186,315 research outputs found
Scaled Enflo type is equivalent to Rademacher type
Get PDFWe introduce the notion of the scaled Enflo type of a metric space, and show that for Banach spaces, scaled Enflo type p is equivalent to Rademacher type p
Extremal vectors and rectifiability
No full textThe concept of extremal vectors of a linear operator with a dense range but not onto on a Hilbert space was introduced by P. Enflo in 1996 as a new approach to study invariant subspaces. Following this, there were several studies on analytic and geometric properties of backward minimal vectors and their applications to construction of invariant subspaces. In this paper, we consider one other property: rectifiability. We show that in general curves that map numbers to backward minimal vectors are not rectifiable.Quaestiones Mathematicae 34(2011), 119-12
Relative Sources of European Regional Productivity Convergence: A Bootstrap Frontier Approach
No full textEnflo K. and Hjertstrand P. Relative sources of European regional productivity convergence: a bootstrap frontier approach, Regional Studies. This paper addresses the issue of Western European regional productivity growth and convergence by means of data envelopment analysis (DEA), decomposing labour productivity into efficiency change, technical change and capital accumulation. The decomposition shows that most regions have fallen behind the production frontier in efficiency and that capital accumulation has had a diverging effect on the labour productivity distribution. Using bootstrapping methods, the paper also accounts for the inherent bias and the stochastic elements in the efficiency estimation. It is found that the relative ranking of the efficiency scores remains stable after the bias correction, even after controlling for spatially correlated measurement errors, and that the DEA successfully identifies the regions on the production frontier as significantly more efficient than other regions
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Effects of vocal loading on the phonation and collision threshold pressures
No full textPhonation threshold pressures (PTP) have been commonly used for obtaining a quantita-tive measure of vocal fold motility. However, as these measures are quite low, it is typically dif-ficult to obtain reliable data. As the amplitude of an electroglottograph (EGG) signal de-creases substantially at the loss of vocal fold contact, it is mostly easy to determine the colli-sion threshold pressure (CTP) from an EGG signal. In an earlier investigation (Enflo & Sundberg, forthcoming) we measured CTP and compared it with PTP in singer subjects. Re-sults showed that in these subjects CTP was on average about 4 cm H2O higher than PTP. The PTP has been found to increase during vocal fatigue. In the present study we compare PTP and CTP before and after vocal loading in singer and non-singer voices, applying a load-ing procedure previously used by co-author FP. Seven subjects repeated the vowel se-quence /a,e,i,o,u/ at an SPL of at least 80 dB @ 0.3 m for 20 min. Before and after the loading the subjects’ voices were recorded while they produced a diminuendo repeating the syllable /pa/. Oral pressure during the /p/ occlusion was used as a measure of subglottal pressure. Both CTP and PTP increased significantly after the vocal loading.</p
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
On the evolution of a spherical short pulse in nonlinear acoustics
No full textPlanar wave propagation in nonlinear acoustics is modeled by the Burgers equation, which is exactly soluble. Spherical wave propagation is modeled by a generalized Burgers equation, in which the dissipative parameter of the plane wave Burgers equation is replaced by an exponentially growing function of the variable symbolizing the travelled length of the wave. A procedure previously used in 1998 by B.O. Enflo [1] on cylindrical short pulses is now used on spherical short pulses, which are originally N-waves. The procedure consists of the four steps: 1) A shock solution of the generalized Burgers equation is found by asymptotic matching. The shock fades in the region where the nonlinear term in the equation can be neglected. 2) The linear equation in step 1) is rescaled. It is identically solved by an integral representation containing an unknown function. 3) The integral representation found in step 2) is evaluated by the steepest descent method in the fading shock region introduced in step 1). The unknown function introduced in step 2) is determined by comparing the result of this evaluation with the fading shock solution found in step 1). 4) The integral representation with the unknown function determined is evaluated approximately asymptotically for large values of the original length (or time) variables in the original generalized Burgers equation (old-age regime). The result of this procedure is an old-age solution, controlled by numerical calculations. Curves of analytical and numerical solutions are given.</p
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
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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