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Background Brood pollination mutualism is a special type of plant-pollinator interaction in which adult insects pollinate plants, and the plants provide breeding sites for the insects as a reward. To manifest such a mutualism between Stellera chamaejasme and flower thrips of Frankliniella intonsa, the study tested the mutualistic association of the thrips life cycle with the plant flowering phenology and determined the pollination effectiveness of adult thrips and their relative contribution to the host’s fitness by experimental pollinator manipulation. Results The adult thrips of F. intonsa, along with some long-tongue Lepidoptera, could serve as efficient pollinators of the host S. chamaejasme. The thrips preferentially foraged half-flowering inflorescences of the plants and oviposited in floral tubes. The floral longevity was 11.8 ± 0.55 (mean ± se) days, which might precisely accommodate the thrips life cycle from spawning to prepupation. The exclusion of adult thrips from foraging flowers led to a significant decrease in the fitness (i.e., seed set) of host plants, with a corresponding reduction in thrips fecundity (i.e., larva no.) in the flowers. Conclusions The thrips of F. intonsa and the host S. chamaejasme mutualistically interact to contribute to each other’s fitness such that the thrips pollinate host plants and, as a reward, the plants provide the insects with brooding sites and food, indicating the coevolution of the thrips life cycle and the reproductive traits (e.g., floral longevity and morphology) of S. chamaejasme.

Yellow River Basin is an important water conservation and ecological barrier area, the study of water supply service in which is of great significance to the high-quality development and ecological environment protection. Based on the Invest InVEST model and the method of scenario analysis, we analyzed the temporal and spatial patterns of water yield in the Yellow River Basin in recent 20 years (1995-2015) with land use and cover, meteorological and soil data as inputs. We examined the impacts of precipitation change and land use change on water yield and their impacts on water yield. The results showed that water yield depth had average growth of 24.34 mm from 1995 to 2015. The high water yield area located in the west and southwest, and the low water yield area located in the northwest. The change of deep spatial pattern was not evident. Among the three grade basins in the Yellow River Basin, the river basin above Longyangxia, with the highest water yield of about 11.7 billion m黄河流域是重要的水源涵养和生态屏障区,研究其水源供给服务对实现黄河流域高质量发展和生态环境保护具有重要意义。本研究基于InVEST模型和情景分析法,以土地利用覆被、气象及土壤等数据作为输入,分析了1995—2015年黄河流域产水量的时空格局以及降水变化和土地利用变化对流域产水量的影响,并探讨产水量对二者的响应。结果表明:1995—2015年,黄河流域产水深度增加,增量为24.34 mm,产水高值区集中在西部和西南部,低值区集中在西北区域,产水深度空间格局特征变化不明显;黄河流域三级流域中,龙羊峡以上流域产水量最高,约117 亿m

Background: Sexual reproduction of plants is likely to be related to climate in their distribution range. Therefore, the investigation of spatial pattern of reproductive traits might provide valuab...

