Static solutions from the point of view of comparison geometry

We analyze (the harmonic map representation of) static solutions of the Einstein Equations in dimension three from the point of view of comparison geometry. We find simple monotonic quantities capturing sharply the influence of the Lapse function on the focussing of geodesics. This allows, in particular, a sharp estimation of the Laplacian of the distance function to a given (hyper)-surface. We apply the technique to asymptotically flat solutions with regular and connected horizons and, after a detailed analysis of the distance function to the horizon, we recover the Penrose inequality and the uniqueness of the Schwarzschild solution. The proof of this last result does not require proving conformal flatness at any intermediate step.Comment: 41 page

Care for chronic illness in Australian general practice – focus groups of chronic disease self-help groups over 10 years: implications for chronic care systems reforms

Background: Chronic disease is a major global challenge. However, chronic illness and its care, when intruding into everyday life, has received less attention in Asia Pacific countries, including Australia, who are in the process of transitioning to chronic disease orientated health systems. Aim: The study aims to examine experiences of chronic illness before and after the introduction of Australian Medicare incentives for longer consultations and structured health assessments in general practice. Methods: Self-help groups around the conditions of diabetes, epilepsy, asthma and cancer identified key informants to participate in 4 disease specific focus groups. Audio taped transcripts of the focus groups were coded using grounded theory methodology. Key themes and lesser themes identified using a process of saturation until the study questions on needs and experiences of care were addressed. Thematic comparisons were made across the 2002/3 and 1992/3 focus groups. Findings: At times of chronic illness, there was need to find and then ensure access to 'the right GP'. The 'right GP or specialist' committed to an in-depth relationship of trust, personal rapport and understanding together with clinical and therapeutic competence. The 'right GP', the main specialist, the community nurse and the pharmacist were key providers, whose success depended on interprofessional communication. The need to trust and rely on care providers was balanced by the need for self-efficacy 'to be in control of disease and treatment' and 'to be your own case manager'. Changes in Medicare appeared to have little penetration into everyday perceptions of chronic illness burden or time and quality of GP care. Inequity of health system support for different disease groupings emerged. Diabetes, asthma and certain cancers, like breast cancer, had greater support, despite common experiences of disease burden, and a need for research and support programs. Conclusion: Core themes around chronic illness experience and care needs remained consistent over the 10 year period. Reforms did not appear to alleviate the burden of chronic illness across disease groups, yet some were more privileged than others. Thus in the future, chronic care reforms should build from greater understanding of the needs of people with chronic illness

Inverse Fourier transform technique of measuring averaged absorption cross section in the reverberation chamber and Monte Carlo study of its uncertainty

The averaged absorption cross section (ACS) of a lossy object characterises its ability to capture power from diffused electromagnetic waves. The averaged ACS is very important in many EMC research areas such as indoor wireless channel modelling and human safety exposure study. The measurement of averaged ACS in a reverberation chamber can be achieved by measuring the rate of power loss in the time domain, however this technique requires dense frequency sampling for taking the inverse Fourier transform, which is very time consuming. A new scenario which accelerates the measurement speed is presented in this paper. It combines the technique of non-linear curve fitting to the power delay profile, segmented frequency sweeping and continuous mode stirring. The scenario was validated by measuring the averaged ACS of a hollow plastic sphere filled with deionized water in an EMC reverberation chamber. Measurement results showed a good accordance with the simulations and the measurement uncertainty was studied numerically with the Monte Carlo method

The cloud-in-cloud problem for non-Gaussian density fields

The cloud-in-cloud problem is studied in the context of the extension to non-Gaussian density fields of the Press-Schechter approach for the calculation of the mass function. As an example of a non-Gaussian probability distribution functions (PDFs) we consider the Chi-square, with various degrees of freedom. We generate density fields in cubic boxes with periodic boundary conditions and then determine the number of points considered collapsed at each scale through an hierarchy of smoothing windows. We find that the mass function we obtain differs from that predicted using the Extended Press-Schechter formalism, particularly for low values of $\sigma$ and for those PDFs most distinct from a Gaussian.Comment: 5 pages, LaTex using mn.sty, matches published version, results for the Inverted Chi-square distribution withdraw

