海森堡不确定性(原理)关系式的数学形式进行概率分析;从个体基元过程的角度对海森堡与玻尔的电子单狭缝位置测定思想实验和爱因斯坦光子箱思想实验进行了重新检视。在数学上通过对概率分布及全概率空间的分析得到了不确定性关系被破坏的结果;对海森堡与玻尔的电子单狭缝位置测定思想实验和爱因斯坦光子箱思想实验进行的重新检视,获得了玻尔与海森堡原有论证不成立的结论。因篇幅所限未就纠缠作进一步的分析。在演绎(数学上的概率分析)与归纳(物理上的思想实验)两个方面,本文都获得了海森堡不确定性关系不成立的结果,证明了量子力学正统诠释难以保持其理论的自洽与逻辑一贯性

submitted time 2019-10-21 Hits8670Downloads735 Comment 0

7. chinaXiv:201909.00120 [pdf]

西宁盆地4种草本和灌木植物降盐效应试验研究

李淑霞; 刘亚斌; 钟鹏; 余冬梅; 胡夏嵩; 杨幼清
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

以西宁盆地长岭沟流域自建试验区为研究区,筛选出适宜当地气候条件下生长的2种灌木植物柠条锦鸡儿(Caragana korshinskii Kom.)、霸王〔Zygophyllum xanthoxylon (Bunge) Maxim.〕和2种草本植物细茎冰草(Agropyron trachycaulum cv. Slender)、紫花苜蓿(Medicago sativa Linn.)作为试验供试种,在试验区对4种植物采用单一种植和组合种植方式,探讨2种种植条件下植物根系在边坡地表以下垂直方向土体中K+、Ca2+、Na+、Mg2+、SO42-、Cl-、HCO3-、CO32-等8种易溶盐离子含量及其变化特征,评价了区内2种草本和2种灌木植物降低边坡土体盐分的能力。结果表明:单一种植细茎冰草、紫花苜蓿、柠条锦鸡儿、霸王对边坡土体中SO42-、Ca2+、Na+具有显著降低作用,草本与灌木组合Ⅰ(柠条锦鸡儿+紫花苜蓿+细茎冰草组合)和草本与灌木组合Ⅱ(霸王+紫花苜蓿+细茎冰草组合)对边坡土体中SO42、Ca2+、Mg2+、K+、Na+表现出显著降低作用;紫花苜蓿的降盐效果相对较为显著、其次为柠条锦鸡儿和细茎冰草,霸王的降盐效果不及前者显著;草本与灌木组合Ⅱ的降盐效果相对显著于草本与灌木组合Ⅰ。

submitted time 2019-09-09 From cooperative journals:《干旱区研究》 Hits10173Downloads523 Comment 0

8. chinaXiv:201907.00026 [pdf]

Exact Solution of Quantum Rabi Model

Degang Zhang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Quantum Rabi model is exactly solved by employing the parameter-dependent unitary transformation method in the Bargmann space. The complete energy spectrum consists of two double-fold sub-energy spectra. The eigenvalue is determined by the parameter in the unitary transformation, which satisfies a highly nonlinear equation. Such the energy spectrum completely coincides with that obtained in the occupation number representation [D. Zhang, chinaXiv:201708.00168].

submitted time 2019-07-31 Hits9604Downloads644 Comment 0

9. chinaXiv:201905.00054 [pdf]

多体多自由度量子隐形传态的张量表示

征夏明
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

[目的] 找到一种最普遍情况下量子隐形传态的一般表示及代数结构。 [方法] 归纳推理与演绎推理,利用多项式相乘与张量积之间的等价性发现一般规律。 [结果] 将多体单自由度或单体多自由度的量子隐形传态推广至多体多自由度,以及混合态。 [局限] 无法推广至连续谱量子态。 [结论] 预言多体多自由度单次量子隐形传态的存在,并包含了已被实验证实的所有特殊情况。

submitted time 2019-04-11 Hits12303Downloads668 Comment 0

10. chinaXiv:201905.00053 [pdf]

纠缠态判据与高阶张量可分性的充分必要条件

征夏明
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

[目的] 找到高阶张量和纯态可写成多个低阶张量乘积的充要条件。 [方法] 类比推理、归纳推理,从多元函数可分离变量的充要条件出发,利用与矩阵的代数余子式的性质,最后得到一般的结论。 [结果] 证明定理及其多个等价形式。 [局限] 不适用于混合态。 [结论] 纯态是否是纠缠态的充要条件。

submitted time 2019-04-11 Hits11932Downloads544 Comment 0

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