Time filter

Source Type

Xu M.,China Agricultural University | Li P.,Graduate University of China Academy of Science | Xie F.,Agricultural University of Hebei | Huang D.,China Agricultural University | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

In order to assess variability of soil organic carbon(SOC) across different land-use types and management practices in agro-pastoral zone, two land-use types, permanent grassland and reclaimed cropland in Guyuan County, Hebei province of Northern China, were investigated with SOC density in 0-10, 10-20, 20-30, 30-40, 40-50 cm soil layers and correlations of SOC density with soil bulk density and SOC content as affected by land-use types and management practices change. The results showed that the carbon stored in soils for different land-use types and management practices ranged from 8.21-11.30 kg/m2. The SOC all declined at each successive increment from 0-50 cm depth across the five land-use types and management practices, with the relative distribution greatly skewed towards the top layers. SOC in 0-50 cm soil layers of permanent grassland under different management practices were higher than those in disturbed soils of reclaimed cropland (RC) and fallowing (FC). For permanent grassland, the management practice of GM has the the highest SOC density in 0-50 cm soil layer, the least SOC density was displayed by FG. For reclaimed grassland, after about 10 years FC, SOC were higher signifcantly in the 0-50 cm soil layer comparing to RC. The results also indicated that land-use types and mangement practices had significantly effect on soil bulk density and SOC content, then on SOC density. GM or grassland enclosure and under controlled grazing therefore was the most feasible and benign short-term grassland management option which could deposit even higher carbon dioxide in agro-pastoral ecotone, Northern China.


Li H.,Graduate University of China Academy of Science | Li H.,CAS Institute of Engineering Thermophysics | Yang K.,CAS Institute of Engineering Thermophysics | Xu J.,CAS Institute of Engineering Thermophysics
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2010

Three-dimensional numerical simulations of wall effect were performed for an S809 airfoil model mounted in a wind tunnel. Two turbulent models, Spalart-Allmaras and k-ε(Shear-Stress Transport), were used in the simulations. The results show that simulation agree well with the experimental data. It also turns out that the effect of wall boundary layer on the flow pattern over the airfoil model surface is significant and the strong three-dimensionality wall effect is introduced when the angles of attack of flow are relatively large.


Zhao H.,Graduate University of China Academy of science | Wu L.,Graduate University of China Academy of science | Chai T.,Graduate University of China Academy of science | Zhang Y.,China University of Mining and Technology | And 2 more authors.
Journal of Plant Physiology | Year: 2012

Synchrotron radiation X-ray fluorescence (SRXRF) and inductively coupled plasma mass spectrometry were used to estimate major, minor and trace elements in Cu-, Zn- and Mn-treated Phytolacca americana. The effects of the addition of Cu, Zn and Mn on morphological parameters, such as root length, shoot height, and fresh and dry weights of shoots and roots, were also examined. In addition, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT) and the expression of Fe-SOD, Cu/Zn-SOD, metallothionein-2 and glutathione S-transferase (GST) exposed to the highest amounts of Cu, Zn or Mn were detected. Our results confirmed the following: (1) Zn supplementation leads to chlorosis, disturbed elemental homeostasis and decreased concentrations of micro- and macroelements such as Fe, Mg, Mn, Ca and K. Cu competed with Fe, Mn and Zn uptake in plants supplemented with 25 μM Cu. However, no antagonistic interactions took place between Cu, Zn, Mn and Fe uptake in plants supplemented with 100 μM Cu. Mn supplementation at various concentrations had no negative effects on elemental deficits. Mn was co-located with high concentrations of Fe and Zn in mature leaves and the concentrations of macro elements were unchanged. (2) P. americana supplemented with increased concentrations of Zn and Cu exhibited lower biomass production and reduced plant growth. (3) When plants were supplemented with the highest Zn and Cu concentrations, symptoms of toxicity corresponded to decreased SOD or CAT activities and increased APX and GPX activities. However, Mn tolerance corresponded to increased SOD and CAT activities and decreased POD and APX activities. Our study revealed that heavy metals partially exert toxicity by disturbing the nutrient balance and modifying enzyme activities that induce damage in plants. However, P. americana has evolved hyper accumulating mechanisms to maintain elemental balance and redox homeostasis under excess Mn. © 2012 Elsevier GmbH.


