Constraining the formation conditions of the ancient martian ALH 84001 carbonates

The martian meteorite ALH 84001 contains carbonates that provide information about the past aqueous conditions on Mars 3.9 Ga, and have been suggested to display signatures of martian organics. Determining the conditions under which the carbonates formed is crucial for addressing whether there was once life on Mars and the history of martian hydrosphere and atmosphere. This study has combined new sample preparation techniques with fresh isotopic analyses of ALH 84001 carbonates and analogue materials, geochemical modelling and the testing of future equipment (WatSen) suitable for carbonate detection on Mars. The results from these lnvestigations have provided quantitative constraints on the formation environment for the ALH 84001 carbonates and an instrument capable of detecting carbonates on Mars. The microscale carbon and oxygen analyses of ALH 84001 carbonates provide the first combined transient study across the carbonates with δ13C and δ18O values correlated ,with chemical compositions. The δ13C values range from -18.6% to +23.2% extending and lowering the previous ion microprobe δ13C range found and suggests that reduced carbon is present in the carbonates. This component exists as either macromolecular carbon introduced through subsequent alteration, terrestrial contamination or martian organics. The δ18O range -0.1% +27.1% is consistent with previous authors and displays a clear correlation with δ18O enrichment with distance from the carbonates core to edge. An 18.6% range in δ18O values was measured across analogue carbonates similar in size, shape and chemical variation which formed in a hydrothermal environmen

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

International variability in 20 m shuttle run performance in children and youth: who are the fittest from a 50-country comparison? A systematic literature review with pooling of aggregate results

Objectives To describe and compare 20 m shuttle run test (20mSRT) performance among children and youth across 50 countries; to explore broad socioeconomic indicators that correlate with 20mSRT performance in children and youth across countries and to evaluate the utility of the 20mSRT as an international population health indicator for children and youth. Methods A systematic review was undertaken to identify papers that explicitly reported descriptive 20mSRT (with 1-min stages) data on apparently healthy 9–17 year-olds. Descriptive data were standardised to running speed (km/h) at the last completed stage. Country-specific 20mSRT performance indices were calculated as population-weighted mean z-scores relative to all children of the same age and sex from all countries. Countries were categorised into developed and developing groups based on the Human Development Index, and a correlational analysis was performed to describe the association between country-specific performance indices and broad socioeconomic indicators using Spearman\u27s rank correlation coefficient. Results Performance indices were calculated for 50 countries using collated data on 1 142 026 children and youth aged 9–17 years. The best performing countries were from Africa and Central-Northern Europe. Countries from South America were consistently among the worst performing countries. Country-specific income inequality (Gini index) was a strong negative correlate of the performance index across all 50 countries. Conclusions The pattern of variability in the performance index broadly supports the theory of a physical activity transition and income inequality as the strongest structural determinant of health in children and youth. This simple and cost-effective assessment would be a powerful tool for international population health surveillance

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

Life on Holidays: Study Protocol for a 3-Year Longitudinal Study Tracking Changes in Children\u27s Fitness and Fatness during the In-School Versus Summer Holiday Period

Background: Emerging evidence suggests that children become fatter and less fit over the summer holidays but get leaner and fitter during the in-school period. This could be due to differences in diet and time use between these distinct periods. Few studies have tracked diet and time use across the summer holidays. This study will measure rates of change in fatness and fitness of children, initially in Grade 4 (age 9 years) across three successive years and relate these changes to changes in diet and time use between in-school and summer holiday periods. Methods: Grade 4 Children attending Australian Government, Catholic and Independent schools in the Adelaide metropolitan area will be invited to participate, with the aim of recruiting 300 students in total. Diet will be reported by parents using the Automated Self-Administered 24-h Dietary Assessment Tool. Time use will be measured using 24-h wrist-worn accelerometry (GENEActiv) and self-reported by children using the Multimedia Activity Recall for Children and Adults (e.g. chores, reading, sport). Measurement of diet and time use will occur at the beginning (Term 1) and end (Term 4) of each school year and during the summer holiday period. Fitness (20-m shuttle run and standing broad jump) and fatness (body mass index z-score, waist circumference, %body fat) will be measured at the beginning and end of each school year. Differences in rates of change in fitness and fatness during in-school and summer holiday periods will be calculated using model parameter estimate contrasts from linear mixed effects model. Model parameter estimate contrasts will be used to calculate differences in rates of change in outcomes by socioeconomic position (SEP), sex and weight status. Differences in rates of change of outcomes will be regressed against differences between in-school and summer holiday period diet and time use, using compositional data analysis. Analyses will adjust for age, sex, SEP, parenting style, weight status, and pubertal status, where appropriate. Discussion: Findings from this project may inform new, potent avenues for intervention efforts aimed at addressing childhood fitness and fatness. Interventions focused on the home environment, or alternatively extension of the school environment may be warranted. Trial registration: Australia New Zealand Clinical Trials Registry, identifier ACTRN12618002008202. Retrospectively registered on 14 December 2018

Evidence for methane in Martian meteorites

The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity

The great leap backward: changes in the jumping performance of Australian children aged 11−12-years between 1985 and 2015

