无限维Heisenberg代数的导子代数

讨论了复数域上无限维Ｈｅｉｓｅｎｂｅｒｇ代数的导干代数与导子代数的完备性．     

The structure of online social networks mirrors those in the offline world

We use data on frequencies of bi-directional posts to define edges (or relationships) in two Facebook datasets and a Twitter dataset and use these to create ego-centric social networks. We explore the internal structure of these networks to determine whether they have the same kind of layered structure as has been found in offline face-to-face networks (which have a distinctively scaled structure with successively inclusive layers at 5, 15, 50 and 150 alters). The two Facebook datasets are best described by a four-layer structure and the Twitter dataset by a five-layer structure. The absolute sizes of these layers and the mean frequencies of contact with alters within each layer match very closely the observed values from offline networks. In addition, all three datasets reveal the existence of an innermost network layer at ∼1.5 alters. Our analyses thus confirm the existence of the layered structure of ego-centric social networks with a very much larger sample (in total, >185,000 egos) than those previously used to describe them, as well as identifying the existence of an additional network layer whose existence was only hypothesised in offline social networks. In addition, our analyses indicate that online communities have very similar structural characteristics to offline face-to-face networks.     

Robust Coplot Analysis

CoPlot analysis is one of the multivariate data-visualizing techniques. It consists of two graphs: the first one represents the distribution of p-dimensional observations over two-dimensional space, whereas the second shows the relations of variables with the observations. At CoPlot analysis, multidimensional scaling (MDS) and Pearson’s correlation coefficient (PCC) are used to obtain a map that demonstrates observations and variables simultaneously. However, both MDS and PCC are sensitive to outliers. When multidimensional dataset contains outliers, interpretation of the map, which is obtained from classical CoPlot analysis, may result in wrong conclusions. At this study, a novel approach to classical CoPlot analysis is presented. By using robust MDS and median absolute deviation correlation coefficient (MADCC), robust CoPlot map is improved. Numerical examples are given to illustrate the merits of the proposed approach. Also, obtained results are compared with the classical CoPlot analysis to emphasize the superiority of introduced robust CoPlot approach.     

The snowball effect of customer slowdown in critical many-server systems

Customer slowdown describes the phenomenon that a customer’s service requirement increases with experienced delay. In healthcare settings, there is substantial empirical evidence for slowdown, particularly when a patient’s delay exceeds a certain threshold. For such threshold slowdown situations, we design and analyze a many-server system that leads to a two-dimensional Markov process. Analysis of this system leads to insights into the potentially detrimental effects of slowdown, especially in heavy-traffic conditions. We quantify the consequences of underprovisioning due to neglecting slowdown, demonstrate the presence of a subtle bistable system behavior, and discuss in detail the snowball effect: A delayed customer has an increased service requirement, causing longer delays for other customers, who in turn due to slowdown might require longer service times.     

Exploring sequences: a graphical tool based on multi-dimensional scaling

Summary.  Sequence analysis has become one of the most used and discussed tools to describe life course trajectories. We introduce a new tool for the graphical exploratory analysis of sequences. Our plots combine standard sequence plots with the results that are provided by multi-dimensional scaling. We apply our procedure to describe work and family careers of Israeli women by using data from the Israel Social Mobility Survey. We first focus on some preliminary choices relative to the definition of the sequences: the age span, the length of the sequences and the set of states registered in each time period. We then describe how our plots can be used to gain insights about the main features of sequences and about the relationships between sequences and external information.     

Prior distributions expressing ignorance about convex increasing failure rates

This paper deals with the specification of probability distributions expressing ignorance concerning annual or otherwise discretized failure or mortality rates, when these rates can safely be assumed to be increasing and convex, but are completely unknown otherwise. Such distributions can be used as noninformative priors for Bayesian analysis of failure data. We demonstrate why a uniform distribution used in earlier work is unsatisfactory, especially from the point of view of insensitivity with respect to the time scale that is chosen for the problem at hand. We suggest alternative distributions based on Dirichlet distributed weights for the extreme points of relevant convex sets, and discuss which consequences a requirement for scale neutrality has for the choice of Dirichlet parameters.     

Hindsight is 20/20: Reflections on the evolution of concept mapping

This paper considers the origins and development of the concept mapping methodology, a summary of its growth, and its influence in a variety of fields. From initial discussions with graduate students, through the rise of the theory-driven approach to program evaluation and the development of a theoretical framework for conceptualization methodology, the paper highlights some of the key early efforts and pilot projects that culminated in a 1989 special issue on the method in Evaluation and Program Planning that brought the method to the attention of the field of evaluation. The paper details the thinking that led to the standard version of the method (the analytic sequence, “bridging” index, and pattern matching) and the development of the software for accomplishing it. A bibliometric analysis shows that the rate of citation continues to increase, where it has grown geographically and institutionally, that the method has been used in a wide variety of disciplines and specialties, and that the literature had an influence on the field. The article concludes with a critical appraisal of some of the key aspects of the approach that warrant further development.     

Aid relief in Haiti after the earthquake: Haitians’ preferences for food and other basic commodities

The earthquake that struck Haiti at the start of 2010 led to impressive international solidarity in the recovery effort. Despite the tons of aid sent to Haiti, relatively little is known about the effectiveness of the aid or about the continuing needs of the Haitians. Using data collected from in‐person surveys with over 1,000 Haitians in two major cities, we sought to quantify some of the impacts of the earthquake while determining people's relative preferences for food and other basic needs in the aftermath of the Haiti earthquake. The results indicate that almost two thirds of Haitians lost a friend to the earthquake, and nearly half lost a family member. People reported spending more on food in the aftermath of the earthquake, and the level of food aid received does not appear to have any impact on food expenditures. Among different types of aid, Haitians stated being most in need of a job—something difficult for international aid agencies to supply over the long run. They also indicated that quality of life would be most improved by education. The lessons learned in Haiti may prove useful in addressing future natural disasters.     

Reanalysis of the Chechile-Cooke Experiment: Correcting for Mismatched Gambles

Chechile and Cooke (1997) experimentally tested a broad class of utility models subsumed under the Miyamoto (1988, 1992) generic utility theory. The Chechile and Cooke study required participants to match on each trial, a fully specified reference gamble to a partially specified comparison gamble by adjusting the probability of a win on the comparison gamble. The Chechile and Cooke experiment, however, contained a subset of trials which were intrinsically unmatchable. In such cases, the participants could only give an extreme probability (either 0 or 1). In this paper, those extreme trials were omitted and the results from the experiment reanalyzed. Despite the mismatch problem, the conclusions of the Chechile and Cooke experiment were again supported. For nine implementations of generic utility there is model failure due to the systematic variation of a parameter that should be a constant.     

广义Haar子波

研究了最简单的规范正交子波棗Haar子波的简单广义化问题首先提出尺度系数函数新概念并引进时移因子将Haar子波进行拓展而得到一类新的规范正交子波广义Haar子波从理论上论证这种简单广义化方法的合理性与广义Haar子波的一些基本性质给出了广义子波系在时域和频域的闭式表达