Establishing the presence and state of organic matter, including its possible biosignatures, in martian materials has been an elusive quest, despite limited reports of the existence of organic matter ...on Mars. We report the in situ detection of organic matter preserved in lacustrine mudstones at the base of the ~3.5-billion-year-old Murray formation at Pahrump Hills, Gale crater, by the Sample Analysis at Mars instrument suite onboard the Curiosity rover. Diverse pyrolysis products, including thiophenic, aromatic, and aliphatic compounds released at high temperatures (500° to 820°C), were directly detected by evolved gas analysis. Thiophenes were also observed by gas chromatography–mass spectrometry. Their presence suggests that sulfurization aided organic matter preservation. At least 50 nanomoles of organic carbon persists, probably as macromolecules containing 5% carbon as organic sulfur molecules.
The Sample Analysis at Mars instrument stepped combustion experiment on a Yellowknife Bay mudstone at Gale crater, Mars revealed the presence of organic carbon of Martian and meteoritic origins. The ...combustion experiment was designed to access refractory organic carbon in Mars surface sediments by heating samples in the presence of oxygen to combust carbon to CO
2
. Four steps were performed, two at low temperatures (less than ∼550 °C) and two at high temperatures (up to ∼870 °C). More than 950 μg C/g was released at low temperatures (with an isotopic composition of δ
13
C = +1.5 ± 3.8‰) representing a minimum of 431 μg C/g indigenous organic and inorganic Martian carbon components. Above 550 °C, 273 ± 30 μg C/g was evolved as CO
2
and CO (with estimated δ
13
C = −32.9‰ to −10.1‰ for organic carbon). The source of high temperature organic carbon cannot be definitively confirmed by isotopic composition, which is consistent with macromolecular organic carbon of igneous origin, meteoritic infall, or diagenetically altered biomass, or a combination of these. If from allochthonous deposition, organic carbon could have supported both prebiotic organic chemistry and heterotrophic metabolism at Gale crater, Mars, at ∼3.5 Ga.
The quality and length of life for boys with Duchenne muscular dystrophy (DMD) has improved due to medical advancements, but obesity has emerged as and may pose a risk to their physical health. ...Clinical guidelines recommend attention to weight management, but healthcare professionals (HCPs) find implementing them in clinical care challenging. Little information is available about the perspectives of children with DMD and their families around weight management. This study explored the key priorities of children with DMD, their parents, and HCPs who treat them, around weight management.
Qualitative, individual, semi-structured interviews were conducted and analyzed using a qualitative descriptive approach.
Participants included parents of children with DMD (n = 13), children with DMD (n = 10), and HCPs (n = 14). Theme one: "Competing priorities between healthcare providers, parents, and boys" contained two sub-themes: (i) Body mechanics and function; and (ii) Psychosocial well-being. Theme two: "The realities of living with Duchenne's Muscular Dystrophy," with subthemes: (i) Striving for normality; (ii) The trajectory of DMD; (iii) The labour associated with DMD.
HCPs, parents, and boys have diverging worldviews around weight management, highlighting the importance of integrating the priorities of families into care, even when not aligned with guideline recommendations.
IMPLICATIONS FOR REHABILITATION
HCPs must understand the competing priorities in the lives of children with DMD and their families when discussing weight, weight management, and lifestyle changes.
Quality of life and living a "normal" life are prioritized by children and families over the surveillance and time demands of lifestyle routines recommended by clinicians for weight management.
Weight management recommendations should be based upon the individual needs and priorities of the family.
The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The ...SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover’s robotic arm.
