建设回应型政府——和谐社会背景下政府改革的重要目标

政府回应性是当代政府改革普遍追求的重要目标,政府回应性与我国构建和谐社会的指导思想与总要求以及社会管理新格局等相互契合,突出政府回应性是构建和谐社会的内在要求,因此,和谐社会背景下的政府改革有必要将建设回应型政府作为目标之一。而我国的根本指导思想、有关法制安排和近几年政府改革的的实践,使得建设回应型政府具备一定的理论思想、法制和实践基础,现代电子技术、信息技术和互联网络的发展及其在公共管理中的应用——电子政务的发展,也为建设回应型政府提供了相应的物质技术条件,建设回应型政府不仅必要而且可行。     

Human Salmonellosis: Estimation of Dose-Illness from Outbreak Data

The quantification of the relationship between the amount of microbial organisms ingested and a specific outcome such as infection, illness, or mortality is a key aspect of quantitative risk assessment. A main problem in determining such dose-response models is the availability of appropriate data. Human feeding trials have been criticized because only young healthy volunteers are selected to participate and low doses, as often occurring in real life, are typically not considered. Epidemiological outbreak data are considered to be more valuable, but are more subject to data uncertainty. In this article, we model the dose-illness relationship based on data of 20 Salmonella outbreaks, as discussed by the World Health Organization. In particular, we model the dose-illness relationship using generalized linear mixed models and fractional polynomials of dose. The fractional polynomial models are modified to satisfy the properties of different types of dose-illness models as proposed by Teunis et al . Within these models, differences in host susceptibility (susceptible versus normal population) are modeled as fixed effects whereas differences in serovar type and food matrix are modeled as random effects. In addition, two bootstrap procedures are presented. A first procedure accounts for stochastic variability whereas a second procedure accounts for both stochastic variability and data uncertainty. The analyses indicate that the susceptible population has a higher probability of illness at low dose levels when the combination pathogen-food matrix is extremely virulent and at high dose levels when the combination is less virulent. Furthermore, the analyses suggest that immunity exists in the normal population but not in the susceptible population.     

An Adjustment Factor for Mode-of-Action Uncertainty with Dual-Mode Carcinogens: The Case of Naphthalene-Induced Nasal Tumors in Rats

The U.S. Environmental Protection Agency (USEPA) guidelines for cancer risk assessment recognize that some chemical carcinogens may have a site-specific mode of action (MOA) involving mutation and cell-killing-induced hyperplasia. The guidelines recommend that for such dual MOA (DMOA) carcinogens, judgment should be used to compare and assess results using separate linear (genotoxic) versus nonlinear (nongenotoxic) approaches to low-level risk extrapolation. Because the guidelines allow this only when evidence supports reliable risk extrapolation using a validated mechanistic model, they effectively prevent addressing MOA uncertainty when data do not fully validate such a model but otherwise clearly support a DMOA. An adjustment-factor approach is proposed to address this gap, analogous to reference-dose procedures used for classic toxicity endpoints. By this method, even when a nonlinear toxicokinetic model cannot be fully validated, the effect of DMOA uncertainty on low-dose risk can be addressed. Application of the proposed approach was illustrated for the case of risk extrapolation from bioassay data on rat nasal tumors induced by chronic lifetime exposure to naphthalene. Bioassay data, toxicokinetic data, and pharmacokinetic analyses were determined to indicate that naphthalene is almost certainly a DMOA carcinogen. Plausibility bounds on rat-tumor-type-specific DMOA-related uncertainty were obtained using a mechanistic two-stage cancer risk model adapted to reflect the empirical link between genotoxic and cytotoxic effects of the most potent identified genotoxic naphthalene metabolites, 1,2- and 1,4-naphthoquinone. Bound-specific adjustment factors were then used to reduce naphthalene risk estimated by linear extrapolation (under the default genotoxic MOA assumption), to account for the DMOA exhibited by this compound.     

