183 research outputs found

    Mining metrics for buried treasure

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    The same but different: That might describe two metrics. On the surface CLASSI may show two metrics are locally equivalent, but buried beneath one may be a wealth of further structure. This was beautifully described in a paper by M.A.H. MacCallum in 1998. Here I will illustrate the effect with two flat metrics -- one describing ordinary Minkowski spacetime and the other describing a three-parameter family of Gal'tsov-Letelier-Tod spacetimes. I will dig out the beautiful hidden classical singularity structure of the latter (a structure first noticed by Tod in 1994) and then show how quantum considerations can illuminate the riches. I will then discuss how quantum structure can help us understand classical singularities and metric parameters in a variety of exact solutions mined from the Exact Solutions book.Comment: 16 pages, no figures, minor grammatical changes, submitted to Proceedings of the Malcolm@60 Conference (London, July 2004

    Scaling anomaly in cosmic string background

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    We show that the classical scale symmetry of a particle moving in cosmic string background is broken upon inequivalent quantization of the classical system, leading to anomaly. The consequence of this anomaly is the formation of single bound state in the coupling interval \gamma\in(-1,1). The inequivalent quantization is characterized by a 1-parameter family of self-adjoint extension parameter \omega. It has been conjectured that the formation of loosely bound state in cosmic string background may lead to the so called anomalous scattering cross section for the particles, which is usually seen in molecular physics.Comment: 4 pages,1 figur

    CareTrack Aged: the appropriateness of care delivered to Australians living in residential aged care facilities: a study protocol

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    INTRODUCTION:The aged population is increasing rapidly across the world and this is expected to continue. People living in residential aged care facilities (RACFs) represent amongst the sickest and frailest cohort of the aged population, with a high prevalence of chronic conditions and complex comorbidities. Given the vulnerability of RACF residents and the demands on the system, there is a need to determine the extent that care is delivered in line with best practice ('appropriate care') in RACFs. There is also a recognition that systems should provide care that optimises quality of life (QoL), which includes support for physical and psychological well-being, independence, social relationships, personal beliefs and a caring external environment. The aims of CareTrack Aged are to develop sets of indicators for appropriate care and processes of care for commonly managed conditions, and then assess the appropriateness of care delivered and QoL of residents in RACFs in Australia. METHODS AND ANALYSIS:We will extract recommendations from clinical practice guidelines and, using expert review, convert these into sets of indicators for 15 common conditions and processes of care for people living in RACFs. We will recruit RACFs in three Australian states, and residents within these RACFs, using a stratified multistage sampling method. Experienced nurses, trained in the CareTrack Aged methods ('surveyors'), will review care records of recruited residents within a 1-month period in 2019 and 2020, and assess the care documented against the indicators of appropriate care. Surveyors will concurrently assess residents' QoL using validated questionnaires. ETHICS AND DISSEMINATION:The study has been reviewed and approved by the Human Research Ethics Committee of Macquarie University (5201800386). The research findings will be published in international and national journals and disseminated through conferences and presentations to interested stakeholder groups, including consumers, national agencies, healthcare professionals, policymakers and researchers.Peter D Hibbert, Louise K Wiles, Ian D Cameron, Alison Kitson, Richard L Reed, Andrew Georgiou ... et al

    Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

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    We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

    Animal models for COVID-19

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    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the aetiological agent of coronavirus disease 2019 (COVID-19), an emerging respiratory infection caused by the introduction of a novel coronavirus into humans late in 2019 (first detected in Hubei province, China). As of 18 September 2020, SARS-CoV-2 has spread to 215 countries, has infected more than 30 million people and has caused more than 950,000 deaths. As humans do not have pre-existing immunity to SARS-CoV-2, there is an urgent need to develop therapeutic agents and vaccines to mitigate the current pandemic and to prevent the re-emergence of COVID-19. In February 2020, the World Health Organization (WHO) assembled an international panel to develop animal models for COVID-19 to accelerate the testing of vaccines and therapeutic agents. Here we summarize the findings to date and provides relevant information for preclinical testing of vaccine candidates and therapeutic agents for COVID-19
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