6,818 research outputs found
The effect of age on referral to and use of specialist palliative care services in adult cancer patients: a systematic review
Objective: to investigate variations in the use of specialist palliative care (SPC) services for adult cancer patients, in relation to age.Design: systematic review of studies examining use of or referral to SPC services in adult cancer patients.Search strategy and selection criteria: six electronic databases (Medline, Embase, Web of Science, HMIC, SIGLE and AgeInfo) were searched for studies published between 1966 and March 2005, and references in the articles identified were also examined. Inclusion criteria were all studies which provided data on age in relation to use of or referral to SPC. Two reviewers independently selected studies, extracted data and assessed methodological quality according to defined criteria.Main outcome measures: use of or referral to SPC services, determined from all sources of report (patient, informal carer, health care professional, health care records).Results: 14 studies were identified. All reported a statistically significant lower use of SPC among older cancer patients (65 and above or older) at a univariate level [crude odds ratios ranged from 0.33 (0.15-0.72) to 0.82 (0.80-0.82)]. However, there were important methodological weaknesses in all of the studies identified; most crucially, studies failed to consider variations in use in relation to need for SPC.Conclusions: there is some evidence that older people are less likely to be referred to, or to use, SPC. These findings require confirmation in studies using prospectively collected data which control for patient's need for SPC
Line width distributions as evidence for axisymmetry in the broad line regions of active galaxies
The nuclei of a wide class of active galaxies emit broad emission lines with
widths at half maximum (FWHM) in the range km s. This
spread of widths is not solely a consequence of the range of the luminosities
of these sources since a plot of width versus luminosity shows a large scatter.
We propose that the broad line emission region (BLR) is axially symmetric and
that this scatter in line width arises from an additional dependence on the
angle of the line of sight to the axis of the emission region. Such a relation
is natural in unified models of active nuclei which link a variety of observed
properties to viewing angle. Adopting a simple form for the line width as a
function of luminosity and angle, and convolving this with the observed
luminosity function, allows us to predict a line width distribution consistent
with the available data. Furthermore, we use the relation between the
equivalent width of a line and the luminosity in the continuum (the `Baldwin
Effect') to predict an observed correlation between line width and equivalent
width. The scatter on this correlation is again provided by angular dependence.
The results have applications as diagnostics of models of the broad line
emission region and in cosmology.Comment: 8 pages including 4 figures. Accepted for publication in MNRAS
Letter
The luminosity dependence of opening angle in unified models of active galaxies
In unified models of active galaxies the direct line of sight to the nucleus
is unobscured only within a certain cone of directions. An opening angle for
this cone is usually estimated by methods such as the overall ratio of Seyfert
1s to Seyfert2s, the latter assumed to be obscured versions of the former. Here
we shall show, as has often been suspected, that the opening angle of the cone
depends on the luminosity of the central source, with higher luminosities
corresponding to larger opening angles. This conclusion depends only on the
assumption that the width of the broad emission lines at a given luminosity is
a measure of inclination angle, an assumption that is supported by observation
in radio-loud systems. On the other hand we show that the scatter in X-ray
spectral index is not primarily an effect of viewing angle, in contrast to what
might be expected if the scatter on the spectral index versus luminosity
relation were a consequence of absorption in the obscuring material. The
observed correlation between linewidth and spectral index appears to be a
further consequence of the dependence of opening angle on luminosity.Comment: 8 pages, 7 figures, uses mn.sty. Accepted for publication in MNRA
Determining the cosmological parameters from the linewidths of active galaxies
We have previously shown that the linewidth distribution in AGN can be
accounted for by an axisymmetric broad emission line region. In this paper we
show that the linewidth distribution changes with redshift and that these
changes are dependent on H_0 and q_0. We show that relatively small samples of
AGN at high redshift with measured linewidth at half maximum can be used to
distinguish between values of H_0 and q_0. Furthermore larger low redshift
samples can be used to distinguish between luminosity functions and hence
different models of quasar evolution.Comment: Accepted for publication in MNRAS. 8 pages LaTeX, uses mn.st
First description of post-fledging migration of Maltese Cory's Shearwaters Calonectris diomedea diomedea
Three juvenile Cory’s Shearwaters Calonectris diomedea diomedea were fitted with back-mounted satellite
tags and tracked during post-fledging migration. The birds spent several weeks in the central Mediterranean
before migrating westwards. Two tags stopped transmitting after 21 and 35 days; the third bird passed
through the Strait of Gibraltar and along the West African coast until transmitting ceased after day 43,
by which time it was 114.6 km off the coast and 4,390 km from Malta. Cory’s Shearwaters from other Mediterranean
islands winter further south in equatorial waters, in the eastern South Atlantic or in the northeast
tropical Atlantic associated with the Canary current, and further research is needed to define the wintering
areas of Maltese Cory’s Shearwaters.peer-reviewe
Long Term Feasibility of Inductive Power Transfer Systems Embedded in Concrete Pavement Panels
Electric vehicles (EVs) have a variety of issues that prevent widespread acceptance. Range limitations, charging times, and lack of accessible locations are all viable concerns when considering the future of EVs. This research seeks to address lack of useable infrastructure and battery life by embedding wireless chargers directly into roadway concrete. These embedded chargers would make it possible to charge an EV while it is in transit, addressing many concerns associated with owning an EV.