This study aimed to understand the stoichiometric characteristics of carbon (C), nitrogen (N) and phosphorus (P) and soil nutrients in rhizosphere and non-rhizosphere soils and to obtain information on the status of soil and microbial nutrient limitation in degraded alpine meadow. We collected soil samples from rhizosphere (0-2 mm) of dominant plant species and non-rhizosphere (0-10 cm) of the alpine meadow with four different degraded degrees in the Qilian Mountains. We measured the concentration of C, N and P and extractable C, N, P (Ext-C, Ext-N, Ext-P), the activity and proportion of extracellular enzymes (β-1, 4-glucosidase, β-1, 4-N-acetylglucosaminidase, leucine aminopeptidase and acid phosphatase) involved in C, N, P cycles, as well as soil microbial biomass (MBC, MBN, MBP). The results showed that nutrient concentrations in the rhizosphere of dominant species was higher than that in non-rhizosphere. With the increases of degradation degree, soil C:N:P changed significantly, and resulted in a serious imbalance of C:N and severe N limitation. In the degraded alpine meadows, the ratio of log-transformed rhizosphere C-, N- and P-extracellular enzymes deviated from the 1:1:1 of global ecosystem, indicating that nutrient supply was mainly restricted by N and followed by P. The contents of soil total nutrients in degraded alpine meadow was relatively high, but the contents of soil available nutrients were low, which would hinder plant growth.为深入理解高寒草甸退化过程中根际和非根际土壤中碳(C)、氮(N)和磷(P)的化学计量特征和土壤养分的变化规律,并获得退化草地土壤养分和微生物养分限制的信息,本研究以祁连山东缘4个不同退化程度高寒草甸为对象,通过采集优势植物根际土(0~2 mm)和非根际土(0~10 cm)的土壤样品,分析了土壤C、N、P浓度和比例,土壤中可提取的C、N、P(Ext-C、Ext-N、Ext-P)的浓度和比例,参与C、N、P循环的胞外酶(β-1,4-葡萄糖苷酶、N-乙酰-β-D-葡萄糖苷酶、亮氨酸基肽酶、酸性磷酸酶)的活性和比例,以及土壤微生物生物量碳、氮、磷(MBC、MBN、MBP)的含量及比例.结果表明: 高寒草甸退化过程中优势植物根际养分含量高于非根际养分.随着高寒草甸退化程度的加剧,其土壤的C∶N∶P发生重大改变,表现出C∶N的严重失调,表明草地退化程度越高受到N的限制越严重.不同退化程度的高寒草甸中,经过对数转化的根际C-、N-和P-胞外酶的比例均偏离了在全球生态系统分析中获得的1∶1∶1比例,表明高寒草甸退化主要受到强烈的N限制,P次之.高寒草甸地区土壤全量养分含量较高,土壤中的速效养分较低,成为阻碍牧草生长的限制因子.

Livestock grazing affects grassland stability, resilience, and productivity owing to trampling, foraging, and excretion. Over time, trampling influences a wide range of grassland components and can have lasting effects. Trampling helps maintain grassland health but may also cause its degradation. In a field experiment over two growing seasons, we simulated yak and sheep trampling at different intensities and investigated their effects on the reproductive and photosynthetic characteristics of Medicago ruthenica var. inschanica in a Tianzhu alpine meadow in Gansu Province, China. Our results show that simulated trampling inhibited the asexual and sexual reproduction and growth of M. ruthenica. The root surface area, root volume, root biomass, pod length, pod number per unit area, number of seeds per pod, thousand-seed weight, and seed yield were significantly reduced under simulated trampling in the upper 30 cm of soil (P 0.05) but were not reduced in the deeper soil layers ( 30 cm). Light trampling by both yak and Tibetan sheep promoted photosynthesis, while heavy trampling by both species inhibited photosynthesis. Yak trampling inhibited photosynthesis more than Tibetan sheep trampling, and overall, the adverse effects of yak trampling on asexual and sexual reproduction and growth of M. ruthenica were greater than those of Tibetan sheep trampling. Thus, the effect of yak trampling is greater than the effect of trampling by Tibetan sheep, where the different trampling intensities of yak and Tibetan sheep can result in direct but varied influences on grasslands, potentially leading to grassland differentiation.

Currently, the main network security mechanisms (such as firewall, intrusion detection, and vulnerability scanning) cannot prevent malicious attacks absolutely from the public network. Therefore, how to ensure the security of the information in the private network is a hot topic. In this paper, a network physical isolation system is designed based on private protocol, in which internal and external networks are physically isolated during the data transmission. Thereby, the security of network information is protected and the network security problems can be solved effectively through this isolation system. This isolation system can be applied in high security network environment such as government departments and business units, etc.

Off-grid systems are proposed for the power shortage in remote areas. In an off-grid home, electronic devices can result in poor power quality issues. In this paper, two topologies of off-grid systems are presented and compared to chose more suitable one for an off-grid home. One compared topology is a system with inverter and transformer, and another one with the converter and inverter. We compared and examined their corresponding current, voltage waveforms, and the THD values based on the same power source and load by the Matlab/Simulink software. The simulation results show that the system with inverter and transformer is more suitable for off-grid home in remote areas.

