In this paper,we incorporate Markov regime-switching into a two-factor stochastic volatility jump-diffusion model to enhance the pricing of power options.Furthermore,we assume that the interest rates and the jump inte...In this paper,we incorporate Markov regime-switching into a two-factor stochastic volatility jump-diffusion model to enhance the pricing of power options.Furthermore,we assume that the interest rates and the jump intensities of the assets are stochastic.Under the proposed framework,first,we derive the analytical pricing formula for power options by using Fourier transform technique,Esscher transform and characteristic function.Then we provide the efficient approximation to calculate the analytical pricing formula of power options by using the FFT approach and examine the accuracy of the approximation by Monte Carlo simulation.Finally,we provide some sensitivity analysis of the model parameters to power options.Numerical examples show this model is suitable for empirical work in practice.展开更多
From AR-enhanced picture books to eco-friendly smart toys,the items now filling children’s shopping carts are more than just products-they epitomize the transformation of consumption in the new era.
The paper is on toxic foreign exchange options problem which occurred in Poland just prior to and after the outbreak of the recent crisis. Especially Polish enterprises were severely stricken by transactions on fx and...The paper is on toxic foreign exchange options problem which occurred in Poland just prior to and after the outbreak of the recent crisis. Especially Polish enterprises were severely stricken by transactions on fx and interest rate derivatives contracted with their banks. Poland was the only EU country which did not precipitate into recession during the financial crisis beginning in 2008. However, the toxic fx and interest rate derivatives transmitted the shockwaves from global financial markets into Poland. Huge dimensions of losses resulted in conflicts between banks and their customers, who claimed just being cheated by the financial institutions. The article deeply researches into reasons for such developments on Polish fx over-the-counter derivatives market. As a case study, an authentic strategy has been presented. The contract was concluded between the construction company and one of the biggest commercial banks in Poland. Because the case study may be representative for many other cases, the analysis includes exact pricing of option strategy and therefore reveals inequality of the contract. The consequences of non-implementing the MiFID directive in the context of derivatives offering to non-financial customers were also touched in the paper.展开更多
This paper deals with the issue of investment certificate formation in the financial market. Investment certificate is a type of structured products, the value of which is derived from the value of an underlying asset...This paper deals with the issue of investment certificate formation in the financial market. Investment certificate is a type of structured products, the value of which is derived from the value of an underlying asset. The underlying asset is usually a share in a company, a basket of shares, or an entire index, etc.. It can be stated that for every estimated development of an asset （growth, fall, and stagnation） or for every attitude to risks （conservative or aggressive investors）, there is a suitable kind of certificate. The main objective is to perform an analysis of the structured product--Austria/Germany Bond 3 and its guarantee certificate construction using digital-barrier options. The authors have found an alternative opportunity to the purchase of this certificate, i.e., investment in a bank deposit, together with a purchase of cash or nothing down and four-knock-out call options and a sale of cash or nothing down and four-knock-out put options. The authors prove that the alternative investment has the same profit profile as the certificate. The authors made this analysis with the objective to contribute to the intellectualization of investors.展开更多
Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign cur...Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign currencies each with a different strike price in the payoff function. We carry out a comparative performance analysis of different stochastic volatility (SV), stochastic correlation (SC), and stochastic exchange rate (SER) models to determine the best combination of these models for Monte Carlo (MC) simulation pricing. In addition, we test the performance of all model variants with constant correlation as a benchmark. We find that a combination of GARCH-Jump SV, Weibull SC, and Ornstein Uhlenbeck (OU) SER performs best. In addition, we analyze different discretization schemes and their results. In our simulations, the Milstein scheme yields the best balance between execution times and lower standard deviations of price estimates. Furthermore, we find that incorporating mean reversion into stochastic correlation and stochastic FX rate modeling is beneficial for MC simulation pricing. We improve the accuracy of our simulations by implementing antithetic variates variance reduction. Finally, we derive the correlation risk parameters Cora and Gora in our framework so that correlation hedging of quanto options can be performed.展开更多
