418 research outputs found

    Phase Transitions in High Purity Zr Under Dynamic Compression

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    We present results from ramp compression experiments on high-purity Zr that show the α→ω\alpha \rightarrow \omega, ω→ÎČ\omega \rightarrow \beta, as well as reverse ÎČ→ω\beta \rightarrow \omega phase transitions. Simulations with a multi-phase equation of state and phenomenological kinetic model match the experimental wave profiles well. While the dynamic α→ω\alpha \rightarrow \omega transition occurs ∌9\sim 9 GPa above the equilibrium phase boundary, the ω→ÎČ\omega \rightarrow \beta transition occurs within 0.9~GPa of equilibrium. We estimate that the dynamic compression path intersects the equilibrium ω−ÎČ\omega - \beta line at P=29.2P= 29.2 GPa, and T=490T = 490 K. The thermodynamic path in the interior of the sample lies ∌100\sim 100 K above the isentrope at the point of the ω→ÎČ\omega \rightarrow \beta transition. Approximately half of this dissipative temperature rise is due to plastic work, and half is due to the non-equilibrium α→ω\alpha \rightarrow \omega transition. The inferred rate of the α→ω\alpha \rightarrow \omega transition is several orders of magnitude higher than that measured in dynamic diamond anvil cell (DDAC) experiments in an overlapping pressure range. We discuss a model for the influence of shear stress on the nucleation rate. The small fractional volume change ΔV/V≈0.1\Delta V/V \approx 0.1 at the α→ω\alpha \rightarrow \omega transition amplifies the effect of shear stress, and we estimate that for this case shear stress is equivalent to a pressure increase in the range of several GPa. Correcting our transition rate to a hydrostatic rate brings it approximately into line with the DDAC results, suggesting that shear stress plays a significant role in the transformation rate

    Excited Hydroxyl Outflow in the High-Mass Star-Forming Region G34.26+0.15

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    G34.26+0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hyper-compact HII regions and a prototypical cometary ultra-compact HII region. Previous high-sensitivity single dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blue-shifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at ∌2\sim 2" scales, and it is coincident with one of the bright ionized cores of the cometary HII region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultra-compact HII region.Comment: 19 pages, 6 figures. Accepted for publication in The Astrophysical Journa

    Is the Shroud of Turin in Relation to the Old Jerusalem Historical Earthquake?

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    Phillips and Hedges suggested, in the scientific magazine Nature (1989), that neutron radiation could be liable of a wrong radiocarbon dating, while proton radiation could be responsible of the Shroud body image formation. On the other hand, no plausible physical reason has been proposed so far to explain the radiation source origin, and its effects on the linen fibres. However, some recent studies, carried out by the first author and his Team at the Laboratory of Fracture Mechanics of the Politecnico di Torino, found that it is possible to generate neutron emissions from very brittle rock specimens in compression through piezonuclear fission reactions. Analogously, neutron flux increments, in correspondence to seismic activity, should be a result of the same reactions. A group of Russian scientists measured a neutron flux exceeding the background level by three orders of magnitude in correspondence to rather appreciable earthquakes (4th degree in Richter Scale). The authors consider the possibility that neutron emissions by earthquakes could have induced the image formation on Shroud linen fibres, trough thermal neutron capture by Nitrogen nuclei, and provided a wrong radiocarbon dating due to an increment in C(14,6)content. Let us consider that, although the calculated integral flux of 10^13 neutrons per square centimetre is 10 times greater than the cancer therapy dose, nevertheless it is100 times smaller than the lethal dose.Comment: 13 pages, 1 figur

    The complexities, coordination, culture and capacities that characterise the delivery of oncology services in the common areas of ambulatory settings.

