Statistical comparison of clouds and star clusters

The extent to which the projected distribution of stars in a cluster is due to a large-scale radial gradient, and the extent to which it is due to fractal sub-structure, can be quantified -- statistically -- using the measure ${\cal Q} = \bar{m}/\bar{s}$. Here $\bar{m}$ is the normalized mean edge length of its minimum spanning tree (i.e. the shortest network of edges connecting all stars in the cluster) and $\bar{s}$ is the correlation length (i.e. the normalized mean separation between all pairs of stars). We show how ${\cal Q}$ can be indirectly applied to grey-scale images by decomposing the image into a distribution of points from which $\bar{m}$ and $\bar{s}$ can be calculated. This provides a powerful technique for comparing the distribution of dense gas in a molecular cloud with the distribution of the stars that condense out of it. We illustrate the application of this technique by comparing ${\cal Q}$ values from simulated clouds and star clusters.Comment: Accepted 2010 October 27. Received 2010 October 25; in original form 2010 September 13 The paper contains 7 figures and 2 table

Planning for the End of Life for People with Dementia - Part 2

This publication is a discussion about additional end-of-life options which may become legally available at some time in the future, i.e., assisted death (usually called euthanasia or assisted suicide). Alzheimer's Australia is not advocating that such options become available and takes a neutral position about them. However, there is a need for an informed debate on the issues, given that well-conducted research indicates that a significant proportion of the community supports making such options available.Some people believe that they should have the right to make decisions about their own bodies and about the way they die; in other casespeople see the current legal and medical options as inadequate. While Australia was the first place in the world to pass legislation allowing both euthanasia and physician-assisted suicide (i.e. the Northern Territory Rights of the Terminally Ill Act (1995)), that legislation was overturned by the Commonwealth's Euthanasia Laws Act (1997) and at present these options are illegal throughout Australia. However, given that assisted dying Bills are regularly presented to state/territory parliaments in Australia it is possible that, at some time in the future, legislation will be passed that allows such options. It is therefore important for the arguments for and against assisted dying to be understood and for open debate to be encouraged. We hope that the information provided in this document will contribute to that debate.Section 2 of Part 2 asks: What is doctor-assisted dying*? and identifies what isand what is not euthanasia. In Section 3, arguments for and against doctor-assisted dying are provided and in Section 4 some issues which relate specifically to assisted dying for people with dementia are considered

Viruses and drinking water

There is no evidence to indicate that there is a risk of acquiring a virus infection through the consumption of properly treated drinking water, provided the integrity of the distribution system is maintained and there is no post-treatment contamination. The consumption of inadequately treated, untreated or post-treatment contaminated water is, however, associated with a risk of hepatitis A, hepatitis E and viral gastroenteritis. The use of the standard bacterial indicators for water monitoring provides an adequate safeguard against viral contamination

Lifting matroid divisors on tropical curves

Tropical geometry gives a bound on the ranks of divisors on curves in terms of the combinatorics of the dual graph of a degeneration. We show that for a family of examples, curves realizing this bound might only exist over certain characteristics or over certain fields of definition. Our examples also apply to the theory of metrized complexes and weighted graphs. These examples arise by relating the lifting problem to matroid realizability. We also give a proof of Mn\"ev universality with explicit bounds on the size of the matroid, which may be of independent interest.Comment: 27 pages, 7 figures, final submitted version: several proofs clarified and various minor change

Researching difficult-to-reach and vulnerable groups using grounded theory methods

This case study describes a research project that used grounded theory methods. The aim of this research was to develop new knowledge about how parents experience their offspring’s problematic drug use. Unstructured interviews were used during the data-gathering phase of the research, and data were collected in two distinct periods. The case study is divided into four sections. Section 1 outlines the approaches used to find and recruit research participants. This section also describes how I engaged with the participants in ways that I hoped would encourage participation and build a rapport. Section 2 outlines significant life events that some of the research participants experienced and the importance of working sensitively with vulnerable participants and how this can contribute to your research endeavor. This section also highlights some of the ethical issues that need to be negotiated during the fieldwork phase of a research project. Section 3 describes the methods used during the data collection and data analysis stages of the project. The processes involved are broken down with each stage being explained. The process is presented as a linear model; however, in grounded theory, it is possible to move back and forth between stages, and the benefits this may bring are explained in this section. Finally, Section 4 offers a reflexive account of the research journey. Reflexivity is an important aspect of qualitative research and this section highlights why it is important

Respite and repair: how mothers of incarcerated long-term problematic drug users make prison work for them

This article considers the way a group of mothers experienced the incarceration of their problematic drug using offspring. The offspring had been imprisoned for a range of offences including theft, burglary and drug dealing with the root cause of their incarceration being connected to their long-term problematic drug use. Much of the existing literature on imprisonment identifies the separation of offenders from their family as a source of strain both for the offender and the family, with separation being one of the pains of imprisonment described in the literature. However, in contrast to this, the evidence gathered during the research that this article is based upon, highlights how the mothers of problematic drug users sought to use the periods of time their offspring were in prison as respite from their difficult and time-consuming caring responsibilities. Furthermore, the time their offspring were incarcerated was used to repair fractured relationships