New Constraints on the Energetics, Progenitor Mass, and Age of the Supernova Remnant G292.0+1.8 Containing PSR J1124-5916

We present spatially resolved spectroscopy of the supernova remnant (SNR) G292.0+1.8 with the Chandra X-ray observatory. This SNR contains the 135 ms pulsar, J1124-5916. We apply non-equilibrium ionization (NEI) models to the data. By comparing the derived abundances with those predicted from nucleosynthesis models, we estimate a progenitor mass of 30-40 solar masses. We also derive the intrinsic parameters of the supernova explosion such as its energy, the age of the SNR, the blast wave velocity, and the swept-up mass. In the Sedov interpretation, our estimated SNR age of 2,600 years is close to the pulsar's characteristic age of 2,900 years. This confirms the pulsar/SNR association and relaxes the need for the pulsar to have a non-canonical value for the braking index, a large period at birth or a large transverse velocity. We discuss the properties of the pulsar wind nebula (PWN) in the light of the Kennel and Coroniti model and estimate the pulsar wind magnetization parameter. We also report the first evidence for steepening of the power law spectral index with increasing radius from the pulsar.Comment: 5 pages, 3 figures. To appear in ApJL, Feb 1 2003 (submitted Oct 9 2002, accepted Dec 19 2002

MeV Emission from Pulsar Wind Nebulae: Understanding Extreme Particle Acceleration in Highly Relativistic Outflows

The Earth is constantly bombarded from outer space by energetic particles. Where and how these "cosmic rays" are produced is poorly understood, with various particle types and energies likely originating from different sources. Particularly mysterious is the source of high-energy e+/- produced in our Galaxy, especially those responsible for both the high fraction of e+ in the GeV cosmic ray lepton spectrum and the e+/- and observed excess of microwaves and gamma-rays detected towards the Galactic center and bulge. While these particles could be evidence for exotic forms of dark matter, they might also be produced by "normal" astrophysical sources such as pulsars the strongly magnetized, rapidly rotating neutron stars whose rotational energy powers an ultra-relativistic outflow (commonly referred to as a "pulsar wind") whose interaction with the surrounding medium creates a pulsar wind nebula .While the detection of TeV emission from numerous PWNe strongly suggest they contain e+/- with PeV or higher energies, how and to what energies these particles are produced is unknown, let alone their dependence on the properties of the pulsar, pulsar wind, and surrounding medium. A major reason for this uncertainty is the lack of information concerning their MeV properties, since the synchrotron emission from the highest energy e+/- peaks in this waveband. Only by combining the MeV spectrum of PWNe measured by proposed missions with that obtained at lower (primarily radio and X-ray) and higher (TeV) photon energies by current and hopefully future facilities is it possible to measure the full spectrum of e+/- in these sources. The resultant insights into the underlying acceleration mechanism would significantly impact many areas of astrophysics from indirect searches for dark matter to the origin of cosmic rays to the physics of relativistic outflows observed from active galactic nuclei, gamma-ray bursts, and some gravitational wave events

Sensitivity of the human circadian system to short wavelength (420 nm) light

The circadian and neurobehavioral effects of light are primarily mediated by a retinal ganglion cell photoreceptor in the mammalian eye containing the photopigment, melanopsin. Nine action spectrum studies using rodents, monkeys, and human for these responses indicate peak sensitivities in the blue region of the visible spectrum ranging from 459 nm to 484 nm, with some disagreement in short wavelength sensitivity of the spectrum. The aim of this work was to quantify the sensitivity of human volunteers to monochromatic 420 nm light for plasma melatonin suppression. Adult female (N=14) and male (N=12) subjects participated in two studies, each employing a within-subjects design. In a fluence-response study, subjects (N=8) were tested with eight light irradiances at 420 nm ranging over a four log unit photon density range of 1010 to 1014 photons/cm2/sec and one dark exposure control night. In the other study, subjects (N=18) completed an experiment comparing melatonin suppression with equal photon doses (1.21 x 1013 photons/cm2/sec) of 420 nm and 460 nm monochromatic light and a dark exposure control night. The first study demonstrated a clear fluence-response relationship between 420 nm light and melatonin suppression (p\u3c0.001) with a half-saturation constant of 2.74 x 1011 photons/cm2/sec. The second study showed that 460 nm light is significantly stronger than 420 nm light for suppressing melatonin (p\u3c0.04). Together, the results clarify the visible short wavelength sensitivity of the human melatonin suppression action spectrum. This basic physiological finding may be useful for optimizing lighting for therapeutic and other applications

What palliative care can do for motor neurone disease patients and their families

Appropriate palliative care is essential for people with motor neurone disease, a progressive and irreversible neurological condition that can have distressing symptoms in its later stages. David Oliver and Samar Aoun detail how and when the specialist palliative care team should get involved

Stochastic Resonance of Ensemble Neurons for Transient Spike Trains: A Wavelet Analysis

