327 research outputs found
Cepheid Calibration of the Peak Brightness of SNe Ia -- IX. SN 1989B in NGC 3627
(Abridged) Repeated imaging observations have been made of NGC 3627 with the
HST in 1997/98, over an interval of 58 days. Images were obtained on 12 epochs
in the F555W band and on five epochs in the F814W band. The galaxy hosted the
prototypical, `Branch normal', type Ia supernova SN 1989B. A total of 83
variables have been found, of which 68 are definite Cepheid variables with
periods ranging from 75 days to 3.85 days. The de-reddened distance modulus is
determined to be (m-M)_0= 30.22+/-0.12 (internal uncertainty) using a subset of
the Cepheid data whose reddening and error parameters are secure.
The photometric data of Wells et al. (1994), combined with the Cepheid data
for NGC 3627 give M_B(max)= -19.36+/-0.18 and M_V(max)= -19.34+/-0.16 for SN
1989B. Combined with the previous six calibrations in this program, plus two
additional calibrations determined by others gives the mean absolute magnitudes
at maximum of = -19.48+/-0.07 and = -19.48 +/-0.07 for `Branch
normal' SNe Ia at this interim stage in the calibration program.
The second parameter correlations of M(max) of blue SNe Ia with decay rate,
color at maximum, and Hubble type are re-investigated. The dependence of
on decay rate is non-linear, showing a minimum for decay rates between
1.0< Delta m_15 <1.6. Magnitudes corrected for decay rate show no dependence on
Hubble type, but a dependence on color remains. Correcting both the fiducial
sample of 34 SNe Ia with decay-rate data and the current 8 calibrating SNe Ia
for the correlation with decay rate as well as color gives H_0= 60+/-2
(internal) km/s/Mpc, in both B and V. The same value to within 4% is obtained
if only the SNe Ia in spirals (without second parameter corrections) are
considered.Comment: 32 pages (with 7 tables and 14 figures) LaTeX, uses emulateapj.sty; a
full-resolution version with complete figs. 4 and 5 is available at
http://www.astro.unibas.ch/cosmology/papers.html ; accepted for publication
in Ap
Cepheid Calibration of the Peak Brightness of SNe Ia. X. SN 1991T in NGC 4527
Repeated imaging observations have been made of NGC 4527 with the Hubble
Space Telescope between April and June 1999, over an interval of 69 days.
Images were obtained on 12 epochs in the F555W band and on five epochs in the
F814W band. The galaxy hosted the type Ia supernova SN1991T, which showed
relatively unusual behavior by having both an abnormal spectrum near light
maximum, and a slower declining light curve than the proto-typical Branch
normal SNe Ia.
A total of 86 variables that are putative Cepheids have been found, with
periods ranging from 7.4 days to over 70 days. From photometry with the DoPHOT
program, the de-reddened distance modulus is determined to be (m-M)_0 = 30.67
+/- 0.12 (internal uncertainty) using a subset of the Cepheid data whose
reddening and error parameters are secure. A parallel analysis of the Cepheids
using photometry with ROMAFOT yields (m -M)_0 =30.82 +/- 0.11. The final
adopted modulus is (m -M)_0 =30.74 +/- 0.12 +/- 0.12 (d=14.1 +/- 0.8 +/- 0.8
Mpc).
The photometric data for SN1991T are used in combination with the Cepheid
distance to NGC 4527 to obtain the absolute magnitude for this supernova of
M_V^0(max) = -19.85 +/- 0.29. The relatively large uncertainty is a result of
the range in estimates of the reddening to the supernova. Thus SN1991T is seen
to be only moderately brighter (by ~ 0.3 mag) than the mean for
spectroscopically normal supernovae, although magnitude differences of up to
0.6 mag cannot be ruled out.Comment: 46 pages, LATEX using aaspp4.sty, including 9 embedded tables, 19
figures (gif and jpg files), a full-resolution version (ps files) is
available at http://www.astro.unibas.ch/forschung/ll/cepheid.shtml, accepted
for publication in the Astrophysical Journa
A Cepheid Distance to NGC 4603 in Centaurus
In an attempt to use Cepheid variables to determine the distance to the
Centaurus cluster, we have obtained images of NGC 4603 with the Hubble Space
Telescope on 9 epochs using WFPC2 and the F555W and F814W filters. This galaxy
has been suggested to lie within the ``Cen30'' portion of the cluster and is
the most distant object for which this method has been attempted. Previous
distance estimates for Cen30 have varied significantly and some have presented
disagreements with the peculiar velocity predicted from redshift surveys,
motivating this investigation. Using our observations, we have found 61
candidate Cepheid variable stars; however, a significant fraction of these
candidates are likely to be nonvariable stars whose magnitude measurement
errors happen to fit a Cepheid light curve of significant amplitude for some
choice of period and phase. Through a maximum likelihood technique, we
determine that we have observed 43 +/- 7 real Cepheids and that NGC 4603 has a
distance modulus of 32.61 +0.11/-0.10 (random, 1 sigma) +0.24/-0.25
(systematic, adding in quadrature), corresponding to a distance of 33.3 Mpc.
