关键词： Maximum-principle boundaryvalue problem   Optimal control   Pontryagin maximum principle   Resource allocation   Singular regimes   Sufficient conditions of optimality in maximum principle terms   Two-sector economic model  

摘要： The article considers the problem of resource allocation in a two-sector economic model with a nonlinear production function of a special type. The main mathematical apparatus is Pontryagin's maximum principle, i.e., the theorem on necessary conditions of optimality. It is shown that in the given problem the maximum principle provides a necessary and sufficient condition of optimality. A possible singular solution of the problem is found. An extremum solution is constructed in explicit form under various assumptions about the initial values. A "sufficiently long" planning horizon is assumed. An alternative approach is described, which does not use the maximum principle and instead investigates the integral representation of the optimand functional. The detailed theoretical investigation of the problem is accompanied by numerous illustrations. © 2010 Springer Science+Business Media, Inc.

关键词： Tiered services   Price structure   Economic model  

摘要： We consider networks offering tiered services and corresponding price structures, a model that has become prevalent in practice. We develop an economic model for such networks and make contributions in two important areas. First, we formulate the problem of selecting the service tiers from three perspectives: one that considers the users' interests only, one that considers only the service provider's interests, and one that considers both simultaneously, i.e., the interests of society as a whole. We also present an approximate yet accurate and efficient solution approach for tackling these nonlinear programming problems. Given the set of (near-) optimal service tiers, we then employ game-theoretic techniques to find an optimal price for each service tier that strikes a balance between the conflicting objectives of users and service provider. This work provides a theoretical framework for reasoning about and pricing Internet tiered services, as well as a practical toolset for network providers to develop customized menus of service offerings. Our results also indicate that tiering solutions currently adopted by ISPs perform poorly both for the providers and society overall.

关键词： Staphylococcus aureus   Vaccine   Orthopedic surgery   Economics   Computer simulation  

摘要： To evaluate the potential economic value of a Staphylococcus aureus vaccine for pre-operative orthopedic surgery patients, we developed an economic computer simulation model. At MRSA colonization rates as low as 1%, a $50 vaccine was cost-effective [<=$50,000 per quality-adjusted life year (QALY) saved] at vaccine efficacy >= 30%, and a $100 vaccine at vaccine efficacy >= 70%. High MASA prevalence (>= 25%) could justify a vaccine price as high as $1000. Our results suggest that a S. aureus vaccine for the pre-operative orthopedic population would be very cost-effective over a wide range of MASA prevalence and vaccine efficacies and costs. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： 数据中心   模型分析   物理模型   可靠性模型   能效模型   生命周期模型   经济模型  

摘要： 本文在业内首次全面完整归纳了数据中心的模型,为数据中心的研究与建设提供了理论分析的模型、工具与方法。数据中心模型包括物理模型、可靠性模型、能效模型、生命周期模型、经济模型等,这些模型将为数据中心的规划、设计、建设提供深入的理论支持。

关键词： 阴极铜   硫化锌   净现值   矿业   钴   锰   资本支出   经济模型  

摘要： Baja矿业宣布了其在墨西哥Boleo铜钴锌锰项目的资本支出和经济模型。Baja矿业拥有该项目70％的股份，剩余由韩国投资集团拥有。公司宣布修正后的资本支出预计为8．89亿美元，每年能生产310万吨干矿石，也就是在项目投产的最初6年中，每年能生产56，697吨阴极铜、1，708吨阴极钴和25，364吨硫化锌水合物。项目整体寿命是23年。因此，项目的净现值为13亿美元。

