Origin of acidic surface waters and the evolution of atmospheric chemistry on early Mars

Observations from in situ experiments and planetary orbiters have shown that the sedimentary rocks found at Meridiani Planum, Mars were formed in the presence of acidic surface waters. The water was thought to be brought to the surface by groundwater upwelling, and may represent the last vestiges of the widespread occurrence of liquid water on Mars. However, it is unclear why the surface waters were acidic. Here we use geochemical calculations, constrained by chemical and mineralogical data from the Mars Exploration Rover Opportunity, to show that Fe oxidation and the precipitation of oxidized iron (Fe^(3+)) minerals generate excess acid with respect to the amount of base anions available in the rocks present in outcrop. We suggest that subsurface waters of near-neutral pH and rich in Fe^(2+) were rapidly acidified as iron was oxidized on exposure to O_2 or photo-oxidized by ultraviolet radiation at the martian surface. Temporal variation in surface acidity would have been controlled by the availability of liquid water, and as such, low-pH fluids could be a natural consequence of the aridification of the martian surface. Finally, because iron oxidation at Meridiani would have generated large amounts of gaseous H_2, ultimately derived from the reduction of H_2O, we conclude that surface geochemical processes would have affected the redox state of the early martian atmosphere

Spatial Guilds in the Serengeti Food Web Revealed by a Bayesian Group Model

Food webs, networks of feeding relationships among organisms, provide fundamental insights into mechanisms that determine ecosystem stability and persistence. Despite long-standing interest in the compartmental structure of food webs, past network analyses of food webs have been constrained by a standard definition of compartments, or modules, that requires many links within compartments and few links between them. Empirical analyses have been further limited by low-resolution data for primary producers. In this paper, we present a Bayesian computational method for identifying group structure in food webs using a flexible definition of a group that can describe both functional roles and standard compartments. The Serengeti ecosystem provides an opportunity to examine structure in a newly compiled food web that includes species-level resolution among plants, allowing us to address whether groups in the food web correspond to tightly-connected compartments or functional groups, and whether network structure reflects spatial or trophic organization, or a combination of the two. We have compiled the major mammalian and plant components of the Serengeti food web from published literature, and we infer its group structure using our method. We find that network structure corresponds to spatially distinct plant groups coupled at higher trophic levels by groups of herbivores, which are in turn coupled by carnivore groups. Thus the group structure of the Serengeti web represents a mixture of trophic guild structure and spatial patterns, in contrast to the standard compartments typically identified in ecological networks. From data consisting only of nodes and links, the group structure that emerges supports recent ideas on spatial coupling and energy channels in ecosystems that have been proposed as important for persistence.Comment: 28 pages, 6 figures (+ 3 supporting), 2 tables (+ 4 supporting

A cross sectional evaluation of an alcohol intervention targeting young university students

BACKGROUND: Hazardous drinking has been found to be higher among young university students compared to their non-university peers. Although young university students are exposed to new and exciting experiences, including greater availability and emphasis on social functions involving alcohol there are few multi strategy comprehensive interventions aimed at reducing alcohol-related harms. METHODS: Random cross sectional online surveys were administered to 18-24 year old students studying at the main campus of a large metropolitan university in Perth, Western Australia. Prior to the completion of the second survey an alcohol intervention was implemented on campus. Completed surveys were received from 2465 (Baseline; T1) and 2422 (Post Year 1: T2) students. Students who consumed alcohol in the past 12 months were categorised as low risk or hazardous drinkers using the Alcohol Use Disorders Identification Test (AUDIT). Due to the cross sectional nature of the two samples two-tailed two-proportion z-test and two sample t-tests were employed to determine statistical significance between the two time periods for categorical and continuous variables respectively. RESULTS: At T1 and T2 89.1 % and 87.2 % of the total sample reported drinking alcohol in the past month respectively. Hazardous levels of alcohol consumption reduced slightly between T1 (39.7 %) and T2 (38 %). In both time periods hazardous drinkers reported significantly higher mean scores for experienced harm, second-hand harm and witnessed harm scores compared to low risk drinkers (p <0.001). Hazardous drinkers were significantly more likely to experience academic problems due to their alcohol consumption and to report more positive alcohol expectations than low risk drinkers at both time periods (p <0.001). CONCLUSIONS: Harms and problems for students who report hazardous drinking are of concern and efforts should be made to ensure integrated and targeted strategies reach higher risk students and focus on specific issues such as driving while intoxicated and alcohol related unplanned sexual activity. However there is also a need for universal strategies targeting all students and low risk drinkers as they too are exposed to alcohol harms within the drinking and social environment. Changing the culture of the university environment is a long term aim and to effect change a sustained combination of organisational actions, partnerships and educational actions is required

