Context. The F8 star HD 181906 (effective temperature ${\sim}6300$ K) was observed for 156 days by the CoRoT satellite during the first long run in the direction of the galactic centre. Analysis of ...the data reveals a spectrum of solar-like acoustic oscillations. However, the faintness of the target (mv = 7.65) means the signal-to-noise (S/N) in the acoustic modes is quite low, and this low S/N leads to complications in the analysis. Aims. We extract global variables of the star, as well as key parameters of the p modes observed in the power spectrum of the lightcurve. Methods. The power spectrum of the lightcurve, a wavelet transform and spot fitting were used to obtain the average rotation rate of the star and its inclination angle. Then, the autocorrelation of the power spectrum and the power spectrum of the power spectrum were used to properly determine the large separation. Finally, estimations of the mode parameters were done by maximizing the likelihood of a global fit, where several modes were fit simultaneously. Results. We have been able to infer the mean surface rotation rate of the star (~4 μHz) with indications of the presence of surface differential rotation, the large separation of the p modes (~87 μHz), hence also the “ridges” corresponding to overtones of the acoustic modes.
GOLF in-flight commissioning and calibration was carried out during the first four months, most of which represented the cruise phase of SOHO towards its final L1 orbit. The initial performance of ...GOLF is shown to be within the design specification, for the entire instrument as well as for the separate sub-systems. Malfunctioning of the polarising mechanisms after 3 to 4 months operation has led to the adoption of an unplanned operating sequence in which these mechanisms are no longer used. This mode, which measures only the blue wing of the solar sodium lines, detracts little from the detection and frequency measurements of global oscillations, but does make more difficult the absolute velocity calibration, which is currently of the order of 20%. Data continuity in the new mode is extremely high and the instrument is producing exceptionally noise-free p-mode spectra. The data set is particularly well suited to the study of effects due to the excitation mechanism of the modes, leading to temporal variations in their amplitudes. The g modes have not yet been detected in this limited data set. In the present mode of operation, there are no indications of any degradation which would limit the use of GOLF for up to 6 years or more.
Parallels are drawn between the asymmetric resonance profiles observed in global helioseismology and the Fano theory for autoionisation profiles in atomic spectroscopy. We show that the underlying ...physics of the interaction of a discrete resonance with a correlated continuum is common to both systems. The approximate formula normally used for fitting to profiles in helioseismology is essentially similar to that developed for atomic spectroscopy by Fano. We propose that the two systems are in reality equivalent. This proposition enables us to understand better which resonances in helioseismology will be correlated with each other and with which solar background "continua". We also question whether the two interacting influences of excitation sources and correlated solar background, are really separate independent processes.
Abstract Objective: To investigate the involvement of angiogenesis markers in very early arthritis patients and their relevance to predict further joint destruction. Methods: Levels of Vascular ...Endothelial Growth Factor (VEGF), angiopoietin-1 (Ang-1), and soluble Fms-like tyrosine kinase-1 (sFlt-1) were measured by ELISA in serum samples from 310 patients having polyarthritis, evolving for less than 6 months (VErA cohort). Each angiogenesis marker was measured at baseline and one year later. X-rays of hands and feet were carried out at inclusion and after 1 year and read using the van der Heidje-modified Sharp method. Results: At baseline and after 1 year, VEGF levels were correlated with clinical and biological parameters of inflammation. We also observed a positive correlation between sFlt-1 levels and biological inflammation (Erythrocyte Sedimentation Rate (ESR): r = 0.17, p = 0.006; C Reactive Protein: r = 0.14, p = 0.02). Angiopoietin-1 levels were correlated with ESR ( r = 0.12, p = 0.04). Interestingly, only VEGF levels measured at baseline were correlated with Disease Activity Score measured 1 year later. Relationship between angiogenesis markers and radiographic progression was also evaluated. VEGF and Ang-1 levels measured at inclusion were related with Sharp score after one year (VEGF: r = 0.21, p < 0.001; Ang-1: r = 0.24, p < 0.001; Spearman's test). Moreover, VEGF levels were higher in patients with radiographic progression ( p = 0.002). Conclusion: Serum concentrations of VEGF, sFlt-1 and angiopoietin-1 were correlated to parameters of inflammation and to bone destruction in early arthritis. These results contribute to demonstrate that angiogenesis reflects disease severity and angiogenesis markers might become a new useful tool to evaluate disease activity and to estimate outcome for patients with inflammatory arthritis.
