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The methodology of self-controlled case series studies
The self-controlled case series method is increasingly being used in pharmacoepidemiology, particularly in vaccine safety studies. This method is typically used to evaluate the association between a transient exposure and an acute event, using only cases. We present both parametric and semiparametric models using a motivating example on MMR vaccine and bleeding disorders. We briefly describe approaches for interferent events and a sequential version of the method for prospective surveillance of drug safety. The efficiency of the self-controlled case series method is compared to the that of cohort and case control studies. Some further extensions, to long or indefinite exposures and to bivariate counts, are described
The fundamental parameters of the roAp star 10 Aql
Due to the strong magnetic field and related abnormal surface layers existing
in rapidly oscillating Ap stars, systematic errors are likely to be present
when determining their effective temperatures, which potentially compromises
asteroseismic studies of these pulsators. Using long-baseline interferometry,
our goal is to determine accurate angular diameters of a number of roAp targets
to provide a temperature calibration for these stars. We obtained
interferometric observations of 10 Aql with the visible spectrograph VEGA at
the CHARA array. We determined a limb-darkened angular diameter of
0.275+/-0.009 mas and deduced a linear radius of 2.32+/-0.09 R_sun. We
estimated the star's bolometric flux and used it, in combination with its
parallax and angular diameter, to determine the star's luminosity and effective
temperature. For two data sets of bolometric flux we derived an effective
temperature of 7800+/-170 K and a luminosity of 18+/-1 L_sun or of 8000+/-210 K
and 19+/-2 L_sun. We used these fundamental parameters together with the large
frequency separation to constrain the mass and the age of 10 Aql, using the
CESAM stellar evolution code. Assuming a solar chemical composition and
ignoring all kinds of diffusion and settling of elements, we obtained a mass of
1.92 M_sun and an age of 780 Gy or a mass of 1.95 M_sun and an age of 740 Gy,
depending on the considered bolometric flux. For the first time, we managed to
determine an accurate angular diameter for a star smaller than 0.3 mas and to
derive its fundamental parameters. In particular, by only combining our
interferometric data and the bolometric flux, we derived an effective
temperature that can be compared to those derived from atmosphere models. Such
fundamental parameters can help for testing the mechanism responsible for the
excitation of the oscillations observed in the magnetic pulsating stars
Improving the surface brightness-color relation for early-type stars using optical interferometry
The aim of this work is to improve the SBC relation for early-type stars in
the color domain, using optical interferometry.
Observations of eight B- and A-type stars were secured with the VEGA/CHARA
instrument in the visible. The derived uniform disk angular diameters were
converted into limb darkened angular diameters and included in a larger sample
of 24 stars, already observed by interferometry, in order to derive a revised
empirical relation for O, B, A spectral type stars with a V-K color index
ranging from -1 to 0. We also took the opportunity to check the consistency of
the SBC relation up to using 100 additional measurements. We
determined the uniform disk angular diameter for the eight following stars:
Ori, Per, Cyg, Her, Aql, Peg,
Lyr, and Cyg with V-K color ranging from -0.70 to 0.02 and
typical precision of about . Using our total sample of 132 stars with
colors index ranging from about to , we provide a revised SBC
relation. For late-type stars (), the results are consistent
with previous studies. For early-type stars (), our new
VEGA/CHARA measurements combined with a careful selection of the stars
(rejecting stars with environment or stars with a strong variability), allows
us to reach an unprecedented precision of about 0.16 magnitude or
in terms of angular diameter.Comment: 13 pages, 5 figures, accepted for publication in A&
Respiratory patient experience of measures to reduce risk of COVID-19: findings from a descriptive cross-sectional UK wide survey
Objectives: To assess the experience of people with long-term respiratory conditions regarding the impact of measures to reduce risk of COVID-19. Design: Analysis of data (n=9,515) from the Asthma UK and British Lung Foundation partnership COVID-19 survey collected online between 1st and 8th of April 2020. Setting: Community Participants: 9,515 people with self-reported long term respiratory conditions. 81% female, age ranges from <17 years to 80 and above, from all nations of the UK. Long term respiratory conditions reported included asthma (83%), Chronic Obstructive Pulmonary Disease (COPD) (10%), bronchiectasis (4%), Interstitial Lung Disease (ILD) (2%), and ‘other’ (<1%) (e.g. lung cancer and pulmonary endometriosis). Outcome measures: Study responses related to impacts on key elements of health care, as well as practical, psychological and social consequences related to the COVID-19 pandemic and social distancing measures. Results: 45% reported disruptions to care, including cancellations of appointments, investigations, pulmonary rehabilitation, treatment, and monitoring. Other practical impacts such as difficulty accessing healthcare services for other issues, and getting basic necessities such as food, were also common. 36% did not use online prescriptions and 54% had not accessed online inhaler technique videos. Psycho-social impacts including anxiety, loneliness and concerns about personal health and family were prevalent. 81% reported engaging in physical activity. Among the 11% who were smokers, 48% reported they were planning to quit smoking because of COVID-19. Conclusions: COVID-19 and related social distancing measures are having profound impacts on people with chronic respiratory conditions. Urgent adaptation and signposting of services is required to mitigate the negative health consequences of the COVID-19 response for this group
Field experiments on dishonesty and stealing: what have we learned in the last 40 years?
