14,009 research outputs found
The environments of intermediate-redshift QSOs: 0.3 < z < 0.7
An angular correlation of low significance (2 sigma) is observed between 0.3
< z < 0.5 QSOs and V < 23 galaxies. Overall, the cross-correlation function
between 82 intermediate-redshift (0.3 < z < 0.7), X-ray selected QSOs and V <
24 galaxies is investigated, but no signal is detected for the z > 0.5 QSOs.
After converting to an excess of galaxies physically associated with the QSO,
this lack of strong correlation is shown to be consistent with the clustering
of normal galaxies at the same moderate redshifts. Combined with previous
observations, these results imply that the environments of radio-quiet QSOs do
not undergo significant evolution with respect to the galaxy population over a
wide range of redshifts (0 < z < 1.5). This is in marked contrast to the rapid
increase in the richness of the environments associated with radio-loud QSOs
over the same redshift range.Comment: 12 pages, 8 figures, MNRAS TeX macro, to appear to MNRA
Testing Inflation: A Bootstrap Approach
We note that the essential idea of inflation, that the universe underwent a
brief period of accelerated expansion followed by a long period of decelerated
expansion, can be encapsulated in a "closure condition" which relates the
amount of accelerated expansion during inflation to the amount of decelerated
expansion afterward. We present a protocol for systematically testing the
validity of this condition observationally.Comment: 4 pages, 2 figures, matches Phys. Rev. Lett. versio
Comparison of a quasi-3D analysis and experimental performance for three compact radial turbines
An experimental aerodynamic evaluation of three compact radial turbine builds was performed. Two rotors which were 40 to 50 percent shorter in axial length than conventional state of the art radial rotors were tested. A single nozzle design was used. One rotor was tested with the nozzle at two stagger angle settings. A second rotor was tested with the nozzle in only the closed down setting. Experimental results were compared to predict results from a quasi-3D inviscid and boundary layer analysis, called Meridl/Tsonic/Blayer (MTSB). This analysis was used to predict turbine performance. It has previously been calibrated only for axial, not radial, turbomachinery. The predicted and measured efficiencies were compared at the design point for the three turbines. At the design points the analysis overpredicted the efficiency by less than 1.7 points. Comparisons were also made at off-design operating points. The results of these comparisons showed the importance of an accurate clearance model for efficiency predictions and also that there are deficiencies in the incidence loss model used
The Extinction Distribution in the Galaxy UGC 5041
We probe the dust extinction through the foreground disk of the overlapping
galaxy pair UGC 5041 by analyzing B,I, and H band images. The inclined
foreground disk of this infrared-selected pair is almost opaque in B at a
projected distance of ~8kpc. From the images, we estimate directly the
area-weighted distribution of differential near-IR extinction: it is nearly
Gaussian with =0.6 and sigma=0.27. For a homogenous dust
distribution and a Milky Way extinction curve, this corresponds to a face-on
distribution p(tau) with a mean of =0.34 and sigma_V=0.15. For a clumpy
dust model the optical depth estimate increases to =0.41 and
sigma_V=0.19. Even though the galaxy pair is subject to different selection
biases and our analysis is subject to different systematics, the result is
consistent with existing case studies, indicating that ~0.3 is generic
for late-type spirals near their half-light radii.
We outline how to estimate from p(tau) by how much background quasars are
underreresented, where projected within ~10kpc of nearby spirals, such as
damped Ly-alpha absorbers or gravitational lenses; from our data we derive a
factor of two deficit for flux-limited, optical surveys.Comment: 18 pages, 3 figures; To appear in the Astronomical Journa
The Evolution of Radio Galaxies at Intermediate Redshift
We describe a new estimate of the radio galaxy 1.4 GHz luminosity function
and its evolution at intermediate redshifts (z~0.4). Photometric redshifts and
color selection have been used to select Bj<23.5 early-type galaxies from the
Panoramic Deep Fields, a multicolor survey of two 25 sq deg fields.
