Adolescent Sibling Relationship Quality and Adjustment: Sibling Trustworthiness and Modeling,as Factors Directly and Indirectly Influencing These Associations

The main goal of this study was to examine the direct and moderating effects of trustworthiness and modeling on adolescent siblings' adjustment. Data were collected from 438 families including a mother, a younger sibling in fifth, sixth, or seventh grade (M = 11.6 years), and an older sibling (M = 14.3 years). Respondents completed Web‐based surveys describing sibling conflict and warmth. Siblings reported on trustworthiness and modeling, and mothers described adjustment. Sibling conflict was directly associated with internalizing and externalizing behaviors for both siblings. The older siblings' reports of trustworthiness were directly associated with the outcome measures. The younger siblings' reports of trustworthiness were less directly associated, but a possible salutary effect was most evident under the highest levels of sibling conflict or warmth. Higher sibling modeling was a risk factor for adjustment problems in relations characterized by high conflict. Results support exploring trustworthiness as a key dimension of sibling relations.     

A Bayesian model for estimating the malaria transition probabilities considering individuals lost to follow-up

It is known that patients may cease participating in a longitudinal study and become lost to follow-up. The objective of this article is to present a Bayesian model to estimate the malaria transition probabilities considering individuals lost to follow-up. We consider a homogeneous population, and it is assumed that the considered period of time is small enough to avoid two or more transitions from one state of health to another. The proposed model is based on a Gibbs sampling algorithm that uses information of lost to follow-up at the end of the longitudinal study. To simulate the unknown number of individuals with positive and negative states of malaria at the end of the study and lost to follow-up, two latent variables were introduced in the model. We used a real data set and a simulated data to illustrate the application of the methodology. The proposed model showed a good fit to these data sets, and the algorithm did not show problems of convergence or lack of identifiability. We conclude that the proposed model is a good alternative to estimate probabilities of transitions from one state of health to the other in studies with low adherence to follow-up.     

基于产业集群的企业重点投资地区决策的仿真

用多Agent仿真技术,研究了基于产业集群的台资IT企业在大陆重点投资地区的决策问题。提出了针对这一问题的、将集群竞争力评价的GEM模型、多Agent仿真技术及演化博弈相结合的思路与方法。仿真模型对集群的研究方法以及多Agent的应用领域有拓展意义,而仿真发现与结论可为政府制定有关政策提供参考。     

关于非数学专业的微积分教学改革

本文认为,当前非数学专业的微积分教学改革,应特别强调微积分的数学建模方法和计算功能,强调对数学原理和背景的介绍.为此,作者以"启发应用意识,提高应用能力"为宗旨,提出从教材到教学法直至成绩考核方法的一整套教学改革方案.     

论化学实验过程中的理论思维

化学实验不是一种纯粹的感性认识过程,它是在理论思维的指导下对化学的自然本质进行“解剖”的过程,是理论思维的物化。     

Effects of the Mechanism of Receptor-Mediated Gene Expression on the Shape of the Dose-Response Curve

A mathematical model of receptor-mediated gene expression that includes receptor binding of natural and xenobiotic ligands, protein synthesis and degradation, and metabolism of the xenobiotic ligand was created to identify the determinants of the shape of the dose-response profile. Values of the model's parameters were varied to reflect alternative mechanisms of expression of the protein. These assumptions had dramatic effects on the computed response to a bolus dose of the xenobiotic ligand. If all processes in the model exhibit hyperbolic kinetics, the dose-response curves can appear sigmoidal but actually be linear with a positive slope at low doses. The slope of the curve only approached zero at low dose, indicative of a threshold for response, if binding of the xenobiotic ligand to the receptor exhibited positive cooperativity (ligand binding at one site increases the affinity for ligand at another binding site on the receptor). Positive cooperativity in the rate-limiting step of protein synthesis produced dose-response curves which were "U-shaped" at low doses, also indicative of a threshold. Positive cooperativity in the metabolism of the xenobiotic ligand produced dose-response curves that increased more rapidly than linearly with increasing dose. The model illustrates the fact that response cannot be predicted from qualitative mechanistic arguments alone; any assessment of risk to health from xenobiotic chemicals must be based on a detailed quantitative examination of the kinetic behavior of each chemical species individually.     

Uncertainties in Pharmacokinetic Modeling for Perchloroethylene: II. Comparison of Model Predictions with Data for a Variety of Different Parameters

In this paper we compare expectations derived from 10 different human physiologically based pharmacokinetic models for perchloroethylene with data on absorption via inhalation, and concentrations in alveolar air and venous blood. Our most interesting finding is that essentially all of the models show a time pattern of departures of predictions of air and blood levels relative to experimental data that might be corrected by more sophisticated model structures incorporating either (a) heterogeneity of the fat compartment (with respect to either perfusion or partition coefficients or both) or (b) intertissue diffusion of perchloroethylene between the fat and muscle/VRG groups. Similar types of corrections have recently been proposed to reduce analogous anomalies in the fits of pharmacokinetic models to the data for several volatile anesthetics.^(17-20) A second finding is that models incorporating resting values for alveolar ventilation in the region of 5.4 L/min seemed to be most compatible with the most reliable set of perchloroethylene uptake data.     

Floods and Climate Change: Interactions and Impacts

Whether the floods experienced during the last decade in Germany and in other European countries are triggered or worsened by human activities has been the subject of a great deal of debate. Possible anthropogenic activities leading to increased flood risk include river regulation measures, intensified land use and forestry, and emissions of greenhouse gases causing a change in the global climate. This article discusses the latter by reviewing the existing knowledge on the subject. First, the relevance, capabilities, and limitations of climate models for the simulation and analysis of flood risk under aspects of the anthropogenic climate change are described. Special consideration is given here to differences between the "typical" spatial scale of climate models and hydrological flood models. Second, observations of trends in climate variables relevant for river flooding issues are summarized. Special emphasis is put on the Rhine and other German catchment areas. Third, the possibilities of modeling the different parts of the "cascade of flood risk" are summarized, introducing the special features of meteorological, hydrological, and river hydraulic models.     

利用智能主体分析"时尚"的涌现

时尚作为一种社会现象,是由个别人物的倡导和示范,先在少数人中流行,然后迅速蔓延到社会.多数人出于新奇与从众心理而仿效.对于它的研究有助于人们把握这种社会现象的产生与蔓延过程,深入认识和控制它的发展.由于它的复杂多样性,当前还缺乏对它的定量分析与研究.论文利用基于智能主体的仿真方法,分析了时尚的涌现过程.文中建立了两种模型,用于确定公众能否接受某种时尚的临界值.一种模型基于公众能获取全部信息,另一种则基于个人只能获取邻近信息.