4,492 research outputs found
The metallicity-luminosity relation at medium redshift based on faint CADIS emission line galaxies
The emission line survey within the Calar Alto Deep Imaging Survey (CADIS)
detects galaxies with very low continuum brightness by using an imaging
Fabry-Perot interferometer. With spectroscopic follow-up observations of
MB>~-19 CADIS galaxies using FORS2 at the VLT and DOLORES at TNG we obtained
oxygen abundances of 5 galaxies at z~0.4 and 10 galaxies at z~0.64. Combining
these measurements with published oxygen abundances of galaxies with MB<~-19 we
find evidence that a metallicity-luminosity relation exists at medium redshift,
but it is displaced to lower abundances and higher luminosities compared to the
metallicity-luminosity relation in the local universe. Comparing the observed
metallicities and luminosities of galaxies at z<3 with Pegase2 chemical
evolution models we have found a favoured scenario in which the metallicity of
galaxies increases by a factor of ~2 between z~0.7 and today, and their
luminosity decreases by ~0.5-0.9mag.Comment: Accepted for publication in A&A; 12 pages, 9 figure
An international comparative study of blood pressure in populations of European vs. African descent
Background: The consistent finding of higher prevalence of hypertension in US blacks compared
to whites has led to speculation that African-origin populations are particularly susceptible to this
condition. Large surveys now provide new information on this issue.
Methods: Using a standardized analysis strategy we examined prevalence estimates for 8 white
and 3 black populations (N = 85,000 participants).
Results: The range in hypertension prevalence was from 27 to 55% for whites and 14 to 44% for
blacks.
Conclusions: These data demonstrate that not only is there a wide variation in hypertension
prevalence among both racial groups, the rates among blacks are not unusually high when viewed
internationally. These data suggest that the impact of environmental factors among both
populations may have been under-appreciated
a prospective observational study
Introduction Emergency rooms (ERs) generally assign a preliminary diagnosis to
patients, who are then hospitalised and may subsequently experience a change
in their lead diagnosis (cDx). In ERs, the cDx rate varies from around 15% to
more than 50%. Among the most frequent reasons for diagnostic errors are
cognitive slips, which mostly result from faulty data synthesis. Furthermore,
physicians have been repeatedly found to be poor self-assessors and to be
overconfident in the quality of their diagnosis, which limits their ability to
improve. Therefore, some of the clinically most relevant research questions
concern how diagnostic decisions are made, what determines their quality and
what can be done to improve them. Research that addresses these questions is,
however, still rare. In particular, field studies that allow for generalising
findings from controlled experimental settings are lacking. The ER, with its
high throughput and its many simultaneous visits, is perfectly suited for the
study of factors contributing to diagnostic error. With this study, we aim to
identify factors that allow prediction of an ER's diagnostic performance.
Knowledge of these factors as well as of their relative importance allows for
the development of organisational, medical and educational strategies to
improve the diagnostic performance of ERs. Methods and analysis We will
conduct a field study by collecting diagnostic decision data, physician
confidence and a number of influencing factors in a real-world setting to
model real-world diagnostic decisions and investigate the adequacy, validity
and informativeness of physician confidence in these decisions. We will
specifically collect data on patient, physician and encounter factors as
predictors of the dependent variables. Statistical methods will include
analysis of variance and a linear mixed-effects model. Ethics and
dissemination The Bern ethics committee approved the study under KEK Number
197/15. Results will be published in peer-reviewed scientific medical
journals. Authorship will be determined according to ICMJE guidelines. Trial
registration number The study protocol Version 1.0 from 17 May 2015 is
registered in the Inselspital Research Database Information System (IRDIS) and
with the IRB (‘Kantonale Ethikkomission’) Bern under KEK Number 197/15
The Luminosity Function Of Field Galaxies And Its Evolution Since z=1
We present the B-band luminosity function and comoving space and luminosity
densities for a sample of 2779 I-band selected field galaxies based on
multi-color data from the CADIS survey. The sample is complete down to I_815 =
22 without correction and with completeness correction extends to I_815=23.0.