The depth variations of soil physicochemical properties in the degraded native grasslands and the artificially restored grasslands were studied in the Three-river headwater areas of Qinghai-Tibetan plateau, China. The results showed: (1) With the increase of the gradient of restoration years, soil water content, total chemical properties, total potassium, phosphorus, available phosphorus and potassium were increased thereafter in the artificial grasslands. (2) With the increase of grassland degradation gradient, soil water content was gradually reduced, and the total N, K, the organic matter didnt gradually reduced also. (3) Both restoration years and degradation degree didnt influence the nutrient distribution in soil. (4) The organic matter, total N and K of degraded grassland were increased by artificial grassland construction. Therefore, artificial grassland construction canbe used as an effective measure of ecological projects in the Three-river headwater area.

According to the field investigation, collecting five kinds of dominant plant from tin ore tailing reservoir of Gejiu and tailing reservoir soil samples by flame atomic absorption spectrometry for the determination of five kinds of dominant plant roots, stems, leaves and its growth soil’s Pb, Zn, Cu and Cd contents, and analyzes five kinds of plant transfer and accumulation coefficient. The results showed that: soil heavy metal pollution is serious, especially Cd pollution; Lactuca indic L、Cattail、Alopecurus aequalis and Cyperus rotundus L. plants of heavy metal contents are the same, all is Zn﹥Cu﹥Pb﹥Cd, but four kinds of heavy metal contents are Pb﹥Zn﹥Cu﹥ Cd in Neyruadia plants; Lactuca indic L、Cyperus rotundus L、Alopecurus aequalis and Cattail to Pb, Zn, Cu and Cd four kinds of heavy metals accumulation ability is weaker. But from the root to the ground part organ transfer ability aspects: four kinds of heavy metal in Lactuca indic L is strong, Pb and Cd two elements in the Cyperus rotundus L is more stronger, Cd in Alopecurus aequalis is more stronger, Zn, Cu and Cd in Cattail is more stronger; the accumulation and transfer coefficient are larger than one, it was a better plant which removes Pb.

Through pot experiment to research the influence of different concentrations of compound heavy metals pollution on Pakchoi, Brassica chinensis and Celery growth status and several physiological and biochemical indexes. The test results showed that: with the increasing of pollution concentration, the maximum leaf area, plant height, fresh weight of the overground part, catalase activity, vitamin C content and free proline content were not uniform in three kinds of vegetables. The Pakchoi plant height and leaf area were increased at first, then decreased in the trend, biomass declined; the maximum leaf area, plant height and overground parts of the fresh weight of celery are tending to decline; the Brassica chinensis except plant height erratic, maximum leaf area and fresh weight of the overground parts showed a gradual downward trend; the Proline content increased compared with the control group, and celery’s proline content increased when compound heavy metals concentration increased, but the proline content declined of Pakchoi and Brassica chinensis in high heavy metals concentrations. The vitamin C content were lower than the control group, and celery’s vitamin C decreased with the compound heavy metals concentration increased, there was significant difference between the treatments, but Pakchoi and Brassica chinensis did not show a strong regularity; catalase activity of Celery and Brassica chinensis is lower than the control, but it is strong in Pakchoi.

The Heisenberg model with Dzyaloshinsky-Moriya interaction (the constant Dzyaloshinsky vector D = Dz, D is a real number) and the growth model (D is a complex number) are investigated in the framework of the quantum inverse scattering method. The Lax pair and the corresponding R matrix satisfying the Yang-Baxter relation are obtained. These models are also solved by means of the algebraic Bethe ansatz. The eigenvalues and the Bethe ansatz equations are derived. [S0163-1829(99)05013-4].

We obtain the Lax pair for the N=3 supersymmetric and SO(3) symmetric extensions of KdV equation by using the prolongation structure technique. Hence its integrability is proved.

The prolongation structure of the N =2 supersymmetric KdV equation with one parameter family is investigated. It is shown to possess the nontrivial Lie superalgebras with central elements of the parameter a =-2, 1 and 4. The Lax pairs associated with the component fields for these three cases are presented.

The static low-energy excitations, their stability and the undistorted-incommensurate phase transition in Slot-Janssen one-dimensional (1D) modulated crystals are studied anew in detail. The exact results are obtained.

The Ising quantum chain with alternating single and sector defects is solved exactly by using the technique of Lieb, Schultz and Mattis. The energy spectrum of this model is shown to have a tower structure if and only if these defects constitute a commensurate configuration. This means that conformal invariance is preserved in such cases.