ObjectivesField experiments combine the benefits of the experimental method and the study of human behavior in real-life settings, providing high internal and external validity. This article aims to review the field experimental evidence on the causes of offending.MethodsWe carried out a systematic search for field experiments studying stealing or monetary dishonesty reported since 1979.ResultsThe search process resulted in 60 field experiments conducted within multiple fields of study, mainly in economics and management, which were grouped into four categories: Fraudulent/ dishonest behavior, Stealing, Keeping money, and Shoplifting.ConclusionsThe reviewed studies provide a wide variety of methods and techniques that allow the real-world study of influences on offending and dishonest behavior. We hope that this summary will inspire criminologists to design and carry out realistic field experiments to test theories of offending, so that criminology can become an experimental science.This study was conducted at the Psychology Research Centre (CIPsi/UM) School of Psychology, University of Minho, supported by the Foundation for Science and Technology (FCT) through the Portuguese State Budget (UIDB/01662/2020). The first author was supported by a doctoral grant from the Portuguese Foundation for Science and Technology (FCT - SFRH/BD/122919/2016)
Imaging the Algol Triple System in H Band with the CHARA Interferometer
Algol (Beta Per) is an extensively studied hierarchical triple system whose
inner pair is a prototype semi-detached binary with mass transfer occurring
from the sub-giant secondary to the main-sequence primary. We present here the
results of our Algol observations made between 2006 and 2010 at the CHARA
interferometer with the Michigan Infrared Combiner in the H band. The use of
four telescopes with long baselines allows us to achieve better than 0.5 mas
resolution and to unambiguously resolve the three stars. The inner and outer
orbital elements, as well as the angular sizes and mass ratios for the three
components are determined independently from previous studies. We report a
significantly improved orbit for the inner stellar pair with the consequence of
a 15% change in the primary mass compared to previous studies. We also
determine the mutual inclination of the orbits to be much closer to
perpendicularity than previously established. State-of-the-art image
reconstruction algorithms are used to image the full triple system. In
particular an image sequence of 55 distinct phases of the inner pair orbit is
reconstructed, clearly showing the Roche-lobe-filling secondary revolving
around the primary, with several epochs corresponding to the primary and
secondary eclipses
The post-hemodialysis rebound: Predicting and quantifying its effect on Kt/V
The post-hemodialysis rebound: Predicting and quantifying its effect on Kt/V. Immediately after hemodialysis, the urea concentration rebounds upwards as urea continues to be transferred into the arterial circulation from peripheral body compartments. This rebound takes at least 30 minutes to complete. Hemodialysis is quantified as the Kt/V, calculated prom pre- and post-dialysis urea samples. Unless the post-dialysis sample is taken at least 30 minutes after dialysis, the Kt/V will be overestimated. This overestimation will be relatively greater in short high-efficiency dialyses, which have greater post-dialysis rebounds. We propose a method of correction that uses only the conventional pre- and immediate post-dialysis samples and is based on the physiologically-appropriate patient clearance time (tp). This is the time needed to clear all body compartments when the dialyzer clearance is infinite. The tp can be calculated from the pre-, immediate post- and 30-minute post-dialysis urea concentrations and was 35 minutes (SD 16) in 29 patients undergoing short (149 min) hemodiafiltration and standard (243 min) hemodialysis the following week. There was no significant difference between tp values calculated during the two treatments. Standard Kt/V can be corrected by multiplying by t/(t + tp) and dialysis time should be increased by tp × Kt/V minutes to compensate for the rebound. Despite individual variations in tp, a value of tp = 35 was sufficient to correct Kt/V in all patients. Kt/V corrected in this way agreed with Kt/V calculated using a 60-minute post-dialysis sample (r = 0.856, P < 0.001). The method predicted the 60-minute post-rebound concentration (SE 0.5mM, r = 0.983, P < 0.001) and the addition of 35 minutes to the treatment time corrected for the rebound in both conventional and short treatments. Similar simple equations corrected the error in V caused by rebound effects
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