Search (5 results, page 1 of 1)

0.029778086 = product of:
  0.11911234 = sum of:
    0.11911234 = weight(_text_:evolution in 2337) [ClassicSimilarity], result of:
      0.11911234 = score(doc=2337,freq=6.0), product of:
        0.19585751 = queryWeight, product of:
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.03697776 = queryNorm
        0.6081582 = fieldWeight in 2337, product of:
          2.4494898 = tf(freq=6.0), with freq of:
            6.0 = termFreq=6.0
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.046875 = fieldNorm(doc=2337)
  0.25 = coord(1/4)

Abstract

This study applied LDA (latent Dirichlet allocation) and regression analysis to conduct a lead-lag analysis to identify different topic evolution patterns between preprints and papers from arXiv and the Web of Science (WoS) in astrophysics over the last 20 years (1992-2011). Fifty topics in arXiv and WoS were generated using an LDA algorithm and then regression models were used to explain 4 types of topic growth patterns. Based on the slopes of the fitted equation curves, the paper redefines the topic trends and popularity. Results show that arXiv and WoS share similar topics in a given domain, but differ in evolution trends. Topics in WoS lose their popularity much earlier and their durations of popularity are shorter than those in arXiv. This work demonstrates that open access preprints have stronger growth tendency as compared to traditional printed publications.

0.014326988 = product of:
  0.05730795 = sum of:
    0.05730795 = weight(_text_:evolution in 1357) [ClassicSimilarity], result of:
      0.05730795 = score(doc=1357,freq=2.0), product of:
        0.19585751 = queryWeight, product of:
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.03697776 = queryNorm
        0.2926002 = fieldWeight in 1357, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.0390625 = fieldNorm(doc=1357)
  0.25 = coord(1/4)

Abstract

Despite a very large number of studies on the aging and obsolescence of scientific literature, no study has yet measured, over a very long time period, the changes in the rates at which scientific literature becomes obsolete. This article studies the evolution of the aging phenomenon and, in particular, how the age of cited literature has changed over more than 100 years of scientific activity. It shows that the average and median ages of cited literature have undergone several changes over the period. Specifically, both World War I and World War II had the effect of significantly increasing the age of the cited literature. The major finding of this article is that contrary to a widely held belief, the age of cited material has risen continuously since the mid-1960s. In other words, during that period, researchers were relying on an increasingly old body of literature. Our data suggest that this phenomenon is a direct response to the steady-state dynamics of modern science that followed its exponential growth; however, we also have observed that online preprint archives such as arXiv have had the opposite effect in some subfields.

0.014326988 = product of:
  0.05730795 = sum of:
    0.05730795 = weight(_text_:evolution in 1208) [ClassicSimilarity], result of:
      0.05730795 = score(doc=1208,freq=2.0), product of:
        0.19585751 = queryWeight, product of:
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.03697776 = queryNorm
        0.2926002 = fieldWeight in 1208, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          5.29663 = idf(docFreq=601, maxDocs=44218)
          0.0390625 = fieldNorm(doc=1208)
  0.25 = coord(1/4)

Abstract

Empirical evidence demonstrates that citations received by scholarly publications follow a pattern of preferential attachment, resulting in a power-law distribution. Such asymmetry has sparked significant debate regarding the use of citations for research evaluation. However, a consensus has yet to be established concerning the historical trends in citation concentration. Are citations becoming more concentrated in a small number of articles? Or have recent geopolitical and technical changes in science led to more decentralized distributions? This ongoing debate stems from a lack of technical clarity in measuring inequality. Given the variations in citation practices across disciplines and over time, it is crucial to account for multiple factors that can influence the findings. This article explores how reference-based and citation-based approaches, uncited articles, citation inflation, the expansion of bibliometric databases, disciplinary differences, and self-citations affect the evolution of citation concentration. Our results indicate a decreasing trend in citation concentration, primarily driven by a decline in uncited articles, which, in turn, can be attributed to the growing significance of Asia and Europe. On the whole, our findings clarify current debates on citation concentration and show that, contrary to a widely-held belief, citations are increasingly scattered.

0.0035425886 = product of:
  0.014170354 = sum of:
    0.014170354 = product of:
      0.04251106 = sum of:
        0.04251106 = weight(_text_:22 in 2763) [ClassicSimilarity], result of:
          0.04251106 = score(doc=2763,freq=4.0), product of:
            0.12948982 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03697776 = queryNorm
            0.32829654 = fieldWeight in 2763, product of:
              2.0 = tf(freq=4.0), with freq of:
                4.0 = termFreq=4.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=2763)
      0.33333334 = coord(1/3)
  0.25 = coord(1/4)

Date

22. 3.2009 19:22:35

0.001252494 = product of:
  0.005009976 = sum of:
    0.005009976 = product of:
      0.015029929 = sum of:
        0.015029929 = weight(_text_:22 in 3809) [ClassicSimilarity], result of:
          0.015029929 = score(doc=3809,freq=2.0), product of:
            0.12948982 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03697776 = queryNorm
            0.116070345 = fieldWeight in 3809, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0234375 = fieldNorm(doc=3809)
      0.33333334 = coord(1/3)
  0.25 = coord(1/4)

Date

20. 1.2015 18:30:22