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1.
根据我国已建成通车的高等级公路的使用情况,从路基施工前准备、路基施工、台背处理、路面施工及路表面排水处理等方面较全面地分析了水泥混凝土路面破坏的原因及其防治。  相似文献   
2.
The magnitude 7.0 earthquake that struck Haiti in January 2010 led to an unprecedented effort in collecting and providing geographical information in support of humanitarian aid. Although most of the compiled datasets and generated maps were able to provide specific and detailed information regarding the location of damaged buildings and road interruptions, none or little information was available to describe the accessibility—or otherwise—of the urban space. Here we try to offer an alternative method to define the urban accessibility landscape in the aftermath of earthquake damage, by combining simple graph theory concepts and GIS-based spatial analysis to assess how the urban space accessibility decreases when the road network is damaged.  相似文献   
3.
Evaluating agricultural programmes requires considering not only the programmes’ influence on input and output indicators, but also considering the relationship between these indicators as embodied in the production technology. This article examines the impact on production of an intervention in the Ecuadorian Sierra designed to improve returns to potato production through training and through linking smallholders to high‐value markets. Critical to identifying the impact of the programme is the careful construction of a counterfactual and meticulous data collection. To assess the impact of the programme on production, a weighted estimation, where weights are constructed through propensity score matching, is employed to estimate a production function within a damage abatement framework. The function incorporates a series of interaction terms to assess the impact of the programme on the production technology. The findings provide evidence that the programme enhances yields both through a general shift in technology as well as increased input use. The results suggest that the use of effective farming techniques that are learned through the programme induce this technological shift.  相似文献   
4.
Using store-level scanner data, elasticity matrices are estimated using a twotiered demand system. Two basic models are estimated, one with promotion variables and one without. Differences between the estimates across the two models are statistically significant. However, when the elasticities are used as 'inputs' into several simulation exercises, there are only small differences in merger effects and patent damage estimates.The results suggest that the differences are not 'economically' significant.  相似文献   
5.
In calculating damages in healthcare antitrust cases, the difference-in-differences (DID) approach provides a potentially valuable means of controlling for lawful factors that influence prices, such as case mix and quality of care, as distinct from price differentials due to unlawful behavior. After comparing DID to traditional methods of estimating damages, this paper uses DID to analyze data from a well-known case against Marshfield Clinic, a large multi-specialty group practice that was found to have illegally allocated markets for physician services in Central Wisconsin. Using a specification similar to what was used in the case, we find that illegal behavior accounted for about one-half of the Clinic’s extra increase in costs per patient during the damage period. The courts, however, were not persuaded that the analysis adequately controlled for legal factors. We discuss potential pitfalls in using DID to estimate damages suggested by the case, as well as possible ways around them.  相似文献   
6.
从1996年起,中国已经连续11年成为世界反倾销头号目标国。贵州省虽然属于西南欠发达省份,但是同国内沿海经济发达地区一样,面临同样的国际市场和同样的反倾销的严峻形势。针对贵州出口涉外企业遭遇的反倾销调查情况进行研究,着重分析了参与应诉的企业和案件,并提出贵州企业应对国外反倾销的策略。  相似文献   
7.
通过彗星电泳法检测样品单细胞DNA损伤从而鉴别辐照食品。[方法]选取12种食品基质,经1KGy、3KGy、5KGy、7KGy、10KGy剂量辐照后,进行彗星电泳检测,并对检测时效性进行研究。[结果]除熟制鸡肉外,其他样品均可通过彗星电泳法检测到辐照状况,检测灵敏度达lKGy辐照剂量;辐照产生的DNA损伤具有明显的剂量-效应关系,以TL、TDNA%指标分析存在平台期,以TM、OTM指标分析则不存在平台期:辐照后6h-5d均可检测到明显的彗星图像。[结论]彗星电泳法适用于除熟制食品外的含DNA食品的辐照检测,方法稳定性好,检测灵敏度高。  相似文献   
8.
大豆食心虫的危害程度是由虫食率来决定的,影响大豆食心虫虫食率的因素很多,以往对虫食率的预测方法只是基于定量变量,并且要求预测数据准确,然而影响害虫的危害程度的因素除定量因素外,还有许多定性因素,本文考虑影响大豆食心虫虫食率的定量因素:上年平均脱荚孔数、上年9月(中下旬)平均气温、上年9月份(中下旬)降水量、上年10月份(上旬)降水量、当年7月份平均气温、当年7月份降水量以及当年7月份湿度作自变量和定性因素:大豆品种、幼虫越冬存活率和8月分平均百米蛾量(观测误差较大的数据做为定性变量来考虑),以当年的虫食率作为基准变量建立数量化理论模型,增加了数据资料信息的应用,取得了精确的预测结果,对实际工作有一定的指导意义。  相似文献   
9.
Should a provider deliver a reliable service or should it allow for occasional service failures? This paper derives conditions under which randomizing service quality can benefit the provider and society. In addition to cost considerations, heterogeneity in customer damages from service failures allows the provider to generate profit from selling damage prevention services or offering compensation to high-damage customers. This strategy is viable even when reputation counts and markets are competitive.  相似文献   
10.
Using a vertically differentiated product model, this paper examines welfare implications of various government policies in a situation where consumers are environmentally discerning. It studies ad valorem taxes/subsidies and emission taxes. The optimal policy depends on the magnitude of damage parameter associated with environmental externality. For a given distribution of tastes and preferences, as the damage parameter increases from a low to a high value, the optimal policy shifts from an ad valorem tax to an ad valorem subsidy. It also shows that for a sufficiently low damage parameter, an ad valorem tax dominates an emission tax.  相似文献   
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