The network structure of a hyperlinked environment can be a rich source of information about the content of the environment, provided we have effective means for understanding it. We develop a set of algorithmic tools for extracting information from the link structures of such environments, and report on experiments that demonstrate their effectiveness in a variety of context on the World Wide Web. The central issue we address within our framework is the distillation of broad search topics, through the discovery of “authorative” information sources on such topics. We propose and test an algorithmic formulation of the notion of authority, based on the relationship between a set of relevant authoritative pages and the set of “hub pages” that join them together in the link structure. Our formulation has connections to the eigenvectors of certain matrices associated with the link graph; these connections in turn motivate additional heuristrics for link-based analysis.

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Authoritative sources in a hyperlinked environment

We present VOSviewer, a freely available computer program that we have developed for constructing and viewing bibliometric maps. Unlike most computer programs that are used for bibliometric mapping, VOSviewer pays special attention to the graphical representation of bibliometric maps. The functionality of VOSviewer is especially useful for displaying large bibliometric maps in an easy-to-interpret way. The paper consists of three parts. In the first part, an overview of VOSviewer’s functionality for displaying bibliometric maps is provided. In the second part, the technical implementation of specific parts of the program is discussed. Finally, in the third part, VOSviewer’s ability to handle large maps is demonstrated by using the program to construct and display a co-citation map of 5,000 major scientific journals.

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Software survey: VOSviewer, a computer program for bibliometric mapping.

A new form of document coupling called co-citation is defined as the frequency with which two documents are cited together. The co-citation frequency of two scientific papers can be determined by comparing lists of citing documents in the Science Citation Index and counting identical entries. Networks of co-cited papers can be generated for specific scientific specialties, and an example is drawn from the literature of particle physics. Co-citation patterns are found to differ significantly from bibliographic coupling patterns, but to agree generally with patterns of direct citation. Clusters of co-cited papers provide a new way to study the specialty structure of science. They may provide a new approach to indexing and to the creation of SDI profiles.

Co-citation in the scientific literature: A new measure of the relationship between two documents

bibliometrix: An R-tool for comprehensive science mapping analysis

We review the recent rapid progress in the statistical physics of evolving networks. Interest has focused mainly on the structural properties of complex networks in communications, biology, social sciences and economics. A number of giant artificial networks of this kind have recently been created, which opens a wide field for the study of their topology, evolution, and the complex processes which occur in them. Such networks possess a rich set of scaling properties. A number of them are scale-free and show striking resilience against random breakdowns. In spite of the large sizes of these networks, the distances between most of their vertices are short - a feature known as the 'small-world' effect. We discuss how growing networks self-organize into scale-free structures, and investigate the role of the mechanism of preferential linking. We consider the topological and structural properties of evolving networks, and percolation and disease spread on these networks. We present a number of models demonstrat...

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Evolution of networks

tion, is compiling a roster of nearly 2000 persons who can serve as expert advisors on toxicology or related subjects. (Since the Society of Toxicology numbers only 385 members, our file obviously will include advisors whose interests are tangential, as well as those whose interests are central, to toxicology.) With assistance from industry, universities, professional societies and government, we hope gradually to develop an inventory of information resources indexed in depth to provide referrals to references, documents, evaluated data, and information. Additionally, the National Referral Center for Science and Technology of the Library of Congress, under an agreement with NLM, will publish a directory of general toxicology information services before the end of 1969. The Library plans ultimately to maintain a file with the capability of supplying up-to-date information for access by data line telephone connection. Qualified users may then readily obtain information on a host of products and compounds with known or potentially toxic effects. The realization of this plan depends on our ability to create and maintain a file satisfactorily describing the capabilities and services of specialized information sources. I ts realization depends also on the utilization of codes, standards, and criteria acceptable to participants in the toxicology information network. The dream of a truly responsive data and information resource would otherwise be impossible of realization. A rational system of information handling requires common acceptance of forms, terms, and units of measure. Unless those who use services and those who provide them can understand each other, the system will be grossly ineffectual. As planners responsible for national toxicologic information activities, we are sensitive to the influence which the structure and contents of our files and the nature of our computer programs will have upon establishment of standards of terminology, codes, practice, and information transfer. Any sizable, potentially useful resource must, by its very nature, influence the ways and means by which prospective users and contributors will interact with these activities.

Literature and the Creative Process-Help or Hindrance?

A Memorable Day with Henry E. Bliss.

Allergies are a common problem, affecting at least 15 percent of Americans and probably comparable numbers in other industrialized countries-at least 100 million people worldwide. Symptoms range from a runny nose to a lifethreatening anaphylactic reaction. The causes of those allergies are as diverse as the symptoms. Thw first of a three-part essay will discuss the immune mechanisms that cause allergic reactions and the factors that predispose some of us to them. In the next part, we will focus on diagnosis and treatment. The third part will deal with the behavioral aspects of allergic disorders.

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Allergies Are Nothing to Sneeze At: Part 1. Epidemiology and Etiology

Agony and Ecstasy of the Internet: Experiences of an Information Scientist Qua Publisher.

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Eugene Garfield

Papers

Literature and the Creative Process-Help or Hindrance?

A Memorable Day with Henry E. Bliss.

Allergies Are Nothing to Sneeze At: Part 1. Epidemiology and Etiology

Agony and Ecstasy of the Internet: Experiences of an Information Scientist Qua Publisher.

Els índexs de citacions: del Science Citation Index al Web of Science