Browse

You are looking at 901 - 1,000 of 11,008 items

Abstract

The study of citation distribution provides retrospective and prospective picture of the evolving impact of a corpus of publications on knowledge community. All distribution models agree on the rise of the number of citations in the first years following the publication to reach a peak and then tend to be less cited when time passes. However, questions such as how long it will continue being cited and what is objectively the rate of the decline remain unanswered. Built up of simple polynomial function, the proposed model is proven to be suitable to represent the observed citation distribution over time and to interestingly identify with accuracy when the major loss of citations happens. I calculate from the model the ‘residual citations’ representing the citations kept after a long time period after publication year. I demonstrate that the residual citations may be greater than or equal to zero, meaning that the ‘life-cycle’ of the corpus is infinite, contrary to what some researches termed to be around 21 years. This model fits the observed data from SCI according to R-sq which is greater than 98.9%. Rather, it is very simple and easy to implement and can be used by not highly-skilled scientometric users. Finally, the model serves as a citation predictive tool for a corpus by determining the citations that would obtain at any time of its life-cycle.

Restricted access

Abstract

This exploratory study aims at answering the following research question: Are the h-index and some of its derivatives discriminatory when applied to rank social scientists with different epistemological beliefs and methodological preferences? This study reports the results of five Tobit and two negative binomial regression models taking as dependent variable the h-index and six of its derivatives, using a dataset combining bibliometric data collected with the PoP software with cross-sectional data of 321 Quebec social scientists in Anthropology, Sociology, Social Work, Political Science, Economics and Psychology. The results reveal an epistemological/methodological effect making positivists and quantitativists globally more productive than constructivists and qualitativists.

Open access

Реэюме  

Лейндлер [5] получил некоторые оценки приближения средними Нёрлунда-Вороноƨо рядов Фурье в метрике Гёльдера. Испольэуя равенство двух норм в пространстве Гёльдера и теорему Лейндлера-Меира-Тотика, мы улучщаем Эти оценки.

Restricted access

Abstract  

Some identities of sums associated with harmonic numbers and binomial coefficients are developed. Integral representations and closed form identities of these sums are also given.

Restricted access

Abstract  

In this paper, the smallest number M which makes the equality

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$K_n (W_2^{L_r } (T),MW_2^{L_r } (T),L_2 (T)) = d_n (W_2^{L_r } (T),L_2 (T))$$ \end{document}
valid, is established and the asymptotic order of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$K_n (W_2^{L_r } (T),W_2^{L_r } (T),L_q (T)),1 \leqslant q \leqslant \infty$$ \end{document}
, is obtained, where
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$W_2^{L_r }$$ \end{document}
(T) is a periodic smooth function class which is determined by a linear differential operator, K n(·, ·, ·) and d n(·, ·) are the relative width and the width in the sense of Kolmogorov, respectively.

Restricted access

Abstract  

Let G be a locally compact abelian group (LCA group) and Ω be an open, 0-symmetric set. Let F:= F(Ω) be the set of all continuous functions f: G → ℝ which are supported in Ω and are positive definite. The Turán constant of Ω is then defined as

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{T}(\Omega ): = \sup \left\{ {\int_\Omega {f:f \in \mathcal{F}} (\Omega ),f(0) = 1} \right\}$$ \end{document}
. Mihalis Kolountzakis and the author has shown that structural properties — like spectrality, tiling or packing with a certain set Λ — of subsets Ω in finite, compact or Euclidean (i.e., ℝd) groups and in ℤd yield estimates of T (Ω). However, in these estimates some notion of the size, i.e., density of Λ played a natural role, and thus in groups where we had no grasp of the notion, we could not accomplish such estimates. In the present work a recent generalized notion of asymptotic uniform upper density is invoked, allowing a more general investigation of the Turán constant in relation to the above structural properties. Our main result extends a result of Arestov and Berdysheva, (also obtained independently and along different lines by Kolountzakis and the author), stating that convex tiles of a Euclidean space necessarily have
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{T}_{\mathbb{R}^d } (\Omega )\left| \Omega \right|/2^d$$ \end{document}
. In our extension ℝd could be replaced by any LCA group, convexity is considerably relaxed to Ω being a difference set, and the condition of tiling is also relaxed to a certain packing type condition and positive asymptotic uniform upper density of the set Λ. Also our goal is to give a more complete account of all the related developments and history, because until now an exhaustive overview of the full background of the so-called Turán problem was not delivered.

