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1.
The minimum configuration to have a h-index equal to h is h papers each having h citations, hence h2 citations in total. To increase the h-index to h + 1 we minimally need (h + 1)2 citations, an increment of I1(h) = 2h + 1. The latter number increases with 2 per unit increase of h. This increment of the second order is denoted I2(h) = 2.If we define I1 and I2 for a general Hirsch configuration (say n papers each having f(n) citations) we calculate I1(f) and I2(f) similarly as for the h-index. We characterize all functions f for which I2(f) = 2 and show that this can be obtained for functions f(n) different from the h-index. We show that f(n) = n (i.e. the h-index) if and only if I2(f) = 2, f(1) = 1 and f(2) = 2.We give a similar characterization for the threshold index (where n papers have a constant number C of citations). Here we deal with second order increments I2(f) = 0.  相似文献   

2.
The distribution of cumulative citations L and contributed citations Lf to individual multiauthored papers published by selected authors working in different scientific disciplines is analyzed and discussed using Langmuir-type function: yn = y0[1 − αKn/(1 + Kn)], where yn denotes the total number of normalized cumulative citations ln* and normalized contributed citations lnf* received by individual papers of rank n, y0 is the maximum value of yn when n = 0, α ≥ 1 is an effectiveness parameter, and K is the Langmuir constant related to the dimensionless differential energy Q = ln(KNc), with Nc as the number of papers receiving citations. Relationships between the values of the Langmuir constant K of the distribution function, the number Nc of papers of an individual author receiving citations and the effectiveness parameter α of this function, obtained from analysis of the data of rank-size distributions of the authors, are investigated. It was found that: (1) the quantity KNc obtained from the real citation distribution of papers of various authors working in different disciplines is inversely proportional to (α − 1) with a proportional constant (KNc)0 < 1, (2) the relation KNc = (KNc)0/(α − 1) also holds for the citation distribution of journals published in countries of two different groups, investigated earlier (Sangwal, K. (2013). Journal of Informetrics, 7, 487–504), and (3) deviations of the real citation distribution from curves predicted by the Langmuir-type function are associated with changing activity of sources of generation of items (citations).  相似文献   

3.
The distributions of citations L, two- (IF2) and five-year impact factors (IF5), and citation half-lives λ of journals published in different selected countries are analyzed using Langmuir-type relation: yn = y0 {1 ? αKn/(1 + Kn)}, where yn denotes Ln, IF2n or IF5n of n-ranked journal, y0 is the value of yn when journal rank n = 0, α is an empirical effectiveness parameter, and K is the Langmuir constant. It was found that: (1) the general features of the distribution of Ln, IF2n or IF5n of the journals published in different individual countries are similar to the results obtained before by the author from the analysis of the citation distribution data of papers of individual authors (K. Sangwal, Journal of Informetrics 7 (2013) 36–49), (2) in contrast to the theoretically expected value of the effectiveness parameter α = 1, the calculated values of α > 1 for journals published in different countries, (3) the trends of the distribution of cited half-lives λn of journals differ from those of Ln, IF2n and IF5n data for different countries, and show one, two or three linear regions, the longest linear regions with low slopes are observed in the case of countries publishing relatively high number of journals, and (4) the product of the Langmuir constant K and the number N of journals for the processes of citations and two- and five-year impact factors of journals published in different countries is constant for a process. The results suggest that: (1) the values of α > 1 are associated with a process that retards the generation of items (i.e. citations or impact factors), the difference (α ? 1) being related to the dissemination of contents of the journals published by a country, and (2) the constancy of KN is related to the publication potential of a country.  相似文献   

4.
To take into account the impact of the different bibliometric features of scientific fields and different size of both the publication set evaluated and the set used as reference standard, two new impact indicators are introduced. The Percentage Rank Position (PRP) indicator relates the ordinal rank position of the article assessed to the total number of papers in the publishing journal. The publications in the publishing journal are ranked by the decreasing citation frequency. The Relative Elite Rate (RER) indicator relates the number of citations obtained by the article assessed to the mean citation rate of the papers in the elite set of the publishing journal. The indices can be preferably calculated from the data of the publications in the elite set of journal papers of individuals, teams, institutes or countries. The number of papers in the elite set is calculated by the equation: P(πv) = (10 log P) ? 10, where P is the total number of papers. The mean of the PRP and RER indicators of the journal papers assessed may be applied for comparing the eminence of publication sets across fields.  相似文献   

5.
The citation distribution of papers of selected individual authors was analyzed using five mathematical functions: power-law, stretched exponential, logarithmic, binomial and Langmuir-type. The former two functions have previously been proposed in the literature whereas the remaining three are novel and are derived following the concepts of growth kinetics of crystals in the presence of additives which act as inhibitors of growth. Analysis of the data of citation distribution of papers of the authors revealed that the value of the goodness-of-the-fit parameter R2 was the highest for the empirical binomial relation, it was high and comparable for stretched exponential and Langmuir-type functions, relatively low for power law but it was the lowest for the logarithmic function. In the Langmuir-type function a parameter K, defined as Langmuir constant, characterizing the citation behavior of the authors has been identified. Based on the Langmuir-type function an expression for cumulative citations L relating the extrapolated value of citations l0 corresponding to rank n = 0 for an author and his/her constant K and the number N of paper receiving citation l ≥ 1 is also proposed.  相似文献   

