Efficient PageRank approximation via graph aggregation

We present a framework for approximating random-walk based probability distributions over Web pages using graph aggregation. The basic idea is to partition the graph into classes of quasi-equivalent vertices, to project the page-based random walk to be approximated onto those classes, and to compute the stationary probability distribution of the resulting class-based random walk. From this distribution we can quickly reconstruct a distribution on pages. In particular, our framework can approximate the well-known PageRank distribution by setting the classes according to the set of pages on each Web host. We experimented on a Web-graph containing over 1.4 billion pages and over 6.6 billion links from a crawl of the Web conducted by AltaVista in September 2003. We were able to produce a ranking that has Spearman rank-order correlation of 0.95 with respect to PageRank. The clock time required by a simplistic implementation of our method was less than half the time required by a highly optimized implementation of PageRank, implying that larger speedup factors are probably possible. Significant portions of the work presented here were done while A. Broder and R. Lempel were employed by the AltaVista corporation.     

HIGH PRESSURE TREATMENT OF SWISS CHEESE SLURRIES (I): INACTIVATION OF SELECTED MICROORGANISMS AFTER TREATMENT AND DURING ACCELERATED RIPENING

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How do we do this: learning how to teach socioscientific issues

Cultural Studies of Science Education - Socioscientific Issues (SSI) provide a strong framework for engaging students and teachers in meaningful and relevant scientific discourse in the development...     

An introduction to minority health resources on the World Wide Web

Health care professionals and consumers often need information about, or targeted to, non-White or non-English speaking populations. Minority health resources sponsored by a variety of organizations are increasingly being made available on the World Wide Web. This information is easily accessible to providers, patients, and families, and community service agencies. The heterogeneity of sponsors, ranging from federal agencies to consumer advocacy and support groups- and their agendas-results in differences of quality, depth of content, and suitability for different information seekers. Taking a conservative approach, this article presents a collection of starting points whose roots are in established agencies, institutions, and organizations already familiar to most health care information professionals.     

Biological applications of the “Filtered” Van der Pol oscillator

The present article deals with the development of an oscillatory model, which generates waveforms corresponding to ECG patterns. The present oscillatory system relies on coupling of oscillators derived from the famous VDP oscillator. We demonstrate that inducing a relaxation type of dynamics in the models contributes to their successful generation of ECG like signals. Furthermore, an interesting affinity is found, which associates the present models with a version of the well-known practical Wien Bridge oscillator. The presently discussed system relies on coupled elementary oscillator units. The present coupling is due to merely two units. The model, however, is likely to become even more realistic by coupling in the same manner an assembly of relatively many oscillators.     

Can epidemic models describe the diffusion of topics across disciplines?

This paper introduces a new approach to describe the spread of research topics across disciplines using epidemic models. The approach is based on applying individual-based models from mathematical epidemiology to the diffusion of a research topic over a contact network that represents knowledge flows over the map of science—as obtained from citations between ISI Subject Categories. Using research publications on the protein class kinesin as a case study, we report a better fit between model and empirical data when using the citation-based contact network. Incubation periods on the order of 4–15.5 years support the view that, whilst research topics may grow very quickly, they face difficulties to overcome disciplinary boundaries.     

The development of emotion expression during the first two years of life

This study examines the course of emotion expression development over the first 2 years of life in a sample of full-term and preterm children. 58 mother/infant pairs were videotaped at infant ages of 2 1/2, 5, 7 1/2, and 22 months, recording face-to-face interaction involving play and separation/reunion sessions. The tapes were coded on a second-to-second basis using Izard's facial affect coding system. Data analysis focused on (1) differences in expressive behavior at 22 months as a function of risk status, gender, attachment status, and patterns of earlier maternal contingency behavior; (2) stability of specific emotional expressive patterns across assessment periods; and (3) the relation of expressive behavior and security of attachment at 2 years to qualities of earlier affective interchange. Mother's contingency behavior (both general level and specific contingency patterns) appeared to have a material effect on the course of emotional development, as did birth status and gender. Prematurity was associated with differential socioemotional development well into the second year, much in contrast to the "catch-up effect" observed in linguistic and cognitive functioning. Discrete emotions analysis of attachment groups yielded differentiation along a broad negative/positive dimension, but it also showed that insecurely attached children can be characterized as showing inhibited anger expression. The results of this study are discussed within the framework of organizational models of infant affective development; attachment theory and discrete emotions approaches were found to yield different yet equally informative data on the course of socioemotional development.