Restricted access

Abstract

Macro-environmental trends such as technological changes, declining trade and investment barriers, and globalizing forces impacting both markets and production worldwide point to the heightened importance of international business (IB) and the relevance of IB research today. Despite this, a leading scholar has expressed concerns that the IB research agenda could be ‘running out of steam’ (Buckley, Journal of International Business Studies 33(2):365–373, ), prompting on-going introspection within the IB field. We contribute to this debate by investigating the evolution of the IB field through a scientometric examination of articles published in its premier journal, the Journal of International Business Studies (JIBS) from 1970 until 2008. We introduce a new analytical tool, Leximancer, to the fields of international business and scientometry. We show an evolution from an initial and extended emphasis on macro-environmental issues to a more recent focus on micro-economic, firm-level ones with the multinational enterprise (MNE) as an organizational form enduring throughout the entire period. We observe a field that has established a justifiable claim for relevance, participating actively in the interdisciplinary exchange of ideas.

Restricted access

Abstract

Scientific authorship has important implications in science since it reflects the contribution to research of the different individual scientists and it is considered by evaluation committees in research assessment processes. This study analyses the order of authorship in the scientific output of 1,064 permanent scientists at the Spanish CSIC (WoS, 1994–2004). The influence of age, professional rank and bibliometric profile of scientists over the position of their names in the byline of publications is explored in three different research areas: Biology and Biomedicine, Materials Science and Natural Resources. There is a strong trend for signatures of younger researchers and those in the lower professional ranks to appear in the first position (junior signing pattern), while more veteran or highly-ranked ones, who tend to play supervisory functions in research, are proportionally more likely to sign in the last position (senior signing pattern). Professional rank and age have an effect on authorship order in the three fields analysed, but there are inter-field differences. Authorship patterns are especially marked in the most collaboration-intensive field (i.e. Biology and Biomedicine), where professional rank seems to be more significant than age in determining the role of scientists in research as seen through their authorship patterns, while age has a more significant effect in the least collaboration-intensive field (Natural Resources).

Open access

Abstract

National research evaluation exercises provide a comparative measure of research performance of the nation's institutions, and as such represent a tool for stimulating research productivity, particularly if the results are used to inform selective funding by government. While a school of thought welcomes frequent changes in evaluation criteria in order to prevent the subjects evaluated from adopting opportunistic behaviors, it is evident that the “rules of the game” should above all be functional towards policy objectives, and therefore be known with adequate forewarning prior to the evaluation period. Otherwise, the risk is that policy-makers will find themselves faced by a dilemma: should they reward universities that responded best to the criteria in effect at the outset of the observation period or those that result as best according to rules that emerged during or after the observation period? This study verifies if and to what extent some universities are penalized instead of rewarded for good behavior, in pursuit of the objectives of the “known” rules of the game, by comparing the research performances of Italian universities for the period of the nation's next evaluation exercise (2004–2008): first as measured according to criteria available at the outset of the period and next according to those announced at the end of the period.

Restricted access

Abstract

Evaluating the career of individual scientists according to their scientific output is a common bibliometric problem. Two aspects are classically taken into account: overall productivity and overall diffusion/impact, which can be measured by a plethora of indicators that consider publications and/or citations separately or synthesise these two quantities into a single number (e.g. h-index). A secondary aspect, which is sometimes mentioned in the rules of competitive examinations for research position/promotion, is time regularity of one researcher's scientific output. Despite the fact that it is sometimes invoked, a clear definition of regularity is still lacking. We define it as the ability of generating an active and stable research output over time, in terms of both publications/quantity and citations/diffusion. The goal of this paper is introducing three analysis tools to perform qualitative/quantitative evaluations on the regularity of one scientist's output in a simple and organic way. These tools are respectively (1) the PY/CY diagram, (2) the publication/citation Ferrers diagram and (3) a simplified procedure for comparing the research output of several scientists according to their publication and citation temporal distributions (Borda's ranking). Description of these tools is supported by several examples.