Risk factors for incident falls in older men and women:The English longitudinal study of ageing

Background: falls are a major cause of disability and death in older people, particularly women. Cross-sectional surveys suggest that some risk factors associated with a history of falls may be sex-specific, but whether risk factors for incident falls differ between the sexes is unclear. We investigated whether risk factors for incident falls differ between men and women.Methods: participants were 3298 people aged ≥60 who took part in the Waves 4-6 surveys of the English Longitudinal Study of Ageing. At Wave 4, they provided information about sociodemographic, lifestyle, behavioural and medical factors and had their physical and cognitive function assessed. Data on incident falls during the four-year follow-up period was collected from them at Waves 5 and 6. Poisson regression with robust variance estimation was used to derive relative risks (RR) for the association between baseline characteristics and incident falls.Results: in multivariable-adjusted models that also controlled for history of falls, older age was the only factor associated with increased risk of incident falls in both sexes. Some factors were only predictive of falls in one sex, namely more depressive symptoms (RR (95% CI) 1.03 (1.01,1.06)), incontinence (1.12 (1.00,1.24)) and never having married in women (1.26 (1.03,1.53)), and greater comorbidity (1.04 (1.00,1.08)), higher levels of pain (1.10 (1.04,1.17) and poorer balance, as indicated by inability to attempt a full-tandem stand, (1.23 (1.04,1.47)) in men. Of these, only the relationships between pain, balance and comorbidity and falls risk differed significantly by sex.Conclusions: there were some differences between the sexes in risk factors for incident falls. Our observation that associations between pain, balance and comorbidity and incident falls risk varied by sex needs further investigation in other cohorts. <br/

Understanding clinician attitudes towards implementation of guided self-help cognitive behaviour therapy for those who hear distressing voices: using factor analysis to test normalisation process theory

Background The Normalisation Process Theory (NPT) has been used to understand the implementation of physical health care interventions. The current study aims to apply the NPT model to a secondary mental health context, and test the model using exploratory factor analysis. This study will consider the implementation of a brief cognitive behaviour therapy for psychosis (CBTp) intervention. Methods Mental health clinicians were asked to complete a NPT-based questionnaire on the implementation of a brief CBTp intervention. All clinicians had experience of either working with the target client group or were able to deliver psychological therapies. In total, 201 clinicians completed the questionnaire. Results The results of the exploratory factor analysis found partial support for the NPT model, as three of the NPT factors were extracted: (1) coherence, (2) cognitive participation, and (3) reflexive monitoring. We did not find support for the fourth NPT factor (collective action). All scales showed strong internal consistency. Secondary analysis of these factors showed clinicians to generally support the implementation of the brief CBTp intervention. Conclusions This study provides strong evidence for the validity of the three NPT factors extracted. Further research is needed to determine whether participants’ level of seniority moderates factor extraction, whether this factor structure can be generalised to other healthcare settings, and whether pre-implementation attitudes predict actual implementation outcomes

Predicting service utilization with the child and adolescent functional assessment scale in a sample of youths with serious emotional disturbance served by center for mental health services-funded demonstrations

