Application of chaos theory to biology and medicine

The application of “chaos theory” to the physical and chemical sciences has resolved some long-standing problems, such as how to calculate a turbulent event in fluid dynamics or how to quantify the pathway of a molecule during Brownian motion. Biology and medicine also have unresolved problems, such as how to predict the occurrence of lethal arrhythmias or epileptic seizures. The quantification of a chaotic system, such as the nervous system, can occur by calculating the correlation dimension (D2) of a sample of the data that the system generates. For biological systems, the point correlation dimension (PD2) has an advantage in that it does not presume stationarity of the data, as the D2 algorithm must, and thus can track the transient non-stationarities that occur when the systems changes state. Such non-stationarities arise during normal functioning (e.g., during an event-related potential) or in pathology (e.g., in epilepsy or cardiac arrhythmogenesis). When stochastic analyses, such as the standard deviation or power spectrum, are performed on the same data they often have a reduced sensitivity and specifity compared to the dimensional measures. For example, a reduced standard deviation of heartbeat intervals can predict increased mortality in a group of cardiac subjects, each of which has a reduced standard deviation, but it cannot specify which individuals will or will not manifest lethal arrhythmogenesis; in contrast, the PD2 of the very same data can specify which patients will manifest sudden death. The explanation for the greater sensitivity and specificity of the dimensional measures is that they aredeterministic, and thus are moreaccurate in quantifying the time-series. This accuracy appears to be significant in detecting pathology in biological systems, and thus the use of deterministic measures may lead to breakthroughs in the diagnosis and treatment of some medical disorders.     

Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Role of orientation in perception of emotions

Our study examined whether perception of novel emotions, as with perception of novel objects, elicits a cardiac orientation reaction. Using a habituation-dishabituation paradigm, data from 11 adult subjects showed that orientation to both novel emotions and novel objects elicited a heart-rate deceleration. Results suggest that the orientation reaction may be an integral part of perception of emotion. Perception of emotions, therefore, is a complex, multistep process that includes an early orientation reaction.     

Does the Type of Cheating Influence Undergraduate Students’ Perceptions of Cheating?

There has been a plethora of studies outlying the various factors which may affect undergraduate student cheating, generally focusing on individual, situational and deterrent factors. But beyond these factors, does the type of cheating affect students’ perceptions of cheating? We found that there were differences in regards to gradable cheating such as cheating on homework, tests and papers versus non-gradable cheating such as illegally downloading software/music from the Internet or photocopying materials which violate the university’s academic integrity policy. Gender, discussion of ethical issues in class and enforcement of cheating reduces the acceptance of cheating across types of cheating. Less time spent on the Internet reduces the acceptance of only non-gradable cheating and the type of institution and knowing the consequences of cheating reduces the acceptance of only gradable cheating.     

Perfectionism and health: A mediational analysis of the roles of stress,social support and health-related behaviours

This study tested a model derived from personality theory in which perceived stress, perceived social support, health-risk and health-promotion behaviours mediate the relationship between perfectionism and perceived physical health. A sample of 538 undergraduate students completed a web-based survey assessing multi-dimensional perfectionism, perceived stress, perceived social support, health behaviours, physical health and a scale tapping elements of the five-factor model of personality. Analyses that account for the effects of traits from the five-factor model (e.g., neuroticism, conscientiousness and extraversion) indicated that socially prescribed perfectionism was associated with poorer physical health and this association was fully mediated by higher levels of perceived stress and lower levels of perceived social support. Self-oriented perfectionism was related complexly to health such that it was related to poorer health via higher levels of perceived stress, but was also related to better health via higher levels of perceived social support. Our findings illustrate the need for considering key mediators of the link between perfectionism and poor health outcomes.     

A Meta‐analytic and Conceptual Update on the Associations Between Procrastination and Multidimensional Perfectionism

The equivocal and debated findings from a 2007 meta‐analysis, which viewed perfectionism as a unidimensional construct, suggested that perfectionism was unrelated to procrastination. The present meta‐analysis aimed to provide a conceptual update and reanalysis of the procrastination–perfectionism association guided by both a multidimensional view of perfectionism and self‐regulation theory. The random‐effects meta‐analyses revealed a small to medium positive average effect size (r  = .23; k  = 43, N  = 10 000; 95% confidence interval (95% CI) [0.19, 0.27]) for trait procrastination and perfectionistic concerns and a small to medium negative average effect size (r  = ?.22; k  = 38, N  = 9544; 95% CI [?0.26, ?0.18]) for procrastination and perfectionistic strivings. The average correlations remained significant after statistically accounting for the joint variance between the two perfectionism dimensions via semi‐partial correlations. For perfectionistic concerns, but not perfectionistic strivings, the effects depended on the perfectionism measure used. All effects did not vary by the trait procrastination measure used or the respondent's sex. Our findings confirm that from a multidimensional perspective, trait procrastination is both positively and negatively associated with higher‐order perfectionism dimensions and further highlights the value of a self‐regulation perspective for understanding the cognitive, affective and behavioural dynamics that characterise these traits. Copyright © 2017 European Association of Personality Psychology     

The developmental course of lexical tone perception in the first year of life

Perceptual reorganisation of infants' speech perception has been found from 6 months for consonants and earlier for vowels. Recently, similar reorganisation has been found for lexical tone between 6 and 9 months of age. Given that there is a close relationship between vowels and tones, this study investigates whether the perceptual reorganisation for tone begins earlier than 6 months. Non-tone language English and French infants were tested with the Thai low vs. rising lexical tone contrast, using the stimulus alternating preference procedure. Four- and 6-month-old infants discriminated the lexical tones, and there was no decline in discrimination performance across these ages. However, 9-month-olds failed to discriminate the lexical tones. This particular pattern of decline in nonnative tone discrimination over age indicates that perceptual reorganisation for tone does not parallel the developmentally prior decline observed in vowel perception. The findings converge with previous developmental cross-language findings on tone perception in English-language infants [Mattock, K., & Burnham, D. (2006). Chinese and English infants' tone perception: Evidence for perceptual reorganization. Infancy, 10(3)], and extend them by showing similar perceptual reorganisation for non-tone language infants learning rhythmically different non-tone languages (English and French).