Field trials to determine the yield response of potatoes to Umostart Super Zn （USZ） fertilizer （11.46.0 ＋ 2 Zn ＋ Humates） were carried out in 2004 using the cultivar Tigoni. During the long rains season, the tre...Field trials to determine the yield response of potatoes to Umostart Super Zn （USZ） fertilizer （11.46.0 ＋ 2 Zn ＋ Humates） were carried out in 2004 using the cultivar Tigoni. During the long rains season, the treatments included USZ at 15 kg ha^-1 at planting; 30 kg ha^-1 split into 15 kg ha^-1 at planting and 15 kg ha^-1 during final earthing-up; 30 kg ha^-1 at planting; and 45 kg ha^-1 at planting. Treatments during the short rains included USZ at 30 kg ha^-1 split into 15 kg ha^-1 at planting and 15 kg ha^-1 during final earthing-up; 30 kg ha^-1 at planting; 40 kg ha^-1 at planting; 50 kg ha^-1 at planting; 50 kg ha^-1 split into 25 kg ha^-1 at planting and 25 kg ha^-1 during final earthing-up; and 60 kg ha^-1 at planting. USZ was contrasted with Diammonium phosphate （DAP） fertilizer （18：46：0） at 300 kg ha^-1 and 500 kg ha^-1 applied at planting and a control in which no fertilizer was applied. The DAP 300 kg ha^-1 treatment was however, not included during the long rains season. The highest tuber yields among the USZ treatments were obtained in plots treated with 45 kg ha^-1 （27.11 t ha^-1） during the long rains and 60 kg ha^-1 （55.17 t ha^-1） during the short rains season. Application of USZ resulted in a yield increase of at least 3.90 and 19.06 t ha^-1 during the long and short rains seasons respectively.展开更多
Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and ...Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and should be added to the total value of the concession. However, in these cases, traditional valuation techniques, like the NPV （net present value） of the project, are insufficient. An alternative methodology for the valuation of highway concession is one based on the real options approach. This methodology is generally built on the assumption of the evolution of traffic volume as a GBM （geometric Brownian motion）, which is the hypothesis analyzed in this paper. First, a description of the methodology used for the analysis of the existence of unit roots （i.e., the hypothesis of non-stationarity） is provided. The Dickey-Fuller approach has been used, which is the most common test for this kind of analysis. Then this methodology is applied to perform a statistical analysis of traffic series in Spanish toll highways. For this purpose, data on the AADT （annual average daily traffic） on a set of highways have been used. The period of analysis is around thirty years in most cases. The main outcome of the research is that the hypothesis that traffic volume follows a GBM process in Spanish toll highways cannot be rejected. This result is robust, and therefore it can be used as a starting point for the application of the real options theory to assess toll highway concessions.展开更多
We improve estimates for the distribution of primitive λ-roots of a composite modulus q yielding an asymptotic formula for the number of primitive A-roots in any interval I of length ｜I｜ 〉〉 q^1/2＋ε Similar resu...We improve estimates for the distribution of primitive λ-roots of a composite modulus q yielding an asymptotic formula for the number of primitive A-roots in any interval I of length ｜I｜ 〉〉 q^1/2＋ε Similar results are obtained for the distribution of ordered pairs （x, x^-1） with x a primitive λ-root, and for the number of primitive A-roots satisfying inequalities such as ｜x - x^-1｜≤ B.展开更多