This study investigated level of restrictiveness of living arrangements and number of days in out-of-family care at six months postintake, based on the Child and Adolescent Functional Assessment Scale (CAFAS), the Child Behavior Checklist (CBCL), gender, age, and level of family income at intake. It was composed of youths who met the criteria for serious emotional disturbance (SED) and were for the most part living in families that are described as socioeconomically disadvantaged. A multinomial logit model was used in the analysis of level of restrictiveness of living arrangements, and an ordinary least squares (OLS) regression model was conducted on number of days in out-of-family care. The CAFAS score at intake was found to be a significant predictor of service utilization between intake and six months and was a more consistent predictor than the CBCL. Results suggest that the CAFAS can be used to match service needs with resource allocation and to monitor performance-based outcome indicators.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45770/1/11414_2005_Article_BF02287803.pd

Comparison of glottic views and intubation times in the supine and 25 degree back-up positions

Background: We explored whether positioning patients in a 25° back-up sniffing position improved glottic views and ease of intubation. Methods: In the first part of the study, patients were intubated in the standard supine sniffing position. In the second part, the back of the operating table was raised 25° from the horizontal by flexion of the torso at the hips while maintaining the sniffing position. The best view obtained during laryngoscopy was assessed using the Cormack and Lehane classification and Percentage of Glottic Opening (POGO) score. The number of attempts at both laryngoscopy and tracheal intubation, together with the use of ancillary equipment and manoeuvres were recorded. The ease of intubation was indirectly assessed by recording the time interval between beginning of laryngoscopy and insertion of the tracheal tube. Results: Seven hundred eighty one unselected surgical patients scheduled for non-emergency surgery were included. In the back-up position, ancillary laryngeal manoeuvres, which included cricoid pressure, backwards upwards rightward pressure and external laryngeal manipulation, were required less frequently (19.6 % versus 24. 6 %, p = 0.004). The time from beginning of laryngoscopy to insertion of the tracheal tube was 14 % shorter (median time 24 versus 28 s, p = 0.031) in the back-up position. There was no significant difference in glottic views. Conclusions: The 25° back-up position improved the ease of intubation as judged by the need for fewer ancillary manoeuvres and shorter time for intubation. Trial registration: ClinicalTrials.gov Identifier: NCT02934347 registered retrospectively on 14th Oct 2016

Unknotting night-time muscle cramp: a survey of patient experience, help-seeking behaviour and perceived treatment effectiveness

Background: Night-time calf cramping affects approximately 1 in 3 adults. The aim of this study was to explore the experience of night-time calf cramp; if and where people seek treatment advice; and perceived treatment effectiveness. Methods: 80 adults who experienced night-time calf cramp at least once per week were recruited from the Hunter region, NSW, Australia through newspaper, radio and television advertisements. All participants completed a pilot-tested survey about muscle cramp. Quantitative data were analysed with independent-sample t-tests, Chi square tests and Fisher’s tests. Qualitative data were transcribed and sorted into categories to identify themes. Results: Median recalled age of first night-time calf cramp was 50 years. Most participants recalled being awoken from sleep by cramping, and experiencing cramping of either calf muscle, calf-muscle soreness in the days following cramp and cramping during day-time. Despite current therapies, mean usual pain intensity was 66 mm on a 100 mm visual analogue scale. Participants described their cramps as being ‘unbearable’, ‘unmanageable’ and ‘cruel’. One participant stated that ‘sometimes I just wish I could cut my legs open’ and another reported ‘getting about 2h sleep a night due to cramps’. Most participants had sought advice about their night-time calf cramps from a health professional. Participants identified 49 different interventions used to prevent night-time calf cramp. Of all treatment ratings, 68% described the intervention used to prevent cramp as being ‘useless’ or of ‘a little help’. Of 14 participants who provided additional information regarding their use of quinine, eight had a current prescription of quinine for muscle cramp at the time of the survey. None had been asked by their prescribing doctor to stop using quinine. Conclusion: Night time calf cramps typically woke sufferers from sleep, affected either leg and caused ongoing pain. Most participants experienced little or no relief with current therapies used to prevent muscle cramp. Most people who were taking quinine for muscle cramp were unaware that the Australian Therapeutic Goods Administration withdrew support of quinine for muscle cramp in 2004 due to the risk of thrombocytopaenia. Case-control studies are required to identify therapeutic targets so that clinical trials can evaluate safe interventions to prevent recurrent cramp