The Dynamics of Radiative Shock Waves: Linear and Nonlinear Evolution

The stability properties of one-dimensional radiative shocks with a power-law cooling function of the form $\Lambda \propto \rho^2T^\alpha$ are the main subject of this work. The linear analysis originally presented by Chevalier & Imamura, is thoroughfully reviewed for several values of the cooling index $\alpha$ and higher overtone modes. Consistently with previous results, it is shown that the spectrum of the linear operator consists in a series of modes with increasing oscillation frequency. For each mode a critical value of the cooling index, $\alpha_\textrm{c}$, can be defined so that modes with $\alpha < \alpha_\textrm{c}$ are unstable, while modes with $\alpha > \alpha_\textrm{c}$ are stable. The perturbative analysis is complemented by several numerical simulations to follow the time-dependent evolution of the system for different values of $\alpha$. Particular attention is given to the comparison between numerical and analytical results (during the early phases of the evolution) and to the role played by different boundary conditions. It is shown that an appropriate treatment of the lower boundary yields results that closely follow the predicted linear behavior. During the nonlinear regime, the shock oscillations saturate at a finite amplitude and tend to a quasi-periodic cycle. The modes of oscillations during this phase do not necessarily coincide with those predicted by linear theory, but may be accounted for by mode-mode coupling.Comment: 33 pages, 12 figures, accepted for publication on the Astrophysical Journa

FUSE Observations of the Dwarf Nova SW UMa During Quiescence

We present spectroscopic observations of the short-period cataclysmic variable SW Ursa Majoris, obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite while the system was in quiescence. The data include the resonance lines of O VI at 1031.91 and 1037.61 A. These lines are present in emission, and they exhibit both narrow (~ 150 km/s) and broad (~ 2000 km/s) components. The narrow O VI emission lines exhibit unusual double-peaked and redshifted profiles. We attribute the source of this emission to a cooling flow onto the surface of the white dwarf primary. The broad O VI emission most likely originates in a thin, photoionized surface layer on the accretion disk. We searched for emission from H_2 at 1050 and 1100 A, motivated by the expectation that the bulk of the quiescent accretion disk is in the form of cool, molecular gas. If H_2 is present, then our limits on the fluxes of the H_2 lines are consistent with the presence of a surface layer of atomic H that shields the interior of the disk. These results may indicate that accretion operates primarily in the surface layers of the disk in SW UMa. We also investigate the far-UV continuum of SW UMa and place an upper limit of 15,000 K on the effective temperature of the white dwarf.Comment: 21 Pages, 3 figures, to be published in Ap

Developing Dementia-Friendly Tourism Destinations: An Exploratory Analysis

Dementia is emerging as a global issue. Increases in life expectancy create an older population structure with accompanying health needs but also high lifestyle expectations. For example existing generations have come to expect to be able to participate in leisure and tourism activities in later life, which can be constrained by the onset of dementia. Leading healthy lifestyles and engaging in tourism activities are viewed as fundamental to remaining active and contributing to slowing the progress of dementia. This study is the first to examine the challenges and implications of the growing scale of dementia and the business opportunities this may create for destinations wishing to achieve dementia-friendly status. The paper reports results from an initial scoping study with tourism businesses in a coastal resort in the United Kingdom with such ambitions to assess the nature of the issues that arose from a series of face-to-face interviews

Optical Spectroscopy of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies

This paper discusses the optical spectroscopic properties of the IRAS 1-Jy sample of ultraluminous infrared galaxies (ULIGs). One hundred and eight of the 118 1-Jy ULIGs have been observed at dlambda = 8.3 AA resolution over the wavelength range ~4500 A -- 8900 A. These data are combined with large, previously published sets of optical spectroscopic data of lower luminosity infrared galaxies to look for systematic trends with infrared luminosity over the luminosity range L_ir ~ 10^{10.5}-10^{13} L_sun. As found in previous studies, the fraction of Seyfert galaxies among luminous infrared galaxies increases abruptly above L_ir ~ 10^{12.3} L_sun --- about 50% of the galaxies with L_ir > 10^{12.3} L_sun present Seyfert characteristics. Many of the optical and infrared spectroscopic properties of the Seyfert galaxies are consistent with the presence of a genuine active galactic nucleus (AGN). About 30% of these galaxies are Seyfert 1s with broad-line regions similar to those of optical quasars. The percentage of Seyfert 1 ULIGs increases with infrared luminosity, contrary to the predictions of the standard unification model for Seyfert galaxies. Comparisons of the broad-line luminosities of optical and obscured Seyfert 1 ULIGs with those of optically selected quasars of comparable bolometric luminosity suggest that the dominant energy source in most of these ULIGs is the same as in optical quasars, namely mass accretion onto a supermassive black hole, rather than a starburst. These results are consistent with recently published ISO, ASCA, and VLBI data. (abridged)Comment: Text and 23 figures (45 pages), Tables 1 - 6 (16 pages