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    BACKGROUND: Relatively little is understood about real-world provision of oncology care in ambulatory outpatient clinics (OPCs). This study aimed to: 1) develop an understanding of behaviours and practices inherent in the delivery of cancer services in OPC common areas by characterising the organisation and implementation of this care; and 2) identify barriers to, and facilitators of, the delivery of this care in OPC common areas. METHODS: A purpose-designed ethnographic study was employed in four public hospital OPCs. Informal field scoping activities were followed by in-situ observations, key informant interviews and document review. A view of OPCs as complex adaptive systems was used as a scaffold for the data collection and interpretation, with the intent of understanding 'work as done'. Data were analysed using an adapted "Qualitative Rapid Appraisal, Rigorous Analysis" approach. RESULTS: Field observations were conducted over 135 h, interviews over 6.5 h and documents were reviewed. Analysis found six themes. Staff working in OPCs see themselves as part of small local teams and as part of a broader multidisciplinary care team. Professional role boundaries could be unclear in practice, as duties expanded to meet demand or to stop patients "falling through the cracks." Formal care processes in OPCs were supported by relationships, social capital and informal, but invaluable, institutional expertise. Features of the clinic layout, such as the proximity of departments, affected professional interactions. Staff were aware of inter- and intra-service communication difficulties and employed strategies to minimise negative impacts on patients. We found that complexity, coordination, culture and capacity underpin the themes that characterise this care provision. CONCLUSIONS: The study advances understanding of how multidisciplinary care is delivered in ambulatory settings and the factors which promote or inhibit effective care practice. Time pressures, communication challenges and competing priorities can pose barriers to care delivery. OPC care is facilitated by: self-organisation of participants; professional acumen; institutional knowledge; social ties and relationships between and within professional groups; and commitment to patient-centred care. An understanding of the realities of 'work-as-done' may help OPCs to sustain high-quality care in the face of escalating service demand

    'Sending Dollars Shows Feeling' - Emotions and Economies in Filipino Migration

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    This paper analyses the conceptualization of gender, relationships, and emotions that underpin ‘care chains’ approaches to Filipino labour migration. In a case study of long‐distance intimacy and economic transfers in an extended Filipino family, I show how contextualizing migration within local understandings of emotion fractures expectations created by care chains accounts. This case instead reveals agency, diversity, and new forms of global subjectivity emerging through long‐distance emotional connections within the translocal field shaped by labour mobility

    Providing outpatient cancer care for CALD patients: a qualitative study

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    Objective There have been few descriptions of how outpatient cancer care is provided to patients from culturally and linguistically diverse (CALD) communities. As populations who experience disparities in cancer care access and outcomes, deeper understanding is needed to help identify those factors which can shape the receipt of multidisciplinary care in ambulatory settings. This paper reports on data collected and analysed as part of a multicentre characterisation of care in Australian public hospital cancer outpatient clinics (OPCs). Results Analysis of data from our ethnographic study of four OPCs identified three themes: “Identifying CALD patient language-related needs”; “Capacity and resources to meet CALD patient needs”, and “Making it work for CALD communities.” The care team comprises not only clinicians but also families and non-clinical staff; OPCs serve as “touchpoints” facilitating access to a range of therapeutic services. The findings highlight the potential challenges oncology professionals negotiate in providing care to CALD communities and the ways in which clinicians adapt their practices, formulate strategies and use available resources to support care delivery

    "The Great Event of the Fortnight”: Steamship Rhythms and Colonial Communication

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    This paper engages with Tim Cresswell’s ‘contellations of mobility’ in order to contribute some understanding of historical maritime rhythms. The empirical focus is upon a steamship mail service in the post-emancipation Caribbean. In examining this communications network, it is stressed that while those managing the network valorised predictable efficiency, ‘friction’ was prized by mercantile groups at the steamers’ ports of call. Thus, the different aspects of mobility signified differently across the network, and this historical case study reinforces the resonance of slowness and stoppage time. The synchronisation of steamship arrivals with sociocultural norms in the Caribbean colonies also necessitated the adaptation of mail service rhythms. Through a focus on shipping operations, this paper proposes to temper our understanding of the role of steamship technology in empire. The influence of colonies on the metropole encompassed an alteration of the rhythms of imperial circulation, and it is within the maritime arena that these realities came into sharp focus
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