The Origin of Iddingsite Veins in Olivine from the Nakhlite Meteorites:New Insights from Analogy with CM Carbonaceous Chondrites and Terrestrial Basalts

The nakhlite meteorites are samples of a ~1300 million year old martian clinopyroxenite lava flow or sill [1, 2]. These rocks contain secondary minerals including hydrous silicates, carbonates, sulphates and Fe-(hydr)oxides that formed by watermediated alteration of the igneous body [3, 4]. A prerequisite for understanding the nature of the aqueous system from which these minerals formed, including water/rock ratio, the provenance of solutes and its longevity, is knowing whether the secondary minerals formed by replacement of primary igneous components (minerals and glasses), or by cementation of pores that were opened by fracturing. A replacive origin would suggest low water/rock ratios with solutions being close to saturation with respect to secondary minerals, and does not require a pre-existing network of pores for fluids to gain access to mineral grain interiors. An origin by cementation would suggest that solutes had been sourced by dissolution of other parts of the nakhlite parent rock or the martian crust and were introduced by fluid flow under relatively high water/rock ratio conditions; a means of fracturing the rock is also required.<p></p> Here we have sought to answer the question of whether olivine-hosted veins in the nakhlites formed by cementation or replacement by comparing the microstructures of veins in the nakhlite Lafayette with veins in olivine grains from type I chondrules in Murchison (CM2 carbonaceous chondrite). We also draw on previously published work on ‘iddingsite’ veins in olivine from terrestrial basalts.<p></p&gt

Copper-catalysed C-H functionalisation gives access to 2-aminobenzimidazoles

This paper describes the development, optimisation and exemplification of a copper-catalysed C–H functionalisation to form pharmaceutically relevant 2-aminobenzimidazoles from aryl-guanidines. High throughput screening was used as a tool to identify a catalytically active copper source, DoE was used for reaction optimisation and a range of aryl-guanidines were prepared and exposed to the optimum conditions to afford a range of 2-aminobenzimidazoles in moderate to good yields. The methodology has been applied to the synthesis of Emedastine, a marketed anti-histamine pharmaceutical compound, with the key cyclisation step performed on a gram-scale

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

Utility of international normative 20 m shuttle run values for identifying youth at increased cardiometabolic risk

The purpose of this study was to examine the ability of international normative centiles for the 20 m shuttle run test (20mSRT) to identify youth at increased cardiometabolic risk. This was a cross-sectional study involving 961 children aged 10–17 years (53% girls) from the United Kingdom. Receiver operating characteristic (ROC) curves determined the discriminatory ability of cardiorespiratory fitness percentiles for predicting increased cardiometabolic risk. ROC analysis demonstrated a significant but poor discriminatory accuracy of cardiorespiratory fitness in identifying low/high cardiometabolic risk in girls (AUC = 0.58, 95% CI: 0.54–0.63; p = 0.04), and in boys (AUC = 0.59, 95% CI: 0.54–0.63; p = 0.03). The cardiorespiratory fitness cut-off associated with high cardiometabolic risk was the 55th percentile (sensitivity = 33.3%; specificity = 84.5%) in girls and the 60th percentile (sensitivity = 42.9%; specificity = 73.6%) in boys. These 20mSRT percentile thresholds can be used to identify children and adolescents who may benefit from lifestyle intervention. Nonetheless, further work involving different populations and cardiometabolic risk scores comprising of different variables are needed to confirm our initial findings

The relationship between ventilatory threshold and repeated-sprint ability in competitive male ice hockey players

Background/objective The relationship between ventilatory threshold (VT1, VT2) and repeated-sprint ability (RSA) in competitive male ice hockey players was investigated. Methods Forty-three male ice hockey players aged 18–23 years competing in NCAA Division I, NCAA Division III, and Junior A level participated. Participants performed an incremental graded exercise test on a skate treadmill to determine V˙ role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3eV˙O2peak, VT1, and VT2 using MedGraphics Breezesuit™ software (v-slope). Participants performed an on-ice repeated shift (RSA) test consisting of 8-maximal skating bouts, lasting approximately 25 s and interspersed with 90 s of passive recovery, to determine first gate, second gate, and total sprint decrement (%dec). Pearson product-moment correlations and multiple regressions were used to assess relationships between ventilatory threshold variables (VT1, VT2, Stage at VT1, and Stage at VT2) and RSA (first gate, second gate, and total course decrement). Results Stage at VT2 was the only variable substantially correlated with first gate (r = −0.35; P \u3c 0.05), second gate (r = −0.58; P \u3c 0.001) and total course decrement (r = −0.42; P \u3c 0.05). Conclusion The results of this study demonstrated that VT is substantially associated with RSA, and VT2 is more strongly correlated with RSA than V˙ role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3eV˙O2peak. This study suggests that longer duration high-intensity interval training at intensities that increase workrate at VT2 may lead to possible improvements in RSA

Temporal trends in the handgrip strength of 2,592,714 adults from 14 countries between 1960 and 2017: A systematic analysis

Background: Handgrip strength (HGS) is an excellent marker of functional capability and health in adults, although little is known about temporal trends in adult HGS. Objectives: The aim of this study was to systematically analyze national (country-level) temporal trends in adult HGS, and to examine relationships between national trends in adult HGS and national trends in health-related and socioeconomic/demographic indicators. Methods: Data were obtained from a systematic search of studies reporting temporal trends in HGS for adults (aged ≥20 years) and by examining national fitness datasets. Trends in mean HGS were estimated at the country-sex-age group level by best-fitting sample-weighted linear/polynomial regression models, with national and sub-regional (pooled data across geographically similar countries) trends estimated by a post-stratified population-weighting procedure. Pearson’s correlations quantified relationships between national trends in adult HGS and national trends in health-related and socioeconomic/demographic indicators. Results: Data from 10 studies/datasets were extracted to estimate trends in mean HGS for 2,592,714 adults from 12 high- and 2 upper-middle-income countries (from Asia, Europe and North America) between 1960 and 2017. National trends were few, mixed and generally negligible pre-2000, whereas most countries (75% or 9/12) experienced negligible-to-small declines ranging from an effect size of 0.05 to 0.27, or 0.6 to 6.3%, per decade post-2000. Sex- and age-related temporal differences were negligible. National trends in adult HGS were not significantly related to national trends in health and socioeconomic/demographic indicators. Conclusions: While trends in adult HGS are currently limited to 14 high- and upper-middle-income countries from 3 continents, adult HGS appears to have declined since 2000 (at least among most of the countries in this analysis), which is suggestive of corresponding declines in functional capability and health. PROSPERO registration number: CRD42013003678. KEY POINTS National (country-level) trends in adult handgrip strength (HGS) were few, mixed and generally negligible pre-2000, and generally negligible and indicated declines post-2000 Sex- and age-related temporal differences in adult HGS were negligible-to-small at the country level and negligible at the regional level National trends in adult HGS were not significantly related to national trends in health and socioeconomic/demographic indicator

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