Accuracy of rate estimation using relaxed-clock models with a critical focus on the early metazoan radiation

In recent years, a number of phylogenetic methods have been developed for estimating molecular rates and divergence dates under models that relax the molecular clock constraint by allowing rate change throughout the tree. These methods are being used with increasing frequency, but there have been few studies into their accuracy. We tested the accuracy of several relaxed-clock methods (penalized likelihood and Bayesian inference using various models of rate change) using nucleotide sequences simulated on a nine-taxon tree. When the sequences evolved with a constant rate, the methods were able to infer rates accurately, but estimates were more precise when a molecular clock was assumed. When the sequences evolved under a model of autocorrelated rate change, rates were accurately estimated using penalized likelihood and by Bayesian inference using lognormal and exponential models of rate change, while other models did not perform as well. When the sequences evolved under a model of uncorrelated rate change, only Bayesian inference using an exponential rate model performed well. Collectively, the results provide a strong recommendation for using the exponential model of rate change if a conservative approach to divergence time estimation is required. A case study is presented in which we use a simulation-based approach to examine the hypothesis of elevated rates in the Cambrian period, and it is found that these high rate estimates might be an artifact of the rate estimation method. If this bias is present, then the ages of metazoan divergences would be systematically underestimated. The results of this study have implications for studies of molecular rates and divergence dates.

Turbulence measurements in a small subtropical estuary under king tide conditions

In natural waterways and estuaries, the understanding of turbulent mixing is critical to the knowledge of sediment transport, stormwater runoff during flood events, and release of nutrient-rich wastewater into ecosystems. In the present study, some field measurements were conducted in a small subtropical estuary with micro-tidal range and semi-diurnal tides during king tide conditions: i. e., the tidal range was the largest for both 2009 and 2010. The turbulent velocity measurements were performed continuously at high-frequency (50Hz) for 60 h. Two acoustic Doppler velocimeters (ADVs) were sampled simultaneously in the middle estuarine zone, and a third ADV was deployed in the upper estuary for 12 h only. The results provided an unique characterisation of the turbulence in both middle and upper estuarine zones under the king tide conditions. The present observations showed some marked differences between king tide and neap tide conditions. During the king tide conditions, the tidal forcing was the dominant water exchange and circulation mechanism in the estuary. In contrast, the long-term oscillations linked with internal and external resonance played a major role in the turbulent mixing during neap tides. The data set showed further that the upper estuarine zone was drastically less affected by the spring tide range: the flow motion remained slow, but the turbulent velocity data were affected by the propagation of a transient front during the very early flood tide motion at the sampling site. © 2012 Springer Science+Business Media B.V.

Job satisfaction and intention to leave among critical care nurses in Saudi Arabia

Aim The purpose of this study was to examine the relationship between registered nurses’ (RN) job satisfaction and their intention to leave critical care nursing in Saudi Arabia. Background Many studies have identified critical care areas as stressful work environments for nurses and have identified factors contributing to job satisfaction and staff retention. However, very little research has examined these relationships in the Saudi context. Design and Methods This study utilised an exploratory, cross-sectional survey design to examine the relationship between RN job satisfaction and intention to leave at King Abdul-Aziz University Hospital, Saudi Arabia. Respondents completed a self-administered survey including demographic items and validated measures of job satisfaction and intention to leave. A convenience sample of 182 RNs working in critical care areas during the data collection period were included. Results Regression analysis predicting RN intention to leave found that demographic variables including age, parental status and length of ICU experience, and three of the job satisfaction subscales including perceived workload, professional support and pay and prospects for promotion, were significantly associated with the outcome variable. Conclusion This study adds to the existing literature on the relationship between job satisfaction and intention to leave critical care areas among RNs working in Saudi Arabia. These findings point to the need for management and policy interventions targeting nurses’ workloads, professional support and pay and promotion in order to improve nurse retention.

Re-examining the evidence in radiation dermatitis management literature : an overview and a critical appraisal of systematic reviews

Purpose: To provide an overview and a critical appraisal of systematic reviews (SRs) of published interventions for the prevention/management of radiation dermatitis. Methods and Materials: We searched Medline, CINAHL, Embase, and the Cochrane Library. We also manually searched through individual reference lists of potentially eligible articles and a number of key journals in the topic area. Two authors screened all potential articles and included eligible SRs. Two authors critically appraised and extracted key findings from the included reviews using AMSTAR (the measurement tool for “assessment of multiple systematic reviews”). Results: Of 1837 potential titles, 6 SRs were included. A number of interventions have been reported to be potentially beneficial for managing radiation dermatitis. Interventions evaluated in these reviews included skin care advice, steroidal/nonsteroidal topical agents, systemic therapies, modes of radiation delivery, and dressings. However, all the included SRs reported that there is insufficient evidence supporting any single effective intervention. The methodological quality of the included studies varied, and methodological shortfalls in these reviews might create biases to the overall results or recommendations for clinical practice. Conclusions: An up-to-date high-quality SR in the prevention/management of radiation dermatitis is needed to guide practice and direction for future research. We recommend that clinicians or guideline developers critically evaluate the information of SRs in their decision making.

In Praise of Critical Criminology

This short essay examines the relationship between academic research and policy with particular emphasis on the question of whether a critical criminology can engage in academic critique at the same time as engaging in policy oriented research. Recognising that critical criminology falls between theory and politics criminologists are urged to adopt pragmatic, strategic positions as they negotiate their role in contentious debates and practical minefi elds. It is concluded that a critical criminology must try not only to think the unthinkable about crime, but also to speak the unspeakable about the conditions in which and by which it is known.

Contemporary Critical Criminology

The concept of critical criminology – that crime and the present day processes of criminalization are rooted in the core structures of society – is of more relevance today than it has been at any other time. Written by an internationally renowned scholar, Contemporary Critical Criminology introduces the most up-to-date empirical, theoretical, and political contributions made by critical criminologists around the world. In its exploration of this material, the book also challenges the erroneous but widely held notion that the critical criminological project is restricted to mechanically applying theories to substantive topics, or to simple calling for radical political, economic, cultural, and social transformations. This book is an essential source of reference for both undergraduate and postgraduate students of Criminology, Criminal Theory, Social Policy, Research Methodology, and Penology.

Handbook of Critical Criminonlogy

The Routledge Handbook of Critical Criminology is a collection of original essays specifically designed to offer students, faculty, policy makers, and others an in-depth overview of the most up-to-date empirical, theoretical, and political contributions made by critical criminologists around the world. Special attention is devoted to new theoretical directions in the field, such as cultural criminology, masculinities studies, and feminist criminologies. Its diverse essays not only cover the history of critical criminology and cutting edge theories, but also the variety of research methods used by leading scholars in the field and the rich data generated by their rigorous empirical work. In addition, some of the chapters suggest innovative and realistic short- and long-term policy proposals that are typically ignored by mainstream criminology. These progressive strategies address some of the most pressing social problems facing contemporary society today, and that generate much pain and suffering for socially and economically disenfranchised people. The Handbook explores up-to-date empirical, theoretical, and political contributions, and is specifically designed to be a comprehensive resource for undergraduate and post-graduate students, researchers, and policy makers.