The financial crisis, beginning from 2008, has brought into sharp relief just how dependent the US has become on foreign creditors, chiefly among them China. It has also sharpened the perception of the relative declin...The financial crisis, beginning from 2008, has brought into sharp relief just how dependent the US has become on foreign creditors, chiefly among them China. It has also sharpened the perception of the relative decline of a US- centric West and the relative rise of a China-centric Aria. The changing relationship between the US and China does demand a new tone. The article will be based on the Hegemonic Stability Theory. According to Charles Kindleberger, one of the scholars most closely associated with the theory, the United States should have acted as a lender of last resort in the early 1930s, continuing to keep its financial markets open to investment and its market open to foreign goods, rather than heading down the path of protectionism. With the inability to complete the Doha round of trade negotiations, the rising influence of the Group of 20, and the centrality of China in the climate change negotiations in Copenhagen, it has been proven that ＂ the provision of basic global public goods now demands co-operation between the established powers and emerging countries. ＂ However, today＇s China may be in a position comparable to that of the US in the 1930s and cannot hope to stabilize the world on its own＇ Thus, the article will also investigate the competition between China and the US for sharing fairer burdens to provide public goods. Based on Hegemonic Stability Theory, the world politics will not be stable in the near future because, on the one hand, the US has not enough capability to lead and to enforce the rules of the system, on the other hand, China has no will to establish a hegemonic regime.展开更多
As common soil fungi that form symbioses with most terrestrial plants,arbuscular mycorrhizal(AM) fungi play an important role in plant adaptation to chromium(Cr) contamination.However,little information is available o...As common soil fungi that form symbioses with most terrestrial plants,arbuscular mycorrhizal(AM) fungi play an important role in plant adaptation to chromium(Cr) contamination.However,little information is available on the underlying mechanisms of AM symbiosis on plant Cr resistance.In this study,dandelion(Taraxacum platypecidum Diels.) was grown with and without inoculation of the AM fungus Rhizophagus irregularis and Cr uptake by extraradical mycelium(ERM) was investigated by a compartmented cultivation system using a Cr stable isotope tracer.The results indicated that AM symbiosis increased plant dry weights and P concentrations but decreased shoot Cr concentrations.Using the Cr stable isotope tracer technology,the work provided possible evidences of Cr uptake and transport by ERM,and confirmed the enhancement of root Cr stabilization by AM symbiosis.This study also indicated an enrichment of lighter Cr isotopes in shoots during Cr translocation from roots to shoots in mycorrhizal plants.展开更多
Forty species of Basidiomycota from 21 genera in 15 families, collected from Liuxihe National Forest Park, Guangzhou, China, have values for use by local people. More than half of the species collected are edible, and...Forty species of Basidiomycota from 21 genera in 15 families, collected from Liuxihe National Forest Park, Guangzhou, China, have values for use by local people. More than half of the species collected are edible, and some (Lactarius deliciosus, Boletus spp.) are gathered for commercial consumption in South China. Ten species have medicinal properties, and include Dictyophora, Ganoderma, Pisolithus and Scleroderma. Over 60% species (26 taxa) are ectomycorrhizal involving 12 edible fungi. The most abundant families were the Amanitaceae, Boletaceae and Sclerodermataceae, which form important ectomycorrhizal associations with coniferous and mixed broad-leafed trees in the Park. Prospective uses of these macrofungi are discussed.展开更多
Arbuscular mycorrhizal （AM）-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytie plants is uncle...Arbuscular mycorrhizal （AM）-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytie plants is unclear. A pot experiment was conducted to determine whether salt tolerance of the C3 halophyte Suaeda salsa was enhanced by the AM fungus Glomus rnosseae. When 60-day-old S. salsa seedlings were subjected to 400 mmol L-1 NaC1 stress for 35 days, plant height, number of leaves and branches, shoot and root biomass, and root length of G. mosseae-colonized seedlings were significantly greater than those of the nonmycorrizal seedlings. Leaf superoxide dismutase （SOD） activity at