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Practical Data (practical + data)

Distribution by Scientific Domains
Mathematics and Statistics40%

Selected Abstracts

Legibility evaluation using point-of-regard measurement

ELECTRICAL ENGINEERING IN JAPAN, Issue 4 2008
Daisuke Saito
Abstract Web site visibility has become important because of the rapid dissemination of the World Wide Web, and combinations of foreground and background colors are crucial in providing high visibility. In our previous studies, the visibilities of several web-safe color combinations were examined using a psychological method. In those studies, simple stimuli were used because of experimental restriction. In this paper, legibility of sentences on web sites was examined using a psychophysiological method, point-of-regard measurement, to obtain other practical data. Ten people with normal color sensations ranging from ages 21 to 29 were recruited. The number of characters per line in each page was arranged in the same number, and the four representative achromatic web-safe colors, that is, #000000, #666666, #999999, and #CCCCCC, were examined. The reading time per character and the gaze time per line were obtained from point-of-regard measurement, and the normalized with the reading time and the gaze time of the three colors were calculated and compared. It was found that the time of reading and gaze become long at the same ratio when the contrast decreases by point-of-regard measurement. Therefore, it was indicated that the legibility of color combinations could be estimated by point-of-regard measurement. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 35,42, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20612 [source]

Statistical issues on the determination of the no-observed-adverse-effect levels in toxicology

ENVIRONMETRICS, Issue 4 2001
Takashi Yanagawa
Abstract The determination of a safe exposure level for toxic agents, often defined as the highest dose level with no toxic effect and termed the no-observed-adverse-effect level (NOAEL) is reviewed. The conventional methods based on statistical tests are criticized, particularly when the sample size is small, and an alternative method, which is based on the Akaike information criterion (AIC), is discussed. The method is extended to the estimation of the NOAEL for continuous data. Computer programs for Windows 95/NT for determining the NOAEL by the AIC approach are developed and its application to practical data is illustrated with examples. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Relations between the continuous and the discrete Lotka power function

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2005
L Egghe
The discrete Lotka power function describes the number of sources (e.g., authors) with n = 1, 2, 3, , items (e.g., publications). As in econometrics, informetrics theory requires functions of a continuous variable j, replacing the discrete variable n. Now j represents item densities instead of number of items. The continuous Lotka power function describes the density of sources with item density j. The discrete Lotka function one obtains from data, obtained empirically; the continuous Lotka function is the one needed when one wants to apply Lotkaian informetrics, i.e., to determine properties that can be derived from the (continuous) model. It is, hence, important to know the relations between the two models. We show that the exponents of the discrete Lotka function (if not too high, i.e., within limits encountered in practice) and of the continuous Lotka function are approximately the same. This is important to know in applying theoretical results (from the continuous model), derived from practical data. [source]

Moment estimation for statistics from marked point processes

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 2 2001
Dimitris N. Politis
In spatial statistics the data typically consist of measurements of some quantity at irregularly scattered locations; in other words, the data form a realization of a marked point process. In this paper, we formulate subsampling estimators of the moments of general statistics computed from marked point process data, and we establish their L2 -consistency. The variance estimator in particular can be used for the construction of confidence intervals for estimated parameters. A practical data-based method for choosing a subsampling parameter is given and illustrated on a data set. Finite sample simulation examples are also presented. [source]

Systematic interpretation of cyclic nucleotide binding studies using KinetXBase

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 6 2008
Sonja Schweinsberg
Abstract Functional proteomics aims to describe cellular protein networks in depth based on the quantification of molecular interactions. In order to study the interaction of adenosine-3,,5,-cyclic monophosphate (cAMP), a general second messenger involved in several intracellular signalling networks, with one of its respective target proteins, the regulatory (R) subunit of cAMP dependent protein kinase (PKA), a number of different methods was employed. These include fluorescence polarisation (FP), isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), amplified luminescence proximity homogeneous assay (ALPHA-screen), radioligand binding or activity-based assays. Kinetic, thermodynamic and equilibrium binding data of a variety of cAMP derivatives to several cAMP binding domains were integrated in a single database system, we called KinetXBase, allowing for very distinct data formats. KinetXBase is a practical data handling system for molecular interaction data of any kind, providing a synopsis of data derived from different technologies. This supports ongoing efforts in the bioinformatics community to devise formal concepts for a unified representation of interaction data, in order to enable their exchange and easy comparison. KinetXBase was applied here to analyse complex cAMP binding data and highly site-specific cAMP analogues could be identified. The software package is free for download by academic users. [source]