198 research outputs found
Effectiveness and safety of leflunomide in the clinical practice : a different experience
No full textSpectroscopic and Interferometric Tests of Stellar Atmosphere Models: UVES and VINCI Measurements of the M-giant α Cet
No full textWe present VLT/UVES spectroscopic and VLTI/VINCI interferometric observations of the cool giant α Cet (M2 III). Spherically symmetric PHOENIXstellar atmosphere models are tested by comparison with our spectroscopic and interferometric observations. The high spectral resolution of UVES allows us to constrain the effective temperature and the surface gravity of the star by comparing observed and model predicted bands that are temperature and gravity indicators. High angular resolution and high precision VLTI/VINCI observations directly measure the strength of the limb darkening effect of α Cet in the K-band. We derive fundamental stellar parameters, namely a Rosseland diameter of 12.08±0.18 mas corresponding to a Rosseland linear radius of 88±6 R☉, and an effective temperature of 3805+95 -109 K, using the Hipparcos parallax and the bolometric flux
On the age of M4: we are not there yet!
No full textWe have reduced and analysed the deep HST observations of a field in the globular cluster M4 obtained with the WFPC2. The colour-magnitude diagrams that we derive from the deepest exposures, in the F606W and F814W bands, reveal a narrow main sequence as well as the white dwarf (WD) cooling sequence extending down to the 5 sigma detection limit at I ≃ 27. The WD sequence is abruptly terminated at exactly this limit as expected by detection statistics. To separate bona fide WDs from field stars, and obtain in this way the WD luminosity function (LF), we have measured the proper motions of all objects which could be also detected in WFPC2 images of the same field taken 6 years earlier. Unfortunately, the first epoch's exposures being considerably less deep than those of the second, the magnitude range over which the WD LF can be reliably studied is reduced to I<26.5 (at the 3 sigma level, or I ≃ 25.6 at 5 sigma). Below such a threshold, most stars detected in the second epoch do not have a corresponding match in the first one.
Using our most recent theoretical WD models to obtain the expected WD sequence for different ages in the observed bandpasses, we find that the data do not reach the peak of the WD LF, thence only allowing one to set a lower limit to the age of M4 of ̃ 9 Gyr. We are not able to reproduce previous results claiming an age of 12.7 Gyr with an uncertainty of 0.35 Gyr (1 sigma). The problem of determining the absolute age of a globular cluster and, therefore, the onset of GC formation with cosmologically significant accuracy remains completely open. Only observations several magnitudes deeper than the limit obtained so far would allow one to approach this objective
On the age and mass function of the globular cluster M4: A different interpretation of recent deep HST observations
No full textVery deep images of the Galactic globular cluster M4 (NGC6121) through the F606W and F814W filters were taken in 2001 with the WFPC2 on board the,HST. A first published analysis of this data set (Richer et al. 2002) produced the result that the age of M 4 is 12.7 +/- 0.7 Gyr (Hansen et al. 2002), thus setting a robust lower limit to the age of the universe. In view of the great astronomical importance of getting this number right, we have subjected the same data set to the simplest possible photometric analysis that completely avoids uncertain assumptions about the origin of the detected sources. This analysis clearly reveals both a thin main sequence, from which can be deduced the deepest statistically complete mass function yet determined for a globular cluster, and a white dwarf (WD) sequence extending all the way down to the 5 sigma detection limit at I similar or equal to 27. The WD sequence is abruptly terminated at exactly this limit as expected by detection statistics. Using our most recent theoretical WD models (Prada Moroni & Stranierc, 2002) to obtain the expected WD sequence for different ages in the observed bandpasses, we find that the data so far obtained do not reach the peak of the WD luminosity function, thus only allowing one to set a lower limit to the age of M 4 of similar to9 Gyr. Thus, the problem of determining the absolute age of a globular cluster and, therefore, the onset of GC formation with cosmologically significant accuracy remains completely open. Only observations several magnitudes deeper than the limit obtained so far would allow one to approach this objective
Supernova remnants' interactions with the inter-stellar medium