Restricted access
Authors: Jörn Quistorff and Jan-Christoph Schlage-Puchta

We consider generalized surjective codes, together with their connection to covering codes and covering arrays. We prove new bounds on σ q(n; s; r), the minimal cardinality of a q-ary code of length n, which is s-surjective with radius r. For covering codes we deduce the new records K 6(10, 7) ≦ 18 and K 6(9, 6) ≦ 24.

Restricted access

Abstract

This study addresses whether interdisciplinarity is a prominent feature of climate research by means of a co-citation analysis of the IPCC Third Assessment Report. The debate on interdisciplinarity and bibliometric measures is reviewed to operationalize the contested notion of interdisciplinarity. The results, based on 6417 references of the 96 most frequently used journals, demonstrate that the IPCC assessment of climate change is best characterized by its multidisciplinarity where the physical, biological, bodily and societal dimensions are clearly separated. Although a few fields and journals integrate a wide variety of disciplines, integration occurs mainly between related disciplines (narrow interdisciplinarity) which indicate an overall disciplinary basis of climate research. It is concluded that interdisciplinarity is not a prominent feature of climate research. The significance of this finding is explored, given that the problem scope of climate change necessitates interdisciplinarity. Ways to promote interdisciplinarity are suggested by way of conclusion.

Restricted access
Authors: Vincent Larivière, Etienne Vignola-Gagné, Christian Villeneuve, Pascal Gélinas and Yves Gingras

Abstract

Using the entire population of professors at universities in the province of Quebec (Canada), this article analyzes the relationship between sex and research funding, publication rates, and scientific impact. Since age is an important factor in research and the population pyramids of men and women are different, the role of age is also analyzed. The article shows that, after they have passed the age of about 38, women receive, on average, less funding for research than men, are generally less productive in terms of publications, and are at a slight disadvantage in terms of the scientific impact (measured by citations) of their publications. Various explanations for these differences are suggested, such as the more restricted collaboration networks of women, motherhood and the accompanying division of labour, women's rank within the hierarchy of the scientific community and access to resources as well as their choice of research topics and level of specialization.

Restricted access

Abstract

By employing new ideas and techniques, we will refigure out the whole frame of L 1-approximation. First, except generalizing the coefficients from monotonicity to a wider condition, Logarithm Rest Bounded Variation condition, we will also drop the prior requirement fL 2π but directly consider the sine or cosine series. Secondly, to achieve nontrivial generalizations in complex spaces, we use a one-sided condition with some kind of balance conditions. In addition, a conjecture raised in [9] is disproved in Section 3.

Restricted access

Abstract

We present a pointfree characterization of paracompactness via strong Cauchy completeness. We also provide a filter characterization of separability in uniform frames and determine those uniform frames that have a Lindelöf and compact completion using the notion of preparacompactness. Further, as an application of preparacompactness, we provide filter conditions for the Lindelöfness of the Hewitt realcompactification υL of a completely regular frame L.

Restricted access

Abstract

A classical insertion theorem due to Katětov–Tong (or Dowker–Katětov, Michael) reads that ℝ can be a test space for the range of maps on the insertion theorem which characterizes the domain to be normal (or normal and countably paracompact, perfectly normal). It is known that the range ℝ in the Katětov–Tong insertion theorem is not necessarily replaced by a non-trivial separable Banach lattice. We show that the range ℝ in the Dowker–Katětov and Michael insertion theorems can be replaced by any non-trivial separable Banach lattice.

Restricted access

Abstract

Let μ be a compactly suppported positive measure on the real line. A point x∊supp [μ] is said to be μ-regular, if, as n→∞,

ea
Otherwise it is a μ-irregular point. We show that for any such measure, the set of μ-irregular points in {μ′>0} (with a suitable definition of this set) has Hausdorff measure 0, for , any β>1.

Restricted access

Abstract

A weak form of Wiener–Ditkin set is introduced and some of its properties are studied. As a consequence, a weak form of C-set-S-set problem has come up.

Restricted access

Abstract

In this paper, we discuss the application of the data mining tools to identify typical features for highly cited papers (HCPs). By integrating papers’ external features and quality features, the feature space used to model HCPs was established. Then, a series of predictor teams were extracted from the feature space with rough set reduction framework. Each predictor team was used to construct a base classifier. Then the five base classifiers with the highest classification performance and larger diversity on whole were selected to construct a multi-classifier system (MCS) for HCPs. The combination prediction model obtained better performance than models of a single predictor team. 11 typical prediction features for HCPs were extracted on the basis of the MCS. The findings show that both the papers’ inner quality and external features, mainly represented as the reputation of the authors and journals, contribute to generation of HCPs in future.