This paper employs the PPO(Proximal Policy Optimization) algorithm to study the risk hedging problem of the Shanghai Stock Exchange(SSE) 50ETF options. First, the action and state spaces were designed based on the cha...This paper employs the PPO(Proximal Policy Optimization) algorithm to study the risk hedging problem of the Shanghai Stock Exchange(SSE) 50ETF options. First, the action and state spaces were designed based on the characteristics of the hedging task, and a reward function was developed according to the cost function of the options. Second, combining the concept of curriculum learning, the agent was guided to adopt a simulated-to-real learning approach for dynamic hedging tasks, reducing the learning difficulty and addressing the issue of insufficient option data. A dynamic hedging strategy for 50ETF options was constructed. Finally, numerical experiments demonstrate the superiority of the designed algorithm over traditional hedging strategies in terms of hedging effectiveness.展开更多
In this paper, the evaluation of discretely sampled Asian options was considered by numerically solving the associated partial differential equations with the Legendre spectral method. Double average options were disc...In this paper, the evaluation of discretely sampled Asian options was considered by numerically solving the associated partial differential equations with the Legendre spectral method. Double average options were discussed as examples. The problem is a parabolic one on a finite domain whose equation degenerates into ordinary differential equations on the boundaries. A fully discrete scheme was established by using the Legendre spectral method in space and the Crank-Nicolson finite difference scheme in time. The stability and convergence of the scheme were analyzed. Numerical results show that the method can keep the spectral accuracy in space for such degenerate problems.展开更多
Alcoholic liver disease(ALD)and non-alcoholic fatty liver disease(NAFLD)are serious health problems worldwide.These two diseases have similar pathological spectra,ranging from simple steatosis to hepatitis to cirrhosi...Alcoholic liver disease(ALD)and non-alcoholic fatty liver disease(NAFLD)are serious health problems worldwide.These two diseases have similar pathological spectra,ranging from simple steatosis to hepatitis to cirrhosis and hepatocellular carcinoma.Although most people with excessive alcohol or calorie intake display abnormal fat accumulation in the liver(simple steatosis),a small percentage develops progressive liver disease.Despite extensive research on understanding the pathophysiology of both these diseases there are still no targeted therapies available.The treatment for ALD remains as it was 50 years ago:abstinence,nutritional support and corticosteroids(or pentoxifylline as an alternative if steroids are contraindicated).As for NAFLD,the treatment modality is mainly directed toward weight loss and co-morbidity management.Therefore,new pathophysiology directed therapies are urgently needed.However,the involvement of several inter-related pathways in the pathogenesis of these diseases suggests that a single therapeutic agent is unlikely to be an effective treatment strategy.Hence,a combination therapy towards multiple targets would eventually be required.In this review,we delineate the treatment options in ALD and NAFLD,including various new targeted therapies that are currently under investigation.We hope that soon we will be having an effective multi-therapeutic regimen for each disease.展开更多
Chronic hepatitis B virus(HBV)infection(CHB)is a public health concern worldwide.Current therapies utilizing nucleos(t)ide analogs(NA)have not resulted in a complete cure for CHB.Furthermore,patients on long-term NA t...Chronic hepatitis B virus(HBV)infection(CHB)is a public health concern worldwide.Current therapies utilizing nucleos(t)ide analogs(NA)have not resulted in a complete cure for CHB.Furthermore,patients on long-term NA treatment often develop low-level viremia(LLV).Persistent LLV,in addition to causing the progression of liver disease or hepatocellular carcinoma,may shed light on the current plight of NA therapy.Here,we review the literature on LLV,NA treatment,and various doses of entecavir to find a strategy for improving the efficacy of this antiviral agent.For LLV patients,three therapeutic options are available,switching to another antiviral monotherapy,interferon-αswitching therapy,and continuing monotherapy.In real-world clinical practice,entecavir overdose has been used in antiviral therapy for CHB patients with NA refractory and persistent LLV,which encouraged us to conduct further in-depth literature survey on dosage and duration related entecavir studies.The studies of pharmacodynamics and pharmacokinetics show that entecavir has the maximal selected index for safety,and has great potential in inhibiting HBV replication,in all of the NAs.In the particular section of the drug approval package published by the United States Food and Drug Administration,entecavir doses 2.5-20 mg/d do not increase adverse events,and entecavir doses higher than 1.0 mg/d might improve the antiviral efficacy.The literature survey led us to two suggestions:(1)Increasing entecavir dose to 1.0 mg/d for the treatment of NA naïve patients with HBV DNA>2×106 IU/mL is feasible and would provide better prognosis;and(2)Further research is needed to assess the long-term toxic effects of higher entecavir doses(2.5 and 5.0 mg/d),which may prove beneficial in treating patients with prior NA treatment,partial virological response,or LLV state.展开更多
