We study the hyperbolicity of metric spaces in the Gromov sense. We deduce the hyperbolicity of a space from the hyperbolicity
of its “building block components”. These results are valuable since they simplify notably the topology of the space and allow
to obtain global results from local information. We also study how the punctures and the decomposition of a Riemann surface
in Y-pieces and funnels affect the hyperbolicity of the surface.
This study compares the citations characteristics of researchers in engineering disciplines with other major scientific disciplines,
and investigates variations in citing patterns within subdisciplines in the field of engineering. Utilizing citations statistics
including Hirsch’s (Proc Natl Acad Sci USA 102(46):16569–16572, <cite>2005</cite>) h-index value, we find that significant differences in citing characteristics exist between engineering disciplines and
other scientific fields. Our findings also reveal statistical differences in citing characteristics between subdisciplines
found within the same engineering discipline.
Authors:Éva Czabarka, Inne Singgih, Laszlό Székely, and Zhiyu Wang
We verify an upper bound of Pach and Tóth from 1997 on the midrange crossing constant. Details of their upper bound have not been available. Our verification is different from their method and hinges on a result of Moon from 1965. As Moon’s result is optimal, we raise the question whether the midrange crossing constant is .
Authors:Eva Sønderstrup-Andersen and Hans Sønderstrup-Andersen
Currently the Journal Impact Factors (JIF) attracts considerable attention as components in the evaluation of the quality
of research in and between institutions. This paper reports on a questionnaire study of the publishing behaviour and researchers
preferences for seeking new knowledge information and the possible influence of JIF on these variables. 54 Danish medical
researchers active in the field of Diabetes research took part. We asked the researchers to prioritise a series of scientific
journals with respect to which journals they prefer for publishing research and gaining new knowledge. In addition we requested
the researchers to indicate whether or not the JIF of the prioritised journals has had any influence on these decisions. Furthermore
we explored the perception of the researchers as to what degree the JIF could be considered a reliable, stable or objective
measure for determining the scientific quality of journals. Moreover we asked the researchers to judge the applicability of
JIF as a measure for doing research evaluations. One remarkable result is that app. 80% of the researchers share the opinion
that JIF does indeed have an influence on which journals they would prefer for publishing. As such we found a statistically
significant correlation between how the researchers ranked the journals and the JIF of the ranked journals. Another notable
result is that no significant correlation exists between journals where the researchers actually have published papers and
journals in which they would prefer to publish in the future measured by JIF. This could be taken as an indicator for the
actual motivational influence on the publication behaviour of the researchers. That is, the impact factor actually works in
our case. It seems that the researchers find it fair and reliable to use the Journal Impact Factor for research evaluation
Authors:Éva Csáki, M. Csőrgő, A. Főldes, and Z. Shi
Sample path properties of the Cauchy principal values of Brownian and random walk local times are studied. We establish LIL type results (without exact constants). Large and small increments are discussed. A strong approximation result between the above two processes is also proved.