Widespread iron-rich conditions in the mid-Proterozoic ocean.

The chemical composition of the ocean changed markedly with the oxidation of the Earth's surface, and this process has profoundly influenced the evolutionary and ecological history of life. The early Earth was characterized by a reducing ocean-atmosphere system, whereas the Phanerozoic eon (less than 542 million years ago) is known for a stable and oxygenated biosphere conducive to the radiation of animals. The redox characteristics of surface environments during Earth's middle age (1.8-1 billion years ago) are less well known, but it is generally assumed that the mid-Proterozoic was home to a globally sulphidic (euxinic) deep ocean. Here we present iron data from a suite of mid-Proterozoic marine mudstones. Contrary to the popular model, our results indicate that ferruginous (anoxic and Fe(2+)-rich) conditions were both spatially and temporally extensive across diverse palaeogeographic settings in the mid-Proterozoic ocean, inviting new models for the temporal distribution of iron formations and the availability of bioessential trace elements during a critical window for eukaryotic evolution.

Comparison of MMPI-2 and PAI validity indicators to detect feigned depression and PTSD symptom reporting.

The purpose of this study was to compare the clinical utility of PAI and MMPI-2 validity indicators to detect exaggeration of psychological symptoms. Participants were 49 (75.5% female) Australian university students who completed the MMPI-2 and PAI under one of three conditions: Control [i.e., honest responding (n=20)], Feign Post Traumatic Stress Disorder [PTSD (n=15)], or Feign Depression (n=14). Participants instructed to feign depression or feign PTSD had significantly higher scores on the majority of MMPI-2 and PAI validity indicators compared with controls. The Meyers Validity Index, the Obvious-Subtle index, and the Response Bias Scale were the most accurate MMPI-2 validity indicators. Diagnostic-specific MMPI-2 validity indicators, such as the Infrequency-PSTD scales and Malingered Depression scale, were not effective at detecting participants instructed to feign those conditions. For the PAI, the most accurate validity indicator was the MAL index; however, the detection rate using this validity indicator was modest at best. The MMPI-2 validity indicators were clearly superior to those on the PAI at identifying feigned versus honest responding in this sample.

The Cerebrovascular Attitudes and Beliefs Scale (CABS-R): the factor structure and psychometric properties of a tool for assessing stroke-related health beliefs.

BACKGROUND: Worldwide stroke is serious problem and one that necessitates continued efforts towards prevention. The health belief model suggests that improvements in prevention will follow from incorporating strategies that change beliefs, but this approach relies on the availability of tools for measuring such change. The Cerebrovascular Attitudes and Beliefs Scale (CABS-R) was developed to meet this need. PURPOSE: The purpose of this study was to investigate the psychometric properties of the CABS-R. METHOD: In 2007, 126 Brisbane residents aged 50 years and older completed the CABS-R. One month later, 70 participants completed the CABS-R again. Internal consistency, test-retest, and exploratory factor analyses were performed on subscales completed by >60 participants. RESULTS: Analyses showed that the CABS-R has moderate-to-good internal consistency and that scores are relatively stable over time. A four-factor solution was identified, suggesting that the CABS-R validly assesses stroke susceptibility and seriousness and the perceived benefits of and barriers to exercise and weight loss for stroke prevention. CONCLUSION: This study shows that the CABS-R is useful to gauge changes in stroke beliefs over time. Consistent with the model, a four factor solution was found. The CABS-R may be a useful inclusion in future stroke prevention programs.

Developing a stroke intervention program: what do people at risk of stroke want?

OBJECTIVE: There is currently little research examining what individuals who are at risk of a stroke want from an invention program. In order to increase the usefulness of such programs, qualitative research methods were used explore invention design issues such as factors affecting accessibility of programs and preferred health information sources. METHODS: Thirty people, each with at least one stroke risk factor, participated in one of eight focus groups. RESULTS: Broad support was indicated for our proposed intervention. Participants perceived the value and likely success of such a program enhanced if it: (a) was integrated with, and supported by, other respected health services; (b) included social components (particularly important to women); (c) produced long-term benefits; and (d) included information that was personally relevant and practical in terms of implementing change. Three reasons emerged for continuing stroke education campaigns as a component of intervention programs; these were: (a) a lack of awareness among some participants of gaps in their stroke knowledge; (b) participants' explicit requests for specific rather than general information; and (c) the apparent failure of some participants to self-identify as at risk. CONCLUSION: This study yielded a number of important design considerations that should be taken into account when developing stroke intervention programs. PRACTICE IMPLICATIONS: We discuss ways of maximising the personal relevance of stroke prevention information along theoretically important dimensions, and consumers' recommendations for the design and delivery of stroke intervention programs.

The nature and predictors of stroke knowledge amongst at risk elderly persons in Brisbane, Australia.

PURPOSE: The aim of the study was to investigate the nature, extent, and predictors of stroke knowledge amongst people at risk of stroke. METHOD: A total of 273 questionnaires were distributed to three types of sites in metropolitan Brisbane (retirement villages, senior citizens and bowls clubs), and this strategy yielded a response rate of 37%. Of the surveys returned, 75 were retained in this study on the basis that: (a) participants met our criteria for being at risk of stroke (i.e., they reported one or more modifiable stroke risk factor, such as hypertension), and (b) they returned a completed Stroke Knowledge Test (SKT). RESULTS: Descriptive analyses revealed the overall level of stroke knowledge in this group was fair (approximately 50% of SKT items answered correctly, on average). SKT performance trends showed that participants did not have misconceptions about stroke but that more than 50% of the sample did not know the answer to seven out of 20 SKT items. Some overlap was identified regarding the issues about which participants in this and other previously researched groups admit they lack knowledge, such as the extent of increased stroke risk associated with smoking; however, the number of knowledge gaps identified in this sample was almost double that reported previously amongst stroke survivors and the general community. Analyses undertaken to explore determinants of stroke knowledge revealed age and education but not risk factor variables as significant predictors. CONCLUSION: Overall, findings suggest that it is presently difficult to predict an individual's understanding of stroke and that there is a need to increase stroke education, especially if this can address issues that people at risk of stroke admit they do not understand.

A whiff of oxygen before the great oxidation event?

High-resolution chemostratigraphy reveals an episode of enrichment of the redox-sensitive transition metals molybdenum and rhenium in the late Archean Mount McRae Shale in Western Australia. Correlations with organic carbon indicate that these metals were derived from contemporaneous seawater. Rhenium/osmium geochronology demonstrates that the enrichment is a primary sedimentary feature dating to 2501 +/- 8 million years ago (Ma). Molybdenum and rhenium were probably supplied to Archean oceans by oxidative weathering of crustal sulfide minerals. These findings point to the presence of small amounts of O2 in the environment more than 50 million years before the start of the Great Oxidation Event.