An experimental study on mitigation of greenhouse gas (CH4, N2O and NO) emission has been conducted in a typical cropping system of Southeast China for 4 years. By simultaneous measurement, the CH4, N2O and NO emissio...An experimental study on mitigation of greenhouse gas (CH4, N2O and NO) emission has been conducted in a typical cropping system of Southeast China for 4 years. By simultaneous measurement, the CH4, N2O and NO emission fluxes from rice-wheat rotation fields, effects of fertilization, water management, temperature and soil moisture were investigated. Temperature, fertilization and water status were found to be the key factors to regulate CH4, N2O and NO emis-sions. Based on the experimental results, some agricultural measures were recommended as techni-cal options to mitigate greenhouse gas emissions from rice-wheat rotation ecosystems. These miti-gation measures are reducing mineral N input, coupling organic manure with chemical fertilizers, applying fertilizers which release available N slowly during periods with intensive plant activity, and applying dry fermented organic manure and well management of water and fertilizer. Key words Mitigation options - Emission - Greenhouse gases - Ecosystems This study was supported by projects “ Experimental and Modeling Study on N2O Emission from the Rice-Wheat Rotation Fields of Southeast China” and “ Experimental and Modeling Study on NO Emission from Croplands” , which were granted by the National Natural Science Foundation of China, the State Key Fundamental Research Project “ Predicting the Future (20–50 years) Trend of Environmental Change in China”, and the project of Chinese Academy of Sciences “ Theory and Methodology on Air Pollution Prediction”.Thanks are due to Professor Zhang Wen, Dr. Bai Jianhui, Mr. Gong Yanbang, Mrs. Luo Dongmei and Mr. Liu Guangren from the Institute of Atmospheric Physics, Chinese Academy of Sciences for their help in experiments.展开更多
Near-surface deposits that extend to considerable depths are often amenable to both open pit mining and/or underground mining.This paper investigates the strategy of mining options for an orebody using a Mixed Integer...Near-surface deposits that extend to considerable depths are often amenable to both open pit mining and/or underground mining.This paper investigates the strategy of mining options for an orebody using a Mixed Integer Linear Programming(MILP)optimization framework.The MILP formulation maximizes the Net Present Value(NPV)of the reserve when extracted with(i)open pit mining,(ii)underground mining,and(iii)concurrent open pit and underground mining.Comparatively,implementing open pit mining generates a higher NPV than underground mining.However considering the investment required for these mining options,underground mining generates a better return on investment than open pit mining.Also,in the concurrent open pit and underground mining scenario,the optimizer prefers extracting blocks using open pit mining.Although the underground mine could access ore sooner,the mining cost differential for open pit mining is more than compensated for by the discounting benefits associated with earlier underground mining.展开更多
Ameliorating waste treatment by technological improvements affects the economic and the ecological-environment benefits of intensive pig production. The objective of the research was to develop and test a method to de...Ameliorating waste treatment by technological improvements affects the economic and the ecological-environment benefits of intensive pig production. The objective of the research was to develop and test a method to determine the technical optimization to ameliorate waste treatment methods and gain insight into the relationship between technological options and the economic and ecological effects. We developed an integrated bio-economic model which incorporates the farming production and waste disposal systems to simulate the impact of technological improvements in pig manure treatment on economic and environmental benefits for the case of a pilot farm in Beijing, China. Based on different waste treatment technology options, three scenarios are applied for the simulation analysis of the model. The simulation results reveal that the economic-environmental benefits of the livestock farm could be improved by reducing the cropland manure application and increasing the composting production with the current technologies. Nevertheless, the technical efficiency, the waste treatment capacity and the economic benefits could be further improved by the introduction of new technologies. It implies that technological and economic support policies should be implemented comprehensively on waste disposal and resource utilization to promote sustainable development in intensive livestock production in China.展开更多
