Low-dimensional chaos maps learning in a model neuropil (olfactory bulb)

Quantification of a chaotic system can be made by calculating the correlation dimension (D2) of the data that the system generates (Packard et al., 1980). The D2 algorithm, however, requires stationarity of the generator, a feature that biological data rarely reflect (Mayer-Kress et al., 1988). So we developed the “point correlation dimension” (PD2), an algorithm that accurately tracks D2 in linked data of different dimensions (Carpeggiani et al., 1991). We now present a mathematical argument that, for stationary data, individual PD2s converge to D2 and we demonstrate that the algorithm rejects contributions made by bursts of noise. Data were obtained from the surface of the olfactory bulb of the conscious rabbit (64 electrodes, 640 Hz each, 1.3 sec epochs) before and after presentation of a novel or habituated odor. D2 could be calculated in only 1 of 10 novel-odor trials, whereas PD2 could be calculated in all. Both algorithms indicated that a novel odor evokes a spatially uniform dimensional increase. The PD2 uniquely exhibited the dimensional decreases that occur during inspiration and the gradients of mean dimension present during the nonstimulated control state. These control gradients remained unchanged without odor experience, but showed spatially specific PD2 increases following odor habituation. It is interpreted that, 1) the PD2 issensitive, accurate, and appropriate for dimensional assessment of biological data, 2) that during analysis of unfamiliar information a singleglobal process is transiently evoked in the neuropil, and 3) after experience multiplespatially specific processes tonically map the sites of learning. Grant Support: National Institutes of Health, HL 31164 and NS27745     

Interpreting canonical correlation analysis through biplots of structure correlations and weights

This paper extends the biplot technique to canonical correlation analysis and redundancy analysis. The plot of structure correlations is shown to the optimal for displaying the pairwise correlations between the variables of the one set and those of the second. The link between multivariate regression and canonical correlation analysis/redundancy analysis is exploited for producing an optimal biplot that displays a matrix of regression coefficients. This plot can be made from the canonical weights of the predictors and the structure correlations of the criterion variables. An example is used to show how the proposed biplots may be interpreted.     

New lower and upper bounds for communality in factor analysis

We derive several relationships between communalities and the eigenvalues for ap ×p correlation matrix under the usual factor analysis model. For suitable choices ofj, _j (), where _j () is thej-th largest eigenvalue of , provides either a lower or an upper bound to the communalities for some of the variables. We show that for at least one variable, 1 - _p () improves on the use of squared mulitiple correlation coefficient as a lower bound.This research was done while the second author was at Tokyo Institute of Technology.     

The factor structure of the Multiple Affect Adjective Check List-Revised (MAACL-R): Some statistical considerations

In response to Zuckerman's comments on my factor analyses of the MAACL-R, I focus on the statistical issues of the cutoff criterion for factor loadings and the evidence for the discriminant validity of the five-factor solution. Based upon the conclusions I draw in these two areas, I recommend that researchers either (a) use the two factor solution to the MAACL-R represented in the summary scores of Dysphoria and Positive Affect + Sensation Seeking or (b) include all MAACL-R scales in their studies and analyze their data to determine whether it is statistically appropriate to report results from a single scale (A, D, H, PA, or SS) rather than from the summary scores.     

Type A behaviour in pre-school children: Interrater reliability, stability over six months and subcomponents

Type A behaviour was measured in 250 boys and 245 girls (ages 3-7) using a Swedish version of Matthews' Youth Test for Health (MYTH). In addition, speech and voice characteristics (speed, loudness, response latency) were measured. Each child was independently rated by two play group leaders and measurements were repeated after a six month interval. Interrater reliability (first session) was 0.76 for both sexes and did not change with the age of the child. Boys obtained significantly (p less than 0.0001) higher scores than girls. Correlations over the six month period were 0.64 and 0.60 (p less than 0.001) for the two possible combinations of different raters and slightly higher (0.75 and 0.68, p less than 0.001) when the same rater was used. Two components of Type A behaviour were identified from a factor analysis of the data: impatience and competitiveness, and they accounted for 57% of the total variance. As for the total scale, boys obtained significantly higher scores than girls on both subscales. Scores on the competitiveness scale increased systematically with age. Speech and voice characteristics correlated significantly with Type A scores (total Type A behaviour: r = 0.50, using different raters, and 0.71, using the same raters, p less than 0.001) and, once again, boys obtained significantly (p less than 0.001) higher scores than girls. The results are in close agreement with the American findings from the original scale. It was concluded that the scale provides a reliable and valid instrument for measuring Type A or Type A-like behaviours in pre-school children.     

