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Background: Young children appear to spend large portions of their waking time being sedentary. Understanding the correlates of sedentary time would assist in developing effective interventions among young children. The purpose of this systematic review was to summarize the current literature on the correlates of objectively measured sedentary time in young children aged 1-5.99y. Methods: This review was registered with PROSPERO (registration no. CRD42017081374) and aligned with the PRISMA Statement for systematic reviews. Five electronic databases (MEDline, CINAHL Complete, PsycINFO, SportDiscus, Scopus) were searched up to October 26, 2017 for studies investigating correlates of sedentary time measured using objective devices. A semiquantitative approach was used to synthesize data. Results: Forty-five studies were retrieved comprising 13,430 participants, and 84 correlates of sedentary time in young children were evaluated. The associations between sex, sleep habits, daily patterns (childcare vs. non-childcare hours), childcare type and sedentary time were indeterminate. Thirty-nine correlates were consistently unrelated. Forty-one potential correlates were examined in too few studies (<4) to make confident conclusions. Parental sedentary behaviour was reported 3 times and maternal sedentary behaviour was reported once. Out of these four studies, three were positively associated with child sedentary time. Conclusions: Despite reviewing 45 studies that evaluated associations for 84 correlates, this review was unable to identify any consistent correlates of sedentary time in young children. Additional research is needed in this area to provide robust evidence of the correlates of sedentary time in young children, particularly for those examined in only a small number of studies.

Background: Donor-derived, cell-free DNA (dd-cfDNA) level correlates with allograft injury with clinical validity and utility for quiescence and active acute rejection (AR) in kidney transplant recipients. We analyzed trends in dd-cfDNA level immediately preceding and during the coronavirus disease 2019 (COVID-19) pandemic with implemented "shelter in place" and a tele-health strategy with remote home phlebotomy to limit COVID-19 exposure., Methods: During COVID-19 in the United States (US), we surveyed weekly (January 6, 2020-May 25, 2020) metrics for dd-cfDNA corresponding to both a low risk for active rejection (dd-cfDNA < 0.5%) and cohorts with indeterminate levels of 0.5% to 1.0% and > 1.0%. During the study timeframe, over 11,000 patient samples (67%) from 150 kidney transplantation centers were transitioned from standard facility-based to remote phlebotomy., Results: The proportion of dd-cfDNA samples, analyzed in 21 weekly aggregated cohorts by risk-stratification category, was unchanged during the COVID-19 escalation in the US. Linearized slopes for numbers of samples corresponding to indeterminate risk for AR cohorts of > 1.0% and 0.5% to 1.0% were -0.31 and -0.12, respectively; indicating that prevalence of these "at risk for AR cohorts" decreased during remote surveillance. Approximately 73% of samples corresponded to low risk of AR (dd-cfDNA < 0.5%), while an additional 15% of samples had dd-cfDNA level ≤ 1.0%., Conclusion: The combination of remote home phlebotomy including dd-cfDNA analysis and a tele-health program offer a new paradigm that may substantially improve patient compliance and assuage anxiety regarding the state of kidney allograft health during the COVID-19 pandemic. Further prospective multi-center studies with robust outcomes data are warranted.

Background: Several countries have released movement guidelines for children under 5 that incorporate guidelines for sleep, physical activity and sedentary behavior. This study examines prospective associations of preschool children's compliance with the 24-Hour Australian movement guidelines (sleep, physical activity, screen time) and physiological, psychosocial and educational outcomes during primary school., Methods: Data were from the Healthy Active Preschool and Primary Years Study (Melbourne, Australia; n = 471; 3-5 years; 2008/9). Follow-ups occurred at 3 (2011/12; 6-8 years), 6 (2014/15; 9-11 years) and 7 (2016; 10-12 years) years post baseline. Multiple regression models assessed associations between compliance with guidelines at baseline and later outcomes., Results: Children were 4.6 years at baseline (53% boys; 62% high socio-economic families). Most children met physical activity (89%) and sleep (93%) guidelines; 23% met screen-time guidelines; and 20% met all guidelines at baseline. Meeting all of the three guidelines was associated with lower BMI z-scores at 9-11 years of age (b = - 0.26, 95%CI -0.47, - 0.05). Meeting physical activity guidelines was associated with higher total body bone mineral density (b = 0.64, 95%CI 0.15, 1.13), and total body bone mineral content (b = 183.19, 95%CI 69.92, 296.46) at 10-12 years of age. Meeting sleep guidelines was associated with better reading (b = 37.60, 95%CI 6.74, 68.46), spelling (b = 34.95, 95%CI 6.65, 63.25), numeracy (b = 39.09, 95%CI 11.75, 66.44), language (b = 44.31, 95%CI 11.77, 76.85) and writing (b = 25.93, 95%CI 0.30, 51.57) at 8-9 years of age. No associations were evident for compliance with screen-time guidelines or for psychosocial outcomes., Conclusions: Compliance with different movement behavior guidelines was associated with different outcomes. Strategies to support children in meeting all of the guidelines are warranted to maximize health and educational outcomes. Future research investigating dose-response associations, and potential mechanisms, is necessary.