It is believed that the global CO2 emissions have to begin dropping in the near fu- ture to limit the temperature increase within 2 degrees by 2100. So it is of great concern to environmentalists and national decision...It is believed that the global CO2 emissions have to begin dropping in the near fu- ture to limit the temperature increase within 2 degrees by 2100. So it is of great concern to environmentalists and national decision-makers to know how the global or national CO2 emissions would trend. This paper presented an approach to project the future CO2 emissions from the perspective of optimal economic growth, and applied this model to the cases of China and the United States, whose CO2 emissions together contributed to more than 40% of the global emissions. The projection results under the balanced and optimal economic growth path reveal that the CO2 emissions will peak in 2029 for China and 2024 for the USA owing to their empirically implied pace of energy efficiency improvement. Moreover, some abatement options are analyzed for China, which indicate that 1） putting up the energy price will de- crease the emissions at a high cost; 2） enhancing the decline rate of energy intensity can significantly mitigate the emissions with a modest cost; and 3） the energy substitution policy of replacing carbon intensive energies with clean ones has considerable potential to alleviate emissions without compromising the economic development.展开更多
Exotic options, or “path-dependent” options are options whose payoff depends on the behavior of the price of the underlying between 0 and the maturity, rather than merely on the final price of the underlying, such a...Exotic options, or “path-dependent” options are options whose payoff depends on the behavior of the price of the underlying between 0 and the maturity, rather than merely on the final price of the underlying, such as compound options, reset options and so on. In this paper, a generalization of the Geske formula for compound call options is obtained in the case of time-dependent volatility and time-dependent interest rate by applying martingale methods and the change of numeraire or the change of probability measure. An analytic formula for the reset call options with predetermined dates is also derived in the case by using the same approach. In contrast to partial differential equation (PDE) approach, our approach is simpler.展开更多
Environmental sustainability has become a policy priority in China. In agriculture, China has had major success in rehabilitating desertified lands through programs to convert steeply-sloped cropland to forest and lim...Environmental sustainability has become a policy priority in China. In agriculture, China has had major success in rehabilitating desertified lands through programs to convert steeply-sloped cropland to forest and limit grazing on sensitive grasslands. However, little has been done in terms of policies for agricultural nutrient management. Runoff and leaching of nutrients in chemical fertilizers and livestock manure are widely acknowledged as significant problems in China. This paper presents an evaluation of agricultural nonpoint pollution control options for China. Options analyzed include design standards（command ＆ control）, performance standards, and design and performance incentives. Evaluation criteria include economic efficiency and effectiveness, environmental impact and risk, and social criteria such as equity and food security. The evaluation indicates that the best options for China involve subsidies to farmers for changing production practices in order to reduce nonpoint emissions, combined with appropriate farmer education and technical assistance.展开更多
Commodity prices have fallen sharply due to the global financial crisis. This has adversely affected the viability of some mining projects, including leading to the possibility of bankruptcy for some companies. These ...Commodity prices have fallen sharply due to the global financial crisis. This has adversely affected the viability of some mining projects, including leading to the possibility of bankruptcy for some companies. These price falls reflect uncertainties and risks associated with mining projects. In recent years, much work has been published related to the application of real options pricing theory to value life-of-mine plans in response to long term financial uncertainty and risk. However, there are uncertainties and risks associated with medium/short-term mining operations. Real options theory can also be applied to tactical decisions involving uncertainties and risks. This paper will investigate the application of real options in the mining industry and present a methodology developed at University of Queensland, Australia, for integrating real options into medium/short-term mine planning and production scheduling. A case study will demonstrate the validity and usefulness of the methodology and techniques developed.展开更多
Through the research on several carbonate reservoirs developed in the Middle East, the basic characteristics of different types of carbonate reservoirs are determined, and a set of high-efficiency water injection deve...Through the research on several carbonate reservoirs developed in the Middle East, the basic characteristics of different types of carbonate reservoirs are determined, and a set of high-efficiency water injection development options and strategies are presented. Hidden baffles and barriers exist in carbonate reservoirs in the Middle East, so the reservoirs could be divided into different separated development units based on the baffles and barriers characteristics. Flexible and diverse profile control techniques such as high angle wells and simple and applicative zonal water injection have been introduced to improve the control and development degree of reservoirs. Three principal water injection development methods suitable for different carbonate reservoirs in the Middle East are proposed, including the combination of crestal gas injection and peripheral water injection, bottom interval injection and top interval production(buoyancy underpinning), and "weak point and strong plane" area well pattern. Based on the characteristics of very low shale content, fast and far pressure transmission in the Middle East carbonate reservoirs, a large well-spacing flood pattern is recommended, and reasonable development strategies have been made such as moderate water injection rate and maintaining reasonable production pressure drawdown and voidage replacement ratio, so as to maximize the recovery of reservoirs in the none or low water cut period.展开更多