Starting in 2014 December, Kepler K 2 observed Neptune continuously for 49 days at a 1 minute cadence. The goals consisted of studying its atmospheric dynamics, detecting its global acoustic ...oscillations, and those of the Sun, which we report on here. We present the first indirect detection of solar oscillations in intensity measurements. Beyond the remarkable technical performance, it indicates how Kepler would see a star like the Sun. The result from the global asteroseismic approach, which consists of measuring the oscillation frequency at maximum amplitude ν {sub max} and the mean frequency separation between mode overtones Δ ν , is surprising as the ν {sub max} measured from Neptune photometry is larger than the accepted value. Compared to the usual reference ν {sub max,⊙} = 3100 μ Hz, the asteroseismic scaling relations therefore make the solar mass and radius appear larger by 13.8 ± 5.8% and 4.3 ± 1.9%, respectively. The higher ν {sub max} is caused by a combination of the value of ν {sub max,⊙}, being larger at the time of observations than the usual reference from SOHO /VIRGO/SPM data (3160 ± 10 μ Hz), and the noise level of the K 2 time series, being 10 times larger than VIRGO’s. The peak-bagging method provides more consistent results: despite a low signal-to-noise ratio (S/N), we model 10 overtones for degrees ℓ = 0, 1, 2. We compare the K 2 data with simultaneous SOHO /VIRGO/SPM photometry and BiSON velocity measurements. The individual frequencies, widths, and amplitudes mostly match those from VIRGO and BiSON within 1 σ, except for the few peaks with the lowest S/N.
Context. The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for ...27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio. Aims. Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum. Methods. The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato. Results. The mean large separation has been measured to be $97.2\pm0.5$ μHz, slightly below the expected value determined from solar scaling laws. We also show strong evidence for variation of the large separation with frequency. The bolometric mode amplitude is only $1.7\pm0.25$ ppm for radial modes, which is 1.7 times less than expected. Due to the low signal-to-noise ratio, mode identification is not possible for the available data set of HD 175726.
Objectives. To test the performances of combining anti-CCP second generation (CCP2) with ACR 1987 classification criteria and to diagnose early RA in a community-based very early arthritis (VErA) ...patient cohort.
Methods. The VErA cohort comprised 310 patients (median age 52 years; 68.1% women; median symptom duration 4.2 months; glucocorticoid- and DMARD naïve) conservatively treated during the first 2 years. At 6 years of follow-up, a three-expert committee classified the patients into three groups: RA, other classified arthritis (OCA) or unclassified arthritis (UA). We calculated the performances of the different sets, including anti-CCP2 positivity, while retaining or deleting RF and rheumatoid nodule components with ACR 1987 criteria for early RA diagnosis. Models were subjected to receiver operating characteristics curve and logistic regression analyses to try to identify relevant sets able to classify very early RA.
Results. At 6 years, 149 patients were diagnosed as RA and 119 as non-RA (95 OCA and 24 UA). The original ACR 1987 criteria had 77.9% sensitivity and 64.7% specificity for the RA diagnosis at 6 years. The modified set excluding rheumatoid nodules, including anti-CCP2 positivity and retaining RF performed significantly better than ACR 1987 criteria, with 79.9% sensitivity and 64.7% specificity and with a larger area under the curve. However, in the zone of interest, i.e. 4/7 criteria, the curves for these sets were superimposed.
Conclusions. Adding anti-CCP2 positivity and deleting rheumatoid nodules failed to improve the performances of ACR 1987 classification criteria for the diagnosis of early RA.
After 8 months of nearly continuous measurements the GOLF instrument, aboard SOHO, has detected acoustic mode frequencies of more than 100 modes, extending from 1.4 mHz to 4.9 mHz. In this paper, we ...compare these results with the best available predictions coming from solar models. To verify the quality of the data, we examine the asymptotic seismic parameters; this confirms the improvements achieved in solar models during the last decade.Using the GOLF set of frequencies for l=0, 1, 2, 3 combined with the LOWL second year data set for l > 3 we then carry out inversions to infer properties of the solar core.This largely confirms the previous results down to around 0.1 Rodot, while there remain differences, even closer to the centre, where the present study shows an extreme sensitivity of the inversion results to the values of the frequencies. We finally consider physical processes which may influence directly or indirectly the solar core structure.
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