Restricted access

Abstract

There is increasing interest in assessing how sponsored research funding influences the development and trajectory of science and technology. Traditionally, linkages between research funding and subsequent results are hard to track, often requiring access to separate funding or performance reports released by researchers or sponsors. Tracing research sponsorship and output linkages is even more challenging when researchers receive multiple funding awards and collaborate with a variety of differentially-sponsored research colleagues. This article presents a novel bibliometric approach to undertaking funding acknowledgement analysis which links research outputs with their funding sources. Using this approach in the context of nanotechnology research, the article probes the funding patterns of leading countries and agencies including patterns of cross-border research sponsorship. We identify more than 91,500 nanotechnology articles published worldwide during a 12-month period in 2008–2009. About 67% of these publications include funding acknowledgements information. We compare articles reporting funding with those that do not (for reasons that may include reliance on internal core-funding rather than external awards as well as omissions in reporting). While we find some country and field differences, we judge that the level of reporting of funding sources is sufficiently high to provide a basis for analysis. The funding acknowledgement data is used to compare nanotechnology funding policies and programs in selected countries and to examine their impacts on scientific output. We also examine the internationalization of research funding through the interplay of various funding sources at national and organizational levels. We find that while most nanotechnology funding is nationally-oriented, internationalization and knowledge exchange does occur as researchers collaborate across borders. Our method offers a new approach not only in identifying the funding sources of publications but also in feasibly undertaking large-scale analyses across scientific fields, institutions and countries.

Restricted access

Abstract

The main purpose of this paper is to introduce and study generalized hyperconnected spaces. Various characterizations of generalized hyperconnected spaces and preservation theorems are discussed.

Restricted access

Abstract

The Essential Science Indicators (ESI) database is widely used to evaluate institutions and researchers. The objective of this study was to analyze trends and characteristics of papers in the subject category of water resources in the ESI database of the Institute for Scientific Information (ISI). Distributions of document type, language of publication, scientific output, and publication of journals are reported in this article. Five indicators (the number and ranking of total papers, first-author papers, corresponding-author papers, independent papers, and collaborative papers) were applied to evaluate country, institute, and author performances. In addition, the numbers of authors cited, numbers of institutes cited, numbers of countries cited, and numbers of subject areas cited were also used to evaluate ESI papers. Results showed that 265 papers, all written in English, were listed in 27 journals in the field of water resources. A review paper was more likely to be included in the ESI than a research paper. Journal of Hydrology published the most papers. The USA and UK were the two leading nations. ESI papers published in the US were more likely to involve inter-institutional collaboration than papers published in the UK. The University of Arizona was the most productive institute. Some papers that were almost excluded from the ESI database appear to have consistently received annual high frequencies of citation. Perhaps the 10 year criterion for inclusion in the ESI should be reassessed.

Restricted access

Abstract

A new bibliometric index is proposed, trying to preserve the advantages of the h-index and to overcome its disadvantages. Multivariate comparisons among 18 bibliometric indices are performed by using Hasse Diagram Technique (HDT) and Principal Component Analysis (PCA). The comparisons were performed on some artificial data sets, three of them well known in literature. The obtained results seems to highlight some interesting properties of the new index and also reveals some relevant relationships among the considered bibliometric indices.

Restricted access
Authors: R. Baskaran, M. Murugalingam and D. Sivaraj

Abstract

We prove that the family of all generalized topologies on a nonempty set is a lattice, neither distributive nor complemented. We define the direct sum of two generalized topologies and characterize the direct sum.

Restricted access

Abstract

We show, conditional on a uniform version of the prime k-tuples conjecture, that there are x/(log x)1+o(1) numbers not exceeding x common to the ranges of ϕ and σ. Here ϕ is Euler’s totient function and σ is the sum-of-divisors function.

Restricted access

Abstract

Let be a class of groups and G a finite group. We call a set Σ of subgroups of G a G-covering subgroup system for if whenever . Let p be any prime dividing |G| and P a Sylow p-subgroup of G. Then we write Σp to denote the set of subgroups of G which contains at least one supplement to G of each maximal subgroup of P. We prove that the sets Σp and Σp∪Σq, where qp, are G-covering subgroup systems for many classes of finite groups.

