Fixed point properties of the binomial function are developed. It is shown that for any 1 < L < N, TLNhas a unique fixed point p? in (0, 1), and that for large N, the fixed point is L/N. This has application to signal detection schemes commonly used in communication systems. When detecting the presence or absence of a signal with an initial false alarm probability pFAand an initial detection probability pD, then TLN(pFA) < pFAand TLN(pD) > pDif, and only if, pFA < p? < pD. When this condition is satisfied, as N → ∞, TLN(pFA) → 0 and TLN(pD → 1. 相似文献
By means of Mawhin's continuation theorem, we study a kind of fourth-order p-Laplacian neutral functional differential equation with a deviating argument in the form:
In both the UK and Australia there has been a recent move to use citation analysis in the evaluation of the research of individuals. In particular, the future UK Research Excellence Framework (REF), proposes using citation data in the research evaluation of articles published as recently as the year prior to the evaluation. In response to this move, this research develops an indicator at the level of individual articles that, when normalized, can supplement peer review. The new hybrid indicator is the weighted sum of two indicators in common usage: the article’s total number of citations in a citation window, and the Impact Factor of the journal in which the article was published. This research compares this new indicator with the article’s total number of citations in a longer citation window (the standard indicator of article impact). For citation windows of 0 or 1 years, the correlation of the simplified weighted sum with long-term citation is substantially higher than the correlation of the standard indicator of article citation with long-term citation. Moreover, for citation windows of as long as 3 years the standard indicator of citation correlates significantly with the month of publication, in that articles published earlier in the year are on average more highly cited than those published later in the year. By contrast, the skewing of the simplified weighted sum towards articles published early in the year is considerably less than that of the standard indicator. 相似文献
A substantial amount of research has focused on the persistence or availability of Web citations. The present study analyzes Web citation distributions. Web citations are defined as the mentions of the URLs of Web pages (Web resources) as references in academic papers. The present paper primarily focuses on the analysis of the URLs of Web citations and uses three sets of data, namely, Set 1 from the Humanities and Social Science Index in China (CSSCI, 1998–2009), Set 2 from the publications of two international computer science societies, Communications of the ACM and IEEE Computer (1995–1999), and Set 3 from the medical science database, MEDLINE, of the National Library of Medicine (1994–2006). Web citation distributions are investigated based on Web site types, Web page types, URL frequencies, URL depths, URL lengths, and year of article publication. Results show significant differences in the Web citation distributions among the three data sets. However, when the URLs of Web citations with the same hostnames are aggregated, the distributions in the three data sets are consistent with the power law (the Lotka function). 相似文献
The paper attempts to provide an alternative method for measuring the importance of scientific papers based on the Google’s PageRank. The method is a meaningful extension of the common integer counting of citations and is then experimented for bringing PageRank to the citation analysis in a large citation network. It offers a more integrated picture of the publications’ influence in a specific field. We firstly calculate the PageRanks of scientific papers. The distributional characteristics and comparison with the traditionally used number of citations are then analyzed in detail. Furthermore, the PageRank is implemented in the evaluation of research influence for several countries in the field of Biochemistry and Molecular Biology during the time period of 2000–2005. Finally, some advantages of bringing PageRank to the citation analysis are concluded. 相似文献
In this paper, we use the coincidence degree theory to establish new results on the existence of T-periodic solutions for the Rayleigh equation with two deviating arguments of the form
Quantitative research evaluation requires measures that are transparent, relatively simple, and free of disciplinary and temporal bias. We document and provide a solution to a hitherto unaddressed temporal bias – citation inflation – which arises from the basic fact that scientific publication is steadily growing at roughly 4% per year. Moreover, because the total production of citations grows by a factor of 2 every 12 years, this means that the real value of a citation depends on when it was produced. Consequently, failing to convert nominal citation values into real citation values produces significant mis-measurement of scientific impact. To address this problem, we develop a citation deflator method, outline the steps to generalize and implement it using the Web of Science portal, and analyze a large set of researchers from biology and physics to demonstrate how two common evaluation metrics – total citations and h-index – can differ by a remarkable amount depending on whether the underlying citation counts are deflated or not. In particular, our results show that the scientific impact of prior generations is likely to be significantly underestimated when citations are not deflated, often by 100% or more of the nominal value. Thus, our study points to the need for a systemic overhaul of the counting methods used evaluating citation impact – especially in the case of researchers, journals, and institutions – which can span several decades and thus several doubling periods. 相似文献
Numerous metrics have been developed to identify revolutionary science which is crucial for advancing science. However, these metrics have rarely successfully identified revolutionary discoveries. We propose a two-dimension metric to quantify revolutionary discoveries by combining the consolidation-or-destabilization (CD) index with the citation count. To verify the validity of the metric, we utilize multivariate linear regression to investigate the differences in the CD indices and citations between 164 Nobel prize-winning papers from 1976 to 2016 (i.e., revolutionary science) and 9,034 counterparts that are similar to the Nobel prize-winning papers in terms of bibliographic information. We find that our proposed metric successfully shows a significant and distinct difference between the Nobel prize-winning papers and their counterparts in that the former receive around 880 more citations and 0.07 higher CD indices than the latter. The reliability of our proposed measure is robust. 相似文献
Using Lu's continuation theorem, the extension one of Manásevich-Mawhin, we study the existence of periodic solutions for p-Laplacian neutral Liénard equation of the form
Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 5 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of the M1 transition ψ(2S) → γηc(2S) and the discovery of the ψ2(3823) state; and report on studies of charmoniumlike states, including the discoveries of the Zc(3900) and Zc(4020) tetraquark candidates, the resolution of the fine structure of the Y(4260) state, the discovery of the new production process e+e− → γX(3872) and the uncovering of strong evidence for the commonality among the X(3872), Y(4260) and Zc(3900) states. The prospects for further research at BESIII and proposed future facilities are also presented. 相似文献
With the increasing use of research paper search engines, such as CiteSeer, for both literature search and hiring decisions, the accuracy of such systems is of paramount importance. This article employs conditional random fields (CRFs) for the task of extracting various common fields from the headers and citation of research papers. CRFs provide a principled way for incorporating various local features, external lexicon features and globle layout features. The basic theory of CRFs is becoming well-understood, but best-practices for applying them to real-world data requires additional exploration. We make an empirical exploration of several factors, including variations on Gaussian, Laplace and hyperbolic-L1 priors for improved regularization, and several classes of features. Based on CRFs, we further present a novel approach for constraint co-reference information extraction; i.e., improving extraction performance given that we know some citations refer to the same publication. On a standard benchmark dataset, we achieve new state-of-the-art performance, reducing error in average F1 by 36%, and word error rate by 78% in comparison with the previous best SVM results. Accuracy compares even more favorably against HMMs. On four co-reference IE datasets, our system significantly improves extraction performance, with an error rate reduction of 6–14%. 相似文献
Mechanically exfoliated two-dimensional ferromagnetic materials (2D FMs) possess long-range ferromagnetic order and topologically nontrivial skyrmions in few layers. However, because of the dimensionality effect, such few-layer systems usually exhibit much lower Curie temperature (TC) compared to their bulk counterparts. It is therefore of great interest to explore effective approaches to enhance their TC, particularly in wafer-scale for practical applications. Here, we report an interfacial proximity-induced high-TC 2D FM Fe3GeTe2 (FGT) via A-type antiferromagnetic material CrSb (CS) which strongly couples to FGT. A superlattice structure of (FGT/CS)n, where n stands for the period of FGT/CS heterostructure, has been successfully produced with sharp interfaces by molecular-beam epitaxy on 2-inch wafers. By performing elemental specific X-ray magnetic circular dichroism (XMCD) measurements, we have unequivocally discovered that TC of 4-layer Fe3GeTe2 can be significantly enhanced from 140 K to 230 K because of the interfacial ferromagnetic coupling. Meanwhile, an inverse proximity effect occurs in the FGT/CS interface, driving the interfacial antiferromagnetic CrSb into a ferrimagnetic state as evidenced by double-switching behavior in hysteresis loops and the XMCD spectra. Density functional theory calculations show that the Fe-Te/Cr-Sb interface is strongly FM coupled and doping of the spin-polarized electrons by the interfacial Cr layer gives rise to the TC enhancement of the Fe3GeTe2 films, in accordance with our XMCD measurements. Strikingly, by introducing rich Fe in a 4-layer FGT/CS superlattice, TC can be further enhanced to near room temperature. Our results provide a feasible approach for enhancing the magnetic order of few-layer 2D FMs in wafer-scale and render opportunities for realizing realistic ultra-thin spintronic devices. 相似文献
In 2019, the International Journal of Information Management (IJIM) celebrated its 40th year of publication. This study commemorates this event by presenting a retrospect of the journal. Using a range of bibliometric tools, we find that the journal has grown impressively in terms of publication and citation. The contributions come from all over the world, but the majority are from Europe and the United States. The journal has mostly published empirical articles, with its authors dominantly using quantitative methodology. Further, the culture of collaboration has increased among authors over the years. The journal publishes on a number of including managing information systems, information technologies and their application in business, technology acceptance among consumers, using information systems for decision making, social perspectives on knowledge management, and information research from the social science perspective. Regression analysis reveals that article attributes such as article order, methodology, presence of authors from Europe, number of references, number of keywords, and abstract length have a significant association with the citations. Finally, we find that conceptual and review articles have a positive association with citations. 相似文献
Previous studies have repeatedly demonstrated that the relevance of a citing document is related to the number of times with which the source document is cited. Despite the ease with which electronic documents would permit the incorporation of this information into citation-based document search and retrieval systems, the possibilities of repeated citations remain untapped. Part of this under-utilization may be due to the fact that very little is known regarding the pattern of repeated citations in scholarly literature or how this pattern may vary as a function of journal, academic discipline or self-citation. The current research addresses these unanswered questions in order to facilitate the future incorporation of repeated citation information into document search and retrieval systems. Using data mining of electronic texts, the citation characteristics of nine different journals, covering the three different academic fields (economics, computing, and medicine & biology), were characterized. It was found that the frequency (f) with which a reference is cited N or more times within a document is consistent across the sampled journals and academic fields. Self-citation causes an increase in frequency, and this effect becomes more pronounced for large N. The objectivity, automatability, and insensitivity of repeated citations to journal and discipline, present powerful opportunities for improving citation-based document search. 相似文献
This paper looks at how citations are perceived among scientists. Based on a questionnaire survey it traces the repertoire of views and experiences about citations that could be found among Norwegian scientists that had published highly cited papers. Their views circle around three issues: the relation between the quality (or importance or significance) of a paper and its citation history; the importance of visibility and how different sorts of factors play a role in determining citation in general and high citation in particular; and the fairness (or lack of fairness) of the system. Taken together, the respondents’ answers and comments offer an informal (and fragmented) sociology of citations and their role in the world of science. In the final section we discuss the relevance of our findings in respect to the increasing use of citation indicators in science policy and research evaluations. 相似文献