Background: The impact of declining physical activity and increased sedentary behaviour in children and adolescents globally prompted the development of national and international physical activity guidelines. This research aims to systematically identify and compare national and international physical activity guidelines for children and adolescents and appraise the quality of the guidelines to promote best practice in guideline development., Methods: This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) and reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Only national, or international physical activity and/or sedentary behaviour guidelines were included in the review. Included guidelines targeted children and adolescents aged between 5 and 18 years. A grey literature search was undertaken incorporating electronic databases, custom Google search engines, targeted websites and international expert consultation. Guideline quality was assessed using the Appraisal of Guidelines for Research and Evaluation II Instrument (AGREE II)., Results: The search resulted in 50 national or international guidelines being identified. Twenty-five countries had a national guideline and there were three international guidelines (European Union, Nordic countries (used by Iceland, Norway and Sweden), World Health Organization (WHO)). Nineteen countries and the European Union adopted the WHO guidelines. Guidelines varied in relation to date of release (2008 to 2019), targeted age group, and guideline wording regarding: type, amount, duration, intensity, frequency and total amount of physical activity. Twenty-two countries included sedentary behaviour within the guidelines and three included sleep. Total scores for all domains of the AGREE II assessment for each guideline indicated considerable variability in guideline quality ranging from 25.8 to 95.3%, with similar variability in the six individual domains. Rigorous guideline development is essential to ensure appropriate guidance for population level initiatives., Conclusions: This review revealed considerable variability between national/international physical activity guideline quality, development and recommendations, highlighting the need for rigorous and transparent guideline development methodologies to ensure appropriate guidance for population-based approaches. Where countries do not have the resources to ensure this level of quality, the adoption or adolopment (framework to review and update guidelines) of the WHO guidelines or guidelines of similar quality is recommended., Trial Registration: Review registration: PROSPERO 2017 CRD42017072558.

The 2017 Australian and Canadian 24-hour movement guidelines recommend infants receive 30 minutes of tummy time daily. Currently, there are no validated objective measurement tools or devices to assess tummy time. The purpose of this study was to: 1) test the practicality of using devices on infants as an objective measure of tummy time, and 2) test the accuracy of developed algorithms and cut-points for predicting prone posture. Thirty-two healthy infants aged 4 to 25 weeks completed a protocol of 12 positions. Infants were placed in each position for 3 minutes while wearing a MonBaby (chest), GENEActiv (right hip) and two ActiGraphs (right hip and ankle). Direct observation was the criterion measure. The accuracy of the algorithms or cut-points to predict prone on floor, non-prone and prone supported positions were analyzed. Parents also completed a practicality questionnaire. Algorithms and cut-points to classify posture using devices from MonBaby, GENEActiv and ActiGraph (hip and ankle) were 79%, 95%, 90% and 88% accurate at defining tummy time and 100%, 98%, 100% and 96% accurate at defining non-prone positions, respectively. GENEActiv had the smallest mean difference and limits of agreement (-8.4s, limits of agreement [LoA]: -78.2 to 61.3s) for the prone on floor positions and ActiGraph Hip had the smallest mean difference and LoA for the non-prone positions (-0.2s, LoA: -1.2 to 0.9s). The majority of parents agreed all devices were practical and feasible to use with MonBaby being the preferred device. The evaluated algorithms and cut-points for GENEActiv and ActiGraph (hip) are of acceptable accuracy to objectively measure tummy time (time spent prone on floor). Accurate measurement of infant positioning practices will be important in the observation of 24-hour movement guidelines in the early years., Competing Interests: The authors have declared that no competing interests exist.