The Sample Analysis at Mars on the Curiosity rover analyzed the major volatile content of four eolian samples at three locations in Gale crater. The Rocknest sample was taken from an inactive sand ...shadow with a significant component of dust‐sized grains, while Gobabeb and Ogunquit Beach samples were taken from different locations in the Bagnold Dune field and had dust‐free, fine sand sized grains. All eolian samples possessed more oxychlorine, carbon, and nitrate relative to sedimentary materials in Gale crater. Evolved CO2 above 450 °C was consistent with ~0.7 and ~0.4 wt. % carbonate in the Bagnold Dunes and Rocknest materials, respectively, with a regional source inside Gale crater. The fine‐grained phase of Rocknest was enriched in adsorbed water and perhaps in Fe sulfate and Fe nitrate/nitrite compared to coarser Bagnold materials and was estimated to contain up to ~0.1 wt. % of organic carbon.
Plain Language Summary
Wind‐driven processes have been the dominant force shaping the landscape on Mars for the last 3 billion years. Sands from a Martian dune field were analyzed and compared to other deposits with smaller, dust‐sized grains. Samples were heated to release gases and determine their composition, revealing that sandy and dusty samples contained more carbon than rock samples. Sand and dust contained more nitrogen and chlorine bearing molecules made in the atmosphere and grain surfaces, either because they are sitting on the surface accumulating them or because nitrogen and chlorine were removed from rocks in the past by water or other processes. Dusty samples had similar compositions to sandy samples and also contained phases associated only with the small dust grains, including adsorbed water. Dust appeared to contain simple organic carbon molecules, perhaps due to atmospheric and surface processes acting to break down more complex organic molecules in rocks. Sand appeared to contain more inorganic carbon in the form of carbonate, even though the rocks nearby do not contain carbonate. Because sand can only travel a limited distance, this suggests that carbonate is present in rocks somewhere in Gale crater that we have not explored yet.
Key Points
Eolian materials generally possessed more O2, CO2, and NO than sedimentary materials in Gale crater
The presence of CO2 that evolved at temperatures greater than 450 degrees Celsius is consistent with the presence of carbonate in the eolian materials
Differences in evolved gases between dust‐bearing and dust‐free eolian materials suggest that dust on Mars is enriched in volatiles
Introduction
Due to the increased risk of obesity for boys with Duchenne muscular dystrophy (DMD), recent guidelines recommend that dietary intake is carefully managed. Parents play an important role ...in the development of their child's eating behaviours and patterns. However, despite what is known about the increased risk of obesity for children with DMD, little is known about parental feeding behaviours in this population. The objective of this study was to qualitatively explore the experiences of parents of children with DMD around their child's weight management and understand what influences their feeding behaviours.
Methods
This paper reports a secondary data analysis. Semi‐structured, individual interviews were conducted and analysed using qualitative description.
Results
Thirteen parents were interviewed for the study. Three themes were developed: (1) parent responses to healthcare provider interactions, (2) mixed emotions contributing to feeding approach and (3) variable parenting feeding styles. Within the third theme, two subthemes arose including (1) control and preoccupation and (2) striking a balance.
Conclusion
Given the potential impact of higher weights on the progression of DMD, it is important that healthcare providers explore feeding behaviours with families. However, it is essential that healthcare providers consider the impact of these conversations on parents, as well as the broader issues that may place additional pressure on the lives of families.
