We present preliminary results of follow-up optical observations, both photometric and spectroscopic, of stellar X-ray sources, selected from the cross-correlation of ROSAT All-Sky Survey (RASS) and TYCHO catalogues. Spectra were acquired with the Elodie spectrograph at the 193-cm telescope of the Haute Provence Observatory (OHP) and with the REOSC echelle spectrograph at the 91-cm telescope of...

Using phase resolved spectroscopic observations obtained with the Ultraviolet and Visual Echelle Spectrograph on ESO’s Kueyen Very Large Telescope supplemented by spectroscopic observations obtained with the Boller and Chivens Spectrograph on the Walter Baade Magellan telescope, we found sinusoidal radial–velocity variations with a semi–amplitude 327±17 km/s. From previous observations and from...

the internal structure of dna-ctab and dna-ddab is investigated by a small angel x- ray scattering(saxs) instrument. hexagonal packing of dna was observed for dna complex with ctab, and for ddabcomplex is observed lamellar structure. variations in the internal spacing and degree of long-range ordering aredependent on both surfactant type and concentrations of added salt. when we increased the a...

The Near Infrared Spectrograph (NIRSpec) for the James Webb Space Telescope (JWST) is a multi-object spectrograph operating in the 0.6-5.0 μm spectral range. One of the primary scientific objectives of this instrument is to measure the number and density evolution of galaxies following the epoch of initial formation. NIRSpec is designed to allow simultaneous observation of a large number of sou...

Using phase-resolved spectroscopic observations obtained with the Ultraviolet and Visual Echelle Spectrograph on the ESO Kueyen Very Large Telescope, supplemented by spectroscopic observations obtained with the Boller and Chivens spectrograph on the Walter Baade Magellan Telescope, we have found sinusoidal radial velocity variations with a semi-amplitude of 327 ± 17 km s−1. From previous observ...

  Background: The sporadic cases of radiation-activated multiple sclerosis (MS) has been previously described, with a few studies focused on the relationship between radiation and the risk of MS. The aim of our study was to evaluate the association between history of X-ray radiation and MS.   Methods : This case-control study was conducted on 150 individuals including 65 MS patients and 85 age-...

introduction: clinical application of radiography in endodontic practice is affected by reproducibility in the orientation of the x-ray source, image receptor and object. the inability of dentists to locate intra oral films or sensors in appropriate positions in different cases can cause complications in the performance of endodontic therapy. commercially available film holder (endoray) and con...