125,199 research outputs found
A bound for the number of columns l(c,a,b) in the intersection array of a distance-regular graph
No full textIn this paper we give a bound for the number l(c,a,b) of columns (c,a,b)T in the intersection array of a distance-regular graph. We also show that this bound is intimately related to the Bannai–Ito conjecture
The distance-regular graphs such that all of its second largest local eigenvalues are at most one
No full textIn this paper, we classify distance-regular graphs such that all of its second largest local eigenvalues are at most one. Also we discuss the consequences for the smallest eigenvalue of a distance-regular graph. These extend a result by the first author, who classified the distance-regular graphs with smallest eigenvalue -1 - b(1)/2. (C) 2011 Elsevier Inc. All rights reserved.X1154sciescopu
A short proof of a theorem of Bang and Koolen
No full textAbstractLet a graph Γ be locally a disjoint union of three copies of complete graphs Kq−1 and let Γ be cospectral with the Hamming graph H(3,q). Bang and Koolen [S. Bang, J.H. Koolen, Graphs cospectral with H(3,q) which are disjoint unions of at most three complete graphs, Asian–Eur. J. Math. 1 (2008) 147–156] proved that if q>3, then Γ is isomorphic to H(3,q). We present a short proof of this result
Correction to: The ‘can do, do do’ concept in COPD; quadrant interpretation, affiliation and tracking longitudinal changes
No full textFollowing publication of the original article [1], the authors identified a mistake in the author names, as both forename and initials were stated. Initially published author names: A. J. Alex van ’t Hul, E. H. Noortje Koolen, H. W. Jeroen van Hees, B. Bram van den Borst and M. A. Martijn Spruit Correct author names: Alex J. van ‘t Hul, Noortje H. Koolen, Jeroen W. van Hees, Bram van den Borst, Martijn A. Spruit. The original article has been corrected.</p
Koolen-de Vries Syndrome: a journey from diagnosis to treatments
No full textThe Koolen-de Vries Syndrome Foundation was founded in 2013 with the mission to educate, increase awareness, promote research and develop treatments for individuals living with Koolen-de Vries Syndrome (KdVS) and their families. With this aim, the foundation has focused on: developing scientific resources through patient cell and animal models, providing seed funding to basic and clinical researchers, establishing a natural history study of KdVS and increasing patient engagement. Projects have been prioritized across these areas of focus with an emphasis on expanding international research on KdVS, supporting translational research, establishing an international natural history study and conducting studies to assess patient priorities. With the incredible growth amongst our research and patient community in the last decade, our goal is to have our first clinical trial for KdVS in 2026
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Triangle- and pentagon-free distance-regular graphs with an eigenvalue multiplicity equal to the valency
No full textWe classify triangle- and pentagon-free distance-regular graphs with diameter d >= 2, valency k, and an eigenvalue multiplicity k. In particular, we prove that such a graph is isomorphic to a cycle, a k-cube, a complete bipartite graph minus a matching, a Hadamard graph, a distance-regular graph with intersection array {k, k-1, k-c, c, 1; 1, c, k-c, k-1, k}, where k = gamma(gamma(2) + 3 gamma + 1), c = gamma(gamma + 1), gamma is an element of N, or a folded k-cube, k odd and k >= 7. This is a generalization of the results of Nomura (J. Combin. Theory Ser. B 64 (1995) 300-313) and Yamazaki (J. Combin. Theory Ser. B 66 (1996) 34-37), where they classified bipartite distance-regular graphs with an eigenvalue multiplicity k and showed that all such graphs are 2-homogeneous. We also classify bipartite almost 2-homogeneous distance-regular graphs with diameter d >=, 4. In particular, we prove that such a graph is either 2-homogeneous (and thus classified by Nomura and Yamazaki), or a folded k-cube for k even, or a generalized 2d-gon with order (1, k-1). (c) 2005 Elsevier Inc. All rights reserved.X116sciescopu
Shilla distance-regular graphs
No full textA Shilla distance-regular graph Gamma (say with valency k) is a distance-regular graph with diameter 3 such that as second-largest eigenvalue equals a(3). We will show that a(3) divides k for a Shilla distance-regular graph Gamma, and for Gamma we define b = b(Gamma) = k/a(3) In this paper we will show that there are finitely many Shilla distance-regular graphs Gamma with fixed b(Gamma) >= 2 Also, we will classify Shilla distance-regular graphs with b(Gamma) = 2 and b(Gamma) = 3 Furthermore, we will give a new existence condition for distance-regular graphs, in general. (C) 2010 Elsevier Ltd. All rights reservedX111912sciescopu
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
On distance-regular graphs with smallest eigenvalue at least -m
No full textA non-complete geometric distance-regular graph is the point graph of a partial linear space in which the set of lines is a set of Delsarte cliques. In this paper, we prove that for a fixed integer m >= 2, there are only finitely many non-geometric distance-regular graphs with smallest eigenvalue at least -m, diameter at least three and intersection number c(2) >= 2. (C) 2010 Elsevier Inc. All rights reserved.X111311sciescopu
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