Simulation of Brugada syndrome using cellular and three-dimensional whole-heart modeling approaches

Brugada syndrome (BS) is a genetic disease identified by an abnormal electrocardiogram ( ECG) ( mainly abnormal ECGs associated with right bundle branch block and ST-elevation in right precordial leads). BS can lead to increased risk of sudden cardiac death. Experimental studies on human ventricular myocardium with BS have been limited due to difficulties in obtaining data. Thus, the use of computer simulation is an important alternative. Most previous BS simulations were based on animal heart cell models. However, due to species differences, the use of human heart cell models, especially a model with three-dimensional whole-heart anatomical structure, is needed. In this study, we developed a model of the human ventricular action potential (AP) based on refining the ten Tusscher et al (2004 Am. J. Physiol. Heart Circ. Physiol. 286 H1573 - 89) model to incorporate newly available experimental data of some major ionic currents of human ventricular myocytes. These modified channels include the L-type calcium current (ICaL), fast sodium current (I-Na), transient outward potassium current (I-to), rapidly and slowly delayed rectifier potassium currents (I-Kr and I-Ks) and inward rectifier potassium current (I-Ki). Transmural heterogeneity of APs for epicardial, endocardial and mid-myocardial (M) cells was simulated by varying the maximum conductance of IKs and Ito. The modified AP models were then used to simulate the effects of BS on cellular AP and body surface potentials using a three-dimensional dynamic heart - torso model. Our main findings are as follows. (1) BS has little effect on the AP of endocardial or mid-myocardial cells, but has a large impact on the AP of epicardial cells. (2) A likely region of BS with abnormal cell AP is near the right ventricular outflow track, and the resulting ST-segment elevation is located in the median precordium area. These simulation results are consistent with experimental findings reported in the literature. The model can reproduce a variety of electrophysiological behaviors and provides a good basis for understanding the genesis of abnormal ECG under the condition of BS disease.

Sustainability metrics for coal power generation in Australia

The basis of this work was to investigate the relative environmental impacts of various power generators knowing that all plants are located in totally different environments and that different receptors will experience different impacts. Based on IChemE sustainability metrics paradigm, we calculated potential environmental indicators (P-EI) that represent the environmental burden of masses of potential pollutants discharged into different receiving media. However, a P-EI may not be of significance, as it may not be expressed at all in different conditions, so to try and include some receiver significance we developed a methodology to take into account some specific environmental indicators (S-EI) that refer to the environmental attributes of a specific site. In this context, we acquired site specific environmental data related to the airsheds and water catchment areas in different locations for a limited number of environmental indicators such as human health (carcinogenic) effects, atmospheric acidification, photochemical (ozone) smog and eutrophication. The S-EI results from this particular analysis show that atmospheric acidification has highest impact value while health risks due to fly ash emissions are considered not to be as significant. This is due to the fact that many coal power plants in Australia are located in low population density air sheds. The contribution of coal power plants to photochemical (ozone) smog and eutrophication were not significant. In this study, we have considered emission related data trends to reflect technology performance (e.g., P-EI indicators) while a real sustainability metric can be associated only with the specific environmental conditions of the relevant sites (e.g., S-EI indicators).

The use of hypertonic saline for treating intracranial hypertension after traumatic brain injury

The past decade has witnessed a resurgence of interest in the use of hypertonic saline for low-volume resuscitation after trauma. Preliminary studies suggested that benefits are limited to a subgroup of trauma patients with brain injury, but a recent study of prehospital administration of hypertonic saline to patients with traumatic brain injury failed to confirm a benefit. Animal and human studies have demonstrated that hypertonic saline has clinically desirable physiological effects on cerebral blood flow, intracranial pressure, and inflammatory responses in models of neurotrauma. There are few clinical studies in traumatic brain injury with patient survival as an end point. In this review, we examined the experimental and clinical knowledge of hypertonic saline as an osmotherapeutic agent in neurotrauma.

'Look at that kid crawling': Race, myth and the 'crawl' stroke

Australia and, more specifically, a Solomon Island schoolboy named A lick Wickham, are credited with creating the swimming racing stroke, the crawl, or freestyle as it is known in contemporary parlance. Wickham's contribution constitutes a popular celebrated and enduring legend. While there is some factual basis to the legend, Wickham s contribution is a sport creation myth. The myth offers an example of the intersection of sport and constructions of Pacific islanders in the racial discourse of the Federation period. As a cultural discourse, the myth reflects how Wickham was accommodated as an exoticised islander and socially acceptable 'black' sportsman.

Being fit and looking healthy: Young women's and men's constructions of health and fitness

We drew on Foucault's notion of 'practices of the self' to examine how young people take up, negotiate, and resist the imperatives of a public health discourse concerned with the relationships between health, fitness, and the body. We did this through a discussion of the ways young women and men talk about their own and others' bodies, in the context of a number of in-depth interviews conducted for the Life Activity Project, a study of the place and meaning of physical activity in young people's lives, funded by an Australian Research Council Grant. We found that the young women and men in the study engaged the health/fitness discourse very differently: for the young men, health conflated with fitness as an embodied capacity to do physical work; and for the young women, health was a much more difficult and complex project associated with managing and monitoring practices associated with eating and exercise to maintain an 'appropriate' body shape.