A Computational Comparison of Optimization Methods for the Golomb Ruler Problem

The Golomb ruler problem is defined as follows: Given a positive integer n, locate n marks on a ruler such that the distance between any two distinct pair of marks are different from each other and the total length of the ruler is minimized. The Golomb ruler problem has applications in information theory, astronomy and communications, and it can be seen as a challenge for combinatorial optimization algorithms. Although constructing high quality rulers is well-studied, proving optimality is a far more challenging task. In this paper, we provide a computational comparison of different optimization paradigms, each using a different model (linear integer, constraint programming and quadratic integer) to certify that a given Golomb ruler is optimal. We propose several enhancements to improve the computational performance of each method by exploring bound tightening, valid inequalities, cutting planes and branching strategies. We conclude that a certain quadratic integer programming model solved through a Benders decomposition and strengthened by two types of valid inequalities performs the best in terms of solution time for small-sized Golomb ruler problem instances. On the other hand, a constraint programming model improved by range reduction and a particular branching strategy could have more potential to solve larger size instances due to its promising parallelization features

Efficient Determination of Reverberation Chamber Time Constant

Determination of the rate of energy loss in a reverberation chamber is fundamental to many different measurements such as absorption cross-section, antenna efficiency, radiated power, and shielding effectiveness. Determination of the energy decay time-constant in the time-domain by linear fitting the power delay profile, rather than using the frequency-domain quality factor, has the advantage of being independent of the radiation efficiency of antennas used in the measurement. However, determination of chamber time constant by linear regression suffers from several practical problems, including a requirement for long measurement times. Here we present a new nonlinear curve fitting technique that can extract the time-constant with typically 60% fewer samples of the chamber transfer function for the same measurement uncertainty, which enables faster measurement of chamber time constant by sampling fewer chamber transfer function, and allows for more robust automated data post-processing. Nonlinear curve fitting could have economic benefits for test-houses, and also enables accurate broadband measurements on humans in about ten minutes for microwave exposure and medical applications. The accuracy of the nonlinear method is demonstrated by measuring the absorption cross-section of several test objects of known properties. The measurement uncertainty of the method is verified using Monte Carlo methods

Beef Quality Assurance from Farm to Fork: Development of a Pilot Program in Farm to Table Food Safety

The goal of the project described here was to develop an interdisciplinary 3-day food safety training program. Course material for this program included content focused on food safety issues at the pre-harvest (farm, ranch, feedlot), post-harvest (slaughter and fabrication), and consumer (foodservice, retail, home) level. A pre-and post-test were given to each participant to assess the impact of this training program. Pre-test scores averaged 62%, while post-test scores averaged 87%. The 3-day interdisciplinary food safety course was effective at increasing constituent knowledge of food safety issues related to beef production and consumption from farm to fork

Must naive realists be relationalists?

Relationalism maintains that perceptual experience involves, as part of its nature, a distinctive kind of conscious perceptual relation between a subject of experience and an object of experience. Together with the claim that perceptual experience is presentational, relationalism is widely believed to be a core aspect of the naive realist outlook on perception. This is a mistake. I argue that naive realism about perception can be upheld without a commitment to relationalism

Infrared Diagnostics for the Extended 12 micron Sample of Seyferts

We present an analysis of Spitzer IRS spectroscopy of 83 active galaxies from the extended 12 micron sample. We find rank correlations between several tracers of star formation which suggest that (1) the PAH feature is a reliable tracer of star formation, (2) there is a significant contribution to the heating of the cool dust by stars, (3) the H$_2$ emission is also primarily excited by star formation. The 55-90 vs. 20-30 spectral index plot is also a diagnostic of the relative contribution of Starburst to AGN. We see there is a large change in spectral index across the sample. Thus, the contribution to the IR spectrum from the AGN and starburst components can be comparable in magnitude but the relative contribution also varies widely across the sample. We find rank correlations between several AGN tracers. We search for correlations between AGN and Starburst tracers and we conclude that the AGN and Starburst tracers are not correlated. This is consistent with our conclusion that the relative strength of the AGN and Starburst components varies widely across the sample. Thus, there is no simple link between AGN fueling and Black Hole Growth and star formation in these galaxies. The distribution of Sil 10 micron and 18 micron strengths is consistent with the clumpy torus models of Sirocky et al. We find a rank correlation between the [NeV] 14 micron line and the 6.7 micron continuum which may be due to an extended component of hot dust. The Sy 2s with a Hidden Broad Line Region (HBLR) have a higher ratio of AGN to Starburst contribution to the SED than Sy 2s without an HBLR. This may contribute to the detection of the HBLR in polarized light. The Sy 2s with an HBLR are more similar to the Sy 1s than they are to the Sy 2s without an HBLR