Homogeneity and projective equivalence of differential equation fields

We propose definitions of homogeneity and projective equivalence for systems of ordinary differential equations of order greater than two, which allow us to generalize the concept of a spray (for systems of order two). We show that the Euler-Lagrange fields of parametric Lagrangians of order greater than one which are regular (in a natural sense that we define) form a projective equivalence class of homogeneous systems. We show further that the geodesics, or base integral curves, of projectively equivalent homogeneous differential equation fields are the same apart from orientation-preserving reparametrization; that is, homogeneous differential equation fields determine systems of paths

Creep studies on oriented thermoplastics

The enhancement of many of the mechanical properties of thermoplastics which may be achieved by orienting the molecules has been known for some time. It has been exploited in the production of textile fibres end oriented films. Molecular orientation also occurs during processes such as extrusion, moulding or forming. Here, unless carefully controlled, it may well cause a deterioration in the properties of the finished article. In view of this a systematic study on the anisotropy of the mechanical properties of thermoplastics, resulting from molecular orientation, is being carried out at present in these laboratories … [cont.]

An apparatus for the measurement of tensile creep and contraction ratios in small non-rigid specimens

An apparatus is described for precise measurement of creep properties in specimens with gauge lengths down to 1.2 cm. An extensometer has been developed which is supported independently of the specimen and exerts a load on the specimen of less than 5 grams. It can thus be used with small non-rigid specimens. The extensometer will detect strains down to 2 x 10-6. The stability is excellent. An adaptation of the system which allows simultaneous measurement of tensile strain and lateral strain during creep is also described. The apparatus was designed for the measurement of anisotropy of creep properties in oriented thermoplastics and reference to such measurements is given. It is however entirely suitable for general application to small specimens

Person-related and Treatment-related Barriers to Alcohol Treatment

Treatment underutilization by persons with alcohol use disorder is well-documented. This study examined barriers to treatment at the latter stages of the treatment-seeking process, which was conceptualized as recognizing the problem, deciding that change is necessary, deciding that professional help is required, and seeking care. All participants identified themselves as having a drinking problem that was severe enough to warrant treatment. Differences between those who had (Treatment Seekers) and those who had not (Comparison Controls) sought treatment were evaluated, including the experience of person-related (e.g., shame) and treatment-related (e.g., cost) barriers. Person-related barriers were more commonly endorsed by both groups than treatment-related barriers. Comparison Controls were more likely to endorse both types of barriers, especially the preference for handling the problem without treatment. Treatment-related barriers were less relevant than person-related barriers at the latter stage of help seeking. The significance of barriers endured after accounting for other differences, such as drinking-related negative consequences. Treatment implications are discussed

Non-invasive imaging of subsurface paint layers with optical coherence tomography

Optical coherence tomography (OCT) systems are fast scanning infrared Michelson interferometers designed for the non-invasive examination of the interiors of the eye and subsurface structures of biological tissues. OCT has recently been applied to the non-invasive examinations of the stratigraphy of paintings and museum artefacts. So far this is the only technique capable of imaging non-invasively the subsurface structure of paintings and painted objects. Unlike the traditional method of paint cross-section examination where sampling is required, the non-invasive and non-contact nature of the technique enables the examination of the paint cross-section anywhere on a painting, as there is no longer an issue with conservation ethics regarding the taking of samples from historical artefacts. A range of applications of the technique including the imaging of stratigraphy of paintings and painted artefacts, the imaging of underdrawings to the analysis of the optical properties of paint and varnish layers is presented. Future projects on the application of OCT to art conservation are discussed

Making postgraduate students and supervisors aware of the role of emotions in the PhD process

Emotions are an integral part of the PhD process. A range of emotions are common and to be expected. How do emotions affect the PhD process for both postgraduate students and their supervisors? How can we make our emotions work positively for us in the PhD process? To explore answers to these questions, three lecturers currently supervising postgraduates and three postgraduates at various stages in their doctoral studies collectively pooled their experiences. We developed an interactive workshop that was recently conducted for postgraduate students at Murdoch University and at the Australian Association for Social Research annual conference 2002. This presentation will explore the role that emotions play in the PhD process and how supervisors and postgraduates alike can benefit from reflecting on this issue. A number of practical (and humorous) tips will be provided as well as examples from others' PhD experiences. The role of emotions at the beginning, middle and end of a PhD program will be explored. The data collection and analysis phases are a time when emotions may run riot. Trepidation is especially common when fieldwork or data collection is involved, as is anger when postgraduate's views about how the world works are challenged and then sadness (and relief!) when the data collection phase is finished. We will discuss how supervisors can assist their postgraduates to make these feelings work for them. The presentation will also explore the emotions that arise from the supervisor-postgraduate partnership

Insulation bonding test system

A method and a system for testing the bonding of foam insulation attached to metal is described. The system involves the use of an impacter which has a calibrated load cell mounted on a plunger and a hammer head mounted on the end of the plunger. When the impacter strikes the insulation at a point to be tested, the load cell measures the force of the impact and the precise time interval during which the hammer head is in contact with the insulation. This information is transmitted as an electrical signal to a load cell amplifier where the signal is conditioned and then transmitted to a fast Fourier transform (FFT) analyzer. The FFT analyzer produces energy spectral density curves which are displayed on a video screen. The termination frequency of the energy spectral density curve may be compared with a predetermined empirical scale to determine whether a igh quality bond, good bond, or debond is present at the point of impact

Bayes-X: a Bayesian inference tool for the analysis of X-ray observations of galaxy clusters

We present the first public release of our Bayesian inference tool, Bayes-X, for the analysis of X-ray observations of galaxy clusters. We illustrate the use of Bayes-X by analysing a set of four simulated clusters at z=0.2-0.9 as they would be observed by a Chandra-like X-ray observatory. In both the simulations and the analysis pipeline we assume that the dark matter density follows a spherically-symmetric Navarro, Frenk and White (NFW) profile and that the gas pressure is described by a generalised NFW (GNFW) profile. We then perform four sets of analyses. By numerically exploring the joint probability distribution of the cluster parameters given simulated Chandra-like data, we show that the model and analysis technique can robustly return the simulated cluster input quantities, constrain the cluster physical parameters and reveal the degeneracies among the model parameters and cluster physical parameters. We then analyse Chandra data on the nearby cluster, A262, and derive the cluster physical profiles. To illustrate the performance of the Bayesian model selection, we also carried out analyses assuming an Einasto profile for the matter density and calculated the Bayes factor. The results of the model selection analyses for the simulated data favour the NFW model as expected. However, we find that the Einasto profile is preferred in the analysis of A262. The Bayes-X software, which is implemented in Fortran 90, is available at http://www.mrao.cam.ac.uk/facilities/software/bayesx/.Comment: 22 pages, 11 figure