The recent manufacture of portable laser-induced breakdown spectroscopy (pLIBS) instruments has permitted widespread applications of an established analytical technique for in situ geochemical ...quantifications. This novelty has created a need for investigations comparing the default univariate pLIBS calibration accuracies to custom instrument calibrations based on geological samples and to other modeling methods. Previous research has shown that multivariate models can mitigate some of the matrix effects that cause intensity and concentration non-linearity within LIBS plasmas of rocks. This study thus makes two pLIBS calibration comparisons: one compares partial least squares (PLS) multivariate regression to univariate instrument models, while the other compares the default instrument calibration, intended for general industrial use, to a custom instrument calibration based on rock standards. Both comparisons use root mean squared errors (RMSE) between model-predicted and true standard values of the major oxides Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2, and TiO2, and minor and trace elements Ba, Cr, Cu, H2O, Li, Ni, Pb, S, and Zn to test calibration accuracies. pLIBS spectra from 2007 diverse rock standards were used for the PLS versus univariate model comparison, while 89 publicly-available geochemical standards were used to compare the default and custom instrument calibrations. PLS models give test accuracies for major elements of ±8.61 wt% for SiO2, ±3.38 for Al2O3, ±0.77 for TiO2, ±3.84 for Fe2O3, ±4.41 wt% for MgO, ±3.08 wt% for CaO, ±1.09 wt% for Na2O, and ±1.52 wt% for K2O. Quantification of trace and minor elements was more accurate with multivariate regression than with univariate instrument models, and the new custom instrument calibration had lower prediction errors for these elements than those of the default models. However, minor and trace element errors from all three calibrations were often greater than the average concentration of the test standards, which suggests that these substances are not well quantified in rocks by pLIBS instruments.
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•Major oxides were predicted equally well among instrument and multivariate models.•PLS models gave much more accurate test predictions for trace and minor elements.•Large & diverse test standard suites give more robust instrument model accuracies.•Accuracy results appear consistent with other benchtop LIBS test errors.•Custom instrument models were generally more accurate than default calibrations.
To identify current practices related to the assessment, monitoring and discussion of bodyweight, growth and obesity in neuromuscular clinics for children with Duchenne muscular dystrophy (DMD).
A ...cross-sectional, online survey was distributed using snowball sampling to healthcare providers working with children with DMD across Canadian neuromuscular clinics. Summary and descriptive statistics were calculated. Content analysis was performed on open text responses.
Thirty-seven responses were received, representing a range of healthcare disciplines. Height and weight were routinely assessed by 32/37 (87%) respondents, although only 21/37 (57%) responses reported having a clinic standard for measuring height and 23/37 (62%) for weight. While 32/36 (89%) reported discussing weight during consultations, only 13/37 (35%) felt confident doing so. Dietitians were considered the most appropriate person to discuss and manage weight with children and families, although only 17/37 (46%) reported having a dietitian involved in their clinic.
Neuromuscular clinics could benefit from implementing consistent and recommended growth assessment practices. The development of evidence-based tools, training and protocols tailored to Duchenne muscular dystrophy should be a priority.
IMPLICATIONS FOR REHABILITATION
Growth and weight monitoring approaches vary within and between neuromuscular clinics.
Additional training on discussing and managing weight are warranted across disciplines.
Advocacy is required to ensure access to dietetic expertise within neuromuscular clinics.
The Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) rover Curiosity detected evolved gases during thermal analysis of soil samples from the Rocknest aeolian deposit in ...Gale Crater. Major species detected (in order of decreasing molar abundance) were H2O, SO2, CO2, and O2, all at the µmol level, with HCl, H2S, NH3, NO, and HCN present at the tens to hundreds of nmol level. We compute weight % numbers for the major gases evolved by assuming a likely source and calculate abundances between 0.5 and 3 wt.%. The evolution of these gases implies the presence of both oxidized (perchlorates) and reduced (sulfides or H‐bearing) species as well as minerals formed under alkaline (carbonates) and possibly acidic (sulfates) conditions. Possible source phases in the Rocknest material are hydrated amorphous material, minor clay minerals, and hydrated perchlorate salts (all potential H2O sources), carbonates (CO2), perchlorates (O2 and HCl), and potential N‐bearing materials (e.g., Martian nitrates, terrestrial or Martian nitrogenated organics, ammonium salts) that evolve NH3, NO, and/or HCN. We conclude that Rocknest materials are a physical mixture in chemical disequilibrium, consistent with aeolian mixing, and that although weathering is not extensive, it may be ongoing even under current Martian surface conditions.
Key Points
Major volatiles detected by SAM were H2O, SO2, CO2, and O2
Minor volatiles include HCl, H2S, NH3, NO, and HCN
Calculating abundances from counts per second is explained
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