By using the wavelet transformation (WT), we have analyzed the response of an ensemble of $N$ (=1, 10, 100 and 500) Hodgkin-Huxley (HH) neurons to {\it transient} $M$-pulse spike trains ($M=1-3$) with independent Gaussian noises. The cross-correlation between the input and output signals is expressed in terms of the WT expansion coefficients. The signal-to-noise ratio (SNR) is evaluated by using the {\it denoising} method within the WT, by which the noise contribution is extracted from output signals. Although the response of a single (N=1) neuron to sub-threshold transient signals with noises is quite unreliable, the transmission fidelity assessed by the cross-correlation and SNR is shown to be much improved by increasing the value of $N$: a population of neurons play an indispensable role in the stochastic resonance (SR) for transient spike inputs. It is also shown that in a large-scale ensemble, the transmission fidelity for supra-threshold transient spikes is not significantly degraded by a weak noise which is responsible to SR for sub-threshold inputs.Comment: 20 pages, 4 figure

Key features of palliative care service delivery to Indigenous peoples in Australia, New Zealand, Canada and the United States: A comprehensive review

Background: Indigenous peoples in developed countries have reduced life expectancies, particularly from chronic diseases. The lack of access to and take up of palliative care services of Indigenous peoples is an ongoing concern. Objectives: To examine and learn from published studies on provision of culturally safe palliative care service delivery to Indigenous people in Australia, New Zealand (NZ), Canada and the United States of America (USA); and to compare Indigenous peoples’ preferences, needs, opportunities and barriers to palliative care. Methods: A comprehensive search of multiple databases was undertaken. Articles were included if they were published in English from 2000 onwards and related to palliative care service delivery for Indigenous populations; papers could use quantitative or qualitative approaches. Common themes were identified using thematic synthesis. Studies were evaluated using Daly’s hierarchy of evidence-for-practice in qualitative research. Results: Of 522 articles screened, 39 were eligible for inclusion. Despite diversity in Indigenous peoples’ experiences across countries, some commonalities were noted in the preferences for palliative care of Indigenous people: to die close to or at home; involvement of family; and the integration of cultural practices. Barriers identified included inaccessibility, affordability, lack of awareness of services, perceptions of palliative care, and inappropriate services. Identified models attempted to address these gaps by adopting the following strategies: community engagement and ownership; flexibility in approach; continuing education and training; a whole-of-service approach; and local partnerships among multiple agencies. Better engagement with Indigenous clients, an increase in number of palliative care patients, improved outcomes, and understanding about palliative care by patients and their families were identified as positive achievements. Conclusions: The results provide a comprehensive overview of identified effective practices with regards to palliative care delivered to Indigenous populations to guide future program developments in this field. Further research is required to explore the palliative care needs and experiences of Indigenous people living in urban areas

Identifying and addressing the support needs of family caregivers of people with motor neurone disease using the Carer Support Needs Assessment Tool

Family caregivers of people with motor neurone disease (MND) experience adverse health outcomes as a result of their caregiving experience. This may be alleviated if their support needs are identified and addressed in a systematic and timely manner. The objective of the present study was to assess the feasibility and relevance of the Carer Support Needs Assessment Tool (CSNAT) in home-based care during the period of caregiving from the perspectives of the family caregivers of people with MND and their service providers. The study was conducted during 2014 in Western Australia. Some 30 family caregivers and 4 care advisors participated in trialling the CSNAT intervention, which involved two visits from care advisors (6–8 weeks apart) to identify and address support needs. The feedback from family caregivers was obtained via telephone interviews and that of care advisors via a self-administered questionnaire. A total of 24 caregivers completed the study (80% completion rate) and identified the highest support priorities as “knowing what to expect in the future,” “knowing who to contact if concerned,” and “equipment to help care.” The majority found that this assessment process adequately addressed their needs and gave them a sense of validation, reassurance, and empowerment. Care advisors advocated the CSNAT approach as an improvement over standard practice, allowing them to more clearly assess needs, to offer a more structured follow-up, and to focus on the caregiver and family. The CSNAT approach for identifying and addressing family caregivers' support needs was found to be relevant and feasible by MND family caregivers and care advisors. The tool provided a formal structure to facilitate discussions with family caregivers and thus enable needs to be addressed. Such discussions can also inform an evidence base for the ongoing development of services, ensuring that new and improved services are designed to meet the explicit needs of the family caregivers of people with a motor neurone disease

An assets-based approach to bereavement care

A survey of bereaved clients of four funeral providers in Australia confirms a public health model predicting that over half the group would demonstrate low risk of complicated grief, another third moderate risk, while a small minority would meet the criteria for prolonged grief disorder. The survey also shows differing patterns of need and sources of support for each of the three groups. While our findings support targeting the bereavement care provided by health services, our primary interest is in the care received by most bereaved people. Some is provided in the community through the everyday activities of healthcare professionals. Most comes from a range of people already involved in the everyday lives of those recently bereaved. We contend that the most effective way to provide bereavement care is to support these ‘everyday assets’, ensuring that their care is recognised, appreciated, and not disrupted by over-reach from professional services