Embedding a wireless charger, or Inductive Power Transfer System (IPTS), can cause premature failure in the concrete. To determine the long-term feasibility of the technology, it was necessary to test two realistic specimens under normal traffic conditions. Using a hydraulic actuator, the specimens underwent simulated traffic loadings to determine if the concrete or electronics would catastrophically fail. After the cycling was completed, both specimens were reconfigured to be broken to determine if there was a point in which the IPTS would completely fail.
It was determined that both specimens were able to withstand normal and extreme traffic conditions. It was not until the specimens were completely broken that a degradation in performance was found. Utilization of embedded IPT systems in concrete was shown in the laboratory and with modeling to be a viable solution to the growing needs of EV infrastructure
Moving Detectors in Cavities
We consider two-level detectors, coupled to a quantum scalar field, moving
inside cavities. We highlight some pathological resonant effects due to abrupt
boundaries, and decide to describe the cavity by switching smoothly the
interaction by a time-dependent gate-like function. Considering uniformly
accelerated trajectories, we show that some specific choices of non-adiabatic
switching have led to hazardous interpretations about the enhancement of the
Unruh effect in cavities. More specifically, we show that the
emission/absorption ratio takes arbitrary high values according to the emitted
quanta properties and to the transients undergone at the entrance and the exit
of the cavity, {\it independently of the acceleration}. An explicit example is
provided where we show that inertial and uniformly accelerated world-lines can
even lead to the same ``pseudo-temperature''.Comment: 13 pages, 6 figures, version accepted in Phys.Rev.
Time resolved spectroscopy of dust and gas from extrasolar planetesimals orbiting WD 1145+017
Multiple long and variable transits caused by dust from possibly
disintegrating asteroids were detected in light curves of WD 1145+017. We
present time-resolved spectroscopic observations of this target with QUCAM CCDs
mounted in the Intermediate dispersion Spectrograph and Imaging System at the
4.2-m William Herschel Telescope in two different spectral arms: the blue arm
covering 3800-4025 {\AA} and the red arm covering 7000-7430 {\AA}. When
comparing individual transits in both arms, our observations show with 20
{\sigma} significance an evident colour difference between the in- and
out-of-transit data of the order of 0.05-0.1 mag, where transits are deeper in
the red arm. We also show with > 6 {\sigma} significance that spectral lines in
the blue arm are shallower during transits than out-of-transit. For the
circumstellar lines it also appears that during transits the reduction in
absorption is larger on the red side of the spectral profiles. Our results
confirm previous findings showing the u'-band excess and a decrease in line
absorption during transits. Both can be explained by an opaque body blocking a
fraction of the gas disc causing the absorption, implying that the absorbing
gas is between the white dwarf and the transiting objects. Our results also
demonstrate the capability of EMCCDs to perform high-quality time resolved
spectroscopy of relatively faint targets.Comment: 9 pages, 5 figures. Accepted to MNRA
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