关键词： 耕地   面板数据   Eviews   社会经济模型  

摘要： 在界定了面板数据含义的基础上,介绍了面板数据回归模型及其具体估计方法。结合江苏省耕地利用现实情况,选取了总人口、地区生产总值、农业产值、固定资产总投资、社会消费品零售总额、城镇居民人均可支配收入、农民人均村收入7个对耕地变化有影响的社会经济因子作为解释变量,耕地作为被解释变量。利用江苏省13个市2000～2008年的面板数据,根据Hausman检验结果选用了固定系数、变截距的固定效应模型,并运用该模型构建了江苏省13个市的耕地社会经济模型。结果表明,人口因素是江苏省耕地变化最重要的驱动力因子,社会经济因素对耕地的固定效应较弱,农业产值的回归系数不显著,地区生产总值的模型系数所反映的经济含义与现实不符,模型从经济意义上来说总体是显著的。

关键词： 金融发展模型   经济模型   光大集团   全国政协委员   唐双宁   董事长   中国   三角  

摘要： 一想到经济学、金融学，很多人脑海里马上浮现的是一堆数据和模型，但是在中国光大集团和光大银行董事长唐双宁的眼里，这两者被加入了很多新的元素，哲学、文学、自然科学和社会科学都可以与经济金融十分巧妙地融合在一起。金融“软实力论”、银行监管“四维论”、国有银行改革“三段论”、“形似”“神似”论等等。“矛盾论”视域下的经济金融问题等使唐双宁经常对于金融有着不寻常和巧妙独到的论述、提法。

关键词： 刘易斯二元经济模型   农村剩余劳动力   局限   城乡一体化   政府主导  

摘要： 刘易斯二元经济模型旨在揭示发展中国家通过工业发展吸纳农业剩余劳动力、实现城乡经济一体化的规律,但该理论对实现我国城乡一体化发展具有明显的局限性。因此,实现我国城乡一体化发展,不能完全沿着刘易斯模型提供的路径,应在政府的主导和支持下,理顺农业发展思路,发展现代农业,夯实农村经济发展的产业基础;推进新型村镇体系建设,改善农村的生产生活条件;改革和消除现行的歧农政策,落实农民的国民待遇。

关键词： Amniocentesis   Fertility  

摘要： Medical practitioners typically utilize the following protocol when advising pregnant women about testing for the possibility of genetic disorders with their fetus. Pregnant women over the age of 35 should be tested for Down syndrome and other genetic disorders, while for younger women, such tests are discouraged (or not discussed) as the test can cause a pregnancy to miscarry. The logic appears compelling. The rate at which amniocentesis causes a pregnancy to miscarry is constant while the rate of genetic disorder rises substantially over a woman's reproductive years. Hence the potential benefit from testing being able to terminate a fetus that is known to have a genetic disorder rises with maternal age. This article argues that this logic is incomplete. While the benefits to testing do rise with age, the costs rise as well. Undergoing an amniocentesis always entails the risk of inducing a miscarriage of a healthy fetus. However, these costs are lower at early ages, because there is a higher probability of being able to replace a miscarried fetus with a healthy birth at a later age. We develop and calibrate a dynamic model of amniocentesis choice to explore this tradeoff. For parameters that characterize realistic age patterns of chromosomal abnormalities, fertility rates and miscarriages following amniocentesis, our model implies a falling, rather than rising, rate of amniocentesis as women approach menopause. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： resort life cycle   demand waves   travelling waves   tourism history   Bath  

摘要： There is a large Volume of literature on the life cycle of the tourist resort. However, there is scope to develop this body of work by harnessing recent contributions in the economics literature on cycles or waves in demand. This paper presents a simple economic model of the rise, fall and possible renaissance of the resort. The analysis is based on the work of Cowan et al (1997, 2004), which models waves in consumption when there are interdependencies between consumers. Of particular interest here are the conditions under which we may observe a 'travelling wave', where a new resort starts off as a distinctive and select venue but then, as it grows in Popularity, starts to go downmarket. After the resort has been unfashionable for some time and unattractive associations art: far enough in the past, a new sort of pioneer (accompanied by a new wave of investment) can start off a second wave of popularity. The model presented was motivated by reference to the history of the city of Bath, which enjoyed a long period as a very popular resort and then fell into decline in the 19th century, but enjoyed a renaissance In the mid-20th century to become one of the most Popular medium-sized towns in England.