Objectives: Adolescents spend large proportions of the school day sitting; potentially increasing their health risks. This study aimed to evaluate the feasibility, acceptability and potential efficacy of a school-based intervention to reduce adolescent sitting time during the school day., Design: Two-arm parallel-group randomised controlled trial., Methods: Adolescents (13-16 years) were recruited from four private high schools in New South Wales, Australia. Schools were pair-matched and randomised to treatment or control. Research assistants were blinded to intervention aims and treatment allocation. Intervention initiatives included classroom and outdoor environmental measures to break up and reduce the proportion of adolescent school time spent sitting. Teacher and students surveys assessed intervention feasibility, acceptability and potential efficacy. Proportional sitting time was the primary outcome, measured by activPAL monitors, worn for one week during the school day. Secondary outcomes included body mass index, body fatness, working memory and non-verbal reasoning. Data were analysed using a general linear model for continuous variables and adjusted for clustering., Results: While teachers and students supported the program, process evaluation results indicate aspects of the intervention were not implemented with fidelity. Eighty-eight adolescents (M age =14.7±0.7, 50% male) participated in the trial. Eighty-six had valid data for all variables (43 controls, 43 intervention). There was no significant intervention effect on the primary outcome. There was a significant effect on working memory (adjusted difference ±SD=-0.42±1.37; p=0.048 (Cohen's d)=0.31)., Conclusions: These findings contribute to limited research in this area, providing guidance for future interventions in the high school environment., Trial Registration: The study was registered with the Australian and New Zealand Clinical Trials Registry (ACTRN 12614001001684)., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

China has high and increasing annual rates of occupational lung diseases such as pneumoconiosis and silicosis. In contrast, Australia and the United States of America (USA) have greatly lowered their annual rates of lung diseases since the 1970s. This paper systematically compared and analysed the multi-elements of coal dust management and health management in these three countries to provide a reference for China. Regarding coal dust management, this paper found that coal workers in China are more susceptible to lung diseases compared to workers in the USA and Australia, considering fundamental aspects such as mine type, coal rank, and geological conditions. In addition, the controllable aspects such as advanced mitigation, monitoring methods, and the personal protective equipment of coal dust were relatively inadequate in China compared to the USA and Australia. Health management in China was found to have multiple deficiencies in health examination, co-governance, and compensations for coal workers suffering from lung diseases and healthcare for retired coal workers. These deficiencies may be attributed to insufficient medical resources, the Chinese government-dominated governance, ineffective procedures for obtaining compensation, and the lack of effective and preventive healthcare programs for the retired coal workers. Based on the USA and Australia experience, some suggestions for improvement were proposed.

Background: The objective of this paper is to derive a wrist-placed cut-point threshold for distinguishing sedentary behaviors from light-intensity walking using the ActiGraph GT3X+ in children., Methods: This study employed a cross-sectional study design, typically used in measurement-related studies. A sample of 167 children, ages 5⁻11 years (mean ± SD: 8.0 ± 1.8 years), performed up to eight seated sedentary activities while wearing accelerometers on both wrists. Activities included: reading books, sorting cards, cutting and pasting, playing board games, eating snacks, playing with tablets, watching TV, and writing. Direct observation verified sedentary behavior from light activity. Receiver operator characteristic (ROC) analyses were used to determine optimal cut-point thresholds. Quantile regression models estimated differences between dominant and non-dominant placement., Results: The optimal cut-point threshold for the non-dominant wrist was 203 counts/5 s with sensitivity, specificity, and area under the curve (AUC) of 71.56, 70.83, and 0.72, respectively. A 10-fold cross-validation revealed an average AUC of 0.70. Statistically significant ( p ≤ 0.05) differences in median counts ranging from 7 to 46 counts/5 s were found between dominant and non-dominant placement in five out of eight sedentary activities, with the dominant wrist eliciting higher counts/5 s., Conclusion: Results from this study support the recommendation to place accelerometers on the non-dominant wrist to minimize "noise" during seated sedentary behaviors.