all sampling times （weekly for 35 days after salt stress was initiated） and leaf catalase （CAT） activity at 2 and 3 weeks after salt stress was initiated were also significantly enhanced in G. mosseae-colonized S. salsa seedlings, while the content of leaf malondialdehyde （MDA）, a product of membrane lipid peroxidation, was significantly reduced, indicating an alleviation of oxidative damage. The corresponding leaf isoenzymes of SOD （Fe-SOD, Cu/Zn-SOD1, and Cu/Zn-SOD2） and CAT （CAT1 and CAT2） were also significantly increased in the mycorrhizal seedlings after 14 days of 400 mmol L-1 NaC1 stress. Our results suggested that G. rnosseae increased salt tolerance by increasing SOD and CAT activities and forming SOD and CAT isoforms in S. salsa seedlings.展开更多
文摘Field trials to determine the yield response of potatoes to Umostart Super Zn （USZ） fertilizer （11.46.0 ＋ 2 Zn ＋ Humates） were carried out in 2004 using the cultivar Tigoni. During the long rains season, the treatments included USZ at 15 kg ha^-1 at planting; 30 kg ha^-1 split into 15 kg ha^-1 at planting and 15 kg ha^-1 during final earthing-up; 30 kg ha^-1 at planting; and 45 kg ha^-1 at planting. Treatments during the short rains included USZ at 30 kg ha^-1 split into 15 kg ha^-1 at planting and 15 kg ha^-1 during final earthing-up; 30 kg ha^-1 at planting; 40 kg ha^-1 at planting; 50 kg ha^-1 at planting; 50 kg ha^-1 split into 25 kg ha^-1 at planting and 25 kg ha^-1 during final earthing-up; and 60 kg ha^-1 at planting. USZ was contrasted with Diammonium phosphate （DAP） fertilizer （18：46：0） at 300 kg ha^-1 and 500 kg ha^-1 applied at planting and a control in which no fertilizer was applied. The DAP 300 kg ha^-1 treatment was however, not included during the long rains season. The highest tuber yields among the USZ treatments were obtained in plots treated with 45 kg ha^-1 （27.11 t ha^-1） during the long rains and 60 kg ha^-1 （55.17 t ha^-1） during the short rains season. Application of USZ resulted in a yield increase of at least 3.90 and 19.06 t ha^-1 during the long and short rains seasons respectively.
文摘Concession contracts in highways often include some kind of clauses （for example, a minimum traffic guarantee） that allow for better management of the business risks. The value of these clauses may be important and should be added to the total value of the concession. However, in these cases, traditional valuation techniques, like the NPV （net present value） of the project, are insufficient. An alternative methodology for the valuation of highway concession is one based on the real options approach. This methodology is generally built on the assumption of the evolution of traffic volume as a GBM （geometric Brownian motion）, which is the hypothesis analyzed in this paper. First, a description of the methodology used for the analysis of the existence of unit roots （i.e., the hypothesis of non-stationarity） is provided. The Dickey-Fuller approach has been used, which is the most common test for this kind of analysis. Then this methodology is applied to perform a statistical analysis of traffic series in Spanish toll highways. For this purpose, data on the AADT （annual average daily traffic） on a set of highways have been used. The period of analysis is around thirty years in most cases. The main outcome of the research is that the hypothesis that traffic volume follows a GBM process in Spanish toll highways cannot be rejected. This result is robust, and therefore it can be used as a starting point for the application of the real options theory to assess toll highway concessions.
基金Project supported by the National Natural Science Foundation of China (No.19625102)the 973 Project of the Ministry of Science and Technology of China.
文摘We improve estimates for the distribution of primitive λ-roots of a composite modulus q yielding an asymptotic formula for the number of primitive A-roots in any interval I of length ｜I｜ 〉〉 q^1/2＋ε Similar results are obtained for the distribution of ordered pairs （x, x^-1） with x a primitive λ-root, and for the number of primitive A-roots satisfying inequalities such as ｜x - x^-1｜≤ B.
