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91.
基于政府和企业视角, 对中国矿产资源利益分配的研究成果加以梳理, 发现资源企业在获得超额利润的同时, 也承受着过重的税收负担, 而资源税费制度的设计缺陷是导致政府和企业资源利益分配错位的根本原因, 其体现在定性不明确、定位不合理、计税不科学、分配有欠缺, 为调整利益分配格局, 资源税是改革之重。现有文献以规范性研究为主, 缺乏对矿产资源税费结构和税费率的整体优化研究, 以及改革后果的预测性研究, 在矿产资源税费制度重构的理论依据上尚存分歧。为此, 认为未来的研究方向有:构建矿产资源税费制度设计的理论框架;对资源企业盈余的性质和数量予以确认和计量;比较研究资源税费的不同计税依据;优化研究资源税费结构和税费率。  相似文献   
92.
Case-control family data are now widely used to examine the role of gene-environment interactions in the etiology of complex diseases. In these types of studies, exposure levels are obtained retrospectively and, frequently, information on most risk factors of interest is available on the probands but not on their relatives. In this work we consider correlated failure time data arising from population-based case-control family studies with missing genotypes of relatives. We present a new method for estimating the age-dependent marginalized hazard function. The proposed technique has two major advantages: (1) it is based on the pseudo full likelihood function rather than a pseudo composite likelihood function, which usually suffers from substantial efficiency loss; (2) the cumulative baseline hazard function is estimated using a two-stage estimator instead of an iterative process. We assess the performance of the proposed methodology with simulation studies, and illustrate its utility on a real data example.  相似文献   
93.
A pioneer first enters the market as the monopolist and later experiences the competition when a similar product is brought to the market by the competitor. In 2012, Wang and Xie suggested to decompose the pioneer survival to “monopoly” and “competition” durations and estimate the two survivals of the pioneer individually with the competitor's survival via regression analysis. In their article, several regression analyses were performed to study the effect of order entry to the pioneer and the later entrant in different market status. Using the same datasets from their study, our main interest is to investigate the interdependent relationship between two competitive firms and study whether the market pioneer and the later entrant can benefit from the competition. The major contribution of this article is that the interdependence between two competitive firms is explicitly expressed and three survival durations can be estimated in one model. The proposed method relates the survival times of two competitive firms to pioneer's monopoly time and some observable covariates via proportional hazard model, and incorporates frailty variables to capture the interdependence in the competition. This article demonstrates a new method that formulates the interdependence between competitive firms and shows data analyses in the industries of newspapers and high technology.  相似文献   
94.
金融衍生品在金融市场的风险管理中扮演着越来越重要的角色,但是由于其所具有的高杠杆性特点,也大大增加了风险发生的可能性。投资者的内部治理和行业自律不能有效地治理衍生品交易带来的风险。衍生品交易的高关联性特征使得交易产生的风险很容易迅速的扩大和蔓延,而衍生品交易越来越强的国际化特征更加剧了这一点。要有效治理国际金融衍生品交易的风险,必须加强监管的国际协调与合作,实行国际多边治理机制。  相似文献   
95.
96.
Ecstasy (MDMA) has been added to the spectrum of illicit drugs used by college students. In this study, the authors estimated the prevalence of ecstasy use within a large college student sample and investigated the polydrug-use history of those ecstasy users. They administered an anonymous questionnaire to college students (N = 1,206) in classrooms at a large university in the mid-Atlantic United States. The overall student response rate was 91%. Nine percent of the sample reported lifetime ecstasy use. Because 98% of ecstasy users had used marijuana, the authors compared polydrug use between ecstasy users and individuals who had used marijuana but not ecstasy. Ecstasy users, as compared with these marijuana users, were significantly more likely to have used inhalants (38% vs. 10%), LSD (38% vs. 5%), cocaine (46% vs 2%), and heroin (17% vs 1%) in the past year. Significant polydrug use among college student ecstasy users has important implications for their substance abuse treatment.  相似文献   
97.
In this paper, we investigate a single-machine problem with the learning effect and release times where the objective is to minimize the makespan. A branch-and-bound algorithm incorporating with several dominance properties and lower bounds is developed to derive the optimal solution. A heuristic algorithm is proposed to obtain a near-optimal solution. The computational experiments show that the branch-and-bound algorithm can solve instances up to 36 jobs, and the average error percentage of the proposed heuristic is less than 0.11%.  相似文献   
98.
We propose inverse probability weighted estimators for the local average treatment effect (LATE) and the local average treatment effect for the treated (LATT) under instrumental variable assumptions with covariates. We show that these estimators are asymptotically normal and efficient. When the (binary) instrument satisfies one-sided noncompliance, we propose a Durbin–Wu–Hausman-type test of whether treatment assignment is unconfounded conditional on some observables. The test is based on the fact that under one-sided noncompliance LATT coincides with the average treatment effect for the treated (ATT). We conduct Monte Carlo simulations to demonstrate, among other things, that part of the theoretical efficiency gain afforded by unconfoundedness in estimating ATT survives pretesting. We illustrate the implementation of the test on data from training programs administered under the Job Training Partnership Act in the United States. This article has online supplementary material.  相似文献   
99.
Monitoring a failure process and measuring its performance are important issues for complex nonrepairable and repairable systems. For a highly reliable process, traditional methods for reliability monitoring and performance measuring become inapplicable. This paper proposes a new two-phase controlling method for monitoring and measuring an Erlang-failure process (EFP). In the first-phase controlling method, a control chart is used to monitor the EFP condition. When special causes of variation have been removed from the EFP and all of the failure times plotted on the control chart lie within the control limits, the EFP is considered to be in control. However, the in-control EFP still likely carries out bad or out-of-lifetime-specification conditions. Thus, its lifetime-specification limit is taken into consideration as the second-phase controlling method for measuring the in-control EFP performance. We propose a lifetime-capability index. Its value has a one-to-one corresponding relationship with the lifetime-conforming rate, which indicates the lifetime performance of this EFP. Without collecting additional data efforts, in-control data gathered from the control chart in the first phase is employed to estimate the lifetime-capability index. To realize main lifetime-capability of the EFP impacting on downstream customers, the lower confidence bound of the estimate of the lifetime-capability index, capturing its minimum lifetime capability, is considered. The advantage of this two-phase method for controlling the failure processes can motivate the manufacturer to develop a reliability-monitoring technique, establish an adequate reliability improvement program and implement an appropriate analysis to ensure its lifetime performance meeting the customers requirement.  相似文献   
100.
This study investigated the developmental continuity, stability, and organization of infants' behavioral response to mild stress from 1 to 3 months of age. Changes in infant stress reactivity were expected to coincide with a suspected neurobiological shift around the 2nd month. A total of 53 infants and their mothers participated in this study. At 1 and 3 months, infants' stress reactivity to mild perturbation was assessed by withdrawing a pacifier during nonnutritive sucking. Infant baseline heart rate activity and maternal reports of infant temperament were also obtained. Focusing on facial and vocal negativity, behavioral measures of infant reactivity to pacifier withdrawal were coded from videos. Results showed that developmental continuity and individual instability characterized changes in infant stress reactivity over the 2nd‐month transition. Developmental reorganization was also evidenced by changes in the direction and magnitude of infant stress reactivity in relation to baseline heart period and maternal temperament ratings, respectively. These findings provide direct supporting evidence for the contention that changes in infant stress reactivity to mild perturbation may be a function of developmental shifts in underlying neurobiological mechanisms in early infancy.  相似文献   
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