Song X.,CAS South China Sea Institute of Oceanography | Liu H.,CAS South China Sea Institute of Oceanography | Liu H.,Graduate University of China Academy of science | Huang L.,CAS South China Sea Institute of Oceanography | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

Both primary production (PP) and bacterial production (BP) are key basic biological productions in marine ecosystems. In this study, the basic biological productions in different zones in the northern South China Sea were investigated in summer in 2008, in order to evaluate the spatial distribution characteristics of the basic biological productions, their influencing factors and their contributions to the carbon flux in the ecosystems of the South China Sea. The investigation covered the estuarine and Yuedong coastal area, the adjacent area of Taiwan Strait and Luzon Strait, the southeast waters of Hainan Island, and the open waters in the northern South China Sea. The results showed that the surface PP (C) and the integrated PP in the euphotic zone (IPP) (C) were (0.83 ±1. 15) mg m -3h -1 and (225. 39 ± 136. 64) mg m -2d -1 respectively; the average surface bacterial production (C) and the integrated bacterial production (IBP) (C) in the euphotic zone were (0. 14 ±0. 19) mg m -3 h -1 and (128. 14 ±74. 86) mg m -2 d -1 respectively. The basic biological production generally declined from the nearshore waters to the deep sea. Besides the general distribution of high production in coastal and estuarine waters, high PP area could also be found near the Xisha Islands. The high PP value usually appeared in the deep water other than in the surface layer with two vertical peaks in the euphotic zone, one at the depth of 0 - 20 m and another at the depth of 50 -75 m in most stations in the open water of the northern South China Sea. According to the vertical distribution of BP, maximum BP values appeared mostly near bottom layers of the euphotic zone (50 - 75 m). The correspondence analysis between BP and environmental parameters indicated that temperature and nutrients are not key controlling factors of BP in the northern South China Sea; BP was significantly correlated with phytoplankton biomass and PP. The IBP: IPP ratio averaged 67. 55 37. 13% and had a significant negative correlation with PP, which indicated that in the northern South China Sea, phytoplankton photosynthesis could afford enough carbon resource to the ecosystem in the high PP area in the euphotic zone, while in the area with low PP, the bacterial production process appeared to be more active. Microphytoplankton and nanophytoplakton was often the primary contributor to PP in the coastal area accompanying with the distribution of low BP: PP and IBP: IPP 9 which indicated that the classic food chain was the main approach for the basic carbon flux in the coastal waters of the northern South China Sea. However, in the oligotrophic open waters that cover most area of the northern South China Sea, IBP: IPP was evidently higher than that in the nearshore waters; the area with extreme high IBP: IPP ratio (> 100%) was found in part of the deep sea area. Meanwhile, picophytoplakton was the dominant primary producer in the oligotrophic waters in the South China Sea, which suggested that heterotrophic bacteria and picophytoplakton play important roles in the ecosystem carbon cycle transporting carbon flux via the microbial loop to higher nutrition levels in the oligotrophic waters of the South China Sea.


Peng P.,CAS Institute of Software | Peng P.,Graduate University of China Academy of science
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

We give a local algorithm to extract dense bipartite-like subgraphs which characterize cyber-communities in the Web [13]. We use the bipartiteness ratio of a set as the quality measure that was introduced by Trevisan [20]. Our algorithm, denoted as FindDenseBipartite (v,s,θ), takes as input a starting vertex v, a volume target s and a bipartiteness ratio parameter θ and outputs an induced subgraph of G. It is guaranteed to have the following approximation performance: for any subgraph S with bipartiteness ratio θ, there exists a subset S θ ⊆ S such that vol(S θ) ≥ vol(S)/9 and that if the starting vertex v ∈ S θ and s ≥ vol(S), the algorithm FindDenseBipartite (v,s,θ) outputs a subgraph (X,Y) with bipartiteness ratio O(√θ). The running time of the algorithm is O(s 2(Δ + logs)), where Δ is the maximum degree of G, independent of the size of G. © 2012 Springer-Verlag.


