We report on the results of the latest solarFLAG hare-and-hounds exercise, which was concerned with testing methods for extraction of frequencies of low-degree solar p modes from data collected by ...Sun-as-a-star observations. We have used the new solarFLAG simulator, which includes the effects of correlated mode excitation and correlations with background noise, to make artificial time-series data that mimic Doppler velocity observations of the Sun-as-a-star. The correlations give rise to asymmetry of mode peaks in the frequency power spectrum. 10 members of the group (the hounds) applied their ‘peak-bagging’ codes to a 3456-d data set, and the estimated mode frequencies were returned to the hare (who was WJC) for comparison. Analysis of the results reveals a systematic bias in the estimated frequencies of modes above ≈1.8 mHz. The bias is negative, meaning the estimated frequencies systematically underestimate the input frequencies. We identify two sources that are the dominant contributions to the frequency bias. Both sources involve failure to model accurately subtle aspects of the observed power spectral density in the part (window) of the frequency power spectrum that is being fitted. One source of bias arises from a failure to account for the power spectral density coming from all those modes whose frequencies lie outside the fitting windows. The other source arises from a failure to account for the power spectral density of the weak l= 4 and 5 modes, which are often ignored in Sun-as-a-star analysis. The Sun-as-a-star peak-bagging codes need to allow for both sources, otherwise the frequencies are likely to be biased.
Context. The space experiment CoRoT has recently detected transits by a hot Jupiter across the disc of an active G7V star (CoRoT-Exo-2a) that can be considered as a good proxy for the Sun at an age ...of approximately 0.5 Gyr. Aims. We present a spot modelling of the optical variability of the star during 142 days of uninterrupted observations performed by CoRoT with unprecedented photometric precision. Methods. We apply spot modelling approaches previously tested in the case of the Sun by modelling total solar irradiance variations, a good proxy for the optical flux variations of the Sun as a star. The best results in terms of mapping of the surface brightness inhomogeneities are obtained by means of maximum entropy regularized models. To model the light curve of CoRoT-Exo-2a, we take into account the photometric effects of both cool spots and solar-like faculae, adopting solar analogy. Results. Two active longitudes initially on opposite hemispheres are found on the photosphere of CoRoT-Exo-2a with a rotation period of 4.522 ± 0.024 days. Their separation changes by ≈80° during the time span of the observations. From this variation, a relative amplitude of the surface differential rotation lower than ~1 percent is estimated. Individual spots form within the active longitudes and show an angular velocity ~1 percent lower than that of the longitude pattern. The total spotted area shows a cyclic oscillation with a period of 28.9 ± 4.3 days, which is close to 10 times the synodic period of the planet as seen by the rotating active longitudes. We discuss the effects of solar-like faculae on our models, finding indications of a facular contribution to the optical flux variations of CoRoT-Exo-2a being significantly smaller than in the present Sun. Conclusions. The implications of such results for the internal rotation of CoRoT-Exo-2a are discussed, based on solar analogy. A possible magnetic star-planet interaction is suggested by the cyclic variation of the spotted area. Alternatively, the 28.9-d cycle may be related to Rossby-type waves propagating in the subphotospheric layers of the star.
Professional Practice Assessment (PPA) has become an obligation for all physicians in France, however its modalities remain unclear. The objective of this work was to evaluate the feasibility and ...accuracy of a PPA for private practice rheumatologists performed in the context of a network.
A list of items considered mandatory to collect during an outpatient visit for rheumatoid arthritis, was prepared by the network. Non hospital-based rheumatologists, members of the network then evaluated some of their patient files selected by chronological order over a one-month period of time using this list. These files were then assessed by another private rheumatologist, member of the group, randomly allocated, using the same list of items.
Eighty percent of the private-practice doctors accepted to participate. The mean time to evaluate 15 patient files was 2 hours. Agreement between auto-evaluation and external evaluation for each file was good (agreement statistic, 0.75-1.0). Items mandatory to collect were collected in a high proportion of cases (84.6%).
PPA can be performed in the context of a network, auto-evaluation is a valid method and when the list of items is decided on by the network, the data are collected satisfactorily.
The predominant contribution to the frequency splitting of low-ℓ solar p modes arises from the rotation of the solar interior and this lifts the frequency degeneracy in ℓ to give a symmetric pattern ...where the observed (synodic) separation between adjacent m (i.e. for |Δm|= 1) is ∼400 nHz. Magnetic fields can also contribute to the splitting, but they do so in such a way as to introduce asymmetries in the arrangement of the components within each multiplet. In disc-integrated data this effect may become apparent when ℓ≥ 2. Here, we attempt to extract estimates of the frequency asymmetries at ℓ= 2 from the analysis of disc-integrated data collected by the ground-based Birmingham Solar Oscillations Network (BiSON) and the GOLF instrument on board the ESA/NASA SOHO satellite. Our analyses demonstrate that we have evidence for there being non-zero asymmetries present (significance ≈3–4σ) during an epoch coincident with high levels of surface activity close to the maximum of solar cycle 23. The asymmetries are indistinguishable from zero at minimum levels of activity near the cycle 22/23 boundary. We also compare the observed asymmetries with those calculated from a model that is based upon the recent predictions of Moreno-Insertis & Solanki. While the level of agreement between the two is found to be reasonable, the observations suggest (though with poor constraints placed upon this) that the influence on the mode frequencies of high-latitude activity may not be as strong as in the model.
