Solution phase, solid state, and theoretical investigations on the MacMillan imidazolidinone

A combination of soln. phase NMR, X-ray crystallog. studies, and DFT calcns. provide a consistent structural conformation for iminium ions derived from the MacMillan imidazolidinone

Do paramedics have a role to play in organ donation?

The future role paramedics may play in organ donation is unclear, and potential ethical, legal and professional issues need to be thoroughly researched and addressed

Evidence that digital game players neglect age classification systems when deciding which games to play

This article considers players’ experiences seeking out new games to play, and their use of the Australian National Classification Scheme in doing so. The global video game industry is booming, with hundreds of games being released each month across numerous platforms. As a result, players have an unprecedented number of games available when choosing what games to purchase. However, a number of confounding issues around the emergent content of games and the subjective nature of game reviewing makes it difficult to relate what kinds of experiences a given game will facilitate. In this study, we surveyed game players in order to find their game platform and acquisition preferences; strategies and experiences when choosing games; and attitudes towards classification systems. Our findings suggest that players find it difficult to choose what games to purchase, and that existing classification systems are mostly only beneficial when choosing games for minors

Review of criterion-referenced standards for cardiorespiratory fitness: what percentage of 1 142 026 international children and youth are apparently healthy?

Purpose To identify criterion-referenced standards for cardiorespiratory fitness (CRF); to estimate the percentage of children and youth that met each standard; and to discuss strategies to help improve the utility of criterion-referenced standards for population health research. Methods A search of four databases was undertaken to identify papers that reported criterion-referenced CRF standards for children and youth generated using the receiver operating characteristic curve technique. A pseudo-dataset representing the 20-m shuttle run test performance of 1 142 026 children and youth aged 9–17 years from 50 countries was generated using Monte Carlo simulation. Pseudo-data were used to estimate the international percentage of children and youth that met published criterion-referenced standards for CRF. Results Ten studies reported criterion-referenced standards for healthy CRF in children and youth. The mean percentage (±95% CI) of children and youth that met the standards varied substantially across age groups from 36%±13% to 95%±4% among girls, and from 51%±7% to 96%±16% among boys. There was an age gradient across all criterion-referenced standards where younger children were more likely to meet the standards compared with older children, regardless of sex. Within age groups, mean percentages were more precise (smaller CI) for younger girls and older boys. Conclusion There are several CRF criterion-referenced standards for children and youth producing widely varying results. This study encourages using the interim international criterion-referenced standards of 35 and 42 mL/kg/min for girls and boys, respectively, to identify children and youth at risk of poor health—raising a clinical red flag

Martian Igneous Activity and Fluid-Based Alteration:Chronological Constraints from 40Ar/39Ar Analyses of the Nakhlites

The nakhlites are a group of mafic igneous rocks that crystallized on Mars at ca. 1.3-1.4 Ga [1-5]. They are amongst the least shocked Martian meteorites, with cumulate igneous textures (Fig. 1) and thus provide a crucial record of igneous activity and fluid-rock interaction on the red planet. Crystallization of the nakhlites. Understanding the original structure of the nakhlite source is crucial for using these stones to explore Martian igneous processes. In particular, are the different nakhlites from a single thick and differentiated lava flow/sill [6; 7], or do they instead represent magmatically related – but distinct – flows/intrusions? If the various meteorites are derived from separate units, then there will be differences in crystallization ages within the nakhlite suite – which may be identified if these differences are sufficiently large relative to the attainable precision of radioisotopic dating techniques. Some studies [e.g., 5] appear to resolve age differences between different stones, and we aim to test the single vs. multiple unit hypotheses via application of detailed 40Ar/39Ar stepheating of six nakhlites.<p></p> Alteration of the nakhlites, and the timing of waterrock interaction. In addition to primary magmatic minerals and glasses, the nakhlites contain secondary minerals including clays and carbonates that were precipitated by Martian aqueous fluids prior to impact ejection (Fig. 2) [8-10]. When did this alteration occur? As the clays contain potassium, they are amenable to K-Ar and 40Ar/39Ar dating. K-Ar data from Lafayette suggests the alteration phases formed between 0 to 670 Ma [11]. We consider further the timing of alteration using our 40Ar/39Ar data.<p></p&gt

Making a case for cardiorespiratory fitness surveillance among children and youth

We review the evidence that supports cardiorespiratory fitness (CRF) as an important indicator of current and future health among school-aged children and youth, independent of physical activity levels. We discuss the merit of CRF measurement for population health surveillance and propose the development of CRF guidelines to help support regional, national, and international surveillance efforts