Infrared spectra of Mg-SiO smokes : comparison with analytical electron microscopy studies

An important component of current models for interstellar and circumstellar evolution is the infrared (IR)spectral data collected from stellar outflows around oxygen-rich stars and from the general interstellar medium [1]. IR spectra from these celestial bodies are usually interpreted as showing the general properties of sub-micron sized silicate grains [2]. Two major features at 10 and 20 microns are reasonably attributed to amorphous olivine or pyroxene (e.g. Mg2Si04 or MgSi03) on the basis of comparisons with natural standards and vapor condensed silicates [3-6]. In an attempt to define crystallisation rates for spectrally amorphous condensates, Nuth and Donn [5] annealed experimentally produced amorphous magnesium silicate smokes at 1000K. On analysing these smokes at various annealing times, Nuth and Donn [5] showed that changes in crystallinity measured by bulk X-ray diffraction occured at longer annealing times (days) than changes measured by IR spectra (a few hours). To better define the onset of crystallinity in these magnesium silicates, we have examined each annealed product using a JEOL 1OOCX analytical electron microscope (AEM). In addition, the development of chemical diversity with annealing has been monitored using energy dispersive spectroscopy of individual grains from areas <20nm in diameter. Furthermore, the crystallisation kinetics of these smokes under ambient, room temperature conditions have been examined using bulk and fourier transform infrared (FTIR)spectra

Featured Piece

This year the General Editors decided to create a feature piece to show our appreciation for the History Department. We selected four professors from the faculty to answer a question about history: what figure/event/idea inspires your interest in history? Reading their responses helped give us insight into the thoughts of these brilliant minds and further help us understand their passion for the subject we all share a common love and interest in. We hope that you enjoy reading their responses as much as we did. The four members of the faculty we spoke with are Dr. Timothy Shannon, Dr. Ian Isherwood, Dr. Jill Titus, and Dr. Scott Hancock

Chronology of Terrestrial Den Use by Polar Bears in Western Hudson Bay as Indicated by Tree Growth Anomalies

In a large polar bear denning area inland from the coast of western Hudson Bay south of Churchill, Manitoba, previous denning activity was determined by examining tree growth anomalies in the black spruce (Picea mariana) around and above den sites. A concentrated sample of dens was examined at each of three lakes, and 14 additional den sites were sampled individually on nine lakes and streams, for a total of 31 den sites. Trees sampled at these den sites ranged in age from 46 to 236 years (n = 83, mean = 136, SE ± 95.66). Some individual den sites dated back at least 200 years. Although some dens had been used for up to 29 years, most were used for only 12 years or less, presumably until melting permafrost caused their collapse. Half of the dens were reused two years after their initial use, but the probability of den reuse declined in subsequent years to about 0.25 after 10 years. During the 20th century, coincident with a reduction in hunting during 1920-53 and the subsequent abandonment of York Factory, there appears to have been an increase in den activity and an accompanying change in the pattern of denning activity. The rate of disturbance to the trees at dens correlated significantly to the number of polar bear hides traded at York Factory over the 1840-1935 period (r = 0.654; p &lt; 0.005). During 1850-99, denning activity was greater at points more distant from the trading post at York Factory. In 1900-53, there was an overall increase in denning activity, which was greatest in denning areas nearer to York Factory (r = -0.872; p &lt; 0.01). In 1954-93, the increase in denning activity continued, but varied with distance from the coast (r = -0.724; p &lt; 0.05). Mark-recapture studies undertaken from 1970 to 2000 confirm that female polar bears in the western Hudson Bay population have a long-term fidelity to this specific area for maternity denning, and from this study it is evident that the population has used this denning area for several hundred years at least.Dans une vaste zone où sont établies des tanières d'ours polaires située en retrait de la côte de la baie d'Hudson occidentale au sud de Churchill (Manitoba), on a déterminé l'activité liée aux tanières en examinant les anomalies de croissance de l'épinette noire (Picea mariana) autour et au-dessus des sites de tanières. On a étudié un échantillon concentré de tanières à chacun de trois lacs, et 14 lieux de mise bas supplémentaires ont fait l'objet d'un échantillonnage individuel à neuf lacs et cours d'eau, pour un total de 31 lieux de mise bas. L'âge des arbres échantillonnés à ces endroits allait de 46 à 236 ans (n = 83, moyenne = 136, écart-type ± 95,66). Quelques lieux de mise bas individuels remontaient à au moins 200 ans. Bien que certaines tanières aient été utilisées aussi longtemps que 29 ans, la plupart ne l'avaient été que pendant 12 ans ou moins, probablement jusqu'à ce que la fonte du pergélisol provoque leur effondrement. La moitié des tanières étaient réutilisées deux ans après leur occupation initiale, mais, par la suite, la probabilité de réutilisation diminuait à environ 0,25 après 10 ans. Au cours du XXe siècle, parallèlement à une réduction de la chasse qui dura de 1920 à 1953 et à l'abandon ultérieur de York Factory, il semble y avoir eu une augmentation de l'activité liée aux tanières, accompagnée d'un changement dans le régime de l'activité liée à la mise bas. Le taux de perturbation des arbres situés près des tanières était fortement corrélé au nombre de peaux d'ours polaires échangées à York Factory entre 1840 et 1935 (r = 0,654; p &lt; 0,005). De 1850 à 1899, l'activité liée à la mise bas était plus grande aux endroits plus éloignés du poste de traite de York Factory. De 1900 à 1953, il y a eu une augmentation générale de l'activité liée à la mise bas, plus marquée dans les zones de mise bas les plus proches de York Factory (r = -0,872; p &lt; 0,01). De 1954 à 1993, l'augmentation dans l'activité liée à la mise bas s'est poursuivie, tout en variant avec l'éloignement de la côte (r = -0,724; p &lt;0,05). Les études de marquage-recapture entreprises de 1970 à 2000 confirment que les ourses polaires de la population de la baie d'Hudson occidentale manifestent une fidélité à long terme à l'égard de cette zone spécifique pour y établir leur tanière de mise bas, et il est évident à partir de cette étude que la population utilise cette zone de mise bas depuis au moins plusieurs siècles