6.
Examining a comprehensive set of papers (n = 1837) that were accepted for publication by the journal Angewandte Chemie International Edition (one of the prime chemistry journals in the world) or rejected by the journal but then published elsewhere, this study tested the extent to which the use of the freely available database Google Scholar (GS) can be expected to yield valid citation counts in the field of chemistry. Analyses of citations for the set of papers returned by three fee-based databases – Science Citation Index, Scopus, and Chemical Abstracts – were compared to the analysis of citations found using GS data. Whereas the analyses using citations returned by the three fee-based databases show very similar results, the results of the analysis using GS citation data differed greatly from the findings using citations from the fee-based databases. Our study therefore supports, on the one hand, the convergent validity of citation analyses based on data from the fee-based databases and, on the other hand, the lack of convergent validity of the citation analysis based on the GS data.  相似文献   

7.
In the present study we have tried to trace the growth of malaria research at Global Level and the distribution of articles in various journals for the period 1955–2005. The data have been extracted from a database, which has been developed in-house from MEDLINE, SCI, TDB, Ovid Heath Information and Indian Science Abstracts. Study indicates that the exponential model fits the data on journals, articles and authors. The R2 value for the trend for journals, articles, and authors are 0.9502, 0.9475, and 0.9651, respectively. The growth rates for journals, articles and authors are 5.31%, 7.38%, and 10.06%, respectively. The linear multiple regression equation that Articles = ?39.2771 + 3.61719*journals + 0.085882*Authors (R2 = 99.16%) is most meaningful and it may be used to estimate the articles for given numbers of journals and authors.  相似文献   

8.
In this paper, we show that an information source composed with n random variables may be split into 2n or 2n − 1 “states”; therefore, one could compute the maximum entropy of the source. We derive the efficiency and the unused capacity of an information source. We demonstrate that in more than two dimensions, the transmission's variability depends on the system configuration; thus, we determine the upper and the lower bounds to the mutual information and propose the transmission power as an indicator of the Triple Helix of university–industry–government relationships. The transmission power is defined as the fraction of the total ‘configurational information’ produced in a system; it appears like the efficiency of the transmission and may be interpreted as the strength of the variables dependency, the strength of the synergy between the system's variable or the strength of information flow within the system.  相似文献   

9.
Bibliometrics has become an indispensable tool in the evaluation of institutions (in the natural and life sciences). An evaluation report without bibliometric data has become a rarity. However, evaluations are often required to measure the citation impact of publications in very recent years in particular. As a citation analysis is only meaningful for publications for which a citation window of at least three years is guaranteed, very recent years cannot (should not) be included in the analysis. This study presents various options for dealing with this problem in statistical analysis. The publications from two universities from 2000 to 2011 are used as a sample dataset (n = 2652, univ 1 = 1484 and univ 2 = 1168). One option is to show the citation impact data (percentiles) in a graphic and to use a line for percentiles regressed on ‘distant’ publication years (with confidence interval) showing the trend for the ‘very recent’ publication years. Another way of dealing with the problem is to work with the concept of samples and populations. The third option (very related to the second) is the application of the counterfactual concept of causality.  相似文献   

10.
The definitions of the rational and real-valued variants of the h-index and g-index are reviewed. It is shown how they can be obtained both graphically and by calculation. Formulae are derived expressing the exact relations between the h-variants and between the g-variants. Subsequently these relations are examined. In a citation context the real h-index is often, but not always, smaller than the rational h-index. It is also shown that the relation between the real and the rational g-index depends on the number of citations of the article ranked g + 1. Maximum differences between h, hr and hrat on the one hand and between g, gr and grat on the other are determined.  相似文献   

11.
In an exploratory study, participants (n = 18) completed 11 usability tasks to assess ease of use of two Web sites, and then a Web site perception questionnaire for each. Participants rated both Web sites positively, but 25% and 36% could not complete all tasks; doing so required more than a minute to complete.  相似文献   

12.
The scientific impact of a publication can be determined not only based on the number of times it is cited but also based on the citation speed with which its content is noted by the scientific community. Here we present the citation speed index as a meaningful complement to the h index: whereas for the calculation of the h index the impact of publications is based on number of citations, for the calculation of the speed index it is the number of months that have elapsed since the first citation, the citation speed with which the results of publications find reception in the scientific community. The speed index is defined as follows: a group of papers has the index s if for s of its Np papers the first citation was at least s months ago, and for the other (Np ? s) papers the first citation was ≤s months ago.  相似文献   