By means of a new multi-color analysis the objects are classified according to
their spectral energy distributions (SEDs) and their redshifts are determined
with typical errors of delta z <= 0.03. We have split our sample into four
redshift bins between z=0.1 and z=1.04 and into three SED bins E-Sa,Sa-Sc and
starbursting (emission line) galaxies. The evolution of the luminosity function
is clearly differential with SED. The normalization phi* of luminosity function
for the E-Sa galaxies decreases towards higher redshift, and we find evidence
that the comoving galaxy space density decreases with redshift as well. In
contrast, we find phi* and the comoving space density increasing with redshift
for the Sa-Sc galaxies. For the starburst galaxies we find a steepening of the
luminosity function at the faint end and their comoving space density increases
with redshift.Comment: 15 pages, 14 figures, accepted by Astronomy&Astrophysic
Multi-color Classification in the Calar Alto Deep Imaging Survey
We use a multi-color classification method introduced by Wolf, Meisenheimer &
Roeser (2000) to reliably identify stars, galaxies and quasars in the up to
16-dimensional color space provided by the filter set of the Calar Alto Deep
Imaging Survey (CADIS). The samples of stars, galaxies and quasars obtained
this way have been used for dedicated studies published in separate papers. The
classification is good enough to detect quasars rather completely and
efficiently without confirmative spectroscopy. The multi-color redshifts are
accurate enough for most statistical applications, e.g. evolutionary studies of
the galaxy luminosity function. We characterize our current dataset on the
CADIS 1h-, 9h- and 16h-fields. Using Monte-Carlo simulations we model the
classification performance expected for CADIS. We present a summary of the
classification results and discuss unclassified objects. More than 99% of the
whole catalog sample at R<22 (more than 95% at R<23) are successfully
classified matching the expectations derived from the simulations. A small
number of peculiar objects challenging the classification are discussed in
detail. Spectroscopic observations are used to check the reliability of the
multi-color classification (6 mistakes among 151 objects with R<24). We also
determine the accuracy of the multi-color redshifts which are rather good for
galaxies (sigma_z = 0.03) and useful for quasars. We find the classification
performance derived from the simulations to compare well with results from the
real survey. Finally, we locate areas for potential improvement of the
classification.Comment: 18 pages, 13 figures included, accepted for publication in Astronomy
& Astrophysic
Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
Redox noninnocent ligands are a promising tool to moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2-10 bar, 20-80 degrees C) by use of the stable catalyst precursor [((Dipp)BIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic studies support a homogeneous catalysis pathway involving alkene and hydrido cobaltates as active catalyst species. Furthermore, considerable reaction acceleration by alkali cations and Lewis acids was observed. The dinuclear hydridocobaltate anion with bridging hydride ligands was isolated and fully characterized
Does self-monitoring reduce blood pressure? Meta-analysis with meta-regression of randomized controlled trials
Introduction. Self-monitoring of blood pressure (BP) is an increasingly common part of hypertension management. The objectives of this systematic review were to evaluate the systolic and diastolic BP reduction, and achievement of target BP, associated with self-monitoring.
Methods. MEDLINE, Embase, Cochrane database of systematic reviews, database of abstracts of clinical effectiveness, the health technology assessment database, the NHS economic evaluation database, and the TRIP database were searched for studies where the intervention included self-monitoring of BP and the outcome was change in office/ambulatory BP or proportion with controlled BP. Two reviewers independently extracted data. Meta-analysis using a random effects model was combined with meta-regression to investigate heterogeneity in effect sizes.
Results. A total of 25 eligible randomized controlled trials (RCTs) (27 comparisons) were identified. Office systolic BP (20 RCTs, 21 comparisons, 5,898 patients) and diastolic BP (23 RCTs, 25 comparisons, 6,038 patients) were significantly reduced in those who self-monitored compared to usual care (weighted mean difference (WMD) systolic −3.82 mmHg (95% confidence interval −5.61 to −2.03), diastolic −1.45 mmHg (−1.95 to −0.94)). Self-monitoring increased the chance of meeting office BP targets (12 RCTs, 13 comparisons, 2,260 patients, relative risk = 1.09 (1.02 to 1.16)). There was significant heterogeneity between studies for all three comparisons, which could be partially accounted for by the use of additional co-interventions.
Conclusion. Self-monitoring reduces blood pressure by a small but significant amount. Meta-regression could only account for part of the observed heterogeneity
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