This article reports on and analyzes long-term projections of world food requirements compared with observed 2000 data reported by the United Nations’ Food and Agriculture Organization. The importance of this “post-...This article reports on and analyzes long-term projections of world food requirements compared with observed 2000 data reported by the United Nations’ Food and Agriculture Organization. The importance of this “post-mortem” is to strengthen the case for carrying out long-term projections of essential resources—food, energy, and non-fuel minerals— because of the long-lead times needed to insure that adequate global output levels of these basic ingredients of living standards will be met. This study should prove useful to those preparing today’s long-term projections, with world population projected to rise to over 9bn by mid-century.展开更多
Near-term climate projections are needed by policymakers; however, these projections are difficult because internally generated climate variations need to be considered. In this study, temperature change scenarios in ...Near-term climate projections are needed by policymakers; however, these projections are difficult because internally generated climate variations need to be considered. In this study, temperature change scenarios in the near-term period 2017-35 are projected at global and regional scales based on a refined multi-model ensemble approach that considers both the secular trend(ST) and multidecadal variability(MDV) in the Coupled Model Intercomparison Project Phase 5(CMIP5) simulations. The ST and MDV components are adaptively extracted from each model simulation by using the ensemble empirical mode decomposition(EEMD) filter, reconstructed via the Bayesian model averaging(BMA) method for the historical period 1901-2005, and validated for 2006-16. In the simulations of the "medium" representative concentration pathways scenario during 2017-35, the MDV-modulated temperature change projected via the refined approach displays an increase of 0.44℃(90% uncertainty range from 0.30 to 0.58℃) for global land, 0.48℃(90% uncertainty range from 0.29 to 0.67℃) for the Northern Hemispheric land(NL), and 0.29℃(90% uncertainty range from 0.23 to 0.35℃) for the Southern Hemispheric land(SL). These increases are smaller than those projected by the conventional arithmetic mean approach. The MDV enhances the ST in 13 of 21 regions across the world. The largest MDV-modulated warming effect(46%) exists in central America. In contrast,the MDV counteracts the ST in NL, SL, and eight other regions, with the largest cooling effect(220%) in Alaska.展开更多
International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to me...International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.展开更多
This paper gives a comprehensive introduction of National Cultural Information Resources Sharing Project. It discusses the best practices in creation and long-term preservation of multimedia digital resources, and rec...This paper gives a comprehensive introduction of National Cultural Information Resources Sharing Project. It discusses the best practices in creation and long-term preservation of multimedia digital resources, and recommends solutions to the key issues in resource selection, standards & specifications and copyright.展开更多
From viewpoint of nonlinear dynamics, the model reduction and its influence on the long-term behaviours of a class of nonlinear dissipative autonomous dynamical system with higher dimension are investigated theoretica...From viewpoint of nonlinear dynamics, the model reduction and its influence on the long-term behaviours of a class of nonlinear dissipative autonomous dynamical system with higher dimension are investigated theoretically under some assumptions. The system is analyzed in the state space with an introduction of a distance definition which can be used to describe the distance between the full system and the reduced system, and the solution of the full system is then projected onto the complete space spanned by the eigenvectors of the linear operator of the governing equations. As a result, the influence of mode series truncation on the long-term behaviours and the error estimate are derived, showing that the error is dependent on the first products of frequencies and damping ratios in the subspace spanned by the eigenvectors with higher modal damping. Furthermore, the fundamental understanding for the topological change of the solution due to the application of different model reduction is interpreted in a mathematically precise way, using the qualitative theory of nonlinear dynamics.展开更多
近年来热浪已成为危害城市公共卫生安全的极端天气事件之一,通过气候情景预测掌握未来热浪风险的时空格局,是保证气候适应性策略前瞻性和科学性的重要途径。基于中尺度气象模型(Weather Research and Forecasting model,WRF)对大连城市...近年来热浪已成为危害城市公共卫生安全的极端天气事件之一,通过气候情景预测掌握未来热浪风险的时空格局,是保证气候适应性策略前瞻性和科学性的重要途径。基于中尺度气象模型(Weather Research and Forecasting model,WRF)对大连城市气候远景预测(2041—2050年)的结果,将研究区域进行热浪风险评估并提出气候适应性策略。结果表明高风险区出现在甘井子区东北部、西岗区北部、沙河口区北部、中山区北部以及金州区中部。基于风险分区气候适应性策略分为两大类:总体策略和分区策略。总体策略包括城市“冷岛”保护和高温避灾场所策略。分区策略则主要针中高风险区展开,重点将高风险区划分为三类策略区,并明确指出气候适应性策略的优先行动区。展开更多
Very little is known about visual functional recovery following long-term naltrexone administration in opioid-dependent patients. In the present study, a portable event-related potential （ERP） working system was uti...Very little is known about visual functional recovery following long-term naltrexone administration in opioid-dependent patients. In the present study, a portable event-related potential （ERP） working system was utilized to collect and record ERP in opioid-dependent patients and normal controls in visual half-field testing. In addition, the influence of long-term sustained naltrexone release on the visual nervous system was observed in opioid-dependent patients. Results revealed a significant main group effect in reaction time to visual signal stimulations. The reaction time of normal controls was shortest, but longest in opioid-dependent patients. The reaction time of long-term sustained naltrexone release group and compulsory detoxification group was similar to normal controls. A significant main group effect was also observed in P100 latency, and P100 latency in normal controls and the compulsory detoxification group was significantly decreased compared with the opioid-dependent patients. P100 amplitude at the Oz-electrode resulted in a significant main group effect. In particular, normal controls exhibited significant differences compared with long-term sustained release naltrexone and compulsory detoxification groups. These findings demonstrated that long-term sustained naltrexone release effectively ameliorated optic center function and improved visual sensitivity and reactions in opioid-dependent patients.展开更多
文摘This article reports on and analyzes long-term projections of world food requirements compared with observed 2000 data reported by the United Nations’ Food and Agriculture Organization. The importance of this “post-mortem” is to strengthen the case for carrying out long-term projections of essential resources—food, energy, and non-fuel minerals— because of the long-lead times needed to insure that adequate global output levels of these basic ingredients of living standards will be met. This study should prove useful to those preparing today’s long-term projections, with world population projected to rise to over 9bn by mid-century.