Long T.,CAS Institute of Software | Long T.,Graduate University of China Academy of science | Zhang W.,CAS Institute of Software
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Deductive rules are useful for proving properties with fairness constraints and there have been many studies on such rules with justice and compassion constraints. This paper focuses on system specifications with strengthened compassion that impose constraints on transitions involving states and their successors. A deductive rule for proving liveness properties under strengthened compassion is presented, and proofs of the soundness and the relative completeness of the rule are also presented. © 2012 Springer-Verlag.


Peng P.,CAS Institute of Software | Peng P.,Graduate University of China Academy of science
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

We survey a recent new line of research on the small community phenomenon in networks, which characterizes the intuition and observation that in a broad class of networks, a significant fraction of nodes belong to some small communities. We propose the formal definition of this phenomenon as well as the definition of communities, based on which we are able to both study the community structure of network models, i.e., whether a model exhibits the small community phenomenon or not, and design new models that embrace this phenomenon in a natural way while preserving some other typical network properties such as the small diameter and the power law degree distribution. We also introduce the corresponding community detection algorithms, which not only are used to identify true communities and confirm the existence of the small community phenomenon in real networks but also have found other applications, e.g., the classification of networks and core extraction of networks. © 2012 Springer-Verlag.


Long T.,Graduate University of China Academy of science | Zhang W.,CAS Institute of Software
Proceedings - Asia-Pacific Software Engineering Conference, APSEC | Year: 2012

Different rules for proving properties have been studied for systems with different kinds of fairness constraints, such as justice, compassion and strengthened compassion. This work considers a kind of bounded fairness and propose a general form that includes these fairness constraints. The general form is referred to as mixed-fairness (m-fairness for short). A deductive rule for proving live ness properties under m-fairness is presented with examples illustrating the application of the deductive rule. © 2012 IEEE.


Li A.,CAS Institute of Software | Peng P.,CAS Institute of Software | Peng P.,Graduate University of China Academy of science
Mathematical Structures in Computer Science | Year: 2012

We investigate several geometric models of networks that simultaneously have some nice global properties, including the small-diameter property, the small-community phenomenon, which is defined to capture the common experience that (almost) everyone in society also belongs to some meaningful small communities, and the power law degree distribution, for which our result significantly strengthens those given in van den Esker (2008) and Jordan (2010). These results, together with our previous work in Li and Peng (2011), build a mathematical foundation for the study of both communities and the small-community phenomenon in various networks. In the proof of the power law degree distribution, we develop the method of alternating concentration analysis to build a concentration inequality by alternately and iteratively applying both the sub- and super-martingale inequalities, which seems to be a powerful technique with further potential applications. © Copyright Cambridge University Press 2012.


Wei X.Z.,CAS Wuhan Botanical Garden | Wei X.Z.,Graduate University of China Academy of science | Liao J.X.,CAS Wuhan Botanical Garden | Jiang M.X.,CAS Wuhan Botanical Garden
Seed Science and Technology | Year: 2010

Euptelea pleiospermum is a rare tertiary relict tree species restricted to mountain riparian forests in China, India and Burma. Poor seedling recruitment is a serious threat to this species, but little is known about its seed or fruit germination. We examined the effects of pericarp, storage conditions, seed weight, substrate moisture content, gibberellic acid (GA3) and light regime, and potassium nitrate (KNO3) on seed or fruit germination. The final germination percentage was 0.8% for untreated fruits, reaching up to 21.2% for fruits with four months cold treatment. Germination test of fruits collected in four consecutive years revealed that seed vigour lost rapidly after one year. Both seed weight and GA3 had no significant effects on final germination percentage and germination dynamics. Pericarp prolonged the germination process, but it did not affect final germination percentage. The optimal substrate moisture content for germination was 20%. Light played a positive role in fruit germination. Nitrate combined with cold treatment were proven having an important effect on breaking non-deep dormancy in E. pleiospermum.

Loading Graduate University of China Academy of Science collaborators
Loading Graduate University of China Academy of Science collaborators