文摘The financial crisis, beginning from 2008, has brought into sharp relief just how dependent the US has become on foreign creditors, chiefly among them China. It has also sharpened the perception of the relative decline of a US- centric West and the relative rise of a China-centric Aria. The changing relationship between the US and China does demand a new tone. The article will be based on the Hegemonic Stability Theory. According to Charles Kindleberger, one of the scholars most closely associated with the theory, the United States should have acted as a lender of last resort in the early 1930s, continuing to keep its financial markets open to investment and its market open to foreign goods, rather than heading down the path of protectionism. With the inability to complete the Doha round of trade negotiations, the rising influence of the Group of 20, and the centrality of China in the climate change negotiations in Copenhagen, it has been proven that ＂ the provision of basic global public goods now demands co-operation between the established powers and emerging countries. ＂ However, today＇s China may be in a position comparable to that of the US in the 1930s and cannot hope to stabilize the world on its own＇ Thus, the article will also investigate the competition between China and the US for sharing fairer burdens to provide public goods. Based on Hegemonic Stability Theory, the world politics will not be stable in the near future because, on the one hand, the US has not enough capability to lead and to enforce the rules of the system, on the other hand, China has no will to establish a hegemonic regime.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX2-YW-BR-17)the National Natural Science Foundation of China(No.41101246)the State Key Laboratory of Urban and Regional Ecology, Research Center of Eco-Environmental Sciences,Chinese Academy of Sciences(No.SKLURE2008-1-03)
文摘As common soil fungi that form symbioses with most terrestrial plants,arbuscular mycorrhizal(AM) fungi play an important role in plant adaptation to chromium(Cr) contamination.However,little information is available on the underlying mechanisms of AM symbiosis on plant Cr resistance.In this study,dandelion(Taraxacum platypecidum Diels.) was grown with and without inoculation of the AM fungus Rhizophagus irregularis and Cr uptake by extraradical mycelium(ERM) was investigated by a compartmented cultivation system using a Cr stable isotope tracer.The results indicated that AM symbiosis increased plant dry weights and P concentrations but decreased shoot Cr concentrations.Using the Cr stable isotope tracer technology,the work provided possible evidences of Cr uptake and transport by ERM,and confirmed the enhancement of root Cr stabilization by AM symbiosis.This study also indicated an enrichment of lighter Cr isotopes in shoots during Cr translocation from roots to shoots in mycorrhizal plants.
文摘Forty species of Basidiomycota from 21 genera in 15 families, collected from Liuxihe National Forest Park, Guangzhou, China, have values for use by local people. More than half of the species collected are edible, and some (Lactarius deliciosus, Boletus spp.) are gathered for commercial consumption in South China. Ten species have medicinal properties, and include Dictyophora, Ganoderma, Pisolithus and Scleroderma. Over 60% species (26 taxa) are ectomycorrhizal involving 12 edible fungi. The most abundant families were the Amanitaceae, Boletaceae and Sclerodermataceae, which form important ectomycorrhizal associations with coniferous and mixed broad-leafed trees in the Park. Prospective uses of these macrofungi are discussed.
基金Supported by the National High Technology Research and Development Program (863 Program) of China (No. 2007AA091701)the National Natural Science Foundation of China (No. 30870138)
文摘Arbuscular mycorrhizal （AM）-mediated plant physiological activities could contribute to plant salt tolerance. However, the biochemical mechanism by which AM fungi enhance salt tolerance of halophytie plants is unclear. A pot experiment was conducted to determine whether salt tolerance of the C3 halophyte Suaeda salsa was enhanced by the AM fungus Glomus rnosseae. When 60-day-old S. salsa seedlings were subjected to 400 mmol L-1 NaC1 stress for 35 days, plant height, number of leaves and branches, shoot and root biomass, and root length of G. mosseae-colonized seedlings were significantly greater than those of the nonmycorrizal seedlings. Leaf superoxide dismutase （SOD） activity at all sampling times （weekly for 35 days after salt stress was initiated） and leaf catalase （CAT） activity at 2 and 3 weeks after salt stress was initiated were also significantly enhanced in G. mosseae-colonized S. salsa seedlings, while the content of leaf malondialdehyde （MDA）, a product of membrane lipid peroxidation, was significantly reduced, indicating an alleviation of oxidative damage. The corresponding leaf isoenzymes of SOD （Fe-SOD, Cu/Zn-SOD1, and Cu/Zn-SOD2） and CAT （CAT1 and CAT2） were also significantly increased in the mycorrhizal seedlings after 14 days of 400 mmol L-1 NaC1 stress. Our results suggested that G. rnosseae increased salt tolerance by increasing SOD and CAT activities and forming SOD and CAT isoforms in S. salsa seedlings.