Throughout the process of coal extraction from surface mines, gases and particles are emitted in the form of fugitive emissions by activities such as hauling, blasting and transportation. As these emissions are diffuse in nature, estimations based upon emission factors and dispersion/advection equations need to be measured directly from the atmosphere. This paper expands upon previous research undertaken to develop a relative methodology to monitor PM 10 dust particles produced by mining activities making use of small unmanned aerial vehicles (UAVs). A module sensor using a laser particle counter (OPC-N2 from Alphasense, Great Notley, Essex, UK) was tested. An aerodynamic flow experiment was undertaken to determine the position and length of a sampling probe of the sensing module. Flight tests were conducted in order to demonstrate that the sensor provided data which could be used to calculate the emission rate of a source. Emission rates are a critical variable for further predictive dispersion estimates. First, data collected by the airborne module was verified using a 5.0 m tower in which a TSI DRX 8533 (reference dust monitoring device, TSI, Shoreview, MN, USA) and a duplicate of the module sensor were installed. Second, concentration values collected by the monitoring module attached to the UAV (airborne module) obtaining a percentage error of 1.1%. Finally, emission rates from the source were calculated, with airborne data, obtaining errors as low as 1.2%. These errors are low and indicate that the readings collected with the airborne module are comparable to the TSI DRX and could be used to obtain specific emission factors from fugitive emissions for industrial activities.

Objectives: To assess the effect of a school playground intervention on the physical activity levels of primary/elementary aged children., Design: Two-arm parallel group randomized controlled trial., Methods: In 2011, children aged 4-13 years from thirteen primary/elementary schools (in Illawarra, New South Wales, Australia) were invited to participate in the study. School recruitment was based on existing policies, equipment and willingness to participate. Participating schools were randomly allocated to the intervention or control using the 'hat and draw' method. The intervention was delivered over four months. Intervention schools introduced policy changes and portable equipment to break-time after baseline measures were collected. The primary outcome was the proportion of break-time spent in Moderate to Vigorous Physical Activity (MVPA) assessed by the System for Observing Playground Activity in Youth (SOPLAY). The analysis involved linear mixed models adjusting for the clustering effect of schools. The study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614001128684)., Results: Four schools (two intervention and two control) met the inclusion criteria (1582 children: 790 males; 267 controls, total of 792 females; 248 controls). Students from the intervention schools had a greater increase at follow-up in the proportion of break-time in MVPA; (adjusted difference=12.5 percentage points, 95% CI [-13.0%, 38.0%]; P=0.17; r=0.6) compared to the controls. MVPA at recess significantly increased (adjusted difference=18.0 percentage points, 95% CI [6.9%, 29.1%]; P=0.02; effect size=0.7). There were no significant increases in MVPA when examining overall break times. Results were greater for girls compared to boys., Conclusions: Making environmental and policy changes are promising strategies for promoting health-enhancing physical activity during school break-time., (Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Sedentary behaviour has emerged as a unique determinant of health in adults. Studies in children and adolescents have been less consistent. We reviewed the evidence to determine if the total volume and patterns (i.e. breaks and bouts) of objectively measured sedentary behaviour were associated with adverse health outcomes in young people, independent of moderate-intensity to vigorous-intensity physical activity. Four electronic databases (EMBASE MEDLINE, Ovid EMBASE, PubMed and Scopus) were searched (up to 12 November 2015) to retrieve studies among 2- to 18-year-olds, which used cross-sectional, longitudinal or experimental designs, and examined associations with health outcomes (adiposity, cardio-metabolic, fitness, respiratory, bone/musculoskeletal, psychosocial, cognition/academic achievement, gross motor development and other outcomes). Based on 88 eligible observational studies, level of evidence grading and quantitative meta-analyses indicated that there is limited available evidence that the total volume or patterns of sedentary behaviour are associated with health in children and adolescents when accounting for moderate-intensity to vigorous-intensity physical activity or focusing on studies with low risk of bias. Quality evidence from studies with robust designs and methods, objective measures of sitting, examining associations for various health outcomes, is needed to better understand if the overall volume or patterns of sedentary behaviour are independent determinants of health in children and adolescents., (© 2016 World Obesity.)