No full textAll-sky data at a number of different wavelengths are used to examine the Giant Radio Loops. The x-ray emission of Loop I is modelled as being due to a Supernova Remnant (SNR) that has evolved in a hot, homogeneous, quasi-isotropic medium. The shock is found to weaken towards higher latitudes, and this is attributed to an increase in the ambient gas temperature away from the galactic plane. Other evolutionary possibilities are examined. Radio spectral index maps from 38 to 1420MHz of the northern celestial hemisphere are produced, and the spectra of loops I and III are modelled on the assumption that the energy distribution of electrons accelerated in the shocks will have an upper energy cut-off due to the finite age of the remnants. It is found that the steepening spectra can be fitted by such a model. The electron distribution below the cut-off of order l0GeV is found to fit best if a flatter spectrum than predicted by simple shock theory is assumed. The idea that shocks. Interacting with clouds can explain this flatter spectrum and enhance the soft x-ray emission is put forward as an alternative evolutionary possibility, bringing together the two separate x-ray and radio emission mechanisms. Other galactic SNR are examined to support this idea, including a newly discovered SNR that exists inside the error circle of the COS-B source 2CG342-02. Although this remnant’s association with the γ-ray source cannot be excluded, no firm evidence is found to identify it as the source
The K-band intensity profile of R Leonis probed by VLTI/VINCI
No full textWe present near-infrared K-band interferometric measurements of the Mira star R Leonis obtained in April 2001 and January 2002 with the VLTI, the commissioning instrument VINCI, and the two test siderostats. These epochs correspond to near-maximum stellar variability phases ∼0.08 and ∼1.02 (one cycle later), respectively. The April 2001 data cover a range of spatial frequencies (31–35 cycles/arcsecond) within the first lobe of the visibility function. These measurements indicate a center-to-limb intensity variation (CLV) that is clearly different from a uniform disk (UD) intensity profile. We show that these measured visibility values are consistent with predictions from recent self-excited dynamic Mira model atmospheres that include molecular shells close to continuum-forming layers. We derive high-precision Rosseland diameters of 28.5±0.4masand 26.2±0.8 mas for the April 2001 and January 2002 data, respectively. Together with literature estimates of the distance and the bolometric flux, these values correspond to linear radii of 350+50−40 R_☉ and 320+50−40 R_☉, and to effective temperatures of 2930±270 K and 3080±310 K, respectively
On the Age of the Globular Cluster M4
No full textVery deep images of the Galactic globular cluster M4 through the F606W and F814W filters were taken in 2001 with the WFPC2 on board the HST. A first published analysis of this data set produced the result that the age of M4 is 12.7+/-0.7 Gyr thus setting a robust lower limit to the age of the universe. In view of the great astronomical importance of getting this number right we have subjected the same data set to the simplest possible photometric analysis that avoids uncertain assumptions about the origin of the detected sources. This analysis reveals both a thin main sequence and a white dwarf (WD) sequence extending all the way down to the 5 sigma detection limit at I~27. The WD sequence is abruptly terminated at exactly this limit as expected by detection statistics. Using our theoretical WD models to obtain the expected WD sequence for different ages in the observed bandpasses we find that these data allow one only to set a lower limit to the age of M4 of ~9 Gyr. Thus the problem of determining the absolute age of a globular cluster and therefore the onset of GC formation with cosmologically significant accuracy remains completely open
Unilateral sacroiliitis associated with systemic isotretinoin treatment
No full textAcne fulminans is the most severe form of inflammatory acne characterized by the acute onset of inflammatory nodules and plaques, most commonly on the chest and the back. The lesions undergo rapid suppuration, leaving ragged hemorrhagic ulcers. Typically, it affects adolescent males with a history of mild to moderate acne. The affected patients often have constitutional symptoms such as fever, malaise, arthralgias, and myalgias. Leukocytosis is commonly associated. Sacroiliitis is reported in 21% of acne fulminans patients in association with arthritis and in a few cases it is reported during isotretinoin treatment, suggesting the drug triggering. CONCLUSION: We report a case of a young male patient in whom the induction of acne fulminans by systemic isotretinoin was associated with unilateral sacroiliitis
Instrument Science Report
No full textThe algorithms and software used in the derivation of the results presented in the Instrument Science Report FOC-060 are described in greater detail. In particular, the details of the image preparation, nonlinear least squares fitting, and spline interpolation are described as well as the program listings included. DISTRIBUTION: TIB: D.A. Baxter, P. Greenfield, W. Hack SCARS: P. Hodge SPD: R. Jedrzejewski, F. Paresce 2 1. Introduction This Report will describe in more detail the algorithms and programs used to analyze the Orion Nebula UV flat field data, the results of which were described in Instrument Science Report FOC060. Ideally, this report would describe these in such detail and clarity that any reader would easily understand what I am talking about and would have no problem in running the software or writing new software to duplicate what I have done. Unfortunately time does not permit that. I hope to include enough information so that with sufficient effort, someone could..
Treatment of active rheumatoid arthritis (RA) with combination therapy by adding leflunomide (LEF) in patients with an inadeguate response to methotrexate (mtx)
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