Approximately 230 radio galaxies have then been selected by matching early-type
galaxies with NVSS radio sources brighter than 5 mJy. Estimates of the 1.4 GHz
luminosity function of radio galaxies measure significant evolution over the
observed redshift range. For an Omega_M=1 cosmology the evolution of the radio
power is consistent with luminosity evolution where P(z)=P(0)(1+z)^{k_L} and
3<k_L<5. The observed evolution is similar to that observed for UVX and X-ray
selected AGN and is consistent with the same physical process being responsible
for the optical and radio luminosity evolution of AGN.Comment: 26 pages, 9 Figures, Accepted for Publication in A
The 2dF QSO Redshift Survey
We present preliminary results from the 2-degree Field (2dF) QSO Redshift
Survey currently under way at the Anglo-Australian Telescope. This survey aims
to determine the redshifts of >25000 QSOs over a redshift range of 0.3<z<3.0
with the primary goal of investigating large-scale structure in the Universe to
high redshift and at very large scales (~1000h-1Mpc).
We describe the photometric procedure used to select QSO candidates for
spectroscopic observation. We then describe results from our first 2dF
observations, which have so far measured the redshifts for over 1000 QSOs. We
already find a significant detection of clustering and have also found one
close pair of QSOs (separation 17'') which are gravitational lens candidates.
To keep up to date with the current progress of the survey see:
http://msowww.anu.edu.au/~rsmith/QSO_Survey/qso_surv.htmlComment: 5 pages Latex including 6 figures, To appear in the proceedings of
"Evolution of Large Scale Structure: From Recombination to Garching", held
August 199
QSO clustering and the AAT 2dF redshift survey
We review previous results on the clustering and environments of QSOs. We
show that the correlation length for QSOs derived from existing surveys is
r~5/h Mpc, similar to the observed correlation length for field galaxies at the
present epoch. The galaxy environment for z<1 radio-quiet QSOs is also
consistent with field galaxies. The evolution of the QSO correlation length
with redshift is currently uncertain, largely due to the small numbers of QSOs
(~2000) in surveys suitable for clustering analysis. We report on intial
progress with the AAT 2dF QSO redshift survey, which, once completed will
comprise almost 30000 QSOs. With over 1000 QSOs already observed, it is already
the largest single homogeneous QSO survey. We discuss prospects for deriving
limits on cosmological parameters from this survey, and on the evolution of
large-scale structure in the Universe.Comment: Invited talk at RS meeting on 'Large Scale Structure in the Universe'
held at the Royal Society on 25-26 March 1998 14 pages, 11 figre
Incorporating patient preferences in the management of multiple long-term conditions: is this a role for clinical practice guidelines?
Background: Clinical practice guidelines provide an evidence-based approach to managing single chronic conditions, but their applicability to multiple conditions has been actively debated. Incorporating patient-preference recommendations and involving consumers in guideline development may enhance their applicability, but further understanding is needed. Objectives: To assess guidelines that include recommendations for comorbid conditions to determine the extent to which they incorporate patient-preference recommendations; use consumer-engagement processes during development, and, if so, whether these processes produce more patient-preference recommendations; and meet standard quality criteria, particularly in relation to stakeholder involvement. Design: A review of Australian guidelines published from 2006 to 2014 that incorporated recommendations for managing comorbid conditions in primary care. Document analysis of guidelines examined the presence of patient-preference recommendations and the consumer-engagement processes used. The Appraisal of Guidelines for Research and Evaluation instrument was used to assess guideline quality. Results: Thirteen guidelines were reviewed. Twelve included at least one core patient-preference recommendation. Ten used consumer-engagement processes, including participation in development groups (seven guidelines) and reviewing drafts (ten guidelines). More extensive consumer engagement was generally linked to greater incorporation of patient-preference recommendations. Overall quality of guidelines was mixed, particularly in relation to stakeholder involvement. Conclusions: Guidelines do incorporate some patient-preference recommendations, but more explicit acknowledgement is required. Consumer-engagement processes used during guideline development have the potential to assist in identifying patient preferences, but further research is needed. Clarification of the consumer role and investment in consumer training may strengthen these processes.Journal of Comorbidity 2015;5(1):122–13
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