Abstract This study examined the validity of current Actical activity energy expenditure (AEE) equations and intensity cut-points in preschoolers using AEE and direct observation as criterion measures. Forty 4-6-year-olds (5.3 ± 1.0 years) completed a ~150-min room calorimeter protocol involving age-appropriate sedentary behaviours (SBs), light intensity physical activities (LPAs) and moderate-to-vigorous intensity physical activities (MVPAs). AEE and/or physical activity intensity were calculated using Actical equations and cut-points by Adolph, Evenson, Pfeiffer and Puyau. Predictive validity was examined using paired sample t-tests. Classification accuracy was evaluated using weighted kappas, sensitivity, specificity and area under the receiver operating characteristic curve. The Pfeiffer equation significantly overestimated AEE during SB and underestimated AEE during LPA (P < 0.0125 for both). There was no significant difference between measured and predicted AEEs during MVPA. The Adolph cut-point showed significantly higher accuracy for classifying SB, LPA and MVPA than all others. The available Actical equation does not provide accurate estimates of AEE across all intensities in preschoolers. However, the Pfeiffer equation performed reasonably well for MVPA. Using cut-points of ≤6 counts · 15 s(-1), 7-286 counts · 15 s(-1) and ≥ 287 counts · 15 s(-1) when classifying SB, LPA and MVPA, respectively, is recommended.

Background: Like many other countries, Australia is facing an inactivity epidemic. The purpose of the Australian 2014 Physical Activity Report Card initiative was to assess the behaviors, settings, and sources of influences and strategies and investments associated with the physical activity levels of Australian children and youth., Methods: A Research Working Group (RWG) drawn from experts around Australia collaborated to determine key indicators, assess available datasets, and the metrics which should be used to inform grades for each indicator and factors to consider when weighting the data. The RWG then met to evaluate the synthesized data to assign a grade to each indicator., Results: Overall Physical Activity Levels were assigned a grade of D-. Other physical activity behaviors were also graded as less than average (D to D-), while Organized Sport and Physical Activity Participation was assigned a grade of B-. The nation performed better for settings and sources of influence and Government Strategies and Investments (A- to a C). Four incompletes were assigned due to a lack of representative quality data., Conclusions: Evidence suggests that physical activity levels of Australian children remain very low, despite moderately supportive social, environmental and regulatory environments. There are clear gaps in the research which need to be filled and consistent data collection methods need to be put into place.

The use of whole-room calorimetry (WRC) in young children can increase our understanding of children's energy balance. However, studies using WRC in young children are rare due to concerns about its feasibility. To assess the feasibility of WRC in young children, forty children, aged 4–6 years, were asked to follow a graded activity protocol while in a WRC. In addition, six children participated in two additional resting protocols to examine the effect of diet-induced thermogenesis on resting energy expenditure (REE) measures and the reliability of REE measurement. Refusals to participate and data loss were quantified as measures of practical utility, and REE measured after an overnight fast and after a 90-min fast were compared. In addition, both were compared to predicted BMR values using the Schofield equation. Our results showed that thirty (78·9 %) participants had acceptable data for all intensities of the activity protocol. The REE values measured after a 90-min fast (5·07 (SD 1·04) MJ/d) and an overnight fast (4·73 (SD 0·61) MJ/d) were not significantly different from each other (P= 0·472). However, both REE after an overnight fast and a 90-min fast were significantly higher than predicted BMR (3·96 (SD 0·18) MJ/d) using the Schofield equation (P= 0·024 and 0·042, respectively). We conclude that, with a developmentally sensitive approach, WRC is feasible and can be standardised adequately even in 4- to 6-year-old children. In addition, the effect of a small standardised breakfast, approximately 90 min before REE measurements, is likely to be small.