文摘In this paper,we incorporate Markov regime-switching into a two-factor stochastic volatility jump-diffusion model to enhance the pricing of power options.Furthermore,we assume that the interest rates and the jump intensities of the assets are stochastic.Under the proposed framework,first,we derive the analytical pricing formula for power options by using Fourier transform technique,Esscher transform and characteristic function.Then we provide the efficient approximation to calculate the analytical pricing formula of power options by using the FFT approach and examine the accuracy of the approximation by Monte Carlo simulation.Finally,we provide some sensitivity analysis of the model parameters to power options.Numerical examples show this model is suitable for empirical work in practice.
文摘From AR-enhanced picture books to eco-friendly smart toys,the items now filling children’s shopping carts are more than just products-they epitomize the transformation of consumption in the new era.
文摘The paper is on toxic foreign exchange options problem which occurred in Poland just prior to and after the outbreak of the recent crisis. Especially Polish enterprises were severely stricken by transactions on fx and interest rate derivatives contracted with their banks. Poland was the only EU country which did not precipitate into recession during the financial crisis beginning in 2008. However, the toxic fx and interest rate derivatives transmitted the shockwaves from global financial markets into Poland. Huge dimensions of losses resulted in conflicts between banks and their customers, who claimed just being cheated by the financial institutions. The article deeply researches into reasons for such developments on Polish fx over-the-counter derivatives market. As a case study, an authentic strategy has been presented. The contract was concluded between the construction company and one of the biggest commercial banks in Poland. Because the case study may be representative for many other cases, the analysis includes exact pricing of option strategy and therefore reveals inequality of the contract. The consequences of non-implementing the MiFID directive in the context of derivatives offering to non-financial customers were also touched in the paper.
文摘This paper deals with the issue of investment certificate formation in the financial market. Investment certificate is a type of structured products, the value of which is derived from the value of an underlying asset. The underlying asset is usually a share in a company, a basket of shares, or an entire index, etc.. It can be stated that for every estimated development of an asset （growth, fall, and stagnation） or for every attitude to risks （conservative or aggressive investors）, there is a suitable kind of certificate. The main objective is to perform an analysis of the structured product--Austria/Germany Bond 3 and its guarantee certificate construction using digital-barrier options. The authors have found an alternative opportunity to the purchase of this certificate, i.e., investment in a bank deposit, together with a purchase of cash or nothing down and four-knock-out call options and a sale of cash or nothing down and four-knock-out put options. The authors prove that the alternative investment has the same profit profile as the certificate. The authors made this analysis with the objective to contribute to the intellectualization of investors.
文摘Quanto options allow the buyer to exchange the foreign currency payoff into the domestic currency at a fixed exchange rate. We investigate quanto options with multiple underlying assets valued in different foreign currencies each with a different strike price in the payoff function. We carry out a comparative performance analysis of different stochastic volatility (SV), stochastic correlation (SC), and stochastic exchange rate (SER) models to determine the best combination of these models for Monte Carlo (MC) simulation pricing. In addition, we test the performance of all model variants with constant correlation as a benchmark. We find that a combination of GARCH-Jump SV, Weibull SC, and Ornstein Uhlenbeck (OU) SER performs best. In addition, we analyze different discretization schemes and their results. In our simulations, the Milstein scheme yields the best balance between execution times and lower standard deviations of price estimates. Furthermore, we find that incorporating mean reversion into stochastic correlation and stochastic FX rate modeling is beneficial for MC simulation pricing. We improve the accuracy of our simulations by implementing antithetic variates variance reduction. Finally, we derive the correlation risk parameters Cora and Gora in our framework so that correlation hedging of quanto options can be performed.