13.
The arbitrariness of the h-index becomes evident, when one requires q × h instead of h citations as the threshold for the definition of the index, thus changing the size of the core of the most influential publications of a dataset. I analyze the citation records of 26 physicists in order to determine how much the prefactor q influences the ranking. Likewise, the arbitrariness of the highly-cited-publications indicator is due to the threshold value, given either as an absolute number of citations or as a percentage of highly cited papers. The analysis of the 26 citation records shows that the changes in the rankings in dependence on these thresholds are rather large and comparable with the respective changes for the h-index.  相似文献   

14.
This article reports on the results of a national survey of academic librarians and library staff (N = 226) in the United States about their awareness of various copyright policies, partnerships with campus groups to address copyright issues, and training needs. A majority of the survey respondents reported that they have answered copyright-related questions in the workplace, yet only 49% (n = 98) of the respondents perceived they were prepared to provide copyright information to library users. Awareness of various copyright policies among librarians and staff members varied, including a reported minimal awareness of the T.E.A.C.H. Act. In addition, survey respondents expressed the desire for more copyright-related training. In light of these findings, the present study extends the existing literature and offers recommendations to help better prepare a “copyright confident” or “copyright responsive” academic library workforce.  相似文献   

15.
In the 2015 Summer Session I, the information literacy team combined two instruments, the Information Literacy Assessment (ILA) and the Students' Perceptions of Their Information Literacy Skills Questionnaire (SPIL-Q), into one survey and distributed it to the college's international graduate students through a Google Form. It was distributed to 932 international graduate students, and 172 valid respondents completed the survey. The purpose of this research was to compare the confidence gap in information literacy skills between men and women, particularly in international graduate students. Data collected illustrated that female international business students (n = 70) tended to be slightly more confident than their male counterparts (n = 102) regarding their perceived information literacy skills as evidenced by their SPIL-Q average score across all six IL topics, 3.78, vs. male student's average score of 3.58.  相似文献   

16.
This study highlights the unique accommodations integral to welcoming transgender library patrons. Research shows transgender people have unique needs which differ from lesbian, gay, bisexual, and queer (LGBQ) individuals, and experience substantial barriers to obtaining quality library service. Most studies in the past exploring the needs of lesbian, gay, bisexual, and transgender library users focused exclusively on LGBQ users. This study surveyed adult transgender individuals (n = 102) with an online questionnaire. The majority of participants were white, designated female at birth, and under 40 years old. Survey respondents needed libraries to make accommodations for them to feel safe (p < 0.001). The top 5 accommodations needed were recent transgender literature, gender identity or expression as part of library nondiscrimination policy, gender neutral, single-stall bathrooms where a key did not need to be requested, recent LGBQ literature), and an established remote process for name change.  相似文献   

17.
Approximately one in five people in developed countries such as Canada and Australia will experience mental illness during their lifespan, and this statistic may be even higher for people between the ages of 18 and 25. Due to widespread stigma and other issues, access to mental health care is limited. However, given the heavy online use by people in this age range as well as the prevalence of existing online health information, it is possible that “e-mental health,” when delivered in an efficacious and engaging format, could be a viable dissemination option. A quantitative and qualitative online survey was distributed to university students in order to determine their opinions of currently available e-mental health resources. Within the sample (n = 1308), text-based searching on Web sites such as Google as well as reading informational Web sites were the most highly preferred and utilized methods. However, a significant knowledge gap regarding the existence of other e-mental health formats was noted. Suggestions for future research include search engine optimization changes and continued development of e-mental health resources.  相似文献   

18.
The relevancy of public libraries is often called into question, with some saying that library services have been or will be displaced by, among other things, new media such as social media. This study tested this displacement hypothesis with survey data collected from three nations (the U.S.: N = 879; South Korea: N = 700; and Singapore: N = 987). Ordinal regressions were used to investigate the relationship between the use of social media and nine public library services, taking into account individual demographic differences. The results show that for all three nations, social media use has significant complementary relationships with all nine library services examined. Computer and information literacy training showed the largest effect size. However, signs of displacement effects were observed in the odds ratio statistics, particularly among daily social media users and in reference services, library visits, and time spent in the library, suggesting that where displacement is concerned, these areas warrant extra attention.  相似文献   

19.
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20.
This study aimed to examine whether a graphical abstract (GA) on a publisher's official website affected an article's usage and citations. Articles published in Molecules during 2016 (n = 1389) and 2017 (n = 1804) were selected as the data sets. Propensity score matching analysis was conducted to examine the data sets. The results showed that articles with GAs had significantly greater text abstract usage than those without GAs. There were no significant differences between the two groups (articles with/without GAs) on the usage of the full text as well as citations, both in the data set of 2016 and the data set of 2017. Our study concluded that a GA played a role in attracting attention with ‘the first impressions’ to gain more clicks of text abstract for an article, however, it took no advantage in receiving more usage of full text and citations of the article.  相似文献   

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