SUMMARY
The objective of this study was to determine the diagnostic and prognostic values of antiglucose‐6‐phosphate isomerase (GPI) antibodies in patients with very early arthritis. Anti‐GPI ...antibodies were measured by ELISA using purified GPI from rabbit muscle in: (i) 383 sera from healthy blood donors (n = 120), well‐established rheumatoid arthritis (RA) (n = 99) and non‐RA differentiated arthritis (NRADA) (n = 164) patients; (ii) 195 sera obtained from community‐recruited patients with very early inflammatory arthritis (VErA cohort) that were studied for 1 year and classified as having RA (n = 116), NRADA (n = 41), and undifferentiated arthritis (UA) (n = 38) after the follow‐up period. The criterion for severity was the progression of radiographic damage. Prevalence of anti‐GPI antibodies was significantly higher in well‐established RA patients (45·4%) compared to healthy subjects (2·5%). Anti‐GPI antibodies were also present in sera from NRADA: systemic lupus erythematosus 53%, polymyositis 45·4%, adult‐onset Still's disease 44%, systemic sclerosis 42·8%, spondylarthropathies 25% and primary Sjögren’s syndrome 5·8%. No significant association was found between the presence of anti‐GPI antibodies and the 3 diagnostic groups from the VErA cohort. No correlation was observed between anti‐GPI and autoantibodies usually associated with RA. Anti‐GPI antibodies were not predictive of radiological progression in patients with very early arthritis. Thus, anti‐GPI antibodies are not useful for discriminating RA from non‐RA rheumatic diseases and do not constitute a predictive factor of structural damage.
Aims. We investigate the asteroseismology of two solar-like targets as observed with the CoRoT satellite, with particular attention paid to the mode fitting. HD 181420 and HD 49933 are typical CoRoT ...solar-like targets (156 and 60-day runs). The low signal-to-noise ratio (SNR) of about $3{-}10$ prevents us from unambiguously identifying the individual oscillation modes. In particular, convergence problems appear at the edges of the oscillation spectrum. Methods. We apply a Bayesian approach to the analysis of these data. We compare the global fitting of the power spectra obtained by the classical maximum likelihood (MLE) and the maximum a posteriori (MAP) estimators. Results. We examine the impact of the choice of the priors upon the fitted parameters. We also propose to reduce the number of free parameters in the fitting, by replacing the individual estimate of mode height associated with each overtone by a continuous function of frequency (Gaussian profile). Conclusions. The MAP appears as a powerful tool to constrain the global fits, but it must be used carefully and only with reliable priors. The mode width of the stars increases with the frequency over all the oscillation spectrum.
Accelerated atherosclerosis has emerged as a critical issue in rheumatoid arthritis (RA). There is a need to better understand the link between RA and atherosclerosis. Our aim was to identify ...parameters associated with the development of subclinical atheroma in a very early arthritis (VErA) cohort.
VErA-cohort patients were prospectively recruited from 1998 to 2002. Arthritis treatment was standardised from onset. The clinical, biological and radiological parameters of all patients were collected from inclusion. Carotid intima-media thickness (cIMT) was measured 7 years after their first symptoms.
Among 105 patients included, 82 developed RA (mean age at onset: 51.7±12.8 years). Mean carotid artery IMT at year 7 was 0.67±0.12 mm. Larger thickness defined by values above the median (0.66) was associated with inclusion age (p<10-6), swollen joint count (p=0.01), DAS44 (p=0.048) and hypertension (p=0.006). In contrast, anti-CCP positivity (>50 UA/ml) was associated with thinner cIMT (p=0.03). Baseline as well as cumulated values of markers reflecting systemic inflammation, lymphocyte activation, endothelial dysfunction and oxidative stress were not correlated with carotid subclinical atherosclerosis. Major independent atheroma risk factors retained by multivariate analyses were hypertension (OR 4.33 1.59-11.73; p=0.004) and swollen joint count at inclusion (OR 3.87 1.54-9.72; p=0.004), while methotrexate use was a protective marker (OR 0.27 0.11-0.71; p=0.007).
This study conducted from the VErA vascular cohort of community-cases of RA confirm that cIMT is under the influence of classical CV risk (hypertension), disease marker (SJC) and methotrexate intake.
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