假日旅游收入成本和消费分析

"黄金周"的出现,开启了居民假日旅游的热潮,假日旅游的收入成本和消费分析,揭示出"虚增旅游成本的负面影响",提出了"分流"和"合理配置资源"解决对策。     

Comparative Potency Method for Cancer Risk Assessment: Application to Diesel Particulate Emissions1

An estimation of the human lung cancer “unit risk” from diesel engine particulate emissions has been made using a comparative potency approach. This approach involves evaluating the tumorigenic and mutagenic potencies of the particulates from four diesel and one gasoline engine in relation to other combustion and pyrolysis products (coke oven, roofing tar, and cigarette smoke) that cause lung cancer in humans. The unit cancer risk is predicated on the linear nonthreshold extrapolation model and is the individual lifetime excess lung cancer risk from continuous exposure to 1 μg carcinogen per m³ inhaled air. The human lung cancer unit risks obtained from the epidemiologic data for coke oven workers, roofing tar applicators, and cigarette smokers were, respectively, 9.3 × 10^?4, 3.6 × 10^?4, and 2.2 × 10^?6 per μg particulate organics per m³ air. The comparative potencies of these three materials and the diesel and gasoline engine exhaust particulates (as organic extracts) were evaluated by in vivo tumorigenicity bioassays involving skin initiation and skin carcinogenicity in SENCAR mice and by the in vitro bioassays that proved suitable for this analysis: Ames Salmonella microsome bioassay, L5178Y mouse lymphoma cell mutagenesis bioassay, and sister chromatid exchange bioassay in Chinese hamster ovary cells. The relative potencies of the coke oven, roofing tar, and cigarette smoke emissions, as determined by the mouse skin initiation assay, were within a factor of 2 of those determined using the epidemiologic data. The relative potencies, from the in vitro bioassays as compared to the human data, were similar for coke oven and roofing tar, but for the cigarette smoke condensate the in vitro tests predicted a higher relative potency. The mouse skin initiation bioassay was used to determine the unit lung cancer risk for the most potent of the diesel emissions. Based on comparisons with coke oven, roofing tar, and cigarette smoke, the unit cancer risk averaged 4.4 × 10^?4. The unit lung cancer risks for the other, less potent motor-vehicle emissions were determined from their comparative potencies relative to the most potent diesel using three in vitro bioassays. There was a high correlation between the in vitro and in vivo bioassays in their responses to the engine exhaust particulate extracts. The unit lung cancer risk per μg particulates per m³ for the automotive diesel and gasoline exhaust particulates ranged from 0.20 × 10^?4 to 0.60 × 10^?4; that for the heavy-duty diesel engine was 0.02 × 10^?4. These unit risks provide the basis for a future assessment of human lung cancer risks when combined with human population exposure to automotive emissions.     

On rates of convergence to infinitely divisible laws for dependent random variables

Large O and small o approximations of the expected value of a class of functions (modified K-functional and Lipschitz class) of the normalized partial sums of dependent random variables by the expectation of the corresponding functions of infinitely divisible random variables have been established. As a special case, we have obtained rates of convergence to the Stable Limit Laws and to the Weak Laws of Large Numbers. The technique used is the conditional version of the operator method of Trotter and the Taylor expansion.     

冯友兰方法论与朱熹工夫论

冯友兰先生的方法论有三个层次,即修养方法("求觉解"、"敬与集义")、新理学方法("正的方法"、"负的方法")、哲学史研究方法("抽象继承法").其新理学方法主要是指求觉解的方法,或者说是使人得到最高的天地境界的方法,不包括<新原人> 中所说的使人常住于道德和天地境界的"敬与集义".冯先生方法论受到朱熹工夫论的深刻影响.     

The Independence Number of Graphs with a Forbidden Cycle and Ramsey Numbers

Let k 5 be a fixed integer and let m = (k – 1)/2. It is shown that the independence number of a C _k-free graph is at least c ₁[ d(v)^{1/(m – 1)}]^{(m – 1)/m} and that, for odd k, the Ramsey number r(C _k, K _n) is at most c ₂(n ^{m + 1}/log n)^1/m , where c ₁ = c ₁(m) > 0 and c ₂ = c ₂(m) > 0.     

基于生存分析的边境地区人口外流及影响研究

本文依据国家计生委2011年对吉林省中朝边境地区人口流动的抽样调查数据,运用非参数及半参数的生存分析模型对外流人口特征、流动影响因素进行研究,同时分析了人口外流对该地区经济及社会发展的影响。实证结果表明：年轻、受过良好教育的个体是外流人口中的主力,且韩国为其主要流入地;民族因素显著的影响个体选择,但性别影响并不显著;最后,尽管外出个体汇款对该地区GDP有一定贡献,但劳动力的严重流失不仅抑制了当地经济长期发展,同时也导致了人口老龄化等社会问题。因此,为了发展地方特色经济,当地政府在为吸引高端人才、招商引资创造条件的同时,还应采取措施避免受过良好教育的劳动力进一步外流,以期促进当地经济持续发展。     

基于模糊综合评价的高校贫困生认定方法研究

当前,针对贫困生认定问题,我国尚未给出明确的认定办法和标准,各高校所采用的认定办法也存在着诸多缺点和不足。模糊综合评价法应用于高校贫困生认定,综合考虑影响学生困难程度的各方面因素,建立定性与定量相结合的贫困生认定指标体系,进行三层逐级模糊综合评判,减弱人为因素的影响,明确判定贫困生的困难等级,提高了认定结果的科学性和准确性。     

空间面板杜宾模型的Bootstrap Wald-COMFAC检验研究

将共同因子约束(COMFAC)的Wald检验问题引入到空间面板模型中,讨论空间面板杜宾模型与空间面板误差模型的识别问题。蒙特卡洛模拟表明:在有限样本下,基于渐近临界值的Wald检验有着良好的检验功效,但存在着较为严重的尺度扭曲。进一步采用残差Bootstrap方法,在不损失检验功效的前提下,能够显著地降低检验的尺度扭曲。因此,残差Bootstrap方法是更为有效的检验方法。     

综合评价中一种凹性指数型功效函数

目前主流功效函数多为凸性,在处理社会经济数据集中常见的右偏样本时效果难以令人满意。通过系统探讨凸性和凹性功效函数各自的适用特征,指出凹性函数在应用中有其必要性。归纳并使用偏度、区分度、P-P图三种方法作为分布形态的评判标准,比较了常见功效函数对指标原始数据分布形态的调整作用。在分析基础上,提出一种改进的凹性指数功效函数,能有效地处理右偏数据,且相比使用对数预处理的凸性功效函数更具适用性与便利性。     

中国生猪养殖业规模化影响因素研究

在中国农业产业中,养殖业率先进入规模化发展阶段。基于1998-2011年省际面板数据,运用FGLS法考察生猪养殖规模化的决定因素,发现技术进步、规模经济效益、饲料加工业发育、城乡猪肉消费、交通条件、劳动力非农化、劳动力文化水平以及财政支持政策对规模化具有显著影响。进一步利用回归分解法识别关键因子,结果表明,规模化发展主要取决于四股力量,其中市场拉力是主要的源动力,而交通条件和劳动力文化素质则是重要支撑力,生产扶持政策也形成一定推力,四者的贡献率分别为27%、19%、10%和3%。