1,721,588 research outputs found
Two topics in geometric group theory
No full textNiblo and Reeves [NR2] constructed a cubing for each Coxeter group using the hyperplanes of the Coxeter complex. In Part 1 Coxeter groups and cubings the natural action of the Coxeter group on this cubing is investigated. In particular the cocompactness or not of this action is studied. Using the geometry of the Moussong complex (another complex for a Coxeter group introduced by Gabor Moussong in [Mou]) it is shown that hyperbolic and right-angled Coxeter groups act cocompactly and Euclidean Coxeter groups act non-cocompactly and that the action is non-cocompact if and only if there exists an infinite family of non-conjugate isomorphic triangle subgroups.In Part II Engulfing and subgroup separability for word-hyperbolic groups theorems of Darren Long [L] concerning fundamental groups of closed hyperbolic manifolds are generalised to word-hyperbolic groups. The main result is that if a torsion-free word-hyperbolic group has a certain engulfing property then every quasiconvex subgroup is contained as a finite index subgroup in a separable subgroup.</p
Development and characterization of PILOT: a transportable instrument for laser-induced grating spectroscopy
Full text linkThis data was created during the characterisation of the PILOT instrument. The "Accuracy and precision" dataset was collected by a Wavesurfer 3074 oscilloscope from Teledyne LeCroy, while the remaining datasets were collected by a Picoscope 6424E from Pico Technology
Polarised-depolarised Rayleigh scattering for simultaneous composition and temperature measurements in non-isothermal gaseous mixtures
Full text linkThe data was collected between February 2018 and May 2019. The data stored are raw image (.tif) files, some experimentally-acquired, and some software-generated. There are 3 main datasets. The first of these are from polarised-depolarised Rayleigh scattering experiments conducted on a gaseous mixture of CO2 and N2. Data was collected from two opposite facing cameras imaging a single area of interest where a mixture of gases was illuminated with a laser sheet. The goal of this experiment was to demonstrate PDRS as a plausible optical diagnostic technique for non-isothermal gaseous mixtures. The second dataset was obtained by taking pictures of a white wall using varying lens apertures. This was to obtain an estimate for the shot noise characteristic of the camera, which could then be used in a numerical sensitivity analysis. The final dataset consists of an arbitrary 2D mixture fraction and temperature field (in image form), also used in the numerical sensitivity analysis. These images were produced using Paint
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Inexpensive multi-plane particle image velocimetry based on defocusing: proof of concept on two-component measurement
No full textThese are the raw data of the laminar flow rig test presented in the article "Inexpensive multi-plane particle image velocimetry based on defocusing: proof of concept on two-component measurement". They include horizontal and vertical flow directions, focused and defocused images with different plane separations (in which 0mm indicates in-focus images), and different particle displacements (quantified by delta_t of the PIV image pair). Please contact [email protected] if you have any queries. Details for accessing the optical engine data is referred to Optical_Engine_Data_Access.txt
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Full text linkWe 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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