2,009 research outputs found
The Weak Clustering of Gas-Rich Galaxies
We examine the clustering properties of HI-selected galaxies through an
analysis of the HI Parkes All-Sky Survey Catalogue (HICAT) two-point
correlation function. Various sub-samples are extracted from this catalogue to
study the overall clustering of HI-rich galaxies and its dependence on
luminosity, HI gas mass and rotational velocity. These samples cover the entire
southern sky Dec < 0 deg, containing up to 4,174 galaxies over the radial
velocity range 300-12,700 km/s. A scale length of r_0 = 3.45 +/- 0.25 Mpc/h and
slope of gamma = 1.47 +/- 0.08 is obtained for the HI-rich galaxy real-space
correlation function, making gas-rich galaxies among the most weakly clustered
objects known. HI-selected galaxies also exhibit weaker clustering than
optically selected galaxies of comparable luminosities. Good agreement is found
between our results and those of synthetic HI-rich galaxy catalogues generated
from the Millennium Run CDM simulation. Bisecting HICAT using different
parameter cuts, clustering is found to depend most strongly on rotational
velocity and luminosity, while the dependency on HI mass is marginal. Splitting
the sample around v_rot = 108 km/s, a scale length of r_0 = 2.86 +/- 0.46 Mpc/h
is found for galaxies with low rotational velocities compared to r_0 = 3.96 +/-
0.33 Mpc/h for the high rotational velocity sample.Comment: Accepted for publication in the Astrophysical Journa
Exploring the causes of adverse events in hospitals and potential prevention strategies
Objectives
To examine the causes of adverse events
(AEs) and potential prevention strategies to minimise the
occurrence of AEs in hospitalised patients.
Methods
For the 744 AEs identified in the patient record
review study in 21 Dutch hospitals, trained reviewers
were asked to select all causal factors that contributed
to the AE. The results were analysed together with data
on preventability and consequences of AEs. In addition,
the reviewers selected one or more prevention strategies
for each preventable AE. The recommended prevention
strategies were analysed together with four general
causal categories: technical, human, organisational and
patient-related factors.
Results
Human causes were predominantly involved in
the causation of AEs (in 61% of the AEs), 61% of those
being preventable and 13% leading to permanent
disability. In 39% of the AEs, patient-related factors were
involved, in 14% organisational factors and in 4%
technical factors. Organisational causes contributed
relatively often to preventable AEs (93%) and AEs
resulting in permanent disability (20%). Recommended
strategies to prevent AEs were quality assurance/peer
review, evaluation of safety behaviour, training and
procedures. For the AEs with human and patient-related
causes, reviewers predominantly recommended quality
assurance/peer review. AEs caused by organisational
factors were considered preventable by improving
procedures.
Discussion
Healthcare interventions directed at human
causes are recommended because these play a large
role in AE causation. In addition, it seems worthwhile to
direct interventions on organisational causes because the
AEs they cause are nearly always believed to be
preventable. Organisational factors are thus relatively
easy to tackle. Future research designs should allow
researchers to interview healthcare providers that were
involved in the event, as an additional source of
information on contributing factors.
Diagnostic reasoning and diagnostic error in medicine
Timmermans, D.R.M. [Promotor]Wal, G. van der [Promotor]Thijs, A. [Copromotor]Wagner, C. [Copromotor
Diagnostic error increases mortality and length of hospital stay in patients presenting through the emergency room
Background: Diagnostic errors occur frequently, especially in the emergency room. Estimates about the
consequences of diagnostic error vary widely and little is known about the factors predicting error. Our
objectives thus was to determine the rate of discrepancy between diagnoses at hospital admission and
discharge in patients presenting through the emergency room, the discrepancies’ consequences, and factors
predicting them.
Methods: Prospective observational clinical study combined with a survey in a University-affiliated tertiary
care hospital. Patients’ hospital discharge diagnosis was compared with the diagnosis at hospital admittance
through the emergency room and classified as similar or discrepant according to a predefined scheme by
two independent expert raters. Generalized linear mixed-effects models were used to estimate the effect of
diagnostic discrepancy on mortality and length of hospital stay and to determine whether characteristics of
patients, diagnosing physicians, and context predicted diagnostic discrepancy.
Results: 755 consecutive patients (322 [42.7%] female; mean age 65.14 years) were included.
The discharge diagnosis differed substantially from the admittance diagnosis in 12.3% of cases. Diagnostic
discrepancy was associated with a longer hospital stay (mean 10.29 vs. 6.90 days; Cohen’s d 0.47; 95%
confidence interval 0.26 to 0.70; P = 0.002) and increased patient mortality (8 (8.60%) vs. 25(3.78%); OR 2.40; 95% CI 1.05
to 5.5 P = 0.038). A factor available at admittance that predicted diagnostic discrepancy was the diagnosing physician’s
assessment that the patient presented atypically for the diagnosis assigned (OR 3.04; 95% CI 1.33–6.96; P = 0.009).