基金supported by the Foundation of Key Laboratory of System Control and Information Processing,Ministry of Education,China,Scip20240111Aeronautical Science Foundation of China,Grant 2024Z071108001the Foundation of Key Laboratory of Traffic Information and Safety of Anhui Higher Education Institutes,Anhui Sanlian University,KLAHEI18018.
文摘This paper employs the PPO(Proximal Policy Optimization) algorithm to study the risk hedging problem of the Shanghai Stock Exchange(SSE) 50ETF options. First, the action and state spaces were designed based on the characteristics of the hedging task, and a reward function was developed according to the cost function of the options. Second, combining the concept of curriculum learning, the agent was guided to adopt a simulated-to-real learning approach for dynamic hedging tasks, reducing the learning difficulty and addressing the issue of insufficient option data. A dynamic hedging strategy for 50ETF options was constructed. Finally, numerical experiments demonstrate the superiority of the designed algorithm over traditional hedging strategies in terms of hedging effectiveness.
文摘In this paper, the evaluation of discretely sampled Asian options was considered by numerically solving the associated partial differential equations with the Legendre spectral method. Double average options were discussed as examples. The problem is a parabolic one on a finite domain whose equation degenerates into ordinary differential equations on the boundaries. A fully discrete scheme was established by using the Legendre spectral method in space and the Crank-Nicolson finite difference scheme in time. The stability and convergence of the scheme were analyzed. Numerical results show that the method can keep the spectral accuracy in space for such degenerate problems.
基金Supported by Merit Review grants BX001155 from the Department of Veterans Affairs,Office of Research and Development(Biomedical Laboratory Research and Development)to Kharbanda KK
文摘Alcoholic liver disease(ALD)and non-alcoholic fatty liver disease(NAFLD)are serious health problems worldwide.These two diseases have similar pathological spectra,ranging from simple steatosis to hepatitis to cirrhosis and hepatocellular carcinoma.Although most people with excessive alcohol or calorie intake display abnormal fat accumulation in the liver(simple steatosis),a small percentage develops progressive liver disease.Despite extensive research on understanding the pathophysiology of both these diseases there are still no targeted therapies available.The treatment for ALD remains as it was 50 years ago:abstinence,nutritional support and corticosteroids(or pentoxifylline as an alternative if steroids are contraindicated).As for NAFLD,the treatment modality is mainly directed toward weight loss and co-morbidity management.Therefore,new pathophysiology directed therapies are urgently needed.However,the involvement of several inter-related pathways in the pathogenesis of these diseases suggests that a single therapeutic agent is unlikely to be an effective treatment strategy.Hence,a combination therapy towards multiple targets would eventually be required.In this review,we delineate the treatment options in ALD and NAFLD,including various new targeted therapies that are currently under investigation.We hope that soon we will be having an effective multi-therapeutic regimen for each disease.
文摘Chronic hepatitis B virus(HBV)infection(CHB)is a public health concern worldwide.Current therapies utilizing nucleos(t)ide analogs(NA)have not resulted in a complete cure for CHB.Furthermore,patients on long-term NA treatment often develop low-level viremia(LLV).Persistent LLV,in addition to causing the progression of liver disease or hepatocellular carcinoma,may shed light on the current plight of NA therapy.Here,we review the literature on LLV,NA treatment,and various doses of entecavir to find a strategy for improving the efficacy of this antiviral agent.For LLV patients,three therapeutic options are available,switching to another antiviral monotherapy,interferon-αswitching therapy,and continuing monotherapy.In real-world clinical practice,entecavir overdose has been used in antiviral therapy for CHB patients with NA refractory and persistent LLV,which encouraged us to conduct further in-depth literature survey on dosage and duration related entecavir studies.The studies of pharmacodynamics and pharmacokinetics show that entecavir has the maximal selected index for safety,and has great potential in inhibiting HBV replication,in all of the NAs.In the particular section of the drug approval package published by the United States Food and Drug Administration,entecavir doses 2.5-20 mg/d do not increase adverse events,and entecavir doses higher than 1.0 mg/d might improve the antiviral efficacy.The literature survey led us to two suggestions:(1)Increasing entecavir dose to 1.0 mg/d for the treatment of NA naïve patients with HBV DNA>2×106 IU/mL is feasible and would provide better prognosis;and(2)Further research is needed to assess the long-term toxic effects of higher entecavir doses(2.5 and 5.0 mg/d),which may prove beneficial in treating patients with prior NA treatment,partial virological response,or LLV state.