Restricted access

Abstract

We consider the classical Kolmogorov condition for strong law of large numbers for sequences of dependent random variables; the so-called ϕ-mixing and Rademacher–Menchoff condition for ρ-mixing sequences.

Restricted access

Abstract

Let f(x)=a d x d+a d−1 x d−1+⋅⋅⋅+a 0∊ℝ[x] be a reciprocal polynomial of degree d. We prove that if the coefficient vector (a d,a d−1,…,a 0) or (a d−1,a d−2,…,a 1) is close enough, in the l 1-distance, to the constant vector (b,b,…,b)∊ℝd+1 or ℝd−1, then all of its zeros have moduli 1.

Restricted access

Abstract

It is proved that the maximal operator of the triangular Cesàro means of a two-dimensional Fourier series is bounded from the periodic Hardy space to for all 2/(2+α)<p≦∞ and, consequently, is of weak type (1,1). As a consequence we obtain that the triangular Cesàro means of a function converge a.e. to f.

Restricted access

Abstract

The aim of this article is to observe differences between research areas when it comes to establish collaboration ties with local, national or international partners. It also intends to determine in what extent the collaboration can influence the patent transfer. A collaboration network between CSIC researchers and their external collaborators was built. Several statistical tests were used to find significant differences between research areas. A multiple regression model was also utilized in order to know what type of collaboration is more successful to transfer a patent. The results show that there are two well defined groups. A “Bio” group with a high international collaboration pattern but less national participation; and a “Physicist” group supported by a high proportion of national partners but with few international connections. The regression analysis found that the national collaboration is the variable that most increase the patent transfer.

Restricted access

Abstract

Pointwise estimates of the deviation T n,A,B f(⋅)−f(⋅) in terms of moduli of continuity and w f are proved. Analog results on norm approximation with remarks and corollaries are also given. In the results essentially weaker conditions than those in [2, Theorem 1, p. 437] are used.

Restricted access

Abstract

The main results of the paper generalize the following classical theorem to the setting of line element D-manifolds: the automorphisms of a covariant derivative on a manifold are exactly the affinities that leave its torsion invariant.

Restricted access

Abstract

We prove that if a space X is well ordered (αA), or linearly semi-stratifiable, or elastic then X is a D-space.

Restricted access

Abstract

In this note we will show that finitely generated condition is necessary in Theorem 1.2 of the above mentioned paper.

Restricted access

Abstract

Bibliometric research assessment has matured into a quantitative phase using more meaningful measures and analogies. In this paper, we propose a thermodynamic analogy and introduce what are called the energy, exergy and entropy terms associated with a bibliometric sequence. This can be displayed as time series (variation over time), or in event terms (variation as papers are published) and also in the form of phase diagrams (energy–exergy–entropy representations). It is exergy which is the most meaningful single number scalar indicator of a scientist's performance while entropy then becomes a measure of the unevenness (disorder) of the publication portfolio.

Restricted access

Abstract

We investigate linear relations between pattern sequences in a 〈q,r〉-numeration system, and give a basis of the module generated by pattern sequences for words of length not exceeding l. The expressions of pattern sequences using the basis are also studied. Similar results are obtained for the module generated by all pattern sequences.

Restricted access

Abstract

We introduce the notion of mixed weak (μ1ν2)-continuity between a generalized topology μ and two generalized topologies ν1, ν2. We characterize such continuity in terms of mixed generalized open sets: (ν12)′-semiopen sets, (ν12)′-preopen sets, (ν12)-preopen sets [2], (ν12)′-β′-open sets and θ12)-open sets [3]. In particular, we show that for a given mixed weakly (μ1ν2)-continuous function, if the codomain of the given function is mixed regular (=(ν12)-regular), then the function is also (μ1)-continuous.

Restricted access

Abstract

The correctness of the problem of optimal control by the coefficients for a weakly nonlinear hyperbolic equation is studied, and a necessary condition of optimality is established.

