N-Alkane Biosignatures in a High Arctic Mars Analogue Gossan Deposit

If past life ever existed on Mars, what are the multiple ways it could have been preserved in the Martian geological record? This crucial question is becoming especially relevant the more we uncover about the planet’s ancient wet history. Different acidic and sulfur rich analog environments have been proposed that are comparable to the alteration environments of iron oxides and sulfate minerals on Mars. However, some authors have hypothesized that these past Martian environments might have been cold and semi-dry, similar to polar regions on Earth. As part of the T-MARS team, we studied reactive gossans in the Canadian High Arctic, on Axel Heiberg Island, as an analog environment to similar deposits on Mars. We hypothesized that n-alkane lipids could potentially be an important form of molecular fossils entombed in varying mineral assemblages of sulphates, iron oxides, and phyllosilicates in Arctic gossans, because of their excellent preservation potential relative to most other forms of organic molecules. To determine the preservation potential of lipids in mineralogically varying acidic sulfur rich gossan deposits, this study extracted and quantified n-alkane biomarkers from three different Arctic gossans with gas chromatography–mass spectrometry (GC-MS). Total organic carbon, pH, and mineralogy were also determined. Organic matter was found to be very low in all samples (<1% wt.%). N-alkane analysis also revealed preserved even-over-odd distribution patterns in short chain n-alkanes, most likely from a microbial source, along with evidence for long-chain n-alkanes with odd-over-even distribution from higher plant sources. The presence of these unique chemical biosignatures in low organic, highly acidic, and sulfur rich Mars analog gossans of varying maturity provides evidence that sulfur deposits linked to paleo hydrothermal systems on Mars can be promising targets for preserved organic biosignatures, specifically lipid n-alkanes. The significant diversity in biosignature patterns across samples of varying mineralogy, pH, and oxidation levels within each gossan suggests that n-alkane preservation varies on a small scale in these environments. These factors alone do not definitively account for the variability of n-alkane concentrations and distributions in this study, and additional investigations of these and other influencing factors are needed to determine which specific targets to choose for biosignature search on Mars in future space missions. This exploratory study provides novel insights into the lipid biosignature content in high Arctic Mars analogue gossan deposits

Fall-Related Psychological Concerns and Anxiety among Community-Dwelling Older Adults: Systematic Review and Meta-Analysis

<div><p>Fear of falling and other fall-related psychological concerns (FRPCs), such as falls-efficacy and balance confidence, are highly prevalent among community-dwelling older adults. Anxiety and FRPCs have frequently, but inconsistently, been found to be associated in the literature. The purpose of this study is to clarify those inconsistencies with a systematic review and meta-analysis and to evaluate if the strength of this relationship varies based on the different FRPC constructs used (e.g., fear of falling, falls-efficacy or balance confidence). A systematic review was conducted through multiple databases (e.g., MEDLINE, PsycINFO) to include all articles published before June 10^th 2015 that measured anxiety and FRPCs in community-dwelling older adults. Active researchers in the field were also contacted in an effort to include unpublished studies. The systematic review led to the inclusion of twenty relevant articles (n = 4738). A random-effect meta-analysis revealed that the mean effect size for fear of falling and anxiety is r = 0.32 (95% CI: 0.22–0.40), Z = 6.49, p < 0.001 and the mean effect size for falls-efficacy or balance confidence and anxiety is r = 0.31 (95% CI: 0.23–0.40), Z = 6.72, p < 0.001. A Q-test for heterogeneity revealed that the two effect sizes are not significantly different (Q(19) = 0.13, p = n.s.). This study is the first meta-analysis on the relationship between anxiety and FRPCs among community-dwelling older adults. It demonstrates the importance of considering anxiety when treating older adults with FRPCs.</p></div

The Client’s Intervention Priorities (CIP)©: A person-centered tool to support goal setting during interdisciplinary neurorehabilitation

Evidence-based neurorehabilitation must be informed by the values, expectations, and goals of individuals with acquired brain injury (ABI). The Client’s Intervention Priorities (CIP)© is a person-centered tool for defining rehabilitation priorities according to self-perceived functioning. The use of the CIP tool is encouraged to promote self-determination and optimal involvement of individuals with ABI in interdisciplinary neurorehabilitation. The objective of this study was to determine the reliability (internal consistency, temporal stability) and content validity (expert agreement) of the CIP tool. Thirty individuals with ABI (66.7% with traumatic brain injury, 33.3% with stroke) with a mean age of 44.8 (SD = 12.6) years were administered the CIP twice at a test-retest interval of 2.3 (SD = 0.7) weeks. An expert panel of 17 neurorehabilitation clinicians and researchers participated in the validation. The CIP tool showed excellent (total score α = .90) and good (CIP subscales α = .83-.87) internal consistencies, with excellent temporal stability (intraclass correlation coefficients = .78-.90). Experts agreed that the CIP items reflect the Disability Creation Process model (89.4% scored as having high to very high correspondence) and were comprehensibly stated (98% rated as clear to absolutely clear). The CIP is a valid and reliable self-assessment tool to assist professionals and their clients in developing and prioritizing rehabilitation goals

Summary of selected studies.

<p>Summary of selected studies.</p

Funnel plot of fear of falling studies.

<p>Funnel plot of fear of falling studies.</p

Forest plot of fear of falling studies.

<p>Forest plot of fear of falling studies.</p

PRISMA flow diagram of the inclusion of studies.

<p>PRISMA flow diagram of the inclusion of studies.</p

Funnel plot of falls-efficacy or balance confidence studies.

<p>Funnel plot of falls-efficacy or balance confidence studies.</p

Forest plot of falls efficacy or balance confidence studies.

<p>Forest plot of falls efficacy or balance confidence studies.</p