文摘An experimental study on mitigation of greenhouse gas (CH4, N2O and NO) emission has been conducted in a typical cropping system of Southeast China for 4 years. By simultaneous measurement, the CH4, N2O and NO emission fluxes from rice-wheat rotation fields, effects of fertilization, water management, temperature and soil moisture were investigated. Temperature, fertilization and water status were found to be the key factors to regulate CH4, N2O and NO emis-sions. Based on the experimental results, some agricultural measures were recommended as techni-cal options to mitigate greenhouse gas emissions from rice-wheat rotation ecosystems. These miti-gation measures are reducing mineral N input, coupling organic manure with chemical fertilizers, applying fertilizers which release available N slowly during periods with intensive plant activity, and applying dry fermented organic manure and well management of water and fertilizer. Key words Mitigation options - Emission - Greenhouse gases - Ecosystems This study was supported by projects “ Experimental and Modeling Study on N2O Emission from the Rice-Wheat Rotation Fields of Southeast China” and “ Experimental and Modeling Study on NO Emission from Croplands” , which were granted by the National Natural Science Foundation of China, the State Key Fundamental Research Project “ Predicting the Future (20–50 years) Trend of Environmental Change in China”, and the project of Chinese Academy of Sciences “ Theory and Methodology on Air Pollution Prediction”.Thanks are due to Professor Zhang Wen, Dr. Bai Jianhui, Mr. Gong Yanbang, Mrs. Luo Dongmei and Mr. Liu Guangren from the Institute of Atmospheric Physics, Chinese Academy of Sciences for their help in experiments.
基金funding support provided by the Laurentian University Research Fund for the compilation of this report
文摘Near-surface deposits that extend to considerable depths are often amenable to both open pit mining and/or underground mining.This paper investigates the strategy of mining options for an orebody using a Mixed Integer Linear Programming(MILP)optimization framework.The MILP formulation maximizes the Net Present Value(NPV)of the reserve when extracted with(i)open pit mining,(ii)underground mining,and(iii)concurrent open pit and underground mining.Comparatively,implementing open pit mining generates a higher NPV than underground mining.However considering the investment required for these mining options,underground mining generates a better return on investment than open pit mining.Also,in the concurrent open pit and underground mining scenario,the optimizer prefers extracting blocks using open pit mining.Although the underground mine could access ore sooner,the mining cost differential for open pit mining is more than compensated for by the discounting benefits associated with earlier underground mining.
基金supported by the International Cooperation Project of Ministry of Science and Technology of China(MOST:2009DFA32710,BMBF(FKZ):0330847F)the Natural Science Foundation of Zhejiang Province,China(Y13G030168)
文摘Ameliorating waste treatment by technological improvements affects the economic and the ecological-environment benefits of intensive pig production. The objective of the research was to develop and test a method to determine the technical optimization to ameliorate waste treatment methods and gain insight into the relationship between technological options and the economic and ecological effects. We developed an integrated bio-economic model which incorporates the farming production and waste disposal systems to simulate the impact of technological improvements in pig manure treatment on economic and environmental benefits for the case of a pilot farm in Beijing, China. Based on different waste treatment technology options, three scenarios are applied for the simulation analysis of the model. The simulation results reveal that the economic-environmental benefits of the livestock farm could be improved by reducing the cropland manure application and increasing the composting production with the current technologies. Nevertheless, the technical efficiency, the waste treatment capacity and the economic benefits could be further improved by the introduction of new technologies. It implies that technological and economic support policies should be implemented comprehensively on waste disposal and resource utilization to promote sustainable development in intensive livestock production in China.