Objective: To provide a user's guide for selecting an appropriate method to assess sedentary behaviours among children and adolescents., Design: While recommendations regarding specific instruments are not provided, the guide offers information about key attributes and considerations for objective (accelerometry; inclinometers; direct observation; screen monitoring devices) and subjective (self-report; parent report; and time use diaries/logs) approaches to assess sedentary behaviour Attributes of instruments and other factors to be considered in the selection of assessment instruments include: population (age); sample size; respondent burden; method/delivery mode; assessment time frame; physical activity information required (data output); data management; measurement error; cost (instrument and administration) and other limitations., Methods: Expert consensus among members of the Australasian Child and Adolescent Obesity Research Network's (ACAORN) Physical Activity and Sedentary Behaviour Special Interest Group., Results: We developed decision flow charts to assist researchers and practitioners select an appropriate method of assessing sedentary behaviour, identified attributes of each method and described five real-life scenarios to illustrate considerations associated with the selection of each method of measurement., Conclusions: It is important that researchers, practitioners and policy makers understand the strengths and limitations of different methods of assessing sedentary behaviour among youth, and are guided on selection of the most appropriate instrument/s to suit their needs., (Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.)

Introduction: Invasive pneumococcal disease due to serotype 19A has become a major concern, particularly in the USA and Asia. We describe the characteristics of pneumococcal serotype 19A related empyema and changes in its incidence in the UK., Methods: Data from paediatric empyema patients between September 2006 and March 2011 were collected from 17 respiratory centres in the UK. Pneumococcal serotypes were identified as part of the Health Protection Agency enhanced paediatric empyema surveillance programme., Results: Four serotypes accounted for over 80% of 136 cases (Serotype 1 : 43%, 3 : 21%, 7 : 11% and 19A:10%). The incidence of empyema due to serotype 19A quadrupled from 0.48 (0.16-1.13) cases per million children in 2006/2007 to 2.02 (1.25-3.09) in 2010/2011. Severity of disease was significantly increased in children with 19A infection when compared to other serotypes., Conclusions: The incidence of empyema due to pneumococcal serotype 19A infection has increased significantly and is associated with substantial morbidity.

Efforts to treat obesity in childhood and adolescence would benefit from a greater understanding of evidence-based strategies to modify physical activity behaviour. A systematic review was conducted to examine the impact of child and adolescent obesity treatment interventions on physical activity. Studies included were randomized controlled trials or controlled trials, with overweight and obese youth (aged < 18 years), which reported statistical analysis of free-living physical activity at pretreatment and post-treatment. Two independent reviewers assessed each study for methodological quality. Seventeen child and three adolescent studies were retrieved, half of which were conducted in the USA. Studies were characterized by small samples of limited cultural and economic diversity. Fifteen studies reported an increase in at least one physical activity outcome at post-test or follow-up. Overall, study quality was rated as low (child median score = 3/10, range = 0-9; adolescent median score = 3/10, range = 2-5) with three child studies classified as high quality (>or=6/10). Research evaluating the effect of child and adolescent obesity treatment trials on physical activity is limited in both quantity and quality. Studies testing innovative, theoretically driven treatment approaches that use robust methodologies are required to better understand generalizable approaches for promoting physical activity participation among obese youth.

Background: Tenofovir disoproxil fumarate (TDF) is neither licensed for use nor extensively studied in HIV-infected children. The only available formulation is an adult tablet, introducing the possibility of dosing errors in children. TDF interacts with other antiretrovirals and has been associated with decline in renal function and CD4 count. We describe the use of TDF in a cohort of HIV-1-infected children in the United Kingdom and Ireland., Methods: Children ever prescribed TDF and followed in the Collaborative HIV Pediatric Study cohort since 2001 were included in analyses of dosing, adverse events, and virologic and immunologic response. Suspected adverse drug reactions to TDF reported to the Medicines and Healthcare products Regulatory Agency during the same time were also reviewed., Results: One hundred fifty-nine of 1253 children had taken TDF. They were older and had clinically more advanced disease than the rest of the cohort. Eighteen percent received >120% and 37% received <80% of the suggested pediatric dose (8 mg/kg). Thirty-seven percent of new TDF regimens contained didanosine (ddI), though few since 2005. Twelve of 159 (7.5%) children experienced serious adverse events and stopped TDF permanently, 11 taking concurrent lopinavir-ritonavir, and 10 ddI; 5 had renal toxicity. Viral load suppressed to < or =50 copies/mL at 12 months in 38% of those starting TDF. Median increase in CD4 count at 12 months was +110 cells/mL (interquartile range, 9-270), but only 3 cells/mL in those taking concurrent ddI., Conclusions: TDF seems to be an effective antiretroviral drug in this pediatric cohort, although considerable underdosing and overdosing occurs. A small number of children experienced serious adverse events while taking TDF; half were renal toxicity, most associated with concurrent ddI and lopinavir-ritonavir use.