High-field magnetic resonance imaging with reduced field/tissue RF artefacts - A modeling study using hybrid MoM/FEM and FDTD technique

Due to complex field/tissue interactions, high-field magnetic resonance (MR) images suffer significant image distortions that result in compromised diagnostic quality. A new method that attempts to remove these distortions is proposed in this paper and is based on the use of transceiver-phased arrays. The proposed system uses, in the examples presented herein, a shielded four-element transceive-phased array head coil and involves performing two separate scans of the same slice with each scan using different excitations during transmission. By optimizing the amplitudes and phases for each scan, antipodal signal profiles can be obtained, and by combining both the images together, the image distortion can be reduced several fold. A combined hybrid method of moments (MoM)/finite element method (FEM) and finite-difference time-domain (FDTD) technique is proposed and used to elucidate the concept of the new method and to accurately evaluate the electromagnetic field (EMF) in a human head model. In addition, the proposed method is used in conjunction with the generalized auto-calibrating partially parallel acquisitions (GRAPPA) reconstruction technique to enable rapid imaging of the two scans. Simulation results reported herein for 11-T (470-MHz) brain imaging applications show that the new method with GRAPPA reconstruction theoretically results in improved image quality and that the proposed combined hybrid MoM/FEM and FDTD technique is. suitable for high-field magnetic resonance imaging (MRI) numerical analysis.

Risk reduction: Recontexualizing health as a physical education curriculum

While there is sufficient evidence to suggest that physical activity is inversely related to lifestyle diseases, researchers are far from being certain that this evidence extends to children. Nevertheless, the school physical education curriculum has been targeted as an institutional agency that could have a significant impact on health during childhood and later during adulthood if individuals could be habituated to assume a physically active lifestyle. The purpose of this article is to examine the recontextualization of biomedical knowledge into an ideology of healthism in which health is conceived as a controllable certainty and used as a pedagogical construction to transform school physical education. Using a Foucauldian perspective, we explore how the atomized biomedical model of chemical and physical relationships is constructed, reproduced, and perpetuated to service and empower the discourse and the practices of researchers and scholars. In this process the sociological or cultural aspects of public health are marginalized or ignored. As a result of this examination, alternative approaches are proposed that engage the limitations of the biomedical model and openly consider the insights that are available from the social sciences regarding what participation in physical activity means to individuals.

When "where'' is more important than "when": Birthplace and birthdate effects on the achievement of sporting expertise

In this study, we assessed whether contextual factors related to where or when an athlete is born influence their likelihood of playing professional sport. The birthplace and birth month of all American players in the National Hockey League, National Basketball Association, Major League Baseball, and Professional Golfer's Association, and all Canadian players in the National Hockey League were collected from official websites. Monte Carlo simulations were used to verify if the birthplace of these professional athletes deviated in any systematic way from the official census population distribution, and chi-square analyses were conducted to determine whether the players' birth months were evenly distributed throughout the year. Results showed a birthplace bias towards smaller cities, with professional athletes being over-represented in cities of less than 500,000 and under-represented in cities of 500,000 and over. A birth month/relative age effect (in the form of a distinct bias towards elite athletes being relatively older than their peers) was found for hockey and baseball but not for basketball and golf. Comparative analyses suggested that contextual factors associated with place of birth contribute more influentially to the achievement of an elite level of sport performance than does relative age and that these factors are essentially independent in their influences on expertise development.

Why is economics not a complex systems science?

The article argues that economics will have to become a complex systems science before economists can comfortably incorporate institutionalist and evolutionary economics into mainstream theory. The article compares the complex adaptive system of John Foster with that of standard economic theory and illustrates the difference through an examination of familiar production function. The place of neoclassical, Keynesian economics in complex systems is considered. The article concludes that convincing, multiple models have been made possible by the increase in widely available computing power available.

Extending a model of shift-work tolerance

The present study contributes to theory and practice through the development of a model of shift-work tolerance with the potential to indicate interventions that reduce nurses' intention toward turnover and increase job satisfaction in hospital-based settings. Survey data from 1257 nurses were used to conduct structural equation modeling that examine the direct and indirect effects of supervisor and colleague support, team identity, team climate, and control over working environment on time-based work/life conflict, psychological well-being, physical symptoms, job satisfaction, and turnover intention. The analysis of the proposed model revealed a good fit The chi-square difference test was non-significant (χ2(26)=338.56), the fit indices were high (CFI=.923, NFI=.918, and NNFI=.868), the distribution of residuals was symmetric and approached zero, the average standardized residual was low (AASR=.04), and the standardized RMR was .072. In terms of the predictor variable, the final model explained 48% of the variance in turnover intention. The data revealed considerable evidence of both direct effects on adjustment and complex indirect links between levels of adjustment and work-related social support, team identity, team climate, and control. Nurses with high supervisor and coworker support experienced more positive team climates, identified more strongly with their team, and increased their perceptions of control over their work environment. This in turn lowered their appraisals of their time-based work/life conflict, which consequently increased their psychological well-being and job satisfaction and reduced their physical health symptoms and turnover intention. The type of shift schedule worked by the nurses influenced levels of turnover intention, control over work environment, time-based work/life conflict, and physical symptoms.

'Putting up your Dukes': Statues, social memory and Duke Paoa Kahanamoku

Public statues that commemorate the lives and achievements of athletes are pervasive and influential forms of social memory in Western societies. Despite this important nexus between cultural practice and history making, there is a relative void of critical studies of statuary dedicated to athletes. This article will attempt to contribute to a broader understanding in this area by considering a bronze statue of Duke Paoa Kahanamoku, the Hawaiian Olympian, swimmer and surfer, at Waikīkī, Hawaii. This prominent monument demonstrates the processes of remembering and forgetting that are integral to acts of social memory. In this case, Kahanamoku's identity as a surfer is foregrounded over his legacy as a swimmer. The distillation and use of Kahanamoku's memory in this representation is enmeshed in deeper cultural forces about Hawaii's identity. Competing meanings of the statue's symbolism indicate its role as a 'hollow icon', and illustrate the way that apparently static objects representing the sporting past are in fact objects of the present.