基金National Basic Research Program of China （973 Program）, No.2012CB955804 National Science Foundation of China, No.41201594 CAS Strategic Priority Research Program, No.XDA05150502
文摘It is believed that the global CO2 emissions have to begin dropping in the near fu- ture to limit the temperature increase within 2 degrees by 2100. So it is of great concern to environmentalists and national decision-makers to know how the global or national CO2 emissions would trend. This paper presented an approach to project the future CO2 emissions from the perspective of optimal economic growth, and applied this model to the cases of China and the United States, whose CO2 emissions together contributed to more than 40% of the global emissions. The projection results under the balanced and optimal economic growth path reveal that the CO2 emissions will peak in 2029 for China and 2024 for the USA owing to their empirically implied pace of energy efficiency improvement. Moreover, some abatement options are analyzed for China, which indicate that 1） putting up the energy price will de- crease the emissions at a high cost; 2） enhancing the decline rate of energy intensity can significantly mitigate the emissions with a modest cost; and 3） the energy substitution policy of replacing carbon intensive energies with clean ones has considerable potential to alleviate emissions without compromising the economic development.
基金Project (No. Y604137) supported by the Natural Science Foundationof Zhejiang Province, China
文摘Exotic options, or “path-dependent” options are options whose payoff depends on the behavior of the price of the underlying between 0 and the maturity, rather than merely on the final price of the underlying, such as compound options, reset options and so on. In this paper, a generalization of the Geske formula for compound call options is obtained in the case of time-dependent volatility and time-dependent interest rate by applying martingale methods and the change of numeraire or the change of probability measure. An analytic formula for the reset call options with predetermined dates is also derived in the case by using the same approach. In contrast to partial differential equation (PDE) approach, our approach is simpler.
文摘Environmental sustainability has become a policy priority in China. In agriculture, China has had major success in rehabilitating desertified lands through programs to convert steeply-sloped cropland to forest and limit grazing on sensitive grasslands. However, little has been done in terms of policies for agricultural nutrient management. Runoff and leaching of nutrients in chemical fertilizers and livestock manure are widely acknowledged as significant problems in China. This paper presents an evaluation of agricultural nonpoint pollution control options for China. Options analyzed include design standards（command ＆ control）, performance standards, and design and performance incentives. Evaluation criteria include economic efficiency and effectiveness, environmental impact and risk, and social criteria such as equity and food security. The evaluation indicates that the best options for China involve subsidies to farmers for changing production practices in order to reduce nonpoint emissions, combined with appropriate farmer education and technical assistance.
文摘Commodity prices have fallen sharply due to the global financial crisis. This has adversely affected the viability of some mining projects, including leading to the possibility of bankruptcy for some companies. These price falls reflect uncertainties and risks associated with mining projects. In recent years, much work has been published related to the application of real options pricing theory to value life-of-mine plans in response to long term financial uncertainty and risk. However, there are uncertainties and risks associated with medium/short-term mining operations. Real options theory can also be applied to tactical decisions involving uncertainties and risks. This paper will investigate the application of real options in the mining industry and present a methodology developed at University of Queensland, Australia, for integrating real options into medium/short-term mine planning and production scheduling. A case study will demonstrate the validity and usefulness of the methodology and techniques developed.
文摘Through the research on several carbonate reservoirs developed in the Middle East, the basic characteristics of different types of carbonate reservoirs are determined, and a set of high-efficiency water injection development options and strategies are presented. Hidden baffles and barriers exist in carbonate reservoirs in the Middle East, so the reservoirs could be divided into different separated development units based on the baffles and barriers characteristics. Flexible and diverse profile control techniques such as high angle wells and simple and applicative zonal water injection have been introduced to improve the control and development degree of reservoirs. Three principal water injection development methods suitable for different carbonate reservoirs in the Middle East are proposed, including the combination of crestal gas injection and peripheral water injection, bottom interval injection and top interval production(buoyancy underpinning), and "weak point and strong plane" area well pattern. Based on the characteristics of very low shale content, fast and far pressure transmission in the Middle East carbonate reservoirs, a large well-spacing flood pattern is recommended, and reasonable development strategies have been made such as moderate water injection rate and maintaining reasonable production pressure drawdown and voidage replacement ratio, so as to maximize the recovery of reservoirs in the none or low water cut period.
