Magnetic anisotropy of asbestos fibres

Original article can be found at : http://jap.aip.org/jap/ Copyright American Institute of PhysicsThe anisotropy of magnetic susceptibility of single asbestos fibers is measured. The alignment of both chrysotile and crocidolite fibers in magnetic fields is found to be due to the anisotropy. The average measured anisotropy of volume susceptibility is 0.40×10−6 for chrysotile and 83×10−6 for crocidolite. Fiber shape effects are estimated to contribute, on average, about 10% and 6%, respectively, to the total anisotropy of the two types of fiber. There is no evidence of significant permanent magnetic moments. The magnitude of the observed alignment makes the effect potentially useful in real-time detection of airborne asbestos fibers. The experimental technique developed in the study can be used for measuring the anisotropy of small particles of well-defined shape. High sensitivity of the technique permits the measurement of torques lower than 10−21 Nm on particles down to picogram mass.Peer reviewe

E-BOSS: an Extensive stellar BOw Shock Survey. I: Methods and First Catalogue

Context: Bow shocks are produced by many astrophysical objects where shock waves are present. Stellar bow shocks, generated by runaway stars, have been previously detected in small numbers and well-studied. Along with progress in model development and improvements in observing instruments, our knowledge of the emission produced by these objects and its origin can now be more clearly understood. Aims: We produce a stellar bow-shock catalogue by applying uniform search criteria and a systematic search process. This catalogue is a starting point for statistical studies, to help us address fundamental questions such as, for instance, the conditions under wich a stellar bow shock is detectable. Methods: By using the newest infrared data releases, we carried out a search for bow shocks produced by early-type runaway stars. We first explored whether a set of known IRAS bow shock candidates are visible in the most recently available IR data, which has much higher resolution and sensitivity. We then carried out a selection of runaway stars from the latest, large runaway catalogue available. In this first release, we focused on OB stars and searched for bow-shaped features in the vicinity of these stars. Results: We provide a bow-shock candidate survey that gathers a total of 28 members which we call the Extensive stellar BOw Shock Survey (E-BOSS). We derive the main bow-shock parameters, and present some preliminary statistical results on the detected objects. Conclusions: Our analysis of the initial sample and the newly detected objects yields a bow-shock detectability around OB stars of $\sim$ 10 per cent. The detections do not seem to depend particularly on either stellar mass, age or position. The extension of the E-BOSS sample, with upcoming IR data, and by considering, for example, other spectral types as well, will allow us to perform a more detailed study of the findings.Comment: A&A accepted (25-NOV-2011), 15 pages, 4 tables, 11 figure

DiapixUK: task materials for the elicitation of multiple spontaneous speech dialogs

The renewed focus of attention on investigating spontaneous speech samples in speech and language research has increased the need for recordings of speech in interactive settings. The DiapixUK task is a new and extended set of picture materials based on the Diapix task by Van Engen et al. (2010) where two people are recorded while conversing to solve a ‘spot the difference’ task. The new task materials allow for multiple recordings of the same speaker pairs due to a larger set of picture pairs which have a number of tested features: equal difficulty across all twelve picture pairs, no learning effect of completing more than one picture task and balanced contributions from both speakers. The new materials also provide extra flexibility making them useful in a wide range of research projects; they are multi-layered electronic images that can be adapted to suit different research needs. This paper presents details of the development of the DiapixUK materials along with data taken from a large corpus of spontaneous speech which demonstrate its new features. Current and potential applications of the task are also discussed

A cross-sectional survey of prevalence and correlates of suicidal ideation and suicide attempts among prisoners in New South Wales, Australia

<p>Abstract</p> <p>Background</p> <p>We aimed to estimate the prevalence of suicidal ideation and suicide attempt among prisoners in New South Wales, Australia; and, among prisoners reporting suicidal ideation, to identify factors associated with suicide attempt.</p> <p>Methods</p> <p>A cross-sectional design was used. Participants were a random, stratified sample of 996 inmates who completed a telephone survey. The estimated population prevalence of suicidal ideation and suicide attempt were calculated and differences by sex and Aboriginality were tested using <it>χ</it>2 tests. Correlates of suicidal ideation and suicide attempt were tested using logistic regression.</p> <p>Results</p> <p>One-third of inmates reported lifetime suicidal ideation and one-fifth had attempted suicide. Women and Aboriginal participants were significantly more likely than men and non-Aboriginal participants, respectively, to report attempting suicide. Correlates of suicidal ideation included violent offending, traumatic brain injury, depression, self-harm, and psychiatric hospitalisation. Univariate correlates of suicide attempt among ideators were childhood out-of-home care, parental incarceration and psychiatric hospitalization; however, none of these remained significant in a multivariate model.</p> <p>Conclusions</p> <p>Suicidal ideation and attempts are highly prevalent among prisoners compared to the general community. Assessment of suicide risk is a critical task for mental health clinicians in prisons. Attention should be given to ensuring assessments are gender- and culturally sensitive. Indicators of mental illness may not be accurate predictors of suicide attempt. Indicators of childhood trauma appear to be particularly relevant to risk of suicide attempt among prisoners and should be given attention as part of risk assessments.</p

Ecosystem Resilience and Threshold Response in the Galápagos Coastal Zone

Background: The Intergovernmental Panel on Climate Change (IPCC) provides a conservative estimate on rates of sea-level rise of 3.8 mm yr⁻¹ at the end of the 21st century, which may have a detrimental effect on ecologically important mangrove ecosystems. Understanding factors influencing the long-term resilience of these communities is critical but poorly understood. We investigate ecological resilience in a coastal mangrove community from the Galápagos Islands over the last 2700 years using three research questions: What are the 'fast and slow' processes operating in the coastal zone? Is there evidence for a threshold response? How can the past inform us about the resilience of the modern system?Methodology/Principal Findings: Palaeoecological methods (AMS radiocarbon dating, stable carbon isotopes (δ13C)) were used to reconstruct sedimentation rates and ecological change over the past 2,700 years at Diablas lagoon, Isabela, Galápagos. Bulk geochemical analysis was also used to determine local environmental changes, and salinity was reconstructed using a diatom transfer function. Changes in relative sea level (RSL) were estimated using a glacio-isostatic adjustment model. Non-linear behaviour was observed in the Diablas mangrove ecosystem as it responded to increased salinities following exposure to tidal inundations. A negative feedback was observed which enabled the mangrove canopy to accrete vertically, but disturbances may have opened up the canopy and contributed to an erosion of resilience over time. A combination of drier climatic conditions and a slight fall in RSL then resulted in a threshold response, from a mangrove community to a microbial mat.Conclusions/Significance: Palaeoecological records can provide important information on the nature of non-linear behaviour by identifying thresholds within ecological systems, and in outlining responses to 'fast and slow' environmental change between alternative stable states. This study highlights the need to incorporate a long-term ecological perspective when designing strategies for maximizing coastal resilience.</p