Manly Hospital

Abstract This tutorial reviews the mathematical foundations of single-antenna radio polarimetry with the aim of fostering a conceptual understanding of the relationships between a physical description of signal propagation (gain, delay, reflection, down-conversion, etc.), the corresponding transformations of the electric field vector, and the equivalent operations on the Stokes parameters. The adopted framework is based on the work of Britton and Hamaker and applied to analyze the signal path described by Hamaker et al. with additional corrections for phase convention and reflection. Some objective criteria for selecting a model of the instrumental response are introduced and discussed, along with some practical guidelines that facilitate polarimetric calibration. Further relevant background material and lengthier mathematical proofs are included in the appendix, which introduces the vector, matrix, and tensor notation and concepts of linear algebra used in this work. The appendix also reviews some of the basics of analog and digital signal processing that are relevant to radio astronomy, and discusses some numerical instabilities that arise when modeling observations.

The long-term stability of coral reef islands and associated reef top sedimentary landforms requires the delivery of sediment from the forereef, but the rates and pathways of sediment delivery to these systems remain unclear. Spurs and grooves (SAGs) are ubiquitous geomorphic features fringing coral reefs, characterised by shore-normal coral ridges (spurs) separated by channels (grooves) with either bare substrate or a relatively low sediment infill. SAGs dissipate wave energy, facilitate offshore sediment transport and enhance nutrient exchange. Here we present the first evidence that SAG can also act as channels for onshore transport of rubble during high-energy events, contributing to maintaining reef islands and rubble-based ecosystems.

Common signal-processing approximations produce artefacts when timing pulsars in relativistic binary systems, especially edge-on systems with tight orbits, such as the Double Pulsar. In this paper, we use extensive simulations to explore various patterns that arise from the inaccuracies of approximations made when correcting dispersion and Shapiro delay. In a relativistic binary, the velocity of the pulsar projected onto the line of sight varies significantly on short timescales, causing rapid changes in the apparent pulsar spin frequency, which is used to convert dispersive delays to pulsar rotational phase shifts. A well-known example of the consequences of this effect is the artificial variation of dispersion measure (DM) with binary phase, first observed in the Double Pulsar 20 years ago. We show that ignoring the Doppler shift of the spin frequency when computing the dispersive phase shift exactly reproduces the shape and magnitude of the reported DM variations. We also simulate and study two additional effects of much smaller magnitude, which are caused by the assumption that the spin frequency used to correct dispersion is constant over the duration of the sub-integration and over the observed bandwidth. We show that failure to account for these two effects leads to orbital phase-dependent dispersive smearing that leads to apparent orbital DM variations. The functional form of the variation depends on the orbital eccentricity. In addition, we find that a polynomial approximation of the timing model is unable to accurately describe the Shapiro delay of edge-on systems with orbits of less than four hours, which poses problems for the measurements of timing parameters, most notably the Shapiro delay. This will be a potential issue for sensitive facilities such as the Five-hundred-meter Aperture Spherical Telescope (FAST) and the forthcoming Square Kilometre Array (SKA); therefore, a more accurate phase predictor is indispensable.

Existing investigations on palliative care of AYAs have indicated poor end of life support for the young patients and their families. These reports are linked to young adults having a higher survival rate in thus have limited dedicated resources for end-of-life care (Grinyer & Barbarachild, 2011). Management of this group requires interdisciplinary clinical involvement to work with the heterogeneity of the patient groups due to the need of addressing the complex medical concerns that coincide with psychosocial developmental phases and existential distress (Wein, Pery, & Zer 2010). The Manly Adolescent and Young Adult Hospice (AYAH) was developed by NSW Health to provide specialised support to AYAs between the ages 16–30 with life limiting illnesses. This case review is on Layla** and her family, a 30-year-old female with head and neck cancer and complex psychosocial background who underwent palliative care during her stay at the AYAH. This review explores the importance of multidisciplinary involvement and support at end-of-life care.MethodologyThis case review was conceptualised using a Schema Therapy framework to uncover family patterns of coping were playing out within a hospice setting. By analysing the schema chemistry (Safran & Segal, 1990), the Clinical Psychologist was able to identify processes by which an individual’s behaviour can ‘pull’ others into a familiar pattern of interaction. In turn, creating formulations for key family members and how they interact with each other during period stress allowed for identification of gaps in providing psychosocial care at the AYAH for both family members and staff.Impact on practiceAs Layla’s physical condition deteriorated, family distress was palpable, especially from Layla’s mother, Madeline**, which impacted the family and AYAH Team dynamic. Madeline’s interaction with the treating team paralleled themes of early experiences of unmet emotional needs within her personal life. Madeline’s observation of her daughter’s deterioration triggers her schema of emotional deprivation, the expectation that one’s desire for emotional support will not be adequately met by others. To be able to support the family and the AYAH staff, the following was identified by the clinical psychologist: 1) the need for psychoeducation and ‘pre-brief’ to allow for a united front across staff, 2) regular family sessions and independent psychological support for individual family members, and 3) opportunities for staff supervision throughout Layla’s end-of-life care.DiscussionThis case illustrates how psychological models are present within AYA palliative care. Lack of family support can detrimentally impact team functioning if family psychological needs are not met. Through supporting Madeline and her family, the treating team was able to review what were considered difficult behaviours as representations of grief. It challenged the team to reframe how family interaction can impact responses to challenging engagement styles as a cry for help.ReferencesGrinyer A, Barbarachild Z. Teenage and young adult palliative and end of life care service evaluation. [Service evaluation, University of Lancaster].2011; https://eprints.lancs.ac.uk/id/eprint/49234/1/tcteolc_report.pdfWein S, Pery S, Zer A. Role of palliative care in adolescent and young adult oncology. Journal of Clinical Oncology 2010;28(32):4819–4824.** pseudonyms