Comments on “the measurement of factorial indeterminacy”

Guttman's index of indeterminacy (2² – 1) measures the potential amount of uncertainty in picking the right alternative interpretation for a factor. When alternative solutions for a factor are equally likely to be correct, then the squared multiple correlation ² for predicting the factor from the observed variables is the average correlation _AB between independently selected alternative solutionsA andB, while var ( _AB )=(1 – ²)²/s, wheres is the dimensionality of the space in which unpredicted components of alternative solutions are to be found. When alternative solutions for the factor are not equally likely to be chosen, ² is the lower bound for E( _AB ); however, E( _AB ) need not be a modal value in the distribution of _AB . Guttman's index and E( _AB ) measure different aspects of the same indeterminacy problem.     

Latent roots of random data correlation matrices with squared multiple correlations on the diagonal: A monte carlo study

In order to make the parallel analysis criterion for determining the number of factors easy to use, regression equations for predicting the logarithms of the latent roots of random correlation matrices, with squared multiple correlations on the diagonal, are presented. The correlation matrices were derived from distributions of normally distributed random numbers. The independent variables are log (N–1) and log {[n(n–1)/2]–[(i–1)n]}, whereN is the number of observations;n, the number of variables; andi, the ordinal position of the eigenvalue. The results were excellent, with multiple correlation coefficients ranging from .9948 to .9992.This research was supported by the Office of Naval Research under Contract N00014-67-A-0305-0012, Lloyd G. Humphreys, principal investigator, and by the Department of Computer Science of which Richard G. Montanelli, Jr., is a member.     

A general factor of personality,social desirability,cognitive ability,and the survey of work styles in an employment selection setting

How a general factor of personality (GFP) correlated with employment screening measures in an applied setting was examined. Participants were 540 adult insurance sales job applicants who completed scales from two personality measures, the five scales from the Survey of Work Styles (SWS), an intelligence measure, and a social desirability scale. A joint factor analysis of the personality questionnaires produced four first order factors. A single GFP was also extracted. Strong correlations were found between some of the personality factors and the SWS scales. Strong significant correlations were found between the GFP and three of the four personality factors with social desirability. Neither the GFP nor the personality factors correlated significantly with cognitive abilities.     

Relationships among higher-order strengths factors,subjective well-being,and general self-efficacy – The case of Israeli adolescents

We investigated relationships among five higher-order strengths factors, subjective well-being, and general self-efficacy in participants that live under challenging conditions. Therefore, a sample of 396 Israeli adolescents (aged 13–18 years) completed the Values in Action Inventory of Strengths for Youth, the Satisfaction With Life Scale, the Affect Balance Scale, and the General Self-Efficacy Scale. An orthogonally rotated principal component analysis of the 24 character strengths yielded five strengths factors that explained 32% of the variance in life satisfaction, with the transcendence strengths factor as the most substantial predictor. The strongest predictors of positive affect were the transcendence and leadership strengths factors; the best predictors of negative affect were the transcendence and temperance strengths factors; and the strongest predictor of affect balance was the transcendence strengths factor. The five strengths factors explained 46% of the variance in general self-efficacy, with the leadership strengths factor as the most substantial predictor. Further analysis indicated that general self-efficacy mediated the relationship between leadership strengths and global life satisfaction. The results suggest that different strengths factors are relevant for different positive experiences (e.g., life satisfaction, self-efficacy beliefs). The findings shed light on the contribution of specific character strengths as a meaningful resource under stressful conditions.     

替格瑞洛与氯吡格雷对急性STEMI患者急诊PCI术后炎症因子的影响

为比较替格瑞洛与氯吡格雷对急性ST段抬高型心肌梗死（STEMI）患者急诊经皮冠状动脉介入术（PCI）术后炎症因子的影响,将176例急性STEMI且行急诊PCI术的患者分为替格瑞洛组（A组）58例、氯吡格雷常规组（B组）58例、氯吡格雷强化组（C组）60例,分别测定术前、术后12小时、术后7天、术后1个月、术后3个月、6个月时炎症因子e反应蛋白（CRP）、白细胞介素-6（IL6）、髓过氧物酶（MPO）、可溶性CD40受体（sCD40L）的含量,比较3组患者各炎症因子在不同时间点有无统计学差异。结果显示c组和A组较B组明显降低（P〈0．05）,有统计学意义,而A组较c组稍降低（P〉0．05）,但两者无统计学意义。由此可见,替格瑞洛的抗炎作用较常规剂量氯吡格雷作用明显增强,和强化剂量氯吡格雷作用相仿。