Previous data have indicated relative stability over time of paediatric jumping performance, but few data exist since the early 2000s. This study quantified the 30-year secular changes in jumping performance of Australian children aged 11−12-years using data from the Australian Schools Health and Fitness Survey (1985, n = 1967) and Growing Up in Australia’s Child Health CheckPoint (2015, n = 1765). Both cohorts measured jumping performance (standing long jump distance), anthropometric and demographic data. Secular changes in jumping performance means and quantiles were examined using multivariable linear and quantile regression. Between 1985 and 2015, jumping performance declined by 16.4 cm or by 11.2% (standardised change 0.66 SD, 95%CI 0.60 to 0.73). Adjustment for body mass reduced the effect by 32%, although the decline remained (absolute change – 11.1 cm, 95%CI −12.5 to −9.7; percent change 7.7%, 95%CI 6.7 to 8.6; standardised change 0.51 SD, 95%CI 0.44 to 0.57). This decline was evident across all quantiles. The jumping performance of Australian children aged 11−12-years has declined between 1985 and 2015, with body mass changes accounting for only part of the decline. Efforts should continue to promote paediatric muscular fitness, reduce adiposity, and aim to reverse this decline in jumping performance.</p

Modulation of enhancer looping and differential gene targeting by Epstein-Barr virus transcription factors directs cellular reprogramming

Epstein-Barr virus (EBV) epigenetically reprogrammes B-lymphocytes to drive immortalization and facilitate viral persistence. Host-cell transcription is perturbed principally through the actions of EBV EBNA 2, 3A, 3B and 3C, with cellular genes deregulated by specific combinations of these EBNAs through unknown mechanisms. Comparing human genome binding by these viral transcription factors, we discovered that 25% of binding sites were shared by EBNA 2 and the EBNA 3s and were located predominantly in enhancers. Moreover, 80% of potential EBNA 3A, 3B or 3C target genes were also targeted by EBNA 2, implicating extensive interplay between EBNA 2 and 3 proteins in cellular reprogramming. Investigating shared enhancer sites neighbouring two new targets (WEE1 and CTBP2) we discovered that EBNA 3 proteins repress transcription by modulating enhancer-promoter loop formation to establish repressive chromatin hubs or prevent assembly of active hubs. Re-ChIP analysis revealed that EBNA 2 and 3 proteins do not bind simultaneously at shared sites but compete for binding thereby modulating enhancer-promoter interactions. At an EBNA 3-only intergenic enhancer site between ADAM28 and ADAMDEC1 EBNA 3C was also able to independently direct epigenetic repression of both genes through enhancer-promoter looping. Significantly, studying shared or unique EBNA 3 binding sites at WEE1, CTBP2, ITGAL (LFA-1 alpha chain), BCL2L11 (Bim) and the ADAMs, we also discovered that different sets of EBNA 3 proteins bind regulatory elements in a gene and cell-type specific manner. Binding profiles correlated with the effects of individual EBNA 3 proteins on the expression of these genes, providing a molecular basis for the targeting of different sets of cellular genes by the EBNA 3s. Our results therefore highlight the influence of the genomic and cellular context in determining the specificity of gene deregulation by EBV and provide a paradigm for host-cell reprogramming through modulation of enhancer-promoter interactions by viral transcription factors

Reproducible image-based profiling with Pycytominer

Technological advances in high-throughput microscopy have facilitated the acquisition of cell images at a rapid pace, and data pipelines can now extract and process thousands of image-based features from microscopy images. These features represent valuable single-cell phenotypes that contain information about cell state and biological processes. The use of these features for biological discovery is known as image-based or morphological profiling. However, these raw features need processing before use and image-based profiling lacks scalable and reproducible open-source software. Inconsistent processing across studies makes it difficult to compare datasets and processing steps, further delaying the development of optimal pipelines, methods, and analyses. To address these issues, we present Pycytominer, an open-source software package with a vibrant community that establishes an image-based profiling standard. Pycytominer has a simple, user-friendly Application Programming Interface (API) that implements image-based profiling functions for processing high-dimensional morphological features extracted from microscopy images of cells. Establishing Pycytominer as a standard image-based profiling toolkit ensures consistent data processing pipelines with data provenance, therefore minimizing potential inconsistencies and enabling researchers to confidently derive accurate conclusions and discover novel insights from their data, thus driving progress in our field.Comment: 13 pages, 4 figure

Relationship of aerobic fitness and motor skills with memory and attention in preschoolers (Ballabeina): A cross-sectional and longitudinal study

BACKGROUND: The debate about a possible relationship between aerobic fitness and motor skills with cognitive development in children has recently re-emerged, because of the decrease in children's aerobic fitness and the concomitant pressure of schools to enhance cognitive performance. As the literature in young children is scarce, we examined the cross-sectional and longitudinal relationship of aerobic fitness and motor skills with spatial working memory and attention in preschool children. METHODS: Data from 245 ethnically diverse preschool children (mean age: 5.2 (0.6) years, girls: 49.4%) analyzed at baseline and 9 months later. Assessments included aerobic fitness (20 m shuttle run) and motor skills with agility (obstacle course) and dynamic balance (balance beam). Cognitive parameters included spatial working memory (IDS) and attention (KHV-VK). All analyses were adjusted for age, sex, BMI, migration status, parental education, native language and linguistic region. Longitudinal analyses were additionally adjusted for the respective baseline value. RESULTS: In the cross-sectional analysis, aerobic fitness was associated with better attention (r=0.16, p=0.03). A shorter time in the agility test was independently associated with a better performance both in working memory (r=-0.17, p=0.01) and in attention (r=-0.20, p=0.01). In the longitudinal analyses, baseline aerobic fitness was independently related to improvements in attention (r=0.16, p=0.03), while baseline dynamic balance was associated with improvements in working memory (r=0.15, p=0.04). CONCLUSIONS: In young children, higher baseline aerobic fitness and motor skills were related to a better spatial working memory and/or attention at baseline, and to some extent also to their future improvements over the following 9 months. TRIAL REGISTRATION: clinicaltrials.gov NCT0067454