This is consistent with a number of recent estimates of the distance to NGC
4603 or Cen30 and implies a small peculiar velocity consistent with predictions
from the IRAS 1.2 Jy redshift survey if the galaxy lies in the foreground of
the cluster.Comment: Accepted for publication in the Astrophysical Journal. 17 pages with
17 embedded figures and 3 tables using emulateapj.sty. Additional figures and
images may be obtained from http://astro.berkeley.edu/~marc/n4603
The extra-galactic Cepheid distance scale from LMC and Galactic period-luminosity relations
In this paper, we recalibrate the Cepheid distance to some nearby galaxies observed by the HST Key Project and the Sandage-Tammann-Saha group. We use much of the Key Project methodology in our analysis but apply new techniques, based on Fourier methods to estimate the mean of a sparsely sampled Cepheid light curve, to published extra-galactic Cepheid data. We also apply different calibrating PL relations to estimate Cepheid distances, and investigate the sensitivity of the distance moduli to the adopted calibrating PL relation. We re-determine the OGLELMC PL relations using a more conservative approach and also study the effect of using Galactic PL relations on the distance scale. For the Key Project galaxies after accounting for charge transfer effects, we find good agreement with an average discrepancy of -0.002 and 0.075 mag when using the LMC and Galaxy, respectively, as a calibrating PL relation. For NGC 4258 which has a geometric distance of 29.28 mag, we find a distance modulus of 29. 44 ± 0.06(random) mag, after correcting for metallicity. In addition we have calculated the Cepheid distance to 8 galaxies observed by the Sandage-Tammann-Saha group and find shorter distance moduli by -0.178 mag (mainly due to the use of different LMC PL relations) and -0.108 mag on average again when using the LMC and Galaxy, respectively, as a calibrating PL relation. However care must be taken to extrapolate these changed distances to changes in the resulting values of the Hubble constant because STS also use distances to NGC 3368 and 4414 and because STS calibration of SN la is often decoupled from the distance to the host galaxy through their use of differential extinction arguments. We also calculate the distance to all these galaxies using PL relations at maximum light and find very good agreement with mean light PL distances. However, after correcting for metallicity effects, the difference between the distance moduli obtained using the two sets of calibrating PL relations becomes negligible. This suggests that Cepheids in the LMC and Galaxy do follow different PL relations and constrains the sign for the coefficient of the metallicity correction, γ, to be negative, at least at the median period log(P) approximately equals 1.4, of the target galaxies
Strengthening patient-centred communication in rural Ugandan health centres: A theory-driven evaluation within a cluster randomized trial.
This article describes a theory-driven evaluation of one component of an intervention to improve the quality of health care at Ugandan public health centres. Patient-centred services have been advocated widely, but such approaches have received little attention in Africa. A cluster randomized trial is evaluating population-level outcomes of an intervention with multiple components, including 'patient-centred services.' A process evaluation was designed within this trial to articulate and evaluate the implementation and programme theories of the intervention. This article evaluates one hypothesized mechanism of change within the programme theory: the impact of the Patient Centred Services component on health-worker communication. The theory-driven approach extended to evaluation of the outcome measures. The study found that the proximal outcome of patient-centred communication was rated 10 percent higher (p < 0.008) by care seekers consulting with the health workers who were at the intervention health centres compared with those at control health centres. This finding will strengthen interpretation of more distal trial outcomes
Long-term outcome after SARS-CoV-2 infection in healthcare workers: a single centre cohort study
BACKGROUND: Long-term symptoms after acute COVID-19 are highly debated. Nevertheless, data on long-term symptoms of COVID-19 in healthcare workers are scarce. METHODS: We assessed frequency and risk factors of persisting symptoms in a retrospective cohort of healthcare workers infected with SARS-CoV-2. RESULTS: Persistent symptoms at 3 and 12 months were reported by 26.5% and 13.5% of participants, respectively. Most commonly reported symptoms were fatigue, impaired sense of taste or smell and general weakness. A history of depression or state of exhaustion, pre-existing lung disease and older age were associated with persisting symptoms. CONCLUSION: Our study shows that a relevant proportion of healthcare workers with mild COVID-19 report persisting symptoms over 3 and 12 months. Although in the majority of cases symptoms are mild, this study highlights the need for further research into causes and therapy
A systematic review of primary care models for non-communicable disease interventions in Sub-Saharan Africa
Background
Chronic diseases, primarily cardiovascular disease, respiratory disease, diabetes and cancer, are the leading cause of death and disability worldwide. In sub-Saharan Africa (SSA), where communicable disease prevalence still outweighs that of non-communicable disease (NCDs), rates of NCDs are rapidly rising and evidence for primary healthcare approaches for these emerging NCDs is needed.