Sensitivity Analysis of Model Output with Input Constraints: A Generalized Rationale for Local Methods

In this work, we introduce a generalized rationale for local sensitivity analysis (SA) methods that allows to solve the problems connected with input constraints. Several models in use in the risk analysis field are characterized by the presence of deterministic relationships among the input parameters. However, SA issues related to the presence of constraints have been mainly dealt with in a heuristic fashion. We start with a systematic analysis of the effects of constraints. The findings can be summarized in the following three effects. (i) Constraints make it impossible to vary one parameter while keeping all others fixed. (ii) The model output becomes insensitive to a parameter if a constraint is solved for that parameter. (iii) Sensitivity analysis results depend on which parameter is selected as dependent. The explanation of these effects is found by proposing a result that leads to a natural extension of the local SA rationale introduced in Helton (1993) . We then extend the definitions of the Birnbaum, criticality, and the differential importance measures to the constrained case. In addition, a procedure is introduced that allows to obtain constrained sensitivity results at the same cost as in the absence of constraints. The application to a nonbinary event tree concludes the article, providing a numerical illustration of the above findings.     

浅析完全学分制下的学生管理模式

随着高等教育事业的发展和招生规模的扩大 ,高校学生工作正面临着机遇和挑战。本文立足于本校的实际情况 ,对在完全学分制下建立三种新的学生管理模式 ,进行了有益的探索。     

网络文学的兴起与文学创作模式的嬗变

随着互联网的蓬勃发展 ,文学网站、网络文学频道及个人文学主页应运而生。它为网络写手、网民中的文学读者、网络文学评论家提供了与传统文学迥异的在线写作、在线阅读、在线评论这种新的文学活动方式和文学活动空间。网络文学蔚然兴起。它具有的革命性意义是突破了传统的文学创作模式 ,实现了从口头文学创作到书面文学创作再到网络文学创作的质的变化     

“以支定收”还是“以收定支”:我国财政收支关系的实证研究

通过对我国财政收入与支出的时序变量建立协整与误差修正模型,实证研究我国的财政收支关系中到底是以支定收还是以收定支,确定这种收支之间的因果关系对采取财政政策的借鉴意义。研究将回答,我国财政收入是财政支出之间是单向格兰杰因还是双向格兰杰因,抑或互非因果关系,并在此基础上指出财政政策的作用方向,为真正建立符合的现代市场经济的财政观提供经验证据。     

Tests and Confidence Intervals for an Extended Variance Component Using the Modified Likelihood Ratio Statistic

Abstract.  The large deviation modified likelihood ratio statistic is studied for testing a variance component equal to a specified value. Formulas are presented in the general balanced case, whereas in the unbalanced case only the one-way random effects model is studied. Simulation studies are presented, showing that the normal approximation to the large deviation modified likelihood ratio statistic gives confidence intervals for variance components with coverage probabilities very close to the nominal confidence coefficient.     

Issue management and crisis management: An integrated,non-linear,relational construct

Despite extensive attempts to define and differentiate issue management and crisis management, the definitional approach – and linear life-cycle models which focus on the elements – fail to capture the full dynamics of the disciplines. Instead of a focus on definitions, this paper proposes a non-linear, relational construct which considers issue and crisis management in the context of interdependent activities and clusters of activity which must be managed at different stages. This includes the role of issue management in both the pre-crisis and post-crisis phases. The model addresses some of the limitations of linear approaches and helps analyze the outcomes and overlaps between activity clusters in order to optimize strategic relationships and enhance bottom-line effectiveness.     

A model for collaboration networks giving rise to a power-law distribution with an exponential cutoff

Recently several authors have proposed stochastic evolutionary models for the growth of complex networks that give rise to power-law distributions. These models are based on the notion of preferential attachment leading to the “rich get richer” phenomenon. Despite the generality of the proposed stochastic models, there are still some unexplained phenomena, which may arise due to the limited size of networks such as protein, e-mail, actor and collaboration networks. Such networks may in fact exhibit an exponential cutoff in the power-law scaling, although this cutoff may only be observable in the tail of the distribution for extremely large networks. We propose a modification of the basic stochastic evolutionary model, so that after a node is chosen preferentially, say according to the number of its inlinks, there is a small probability that this node will become inactive. We show that as a result of this modification, by viewing the stochastic process in terms of an urn transfer model, we obtain a power-law distribution with an exponential cutoff. Unlike many other models, the current model can capture instances where the exponent of the distribution is less than or equal to two. As a proof of concept, we demonstrate the consistency of our model empirically by analysing the Mathematical Research collaboration network, the distribution of which has been shown to be compatible with a power law with an exponential cutoff.