Deliberate clinical inertia: Using meta-cognition to improve decision-making

Deliberate clinical inertia is the art of doing nothing as a positive response. To be able to apply this concept, individual clinicians need to specifically focus on their clinical decision-making. The skill of solving problems and making optimal clinical decisions requires more attention in medical training and should play a more prominent part of the medical curriculum. This paper provides suggestions on how this may be achieved. Strategies to mitigate common biases are outlined, with an emphasis on reversing a 'more is better' culture towards more temperate, critical thinking. To incorporate such an approach in medical curricula and in clinical practice, institutional endorsement and support is required

First do no harm in responding to incidental imaging findings

You order a computed tomography pulmonary angiogram (CTPA) for a patient with suspected pulmonary thromboembolism. The radiology report states that no pulmonary thromboembolism is seen but notes an unrelated lung nodule. What should you do with this incidental finding, or “incidentaloma”

Using new and innovative technologies to assess clinical stage in early intervention youth mental health services: Evaluation study

Background: Globally there is increasing recognition that new strategies are required to reduce disability due to common mental health problems. As 75% of mental health and substance use disorders emerge during the teenage or early adulthood years, these strategies need to be readily accessible to young people. When considering how to provide such services at scale, new and innovative technologies show promise in augmenting traditional clinic-based services. Objective: The aim of this study was to test new and innovative technologies to assess clinical stage in early intervention youth mental health services using a prototypic online system known as the Mental Health eClinic (MHeC). Methods: The online assessment within the MHeC was compared directly against traditional clinician assessment within 2 Sydney-based youth-specific mental health services (headspace Camperdown and headspace Campbelltown). A total of 204 young people were recruited to the study. Eligible participants completed both face-to-face and online assessments, which were randomly allocated and counterbalanced at a 1-to-3 ratio. These assessments were (1) a traditional 45- to 60-minute headspace face-to-face assessment performed by a Youth Access Clinician and (2) an approximate 60-minute online assessment (including a self-report Web-based survey, immediate dashboard of results, and a video visit with a clinician). All assessments were completed within a 2-week timeframe from initial presentation. Results: Of the 72 participants who completed the study, 71% (51/72) were female and the mean age was 20.4 years (aged 16 to 25 years); 68% (49/72) of participants were recruited from headspace Camperdown and the remaining 32% (23/72) from headspace Campbelltown. Interrater agreement of participants’ stage, as determined after face-to-face assessment or online assessment, demonstrated fair agreement (kappa=.39, P\u3c.001) with concordance in 68% of cases (49/72). Among the discordant cases, those who were allocated to a higher stage by online raters were more likely to report a past history of mental health disorders (P=.001), previous suicide planning (P=.002), and current cannabis misuse (P=.03) compared to those allocated to a lower stage. Conclusions: The MHeC presents a new and innovative method for determining key clinical service parameters. It has the potential to be adapted to varied settings in which young people are connected with traditional clinical services and assist in providing the right care at the right tim