Taking the main companion species Saussurea superba in an alpine Kobresia humilis meadow on Qinghai-Tibet Plateau as test material, a UV-B exclusion experiment with UV-B excluding and UV-B transmitting filters was performed to study the effects of strong solar UV-B on the photosynthesis, photosynthetic pigments, and UV-B-absorbing compounds of S. superba, aimed to examine the adaptation capability of alpine plants to strong solar UV-B radiation. The removal of UV-B components from natural sunlight increased the net photosynthetic rate (P0.05) and PS II photochemistry efficiency of S. superba. The relatively increased leaf thickness under ambient UV-B could compensate the photo-oxidation of photosynthetic pigments, an inherent characteristic of alpine plants growing in intense UV-B. Short-term removal of UV-B radiation had no obvious effects on the UV-B-absorbing compounds, suggesting that these compounds in epidermal layer of S. superba could hardly be affected by the environment. It was concluded that the increase of photosynthetic pigment contents due to the enhancement of leaf thickness was a specious phenomenon, but the strong solar UV-B radiation on Qinghai-Tibet Plateau still had a potential negative impact on the photo-physiological processes in alpine plant S. superba.

The integrable deformations of the one-dimensional classical Heisenberg model have been investigated by use of the prolongation theory of Wahlquist and Estabrook (1975). The SO(3) invariant deformation and a higher-order isotropic deformation with nonlinearity in the deformation parameters are obtained. The Lax pairs for these integrable spin equations are presented. Finally it is pointed out that these spin equations are equivalent to the generalized nonlinear Schrodinger equations.

The one-dimensional XY model with n arbitrarily placed interfaces is investigated. The energy spectrum is shown to have a tower structure only for a commensurate configuration of the critical parameters. The interfacial critical exponents in such cases are determined from conformal invariance theory. The underlying algebra generating the conformal spectrum is the shifted SO(4c) Kac-Moody algebra, the central charge is 2c, which is exactly two times of that in the Ising model with the same structure of interfaces.

The authors investigate in detail the integrable deformations of the classical Heisenberg model by use of the prolongation theory of Wahlquist and Estabrook (1975). For the first-order deformations, their results coincide with those obtained by Mikhailov and Shabat (1986). For the higher-order deformations, there exist arbitrary N-order isotropic integrable deformations, but the anisotropic integrable deformations, are not found. Finally it is pointed out that these higher-order isotropic deformed Heisenberg spin equations are equivalent to the generalised nonlinear Schrodinger equations.

OBJECTIVE To investigate the effects of Tongluo Recipe (TLR), a compound Chinese herbal medicine, on experimental diabetic peripheral neuropathy in rats. METHODS Diabetes was induced by streptozocin in rats. Eight weeks later, the diabetic rats were assigned to 3 groups according to different body weights: untreated group, low-dose TLR-treated group and high-dose TLR-treated group. Eight normal rats were assigned to normal control group. Systemic and sciatic nerve intrinsic antioxidant enzyme activities, lipid peroxide levels, hemorheology and sciatic nerve conduction velocity and ultrastructure changes were evaluated. RESULTS Glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were lower, and lipid peroxide levels were higher in plasma and sciatic nerve of the untreated group than those in the normal control group (P

We investigate in detail the integrability of fermionic extensions of the Korteweg-de Vries equation by using the prolongation structure method. The integrable one- and two-parameter systems are obtained. The previously known integrable systems are their special cases.

Using the prolongation structure technique, we investigate the fermionic extensions of the Burgers equation suggested by Hlavaty. Besides those which pass the Painleve test, some new integrable cases are found. Through the representations of the Lie superalgebras, the Lax pairs for these integrable cases are constructed.

The integrability of the new Painleve admissible fermionic extension of the KdV equation suggested by Hlavaty is proved by the use of the super prolongation structure technique. It possesses an eight-dimensional Lie superalgebra. The Lax equations associated with this system are obtained.

The deformed anisotropic Heisenberg model suggested by Mikhailov and Shabat is discussed from the viewpoint of prolongation theory. The Lax pair associated with this equation is derived.