Restricted access

Abstract

This paper focuses on boundary value problems for anisotropic differential-operator equations of high order with variable coefficients in the half plane. Several conditions are obtained which guarantee the maximal regularity of anisotropic elliptic and parabolic problems in Banach-valued L p-spaces. Especially, it is shown that this differential operator is R-positive and is a generator of an analytic semigroup. These results are also applied to infinite systems of anisotropic type partial differential equations in the half plane.

Restricted access

Abstract

We obtain the structure theorem for -Hopf bimodules over Hopf algebroids, where H is the total algebra of the Hopf algebroid . Based on this theorem, we investigate the structure theorem for comodule algebras over Hopf algebroids.

Restricted access

Abstract

Scientific literature recommender systems (SLRSs) provide papers to researchers according to their scientific interests. Systems rely on inter-researcher similarity measures that are usually computed according to publication contents (i.e., by extracting paper topics and citations). We highlight two major issues related to this design. The required full-text access and processing are expensive and hardly feasible. Moreover, clues about meetings, encounters, and informal exchanges between researchers (which are related to a social dimension) were not exploited to date. In order to tackle these issues, we propose an original SLRS based on a threefold contribution. First, we argue the case for defining inter-researcher similarity measures building on publicly available metadata. Second, we define topical and social measures that we combine together to issue socio-topical recommendations. Third, we conduct an evaluation with 71 volunteer researchers to check researchers’ perception against socio-topical similarities. Experimental results show a significant 11.21% accuracy improvement of socio-topical recommendations compared to baseline topical recommendations.

Restricted access

Abstract

The object of the present work is to obtain a necessary condition for the existence of weakly symmetric and weakly Ricci-symmetric Sasakian manifolds admitting a quarter-symmetric metric connection.

Restricted access

Abstract

The problem of representability of quadratic functionals (acting on modules over unital complex ∗-algebras), by sesquilinear forms, is generalized by weakening the homogeneity equation. The corresponding representation theorem can be considered as a generalization of (the original form of) the classical Jordan–von Neumann characterization of complex inner product spaces.

Restricted access

Abstract

Best trigonometric approximation in L p, 1≦p≦∞, is characterized by a modulus of smoothness, which is equivalent to zero if the function is a trigonometric polynomial of a given degree. The characterization is similar to the one given by the classical modulus of smoothness. The modulus possesses properties similar to those of the classical one.

Restricted access
Authors: Karin Cvetko-Vah, Damjana Kokol Bukovšek, Tomaž Košir and Ganna Kudryavtseva

Abstract

We prove that the minimal cardinality of a semitransitive subsemigroup in the singular part of the symmetric inverse semigroup is 2np+1, where p is the greatest proper divisor of n, and classify all semitransitive subsemigroups of this minimal cardinality.

Restricted access

Abstract

We give a simple elementary proof of the statement above.

Restricted access
Authors: Alfred Geroldinger, David J. Grynkiewicz and Wolfgang A. Schmid

Abstract

For a finite abelian group G and a positive integer d, let s d(G) denote the smallest integer ∊ℕ0 such that every sequence S over G of length |S|≧ has a nonempty zero-sum subsequence T of length |T|≡0 mod d. We determine s d(G) for all d≧1 when G has rank at most two and, under mild conditions on d, also obtain precise values in the case of p-groups. In the same spirit, we obtain new upper bounds for the Erdős–Ginzburg–Ziv constant provided that, for the p-subgroups G p of G, the Davenport constant D(G p) is bounded above by 2exp  (G p)−1. This generalizes former results for groups of rank two.

Restricted access
Authors: Takao Furukawa, Nobuyuki Shirakawa and Kumi Okuwada

Abstract

This study proposes a quantitative analysis of researcher mobility (i.e. transfer from one institution to another) and collaborative networks on the basis of author background data extracted from biographical notes in scientific articles to identify connections that are not revealed via simple co-authorship analysis. Using a top-ranked journal in the field of computer vision, we create a layered network that describes various aspects of author backgrounds, demonstrating a geographical distribution of institutions. We classify networks according to various dimensions including authors, institutions and countries. The results of the quantitative analysis indicate that mobility networks extend beyond the typical collaborative networks describing institutional and international relationships. We also discuss sectoral collaboration considering the mobility networks. Our findings indicate a limitation of collaborative analysis based on bibliometric data and the importance of tracing researcher mobility within potential networks to identify the true nature of scientific collaboration.