In a previous article, we introduced a number of visualization techniques that we had developed for monitoring the dynamics of artificial competitive coevolutionary systems. One of these techniques involves evaluating the performance of an individual from the current population in a series of trials against opponents from all previous generations, and visualizing the results as a 2D grid of shaded cells or pixels: qualitative patterns in the shading can indicate different classes of coevolutionary dynamics. As this technique involves pitting a current individual against ancestral opponents, we referred to the visualizations as CIAO plots. Since then, a number of other authors studying the dynamics of competitive coevolutionary systems have used CIAO plots or close derivatives to help illuminate the dynamics of their systems, and it has become something of a de facto standard visualization technique. In this very brief article we summarize the rationale for CIAO plots, explain the method of constructing a CIAO plot, and review important recent results that identify significant limitations of this technique.

As community nurses become more actively involved in practice-centred enquiry, they are increasingly exploring ways of understanding the lived experience of clients. Narrative approaches are becoming particularly prominent as these methods of enquiry closely connect with the regular interactions between client and nurse. In this article the nature of narrative and its use is outlined and illustrated with an example of narrative exploration. Additionally the article identifies some of the arguments for developing narrative approaches in primary health care and concludes with some discussion on challenges in using this approach.

An artificial life entertainment software product called Creatures was released in Europe in late 1996 and in the United States and Japan in mid-1997. When installed on a domestic computer (PC or Macintosh), each Creatures CD-ROM creates a virtual world in which autonomous software agents exist. The agents, known as "norn," interact with the human user, with each other, and with objects in their virtual world. Each norn coordinates perception and action via its own modular recurrent neural network. Each network has Hebbian learning, plus diffuse modulation of activity via a "hormonal" system that is part of that norns "biochemistry." Details of each norns neural network and biochemistry are genetically specified, and norns can breed via sexual reproduction. In the reproduction process, genetic material may be mutated and may also be subjected to "gene duplications" that enable potentially unlimited increases in complexity of the norns' design. Over 500,000 Creatures CD-ROMS have now been sold. As each installed copy of Creatures can support 5 to 10 simultaneously existing individual norns, it seems reasonable to estimate that there are up to 5 million norns existing in the "cyberspace" provided by the global Creatures user community. Continued growth of the global norn population, to figures measured in tens of millions, is quite likely. Although a commercial product, the Creatures digital ecosystem should be of interest to artificial life scientists. There are obvious parallels with Yaeger's PolyWorld and Ray's NetTierra systems. This article provides a detailed discussion of the links between the artificial life literature and the technology used in Creatures and includes anecdotal discussion of the "digital naturalism" witnessed on the many independent websites maintained by Creatures enthusiasts.

Objective: To investigate patterns of attendance and non-attendance at National Health Service antenatal classes of first-time mothers in the indigenous white population of a large northern city of the UK., Design: Survey using questionnaires, and selected participants were then given an in-depth interview., Setting: Five maternity wards in two large northern hospitals in the UK. In-depth interviews took place in the respondents' homes., Participants: Fifty newly delivered women were surveyed of whom 18 took part in the follow-up interviews., Findings: There was a clear hierarchy in attendance and non-attendance based on social class, with middle class women being the most regular attenders, closely followed by older, married, working class women. However, overall social class differences were found to be accounted for by the overwhelming non attendance of young, unmarried, working class women. Older, married, working class women were found to have attendance patterns which were close to their middle class counterparts, and what differences there were seemed to be based on material factors., Key Conclusions: The majority of women felt that antenatal classes were too technical and did not address emotional and psychological issues. However, young, single unmarried women perceived the classes most negatively. If midwives are to attract such young women, their fears and their need for peer support will have to be recognised.

The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong.

Radiofrequency ablation as a treatment for supraventricular and ventricular tachycardias has increased in popularity as a safe and effective mode of therapy. The critical care nurse's role includes pre-procedure, peri-procedure, and post-procedure observations and interventions that contribute to positive patient outcomes.