Methods
A systematic review and evidence synthesis of primary care approaches for chronic disease in SSA. Quantitative and qualitative primary research studies were included that focused on priority NCDs interventions. The method used was best-fit framework synthesis.
Results
Three conceptual models of care for NCDs in low- and middle-income countries were identified and used to develop an a priori framework for the synthesis. The literature search for relevant primary research studies generated 3759 unique citations of which 12 satisfied the inclusion criteria. Eleven studies were quantitative and one used mixed methods. Three higher-level themes of screening, prevention and management of disease were derived. This synthesis permitted the development of a new evidence-based conceptual model of care for priority NCDs in SSA.
Conclusions
For this review there was a near-consensus that passive rather than active case-finding approaches are suitable in resource-poor settings. Modifying risk factors among existing patients through advice on diet and lifestyle was a common element of healthcare approaches. The priorities for disease management in primary care were identified as: availability of essential diagnostic tools and medications at local primary healthcare clinics and the use of standardized protocols for diagnosis, treatment, monitoring and referral to specialist care
Mental health and resilience among Eritrean refugees at arrival and one-year post-registration in Switzerland: a cohort study
OBJECTIVE: Eritrea is the most frequent country of origin among asylum seekers in Switzerland. On their journey through the desert and across the Mediterranean Sea, Eritrea refugees are often exposed to traumatizing experiences. The aim of this study is to assess the mental health status and resilience of Eritrean migrants in Switzerland upon arrival and one-year post-arrival, using standardized mental health screening and resilience assessment tools. RESULTS: At baseline, 107 refugees (11.2% female, median age 25) were interviewed: 52 (48.6%) screened positive for Post-Traumatic Stress Disorder (score ≥ 30), 10.3% for anxiety (≥ 10) and 15.0% for depression (≥ 10); 17.8% scored as risk/hazardous drinkers (≥ 8). The majority (94.4%) had a high resilience score (≥ 65). For one-year follow-up, 48 asylum seekers could be reached. In interviews 18 (38%) of these reported imprisonment in a transit country and 28 (58%) that they had witnessed the death of a close person along the migration route. At the one year assessment, rates of risky/hazardous alcohol use remained unchanged, rates of positive PTSD screening tended to be lower (50.0% (24/48) at baseline vs 25.0% (12/48) at follow-up), as were rates of positive screening for anxiety (8.3% vs 4.2%) and depression (14.6 vs 6.3%)
Reaching absent and refusing individuals during home-based HIV testing through self-testing-at what cost?
Introduction: In the HOSENG trial (NCT03598686), the secondary distribution of oral self-tests for persons absent or refusing to test during a home-based HIV testing campaign in rural Lesotho resulted in an increase in testing coverage of 21% compared to a testing campaign without secondary distribution. This study aims to determine the per patient costs of both HOSENG trial arms. Method: We conducted a micro-costing study to estimate the cost of home-based HIV testing with (HOSENG intervention arm) and without (HOSENG control arm) secondary self-test distribution from a provider's perspective. A mixture of top-down and bottom-up costing was used. We estimated both the financial and economic per patient costs of each possible testing cascade scenario. The costs were adjusted to 2018 US36,481 among the 4,174 persons enumerated and 3,094 eligible for testing in the intervention villages compared to US11.79 in the intervention vs. US15.70 vs. US889.79 in the intervention and US$753.17 in the control. Conclusion: During home-based HIV testing in Lesotho, the secondary distribution of self-tests for persons absent or refusing to test during the visit reduced the costs per person tested and thus presents a promising add-on for such campaigns. Trial Registration:https://ClinicalTrials.gov/, identifier: NCT03598686
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