Restricted access
Authors: Ludo Waltman, Nees Jan van Eck, Thed N. van Leeuwen, Martijn S. Visser and Anthony F. J. van Raan

Abstract

We present an empirical comparison between two normalization mechanisms for citation-based indicators of research performance. These mechanisms aim to normalize citation counts for the field and the year in which a publication was published. One mechanism is applied in the current so-called crown indicator of our institute. The other mechanism is applied in the new crown indicator that our institute is currently exploring. We find that at high aggregation levels, such as at the level of large research institutions or at the level of countries, the differences between the two mechanisms are very small. At lower aggregation levels, such as at the level of research groups or at the level of journals, the differences between the two mechanisms are somewhat larger. We pay special attention to the way in which recent publications are handled. These publications typically have very low citation counts and should therefore be handled with special care.

Open access

Abstract

We give a systematic discussion on the relationship among generalized topologies, generalized neighborhood systems, and generalized interior operators. As some applications, we answer a question raised in [7] by Shen, and characterize generalized continuous maps.

Restricted access

Abstract

In a previous work [3], the current author, together with P. R. Hall, studied various kinds of primeness in near-rings and sandwich near-rings of continuous functions. In this paper, we study various prime radicals for sandwich near-rings. In certain cases, complete characterisations of the prime, 3-prime, equiprime and strongly equiprime radicals are obtained.

Restricted access
Authors: Veljko Jeremic, Milica Bulajic, Milan Martic and Zoran Radojicic

Abstract

The aim of this article is to present new ideas in evaluating Shanghai University's Academic Ranking of World Universities (ARWU). One issue frequently put forth in various publications is that the Shanghai rankings are sensitive to the relative weight they attribute to each variable. As a possible remedy to this issue, the statistical I-distance method is proposed to be used. Based on a sample containing the top 100 ranked universities, the results show a significant correlation with the official ARWU list. However, some inconsistencies concerning European universities have been noticed and elaborated upon.

Restricted access

Abstract

There are few comprehensive studies and categorization schemes to discuss the characteristics for both data mining and customer relationship management (CRM) although they have already become more important recently. Using a bibliometric approach, this paper analyzes data mining and CRM research trends from 1989 to 2009 by locating headings “data mining” and “customer relationship management” or “CRM” in topics in the SSCI database. The bibliometric analytical technique was used to examine these two topics in SSCI journals from 1989 to 2009, we found 1181 articles with data mining and 1145 articles with CRM. This paper implemented and classified data mining and CRM articles using the following eight categories—publication year, citation, country/territory, document type, institute name, language, source title and subject area—for different distribution status in order to explore the differences and how data mining and CRM technologies have developed in this period and to analyze data mining and CRM technology tendencies under the above result. Also, the paper performs the K–S test to check whether the analysis follows Lotka's law. The research findings can be extended to investigate author productivity by analyzing variables such as chronological and academic age, number and frequency of previous publications, access to research grants, job status, etc. In such a way characteristics of high, medium and low publishing activity of authors can be identified. Besides, these findings will also help to judge scientific research trends and understand the scale of development of research in data mining and CRM through comparing the increases of the article author. Based on the above information, governments and enterprises may infer collective tendencies and demands for scientific researcher in data mining and CRM to formulate appropriate training strategies and policies in the future. This analysis provides a roadmap for future research, abstracts technology trends and facilitates knowledge accumulations so that data mining and CRM researchers can save some time since core knowledge will be concentrated in core categories. This implies that the phenomenon “success breeds success” is more common in higher quality publications.

Restricted access

Abstract  

Aggregated processes appear in many areas of statistics, natural sciences and economics and studying their behavior has a considerable importance from a purely probabilistic point of view as well. Granger (1980) showed that aggregating processes of simple structure can lead to processes with much more complex dynamics, in particular, aggregating random coefficient AR(1) processes can result in long memory processes. This opens a new way to analyze complex processes by constructing such processes from simple ‘building blocks’ via aggregation. The basic statistical problem of aggregation theory is, given a sample {Y 1 (N), …, Y n (N)} of size n of the N-fold aggregated process, to draw conclusions for the structure of the constituting processes (“disaggregation”) and use this for describing the asymptotic behavior of the aggregated process. Probabilistically, this requires determining the limit distribution of nonlinear functionals of {Y 1 (N), …, Y n (N)}, which depends sensitively on the relative order of n and N. In this survey paper, we give a detailed asymptotic study of aggregated linear processes with an arbitrary (possibly infinite) number of parameters and apply the results to the disaggregation problem of AR(1) and AR(2) processes. We also discuss the problem of long memory of aggregated processes.

