Dynamic Radio-Frequency Transverse Susceptibility in Magnetic Nanoparticle Systems

A novel resonant method based on a tunnel-diode oscillator (TDO) is used to study the dynamic transverse susceptibility in a Fe nanoparticle system. The magnetic system consists of an aggregate of nanometer-size core (Au)-shell (Fe) structure, synthesized by reverse micelle methods. Static and dynamic magnetization measurements carried out in order to characterize the system reveal a superparamagnetic behavior at high temperature. The field-dependent transverse susceptibility at radio-frequencies (RF), for different temperatures reveals distinct peak structure at characteristics fields (H_k, H_c) which changes with temperature. It is proposed that relaxation processes could explain the influence of the temperature on the field dependence of the transverse susceptibility on the MI.Comment: 3 pages, 2-column, 3 figures, To be published in J. Appl. Phys. 2000 (44th Annual MMM proceedings

Past lives, present values: historic cultural values in the South-West Forests of Western Australia

The purpose of this thesis is to examine the processes surrounding the assessment of places of cultural significance in Australia, and the extent to which they are achieving some of their key objectives.In the 1970s, Australia challenged the conventions of many other countries by developing a methodology for heritage assessment that aimed at identifying all the qualities that make a place significant. This contrasted with traditional practices that focussed on architectural style, design or historic associations. The Australian paradigm identifies four key evaluative criteria against which to assess the evidence about a place: aesthetic, historic, scientific and social value. This systematic, criterion based approach is now nationally regarded as representing best practice and has been adopted in all state heritage legislation. Internationally, several countries have developed codes of practice substantially on the basis of the Australian model.One consequence of the widespread acceptance of the principles used in Australia is a lack of investigation into their successful application. The methodology has come to function as a ‘primary frame’, a way of thinking that is so widely accepted it is applied without question. The concern with any primary frame is that those working within its parameters can become ‘frame blind’ and fail to recognise any disjunction between the frame’s objectives and the outcomes it achieves. One of the aims of this thesis is to draw attention to the presence and dominant nature of this primary frame and encourage greater critical reflection on the professional practice of cultural heritage.The research program undertaken for this thesis focuses on the particular issue of how the primary frame allows for the identification of cultural heritage values held by past communities. In examining this subject it addresses several key questions: Which places did historic communities value? Can such places be assessed in terms of contemporary heritage values as set out by the primary frame? What other forms of assessment may be valid? To what extent do places identified by today’s society as having heritage values correlate to those valued by historic communities? What implications does the identification of places valued by historic communities have for contemporary land management agencies? Are there other forms of assessment that could be developed to uncover historic community places and values?In addressing these questions, this thesis challenges many of the conventions that have developed around the current assessment methodology; conventions that work to undermine the holistic objective of the primary frame. The study does not, however, seek to develop an alternative model for heritage assessment and the approaches it uses are consistent with the primary frame. Nevertheless, the approaches may be confronting to many practitioners.The research program focussed on the physically and temporally discrete historic community living in what is now the Shire of Augusta-Margaret River in Western Australia between 1832 and 1880. From the extensive collection of letters, journals and diaries written by settlers held in local archives, places that were significant to the historic community were identified. Omissions were then identified by comparing these to places identified on other heritage lists.The findings demonstrate the extent to which the primary frame is being reframed through conventions and unofficial practices, and the degree to which this is overlooked, despite being inconsistent with the broad objectives of the primary frame. Some places that were significant to the historic community have been identified as important, but there is little acknowledgement in these assessments of past cultural associations. Other places have not been identified because they no longer have the same degree of significance that was accorded to them by the historic community.This thesis concludes that the potential for the primary frame to result in more holistic heritage assessments has yet to be realised, and that the assessment process is being constrained by conventions and reframing. In order to effect change, the evaluative criteria need to be more rigorously and expansively applied.In line with the regulations of Curtin University, this thesis is presented as a series of eight papers published in refereed publications. They are supported by four chapters, which introduce the topic, provide a theoretical context, explain the methodological approach and draw together the conclusions of the research. Each paper also has a brief introduction. Together, the papers and supporting material form the thesis

Lifetime Measurement of the 8s Level in Francium

We measure the lifetime of the 8s level on a magneto-optically trapped sample of ^{210}Fr atoms with time-correlated single-photon counting. The 7P_{1/2} state serves as the resonant intermediate level for two-photon excitation of the 8s level completed with a 1300 nm laser. Analysis of the fluorescence decay through the the 7P_{3/2} level gives 53.30 +- 0.44 ns for the 8s level lifetime.Comment: 4 pages, 4 figure