Conclusions: Diagnostic discrepancies are a relevant healthcare problem in patients admitted through the
emergency room because they occur in every ninth patient and are associated with increased in-hospital
mortality. Discrepancies are not readily predictable by fixed patient or physician characteristics; attention
should focus on context
The velocity function of gas-rich galaxies
We measure the distribution function of rotational velocities phi(V_c) of
late-type galaxies from the HIPASS galaxy catalogue. Previous measurements of
the late-type velocity function are indirect, derived by converting the galaxy
luminosity function using the relation between galaxy luminosity and rotation
velocity (the Tully-Fisher relation). The advantage of HIPASS is that space
densities and velocity widths are both derived from the same survey data. We
find good agreement with earlier inferred measurements of phi(V_c), but we are
able to define the space density of objects with V_c as low as 30 km/s. The
measured velocity function is `flat' (power-law slope alpha ~ -1.0) below V_c =
100 km/s. We compare our results with predictions based on LCDM simulations and
find good agreement for rotational velocities in excess of 100 km/s, but at
lower velocities current models over-predict the space density of objects. At
V_c=30 km/s this discrepancy is approximately a factor 20.Comment: 9 pages, 7 figures. Accepted for publication in MNRA
The HIPASS catalogue: Omega_HI and environmental effects on the HI mass function of galaxies
We use the catalogue of 4315 extragalactic HI 21-cm emission line detections
from HIPASS to calculate the most accurate measurement of the HI mass function
(HIMF) of galaxies to date. The completeness of the HIPASS sample is well
characterised, which enables an accurate calculation of space densities. The
HIMF is fitted with a Schechter function with parameters: alpha=-1.37 +/- 0.03
+/- 0.05, log (M_HI/M_sun=9.80 +/- 0.03 +/- 0.03, and theta*=(6.0 +/- 0.8 +/-
0.6) x 10^{-3} Mpc^{-3} (random and systematic uncertainties at 68% CL, H0=75),
in good agreement with calculations based on the HIPASS Bright Galaxy
Catalogue, which is a complete, but smaller, sub-sample of galaxies. The
cosmological mass density of HI in the local universe is found to be
Omega_HI=(3.5 +/- 0.4 +/- 0.4) x 10^{-4}. This large homogeneous sample allows
us to test whether the shape of the HIMF depends on local galaxy density. We
find tentative evidence for environmental effects in the sense that the HIMF
becomes steeper toward higher density regions, ranging from alpha ~ -1.2 in the
lowest density environments to alpha ~ -1.5 in the highest density environments
probed by this blind HI survey. This effect appears stronger when densities are
measured on larger scales.Comment: Accepted for publication in MNRAS Letters. 5 pages, including 4
figures. Corrected typo
A techno-economic perspective on rigid and flexible perovskite solar modules
Perovskite solar cells have shown considerable developments in the last decade, and commercial applications are drawing closer. In this article, we present a techno-economic study of perovskite PV technologies. We compare published data on manufacturing costs of single-junction perovskite modules and find that they are dependent on the module design (rigid or flexible) and vary from 10 to almost 100 € per m2. We calculate the LCOE as a function of module efficiency and stability for a set of four module cost scenarios at 12.5, 25, 50, and 100 € per m2. The resulting LCOE varies from 4.3 to 25.5 ct kW−1 h−1 and shows low potential for immediate competition with crystalline silicon PV in the utility sector. Perovskite PV's competitive advantage lies in both lighter and less rigid modules, and in the development of tandem modules together with silicon. We hence extend the LCOE equation to highlight the benefit of producing flexible low-weight modules by roll-to-roll manufacturing, and modify the LCOE maps to showcase the benefits of tandem modules. Based on learning curve analyses applied to the CAPEX of single-junction and tandem modules, we develop three scenarios for the evolution of the LCOE of perovskite modules from 2025 to 2050. Under the optimistic scenarios, we find that the LCOE could reduce to 2.8 ct kW−1 h−1 by 2050.</p
Fandom
This entry presents an overview of the development and current state of fan studies, exploring the “reverse image” of media effects. The field of fan studies offers the ultimate rebuttal of the traditional media effects-model, by stressing the independence, agency and power of media consumers vis-à-vis media producers.
After providing a short historiography of the discipline, this entry dives deeper into three themes that have been central to discussions within fan studies since its early beginnings: fan fiction, fan communities, and places of fandom
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