Restricted access

Abstract

An increasing number of nations allocate public funds to research institutions on the basis of rankings obtained from national evaluation exercises. Therefore, in non-competitive higher education systems where top scientists are dispersed among all the universities, rather than concentrated among a few, there is a high risk of penalizing those top scientists who work in lower-performance universities. Using a 5 year bibliometric analysis conducted on all Italian universities active in the hard sciences from 2004 to 2008, this work analyzes the distribution of publications and relevant citations by scientists within the universities, measures the research performance of individual scientists, quantifies the intensity of concentration of top scientists at each university, provides performance rankings for the universities, and indicates the effects of selective funding on the top scientists of low-ranked universities.

Restricted access

Abstract

Bibliometric data on psychology publications from 1977 through 2008 are modeled and forecasted for the 10 years following 2008. Data refer to the raw frequencies of the PsycINFO (94% English-language, mainly Anglo-American publications) and the English-language documents of PSYNDEX (publications from the German-speaking countries). The series were modelled by way of exponential smoothing. In contrast to Single Moving Average methods which do not weigh observations, exponential smoothing assigns differential weights to observations. Weights reflect the distance from the most recent data point. Results suggest strongly expanding publication activities which can be represented by exponential functions. In addition, forecasted publication activities, estimated based on psychology publication frequencies in the past, show positive bibliometric trends in the Anglo-American research community. These trends go in parallel the bibliometric trends for the English-language publications of German-speaking authors. However, while positive trends were forecasted for all psychological subdisciplines of the Anglo-American publication database PsycINFO, negative bibliometric trends were estimated for English-language publications from German-speaking authors in 6 out of 20 subdisciplines.

Restricted access

Abstract  

In this paper the third order long-range dependence (LRD) is defined in terms of the bispectrum and third order cumulants (bicovariances). Two particular non-Gaussian processes with second order LRD are considered together with their bispectra and bicovariances.

Restricted access

Abstract  

The well-known characterization indicated in the title involves the moving maximal dyadic averages of the sequence (X k: k = 1, 2, …) of random variables in Probability Theory. In the present paper, we offer another characterization of the SLLN which does not require to form any maximum. Instead, it involves only a specially selected sequence of moving averages. The results are also extended for random fields (X k: k, ℓ = 1, 2, …).

Restricted access

Abstract  

Firstly, we compute the distribution function for the hitting time of a linear time-dependent boundary ta + bt, a ≥ 0, b ∈ ℝ, by a reflecting Brownian motion. The main tool hereby is Doob’s formula which gives the probability that Brownian motion started inside a wedge does not hit this wedge. Other key ingredients are the time inversion property of Brownian motion and the time reversal property of diffusion bridges. Secondly, this methodology can also be applied for the three-dimensional Bessel process. Thirdly, we consider Bessel bridges from 0 to 0 with dimension parameter δ > 0 and show that the probability that such a Bessel bridge crosses an affine boundary is equal to the probability that this Bessel bridge stays below some fixed value.

Restricted access

Abstract  

We investigate the repeated and sequential portfolio St. Petersburg games. For the repeated St. Petersburg game, we show an upper bound on the tail distribution, which implies a strong law for a truncation. Moreover, we consider the problem of limit distribution. For the sequential portfolio St. Petersburg game, we obtain tight asymptotic results for the growth rate of the game.

Restricted access
Authors: István Berkes, Wolfgang Müller and Michel Weber

Abstract  

Let f(n) be a strongly additive complex-valued arithmetic function. Under mild conditions on f, we prove the following weighted strong law of large numbers: if X,X 1,X 2, … is any sequence of integrable i.i.d. random variables, then

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathop {\lim }\limits_{N \to \infty } \frac{{\sum\nolimits_{n = 1}^N {f(n)X_n } }} {{\sum\nolimits_{n = 1}^N {f(n)} }} = \mathbb{E}Xa.s.$$ \end{document}