Short gamma-ray bursts within 200 Mpc

We present a systematic search for short-duration gamma-ray bursts (GRBs) in the local Universe based on 14 yr of observations with the Neil Gehrels Swift Observatory. We cross-correlate the GRB positions with the GLADE catalogue of nearby galaxies, and find no event at a distance ≲100 Mpc and four plausible candidates in the range 100 Mpc ≲ D ≲ 200 Mpc. Although affected by low statistics, this number is higher than the one expected for chance alignments to random galaxies, and possibly suggests a physical association between these bursts and nearby galaxies. By assuming a local origin, we use these events to constrain the range of properties for X-ray counterparts of neutron star mergers. Optical upper limits place tight constraints on the onset of a blue kilonova, and imply either low masses (⁠≲10−3M⊙⁠) of lanthanide-poor ejecta or unfavorable orientations (θ_(obs) ≳ 30 deg). Finally, we derive that the all-sky rate of detectable short GRBs within 200 Mpc is 1.3^(+1.7)_(−0.8) yr⁻¹ (68 per cent confidence interval), and discuss the implications for the GRB outflow structure. If these candidates are instead of cosmological origin, we set a upper limit of ≲2.0 yr⁻¹ (90 per cent confidence interval) to the rate of nearby events detectable with operating gamma-ray observatories, such as Swift and Fermi

Dimensional Reduction, Hard Thermal Loops and the Renormalization Group

We study the realization of dimensional reduction and the validity of the hard thermal loop expansion for lambda phi^4 theory at finite temperature, using an environmentally friendly finite-temperature renormalization group with a fiducial temperature as flow parameter. The one-loop renormalization group allows for a consistent description of the system at low and high temperatures, and in particular of the phase transition. The main results are that dimensional reduction applies, apart from a range of temperatures around the phase transition, at high temperatures (compared to the zero temperature mass) only for sufficiently small coupling constants, while the HTL expansion is valid below (and rather far from) the phase transition, and, again, at high temperatures only in the case of sufficiently small coupling constants. We emphasize that close to the critical temperature, physics is completely dominated by thermal fluctuations that are not resummed in the hard thermal loop approach and where universal quantities are independent of the parameters of the fundamental four-dimensional theory.Comment: 20 pages, 13 eps figures, uses epsfig and pstrick

Women’s experiences of personalised support for asthma care during pregnancy: A systematic review of the literature

Abstract Background Asthma and pregnancy are both sources of anxiety for women. Although there has been a focus on physiological management of asthma and pregnancy, there has been little research on the impact that personalised support can have on asthma care during pregnancy. This systematic review and narrative synthesis of the literature set out to answer the question ‘What are women’s experiences of asthma care, its management and education, during pregnancy?’ Methods This systematic review was carried out using accepted methodology from the York Centre for Reviews and Dissemination. Electronic database searches were conducted using PsycInfo, CINAHL, MedLine, Google Scholar and the Cochrane Library, using the combination search terms: ‘Asthma’ AND ‘Pregnancy’ AND ‘Care’ AND (‘Education OR Information OR Experience’). Hand searching of journals and searches for grey literature were also undertaken. Independent quality appraisal by the three authors took place using the criteria detailed by Kmet et al. (Standard Quality Assessment Criteria for Evaluating Primary Research Papers from a Variety of Fields, 2004). Results All papers scoring in excess of 60% were deemed to be of adequate quality for inclusion, of which there were five: two qualitative designs and three quantitative designs. The designs were too methodologically heterogeneous to permit statistical meta-analysis so narrative review and synthesis was undertaken. Despite an embryonic evidence bases, it is reasonable to conclude that personalised care has beneficial outcomes for pregnant asthmatic women. Conclusions Larger randomised controlled trials investigating personalised care are required to build an evidence base which can establish the efficacy of such interventions

The Físchlár digital video system: a digital library of broadcast TV programmes

Físchlár is a system for recording, indexing, browsing and playback of broadcast TV programmes which has been operational on our University campus for almost 18 months. In this paper we give a brief overview of how the system operates, how TV programmes are organised for browse/playback and a short report on the system usage by over 900 users in our University