Modified biserial correlation coefficients

Asymptotic distribution theory of Brogden's form of biserial correlation coefficient is derived and large sample estimates of its standard error obtained. Its efficiency relative to the biserial correlation coefficient is examined. Other modifications of the statistic are evaluated, and on the basis of these results, recommendations for choice of estimator of biserial correlation are presented.Supported by the National Institute of Mental Health Specialized Research Center Grant #MH-30854 and by the National Institute of Mental Health Grant #MH-11028.     

On logic of complex algorithms

An algebraic approach to programs called recursive coroutines — due to Janicki [3] — is based on the idea to consider certain complex algorithms as algebraics models of those programs. Complex algorithms are generalizations of pushdown algorithms being algebraic models of recursive procedures (see Mazurkiewicz [4]). LCA — logic of complex algorithms — was formulated in [11]. It formalizes algorithmic properties of a class of deterministic programs called here complex recursive ones or interacting stacks-programs, for which complex algorithms constitute mathematical models. LCA is in a sense an extension of algorithmic logic as initiated by Salwicki [14] and of extended algorithmic logic EAL as formulated and examined by the present author in [8], [9], [10]. In LCA — similarly as in EAL-ω ⁺ -valued logic is applied as a tool to construct control systems (stacks) occurring in corresponding algorithms. The aim of this paper is to give a complete axiomatization. of LCA and to prove a completeness theorem. Logic of complex algorithms was presented at FCT'79 (International Symposium on Fundamentals of Computation Theory, Berlin 1979)     

Tests of homogeneity of independent correlation coefficients

It is demonstrated that tests of homogeneity of independent correlation coefficients based on the simple forms of the normal andt approximations to the distribution of the correlation coefficients are comparable in terms of robustness, size and power.     

Body mass index and waist: hip ratio are not enough to characterise female attractiveness

The assessment of characteristic body features of Miss Poland beauty contest finalists compared with the control group, can contribute to recognising the contemporary ideal of beauty promoted by the mass media. The studies of Playboy models and fashion models conducted so far have been limited to the following determinants of attractiveness: body mass index, waist:hip ratio, and waist:chest ratio, which only partially describe the body shape. We compared 20 body features of the finalists of Miss Poland 2004 beauty contest with those of the students of Medical Academy in Bydgoszcz. Discriminant analysis showed that the thigh girth-height index, waist: chest ratio, height, and body mass index had the greatest discrimination power distinguishing the two groups. A model of Miss Poland finalists figure assessment is presented which allows one to distinguish super-attractive women from the control group.     

A motion capture library for the study of identity, gender, and emotion perception from biological motion

We present the methods that were used in capturing a library of human movements for use in computer-animated displays of human movement. The library is an attempt to systematically tap into and represent the wide range of personal properties, such as identity, gender, and emotion, that are available in a person's movements. The movements from a total of 30 nonprofessional actors (15 of them female) were captured while they performed walking, knocking, lifting, and throwing actions, as well as their combination in angry, happy, neutral, and sad affective styles. From the raw motion capture data, a library of 4,080 movements was obtained, using techniques based on Character Studio (plug-ins for 3D Studio MAX, AutoDesk, Inc.), MATLAB The MathWorks, Inc.), or a combination of these two. For the knocking, lifting, and throwing actions, 10 repetitions of the simple action unit were obtained for each affect, and for the other actions, two longer movement recordings were obtained for each affect. We discuss the potential use of the library for computational and behavioral analyses of movement variability, of human character animation, and of how gender, emotion, and identity are encoded and decoded from human movement.     

Figures of Time in Evolution of Complex Systems

Owing to intensive development of the theory of self-organization of complex systems called also synergetics, profound changes in our notions of time occur. Whereas at the beginning of the 20th century, natural sciences, by picking up the general spirit of Einstein's theory of relativity, consider a geometrization as an ideal, i.e. try to represent time and force interactions through space and the changes of its properties, nowadays, at the beginning of the 21st century, time turns to be in the focus of attention. It turns to be possible to represent space through time, because synergetics shows that historical and evolutionary stages of development of a complex structure can be found now, in its present spatial configuration. A whole series of paradoxical notions, such as “the influence of the future upon the present”, a “possibility of touching of a rather remote future today”, “availability of the past and the future now, in praesenti”, “irreversibility and elements of reversibility in the course of evolutionary processes in time”, “discrete unites, quanta of time”, appear in synergetics.     

Na+,K(+)-ATPase activity is reduced in hippocampus of rats submitted to an experimental model of depression: effect of chronic lithium treatment and possible involvement in learning deficits

This study was undertaken to verify the effects of chronic stress and lithium treatments on the hippocampal Na+,K(+)-ATPase activity of rats, as well as to investigate the effects of stress interruption and post-stress lithium treatment on this enzyme activity and on spatial memory. Two experiments were carried out; in the first experiment, adult male Wistar rats were divided into two groups: control and submitted to a chronic variate stress paradigm, and subdivided into treated or not with LiCl. After 40 days of treatment, rats were killed, and Na+,K(+)-ATPase activity was determined. In the second experiment, rats were stressed during 40 days, and their performance was evaluated in the Water Maze task. The stressed group was then subdivided into four groups, with continued or interrupted stress treatment and treated or not with lithium for 30 additional days. After a second evaluation of performance in the Water Maze, rats were killed and Na+,K(+)-ATPase activity was also measured. Results showed an impairment in Na+,K(+)-ATPase activity and in Water Maze performance of chronically stressed rats, which were prevented by lithium treatment and reversed by lithium treatment and by stress interruption. These results suggest that the modulation of Na+,K(+)-ATPase activity may be one of the mechanisms of action of lithium in the treatment of mood disorders.     

A simple effect size indicator for two-group comparisons? A comment on r equivalent

R. Rosenthal and D. B. Rubin (2003) proposed an effect size, r equivalent, to be used when (a) only sample size and p values are known for a study, (b) there are no generally accepted effect size indicators, or (c) sample sizes are so small or the data so non-normal that the directly computed effect sizes would be more misleading than the simple effect size. The limitations of their proposal, however, are many, and much more serious than the authors suggested, and should be carefully considered before this effect size is applied, as well as in developing other effect sizes using similar methods.