Using appreciative inquiry to implement person-centred dementia care in hospital wards

The quality of care of persons with dementia in hospitals is not optimal and can be challenging. Moreover, staff may find difficulty in translating what they have learned during training into practice. This paper report the development and evaluation of a set of workshops using an Appreciative Inquiry (AI) approach to implement person-centred dementia care in two hospital wards. Staff worked collaboratively to develop a ward vision and to implement a number of action plans. Using AI approach, staff attitudes towards persons with dementia improved, inter-professional collaboration was enhanced and small changes in staff practices were noted. Dementia care in hospitals can be enhanced by empowering staff to take small but concrete actions after they engage in AI workshops, during which they are listened to and appreciated for what they can contribute

The Effects of Meditation on Perceived Stress and Related Indices of Psychological Status and Sympathetic Activation in Persons with Alzheimer\u27s Disease and Their Caregivers: A Pilot Study

Objective. To investigate the effects of an 8-week meditation program on perceived stress, sleep, mood, and related outcomes in adults with cognitive impairment and their caregivers. Methods. Community-dwelling adults with a diagnosis of mild cognitive impairment or early-stage Alzheimer’s disease, together with their live-in caregivers, were enrolled in the study. After a brief training, participants were asked to meditate for 11 minutes, twice daily for 8 weeks. Major outcomes included measures of perceived stress (Perceived Stress Scale), sleep (General Sleep Disturbance Scale), mood (Profile of Mood States), memory functioning (Memory Functioning Questionnaire), and blood pressure. Participants were assessed pre- and post-intervention. Results. Ten participants (5 of 6 dyads) completed the study. Treatment effects did not vary by participant status; analyses were thus pooled across participants. Adherence was good (meditation sessions completed/week: ). Participants demonstrated improvement in all major outcomes, including perceived stress (), mood (overall, ; depression, ), sleep (), retrospective memory function (), and blood pressure (systolic, ; diastolic, ). Conclusions. Findings of this exploratory trial suggest that an 8-week meditation program may offer an acceptable and effective intervention for reducing perceived stress and improving certain domains of sleep, mood, and memory in adults with cognitive impairment and their caregivers

The Effects of Meditation on Perceived Stress and Related Indices of Psychological Status and Sympathetic Activation in Persons with Alzheimer's Disease and Their Caregivers: A Pilot Study

Objective. To investigate the effects of an 8-week meditation program on perceived stress, sleep, mood, and related outcomes in adults with cognitive impairment and their caregivers. Methods. Community-dwelling adults with a diagnosis of mild cognitive impairment or early-stage Alzheimer's disease, together with their live-in caregivers, were enrolled in the study. After a brief training, participants were asked to meditate for 11 minutes, twice daily for 8 weeks. Major outcomes included measures of perceived stress (Perceived Stress Scale), sleep (General Sleep Disturbance Scale), mood (Profile of Mood States), memory functioning (Memory Functioning Questionnaire), and blood pressure. Participants were assessed pre- and post-intervention. Results. Ten participants (5 of 6 dyads) completed the study. Treatment effects did not vary by participant status; analyses were thus pooled across participants. Adherence was good (meditation sessions completed/week: X = 11.4 ± 1.1). Participants demonstrated improvement in all major outcomes, including perceived stress (P < 0.001), mood (overall, P = 0.07; depression, P = 0.01), sleep (P < 0.04), retrospective memory function (P = 0.04), and blood pressure (systolic, P = 0.004; diastolic, P = 0.065). Conclusions. Findings of this exploratory trial suggest that an 8-week meditation program may offer an acceptable and effective intervention for reducing perceived stress and improving certain domains of sleep, mood, and memory in adults with cognitive impairment and their caregivers