1,720,964 research outputs found
Graph-different permutations
No full textFor a finite graph G whose vertices are different natural numbers we call two infinite permutations of the natural numbers G-different if they have two adjacent vertices of G somewhere in the same position. The maximum number of pairwise G-different permutations of the naturals is always finite. We study this maximum as a graph invariant and relate it to a problem of the first two authors on colliding permutations. An improvement on the lower bound for the maximum number of pairwise colliding permutations is obtained. © 2008 Society for Industrial and Applied Mathematics
FAMILIES OF GRAPH-DIFFERENT HAMILTON PATHS
No full textLet D subset of N be an arbitrary subset of the natural numbers. For every n, let M(n, D) be the maximum of the cardinality of a set of Hamiltonian paths in the complete graph K-n such that the union of any two paths from the family contains a not necessarily induced cycle of some length from D. We determine or bound the asymptotics of M(n, D) in various special cases. This problem is closely related to that of the permutation capacity of graphs and constitutes a further extension of the problem area around Shannon capacity. We also discuss how to generalize our cycle-difference problems and present an example where cycles are replaced by 4-cliques. These problems are in a natural duality to those of graph intersection, initiated by Erdos, Simonovits, and Sos. The lack of kernel structure as a natural candidate for optimum makes our problems quite challenging
Local chromatic number and Sperner capacity
Get PDFWe introduce a directed analog of the local chromatic number defined by Erdos et al. [Discrete Math. 59 (1986) 21-34] and show that it provides an upper bound for the Sperner capacity of a directed graph. Applications and variants of this result are presented. In particular, we find a special orientation of an odd cycle and show that it achieves the maximum of Sperner capacity among the differently oriented versions of the cycle. We show that apart from this orientation, for all the others an odd cycle has the same Sperner capacity as a single edge graph. We also show that the (undirected) local chromatic number is bounded from below by the fractional chromatic number while for power graphs the two invariants have the same exponential asymptotics (under the co-normal product on which the definition of Sperner capacity is based). We strengthen our bound on Sperner capacity by introducing a fractional relaxation of our directed variant of the local chromatic number. (C) 2005 Elsevier Inc. All rights reserved
Permutation capacities of families of oriented infinite paths
No full textKörner and Malvenuto asked whether one can find (n/2) linear orderings (i.e., permutations) of the first n natural numbers such that any pair of them places two consecutive integers somewhere in the same position. This led to the notion of graph-different permutations. We extend this concept to directed graphs, focusing on orientations of the semi-infinite path whose edges connect consecutive natural numbers. Our main result shows that the maximum number of permutations satisfying all the pairwise conditions associated with all of the various orientations of this path is exponentially smaller, for any single orientation, than the maximum number of those permutations which satisfy the corresponding pairwise relationship. This is in sharp contrast to a result of Gargano, Körner, and Vaccaro concerning the analogous notion of Sperner capacity of families of finite graphs. We improve the exponential lower bound for the original problem and list a number of open questions. © 2010 Society for Industrial and Applied Mathematics
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Benefits of Fixed Dose Combination of Ramipril/Amlodipine in Hypertensive Diabetic Patients: A Subgroup Analysis of RAMONA Trial
No full textBackground: Combination of angiotensin-converting enzyme inhibitors and calcium channel blockers has been successfully used in the antihypertensive therapy for many years. Fixed dose combinations of ramipril/amlodipine have a benefit effect for patients to achieve target blood pressure (BP). This study aimed to assess the efficacy and safety of fixed dose combinations of ramipril and amlodipine (Egiramlon®) in hypertensive diabetic patients.
Methods: Hypertensive diabetic patients who were enrolled into the RAMONA trial were included in this open, prospective, Phase IV observational clinical study. Patients had mild-to-moderate hypertension and failed to reach target BP levels through their previous therapy. During the four months of observation, patients took part in three visits (1st day = visit 1, 1st month = visit 2, and 4th month = visit 3) where they received a fixed dose combination of 5/5, 5/10, 10/5, or 10/10 mg ramipril/amlodipine, respectively, with the possibly required dose titrations, based on the decision of their attending physician. Target BP for diabetic patients was <140/85 mmHg. BP levels were measured in all visits, by taking two readings at 2-min interval. Laboratory tests including full blood count, renal function test, electrolytes, blood glucose, serum cholesterol, uric acid, triglycerides, liver function test, creatinine kinase, and midstream urinalysis were performed at visit 1 and visit 3.
Results: The 6423 patients completed the study. Among these patients, 1276 (19.9%) patients suffered from type 2 diabetes mellitus. The mean age of these diabetic patients was 64.2 ± 10.0 years; 707 (55.4%) patients were males. Target BP was achieved by 891 (69.8%) of diabetic patients at visit 3 (primary endpoint). BP decreased from 157.5/91.3 ± 9.6/7.6 mmHg (visit 1) to 130.9/79.6 ± 7.4/5.8 mmHg (visit 3). As for the secondary endpoint of the study, total cholesterol decreased from 5.50 ± 1.13 mmol/L (visit 1) to 5.20 ± 0.95 mmol/L (P = 0.000), low-density lipoprotein cholesterol decreased from 3.20 ± 0.93 mmol/L to 3.00 ± 0.77 mmol/L (P = 0.000), triglyceride decreased from 2.20 ± 1.14 mmol/L to 2.00 ± 1.97 mmol/L (P = 0.000), while high-density lipoprotein cholesterol increased from 1.30 ± 0.42 to 1.35 ± 0.30 mmol/L (P = 0.001) until the end of the 4th month (visit 3). Fasting blood glucose of the hypertensive diabetic patients decreased from 7.20 ± 1.88 mmol/L to 6.70 ± 1.38 mmol/L (P = 0.000), while HbA1c decreased from 7.90 ± 1.78% to 7.60 ± 1.83% (P = 0.000). Various fixed dose combinations of ramipril/amlodipine were well tolerated and no adverse event related to the use of the medicine has appeared.
Conclusions: The fixed dose combination of ramipril/amlodipine was effective in hypertensive diabetic patients who failed to reach target BP previously
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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