we received good news from the Institute for Scientific Information (ISI), the creators of the journal impact factor (IF). Their Essential Science Indicators ranked the American Journal of Physiology (AJP)-Regulatory, Integrative and Comparative Physiology as the “most improved” journal in the Biology & Biochemistry group for August–October 2001. For January–March 2002, our journal was again successful, ranking as the second most improved journal.
What is written, read, and cited in AJP-Regulatory, Integrative and Comparative Physiology? Conjugated linoleic acid (CLA) soars. This is one of the remarkable observations made when looking back at 2001 citation behavior. DeLany et al. (6) was the study published in 1999 that was most frequently cited in 2001; it received 23 citations in 2001 (Table1). The authors showed that feeding CLA produces a rapid decrease in fat accumulation without any major effect on food intake. Baumgard et al. (3) “take the cake” for articles published in 2000 (Table2). Again, it was CLA:trans-10,cis-12. CLA was identified as the isomer responsible for inhibition of milk fat synthesis. Tables 1 and 2summarize the articles published in AJP-Regulatory, Integrative and Comparative Physiology in 1999 (of 447 total articles published) and 2000 (of 488 articles published), respectively, that were most frequently cited in 2001. These statistics are similar to those that ultimately make up the impact factor (IF). When comparing Tables 1 and 2, one notices that articles from 2000 appear to be less “appreciated” than those from 1999. This is a technical artifact, however, that identifies one major difficulty with IF interpretation. The articles from 2000 were cited less often than those from 1999 because a certain amount of time is required for work to be referenced. In fact, more than one-half of all the citations to a typical study published in our journal occur after 6 years.
The ISI Essential Science Indicators considers the citation behavior over a longer period than the IF (>10 years) and is updated every 2 months. The “citation half-life” provides information about the period during which papers of a journal are usually cited. Thus before the use of the Essential Science Indicators, rankings of journals had been made by considering the product of the citation half-life and the IF (7). The IF by itself, however, only considers the citation behavior of a given 2-yr period. Thus, articles with apparent long-lasting impact are not fully rewarded. For the same reason, December issues attract fewer citations than January issues (e.g., there are no October-December 2000 articles among the top 10 in Table 2); the simple explanation is that January papers have 11 months more time to be considered for the IF than a study published in December. This helps explain why some journals have considerably thicker volumes in January than in December!
AJP-Regulatory, Integrative and Comparative Physiologycurrently receives roughly one-half of its submissions from outside the United States (Table 3). Regulatory and Integrative Physiology was the subheading of most of the studies published in 1999 and 2000 (3 subheadings were available: Regulatory and Integrative Physiology, Developmental Physiology, or Comparative Physiology). All of the sections are valuable, however, and make AJP-Regulatory, Integrative and Comparative Physiologythe journal it is.
What all the commonly used indexes do not take into account is the remarkable observation that what is most frequently read is not necessarily most often cited. The average article appearing inAdvances in Physiology Education is downloaded from the website around three times as often as a typical AJPpaper. Statistically speaking, there are 62,730 readers for every IF of Advances in Physiology Education. ForAJP-Regulatory, Integrative and Comparative Physiology, there are 168 readers per IF.
Finally, some news regarding submitted manuscripts: the time from submission to first decision has been reduced to 34 days. The average manuscript that is ultimately accepted for publication has been in the pipeline for only 76 days. The present acceptance rate for original articles is below 50%.
Address for reprint requests and other correspondence: P. B. Persson, Johannes-Müller-Institut für Physiologie, Tucholskystr. 2, D-10117 Berlin, Germany (E-mail:).
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- Copyright © 2002 the American Physiological Society