基金Supported by the National Key Research and Development Program of China(2016YFA0600404)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2016075)Jiangsu Collaborative Innovation Center for Climate Change
文摘Near-term climate projections are needed by policymakers; however, these projections are difficult because internally generated climate variations need to be considered. In this study, temperature change scenarios in the near-term period 2017-35 are projected at global and regional scales based on a refined multi-model ensemble approach that considers both the secular trend(ST) and multidecadal variability(MDV) in the Coupled Model Intercomparison Project Phase 5(CMIP5) simulations. The ST and MDV components are adaptively extracted from each model simulation by using the ensemble empirical mode decomposition(EEMD) filter, reconstructed via the Bayesian model averaging(BMA) method for the historical period 1901-2005, and validated for 2006-16. In the simulations of the "medium" representative concentration pathways scenario during 2017-35, the MDV-modulated temperature change projected via the refined approach displays an increase of 0.44℃(90% uncertainty range from 0.30 to 0.58℃) for global land, 0.48℃(90% uncertainty range from 0.29 to 0.67℃) for the Northern Hemispheric land(NL), and 0.29℃(90% uncertainty range from 0.23 to 0.35℃) for the Southern Hemispheric land(SL). These increases are smaller than those projected by the conventional arithmetic mean approach. The MDV enhances the ST in 13 of 21 regions across the world. The largest MDV-modulated warming effect(46%) exists in central America. In contrast,the MDV counteracts the ST in NL, SL, and eight other regions, with the largest cooling effect(220%) in Alaska.
基金supported by the Young Fund of Shanxi University of Finance and Economics(No.QN-2018002)National Natural Science Foundation of China(No.71774105)the Fund for Shanxi Key Subjects Construction(FSKSC)and Shanxi Repatriate Study Abroad Foundation(No.2016-3)
文摘International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.
文摘This paper gives a comprehensive introduction of National Cultural Information Resources Sharing Project. It discusses the best practices in creation and long-term preservation of multimedia digital resources, and recommends solutions to the key issues in resource selection, standards & specifications and copyright.
文摘From viewpoint of nonlinear dynamics, the model reduction and its influence on the long-term behaviours of a class of nonlinear dissipative autonomous dynamical system with higher dimension are investigated theoretically under some assumptions. The system is analyzed in the state space with an introduction of a distance definition which can be used to describe the distance between the full system and the reduced system, and the solution of the full system is then projected onto the complete space spanned by the eigenvectors of the linear operator of the governing equations. As a result, the influence of mode series truncation on the long-term behaviours and the error estimate are derived, showing that the error is dependent on the first products of frequencies and damping ratios in the subspace spanned by the eigenvectors with higher modal damping. Furthermore, the fundamental understanding for the topological change of the solution due to the application of different model reduction is interpreted in a mathematically precise way, using the qualitative theory of nonlinear dynamics.
文摘近年来热浪已成为危害城市公共卫生安全的极端天气事件之一,通过气候情景预测掌握未来热浪风险的时空格局,是保证气候适应性策略前瞻性和科学性的重要途径。基于中尺度气象模型(Weather Research and Forecasting model,WRF)对大连城市气候远景预测(2041—2050年)的结果,将研究区域进行热浪风险评估并提出气候适应性策略。结果表明高风险区出现在甘井子区东北部、西岗区北部、沙河口区北部、中山区北部以及金州区中部。基于风险分区气候适应性策略分为两大类:总体策略和分区策略。总体策略包括城市“冷岛”保护和高温避灾场所策略。分区策略则主要针中高风险区展开,重点将高风险区划分为三类策略区,并明确指出气候适应性策略的优先行动区。
基金the Natural Science Foundation of Guangdong Province,No. 06027973the Science and Technology Development Program of Guangdong Province,No. 2004B3600105the Medical Science Foundation Program of Guangdong Province,No. A2007592
文摘Very little is known about visual functional recovery following long-term naltrexone administration in opioid-dependent patients. In the present study, a portable event-related potential （ERP） working system was utilized to collect and record ERP in opioid-dependent patients and normal controls in visual half-field testing. In addition, the influence of long-term sustained naltrexone release on the visual nervous system was observed in opioid-dependent patients. Results revealed a significant main group effect in reaction time to visual signal stimulations. The reaction time of normal controls was shortest, but longest in opioid-dependent patients. The reaction time of long-term sustained naltrexone release group and compulsory detoxification group was similar to normal controls. A significant main group effect was also observed in P100 latency, and P100 latency in normal controls and the compulsory detoxification group was significantly decreased compared with the opioid-dependent patients. P100 amplitude at the Oz-electrode resulted in a significant main group effect. In particular, normal controls exhibited significant differences compared with long-term sustained release naltrexone and compulsory detoxification groups. These findings demonstrated that long-term sustained naltrexone release effectively ameliorated optic center function and improved visual sensitivity and reactions in opioid-dependent patients.