None of the established formulae for breakwater armour stone stability, Hudson (1958) or van der Meer (1987), explicitly account for the water depth at the toe of the structure. More recently, Hughes (2004), Melby and Hughes (2004), Melby and Kobayashi (2011) have developed equations for stability and runup utilising the concept of wave momentum flux which explicitly accounts for the water depth of the wave probe(s) in close proximity to the structure. The equations are adapted to three forms; namely (1) linear, (2) extended-linear and (3) non-linear. In the paper linearity is assessed by using the Ursell number at each probe depth. Also, due to the placement of probes at various depths in MHL’s 2D wave flume it is possible to correlate the linearity of the wave measurement for the same time series and subsequently test the appropriateness of the momentum flux equation applied for assessment of stability and runup. The stability and runup data from 43 2D physical model tests where stability was previously assessed using van der Meer’s and Hudson’s equations are assessed using the momentum flux equations and an evaluation of the results has been made. It was found that the estimation of notional permeability and selection of the use of the plunging or surging formulae was critical to obtaining a closer match between measurement and prediction. The equations were also utilised in conjunction with numerical models to evaluate the armour size for repair of two breakwater heads in South Camden Haven and Bellambi. The maximum momentum flux equations were found to perform satisfactorily at these locations where the Ursell numbers were found to be high and the waves non-linear.

Cryobiopsy is an emerging tool in the diagnosis of peripheral pulmonary lesions (PPL) and becoming an important tool in the toolbox. Anecdotally the data on cryobiopsy use in the lung was extrapolated from the use of transbronchial cryobiopsy (TBCB) in Interstitial Lung disease (ILD). Similar to ILD data, cryobiopsy in PPL also provided larger tissue compared to forceps biopsies. Yet, unlike TBCB in ILD, the safety profile for cryobiopsy in PPL seems much more favourable, yet the number of publications on cryobiopsy in PPL remains sparse. Some PPL, both malignant and non-malignant are considered to be of a high bleeding risk due to vascularity of the tumour and/or inflammation of the blood vessels and surrounding tissue. The use of cryobiopsy and the risk of bleeding in this type of PPL have not been described. This paper describes four patients with PPL, undergoing cryobiopsy with radial EBUS for suspected lung cancer, and later diagnosed to have a PPL, deemed to be of a high bleeding risk. The use of cryobiopsy with radial ultrasonic examination for the vasculature of the PPL, bronchial blocker use, and airway protection as well as an expert team preserved the safety of the procedure.

ABSTRACT A pulsar dynamic spectrum is an inline digital hologram of the interstellar medium; it encodes information on the propagation paths by which signals have travelled from source to telescope. To decode the hologram, it is necessary to ‘retrieve’ the phases of the wavefield from intensity measurements, which directly gauge only the field modulus, by imposing additional constraints on the model. We present a new method for phase retrieval in the context of pulsar spectroscopy. Our method makes use of the Fast Iterative Shrinkage Thresholding Algorithm (FISTA) to obtain sparse models of the wavefield in a hierarchical approach with progressively increasing depth. Once the tail of the noise distribution is reached the hierarchy terminates with a final, unregularized optimization. The result is a fully dense model of the complex wavefield that permits the discovery of faint signals by appropriate averaging. We illustrate the performance of our method on synthetic test cases and on real data. Our algorithm, which we call H-FISTA, is implemented in the python programming language and is freely available.

Rapidly rotating neutron stars are promising sources for existing and upcoming gravitational-wave interferometers. While relatively dim, these systems are expected to emit continuously, allowing for signal to be accumulated through persistent monitoring over year-long timescales. If, at some point during the observational window, the source comes to lie behind a dense collection of stars, transient gravitational lensing may occur. Such events, though rare, would modulate the waveform, induce phase drifts, and ultimately affect parameter inferences concerning the nuclear equation of state and/or magnetic field structure of the neutron star. Importantly, the radiation wavelength will typically exceed the Schwarzschild radius of the individual perturbers in this scenario, implying that (micro)lensing occurs in the diffractive regime, where geometric optics does not apply. In this paper, we make use of numerical tools that borrow from Picard–Lefschetz theory to efficiently evaluate the relevant Fresnel–Kirchhoff integrals for n ≳ 102 microlenses. Modulated strain profiles are constructed both in general and for particular neutron star trajectories relative to some simulated macrolenses.

ABSTRACT We discovered rapid intra-day variability in radio source PMN J1726+0639 at GHz frequencies, during a survey to search for such variability with the Australia Telescope Compact Array. Follow-up observations were conducted over 2 yr and revealed a clear, repeating annual cycle in the rate, or characteristic time-scale, of variability, showing that the observed variations can be attributed to scintillations from interstellar plasma inhomogeneities. The strong annual cycle includes an apparent ‘standstill’ in April and another in September. We fit kinematic models to the data, allowing for finite anisotropy in the scintillation pattern. The cycle implies a very high degree of anisotropy, with an axial ratio of at least 13:1, and the fit is consistent with a purely one-dimensional scintillation pattern. The position angle of the anisotropy, and the transverse velocity component are tightly constrained. The parameters are inconsistent with expectations from a previously proposed model of scattering associated with plasma filaments radially oriented around hot stars. We note that evidence for a foreground interstellar cloud causing anomalous Ca ii absorption towards the nearby star Rasalhague (α Oph) has been previously reported, and we speculate that the interstellar scintillation of PMN J1726+0639 might be associated with this nearby cloud.